WO2007013618A1

WO2007013618A1 - Heat-shrinkable polyester film and process for production thereof

Info

Publication number: WO2007013618A1
Application number: PCT/JP2006/315035
Authority: WO
Inventors: Katsuya Ito; Norimi Tabota; Katsuhiko Nose
Original assignee: Toyo Boseki Kabushiki Kaisha
Priority date: 2005-07-29
Filing date: 2006-07-28
Publication date: 2007-02-01

Abstract

[PROBLEMS] To provide a heat-shrinkable polyester film which is excellent in perforation cuttability and can form labels excellent in joint strength. [MEANS FOR SOLVING PROBLEMS] A heat-shrinkable polyester film having a structure composed of X layers containing a polyester M and Y layers containing a polyester N which are laminated alternately, characterized in that when ten 500mL labeled PET bottles obtained by applying 1,3-dioxolane to one margin on one surface of the polyester film, rolling the film up and laying the margin on top of the other margin to form a tubular film label, covering each bottle with the film label, and heating the covered bottle to 80°C for 2.5 seconds fall from the height of one meter, no PET bottle causes breakage of the film label due to delamination between X and Y layers.

Description

Specification

Heat-shrinkable polyester film and method for producing the same

Technical field

The present invention relates to a heat-shrinkable polyester film, and more particularly to a heat-shrinkable polyester film suitable for labeling applications such as PET bottles (polyethylene terephthalate (PET) bottles).

Background art

[0002] As a heat-shrinkable film, particularly a heat-shrinkable film for labeling the body of a bottle, a film having polyvinyl chloride, polystyrene or the like is mainly used. However, in recent years, the generation of chlorine-based gas has been a problem for incineration of discarded vinyl chloride products with respect to polyvinyl chloride, while the problem with polystyrene is that it is difficult to print on polystyrene film. There is. Furthermore, when collecting and recycling PET bottles, it is necessary to separate plastic labels such as polyvinyl chloride and polystyrene at the time of disposal. For this reason, polyester-based heat-shrinkable films that do not have these problems are attracting attention.

[0003] In addition to general properties such as heat shrinkability and tensile strength, heat shrinkable polyester film used as a label for bottles is required to have perforation cut ability and strength of the adhesive portion when labeling is performed. ing.

[0004] The perforation cutability is required because a perforation for opening may be provided on a bottle label. If product bottles are beverage glass bottles, they are usually refrigerated. In this case, since label opening is performed at a low temperature, there is a problem that unsuccessful opening is likely to occur, and there is a high demand for perforation cutability. In Patent Document 1, in order to improve the perforation cutting property, the temperature conditions during stretching are optimized in the manufacturing process of the heat-shrinkable polyester film. Although the perforation cutting property of the heat-shrinkable polyester film obtained by this method is somewhat improved, it is still insufficient.

[0005] As a heat-shrinkable polyester film excellent in perforation cutability, Patent Document 2 discloses a heat-shrinkable polyester film having a predetermined hot water shrinkage ratio and elongation at break. This heat-shrinkable polyester film can be used as a label on PET bottles. There was a problem that the strength of the adhesive part at the time of labeling was inferior, for example, when the plastic bottle dropped when attached, the adhesive part of the label was peeled off by impact.

[0006] Therefore, in bottle label applications, the heat-shrinkable polyester film is required to have excellent perforation cutability and strength of the adhesive portion when labeling occurs.

Patent Document 1: Japanese Unexamined Patent Publication No. 2003-268131

Patent Document 2: JP-A-11-207818

Brief Description of Drawings

FIG. 1 is a schematic view showing an example of a production line for a heat-shrinkable polyester film of the present invention.

[Fig. 2] TEM photograph of film imported into image analysis software.

FIG. 3 is an image after the Fourier transform of FIG.

4 is an image after the inverse Fourier transform of FIG.

FIG. 5 is an image after clearing the shading of FIG.

Disclosure of the invention

Problems to be solved by the invention

[0008] In view of the above circumstances, the problem to be solved by the present invention is to provide a heat-shrinkable polyester film excellent in perforation cutting properties and strength of an adhesive portion at the time of labeling.

Means for solving the problem

[0009] The heat-shrinkable polyester film of the present invention that has been able to solve the above-described problems is a heat shrinkable structure in which an X layer containing a polyester component M and a Y layer containing a polyester component N are alternately laminated. A shrinkable polyester film, which is coated with 1,3-dioxolan slightly inside from one edge of one end of the film, rolled up and overlapped to form a tubular film label, When a film label is coated on a 500 mL PET bottle, heated at 80 ° C for 2.5 seconds and then attached, and when 10 PET bottles are dropped even at a height of lm, all 10 PET bottles It is characterized in that the film label is not damaged due to peeling from the Y layer. The heat-shrinkable polyester film of the present invention comprises polyester component M 1S polyester A 70 to 99% by mass and polyester Bl 30% by mass contained in the X layer, and polyester component N force polyester B 70 to 99% contained in the Y layer. ^_0/0 and a is a preferred embodiment comprises a polyester a 1 to 30 wt%. Further, it is preferable that the X layer and the Y layer have a structure in which 500 layers or more are alternately laminated.

The heat-shrinkable polyester film of the present invention has a heat shrinkage ratio of 50% or more in the main shrinkage direction after being immersed in warm water of 95 ° C ± 0.5 ° C for 10 seconds, and has a solvent adhesive strength of 2.0 N. / 15 mm or more, tear propagation strength is 2. ON or less, and the thickness after breaking into hot water at 60 ° C ± 1 ° C for 30 minutes is 20 MPa or more. Thickness is 5 to: L00 μm It is also expressed as a heat-shrinkable polyester film.

The heat-shrinkable polyester film of the present invention is suitable for a bottle label, and a bottle label using the heat-shrinkable polyester film of the present invention is also included in the present invention. The heat-shrinkable polyester film of the present invention comprises a polyester component M containing 70 to 99% by weight of polyester A and 30 to 30% by weight of polyester Bl, and a polyester component containing 70 to 99% by weight of polyester B and 30 to 30% by weight of polyester Al. N is fed into separate extruders E and F, respectively, and melted. Polyester components M and N in a molten state are fed into a laminating apparatus to obtain a laminated body of polyester components X and Y. The laminated body is guided from the laminating apparatus to a slit die so that it takes 45 seconds to 10 minutes until the force is discharged from the laminating apparatus and the force comes into close contact with the cooling roll. The unstretched sheet can be produced by a method characterized by stretching at least uniaxially, and this method is also included in the present invention.

The invention's effect

According to the present invention, a heat-shrinkable polyester-based film having general characteristics of heat-shrinkable polyester film such as heat-shrinkability and tensile strength, and having excellent perforation cutability and strength of an adhesive portion at the time of labeling. A film is provided. When the film of the present invention is a full-bottle label, it is easy to peel off the label even at low temperatures, causing a problem of label breakage when a beverage product in a PET bottle falls to the outlet with a vending machine. It can be used favorably as a label for bottles with a long gap. BEST MODE FOR CARRYING OUT THE INVENTION

[0011] The present invention relates to a heat-shrinkable polyester film having a structure in which an X layer containing a polyester component M and a Y layer containing a polyester component N are laminated in a force alternating fashion, on one side of the film. Apply 1,3-dioxolan slightly inward from the edge, roll the film and overlap the edges to form a tube-shaped film label, and cover the film label on a 500 mL PET bottle at 80 ° C. 2. If the PET bottle is heated and attached for 5 seconds and dropped from the height of lm, the film label will be damaged due to the peeling between the X layer and the Y layer for all 10 PET bottles. This is a heat-shrinkable polyester film characterized by the absence of the heat-shrinkable polyester film.

