JP2009067861A - Polyvinyl alcohol film, optical film, polarizing plate, and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyvinyl alcohol film and an optical film excellent in durability and useful for members in a liquid crystal display device and the like. <P>SOLUTION: The polyvinyl alcohol film is formed of a composition containing polyvinyl alcohol having a reactive group including active hydrogen in its molecule and a cross-linking agent. The optical film has an optical anisotropic layer, which is formed of a liquid crystal composition, on the polyvinyl alcohol film. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a polyvinyl alcohol film useful as an alignment film for liquid crystalline molecules, and an optical film, a polarizing plate, and a liquid crystal display device using the same.

  Various optical films produced by utilizing the orientation of a liquid crystal composition have been proposed as optical compensation films used for liquid crystal display devices and the like. This optical film is produced, for example, by applying a polymerizable liquid crystal composition to the alignment film surface to obtain a desired alignment state, and then fixing the state by polymerization. However, some of these optical films have insufficient adhesion between the optically anisotropic layer and the alignment film or cohesive force of the alignment film, and when used for a long time, the liquid crystal layer may peel off. There is a need for improved durability.

For example, in Patent Document 1, as an optical compensation sheet having excellent durability, an optical compensation sheet comprising a transparent support, an alignment film made of a polymer, and an optical anisotropic layer made of a liquid crystal compound in this order. Has proposed an optical compensation sheet characterized in that the polymer of the alignment film and the liquid crystal compound of the optically anisotropic layer are chemically bonded via the interface of these layers.
However, further improvements in durability are required for optical films and the like used in liquid crystal display devices.

In Patent Document 2, after applying a coating liquid containing a liquid crystalline molecule having an ethylenically unsaturated group and a photopolymerization initiator on an alignment film prepared by mixing a high saponification degree polyvinyl alcohol and an alkyl-modified polyvinyl alcohol, An optical film produced by aligning liquid crystal molecules and then immobilizing them by ultraviolet irradiation is disclosed.
However, this alignment film is premised on peeling of the liquid crystal layer. Therefore, the adhesion between the alignment film and the liquid crystal layer is weak, and it is unsuitable for use as it is as a polarizing plate protective film without peeling off the liquid crystal layer.
JP 09-152509 A JP 2006-243025 A

  An object of the present invention is to provide a polyvinyl alcohol film, an optical film, a polarizing plate, and a liquid crystal display device using the same, which are useful as members of a liquid crystal display device and the like, and have excellent durability.

Means for solving the above problems are as follows.
[1] A film comprising a composition containing polyvinyl alcohol having a reactive group having active hydrogen in the molecule and a crosslinking agent.
[2] The film according to [1], which is a liquid crystal alignment film.
[3] The film according to [1] or [2], wherein the polyvinyl alcohol having a reactive group having active hydrogen in the molecule is acetoacetyl-modified polyvinyl alcohol.
[4] The film according to any one of [1] to [3], wherein the crosslinking agent is glutaraldehyde.
[5] The film according to any one of [1] to [4], wherein the average saponification degree of the polyvinyl alcohol having a reactive group having active hydrogen in the molecule is 95 mol% or more.
[6] The film according to any one of [1] to [5], wherein the composition further contains at least one kind of polyvinyl alcohol having a polymerizable group.
[7] The membrane according to [6], wherein the average saponification degree of the polyvinyl alcohol having a polymerizable group is 70 to 90 mol%.
[8] The film according to any one of [1] to [7], containing polyvinyl alcohol as a main component.
[9] An optical film having a polymer film and the film of any one of [1] to [8] on the polymer film.
[10] The optical film of [9], comprising an optically anisotropic layer formed from a liquid crystal composition on the film.
[11] The optically anisotropic layer is a layer formed by aligning a polymerizable liquid crystal composition containing a liquid crystal compound having a polymerizable group on the film and fixing it in that state. [10] The optical film of [10].
[12] The optical film according to [11], wherein the film contains at least one polymerizable compound having a polymerizable group of the same type as the polymerizable group of the liquid crystal compound.
[13] The optical film of [12], wherein the polymerizable compound is a polyvinyl alcohol.
[14] The optical film of any one of [11] to [13], wherein the polymerizable group of the polymerizable liquid crystal compound is any one of an unsaturated polymerizable group, an epoxy group, and an aziridinyl group.
[15] The optical film of [14], wherein the polymerizable group of the polymerizable liquid crystal compound is an ethylenically unsaturated polymerizable group.
[16] The optical film according to any one of [9] to [15], wherein the polymer film is a film mainly composed of cellulose acylate.
[17] A polarizing plate having a polarizing film and the optical film of any one of [1] to [16].
[18] The polarizing plate according to [17], wherein the optical film is a protective film for the polarizing film.
[19] A liquid crystal display device comprising the polarizing plate of [17] or [18].

  According to the present invention, it is possible to provide a polyvinyl alcohol film, an optical film, a polarizing plate, and a liquid crystal display device using the same, which are useful as a member of a liquid crystal display device and the like and have excellent durability.

BEST MODE FOR CARRYING OUT THE INVENTION

  Hereinafter, the present invention will be described in detail. In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

[Polyvinyl alcohol film]
The present invention relates to a polyvinyl alcohol film comprising a composition containing polyvinyl alcohol having a reactive group having active hydrogen in the molecule and a crosslinking agent. When the composition is applied to the surface of a polymer film or the like and dried, the active hydrogen of the reactive group of the polyvinyl alcohol is extracted by the crosslinking agent, so that the crosslinking reaction by the crosslinking agent is promoted and the strength of the film is improved. A film excellent in water resistance is formed. The formed film has the property of imparting sufficient alignment to the liquid crystal to function as an alignment film. Furthermore, the polyvinyl alcohol film has high adhesion to the polymer film surface and is excellent in durability as the entire optical film.
(Summary of Invention)
The present inventor uses a composition containing, on a transparent base film, an acetoacetyl-modified polyvinyl alcohol, which is a polyvinyl alcohol having a reactive group having an active hydrogen in the molecule, and a crosslinking agent. As a result, it was found that an alignment film having good liquid crystal orientation and excellent water resistance can be formed, and the present invention has been completed.

(Polyvinyl alcohol having a reactive group having active hydrogen in the molecule)
The polyvinyl alcohol film of the present invention comprises a composition containing at least one kind of polyvinyl alcohol having a reactive group having active hydrogen in the molecule (hereinafter referred to as “reactive polyvinyl alcohol”). Here, active hydrogen refers to a hydrogen atom having a high reactivity among hydrogen atoms present in an organic compound. Examples thereof include hydrogen directly bonded to atoms having high electronegativity (for example, N and O). An atom and a hydrogen atom bonded to a carbon having a plurality of electron-attracting groups (for example, —COR) bonded thereto are included. Examples of the reactive group include an acetoacetyl group (also referred to as an acetoacetate group), a diacetone acrylamide group, a primary amino group, a secondary amino group, and a primary hydroxyl group. Among them, acetoacetyl-modified polyvinyl alcohol having an acetoacetyl group is preferable as the reactive group.

(Acetoacetyl-modified polyvinyl alcohol)
Acetoacetyl-modified polyvinyl alcohol (hereinafter, polyvinyl alcohol is sometimes referred to as “PVA”. Also, acetoacetyl-modified polyvinyl alcohol is sometimes referred to as AA-modified PVA). PVA substituted with a group (CH ₃ COCH ₂ CO—). In the present invention, it is preferable to use AA-modified PVA as the reactive PVA.

  The AA-modified PVA can be synthesized, for example, by a method in which diketene is reacted with PVA (see, for example, JP-A-55-137107). Moreover, an acetoacetyl group can also be introduce | transduced by acetoacetic ester exchange reaction to PVA.

Moreover, such AA modified PVA can also be obtained as a commercial item. For example, in the present invention, commercially available products such as Goseifamer Z200, Z210, Z220, Z100 manufactured by Nippon Synthetic Chemical Industry Co., Ltd. can be preferably used.
AA modified PVA may be used independently or may use 2 or more types together.

  In the present invention, the reactive PVA is preferably an AA-modified PVA having an average saponification degree of 65 to 100 mol%, more preferably an AA-modified PVA having an average saponification degree of 80 to 99.7 mol%. It is more preferable to use AA-modified PVA having an average saponification degree of 90 to 99.5 mol%, and it is even more preferable to use AA-modified PVA having an average saponification degree of 95 to 99.5 mol%. By setting the degree of saponification within the above range, sufficient water solubility can be obtained.

