JP2006308725A - Optical compensating sheet and method for manufacturing the same, polarizing sheet, and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing an optical compensating sheet by which an alignment layer is obtained which is used for applying liquid crystal material onto a support and combines uniform aligning properties with preferred adhesive properties to a liquid crystal layer and to a support, and to provide an optical compensating sheet obtained by the method, a polarizing sheet and a liquid crystal display device that have the optical compensating sheet. <P>SOLUTION: The method for manufacturing an optical compensating sheet 10 includes the steps of: applying an alignment layer solution L1 onto a transparent support 11 and drying the the solution L1 to form a dry film 12 and then rubbing the surface of the dry film 12 to obtain an alignment layer 14; and applying a composition containing a liquid crystal compound onto the surface of the alignment layer 14 and then aligning the liquid crystal compound, and curing the liquid crystal compound, while keeping the alignment, where the alignment layer solution L1 contains a hydrolyzed product C1 of an alkoxysilane compound, a polymer material C2 having a hydroxyl group, and crosslinking agent. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical compensation sheet and a method for manufacturing the same, a polarizing sheet including the optical compensation sheet, and a liquid crystal display device using the polarizing sheet.

  The liquid crystal state is an intermediate state between the crystal and the liquid, and is a state in which the molecular orientation remains even after the three-dimensionality of the center of gravity of the molecule in the crystal state is lost. Since the molecular orientation remains, it has the property of changing the polarization state of light, and is used for optical elements such as liquid crystal cells, optical compensation sheets, and PS separation films of liquid crystal display elements.

  Here, an alignment film is employed as a base layer for promoting the alignment of the liquid crystal molecules. Examples of the alignment method of the alignment film include a method in which an alignment material is obliquely vacuum-deposited and a method by irradiation with polarized ultraviolet rays. For cost and productivity, the alignment film is rubbed in one direction with a cloth having a long bristle (for example) The rubbing method is most widely used.

  In addition, as alignment film materials corresponding to rubbing treatment, polyimide, polyvinyl alcohol, alkoxysilane compound, cellulose, metal complex, polyamide, epoxy acrylate, silanol oligomer, polyacrylonitrile, phenol resin, polyoxazole, cyclized polyisoprene, etc. Proposed.

  By the way, conventional liquid crystal materials have been most studied mainly for application to liquid crystal cells of liquid crystal display elements. Therefore, an alignment film using a rubbing method is a polyimide-based alignment film that is optimal for a liquid crystal cell. In this case, the base substrate to which the alignment film is applied is glass or ITO.

  However, in recent years, an application example in which a liquid crystal material is used for an optical compensation sheet of a liquid crystal display, a liquid crystal display on a flexible base substrate, and the like has been attracting attention. Here, the purpose of the optical compensation sheet is to improve the viewing angle and display performance of the liquid crystal display by changing the retardation (phase difference) of the optical anisotropic layer (liquid crystal layer). In the case of such an application example, it is necessary to change the support (base substrate) from glass or ITO to a flexible plastic.

  In addition, the adhesion of the alignment film in the conventional liquid crystal cell is sufficient if it is strong enough to prevent the alignment film from peeling off from the support by rubbing treatment. In the rework adhesion between the compensation sheet and the polarizing plate, the alignment film needs to have adhesion between both the liquid crystal layer and the support. In addition, for example, when an optical element is used for mobile applications, the performance as an optical element is significantly impaired by peeling at the support-alignment film interface and the alignment film-liquid crystal layer interface due to various physical shocks. .

As described above, it is necessary to develop an alignment film in which a liquid crystal layer is aligned on a plastic-based support and has good adhesion to the support and the liquid crystal layer.
As an alignment film that satisfies the above requirements, a technique for aligning liquid crystal while introducing an organic functional group into a part of polyvinyl alcohol (hereinafter referred to as PVA) to improve adhesion with the liquid crystal has been proposed (for example, patents). Reference 1).

  However, the modified PVA is synthesized by dissolving PVA in a cosolvent of PVA and an organic functional group, introducing a monofunctional organic group and reacting, and gradually dropping the resulting solution into a poor solvent of PVA for recrystallization. I get it. When such modified PVA is used, the productivity of PVA synthesis is poor. Moreover, only functional groups are introduced at a rate of at most 1 to 2% of the PVA chain. Furthermore, the introduction ratio of this significant functional group depends on the PVA species and the functional group species, but PVA is hardly dissolved in a solvent other than water and is not compatible with organic functional groups. There was a problem that the type and amount of the product would be limited.

  Further, since the alkoxysilane compound is generally used to improve the adhesion between the inorganic surface and the organic surface, even when the alkoxysilane compound is used as the alignment film, the adhesion with the liquid crystal layer is expected to be improved. It has been proposed to use an alkoxysilane compound as an alignment film (see, for example, Patent Document 2).

JP 9-152509 A JP 2001-55573 A

  However, even with the above technique, sufficient adhesion between the support and the liquid crystal layer may not be obtained. In some cases, the liquid crystal layer has uneven alignment.