[0012] The heat-shrinkable polyester film of the present invention has a structure in which X layers and Y layers are alternately laminated, and the X layers and Y layers are composed of different polyester components (polyester components M and N). The

[0013] The polyester components M and N can be selected to meet the object of the present invention in any combination as long as they have different thermal characteristics. It is preferable that the difference between the glass transition temperatures of the polyester components M and N is 3 ° C. or more and 100 ° C. or less and the difference in crystal heat of fusion is 5 jZg or more and 100 J Zg or less. Polyester component M is a crystalline polyester component having a glass transition temperature measured by DSC of −50 ° C or more and less than 60 ° C and a heat of crystal melting of 5jZg or more and lOOjZg or less, and polyester component N is More preferably, it is a substantially amorphous polyester component having a glass transition temperature of 60 ° C. or higher and 150 ° C. or lower and a heat of crystal melting of OjZg or higher and 3jZg or lower. The starting polyester components M and N may be either homopolymers or copolymers, and may be a polyester composition containing two or more arbitrary polyesters.

[0014] Preferred combinations of the polyester component M and N, wherein the polyester component M power Po Riesuteru A70~99 mass ^_0/0 and polyester Bl~30 mass ^_0/0, the polyester component N is polyester B70~99 wt% And polyester Al to 30% by mass is preferable. Also includes B3~27 wt% polyester component M force polyester A73~97 mass ^_0/0 and polyester, and more preferably contains B73~97 wt% polyester component N force polyester Oyobi polyester A3~27 wt%. In addition, police Include ether components M force polyester A75~94 wt% and the polyester B6~25 mass ^_0/0, most preferred to contain B75~94 wt% polyester component N force polyesters and polyester A6 to 25 wt%.

[0015] The polyester components M and N are preferably used in a mass ratio (polyester component MZN) of 97Z3 to 3Z97. If the mass ratio is outside this range, it becomes difficult to form a layer structure, and it becomes difficult to simultaneously achieve a heat shrinkage ratio of 60% or more at 95 ° C and a tear strength of 2. ON or less. There is a fear.

In addition, the polyester components M and N are used in a mass ratio (polyester component MZN) of 90/10 to 10/90, more preferably force S, and used in 85/15 to 60/40 or 40/60 to 15 Z85. Most preferably.

Here, examples of polyester A include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polypentamethylene terephthalate, polyhexamethylene terephthalate, polyethylene 2, 6 naphthalate. Crystalline polyester such as (PEN) can be used. Further, based on these, an acid component and Z or glycol component described later may be copolymerized with 10 mol% or less in 100 mol% of the acid component and Z or glycol component. Further, the polyethylene terephthalate (PET) base, 10 moles dimer acid ^_0/0 those following copolymer (PET-D) and a polyethylene one 2, 10 moles of isophthalic acid to 6-naphthalate (PEN) ^_0/0 Those copolymerized below can also be used. More preferred are PBT, PTT and PET. It is.

[0017] Polyester B is, for example, based on polyester having terephthalic acid as the acid component and diethylene glycol power as the glycol component, and 5 mol% or more, preferably 6 mol% or more in 100 mol% of the acid component and / or the diol component. A copolymer obtained by copolymerizing different dicarboxylic acid components and Z or glycol components of less than 40 mol% can be used. Specific monomer components include, for example, dicarboxylic acid components such as aromatic dicarboxylic acids such as isophthalic acid, naphthalenedicarboxylic acid, and orthophthalic acid, and aliphatic dicarboxylic acids such as adipic acid, azelaic acid, sebacic acid, and decanedicarboxylic acid. Acid, and alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid. Glico Examples of the amine component include aliphatic diols such as propanediol, butanediol, neopentylglycol, and hexanediol; alicyclic diols such as 1,4-cyclohexanedimethanol, and aromatic diols.

Polyester B is preferably composed of terephthalic acid as the acid component and 7 to 35 mol% of neopentyl glycol and Z or 1,4-cyclohexanedimethanol based on polyester having diethylene glycol strength as the glycol component. It is a copolymerized polyesterol.

[0018] The heat-shrinkable polyester film of the present invention has a structure in which X layers and Y layers are alternately laminated. As the number of X layers and Y layers to be laminated, the number of X layers and Y layers is More preferably, the total is 500 or more, more preferably 1,000 to 100,000, and most preferably 2,000 to 10,000. When the total of the X layer and the Y layer is 500 layers or more, the perforation cutting property is particularly excellent.

The outermost layer of the heat-shrinkable polyester film may be either the X layer or the Y layer.

In order to measure the number of laminated films, the X- and Y-layers are dyed separately, and then the film cross-section is observed by TEM. However, as the number of layers increases, it becomes difficult to visually count even if the magnification of the TEM image is increased. Therefore, in this case, as will be described in detail later, the method of obtaining the number of layers by using the image analysis software to clearly show the degree of shading of the image and then numerically (binarizing) it was adopted.

For the X layer and the Y layer, conventionally known additives, for example, organic particles (eg, bridge acrylic particles, crosslinked styrene particles, silicone particles, etc.), inorganic particles (eg, silica, kaolin) Contains phosphorus, clay, calcium carbonate, aluminum oxide, barium sulfate, zinc oxide, zinc sulfide, etc.), lubricant, stabilizer, colorant, antioxidant, antifoaming agent, antistatic agent, UV absorber, etc. May be.

[0020] Further, in the heat-shrinkable polyester film of the present invention, 1,3-dioxolane is applied slightly inside from one edge of one end of the film, the film is rolled up and the ends are overlapped to form a tube. The film label was covered with a 500mL plastic bottle, heated at 80 ° C for 2.5 seconds, and 10 plastic bottles dropped with a height of lm. In this case, the film label is not damaged due to peeling between the X layer and the Y layer for all the 10 PET bottles.

[0021] Specifically, using a tube forming apparatus, 1,3-dioxolan is applied in a width of 2 ± lmm slightly inward from the edge of one side of the film (application amount: 3.0 ± 0. 3g / m ^2). Immediately roll up the film and overlap the edges to bond them together to create a tube-shaped film label. The size of the tube-shaped film label is not limited as long as it can be mounted on a 500 mL plastic bottle without any strain. As a guideline for the size of the film label, the folding diameter is 109 mm and the label length is about 90 mm.

[0022] The label is provided with perforations according to the actual product form. For example, by using a sewing blade, holes with a length of 0.2 to 2. Omm are arranged at intervals of 0.2 to 1. Omm along the direction perpendicular to the main shrinkage direction of the label. Provide one or two perforations of length.

[0023] Continue! Coat the film on a 500 mL PET bottle (round shape, barrel diameter 62 mm, minimum neck diameter 25 mm) and pass through the tubular film label using a steam tunnel 2. Attach to a 500 mL PET bottle by heat shrinking at a zone temperature of 80 ° C for 5 seconds.

[0024] When ten PET bottles equipped with this label are prepared and dropped from the height of lm, the film label is damaged due to peeling between the X layer and the Y layer for all 10 bottles. This is essential for the present invention. Film labels that do not break during such a drop test, in particular, do not cause the problem of label breakage when a beverage product in a PET bottle falls to the outlet in a vending machine.

Here, the film label breakage due to the peeling between the X layer and the Y layer is, for example, that the label is peeled off due to the delamination between the X layer and the Y layer, particularly in the solvent adhesion portion. It is done.

[0025] The heat-shrinkable polyester film as described above has a heat shrinkage ratio of 50% or more in the main shrinkage direction after being immersed in warm water at 95 ° C for 5 seconds, and a solvent adhesive strength of 2.0 NZl5 mm or more. Yes, the tear propagation strength is 2. ON or less, and the fracture strength after immersion for 30 minutes in 60 ° C warm water is 20 MPa or more. In the present invention, the problem to be solved by the present invention can be solved by the heat-shrinkable polyester film having such characteristics. I found out.

[0026] (heat shrinkage rate)

The heat-shrinkable polyester film of the present invention has a hot-water heat shrinkage force when immersed in hot water at 95 ° C ± 0.5 ° C for 10 seconds under no load condition. % Or more. If the heat shrinkage rate is less than 50%, the label may not be properly attached to the container due to insufficient heat shrinkage force. The heat shrinkage rate is preferably 55% or more, more preferably 60% or more. In particular, when the heat shrinkage rate is 60% or more, it is very easy to attach a label even on a difficult part such as a shoulder of a bottle. On the other hand, the upper limit of the thermal shrinkage rate is a technical limit of 98%, preferably 90% or less, more preferably 85% or less. In particular, when the heat shrinkage rate is 85% or less, the occurrence of label jumping due to the excessively large shrinkage force of the label when the bottle is heated and shrunk over the bottle is extremely suppressed.

