WO2018221360A1

WO2018221360A1 - Liquid crystal display device and method for manufacturing liquid crystal display device

Info

Publication number: WO2018221360A1
Application number: PCT/JP2018/019915
Authority: WO
Inventors: 真伸水▲崎▼; 康司郎谷池
Original assignee: シャープ株式会社
Priority date: 2017-05-31
Filing date: 2018-05-24
Publication date: 2018-12-06

Abstract

The present invention provides a liquid crystal display device whereby ghosting caused by application of AC voltage can be suppressed, and a method for manufacturing a liquid crystal display device whereby such a liquid crystal display device can be manufactured. The present invention is a liquid crystal display device provided with a liquid crystal layer containing a liquid crystal material having positive dielectric anisotropy, a seal material disposed so as to surround the liquid crystal layer in plan view, a pair of substrates sandwiching the liquid crystal layer, and an optical alignment film provided to a surface of at least one of the pair of substrates, the optical alignment film containing a polyamic acid and/or a polyimide and causing a liquid crystal compound in the liquid crystal material to align in the horizontal direction with respect to the substrate surface, at least one of the pair of substrates including a pixel electrode and a shared electrode, the pixel electrode and/or the shared electrode including a linear part, and the inclination angle of the linear part with respect to the initial alignment direction of the liquid crystal compound being 7° or greater in plan view.

Description

Liquid crystal display device and method of manufacturing liquid crystal display device

The present invention relates to a liquid crystal display device and a method for manufacturing the liquid crystal display device. More specifically, the present invention relates to a liquid crystal display device having a photo-alignment film and a manufacturing method thereof.

A liquid crystal display device is a display device that uses a liquid crystal composition for display. A typical display method is to irradiate light from a backlight onto a liquid crystal panel in which the liquid crystal composition is sealed between a pair of substrates. The amount of light transmitted through the liquid crystal panel is controlled by applying a voltage to the liquid crystal composition to change the orientation of the liquid crystal material. Such a liquid crystal display device has features such as thinness, light weight, and low power consumption, and thus is used in electronic devices such as smartphones, tablet PCs, and car navigation systems.

In addition, as a display method of a liquid crystal display device, a horizontal electric field type horizontal control in which the orientation of a liquid crystal material is controlled mainly in a plane parallel to the substrate surface for the purpose of easily obtaining a wide viewing angle characteristic. The orientation mode is attracting attention. Examples of the horizontal electric field type horizontal alignment mode include an in-plane switching (IPS: In-Plane Switching) mode and a fringe electric field switching (FFS: Fringe Field Switching) mode.

In a liquid crystal display device, the alignment of a liquid crystal material in a state where no voltage is applied is generally controlled by an alignment film that has been subjected to an alignment treatment (see, for example, Patent Document 1). The alignment film is formed, for example, by applying an alignment film material such as polyamic acid on a substrate and then baking it. As another method for controlling the alignment of the liquid crystal material, a polymer-supported alignment technique (Polymer) that polymerizes a polymerizable monomer added in the liquid crystal layer to form a polymer layer for controlling the alignment of the liquid crystal material on the surface of the alignment film. Sustained Alignment) has also been studied (see, for example, Non-Patent Document 1).

JP 2009-173792 A

However, in a horizontal electric field type horizontal alignment mode such as FFS mode, an alignment film formed from an alignment film material (hereinafter also referred to as a horizontal light alignment film material) that exhibits a horizontal alignment control ability when irradiated with polarized light. When a positive liquid crystal material is used (hereinafter also referred to as a horizontal light alignment film), image sticking may occur due to application of an AC (alternating current) voltage to a liquid crystal panel (liquid crystal layer, each pixel). The cause is considered as follows. FIG. 7 is an enlarged schematic plan view of a liquid crystal display device according to a reference example, showing a liquid crystal compound and a linear portion of a pixel electrode and / or a common electrode. FIG. b) shows when the AC voltage is applied, and (c) shows after the AC voltage is applied. In the horizontal electric field type horizontal alignment mode using the positive type liquid crystal material, from the viewpoint of improving the transmittance and the viewing angle, as shown in FIG. 7A, the pixel electrode with respect to the initial alignment direction 31a of the liquid crystal compound 31 and It is necessary to make the inclination angle (Inclination Angle; IA) α of the linear portion 27 of the common electrode as small as possible. Therefore, the inclination angle α is normally set to less than 7 °. However, when a high AC voltage is applied to the liquid crystal panel using the horizontal light alignment film, as shown in FIG. 7B, the liquid crystal compound 31 rotates greatly from the initial alignment azimuth 31a when the tilt angle α is small. However, since the anchoring strength (especially the azimuth anchoring strength) of the horizontal photo-alignment film is relatively weak (low orientation regulation force), as shown in FIG. However, it is presumed that the liquid crystal compound 31 does not return to the initial orientation azimuth 31a, and as a result, burn-in occurs.

In particular, in-vehicle applications in which a high AC voltage (for example, about 6 V) is applied to a liquid crystal panel in order to reduce the dielectric anisotropy (Δε) of a positive liquid crystal material (for example, less than 3.5) and improve the transmittance accordingly In the liquid crystal display device, image sticking derived from the AC voltage is significant. The reason why the dielectric anisotropy of the positive liquid crystal material is reduced is to increase the response characteristic of the liquid crystal panel.

Also, when an alignment film material having an azobenzene group (isomerization type) in the polymer main chain, which is a kind of horizontal light alignment film material, is used, the image sticking from the AC voltage becomes remarkable. This is presumably because the azimuth anchoring strength is particularly low in an alignment film formed from an alignment film material having an azobenzene group in the polymer main chain (hereinafter also referred to as an azobenzene group-containing photo-alignment film material). The factors are (1) the weight-average molecular weight of the azobenzene group-containing photoalignment film material is relatively small (for example, 20,000 or less), and (2) some azobenzene groups by irradiation with polarized ultraviolet rays are expressed by the following reaction formula: As shown, because of photocleavage, the weight average molecular weight of the polymer is further reduced.

With respect to the above (1), the azobenzene group-containing photo-alignment film material is designed to improve the molecular mobility by reducing the weight average molecular weight to some extent in order to align the polymer in one direction by irradiation with polarized ultraviolet rays. Regarding (2) above, the azobenzene group is susceptible to cleavage reaction in addition to isomerization by (polarized) ultraviolet irradiation. In addition, when polyamic acid and / or polyimide is used as the polymer and the one having a bent molecular structure is used as tetracarboxylic dianhydride, the absorption efficiency of polarized ultraviolet light is improved, so the number of cleavage of the azobenzene group is further increased. Become.

In addition, other factors that lower the azimuth anchoring strength in the horizontal photo-alignment film include (3) (meth) acrylic resin, which is a constituent compound (unreacted component) of the sealing material for the dropping injection method, at the seal peripheral portion. The monomer ((meth) acrylic monomer) and the polymerization initiator are eluted from the seal into the liquid crystal layer, and the eluted unreacted components are adsorbed on the surface of the horizontal photo-alignment film. Regarding (3) above, since the (meth) acrylic monomer and the polymerization initiator (especially radical polymerization initiator, especially photoradical polymerization initiator) in the seal are of low polarity, as described above, for high speed response. If the dielectric anisotropy of the liquid crystal material is decreased (for example, less than 3.5), the polarity of the liquid crystal material also decreases, and the unreacted components are more easily eluted in the liquid crystal layer.

The present invention has been made in view of the above situation, and provides a liquid crystal display device capable of suppressing burn-in caused by application of an AC voltage and a method of manufacturing a liquid crystal display device capable of manufacturing such a liquid crystal display device. It is intended to do.

One embodiment of the present invention includes a liquid crystal layer containing a liquid crystal material having a positive dielectric anisotropy, a sealant disposed so as to surround the liquid crystal layer in a plan view, and a pair of sandwiching the liquid crystal layer A substrate and a photo-alignment film provided on at least one surface of the pair of substrates, wherein the photo-alignment film contains at least one of polyamic acid and polyimide, and contains the liquid crystal compound in the liquid crystal material. One of the pair of substrates includes a pixel electrode and a common electrode, and at least one of the pixel electrode and the common electrode includes a linear portion, The liquid crystal display device may have an inclination angle of the linear portion with respect to the initial alignment direction of the liquid crystal compound of 7 ° or more in plan view.

Another embodiment of the present invention is a preparatory step of preparing a pair of substrates, and an orientation containing at least one polymer of polyamic acid and polyimide and at least one monomer on at least one surface of the pair of substrates. A film forming step of forming a photo-alignment film by applying an agent; and an irradiation step of irradiating the photo-alignment film with polarized ultraviolet rays to align the at least one polymer and align and polymerize the at least one monomer. The at least one monomer may be a method for producing a liquid crystal display device that exhibits orientation by causing at least one of an isomerization reaction and a dimerization reaction by irradiation with polarized ultraviolet rays.

Patent Document 1 discloses a polyamic acid-based alignment film material having an azobenzene group in the main chain. However, in the above-mentioned Patent Document 1, it is not considered that the inclination angle of the linear portion of the pixel electrode and / or the common electrode with respect to the initial alignment direction of the liquid crystal compound is 7 ° or more. There is no disclosure at all of forming an optical alignment film by applying an alignment agent containing at least one polymer and at least one monomer.

According to the liquid crystal display device and the manufacturing method of the liquid crystal display device of the present invention, it is possible to suppress image sticking caused by application of an AC voltage.

1 is a schematic cross-sectional view of a liquid crystal display device according to Embodiment 1. FIG. 1 is a schematic plan view of a liquid crystal display device according to Embodiment 1. FIG. FIG. 2 is an enlarged schematic plan view of the liquid crystal display device according to Embodiment 1, showing a liquid crystal compound and a linear portion of a pixel electrode and / or a common electrode. FIG. 5 is an enlarged schematic plan view of a liquid crystal display device according to a modification of Embodiment 1, showing a liquid crystal compound and a linear portion of a pixel electrode and / or a common electrode. FIG. 3 is a schematic diagram illustrating states of a polyimide polymer having an azobenzene group and a polymer of an alignment monomer in a photo-alignment film of the liquid crystal display device according to Embodiment 1. It is the schematic diagram explaining the state of the molecule | numerator in the photo-alignment film | membrane of the liquid crystal display device which concerns on Embodiment 1, (a) shows the polyimide-type polymer and orientation monomer which have an azobenzene group before polarized ultraviolet irradiation, (b ) Shows a polyimide polymer having an azobenzene group after irradiation with polarized ultraviolet rays and a polymer of an orientation monomer. It is an expansion plane schematic diagram of the liquid crystal display device concerning a reference example, and shows a liquid crystal compound and the linear part of a pixel electrode and / or a common electrode, (a) is before an AC voltage application, (b) is When the AC voltage is applied, (c) shows after the AC voltage is applied.

Hereinafter, embodiments of the present invention will be described. The present invention is not limited to the contents described in the following embodiments, and appropriate design changes can be made within a range that satisfies the configuration of the present invention.

In the present specification, the “photoreactive monomer” means a monomer containing a photofunctional group.

In the present specification, the “photofunctional group” means a functional group capable of causing a photoreaction.

In this specification, “observation surface side” means a side closer to the screen (display surface) of the liquid crystal display device, and “back side” means the screen (display surface) of the liquid crystal display device. Means the farther side.