  The average degree of polymerization of the AA-modified PVA (measured according to JIS K6726) is preferably 150 to 3000, more preferably 200 to 2500, and still more preferably 250 to 2000. By suppressing the average degree of polymerization to the above range, it is possible to control the sufficient film strength and the viscosity of the aqueous solution to a range that can be easily handled.

  The modification degree of the acetoacetyl group of the AA-modified PVA is preferably from 0.1 to 15 mol%, more preferably from 0.3 to 10 mol%, still more preferably from 0.5 to 5.0 mol%. If the degree of modification is too small, sufficient water resistance of the alignment film cannot be obtained. In addition, if the degree of modification is too high, the aqueous solution may become turbid, and the alignment state is disturbed when the alignment film is formed.

The degree of modification of the acetoacetyl group of the AA-modified PVA represents the amount (mol%) of the acetoacetyl group with respect to all vinyl structural units of the AA-modified PVA, and specifically, the main chain in the ¹ H-NMR spectrum. It can be determined by the ratio of the peak area derived from the methylene proton of the acetylene and the peak area derived from the methylene proton of the acetoacetyl group.

  The AA-modified PVA is preferably contained in an amount of 50% by mass or more in terms of solid content, more preferably 70% by mass or more, in the total binder contained in the polyvinyl alcohol film of the present invention, and 80% by mass. The above is particularly preferable. By increasing the ratio of AA-modified PVA, the degree of cross-linking of the alignment film can be increased and the water resistance can be improved. Accordingly, the upper limit is not particularly limited and may be 100% by mass. However, as described later, in view of the adhesiveness with the optically anisotropic layer made of the liquid crystal composition, a polymerizable group is separately provided. In such an embodiment, the content of AA-modified PVA in all binders is preferably 99.5% by mass or less.

  In the composition used for forming the polyvinyl alcohol film of the present invention, the content of the AA-modified PVA is preferably 0.5 to 20% by mass, more preferably 1.0 to 10% by mass. preferable.

  For the production of the polyvinyl alcohol film of the present invention, in addition to the AA-modified PVA, in order to add desired characteristics, a polymer having another hydrophilic group can be used in combination as long as the effects of the present invention are not impaired. . As the polymer that can be used in combination, unmodified PVA and modified PVA having a reactive group other than acetoacetyl modification are preferable.

(Reactive PVA other than AA-modified PVA)
In the present invention, polyvinyl alcohol having a diacetone acrylamide group may be used as the reactive PVA. Specifically, a PVA having a diacetone acrylamide group obtained by saponifying a copolymer of diacetone acrylamide and a fatty acid ester described in JP-A-10-330572 and the like by a conventionally known method. Etc. can be used.
The amount of diacetone acrylamide group contained in the reactive PVA is 0.1 to 20 mol% (more preferably 1 to 15 mol%, further preferably 2 to 12 mol%, still more preferably 3 to 8 mol%). ) Is preferable, and if it is less than 0.1 mol%, sufficient water resistance may not be exhibited. If it exceeds 20 mol%, the water solubility decreases when used as a coating liquid, and the stability of the obtained coating liquid. May decrease. The preferred range of the saponification degree and average polymerization degree is the same as that of the above-mentioned AA-modified PVA.

In the present invention, polyvinyl alcohol having an amino group may be used as the reactive PVA. Specifically, for example, an amino group obtained by completely saponifying a product obtained by copolymerizing N-vinylformamide and a fatty acid ester in methanol as described in JP-A-2-11609, etc. by a conventionally known method. PVA etc. which have can be used.
The amount of amino group contained in the reactive PVA is 0.1 to 20 mol% (more preferably 1 to 15 mol%, still more preferably 2 to 12 mol%, still more preferably 3 to 8 mol%). When the amount is less than 0.1 mol%, sufficient water resistance may not be exhibited. When the amount exceeds 20 mol%, the water solubility decreases when the coating solution is used, and the stability of the obtained coating solution is low. It may decrease and is not preferable. The preferred range of the saponification degree and average polymerization degree is the same as that of the above-mentioned AA-modified PVA.

  In the present invention, polyvinyl alcohol containing a primary hydroxyl group may be used as the reactive PVA. Specifically, polyvinyl alcohols containing a 1,2-glycol bond in the side chain can be used. Polyvinyl alcohols containing a 1,2-glycol bond in the side chain include, for example, a 1,2-glycol bond by a saponification reaction of a vinyl ester monomer, 3,4-diacetoxy-1-butene, vinyl ethylene carbonate, etc. It is obtained by saponifying a copolymer with a monomer capable of producing Examples of the vinyl ester monomers include vinyl formate, vinyl acetate, vinyl propionate, vinyl valelate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl benzoate. , And vinyl versatate, and vinyl acetate is preferably used because it is easily available.

(PVA having a polymerizable group in the molecule)
The polyvinyl alcohol film of the present invention has a polymerizable group in the molecule in order to ensure adhesion with a layer formed on the film (for example, an optically anisotropic layer formed from a liquid crystal composition). It is preferably formed from a composition containing PVA (hereinafter sometimes referred to as “polymerizable PVA”). When the liquid crystalline molecules having a polymerizable group are aligned on the polyvinyl alcohol film containing polymerizable PVA, the alignment state is fixed by polymerization, and an optically anisotropic layer or the like is formed. A chemical bond is formed at the interface between the adhesive layer and the polyvinyl alcohol film, and adhesion is improved. Thereby, durability of the whole optical films, such as an optical compensation film, can be improved. Examples of the polymerizable PVA include PVA containing a repeating unit having a polymerizable group, and PVA obtained by reacting a compound having a polymerizable group with PVA or modified PVA.

  When the polymerizable group of the polymerizable PVA is capable of undergoing a polymerization reaction with the polymerizable group (Q) of the liquid crystal molecule described later, the liquid crystal molecule and the modified PVA are chemically formed at the interface between the layers. It is preferable to bond and improve the adhesion between the layers. Therefore, the polymerizable group possessed by the polymerizable PVA is preferably selected according to the type of the polymerizable group (Q) of the liquid crystal molecule described later. As described later, the polymerizable group (Q) of the liquid crystal molecule is preferably an unsaturated polymerizable group (examples Q1 to Q7 described later), an epoxy group (Q8) or an aziridinyl group (Q9). A saturated polymerizable group is more preferable, and an ethylenically unsaturated polymerizable group (Q1 to Q6) is still more preferable. Similarly, the polymerizable group of the modified PVA is preferably an unsaturated polymerizable group, an epoxy group or an aziridinyl group, more preferably an unsaturated polymerizable group, and an ethylenically unsaturated polymerizable group. Most preferred.

  In the polymerizable PVA, the main chain and the polymerizable group are preferably connected via a connecting group without being directly connected. Examples of the linking group include -O-, -O-CO-, -O-CO-NH-, -O-CO-NH-alkylene group-, -O-CO-NH-alkylene group -O-,- O-CO-NH-alkylene group -CO-O-, -O-CO-NH-alkylene group -O-CO-, -O-CO-NH-alkylene group -CO-NH-, -O-CO-alkylene -O-CO-, -O-CO-arylene group -O-alkylene group -O-CO-, -O-CO-arylene group -O-alkylene group -O-, -O-CO-arylene group -O -Alkylene group- and -O-alkylene group-O-CO- are included (the left side is bonded to the main chain and the right side is bonded to the polymerizable group). The alkylene group may have a branched or cyclic structure. The number of carbon atoms of the alkylene group is preferably 1-30, more preferably 1-20, still more preferably 1-15, and even more preferably 1-12. The arylene group is preferably phenylene or naphthylene, more preferably phenylene, and most preferably p-phenylene. The arylene group may have a substituent. Examples of the substituent of the arylene group include a halogen atom (F, Cl, Br), carboxyl, cyano, nitro, carbamoyl, sulfamoyl, alkyl group, cycloalkyl group, alkoxy group, alkylthio group, acyl group, acyloxy group, alkyl Substituted carbamoyl groups, alkyl-substituted sulfamoyl groups, amide groups, sulfonamido groups and alkylsulfonyl groups are included.

  The alkyl group may have a branch. The number of carbon atoms in the alkyl group is preferably 1-20, more preferably 1-15, still more preferably 1-10, and even more preferably 1-6. The cycloalkyl group is preferably cyclohexyl. The alkoxy group may have a branch. The number of carbon atoms in the alkoxy group is preferably 1-20, more preferably 1-15, still more preferably 1-10, and even more preferably 1-6. The alkylthio group may have a branch. The number of carbon atoms in the alkylthio group is preferably 1-20, more preferably 1-15, still more preferably 1-10, and even more preferably 1-6. The acyl group preferably has 2 to 20 carbon atoms, more preferably 2 to 15, more preferably 2 to 10, and still more preferably 2 to 6. The number of carbon atoms of the acyloxy group is preferably 2-20, more preferably 2-15, still more preferably 2-10, and even more preferably 2-6.

