WO2016013260A1

WO2016013260A1 - Polarizing plate, method for producing polarizing plate, and liquid crystal display device

Info

Publication number: WO2016013260A1
Application number: PCT/JP2015/061600
Authority: WO
Inventors: 矢野　健太郎
Original assignee: コニカミノルタ株式会社
Priority date: 2014-07-25
Filing date: 2015-04-15
Publication date: 2016-01-28
Also published as: JPWO2016013260A1

Abstract

This polarizing plate (5) comprises a polarizer (11) and an optical film (12) serving as a protective film that protects the polarizer (11). The polarizer (11) is formed of a film having a thickness of 15 μm or less and containing a polyvinyl alcohol. The optical film (12) comprises a base (21), which is formed of a cellulose ester, and at least one coating layer (22) in this order from the polarizer (11) side. The base (21) and the polarizer (11) are adjacent to each other. The base (21) has a thickness of 80 μm or less. The coating layer (22) has a water vapor permeability of more than 1 g/m²/day. The optical film (12) as a whole has a water vapor permeability of less than 300 g/m²/day.

Description

Polarizing plate, manufacturing method of polarizing plate, and liquid crystal display device

The present invention relates to a polarizing plate having a protective film on a polarizer, a method for producing the polarizing field, and a liquid crystal display device including the polarizing plate.

Liquid crystal display devices are becoming thinner and lighter. In particular, medium- and small-sized liquid crystal display devices have been reduced in weight, and can be carried to various places. For this reason, for example, the form which uses a medium-sized liquid crystal display device in high-temperature, high-humidity environment like a bathroom is increasing. Under such a high-temperature and high-humidity environment, the durability of the polarizing plate and the display unevenness of the display device resulting from it become a problem.

Generally, a polarizing plate is configured by sandwiching a polarizer made of polyvinyl alcohol (PVA) from both sides with a protective film. As the protective film, a cellulose ester film having excellent optical isotropy and transparency and excellent adhesion to PVA, particularly a triacetyl cellulose film (TAC film) has been widely used.

The polarizer is made by dyeing iodine on a PVA film, and it is known that iodine is decolorized from the PVA film due to moisture in particular and deteriorates. In addition, the PVA film constituting the polarizer is stretched at a very high magnification in order to orient the dyed iodine. In a high temperature and high humidity environment, the PVA film shrinks by containing moisture, and the polarizing plate Causes warping and distortion.

Since the cellulose ester film used as a protective film has very high moisture permeability and hygroscopicity, there has been a problem that the polarizer is likely to deteriorate as described above due to moisture that passes through the protective film.

On the other hand, for example,

Patent Document

1 or 2 discloses a technique in which the protective film is made of a low moisture-permeable material such as a polyester-based resin film or a norbornene-based resin film. By using such a low moisture-permeable material, it is considered that moisture can be prevented from entering from the outside in the protective film and deterioration of the polarizer due to moisture can be suppressed.

Japanese Patent Laying-Open No. 2012-202111 (see claim 1, paragraphs [0004], [0005], etc.) JP 2008-102475 A (see claims 1 and 7, paragraphs [0008] and [0023], etc.)

However, in recent years, the weight of each member has been increasingly reduced, and it has been found that the above technique cannot be applied particularly when the polarizer becomes a thin film (for example, a film thickness of 15 μm or less). In other words, even if the protective film is made of a material with low moisture permeability, when the polarizer is a thin film, the polarizer is deteriorated under high temperature conditions, and it is impossible to prevent discoloration of the display portion and contrast reduction. I understand.

As a result of intensive studies by the inventor of the present application, it was found that the above-described polarizer deterioration is caused by moisture contained in PVA which is the base of the polarizer. That is, by protecting the polarizer with a low moisture-permeable film, moisture can be prevented from entering from the outside. However, under high temperature conditions, it is contained in PVA, regardless of the external humidity conditions. It is considered that the polarizer has deteriorated due to moisture losing its escape and the moisture decolorizing iodine. Therefore, when the polarizer is a thin film, it is desired to suppress the deterioration of the polarizer due to the moisture of the polarizer itself under high temperature conditions.

In addition, the idea of solving the above problem can be achieved by reducing the amount of water contained in the polarizer. However, if the amount of water contained in the polarizer is too small, the film quality may deteriorate or the adhesion to the protective film may deteriorate, which may adversely affect productivity. It is not preferable.

The present invention has been made in order to solve the above-described problem. The object of the present invention is to provide a polarizer under high temperature conditions without reducing the amount of water contained in the polarizer even when the polarizer is a thin film. It is providing the polarizing plate which can suppress deterioration of this, its manufacturing method, and a liquid crystal display device provided with the polarizing plate.

The above object of the present invention is achieved by the following configuration.

A polarizing plate according to one aspect of the present invention is a polarizing plate having a polarizer and a protective film for protecting the polarizer,
The polarizer is made of a film containing polyvinyl alcohol having a film thickness of 15 μm or less,
The protective film has a base material made of cellulose ester and at least one coating layer in this order from the polarizer side,
The substrate and the polarizer are adjacent to each other,
The substrate has a thickness of 80 μm or less,
The moisture permeability of the coating layer is greater than 1 g / m ² / day,
The moisture permeability of the entire protective film is smaller than 300 g / m ² / day.

According to the above configuration, even when the polarizer is a thin film having a film thickness of 15 μm or less, by defining the moisture permeability of the protective film coating layer and the entire protective film as described above, moisture from the outside is applied by the coating layer. While making it difficult to pass through to the polarizer side, moisture contained in the polarizer can be transmitted (moisture permeable) through a base material made of cellulose ester under high temperature conditions and escape to the outside through the coating layer. As a result, even when the polarizer is a thin film, deterioration of the polarizer under high temperature conditions can be suppressed without reducing the amount of water contained in the polarizer.

1 is a cross-sectional view illustrating a schematic configuration of a liquid crystal display device according to an embodiment of the present invention. It is sectional drawing which shows an example of the manufacturing process of the polarizing plate of the said liquid crystal display device.

An embodiment of the present invention will be described below with reference to the drawings. In this specification, when the numerical range is expressed as A to B, the numerical value range includes the values of the lower limit A and the upper limit B. The present invention is not limited to the following contents.

[Outline of polarizing plate]
First, the outline | summary of the polarizing plate of this embodiment is demonstrated. Generally, a polarizer of a polarizing plate is made by dyeing a polyvinyl alcohol (PVA) film with iodine, and has a dyed area on the film surface side and a non-dyed area on the film inner side. Conceivable. When a thin film polarizer is manufactured by a general known manufacturing method, the thickness of the dyed region does not change unless the dyeing method is changed, and only the non-stained region is thinned. By reducing the thickness of the non-stained region, moisture enters from outside to the dyed region on the surface side, and the polarizer is severely deteriorated. By using a low moisture-permeable film as a protective film for the polarizer, it is possible to prevent moisture from entering from the outside, but this time the moisture contained in the PVA of the polarizer loses its escape and becomes a dyeing area. Adversely affect.

Therefore, in the present embodiment, the polarizing plate is configured as follows. That is, the polarizing plate of this embodiment has a polarizer and a protective film that protects the polarizer. The polarizer is made of a film containing PVA having a film thickness of 15 μm or less. The protective film has a base material made of cellulose ester and at least one coating layer in this order from the polarizer side. The base material and the polarizer are adjacent to each other. The base material has a thickness of 80 μm or less. The moisture permeability of the coating layer is larger than 1 g / m ² / day, and the moisture permeability of the entire protective film is smaller than 300 g / m ² / day. Here, the moisture permeability is determined as a value of moisture permeability (g / m ² / day) for 24 hours per 1 m ² under the condition of 40 ° C. and 90% RH by the method described in JIS Z 0208. . Among these, in particular, it is desirable that the film thickness of the protective film is 30 μm or less, and the moisture permeability of the coating layer included in the protective film is larger than 50 g / m ² / day.

Since the protective film has a base material made of a cellulose ester film and a low moisture-permeable coating layer in this order from the polarizer side, entry of moisture from the outside is prevented by the low moisture-permeable coating layer. And deterioration of the polarizer due to the moisture can be suppressed. In addition, by providing a substrate composed of a cellulose ester film between the low moisture-permeable coating layer and the polarizer, and by defining the moisture permeability of the coating layer and the entire protective film as described above, under high temperature conditions, An effect like a buffer material that absorbs moisture contained in the PVA of the polarizer is born, and the moisture can be transmitted through the substrate and escaped to the outside through the coating layer. As a result, even when the polarizer is a thin film, it is considered that deterioration of the polarizer under high temperature conditions can be suppressed without reducing the amount of moisture originally contained in the polarizer.

At this time, the use of a cellulose ester film is not very effective, and the low moisture-permeable portion (coating layer) prevents moisture from entering from the outside to some extent, and further allows internal moisture to escape to the outside. Thus, it is considered that the polarizer deterioration can be effectively suppressed. Thus, the durability of the polarizing plate can be improved by suppressing the deterioration of the polarizer.

In particular, a polarizer made of polyethylene terephthalate (PET), which is a film different from the above cellulose ester film as a substrate, and is formed by applying PVA to the substrate to form a film (coating polarizer). Then, it is common to dye | stain in the state which laminated | stacked PVA on the board | substrate, and only the one side (opposite side of a board | substrate) of PVA is dye | stained. That is, the dyed region exists only on one side of the PVA. Therefore, when this dyeing | staining area | region deteriorates with a water | moisture content, the function as a polarizer will be impaired. On the other hand, in a normal polarizer other than a coating type polarizer, both sides of the polarizer are dyed, and the dyed areas are present on both sides of the PVA, so even if either one of the dyed areas deteriorates due to moisture, If the remaining dyed area is not deteriorated, the function as a polarizer can be exhibited. Therefore, it can be said that a coating-type polarizer having a smaller number of dyed regions than a normal polarizer is more likely to deteriorate than a normal polarizer.

In addition, when using a coating type polarizer, from the viewpoint of productivity and the like, a new film is directly bonded to the PVA-dyed surface in a state where the substrate and the PVA are laminated. Therefore, if this new film has low moisture permeability, there is no escape space for moisture contained in PVA under high temperature conditions, so that the dyeing area of PVA tends to deteriorate and is used in a state where it is more susceptible to adverse effects. .

From the above viewpoint, the above-described configuration capable of suppressing the deterioration of the polarizer is very effective particularly when a coating type polarizer is used.

In addition, the cellulose ester used as the base material of the protective film has high moisture permeability, and even if an additive as described later is added, the film has a film thickness of 80 μm and has a moisture permeability of 300 g / m ² / day or more. A film having a thickness of 30 μm has a water vapor transmission rate of 800 g / m ² / day or more (a cellulose ester monolayer film having a film thickness of 80 μm or less and a water vapor transmission rate of less than 300 g / m ² / day cannot be produced by a known technique. Is). For this reason, in the structure whose film thickness of the base material which consists of cellulose ester is 80 micrometers or less (in the structure whose water vapor transmission rate of a base material is 300 g / m < ² > / day or more), the water vapor transmission rate of the whole protective film is 300 g / m < ² > /. In order to make it smaller than day, it is necessary to make the moisture permeability of the coating layer lower than a predetermined value. The predetermined value (upper limit value of moisture permeability of the coating layer) can be derived as follows.

Generally, when the film C is formed by laminating the first layer A and the second layer B, the moisture permeability of the entire film C is x (g / m ² / day), and the first layer When the moisture permeability of A is y (g / m ² / day) and the moisture permeability of the second layer B is z (g / m ² / day), the relationship 1 / x = 1 / y + 1 / z is satisfied. It is known to hold. When this is applied to the protective film, the moisture permeability of the entire protective film is x (g / m ² / day), the moisture permeability of the substrate is y (g / m ² / day), and the moisture permeability of the coating layer is z. In the case of (g / m ² / day), the relationship 1 / x = 1 / y + 1 / z is established. By using this formula, when the moisture permeability of the protective film is to be set to a constant value, a guide for how much the moisture permeability should be provided for a specific moisture permeability substrate is derived. be able to. That is, the upper limit value of the moisture permeability of the coating layer can vary depending on the moisture permeability (target value) of the entire protective film and the moisture permeability (type and thickness of the substrate) of the substrate to be used.

Hereinafter, the display device of this embodiment will be described.

[Configuration of display device]
FIG. 1 is a cross-sectional view showing a schematic configuration of a liquid crystal display device 1 as a display device of the present embodiment. The liquid crystal display device 1 includes a liquid crystal display panel 2 and a backlight 3. The backlight 3 is a light source for illuminating the liquid crystal display panel 2.

The liquid crystal display panel 2 is configured by disposing

polarizing plates

5 and 6 on both sides of a liquid crystal cell 4 (display cell) in which a liquid crystal layer is sandwiched between a pair of substrates. The polarizing plate 5 is attached to one surface side of the liquid crystal cell 4 (viewing side opposite to the liquid crystal cell 4) with the adhesive layer 7 interposed therebetween. The polarizing plate 6 is attached to the other surface side of the liquid crystal cell 4 (backlight 3 side opposite to the liquid crystal cell 4) via the adhesive layer 8. The driving method of the liquid crystal display panel 2 is not particularly limited, and various driving methods such as an IPS (In Plane Switching) type and a TN (Twisted Nematic) method can be employed.

The polarizing plate 5 includes a polarizer 11 that transmits predetermined linearly polarized light, an optical film 12 as a protective film disposed on the viewing side (front side) of the polarizer 11, and the backlight 3 side (back side) of the polarizer 11. And an optical film 13 disposed on the side). Note that the optical film 13 on the back side may be omitted, and the polarizer 11 may be in direct contact with the adhesive layer 7. The polarizing plate 6 includes a polarizer 14 that transmits predetermined linearly polarized light, an optical film 15 that is disposed on the viewing side of the polarizer 14, and an optical film 16 that is disposed on the backlight 3 side of the polarizer 14. Has been. The optical film 15 may be omitted, and the polarizer 14 may be directly in contact with the adhesive layer 8. The polarizer 11 and the polarizer 14 are arranged so as to be in a crossed Nicols state. As the polarizing plate 6 on the backlight 3 side, a conventionally known one can be used. Hereinafter, the polarizing plate 5 on the viewing side will be described.

The polarizer 11 of the polarizing plate 5 is formed by dyeing a PVA film having a thickness of 15 μm or less with iodine. The optical film 12 has a film substrate 21 and a coating layer 22 composed of at least one layer laminated on the viewing side of the film substrate 21.

The film substrate 21 is a transparent substrate made of cellulose esthetic. The thickness of the film substrate 21 is 80 μm or less. The moisture permeability of the film substrate 21 is approximately 350 to 400 g / m ² / day at a thickness of 80 μm and approximately 500 g / m ² / day at a thickness of 60 μm when the film substrate 21 includes a plasticizer described later. is there.

The moisture permeability of the coating layer 22 is greater than 1 g / m ² / day. This is because the coating layer 22 has a function of preventing moisture from entering from the outside and releasing the moisture of the polarizer 11 that has passed through the film substrate 21 to the outside. That is, the coating layer 22 has a barrier property that suppresses moisture permeation to some extent, and does not have a high barrier property that completely prevents moisture permeation. The moisture permeability of a film having a high barrier property is generally much smaller (2 to 3 digits) than 1 g / m ² / day.

Here, if the entire moisture permeability of the optical film 12 is too high, the coating layer 22 cannot suppress the intrusion of moisture from the outside. Therefore, the moisture permeability of the entire optical film 12 is 300 g / m ² / day. It is necessary to make it smaller. Therefore, when the moisture permeability of the film substrate 12 is taken into consideration, the upper limit of the moisture permeability of the coating layer 22 is naturally limited by the above-described relational expression.

Thus, even when the polarizer 11 is a thin film having a film thickness of 15 μm or less, the moisture content from the outside is covered by defining the moisture permeability of the coating layer 22 of the optical film 12 and the entire optical film 12 as described above. 22 makes it difficult to pass through to the polarizer 11 side, but allows moisture contained in the polarizer 11 to pass through the film base material 21 made of cellulose ester under high temperature conditions and to escape to the outside through the coating layer 22. be able to. As a result, even when the polarizer 11 is a thin film, deterioration of the polarizer 11 under a high temperature condition can be suppressed without reducing the amount of moisture contained in the polarizer 11, and the durability of the polarizing plate 5 can be improved. Can be improved.

The moisture permeability of the coating layer 22 is greater than 10 g / m ² / day, and the film thickness of the optical film 12 may be 30 μm or less. When the film thickness of the optical film 12 is 30 μm or less, the film base 21 is thinned, and the moisture permeability is further increased. That is, the film base material 21 becomes easier to transmit moisture of the polarizer 11. In this case, when the moisture permeability of the coating layer 22 is larger than 10 g / m ² / day, moisture from the polarizer 11 that has passed through the film base material 21 is efficiently released to the outside through the coating layer 22. Can do. Therefore, even if the film substrate 21 and thus the polarizing plate 5 are further thinned, deterioration of the polarizer 11 under high temperature conditions can be suppressed.