  The present invention has been made in view of the above-described problems in the prior art. In an alignment film for applying a liquid crystal material on a support, uniform alignment and good liquid crystal layer and support are obtained. An object of the present invention is to provide a method for producing an optical compensation sheet that achieves both adhesion and to provide an optical compensation sheet obtained by the production method. Further, a polarizing sheet having the optical compensation sheet and a liquid crystal display device are provided. The purpose is to provide.

  The inventors applied an alkoxysilane compound as an alignment film material that contains a large amount of organic functional groups in the molecule and has excellent productivity, and has uniform alignment and good adhesion to both the liquid crystal layer and the support. As a result, intensive studies were conducted to achieve both of the above and the present invention was achieved.

  The present invention provided to solve the above problems includes a step of applying an alignment film solution on a transparent support and drying to form a dry film, and then rubbing the surface of the dry film to form an alignment film; An optical compensation sheet comprising: applying a composition containing a liquid crystal compound to the surface of the alignment film; and performing an alignment treatment on the liquid crystal compound, and curing the liquid crystal compound while maintaining the alignment to form an optically anisotropic layer. The alignment film solution includes a hydrolyzate of an alkoxysilane compound, a polymer material having a hydroxyl group, and a crosslinking agent (Claim 1). .

  Here, the polymer material having a hydroxyl group is preferably polyvinyl alcohol, glucose, or gelatin. Moreover, it is preferable that the weight ratio of the alkoxysilane compound to the polymer material having a hydroxyl group is 0.33 or more and 3 or less.

  Moreover, before applying the composition containing a liquid crystal compound on the surface of the alignment film, the alignment film is preferably washed with a solvent of the hydrolyzate of the alkoxysilane compound.

The functional group of the alkoxysilane compound is preferably any one of an acryloxy group, a methacryloxy group, a mercapto group, an epoxy group, and an amino group.
The transparent support preferably has a hydroxyl group on the surface, and is particularly preferably made of saponified triacetyl cellulose.

The present invention provided to solve the above problems is obtained by the method for producing an optical compensation sheet according to any one of claims 1 to 7, comprising a transparent support, and an alignment film on the transparent support. And an optically anisotropic layer made of a liquid crystal compound and aligned and fixed by the alignment film (claim 8).
Here, the transparent support is preferably a flexible polymer film.

  The present invention provided to solve the above problems is a polarizing sheet in which a protective film is provided on both surfaces of a polarizing element sheet, wherein one of the protective films is the optical compensation sheet according to claim 8 or 9. A polarizing sheet characterized in that (Claim 10).

  The present invention provided to solve the above-mentioned problems is a polarizing sheet comprising a polarizing plate and the optical compensation sheet according to claim 8 or 9 bonded together (invention 11).

  The present invention provided to solve the above-described problems is a liquid crystal display device comprising the polarizing sheet according to claim 10 or 11 on at least one surface of a liquid crystal panel (claim 12).

According to the present invention, it is possible to form an alignment film made of an alkoxysilane compound having good adhesion to a support that is a base substrate without impairing the alignment and adhesion of an optically anisotropic layer made of a liquid crystal material. In addition, it is possible to provide an optical compensation sheet that achieves both uniform alignment and good adhesion between the liquid crystal layer and the support.
Furthermore, a polarizing sheet on which the optical compensation sheet is mounted, and a liquid crystal display device can be provided.

  FIG. 1 shows the steps of the action mechanism of an alkoxysilane compound from the preparation of a conventional alignment film solution containing an alkoxysilane compound to the formation of a dry film using the alignment film solution. Shown from the perspective. Here, the transparent support 11 is a base substrate having an OH group on its surface, such as saponified triacetyl cellulose (hereinafter referred to as TAC).

First, an alignment film solution L9 is prepared by hydrolyzing an alkoxysilane compound (FIG. 1 (a)).
Next, the alignment film solution L9 is applied on the transparent support 11 (FIG. 1B). Thereby, the OH group of the transparent support 11 and the OH group of the hydrolyzate of the alkoxysilane compound are in a hydrogen bond state (FIG. 1C).

  Next, the alignment film solution applied on the transparent support 11 is dried to form a dry film 92 (FIG. 1D). Here, adhesion between the hydrolyzate of the alkoxysilane compound and the transparent support 11 is achieved by dehydration of water from the portion where the OH group of the transparent support 11 and the OH group of the hydrolyzate of the alkoxysilane compound are hydrogen bonded. The dry film 92 is formed in a state where the property is ensured.

  Thereafter, in the conventional manufacturing method, the dry film 92 is rubbed to form an alignment film, and then a liquid crystal layer is formed on the alignment film. In this case, the transparent support 11 and the liquid crystal layer are formed. Adhesion with was not sufficient. The inventors investigated the cause in detail and found that there was a problem with the state of the dry film 92.