In the present specification, the “initial alignment direction of the liquid crystal compound” means the alignment direction of the liquid crystal compound in a state in which no voltage is applied between the pixel electrode and the common electrode. Further, the “alignment orientation of the liquid crystal compound” means the direction of the long axis (liquid crystal director) of the liquid crystal compound.

<Embodiment 1>
<Liquid crystal display device>
FIG. 1 is a schematic cross-sectional view of the liquid crystal display device according to the first embodiment. FIG. 2 is a schematic plan view of the liquid crystal display device according to the first embodiment. FIG. 3 is an enlarged schematic plan view of the liquid crystal display device according to Embodiment 1, and shows a liquid crystal compound and a linear portion of a pixel electrode and / or a common electrode. As shown in FIGS. 1 and 2, the liquid crystal display device 100 of the present embodiment is an FFS mode that is a kind of horizontal electric field type horizontal alignment mode, and contains a liquid crystal material having positive dielectric anisotropy. The liquid crystal layer 30, the sealing material 40 disposed so as to surround the liquid crystal layer 30 in plan view, the pair of

substrates

10 and 20 that are bonded to each other by the sealing material 40 and sandwich the liquid crystal layer 30, and the

substrates

10 and 20 And a photo-alignment film 50 provided on the surface of the liquid crystal layer 30 side. The liquid crystal display device 100 further includes a backlight 70 behind one of the pair of

substrates

10 and 20.

As shown in FIG. 1, one of the

substrates

10 and 20 is arranged between the planar electrode 22, the slit electrode 24 provided with at least one slit 24 s, and the planar electrode 22 and the slit electrode 24. A structure (FFS electrode structure) including the insulating film (interlayer insulating film) 23 is provided, and an oblique electric field (fringe electric field) including a lateral electric field component is formed in the liquid crystal layer 30. Usually, from the liquid crystal layer 30 side, the slit electrode 24 (upper layer electrode), the insulating film 23, and the planar electrode 22 (lower layer electrode) are arranged in this order. As the slit electrode 24, for example, a linear opening surrounded by an electrode around the entire circumference as the slit 24s, or a linear electrode provided with a plurality of comb teeth and disposed between the comb teeth. A comb-shaped slit that forms the slit 24s can be used.

In the FFS mode, one of the slit electrode 24 and the planar electrode 22 functions as the pixel electrode 25 provided corresponding to each pixel, and the other functions as the common electrode 26. In addition, one of the slit electrode 24, that is, the pixel electrode 25 and the common electrode 26 includes a plurality of linear portions 27 parallel to each other. The linear portion 27 and the slit 24 s of the slit electrode 24 include the liquid crystal compound 31. They are alternately arranged in the direction orthogonal to the initial orientation direction 31a. Each linear portion 27 is usually composed of one or more straight portions, and when composed of two straight portions, it is composed of three or more straight portions in a V shape as shown in FIG. If it is, it is formed in a zigzag shape.

FIG. 4 is an enlarged schematic plan view of a liquid crystal display device according to a modification of the first embodiment, and shows a liquid crystal compound and a linear portion of a pixel electrode and / or a common electrode. As shown in FIG. 4, each linear portion 27 may be composed of a plurality of linear portions having different inclination angles α with respect to the initial alignment azimuth 31 a of the liquid crystal compound 31. It is preferable that the smallest of these satisfy the numerical range described later.

The photo-alignment film 50 includes at least one polymer of polyamic acid and polyimide (hereinafter also referred to as polyimide polymer), and the liquid crystal compound 31 in the liquid crystal material is oriented in a horizontal direction with respect to the

substrates

10 and 20. To be oriented. Such a photo-alignment film usually has a lower anchoring strength (particularly azimuth angle anchoring strength) than a horizontal alignment film for rubbing treatment. Therefore, as described above, even in the liquid crystal display device 100, the liquid crystal panel (liquid crystal There is concern over the occurrence of burn-in due to the application of an AC voltage to the layer 30 and each pixel).

However, in this embodiment, as shown in FIG. 3, the inclination angle α of the linear portion 27 with respect to the initial alignment direction 31a of the liquid crystal compound 31 is large, specifically, set to 7 ° or more in plan view. . When the inclination angle α is increased, the amount of change Δd in the azimuth direction of the liquid crystal compound 31 due to the application of the AC voltage is reduced, so that burn-in due to the application of the AC voltage can be reduced. In addition, since the return of the liquid crystal compound 31 (liquid crystal director) to the initial alignment azimuth 31a at the time of removing the AC voltage becomes faster, a high-speed response is possible.

On the other hand, the upper limit of the tilt angle α is not particularly limited and can be set as appropriate from the viewpoint of reducing the burn-in resulting from the AC voltage application and increasing the response speed. However, if the tilt angle α is too large, the liquid crystal compound 31 A decrease in transmittance and contrast due to a small change Δd in the azimuth direction may occur (although there are effects of low image sticking and high-speed response). Therefore, from the viewpoint of transmittance and contrast, the inclination angle α is preferably not too large, and specifically, it is preferably 13 ° or less in plan view.

<Board>
Examples of the pair of

substrates

10 and 20 include a combination of an active matrix substrate (TFT substrate) and a color filter (CF) substrate.

As the active matrix substrate, those normally used in the field of liquid crystal display devices can be used. When the active matrix substrate is viewed in plan, the transparent matrix 21 has a plurality of parallel gate signal lines; a plurality of parallel gate signal lines extending in a direction perpendicular to the gate signal lines and parallel to each other. Source signal lines; active elements such as thin film transistors (TFTs) arranged corresponding to the intersections of the gate signal lines and the source signal lines; arranged in a matrix in a region partitioned by the gate signal lines and the source signal lines A configuration in which the pixel electrode 25 and the like are provided can be given. In the case of the horizontal electric field type horizontal alignment mode, a common electrode; a common electrode 26 that is connected to the common wire and applies a common voltage to a plurality of pixels (or all pixels) is provided. The pixel electrode 25 and the common electrode 26 may be stacked via the insulating film 23. As the TFT, an amorphous silicon, polysilicon, or an oxide semiconductor IGZO (indium-gallium-zinc-oxygen) is preferably used.

In the active matrix display method, normally, when the TFT provided in each pixel is turned on, a signal voltage is applied to the pixel electrode 25 through the TFT, and the charge charged in the pixel at this time is turned off. Hold during the period. A voltage holding ratio (VHR) indicates a ratio of holding the charged charge during one frame period (for example, 16.7 ms). That is, a low VHR means that the voltage applied to the liquid crystal layer tends to decay with time. In the active matrix display method, it is required to increase the VHR.

As the color filter substrate, those usually used in the field of liquid crystal display devices can be used. Examples of the configuration of the color filter substrate include a configuration in which a black matrix formed in a lattice shape, a color filter formed inside a lattice, that is, a pixel, and the like are provided on a transparent substrate. The color filter may include a red color filter, a green color filter, and a blue color filter. The thickness of the blue color filter may be greater than the thickness of the red color filter or the green color filter. By increasing the blue color filter, the liquid crystal layer thickness can be reduced and the cell thickness can be optimized. An overcoat layer (dielectric constant ε = 3 to 4) for flattening the uneven surface may be disposed on the surface of the color filter.

The pair of

substrates

10 and 20 may be one in which both the color filter and the active matrix are formed on one substrate.

<Seal material>
As shown in FIG. 2, the sealing material 40 is disposed so as to surround the liquid crystal layer 30 in a plan view. The sealing material 40 may be cured by light such as ultraviolet rays, may be cured by heat, or may be cured by both light and heat. Those that cure by both heat and heat are preferred. Examples of the sealing material 40 include those containing an epoxy resin, a (meth) acrylic resin, and the like. The sealing material 40 may contain a curing agent such as a silane coupling agent, an inorganic filler, an organic filler, and an epoxy curing material. As the sealing material 40, for example, Sekisui Chemical Co., Ltd., Photorec, etc. can be used. In addition, the width | variety of the sealing material 40 in planar view is not specifically limited, According to the adhesive strength requested | required, it can set suitably.

The sealing material 40 before and after curing may contain a (meth) acrylic monomer, a radical polymerization initiator, an epoxy monomer, and an epoxy curing material. These components are contained in the sealing material 40 before curing, and are unreacted components remaining in the sealing material 40 after curing. As described above, the liquid crystal layer is formed from the cured sealing material 40. 30 and is adsorbed on the surface of the photo-alignment film 50 to cause a decrease in the azimuth anchoring strength of the photo-alignment film 50. However, in this embodiment, since the inclination angle α is set to 7 ° or more in plan view, even when such an unreacted component remains in the sealing material 40, it is attributed to the unreacted component. Thus, it is possible to effectively suppress the occurrence of image sticking due to application of an AC voltage. Among the above components, the (meth) acrylic monomer and the radical polymerization initiator have higher solubility in the liquid crystal material than the epoxy monomer and the epoxy cured material, and therefore the orientation of the photo-alignment film 50 compared to the epoxy monomer and the epoxy cured material. The possibility of reducing the angle anchoring strength is considered very high.

As the radical polymerization initiator, a polymerization initiator that generates radicals upon irradiation with light (preferably ultraviolet rays), that is, a photo radical polymerization initiator is preferable, and a (meth) acrylic monomer contained in the sealant 40 before curing. In many cases, radical polymerization is performed by radicals generated from a radical polymerization initiator by light irradiation to form a (meth) acrylic resin. The (meth) acrylic monomer may be of low polarity.

The (meth) acrylic monomer is not particularly limited, and examples thereof include urethane (meth) acrylate having a urethane bond, and epoxy (meth) acrylate derived from a compound having a glycidyl group and (meth) acrylic acid. . Any of these may be used alone or in combination of two or more. In addition, in this specification, (meth) acryl means acryl or methacryl.

The urethane (meth) acrylate is not particularly limited, and examples thereof include derivatives of diisocyanates such as isophorone diisocyanate and reactive compounds that undergo addition reaction with isocyanates such as acrylic acid and hydroxyethyl acrylate. These derivatives may be chain-extended with caprolactone or polyol. Examples of commercially available products include U-122P, U-340P, U-4HA, U-1084A (manufactured by Shin-Nakamura Chemical Co., Ltd.); KRM7595, KRM7610, KRM7619 (manufactured by Daicel UCB) and the like. .

The epoxy (meth) acrylate is not particularly limited, and examples thereof include an epoxy (meth) acrylate derived from an epoxy resin such as bisphenol A type epoxy resin or propylene glycol diglycidyl ether, and (meth) acrylic acid. It is done. Examples of commercially available products include EA-1020, EA-6320, EA-5520 (above, Shin-Nakamura Chemical Co., Ltd.); Epoxy ester 70PA, Epoxy ester 3002A (above, Kyoeisha Chemical Co., Ltd.) and the like. .

Other (meth) acrylic monomers include, for example, methyl methacrylate, tetrahydrofurfuryl methacrylate, benzyl methacrylate, isobornyl methacrylate, 2-hydroxyethyl methacrylate, glycidyl methacrylate, (poly) ethylene glycol dimethacrylate, 1,4-butane Examples thereof include diol dimethacrylate, 1,6-hexanediol dimethacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, and glycerin dimethacrylate.

The radical polymerization initiator is not particularly limited, and examples thereof include compounds represented by the following chemical formula (R-1) or (R-2). Moreover, as a commercial item, IRGACURE 651, IRGACURE189, IRGACURE-OXE01 (above, BASF Japan make) etc. are mentioned, for example. Any of these may be used alone or in combination of two or more.