The moisture permeability of the coating layer 22 is greater than 50 g / m ² / day, and the coating layer 22 may contain a binder component and a layered inorganic compound. Since the moisture permeability of the coating layer 22 is larger than 50 g / m ² / day, the moisture from the polarizer 11 that has passed through the film substrate 21 is efficiently released to the outside through the coating layer 22. By including the binder component (for example, resin) and the layered inorganic compound in the layer 22, it is possible to ensure that the coating layer 22 has a barrier property that reduces intrusion of moisture from the outside.

The film substrate 21 may contain a polarizer durability improving agent. In this case, combined with the effect of suppressing the deterioration of the polarizer 11 under a high temperature condition obtained from the above-described configuration, the durability of the polarizer 11 can be reliably improved.

As the polarizer durability improver, a compound represented by the following general formula (1) can be used.

In general formula (1), R ¹ represents a substituent, R ² represents a group represented by the following general formula (1-2), n1 represents an integer of 0 to 4, and when n1 is 2 or more The plurality of R ¹ may be the same or different from each other, n2 represents an integer of 1 to 5, and when n2 is 2 or more, the plurality of R ² may be the same or different from each other Good.

In general formula (1-2), A represents a substituted or unsubstituted aromatic ring, and R ³ and R ⁴ each independently represent a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or the following general formula Represents a group represented by (1-3), R ⁵ represents a single bond or an alkylene group having 1 to 5 carbon atoms, X represents a substituted or unsubstituted aromatic ring, and n3 represents 0 to Represents an integer of 10, and when n3 is 2 or more, the plurality of R ⁵ and X may be the same or different from each other.

In the general formula (1-3), X ₁ represents a substituted or unsubstituted aromatic ring, and R ⁶ , R ⁷ , R ⁸ , and R ⁹ are each independently a hydrogen atom or a carbon number of 1 to 5 N5 represents an integer of 1 to 11, and when n5 is 2 or more, a plurality of R ⁶ , R ⁷ , R ⁸ , R ⁹ and X ₁ may be the same or different from each other Good.

In addition, as the polarizer durability improver, a compound represented by the following general formula (2) can also be used.

In the general formula (2), R ²⁶ represents an alkyl group, an alkenyl group, or an aryl group, R ²⁷ and R ²⁸ each independently represent a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, or a heteroaryl group, and R ²⁹ represents a hydrogen atom. R ²⁶ , R ²⁷ , and R ²⁸ may each independently have a substituent. However, at least one of R ²⁶ , R ²⁷ and R ²⁸ contains an aromatic ring.

Moreover, said film base material 21 which consists of cellulose esters may contain the specific polymer represented by following General formula (3). By including such a specific polymer, deterioration of the polarizer 11 can be suppressed and its durability can be improved.

In the general formula (3), R ²¹ , R ²² , R ²³ , and R ²⁴ each independently represent a substituent. x represents 0 to 40 in molar ratio. y represents a molar ratio of 5 to 95. z represents a molar ratio of 0 to 70. m1 and m2 each represents an integer of 0 to 4. m3 represents an integer of 0-2. m4 represents an integer of 0 to 5. R ¹⁰¹ , R ¹⁰² and R ¹⁰³ represent a hydrogen atom or an aliphatic group having 1 to 4 carbon atoms.

As described above, the polarizing plate 5 has another optical film 13 (a protective film on the back side) on the side opposite to the optical film 12 with respect to the polarizer 11. The optical film 13 may be a cellulose ester film. In this case, in the configuration in which the polarizer 11 is sandwiched between the cellulose ester films from both sides, the above-described effects can be obtained.

Desirably, the optical film 13 has a thickness of 25 μm or less. Even when the optical film 13 is provided on the back side of the polarizer 11, the optical film 13 is a thin film having a thickness of 25 μm or less, which can contribute to the thinning of the entire polarizing plate 5.

Desirably, the coating layer 22 of the polarizing plate 5 contains fine particles formed by coating with a polymer silane coupling agent. In this case, the surface free energy of the coating layer 22 is increased and wettability is improved, and even when another layer (for example, a hard coat layer) is laminated on the coating layer 22, the adhesion between both layers is sufficiently increased. Can be secured.

In the optical film 12 of the polarizing plate 5, the in-plane retardation Ro represented by the following formula may be 30 nm or more.
Ro = (nx−ny) × t
However, nx represents the refractive index in the slow axis direction in which the refractive index is maximum in the in-plane direction of the optical film 12, and ny is in the direction orthogonal to the slow axis direction in the in-plane direction of the optical film 12. The refractive index is represented, and t (nm) represents the thickness of the optical film 12.

In this case, the optical film 12 can have a function as a retardation film (for example, a λ / 4 film). Therefore, the linearly polarized light emitted from the polarizer 11 is converted into circularly polarized light or elliptically polarized light by the optical film 12. For this reason, when the observer wears polarized sunglasses and observes the display image of the liquid crystal display device 1, how the transmission axis of the polarizer 11 (perpendicular to the absorption axis) and the transmission axis of the polarized sunglasses deviate. Even in this case, the light component parallel to the transmission axis of the polarized sunglasses contained in the light emitted from the polarizing plate 5 (circularly polarized light or elliptically polarized light) can be guided to the eyes of the observer. Thereby, it can suppress that it becomes difficult to see a display image with the angle to observe. In addition, even when the observer does not wear polarized sunglasses, since it is circularly polarized light or elliptically polarized light that is emitted from the polarizing plate 5 and incident on the observer's eyes, linearly polarized light is directly incident on the observer's eyes. Compared to the above, the burden on the eyes of the observer can be reduced.

The polarizer 11 of the polarizing plate 5 may be a coating type polarizer. The coating type polarizer is a polarizer formed by applying a PVA film on a substrate and stretching the whole substrate. The polarizing plate 5 using such a coating type polarizer is manufactured as follows.

FIG. 2 is a cross-sectional view showing the manufacturing process of the polarizing plate 5. First, a film (for example, PET film) different from the optical film 12 is used as the substrate 31, and a film containing PVA is applied on the substrate 31. And a PVA film is laminated | stacked on the board | substrate 31, a laminated body is formed, this laminated body is extended | stretched, the stretched PVA film is dye | stained, and the polarizer 11 is formed. Then, the surface of the polarizer 11 opposite to the substrate 31 is bonded to the film base 21 of the optical film 12. The substrate 31 may be removed (peeled) after the polarizer 11 is bonded to the film base material 21 or may be left as it is.

As described above, the coating-type polarizer is dyed only on one side of PVA (on the side opposite to the substrate 31) and is more easily deteriorated than a normal polarizer in which both sides of PVA are dyed. Therefore, the above-described configuration capable of suppressing the deterioration of the polarizer 11 is very effective particularly when a coating type polarizer is used as the polarizer 11.

Hereinafter, details of the polarizing plate 5 will be described.

〔Base material〕
Cellulose ester resins that can be used for the substrate (film substrate 21) of this embodiment are cellulose (di, tri) acetate, cellulose propionate, cellulose butyrate, cellulose acetate propionate, cellulose acetate butyrate, It is preferably at least one selected from cellulose acetate phthalate and cellulose phthalate.

Among these, particularly preferred cellulose esters include cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate propionate, and cellulose acetate butyrate.

More preferable cellulose acetate propionate or lower acetate of cellulose acetate butyrate as a mixed fatty acid ester has an acyl group having 2 to 4 carbon atoms as a substituent, the substitution degree of acetyl group is X, and a propionyl group Or when the substitution degree of a butyryl group is set to Y, it is preferable that it is a cellulose resin containing the cellulose ester which satisfy | fills following formula (I) and (II) simultaneously.
Formula (I) 2.6 ≦ X + Y ≦ 3.0
Formula (II) 1.0 ≦ X ≦ 2.5

Of these, cellulose acetate propionate is particularly preferably used. Among them, 1.9 ≦ X ≦ 2.5 and 0.1 ≦ Y ≦ 0.9 are preferable. A hydroxyl group is usually present in the portion not substituted with the acyl group. These can be synthesized by known methods.

Furthermore, as the cellulose ester used in the present embodiment, those having a weight average molecular weight (Mw) to number average molecular weight (Mn) ratio (Mw / Mn) of 1.5 to 5.5 are preferably used. A cellulose ester having a ratio of 2.0 to 5.0 is more preferably used, a cellulose ester having a ratio of 2.5 to 5.0 is more preferably used, and the ratio is 3.0 to 5. A cellulose ester of 0 is particularly preferably used.

The cellulose that is the raw material of the cellulose ester used in the present embodiment may be wood pulp or cotton linter. The wood pulp may be coniferous or hardwood, but coniferous is more preferred. A cotton linter is preferably used from the viewpoint of releasability during film formation. The cellulose ester made from these can be mixed suitably or can be used independently.

For example, the ratio of cellulose ester derived from cellulose linter: cellulose ester derived from wood pulp (conifer): cellulose ester derived from wood pulp (hardwood) is set to 100: 0: 0, 90: 10: 0, 85: 15: 0, 50:50. : 0, 20: 80: 0, 10: 90: 0, 0: 100: 0, 0: 0: 100, 80:10:10, 85: 0: 15, or 40:30:30 .

In this embodiment, the cellulose ester resin has a pH of 1 g when charged in 20 ml of pure water (electric conductivity of 0.1 μS / cm or less, pH 6.8) and stirred in a nitrogen atmosphere at 25 ° C. for 1 hr. Preferably, the electrical conductivity is 6 to 7 and the electrical conductivity is 1 to 100 μS / cm.

When using the cellulose ester resin as a film, polymer components other than the cellulose ester may be appropriately mixed. The polymer component to be mixed is preferably one having excellent compatibility with the cellulose ester. The transmittance when formed into a film is preferably 80% or more, more preferably 90% or more, and further preferably 92% or more.

<Polarizer durability improver>
(Compound represented by the general formula (1))
In this embodiment, it is preferable that the polarizer durability improving agent is contained in the cellulose-ester film used as a base material of a protective film. Here, the polarizer durability improving agent refers to a material that prevents the polarization degree of the polarizer from deteriorating under high temperature and high humidity conditions. In particular, a compound represented by the following general formula (1) is preferable as the polarizer durability improving agent.

In general formula (1), R ¹ represents a substituent. Examples of the substituent are not particularly limited, and may be an alkyl group (preferably an alkyl group having 1 to 10 carbon atoms such as methyl, ethyl, isopropyl, t-butyl, pentyl, heptyl, 1-ethylpentyl, benzyl, 2 -Ethoxyethyl, 1-carboxymethyl, etc.), alkenyl groups (preferably alkenyl groups having 2 to 20 carbon atoms, such as vinyl, allyl, oleyl, etc.), alkynyl groups (preferably alkynyl groups having 2 to 20 carbon atoms) For example, ethynyl, butadiynyl, phenylethynyl, etc.), a cycloalkyl group (preferably a cycloalkyl group having 3 to 20 carbon atoms, eg, cyclopropyl, cyclopentyl, cyclohexyl, 4-methylcyclohexyl, etc.), an aryl group (preferably Aryl groups having 6 to 26 carbon atoms, such as phenyl, -Naphthyl, 4-methoxyphenyl, 2-chlorophenyl, 3-methylphenyl and the like), a heterocyclic group (preferably a heterocyclic group having 2 to 20 carbon atoms, such as 2-pyridyl, 4-pyridyl, 2-imidazolyl, 2-benzimidazolyl, 2-thiazolyl, 2-oxazolyl, etc.), an alkoxy group (preferably an alkoxy group having 1 to 20 carbon atoms, such as methoxy, ethoxy, isopropyloxy, benzyloxy, etc.), an aryloxy group (preferably carbon Aryloxy groups having 6 to 26 atoms, such as phenoxy, 1-naphthyloxy, 3-methylphenoxy, 4-methoxyphenoxy, etc., alkoxycarbonyl groups (preferably alkoxycarbonyl groups having 2 to 20 carbon atoms, such as Ethoxycarbonyl, 2-ethylhexyloxycar Nyl, etc.), an amino group (preferably an amino group having 0 to 20 carbon atoms, such as amino, N, N-dimethylamino, N, N-diethylamino, N-ethylamino, anilino, etc.), a sulfonamide group (preferably Is a sulfonamide group having 0 to 20 carbon atoms, such as N, N-dimethylsulfonamide, N-phenylsulfonamide, etc., an acyloxy group (preferably an acyloxy group having 1 to 20 carbon atoms, such as acetyloxy, Benzoyloxy and the like), a carbamoyl group (preferably a carbamoyl group having 1 to 20 carbon atoms, such as N, N-dimethylcarbamoyl, N-phenylcarbamoyl, etc.), an acylamino group (preferably an acylamino group having 1 to 20 carbon atoms) For example, acetylamino, benzoylamino, etc.), cyano group, or halogen atom (For example, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc.) and a hydroxyl group are mentioned.

R ¹ is preferably an alkyl group having 1 to 20 carbon atoms or a hydroxyl group, and more preferably a hydroxyl group or a methyl group. R ¹ may have one or more substituents as substituents. R ¹ may further have one or more substituents, and examples of the further substituents include the same substituents as R ¹ .

N1 represents an integer of 0 to 4, and preferably 2 to 4.

N2 represents an integer of 1 to 5, preferably 1 to 3, and more preferably 1 to 2.

In general formula (1-2), A represents a substituted or unsubstituted aromatic ring. The aromatic ring may be a heterocyclic ring containing a hetero atom such as a nitrogen atom, an oxygen atom, or a sulfur atom. Examples of A include benzene ring, indene ring, naphthalene ring, fluorene ring, phenanthrene ring, anthracene ring, biphenyl ring, pyrene ring, pyran ring, dioxane ring, dithiane ring, thiyne ring, pyridine ring, piperidine ring, oxazine ring Morpholine ring, thiazine ring, pyridazine ring, pyrimidine ring, pyrazine ring, piperazine ring, triazine ring and the like. Further, other 6-membered rings or 5-membered rings may be condensed. A is preferably a benzene ring.

Examples of the substituent that A may have include a halogen atom (for example, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc.), an alkyl group, a hydroxyl group, etc., preferably an alkyl group or a hydroxyl group, An alkyl group or hydroxyl group having 1 to 10 carbon atoms is more preferable, and an alkyl group or hydroxyl group having 1 to 5 carbon atoms is still more preferable.

R ³ and R ⁴ each independently represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms and a substituent represented by the following general formula (1-3). R3 and R4 are preferably a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or a substituent represented by the general formula (1-3), represented by a hydrogen atom, a methyl group, or a general formula (1-3). The substituent is more preferable.

In general formula (1-2), R ⁵ represents a single bond or an alkylene group having 1 to 5 carbon atoms, and the alkylene group having 1 to 5 carbon atoms may have a substituent. R ⁵ is preferably an alkylene group having 1 to 4 carbon atoms, and more preferably an alkylene group having 1 to 3 carbon atoms. Examples of the substituent that R ⁵ may have include an alkyl group having 1 to 5 carbon atoms (for example, methyl, ethyl, isopropyl, t-butyl), a halogen atom (for example, a fluorine atom, a chlorine atom, a bromine atom, iodine) Atoms), hydroxyl groups and the like.

In general formula (1-2), X represents a substituted or unsubstituted aromatic ring. The aromatic ring may be a heterocyclic ring containing a hetero atom such as a nitrogen atom, an oxygen atom, or a sulfur atom. Examples of X include benzene ring, indene ring, naphthalene ring, fluorene ring, phenanthrene ring, anthracene ring, biphenyl ring, pyrene ring, pyran ring, dioxane ring, dithiane ring, thiyne ring, pyridine ring, piperidine ring, oxazine ring Morpholine ring, thiazine ring, pyridazine ring, pyrimidine ring, pyrazine ring, piperazine ring, triazine ring and the like. Further, other 6-membered rings or 5-membered rings may be condensed. X is preferably a benzene ring. Examples of the substituent which X may have are the same as the examples given as the substituent of A.

n3 represents an integer of 0 to 10, preferably 0 to 2, and more preferably 0 to 1. When n3 is an integer of 2 or more, a plurality of groups represented by — (R ⁵ —X) may be the same as or different from each other, and each bond to A. When n3 is 0, a group represented by-(R ⁵ -X) does not exist, and therefore a group represented by-(R ⁵ -X) is not bonded to A.

The general formula (1-2) is preferably represented by the following general formula (1-2 ').

In the general formula (1-2 ′), R ³ represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a substituent represented by the general formula (1-3), and R ⁵ represents a single bond. Or an alkylene group having 1 to 5 carbon atoms, X represents a substituted or unsubstituted aromatic ring, n3 represents an integer of 0 to 5, and when n3 is 2 or more, a plurality of R ⁵ and X May be the same as or different from each other.

The preferred range of each symbol in the general formula (1-2 ') is the same as that in the general formula (1-2).

The general formula (1-2) is preferably represented by the following general formula (1-2 ″).

In the general formula (1-2 ″), n3 represents an integer of 0 to 5.

The preferable range of n3 in the general formula (1-2 ″) is the same as the preferable range of n3 in the general formula (1-2).

X1 in the general formula (1-3) has the same meaning as X in the general formula (1-2), and the preferred range is also the same.

In general formula (1-3), R ⁶ , R ⁷ , R ⁸ , and R ⁹ each independently represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. R ⁶ , R ⁷ , R ⁸ and R ⁹ are preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and more preferably a hydrogen atom or a methyl group.