  The number of carbon atoms in the alkyl-substituted carbamoyl group is preferably 2-20, more preferably 2-15, still more preferably 2-10, and most preferably 2-6. The alkyl part of the alkyl-substituted carbamoyl group may further have a substituent (eg, alkoxy group). The number of carbon atoms in the alkyl-substituted sulfamoyl group is preferably 1-20, more preferably 1-15, still more preferably 1-10, and even more preferably 1-6. . The alkyl portion of the alkyl-substituted sulfamoyl group may further have a substituent (eg, an alkoxy group). The number of carbon atoms in the amide group is preferably 2-20, more preferably 2-15, still more preferably 2-10, and even more preferably 2-6. The number of carbon atoms in the sulfonamide group is preferably 1-20, more preferably 1-15, still more preferably 1-10, and even more preferably 1-6. The number of carbon atoms in the alkylsulfonyl group is preferably 1-20, more preferably 1-15, still more preferably 1-10, and even more preferably 1-6. The alkyl part of the alkylsulfonyl group may further have a substituent (eg, an alkoxy group).

  The polymerizable PVA may have two or more polymerizable groups. A preferred example of the polymerizable PVA is PVA including a repeating unit having a polymerizable group represented by the following formula (II).

In the formula (II), L ¹¹ represents a single bond, —CO—, —CO—NH—, —CO—NH-alkylene group—, —CO—NH-alkylene group —O—, —CO—NH-alkylene group. -CO-O-, -CO-NH-alkylene group -O-CO-, -CO-NH-alkylene group -CO-NH-, -CO-alkylene group -O-CO-, -CO-arylene group -O -Alkylene group-O-CO-, -CO-arylene group-O-alkylene group-O-, -CO-arylene group-O-alkylene group- and -alkylene group-O-CO- selected from the group consisting of It is a group. -CO-NH-alkylene group-, -CO-NH-alkylene group-O-, -CO-NH-alkylene group-O-CO-, -CO-arylene group-O-alkylene group-O-CO-,- CO-arylene group-O-alkylene group-O-, -CO-arylene group-O-alkylene group- and -alkylene group-O-CO- are preferred, and -CO-NH-alkylene group-O-CO- is particularly preferred. preferable. The alkylene group may have a branched or cyclic structure. The number of carbon atoms of the alkylene group is preferably 1-30, more preferably 1-20, still more preferably 1-15, and even more preferably 1-12. The arylene group is preferably phenylene or naphthylene, more preferably phenylene, and most preferably p-phenylene. The arylene group may have a substituent. Examples of the substituent for the arylene group are the same as the examples of the substituent for the arylene group described above. In the formula (II), Q is a polymerizable group. As described above, the polymerizable group is preferably the same group as the polymerizable group (Q) of the liquid crystal molecule. Examples of repeating units having a polymerizable group are shown below.

  The polymerizable PVA is produced, for example, by reacting a commercially available unmodified poly with bil alcohol and a reagent such as methacryloyloxyethyl isocyanate or 4- (4-acryloyloxybutoxy) benzoic acid in the presence of a catalyst. be able to. As commercially available unmodified polyvinyl alcohol used as a raw material, PVA103, PVA203, and PVA205 (all manufactured by Kuraray) can be used. This method is described in detail in JP-A-9-152509 and other publications.

  The polymerizable PVA preferably has an average degree of saponification of 95% or less, and more preferably 90 mol% or less. Lowering the degree of saponification is preferable because the difference in surface energy from the high-saponification degree PVA molecules that are the main components of the alignment film is increased and the surface tends to be unevenly distributed. The average saponification degree of the polymerizable PVA is preferably about 70% or more.

  The average degree of polymerization of the polymerizable PVA is preferably 800 or less, more preferably 600 or less, and particularly preferably 400 or less. Decreasing the degree of polymerization facilitates the movement of the molecule, and PVA molecules having a crosslinking group in the molecule tend to be unevenly distributed on the surface, which is preferable. The average degree of polymerization of the polymerizable PVA is preferably about 50 or more.

In the polyvinyl alcohol film of the present invention, the content of the polymerizable PVA in the total solid content of the binder is preferably 0.1 to 20% by mass, more preferably 0.3 to 15% by mass, More preferably, it is 0.5-10 mass%.
By setting the blending amount in the above range, it is possible to increase the cohesive force of the alignment film and ensure water resistance while ensuring interface adhesion.

  The polyvinyl alcohol of the present invention preferably contains one or more kinds of PVA as a main component, and in the solid content of all components in the film, the PVA is preferably 70% by mass or more, More preferably, it is 80 mass% or more.

(Crosslinking agent)
The polyvinyl alcohol film of the present invention is formed from a composition containing a crosslinking agent together with the reactive PVA. Examples of the crosslinking agent include aldehydes, N-methylol compounds, dioxane derivatives, compounds that act by activating carboxyl groups, active vinyl compounds, active halogen compounds, isoxazole and dialdehyde starch. More specifically, compounds described in paragraph numbers [0023] to [0024] of JP-A No. 2002-62426 may be mentioned. Of these, aldehydes are preferred, and bifunctional aldehydes are particularly preferred.

Specific examples of the bifunctional aldehyde include the following.
1) Aliphatic bifunctional aldehydes such as glyoxal, malonaldehyde, succinaldehyde, glutaraldehyde, adipaldehyde and the like.
2) Aromatic bifunctional aldehydes such as phthalaldehyde, isophthalaldehyde and terephthalaldehyde.
3) Polymer bifunctional aldehydes such as double-end aldehyded poval and dialdehyde starch.
Of these, aliphatic bifunctional aldehydes with high reaction activity are preferred.

  0.5-30 mass% is preferable with respect to the said reactive PVA, as for the addition amount of the said crosslinking agent, 3-25 mass% is more preferable, and 5-20 mass% is still more preferable.

(Method for forming polyvinyl alcohol film)
The polyvinyl alcohol film of the present invention is formed from a composition containing reactive PVA, a cross-linking agent, polymerizable PVA that is optionally added, and other additives. The composition is preferably prepared as a coating solution. The composition prepared as a coating solution is applied to the surface of a polymer film or the like and then dried, and at the same time, a crosslinking reaction is allowed to proceed to form a film. The crosslinking reaction can be performed at any time after being applied to the surface of a polymer film or the like.

  When preparing the composition as a coating solution, it is preferable to use a mixed solvent of an organic solvent (eg, methanol) and water having an antifoaming action. The ratio by mass is water: methanol greater than 0 and 99 or less: less than 100, preferably 1 or more, and more preferably greater than 0 and 91 or less: less than 100, 9 or more. Thereby, generation | occurrence | production of a bubble is suppressed and the defect of layer surfaces, such as a film surface and the optically anisotropic layer formed on it, can be reduced.

  The composition is preferably applied by spin coating, dip coating, curtain coating, extrusion coating, rod coating, roll coating, or the like. In particular, the rod coating method or the extrusion coating method is preferable. Although there is no restriction | limiting in particular about an application quantity, It is preferable to set it as the application quantity from which the film thickness after drying becomes about 0.1-10 micrometers.

  After coating, the coating solution is dried to remove the solvent in the coating solution, and the crosslinking reaction proceeds to form a film. When drying, it may be heated as desired. Drying is preferably performed at 20 ° C to 110 ° C. In order to form sufficient cross-linking, 60 ° C to 100 ° C is preferable, and 80 ° C to 100 ° C is particularly preferable. The drying time is preferably 1 minute to 36 hours, more preferably 1 minute to 30 minutes. The pH is also preferably set to an optimum value for the crosslinking agent to be used. When glutaraldehyde is used as the crosslinking agent, the pH is preferably 2.5 to 5.5.

  When the polyvinyl alcohol film of the present invention is used as an alignment film, the surface of the formed film may be rubbed. For the rubbing treatment, a treatment method widely adopted as a liquid crystal alignment treatment process of LCD can be applied. That is, a method of obtaining the orientation by rubbing the surface of the orientation film in a certain direction using paper, gauze, felt, rubber, nylon, polyester fiber or the like can be used. Generally, it is carried out by rubbing using a cloth in which fibers having uniform length and thickness are flocked on average.