(In the formula (R-2), R represents hydrogen or an aliphatic hydrocarbon residue having 4 or less carbon atoms, X represents a residue of a bifunctional isocyanate derivative having 13 or less carbon atoms, and Y represents carbon. This represents an aliphatic hydrocarbon residue having a number of 4 or less or a residue having an atomic ratio of carbon to oxygen constituting the residue of 3 or less.)

The epoxy monomer means a compound having a reactive epoxy group at both ends, and includes a prepolymer. A prepolymer is a compound (intermediate product) having a repeating structure between two epoxy groups (may be glycidyl groups) at both ends. Many of the epoxy monomers contained in the sealing material 40 before curing are cross-linked by an addition reaction of the epoxy curing material to form an epoxy resin when heated.

Examples of the epoxy resin include a phenol novolac epoxy resin, a cresol novolac epoxy resin, a biphenyl novolac epoxy resin, a trisphenol novolac epoxy resin, a dicyclopentadiene novolac epoxy resin, a bisphenol A epoxy resin, and a bisphenol F type. Epoxy resin, 2,2'-diallylbisphenol A type epoxy resin, bisphenol S type epoxy resin, hydrogenated bisphenol A type epoxy resin, propylene oxide added bisphenol A type epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin, resorcinol type Examples include epoxy resins and glycidylamines. Any of these may be used alone or in combination of two or more.

Among the above epoxy resins, those commercially available include, for example, NC-3000S (manufactured by Nippon Kayaku Co., Ltd.) as a phenyl novolac type epoxy resin, and EPPN-501H and EPPN-501H as trisphenol novolak type epoxy resins. (Nippon Kayaku Co., Ltd.), NC-7000L (Nippon Kayaku Co., Ltd.) as the dicyclopentadiene novolak type epoxy resin, and Epicron 840S and Epicron 850CRP (above, DIC Corporation) as the bisphenol A type epoxy resin ), Bisphenol F type epoxy resin, Epicoat 807 (manufactured by Japan Epoxy Resin Co., Ltd.), Epicron 830 (manufactured by DIC), and 2,2′-diallyl bisphenol A type epoxy resin, RE310NM (manufactured by Nippon Kayaku Co., Ltd.) , Hydrogenated bisphenol As an epoxy resin, Epicron 7015 (manufactured by DIC), as a propylene oxide-added bisphenol A type epoxy resin, as an epoxy ester 3002A (manufactured by Kyoeisha Chemical Co., Ltd.), as a biphenyl type epoxy resin, as Epicoat YX-4000H, YL-6121H ( As described above, manufactured by Japan Epoxy Resin Co., Ltd., as naphthalene type epoxy resin, Epicron HP-4032 (manufactured by DIC), as resorcinol type epoxy resin, Denacol EX-201 (manufactured by Nagase ChemteX Corporation), as glycidylamines , Epicron 430 (manufactured by DIC), Epicoat 630 (manufactured by Japan Epoxy Resin), and the like. Any of these may be used alone or in combination of two or more.

The epoxy curing material is not particularly limited, but preferably contains an amine and / or thiol group having excellent low-temperature reactivity in order to cure the sealing material 40 before curing at a curing temperature of 100 to 120 ° C. Such an epoxy curing material is not particularly limited, but for example, hydrazide compounds such as 1,3-bis [hydrazinocarbonoethyl-5-isopropylhydantoin], adipic acid dihydrazide; dicyandiamide, guanidine derivatives, 1-cyanoethyl-2 -Phenylimidazole, N- [2- (2-methyl-1-imidazolyl) ethyl] urea, 2,4-diamino-6- [2'-methylimidazolyl- (1 ')]-ethyl-s-triazine, N , N′-bis (2-methyl-1-imidazolylethyl) urea, N, N ′-(2-methyl-1-imidazolylethyl) -adipamide, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2- Imidazoline-2-thiol, 2-2'-thiodiethanethiol, various amines and epoxy resin Include addition products, etc. are. Any of these may be used alone or in combination of two or more.

<Liquid crystal layer>
The liquid crystal layer 30 contains a liquid crystal material including at least one liquid crystal compound (liquid crystal molecule) 31. The liquid crystal material is a thermotropic liquid crystal, and preferably a liquid crystal material exhibiting a nematic phase (nematic liquid crystal). The liquid crystal material preferably has a phase transition to an isotropic phase when the temperature rises from a nematic phase and reaches a certain critical temperature (nematic phase-isotropic phase transition point (T _NI )) or higher. The liquid crystal layer 30 preferably exhibits a nematic phase under the usage environment of the liquid crystal display device (for example, −40 ° C. to 90 ° C.). The temperature of the nematic phase-isotropic phase transition point of the liquid crystal material is not particularly limited, but is, for example, 70 to 110 ° C., and preferably 95 ° C. or higher. By setting the temperature to 95 ° C. or higher, the liquid crystal display device 100 can be made suitable for in-vehicle use, marine use, aviation use, and the like. The method for measuring the nematic phase-isotropic phase transition point of the liquid crystal material is, for example, by differential scanning calorimetry (DSC) or by directly observing the temperature dependence by enclosing the liquid crystal material in a capillary. can do.

The liquid crystal material and the liquid crystal compound 31 have a positive dielectric anisotropy (Δε) defined by the following formula. That is, the liquid crystal material and the liquid crystal compound 31 have positive dielectric anisotropy. The liquid crystal material having positive dielectric anisotropy and the liquid crystal compound 31 have characteristics such as high T _NI and high-speed response (low rotational viscosity). As the liquid crystal material having positive dielectric anisotropy, for example, a material having Δε of 1 to 20 can be used. Furthermore, the liquid crystal layer 30 and the liquid crystal material may contain a liquid crystal compound (neutral liquid crystal compound) having no polarity, that is, Δε is substantially zero. Examples of the neutral liquid crystal compound include a liquid crystal compound having an alkene structure. Hereinafter, a liquid crystal material and a liquid crystal compound having positive dielectric anisotropy are also referred to as a positive liquid crystal material and a positive liquid crystal compound, respectively.
Δε = (dielectric constant in the major axis direction)-(dielectric constant in the minor axis direction)

The liquid crystal material may have a dielectric anisotropy of 1 or more and less than 3.5 (preferably 1.5 or more and 3 or less, more preferably 1.8 or more and 2.7 or less). . As a result, the liquid crystal display device 100 can achieve high-speed response and is suitable for in-vehicle use. On the other hand, in this case, in order to improve the transmittance of white display, it is necessary to apply a high AC voltage (for example, about 6 V) to the liquid crystal panel, and as described above, the burn-in derived from the AC voltage becomes remarkable. There is concern. However, in the present embodiment, since the inclination angle α is set to 7 ° or more in plan view, image sticking due to application of a high AC voltage occurs even when the dielectric anisotropy of the liquid crystal material is small. This can be effectively suppressed.

The liquid crystal material may contain a liquid crystal compound having an alkenyl group. The liquid crystal compound having an alkenyl group is preferably a neutral liquid crystal compound. By including the liquid crystal compound having an alkenyl group, the rotational viscosity of the liquid crystal material is improved, so that the response performance of the liquid crystal material can be improved and the speed can be increased. Accordingly, it is possible to introduce a liquid crystal compound having a liquid crystal phase at a high temperature and having a high viscosity at a low temperature into the liquid crystal material. As a result, the liquid crystal material has a fast response and exhibits a liquid crystal phase in a wide temperature range. (Preferably, a liquid crystal material having a nematic phase-isotropic phase transition point of 95 ° C. or higher) can be used.

The liquid crystal compound having an alkenyl group may be a compound represented by any of the following chemical formulas (L-1) to (L-4). Any of these may be used alone or in combination of two or more.

(Wherein, m and n are the same or different and are integers of 1 to 6)

Specific examples of the liquid crystal compound having an alkenyl group include a compound represented by the following chemical formula (L-1-1).

<Photo-alignment film>
The photo-alignment film 50 is disposed in contact with the liquid crystal layer 30 and aligns the liquid crystal compound 31 in the liquid crystal material included in the liquid crystal layer 30 in the horizontal direction with respect to the surfaces of the

substrates

10 and 20. The alignment of the liquid crystal material in a state where a voltage equal to or higher than the threshold value of the liquid crystal material is not applied to the liquid crystal layer 30 (for example, a voltage non-applied state) is controlled by the photo-alignment film 50. In addition, aligning the liquid crystal compound 31 in the liquid crystal material in the horizontal direction with respect to the

substrates

10 and 20 means that the pretilt angle of the liquid crystal material with respect to the

substrates

10 and 20 is 10 ° or less. The pretilt angle is more preferably 3 ° or less. The pretilt angle refers to an angle formed by the major axis of the liquid crystal material (liquid crystal compound 31) with respect to the surface of the substrate when the applied voltage to the liquid crystal layer 30 is less than the threshold voltage (including no voltage applied). The surface is 0 ° and the substrate normal is 90 °.

The photo-alignment film 50 includes at least one polymer (polyimide polymer) of polyimide and polyamic acid. The polyimide that can be included in the photo-alignment film 50 may be a partially imidized polyamic acid, that is, a partially included polyamic acid structure, or a completely imidized polyamic acid. That is, it may not contain any polyamic acid structure. Moreover, the photo-alignment film 50 may contain only one type of polyimide polymer, or may contain two or more types of polyimide polymers.

The photo-alignment film 50 is subjected to photo-alignment treatment, and the polyimide polymer has a photofunctional group in the main chain. The photofunctional group is irradiated with light (electromagnetic wave, preferably deflected light, more preferably deflected ultraviolet light, particularly preferably linearly polarized ultraviolet light) such as ultraviolet light and visible light, for example, dimerization (dimer formation). It is preferably a functional group capable of causing structural changes such as isomerization, light fleece transition, and decomposition (cleavage) and exhibiting orientation regulating power. Specific examples of the photofunctional group include azobenzene group, chalcone group, cinnamate group, coumarin group, tolan group, stilbene group, and cyclobutane ring. By using the photo-alignment film 50, the liquid crystal display device 100 can have high contrast.

The polyimide-based polymer is a polymer having a structure derived from a diamine and a structure derived from a tetracarboxylic dianhydride as a repeating structure, and includes at least one diamine and at least one tetracarboxylic dianhydride. Polymerized. The polyimide polymer includes a polyamic acid structure represented by the following chemical formula (P-1) and / or a polyimide structure represented by the following chemical formula (P-2).

(In the formula, X represents a tetravalent organic group, and Y represents a trivalent organic group.)

In one molecule of the polyimide polymer, X and Y may be one type or two or more types, respectively.

As the polyimide polymer (the polyamic acid and the polyimide), those having a structure derived from a diamine having an azobenzene group and a structure derived from a tetracarboxylic dianhydride having a bent molecular structure are suitable. The azobenzene group undergoes an isomerization reaction and a decomposition (cleavage) reaction upon irradiation with polarized ultraviolet rays (preferably linearly polarized ultraviolet rays). When the polyimide polymer is formed by polymerizing a diamine having an azobenzene group and a tetracarboxylic dianhydride having a bent molecular structure, an azobenzene group is present in the main chain of the polyimide polymer, Since the absorption efficiency of polarized ultraviolet rays of the polyimide-based polymer is improved, there is a concern that the burn-in derived from the AC voltage becomes significant as described above. However, in this embodiment, since the inclination angle α is set to 7 ° or more in plan view, even in such a case, the occurrence of image sticking due to the application of a high AC voltage is effectively suppressed. be able to. In the present specification, a tetracarboxylic dianhydride having a bent molecular structure means that a plurality of conformations can be obtained and the molecular structure in at least the most energetically stable conformation is bent. The molecular structure in a conformation other than the most energetically stable conformation may be bent or unbent. In order to determine which of the multiple conformations is the most energetically stable, the molecular structure is confirmed by mass spectrometry (ToF-SIMS, LC-MS, etc.), and the energy calculation by simulation is performed for the molecular structure. It can be determined by the method to be performed.