In addition, the heat-shrinkable polyester film of the present invention has a hot-water heat shrinkage rate in the main shrinkage direction when immersed in hot water at 70 ° C ± 0.5 ° C for 10 seconds under no load! Thus, it is preferably 10% or more and 50% or less. If the heat shrinkage rate is less than 10%, the shrinkability is insufficient and the shrinking process needs to be performed at a higher temperature. When the thermal shrinkage rate exceeds 50%, a label jumping phenomenon may occur when the bottle is covered with a bottle and heated and shrunk, because the shrinkage force of the label is too large.

[0027] Here, the hot water heat shrinkage ratio is measured by measuring the length of the film before and after the dipping treatment, (length before shrinkage, length after shrinkage) Z length before shrinkage) X 100 (%) This is the value obtained from the formula. In addition, the main shrinkage direction is a direction in which the hot water heat shrinkage rate is high in the longitudinal direction and the transverse direction.

In addition, when measuring the heat shrinkage rate, in order not to give the film an excessive heat history, after immersion in warm water at a predetermined temperature for a predetermined time, water at 25 ° C ± 0.5 ° C is used. The film should be soaked in to cool the film.

[0028] The heat-shrinkable polyester film of the present invention has a characteristic that the solvent adhesive strength is 2.0 NZl 5 mm or more. The solvent adhesive strength is preferably 2.5 to 20 NZl5 mm. 2. 8 to: LON / 15 mm is preferable. Here, the solvent adhesive strength is as follows. This is the value obtained in this way.

[0029] Apply 1, 3-dioxolan with a width of 2 ± lmm slightly inward from the edge of one side of the film (coating amount: 3.0 ± 0.3 gZm ² ). Overlap, bond and process into a tube (processing speed: lOmmZ). Cut this tube so that the bonding point is in the center, and then cut out a film-like test piece (n = 10) with a length of 100 mm and a width of 15 mm so that the bonding point is in the center. Set this film specimen on a tensile tester (Boldwin's “STM-T”) with the distance between chucks set to 50 mm so that the solvent adhesion part is located at the center of the chucks, and the temperature is 23 °. C. Tensile test is performed under the condition of 200mm Z for the tensile speed, and the peel strength of the bonded part is measured. This peel strength is the solvent adhesive strength.

[0030] The heat-shrinkable polyester film of the present invention has a characteristic that the tear propagation strength is 2.0 N or less. The tear propagation strength is preferably 0.2 to 1.9 N, and more preferably 0.5 to 1.8 N.

Here, the tear propagation strength is based on JIS K7128-2 (1998). A film that has been shrunk 10% at 85 ° C in advance to 5 lmm x 64 mm is manufactured by Toyo Seiki Seisakusho Co., Ltd. The value obtained by measuring with a light load tear tester.

[0031] The heat-shrinkable polyester film of the present invention has a characteristic that the breaking strength after immersion for 30 minutes in warm water of 60 ° C ± 1 ° C is 20 MPa or more. The breaking strength is preferably 30 to 200 MPa, more preferably 40 to 150 MPa. Here, the breaking strength is a value obtained as follows.

[0032] Folded diameter 87.5mm X Label length 120mm film label is put on a 250mL steel can (outer diameter 53mm, height 133mm) and immersed in hot water at 80 ° C for 10 seconds to put the label in the can Wear shrinkage (about 5% shrinkage). Immediately transfer the labeled steel can into warm water of 60 ° C ± 1 ° C and soak for 30 minutes. Cut the sample from the steel can label, and film before heat treatment according to JIS-K-7127 (1999) (test piece is type 2. However, distance between chucks: 20mm, pulling speed: 200mmZ) Conduct a tensile test in the direction perpendicular to the maximum shrinkage direction. The test piece size is 100 mm long (in the direction perpendicular to the maximum film shrinkage direction) and 15 mm wide. mm, temperature 23 ° C, tensile speed 200mmZ. The strength at the time of rupture during the test is the breaking strength.

[0033] The heat-shrinkable polyester film used in the present invention preferably has a melt specific resistance at a temperature of 275 ° C of 0.70 to 10 ⁸ Ω'cm or less. When such a film is used, as will be described in detail below, the uniformity of the film thickness can be improved, and the printability on the film and the workability when processing the film into a form that can be mounted on a container. (Stable workability) can be improved.

That is, in the present invention, when the film melted and extruded by an extruder is cooled by a conductive cooling roll (such as a casting roll), an electrode is disposed between the extruder and the casting roll, and the electrode, the casting roll, A voltage is applied between them (that is, the electrode force also applies electricity to the film), and the film is electrostatically adhered to the roll. When the melting specific resistance value is small, the adhesion between the film and the roll (electrostatic adhesion) can be enhanced. If the electrostatic adhesion to the roll is low, the thickness of the cast unstretched film becomes non-uniform, and the thickness non-uniformity is further expanded in the stretched film obtained by stretching the unstretched film. On the other hand, when the electrostatic adhesion is sufficiently high, the thickness can be made uniform even in the stretched film.

When the uniformity of the film thickness is increased, color misregistration can be prevented and printability can be improved when multicolor printing in which a plurality of colors are superimposed is applied to the film.

[0036] In addition, if the uniformity of the film thickness is increased, the bonded portions can be easily overlapped even when the film is processed into a tube or the like by solvent bonding. When multi-color printing is performed on the film, the film can be prevented from becoming wrinkled easily, and the film can be prevented from meandering during running, thereby improving workability (stable workability). it can.

[0037] When the uniformity of the film thickness is further increased, it is possible to prevent partial differences in winding hardness when the film is wound in a roll shape, and the film is loosened and wrinkled, resulting in an appearance of the film. It can be prevented from being greatly damaged.

[0038] It should be noted that, when the electrostatic resistivity is increased by lowering the melt specific resistance value, the film productivity can be increased as well as the uniformity of the film thickness, and the appearance of the film can also be improved. In other words, high electrostatic adhesion improves the stability of film cooling and solidification. The casting speed (production speed) can be increased. In addition, if the electrostatic adhesion is high, the film is incompletely cooled and solidified, and air is locally introduced between the roll and the film, resulting in pinner bubbles (streaky defects) on the film surface. Can be prevented and the film appearance can be enhanced.

[0039] The melting specific resistance value is preferably 0.65 X 10 ⁸ Ω'cm or less, more preferably 0.60.

Χ 10 ⁸ Ω · «is less than or equal to η.

[0040] In order to control the melt specific resistance value within the above range, it is desirable to contain an alkaline earth metal compound and a phosphorus-containing compound in the film. The melting specific resistance value can be lowered by using only the alkaline earth metal compound, but the melting specific resistance value can be remarkably lowered by the presence of the phosphorus-containing compound. It is not clear why the specific resistance of the melt can be significantly lowered by combining the alkaline earth metal compound and the phosphorus-containing compound. It is estimated that the amount of charge carriers can be increased.

[0041] The content of the alkaline earth metal compound in the film is, for example, 20 ppm (mass basis) or more, preferably 40 ppm (mass basis) or more, based on the alkaline earth metal atom ² . Preferably it is 50 ppm (mass basis) or more, particularly 60 ppm (mass basis) or more. If the amount of the alkaline earth metal compound is too small, the melting specific resistance value cannot be lowered. Even if the content of the alkaline earth metal compound is excessively increased, the effect of reducing the melt specific resistance value is saturated, and rather adverse effects such as generation of foreign matter and coloring are increased. The content of this reason alkaline earth metal compound, based on the alkaline-earth metal atom M ^2, for example, 400pp m (by mass) or less, preferably 350 ppm (mass basis) or less, more preferably 300 ppm (mass basis) It is as follows.