N5 represents an integer of 1 to 11, preferably 1 to 9, and more preferably 1 to 7.

The general formula (1-3) is preferably represented by the following general formula (1-3 ′).

The definition of each symbol in the general formula (1-3 ′) is synonymous with that in the general formula (1-3), and the preferred range is also the same.

The general formula (1-3) is preferably represented by the following general formula (1-3 ″).

In the general formula (1-3 ″), n4 represents an integer of 0 to 10. n4 is preferably from 0 to 8, and more preferably from 0 to 6. *

In the compound represented by the general formula (1), R ¹ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, R ² is represented by the general formula (1-2 ″), and n1 is 2 to 4 It is preferable that n2 represents an integer of 1 to 3, and n3 represents an integer of 0 to 2.

Specific examples of the compound represented by the general formula (1) are shown below, but are not limited to the following specific examples.

In order to allow the compound represented by the general formula (1) having a different number of hydroxyl groups to be hydrogen-bonded at multiple points, at least 2 compounds represented by the general formula (1) which are different from each other are bonded. It is good also as a mixture containing a seed. One example is a styrenated phenol in which 1 to 3 moles of styrene are alkylated with respect to phenol, a styrenated phenol in which styrene is further alkylated at the phenyl moiety of the alkylated styrene, and an oligomer of about 2 to 4 monomers of styrene. Mention may be made of mixtures with styrenated phenols alkylated to phenol.

The compound represented by the general formula (1) can generally be synthesized by adding 1 equivalent or more of styrenes in the presence of an acid catalyst to 1 equivalent of phenols, and a commercially available product may be used. . Moreover, you may use the mixture obtained by the said synthesis method as it is.

Commercially available products of the compound represented by the general formula (1) include “TSP” which is a styrenated phenol manufactured by Sanko Co., Ltd., “PH-25” manufactured by Nikko Paint Chemical Co., Ltd., “ Non-flex WS "etc. are mentioned.

(Compound represented by the general formula (2))
As the polarizer durability improver, a compound represented by the following general formula (2) is also preferable.

In the general formula (2), R ²⁶ represents an alkyl group, an alkenyl group, or an aryl group, R ²⁷ and R ²⁸ each independently represent a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, or a heteroaryl group, R ²⁹ represents a hydrogen atom. R ²⁶ , R ²⁷ and R ²⁸ may each independently have a substituent.

R ²⁶ is preferably an alkyl group having 1 to 20 carbon atoms (including a cycloalkyl group), an alkenyl group having 2 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms, and an alkyl group having 1 to 12 carbon atoms. More preferably an alkenyl group having 2 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, an alkyl group having 1 to 12 carbon atoms (including a cycloalkyl group), It is more preferably an alkenyl group having 2 to 10 carbon atoms or an aryl group having 6 to 18 carbon atoms, an alkyl group having 1 to 8 carbon atoms (including a cycloalkyl group), an alkenyl group having 2 to 5 carbon atoms, An aryl group having 6 to 12 carbon atoms is particularly preferable, and an alkyl group having 1 to 6 carbon atoms (including a cycloalkyl group) or an aryl group having 6 to 12 carbon atoms is most preferable. Good.

Among these, a methyl group, an ethyl group, a propyl group, a cyclohexyl group, a phenyl group or a naphthyl group is more preferable, and a methyl group, a cyclohexyl group or a phenyl group is most preferable.

R ²⁷ and R ²⁸ are each independently an alkyl group having 1 to 20 carbon atoms (including a cycloalkyl group), an alkenyl group having 2 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or 6 to 20 carbon atoms. A heteroaryl group is more preferably an alkyl group having 1 to 12 carbon atoms (including a cycloalkyl group), an alkenyl group having 2 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms. It is more preferably an alkyl group having 1 to 12 (including a cycloalkyl group), an alkenyl group having 2 to 10 carbon atoms, or an aryl group having 6 to 18 carbon atoms, and an alkyl group having 1 to 8 carbon atoms (cycloalkyl An alkenyl group having 2 to 5 carbon atoms or an aryl group having 6 to 12 carbon atoms, and an alkyl group (cycloalkyl group) having 1 to 6 carbon atoms. Including), or most preferably an aryl group having 6 to 12 carbon atoms.

Among them, a methyl group, an ethyl group, a propyl group, a cyclohexyl group, a phenyl group, or a naphthyl group is most preferable, and a methyl group, an ethyl group, a cyclohexyl group, or a phenyl group is particularly preferable.

The substituent that R ²⁶ may have is not particularly limited as long as it is not contrary to the gist of the present invention, but is preferably a halogen atom, an alkyl group, or an aryl group, and preferably a halogen atom, a carbon number It is more preferably a 1 to 6 alkyl group or an aryl group having 6 to 12 carbon atoms, and particularly preferably a chlorine atom, a methyl group or a phenyl group.

The substituent that R ²⁷ and R ²⁸ may have is not particularly limited as long as it does not contradict the gist of the present invention, but is preferably an aryl group having 6 to 12 carbon atoms, More preferably.

As the compound represented by the general formula (2), a compound represented by the following general formula (2-a) can be used. The compound represented by the general formula (2-a) is preferable from the viewpoint of suppressing volatilization during film formation.

In the general formula (2-a), L ¹ to L ³ each independently represents a single bond or an alkylene group, and Ar ¹ to Ar ³ each independently represents an aryl group having 6 to 20 carbon atoms. .

L ¹ to L ³ are more preferably a single bond or an alkylene group having 1 to 6 carbon atoms, more preferably a single bond, a methylene group or an ethylene group, and particularly preferably a single bond or a methylene group. preferable. The divalent linking group may have a substituent, and the substituent is synonymous with a substituent that Ar ¹ , Ar ² , and Ar ³ described later may have.

Ar ¹ to Ar ³ are preferably a phenyl group or a naphthyl group, and more preferably a phenyl group. Ar ¹ to Ar ³ may have a substituent or may not have a substituent. When it has a substituent, it is preferable that the said substituent does not have a ring structure.

The substituent that Ar ¹ , Ar ² , and Ar ³ have is not particularly limited, and may be an alkyl group (preferably having 1 to 10 carbon atoms such as methyl, ethyl, isopropyl, t-butyl, pentyl, heptyl, 1- Ethylpentyl, benzyl, 2-ethoxyethyl, 1-carboxymethyl, etc.), alkenyl groups (preferably having 2 to 20 carbon atoms, such as vinyl, allyl, oleyl, etc.), alkynyl groups (preferably having 2 to 20 carbon atoms). For example, ethynyl, butadiynyl, phenylethynyl, etc.), cycloalkyl groups (preferably having 3 to 20 carbon atoms, such as cyclopropyl, cyclopentyl, cyclohexyl, 4-methylcyclohexyl, etc.), aryl groups (preferably having 6 to 6 carbon atoms). 26, for example, phenyl, 1-naphthyl, 4-methoxyphenyl, 2-chloro Phenyl, 3-methylphenyl and the like), a heterocyclic group (preferably a heterocyclic group having 0 to 20 carbon atoms, wherein the ring-constituting hetero atom is preferably an oxygen atom, a nitrogen atom or a sulfur atom, and a 5- or 6-membered ring is a benzene ring Or may be condensed with a heterocyclic ring, and the ring may be a saturated ring, an unsaturated ring, or an aromatic ring. For example, 2-pyridyl, 4-pyridyl, 2-imidazolyl, 2-benzoimidazolyl, 2- Thiazolyl, 2-oxazolyl, etc.), alkoxy groups (preferably having 1 to 20 carbon atoms, such as methoxy, ethoxy, isopropyloxy, benzyloxy, etc.), aryloxy groups (preferably having 6 to 26 carbon atoms, such as phenoxy) 1-naphthyloxy, 3-methylphenoxy, 4-methoxyphenoxy, etc.), an alkylthio group (preferably having 1 to 20 carbon atoms such as methyl Thio, ethylthio, isopropylthio, benzylthio, etc.), arylthio groups (preferably having 6 to 26 carbon atoms, such as phenylthio, 1-naphthylthio, 3-methylphenylthio, 4-methoxyphenylthio, etc.), acyl groups (alkylcarbonyl Group, an alkenylcarbonyl group, an arylcarbonyl group, and a heterocyclic carbonyl group, preferably having 20 or less carbon atoms, such as acetyl, pivaloyl, acryloyl, metachloroyl, benzoyl, nicotinoyl), an aryloylalkyl group, an alkoxycarbonyl group ( Preferably it has 2 to 20 carbon atoms, for example, ethoxycarbonyl, 2-ethylhexyloxycarbonyl, etc., aryloxycarbonyl group (preferably 7 to 20 carbon atoms, such as phenyloxycarbonyl, naphthyloxycarbonyl) Bonyl etc.), amino groups (including amino groups, alkylamino groups, arylamino groups, heterocyclic amino groups, preferably having 0 to 20 carbon atoms, for example, amino, N, N-dimethylamino, N, N-diethylamino N-ethylamino, anilino, 1-pyrrolidinyl, piperidino, morpholinyl, etc.), sulfonamide groups (preferably having 0 to 20 carbon atoms, such as N, N-dimethylsulfonamide, N-phenylsulfonamide, etc.), sulfamoyl Groups (preferably having 0 to 20 carbon atoms such as N, N-dimethylsulfamoyl, N-phenylsulfamoyl, etc.), acyloxy groups (preferably having 1 to 20 carbon atoms such as acetyloxy, benzoyloxy, etc. ), A carbamoyl group (preferably having 1 to 20 carbon atoms, for example, N, N-dimethylcarbamoyl) N-phenylcarbamoyl, etc.), acylamino groups (preferably having 1 to 20 carbon atoms, such as acetylamino, acryloylamino, benzoylamino, nicotinamide, etc.), cyano groups, hydroxyl groups, mercapto groups, or halogen atoms (eg, fluorine atoms) , Chlorine atom, bromine atom, iodine atom, etc.).

The substituent that Ar ¹ , Ar ² , and Ar ³ may have may further have the substituent.

Here, among the above substituents that each of Ar ¹ , Ar ² , and Ar ³ may have, an alkyl group, an aryl group, an alkoxy group, and an acyl group are preferable.

The molecular weight of the compound represented by the general formula (2) or (2-a) is preferably 250 to 1200, and more preferably 300 to 800. If the molecular weight is 250 or more, volatilization from the film is suppressed, and if it is 1200 or less, the compatibility with the cellulose acylate is excellent, and thus the transparency of the film is good.

Specific examples of the compound represented by the general formula (2) or (2-a) are shown below, but the present invention is not limited thereto. In the following exemplary compounds, Me represents a methyl group.

It is known that the compound represented by the general formula (2) can be synthesized by using a barbituric acid synthesis method in which a urea derivative and a malonic acid derivative are condensed. Barbituric acid having two substituents on N can be obtained by heating N, N 'disubstituted urea and malonic acid chloride, or by combining malonic acid and an activating agent such as acetic anhydride. For example, Journal of the American Chemical Society, Vol. 61, p. 1015 (1939), Journal of Medicinal Chemistry, Vol. 54, p. 2409 (2011), Tetrahedron, vol. ), Methods described in WO2007 / 150011 and the like can be preferably used.

In addition, the malonic acid used for the condensation may be unsubstituted or substituted, and if malonic acid having a substituent corresponding to R ⁵ is used, by constructing barbituric acid, the general formula (2 ) Can be synthesized. Further, when an unsubstituted malonic acid and a urea derivative are condensed, a 5-position unsubstituted barbituric acid is obtained. By modifying this, the compound represented by the general formula (2) can be synthesized. Good.

The method for synthesizing the compound represented by the general formula (2) is not limited to the above method.

The compound represented by the general formula (2) may be obtained commercially or synthesized by a known method.

(Content of polarizer durability improver)
The content of the polarizer durability improving agent in the protective film is preferably 1 part by mass or more and 20 parts by mass with respect to 100 parts by mass of cellulose acylate. If it is 1 part by mass or more, the effect of improving the durability of the polarizer can be easily obtained, and if it is 20 parts by mass or less, bleeding out and bleeding are less likely to occur when a polarizing plate protective film is formed.

The content of the polarizer durability improving agent is more preferably 1 to 15 parts by mass, and particularly preferably 1 to 10 parts by mass with respect to 100 parts by mass of cellulose acylate.

<Specific polymer>
It is preferable that the base material which consists of a cellulose ester contains the specific polymer which contains three components represented by following General formula (3) as a repeating unit.

・ R ²¹ to R ²⁴
R ²¹ , R ²² , R ²³ and R ²⁴ each independently represent a substituent. Although a substituent is not specifically limited, The following substituent T is mentioned, The preferable range is also synonymous.

・ R ¹⁰¹ to R ¹⁰³
R ¹⁰¹ to R ^{103 each} represents a hydrogen atom or an aliphatic group having 1 to 4 carbon atoms. R ¹⁰¹ to R ¹⁰³ are not particularly limited, but are preferably a hydrogen atom, a methyl group, or an ethyl group.

X, y, z
x represents a molar ratio of 0 to 40, preferably 0 to 30, and more preferably 0 to 20. y represents a molar ratio of 5 to 95, preferably 10 to 90, and more preferably 30 to 90. z represents a molar ratio of 0 to 70, preferably 0 to 60, and more preferably 0 to 50. x + y + z may not be 1 (100%), but when it is less than 1, it means that there are other copolymerization components. Examples of other copolymer components include vinyl toluene, isopropenyl toluene, α-methylstyrene, alkylindene, and dicyclopentadiene. The copolymerization ratio t of the other copolymer components is preferably 0 to 30, and more preferably 0 to 20.

・ M1 to m4
m1 and m2 each represents an integer of 0 to 4, and preferably 0 to 2. m3 represents an integer of 0 to 2, and is preferably 0. m4 represents an integer of 0 to 5, preferably 0 to 3, and more preferably 0 to 1.

Note that the end group of the specific polymer may be any type, and typically has a structure in which polymerization is stopped by adding hydrogen to a vinyl group.

Specific examples of the specific polymer are shown below, but the present invention is not construed as being limited thereto. In addition, the following structural formula has shown the chemical structure of the repeating unit of the main component, and its structural ratio, and it is as above-mentioned that the other component may be contained.

(Weight average molecular weight)
The weight average molecular weight of the specific polymer is preferably 200 to 10,000, more preferably 300 to 8,000, and particularly preferably 400 to 4,000. When the molecular weight is equal to or higher than the lower limit, it is possible to expect an effect that the moisture permeability and moisture content of the film can be effectively suppressed, and when the molecular weight is equal to or lower than the upper limit, compatibility with the cellulose acylate can be expected to be preferable. .

Unless otherwise specified, the molecular weight and the dispersity are values measured using a GPC (gel filtration chromatography) method, and the molecular weight is a weight average molecular weight in terms of polystyrene. The gel packed in the column used in the GPC method is preferably a gel having an aromatic compound as a repeating unit, and examples thereof include a gel made of a styrene-divinylbenzene copolymer. Two to six columns are preferably connected and used. Examples of the solvent used include ether solvents such as tetrahydrofuran and amide solvents such as N-methylpyrrolidinone. The measurement is preferably performed at a solvent flow rate in the range of 0.1 to 2 mL / min, and most preferably in the range of 0.5 to 1.5 mL / min. By performing the measurement within this range, the apparatus is not loaded and the measurement can be performed more efficiently. The measurement is preferably performed at 10 to 50 ° C., and most preferably at 20 to 40 ° C. In addition, the column and carrier to be used can be appropriately selected according to the physical properties of the polymer compound that is symmetrical to the measurement.

(Addition amount)
The addition amount of the specific polymer is not particularly limited, but is preferably 0.1 to 100 parts by mass, more preferably 0.5 to 50 parts by mass with respect to 100 parts by mass of cellulose acylate. 1.0 to 30 parts by mass is particularly preferable. When the addition amount is equal to or more than the lower limit value, it is possible to effectively suppress the moisture permeability and moisture content of the film, and when it is equal to or less than the upper limit value, high transparency can be expected to be maintained. One kind of the specific polymer may be used, or two or more kinds thereof may be used. In addition, even if there is no notice in particular, in the cellulose acylate film of the present embodiment, it means that each component may be used alone or in combination of two or more.

In this specification, a polymer or a polymer includes not only a polymer that is a general polymer compound in which a large number of monomers are polymerized, but also an oligomer that is a compound having a molecular weight of about several hundreds in which several monomers are polymerized. Means. The term “polymer” or “polymer” means a copolymer or copolymer unless otherwise specified.

In the present specification, when the term “compound” is added at the end, or when it is indicated by a specific name or chemical formula, it is used in the meaning including its salt, complex, and ion in addition to the compound itself. Moreover, it is the meaning including the derivative modified with the predetermined form in the range with the desired effect. Furthermore, in the present specification, when a specific group of atoms is referred to with the word “group” at the end of a substituent, this means that the group may have an arbitrary substituent. This is also synonymous for compounds that do not specify substitution / non-substitution. Preferred substituents include the following substituent T.