When the tetracarboxylic dianhydride has a flexible (bent) molecular structure, the steric hindrance between the polyimide polymer molecules is suppressed, so that the isomerization reaction of the azobenzene group by light irradiation occurs efficiently. Become. Since the isomerization reaction of the azobenzene group occurs efficiently, the contrast of the liquid crystal display device 100 is improved, and at the same time, a low molecular additive for improving the reaction efficiency is added in the photo-alignment film 50 (alignment agent therefor). There is no need to introduce it. When the low molecular additive is added, a part of the unreacted low molecular additive is eluted into the liquid crystal layer 30, and the orientation of the liquid crystal compound 31 is lowered or the VHR is lowered due to the increased concentration of ionic impurities. Therefore, in particular, in applications where the liquid crystal layer 30 needs to exhibit a liquid crystal phase even at high temperatures (preferably in-vehicle applications), a bent tetracarboxylic dianhydride is preferable. On the other hand, the steric hindrance between the azobenzene group-containing polyimide polymer molecules is suppressed, so that image sticking is likely to occur when an AC voltage is applied for a long time. This is considered to be due to a decrease in density between polymer molecules in the photo-alignment film 50. More specifically, image sticking due to AC voltage application occurs because the liquid crystal compound 31 does not return to the original initial alignment state (when 0 V is applied) immediately after the voltage application is stopped. Here, the reason why the alignment of the liquid crystal compound 31 is difficult to return to the original state (it takes time to return) is that the stretched spring is difficult to return to the original state in the rheological way of thinking. Therefore, when the density of the polymer chains constituting the photo-alignment film 50 that controls the liquid crystal alignment is decreased, the spring constant is considered to be small (the alignment of the liquid crystal compound 31 is difficult to return to the original state), and image sticking by applying an AC voltage is considered. Is likely to occur. However, in this embodiment, since the inclination angle α is set to 7 ° or more in plan view, even in such a case, the occurrence of image sticking due to the application of a high AC voltage is effectively suppressed. be able to.

The low-molecular additive is a cross-linking agent that cross-links polyimide polymers and generally includes a low-molecular compound having 2 to 4 epoxy groups in one molecule. When a tetracarboxylic dianhydride that is not bent is used, if the polyimide polymer has a high molecular weight, intermolecular steric hindrance increases, and photoalignment control becomes difficult. Therefore, after performing photo-alignment treatment using a polyimide polymer with a relatively small molecular weight, the epoxy group of the low molecular additive and the carboxylic acid in the polyimide polymer are thermally reacted to increase the molecular weight of the polyimide polymer. .

The diamine having an azobenzene group (diamine for constituting Y in the above formulas (P-1) and (P-2)) is represented by any one of the following chemical formulas (Y-1) to (Y-5). It may be a compound. Any of these may be used alone or in combination of two or more.

The tetracarboxylic dianhydride having a bent molecular structure (tetracarboxylic dianhydride for constituting X in the above formulas (P-1) and (P-2)) is represented by the following chemical formula (X-1) It may be a compound represented by any one of (X-28). In particular, a compound represented by any of the following chemical formulas (X-6), (X-22), (X-23) or (X-27) is preferred. Any of these may be used alone or in combination of two or more.

The polyimide polymer (the polyamic acid and the polyimide) may have a structure derived from a cyclobutane ring. The cyclobutane ring undergoes a decomposition (cleavage) reaction upon irradiation with polarized ultraviolet rays (preferably linearly polarized ultraviolet rays). The cyclobutane ring is included in a structure derived from 1,2,3,4-cyclobutanetetracarboxylic dianhydride represented by the following chemical formula (Xa), and includes the above formulas (P-1) and (P-2). ) Included. In the case where the polyimide polymer has a structure derived from a cyclobutane ring, the structure derived from a diamine is not particularly limited, and is used for constituting Y in the above formulas (P-1) and (P-2). The diamine may be, for example, a compound represented by the following chemical formula (Ya).

The photo-alignment film 50 further contains a polymer obtained by polymerizing at least one monomer (hereinafter also referred to as an alignment monomer), and the alignment monomer is subjected to at least isomerization reaction and dimerization reaction by irradiation with polarized ultraviolet rays. It is preferable that one of the reactions occurs to exhibit orientation. As a result, the orientation monomer can be polymerized in a state in which the orientation is controlled and entangled with the main chain of the polyimide polymer, and the orientation state of the polyimide polymer can be more stably fixed, resulting in liquid crystal. The orientation state of the compound 31 can be more stably fixed. That is, the azimuth anchoring strength of the photo-alignment film 50 can be improved, and image sticking due to application of AC voltage can be more effectively suppressed. The polarized ultraviolet ray irradiated to the alignment monomer is preferably a linearly polarized ultraviolet ray.

As described above, when an unreacted component (for example, (meth) acrylic monomer or photo radical polymerization initiator) of the sealing material 40 eluted in the liquid crystal layer 30 is adsorbed on the surface of the photo-alignment film 50 without being controlled in orientation. The alignment regulating force (azimuth angle anchoring strength) of the photo-alignment film 50 further decreases and causes burn-in due to further AC voltage application. In such a case, the photo-alignment film 50 is obtained by polymerizing the alignment monomer. By including the polymer, it is possible to effectively suppress image sticking resulting from application of the AC voltage.

Although the specific example of the said orientation monomer is not specifically limited, It has a monomer which has a chalcone group which may have a substituent, a monomer which has a cinnamate group which may have a substituent, and a substituent. It is preferable to include at least one photoreactive monomer selected from the group consisting of monomers having a good coumarin group. The chalcone group, cinnamate group and coumarin group function as photofunctional groups.

Although the kind of said substituent is not specifically limited, A halogen group, a methyl group, a methoxy group, an ethyl group, and an ethoxy group can be mentioned as a suitable example. Any of these may be used alone or in combination of two or more. That is, the substituent preferably includes at least one substituent selected from the group consisting of a halogen group, a methyl group, a methoxy group, an ethyl group, and an ethoxy group. The at least one alignment monomer may contain a photoreactive monomer having a photofunctional group having a substituent and a photoreactive monomer having a photofunctional group having no substituent. As the halogen group, a fluoro group and a chloro group are preferred. In addition, when the said photofunctional group has a substituent, a substituent is normally substituted by the at least 1 hydrogen atom which ring structures, such as a phenylene group of the said photofunctional group, have. The photofunctional group may be a monovalent functional group, but is preferably a divalent cinnamate group represented by the following chemical formula (G-1), preferably represented by the following chemical formula (G-2). A divalent chalcone group and a divalent coumarin group represented by the following chemical formula (G-3).

The at least one orientation monomer preferably contains at least one monomer represented by the following chemical formula (1).

(In the formula, P ¹ and P ² are the same or different and each represents an acryloyloxy group, a methacryloyloxy group, an acryloylamino group, a methacryloylamino group, a vinyl group, or a vinyloxy group.
Sp ¹ and Sp ² are the same or different and each represents a linear, branched or cyclic alkylene group or alkyleneoxy group having 1 to 6 carbon atoms, or a direct bond.
At least one hydrogen atom of each phenylene group may be substituted. )

FIG. 5 is a schematic diagram illustrating a state of a polyimide polymer having an azobenzene group and a polymer of an alignment monomer in the photo-alignment film of the liquid crystal display device according to the first embodiment. FIG. 6 is a schematic diagram illustrating a molecular state in the photo-alignment film of the liquid crystal display device according to the first embodiment. FIG. 6A illustrates a polyimide polymer having an azobenzene group and an alignment monomer before irradiation with polarized ultraviolet rays. (B) shows the polymer of the polyimide-type polymer which has an azobenzene group after polarized ultraviolet irradiation, and the polymer of an orientation monomer. The orientation monomer represented by the chemical formula (1) has a chalcone group, and the chalcone group is oriented in the same direction as the azobenzene group by irradiation with linearly polarized ultraviolet rays, and is not only isomerized but also dimerized. Since the reaction also occurs, as shown in FIG. 5, the polymer 52 having a chalcone group is easily entangled in the main chain of the polyimide-based polymer 51 having an azobenzene group. Therefore, the alignment state of the liquid crystal compound 31 can be more stably fixed, and image sticking due to application of the AC voltage can be more effectively suppressed.

More specifically, as shown in FIGS. 6A and 6B, the chalcone group exhibits orientation by irradiation with linearly polarized ultraviolet rays, and the orientation monomer 53 having a chalcone group is a polyimide having an azobenzene group. Similar to the system polymer 51, it is oriented in the direction of 90 ° (easily aligned) with respect to the polarization axis (polarization direction) of the linearly polarized ultraviolet light to be irradiated, and coincides with the orientation control direction of the azobenzene group by irradiation with the polarized ultraviolet light. Further, the chalcone group can cause isomerization reaction and dimerization reaction, but in particular, the orientation of the polyimide polymer 51 having an azobenzene group can be effectively fixed by dimerization of the orientation monomer 53 having the chalcone group. Can do. Furthermore, the orientation of the polyimide polymer 51 having an azobenzene group can also be fixed by polymerization of the orientation monomer 53 having a chalcone group. Accordingly, at least one kind of orientation monomer represented by the above chemical formula (1) is added to an orientation agent containing a polyimide polymer having an azobenzene group, and the orientation of the azobenzene group, the polymerization of the orientation monomer, and the chalconyl group. By performing the exposure for the orientation of the polyimide, the orientation state of the polyimide polymer having an azobenzene group can be more stably fixed.

The said effect by the orientation monomer represented by the said Chemical formula (1) can be acquired similarly, also when a polyimide-type polymer has a structure originating in a cyclobutane ring.

In the chemical formula (1), at least one hydrogen atom of the phenylene group is the same or different and is substituted with a halogen atom (preferably a fluorine atom or a chlorine atom), a methyl group, a methoxy group, an ethyl group, or an ethoxy group. May be.

More specific and preferred examples of the orientation monomer represented by the chemical formula (1) include a monomer represented by either the following chemical formula (1-1) or (1-2). Any of these may be used alone or in combination of two or more. Like these monomers, when an alkyl group is introduced between at least one polymerizable group and a chalconyl group, the flexibility in the molecular structure is improved and the degree of alignment control by irradiation with polarized ultraviolet rays can be improved. Is possible.

(Wherein p and q are the same or different and are 0 or 1, and m and n are the same or different and are integers of 0 to 6)

More specific and preferred examples of the orientation monomer represented by the chemical formula (1) include monomers represented by any of the following chemical formulas (2-1) to (2-5). Any of these may be used alone or in combination of two or more.

<Other configurations>
A polarizing plate (linear polarizer) 60 may be disposed on the opposite side of the pair of

substrates

10 and 20 from the liquid crystal layer 30. The polarizing plate 60 typically includes a polyvinyl alcohol (PVA) film obtained by adsorbing and orienting an anisotropic material such as an iodine complex having dichroism. Usually, a protective film such as a triacetyl cellulose film is laminated on both sides of the PVA film and put to practical use. An optical film such as a retardation film may be disposed between the polarizing plate 60 and the pair of

substrates

10 and 20.