[0042] The content of the phosphorus compound in the film is, for example, 5 ppm (mass standard) or more, preferably 20 ppm (mass standard) or more, more preferably 40 ppm (mass standard) or more, based on the phosphorus atom P. Especially 60ppm (mass basis) or more. If the amount of the phosphorus compound is too small, the melting specific resistance value cannot be lowered sufficiently, and the amount of foreign matter generated cannot be reduced. Even if the content of the phosphorus compound is increased too much, the effect of reducing the melt specific resistance value is saturated. Furthermore, it promotes the production of diethylene glycol, and the force also controls the amount of production. Since it is difficult to trawl, the physical properties of the film may be different from what was planned. Therefore, the phosphorus compound content is, for example, 500 ppm (mass basis) or less, preferably 450 ppm (mass basis) or less, more preferably 400 ppm (mass basis) or less, particularly 350 ppm (mass basis), based on the phosphorus atom P. It is as follows.

[0043] In the case of lowering the melt specific resistance value of an alkaline earth metal compound and phosphorus compound, the mass ratio (M ² ZP) of the alkaline earth metal atom M ² and phosphorus atom P in the film is 1 It should be 2 or more (preferably 1.3 or more, more preferably 1.4 or more). By setting the mass ratio (M ² ZP) to 1.2 or more, the melting specific resistance can be significantly reduced. When the mass ratio (M ² ZP) exceeds 5.0, the amount of foreign matter generated increases or the film is colored. Therefore, the mass ratio (M ² ZP) is 5.0 or less, preferably 4.5 or less, and more preferably 4.0 or less.

[0044] In order to further reduce the melt specific resistance value of the film, it is desirable to contain an alkali metal compound in the film in addition to the alkaline earth metal compound and the phosphorus-containing compound. Alkali metal compounds cannot lower the melt resistivity even if they are contained alone in the film, but by adding them to the coexistence system of alkaline earth metal compounds and phosphorus-containing compounds, the melt resistivity can be reduced. Can be significantly reduced. Although the reason for this is not clear, it is presumed that the melting specific resistance value is lowered by forming a complex of the alkali metal compound, the alkaline earth metal compound, and the phosphorus-containing compound.

[0045] The content of the alkali metal compound in the film, based on the alkali metal atom M ^1, for example, Oppm (mass basis) or more, preferably 5 ppm (mass basis) or more, more preferably 6 ppm (mass basis) Above, especially 7ppm (mass basis) or more. Even if the content of the alkali metal compound is excessively increased, the effect of reducing the melt specific resistance value is saturated, and further, the amount of foreign matter generated is increased. The content of this reason the alkali metal compound, based on the alkali metals atom M ^1, for example, LOOppm (mass basis) or less, preferably 90 ppm (mass basis) or less, still more preferably not more than 80 ppm (by weight) .

[0046] Examples of the alkaline earth metal compound include an alkaline earth metal hydroxide, alkoxide, aliphatic carboxylate (acetate, butyrate, etc., preferably acetate), and aromatic carboxylate (benzoic acid). Acid salt), a salt with a compound having a phenolic hydroxyl group (such as a salt with phenol). Etc.). Examples of the alkaline earth metal include magnesium, calcium, strontium, norium (preferably magnesium). Preferred alkaline earth metal compounds include magnesium hydroxide, magnesium methoxide, magnesium acetate, calcium acetate, strontium acetate, barium acetate and the like, in particular magnesium acetate. The alkaline earth metal compounds can be used alone or in combination of two or more.

[0047] Examples of the phosphorus compound include phosphoric acids (phosphoric acid, phosphorous acid, hypophosphorous acid, etc.), esters thereof (alkyl esters, aryl esters, etc.), alkyl phosphonic acids, aryl phosphones. Examples thereof include acids and esters thereof (alkyl esters, aryl esters, etc.). Preferred phosphoric acid compounds include phosphoric acid, aliphatic esters of phosphoric acid (alkyl esters of phosphoric acid, etc .; for example, phosphoric acid monomethyl esters, phosphoric acid monoethyl esters, phosphoric acid monobutyl esters, etc. Alkyl ester, dimethyl phosphate

1-6

Di-C alkyl phosphates such as stealth, jetyl phosphate, dibutyl phosphate

1-6 ester, trimethyl phosphate, triethyl ester phosphate, tri-C phosphate ester such as tributyl ester), phosphoric acid aromatic ester (phosphate phosphate)

1-6

Such as phosphoric acid, tricresyl phosphate, or tri-C aryl ester.

6-9

), Aliphatic esters of phosphorous acid (alkyl esters of phosphorous acid, etc .; for example, phosphorous acid compounds such as trimethyl phosphite, tributyl phosphite, or tri C alkyl ester

1-6

Nore), anorequinolephosphonic acid (methinorephosphonic acid, ethenorephosphonic acid, etc.)

1-6 alkylphosphonic acid), alkylphosphonic acid alkyl esters (mono- or di-C alkyl ethers of C alkylphosphonic acids such as dimethyl methylphosphonate, dimethyl ethylphosphonate)

1-6 1-6

Stearyl, etc.), aryl phosphonic acid alkyl esters (mono- or di-C alkyl ethers of C allylic phosphonic acids such as dimethyl phosphophosphonate, jetyl phosphophosphonate)

6-9 1-6 steal, etc.), aryl phosphonic acid aryl ester (mono- or di-C aryl ester of C arylphosphonic acid such as diphosphorus phosphonic acid) etc.

6-9 6-9

The Particularly preferred phosphorus compounds include phosphoric acid and trialkyl phosphates (such as trimethyl phosphate). These phosphorus compounds can be used alone or in combination of two or more.

[0048] Examples of the alkali metal compounds include alkali metal hydroxides, carbonates, and aliphatic carbonates. Bonates (acetate, butyrate, etc., preferably acetate), aromatic carboxylates (benzoate), salts with compounds having a phenolic hydroxyl group (such as salts with phenol), etc. It is. Examples of the alkali metal include lithium, sodium, potassium and the like (preferably sodium). Preferred alkaline earth metal compounds include lithium hydroxide, sodium hydroxide, potassium hydroxide, lithium carbonate, sodium carbonate, potassium carbonate, lithium acetate, sodium acetate, potassium acetate and the like, especially sodium acetate.

[0049] The thickness of the heat-shrinkable polyester film of the present invention,. 5 to: LOO mu m is preferably 20 to 50 111 mosquitoes ^ Yori preferably 1ヽ₀

[0050] The heat-shrinkable polyester film of the present invention can be labeled by a conventionally known method. As an example, a suitable film is applied to a heat-shrinkable polyester film cut to a desired width, and a film film is manufactured by overlapping and bonding the left and right ends of the film by solvent adhesion or the like. The tube film is cut into an appropriate length to obtain a tube-shaped label. Alternatively, one opening of this tubular label is joined to form a bag-like label.

These labels are then perforated by a conventional method, and then covered with a plastic bottle. The plastic bottle is placed on a belt conveyor and the like, and steam is blown into the shrink tunnel (steam tunnel) or hot air. The inside of a contracting tunnel (hot air tunnel) that blows air. The label is attached to a bottle container such as a plastic bottle by heat shrinking when passing through these tunnels.

[0051] Next, a method for producing the heat-shrinkable polyester film of the present invention will be described.

Do particular limitation on the method for producing heat-shrinkable polyester film of the present invention, but, for example, polyester Le component containing A70~99 wt% polyester and polyester Bl~30 wt% M, and polyester B70~99 mass ⁰ / ₀ and polyester component N containing polyester Al~30 mass ^_0/0 melt was poured into separate extruders E and F, respectively, the polyester component by introducing a polyester component M and N of molten state in the stacking device M And the laminate is led from the laminating apparatus to the slit die so that the time from when the laminated body is discharged from the laminating apparatus until it comes into close contact with the cooling roll is 45 seconds to 10 minutes. Extruded into a roll to obtain an unstretched sheet, and the unstretched sheet is stretched at least uniaxially (An example of a production line is shown in Fig. 1).