Examples of the substituent T include the following. An alkyl group (preferably an alkyl group having 1 to 20 carbon atoms, such as methyl, ethyl, isopropyl, t-butyl, pentyl, heptyl, 1-ethylpentyl, benzyl, 2-ethoxyethyl, 1-carboxymethyl, etc.), alkenyl A group (preferably an alkenyl group having 2 to 20 carbon atoms such as vinyl, allyl, oleyl and the like), an alkynyl group (preferably an alkynyl group having 2 to 20 carbon atoms such as ethynyl, butadiynyl, phenylethynyl and the like), A cycloalkyl group (preferably a cycloalkyl group having 3 to 20 carbon atoms, such as cyclopropyl, cyclopentyl, cyclohexyl, 4-methylcyclohexyl, etc.), an aryl group (preferably an aryl group having 6 to 26 carbon atoms, for example, Phenyl, 1-naphthyl, 4-methoxyphenyl, -Chlorophenyl, 3-methylphenyl, etc.), heterocyclic groups (preferably heterocyclic groups having 2 to 20 carbon atoms, such as 2-pyridyl, 4-pyridyl, 2-imidazolyl, 2-benzimidazolyl, 2-thiazolyl, 2 -Oxazolyl etc.), an alkoxy group (preferably an alkoxy group having 1 to 20 carbon atoms, such as methoxy, ethoxy, isopropyloxy, benzyloxy etc.), an aryloxy group (preferably an aryloxy group having 6 to 26 carbon atoms) For example, phenoxy, 1-naphthyloxy, 3-methylphenoxy, 4-methoxyphenoxy, etc.), alkoxycarbonyl groups (preferably alkoxycarbonyl groups having 2 to 20 carbon atoms, such as ethoxycarbonyl, 2-ethylhexyloxycarbonyl, etc.) ), Amino group (preferably carbon Amino groups having 0 to 20 atoms, such as amino, N, N-dimethylamino, N, N-diethylamino, N-ethylamino, anilino, etc., sulfonamido groups (preferably sulfonamido having 0 to 20 carbon atoms) A group such as N, N-dimethylsulfonamide, N-phenylsulfonamide, etc., an acyloxy group (preferably an acyloxy group having 1 to 20 carbon atoms such as acetyloxy, benzoyloxy, etc.), a carbamoyl group (preferably A carbamoyl group having 1 to 20 carbon atoms, such as N, N-dimethylcarbamoyl, N-phenylcarbamoyl, etc.), an acylamino group (preferably an acylamino group having 1 to 20 carbon atoms, such as acetylamino, benzoylamino, etc.) , A cyano group, or a halogen atom (eg, fluorine atom, chlorine atom, bromine atom) More preferably an alkyl group, alkenyl group, aryl group, heterocyclic group, alkoxy group, aryloxy group, alkoxycarbonyl group, amino group, acylamino group, cyano group or halogen atom, Particularly preferred are an alkyl group, an alkenyl group, a heterocyclic group, an alkoxy group, an alkoxycarbonyl group, an amino group, an acylamino group, and a cyano group. *

<Additives>
In addition to the specific compound, an additive may be added to each resin used for the transparent substrate. Examples of additives to be added include hydrophobizing agents (sugar ester compounds, aromatic terminal ester compounds) and plasticizers (polyester resins) described in paragraphs [0072] to [0121] of JP2013-28782A. Compound), retardation adjusting agent, ultraviolet absorber, antioxidant, deterioration preventing agent, peeling aid, surfactant, dye, fine particle and the like. It is preferable to add a plasticizer, an antioxidant, an ultraviolet absorber, or the like that imparts heat and humidity resistance to a polarizing plate used in a display device such as an organic EL display.

These compounds are contained in an amount of 1 to 30% by mass, preferably 1 to 20% by mass, based on each resin. In order to suppress bleeding out during stretching and drying, a compound having a vapor pressure at 200 ° C. of 1400 Pa or less is preferable.

<Other plasticizers>
The cellulose ester resin can contain other plasticizers as necessary. Preferably, 1) a polyhydric alcohol ester plasticizer, 2) a polycarboxylic acid ester plasticizer, 3) a glycolate plasticizer, 4) a phthalate ester plasticizer, 5) a citrate ester plasticizer, 6) Fatty acid ester plasticizer, 7) Phosphate ester plasticizer, etc. These plasticizers are preferably used in the range of 1 to 30% by mass with respect to the cellulose ester.

1) The polyhydric alcohol ester plasticizer is an ester compound of a polyhydric alcohol represented by the following general formula (4).
R1- (OH) n (4)
(In the formula, R1 represents an n-valent organic group, and n represents a positive integer of 2 or more)

Preferred examples of the polyhydric alcohol include ethylene glycol, propylene glycol, trimethylolpropane, and pentaerythritol.

As the monocarboxylic acid used in the polyhydric alcohol ester, known aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, aromatic monocarboxylic acid, and the like can be used.

As the aliphatic monocarboxylic acid, a fatty acid having a straight chain or a side chain having 1 to 32 carbon atoms can be preferably used. More preferably, it has 1 to 20 carbon atoms, and particularly preferably 1 to 10 carbon atoms.

Examples of preferable alicyclic monocarboxylic acids include cyclopentane carboxylic acid, cyclohexane carboxylic acid, cyclooctane carboxylic acid, and derivatives thereof.

Examples of preferred aromatic monocarboxylic acids include those in which an alkyl group is introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, and two or more benzene rings such as biphenylcarboxylic acid, naphthalenecarboxylic acid, and tetralincarboxylic acid. The aromatic monocarboxylic acid which has, or those derivatives can be mentioned. In particular, benzoic acid is preferred.

The molecular weight of the polyhydric alcohol ester is preferably in the range of 300 to 1500, more preferably in the range of 350 to 750. The carboxylic acid used for the polyhydric alcohol ester may be one kind or a mixture of two or more kinds. Moreover, all the OH groups in the polyhydric alcohol may be esterified, or a part of the OH groups may be left as they are.

In addition, trimethylolpropane triacetate, pentaerythritol tetraacetate, and the like are also preferably used. It is also preferable to use the ester compound (A) represented by the general formula (I) described in JP-A-2008-88292.

2) The polyvalent carboxylic acid ester compound is composed of an ester of divalent or higher, preferably divalent to 20-valent polyvalent carboxylic acid and alcohol. The aliphatic polyvalent carboxylic acid is preferably divalent to 20-valent, and in the case of an aromatic polyvalent carboxylic acid or an alicyclic polyvalent carboxylic acid, it is preferably divalent to 20-valent.

The polyvalent carboxylic acid is represented by the following general formula (5).
R2 (COOH) m (OH) n (5)
(Wherein R2 is an (m + n) -valent organic group, m is a positive integer of 2 or more, n is an integer of 0 or more, a COOH group is a carboxyl group, and an OH group is an alcoholic or phenolic hydroxyl group)

Examples of preferred polyvalent carboxylic acids include the following. Divalent or higher aromatic polyvalent carboxylic acids or derivatives such as phthalic acid, terephthalic acid, isophthalic acid, trimellitic acid, trimesic acid, pyromellitic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, oxalic acid Aliphatic polycarboxylic acids such as fumaric acid, maleic acid and tetrahydrophthalic acid, and oxypolycarboxylic acids such as tartaric acid, tartronic acid, malic acid and citric acid can be preferably used.

Known alcohols and phenols can be used as the alcohol used in the polyvalent carboxylic acid ester compound that can be used in the present embodiment. For example, an aliphatic saturated alcohol having a straight chain or a side chain having 1 to 32 carbon atoms can be preferably used. More preferred are those having 1 to 20 carbon atoms, and particularly preferred are those having 1 to 10 carbon atoms.

In addition, alicyclic alcohols such as cyclopentanol and cyclohexanol or derivatives thereof, aromatic alcohols such as benzyl alcohol and cinnamyl alcohol, or derivatives thereof can also be preferably used. Examples of phenol include phenol, paracresol, dimethyl Phenol etc. can be used individually or in combination of 2 or more types.

It is also preferable to use an ester compound (B) represented by the general formula (II) described in JP-A-2008-88292.

The molecular weight of the polyvalent carboxylic acid ester compound is not particularly limited, but is preferably in the range of 300 to 1000, more preferably in the range of 350 to 750.

The alcohol used for the polyvalent carboxylic acid ester may be one kind or a mixture of two or more kinds.

The acid value of the polycarboxylic acid ester compound is preferably 1 mgKOH / g or less, and more preferably 0.2 mgKOH / g or less. The acid value means the number of milligrams of potassium hydroxide necessary for neutralizing the acid (carboxyl group present in the sample) contained in 1 g of the sample. The acid value is measured according to JIS K0070.

3) The glycolate plasticizer is not particularly limited, but alkylphthalylalkyl glycolates can be preferably used. Examples of the alkyl phthalyl alkyl glycolates include methyl phthalyl methyl glycolate, ethyl phthalyl ethyl glycolate, propyl phthalyl propyl glycolate, butyl phthalyl butyl glycolate, octyl phthalyl octyl glycolate and the like.

4) Examples of the phthalate ester plasticizer include diethyl phthalate, dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, dioctyl phthalate, dicyclohexyl phthalate, and dicyclohexyl terephthalate.

5) Examples of the citrate plasticizer include acetyltrimethyl citrate, acetyltriethyl citrate, and acetyltributyl citrate.

6) Examples of fatty acid ester plasticizers include butyl oleate, methylacetyl ricinoleate, and dibutyl sebacate.

7) Examples of the phosphate ester plasticizer include triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, tributyl phosphate, and the like.

<Retardation adjuster>
As the compound added for adjusting the retardation of the transparent substrate, an aromatic compound having two or more aromatic rings as described in EP 911,656A2 can be used. Two or more aromatic compounds may be used in combination. The aromatic ring of the aromatic compound includes an aromatic heterocyclic ring in addition to the aromatic hydrocarbon ring. Particularly preferred is an aromatic heterocycle, and the aromatic heterocycle is generally an unsaturated heterocycle. Of these, a 1,3,5-triazine ring is particularly preferred.

<Polymer or oligomer>
Each resin constituting the transparent substrate of the present embodiment has a substituent selected from a carboxyl group, a hydroxyl group, an amino group, an amide group, and a sulfo group, and has a weight average molecular weight of 500 to 200,000. It is also possible to contain a polymer or oligomer of a vinyl compound that falls within the range. The mass ratio of the content of each resin constituting the transparent substrate and the polymer or oligomer is preferably in the range of 95: 5 to 50:50.

<Ultraviolet absorber>
It is preferable that the transparent base material of this embodiment contains a ultraviolet absorber. The ultraviolet absorber is intended to improve durability by absorbing ultraviolet light having a wavelength of 400 nm or less. In particular, the transmittance at a wavelength of 370 nm is preferably 10% or less, and more preferably 5% or less. .

Although the ultraviolet absorber used in this embodiment is not particularly limited, for example, oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, triazine compounds, nickel complex salts, inorganic Examples thereof include powders.

The amount of the UV absorber used is not uniform depending on the type of UV absorber, the use conditions, etc., but when the dry film thickness of the transparent substrate is 30 to 200 μm, it is 0.5 to 10 with respect to the transparent substrate. % By mass is preferable, and 0.6 to 4% by mass is more preferable.

<Antioxidant>
It is also preferred that the film substrate contains an antioxidant. Preferred antioxidants are phosphorous or phenolic, and it is more preferred to combine phosphorous and phenolic simultaneously.

<Matting agent>
In the present embodiment, fine particles can be contained in the transparent substrate as a matting agent, which makes it easy to transport and wind up when the film is long. The particle size of the matting agent is preferably primary particles or secondary particles of 10 nm to 0.1 μm. A substantially spherical matting agent having a primary particle acicular ratio of 1.1 or less is preferably used. As the fine particles, those containing silicon are preferable, and silicon dioxide is particularly preferable. As fine particles of silicon dioxide preferable for this embodiment, for example, Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600 (manufactured by Nippon Aerosil Co., Ltd.) manufactured by Nippon Aerosil Co., Ltd. And commercially available products such as Aerosil 200V, R972, R972V, R974, R202, and R812 can be preferably used. Examples of polymer fine particles include silicone resin, fluorine resin, and acrylic resin. Silicone resins are preferable, and those having a three-dimensional network structure are particularly preferable. Examples include Tospearl 103, 105, 108, 120, 145, 3120, and 240 (manufactured by Toshiba Silicone Co., Ltd.). Can do.

<Other additives>
In addition, heat stabilizers such as inorganic fine particles such as kaolin, talc, diatomaceous earth, quartz, calcium carbonate, barium sulfate, titanium oxide, and alumina, and alkaline earth metal salts such as calcium and magnesium may be added to the transparent substrate. Good. Further, a surfactant, a peeling accelerator, an antistatic agent, a flame retardant, a lubricant, an oil agent and the like may be added to the transparent substrate.

(Coating layer)
The protective film in this embodiment has at least one coating layer on a substrate made of cellulose ester.

The coating layer is not particularly limited as long as it is a low moisture-permeable material, but a resin layer containing a layered inorganic compound, a layer containing a vinyl alcohol polymer, a repeating unit derived from a chlorine-containing vinyl-chlorine-containing vinyl monomer A layer mainly composed of a polymer containing, a silica-based coating film, a coating film mainly composed of silica formed from a coating composition containing polysilazane, and the like can be used alone or in combination. Among these, a resin layer containing a layered inorganic compound is particularly preferable from the viewpoints of moisture permeability and adhesion with a cellulose ester as a substrate.

These can be used as a single layer as a coating layer for the substrate, or two or more different materials can be used. The method for laminating the coating layer is not particularly limited. In the case of using two or more different materials, the stacking order is not limited, and they may be provided on the opposite sides of each other through the base material. Further, a functional layer such as a hard coat layer, AG (anti-glare layer), a low refractive index layer, and a high refractive index layer can be further provided on the coating layer.

<Resin layer containing layered compound>
The resin layer containing the layered compound is not particularly limited as long as the layered inorganic compound is dispersed in the resin layer (binder component). Examples of the resin layer include the above-described cellulose ester, a resin containing a vinyl alcohol polymer, or a UV curable acrylic resin.

The layered inorganic compound in the present embodiment is an inorganic compound that has a structure in which unit crystal layers are laminated and swells or cleaves when a solvent is coordinated or absorbed between the layers. Examples of such inorganic compounds include swellable hydrous silicates such as smectite group clay minerals (montmorillonite, saponite, hectorite, etc.), palm curite group clay minerals, kaolinite group clay minerals, phyllosilicates (mica). Etc.). A synthetic layered inorganic compound is also preferably used. Examples of the synthetic layered inorganic compound include synthetic smectite (hectorite, saponite, stevensite, etc.), synthetic mica and the like.

Among these layered inorganic compounds, smectite, montmorillonite and mica are preferable, montmorillonite and mica are more preferable, mica is more preferable, and synthetic mica is more preferable from the viewpoint of adjustment of moisture permeability, improvement of brittleness, and prevention of coloring. Particularly preferred. Examples of layered inorganic compounds that can be used as commercial products include MEB-3 (synthetic mica aqueous dispersion manufactured by Corp Chemical Co., Ltd.), ME-100 (synthetic mica manufactured by Corp Chemical Co., Ltd.), and S1ME (manufactured by Corp Chemical Co., Ltd.). Synthetic mica), SWN (Synthetic smectite manufactured by Corp Chemical Co., Ltd.), SWF (Synthetic smectite manufactured by Corp Chemical Co., Ltd.), Kunipia F (Purified bentonite manufactured by Kunimine Chemical Industry Co., Ltd.), Bengel (Hojun Co., Ltd.) Purified bentonite), Bengel HV (refined bentonite manufactured by Hojun Co., Ltd.), Wenger FW (purified bentonite manufactured by Hojun Co., Ltd.), Wenger Bright 11 (purified bentonite manufactured by Hojun Co., Ltd.), Wenger Bright 23 (Hojung) (Refined bentonite manufactured by Co., Ltd.), Wenger Bright 25 ( Jun K.K. purified bentonite), Wenger A (HOJUN Co., Ltd. purified bentonite), Wenger 2M (HOJUN Co., Ltd. purified bentonite) and the like can be used.

(Organized layered inorganic compound)
In the present embodiment, the layered inorganic compound is from the viewpoint of improving the moisture permeability adjustment by improving the dispersibility in the organic solvent and the swelling / cleavage after addition to the solvent, and improving the brittleness, It is preferably organically treated. The organic treatment of the layered inorganic compound means that the organic agent is captured between the unit crystal layers by treating the crystal surface of the unit crystal layer and the hydroxyl group on the crystal end face with the organic agent.

Examples of the layered inorganic compound subjected to the organic treatment include a layered inorganic compound subjected to an organic treatment with an organic agent such as alkylamine as described below. Further, for the purpose of further strengthening the strength of the cellulose acylate film and reducing moisture permeability, the organic acylation treatment may be performed with an organic agent containing a polymerizable group.

Examples of organically treated layered inorganic compounds that can be used as commercial products include Somasif MAE, MTE, MEE, MPE (all synthetic mica manufactured by Coop Chemical Co., Ltd.), Lucentite SAN, STN, SEN, SPN (all COP Chemical). Synthetic smectite manufactured by Co., Ltd.) and the like.