  That is, as shown in FIG. 2, the dry film 92 is formed on the hydrolyzate (A) of the alkoxysilane compound and the hydrolyzate (A) of the alkoxysilane compound bonded to the transparent support 11 as described above. It comprises a hydrolyzate (B) of an unreacted alkoxysilane compound not bonded to the OH group of the transparent support 11, and a liquid crystal layer is formed on the alignment film obtained by rubbing the dry film 92. When formed, delamination occurred between the hydrolyzate (A) of the alkoxysilane compound and the hydrolyzate (B) of the alkoxysilane compound, resulting in poor adhesion.

  Therefore, the inventors have intensively studied to improve the adhesion deterioration due to the hydrolyzate (B) of the unreacted alkoxysilane compound, and have completed the present invention.

Below, the manufacturing method of the optical compensation sheet which concerns on this invention is demonstrated.
FIG. 3 shows the procedure from the preparation of the alignment film solution to the formation of a dry film using the alignment film solution in the method for producing an optical compensation sheet of the present invention. Again, the transparent support 11 is a base substrate having OH groups on the surface, such as saponified triacetyl cellulose (hereinafter referred to as TAC).

  First, an alignment film solution L1 containing a hydrolyzate C1 of an alkoxysilane compound, a polymer material C2 having a hydroxyl group, and a crosslinking agent is prepared (FIG. 3A).

  The alkoxysilane compound is a silane compound having 2 or 3, preferably 3 alkoxy groups, for example, a methoxy group having an affinity for an inorganic surface or an ethoxy group, and is commercially available as a silane coupling agent. Can be used. Here, the silane coupling agent is a compound composed of an organic substance and silicon, and includes two kinds of substituents having different reactivity in a molecule, that is, a functional group having affinity or reactivity for an inorganic material. I have it. The structural formula of the alkoxysilane compound is shown below.

In the above structural formula, the R ₁ group obtains adhesion to the optically anisotropic layer made of liquid crystal by polymerizing with liquid crystal, and may be any functional group as long as it can copolymerize with liquid crystal. For example, any of acryloxy group, methacryloxy group, mercapto group, epoxy group, and amino group may be used. Further, at least one of the R ₂ groups is substituted by hydrolysis, and becomes an OH group for ensuring adhesion with the transparent support 11.

  The hydrolyzate C1 of the alkoxysilane compound is, for example, charged into 25 to 100 parts by weight of acidic water containing 0.2 to 2.0 wt% of a weak acid such as acetic acid, by adding 1 part by weight of the alkoxysilane compound, and 20 degrees to 60 degrees. It is obtained by hydrolysis under conditions of 1 hour to 24 hours with stirring in a moderate atmosphere.

  The polymer material C2 having a hydroxyl group is preferably polyvinyl alcohol, glucose, or gelatin. Further, it is more preferably a long chain polymer material in order to promote the orientation of the liquid crystal compound layer.

  Further, the polymer material C2 having a hydroxyl group in the alignment film solution L1 is preferably added so that the weight ratio with respect to the alkoxysilane compound before hydrolysis is 0.33 or more and 3 or less. Thereby, it is possible to improve the adhesion deterioration due to the hydrolyzate (B) of the unreacted alkoxysilane compound without impairing the orientation and adhesion of the optically anisotropic layer made of the liquid crystal compound.

  The crosslinking agent promotes bonding between the OH groups of the transparent support 11 and the hydrolyzate C1 of the alkoxysilane compound, and between the OH groups of the hydrolyzate C1 of the alkoxysilane compound and the polymer material C2 having a hydroxyl group. The crosslinking agent is added to promote bonding, and may be either a thermal crosslinking agent or a UV curable crosslinking agent. For example, an acrylic crosslinking agent, glutaraldehyde, etc. are mentioned. Moreover, it is preferable that the addition amount is 0.04-0.40 as a weight ratio with a silane compound.

  Next, the alignment film solution L1 is applied on the transparent support 11 (FIG. 2B). This can be carried out by various methods capable of uniformly attaching the alignment film solution L1 to the surface of the transparent support 11. For example, after immersing the transparent support 11 in the alignment film solution L1, the transparent support 11 may be pulled out of the solution, or the alignment film solution L1 may be sprayed on the surface of the transparent support 11.

  Here, the transparent support 11 preferably has a hydroxyl group (OH group) that transmits light and has good adhesion to the hydrolyzate C1 of the alkoxysilane compound. In particular, a material having a light transmittance of 80% or more is preferable, and triacetylcellulose, polycarbonate, polyarylate, polysulfone, polyethersulfone, polyethylene terephthalate, ARTON (Nippon Rubber Synthetic), Zeonex (manufactured by Nippon Zeon), etc. are used. It can be obtained by appropriately surface-treating such a material. As the surface treatment, saponification treatment, corona treatment, excimer UV treatment, plasma treatment or the like may be performed. The transparent support 11 is preferably a flexible polymer film.

  As a result, the OH group of the transparent support 11 and the OH group of the hydrolyzate C1 of the alkoxysilane compound are hydrogen bonded (FIG. 2C).