[Optical film]
The present invention also relates to an optical film having a polymer film and the polyvinyl alcohol film of the present invention thereon. One aspect of the optical film of the present invention has an optically anisotropic layer formed from a liquid crystal composition on the polyvinyl alcohol film. In this embodiment, the polyvinyl alcohol film can be used as an alignment film of a liquid crystal composition.
(Optically anisotropic layer)
The optically anisotropic layer can be formed from a polymerizable liquid crystal composition containing a liquid crystal compound.
-Liquid crystal compound The polymerizable liquid crystal composition used for forming the optically anisotropic layer contains at least one liquid crystal compound. The liquid crystal compound is preferably a polymerizable liquid crystal compound having a polymerizable group. Liquid crystal compounds are generally classified into rod-like liquid crystal compounds and discotic liquid crystal compounds based on their molecular shapes. In the present invention, any liquid crystal compound may be used.
-Rod-like liquid crystal compounds As rod-like liquid crystal compounds, azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted compounds Phenylpyrimidines, phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used. In addition to the low-molecular liquid crystals as described above, polymer liquid crystals can also be used. As the rod-like liquid crystal compound, those having a partial structure capable of causing polymerization or crosslinking reaction by actinic rays, electron beams, heat, or the like are suitably used. The number of the partial structures is 1 to 6, preferably 1 to 3. As described above, the rod-like liquid crystalline molecules that can be used in the present invention preferably have a polymerizable group in order to fix the alignment state. The polymerizable group is preferably a radically polymerizable unsaturated group, and specific examples thereof include a polymerizable group and a polymerizable liquid crystal compound described in JP-T-1000-514202 or JP-A-2002-62427. There is no restriction | limiting in particular about the orientation form of the rod-shaped liquid crystalline molecule in the said optically anisotropic layer. The orientation may be any of vertical, horizontal, and hybrid with respect to the layer surface.

  As described above, it is more preferable to fix the alignment of the rod-like liquid crystalline molecules by polymerization. Chem. 190, 2255 (1989), Advanced Materials 5, 107 (1993), US Pat. Nos. 4,683,327, 5,622,648 and 5,770,107, WO 95/22586, 95/24455, 97/97. No. 0600, No. 98/23580, No. 98/52905, JP-A-1-272551, JP-A-6-16616, JP-A-7-110469, JP-A-11-80081, and Japanese Patent Application No. 2001-64627. 2001-328773 gazette) and the like can be used. More preferably, it is a compound represented by the following general formula (II).

^{(IV) Q 1 -L 1 -Cy} 1 -L 2 - (Cy 2 -L 3) n -Cy 3 -L 4 -Q 2
In the formula, Q ¹ and Q ² are each independently a polymerizable group, L ¹ and L ⁴ are each independently a divalent linking group, and L ² and L ³ are each independently a single bond or a divalent group. It is a linking group, Cy ¹ , Cy ² and Cy ³ are divalent cyclic groups, and n is 0, 1 or 2.

The polymerizable rod-like liquid crystal compound will be further described below.
^{(IV) Q 1 -L 1 -Cy} 1 -L 2 - (Cy 2 -L 3) n -Cy 3 -L 4 -Q 2
In the formula, Q ¹ and Q ² are each independently a polymerizable group. The polymerization reaction of the polymerizable group is preferably addition polymerization (including ring-opening polymerization) or condensation polymerization. In other words, the polymerizable group is preferably a functional group capable of addition polymerization reaction or condensation polymerization reaction. Examples of polymerizable groups are shown below.

  In the formula, Q is a polymerizable group, the polymerizable group (Q) in the polyvinyl alcohol having a crosslinkable group in the molecule, the polymerizable group (Q) in a discotic liquid crystal compound having a polymerizable group described later, and As described above, it is preferably an unsaturated polymerizable group (the above-mentioned examples Q1 to Q7), an epoxy group (Q8) or an aziridinyl group (Q9), and more preferably an unsaturated polymerizable group. And most preferably an ethylenically unsaturated polymerizable group (Q1 to Q6).

L ¹ and L ⁴ are each independently a divalent linking group. L ¹ and L ⁴ are each independently two selected from the group consisting of —O—, —S—, —CO—, —NR ² —, a divalent chain group, a divalent cyclic group, and combinations thereof. A valent linking group is preferred. R ² is an alkyl group having 1 to 7 carbon atoms or a hydrogen atom. R ² is preferably an alkyl group having 1 to 4 carbon atoms or a hydrogen atom, more preferably a methyl group, an ethyl group or a hydrogen atom, and most preferably a hydrogen atom. The example of the bivalent coupling group which consists of a combination is shown below. Here, the left side is coupled to Q (Q ¹ or Q ² ), and the right side is coupled to Cy (Cy ¹ or Cy ³ ).

L-1: —CO—O—divalent chain group —O—
L-2: -CO-O-divalent chain group -O-CO-
L-3: —CO—O—divalent chain group —O—CO—O—
L-4: -CO-O-divalent chain group -O-divalent cyclic group-
L-5: -CO-O-divalent chain group -O-divalent cyclic group -CO-O-
L-6: -CO-O-divalent chain group -O-divalent cyclic group -O-CO-
L-7: -CO-O-divalent chain group-O-divalent cyclic group-divalent chain group-
L-8: -CO-O-divalent chain group -O-divalent cyclic group -divalent chain group -CO-O-
L-9: -CO-O-divalent chain group -O-divalent cyclic group -divalent chain group -O-CO-
L-10: —CO—O—divalent chain group—O—CO—divalent cyclic group—
L-11: -CO-O-divalent chain group -O-CO-divalent cyclic group -CO-O-
L-12: -CO-O-divalent chain group -O-CO-divalent cyclic group -O-CO-
L-13: —CO—O—Divalent chain group—O—CO—Divalent cyclic group—Divalent chain group—
L-14: -CO-O-divalent chain group -O-CO-divalent cyclic group -divalent chain group -CO-O-
L-15: -CO-O-divalent chain group-O-CO-divalent cyclic group-divalent chain group-O-CO-
L-16: —CO—O—divalent chain group—O—CO—O—divalent cyclic group—
L-17: -CO-O-divalent chain group -O-CO-O-divalent cyclic group -CO-O-
L-18: -CO-O-divalent chain group -O-CO-O-divalent cyclic group -O-CO-
L-19: —CO—O—Divalent chain group—O—CO—O—Divalent cyclic group—Divalent chain group—
L-20: -CO-O-divalent chain group -O-CO-O-divalent cyclic group -divalent chain group -CO-O-
L-21: -CO-O-divalent chain group -O-CO-O-divalent cyclic group -divalent chain group -O-CO-

  The divalent chain group means an alkylene group, a substituted alkylene group, an alkenylene group, a substituted alkenylene group, an alkynylene group, or a substituted alkynylene group. An alkylene group, a substituted alkylene group, an alkenylene group and a substituted alkenylene group are preferred, and an alkylene group and an alkenylene group are more preferred. The alkylene group may have a branch. The alkylene group preferably has 1 to 12 carbon atoms, more preferably 2 to 10 carbon atoms, and still more preferably 2 to 8 carbon atoms. The alkylene part of the substituted alkylene group is the same as the above alkylene group. Examples of the substituent include a halogen atom. The alkenylene group may have a branch. The alkenylene group preferably has 2 to 12 carbon atoms, more preferably 2 to 10 carbon atoms, and still more preferably 2 to 8 carbon atoms. The alkenylene part of the substituted alkenylene group is the same as the above alkenylene group. Examples of the substituent include a halogen atom. The alkynylene group may have a branch. The alkynylene group preferably has 2 to 12 carbon atoms, more preferably 2 to 10 carbon atoms, and still more preferably 2 to 8 carbon atoms. The alkynylene part of the substituted alkynylene group is the same as the above alkynylene group. Examples of the substituent include a halogen atom.

  Specific examples of the divalent chain group include ethylene, propylene, tetramethylene, 2-methyl-1,4-butylene, pentamethylene, hexamethylene, octamethylene, 2-butenylene, 2-butynylene and the like.

The definition and examples of the divalent cyclic group are the same as those of Cy ¹ , Cy ² and Cy ³ described later.

L ^{2 and} L ³ are each independently a single bond or a divalent linking group. L ² and L ³ are each independently two selected from the group consisting of —O—, —S—, —CO—, —NR ² —, a divalent chain group, a divalent cyclic group, and combinations thereof. A valent linking group or a single bond is preferred. R ² is an alkyl group having 1 to 7 carbon atoms or a hydrogen atom, preferably an alkyl group having 1 to 4 carbon atoms or a hydrogen atom, and is a methyl group, an ethyl group or a hydrogen atom. Is more preferable, and a hydrogen atom is most preferable. The divalent chain group and the divalent cyclic group have the same definitions as L ¹ and L ⁴ .