In addition, layered inorganic compounds that have not been organically treated, such as Lucentite ME-100 (synthetic mica manufactured by Corp Chemical Co., Ltd.) and Lucentite SWN (synthetic smectite manufactured by Corp Chemical Co., Ltd.) are commercially available. It is also preferable to perform an organic treatment with an agent. The organic agent is preferably a quaternary ammonium salt, and is not particularly limited, but a quaternary ammonium salt represented by the following general formula (6) is more preferable.
N (Ra) _4-n (Rb) _n + A ⁻ (6)

In the general formula (6), Ra represents — (CH ₂ ) _m H, — (CH ₂ ) _m RcH, or — (CH ₂ Rc) _m H, m is an integer of 2 or more, and Rc is an arbitrary group or There is no need, and Rb represents —CH ₃ . n represents an integer of 0 to 3. A ^- is Cl ^- or Br ^- represents a.

In the general formula (6), n is preferably 0 to 3, more preferably 0 to 2, and still more preferably 0 to 1. It is preferable from the viewpoint of dispersibility that n is in this range. When there are a plurality of Ras, all groups may have the same structure or different structures.

M is 2 or more, and in at least one group of Ra, m is particularly preferably 4 or more, more preferably 8 or more, and further preferably 8 to 30. The larger m is, the better the dispersibility is improved. Moreover, it is preferable from the point of the ratio of the organic substance with respect to a layered inorganic compound that m is in the said range.

Ra preferably has a structure in which interaction between molecules is large, and examples thereof include —OH, —CH ₂ CH ₂ O—, and —CHO (CH) ₃ —.

Examples of the quaternary ammonium salt used for the organic treatment including the quaternary ammonium salt represented by the general formula (6) include dimethyldioctadecylammonium bromide, trimethyloctadecylammonium chloride, benzyltrimethylammonium chloride, dimethylbenzyloctadecyl. Ammonium bromide, trioctylmethylammonium chloride, polyoxypropylene trimethylammonium chloride, di (polyoxypropylene) dimethylammonium chloride, di (polyoxyethylene) dodecylmethylammonium chloride, tri (polyoxypropylene) methylammonium chloride, tri (poly And oxypropylene) methylammonium bromide.

As a method of using an organically treated layered inorganic compound, a method in which the organically treated layered inorganic compound is sufficiently dispersed in an organic solvent and a cellulose acylate solution (dope) is added to the dispersion. In addition, a method of adding a solution in which a layered inorganic compound subjected to organic treatment is dispersed in an organic solvent is added to the dope solution.

The layered inorganic compound is preferably finely divided from the viewpoint of moisture permeability adjustment, brittleness, and haze. The layered inorganic compound subjected to the fine particle treatment is usually plate-shaped or flat-shaped, and the planar shape is not particularly limited, and may be an amorphous shape. The average particle radius (planar average particle radius) of the layered inorganic compound that has been microparticulated is preferably, for example, 0.1 to 10 μm, more preferably 0.5 to 8 μm, and particularly preferably 0.8 to 6 μm. The average particle radius is the number of particles having the value among the particle radius distribution values measured by a general particle size distribution meter, for example, a light scattering type particle size distribution meter ("Microtrack UPA" manufactured by Nikkiso Co., Ltd.). The largest particle size. By setting it as the above range, a sufficient moisture permeability adjusting effect can be obtained, and an increase in haze value and an increase in surface roughness can be prevented.

(Dispersion treatment of layered inorganic compound)
By laminating the layered inorganic compound in the resin film in a state where the layers are swollen or cleaved, the moisture permeability path length can be increased and the moisture permeability can be reduced. Therefore, in order to obtain a state in which each layer of the layered inorganic compound is swollen or cleaved, it is preferable to perform the organic treatment or dispersion treatment. The dispersion treatment is preferably carried out by high-pressure dispersion treatment a plurality of times in the solution. The treatment pressure is preferably 10 MPa or more, more preferably 20 MPa or more. There is no specific designation as a solvent.

In the present embodiment, the content of the layered inorganic compound in the resin film is 1 to 50% by mass with respect to the total solid content in the resin film. If it is this range, a water vapor transmission rate can be reduced to a desired range, without causing a raise of a haze value. More preferably, it is 3 to 48% by mass.

<Layer containing vinyl alcohol polymer>
Examples of the vinyl alcohol polymer constituting the coating layer include a homopolymer such as polyvinyl alcohol (PVA) and an ethylene-vinyl alcohol copolymer (EVOH). In addition, these vinyl alcohol polymers may be partially carbonyl-modified, silanol-modified, epoxy-modified, acetoacetyl-modified, amino-modified or ammonium-modified, and a part thereof is a diacetone acrylamide unit. You may use the copolymer containing these. Various vinyl alcohol polymers can be used alone or in combination of two or more.

The saponification degree of the vinyl alcohol polymer can be selected from a range of 80 mol% or more, but is preferably 96 mol% or more, more preferably 99 mol% or more. The degree of polymerization of the vinyl alcohol polymer is preferably from 200 to 5,000, preferably from 400 to 5,000, more preferably from about 500 to 3,000, from the viewpoint of moisture permeability and coatability.

In this embodiment, a vinyl alcohol polymer cross-linking agent can be further added as a component of the resin composition to the vinyl alcohol polymer, thereby improving the water resistance of the adhesive layer.

The cross-linking agent that can be used for this purpose is not particularly limited, and any known cross-linking agent can be preferably used. Examples of crosslinking agents include phenolic resin, melamine resin, urea resin, polyamide polyurea, dimethylol urea, dimethylol melamine, polyvalent epoxy compound, dialdehyde compound, polyvalent isocyanate resin, aziridine compound, polyamidoamine epichlorohydrin compound, activity Vinyl compound, dicarbonate compound, hydrazino group-containing compound (other carboxylic acid polyhydrazide compound), colloidal silica, zirconium salt, polyvalent metal salt, boric acid, phosphoric acid, polyacrylic acid, dicarboxylic acid, adipic acid anhydride And titanium compounds such as succinic anhydride, tetraisopropyl titanate, and diisopropoxy bis (acetylacetone) titanate. In addition, coupling agents such as 3-glycidpropylmethoxysilane, The use of such a radical generating agent such as id are possible. It is also possible to add a catalyst and other additives for promoting the crosslinking reaction.

The addition amount of the crosslinking agent is preferably 0.5% by mass or more, more preferably 1% by mass or more, and particularly preferably 2% by mass or more in terms of (crosslinking agent / (vinyl alcohol polymer + crosslinking agent)). . In the case where the mass ratio of the crosslinking agent to both the PVA polymer and the crosslinking agent is less than 0.5% by mass, the effect is not exhibited by adding the crosslinking agent. The mass ratio of the crosslinking agent to both the vinyl alcohol polymer and the crosslinking agent is preferably 50% by mass or less, more preferably 40% by mass or less, and particularly preferably 30% by mass or less. Since some crosslinking agents such as aldehyde-based compounds turn yellow by heat, it is necessary to reduce the amount of such crosslinking agents to be within an allowable range by reducing the amount of addition.

When a vinyl alcohol polymer is used as the coating layer, the thickness is preferably 1.0 to 10 μm, more preferably 2 to 8 μm, still more preferably 3 to 7 μm. If the thickness is less than 1 μm, the effect of improving light leakage is not sufficient, which is not preferable. Moreover, when thickness exceeds 10 micrometers, brittleness deteriorates and it is not preferable.

<Resin layer containing a polymer containing a repeating unit derived from a chlorine-containing vinyl monomer>
In general, examples of the chlorine-containing vinyl monomer include vinyl chloride and vinylidene chloride. The chlorine-containing polymer can be obtained by copolymerizing these vinyl chloride or vinylidene chloride monomers with a monomer copolymerizable therewith.

Examples of the chlorine-containing polymer in the present embodiment include JP-A-53-58553, JP-A-55-43185, JP-A-57-139109, JP-A-57-139136, The ones described in JP-A-60-235818, JP-A-61-108650, JP-A-62-256671, JP-A-62-280207, JP-A-63-256665, etc. may be used. it can.

The proportion of the chlorine-containing vinyl monomer in the chlorine-containing polymer is preferably 50 to 99% by mass, more preferably 60 to 98% by mass, and most preferably 70 to 97% by mass. If the ratio of the chlorine-containing vinyl monomer is 50% by mass or more, problems such as deterioration of moisture permeability will not occur, and if it is 99% by mass or less, solubility in various solvents can be obtained. Therefore, it is preferable.

Chlorine-containing polymers are available from Asahi Kasei Chemicals Corporation and Kureha Chemical Corporation. The following are listed as available from Asahi Kasei Chemicals Corporation.

That is, “Saran Resin R241C”, “Saran Resin F216”, “Saran Resin R204”, “Saran Latex L502”, “Saran Latex L529B”, “Saran Latex L536B”, “Saran Latex L544D”, “Saran Latex L549B”, “Saran Latex” "L551B", "Saran Latex L557", "Saran Latex L561A", "Saran Latex L116A", "Saran Latex L411A", "Saran Latex L120", "Saran Latex L123D", "Saran Latex L106C", "Saran Latex L131A" “Saran Latex L111”, “Saran Latex L232A”, and “Saran Latex L321B” are available. In particular, Saran Resin F216 and Saran Resin R204 are more preferably used because they are soluble in ketone solvents (such as methyl ethyl ketone and cyclohexanone).

When a resin layer containing a polymer containing a repeating unit derived from a chlorine-containing vinyl monomer is used as the coating layer, the thickness is preferably 0.3 to 5 μm, more preferably 0.5 to 4 μm, and more preferably 0.7 to 3 μm is more preferable. If the thickness of the coating layer is less than 0.3 μm, the moisture permeability is not sufficiently lowered, and thus the effect of improving light leakage is not sufficient, which is not preferable. Moreover, when the thickness of a coating layer exceeds 5 micrometers, problems, such as yellowing of a film, will arise and it is unpreferable.

In this embodiment, when the chlorine-containing polymer is vinylidene chloride, it is preferable to use tetrahydrofuran as the main solvent. In addition, by selecting a copolymer of vinylidene chloride, it is possible to dissolve in toluene, ketone solvents, etc., and it is more preferable to use toluene, ketone solvents, etc. without using tetrahydrofuran, and use methyl ethyl ketone, cyclohexanone. Is particularly preferred. Moreover, it is also preferable to add the said solvent in the range which a solute melt | dissolves in tetrahydrofuran. When tetrahydrafuran is used, it is preferable to add 0.01 to 1% by mass of a reducing substance such as p-cresol, resorcin, hydroquinone, and ferrous salt from the viewpoint of light stabilization. . The reducing substance is preferably used because it is effective in preventing coloring of the coating layer.

Further, when the chlorine-containing polymer is supplied as a latex dispersion, water is preferably used as the main solvent. In the case of a latex dispersion, it is preferable to use a surfactant, a thickener or the like in combination.

Silicia (Fuji Silysia), Mizuka Seal (Mizusawa Chemical Co., Ltd.), Nip Seal (Nihon Silica Kogyo Co., Ltd.), etc. for improving blocking resistance when coating layers containing chlorine-containing polymers are applied on transparent substrates. 0.2 to 1.0 part of silica powder is added to the chlorine-containing polymer, paraffin wax (manufactured by Nippon Seiwa), behenic acid (manufactured by Nippon Oil & Fats), stearic acid (manufactured by Nippon Oil & Fats), etc. It is also preferable to add 0.2 to 5.0 parts of wax emulsion. Further, modified waxes described in paragraphs [0012] to [0016] of JP-A-9-143419 are also preferably used.

Since the chlorine-containing polymer is decomposed and colored by heat, light, and ultraviolet rays, it is preferable that stearic acid such as lead, zinc, barium, silver salts, magnesium oxide, or the like is used together as a stabilizer. Further, the antioxidants described in paragraphs [0013] to [0020] of JP-A-2004-359819 may be used.

In addition, in order to increase the adhesion between the coating layer containing the chlorine-containing polymer and the transparent substrate or other layers, an isocyanate-based adhesive such as Coronate L (manufactured by Nippon Polyurethane) or Takenate A-3 (Takeda Pharmaceutical). It is also preferable to add 0.1 to 1.0 part of the agent with respect to the chlorine-containing polymer.

<Silica-based coating film>
The silica-based coating film is provided on at least one side of a transparent substrate made of cellulose acylates. In order to achieve the desired moisture permeability and withstand practical use as a protective film, it is necessary to achieve both denseness and flexibility. Only a silica film which is a hydrolyzate produced by adding a catalyst and water to alkoxysilane and hydrolytic condensation is insufficient in flexibility. For this reason, in this embodiment, the coating film containing the compound which consists of a compound which consists of alkoxysilane, a functional group which reacts with a hydroxyl group or an alkoxyl group, and / or a silane coupling agent is used preferably. It is particularly preferable to contain all of a compound comprising an alkoxysilane, a compound having a functional group that reacts with a hydroxyl group or an alkoxyl group, and a silane coupling agent.

(Compound consisting of alkoxysilane)
As a compound which consists of alkoxysilane used by this embodiment, it represents with following General formula (7), for example. In the following general formula (7), R ₁ represents a hydrogen atom, an alkyl group or an acyl group, R ₂ represents a hydrogen atom, an alkyl group or an aromatic group, and n represents a number from 2 to 4.

In the general formula (7), examples of the alkyl group represented by R ₁ include a methyl group, an ethyl group, a propyl group, and a butyl group. Examples of the acyl group include an acetyl group and a propionyl group. . Among these, a methyl group, an ethyl group, and a propyl group are particularly preferable, and an ethyl group is most preferable. n is preferably 2 to 4, more preferably 3 to 4, and still more preferably 4.

Accordingly, tetraalkoxysilane is preferable, tetramethoxysilane, tetraethoxysilane, and tetrapropoxysilane are particularly preferable, and tetraethoxysilane is particularly preferable. When n is 2 or 3, examples of the alkyl group represented by R ₂ include an alkyl group having 1 to 18 carbon atoms, preferably 1 to 5 carbon atoms, and examples of the aromatic group include a phenyl group. .

(Compound having a functional group that reacts with a hydroxyl group or an alkoxyl group)
In this embodiment, a compound having a functional group that reacts with a hydroxyl group or an alkoxyl group is used.

Monomers, oligomers, and polymers having a functional group that reacts with a hydroxyl group or an alkoxyl group are more preferably used, and any monomer having a functional group that reacts with a hydroxyl group or an alkoxyl group can be used without particular limitation.

For example, a thermosetting, ionizing curable, or moisture curable resin selected from an acrylic resin, a polyester resin, an epoxy resin, a urethane resin, and a melamine resin is used, and a monomer having a hydroxyl group, More preferred are oligomers and polymers, polymers having hydroxyl groups are particularly preferred, vinyl alcohol polymers such as polyvinyl alcohol (PVA) homopolymers and ethylene-vinyl alcohol copolymers (EVOH) are more preferably used, A homopolymer of polyvinyl alcohol (PVA) is particularly preferably used.

It is also possible to use a part of these vinyl alcohol polymers modified with a carbonyl group or the like, a copolymer containing a diacetone acrylamide unit or the like in part. Various vinyl alcohol polymers can be used alone or in combination of two or more.

The vinyl alcohol polymer preferably used as the compound having a functional group that reacts with a hydroxyl group or an alkoxyl group can be selected from a range in which the saponification degree of the vinyl alcohol polymer is 80 mol% or more. The saponification degree is preferably 96 mol% or more, and more preferably 98 mol% or more. The degree of polymerization of the vinyl alcohol polymer is preferably 200 to 5,000, more preferably 400 to 5,000, and even more preferably about 500 to 3,000, from the viewpoint of moisture permeability and coatability.

(Silane coupling agent)
In this embodiment, a silane coupling agent is used. The silane coupling agent is not particularly limited as long as it is a compound having an alkoxysilane at the terminal, but at the same time, vinyl group, epoxy group, acrylic group or methacryl group, amine group, mercapto group, hydroxyl group, isocyanate group, carboxyl group, acid Those having an anhydride group are more preferred, and those having an epoxy group, an amine group, an acrylic group or a methacryl group are even more preferred.

As the silane coupling agent having a vinyl group, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (β-methoxyethoxy) silane and the like are preferably used.

Examples of silane coupling agents having an epoxy group include β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltriethoxysilane, and γ-glycidoxypropyltrimethoxysilane. Γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltriethoxysilane and the like are preferably used.

Examples of the silane coupling agent having an acrylic group or a methacryl group include γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, and γ-methacryloxypropyltriethoxy. Silane or the like is preferably used.

Examples of the silane coupling agent having an amine group include N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N-β (aminoethyl) γ- Aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane and the like are preferably used.

As the silane coupling agent having a mercapto group, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane and the like are preferably used.

As the silane coupling agent having an isocyanate group, γ-isocyanatopropyltrimethoxysilane, γ-isocyanatopropyltriethoxysilane, and the like are preferably used.

In this embodiment, since a silane coupling agent may be used simultaneously with a compound having a functional group that reacts with a hydroxyl group or an alkoxyl group, in order to crosslink with a compound having a functional group that reacts with a hydroxyl group or an alkoxyl group. It is preferable to use a silane coupling agent having an epoxy group.