The transmission axes of the pair of polarizing plates 60 are preferably orthogonal to each other. According to such a configuration, since the pair of polarizing plates 60 are arranged in crossed Nicols, a good black display state can be realized when no voltage is applied.

In the present specification, that two axes (directions) are orthogonal means that an angle (absolute value) between the two axes (direction) is within a range of 90 ± 3 ° unless otherwise specified, preferably 90 ±. It is within the range of 1 °, more preferably within the range of 90 ± 0.5 °, and particularly preferably 90 ° (fully orthogonal).

In plan view, the initial alignment direction 31 a of the liquid crystal compound 31 may be parallel to one polarization axis of the pair of polarizing plates 60 and may be orthogonal to the other polarization axis. As a result, the control method of the liquid crystal display device 100 can be set to a so-called normally black mode in which black display is performed with no voltage applied.

As shown in FIGS. 1 and 3, in the liquid crystal display device of the present embodiment, a backlight 70 is disposed on the back side of the liquid crystal panel. A liquid crystal display device having such a configuration is generally called a transmissive liquid crystal display device. The backlight 70 is not particularly limited as long as it emits light including visible light, may emit light including only visible light, and emits light including both visible light and ultraviolet light. It may be.

The liquid crystal display device of the present embodiment includes an external circuit such as a TCP (tape carrier package) and a PCB (printed wiring board) in addition to the liquid crystal panel and the backlight 70; an optical film such as a viewing angle widening film and a brightness enhancement film. A plurality of members such as a bezel (frame), and some members may be incorporated in other members. Members other than those already described are not particularly limited, and those normally used in the field of liquid crystal display devices can be used, and thus description thereof is omitted.

In the present embodiment, the case where the liquid crystal drive mode of the liquid crystal display device 100 is the FFS mode is described in detail. However, the liquid crystal drive mode according to the present embodiment is particularly limited as long as it is a horizontal electric field type horizontal alignment mode. Alternatively, the IPS mode may be used.

In the IPS mode, for example, a pair of comb electrodes is provided on at least one of the

substrates

10 and 20, and a lateral electric field is formed in the liquid crystal layer 30. As the pair of comb-shaped electrodes, for example, an electrode pair that includes a plurality of comb-tooth portions and is arranged so that the comb-tooth portions mesh with each other can be used. In the IPS mode, a pair of comb electrodes functions as the pixel electrode 25 and the common electrode 26. Moreover, the linear part 27 is contained in each comb-tooth part of each comb-shaped electrode.

<Method for manufacturing liquid crystal display device>
Next, a manufacturing method of the liquid crystal display device of this embodiment will be described. The manufacturing method of the liquid crystal display device of the present embodiment includes a preparation step of preparing a pair of substrates, at least one polymer of polyamic acid and polyimide, and at least one monomer on at least one surface of the pair of substrates. A film forming step of forming a photo-alignment film by applying an alignment agent contained therein, and irradiating the photo-alignment film with polarized ultraviolet rays to align the at least one polymer and align and polymerize the at least one monomer. Including at least one irradiation step, and the at least one monomer may be a method for producing a liquid crystal display device that exhibits orientation by causing at least one of an isomerization reaction and a dimerization reaction by irradiation with polarized ultraviolet rays.

Hereinafter, although each process is further demonstrated, since each member, a polymer, and a monomer are as having mentioned above, description is abbreviate | omitted.

In the preparation step of preparing a pair of substrates, for example, a pair of

substrates

10 and 20 are prepared.

In the method of manufacturing a liquid crystal display device according to the present embodiment, at least one (preferably both) of the pair of substrates has at least one polymer (polyimide polymer) of polyamic acid and polyimide, and at least one monomer (alignment). A film forming step of forming a photo-alignment film (that is, a polyimide-based polymer has a photofunctional group) by applying an aligning agent containing a photopolymerizable monomer), and the at least one monomer is a polarized ultraviolet ray Irradiation causes at least one of an isomerization reaction and a dimerization reaction (preferably at least a dimerization reaction) to exhibit orientation.

In the film forming step, first, an alignment agent is prepared by dissolving a polyimide polymer and an alignment monomer in a solvent (for example, an organic solvent). The alignment agent may contain other optional components as necessary, and is preferably prepared as a solution-like composition in which each component is dissolved in a solvent. As said organic solvent, the thing which melt | dissolves a polyimide-type polymer, an orientation monomer, and another arbitrary component, and does not react with these is suitable. As said other arbitrary component, polymers other than the said polyimide-type polymer, a hardening | curing agent, a hardening accelerator, a catalyst etc. can be mentioned, for example. Polymers other than the above polyimide-based polymers can be used to further improve the solution properties of the aligning agent and the electrical properties of the photo-alignment film. Examples of such polymers include no photofunctional groups. General polymers for alignment films are listed.

The alignment monomer added to the alignment agent is 3% by weight or more and less than 30% by weight with respect to the polyimide polymer having a photofunctional group (when the polyimide polymer having a photofunctional group is 100% by weight). It is preferably 5 wt% or more and 25 wt% or less, more preferably 10 wt% or more and 20 wt% or less. If it is less than 3% by weight, there is a possibility that the effect of suppressing the AC image sticking is insufficient due to the orientation monomer, and if it exceeds 30% by weight, the contrast may be greatly lowered.

Next, an alignment agent is applied on the surface of each substrate. The coating method is not particularly limited, and examples thereof include a roll coater method, a spinner method, a printing method, and an ink jet method.

Next, each substrate is heated. Thereby, the solvent in the aligning agent is volatilized and a photo-alignment film is formed. Heating may be performed in two stages of pre-baking (pre-baking) and main baking (post-baking). When the alignment agent contains an alignment film polymer that does not have a photofunctional group, the formed photo alignment film may have a two-layer structure, mainly from the alignment film polymer that does not have a photofunctional group. You may have the comprised lower layer and the upper layer comprised mainly from the polyimide-type polymer which has a photofunctional group. The upper layer is in contact with the liquid crystal layer.

In the method of manufacturing a liquid crystal display device according to this embodiment, the photo-alignment film is irradiated with polarized ultraviolet rays to align the at least one polymer (polyimide polymer) and align the at least one monomer (orientation monomer). And an irradiation step for polymerization. As a result, as described above, the orientation of the polyimide polymer having a photofunctional group is controlled, and the orientation monomer is polymerized in a controlled orientation, thereby fixing the orientation of the polyimide polymer having the photofunctional group. be able to. Therefore, since the azimuth anchoring strength of the photo-alignment film can be improved, it is possible to reduce image sticking due to application of an AC voltage. The polarized ultraviolet light to be irradiated is preferably linearly polarized ultraviolet light.

The wavelength of the polarized ultraviolet light may be 200 nm or more and 430 nm or less. A more preferable lower limit of the wavelength is 250 nm, and a more preferable upper limit is 380 nm. Dose of the polarized ultraviolet is, 0.3 J / cm ² or more, may be 20 J / cm ² or less. A more preferable lower limit of the irradiation amount is 1 J / cm ² , and a more preferable upper limit is 5 J / cm ² .

One of the pair of substrates includes a pixel electrode and a common electrode, and at least one of the pixel electrode and the common electrode includes a linear portion. The photo-alignment film is formed on the surface of the substrate including the pixel electrode and the common electrode (more preferably both substrates). In the irradiation step, the angle formed by the polarization axis direction (polarization direction) with respect to the linear portion is 83. It is preferable to irradiate the above-mentioned photo-alignment film with polarized ultraviolet rays so that the temperature is not more than 0 °. Thereby, it can be easily made 7 ° or more in a plan view of the inclination angle of the linear portion with respect to the initial orientation direction of the liquid crystal compound. For this reason, it is possible to further reduce the burn-in resulting from the AC voltage application.

In the irradiation step, it is more preferable to irradiate the photo-alignment film with polarized ultraviolet rays so that an angle formed by a polarization axis direction (polarization direction) with respect to the linear portion is 77 ° or more. As a result, the inclination angle of the linear portion with respect to the initial alignment direction of the liquid crystal compound can be easily reduced to 13 ° or less in plan view. Therefore, it is possible to suppress a decrease in transmittance and contrast.

After the above steps, the liquid crystal display device of this embodiment is completed through a liquid crystal layer forming step, a polarizing plate attaching step, and a control step, a power supply portion, a backlight attaching step, and the like.

Note that, in the liquid crystal layer forming step, a liquid crystal composition containing a liquid crystal material is usually sealed between a pair of substrates bonded by a sealing material.

The liquid crystal layer can be formed by, for example, filling a liquid crystal composition between a pair of substrates by a vacuum injection method or a drop injection method. When the vacuum injection method is adopted, a liquid crystal layer is formed by applying a sealing material, bonding a pair of substrates, curing the sealing material, injecting a liquid crystal composition, and sealing the injection port in this order. To do. When the dropping injection method is employed, a liquid crystal layer is formed by applying a sealing material, dropping a liquid crystal composition, bonding a pair of substrates, and curing the sealing material in this order.

As described above, the liquid crystal material has positive dielectric anisotropy. The liquid crystal material may contain a liquid crystal compound having an alkenyl group. The liquid crystal material may contain one or more liquid crystal compounds.

When the liquid crystal display device is in a normally black mode, for example, on the outside of the pair of substrates, a pair of polarizing plates are arranged in crossed Nicols so that the absorption axes are orthogonal to each other, and the absorption axes of the pair of polarizing plates; It arrange | positions so that the angle which the polarization axis direction (polarization direction) of the polarized ultraviolet rays (preferably linearly polarized ultraviolet rays) irradiated to a photo-alignment film may be 0 degree or 90 degrees. In a state where a voltage equal to or higher than the threshold is not applied to the liquid crystal layer, the light from the backlight does not pass through the liquid crystal layer and is displayed in black. When a voltage higher than the threshold is applied to the liquid crystal layer, the angle formed between the absorption axis of the pair of polarizing plates arranged in the crossed Nicols and the liquid crystal director becomes larger than 0 ° (for example, 45 °), and the light from the backlight Transmits through the liquid crystal layer.

As mentioned above, although embodiment of this invention was described, each described matter can be applied with respect to this invention altogether.

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples.

<Example 1-1>
(Production of liquid crystal panel)
An FFS mode liquid crystal panel was actually produced by the following method. First, a planar electrode (lower layer electrode) having an FFS electrode structure made of indium tin oxide (ITO), a TFT substrate on which an insulating film and a slit electrode (upper layer electrode) are stacked, and a counter electrode having no electrode A substrate was prepared. Next, an aligning agent A containing polyamic acid having an azobenzene group in the main chain, represented by the following chemical formula (P-1a), was applied to both substrates.

(Wherein X includes at least a structure derived from X1, and Y includes at least a structure derived from Y1.)

Next, preliminary baking is performed at 60 to 80 ° C. (2 minutes), followed by irradiation with 1 to 3 J / cm ² of linearly polarized light (including 300 to 500 nm ultraviolet rays), and subsequently 170 to 180 ° C. (10 to 10 ° C.). 20 minutes) is performed (first stage firing) and 220 to 230 ° C. (20 to 30 minutes) firing (second stage firing). Thus, the photo-alignment film is formed on each substrate. Formed.