In the formula (IV), n is 0, 1 or 2. When n is 2, two L ³ may be the same or different, and two Cy ² may be the same or different. n is preferably 1 or 2, and more preferably 1.

In formula (IV), Cy ¹ , Cy ² and Cy ³ are each independently a divalent cyclic group. The ring contained in the cyclic group is preferably a 5-membered ring, a 6-membered ring, or a 7-membered ring, more preferably a 5-membered ring or a 6-membered ring, and most preferably a 6-membered ring. The ring contained in the cyclic group may be a condensed ring. However, it is more preferably a monocycle than a condensed ring. The ring contained in the cyclic group may be any of an aromatic ring, an aliphatic ring, and a heterocyclic ring. Examples of the aromatic ring include a benzene ring and a naphthalene ring. Examples of the aliphatic ring include a cyclohexane ring. Examples of the heterocyclic ring include a pyridine ring and a pyrimidine ring.
As the cyclic group having a benzene ring, 1,4-phenylene is preferable. As the cyclic group having a naphthalene ring, naphthalene-1,5-diyl and naphthalene-2,6-diyl are preferable. The cyclic group having a cyclohexane ring is preferably 1,4-cyclohexylene. As the cyclic group having a pyridine ring, pyridine-2,5-diyl is preferable. The cyclic group having a pyrimidine ring is preferably pyrimidine-2,5-diyl.

  The cyclic group may have a substituent. Examples of the substituent include a halogen atom, a cyano group, a nitro group, an alkyl group having 1 to 5 carbon atoms, a halogen-substituted alkyl group having 1 to 5 carbon atoms, and an alkoxy group having 1 to 5 carbon atoms. , An alkylthio group having 1 to 5 carbon atoms, an acyloxy group having 2 to 6 carbon atoms, an alkoxycarbonyl group having 2 to 6 carbon atoms, a carbamoyl group, and an alkyl-substituted carbamoyl group having 2 to 6 carbon atoms And an acylamino group having 2 to 6 carbon atoms.

  Examples of the polymerizable rod-like liquid crystal compound represented by the formula (IV) are shown below, but are not limited thereto.

-Discotic liquid crystal compounds Discotic liquid crystal compounds can be obtained from various documents (C. Destrade et al., Mol. Crysr. Liq. Cryst., Vol. 71, page 111 (1981); edited by the Chemical Society of Japan). , Quarterly Chemical Review, No. 22, Liquid Crystal Chemistry, Chapter 5, Chapter 10 Section 2 (1994); B. Kohne et al., Angew. Chem. Soc. Chem. Comm., Page 1794 (1985). J. Zhang et al., J. Am.Chem.Soc., Vol.116, page 2655 (1994)). Either can be used in the present invention. Moreover, about superposition | polymerization of a discotic liquid crystalline compound, Unexamined-Japanese-Patent No. 8-27284 has description.

  The discotic liquid crystalline compound preferably has a polymerizable group so that it can be fixed by polymerization. For example, a structure in which a polymerizable group is bonded as a substituent to a discotic core of a discotic liquid crystalline compound is conceivable. However, when a polymerizable group is directly connected to the discotic core, the alignment state is maintained in the polymerization reaction. It becomes difficult. Therefore, a structure having a linking group between the discotic core and the polymerizable group is preferable. That is, the discotic liquid crystalline compound having a polymerizable group is preferably a compound represented by the following formula.

D (-LQ) _n
In the formula, Q is a polymerizable group, and is synonymous with the polymerizable group (Q) in the polyvinyl alcohol having a crosslinkable group in the molecule, and the polymerizable group (Q) in the polymerizable rod-like liquid crystal compound, As described above, it is preferably an unsaturated polymerizable group (the above-described examples Q1 to Q7), an epoxy group (Q8) or an aziridinyl group (Q9), more preferably an unsaturated polymerizable group, and an ethylenic group. Most preferably, it is a saturated polymerizable group (Q1 to Q6).
D is a disk-shaped core, L is a divalent linking group, and n is an integer of 3 to 12. Preferred specific examples of the discotic core (D) and the divalent linking group (L) in the above formula are (D1) to (D15) and (L1) to (D1) described in JP-A No. 2001-4837, respectively. (L25), and the contents described in the publication can be preferably used.

  The above discotic (discotic) compounds generally have a structure in which these are used as a mother nucleus at the center of a molecule, and a linear alkyl group, an alkoxy group, a substituted benzoyloxy group, etc. are radially substituted as the linear chain. , Which shows liquid crystallinity and is generally called a discotic liquid crystal. However, the molecule itself is not limited to the above description as long as the molecule itself has negative uniaxiality and can give a certain orientation. Further, in the present invention, it is not necessary that the final product is formed from a discotic compound, for example, the low molecular discotic liquid crystal has a group that reacts with heat, light, or the like. As a result, it may be polymerized or cross-linked by reaction with heat, light, etc., to have a high molecular weight and lose liquid crystallinity.

  Preferred examples of the discotic compound are shown below.

Other components The polymerizable liquid crystal composition may contain components other than the compound capable of bonding to the (meth) acryl group and the liquid crystal compound. For example, it may contain a polymerization initiator, an alignment controller, a surfactant and the like as desired.
-Polymerization initiator As the polymerization initiator, any of a thermal polymerization initiator used in a thermal polymerization reaction and a photopolymerization initiator used in a photopolymerization reaction may be used, and a photopolymerization initiator is preferable. Examples of photopolymerization initiators include α-carbonyl compounds (described in US Pat. Nos. 2,367,661 and 2,367,670), acyloin ether (US Pat. No. 2,448,828). ), Α-hydrocarbon substituted aromatic acyloin compounds (described in US Pat. No. 2,722,512), polynuclear quinone compounds (US Pat. Nos. 3,046,127 and 2,951,758) Description), combinations of triarylimidazole dimers and p-aminophenyl ketone (described in US Pat. No. 3,549,367), acridine and phenazine compounds (Japanese Patent Laid-Open No. 60-105667, US Pat. No. 4,239) And oxadiazole compounds (described in U.S. Pat. No. 4,212,970).
The amount of the photopolymerization initiator used is preferably 0.01 to 20% by mass and more preferably 0.5 to 5% by mass of the polymerizable liquid crystal composition (solid content in the case of a coating liquid). preferable.

-Alignment controller The polymerizable liquid crystal composition may contain an alignment controller that controls the alignment of the liquid crystal. The alignment control agent can be selected according to the type of liquid crystal, the desired alignment state, and the like.
For example, when the composition contains a rod-like liquid crystal and the rod-like liquid crystal is to be oriented perpendicular to the layer surface (the long axis is perpendicular to the layer surface), it is preferable to contain an onium salt or the like in the composition. . Specific examples are described in JP-A-2006-301605 (Table 1, second phase difference regions 1 to 3) and the like, and any of them can be used.
Further, when the composition contains a rod-like liquid crystal and the rod-like liquid crystal is oriented horizontally with respect to the layer surface (the long axis is parallel to the layer surface), it is preferable to contain a triazine compound or the like in the composition. . Specific examples are described in JP-A-2006-293275 (Example 2) and the like, and any of them can be used.
Further, when the composition contains a discotic liquid crystal and the discotic liquid crystal is oriented perpendicularly to the layer surface (the disk surface is perpendicular to the layer surface), a pyridinium salt (Example 1) in the composition Etc. are preferably contained. Specific examples are described in JP-A-2006-285187 and the like, and any of them can be used.
In addition, when the composition contains a discotic liquid crystal and the discotic liquid crystal is to be aligned horizontally with respect to the layer surface (the disk surface is horizontal to the layer surface) or when it is desired to perform hybrid alignment, It is preferable to contain a specific fluorine-based polymer. Specific examples are described in JP-A-2006-267183 (Reference Example 2), and any of them can be used.

-Surfactant The polymerizable liquid crystal composition may contain a surfactant in order to improve applicability and the like. As the surfactant, a fluorine-based surfactant is preferable. Specifically, for example, compounds described in paragraph numbers [0028] to [0056] of JP-A No. 2001-330725 are exemplified.

-Method for forming optically anisotropic layer The optically anisotropic layer is prepared by applying the polymerizable composition as a coating liquid, applying it to the surface of the alignment film made of the polyvinyl alcohol film of the present invention, and drying to remove the solvent. While removing, it is preferable to obtain a desired alignment state and fix the alignment state by polymerization.
As the solvent used for preparing the coating solution, an organic solvent is preferably used. Examples of the organic solvent include amide (eg, N, N-dimethylformamide), sulfoxide (eg, dimethyl sulfoxide), heterocyclic compound (eg, pyridine), hydrocarbon (eg, benzene, hexane), alkyl halide ( Examples, chloroform, dichloromethane), esters (eg, methyl acetate, butyl acetate), ketones (eg, acetone, methyl ethyl ketone), ethers (eg, tetrahydrofuran, 1,2-dimethoxyethane) are included. Alkyl halides and ketones are preferred. Two or more organic solvents may be used in combination. The coating liquid can be applied by a known method (eg, extrusion coating method, direct gravure coating method, reverse gravure coating method, die coating method).