Further, since the silane coupling agent is used at the same time as the compound composed of alkoxysilane, it is preferable to use a silane coupling agent having an amine group from the viewpoint of increasing the reaction rate of dehydration polycondensation of alkoxysilane.

Further, a layer having a hard coat property may be provided on the coating layer. In this case, in order to improve interlayer adhesion with the layer having a hard coat property, a silane coupling having an acrylic group or a methacryl group is provided. It is particularly preferable to use an agent.

Another preferred embodiment of the silane coupling agent that can be used in the present embodiment is a silane coupling agent having alkoxysilane at both ends.

A silane coupling agent having alkoxysilane at both ends is desirable in that it can be crosslinked with a compound comprising alkoxysilane. As an example of the compound, an organic chain-containing both-end functional silane monomer described in JP-A No. 2000-326448 is preferably used.

In this embodiment, a hydrolyzate of a silane coupling agent and a partial condensate of a hydrolyzate of a silane coupling agent are also preferably used. In the present embodiment, the silane coupling agent includes a hydrolyzate of the silane coupling agent and a partial condensate of the hydrolyzate of the silane coupling agent.

The silane coupling agent having an epoxy group, an amine group, an acrylic group, or a methacryl group may be used alone, but it is more preferable to use two or more types in combination, and it is particularly preferable to use three types in combination. A tertiary amine soluble in an organic solvent is used as a polycondensation catalyst for increasing the reaction rate, and two types of silane coupling agent having an epoxy group and a silane coupling agent having an acrylic group or a methacryl group are simultaneously used. Is more preferable.

When the content rate of the compound which consists of an alkoxysilane, the compound which has a functional group which reacts with a hydroxyl group or an alkoxyl group, and a silane coupling agent is a mass%, b mass%, and c mass%, respectively (in this case, alkoxy The content of the compound composed of silane is calculated from the calculated value after polycondensation when ideally condensed), a compound composed of alkoxysilane, and a compound having a functional group that reacts with a hydroxyl group or an alkoxyl group. When used, a / b is preferably 10/90 to 90/10, more preferably 20/80 to 80/20, and particularly preferably 40/60 to 80/20. In the case of using a compound comprising an alkoxysilane and a silane coupling agent, a / c is preferably 40/60 to 95/5, and more preferably 50/50 to 90/10.

In the case of simultaneously using a compound comprising an alkoxysilane, a compound having a functional group that reacts with a hydroxyl group or an alkoxyl group, and a silane coupling agent, a / (b + c) is preferably 10/90 to 90/10, 20/80 to 80/20 is more preferable, and 40/60 to 80/20 is particularly preferable. In this case, b / c is preferably 10/90 to 90/10, more preferably 20/80 to 80/20, and still more preferably 40/60 to 80/20.

(Other ingredients)
In this embodiment, a catalyst and water are used in order to advance the polycondensation reaction of the compound consisting of alkoxysilane as described above.

Examples of the curing catalyst include acids such as hydrochloric acid, nitric acid, acetic acid, oxalic acid, maleic acid, and fumaric acid, and N, N-dimethylbenzylamine, tripropylamine, tributylamine, and tripentylamine that are soluble in organic solvents. Triamines, organic metals, metal alkoxides and the like are used.

The addition amount is preferably 1 to 10% by mass, more preferably 1 to 5 parts by mass with respect to 100 parts by mass of the compound comprising alkoxysilane.

In addition, with respect to the addition of water, an amount that is at least the amount by which the partial hydrolyzate can theoretically be hydrolyzed by 100% is preferable, and an amount equivalent to 110 to 300% is more preferable. More preferably, an amount corresponding to 120 to 200% is added.

(Coating solvent)
As the solvent of the coating composition for forming the silica-based coating film as the coating layer of this embodiment, one or two of water, methyl alcohol, ethyl alcohol, isopropyl alcohol, n-butanol, isobutanol, and octanol are used. It is preferable to use a mixture of the above. The amount of the solvent is preferably adjusted so that the solid concentration is 15 to 60% by mass.

<Coating film mainly composed of silica formed from a coating composition containing polysilazane>
Another preferred material of the silica-based coating film as the coating layer of the present embodiment includes a cured product of a coating composition containing polysilazane. The polysilazane used is preferably the polysilazane described in paragraphs [0097] to [0104] described in JP-A No. 11-240103. Although it is possible to use polysilazane alone, it is also possible to use it in place of the aforementioned compound comprising alkoxysilane.

[Polarizer]
The polarizer is preferably composed of polyvinyl alcohol (PVA) and a dichroic molecule. However, as described in JP-A-11-248937, PVA and polyvinyl chloride are dehydrated and dechlorinated. Thus, a polyvinylene polarizer in which a polyene structure is generated and oriented may be used.

PVA is a polymer material obtained by saponifying polyvinyl acetate, but may contain a component copolymerizable with vinyl acetate such as unsaturated carboxylic acid, unsaturated sulfonic acid, olefins and vinyl ethers. Further, modified PVA containing an acetoacetyl group, a sulfonic acid group, a carboxyl group, an oxyalkylene group, or the like may be used.

The degree of saponification of PVA is not particularly limited and may be appropriately selected depending on the intended purpose. For example, from the viewpoint of solubility and the like, it is preferably 80 to 100 mol%, more preferably 90 to 100 mol%.

The polymerization degree of PVA is not particularly limited and may be appropriately selected depending on the intended purpose. For example, 1,000 to 10,000 is preferable, and 1,500 to 5,000 is more preferable.

The syndiotacticity of PVA is not particularly limited and may be appropriately selected according to the purpose. For example, as described in Japanese Patent No. 2978219, 55% or more is required to improve durability. However, as described in Japanese Patent No. 3317494, 45 to 52.5% can be preferably used. PVA is preferably formed into a film and then a dichroic molecule is introduced to form a polarizer.

As a method for producing a PVA film, a method of casting a stock solution obtained by dissolving a PVA resin in water or an organic solvent and forming a single film is generally preferably used. The concentration of the polyvinyl alcohol-based resin in the stock solution is usually 5 to 20% by mass, and a PVA film having a film thickness of 10 to 200 μm can be produced by forming this stock solution by casting. It can also be produced by a method of coating on a base film and forming a laminate, and a thinner PVA film having a thickness of 1 to 20 μm can be formed.

The production of the PVA film is disclosed in Japanese Patent No. 3342516, Japanese Patent Application Laid-Open No. 09-328593, Japanese Patent Application Laid-Open No. 2001-302817, Japanese Patent Application Laid-Open No. 2002-144401, Japanese Patent No. 4279944, Japanese Patent Application Laid-Open No. 2009-98653. It can carry out with reference to the production method described in the above.

The film thickness before stretching of the PVA film can be appropriately selected depending on the purpose. For example, from the viewpoint of film holding stability and stretching uniformity, 1 μm to 1 mm is preferable, and 20 to 200 μm is more preferable. preferable.

Further, as described in JP-A-2002-236212, a thin PVA film may be used in which the stress generated when stretching 4 to 6 times in water is 10 N or less.

The dichroic molecule, I ₃ ^- and I ₅ ^- higher iodine ion such as, or a dichroic dye is preferably used. Among these, higher-order iodine ions are particularly preferably used in the present embodiment. Higher-order iodine ions can be obtained by converting iodine into an aqueous potassium iodide solution as described in “Application of Polarizing Plate” by Nagata Ryo, CMC Publishing, Industrial Materials, Vol. 28, No. 7, p39-p45. PVA can be immersed in the dissolved liquid and / or boric acid aqueous solution, and can be produced in a state of being adsorbed and oriented in PVA.

When a dichroic dye is used as the dichroic molecule, an azo dye is preferable, and among them, a bisazo dye and a trisazo dye are more preferable. The dichroic dye is preferably a water-soluble dye. For this reason, a hydrophilic substituent such as a sulfonic acid group, an amino group, or a hydroxyl group is introduced into the dichroic molecule, and a free acid, an alkali metal salt, an ammonium salt, or an amine is introduced. It is preferably used as a salt.

Here, in order to produce dichroic molecules having various hues, two or more of these dichroic dyes may be blended. When a dichroic dye is used, the adsorption thickness may be 4 μm or more as described in JP-A No. 2002-082222.

If the content of the dichroic molecule in the film is too small, the degree of polarization is low, and if it is too large, the single-plate transmittance is lowered, so that usually a polyvinyl alcohol polymer constituting the matrix of the film Is adjusted to a range of 0.01% by mass to 5% by mass.

The preferable film thickness of the polarizer is preferably 15 μm or less, more preferably 3 μm or more and 10 μm or less. Further, as described in JP-A-2002-174727, the ratio (A / B) between the thickness (A) of the polarizer and the thickness (B) of the protective film is set to 0.01 ≦ A /B≦0.8 is also preferable.

〔Polarizer〕
The polarizing plate of this embodiment has the polarizer which consists of PVA, and the protective film containing the transparent base material and coating layer which consist of a cellulose ester. The polarizing plate of this embodiment can be produced by a general method. That is, the polarizer side of the cellulose ester film of this embodiment and at least one surface of a polarizer produced by immersion and stretching in an iodine solution can be bonded together using an adhesive. As an adhesive agent, a commercially available saponified polyvinyl alcohol aqueous solution or a photocurable adhesive agent can be used, and can be properly used depending on the film. For example, when a transparent base material is a cellulose ester film like this embodiment, a protective film and a polarizer can be alkali-treated and these can be bonded by saponification type polyvinyl alcohol aqueous solution. When the transparent substrate is an acrylic or polyester film, a protective film and a polarizer can be bonded using a photocurable adhesive.

In the polarizing plate of the present embodiment, a conventional polarizing plate protective film or an optical film may be bonded to the opposite side of the cellulose ester film (transparent substrate) on the viewing side with respect to the polarizer. It does not have to be combined. That is, the polarizing plate of the present embodiment may have only a cellulose ester film and a polarizer, and various configurations can be employed. In particular, it is preferable that the cellulose ester film is bonded to both sides of the polarizer.

[Display device]
The display apparatus of this embodiment is comprised by arrange | positioning the polarizing plate containing the protective film which has a coating layer and a cellulose-ester film, and a polarizer with a film thickness of 15 micrometers or less on the visual recognition side with respect to a liquid crystal cell. Thereby, even if a polarizer is a structure of a thin film, a polarizer deterioration in a high temperature, high humidity environment can be suppressed, and a display nonuniformity can be suppressed.

The polarizing plate of the present embodiment is not only a liquid crystal display device of various driving methods such as STN, TN, OCB, HAN, VA (MVA, PVA), IPS, OCB, but also other displays such as an organic EL display device and a plasma display. It can also be used for devices.

〔Example〕
EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "part by mass" or "mass%" is represented.

<Preparation of protective film F1>
(Preparation of composition liquid a-1 for substrate)
The following composition was placed in a mixing tank and stirred to dissolve each component to prepare a substrate composition liquid a-1.
Cellulose acetate (acetyl substitution degree 2.87) 100.0 parts by mass Polyester compound (PE-1) 8.0 parts by mass Polarizer durability improver (A-6) 5.0 parts by mass UV absorber A 0 parts by mass Methylene chloride (first solvent) 300.0 parts by mass Methanol (second solvent) 75.0 parts by mass n-butanol (third solvent) 4.0 parts by mass

The polyester-based compound (PE-1) has an ethanediol / phthalic acid (1/1 (molar ratio)) condensate at both ends with an acetate ester, and its number average molecular weight Mn is 1000 It is.

Further, the ultraviolet absorber A is represented by the following chemical structural formula.

(Preparation of composition liquid b-1 for coating layer)
The following composition was charged into a mixing tank and stirred to dissolve each component to prepare a coating layer composition liquid b-1.
Cellulose acetate (acetyl substitution degree 2.87) 100.0 parts by mass The polyester-based compound (PE-1) 8.0 parts by mass Polarizer durability improver (A-6) 5.0 parts by mass Synthetic smectite (Lucentite) STN, manufactured by Coop Chemical Co., Ltd.)
66.0 parts by mass Methylene chloride (first solvent) 621.0 parts by mass Methanol (second solvent) 90.0 parts by mass n-butanol (third solvent) 5.0 parts by mass

(Casting)
Using a drum casting apparatus, two layers of the prepared substrate composition liquid a-1 and coating layer composition liquid b-1 were simultaneously poured onto a stainless steel casting support (support temperature -9 ° C.). Cast uniformly from the slot. Stripped in a state where the amount of residual solvent in the solution of each layer is approximately 70% by mass, fixed both ends in the width direction of the film with a pin tenter, and 1.28 in the lateral direction when the amount of residual solvent was 3-5% by mass. The film was dried while being stretched twice. Thereafter, the film was further dried by conveying between rolls of a heat treatment apparatus to obtain a laminated film in which the coating layer b-1 was laminated on the base material a-1. The thickness of the obtained laminated film was 25 μm (the thickness of the base material a-1 was 20 μm, the thickness of the coating layer b-1 was 5 μm), and the width was 1480 mm.

(Preparation of composition liquid b-2 for coating layer)
100 parts by mass of NK Ester A-TMM-3L (manufactured by Shin-Nakamura Chemical Co., Ltd.), 1 part by mass of KF-351A (polyether-modified silicone oil, manufactured by Shin-Etsu Chemical Co., Ltd.), BYK-UV3505 (Bic Chemie) 2 parts by mass of Japan Co., Ltd., 220 parts by mass of V-8804 (silica fine particle dispersion, manufactured by JGC Catalysts & Chemicals Co., Ltd.), 12 parts by mass of Irgacure 184 (manufactured by BASF Japan Ltd.), propylene glycol monomethyl ether 20 parts by mass and 240 parts by mass of normal propanol were mixed and stirred for about 30 minutes to prepare a coating layer composition liquid b-2.

(Preparation of protective film F1)
On the laminated film produced above, the coating layer composition liquid b-2 was applied using an extrusion coater so that the dry film thickness was 5 μm, and the constant rate drying zone temperature was 50 ° C., the decreasing rate drying zone temperature was 50 ° C. After drying with an ultraviolet lamp using an ultraviolet lamp while purging with nitrogen so that the atmosphere has an oxygen concentration of 1.0% by volume or less, the illuminance of the irradiated part is 100 mW / cm ² , and the irradiation dose is 0.2 J / cm ^2. The coating layer was cured to form a coating layer b-2, and a protective film F1 was obtained. That is, the protective film F1 has a configuration in which the coating layer b-1 and the coating layer b-2 are laminated in this order on the base material a-1, and the total film thickness is 30 μm.

<Preparation of protective film F2>
(Preparation of composition liquid b-3 for coating layer)
70 parts by mass of water and 5 parts by mass of Lucentite STN (solid content ratio 8% by mass, manufactured by Co-op Chemical) in water are mixed, and 3 parts by mass of vinyl alcohol polymer HR-3010 (manufactured by Kuraray Co., Ltd.) is mixed. After the addition, the mixture was stirred at 95 ° C. for 2 hours. Thereafter, the obtained composition liquid was filtered through a polypropylene filter having a pore diameter of 100 μm to obtain a coating layer composition liquid b-3.

(Preparation of protective film F2)
Using the drum casting apparatus, only the base material composition liquid a-1 was cast on a casting support, and stretched and dried to prepare a base material a-1 having a thickness of 20 μm. Thereafter, saponification treatment was performed at 50 ° C. using a 1 mol / L alkaline solution on the side of the base material a-1 on which the coating layer was provided. Next, the coating layer composition liquid b-3 was applied onto the saponification surface of the substrate a-1 so that the film thickness after drying was 5 μm at a conveying speed of 30 m / min, and 100 ° C. for 5 minutes. The coating layer b-3 was formed by drying. Thereafter, the coating layer composition liquid b-2 is applied onto the coating layer b-3 and cured in the same manner as in the production of the protective film F1, thereby forming a coating layer b-2 having a dry film thickness of 5 μm. Thus, a protective film F2 was obtained. That is, the protective film F2 has a configuration in which the coating layer b-3 and the coating layer b-2 are laminated in this order on the base material a-1, and the total film thickness is 30 μm.

<Preparation of protective film F3>
(Preparation of composition liquid b-4 for coating layer)
100 parts by weight of UA-306H (Kyoeisha Co., Ltd., pentaerythritol triacrylate hexamethylene diisocyanate urethane prepolymer: pentaerythritol tetraacrylate = 70: 30), 5 parts by weight of Lucentite STN, Irgacure 184 (Ciba Japan Co., Ltd.) 5 parts by mass), 50 parts by mass of methyl ethyl ketone and 50 parts by mass of propylene glycol monomethyl ether were mixed and stirred for about 30 minutes to prepare a coating layer composition b-4.

(Preparation of protective film F3)
Using the drum casting apparatus, only the base material composition liquid a-1 was cast on a casting support, and stretched and dried to prepare a base material a-1 having a thickness of 20 μm. Thereafter, the coating layer composition liquid b-4 is applied onto the substrate a-1 and cured by the same method as the formation of the coating layer b-2 described above, and the coating layer b-4 having a dry film thickness of 5 μm is cured. And a protective film F3 was obtained. That is, the protective film F3 has a configuration in which the coating layer b-4 is laminated on the base material a-1, and the total film thickness is 25 μm.