[0052] Hereinafter, more specifically, the polyester as a raw material is first dried using a dryer such as a hopper dryer, a paddle dryer, or a vacuum dryer.

[0053] A predetermined amount of polyester A and polyester B are mixed to prepare polyester component M and polyester component N. As a method for mixing polyester, a chip blend method, a master batch method and the like, which are not particularly limited, can be employed. It is known that even when two or more polyester components are blended, there is a strong tendency to transesterify and copolymerize due to the heat history during melt extrusion.

Polyester component M and polyester component N are charged into separate extruders E and F, respectively, and melted. The melting temperature is not particularly limited as long as it does not cause deterioration or alteration for each of the fats and oils. As an index, when the composition exhibits crystallinity, the melting point + (5 ° C to 30 ° C), and when amorphous, the softening temperature + (20 ° C to 150 ° C) It is preferable.

[0054] The melted polyester components M and N are guided to the laminating apparatus while being in a molten state, and a stacked body is formed. Examples of the laminating apparatus include a feed block, a multi-hold die, and a static mixer. Of these, the stacking of several hundred layers can be easily achieved, so it is more preferable to use a combination of a feed block and a static mixer, which are preferable to use a static mixer.

[0055] The static mixer in the present invention is an element having a shape in which a horizontally long rectangular plate is twisted and bent so that an angle (torsion angle) between its short sides is 45 degrees to 270 degrees. The in-pipe mixing device arranged alternately so that the short sides of adjacent elements intersect. When molten resin passes through one element, the resin is divided into two layers, and each resin layer is twisted in the direction opposite to the swivel direction of the element. In addition, when passing through the next element, the splitting and twisting of the resin occurs in the same way, and it is divided into four layers. Therefore, when the resin component M and the resin component N are laminated one by one and introduced into the static mixer, theoretically, if the short side of the first element is horizontal to the lamination surface, n When passing through the elements of the 2 ⁿ layers, actually force the short side of the first element is 2 ^{n + 1} layer as long perpendicular to the laminated surface, the passage diameter and length, torsional angle of the elements, the torsional gradient, Effervescent oil discharge amount, each oil It may change due to the influence of melting characteristics such as viscosity and surface tension.

The LZD (pipe length Z pipe inner diameter) ratio of the static mixer element is preferably in the range of 1.0 to 3.0, more preferably in the range of 1.4 to 2.0. If the L / D ratio is less than 1.0, the efficiency of dividing the resin deteriorates, and if it exceeds 3.0, the residence time of the resin passing through the mixer becomes longer, which is not practical.

The torsion angle of the static mixer element shall be 45 degrees or more. This is because if the twist angle is less than 45 degrees, the twist of the resin layer is insufficient. The twist angle is more preferably 90 ° or more, and more preferably 135 ° or more. The upper limit of torsion angle should be 315 degrees. If it exceeds 315 degrees, a uniform laminated structure cannot be obtained due to excessive twisting. The twist angle is preferably 270 degrees or less, more preferably 215 degrees or less. Note that the fact that a uniform laminated structure cannot be obtained means that the laminated structure is disturbed, for example, the laminated layers are wavy.

In addition, when the side surface of the static mixer pipe is cut and expanded in the direction of grease movement, the angle formed by the straight line that follows the joint between the pipe inner wall and the element and the direction of grease movement, that is, the torsional gradient of the element is 27 degrees or more is preferable. If this twist gradient is less than 27 degrees, the LZD ratio must be increased in order to give sufficient twist to the resin with less twisting effect of the resin layer, which is not practical. The torsional gradient is more preferably 38 degrees or more, and more preferably 42 degrees or more. On the other hand, when the torsional gradient exceeds 65 degrees, the turbulent flow of the resin becomes violent and the laminated structure is disturbed. The twist gradient is more preferably 54 degrees or less, and further preferably 50 degrees or less.

The preferred shape of the elements of the static mixer can be appropriately selected according to the discharge amount and melting characteristics of the resin, and the shape varies depending on the change of the melting characteristics of the resin passing through the static mixer. A plurality of elements can also be used in combination. The most preferred elements are those with L / D = l.5, twist angle 180 degrees, and twist gradient 46 degrees. The arrangement of the elements of the static mixer is preferably changed alternately so that the twisting directions of the elements are right turn, left turn, and right turn. This is because a uniform laminated structure can be obtained. It is also preferable to arrange adjacent elements so that they intersect at right angles in order to obtain a uniform laminated structure.

The number of static mixer elements is preferably 4 or more, more preferably 6 or more. More preferably, it is 8 or more. The film of the present invention has a laminated structure, and the number of layers is particularly preferably 500 or more as will be described later. When the number of elements is 8 or more, a laminated structure of 500 or more layers is ensured. Easy to obtain. On the other hand, if the number of elements becomes too large, the laminated structure tends to be disturbed. Therefore, the number of elements is preferably 24 or less, more preferably 18 or less, and more preferably 14 or less. Is more preferable.

For example, when the mass ratio of the polyester component is 8Z2 (MZN), the number of elements is preferably 8 to 14, and particularly preferably 10 to 12 forces! / ヽ.

The structure of the static mixer described above is one typical example, and the shape and arrangement can be changed without departing from the object of the present invention, and another apparatus can be arranged before and after the static mixer and between the elements. Of course, it is possible. For example, two or more rows of static mixers smaller in diameter than the resin piping may be arranged in parallel in the piping. It can be obtained by laminating a mixture of the resin component M and the component N of the resin component N by passing through a static mixer and further mixing another resin.

In addition, it is possible to use a plurality of feed blocks and laminate the laminated resin laminated in three or more layers to a static mixer for further multilayering. In this case, the force that can reduce the number of elements in the static mixer by the number of layers in the feed block. The unique effects of the film (such as improved perforation opening) caused by the lamination in the static mixer are small. For this reason, the number of stacked feed blocks is preferably within 100 layers.

[0056] The temperature of the laminating apparatus (static mixer or the like) is as follows: melting point + (5 ° C to 30 ° C) when the composition exhibits crystallinity, softening temperature + Most preferably, it should be set to (20 ° C to 150 ° C).

[0057] This laminate is extruded through a slit die such as a T-die and is brought into close contact with a cooling tool having a surface temperature of 10 to 40 ° C to obtain an unstretched sheet. When the laminated body is extruded from the slit die to the cooling roll, the laminated body is discharged from the laminating device (the last device that performs laminating when multiple laminating devices are used) until it comes into close contact with the force cooling roll. Time (for example, in Fig. 1, the stack is discharged from the static mixer 4 and then extruded from the T die 5 to The time until the laminate adheres to the handle 6) is 45 seconds to 10 minutes, preferably 1 to 8 minutes, and more preferably 1.5 to 5 minutes. By keeping the time from when the laminate is discharged from the laminating apparatus until it comes into close contact with the force cooling roll within the above range, damage to the label film due to peeling between the X layer and Y layer can be prevented. The strength of the label adhesion portion is ensured. The fact that the stacked body is in close contact with the cooling roll means that the laminate is in surface contact with the cooling roll in the entire width direction. For example, when the electrostatic contact method is adopted, the laminated body extruded from the die first comes into surface contact with the cooling roll when the cooling roll rotates as a force that makes contact with the cooling roll in the entire width direction. The starting point of the surface contact appears as a line that is formed when the contact points between the cooling roll and the laminate are continuously arranged in the width direction. Therefore, consider the moment when this line appears as the point of contact with the cooling roll.

As a method of adjusting the time from when the laminate is discharged to the force cooling roller, the stacking device force can be increased by, for example, increasing the flow path to the slit die, or causing the laminate to stay in the path. The method is mentioned.

[0058] Next, the obtained unstretched sheet is preheated at 50 to 120 ° C, preferably 60 to 100 ° C, if necessary, and then stretched in the transverse direction (direction perpendicular to the extrusion direction) with a tenter. Stretched to 0 times or more, preferably 3.5 times to 15 times. The stretching temperature is 60 ° C or higher and 120 ° C or lower, preferably 70 ° C or higher and 100 ° C or lower. Although it is not always necessary to perform longitudinal stretching before and after transverse stretching, longitudinal stretching may be performed as necessary.