After applying the polymerizable liquid crystal composition, it is dried to obtain a desired alignment state, and then cured by polymerization to form an optically anisotropic layer. Polymerization is preferably initiated by light irradiation, and ultraviolet light is preferably used for light irradiation. The irradiation energy is preferably 20 mJ / cm ^{2 to} 50 J / cm ² , and more preferably 100 mJ / cm ^{2 to} 800 mJ / cm ² . Furthermore, in order to accelerate the photopolymerization reaction, light irradiation may be performed under heating conditions.

  The thickness of the optically anisotropic layer is preferably 0.1 to 10 μm, more preferably 0.5 to 5 μm, and still more preferably 1 to 5 μm.

(Polymer film)
The polymer film as a support included in the optical film of the present invention is preferably transparent, and specifically, the light transmittance is preferably 80% or more. Examples of polymer films that can be used include cellulose ester, polycarbonate, polysulfone, polyethersulfone, polyacrylate and polymethacrylate films. Among these, a cellulose ester film is preferable, an acetyl cellulose film is more preferable, and a triacetyl cellulose film is most preferable. The polymer film is preferably formed by a solvent cast method.

  In general, the thickness of the polymer film is preferably 20 to 500 μm, and more preferably 40 to 200 μm. In addition, in order to improve adhesion between the polymer film and the polyvinyl alcohol film of the present invention provided thereon, the polymer film is subjected to surface treatment (eg, glow discharge treatment, corona discharge treatment, ultraviolet (UV) treatment, flame treatment). You may implement. Furthermore, an adhesive layer (undercoat layer) may be provided on the polymer film. Moreover, in order to give the slip property in a conveyance process or to prevent sticking with the back surface and the surface after winding up, the inorganic particle whose average particle diameter is about 10-100 nm is 5% by solid content mass ratio. You may form the polymer layer which mixed -40% on the back surface (surface on the opposite side to the surface which forms an optical anisotropic layer) of a support body. The polymer layer can be formed by a coating method or a co-casting method.

The surface of the polymer film on the side in contact with the polyvinyl alcohol film is preferably hydrophilized from the viewpoint of durability. Hydrophilization can also be achieved by the above-exemplified surface treatment, but among these, it is preferable to make hydrophilic by applying a liquid containing at least an organic solvent, a metal hydroxide salt, water, a compatibilizing agent, and a surfactant to the surface. . This hydrophilization method is particularly effective for a polymer film containing a cellulose-based polymer such as cellulose acylate. The liquid used for the hydrophilization is preferably an alkaline liquid. When the surface of a polymer film containing a cellulosic polymer such as cellulose acylate is treated with an alkaline solution, saponification proceeds, thereby making it hydrophilic.
The organic solvent preferably dissolves the metal hydroxide salt and does not dissolve the cellulose acylate film, and specific examples thereof include methanol, ethanol, isopropanol, isobutanol and the like.
Specific examples of the metal hydroxide salt are preferably alkali metal hydroxides, and include sodium hydroxide, potassium hydroxide and the like.
The compatibilizing agent is preferably a compound that forms a uniform solution by adding the agent when water, an organic solvent, and a metal hydroxide salt are mixed. Specific examples thereof include diethylene glycol, Propylene glycol, polyhydric alcohol and the like are included.
The surfactant is preferably a nonionic surfactant, and specific examples thereof include polyoxyethylene lauryl ether, polyoxyethylene nonyl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene stearyl ether, Oxyethylene oleyl ether, polyoxyethylene behenyl ether, and the like.

  The hydrophilization treatment can be carried out by applying the liquid onto the surface of a polymer film or the like used as a support, leaving it under heating as desired for 10 to 120 seconds, and then washing with water. Before the hydrophilization treatment, the film may be heated to about 30 to 80 ° C. if desired. Further, after coating, the film may be heated to about 30 to 80 ° C. as desired when the film is allowed to stand. Washing with water may be performed a plurality of times, and draining with an air knife or the like is preferable because the number of times of washing with water can be reduced. From the viewpoint of handleability and the like, the surface tension of the liquid is preferably 15 to 65 mN / m, and the viscosity is preferably 0.6 to 20 mPa · s.

Further, when the optical film of the present invention is used as an optical compensation film of a liquid crystal display device, the polymer film preferably has a small optical anisotropy so as not to impair the optical compensation ability of the optical anisotropic layer. Furthermore, the wavelength dispersion of the retardation is preferably small. Specifically, the in-plane retardation of the polymer film is preferably 10 nm or less, and more preferably 5 nm or less. Further, the wavelength dispersibility is specifically the ratio Re (400) / Re (700) between the in-plane retardation Re (400) at a wavelength of 400 nm and the in-plane retardation Re (700) at a wavelength of 700 nm. It is preferable that it is less than 1.2.
However, this is not the case in an aspect in which the optical characteristics necessary for the optical compensation capability are obtained by actively utilizing the optical characteristics of the polymer film.

[Polarizer]
The present invention also relates to a polarizing plate having the optical film of the present invention and a polarizing film. The optical film of the present invention may be bonded as a protective film to one surface of the polarizing film. Hereinafter, the polarizing plate of the present invention will be described.
-Polarizing film The polarizing film includes an iodine polarizing film, a dye polarizing film using a dichroic dye, and a polyene polarizing film, and any of them may be used in the present invention. The iodine polarizing film and the dye polarizing film are generally produced using a polyvinyl alcohol film.

-Protective film It is preferable that a transparent polymer film is used for the protective film bonded to the other surface. “Transparent” means that the light transmittance is 80% or more. As the protective film, a cellulose acylate film and a polyolefin film containing polyolefin are preferable. Among the cellulose acylate films, a cellulose triacetate film is preferable. Of the polyolefin films, a polynorbornene film containing a cyclic polyolefin is preferable.
The thickness of the protective film is preferably 20 to 500 μm, and more preferably 50 to 200 μm.

  The optical film and the polarizing plate of the present invention include various modes of liquid crystal display devices, TN (Twisted Nematic), IPS (In-Plane Switching), OCB (Optically Compensated Bend), VA (Vertically Aligned), ECB (Electrically Cred). And the like can be used for liquid crystal display devices in any display mode. In addition, the liquid crystal display device can be any of a transmissive type, a reflective type, and a transflective type.

  The features of the present invention will be described more specifically with reference to examples and comparative examples. Hereinafter, materials, usage amounts, ratios, processing contents, processing procedures, and the like shown in the examples can be appropriately changed without departing from the gist of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.

[Example 1]
First, an example of an optical compensation film produced by using the polyvinyl alcohol film of the present invention as an alignment film, homeotropic alignment of a discotic liquid crystal, and fixing the alignment state to form an optically anisotropic layer will be described. To do.
(Production of support)
The following composition was put into a mixing tank and stirred while heating at 30 ° C. to dissolve each component to prepare a cellulose acylate solution (SA-1) (inner layer dope and outer layer dope).
Regarding the silica fine particles of the cellulose acylate solution for the outer layer, 20 parts by mass of the following silica fine particles and 80 parts by mass of methanol were mixed well for 30 minutes to obtain a mixed silica molecular dispersion.
Cellulose acylate (SA-1) solution composition:
Cellulose acylate solution composition (parts by mass) For inner layer For outer layer Cellulose acetate with an acyl substitution degree of 2.87 100 100
Triphenyl phosphate (plasticizer) 7.8 7.8
Biphenyl diphenyl phosphate (plasticizer) 3.9 3.9
Methylene chloride (first solvent) 293 314
Methanol (second solvent) 71 76
1-butanol (third solvent) 1.5 1.6
Silica fine particles (AEROSIL R972, manufactured by Nippon Aerosil Co., Ltd.)
0 0.8
Retardation adjuster A 1.50

The obtained inner layer dope and outer layer dope were cast on a drum cooled to −5 ° C. using a three-layer co-casting die.
The film having a residual solvent amount of 70% by mass was peeled off from the drum, and dried at 80 ° C. while being transported with the draw ratio in the transport direction being 110% while holding both ends with a pin tenter, and the residual solvent amount was 10%. By the way, it was dried at 110 ° C. Thereafter, it was dried at a temperature of 140 ° C. for 30 minutes to prepare a cellulose acylate film (CAF-1, outer layer: 3 μm, inner layer: 74 μm, outer layer: 3 μm) having a residual solvent of 0.3% by mass. The obtained CAF-1 had a width of 1340 mm and a thickness of 80 μm.
The obtained film CAF-1 had an in-plane slow axis in the longitudinal direction, Re (630) was 8 nm, and Rth (630) was 80 nm.