Subsequently, on one substrate, a UV and thermosetting sealant (manufactured by Sekisui Chemical Co., Ltd., Photorec; this sealant is composed of (meth) acrylic monomer, photoradical polymerization initiator, epoxy monomer, epoxy A curing material, a silane coupling agent, and an inorganic filler are drawn. In addition, a positive type liquid crystal material having a positive dielectric anisotropy (Δε = 2.8) and a liquid crystal phase-isotropic phase transition point (T _NI ) of 95 ° C. at a predetermined position on the other substrate. It was dripped. This positive type liquid crystal material was composed of a compound having an alkenyl group and a positive type liquid crystal compound. Subsequently, both the substrates were bonded together under vacuum, and the sealing material was cured by irradiating with ultraviolet rays (including 300 to 500 nm ultraviolet rays) to produce a liquid crystal panel. Subsequently, the liquid crystal panel was heated at 110 to 140 ° C. for about 40 minutes to thermally cure the sealing material and to make the liquid crystal layer isotropic, and then the liquid crystal panel was cooled to room temperature. Finally, a pair of polarizing plates was attached to the liquid crystal panel to complete a normally black mode and FFS mode liquid crystal panel.

As shown in FIG. 3, the slit electrode 24 has a V-shaped structure, and the inclination angle α of the linear portion 27 with respect to the initial alignment azimuth 31a of the liquid crystal compound is 7 ° in plan view.

<Example 1-2>
A liquid crystal panel of this example was produced in the same manner as in Example 1-1, except that the inclination angle α was 10 ° in plan view.

<Example 1-3>
A liquid crystal panel of this example was produced in the same manner as in Example 1-1 except that the inclination angle α was 13 ° in plan view.

<Example 1-4>
A liquid crystal panel of this example was produced in the same manner as in Example 1-1 except that the inclination angle α was 15 ° in plan view.

<Comparative Example 1>
A liquid crystal panel of this comparative example was produced in the same manner as in Example 1-1 except that the inclination angle α was 5 ° in plan view.

<Characteristic evaluation 1>
The FFS mode liquid crystal panels produced in Examples 1-1 to 1-4 and Comparative Example 1 were evaluated for the following characteristics.

(Response characteristics)
Using a Photo 5200 (manufactured by Otsuka Electronics Co., Ltd.), response speed (rise time (τr) and fall time (τd)) at 25 ° C. between application of 0.5 V and application of voltage with maximum transmittance. Were measured and summed.

(Contrast measurement)
The measurement was performed in a dark room at 25 ° C. using a spectroradiometer SR-1 manufactured by Topcon Technohouse.

(AC burn-in observation by high temperature current test)
In an oven at 90 ° C., the display area was left for 1000 hours with an AC voltage of 6 V and an AC voltage of 0.5 V applied to each of the two display areas. The degree of image sticking when an intermediate voltage was applied was observed to determine the image sticking rate. The burn-in rate was determined based on the method described in Non-Patent Document 1.

The results are shown in Table 1 below.

From the results shown in Table 1, the response speed increased as the inclination angle α increased from 5 ° to 15 °, but the contrast tended to decrease. The response speed increased because the rotation angle of the liquid crystal director (change in the azimuth direction of the liquid crystal compound) with voltage application decreased with increasing tilt angle α. For the same reason, the contrast was reversed. Declined. Contrast reduction is also caused by an increase in black transmittance on the low voltage side as the tilt angle α increases. On the other hand, the image sticking rate in the high-temperature energization test decreased as the inclination angle α increased. This is also presumed to be because the rotation angle of the liquid crystal director at the time of voltage application became smaller as the tilt angle α increased. From the above results, it was confirmed that the inclination angle α at which high-speed response, high contrast, and low image sticking are in the range of 7 ° to 13 ° is suitable.

<Example 2-1>
(Production of liquid crystal panel)
An FFS mode liquid crystal panel was actually produced by the following method. First, a planar electrode (lower electrode) having an FFS electrode structure made of indium tin oxide (ITO), a TFT substrate on which an insulating film and a slit electrode (upper electrode) are stacked, and a counter substrate having no electrode are prepared. did. Next, an aligning agent A containing a polyamic acid containing an azobenzene group in the main chain represented by the following chemical formula (P-1b) was applied to both substrates.

(In the formula, X contains at least a structure derived from X2, and Y contains at least a structure derived from Y2.)

Next, preliminary baking is performed at 60 to 80 ° C. (2 minutes), followed by irradiation with 3 to 5 J / cm ² of linearly polarized light (including 300 to 500 nm ultraviolet rays), and subsequently 110 to 130 ° C. (10 to 10 ° C.). A photo-alignment film was formed on each substrate by performing main firing including firing at 20 minutes (first stage firing) and firing at 230 ° C. (30 to 40 minutes) (second stage firing). .

Subsequently, on one substrate, a UV and thermosetting sealant (manufactured by Sekisui Chemical Co., Ltd., Photorec; this sealant is composed of (meth) acrylic monomer, photoradical polymerization initiator, epoxy monomer, epoxy A curing material, a silane coupling agent, and an inorganic filler are drawn. Further, a positive type liquid crystal having a positive dielectric anisotropy (Δε = 3.3) and a liquid crystal phase-isotropic phase transition point (T _NI ) of 97.5 ° C. at a predetermined position on the other substrate. The material was added dropwise. This positive type liquid crystal material was composed of a compound having an alkenyl group and a positive type liquid crystal compound. Subsequently, both the substrates were bonded together under vacuum, and the sealing material was cured by irradiating with ultraviolet rays (including 300 to 500 nm ultraviolet rays) to produce a liquid crystal panel. Subsequently, the liquid crystal panel was heated at 110 to 140 ° C. for about 30 minutes to thermally cure the sealing material and to make the liquid crystal layer isotropic, and then the liquid crystal panel was cooled to room temperature. Finally, a pair of polarizing plates was attached to the liquid crystal panel to complete a normally black mode and FFS mode liquid crystal panel.

<Example 2-2>
A liquid crystal panel of this example was fabricated in the same manner as in Example 2-1, except that the inclination angle α was 10 ° in plan view.

<Example 2-3>
A liquid crystal panel of this example was produced in the same manner as in Example 2-1, except that the inclination angle α was 13 ° in plan view.

<Example 2-4>
A liquid crystal panel of this example was produced in the same manner as in Example 2-1, except that the inclination angle α was 15 ° in plan view.

<Comparative example 2>
A liquid crystal panel of this comparative example was produced in the same manner as in Example 2-1, except that the inclination angle α was 5 ° in plan view.

<Characteristic evaluation 2>
For the FFS mode liquid crystal panels produced in Examples 2-1 to 2-4 and Comparative Example 2, the above characteristic evaluation was performed in the same manner as in Example 1-1. The results are shown in Table 2 below.

From the results shown in Table 2, even when the liquid crystal material T _{NI is set} to 97.5 ° C., the inclination angle α is increased from 5 ° to 15 ° as in the case of Examples 1-1 to 1-4 and Comparative Example 1. As the response speed increased, the contrast decreased. Further, the burn-in rate in the high-temperature energization test showed the same tendency as in Examples 1-1 to 1-4 and Comparative Example 1, and became smaller as the inclination angle α increased. From the above results, it was confirmed that the inclination angle α at which high-speed response, high contrast, and low image sticking are in the range of 7 ° to 13 ° is suitable.

<Example 3-1>
(Production of liquid crystal panel)
An FFS mode liquid crystal panel was actually produced by the following method. First, a planar electrode (lower electrode) having an FFS electrode structure made of indium tin oxide (ITO), a TFT substrate on which an insulating film and a slit electrode (upper electrode) are stacked, and a counter substrate having no electrode are prepared. did. Next, an aligning agent A containing polyamic acid having an azobenzene group in the main chain, represented by the above chemical formula (P-1a), was applied to both substrates.

Subsequently, on one substrate, a UV and thermosetting sealant (manufactured by Sekisui Chemical Co., Ltd., Photorec; this sealant is composed of (meth) acrylic monomer, photoradical polymerization initiator, epoxy monomer, epoxy A curing material, a silane coupling agent, and an inorganic filler are drawn. Further, a positive type liquid crystal material having a positive dielectric anisotropy (Δε = 2.5) and a liquid crystal phase-isotropic phase transition point (T _NI ) of 95 ° C. at a predetermined position on the other substrate. It was dripped. This positive type liquid crystal material was composed of a compound having an alkenyl group and a positive type liquid crystal compound. Subsequently, both the substrates were bonded together under vacuum, and the sealing material was cured by irradiating with ultraviolet rays (including 300 to 500 nm ultraviolet rays) to produce a liquid crystal panel. Subsequently, the liquid crystal panel was heated at 110 to 140 ° C. for about 40 minutes to thermally cure the sealing material and to make the liquid crystal layer isotropic, and then the liquid crystal panel was cooled to room temperature. Finally, a pair of polarizing plates was attached to the liquid crystal panel to complete a normally black mode and FFS mode liquid crystal panel.

As shown in FIG. 3, the slit electrode 24 has a V-shaped structure, and the inclination angle α of the linear portion 27 with respect to the initial alignment azimuth 31a of the liquid crystal compound is 10 ° in plan view.

<Example 3-2>
A liquid crystal panel of this example was produced in the same manner as in Example 3-1, except that the dielectric anisotropy Δε of the positive liquid crystal material was 3.3.

<Example 3-3>
A liquid crystal panel of this example was produced in the same manner as in Example 3-1, except that the dielectric anisotropy Δε of the positive liquid crystal material was set to 4.0.

<Characteristic evaluation 3>
With respect to the FFS mode liquid crystal panels manufactured in Examples 3-1 to 3-3, the above characteristic evaluation was performed in the same manner as in Example 1-1. The results are shown in Table 3 below.

From the results shown in Table 3, the response characteristics, contrast, and burn-in rate deteriorated as Δε of the liquid crystal material increased. Since the polarity of the liquid crystal material increases as Δε increases, unreacted components in the seal material (presumably mainly (meth) acrylic monomers or radical polymerization initiators) are likely to elute into the liquid crystal layer, and the eluted unreacted components As a result of the components adsorbed on the surface of the photo-alignment film, it is considered that the alignment regulating force (anchoring strength) is further reduced and the image sticking rate is increased. In general, as Δε increases, the rotational viscosity coefficient of the liquid crystal material also increases. Therefore, the response speed decreases as Δε of the liquid crystal material increases. Further, the black transmittance when a low voltage is applied is slightly deteriorated with an increase in Δε, so that it is considered that the contrast decreases as Δε of the liquid crystal material increases. From the above results, it is considered that Δε of the positive liquid crystal material is preferably less than 3.5.

<Example 4-1>
(Alignment agent adjustment)
A monomer (orienting monomer) having a chalconyl group represented by the following chemical formula (2-2) is added to the aligning agent A containing a polyamic acid having an azobenzene group in the main chain represented by the chemical formula (P-1a). The alignment agent B1 was prepared by adding 10% by weight to the total weight of the solute of the alignment agent A (total weight of the polyamic acid represented by the chemical formula (P-1a)).

(Production of liquid crystal panel)
An FFS mode liquid crystal panel was actually produced by the following method. First, a planar electrode (lower electrode) having an FFS electrode structure made of indium tin oxide (ITO), a TFT substrate on which an insulating film and a slit electrode (upper electrode) are stacked, and a counter substrate having no electrode are prepared. did. Next, the alignment agent B1 was applied to both substrates.