[0059] Further, if necessary, heat treatment is performed at a temperature of 70 to 100 ° C to obtain a heat-shrinkable polyester film. The film may be made into a film roll by winding it according to a conventional method.

[0060] Note that the stretching method may be biaxial stretching by additionally stretching in the machine direction in addition to transverse monoaxial stretching with a tenter. Such biaxial stretching may be performed by any of the sequential biaxial stretching method and the simultaneous biaxial stretching method, and may be re-stretched in the longitudinal direction or the transverse direction as necessary.

[0061] In addition, when the film is stretched, if the fluctuation range of the surface temperature of the film is reduced (soaking), the film can be stretched and heat-treated at the same temperature over the entire length of the film, and the thickness distribution value and heat The shrinkage behavior can be made uniform. [0062] The fluctuation range of the surface temperature is a temperature force at each point when the surface temperature of the film is measured at an arbitrary point. For example, it is preferable that the average temperature of the film is within about ± 1 ° C. More preferably, the temperature is within ± 0.6 ° C.

[0063] When the film is stretched, the film is stretched through various processes such as a preheating process before stretching, a stretching process, a heat treatment process after stretching, a relaxation process, and a restretching process process. It is preferable to use equipment that can reduce (homogenize) the fluctuation range of the surface temperature of the film partially or entirely. In particular, in order to make the thickness distribution value uniform over the entire length of the film, the fluctuation range of the surface temperature of the film can be reduced in the preheating step and the stretching step (and in the heat treatment step after stretching if necessary). It is preferable to use equipment. In order to make the heat shrinkage rate uniform, it is preferable to use equipment capable of reducing the fluctuation range of the surface temperature of the film in the stretching process.

[0064] Examples of the equipment that can reduce the fluctuation of the film surface temperature include, for example, equipment equipped with a wind speed control means (such as an inverter) for controlling the supply speed of hot air for heating the film, and stably supplying air. Examples include equipment equipped with heating means for heating to prepare the hot air [heating means using low-pressure steam of 500 kPa or less (5 kgf Zcm ² or less) as a heat source].

[0065] In order to achieve the object of the present invention, the horizontal direction is practical as the main shrinkage direction, and thus, an example of the film forming method in the case where the main shrinkage direction is the horizontal direction has been shown above. However, when the main shrinkage direction is the longitudinal direction, a film can be formed in accordance with the operation of the above method except that the stretching direction in the above method is changed by 90 degrees.

[0066] The heat-shrinkable polyester film thus obtained has the general characteristics of a heat-shrinkable polyester film such as heat-shrinkability and tensile strength, and also has a perforation cut property and a label wear. It is excellent in the strength of the bonded part and is suitable as a label for a bottle.

Example

[0067] Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited to these examples. First, the evaluation method of the film produced in the Example and the comparative example is demonstrated.

[0068] (1) Thermal contraction rate The film was cut into a square of lOcm X IOcm and heat-shrinked by treatment for 10 seconds in 95 ° C ± 0.5 ° C or 70 ° C ± 0.5 ° C warm water under no load. The film was immediately immersed in water at 25 ° C ± 0.5 ° C for 10 seconds, then the vertical and horizontal dimensions of the film were measured, and the thermal contraction rate was determined according to the following formula (1). The direction in which the heat shrinkage rate is large was defined as the main shrinkage direction.

Thermal shrinkage rate = ((length before shrinkage, length after shrinkage) Z length before shrinkage) X 100 (%) (1) [0069] (2) Solvent bond strength

1 from one side edge of one end slightly inside of the film, 3 Jiokisoran was applied at 2 ± 1 mm width (coating amount:. 3. 0 ± 0 3g / m 2) 0 superposed ends immediately rounded film And bonded to the tube (force speed: lOmmZ). The tube was rolled up in a flat crushed state to form a roll.

Roll-like physical force The cut-out tube-like sample was cut open so that the bonded portion was in the center, and a film-like sample was obtained. A film test piece (n = 10) having a length of 100 mm and a width of 15 mm was cut out from this film sample, and the film test piece was set to a tensile tester (made by Baldwin) with the distance between chucks set to 50 mm. Set "STM-T") so that the solvent-bonded part is positioned at the center of the chuck, and perform a tensile test at a temperature of 23 ° C and a tensile speed of 200mmZ to measure the peel strength of the bonded part. And this was the solvent adhesive strength

[0070] (3) Tear propagation strength

Based on JIS K7128-2 (1998), a film that had been shrunk 10% in advance at 85 ° C was cut into a length of 51 mm and a width of 64 mm and measured using a light load tear tester manufactured by Toyo Seiki Seisakusho. The obtained value was taken as the tear propagation resistance.

[0071] (4) Perforation cut test

Three colors were printed on the heat-shrinkable film using Toyo Ink Mfg. Co., Ltd.'s grass gold and white ink. A tube-shaped label was created by adhering both ends of the printed film with 1,3 dioxolane. The label size was 109 mm fold diameter and 90 mm label length.

The label was perforated in a direction perpendicular to the main shrinkage direction of the label. Fold in half Two lmm thick cardboards are placed under the label, and a sewing machine blade (100mm blade with 1mm pitch blades at lmm intervals) is placed on the test sealer (made by Seibu Kikai Co., Ltd.). Attach, press the sewing blade to the label with a gauge pressure of 2kg / cm ² , and put a perforation parallel to the label edge at 5mm from the edge of the folded label. The label was provided with two perforations with 1 mm long holes arranged at lmm intervals over the entire length of the label, and the interval between the two perforations was 10 mm.

Using Fuji Astec Inc's steam tunnel (model: SH-1500-L), spraying water vapor with a passage time of 2.5 seconds and a zone temperature of 80 ° C (indication) with a vapor pressure of 1 kgZcm ² (pressure gauge indication: 98 kPa). The label was heat-shrinked and attached to a 500 mL PET bottle (round shape, trunk diameter 62 mm, minimum neck diameter 25 mm). At this time, a portion (shoulder) having a diameter of about 4 Omm was set to one end of the label.

After that, fill this bottle with about 500 mL of water, refrigerate at 5 ° C for 12 hours, tear the perforation of the bottle label immediately after taking it out of the refrigerator with your fingertips, tear it cleanly in the vertical direction, and remove the label from the bottle. The number that could be removed was counted, and the percentage (%) of all 50 samples was shown.

[0072] (5) Torn when dropped

The label was attached under the condition (4), and the PET bottle refrigerated at 5 ° C for 12 hours was dust-coated from the height of lm and allowed to fall freely onto the glossy concrete surface. At this time, holding the plastic bottle sideways and letting go of the hand, the bottle dropped on its side force concrete surface. A test was performed on 10 PET bottles, and X was given if even one bonded part was removed.

[0073] (6) Breaking strength

Folded diameter 87.5mm X Label length 120mm film label is placed on a 250mL steel can (outer diameter 53mm, height 133mm) and immersed in 80 ° C hot water for 10 seconds to shrink the label into the can (5% contraction). The steel can with the label was immediately transferred to warm water of 60 ° C ± 1 ° C and immersed for 30 minutes. Also cut out the sample of the steel can label (part without back attachment) and set it to JIS K 7127 (1999) (specimen is type 2; however, distance between chucks: 20 mm, pulling speed: 200 mmZ) According to heat treatment The bow I tension test was conducted in the direction perpendicular to the maximum shrinkage direction of the film before the treatment. The size of the test piece is 100 mm in length (direction perpendicular to the maximum film shrinkage direction), 15 mm in width, and the test conditions are a distance between chucks of 20 mm, a temperature of 23 ° C, and a tensile speed of 200 mmZ. The strength at the time of breaking during the test was defined as the breaking strength.

[0074] The evaluation results of (1) to (6) are shown in Table 3.