The adhesion amount of the alignment film solution L1 to the transparent support 11 is preferably 0.01 to 1.0 g / m ² , more preferably 0.05 to 0.2 g / m in terms of an alkoxysilane compound before hydrolysis. ² .

Next, the alignment film solution L1 applied on the transparent support 11 is dried to form a dry film 12 (FIG. 2D).
Thereby, the hydrolyzate C1 of the alkoxysilane compound, the transparent support 11 and the hydrolyzate of the alkoxysilane compound from the portion where the OH group of the transparent support 11 and the OH group of the hydrolyzate C1 of the alkoxysilane compound are hydrogen bonded. Is ensured.

  Simultaneously, hydrolyzate C1 of alkoxysilane compound (hydrolyzate of alkoxysilane compound (A) and hydrolyzate of unreacted alkoxysilane compound (B) bonded to transparent support 11) and polymer having a hydroxyl group A binding reaction by dehydration of water occurs between the OH groups of the material C2. Thereby, the hydrolyzate (B) of the unreacted alkoxysilane compound is not released in the dry film 12, and the liquid crystal compound layer 15 (optical anisotropic layer 16) described later and the transparent support 11 Adhesion as the alignment film 14 interposed therebetween can be improved.

In FIG. 4, the manufacturing process figure of the optical compensation sheet after dry film 12 formation is shown.
(S11) As described above, the alignment film solution L1 is applied on the transparent support 11 and dried to form the dry film 12 (FIG. 4A).

(S12) Next, the surface of the dry film 12 is rubbed to form the alignment film 14 (FIG. 4B).
As the rubbing treatment method, a known rubbing treatment method can be employed. For example, a rubbing cloth made of a material such as rayon, cotton, polyamide or the like is wound around a metal roll, and the roll is rotated while being in contact with the dry film 12. And a method of moving, and a method of moving the dry film 12 side while the roll is fixed.

  Here, the alignment film 14 is preferably washed with a solvent of a hydrolyzate of an alkoxysilane compound. Even if the hydrolyzate (B) of the unreacted alkoxysilane compound remains in the dry film 12, it is removed by this treatment, and the adhesion between the liquid crystal compound layer and the transparent support 11 mounted in the subsequent treatment. Can be further improved. Furthermore, dust such as alignment film cloth generated on the surface of the alignment film in the rubbing process can be removed by washing.

The solvent for the hydrolyzate of the alkoxysilane compound may be anything as long as it can dissolve the unreacted alkoxysilane compound hydrolyzate (B). For example, water, ethers, alcohols, ketones, glycols, acetaldehyde, toluene, acetone, xylene and the like can be mentioned. Particularly, the alkoxysilane compound hydrolyzate (B) has a high solubility, ethers and alcohols. , Ketones, glycols, acetaldehyde, toluene, acetone, and xylene are preferable. Further, these solvents may be combined, or a solution containing a certain ratio may be used.
In addition, the cleaning method using the solvent may be any method such as a method of spraying and cleaning an object and a method of immersing and cleaning an object in a tank filled with the solvent.

(S13) A liquid crystal compound-containing composition is applied on the alignment film 14 to form the liquid crystal compound layer 15 (FIG. 4C). Specifically, when the polymerizable liquid crystal compound-containing composition is applied onto the alignment film 14 by a known application method such as a spin coating method, a roll coating method, a printing method, a dip-up method, or a curtain coating method (die coating method). Good. After application, it is usually dried by a conventional method. The drying conditions are not particularly limited, and it is only necessary to select conditions that can remove the organic solvent without causing the coating film to flow or flow down. For example, the organic solvent can be removed using air drying at room temperature, drying on a hot plate, drying in a drying furnace, blowing hot air or hot air, and the like. As a result, the liquid crystal compound layer 15 is in a solid crystal state while maintaining the liquid crystal phase structure at room temperature.

  As the polymerizable liquid crystal compound used in the polymerizable liquid crystal compound-containing composition, a polymerizable group, for example, a (meth) acryloyl group (a generic name for an acryloyl group and a methacryloyl group), a vinyl group, an allyl group, an epoxy group, a phthalimide group, A known discotic polymerizable liquid crystal compound having a cinnamoyl group or the like and a rod-like smectic polymerizable liquid crystal compound can be used. For example, a biphenyl derivative, a phenylbenzoate derivative, a stilbene derivative, a triphenylene derivative, a torquesen derivative In the molecular structure, such as containing a group capable of imparting homeotropic orientation (for example, an aromatic group having a bulky substituent at the terminal, an aromatic group having a long-chain alkyl group, an aromatic group having a fluorine atom) Photocurable polymerizable liquid crystal compound) can be used.