Alkali saponification treatment One side of the film CAF-1 was subjected to the following alkali saponification treatment.
The film (CAF-1) is passed through a dielectric heating roll having a temperature of 60 ° C. and heated to a film surface temperature of 40 ° C., and then an alkali solution (S-1) having the composition shown below is used with a rod coater. It apply | coated with the application quantity of 17 mL / m < ² >, and it was made to retain for 10 second under the steam type far-infrared heater by Noritake Co., Ltd. which was heated to 110 degreeC. Then, using a rod coater as well, “applying 2.8 mL / m ^{2 of} distilled water, then washing with a fountain coater and draining with an air knife three times to wash off the alkali, It dwelled for 2 seconds and dried to produce a single-sided saponified film KF-1.
Alkaline solution (S-1) composition:
Potassium hydroxide 8.6 parts by weight Water 24.1 parts by weight Isopropanol 56.3 parts by weight Surfactant (K-1: C ₁₆ H ₃₃ O (CH ₂ CH ₂ O) ₁₀ H) 1.0 part by weight Propylene glycol 10.0 parts by mass Alkaline solution (S-1) properties:
Surface tension 20mN / m
Viscosity 5.2 mPa · s

  When the surface of the saponified film KF-1 was measured for the contact angle with water, the result of measurement at 10 points was in the range of 36 to 38 °.

(Preparation of coating solution for alignment film)
Using each PVA shown in Table 1, various coating solutions for alignment films having the following compositions were prepared. In the composition, the numbers are parts by mass. The amount of PVA below is the total amount of PVA (1) and PVA (2) in Table 1, and the proportion of PVA (2) corresponds to the mixing ratio in Table 1.
Composition of alignment film coating solution:
PVA 1.244
Glutaraldehyde (50% aqueous solution) 0.12
Citric acid, 1 ethyl citrate, 2 ethyl citrate,
And a mixture of 3 ethyl citrate 0.022
Methanol 9.02
Water 28.794

In Table 1, Z100, Z200, Z210, and Z220 are respectively trade names of acetoacetyl-modified PVA manufactured by Nippon Synthetic Chemical Industry Co., Ltd. It is Goseifamer Z220, NL05 is a trade name of unmodified PVA manufactured by Nippon Synthetic Chemical Industry Co., Ltd., Gohsenol NL-05, and the average polymerization degree and saponification degree are shown in Table 1.
Further, in Table 1, polymerizable PVA is PVA203 (stock) instead of MP203 (manufactured by Kuraray Co., Ltd.) used in accordance with Synthesis Example 1 described in [0101] column of JP-A-9-152509. This is a polymerizable PVA produced by using Kuraray Co., Ltd.

(Formation of alignment layer)
Each of the alignment film coating solutions prepared above is applied to the saponified surface of the saponified film (KF-1) at a coating amount of 31 mL / m ² and dried at a temperature of 100 ° C. for 2 minutes. The optical films on which the alignment films were formed were respectively produced.

(Formation of optically anisotropic layer)
A coating liquid (D-1) containing a discotic liquid crystalline compound having the following composition was prepared.
(Preparation of coating liquid D-1 for optically anisotropic layer)
――――――――――――――――――――――――――――――――――――
Composition of coating liquid (D-1) containing discotic liquid crystal compound ――――――――――――――――――――――――――――――――――― -
The following discotic liquid crystalline compound (I) 91 parts by mass Ethylene oxide modified trimethylolpropane triacrylate (V # 360, manufactured by Osaka Organic Chemical Co., Ltd.) 9 parts by mass Photopolymerization initiator (Irgacure 907, manufactured by Ciba Geigy) 3 parts by mass Sensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.) 1 part by mass The following fluoropolymer 0.4 part by mass Methyl ethyl ketone 212 parts by mass ――――――――――――――― ―――――――――――――――――――――

The coating liquid (D-1) was continuously applied onto the prepared alignment film with a # 6.0 wire bar. The conveyance speed of the film was 20 m / min. The solvent was dried in a step of continuously heating from room temperature to 80 ° C., and then heated in a drying zone at 120 ° C. for 90 seconds to align the discotic liquid crystalline compound. Subsequently, the temperature of the film is maintained at 90 ° C., UV light is irradiated at 500 mJ / cm ² using a high-pressure mercury lamp, the orientation of the liquid crystal compound is fixed, an optically anisotropic layer is formed, and an optical compensation film F1-1 was produced.

  An optical birefringence meter (KOBRA-21ADH, Oji Scientific Instruments Co., Ltd.) obtained by removing only the optically anisotropic layer containing the discotic liquid crystalline compound from the produced optical compensation film F1-1 and the optical compensation film F1-1. The optical properties were measured using a). Re measured at a wavelength of 590 nm of the optical compensation film F1-1 was 2 nm, and Rth was 280 nm. Further, Re of the optically anisotropic layer alone was 0 nm, and Rth was 200 nm. It was also confirmed that an optically anisotropic layer in which the discotic liquid crystal structural unit was aligned substantially horizontally with respect to the film surface was confirmed.

(Preparation of optical compensation films F1-2 to F1-8)
For the optical compensation film F1-1 produced above, the composition of the coating liquid for alignment film and the curing temperature at the time of forming the optically anisotropic phase (temperature at the time of UV light irradiation) were changed as shown in Table 1. In the same manner as in F1-1, optical compensation films F1-2 to F1-8 were produced.
F1-6 and F1-7 are comparative examples using unmodified PVA instead of AA-modified PVA, F1-8 is a comparative example without addition of a crosslinking agent, and F1-9 is an AA-modified PVA. It is a comparative example using PVA which has a polymeric group instead.

Each optical compensation film prepared above was evaluated for water resistance, adhesion, and refractive index anisotropy according to the following methods. The results are shown in Table 1.
(Water resistance evaluation)
Each of the produced optical compensation film samples was immersed in warm water at 40 ° C. for 30 minutes, and then the adhesiveness of the film was evaluated by rubbing the optical compensation layer side of the film with a finger. The evaluation criteria are as follows.
(Double-circle): It does not peel even if it rubs strongly.
◯: Can not be peeled lightly.
Δ: Slightly peeled off when rubbed lightly.
X: Peel off when gently rubbed.
The evaluation results are shown in Table 1.

(Adhesion evaluation)
In each of the optical compensation film samples prepared above, 11 vertical and 11 horizontal cuts were made in a grid pattern with a cutter knife to make a total of 100 square squares. A polyester adhesive tape “No. 31B” manufactured by Nitto Denko Co., Ltd. was pressure-bonded and subjected to an adhesion test. The presence or absence of peeling was visually observed, and the following four-stage evaluation was performed.
◎: No peeling was observed in 100 squares ○: No peeling was observed in 100 squares within 2 squares Δ: peeling was observed in 100 squares 3 to 10 mm x: 100 mm of which peeling was observed exceeded 10 mm

(Preparation of polarizing plate)
About each optical compensation film F1-1 to F1-8 produced above, the back surface (surface on which the alignment film and the optically anisotropic layer are not formed) of the support was saponified. Specifically, it was immersed in a 1.5N sodium hydroxide aqueous solution (55 ° C., 2 minutes) and then washed with water (room temperature, 15 seconds). Further, it was immersed in 0.1N sulfuric acid (30 ° C., 20 seconds) and then washed with water (room temperature, 15 seconds).
Using a polyvinyl alcohol adhesive, the back surface of each optical film subjected to saponification treatment was attached to one surface of the polarizing film with Roll To Roll.
Next, a cellulose triacetate film (TD-80UF: manufactured by Fuji Film Co., Ltd.) having a thickness of 80 μm is subjected to the above saponification treatment, and the surface on the opposite side of the polarizing film is coated with a polyvinyl alcohol adhesive. Affixed with Roll To Roll. In this manner, polarizing plates H1-1 to H1-8 were produced.