<Preparation of protective film F4>
The protective film F1 was produced in the same manner as the protective film F1, except that the coating layer b-4 was formed using the coating layer composition liquid b-4 instead of the coating layer composition liquid b-2. A protective film F4 was produced. That is, the protective film F4 has a configuration in which the coating layer b-1 and the coating layer b-4 are laminated in this order on the base material a-1, and the total film thickness is 30 μm.

<Preparation of protective film F5>
(Preparation of coating layer composition liquid b-5)
100 parts by weight of UA-306H (Kyoeisha Co., Ltd., pentaerythritol triacrylate hexamethylene diisocyanate urethane prepolymer: pentaerythritol tetraacrylate = 70: 30), AV Light 3PC (Asahi Organic Materials Co., Ltd., 2, 15 parts by mass of 6-bis [(2-hydroxy-5-methylphenyl) methyl] -4-methylphenol), 5 parts by mass of Irgacure 184 (manufactured by Ciba Japan), 50 parts by mass of methyl ethyl ketone, propylene 50 parts by mass of glycol monomethyl ether was mixed and stirred for about 30 minutes to prepare a coating layer composition liquid b-5.

(Preparation of protective film F5)
The protective film F1 was produced in the same manner as the protective film F1, except that the coating layer b-5 was formed using the coating layer composition liquid b-5 instead of the coating layer composition liquid b-2. A protective film F5 was produced. That is, the protective film F5 has a configuration in which the coating layer b-1 and the coating layer b-5 are laminated in this order on the base material a-1, and the total film thickness is 30 μm.

<Preparation of protective film F6>
(Preparation of composition liquid b-6 for coating layer)
15 parts by mass of perhydropolysilazane solution (NP110-20, solid content 20%) manufactured by AZ Electronic Materials Co., Ltd., which is a polysilazane solution, and 1 part by mass of BR-80 manufactured by Mitsubishi Rayon Co., Ltd., which is a methyl methacrylate polymer After mixing and stirring for 30 minutes, composition liquid b-6 for coating layer was prepared.

(Preparation of protective film F6)
Using the drum casting apparatus, only the base material composition liquid a-1 was cast on a casting support, and stretched and dried to prepare a base material a-1 having a thickness of 20 μm. Thereafter, the coating layer composition b-6 was applied onto the substrate a-1 using an extrusion coater, dried at a temperature of 80 ° C. for 1 hour, and then at a temperature of 60 ° C. and a humidity of 60% for 1 hour. Humidity treatment (humidity treatment step) was performed to form a coating layer b-6 with a dry film thickness of 5 μm, and a protective film F6 was produced. That is, the protective film F6 has a configuration in which the coating layer b-6 is laminated on the base material a-1, and the total film thickness is 25 μm.

<Preparation of protective film F7>
(Preparation and application of coating solution for undercoat layer)
6 parts by mass of styrene butadiene latex (solid content 43%), 1 part by mass of 2,4-dichloro-6-hydroxy-s-triazine sodium salt (8%), and 32 parts by mass of water are stirred to dissolve each component. The undercoat layer coating solution was prepared.

Using the drum casting apparatus, only the base material composition liquid a-1 was cast on a casting support, and stretched and dried to prepare a base material a-1 having a thickness of 20 μm. Thereafter, the substrate a-1 was unwound in a roll form, and the above undercoat layer coating solution was applied to one surface (the surface serving as an adhesive interface with the coating layer) so that the dry film thickness was 90 nm. .

(Preparation of composition liquid b-7 for coating layer)
12 parts by mass of “Saran Resin R204” manufactured by Asahi Kasei Life & Living Co., Ltd. and 63 parts by mass of tetrahydrofuran were charged into a mixing tank and stirred to dissolve each component, thereby preparing a coating layer composition liquid b-7.

(Preparation of protective film F7)
The substrate a-1 coated with the undercoat layer coating liquid on one side is unwound in a roll form, and the coating layer composition liquid b-7 is directly extruded onto the substrate a-1 using a coater having a slot die. And applied. At this time, the coating layer composition liquid b-7 was applied under the condition of a conveyance speed of 30 m / min so that the film thickness would be 5 μm, and dried at 80 ° C. for 5 minutes to form the coating layer b-7. Rolled up as F7. That is, the protective film F7 has a configuration in which the coating layer b-7 is laminated on the base material a-1, and the total film thickness is approximately 25 μm.

<Preparation of protective film F8>
Using the drum casting apparatus, only the base material composition liquid a-1 was cast on a casting support, and stretched and dried to prepare a base material a-1 having a thickness of 20 μm. Thereafter, the substrate a-1 was subjected to corona treatment, and the mixture was applied to the corona-treated surface and dried to form an anchor coat layer having a thickness of 100 nm. The above mixture refers to a hydroxyl group-containing acrylic resin ("Dainal LR209" manufactured by Mitsubishi Rayon Co., Ltd.) and an isocyanate group-containing resin ("Sumidule N-3200" manufactured by Sumitomo Bayer Urethane Co., Ltd.). It is a mixture blended so that the equivalent ratio of the isocyanate group to 1 is 1: 1.

Next, SiO was evaporated by a heating method under a vacuum of 2 × 10 ⁻³ Pa using a vacuum vapor deposition apparatus, and a 40 nm thick SiOx vacuum vapor deposition film (PVD film) was formed on the anchor coat layer. The conveyance speed of the base material in forming the PVD inorganic layer was 250 m / min. Subsequently, without returning the pressure to atmospheric pressure, HMDSN (hexamethyldisilazane), nitrogen, and Ar gas were introduced at a molar ratio of 1: 7: 7 to form plasma under a vacuum of 0.4 Pa. A CVD inorganic layer (SiOCN (silicon oxycarbonitride) was formed thereon (carbon content: 2 at.%, Thickness: 1 nm). The substrate conveyance speed during the formation of the CVD inorganic layer was 250 m / min.

Thereafter, without returning the pressure to atmospheric pressure, SiO is evaporated by a heating method under a vacuum of 2 × 10 ⁻³ Pa, and an inorganic layer (SiOx) having a thickness of 40 nm is formed as a coating layer b-8 on the CVD inorganic layer. The protective film F8 was obtained. That is, the protective film F8 has a configuration in which the coating layer b-8 is laminated on the base material a-1, and the total film thickness is approximately 20 μm.

<Preparation of protective film F9>
Using the drum casting apparatus, only the base material composition liquid a-1 was cast on a casting support, and stretched and dried to prepare a base material a-1 having a thickness of 20 μm. Thereafter, the coating layer composition b-2 is applied onto the substrate a-1 and cured in the same manner as in the production of the protective film F1 to form a coating layer b-2 having a dry film thickness of 5 μm. Thus, a protective film F9 was obtained. That is, the protective film F9 has a configuration in which the coating layer b-2 is laminated on the base material a-1, and the total film thickness is 25 μm.

<Preparation of protective film F13>
The coating layer b-1 is formed on both sides of the base material a-1 by the three-layer simultaneous casting using the base material composition liquid a-1 and the coating layer composition liquid b-1, and one coating layer b A coating layer b-2 was formed on -1. Other than that produced the protective film F13 by the method similar to preparation of the protective film F1. In the protective film F13, the thickness of each coating layer b-1 was 2.5 μm. Therefore, the protective film F13 has a configuration in which the coating layer b-1, the base material a-1, the coating layer b-1, and the coating layer b-2 are laminated in this order, and the total film thickness is 30 μm.

<Preparation of protective film F14>
(Preparation of composition liquid a-2 for substrate)
The following composition was placed in a mixing tank and stirred to dissolve each component to prepare a substrate composition liquid a-2.
Cellulose acetate (acetyl substitution degree 2.86) 100.0 parts by mass Sucrose octabenzoate 5.0 parts by mass UV absorber A 2.0 parts by mass Polarizer durability improver (1-11) 8.0 parts by mass Methylene Chloride (first solvent) 300.0 parts by mass Methanol (second solvent) 75.0 parts by mass n-butanol (third solvent) 4.0 parts by mass

(Preparation of protective film F14)
The protective film F1 was prepared except that the base material composition liquid a-1 was changed to the base material composition liquid a-2 and the coating layer b-1 was formed on the base material a-2 by two-layer simultaneous casting. A protective film F14 was produced by the same method as the production. That is, the protective film F14 has a configuration in which the coating layer b-1 and the coating layer b-2 are laminated in this order on the base material a-2, and the total film thickness is 30 μm.

<Preparation of protective film F15>
(Preparation of composition liquid a-3 for substrate)
The following composition was put into a mixing tank and stirred to dissolve each component to prepare a composition liquid a-3 for a substrate.
Cellulose acetate (acetyl substitution degree 2.87) 100.0 parts by mass Monopet (registered trademark) SB manufactured by Daiichi Kogyo Kagaku Co. 9.0 parts by mass SAIB100 (plasticizer) manufactured by Eastman Chemical Co., Ltd. 3.0 parts by mass Polymer (P-01) 4.0 parts by mass UV absorber A 2.0 parts by mass Methylene chloride (first solvent) 300.0 parts by mass Methanol (second solvent) 75.0 parts by mass n-butanol (first 3 solvents) 4.0 parts by mass

(Preparation of protective film F15)
The protective film F1 was prepared except that the base material composition liquid a-1 was changed to the base material composition liquid a-3, and the coating layer b-1 was formed on the base material a-3 by simultaneous casting of two layers. A protective film F15 was produced by the same method as the production. That is, the protective film F15 has a configuration in which the coating layer b-1 and the coating layer b-2 are laminated in this order on the base material a-3, and the total film thickness is 30 μm.

<Preparation of protective film F16>
(Preparation of composition liquid a-4 for substrate)
The following composition was put into a mixing tank and stirred to dissolve each component to prepare a substrate composition liquid a-4.
Cellulose acetate (acetyl substitution degree 2.86) 100.0 parts by mass The polyester-based compound (PE-1) 12.0 parts by mass Retardation increasing agent A 3.0 parts by mass Compound X 2.0 parts by mass Methylene chloride 400.0 Parts by mass methanol 60.0 parts by mass

In addition, said retardation raising agent A is shown with the following chemical structural formula.

Further, the above compound X is represented by the following chemical structural formula.

(Preparation of protective film F16)
The protective film F1 was formed except that the base material composition liquid a-1 was changed to the base material composition liquid a-4, and the coating layer b-1 was formed on the base material a-4 by simultaneous casting of two layers. A protective film F16 was produced by the same method as the production. However, the thickness of the base material a-4 was 40 μm. That is, the protective film F16 has a configuration in which the coating layer b-1 and the coating layer b-2 are laminated in this order on the base material a-4, and the total film thickness is 50 μm.

<Preparation of protective film F17>
A protective film F17 containing the base material a-5 was produced as follows.

(Preparation of solution for skin layer)
100 parts by mass of the following cellulose acylate solution 1 and a predetermined amount of the following matting agent dispersion 1 were mixed to prepare a skin layer solution. The predetermined amount is such that the amount of the matting agent fine particles is 0.20 parts by mass with respect to the cellulose acylate resin.

<< Cellulose Acylate Solution 1 >>
Cellulose acetate (acetyl substitution degree 2.87) 100.0 parts by mass Polyester compound (PE-2) 30.0 parts by mass Methylene chloride (first solvent) 350.0 parts by mass Methanol (second solvent) 90.0 parts by mass N-Butanol (third solvent) 5.0 parts by mass

The polyester compound (PE-2) has an acetyl ester form at both ends of the condensate of ethanediol / 1,2-propanediol / adipic acid (7/3/10 (molar ratio)). The number average molecular weight Mn is 1000.

<< Matting Agent Dispersion 1 >>
Matting agent (Aerosil R972) 2.0 parts by weight Methylene chloride (first solvent) 70.0 parts by weight Methanol (second solvent) 18.0 parts by weight n-butanol (third solvent) 1.0 part by weight Rate solution 1 1.0 part by mass

(Preparation of core solution)
The following composition was put into a mixing tank and stirred to dissolve each component to prepare a core solution.
Cellulose acetate (acetyl substitution degree 2.87) 100.0 parts by mass The polyester-based compound (PE-2) 30.0 parts by mass The ultraviolet absorber A 2.0 parts by mass Methylene chloride (first solvent) 300.0 parts by mass Methanol (second solvent) 75.0 parts by mass n-Butanol (third solvent) 4.0 parts by mass

(Preparation of protective film F17)
Using a drum casting apparatus, the core layer solution prepared above and the skin layer solution on both sides of the solution were uniformly applied to the stainless steel casting support (support temperature -9 ° C.) from the casting port. Casted. Stripped in a state where the amount of residual solvent in the solution of each layer is approximately 70% by mass, fixed both ends in the width direction of the film with a pin tenter, and 1.28 in the lateral direction when the amount of residual solvent was 3-5% by mass. The film was dried while being stretched twice. Thereafter, the substrate was further dried by being conveyed between rolls of a heat treatment apparatus to produce a base material a-5, and a protective film F17 was formed as a single layer of the base material a-5. The thickness of the obtained protective film F17 was 25 μm (air side surface layer (skin layer) 3 μm, base layer (core layer) 19 μm, support side surface layer (skin layer) 3 μm), and the width was 1480 mm.

<Preparation of protective film F10>
40 parts by weight of a (meth) acrylic resin having a lactone ring structure [weight ratio of copolymerization monomer: methyl methacrylate / 2- (hydroxymethyl) methyl acrylate = 8/2; lactone cyclization rate of about 100%] A mixture of 60 parts by weight of acrylonitrile-styrene (AS) resin {Toyo AS AS20, manufactured by Toyo Styrene Co., Ltd.} is dissolved in a solvent of 250 parts by weight of methylene chloride and 10 parts by weight of ethanol, and uniformly on a stainless steel belt support. Casted. With the stainless steel band support, the solvent is evaporated until the residual solvent amount reaches 75% by weight, and the solvent is peeled off from the stainless steel band support, and dried while being transported by a number of rolls. 6 was obtained as a protective film F10.

<Protective film F11>
As the base material a-7, an ester film E5101 (biaxially stretched polyester film with a film thickness of 25 μm, single-sided corona treatment) manufactured by Toyobo Co., Ltd. was used, and this base material a-7 was used as the protective film F11.

<Preparation of protective film F12>
A norbornene resin [Nippon Zeon Co., Ltd., ZEONOR (registered trademark) 1420] is melt-extruded at 250 ° C. and stretched at a stretching temperature of 135 ° C. in the width direction by 2 times and in the transport direction by 2 times. As a result, a base material a-8 having a dry film thickness of 20 μm was obtained. This base material a-8 was used as the protective film F12.

<Preparation of polarizing plate>
(Preparation of polarizer 1)
A polyvinyl alcohol film (average polymerization degree 2400, saponification degree 99 mol%, trade name: VF-PS2400) manufactured by Kuraray Co., Ltd. is dissolved in hot water at 95 ° C. to obtain a polyvinyl alcohol aqueous solution having a concentration of 10% by weight. Was prepared. After apply | coating the said polyvinyl alcohol aqueous solution to a commercially available PET film, it was made to dry at 120 degreeC for 10 minute (s), and the laminated body which formed the 20-micrometer-thick polyvinyl alcohol coating film was obtained. The laminate was stretched to a stretch ratio of 5 times by free end uniaxial stretching using a tenter apparatus under heating at 143 ° C. to obtain a stretched laminate.

Next, the stretched laminate was immersed in an iodine solution (weight ratio: iodine / potassium iodide / water = 1/10/100) at 30 ° C. for 60 seconds while maintaining the tension. Then, it dried at 60 degreeC for 4 minute (s), and obtained the polarizer with PET which is a coating type polarizer. The thickness of the polyvinyl alcohol coating film in the obtained polarizer with PET (stretched laminate) was 10 μm.

(Preparation of polarizer 2)
A polarizer 2 having a thickness of 5 μm, which is a coating-type polarizer, was obtained in the same manner as the production of the polarizer 1 except that the polyvinyl alcohol coating film before stretching was changed to 10 μm.

(Preparation of polarizer 3)
After applying an aqueous solution prepared by dissolving PVA powder having an average polymerization degree of 2400 and a saponification degree of 99.9% or more in pure water to 10% by mass on a polyester film and drying at 40 ° C. for 3 hours. Further, drying was performed at 110 ° C. for 60 minutes to obtain a PVA film having a thickness of 60 μm. The obtained film was swollen with warm water at 30 ° C. for 1 minute, immersed in an aqueous solution of potassium iodide / iodine (mass ratio 10: 1) at 30 ° C., and stretched uniaxially 1.5 times. The iodine concentration of the aqueous solution of potassium iodide / iodine (mass ratio 10: 1) was 0.38% by mass.

Next, in a 4.25% boric acid aqueous solution at 50 ° C, the film was uniaxially stretched so that the total draw ratio was 7 times, immersed in a 30 ° C water bath, washed with water, dried at 50 ° C for 4 minutes, A polarizer 3 having a thickness of 15 μm was obtained.

(Preparation of polarizer 4)
A polarizer 4 having a thickness of 25 μm was obtained in the same manner as the production of the polarizer 3 except that the original film thickness was changed to 100 μm.

(Preparation of polarizing plate)
The protective films F1 to F17 produced above and the polarizers 1 to 4 were bonded so as to have the combinations shown in Table 2 below, thereby producing polarizing plates P1 to P22.