[0075] (7) Thermal analysis of polyester component

Thermal analysis of the polyester component was performed using a DSC device (model: DSC220) manufactured by Seiko Denshi Kogyo. 10 ± lmg of each chip synthesized in the synthesis example described below is used as a sample. This sample is heated at 300 ° C for 2 minutes, immediately put in liquid nitrogen and rapidly cooled, and then the temperature is increased from 40 ° C to 300 ° C. The temperature was raised at 20 ° CZ and the heat flow rate curve (DSC curve) was measured. The intersection of tangent lines drawn before and after the endothermic start curve in the DSC curve was defined as the glass transition temperature (Tg). The temperature showing the maximum value of the endothermic peak in the DSC curve was defined as the melting temperature (Tm). The integrated value of the endothermic peak of the DSC curve was defined as the heat of fusion (Hm). The results are shown in Table 1.

[0076] (8— 1) Number of layers in the film (1)

The number of layers inside the film was determined by observation using a transmission electron microscope. First, the film was embedded in epoxy resin. As the epoxy resin used, Luabeck 812, Luabeck NMA (manufactured by Nacalai Testa Co., Ltd.) and DMP30 (TAAB Co., Ltd.) were mixed well in a ratio of 100: 89: 3, respectively. Next, after embedding the sample film in the above-described mixed resin, it was left in an oven adjusted to a temperature of 60 ° C. for 16 hours to cure the resin and obtain an embedded block.

The obtained embedding block was attached to Nissan Sangyo Ultracut N, and an ultrathin section was prepared. First, trimming was performed using a glass knife until the cross section of the part that was desired for film observation appeared on the resin surface. Next, an ultrathin section was cut out using a diamond knife (Sumitomo Electric Sumiknife S K2045). The cut sections were collected on a mesh, stained in ruthenium tetroxide vapor at room temperature for 30 minutes, and then thinly deposited with carbon.

For electron microscope observation, JEOL SiiEM—2010 was conducted under the condition of an acceleration voltage of 200 kV. It was. The obtained image was recorded on an imaging plate (FDL UR-V made by Fuji Photo Film). The signal recorded on the imaging plate is read out using digital luminography (PixsysTEM, manufactured by JEOL) and recorded as digital image information on a Windows (registered trademark) PC. We counted the number of layers identified.

(8 2) Number of layers inside the film (part 2)

The number of layers inside the film was determined by observation using a transmission electron microscope (TEM). First, the film was embedded in epoxy resin. As the epoxy resin used, Luabeck 812, Luavec NMA (manufactured by Nacalai Testa Co., Ltd.) and DMP30 (TAAB Co.) were mixed well at a ratio (mass) of 100: 89: 3, respectively. Next, after embedding the sample film in the above-described mixed resin, the sample film was allowed to stand in an oven adjusted to a temperature of 60 ° C. for 16 hours to cure the resin and obtain an embedded block.

The embedded block was cut with a glass knife until the cross section of the film portion appeared on the block surface (surface contact). The embedding block after the surface exposure was placed in a container sealed with ruthenium chloride vapor for 3 days to carry out ruthenium staining. The ruthenium chloride vapor was replaced with fresh vapor every day.

From the embedding block after staining, several ultrathin sections with a thickness of about 700A were cut out from the surface of the embedding block to about 1.5 / zm by the microtome. The ultra-thin slice with the clearest contrast was selected, and carbon deposition was performed to prepare a sample for TEM observation.

The electron microscope was observed using JEOL SiiEM-2010 under an acceleration voltage of 200 kV. The obtained image was recorded on an imaging plate (“FDL UR V” manufactured by Fuji Photo Film Co., Ltd.). The signal recorded on the imaging plate was read out using a digital luminography (“PixsysTEM” manufactured by JEOL Ltd.) and recorded as digital image information on a Windows (registered trademark) PC. The magnification was appropriately selected from the medium power of 5000-20000 times.

Image analysis software (Scion Image

Alpha 4.0.3.2; manufactured by Scion Corporation). First, a preliminary check was performed before checking the detailed number of layers. The preliminary confirmation was performed as follows.

1. The shade of the color in the film thickness direction was numerically expressed by the line profile. In particular , Read the shade of 100 pixels wide and 3000 pixels long (number of pixels can be changed arbitrarily), draw a curve with the horizontal axis as the length direction pixel and the vertical axis as the signal intensity (lightness and shade). I was jealous.

2.Because there are many peaks in the curve in the graph, for one peak, read the number of pixels at the position with the maximum value and the number of pixels at the position with the minimum value, and the difference d (peak About half of the width) was considered the thickness of the layer. About 30 peaks, d was calculated | required and average value d was computed.

av

3. If the above average value d is converted to nm unit and the converted value is more than lOOnm,

The number of layers was counted visually from the TEM image on the ging plate. In the conversion, when the TEM image is 5000 times, 1 pixel is 5 nm, and when it is 20,000 times, 1 pixel is 1.25 ηm.

4. If the converted d (nm) is less than lOOnm, use the following detailed layer number confirmation method.

To determine the number of layers.

A detailed method for confirming the number of layers was performed as follows.

1. The above TEM observation image was corrected for noise and shading of the image. First, the above images were captured using image analysis software (L Process ver. 1.96; manufactured by FUJIFILM Science Lab99) (Figure 2). With the image selector tool set to 2 ⁿ , Fourier transform (FFT) was performed over the maximum image range (2048 x 2048 pixels, but can be specified arbitrarily) (Figure 3). In Fig. 2, the center of the figure is determined, and the layer direction (stripe direction) is the X axis, and the direction perpendicular to the direction is the Y axis. In Fig. 3, the center of Fig. 2 and the center of Fig. 3 (neck pixel) are aligned so that the collection of white bright spots is along the Y axis (the power to see the horizontal and vertical lines in the figure is noise). Combined, the 5th pixel from the 5th pixel on the Y axis to the 1020th pixel is surrounded by a rectangle with a width of 200 pixels (on the X axis—from the 100th pixel to the + 100th pixel). Similarly-5th pixel power-The 1020th pixel is surrounded by a 200 pixel wide rectangle. The areas other than those enclosed are treated as noise. The above numbers of 5 to 1020 pixels and width of 200 pixels are empirically derived values to eliminate noise. Only the enclosed area was subjected to inverse Fourier transform (IFFT), and the resulting image was saved in TIFF format (16bit) (Figure 4). 2. After the inverse Fourier transform, the image analysis software (Scion

Image Alpha 4.0.3.2 (manufactured by Scion Corporation), and the threshold of the image was clarified with the Threshold function and changed to BMP format (Fig. 5). (End of correction process)

3. In this BMP format image, use the Profile Plot function and take a line profile parallel to the Y-axis (approximately 2000-2500 pixels) with a plot width of 1 pixel. Was saved in Plot Value format.

4. This Plot Value format data was read into Microsoft Excel, and the average value (Av) of all data for each pixel of the line parallel to the Y axis was obtained. Next, when the data of a certain pixel is larger than the average value (Αν), the judgment value + 1 is given to the pixel, and in other cases, the judgment value 1 is given to the pixel. When the judgment value of each pixel is plotted against the pixel (horizontal axis), the resulting graph is a horizontal straight line connecting +1 and +1 (or -1 and -1), and +1 and 1 ( Or the opposite)). The number of diagonal lines was determined as the number of layers.

Incidentally, the number of layers obtained by the above method may be less than 2 ^eta layer or 2 ^{eta + 1} layer obtained theoretically from several elements of the static mixer eta. Polyester constituting the X layer, the resin component Μ and the polyester resin component constituting the cocoon layer Although the composition is different from that of the cocoon layer, transesterification occurs at the interface between adjacent layers during the lamination process, and the X layer A polyester with the same composition may be formed near the interface of the cocoon layer. For example, if the number of layers is large and the thickness of one layer is reduced to the level of several _nanometers , the X layer and the cocoon layer are partly identified as layers of the same polyester composition, and the above dyeing method or layer When the number confirmation method is adopted, it is considered to be less than the theoretical value.