  In the polymerizable liquid crystal compound-containing composition used in the present invention, the blending amount is usually 40% by weight or less, preferably 30% by weight or less, more preferably 20% by weight or less, as long as the effects of the present invention are not impaired. A non-liquid crystalline polymerizable compound copolymerizable with the polymerizable liquid crystal compound can be blended. Examples of such a polymerizable compound include a polyester (meth) acrylate obtained by reacting a (meth) acrylic acid with a polyester prepolymer of a polyhydric alcohol and a monobasic acid or a polybasic acid; a polyol group and two Polyurethane (meth) acrylate obtained by reacting a compound having an isocyanate group, and then reacting with (meth) acrylic acid; bisphenyl A type epoxy resin, bisphenyl F type epoxy resin, novolak type epoxy resin, polycarboxylic acid By reacting an epoxy resin such as acid polyglycidyl ester, polyol polyglycidyl ether, fatty acid or alicyclic epoxy resin, amine epoxy resin, triphenolmethane type epoxy resin, dihydroxybenzene type epoxy resin, and (meth) acrylic acid. The resulting epoxy (medium ) Photopolymerizable compound and compositions, such as acrylates, also include a photopolymerizable compound having an acrylic group or a methacrylic group.

  Moreover, a photoinitiator can be suitably added to the polymerizable liquid crystal compound-containing composition used in the present invention, if necessary. The photoinitiator is not particularly limited, and for example, benzyl (also known as bibenzoyl), benzoyl ether, benzoin isobutyl ether, benzoin isopropyl ether, benzophenone, benzoylbenzoic acid, methyl benzoylbenzoate, 4-benzoyl- 4'-methyldiphenyl sulfide, benzylmethyl ketal, dimethylaminomethylbenzoate, 2-n-butoxyethyl-4-dimethylaminobenzoate, isoamyl p-dimethylaminobenzoate, 3,3'-dimethyl-4-methoxybenzophenone, Tyrobenzoyl formate, 2-methyl-1- (4- (methylthio) phenyl) -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl)- Butan-1-one, 1- (4-dodecylphenyl) -2-hydroxy-2-methylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropane-1- ON, 1- (4-isopropylphenyl) -2-hydroxy-2-mailpropan-1-one, 2-chlorothioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, 2,4-dimethylthioxanthone, Examples include isopropylthioxanthone and 1-chloro-4-pyropoxythioxanthone.

  The addition amount of the photoreaction initiator is usually 0.01 to 20 parts by weight, preferably 0.1 to 10 parts by weight, more preferably 0.5 to 5 parts by weight with respect to 100 parts by weight of the polymerizable liquid crystal compound. .

  Moreover, you may add a sensitizer to the polymeric liquid crystal compound containing composition in the range which does not impair the effect of this invention.

Moreover, an organic solvent can be mix | blended with a polymeric liquid crystal compound containing composition as needed. By using the organic solvent, the coating film of the polymerizable liquid crystal compound-containing composition can be easily formed.
Examples of such organic solvents include hydrocarbons such as benzene, toluene, xylene, n-butylbenzene, diethylbenzene, and tetralin, ethers such as methoxybenzene, 1,2-dimethoxybenzene, and diethylene glycol dimethyl ether, acetone, methyl ethyl ketone, Ketones such as methyl isobutyl ketone, cyclohexanone, 2,4-pentanedione, ethyl acetate, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, esters such as γ-butyrolactone, 2-pyrrolidone Amide solvents such as N-methyl-2-pyrrolidone, dimethylformaldehyde, dimethylacetamide, chloroform, dichloromethane, Halogen solvents such as carbon chloride, dichloroethane, tetrachloroethane, trichloroethylene, tetrachloroethylene, chlorobenzene, orthodichlorobenzene, t-butyl alcohol, diacetone alcohol, glycerin, monoacetone, ethylene glycol, triethylene glycol, hexylene glycol, ethylene glycol monomethyl Examples include alcohols such as ether, ethylene cellosolve and butyl cellosolve, phenols such as phenol and parachlorophenol, and the like, and are selected in consideration of the solvent resistance of the transparent support 11.

  The amount of the organic solvent used in the polymerizable liquid crystal compound-containing composition varies depending on the solubility of the polymerizable liquid crystal compound and the thickness of the liquid crystal compound layer 15, but is usually 1 to 60% by weight, preferably 3 to 40% by weight. is there.

In addition, a surfactant or the like may be appropriately added to the polymerizable liquid crystal compound-containing composition as long as the effects of the present invention are not impaired in order to improve the coating property.
Surfactants include, for example, cationic surfactants such as imidazoline, quaternary ammonium salts, alkylamine oxides, polyamine derivatives, polyoxyethylene-polyoxypropylene condensates, primary or secondary alcohol ethoxylates. , Alkylphenol ethoxylates, polyethylene glycol and its esters, sodium lauryl sulfate, ammonium lauryl sulfate, amines of lauryl sulfate, alkyl-substituted aromatic sulfonates, alkyl phosphates, aliphatic or aromatic sulfonate formalin condensates, etc. Surfactants, amphoteric surfactants such as laurylamidopropylbetaine, ralylaminoacetic acid betaine, non-ionic surfactants such as polyethylene glycol fatty acid esters, polyoxyethylene alkylamine, etc. , Perfluoroalkyl sulfonate, perfluoroalkyl carboxylsan salt, perfluoroalkyl ethylene oxide adduct, perfluoroalkyl trimethyl ammonium salt, perfluoroalkyl group and hydrophilic group-containing oligomer, perfluoroalkyl group and lipophilic group-containing oligomer And fluorine-based surfactants such as perfluoroalkyl group-containing urethane.