Here, when the substrate of the protective film contains a cellulose ester (see the substrates a-1 to a-5), the protective film and the polarizer were bonded as follows.

The produced cellulose acetate film was alkali-treated with a 2.5 mol / L sodium hydroxide aqueous solution at 40 ° C. for 90 seconds, washed with water for 45 seconds, neutralized with 10% by mass HCl at 30 ° C. for 45 seconds, and then 30 ° C. for 45 seconds. It was washed with water and saponified to obtain an alkali-treated film. Then, the prepared polarizer and the alkali-treated film were bonded using a completely saponified polyvinyl alcohol 5% aqueous solution as an adhesive.

On the other hand, when the base material of the protective film contains other than cellulose ester (see base materials a-6 to a-8), the protective film and the polarizer were bonded as follows.

A composition for an adhesive layer comprising 100 parts by weight of N-hydroxyethylacrylamide and 3 parts by weight of Irgacure 127 (manufactured by Ciba Japan Co., Ltd.) as a micro gravure coater (gravure roll: # 300, rotational speed 140%). / Line speed) was applied so that the thickness after curing was 5 μm to obtain a protective film with an adhesive. Next, the adhesive side of the protective film with adhesive and the polarizer were bonded together with a roll machine. Thereafter, the adhesive was cured by irradiating ultraviolet rays from both sides. The line speed was 20 m / min, and the cumulative amount of ultraviolet light applied to the protective film was 200 mJ / cm ² , respectively.

<Evaluation of moisture permeability>
In accordance with JIS Z-0208, each protective film F1 to F17 is conditioned for 24 hours in an environment of 40 ° C. and 90% RH, and is then measured per unit area before and after humidity adjustment using a moisture permeability test device. The amount of water (g / m ² ) was calculated. Then, the moisture permeability of the entire protective film was determined by (water content after humidity control) − (water content before humidity control). In addition, the moisture permeability of the coating layer was calculated in advance from the relationship of 1 / x = 1 / y + 1 / z, which was obtained in advance with a predetermined thickness of the base material alone. In addition, x is the water vapor transmission rate of the whole protective film, y is the water vapor transmission rate of a base material, and z is the water vapor transmission rate of a coating layer. Here, said coating layer refers to all the layers except a base material from the protective film. In addition, the unit of moisture permeability is g / m ² / day. Table 1 shows the layer configuration of each protective film, the film thickness of each layer, and the moisture permeability. In Table 1, the coating layers are a coating layer 1, a coating layer 2, and a coating layer 3 from the viewer side.

<Evaluation of display device>
A conventionally known IPS type liquid crystal display panel was used as the liquid crystal display panel, and the polarizing plate on the viewing side thereof was replaced with the prepared polarizing plates P1 to P22, thereby manufacturing a liquid crystal display device. At this time, the polarizing plates P1 to P22 were bonded to the panel using an acrylic pressure-sensitive adhesive so that the viewer-side protective film was on the outermost surface side (viewer side).

The produced IPS-type liquid crystal display device was subjected to wet heat treatment at 60 ° C. and 90% RH for 24 hours, and luminance unevenness (strong / weak) and color unevenness (presence or absence of color different from black) after 2 hours of backlight lighting The influence was evaluated based on the following criteria by visual observation in a lighted room and under a fluorescent lamp. The evaluation results are shown in Table 2.
<Evaluation criteria>
A: Brightness unevenness or color unevenness is not visible even in an unlit environment.
○: Luminance unevenness or color unevenness appears to be weak visually in an extinguished environment, but does not bother under fluorescent lights.
X: Brightness unevenness or color unevenness is worrisome even under a fluorescent lamp.

From Tables 1 and 2, in the liquid crystal display device using the polarizing plates P8 to P13 and P22, at least one of luminance unevenness and color unevenness is visually observed, and the display quality is deteriorated. This is considered to be due to the following reasons.

In the protective film F8 of the polarizing plate P8, the moisture permeability of the coating layer is less than 0.1 g / m ² / day, which is definitely below 1 g / m ² / day. That is, the coating layer of the protective film F8 has a very high barrier property. For this reason, even if moisture from a polarizer is transmitted through a substrate made of cellulose ester at a high temperature, the moisture hardly penetrates the coating layer, and as a result, the polarizer deteriorates due to the moisture. Therefore, the display quality is considered to have deteriorated.

In the protective film F9 of the polarizing plate P9, the moisture permeability of the coating layer is very high as 650 g / m ² / day, and the moisture permeability of the entire protective film is also 430 g / m ² / day, far exceeding 300 g / m ² / day. It has become. For this reason, it is considered that moisture in the atmosphere easily passes through the coating layer and the base material and easily reaches the polarizer, and this moisture deteriorates the polarizer and lowers the display quality.

The protective films F10 to F12 of the polarizing plates P10 to P12 are composed of a single base material (no coating layer is provided on the viewing side of the base material). The base material is a resin other than cellulose ester, that is, an acrylic resin, a polyester resin, or a norbornene resin, and the moisture permeability of these resins is lower than that of cellulose ester. For this reason, the moisture contained in the polarizer cannot be transmitted at a high temperature, and as a result, the polarizer deteriorates due to the moisture remaining at the interface between the polarizer and the film, resulting in a deterioration in display quality. it is conceivable that.

In the protective film F13 of the polarizing plate P13, the coating layer (coating layer 3) is interposed between the base material and the polarizer, and the base material is not in direct contact with the polarizer. For this reason, the water | moisture content of a polarizer can hardly be permeate | transmitted with a base material at the time of high temperature, As a result, it is thought that a polarizer deteriorates with the said water | moisture content and the display quality fell.

The polarizing plate P22 is composed of a polarizer having a thickness of 25 μm and a protective film F1. Since the thickness of the polarizer exceeds 15 μm, the amount of moisture originally contained in the polarizer is larger than that of the thin film polarizer. For this reason, even when moisture permeates from the polarizer in the substrate made of cellulose ester at high temperature, the diffusion of the moisture through the coating layer does not catch up, and as a result, the polarizer deteriorates due to the moisture, It is considered that the display quality has deteriorated.

On the other hand, in the liquid crystal display device using the polarizing plates P1 to P7 and P14 to P21, both luminance unevenness and color unevenness are not visually observed, and the evaluation is good. In any polarizing plate, the polarizer is a thin film having a film thickness of 15 μm or less, the moisture permeability of the coating layer of the protective film on the viewing side with respect to the polarizer is larger than 1 g / m ² / day, The moisture permeability of the whole film is smaller than 300 g / m ² / day, so that it is difficult for moisture from the outside to pass through the polarizer side by the coating layer. This is presumably because the light can be transmitted through the substrate made of ester and escaped to the outside through the coating layer, thereby suppressing the deterioration of the polarizer under high temperature conditions.

In particular, from the results of Tables 1 and 2, when the moisture permeability of the coating layer is 5 g / m ² / day or more and the moisture permeability of the entire protective film is 240 g / m ² / day or less, the above effect is obtained. Can be reliably obtained (see polarizing plates P3 and P6). Further, by further satisfying the condition that the film thickness of the substrate is 20 μm or less and the moisture permeability of the coating layer is 150 g / m ² / day or more, at least one of luminance unevenness and color unevenness is improved. Since it can be suppressed, it can be said that the effect of suppressing the deterioration of the polarizer is very high (refer to polarizing plates P1, P3-P5, P14, P15).

In addition, from the result of evaluation of the polarizing plate P6 using the protective film F6 and the polarizing plate P8 using the protective film F8, the lower limit of the moisture permeability of the coating layer is the moisture permeability of the coating layer of the protective film F6 (5 g / M ² / day) and the moisture permeability of the coating layer of the protective film F8 (less than 0.1 g / m ² / day) can be considered. In order to escape to the outside through the coating layer, it is sufficient that the coating layer does not have a high barrier property. From these facts, it can be said that the moisture permeability of the coating layer should be larger than 1 g / m ² / day (much larger than the value indicating high barrier properties).

Moreover, from the result of evaluation of the polarizing plate P3 using the protective film F3 and the polarizing plate P9 using the protective film F9, the upper limit value of the moisture permeability of the entire protective film is the moisture permeability (240 g / m of the protective film F3). ² / day) and an intermediate value (335 g / m ² / day) between the moisture permeability (430 g / m ² / day) of the protective film F9 can be considered. However, if the evaluation result is closer to the better side than the intermediate value, that is, the value closer to the moisture permeability of the protective film F3 (300 g / m ² / day), the evaluation result is assured. It is thought to improve.

Moreover, from the result of evaluation of the polarizing plate P4 using the protective film F4 and the polarizing plate P7 using the protective film F7, the lower limit value of the moisture permeability of the coating layer is the moisture permeability (150 g) of the coating layer of the protective film F4. / M ² / day) and the value (50 g / m ² / day) between the moisture permeability (30 g / m ² / day) of the coating layer of the protective film F7 can be considered, and more than that value If the evaluation result is a value close to a good side, that is, a value close to the moisture permeability of the protective film F4 (100 g / m ² / day), the evaluation result is considered to be surely good.

From the above, the lower limit of the moisture permeability of the coating layer is 1 g / m ² / day, preferably 5 g / m ² / day, more preferably 50 g / m ² / day, and even more preferably 100 g. / M ² / day, more preferably 150 g / m ² / day. Moreover, it can be said that the upper limit of the water vapor transmission rate of the whole protective film is 300 g / m < ² > / day, Preferably it is 240 g / m < ² > / day.

The polarizing plate, the manufacturing method of the polarizing plate, and the image display device of the present embodiment described above can be expressed as follows.

1. A polarizing plate having a polarizer and a protective film for protecting the polarizer,
The polarizer is made of a film containing polyvinyl alcohol having a film thickness of 15 μm or less,
The protective film has a base material made of cellulose ester and at least one coating layer in this order from the polarizer side,
The substrate and the polarizer are adjacent to each other,
The substrate has a thickness of 80 μm or less,
The moisture permeability of the coating layer is greater than 1 g / m ² / day,
A polarizing plate, wherein the moisture permeability of the entire protective film is smaller than 300 g / m ² / day.

2. The moisture permeability of the coating layer is greater than 50 g / m ² / day,
2. The polarizing plate as described in 1 above, wherein the protective film has a thickness of 30 μm or less.

3. The polarizing plate as described in 1 or 2 above, wherein the coating layer contains a binder component and a layered inorganic compound.

4. 4. The polarizing plate according to any one of 1 to 3, wherein the base material contains a polarizer durability improving agent.

5. 5. The polarizing plate according to 4 above, wherein the polarizer durability improving agent contains a compound represented by the following general formula (1).

6). 6. The polarizing plate as described in 4 or 5 above, wherein the polarizer durability improver comprises a compound represented by the following general formula (2).

7). The polarizing plate according to any one of 1 to 6, wherein the base material contains a specific polymer represented by the following general formula (3).

8). It further has an optical film on the side opposite to the protective film with respect to the polarizer,
The polarizing plate as described in any one of 1 to 7 above, wherein the optical film is a cellulose ester film.

9. 9. The polarizing plate as described in 8 above, wherein the optical film has a thickness of 25 μm or less.

10. 10. The polarizing plate according to any one of 1 to 9, wherein the coating layer contains fine particles formed by coating with a polymer silane coupling agent.

11. 11. The polarizing plate as described in any one of 1 to 10 above, wherein in the protective film, retardation Ro in the in-plane direction represented by the following formula is 30 nm or more.
Ro = (nx−ny) × t (nm)
However, nx represents the refractive index in the slow axis direction in which the refractive index is maximum in the in-plane direction of the protective film, and ny is in the direction orthogonal to the slow axis direction in the in-plane direction of the protective film. The refractive index is represented, and t (nm) represents the thickness of the protective film.

12 The liquid crystal cell is sandwiched between the viewing side polarizing plate and the backlight side polarizing plate,
The liquid crystal display device, wherein the viewing side polarizing plate is the polarizing plate according to any one of 1 to 11 above.

13 It is a manufacturing method of the polarizing plate in any one of said 1-11,
Using a film different from the protective film as a substrate, stretching a laminate obtained by laminating the film containing the polyvinyl alcohol on the substrate, and dyeing the film to form the polarizer;
The manufacturing method of the polarizing plate characterized by having the process of bonding the surface on the opposite side to the said board | substrate in the said polarizer on the said base material of the said protective film.

The polarizing plate of the present invention can be used for a display device such as a liquid crystal display device.

1 Liquid crystal display device (display device)
4 Liquid crystal cell 5 Polarizing plate (viewing side polarizing plate)
6 Polarizing plate (Backlight side polarizing plate)
11 Polarizer 12 Optical film (protective film)
13 Optical Film 21 Base Material 22 Coating Layer 31 Substrate

Claims

A polarizing plate having a polarizer and a protective film for protecting the polarizer,
The polarizer is made of a film containing polyvinyl alcohol having a film thickness of 15 μm or less,
The protective film has a base material made of cellulose ester and at least one coating layer in this order from the polarizer side,
The substrate and the polarizer are adjacent to each other,
The substrate has a thickness of 80 μm or less,
The moisture permeability of the coating layer is greater than 1 g / m 2 / day,
A polarizing plate, wherein the moisture permeability of the entire protective film is smaller than 300 g / m 2 / day.
The moisture permeability of the coating layer is greater than 50 g / m 2 / day,
The polarizing plate according to claim 1, wherein the protective film has a thickness of 30 μm or less.
The polarizing plate according to claim 1 or 2, wherein the coating layer contains a binder component and a layered inorganic compound.
4. The polarizing plate according to claim 1, wherein the base material contains a polarizer durability improving agent.
The polarizing plate according to claim 4, wherein the polarizer durability improver comprises a compound represented by the following general formula (1).

In general formula (1), R 1 represents a substituent, R 2 represents a group represented by the following general formula (1-2), n1 represents an integer of 0 to 4, and when n1 is 2 or more The plurality of R 1 may be the same or different from each other, n2 represents an integer of 1 to 5, and when n2 is 2 or more, the plurality of R 2 may be the same or different from each other Good.

In general formula (1-2), A represents a substituted or unsubstituted aromatic ring, and R 3 and R 4 each independently represent a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or the following general formula Represents a group represented by (1-3), R 5 represents a single bond or an alkylene group having 1 to 5 carbon atoms, X represents a substituted or unsubstituted aromatic ring, and n3 represents 0 to Represents an integer of 10, and when n3 is 2 or more, the plurality of R 5 and X may be the same or different from each other.

In the general formula (1-3), X 1 represents a substituted or unsubstituted aromatic ring, and R 6 , R 7 , R 8 , and R 9 are each independently a hydrogen atom or a carbon number of 1 to 5 N5 represents an integer of 1 to 11, and when n5 is 2 or more, a plurality of R 6 , R 7 , R 8 , R 9 and X 1 may be the same or different from each other Good.
The polarizing plate according to claim 4 or 5, wherein the polarizer durability improver comprises a compound represented by the following general formula (2).

In the general formula (2), R 26 represents an alkyl group, an alkenyl group, or an aryl group, R 27 and R 28 each independently represent a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, or a heteroaryl group, and R 29 represents a hydrogen atom. R 26 , R 27 , and R 28 may each independently have a substituent. However, at least one of R 26 , R 27 and R 28 contains an aromatic ring.
The polarizing plate according to claim 1, wherein the base material contains a specific polymer represented by the following general formula (3).

In the general formula (3), R 21 , R 22 , R 23 , and R 24 each independently represent a substituent. x represents 0 to 40 in molar ratio. y represents a molar ratio of 5 to 95. z represents a molar ratio of 0 to 70. m1 and m2 each represents an integer of 0 to 4. m3 represents an integer of 0-2. m4 represents an integer of 0 to 5. R 101 , R 102 and R 103 represent a hydrogen atom or an aliphatic group having 1 to 4 carbon atoms.
It further has an optical film on the side opposite to the protective film with respect to the polarizer,
The polarizing plate according to claim 1, wherein the optical film is a cellulose ester film.
The polarizing plate according to claim 8, wherein the optical film has a thickness of 25 μm or less.
The polarizing plate according to claim 1, wherein the coating layer includes fine particles formed by coating with a polymer silane coupling agent.
11. The polarizing plate according to claim 1, wherein in the protective film, retardation Ro in the in-plane direction represented by the following formula is 30 nm or more.
Ro = (nx−ny) × t (nm)
However, nx represents the refractive index in the slow axis direction in which the refractive index is maximum in the in-plane direction of the protective film, and ny is in the direction orthogonal to the slow axis direction in the in-plane direction of the protective film. The refractive index is represented, and t (nm) represents the thickness of the protective film.
The liquid crystal cell is sandwiched between the viewing side polarizing plate and the backlight side polarizing plate,
The liquid crystal display device, wherein the viewing side polarizing plate is the polarizing plate according to claim 1.
A method for producing a polarizing plate according to any one of claims 1 to 11,
Using a film different from the protective film as a substrate, stretching a laminate obtained by laminating the film containing the polyvinyl alcohol on the substrate, and dyeing the film to form the polarizer;
The manufacturing method of the polarizing plate characterized by having the process of bonding the surface on the opposite side to the said board | substrate in the said polarizer on the said base material of the said protective film.