Next, pre-baking is performed at 60 to 80 ° C. (2 minutes), followed by irradiation with 4 to 7 J / cm ² of linearly polarized light (including 300 to 500 nm ultraviolet rays) to perform uniaxial alignment treatment of the azobenzene group. At the same time, the monomer represented by the chemical formula (2-2) was polymerized. Subsequently, by performing main firing including firing at 170 to 180 ° C. (20 to 30 minutes) (first stage firing) and firing at 220 to 230 ° C. (20 to 30 minutes) (second stage firing). A photo-alignment film was formed on each substrate.

<Example 4-2>
Instead of the aligning agent B1, the aligning agent A containing a polyamic acid containing an azobenzene group in the main chain represented by the chemical formula (P-1a) has a chalcone group represented by the chemical formula (2-2). An aligning agent prepared by adding a monomer (orienting monomer) to 20 wt% with respect to the total weight of the solute of the aligning agent A (the total weight of the polyamic acid represented by the chemical formula (P-1a)). A liquid crystal panel of this example was produced in the same manner as in Example 4-1, except that B2 was used.

<Example 4-3>
Instead of the aligning agent B1, the aligning agent A containing a polyamic acid containing an azobenzene group in the main chain represented by the chemical formula (P-1a) has a chalcone group represented by the chemical formula (2-2). An aligning agent prepared by adding a monomer (orienting monomer) to 30% by weight with respect to the total weight of the solute of the aligning agent A (the total weight of the polyamic acid represented by the chemical formula (P-1a)). A liquid crystal panel of this example was produced in the same manner as in Example 4-1, except that B3 was used.

<Example 4-4>
Instead of the aligning agent B1, the aligning agent A containing a polyamic acid containing an azobenzene group in the main chain represented by the chemical formula (P-1a) has a chalcone group represented by the chemical formula (2-2). An aligning agent prepared by adding a monomer (orienting monomer) to 40% by weight with respect to the total weight of the solute of the aligning agent A (the total weight of the polyamic acid represented by the chemical formula (P-1a)). A liquid crystal panel of this example was produced in the same manner as in Example 4-1, except that B4 was used.

<Example 4-0>
In the same manner as in Example 4-1, except that the aligning agent A containing a polyamic acid containing an azobenzene group in the main chain, represented by the chemical formula (P-1a), was used instead of the aligning agent B1. The liquid crystal panel of the example was produced.

<Characteristic evaluation 4>
With respect to the FFS mode liquid crystal panels manufactured in Examples 4-0 to 4-4, the above characteristic evaluation was performed in the same manner as in Example 1-1. The results are shown in Table 4 below.

From the results shown in Table 4, the burn-in rate was greatly reduced by adding the monomer having the chalconyl group to the photo-alignment film material and polymerizing the monomer during exposure of the photo-alignment film. From this, it was confirmed that the alignment control of the liquid crystal compound is stabilized by forming a polymer of a monomer having a chalcone group in the photo-alignment film. This is presumably because the anchoring strength (particularly the azimuth anchoring strength) of the photo-alignment film has increased. On the other hand, the response characteristics were almost constant with respect to the added amount of the monomer, but the contrast was greatly reduced when 30% by weight of the monomer was added. This is presumed that when the photo-alignment film having 30% by weight of the monomer was formed, it was not a transparent film but a white turbid film, so that a significant decrease in contrast due to scattering occurred. At 40% by weight, the photo-alignment film became more turbid, and the contrast reduction due to scattering became more remarkable. From the above, it was confirmed that by adding a monomer having a chalconyl group to the photo-alignment film, the alignment control power is improved and the image sticking due to the application of the AC voltage is reduced. Moreover, in order to suppress the significant fall of the contrast by scattering, it turned out that it is preferable to add the monomer which has a chalconyl group with the density | concentration of less than 30 weight% with respect to the solute (polyamic acid) of an orientation agent.

<Example 5-1>
(Alignment agent adjustment)
A monomer (orienting monomer) having a chalcone group represented by the above chemical formula (2-2) is added to the aligning agent C containing a polyamic acid having a cyclobutane ring in the main chain represented by the following chemical formula (P-1c). The alignment agent D1 was prepared by adding 10% by weight to the total weight of the solute of the alignment agent C (total weight of the polyamic acid represented by the following chemical formula (P-1c)).

(Production of liquid crystal panel)
An FFS mode liquid crystal panel was actually produced by the following method. First, a planar electrode (lower electrode) having an FFS electrode structure made of indium tin oxide (ITO), a TFT substrate on which an insulating film and a slit electrode (upper electrode) are stacked, and a counter substrate having no electrode are prepared. did. Next, the alignment agent D1 was applied to both substrates.

Next, after pre-baking at 60 to 80 ° C. (2 minutes), main baking is performed at 190 to 200 ° C. (20 to 30 minutes), followed by 0.5 to ² J / cm ² linearly polarized light (250 (Including ultraviolet rays of up to 360 nm) and uniaxial orientation treatment of the cyclobutane ring, and at the same time, polymerization of the monomer represented by the chemical formula (2-2) was performed. Subsequently, by baking at 220 to 220 ° C. (30 to 40 minutes), a photo-alignment film was formed on each substrate.

<Example 5-2>
Instead of the aligning agent D1, the aligning agent C containing a polyamic acid containing a cyclobutane ring in the main chain represented by the chemical formula (P-1c) has a chalcone group represented by the chemical formula (2-2). An aligning agent prepared by adding a monomer (orienting monomer) to 20 wt% with respect to the total weight of the solute of the aligning agent C (the total weight of the polyamic acid represented by the chemical formula (P-1c)). A liquid crystal panel of this example was produced in the same manner as in Example 5-1, except that D2 was used.

<Example 5-3>
Instead of the aligning agent D1, the aligning agent C containing a polyamic acid containing a cyclobutane ring in the main chain represented by the chemical formula (P-1c) has a chalcone group represented by the chemical formula (2-2). An aligning agent prepared by adding a monomer (orienting monomer) to 30% by weight with respect to the total weight of the solute of the aligning agent C (the total weight of the polyamic acid represented by the chemical formula (P-1c)). A liquid crystal panel of this example was produced in the same manner as in Example 5-1, except that D3 was used.

<Example 5-4>
Instead of the aligning agent D1, the aligning agent C containing a polyamic acid containing a cyclobutane ring in the main chain represented by the chemical formula (P-1c) has a chalcone group represented by the chemical formula (2-2). An aligning agent prepared by adding a monomer (orienting monomer) so as to be 40% by weight with respect to the total weight of the solute of the aligning agent C (the total weight of the polyamic acid represented by the chemical formula (P-1c)). A liquid crystal panel of this example was produced in the same manner as in Example 5-1, except that D4 was used.

<Example 5-0>
In the same manner as in Example 5-1, except that the aligning agent C containing a polyamic acid containing a cyclobutane ring in the main chain, represented by the chemical formula (P-1c), was used instead of the aligning agent D1. The liquid crystal panel of the example was produced.

<Characteristic evaluation 5>
With respect to the FFS mode liquid crystal panels manufactured in Examples 5-0 to 5-4, the above characteristic evaluation was performed in the same manner as in Example 1-1. The results are shown in Table 5 below.

From the results shown in Table 5, the cyclobutane ring originally has a cyclobutane ring by adding the monomer having the chalconyl group to the photo-alignment film material having a cyclobutane ring and also polymerizing the monomer during the exposure of the photo-alignment film. Although the degree of image sticking of the photo-alignment film was small, the image sticking rate was further reduced. From this, it was confirmed that the alignment control of the liquid crystal compound is stabilized also by forming a polymer of a monomer having a chalcone group in a photo-alignment film (decomposed type) having a cyclobutane ring. This is presumably because the anchoring strength (particularly the azimuth anchoring strength) of the photo-alignment film is further increased. On the other hand, the response characteristics were almost the same as in Example 4 and were almost constant with respect to the added amount of the monomer, but the contrast was greatly lowered when 30% by weight of the monomer was added. This is presumed that when the photo-alignment film having 30% by weight of the monomer was formed, it was not a transparent film but a white turbid film, so that a significant decrease in contrast due to scattering occurred. Regarding the contrast, the photo-alignment film having a cyclobutane ring was slightly lower than the photo-alignment film having an azobenzene group. This is thought to be due to the difference in the degree of orientation control of the photo-alignment film by polarized ultraviolet rays. At 40% by weight, the photo-alignment film became more turbid, and the contrast reduction due to scattering became more remarkable. From the above, it was confirmed that by adding a monomer having a chalconyl group to the photo-alignment film having a cyclobutane ring, the alignment control power is improved and the image sticking due to the AC voltage application is reduced. Moreover, in order to suppress the significant fall of the contrast by scattering, it turned out that it is preferable to add the monomer which has a chalconyl group with the density | concentration of less than 30 weight% with respect to the solute (polyamic acid) of an orientation agent.

<Example 6-1>
(Production of liquid crystal panel)
An FFS mode liquid crystal panel was actually produced by the following method. First, a planar electrode (lower electrode) having an FFS electrode structure made of indium tin oxide (ITO), a TFT substrate on which an insulating film and a slit electrode (upper electrode) are stacked, and a counter substrate having no electrode are prepared. did. Next, an orientation agent containing polyamic acid represented by the chemical formula (P-1a) and containing an azobenzene group in the main chain (the low molecular additive was not introduced) was applied to both substrates.

<Example 6-2>
Except for using a polyamic acid represented by the following chemical formula (P-1d) represented by the following chemical formula (P-1a), a polyamic acid comprising an azobenzene group contained in the main chain, instead of the polyamic acid represented by the chemical formula (P-1a). In the same manner as in Example 6-1, a liquid crystal panel of this example was produced. Also in this example, no low molecular additive was introduced into the light distribution agent.

(In the formula, X includes at least a structure derived from X3, and Y includes at least a structure derived from Y3.)

<Characteristic evaluation 6>
With respect to the FFS mode liquid crystal panels produced in Examples 6-1 and 6-2, the above characteristic evaluation was performed in the same manner as in Example 1-1. The results are shown in Table 6 below.

From the results shown in Table 6, when the tetracarboxylic dianhydride having the bent structure represented by the chemical formula (P-1a) is used, the tetracarboxylic acid dihydrate having no bent structure represented by the chemical formula (P-1d) is used. High contrast was obtained compared to the case of using an anhydride. This is probably because the polyamic acid represented by the chemical formula (P-1a) was higher in the orientation state due to isomerization of the azobenzene group by irradiation with polarized ultraviolet rays than the polyamic acid represented by the chemical formula (P-1d). On the other hand, the seizure resulting from the application of AC voltage over a long period of time was higher (bad) when the polyamic acid represented by the chemical formula (P-1a) was used. The polyamic acid represented by the above chemical formula (P-1a) has low molecular steric hindrance due to the bending of the polymer, and therefore has high molecular mobility, and as a result, there is a slight seizure resulting from application of AC voltage over a long period of time. It got worse.

[Appendix]
One embodiment of the present invention includes a liquid crystal layer containing a liquid crystal material having a positive dielectric anisotropy, a sealant disposed so as to surround the liquid crystal layer in a plan view, and a pair of sandwiching the liquid crystal layer A substrate and a photo-alignment film provided on at least one surface of the pair of substrates, the photo-alignment film containing at least one of polyamic acid and polyimide (polyimide polymer), and the liquid crystal material The liquid crystal compound in the substrate is aligned horizontally with respect to the substrate surface, and one of the pair of substrates includes a pixel electrode and a common electrode, and at least one of the pixel electrode and the common electrode is linear. The liquid crystal display device may be characterized in that an inclination angle of the linear portion with respect to an initial alignment direction of the liquid crystal compound is 7 ° or more in plan view. The liquid crystal display device includes a photo-alignment film that aligns the liquid crystal compound in a horizontal direction with respect to the substrate surface, and the inclination angle of the linear portion with respect to the initial alignment direction of the liquid crystal compound is 7 ° or more in plan view. Therefore, image sticking due to the application of the AC voltage can be suppressed.