Synthesis Example 1 (Synthesis of polyester)

In an esterification reactor, 57036 parts by mass of terephthalic acid (TPA), 33244 parts by mass of ethylene glycol (EG), 15733 parts by mass of neopentyl glycol (NPG), 23.2 parts by mass of dianhymonic triacid ( Polymerization catalyst), 5.0 parts by weight of sodium acetate (alkali metal compound) and 46.1 parts by weight of trimethyl phosphate (phosphorus compound), and the pressure is adjusted to 0.25 MPa, at a temperature of 220 to 240 ° C. Perform esterification reaction by stirring for 120 minutes It was. The reaction vessel was returned to normal pressure, and 3.0 parts by mass of cobalt acetate tetrahydrate and 124.1 parts by mass of magnesium acetate tetrahydrate (alkaline earth metal compound) were added at a temperature of 240 ° C. After stirring for 10 minutes, the pressure was reduced to 0.5 hPa over 75 minutes and the temperature was raised to 280 ° C. Stirring was continued until the melt viscosity reached 4500 boise at a temperature of 280 ° C (about 70 minutes), and then discharged into water as a strand. Polyester chip A was obtained by cutting the discharged material with a strand cutter. The intrinsic viscosity of polyester chip A is 0.75 dlZg.

[0078] Synthesis Examples 2 to 4

Polyester raw material chips B to D having the chip compositions shown in Table 1 were obtained in the same manner as in Synthesis Example 1. In the table, PD is an abbreviation for 1,3 propanediol, CHDM is 1,4-cyclohexanedimethanol, BD is 1,4 butanediol, and DEG is diethylene glycol. The intrinsic viscosities of each polyester were 0.92 dlZg for chip B, 0.72 dlZg for chip C, and 1.20 dlZg for chip D.

[0079] For the intrinsic viscosity, 0.1 ml of the chip was precisely weighed and 25 ml of phenol Z tetrachloroethane was used.

After being dissolved in a mixed solvent of 3/2 (mass ratio), it was measured at 30 ± 0.1 ° C with an Ostwald viscometer. The intrinsic viscosity [r?] Is obtained by the following equation (Huggins equation).

[0080] [Equation 1]

[0081] where r ?: specific viscosity, t: solvent fall time using Ostwald viscometer, t: Ostwald sp 0

Drop time of tip solution using viscometer, C: concentration of tip solution. In the actual measurement, the intrinsic viscosity was calculated by the following approximate equation with k = 0.375 in the Huggins equation.

[0082] [Equation 2]

(η 1) +3 X Ιηη

[0083] where: is the relative viscosity.

[0084] Example 1

Each chip obtained in the above synthesis example was separately pre-dried, and as shown in Table 2, 80 kg of chip A and 20 kg of chip B were thoroughly mixed using a super mixer (manufactured by Kawada Seisakusho). It was put into the hot rod of Extruder 1 (single shaft 60φ, LZD = 25) and melted at 275 ° C ± 2 ° C. Similarly, Chip A5kg and Chip B25kg were mixed thoroughly using a super mixer, and then melted at 255 ° C ± 2 ° C with Extruder II (two-screw extruder, 22.5mmX, LZD = 25).

[0085] The resin melted in both extruders is led to a feed block of 265 ° C ± 2 ° C so that ΙΖΠ = 8Ζ2 (discharge mass ratio), and further static of 275 ° C ± 2 ° C Stacked with a mixer (Noritake Kampa-made, 12 elements, inside diameter 38.4 mm, 1 element L / D = 1.5, 1 element plate twist angle 180 degrees, twist gradient 46 degrees). It was then led to a T-die at 275 ° C ± 2 ° C and melt extruded. The extruded resin was electrostatically adhered onto a cooling roll having a surface temperature of 20 ° C ± 2 ° C to obtain an unstretched sheet. Note that the time from when the resin laminate was discharged from the outlet of the static mixer at the end of lamination to the close contact with the cooling roll was about 2 minutes. In addition, the discharge rate of Extruder I and Saddle was 40 kg per hour.

[0086] The above unstretched sheet was preheated in a tenter at 82 ° C for 24 seconds, subsequently stretched 4.8 times at 77 ° C in the lateral direction, and subsequently heat treated at 70 ° C for 24 seconds. And a heat-shrinkable polyester film having a thickness of 45 m was obtained.

Here, in Example 1, the change in the surface temperature of the film when the film was continuously produced was changed. The dynamic range was within the range of the average temperature ± 0.6 ° C in the tenter preheating step, the average temperature ± 0.5 ° C in the stretching step, and the average temperature ± 0.5 ° C in the heat treatment step.

[0087] Examples 2-3

In Example 2, chip A was changed to chip C. In Example 3, heat shrinkage was performed in the same manner as in Example 1 except that chip B was changed to chip D and the preheating temperature during transverse stretching was changed to 79 ° C. A conductive polyester film was obtained.

Comparative Example 1

Polyester chip A and polyester chip B are put into a single extruder I and melted at a ratio of A / B = 80/20 (mass ratio) (temperature 275 ° C 2 ° C) Heat shrinkage of 45 m in thickness using the same method as in Example 1 except that an unstretched sheet was obtained by using a T-die temperature of 275 ° C ± 2 ° C without using a static mixer. A conductive polyester film was obtained.

Table 1 shows the evaluation results of the films obtained in Examples 1 to 3 and Comparative Example 1. The number of layers in each example was determined by employing the detailed layer number confirmation method described in (8-2) above.

[0088] [Table 1]

[0089] [Table 2]

[0090] [Table 3]

Heat shrinkage rate (%) Perforation cutting property Solvent adhesion strength after drop treatment Tear propagation strength Number of layers Horizontal perforation 卜 La perforation break strength (layer) Breaking from defective rate after shrinkage

Example ○

Comparative example Industrial applicability

[0091] The heat-shrinkable polyester film of the present invention is suitable for a label for a bottle.

[0092] 1 Extruder E

2 Extruder F

3 Feed, block

4 Static mixer

5 T die

6 Cooling roll

Claims

The scope of the claims

[1] A heat-shrinkable polyester film having a structure in which an X layer containing a polyester component M and a Y layer containing a polyester component N are alternately laminated,

Apply 1,3-dioxolan slightly inside from the edge of one side of the film, roll the film and overlap the edges to form a tubular film label,

Cover the 500 ml PET bottle with the film label, heat it at 80 ° C for 2.5 seconds, and put it on for 10 seconds. A heat-shrinkable polyester film characterized in that the film label is not damaged due to peeling between the Y layer and the Y layer.

[2] includes a polyester component M force polyester A70~99 wt% and polyethylene ester Bl~30 mass ^_0/0 contained in X layer, the polyester component N force polyesters contained in the Y layer B 70 to 99% by weight and polyester Al The heat-shrinkable polyester film according to claim 1, comprising -30 mass%.

[3] The heat-shrinkable polyester film according to claim 1 or 2, wherein the X layer and the Y layer have a structure in which 500 layers or more are alternately laminated.

[4] Thermal shrinkage in the main shrinkage direction after immersion for 10 seconds in warm water at 95 ° C ± 0.5 ° C is 50% or more, solvent adhesion strength is 2.0NZl5mm or more, and tear propagation strength is 2. Heat-shrinkable polyester film with a thickness of ~ 100 μm that is below ON and has a breaking strength of 20 MPa or more after being immersed in warm water at 60 ° C ± 1 ° C for 30 minutes.

[5] Polyester A70~99 wt% and polyester Bl~30 wt% polyester Le component M containing, and polyester B70~99 mass ^_0/0 and polyester Al~30 mass ^_0/0 respectively separate the polyester component N including Injected into extruders E and F and melted, molten polyester components M and N were charged into a laminating apparatus to obtain a laminate of polyester components X and Y,

In order that the time it takes for the laminate to be discharged from the laminating apparatus and the force to adhere to the cooling roll is 45 seconds to 10 minutes, the laminating apparatus force is also led to the slit die and extruded to the cooling film roll to form the unstretched sheet. Get A method for producing a heat-shrinkable polyester film, wherein the unstretched sheet is stretched at least uniaxially.

A bottle label using the heat-shrinkable polyester film according to claim 1.