  The amount of the surfactant added varies depending on the type of the surfactant, the composition ratio of the constituent components of the polymerizable liquid crystal compound-containing composition, the type of the organic solvent, the type of the transparent support 11, and the like. It is usually in the range of 10 ppm to 10%, preferably 100 ppm to 5%, more preferably 0.1% to 1% with respect to parts by weight.

(S14) The liquid crystal compound layer 15 is subjected to alignment treatment and curing treatment to form the optically anisotropic layer 16 (FIG. 4D).

  Here, a nematic alignment process generally performed as the alignment process will be described. Examples of the nematic alignment treatment include a method in which the liquid crystal compound layer 15 is heated. Specifically, the liquid crystal compound layer 15 is heated to a temperature at which the liquid crystal compound exhibits a nematic liquid crystal phase to develop nematic alignment, and the liquid crystal compound is heated to a temperature higher than the temperature range at which the liquid crystal compound exhibits a nematic liquid crystal phase. Then, the compound is brought into an isotropic liquid state, and then the temperature of the liquid crystal compound layer 15 is lowered to a temperature range exhibiting a nematic liquid crystal phase, or to a high temperature range within a temperature range where the liquid crystal compound exhibits a nematic liquid crystal phase. The nematic alignment in the liquid crystal compound layer 15 is generally completed by heating, and then nematic alignment may be performed by a method of improving the order of alignment by lowering the temperature. The actual heat treatment temperature is usually 40 to 220 ° C., and the heat treatment time is usually 5 seconds to 2 hours.

  Depending on the composition of the polymerizable liquid crystal compound-containing composition, nematic alignment may be completed thermotropically or lyotropically when the above-mentioned coating film is dried. In such a case, the dried coating film may be subjected to the curing treatment described below without going through the above-described heating treatment, but is heated for the purpose of making the orientation of the liquid crystal molecules in the coating film more uniform. It is preferable to carry out the treatment.

  The curing treatment can be performed by irradiating the alignment-treated liquid crystal compound layer 15 with electromagnetic waves. The wavelength of the electromagnetic wave used for the curing treatment is not particularly limited, and can be appropriately selected from electron beams, ultraviolet rays, visible rays, infrared rays (heat rays) and the like. Moreover, what is necessary is just to determine suitably irradiation energy, temperature at the time of irradiation, irradiation atmosphere, irradiation time, etc. according to the compounding component etc. of a polymerizable liquid crystal compound containing composition.

  Through the above steps, the optical compensation sheet 10 includes the transparent support 11, the alignment film 14 on the transparent support 11, and the optical anisotropic layer 16 made of a liquid crystal compound and aligned and fixed by the alignment film 14. Is completed.

  The optical compensation sheet obtained by the method for producing an optical compensation sheet of the present invention can be used in various optical fields. For example, it can be used as a viewing angle compensation sheet or a retardation sheet of a liquid crystal display device. Further, these optical compensation sheets may be combined with a polarizing plate used in the liquid crystal display device to form a polarizing sheet.

FIG. 5 shows a configuration example of a polarizing sheet using the optical compensation sheet 10 of the present invention.
The polarizing sheet is usually formed by providing a protective film on both surfaces of the polarizing element sheet. However, the polarizing sheet 20 of the present invention has the function of the protective film on one surface of the polarizing element sheet 21 as described above. The compensation sheet 10 is formed, and the protective film 22 is formed on the other surface.

  Here, the polarizing element sheet | seat 21 may be generally used as a polarizing element which comprises the polarizing plate for liquid crystals, for example, consists of a stretched and dyed polyvinyl alcohol (PVA). The protective film 22 may also be one generally used as a protective film constituting a liquid crystal polarizing plate, and is made of, for example, TAC.

FIG. 6 shows another configuration example of a polarizing sheet using the optical compensation sheet 10 of the present invention.
In the polarizing sheet 30 of the present invention, a conventionally known polarizing element sheet 31, a polarizing plate in which protective films are provided on both surfaces of the polarizing element sheet 31, and the optical compensation sheet 10 include an adhesive layer or an adhesive layer 33. It is configured to be pasted through.

  By providing the polarizing sheets 20 and 30 of the present invention on at least one surface of a known liquid crystal panel, for example, a liquid crystal display device with improved viewing angle or high contrast can be configured.

FIG. 7 shows a configuration example of the liquid crystal display device of the present invention.
In the liquid crystal display device 100, the polarizing sheet 20 of the present invention is provided on one surface of a known liquid crystal panel 101 so that the optical compensation sheet 10 is in contact with the liquid crystal panel 101, and the other surface of the liquid crystal panel 101 is known. The polarizing plate 102 is provided.

FIG. 8 shows another configuration example of the liquid crystal display device of the present invention.
In the liquid crystal display device 200, the polarizing sheet 30 of the present invention is provided on one surface of a known liquid crystal panel 201 so that the optical compensation sheet 10 is in contact with the liquid crystal panel 201, and the other surface of the liquid crystal panel 201 is known. The polarizing plate 202 is provided.

  In these liquid crystal display devices 100 and 200, a known backlight is provided outside the polarizing plates 102 and 202. Further, a known hard coat layer may be provided outside the polarizing sheets 20 and 30.

Hereinafter, the present invention will be specifically described by way of examples.
Example 1
The optical compensation sheet of the present invention was produced under the following conditions.
(Preparation of alignment film solution)
As the alkoxysilane compound, KBE-5103 manufactured by Shin-Etsu Silicone Co., Ltd. was used, mixed in a weight ratio of methanol: 1% acetic acid aqueous solution: KBM-5103 = 78: 2: 2, stirred at 60 ° C. for 1.5 hours, and silane compound 2 % Solution was prepared. Here, the structure of the alkoxysilane compound (KBM-5103) is a _{(CH 3 O) 3 -Si-} C 3 H 6 -O-CO-C = C.
Next, this silane compound 2% solution, PVA 2% aqueous solution (Kuraray MP-203) and 12.5% glutaraldehyde aqueous solution were mixed at a weight ratio of 5: 5: 1 to obtain an alignment film solution.

(S21) Saponified TAC was used as the transparent support 11, and the alignment film solution was applied onto the transparent support 11 by spin coating at 1500 rpm so that the final film thickness was 1 μm, and then 120 ° C., 30 minutes. The dried film 12 was formed.
(S22) The surface of the dry film 12 was rubbed to form an alignment film 14.
(S23) The liquid crystal compound layer 15 was formed by applying an acrylate liquid crystal compound-containing composition containing a polymerization initiator on the alignment film 14 so that the final film thickness was 2 μm.
(S24) Finally, the liquid crystal compound layer 15 was heated to the liquid crystal phase temperature to align the liquid crystal, and then UV-irradiated by UV irradiation to form an optically anisotropic layer 16 made of an acrylate liquid crystalline polymer. Thus, a sample of the optical compensation sheet 10 having the optical anisotropic layer 16 that causes the phase difference was completed.

About the said preparation sample, orientation evaluation and adhesiveness evaluation were performed.
The orientation evaluation was calculated as a ratio when the retardation (retardation) when polyimide was used as the alignment film was 100.
Moreover, adhesive evaluation was performed according to JISK5400. That is, a 10 mm square region of the optical anisotropic layer 16 is cut with a cutter at intervals of 1 mm in length and width and cut into 100 sections, and a Nichiban adhesive tape is attached to the region and then peeled off. It was evaluated how many 100 areas that were cut off were peeled off. Here, the case of the best result in which even one of the 100 areas is not peeled is expressed as 100/100.

(Example 2)
In Example 1, the silane compound 2% solution, the PVA 2% aqueous solution and the 12.5% glutaraldehyde aqueous solution were mixed at a weight ratio of 7.5: 2.5: 1 to obtain an alignment film solution. An optical compensation sheet 10 was produced under the same conditions as in Example 1.

(Example 3)
In Example 1, the silane compound 2% solution, the PVA 2% aqueous solution, and the 12.5% glutaraldehyde aqueous solution were mixed at a weight ratio of 2.5: 7.5: 1 to obtain an alignment film solution. An optical compensation sheet 10 was produced under the same conditions as in Example 1.

Example 4
In Example 1, a solution in which the silane compound 2% solution, the PVA 2% aqueous solution, and the UV curable crosslinking agent (diacrylate M215 manufactured by Shin-Nakamura) 2% isopropyl alcohol solution were mixed at a weight ratio of 33: 33: 1. Using a mixture of a small amount of reaction initiator as an alignment film solution, the dried film 12 in step S21 was irradiated with about 1 J of ultraviolet light to cure the UV curable crosslinking agent, and the other conditions were the same as in Example 1. A compensation sheet 10 was produced.

(Example 5)
In Example 1, KBM-1403 manufactured by Shin-Etsu Silicone Co., Ltd. was used as the alkoxysilane compound, and the optical compensation sheet 10 was produced under the same conditions as in Example 1. Note that the structure of the alkoxysilane compound (KBM-1403) is (CH ₃ O) ₃ —Si— (C ₆ H ₆ ) —C═C.

(Comparative Example 1)
Using saponified TAC as the transparent support 11, an alignment film made of polyimide is formed on the transparent support 11, and the processing of steps S23 and S24 in Example 1 is performed on the alignment film to produce an optical compensation sheet. did.

(Comparative Example 2)
In Example 1, the 2% solution of the silane compound and the 12.5% glutaraldehyde aqueous solution were mixed at a weight ratio of 5: 1 to obtain an alignment film solution. Otherwise, the optical compensation sheet was prepared under the same conditions as in Example 1. Produced.

(Comparative Example 3)
In Example 1, the PVA 2% aqueous solution and 12.5% glutaraldehyde aqueous solution were mixed at a weight ratio of 5: 1 to obtain an alignment film solution, and an optical compensation sheet was prepared under the same conditions as in Example 1 except that. .

(Comparative Example 4)
In Example 1, the 2% solution of the silane compound and the 2% aqueous solution of PVA were mixed at a weight ratio of 1: 1 to obtain an alignment film solution. Otherwise, an optical compensation sheet was produced under the same conditions as in Example 1.

The above evaluation results are shown in Table 1.
In the examples, peeling due to the unreacted residual silane compound could be solved.
Moreover, when combined with the results of Comparative Examples 2 to 4, it was found that good adhesion cannot be obtained unless a hydrolyzate of an alkoxysilane compound, a polymer material having an OH group, and a crosslinking agent are used in combination. . In Comparative Example 2, the adhesion between the alignment film and the transparent support was poor, and in Comparative Example 3, the adhesion between the alignment film and the liquid crystal compound layer was poor.
Moreover, from the results of Examples, it was found that the mixing ratio between the alkoxysilane compound and the polymer material having an OH group is preferably in the range of 0.33 to 3.
Further, as in Examples 1 and 4, it was found that the crosslinking agent may be either a thermal crosslinking agent or a UV curable crosslinking agent.
Moreover, it turned out that a silane compound may not be a specific thing like Examples 1 and 5, and should just be a material with sufficient adhesiveness with a liquid crystal. Here, those having a highly polar molecular structure such as a double bond or a benzene ring are particularly preferred.

It is a figure which shows a procedure until a dry film | membrane is formed from a viewpoint of the action mechanism of the conventional alkoxysilane compound. It is a conceptual diagram which shows the problem of the conventional alignment film. It is a figure which shows a procedure until a dry film | membrane is formed from a viewpoint of the action mechanism of the alkoxysilane compound of this invention. It is a manufacturing-process figure of the optical compensation sheet which concerns on this invention. It is the structural example 1 of the polarizing sheet which concerns on this invention. It is the structural example 2 of the polarizing sheet which concerns on this invention. 1 is a configuration example 1 of a liquid crystal display device according to the present invention. It is the structural example 2 of the liquid crystal display device which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Optical compensation sheet, 11 ... Transparent support, 12, 92 ... Dry film, 14 ... Alignment film, 15 ... Liquid crystal compound layer, 16 ... Optical anisotropic layer, 20 , 30... Polarizing sheet, 21, 31... Polarizing element sheet, 22, 32... Protective film, 33... Adhesive layer (adhesive layer), 100, 200. 201 ... Liquid crystal panel, 102, 202 ... Polarizing plate

Claims (12)

Applying an alignment film solution on a transparent support and drying to form a dry film, then rubbing the surface of the dry film to form an alignment film, and applying a composition containing a liquid crystal compound to the alignment film surface The liquid crystal compound is then subjected to an alignment treatment, and the liquid crystal compound is cured while maintaining the alignment to form an optically anisotropic layer.
The method for producing an optical compensation sheet, wherein the alignment film solution includes a hydrolyzate of an alkoxysilane compound, a polymer material having a hydroxyl group, and a crosslinking agent.   2. The method for producing an optical compensation sheet according to claim 1, wherein the polymer material having a hydroxyl group is any one of polyvinyl alcohol, glucose, and gelatin.   2. The method for producing an optical compensation sheet according to claim 1, wherein a weight ratio of the alkoxysilane compound to the polymer material having a hydroxyl group is 0.33 or more and 3 or less.   2. The optical compensation sheet according to claim 1, wherein the alignment film is washed with a hydrolyzate solvent of the alkoxysilane compound before applying a composition containing a liquid crystal compound on the surface of the alignment film. Production method.   2. The method for producing an optical compensation sheet according to claim 1, wherein the functional group of the alkoxysilane compound is any one of an acryloxy group, a methacryloxy group, a mercapto group, an epoxy group, and an amino group.   The method for producing an optical compensation sheet according to claim 1, wherein the transparent support has a hydroxyl group on the surface.   The method for producing an optical compensation sheet according to claim 1, wherein the transparent support is made of saponified triacetylcellulose.   It is obtained by the method for producing an optical compensation sheet according to any one of claims 1 to 7, and comprises a transparent support, an alignment film on the transparent support, and a liquid crystal compound, which is aligned and fixed by the alignment film. An optical compensation sheet comprising: an optically anisotropic layer formed into an optically anisotropic layer.   The optical compensation sheet according to claim 8, wherein the transparent support is a flexible polymer film. In a polarizing sheet in which protective films are provided on both sides of the polarizing element sheet,
One of the said protective films is the optical compensation sheet of Claim 8 or 9, The polarizing sheet characterized by the above-mentioned.   A polarizing sheet comprising a polarizing plate and the optical compensation sheet according to claim 8 or 9 bonded together.   A liquid crystal display device comprising the polarizing sheet according to claim 10 or 11 on at least one surface of a liquid crystal panel.

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