(Durability evaluation of polarizing plate)
A pressure-sensitive adhesive was applied to the optically anisotropic layer side of each produced polarizing plate, and a sample attached to a glass plate was produced. The sample was allowed to stand in an atmosphere of 65 ° C. and 95% for 6 hours, and then each sample was magnified 30 times with an actual microscope to observe the presence or absence of cracks, and evaluated according to the following criteria.
(Double-circle): A crack is not recognized at all.
○: If you look closely, you can see slight cracks.
Δ: Fine cracks are observed.
X: A crack is clearly visible.
The evaluation results are shown in Table 1 below.

  From the results shown in Table 1, the polyvinyl alcohol film of the present invention is an alignment film effective for homeotropic alignment of the discotic liquid crystal, and the present invention produced using the polyvinyl alcohol film of the present invention as the alignment film. It can be understood that all of the optical compensation films F1-1 to F1-5 in the embodiment are excellent in water resistance and adhesion, and a polarizing plate having this as a protective film is also excellent in durability.

[Example 2]
Next, an example of an optical compensation film prepared by using the polyvinyl alcohol film of the present invention as an alignment film and hybrid-aligning a discotic liquid crystal and fixing the alignment state to form an optically anisotropic layer will be described. To do.

A single-sided saponified film KF-1 was prepared in the same manner as in Example 1, and each alignment film was formed thereon in the same manner as the optical compensation films F1-2, F1-4, F1-7, and F1-9. After that, the surface was rubbed in the same manner as in Example 1.
(Formation of optically anisotropic layer)
A coating liquid D-2 for optically anisotropic layer having the following composition was prepared.
(Preparation of coating liquid D-2 for optical anisotropy)
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Composition of coating liquid (D-2) containing discotic liquid crystal compound ――――――――――――――――――――――――――――――――――― -
9.1 parts by mass of the above discotic liquid crystal compound (I) Ethylene oxide modified trimethylolpropane acrylate (V # 360, trade name, Osaka Organic Chemical Co., Ltd.) 0.9 parts by mass Cellulose acetate butyrate (CAB551-0.2) 0.2 parts by weight Cellulose acetate butyrate (CAB531-1, trade name, manufactured by Eastman Chemical) 0.05 parts by weight The following fluorine compound (F-1) 1.3 parts by weight Irgacure 907 (trade name, manufactured by Ciba Geigy) 3.0 parts by mass Kayacure DETX (trade name, manufactured by Nippon Kayaku Co., Ltd.) 0.1 parts by mass Methyl ethyl ketone 29.6 parts by mass ――――――――― ―――――――――――――――――――――――――――

The coating liquid D-2 was applied at 5.3 mL / m ² on the rubbing-treated surface of each alignment film, and 115 ° C.
The liquid crystal layer was aged for 90 seconds to align the liquid crystal layer. Subsequently, UV irradiation was performed after the entire coated product reached 80 ° C., the liquid crystal layer was fixed in the alignment state, an optically anisotropic layer was formed, and optical compensation films F2-1 to F2-4 were respectively produced. .
Each optical compensation film was evaluated in the same manner as in Example 1. The results are shown in Table 2 below.
In addition, each of the produced optical compensation films was placed between polarizing plates in a crossed Nicol arrangement, and surface observation was performed. The optically anisotropic layer was free from defects such as schlieren, and the viewing angle could be changed from any direction. It was a uniform film without unevenness. In addition, with a microtome, an ultrathin section of each optical compensation film was cut out so that the direction of the rubbing process was a cross section, and observed while rotating the stage with a polarizing microscope. The direction of extinction in the thickness direction was different. Clearly, it was found to be in a hybrid orientation.

(Production and evaluation of polarizing plate)
In the same manner as in Example 1, polarizing plates H2-1 to H2-4 in which each of the optical compensation films F2-1 to F2-4 was attached as protective films were produced, and in the same manner as in Example 1, polarization was performed. The durability of the plate was evaluated. The evaluation results are shown in Table 2 below.

  From the results of Table 2, the polyvinyl alcohol film of the present invention is useful as an alignment film for hybrid alignment of discotic liquid crystals, and an optical compensation film F2-1 produced using the polyvinyl alcohol film alignment film of the present invention. It can be understood that all of F2-3 are optical compensation films excellent in water resistance and adhesion, and further that polarizing plates having these optical compensation films as protective films are also excellent in durability.

[Example 3]
Next, an example of an optical compensation film prepared by using the polyvinyl alcohol film of the present invention as an alignment film, homeotropic alignment of rod-like liquid crystals, and fixing in the alignment state to form an optically anisotropic layer will be described. To do.

  A single-sided saponified film KF-1 was prepared in the same manner as in Example 1, and each alignment film was formed thereon in the same manner as the optical compensation films F1-2, F1-4, F1-7, and F1-9. After that, the surface was rubbed in the same manner as in Example 1.

(Formation of optically anisotropic layer)
A coating liquid containing a rod-like liquid crystal compound described in JP-A-2006-215092 [0198] to [0200], that is, a coating liquid N-1 having the following composition was prepared.
Composition of coating liquid N-1:
The following rod-shaped liquid crystal compound A 3.8 g
Photopolymerization initiator (Irgacure 907, manufactured by Ciba Geigy) 0.06 g
Sensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.) 0.02g
The following air interface side vertical alignment agent 0.002g
9.2 g of methyl ethyl ketone

The coating liquid N-1 was applied to the rubbing treated surface of each alignment film with a # 4.5 wire bar. This was affixed to a metal frame and heated in a constant temperature bath at 100 ° C. for 2 minutes to align the rod-like liquid crystal compound. Next, UV irradiation was performed at 80 ° C. with a 120 W / cm high-pressure mercury lamp for 20 seconds to crosslink the rod-like liquid crystal compound, and then allowed to cool to room temperature to form an optically anisotropic layer, thereby forming an optical compensation film F3-1. -F3-4 were respectively prepared.
Each optical compensation film F3-1 to F3-4 was evaluated in the same manner as in Example 1. The results are shown in Table 3 below.

(Production and evaluation of polarizing plate)
In the same manner as in Example 1, polarizing plates H3-1 to H3-4 were prepared by attaching the optical compensation films F3-1 to F3-4 as protective films, respectively. The durability of the plate was evaluated. The evaluation results are shown in Table 3 below.

  From the results shown in Table 3, the polyvinyl alcohol film of the present invention is an alignment film useful for homeotropic alignment of rod-like liquid crystals, and an optical compensation film F3- produced using the polyvinyl alcohol film alignment film of the present invention. It can be understood that any of 1 to F3-4 is an optical compensation film excellent in water resistance and adhesion, and a polarizing plate having these optical compensation films as protective films is also excellent in durability.

Claims (19)

A film comprising a composition containing polyvinyl alcohol having a reactive group having active hydrogen in the molecule and a crosslinking agent. The film according to claim 1, wherein the film is a liquid crystal alignment film. The membrane according to claim 1 or 2, wherein the polyvinyl alcohol having a reactive group having active hydrogen in the molecule is acetoacetyl-modified polyvinyl alcohol. The film according to any one of claims 1 to 3, wherein the cross-linking agent is glutaraldehyde. The film according to any one of claims 1 to 4, wherein an average saponification degree of polyvinyl alcohol having a reactive group having active hydrogen in the molecule is 95 mol% or more. The film according to any one of claims 1 to 5, wherein the composition further contains at least one polyvinyl alcohol having a polymerizable group. The film according to claim 6, wherein the average saponification degree of the polyvinyl alcohol having a polymerizable group is 70 to 90 mol%. The film according to any one of claims 1 to 7, comprising polyvinyl alcohol as a main component. The optical film which has a polymer film and the film | membrane of any one of Claims 1-8 on it. The optical film according to claim 9, further comprising an optically anisotropic layer formed from a liquid crystal composition on the film. The optically anisotropic layer is a layer formed by aligning a polymerizable liquid crystal composition containing a liquid crystal compound having a polymerizable group on the film and fixing it in that state. The optical film according to claim 10. The optical film according to claim 11, wherein the film contains at least one polymerizable compound having a polymerizable group of the same type as the polymerizable group of the liquid crystal compound. The optical film according to claim 12, wherein the polymerizable compound is a polyvinyl alcohol. 14. The optical film according to claim 11, wherein the polymerizable group of the polymerizable liquid crystal compound is any one of an unsaturated polymerizable group, an epoxy group, and an aziridinyl group. The optical film according to claim 14, wherein the polymerizable group of the polymerizable liquid crystal compound is an ethylenically unsaturated polymerizable group. The optical film according to claim 9, wherein the polymer film is a film mainly composed of cellulose acylate. The polarizing plate which has a polarizing film and the optical film of any one of Claims 1-16. The polarizing plate according to claim 17, wherein the optical film is a protective film for the polarizing film. A liquid crystal display device comprising the polarizing plate according to claim 17 or 18.