The inclination angle may be 13 ° or less. Thereby, it is possible to suppress a decrease in transmittance and contrast.

The polyamic acid and the polyimide may have a structure derived from a diamine having an azobenzene group and a structure derived from a tetracarboxylic dianhydride having a bent molecular structure. Even in this case, it is possible to effectively suppress the occurrence of image sticking due to application of a high AC voltage.

The tetracarboxylic dianhydride having a bent molecular structure may include at least one tetracarboxylic dianhydride represented by any one of the following chemical formulas (X-1) to (X-28).

The tetracarboxylic dianhydride having a bent molecular structure is at least one tetracarboxylic dianhydride represented by any one of the chemical formulas (X-6), (X-22), (X-23) or (X-27). Carboxylic dianhydrides may be included.

The polyamic acid and the polyimide may have a structure derived from a cyclobutane ring.

The liquid crystal material may have a dielectric anisotropy of 1 or more and less than 3.5. Even in this case, it is possible to effectively suppress the occurrence of image sticking due to application of a high AC voltage. Further, the response performance of the liquid crystal material can be improved and the speed can be increased.

The nematic phase-isotropic phase transition point of the liquid crystal material may be 95 ° C. or higher. Thereby, the said liquid crystal display device can be made suitable for a vehicle-mounted use, a ship use, an aviation use, etc.

The sealing material may contain a (meth) acrylic monomer, a radical polymerization initiator, an epoxy monomer, and an epoxy curing material. Even in this case, it is possible to effectively suppress the occurrence of image sticking due to application of a high AC voltage.

The photo-alignment film further contains a polymer obtained by polymerizing at least one monomer (alignment monomer), and the at least one monomer reacts with at least one of an isomerization reaction and a dimerization reaction by irradiation with polarized ultraviolet rays. May be produced to show the orientation. As a result, the alignment state of the polyimide-based polymer can be more stably fixed, and as a result, the alignment state of the liquid crystal compound can be more stably fixed. That is, the azimuth anchoring strength of the photo-alignment film can be improved, and image sticking due to application of AC voltage can be more effectively suppressed.

The at least one monomer is a monomer having a chalcone group which may have a substituent, a monomer having a cinnamate group which may have a substituent, and a monomer having a coumarin group which may have a substituent. It may contain at least one photoreactive monomer selected from the group consisting of:

The at least one monomer may include at least one monomer represented by the following chemical formula (1). As a result, the alignment state of the polyimide-based polymer can be more stably fixed, and as a result, the alignment state of the liquid crystal compound can be more stably fixed. Therefore, the alignment state of the liquid crystal compound can be more stably fixed, and image sticking resulting from application of the AC voltage can be more effectively suppressed.

The at least one monomer represented by the chemical formula (1) may include at least one monomer represented by any one of the following chemical formulas (2-1) to (2-5).

The display mode of the liquid crystal display device may be a fringe field switching (FFS) mode.

Another embodiment of the present invention is a preparatory step of preparing a pair of substrates, at least one surface of the pair of substrates, at least one polymer of polyamic acid and polyimide (polyimide polymer), and at least one monomer A film forming step of forming a photo-alignment film by applying an aligning agent containing (orienting monomer), and irradiating the photo-alignment film with polarized ultraviolet rays to align the at least one polymer and at least the one type And an irradiation step of aligning and polymerizing the monomer, wherein the at least one monomer exhibits orientation by causing at least one of an isomerization reaction and a dimerization reaction by irradiation with polarized ultraviolet rays. The manufacturing method of a display apparatus may be sufficient. The method for manufacturing the liquid crystal display device includes an irradiation step of irradiating the photo-alignment film with polarized ultraviolet rays to align the polyimide polymer and aligning and polymerizing the orientation monomer. The polyimide polymer having a group is controlled in orientation, and the orientation monomer is polymerized in a state in which the orientation is controlled, so that the orientation of the polyimide polymer having a photofunctional group can be fixed. Therefore, since the azimuth anchoring strength of the photo-alignment film can be improved, it is possible to reduce image sticking due to application of an AC voltage.

One of the pair of substrates includes a pixel electrode and a common electrode, and at least one of the pixel electrode and the common electrode includes a linear portion. The photo-alignment film is formed on the surface of the substrate including the pixel electrode and the common electrode. In the irradiation step, the photo-alignment film is polarized so that an angle formed by the polarization axis direction with respect to the linear portion is 83 ° or less. You may irradiate with an ultraviolet-ray. Thereby, it can be easily made 7 ° or more in a plan view of the inclination angle of the linear portion with respect to the initial orientation direction of the liquid crystal compound. For this reason, it is possible to further reduce the burn-in resulting from the AC voltage application.

In the irradiation step, the photo-alignment film may be irradiated with polarized ultraviolet rays so that an angle formed by a polarization axis direction with respect to the linear portion is 77 ° or more. As a result, the inclination angle of the linear portion with respect to the initial alignment direction of the liquid crystal compound can be easily reduced to 13 ° or less in plan view. Therefore, it is possible to suppress a decrease in transmittance and contrast.

Each aspect of the present invention described above may be appropriately combined without departing from the scope of the present invention.

10, 20: Substrate 21: Transparent substrate 22: Planar electrode 23: Insulating film 24: Slit electrode 24s: Slit 25: Pixel electrode 26: Common electrode 27: Linear portion 30: Liquid crystal layer 31: Liquid crystal compound (liquid crystal molecule)
31a: initial orientation orientation 40: sealing material 50: photo-alignment film 51: polyimide polymer having azobenzene group 52: polymer having chalconyl group 53: orientation monomer having chalconyl group 60: polarizing plate 70: backlight 100: liquid crystal Display device α: angle of inclination of the linear portion with respect to the initial orientation of the liquid crystal compound

Claims

A liquid crystal layer containing a liquid crystal material having positive dielectric anisotropy;
A sealing material disposed so as to surround the liquid crystal layer in plan view;
A pair of substrates sandwiching the liquid crystal layer;
A photo-alignment film provided on at least one surface of the pair of substrates,
The photo-alignment film contains at least one of polyamic acid and polyimide, and aligns the liquid crystal compound in the liquid crystal material in a horizontal direction with respect to the substrate surface.
One of the pair of substrates includes a pixel electrode and a common electrode,
At least one of the pixel electrode and the common electrode includes a linear portion,
An inclination angle of the linear portion with respect to an initial alignment direction of the liquid crystal compound is 7 ° or more in a plan view.
The liquid crystal display device according to claim 1, wherein the tilt angle is 13 ° or less.
3. The liquid crystal according to claim 1, wherein the polyamic acid and the polyimide have a structure derived from a diamine having an azobenzene group and a structure derived from a tetracarboxylic dianhydride having a bent molecular structure. Display device.
The tetracarboxylic dianhydride having a bent molecular structure includes at least one tetracarboxylic dianhydride represented by any one of the following chemical formulas (X-1) to (X-28): The liquid crystal display device according to claim 3.
The tetracarboxylic dianhydride having a bent molecular structure is at least one tetracarboxylic dianhydride represented by any one of the chemical formulas (X-6), (X-22), (X-23) or (X-27). 5. The liquid crystal display device according to claim 4, comprising carboxylic dianhydride.
The liquid crystal display device according to claim 1, wherein the polyamic acid and the polyimide have a structure derived from a cyclobutane ring.
7. The liquid crystal display device according to claim 1, wherein the liquid crystal material has a dielectric anisotropy of 1 or more and less than 3.5.
The liquid crystal display device according to any one of claims 1 to 7, wherein the liquid crystal material has a nematic phase-isotropic phase transition point of 95 ° C or higher.
The liquid crystal display device according to any one of claims 1 to 7, wherein the sealing material contains a (meth) acrylic monomer, a radical polymerization initiator, an epoxy monomer, and an epoxy curing material.
The photo-alignment film further contains a polymer obtained by polymerizing at least one monomer,
10. The liquid crystal display device according to claim 1, wherein the at least one monomer exhibits orientation by causing at least one of an isomerization reaction and a dimerization reaction by irradiation with polarized ultraviolet rays. .
The at least one monomer is a monomer having a chalcone group which may have a substituent, a monomer having a cinnamate group which may have a substituent, and a monomer having a coumarin group which may have a substituent. The liquid crystal display device according to claim 10, comprising at least one photoreactive monomer selected from the group consisting of:
The liquid crystal display device according to claim 11, wherein the at least one monomer includes at least one monomer represented by the following chemical formula (1).

(In the formula, P 1 and P 2 are the same or different and each represents an acryloyloxy group, a methacryloyloxy group, an acryloylamino group, a methacryloylamino group, a vinyl group, or a vinyloxy group.
Sp 1 and Sp 2 are the same or different and each represents a linear, branched or cyclic alkylene group or alkyleneoxy group having 1 to 6 carbon atoms, or a direct bond.
At least one hydrogen atom of each phenylene group may be substituted. )
13. The at least one monomer represented by the chemical formula (1) includes at least one monomer represented by any one of the following chemical formulas (2-1) to (2-5). Liquid crystal display device.
The liquid crystal display device according to any one of claims 1 to 13, wherein a display mode of the liquid crystal display device is a fringe field switching (FFS) mode.
A preparation step of preparing a pair of substrates;
A film forming step of forming an optical alignment film by applying an alignment agent containing at least one polymer of polyamic acid and polyimide and at least one monomer on at least one surface of the pair of substrates;
An irradiation step of irradiating the photo-alignment film with polarized ultraviolet rays to align the at least one polymer and align and polymerize the at least one monomer;
The method for producing a liquid crystal display device, wherein the at least one monomer exhibits orientation by causing at least one of an isomerization reaction and a dimerization reaction by irradiation with polarized ultraviolet rays.
One of the pair of substrates includes a pixel electrode and a common electrode,
At least one of the pixel electrode and the common electrode includes a linear portion,
In the film-forming step, the photo-alignment film is formed on the surface of at least the substrate including the pixel electrode and the common electrode among the pair of substrates.
16. The method of manufacturing a liquid crystal display device according to claim 15, wherein, in the irradiating step, the photo-alignment film is irradiated with polarized ultraviolet rays so that an angle formed by a polarization axis direction with respect to the linear portion is 83 ° or less. .
17. The method of manufacturing a liquid crystal display device according to claim 16, wherein, in the irradiating step, the photo-alignment film is irradiated with polarized ultraviolet rays so that an angle formed by a polarization axis direction with respect to the linear portion is 77 ° or more. .
18. The polyamic acid and the polyimide each have a structure derived from a diamine having an azobenzene group and a structure derived from a tetracarboxylic dianhydride having a bent molecular structure. A method for producing a liquid crystal display device according to claim 1.
The method for producing a liquid crystal display device according to claim 15, wherein the polyamic acid and the polyimide have a structure derived from a cyclobutane ring.
The at least one monomer is a monomer having a chalcone group which may have a substituent, a monomer having a cinnamate group which may have a substituent, and a monomer having a coumarin group which may have a substituent. 20. The method for producing a liquid crystal display device according to claim 15, comprising at least one photoreactive monomer selected from the group consisting of: