JP2008224761A - Optical compensation film and its manufaucturing method, polarizing plate, and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical compensation film which has high durability when a polarizing plate is manufactured and placed under high humidity and can hold smoothness excellently, to provide its manufacturing method, and to provide the polarizing plate and a liquid crystal display device. <P>SOLUTION: The method for manufacturing the optical compensation film includes: an adhesion application processing process for executing the adhesion application processing process to a support; an orientation film formation process for forming an orientation film by applying a composition for forming the orientation film containing a radical polymerization group on the support surface; a rubbing process for performing rubbing processing to the orientation film and an optical anisotropic layer formation process for forming an optical anisotropic layer on the orientation film; and a pretreatment process for bridging the radical polymerization group before the optical anisotropic layer formation process. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical compensation film, a method for producing the same, a polarizing plate, and a liquid crystal display device.

Optical films in which liquid crystal compounds are highly oriented and fixed are being developed in various applications such as optical compensation films for liquid crystal display devices, brightness enhancement films, and optical correction films for projection display devices. The development of the device as an optical compensation film is remarkable.
Here, the liquid crystal display device mainly includes a polarizing plate and a liquid crystal cell. For example, in a currently used Twisted Nematic mode (TN mode) thin film transistor (TFT) liquid crystal display device, an optical compensation film is used. Is inserted between the polarizing plate and the liquid crystal cell to realize a liquid crystal display device with high display quality. However, this method has a problem that the liquid crystal display device itself becomes thick.

In order to solve the problem that the liquid crystal display device becomes thick, in Patent Document 1, the liquid crystal display device is made thick by using an elliptically polarizing plate having a retardation film on one side of the polarizing film and a protective film on the other side. However, it has been proposed to increase the front contrast. However, the proposed retardation film (optical compensation film) has a problem that a sufficient viewing angle improvement effect cannot be obtained and the display quality of the liquid crystal display device is deteriorated.
Therefore, in order to solve the problem relating to the viewing angle without increasing the thickness of the liquid crystal display device, that is, to prevent deterioration in display quality, in Patent Document 2 and Patent Document 3, a discotic compound is formed on a transparent support. An optical compensation film formed by coating an optically anisotropic layer is proposed as a protective film for a polarizing plate.

However, in these proposals, since an optical compensation film has been developed mainly assuming a small or medium-sized liquid crystal display device of 15 inches or less, a large liquid crystal having a large size of 17 inches or more and high brightness in recent years. Even if it is mounted on a polarizing plate of a display device, there is a problem that it cannot be applied due to unevenness on the panel. For this reason, it is necessary to further develop an optical film that copes with light leakage unevenness in response to an increase in size and brightness.
In order to improve this unevenness, Patent Document 4 proposes that a polymerizable liquid crystal contains a leveling agent. However, this proposal is effective only when the polymerizable liquid crystal has homogeneous alignment, and cannot be applied to complicated alignment including hybrid alignment.

Therefore, as an optical compensation film that can be applied to complicated alignment, a repeating unit derived from a liquid crystal compound, a fluoroaliphatic group-containing (meth) acrylate monomer, and a polyoxyalkylene (meth) acrylate monomer on a support. There has been proposed an optical compensation film having an optically anisotropic layer containing a fluoroaliphatic group-containing copolymer containing (see Patent Document 5).
However, the alignment film bonded to the support through the adhesive layer absorbs moisture as compared with the support and the optically anisotropic layer constituting the optical compensation film disclosed in Patent Documents 1 to 5 above. Therefore, when the optical compensation film is placed under high humidity, the expansion coefficient of the alignment film is higher than that of the support or adhesive layer, and the alignment film is cracked. The display quality of the display device equipped with the optical compensation film may be impaired, and there is room for improvement in improving durability.

  Therefore, the development of an optical compensation film and a method for producing the same, a polarizing plate, and a liquid crystal display device that have high durability when the polarizing plate is prepared and placed under high humidity and can maintain good smoothness is strong. What is desired is the current situation.

JP-A-2-247602 Japanese Patent Laid-Open No. 7-191217 European Patent No. 91656 JP-A-11-148080 JP 2004-198511 A

  An object of the present invention is to solve the conventional problems and achieve the following objects. That is, the present invention provides an optical compensation film that is highly durable when a polarizing plate is prepared and placed under high humidity and that can maintain good smoothness, a manufacturing method thereof, a polarizing plate, and a liquid crystal display device The purpose is to provide.

In order to solve the above-mentioned problems, the present inventors have made extensive studies and as a result, obtained the following findings. That is, in order to improve durability, it is necessary to strengthen the crosslinking reaction, and the crosslinking reaction is performed by heat curing or photocuring.
In this curing step, heat may be applied to the optical compensation film to cause a phenomenon that the shape of the optical compensation film is undulated.
In this way, if the smoothness of the optical compensation film is impaired, the appearance quality as an optical compensation film and, as a result, a problem with durability arises. It is the knowledge that it is required to make it.

This invention is based on the said knowledge by the present inventors, and the means for solving the said subject are as follows. That is,
<1> An alignment film forming step of forming an alignment film by applying a composition for forming an alignment film containing a radical polymerizable group on at least one surface of the support; and a rubbing step of rubbing the alignment film; And an optically anisotropic layer forming step of forming an optically anisotropic layer by applying a coating liquid containing a liquid crystalline compound on the alignment film subjected to the rubbing treatment. And
A method for producing an optical compensation film comprising a pretreatment step of crosslinking the radical polymerizable group before the optical anisotropic layer forming step.
In the method for producing an optical compensation film described in <1>, in the step of forming the optical anisotropic layer, the alignment film radicals are cured before the interface of the alignment film is cured by the ultraviolet rays slightly transmitted from the optical anisotropic layer. Since the polymerizable group is cross-linked, the expansion rate of the alignment film itself decreases, and even when the optical compensation film laminated as a product is placed under high humidity, the alignment film can be prevented from swelling.
<2> The method for producing an optical compensation film according to <1>, wherein the pretreatment step is performed before the rubbing step.
<3> The pretreatment step is the method for producing an optical compensation film according to any one of <1> to <2>, wherein the alignment film is a treatment of irradiating ultraviolet rays in an amount of 60 mJ to 600 mJ.
<4> The method for producing an optical compensation film according to any one of <1> to <3>, wherein the radical polymerizable group is a (meth) acryloyl group.
<5> A polymerization initiator that is radicalized by light is included in the alignment film, and the content of the polymerization initiator is 0.05% by mass to 2.% by mass with respect to the solid content of the polymer compound included in the alignment film. The method for producing an optical compensation film according to any one of <1> to <4>, wherein the content is 0% by mass.
<6> The method for producing an optical compensation film according to any one of <1> to <5>, wherein the alignment film forming composition contains a modified polyvinyl alcohol.
<7> The above-mentioned <1> including an adhesion imparting treatment step of applying a saponification treatment by applying an alkaline solution having a water-soluble organic solvent and at least one of a surfactant and a compatibilizer before the alignment film formation step To <6>. The method for producing an optical compensation film according to any one of <6>.
<8> The method for producing an optical compensation film according to any one of <1> to <7>, wherein the support is a cellulose acylate film.
<9> An optical compensation film produced by the method for producing an optical compensation film according to any one of <1> to <8>.
<10> An alignment film forming step of forming an alignment film by applying a composition for forming an alignment film containing a radical polymerizable group on at least one surface of the support, and a pretreatment step of crosslinking the radical polymerizable group And a rubbing step for rubbing the alignment film, and an optically anisotropic layer for forming an optically anisotropic layer by applying a coating liquid containing a liquid crystalline compound on the alignment film subjected to the rubbing process The optical compensation film according to <9>, which is produced by a forming step.
<11> A polarizing plate comprising the optical compensation film according to any one of <9> to <10> and a polarizer.
<12> A liquid crystal display device comprising the polarizing plate according to <11> and a liquid crystal cell.

  According to the present invention, the above-mentioned problems in the prior art can be solved, and an optical compensation film that has a high durability when a polarizing plate is prepared and placed under high humidity and can maintain good smoothness, and its A manufacturing method, a polarizing plate, and a liquid crystal display device can be provided.

  Hereinafter, the optical compensation film according to the present invention, the production method thereof, the polarizing plate, and the liquid crystal display device will be described in detail.

(Optical compensation film)
The optical compensation film of the present invention is formed by laminating an alignment film layer containing a polymer compound having a radical polymerizable group and an optically anisotropic layer containing a liquid crystal compound in this order on a support.

<Support>
The support is preferably glass or a transparent polymer film, and preferably has a light transmittance of 80% or more.
Examples of the polymer constituting the polymer film include cellulose esters, norbornene polymers, and polymethyl methacrylate. Examples of the cellulose ester include cellulose acetate and cellulose diacetate.
A commercially available polymer may be used as the polymer. Examples of the commercially available polymer include norbornene-based polymers such as Arton and Zeonex (both are trade names).
Among the polymers exemplified above, cellulose ester is preferable, and cellulose lower fatty acid ester is more preferable.
Here, the lower fatty acid means a fatty acid having 6 or less carbon atoms, and is cellulose acetate (2 carbon atoms), cellulose propionate (3 carbon atoms), or cellulose butyrate (4 carbon atoms). Is preferable, and cellulose acetate is more preferable.

Even a conventionally known polymer such as polycarbonate or polysulfone, which easily develops birefringence, can be modified by modifying the molecule as described in, for example, WO '00 / 26705. If the expression of refraction is controlled, it can be used for the optical compensation film of the present invention.
When the optical compensation film of the present invention is used for a polarizing plate protective film or a retardation film, cellulose acetate having an acetylation degree of 55.0 to 62.5% is used as the polymer film of the support. It is preferable to use cellulose acetate that is 57.0 to 62.0%.

Here, the degree of acetylation means the amount of bound acetic acid per unit mass of cellulose, and is determined, for example, by measuring and calculating the degree of acetylation in ASTM: D-817-91 (testing method for cellulose acetate and the like).
The viscosity average degree of polymerization (DP) of cellulose acetate is preferably 250 or more, and more preferably 290 or more. The cellulose acetate preferably has a narrow molecular weight distribution of Mw / Mn (Mw is a mass average molecular weight, Mn is a number average molecular weight) by gel permeation chromatography. Specifically, the value of Mw / Mn is preferably 1.0 to 1.7, more preferably 1.0 to 1.65, and 1.0 to 1.6. Particularly preferred.

In the cellulose acetate, the hydroxyl groups at the 2-position, 3-position and 6-position of cellulose are not evenly substituted, but the substitution degree at the 6-position tends to be small. For this reason, in the polymer film used for this invention, it is preferable that the 6th-position substitution degree of a cellulose is the same or more compared with 2nd-position and 3rd-position.
The ratio of the substitution degree at the 6-position to the total substitution degree at the 2-position, the 3-position, and the 6-position of the cellulose acetate is preferably 30 to 40%, more preferably 31 to 40%, It is especially preferable that it is 32 to 40%. The substitution degree at the 6-position is preferably 0.88 or more. The degree of substitution at each position can be measured by NMR.
Cellulose acetate having a high degree of substitution at the 6-position is, for example, Synthesis Example 1 described in Paragraph Nos. 0043 to 0044, Synthesis Example 2 described in Paragraph Nos. 0048 to 0049 and Paragraph Nos. 0051 to 0052 of JP-A No. 11-5851. It can be synthesized with reference to the method of Synthesis Example 3 described in 1.

<Alignment film layer>
The alignment film (layer) of the present invention contains a polymer compound having a radical polymerizable group. Examples of the radical polymerizable group include acryloyl group, methacryloyl group, styryl group, allyl group, vinylbenzyl group, vinyl ether group, vinylalkylsilyl group, vinylketone group, and isopenyl group. Among these, an acryloyl group and a methacryloyl group are preferable.

  In addition, as the polymer compound, either a polymer that can be crosslinked by itself or a polymer that is crosslinked by a crosslinking agent can be used, and a plurality of combinations thereof can be used. Examples of the polymer include compounds described in paragraph No. [0022] of JP-A-8-338913.

Examples of the polymer compound include polymethyl methacrylate, acrylic acid / methacrylic acid copolymer, styrene / maleimide copolymer, polyvinyl alcohol, and modified polyvinyl alcohol, poly (N-methylolacrylamide), styrene / vinyltoluene. Copolymer, chlorosulfonated polyethylene, nitrocellulose, polyvinyl chloride, chlorinated polyolefin, polyester, polyimide, vinyl acetate / vinyl chloride copolymer, ethylene / vinyl acetate copolymer, carboxymethyl cellulose, polyethylene, polypropylene, polycarbonate, etc. And polymers such as silane coupling agents.
Among the above polymer compounds, water-soluble polymers such as poly (N-methylolacrylamide), carboxymethylcellulose, gelatin, polyvinyl alcohol, and modified polyvinyl alcohol described later are preferable, and gelatin, polyvinyl alcohol, and modified Polyvinyl alcohol is more preferred, polyville alcohol is more preferred, and modified polyvinyl alcohol is particularly preferred.

Specific examples of the polymer compound having a radical polymerizable group include those described in paragraphs [0071] to [0095] of JP-A-9-152509, and among these, paragraph numbers of the same publication The modified polyvinyl alcohol represented by the following general formula (I) described in [0072] is preferable.

[Polymerization initiator]
The alignment film preferably contains a polymerization initiator that is radicalized by light in order to promote a polymerization reaction of a reactive group (for example, a (meth) acryloyl group) included in the alignment film.
The polymerization initiator is preferably contained in a proportion of 0.05% by mass or more and less than 1% by mass with respect to the solid content of the polymer compound of the alignment film, and is preferably 0.25% by mass or more, More preferably, it is contained in a proportion of less than 1% by weight, more preferably 0.5% by weight or more and less than 1% by weight, more preferably 0.75% by weight or more and less than 1% by weight It is particularly preferable that it is contained in a proportion. When the content of the polymerization initiator is less than 0.05% by mass, the durability crack is deteriorated, and when it is 1% by mass or more, orientation failure occurs.
As a polymerization initiator, the compound shown by the following general formula (II) is mentioned, for example, Among these, Irgacure 2959 is preferable.
The polymerization initiator may be incorporated into the alignment film by crosslinking with the polymer or may be included as a molecule as it is.

―Saponification degree―
As the polyvinyl alcohol and the modified polyvinyl alcohol, for example, the saponification degree is preferably 70 to 100%, the saponification degree is more preferably 80 to 100%, and the saponification degree is 85 to 95%. Particularly preferred. The degree of polymerization is preferably in the range of 100 to 3,000.

  The modifying group of the modified polyvinyl alcohol can be introduced by copolymerization modification, chain transfer modification or block polymerization modification. Examples of modifying groups include hydrophilic groups (carboxy groups, sulfo groups, phosphono groups, amino groups, ammonium groups, amide groups, mercapto groups, etc.), hydrocarbon groups having 10 to 100 carbon atoms, and carbon atoms substituted with fluorine atoms. Examples thereof include a hydrogen group, sulfide group, polymerizable group (unsaturated polymerizable group, epoxy group, aziridinyl group, etc.), alkoxysilyl group (trialkoxy, dialkoxy, monoalkoxy) and the like. Specific examples of these modified polyvinyl alcohol compounds include, for example, paragraph numbers [0071] to [0095] of JP-A-9-152509, paragraph number [0074] of JP-A 2000-56310, 2000-155216. Examples include the compounds described in paragraph numbers [0022] to [0145] of the publication and paragraph numbers [0018] to [0022] of the publication 2002-62426.

  Moreover, when performing alignment by light irradiation, it is necessary to have a photo-alignment group which expresses a photo-alignment function in the molecule. Examples of these photo-alignment groups include “Liquid Crystal” written by Masaki Hasegawa, Volume 3 (1) p. 3-16 (1999), a photo-alignment group having a C = C bond and exhibiting a photo-alignment function by a photodimerization reaction (for example, polyene group, stilbene group, stilbazole group, stilbazolium group, cinnamoyl group) , Hemithioindigo group, chalcone group, and the like) and photo-alignable groups having a C═O bond and exhibiting a photo-alignment function by a photodimerization reaction (for example, groups having a structure such as a benzophenone group and a coumarin group). Specific examples include those described in paragraphs [0021] and the like of JP-A Nos. 2000-122069 and 2002-317013.

―Crosslinking agent―
Examples of cross-linking agents for polymers (preferably water-soluble polymers, more preferably polyvinyl alcohol or modified polyvinyl alcohol) used in the alignment film include aldehydes, N-methylol compounds, dioxane derivatives, and carboxy groups by activating them. Compounds that act, active vinyl compounds, active halogen compounds, isoxazoles and dialdehyde starches are included. Two or more kinds of crosslinking agents may be used in combination. Specific examples include compounds described in paragraph numbers [0023] to [0024] of JP-A No. 2002-62426. Aldehydes having high reaction activity, particularly glutaraldehyde are preferred.

―Amount of crosslinking agent added―
0.1-20 mass% is preferable with respect to a polymer, and, as for the addition amount of the said crosslinking agent, 0.5-15 mass% is still more preferable. The amount of the unreacted crosslinking agent remaining in the alignment film is preferably 1.0% by mass or less, and more preferably 0.5% by mass or less. If the remaining amount of the crosslinking agent in the alignment film is not more than the upper limit, it is preferable because sufficient durability can be obtained. When such an alignment film is used in a liquid crystal display device, it is preferable that reticulation does not occur even when used for a long time or when left in a high temperature and high humidity atmosphere for a long time.

-Carboxylic acid compound-
The alignment film-forming composition in the present invention preferably contains a specific carboxylic acid compound. Thereby, after aligning the formed alignment film by an aligning means, the coated surface shape of the optical compensation sheet obtained by coating the optically anisotropic layer is good, reducing optical defects such as white spots, Or the improvement effect which eliminates is expressed.
This is because the specific carboxylic acid compound contained in the alignment film has an effect on the alignment state of the liquid crystal molecules when the film surface hydrogen ion concentration of the alignment film is stabilized and the optically anisotropic layer is applied. It is presumed that one of the factors is to reduce the size.
In addition, when the surface of the transparent support is hydrophilized by alkali saponification treatment, an alignment film with good optical performance can be stably formed even if there is a slight residual treatment solution on the film surface. It is. At this time, since the effect varies depending on the amount added, it is necessary to adjust the amount appropriately. Specific examples of the specific carboxylic acid compound include those described in paragraph numbers [0162] to [0176] of JP-A-2005-115341.

  The alignment film is basically formed by applying a coating solution containing the polymer, a crosslinking agent, and a specific carboxylic acid, which is a composition for forming an alignment film, onto a transparent support, followed by drying by heating (crosslinking). It is a cured film that can be formed by orientation treatment. That is, the alignment film is preferably a cured film obtained by applying an alignment film forming composition containing polyvinyl alcohol and / or modified polyvinyl alcohol as a main component and drying. The cross-linking reaction may be performed at any time after coating on the transparent support.

  When a water-soluble polymer such as polyvinyl alcohol is used as the composition for forming an alignment film, the coating solution should be a mixed solvent of an organic solvent (for example, methanol, ethanol, isopropanol, etc.) having a defoaming action and water. preferable. The ratio of water: organic solvent (for example, methanol) is preferably 0: 100 to 99: 1, and more preferably 0: 100 to 91: 9 in terms of mass ratio. Thereby, generation | occurrence | production of a bubble is suppressed and the defect of the layer surface of an orientation film and also an optically anisotropic layer reduces remarkably.

The alignment film can be obtained by rubbing the surface after crosslinking the polymer layer as described above.
For the rubbing treatment, a treatment method widely adopted as a liquid crystal alignment treatment process of a liquid crystal display device can be applied. That is, a method is used in which the orientation is obtained by rubbing the surface of the orientation film in a certain direction using paper, gauze, felt, rubber, nylon, polyester fiber or the like. In general, it is carried out by rubbing several times using a cloth in which fibers having a uniform length and thickness are flocked on average.

In the case of photo-alignment by light irradiation, the light source as the light irradiation device can be an ultra-high pressure mercury lamp, a xenon lamp, a fluorescent lamp, a laser, or the like. A light source and a polarizing film are combined (through the polarizing film) to convert the ultraviolet light into linearly polarized light and irradiate the photo alignment film.
As the polarizing film, stretched dyeing PVA (polyvinyl alcohol) is mainly used. Examples of the linearly polarized ultraviolet irradiation device include those disclosed in JP-A-10-90684.
The thickness of the alignment film is preferably 0.01 to 5 μm, and more preferably 0.05 μm to 1 μm.

<Optically anisotropic layer>
The optically anisotropic layer is preferably designed so as to compensate for the liquid crystal compound in the liquid crystal cell in the black display of the liquid crystal display device. The alignment state of the liquid crystal compound in the liquid crystal cell in black display varies depending on the mode of the liquid crystal display device. Regarding the alignment state of the liquid crystal compound in this liquid crystal cell, IDW'00, FMC7-2, P.I. 411-414.

The optically anisotropic layer is formed from liquid crystalline molecules through the alignment film. The liquid crystalline molecules used in the optically anisotropic layer include rod-like liquid crystalline molecules and discotic compounds.
The rod-like liquid crystalline molecules and discotic compounds may be high molecular liquid crystals or low molecular liquid crystals, and further include those in which the low molecular liquid crystals are crosslinked and no longer exhibit liquid crystallinity.
The optically anisotropic layer can be formed by applying a coating liquid containing liquid crystalline molecules, if necessary, a polymerizable initiator and other components on the alignment film.

[Bar-shaped liquid crystal compound]
Examples of the rod-shaped liquid crystal compound that can be used in the present invention include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, Alkoxy-substituted phenylpyrimidines, phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used.
The rod-like liquid crystal compound includes a metal complex. A liquid crystal polymer containing a rod-like liquid crystal compound in a repeating unit can also be used. In other words, the rod-like liquid crystal compound may be bonded to a (liquid crystal) polymer.
For rod-shaped liquid crystal compounds, Chapter 4, Chapter 7, and Chapter 11 of Quarterly Chemical Review Vol. 22 “Chemicals of Liquid Crystals (1994), Chemical Society of Japan” and the 142nd Committee of the Japan Society for the Promotion of Science It is described in Chapter 3 of the volume.

The birefringence of the rod-like liquid crystal compound used in the present invention is preferably in the range of 0.001 to 0.7.
The rod-like liquid crystal compound preferably has a polymerizable group in order to fix its alignment state. The polymerizable group is preferably an unsaturated polymerizable group or an epoxy group, more preferably an unsaturated polymerizable group, and particularly preferably an ethylenically unsaturated polymerizable group.

[Discotic liquid crystal compound]
Examples of discotic liquid crystal compounds include C.I. Destrade et al., Mol. Cryst. 71, 111 (1981), benzene derivatives described in C.I. Destrade et al., Mol. Cryst. 122, 141 (1985), Physics lett, A, 78, 82 (1990); Kohne et al., Angew. Chem. 96, 70 (1984) and the cyclohexane derivatives described in J. Am. M.M. Lehn et al. Chem. Commun. , 1794 (1985), J. Am. Zhang et al., J. Am. Chem. Soc. 116, 2655 (1994), azacrown type and phenylacetylene type macrocycles are included.

The discotic liquid crystal compound exhibits liquid crystallinity with a structure in which a linear alkyl group, an alkoxy group, or a substituted benzoyloxy group is radially substituted as a side chain of the mother nucleus with respect to the mother nucleus at the center of the molecule. Also included are compounds. The molecule or the assembly of molecules is preferably a compound having rotational symmetry and imparting a certain orientation.
When an optically anisotropic layer is formed from a discotic liquid crystal compound, the compound finally contained in the optically anisotropic layer no longer needs to exhibit liquid crystallinity.
For example, a low-molecular discotic liquid crystal compound has a group that reacts with heat or light, and the group reacts with heat or light to polymerize or crosslink to increase the molecular weight. When a layer is formed, the compound contained in the optically anisotropic layer may no longer have liquid crystallinity.
Preferred examples of the discotic liquid crystal compound are described in JP-A-8-50206. The polymerization of discotic liquid crystal compounds is described in JP-A-8-27284.

In order to fix the discotic liquid crystal compound by polymerization, it is necessary to bond a polymerizable group as a substituent to the discotic core of the discotic liquid crystal compound. However, when the polymerizable group is directly connected to the disc-shaped core, it becomes difficult to maintain the orientation state in the polymerization reaction. Therefore, a linking group is introduced between the discotic core and the polymerizable group.
Therefore, the discotic liquid crystal compound having a polymerizable group is preferably a compound represented by the following general formula (III).

In the general formula (III), D is a discotic core, L is a divalent linking group, Q is a polymerizable group, and n is an integer of 4 to 12.

  As examples of the disk-shaped core (D), (D1) to (D15) are shown below. In each of the following examples, LQ (or QL) means a combination of a divalent linking group (L) and a polymerizable group (Q).

In the general formula (III), the divalent linking group (L) is composed of an alkylene group, an alkenylene group, an arylene group, —CO—, —NH—, —O—, —S—, and combinations thereof. A divalent linking group selected from the group is preferred.
The divalent linking group (L) is a divalent group in which at least two divalent groups selected from the group consisting of an alkylene group, an arylene group, —CO—, —NH—, —O—, and —S— are combined. More preferably, it is a linking group.
The divalent linking group (L) is particularly preferably a divalent linking group in which at least two divalent groups selected from the group consisting of an alkylene group, an arylene group, -CO- and -O- are combined. .
The alkylene group preferably has 1 to 12 carbon atoms. The alkenylene group preferably has 2 to 12 carbon atoms. The arylene group preferably has 6 to 10 carbon atoms.

  As examples of the divalent linking group (L), (L1 to L24) are shown below. The left side is bonded to the discotic core (D), and the right side is bonded to the polymerizable group (Q). AL represents an alkylene group or an alkenylene group, and AR represents an arylene group. The alkylene group, alkenylene group and arylene group may have a substituent (eg, an alkyl group).

L1: -AL-CO-O-AL-
L2: -AL-CO-O-AL-O-
L3: -AL-CO-O-AL-O-AL-
L4: -AL-CO-O-AL-O-CO-
L5: -CO-AR-O-AL-
L6: -CO-AR-O-AL-O-
L7: -CO-AR-O-AL-O-CO-
L8: -CO-NH-AL-
L9: -NH-AL-O-
L10: -NH-AL-O-CO-

L11: -O-AL-
L12: -O-AL-O-
L13: -O-AL-O-CO-
L14: -O-AL-O-CO-NH-AL-
L15: -O-AL-S-AL-
L16: -O-CO-AL-AR-O-AL-O-CO-
L17: -O-CO-AR-O-AL-CO-
L18: -O-CO-AR-O-AL-O-CO-
L19: -O-CO-AR-O-AL-O-AL-O-CO-
L20: -O-CO-AR-O-AL-O-AL-O-AL-O-CO-
L21: -S-AL-
L22: -S-AL-O-
L23: -S-AL-O-CO-
L24: -S-AL-S-AL-
L25: -S-AR-AL-

  The polymerizable group (Q) of the general formula (III) is determined according to the type of polymerization reaction. Examples of the polymerizable group (Q) are shown below.

  The polymerizable group (Q) of the general formula (III) is preferably an unsaturated polymerizable group (Q1, Q2, Q3, Q7, Q8, Q15, Q16, Q17) or an epoxy group (Q6, Q18). The unsaturated polymerizable group is more preferably an ethylenically unsaturated polymerizable group (Q1, Q7, Q8, Q15, Q16, Q17). A specific value of n is determined according to the type of the disk-shaped core (D). In addition, although the combination of several L and Q may differ, it is preferable that it is the same.

In the hybrid orientation, the angle between the major axis (disk surface) of the discotic compound and the surface of the support, that is, the tilt angle, increases in the depth direction of the optically anisotropic layer and increases with increasing distance from the surface of the polarizing film. Or it is decreasing. The angle preferably decreases with increasing distance.
Examples of the change in the inclination angle include a continuous increase, a continuous decrease, an intermittent increase, an intermittent decrease, a change including a continuous increase and a continuous decrease, or an intermittent change including an increase and a decrease. . The intermittent change includes a region where the inclination angle does not change in the middle of the thickness direction. Even if such a region where the angle does not change is included, it may be increased or decreased as a whole. However, it is preferable that the inclination angle changes continuously.

The average direction of the major axis (disk surface) of the discotic compound (average of the major axis direction of each molecule) is generally determined by selecting the discotic compound or the material of the alignment film, or by selecting the rubbing treatment method. Can be adjusted.
The major axis (disk surface) direction of the discotic compound on the surface side (air side) can generally be adjusted by selecting the discotic compound or the type of additive used together with the discotic compound.
Examples of the additive used together with the discotic compound include a plasticizer, a surfactant, a polymerizable monomer, and a polymer.
The degree of change in the orientation direction of the major axis can be adjusted by selecting liquid crystal molecules and additives as described above.

The plasticizer, surfactant and polymerizable monomer used together with the discotic compound are preferably compatible with the discotic compound and can change the tilt angle of the discotic compound or do not inhibit the orientation. . Therefore, a polymerizable monomer is preferable among these additive components.
Examples of the polymerizable monomer include compounds having a vinyl group, a vinyloxy group, an acryloyl group, or a methacryloyl group.
The addition amount of these additive components is usually 1 to 50% by mass and preferably 5 to 30% by mass with respect to the discotic compound. In addition, when a monomer having 4 or more polymerizable reactive functional groups is mixed and used, adhesion between the alignment film and the optically anisotropic layer can be improved.

The optically anisotropic layer may contain a polymer together with the discotic compound. Such a polymer preferably has a certain degree of compatibility with the discotic compound and can change the tilt angle of the discotic compound.
Examples of the polymer include cellulose esters. Preferable examples of the cellulose ester include cellulose acetate, cellulose acetate propionate, hydroxypropyl cellulose, cellulose acetate butyrate and the like.
The addition amount of the polymer is preferably 0.1 to 10% by mass, more preferably 0.1 to 8% by mass, more preferably 0.1 to 5% by mass with respect to the discotic compound so as not to inhibit the orientation of the discotic compound. Mass% is particularly preferred.
The discotic nematic liquid crystal phase-solid phase transition temperature of the discotic compound is preferably 70 to 300 ° C, more preferably 70 to 170 ° C.

[Fixing the alignment state of liquid crystalline molecules]
The aligned liquid crystal molecules can be fixed while maintaining the alignment state. The immobilization is preferably performed by a polymerization reaction. This polymerization reaction includes a thermal polymerization reaction using a thermal polymerization initiator and a photopolymerization reaction using a photopolymerization initiator, and a photopolymerization reaction is preferred.
Examples of the photopolymerization initiator include α-carbonyl compounds described in US Pat. Nos. 2,367,661 and 2,367,670, acyloin ethers described in US Pat. No. 2,448,828, and US Pat. Α-hydrocarbon substituted aromatic acyloin compounds described in US Pat. Nos. 3,056,127, and polynuclear quinone compounds described in US Pat. Nos. 2,951,758 and US Pat. No. 3,549,367. Combinations of triarylimidazole dimer and p-aminophenyl ketone, acridine compounds and phenazine compounds described in JP-A-60-105667, US Pat. No. 4,239,850, and US Pat. No. 4,221,970 Oxadiazole compound Such as things.

The amount of the photopolymerization initiator used is preferably 0.01% by mass to 20% by mass, more preferably 0.5% by mass to 5% by mass, based on the solid content of the coating solution.
The light irradiation for the polymerization of the liquid crystalline molecules preferably uses ultraviolet rays. Its radiation energy is ^preferably in the range of ^{20mJ / cm 2 ~50J / cm 2} , more preferably in the range of ^{20mJ / cm 2 ~5,000mJ / cm 2} , 100mJ / cm 2 ~800mJ / cm More preferably, it is in the range of ² . In order to accelerate the photopolymerization reaction, light irradiation may be performed under heating conditions.

The optically anisotropic layer is prepared by preparing a coating solution containing at least one of the liquid crystalline compounds and, optionally, an additive such as a polymerizable initiator and a fluorine-based polymer, and applying the coating solution to the alignment film surface. It is formed by drying.
Examples of the fluorine compound include conventionally known compounds, and specific examples include the fluorine compounds described in paragraph numbers [0028] to [0056] of JP-A No. 2001-330725.

As the solvent used for preparing the coating solution, an organic solvent is preferably used. Examples of the organic solvent include amides (eg, N, N-dimethylformamide), sulfoxides (eg, dimethyl sulfoxide), heterocyclic compounds (eg, pyridine), hydrocarbons (eg, benzene, hexane), alkyl halides ( Examples include chloroform (dichloromethane, tetrachloroethane), esters (eg, methyl acetate, butyl acetate), ketones (eg, acetone, methyl ethyl ketone), and ethers (eg, tetrahydrofuran, 1,2-dimethoxyethane). Among these, alkyl halides and ketones are preferable. What are these organic solvents? You may use individually by 1 type and may use 2 or more types together.
When producing an optical compensation film having very high uniformity as in the present invention, the surface tension is preferably 25 mN / m or less, and more preferably 22 mN / m or less.
The coating solution can be applied by a known method, and examples thereof include a wire bar coating method, an extrusion coating method, a direct gravure coating method, a reverse gravure coating method, and a die coating method.
The thickness of the optically anisotropic layer is preferably 0.1 μm to 20 μm, more preferably 0.5 μm to 15 μm, and still more preferably 1 μm to 10 μm. The optically anisotropic layer may be provided with a protective layer thereon.

(Method for producing optical compensation film)
Next, a method for continuously producing a preferable optical compensation film of the present invention will be described.
In the method for producing an optical compensation film of the present invention, for example, the following steps (1) to (7) are continuously performed.
(1) Support forming step (2) Adhesion imparting treatment step (3) Alignment film forming step (4) Pretreatment step (5) Rubbing step (6) Optical anisotropic layer forming step (6a) Optical anisotropy Layer coating step (6b) Drying step (6c) Optically anisotropic layer fixing step (7) Winding step

In the present invention, the alignment film formed on the support surface in the “alignment film forming step” is irradiated with ultraviolet rays to the alignment film before the “optically anisotropic layer coating step”, A “pretreatment step” for crosslinking radical polymerizable groups contained in the alignment film is included.
The time when this “pretreatment step” is performed may be before the “optically anisotropic layer coating step” after the alignment layer is formed on the support surface in the “alignment layer formation step”. It is more preferable if it is before the “rubbing step”.

  Hereinafter, each process will be described in detail with reference to the drawings.

(1) Support Forming Step In the present invention, it is preferable to produce a cellulose acylate film (support) by a solvent cast method, and the film is produced using a solution (dope) in which cellulose acylate is dissolved in an organic solvent. The
As an organic solvent used for the manufacturing method of a support body, a conventionally well-known organic solvent is mentioned, For example, the thing of the range of 17-22 by a solubility parameter is preferable. Solubility parameters are described in, for example, J. Brandrup, E.I. “Polymer Handbook (4th. Edition)” such as H and the like described in VII / 671 to VII / 714.
Such organic solvents include lower aliphatic hydrocarbon chlorides, lower aliphatic alcohols, ketones having 3 to 12 carbon atoms, esters having 3 to 12 carbon atoms, ethers having 3 to 12 carbon atoms, carbon Examples thereof include aliphatic hydrocarbons having 5 to 8 atoms and aromatic hydrocarbons having 6 to 12 carbon atoms.
The ether, ketone and ester may have a cyclic structure. A compound having two or more functional groups of ether, ketone, and ester (that is, —O—, —CO—, and COO—) can also be used as the organic solvent.
The organic solvent may have another functional group such as an alcoholic hydroxyl group. In the case of an organic solvent having two or more types of functional groups, the number of carbon atoms may be within the specified range of the compound having any functional group.
Specifically, for example, detailed compounds can be mentioned on pages 12 to 16 of the aforementioned technical number 2001-1745.

In particular, in the present invention, the solvent is preferably a mixture of two or more organic solvents, and is a mixed solvent of three or more different from each other, wherein the first solvent is a ketone having 3 to 4 carbon atoms. And an ester having 3 to 4 carbon atoms or a mixture thereof, and the second solvent is selected from ketones having 5 to 7 carbon atoms, or acetoacetate, and the boiling point is 30 as the third solvent. It is particularly preferred to be selected from alcohols of ~ 170 ° C or hydrocarbons having a boiling point of 30 to 170 ° C.
In particular, it is preferable from the viewpoint of solubility of cellulose acetate to use 20 to 90% by mass of acetate, 5 to 60% by mass of ketones, and 5 to 30% by mass of alcohols.

In addition to the above organic solvents, the dope used in the present invention may contain fluoroalcohols in an amount of 10% by mass or less, more preferably 5% by mass or less of the total organic solvent amount of the present invention, thereby improving the transparency of the film. Or in order to accelerate the solubility.
As fluoroalcohols, those having a boiling point of 165 ° C. or less are preferable, preferably 111 ° C. or less, and more preferably 80 ° C. or less. The fluoroalcohols preferably have about 2 to 10 carbon atoms, more preferably about 2 to 8. The fluoroalcohols are fluorine atom-containing aliphatic alcohols that may or may not have a substituent. The substituent is preferably an aliphatic substituent or an aromatic substituent containing or not containing a fluorine atom.

  Examples of the fluoroalcohols include compounds described in paragraph No. [0020] of JP-A-8-143709, paragraph No. [0037] of JP-A-11-60807, and the like. These fluoroalcohols may be used alone or in combination.

Further, non-halogen organic solvent systems that do not contain halogenated hydrocarbons are particularly preferred.
Technically, halogenated hydrocarbons such as methylene chloride can be used without problems, but from the viewpoint of the global environment and working environment, it is preferable that the organic solvent is substantially free of halogenated hydrocarbons.
Here, “substantially free” means that the proportion of halogenated hydrocarbon in the organic solvent is less than 5% by mass (preferably less than 2% by mass). Moreover, it is preferable that halogenated hydrocarbons such as methylene chloride are not detected at all from the produced cellulose acetate film.

  Specifically, the organic solvent used in the present invention is described, for example, in paragraph numbers [0021] to [0025] of JP-A No. 2002-146043, paragraph numbers [0016] to [0021] of JP-A No. 2002-146045, and the like. Examples of the solvent system are as follows.

  When preparing the cellulose acylate solution of the present invention, the container may be filled with an inert gas such as nitrogen gas. The viscosity of the cellulose triacetate solution immediately before film formation may be within a range that allows casting, and is usually adjusted to a range of 10 to 2,000 Pa · s, preferably 30 to 400 Pa · s. More preferred.

  Regarding the preparation of the cellulose acylate solution (dope) according to the present invention, the dissolution method is not particularly limited, and may be a room temperature dissolution method, a cooling dissolution method or a high temperature dissolution method, or a combination thereof. Regarding these, for example, JP-A-5-163301, JP-A-61-106628, JP-A-58-127737, JP-A-9-95544, JP-A-10-95854, JP-A-10-45950, JP 2000-53784, JP 11-322946, JP 11-322947, JP 2-276830, JP 2000-273239, JP 11-71463, JP 04-259511, Special Examples include methods for preparing cellulose acylate solutions described in JP 2000-273184 A, JP 11-323017 A, JP 11-302388 A, and the like. The above-described method for dissolving cellulose acylate in an organic solvent can appropriately apply these techniques also in the present invention. Further, the dope solution of cellulose acylate is usually concentrated and filtered, and similarly described in detail on page 25 of the aforementioned technical number 2001-1745. In addition, when it melt | dissolves at high temperature, it is the case where it is more than the boiling point of the organic solvent to be used, and in that case, it uses in a pressurized state.

Next, in the present invention, a method for producing a film using a cellulose acylate solution will be described. As a method and equipment for producing a cellulose acylate film, a conventionally known solution casting film forming method and solution casting film forming apparatus called a drum method or a band method used for producing a cellulose triacetate film are used.
The film forming process will be described by taking the band method as an example. The dope (cellulose acylate solution) prepared from the dissolving machine (kettle) is temporarily stored in a storage kettle, and the bubbles contained in the dope are defoamed to finish. Prepare.
The prepared dope is fed from the dope discharge port to the pressure die through a pressure metering gear pump capable of delivering a constant amount of liquid with high accuracy, for example, by the rotational speed, and the dope is run endlessly from the die (slit) of the pressure die. The dope film (also referred to as a web) is peeled off from the metal support at the peeling point where the metal support is almost cast around the metal support. Both ends of the obtained web are sandwiched between clips, transported by a tenter while keeping the width, dried, then transported by a roll group of a drying device, dried, and wound up to a predetermined length by a winder.
The combination of the tenter and the roll group dryer varies depending on the purpose. Each of these manufacturing steps (casting (including co-casting), metal support, drying, peeling, stretching, etc.) is described in detail on pages 25 to 30 of the aforementioned technical number 2001-1745. Content.
In the casting step, one type of cellulose acylate solution may be cast as a single layer, or two or more types of cellulose acylate solutions may be cast simultaneously and / or sequentially.

  Furthermore, the cellulose acylate solution of the present invention can be cast simultaneously with other functional layers (for example, an adhesive layer, a dye layer, an antistatic layer, an antihalation layer, a UV absorbing layer, a polarizing layer).

  In the conventional single-layer liquid, it is necessary to extrude a cellulose acylate solution having a high concentration and a high viscosity in order to obtain a required film thickness. In many cases, a problem occurred due to the occurrence of an object, a fault, or poor flatness. As a solution to this, by casting a plurality of cellulose acylate solutions from the casting port, it is possible to extrude a highly viscous solution onto the support at the same time, producing a flat film with improved flatness. Not only can this be achieved, but the use of a concentrated cellulose acylate solution can achieve a reduction in drying load and increase the production speed of the film.

(2) Adhesion imparting treatment process When the support of the present invention is provided with an alignment film by a coating method, the support is imparted to the surface of the support so that the alignment film coating solution is uniformly applied. It is preferable to subject the surface to a surface treatment.
Examples of the surface treatment method include a method of providing an undercoat layer of the alignment film. A single-layer method in which only one layer of an undercoat layer described in JP-A-7-333433 or a resin layer such as gelatin containing both a hydrophobic group and a hydrophilic group is applied, and the first layer is well adhered to a polymer film A layer (hereinafter abbreviated as the undercoat first layer) is applied, and a hydrophilic resin layer such as gelatin (hereinafter abbreviated as the undercoat second layer) is applied thereon as the second layer. The contents of the multilayer method (for example, described in JP-A No. 11-248940) can be mentioned.
Examples of other surface treatment include a method of modifying the film surface by corona discharge treatment, glow discharge treatment, ultraviolet irradiation treatment, flame treatment, ozone treatment, acid treatment, alkali treatment, and the like. Details of these are described in detail on pages 30 to 32 of the above-mentioned public technical number 2001-1745. Among these, alkali saponification treatment is particularly preferable, and it is extremely effective as the surface treatment of the cellulose acetate film.

[Alkaline saponification]
The alkali saponification treatment is performed by immersing, spraying or coating an alkali solution on a support. Preferably, a saponification treatment is preferably performed by application described later.

[Alkaline solution]
The alkaline solution is preferably an alkaline solution having a pH of 11 or more, and more preferably an alkaline solution having a pH of 12 to 14.
Examples of the alkaline agent used in the alkaline solution include inorganic alkaline agents such as sodium hydroxide, potassium and lithium, diethanolamine, triethanolamine, DBU (1,8-diazabicyclo [5,4,0]- 7-undecene), DBN (1,5-diazabicyclo [4,3,0] -5-nonene), tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, triethylbutyl Organic alkali agents such as ammonium hydroxide are also used. These alkali agents can be used alone or in combination of two or more, and a part of them may be added, for example, in the form of a halogenated salt.
Among these alkali agents, sodium hydroxide or potassium hydroxide is preferable because the pH can be adjusted in a wide pH range by adjusting these amounts.

  The concentration of the alkaline solution is determined according to the type of alkaline agent used, the reaction temperature and the reaction time. The content of the alkaline agent is preferably 0.1 to 5 mol / Kg in the alkaline solution, 0.5 -3 mol / Kg is more preferable.

The solvent of the alkaline solution of the present invention is preferably composed of a mixed solution of water and a water-soluble organic solvent. As the organic solvent, any organic solvent miscible with water can be used, but those having a boiling point of 120 ° C. or lower, more preferably 100 ° C. or lower are preferable.
Among them, preferred organic solvents are those having an inorganic / organic value (I / O value) of 0.5 or more and a solubility parameter in the range of 16 to 40 [mJ / m ³ ] ^1/2. An O value of 0.6 to 10 and a solubility parameter of 18 to 31 [mJ / m ³ ] ^1/2 are more preferable. When the I / O value and the solubility parameter are within this range, the alkali saponification rate is appropriate, the uniformity of the entire surface of the saponification degree is sufficient, and haze does not occur.
In addition, when an organic solvent, particularly an organic solvent in each of the above-mentioned organic and soluble ranges, is used in combination with a surfactant, a compatibilizing agent, etc. described later, a high saponification rate is maintained and the saponification degree over the entire surface is maintained. It is preferable because the uniformity is improved.

  Examples of the organic solvent having preferable characteristic values include those described in “Synthetic Organic Chemistry Association”, “New Edition Solvent Pocket Book” (Ohm Co., Ltd., published in 1994) and the like. The inorganic / organic value (I / O value) of the organic solvent is described, for example, in Yoshio Tanaka “Organic Conceptual Diagram” (Sankyo Publishing Co., Ltd., 1983, pages 1-31).

  Specifically, monohydric aliphatic alcohols (eg, methanol, ethanol, propanol, butanol, pentanol, hexanol, etc.), alicyclic alkanols (eg, cyclohexanol, methylcyclohexanol, methoxycyclohexanol, cyclohexylmethanol, Cyclohexylethanol, cyclohexylpropanol, etc.), phenylalkanols (eg, benzyl alcohol, phenylethanol, phenylpropanol, phenoxyethanol, methoxybenzyl alcohol, benzyloxyethanol, etc.), heterocyclic alkanols (furfuryl alcohol, tetrahydrofurfuryl alcohol) Etc.), monoethers of glycol compounds (methyl cellosolve, ethyl cellosolve, propyl cellosolve, methoxymethoxyethane) Butyl cell sorb, hexyl cell sorb, methyl carbitol, ethyl carbitol, propyl carbitol, butyl carbitol, methoxy triglycol, ethoxy triglycol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl Ethers, etc.) ketones (eg, acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.), amides (eg, N, N-dimethylformamide, dimethylformamide, N-methyl-2-pyrrolidone, 1,3-dimethylimidazolidinone, etc. ), Sulfoxides (eg, dimethyl sulfoxide) and ethers (eg, tetrahydrofuran, pyran, dioxane, trioxane, dimethyl cellosolve, diethyl cellosolve, dipro) Ruserusorubu, methyl ethyl cellosolve, dimethyl carbitol, dimethyl carbitol, methyl ethyl carbitol, etc.) and the like. The organic solvent to be used may be used alone or in combination of two or more.

When the organic solvent is used alone or when two or more organic solvents are mixed, it is preferable that at least one organic solvent has high solubility in water. The solubility of water in the organic solvent is preferably 50% by mass or more, and more preferably freely mixed with water. Thereby, an alkali solution having sufficient solubility in an alkali agent, a salt of a fatty acid by-produced by a saponification treatment, a salt of carbonic acid generated by absorbing carbon dioxide in the air, and the like can be prepared.
The use ratio of the organic solvent in the solvent is determined according to the type of the solvent, the miscibility (solubility) with water, the reaction temperature and the reaction time.
The mixing ratio of water and organic solvent is preferably 3/97 to 85/15 mass ratio. More preferably, it is 5 / 95-60 / 40 mass ratio, More preferably, it is 15 / 85-40 / 60 mass ratio. Within this range, the entire surface of the film is easily and uniformly saponified without impairing the optical properties of the cellulose acylate film, which is preferable.

  As the organic solvent contained in the alkaline solution used in the present invention, an organic solvent (for example, fluorinated alcohol) different from the organic solvent having the above-mentioned preferable I / O value is used as a dissolution aid for the surfactant and compatibilizer described later. You may use together as an agent. The content is preferably 0.1 to 5% with respect to the total mass of the liquid used.

  The alkaline solution used in the present invention preferably contains a surfactant. By adding a surfactant, the surface tension can be lowered to facilitate coating, and the uniformity of the coating film can be increased to prevent cissing failure, and haze that tends to occur in the presence of an organic solvent is suppressed. Progress evenly. The effect becomes particularly remarkable by the coexistence of a compatibilizer described later. There is no restriction | limiting in particular in surfactant to be used, Any of anionic surfactant, a cationic surfactant, an amphoteric surfactant, a nonionic surfactant, a fluorine-type surfactant, etc. may be sufficient.

Specifically, for example, Tokiyuki Yoshida “Surfactant Handbook (new edition)” (Engineering Book, published in 1987), “Functional Creation / Material Development / Applied Technology of Surfactant”, Volume 1 (Technical Education Publishing) , Published in 2000) and the like.
Among these surfactants, quaternary ammonium salts as cationic surfactants, various polyalkylene glycol derivatives as nonionic surfactants, polyethylene oxide derivatives such as various polyethylene oxide adducts, Betaine-type compounds as amphoteric surfactants are preferred.
In the alkaline solution, it is also preferable to use a nonionic surfactant and an anionic surfactant or a nonionic masking surfactant and a cationic surfactant in coexistence because the effect of the present invention is enhanced.

  The amount of these surfactants added to the alkaline solution is preferably 0.001 to 10% by mass, more preferably 0.01 to 5% by mass.

  The alkaline solution used in the present invention preferably contains a compatibilizing agent. In the present invention, the “compatibilizer” refers to a hydrophilic compound having a water solubility of 50 g or more with respect to 100 g of the compatibilizer at a temperature of 25 ° C. The solubility of the water of the compatibilizing agent is preferably 80 g or more, more preferably 100 g or more with respect to 100 g of the compatibilizing agent. When the compatibilizer is a liquid compound, the boiling point is preferably 100 ° C. or higher, and more preferably 120 ° C. or higher.

The compatibilizing agent has an action of preventing drying of the alkaline solution attached to the wall surface of a bath or the like for storing the alkaline solution, suppressing sticking, and stably holding the alkaline solution.
In addition, after the alkali solution is applied to the surface of the support and held for a certain period of time, the applied alkali solution thin film is dried until the saponification treatment is stopped, resulting in precipitation of solids, It has the effect of preventing the solid from being difficult to be washed out. Furthermore, phase separation between water as a solvent and the organic solvent is prevented.
In particular, due to the coexistence of the surfactant, the organic solvent, and the above-described compatibilizing agent, the treated support has less haze, and even in the case of a long continuous saponification treatment, the entire surface is stable and uniform. This is the degree of saponification.

The compatibilizing agent is not particularly limited as long as it is a material that satisfies the above conditions. For example, a water-soluble polymer containing a repeating unit having a hydroxyl group and / or an amide group, such as a polyol compound or a saccharide, can be suitably exemplified. .
As the polyol compound, any of a low molecular compound, an oligomer compound, and a high molecular compound can be used.
Examples of aliphatic polyols include alkanediols having 2 to 8 carbon atoms (for example, ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, glycerin monomethyl ether, glycerin monoethyl ether, cyclohexanediol, cyclohexanedimethanol). , Diethylene glycol, dipropylene glycol, etc.), C3-C18 alkanes containing 3 or more hydroxyl groups (for example, glycerin, trimethylolethane, trimethylolpropane, trimethylolbutane, hexanetriol, pentaerythritol, diglycerin) , Dipentaerythritol, inositol, etc.).
As the polyalkyleneoxy polyols, the same alkylene diols as described above may be bonded to each other, or different alkylene diols may be bonded to each other, but a polyalkylene polyol in which the same alkylene diols are bonded to each other is more preferable. . In any case, the number of bonds is preferably 3 to 100, and more preferably 3 to 50. Specific examples include polyethylene glycol, polypropylene glycol, and poly (oxyethylene-oxypropylene).

Examples of saccharides include “Natural Polymers” Chapter 2 (Kyoritsu Shuppan Co., Ltd., published in 1984) edited by the Society of Polymer Science, Japan, “Modern Industrial Chemistry 22, Natural Products Industrial Chemistry”. II "(Asakura Shoten Co., Ltd., published in 1967) and the like. Among these, saccharides that have no free aldehyde group and ketone group and do not exhibit reducibility are preferable.
Sugars are generally classified into glucose, sucrose, trehalose-type oligosaccharides in which reducing groups are bonded, glycosides in which reducing groups of saccharides and non-saccharides are bonded, and sugar alcohols reduced by hydrogenation of saccharides. Both are suitably used in the present invention.
For example, saccharose, trehalose, alkyl glycoside, phenol glycoside, mustard oil glycoside, D, L-arabit, rebit, xylit, D, L-sorbit, D, L-mannit, D, L-exit , D, L-Tallit, Zulsicit, Allozulcit, and reduced water candy. These saccharides can be used alone or in combination of two or more.

Examples of the water-soluble polymer having a repeating unit having a hydroxyl group and / or an amide group include natural gums (for example, gum arabic, guar gum, tragand gum, etc.), polyvinyl pyrrolidone, dihydroxypropyl acrylate polymers, celluloses. Or the addition reaction body of chitosans and an epoxy compound (ethylene oxide or propylene oxide) is mentioned.
Of these, polyol compounds such as alkylene polyols, polyalkyleneoxy polyols and sugar alcohols are preferred.

  The content of the compatibilizer is preferably 0.5 to 25% by mass and more preferably 1 to 20% by mass with respect to the alkaline solution.

  The alkaline solution used in the present invention can contain other additives. Examples of other additives include known additives such as antifoaming agents, alkaline solution stabilizers, pH buffering agents, preservatives, and antibacterial agents.

[Alkali saponification method]
The surface treatment method of the cellulose acylate film using the above alkaline solution may be any conventionally known method, but the coating method is preferred particularly when only one surface of the film is uniformly saponified without unevenness. As a coating method, a conventionally known coating method {rod coating method (rod wound with a thin metal wire), roll coating method (forward roll coater, reverse roll coater, gravure coater), curtain coating method, die coating method ( Coating methods such as extrusion coater (slot coater), slide coater, slit die coater). The coating method is described in various documents (for example, Modern Coating and Drying Technology, Edward Cohen and Edgar B. Gutoff, Edits., VCH Publishers, Inc, 1992).
The coating amount of the alkali solution, then, taking into account the waste treatment to water washing removed as much as possible it is desirable to suppress, preferably ^{1~100mL / m 2, 1~50mL / m} 2 is more preferable. A rod coater, gravure coater, blade coater and die coater that can be stably operated even in a small coating amount range are preferred.
In particular, a die coater in which the coating device portion and the coating support surface can be applied at high speed without causing uneven coating stripes in a small coating amount region is preferable.
The saponification treatment is preferably performed at a treatment temperature in a range not exceeding 120 ° C., which is a temperature at which deformation of the film to be treated, alteration of the treatment liquid, and the like do not occur. Further, the temperature is preferably 10 ° C. or higher and 100 ° C. or lower. In particular, a temperature of 20 to 80 ° C. is preferable.
The saponification time is determined by appropriately adjusting the alkali solution and the processing temperature, but it is preferably performed in the range of 1 second to 60 seconds.

Further, the step of saponifying the cellulose acylate film with an alkaline solution at a surface temperature of at least 10 ° C., the step of maintaining the temperature of the cellulose acylate film at least at 10 ° C., and the alkali solution to the cellulose acylate film It is preferable to carry out an alkali saponification treatment by a step of rinsing off.
The step of saponifying the cellulose acylate film with an alkaline solution at a predetermined temperature on the surface thereof is a step of adjusting to a predetermined temperature before application, a step of adjusting the alkaline liquid to a predetermined temperature in advance, Or the process etc. which combined these are mentioned. It is preferable to combine with a step of adjusting to a predetermined temperature before coating.
After the saponification reaction, it is preferable to wash and remove the alkaline solution and the saponification treatment reaction product from the film surface by washing with water, neutralizing and washing with water.
Specifically, for example, the contents described in International Publication No. 02/46809 pamphlet, Japanese Patent Application Laid-Open No. 2003-313326, and the like can be given.
The surface of the film on which the hydrophilic treatment has been performed preferably has a contact angle with water on the film surface in the range of 20 to 55 °. The contact angle with water is more preferably in the range of 25 to 50 °, and particularly preferably in the range of 30 to 45 °.
Moreover, it is preferable that the surface energy in the film surface exists in the range of 55-75 mN / m. The evaluation method of the surface energy [Evaluation Item 2] of the surface characteristics can be obtained by the contact angle method, the wet heat method, and the adsorption method described in “Basics and Application of Wetting” (Realize, 1989).
By satisfying such surface characteristics, the adhesion to the alignment film and the polarizing film is sufficient, and when the polarizing plate of the present invention is used for an image display device, optical such as a bright spot failure and a cloud failure It exhibits excellent characteristics with no typical defects.

(3) Alignment film forming step The alignment film is a cured film that can be formed by applying a coating liquid of the composition for forming an alignment film on a support, followed by drying by heating (crosslinking) and performing an alignment treatment. It is.
As described above, the crosslinking reaction may be carried out at any time after coating on the support. When a water-soluble polymer such as polyvinyl alcohol is used as the composition for forming an alignment film, the coating solution may be a mixed solvent of an organic solvent (eg, methanol, ethanol, isopropanol, etc.) having a defoaming action and water. preferable.
The ratio of water: methanol is preferably 0: 100 to 99: 1, and more preferably 0: 100 to 91: 9. Thereby, generation | occurrence | production of a bubble is suppressed and the orientation film and also the defect of the layer surface of an optically anisotropic layer reduce remarkably, and it is preferable.

  FIG. 1 is a schematic view showing the configuration of the method for producing an optical compensation film of the present invention. As shown in FIG. 1, the long support 4a sent out by the delivery machine 1a from the long roll (film roll) 5a of the support produced as described above is transported by the drive roller, and the surface dust remover 2 Then, a coating solution containing the composition for forming an alignment film is applied by the coating machine 3 and dried in the drying zone 5 to form a resin layer on the support surface. The film obtained here may be wound up once.

The alignment film of the present invention comprises a coating solution for the alignment film forming composition as described above, a dip coating method, an air knife coating method, a curtain coating method, a roller coating method, a wire bar coating method, a gravure coating, and a micro gravure method. It is formed by coating using a method such as a die coating method (extrusion coating method (US Pat. No. 2,681,294), slide coating method, extrusion coating method).
The coating method is described in various documents (for example, Modern Coating and Drying Technology, Edward Cohen and Edgar B. Gutoff, Edits., VCH Publishers, Inc, 1992).
A rod coater method, a gravure coater method, a blade coater method, and a die coater method that can be stably operated even in a small coating amount range are preferable, and a rod coater method and a die coater method are particularly preferable.

Although not shown, the alignment film forming step is specifically performed as follows.
The coating solution containing the alignment film forming resin in the coating solution tank is sent by a pump through the filter into the extrusion die having the decompression chamber 35a, while being supported by the backup roll on the transported support. Applied.
The coated substrate is then dried in the drying zone through a transport zone where initial drying is performed, and continuously transferred to the next “rubbing step”. Or you may make it wind up once here.
The distance between the extrusion die and the support is generally 100 μm to 300 μm, the decompression chamber is generally kept 200 Pa to 500 Pa lower than the atmospheric pressure, and the coating speed is 0.1 m / second to 1.0 m / second. Seconds are preferred.
Drying is preferably performed at 70 to 100 ° C. for 1 to 10 minutes. The viscosity of the coating solution, 1mPas (25 ℃) ~20mPas ( 25 ℃) are preferred, coating ^{amount, 10g / m 2 ~50g / m} 2 is preferred.
In the above description, the application is performed using an extrusion die, but it can be similarly performed using a wire bar used for forming a liquid crystal layer described later.

(4) Pretreatment step The pretreatment step of the present invention is a step of irradiating the alignment film formed on the support with ultraviolet rays to crosslink the radical polymerizable group contained in the alignment film.
As in this step, before the optically anisotropic layer is formed, the alignment film is irradiated with ultraviolet rays to crosslink the radical polymerizable group, thereby not only the alignment film interface but also the alignment film. Since the inside is also cured to some extent, the expansion rate of the alignment film itself decreases, and even when the optical compensation film laminated as a product is placed under high humidity, the alignment film can be prevented from swelling.
60 mJ-600 mJ is preferable, the irradiation amount of the ultraviolet rays irradiated to the alignment film is more preferably 120 mJ-600 mJ, and still more preferably 120 mJ-300 mJ. If the irradiation amount of the ultraviolet rays irradiated to the alignment film in this step is 60 mJ or less, the alignment film is not completely cured, and the alignment film may swell when placed under high humidity. Further, when the irradiation amount is 600 mJ or more, the curing of the alignment film proceeds more than necessary, and the bonding between the alignment film and the optical anisotropic layer may be incomplete in the optical anisotropic layer forming process described later. There is.
Here, when the support, the alignment film, and the optically anisotropic layer are stacked and the stacking direction is the “thickness direction”, the inside refers to the thickness from the interface on the support side of the alignment film. It is a region having a depth of 0.7 μm in the vertical direction and also including the interface on the support side.
In addition, the radical polymerizable group was crosslinked by the pretreatment step when the cross section of the alignment film was confirmed by a transmission electron micrograph using an osmium staining method and the reaction rate distribution of the radical polymerizable group was distributed. Can be identified by confirming that it is manifested internally.

(5) Rubbing process The support 4b on which the alignment layer forming resin layer is formed comprises a rubbing roller 8, a guide roller 6 fixed to a roller stage with a spring, and a dust remover 7 provided on the rubbing roller. Thus, the rubbing treatment is performed, and the surface of the formed alignment film is removed by the surface dust remover 9 provided adjacent to the rubbing apparatus.
A known device other than the above may be used as the rubbing device.

(6) Optically anisotropic layer forming step (6a) Optically anisotropic layer coating step The support 4c on which the alignment film is formed is conveyed by a driving roller, and the alignment film includes a liquid crystalline discotic compound. The liquid is applied by the applicator 10.

(6b) Drying step Next, after evaporating the solvent, the coating layer is heated to the discotic nematic phase formation temperature in the heating zone 11 (here, the residual solvent of the coating layer is also evaporated) to form a discotic nematic phase. The liquid crystal layer is formed.

(6c) Optically anisotropic layer fixing step Thereafter, the liquid crystal layer is irradiated with ultraviolet rays from an ultraviolet (UV) lamp 12 to crosslink the liquid crystal layer.
Here, in order to make it bridge | crosslink, it is necessary to use the liquid crystalline discotic compound which has a crosslinkable functional group as a liquid crystalline discotic compound.
When a liquid crystal discotic compound having no crosslinkable functional group is used, this ultraviolet irradiation step is omitted and the liquid crystal is immediately cooled.
In this case, the cooling needs to be performed rapidly so that the discotic nematic phase is not destroyed during cooling.
The support on which the alignment film and the liquid crystal layer are formed is inspected for optical properties on the surface of the support by the inspection device 13 to check for any abnormalities. Next, the protective film 14 is laminated on the surface of the liquid crystal layer by a laminating machine 15 and wound up by a winding device.

Here, the liquid crystalline molecules are preferably substantially uniformly aligned, more preferably fixed in a substantially uniformly aligned state, and the liquid crystalline molecules are substantially converted by a polymerization reaction. Most preferably, it is fixed in a uniformly oriented state. The polymerization reaction includes a thermal polymerization reaction using a thermal polymerization initiator and a photopolymerization reaction using a photopolymerization initiator. A photopolymerization reaction is preferred.
Examples of the photopolymerization initiator include α-carbonyl compounds (described in US Pat. Nos. 2,367,661 and 2,367,670), acyloin ether (described in US Pat. No. 2,448,828), α-hydrocarbon-substituted aromatic acyloin. Compound (described in US Pat. No. 2,722,512), polynuclear quinone compound (described in US Pat. Nos. 3,046,127 and 2,951,758), a combination of triarylimidazole dimer and p-aminophenyl ketone (US Pat. No. 3,549,367) Acridine and phenazine compounds (JP-A-60-105667, U.S. Pat. No. 4,239,850) and oxadiazole compounds (U.S. Pat. No. 4,212,970).
It is preferable that the usage-amount of a photoinitiator is 0.01-20 mass% of solid content of a coating liquid, and it is further more preferable that it is 0.5-5 mass%.
Light irradiation for polymerization of discotic liquid crystalline molecules is preferably performed using ultraviolet rays.
The irradiation energy ^is preferably ^{20mJ / cm 2 ~50J / cm 2} , and more preferably 100 to 800 mJ / cm ^2. In order to accelerate the photopolymerization reaction, light irradiation may be performed under heating conditions.

(7) Winding process In the winding process, using the wound film having the alignment layer-forming resin layer that has been wound once, the process until the optical compensation film is created and wound is continuously produced. You may do it. By doing in this way, the film 4b is sent out by the sending machine 1b from the film roll 5b having the alignment layer forming resin layer, and the steps after the rubbing step are performed in the same manner as described above.

It is used when the support is fed out and when the support having the alignment layer forming resin layer is fed out and bonded to the support.
As the feeder, those generally used for feeding plastic films can be used. For example, it is used together with a feeder using a superposition method (for example, manufactured by EAGAN, manufactured by Black Clawson), and a joining device and a joining device described in Japanese Patent Publication No. 48-38461. An unwinding device that can be used.
As a delivery stand, a turret type shaftless (Shftless Turret Unwinder) is generally used.
A lateral position guidance system for the unwinding or winding roll stand (eg, FIG. 352A and FIG. 352B on page 446 of COATING AND LAMINATING MACHINES) can also be used.
To prevent the film from moving to one side or meandering while being transported, after passing through the drying zone, a biaxial roll lateral guide device (eg, COATING AND LAMINATING MACHINES, page 448) 355A), and during roll transport, a box-roller lateral guidance device (eg, FIG. 355B on page 448 of COATING AND LAMINATING MACHINES) is used. These are commercially available from Fife or Nippon Regulator Co., Ltd.
As a driving device such as a transport device, a suction drum having a large number of holes on its surface is used.
The winding device can be wound using a saw blade cutting method and a tip winding method using an adhesive (refer to a catalog of a winding device manufactured by EAGAN or Black Lawson).
As the winding stand, a turret type shaftless (Shaftless Turret Unwinder) used as the delivery stand is generally used. The roll stand lateral position guide system used in the above-described feeder can be used in the same manner.

(Polarizer)
The polarizing plate of the present invention includes at least the optical compensation film of the present invention and a polarizer.
As described above, the optical compensation film of the present invention exhibits its functions remarkably by being bonded to a polarizer to produce a polarizing plate.

<Polarizer>
Examples of the polarizer (hereinafter also referred to as “polarizing film”) include a coating type polarizing film typified by those manufactured by Optiva, a polarizing film comprising a binder and iodine or a dichroic dye. Etc. are preferable.
The iodine and the dichroic dye in the polarizer exhibit a deflection performance by being oriented in the binder. It is preferable that the iodine and the dichroic dye are aligned along the binder molecule, or the dichroic dye is aligned in one direction by self-assembly like a liquid crystal.
Here, a general-purpose polarizer is produced by immersing a stretched polymer in a solution of iodine or dichroic dye in a bath and allowing the iodine or dichroic dye to penetrate into the binder. It is common.
In the general-purpose polarizer, iodine or a dichroic dye is distributed about 4 μm (about 8 μm on both sides) from the polymer surface. For this reason, in order to obtain sufficient polarization performance, the thickness of the binder is preferably 10 μm or more. On the other hand, the upper limit of the thickness is not particularly limited, but it is preferably as thin as possible from the viewpoint of the light leakage phenomenon that occurs when the polarizing plate is used in a liquid crystal display device. For this reason, it is preferable that it is 30 micrometers or less, 25 micrometers or less are more preferable, and 20 micrometers or less are especially preferable. When the thickness is 20 μm or less, the light leakage phenomenon is not observed on a 17-inch liquid crystal display device. The degree of penetration can be controlled by the solution concentration, bath temperature, and immersion time of iodine or dichroic dye.

The binder of the polarizing film may be cross-linked. As the crosslinked binder, a polymer that can be crosslinked per se can be used. Specifically, a polarizing film can be formed by reacting a polymer having a functional group or a binder obtained by introducing a functional group into the polymer between the binders by light, heat, or pH change.
Further, a crosslinked structure may be introduced into the polymer by a crosslinking agent. The cross-linked structure can be formed by using a cross-linking agent that is a highly reactive compound, introducing a bonding group derived from the cross-linking agent between the binders, and cross-linking the binders.
In general, the crosslinking is performed by applying a coating liquid containing a polymer or a mixture of a polymer and a crosslinking agent on a transparent support and then heating. The crosslinking treatment may be performed at any stage until the final polarizing plate is obtained as long as the durability can be ensured at the stage of the final product.

As the binder of the polarizing film, either a polymer that can be crosslinked by itself or a polymer that is crosslinked by a crosslinking agent can be used. Examples of the polymer include polymethyl methacrylate, polyacrylic acid, polymethacrylic acid, polystyrene, gelatin, polyvinyl alcohol, modified polyvinyl alcohol, poly (N-methylolacrylamide), polyvinyltoluene, chlorosulfonated polyethylene, nitrocellulose, and chlorine. Polyolefins (for example, polyvinyl chloride), polyester, polyimide, polyvinyl acetate, polyethylene, carboxymethylcellulose, polypropylene, polycarbonate, and copolymers thereof. Examples of the copolymer include acrylic acid / methacrylic acid copolymer, styrene / maleimide copolymer, styrene / vinyl toluene copolymer, vinyl acetate / vinyl chloride copolymer, and ethylene / vinyl acetate copolymer. Can be mentioned.
Among these, as the polymer, for example, water-soluble polymers such as poly (N-methylolacrylamide), carboxymethylcellulose, gelatin, polyvinyl alcohol, and modified polyvinyl alcohol are preferable, and gelatin, polyvinyl alcohol, and modified polyvinyl alcohol are more preferable. Polyvinyl alcohol and modified polyvinyl alcohol are particularly preferred.

The saponification degree of the polyvinyl alcohol and modified polyvinyl alcohol is preferably 70 to 100%, more preferably 80 to 100%, and particularly preferably 95 to 100%. The degree of polymerization of the polyvinyl alcohol is preferably 100 to 5,000.
The modified polyvinyl alcohol is obtained by introducing a modifying group into polyvinyl alcohol by copolymerization modification, chain transfer modification or block polymerization modification. In the copolymerization modification, COONa, Si (OH) ₃ , N (CH ₃ ) ₃ .Cl, C ₉ H ₁₉ COO, SO ₃ Na, C ₁₂ H ₂₅ can be introduced as modifying groups. In the chain transfer modification, COONa, SH, or SC ₁₂ H ₂₅ can be introduced as a modifying group.
The degree of polymerization of the modified polyvinyl alcohol is preferably 100 to 3,000. Examples of the modified polyvinyl alcohol are described in JP-A-8-338913, JP-A-9-152509, JP-A-9-316127, and the like.
Among these, the polyvinyl alcohol and modified polyvinyl alcohol are particularly preferably unmodified polyvinyl alcohol and alkylthio-modified polyvinyl alcohol having a saponification degree of 85 to 95%. In addition, the said polyvinyl alcohol and modified polyvinyl alcohol may be used individually by 1 type, and may use 2 or more types together.

When a large amount of the crosslinking agent for the binder is added, the wet heat resistance of the polarizing film can be improved. However, when 50 mass% or more of a crosslinking agent is added to the binder, the orientation of iodine or the dichroic dye is lowered. For this reason, 0.1-20 mass% is preferable with respect to a binder, and, as for the addition amount of the said crosslinking agent, 0.5-15 mass% is more preferable.
The binder may contain some crosslinking agent that has not reacted even after the crosslinking reaction has been completed. However, the amount of the remaining crosslinking agent is preferably 1.0% by mass or less and more preferably 0.5% by mass or less in the binder. When the crosslinking agent is contained in the binder in an amount exceeding 1.0% by mass, there may be a problem in durability. That is, when a polarizing film having a large amount of residual crosslinking agent is incorporated in a liquid crystal display device and used for a long time or left in a high-temperature and high-humidity atmosphere for a long time, the degree of polarization may decrease.
Examples of the crosslinking agent are described in US Reissue Patent 23297. For example, boron compounds such as boric acid and borax can also be used as a crosslinking agent.

Examples of the dichroic dye include azo dyes, stilbene dyes, pyrazolone dyes, triphenylmethane dyes, quinoline dyes, oxazine dyes, thiazine dyes, anthraquinone dyes, and the like. The dichroic dye is preferably water-soluble. Further, it preferably has a hydrophilic substituent (eg, sulfo, amino, hydroxyl).
Examples of the dichroic dye include C.I. I. Direct Yellow 12, C.I. I. Direct Orange 39, C.I. I. Direct Orange 72, C.I. I. Direct Red 39, C.I. I. Direct Red 79, C.I. I. Direct Red 81, C.I. I. Direct Red 83, C.I. I. Direct Red 89, C.I. I. Direct Violet 48, C.I. I. Direct Blue 67, C.I. I. Direct Blue 90, C.I. I. Direct Green 59, C.I. I. Acid Red 37 and the like.
Examples of the dichroic dye include, for example, JP-A-1-161202, 1-172906, 1-172907, 1-183602, 1-248105, 1-265205, 7-261024, and the like.
The dichroic dye is used as a free acid, an alkali metal salt, an ammonium salt, or an amine salt. Moreover, the polarizing film which has various hues can be manufactured by mix | blending two or more types of dichroic dyes.
Among these, as the dichroic dye, a polarizing film using a compound (pigment) that exhibits black when the polarization axes are orthogonal to each other, a polarizing film containing various dichroic molecules so as to exhibit black, or polarized light A plate is preferable because both the single plate transmittance and the polarization rate are excellent.

In order to increase the contrast ratio of the liquid crystal display device, the transmittance of the polarizing plate is preferably higher and the degree of polarization is preferably higher. The transmittance of the polarizing plate is preferably in the range of 30 to 50%, more preferably in the range of 35 to 50%, and particularly in the range of 40 to 50% in light having a wavelength of 550 nm. preferable. The maximum value of the single plate transmittance of the polarizing plate is 50%.
The degree of polarization is preferably in the range of 90 to 100%, more preferably in the range of 95 to 100%, and particularly preferably in the range of 99 to 100% in light having a wavelength of 550 nm.

The polarizing film and the optically anisotropic layer can also be disposed via an adhesive. Examples of the adhesive include polyvinyl alcohol resins and boron compound aqueous solutions. Among these, polyvinyl alcohol resins are preferable. In addition, as said polyvinyl alcohol-type resin, the modified polyvinyl alcohol by an acetoacetyl group, a sulfonic acid group, a carboxyl group, or an oxyalkylene group is included.
The thickness of the adhesive layer is preferably in the range of 0.01 μm to 10 μm after drying, and more preferably in the range of 0.05 μm to 5 μm.

[Production method of polarizer]
From the viewpoint of yield, the polarizing film is stretched at an angle of 10 to 80 ° with respect to the longitudinal direction (MD direction) of the polarizing film (stretching method), or after rubbing (rubbing method), iodine, It is preferable to dye with a dichroic dye. The inclination angle is preferably stretched so as to match the transmission axis of the two polarizing plates bonded to both sides of the liquid crystal cell constituting the liquid crystal display (LCD) and the angle formed by the vertical or horizontal direction of the liquid crystal cell. .
The tilt angle is usually 45 °, but in recent years, transmissive LCDs, reflective LCDs, and transflective LCDs have not been developed with a device that is not necessarily 45 °, and the stretching direction is arbitrary according to the design of the LCD. It is preferable that it can be adjusted.

In the case of the stretching method, the stretching ratio is preferably 2.5 to 30.0 times, more preferably 3.0 to 10.0 times. Stretching may be performed by dry stretching in air, or wet stretching in a state of being immersed in water. The stretch ratio of the dry stretching is preferably 2.5 to 5.0 times, and the stretch ratio of the wet stretching is preferably 3.0 to 10.0 times.
The stretching step may be performed in several steps including oblique stretching. By dividing into several times, it is possible to stretch more uniformly even at high magnification. Further, before the oblique stretching, the stretching may be performed horizontally or vertically to prevent shrinkage in the width direction.
Stretching can be performed by performing tenter stretching in biaxial stretching in different steps. The biaxial stretching is the same as the stretching method performed in normal film formation. Since the biaxial stretching is performed at different speeds on the left and right, the thickness of the binder film before stretching needs to be different on the left and right. In casting film formation, the flow rate of the binder solution can be differentiated between the left and right sides by tapering the die.
In the stretching method, a binder film that is obliquely stretched by 10 to 80 ° with respect to the MD direction of the polarizing film is produced as described above.

In the rubbing method, a rubbing treatment method widely adopted as a liquid crystal alignment treatment process of LCD can be applied. That is, the orientation is obtained by rubbing the surface of the film in a certain direction using, for example, paper, gauze, felt, rubber, nylon, polyester fiber or the like. Generally, it is carried out by rubbing several times using a cloth in which fibers having a uniform length and thickness are planted on average.
The rubbing is preferably performed using a rubbing roll whose roundness, cylindricity, and runout (eccentricity) are all 30 μm or less. The film wrap angle on the rubbing roll is preferably 0.1 to 90 °. However, as described in JP-A-8-160430, a stable rubbing treatment can also be obtained by winding 360 ° or more.
When rubbing a long film, it is preferable to transport the film at a speed of 1 to 100 m / min with a constant tension by a transport device. At this time, the rubbing roll is preferably rotatable in a horizontal direction with respect to the film traveling direction for setting an arbitrary rubbing angle, and specifically, an appropriate rubbing angle within a range of 0 to 60 °. It is preferable to select. The rubbing angle is preferably 40 to 50 ° and particularly preferably 45 ° when used in a liquid crystal display device.
A polymer film is preferably disposed on the surface of the polarizing film opposite to the optically anisotropic layer, and the optically anisotropic layer / polarizing film / polymer film is preferably disposed.

[Surface treatment of optical compensation film]
When an optical compensation film is used instead of the transparent protective film of the polarizing plate, adhesion between the optical compensation film and the transparent protective film of the polarizing plate becomes a problem. In the present invention, adhesion between the optical compensation film and the polarizing film can be improved by surface-treating the surface of the optical compensation film on the polarizing film side.
As the surface treatment, corona discharge treatment, glow discharge treatment, flame treatment, ultraviolet irradiation treatment, ozone treatment, acid treatment or alkali treatment is performed.
Examples of treatment methods such as corona discharge treatment, glow discharge treatment, flame treatment, ultraviolet irradiation treatment, ozone treatment, acid treatment, and alkali treatment include the contents described in pages 30 to 31 of public technical number 2001-1745. In the present invention, it is preferable to perform an alkali treatment, and examples thereof include the same contents as described in the saponification treatment of the above-described film.

(Liquid crystal display device)
The liquid crystal display device of the present invention has the polarizing plate of the present invention. A preferable form in each liquid crystal mode will be described below.

[TN mode liquid crystal display]
A TN (twisted nematic) mode liquid crystal cell is most frequently used as a color thin film transistor array (TFT) liquid crystal display device, and is described in many documents.
The alignment state in the liquid crystal cell in the TN mode black display is an alignment state in which the rod-like liquid crystal molecules rise at the center of the cell and the rod-like liquid crystal molecules lie near the cell substrate.

For the rod-like liquid crystalline molecules in the center of the cell, it can be compensated by a discotic compound of homeotropic alignment that is a horizontal alignment in which the disk surface is lying, or a (transparent) support, and in the vicinity of the substrate of the cell The rod-like liquid crystal molecules can be compensated by a hybrid alignment discotic compound in which the inclination of the major axis changes with the distance from the polarizing film.
Further, for the rod-like liquid crystalline molecules at the center of the cell, it can be compensated by a homogeneously oriented rod-like liquid crystalline molecule having a horizontal axis with a long axis lying or a (transparent) support. The rod-like liquid crystalline molecules in the vicinity of the substrate can be compensated with a discotic compound having a hybrid orientation.

The homeotropic alignment liquid crystal molecules are aligned in a state where the angle between the average alignment direction of the major axis of the liquid crystal molecules and the plane of the polarizing film is 85 to 95 °.
The homogeneously aligned liquid crystal molecules are aligned in a state where the angle between the average alignment direction of the major axes of the liquid crystal molecules and the plane of the polarizing film is less than 5 °.
In the hybrid alignment liquid crystal molecules, the angle between the average alignment direction of the long axes of the liquid crystal molecules and the plane of the polarizing film is preferably larger than 15 °, and more preferably 15 to 85 °.

An optically anisotropic layer in which the (transparent) support or discotic compound is homeotropically oriented, an optically anisotropic layer in which the rod-like liquid crystalline molecules are homogeneously oriented, and the homeotropically oriented discotic compound; The optically anisotropic layer composed of a mixture with homogeneously oriented rod-like liquid crystal molecules preferably has a thickness direction retardation value (Rth) of 40 nm to 200 nm and an in-plane retardation value (Re) of 0 to 70 nm. . Here, Rth is a value defined by the following formula (A), and Re is a value defined by the following formula (B).
Rth = {(nx + ny) / 2−nz} × d (Equation (A))
Re = (nx−ny) × d... Formula (B)
In the above formulas (A) and (B), nx represents the refractive index in the slow axis direction in the film plane, ny represents the refractive index in the fast axis direction in the film plane, and nz represents the thickness of the film. Represents the refractive index in the direction. d represents the thickness of the film.
The discotic compound layer having homeotropic alignment (horizontal alignment) and the rod-like liquid crystalline molecular layer having homogeneous alignment (horizontal alignment) are described in JP-A Nos. 12-304931 and 12-304932. Has been. The hybrid liquid crystal discotic liquid crystalline molecular layer is described in JP-A-8-50206.

[OCB mode liquid crystal display]
An OCB (Optically Compensatory Bend) mode liquid crystal cell is a bend alignment mode liquid crystal cell in which rod-like liquid crystal molecules are aligned symmetrically in substantially opposite directions at the upper and lower portions of the liquid crystal cell. The liquid crystal display device using the bend alignment mode liquid crystal cell is described in, for example, US Pat. Nos. 4,583,825 and 5,410,422.
The bend alignment mode liquid crystal cell has a self-optical compensation function because rod-like liquid crystalline molecules are symmetrically aligned between the upper and lower portions of the liquid crystal cell. Therefore, this liquid crystal mode is called an OCB liquid crystal mode.
In the OCB mode liquid crystal cell as well as the TN mode, in the black display, the alignment state in the liquid crystal cell is an alignment state in which the rod-like liquid crystalline molecules rise at the center of the cell and the rod-like liquid crystalline molecules lie in the vicinity of the cell substrate. It is in.

Thus, in black display, since the alignment of the TN mode and the liquid crystal is in the same state, the preferred mode is also the same as in the TN mode. However, since the OCB mode has a larger range in which the liquid crystal compound rises in the center of the cell than the TN mode, the optically anisotropic layer in which the discotic compound is homeotropically aligned, or the rod-like liquid crystal molecule It is necessary to slightly adjust the retardation value of the optically anisotropic layer that is homogeneously oriented.
Specifically, an optically anisotropic layer in which a discotic compound on a (transparent) support is homeotropically aligned, or an optically anisotropic layer in which rod-like liquid crystalline molecules are homogeneously aligned has an Rth of 150. It is preferable that it is -500nm and Re is 20-70nm.

[VA mode liquid crystal display]
In a VA (Vertically Aligned) mode liquid crystal cell, rod-like liquid crystal molecules are aligned substantially vertically when no voltage is applied. In the VA mode liquid crystal cell, for example, (1) rod-like liquid crystal molecules described in JP-A-2-176625 are aligned substantially vertically when no voltage is applied, and substantially when a voltage is applied. VA mode liquid crystal cell in a narrow sense oriented horizontally, (2) SID97, Digest of tech. Papers (Preliminary Proceedings) 28 (1997) 845, MVA mode liquid crystal cell in which the VA mode is multi-domained for widening the viewing angle. (3) Proc. 58-59 (1998) And (4) LCD International 98 in a mode in which rod-like liquid crystalline molecules are substantially vertically aligned when no voltage is applied and twisted multi-domain alignment is applied when a voltage is applied, and (4) LCD International 98 Examples include the SURVAVAL mode liquid crystal cells that have been announced.

In the black display of the VA mode liquid crystal display device, since most of the rod-like liquid crystalline molecules in the liquid crystal cell are in an upright state, the optically anisotropic layer in which the discotic compound is homeotropically aligned, or The liquid crystal compound is compensated by the optically anisotropic layer in which the rod-like liquid crystalline molecules are homogeneously oriented, and separately, the rod-like liquid crystalline molecules are homogeneously oriented, and the average orientation direction of the major axis of the rod-like liquid crystalline molecules and the transmission through the polarizing film It is preferable to compensate the viewing angle dependence of the polarizing plate with an optically anisotropic layer having an angle with the axial direction of less than 5 °.
The optically anisotropic layer having homeotropic alignment or the optically anisotropic layer in which rod-like liquid crystalline molecules are homogeneously aligned preferably has Rth of 150 to 500 nm and Re of 20 to 70 nm.

[Other liquid crystal display devices]
In addition, liquid crystal display devices in ECB (Electrically Controlled Bend) mode and STN (Super Twisted Nematic) mode can be optically compensated in the same way as described above.

  Examples of the present invention will be described below, but the present invention is not limited to the following examples.

(Example 1)
(Preparation of optical compensation film (KH-1))
<Preparation of support (PK-1)>
The following composition was put into a mixing tank and stirred while heating to dissolve each component to prepare a cellulose acetate solution.

[Cellulose acetate solution composition]
・ Acetylation degree 60.9% cellulose acetate (Linter) ・ ・ ・ ・ ・ ・ ・ ・ 80 parts by mass ・ Acetylation degree 60.8% cellulose acetate (Linter) ・ ・ ・ ・ ・ ・ ・ ・ 20 Parts by mass, triphenyl phosphate (plasticizer) ... 7.8 parts by mass, biphenyl diphenyl phosphate (plasticizer) ... -3.9 parts by mass-Methylene chloride (first solvent) ... 300 parts by mass-Methanol (second solvent) ... ... 54 parts by mass
・ 1-Butanol (3rd solvent) ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 11 parts by mass

In another mixing tank, 4 parts by mass of cellulose acetate (linter) having an acetylation degree of 60.9%, 16 parts by mass of a retardation increasing agent represented by the following general formula (IV), silica fine particles (particle size 20 nm, Mohs hardness about 7) ) 0.5 parts by mass, 87 parts by mass of methylene chloride, and 13 parts by mass of methanol were added and stirred while heating to prepare a retardation increasing agent solution.
Next, 36 parts by mass of the retardation increasing agent solution was mixed with 464 parts by mass of the cellulose acetate solution, and the dope was prepared by sufficiently stirring. In addition, the addition amount of the retardation increasing agent was 5.0 mass parts with respect to 100 mass parts of cellulose acetate.

The obtained dope was cast using a band casting machine. The dope was dried for 1 minute after the film surface temperature on the band reached 40 ° C., peeled off the film having a residual solvent amount of 43% by mass, and then dried using a tenter with a drying air of 140 ° C. Stretched 28% in the direction.
Then, it dried for 20 minutes with 135 degreeC drying air, and manufactured the support body (PK-1) whose residual solvent amount is 0.3 mass%.
The obtained support (PK-1) had a width of 1,340 mm and a thickness of 92 μm. Using an ellipsometer (M-150, manufactured by JASCO Corporation), the in-plane retardation value (Re) at a wavelength of 590 nm was measured and found to be 43 nm. The retardation value (Rth) in the thickness direction at a wavelength of 590 nm was measured and found to be 175 nm.
The support (PK-1) thus produced was immersed in a 2.0N potassium hydroxide solution (25 ° C.) for 2 minutes, neutralized with sulfuric acid, washed with pure water and dried. The surface energy of this PK-1 was determined by the contact angle method and found to be 63 mN / m.

<< Preparation of alignment film >>
On this support (PK-1) (alkali-treated surface), an alignment film coating solution (composition for forming an alignment film) having the following composition was applied at 28 mL / m ² with a # 16 wire bar coater.
Thereafter, the film was dried with warm air of 60 ° C. for 60 seconds and further with warm air of 90 ° C. for 150 seconds to produce an alignment film.

[Alignment film coating solution composition]
・ Modified polyvinyl alcohol represented by the following general formula (V): 10 parts by mass, water: ······· 371 parts by mass · Methanol ····················································· Cross-linking agent) ··············· 0.5 parts by mass · Citrate ester (AS3 manufactured by Sankyo Chemical Co., Ltd.) 0.175 parts by mass
・ Polymerization initiator (Irgacure 2959, manufactured by Ciba Geigy Co., Ltd.) ... 0.05 parts by mass

  Thereafter, the prepared alignment film is irradiated with ultraviolet rays having an illuminance of 12 mW for 5 seconds by an ultraviolet irradiation device (ultraviolet lamp: output 160 W / cm, emission length 1.6 m), and the inside of the alignment film is irradiated with an ultraviolet irradiation amount of 60 mJ. Was cured.

<Formation of optically anisotropic layer>
On the alignment film, 41.01 kg of a discotic liquid crystalline compound represented by the following general formula (VI), 4.06 kg of ethylene oxide-modified trimethylolpropane triacrylate (V # 360, manufactured by Osaka Organic Chemical Co., Ltd.), cellulose acetate Butyrate (CAB531-1, Eastman Chemical Co., Ltd.) 0.35 kg, photopolymerization initiator (Irgacure 907, Ciba Geigy Co.) 1.35 kg, and sensitizer (Kayacure DETX, Nippon Kayaku Co., Ltd.) To a coating solution in which 0.45 kg is dissolved in 102 kg of methyl ethyl ketone, 0.1 kg of a fluoroaliphatic group-containing copolymer (Megafac F780 manufactured by Dainippon Ink, Inc.) is added, and a wire bar of # 3.4 is added to 391. Rotate in the same direction as the film transport direction and support is transported at 20 m / min. An optically anisotropic layer (discotic liquid crystal compound layer) was formed by continuously applying to the alignment film surface of the holder (PK-1).

In the step of continuously heating from room temperature to 100 ° C., the solvent is dried, and then the film surface wind speed of the discotic liquid crystal compound layer is 2.5 m / sec with a dry zone of 130 ° C. The discotic liquid crystal compound was aligned by heating for about 90 seconds.
Next, the film is conveyed to a dry zone at 80 ° C., and the surface temperature of the film is about 100 ° C., and an illuminance of 600 mW is applied by an ultraviolet irradiation device (ultraviolet lamp: output 160 W / cm, emission length 1.6 m). Ultraviolet rays were irradiated for 4 seconds to advance the crosslinking reaction, and the discotic liquid crystal compound was fixed to the alignment.
Thereafter, the mixture was allowed to cool to room temperature and wound into a cylindrical shape to form a roll. In this way, a roll-shaped optical compensation film (KH-1) was produced.
The retardation Re of the optically anisotropic layer measured at a wavelength of 546 nm was 40 nm.
Further, the angle (tilt angle) between the disc surface of the discotic liquid crystal compound in the optically anisotropic layer and the support surface was continuously changed in the depth direction of the layer, and was 39 ° on average.

<Production of Polarizing Plate (HB-1)>
[Production of polarizer]
Polyvinyl alcohol (PVA) having an average polymerization degree of 4,000 and a saponification degree of 99.8 mol% was dissolved in water to obtain a 4.0% aqueous solution. This solution was band-cast using a die having a taper and dried to form a film so that the width before stretching was 110 mm, the thickness was 120 μm at the left end, and 135 μm at the right end.
The film was peeled off from the band, obliquely stretched in the 45 ° direction in a dry state, and immersed in an aqueous solution of iodine 0.5 g / L and potassium iodide 50 g / L for 1 minute at 30 ° C., and then boric acid 100 g / L. L, immersed in an aqueous solution of 60 g / L of potassium iodide at 70 ° C. for 5 minutes, further washed in a water washing tank at 20 ° C. for 10 seconds, dried at 80 ° C. for 5 minutes, and then iodine-based polarizer (HF-01 ) The obtained polarizer had a width of 660 mm and a thickness of 20 μm on both sides.

[Attaching optical compensation film]
Iodine is adsorbed on the stretched polyvinyl alcohol film to produce a polarizer (HF-01), and using a polyvinyl alcohol adhesive, KH-1 (optical compensation film) is polarized on the support (PK-1) surface. It stuck on one side of the child (HF-01).
Further, a saponification treatment was performed on a 80 μm thick triacetyl cellulose film (TD-80U: manufactured by Fuji Photo Film Co., Ltd.), and the other side of the polarizer (HF-1) was coated with a polyvinyl alcohol adhesive. Pasted.
In addition, it arrange | positioned so that the longitudinal direction of polarizer (HF-01), the longitudinal direction of a support body (PK-1), and also the longitudinal direction of a commercially available triacetylcellulose film might all become parallel. In this way, a polarizing plate (HB-1) was produced.
Further, when the polarizing plate was arranged in a crossed Nicol arrangement and the unevenness of the obtained optical compensation film was observed, no unevenness was detected even when viewed from the front and a direction inclined by 60 ° from the normal line.

<Production of bend alignment liquid crystal cell>
A polyimide film was provided as an alignment film on a glass substrate with an ITO electrode, and the alignment film was rubbed. The obtained two glass substrates were faced to each other so that the rubbing directions were parallel to each other, and the cell gap was set to 4.5 μm.
A liquid crystal compound having a Δn of 0.1396 (ZLI1132, manufactured by Merck & Co., Inc.) was injected into the cell gap to produce a bend-aligned liquid crystal cell. The size of the liquid crystal cell was 20 inches.
Two polarizing plates (HB-1) were bonded so as to sandwich the produced bend alignment liquid crystal cell. The optically anisotropic layer of the polarizing plate faces the glass substrate, and the rubbing direction of the liquid crystal cell and the rubbing direction of the optically anisotropic layer facing it are arranged to be antiparallel.

  A rectangular wave voltage of 55 Hz was applied to the liquid crystal cell. The liquid crystal cell was in a normally white mode with a white display of 2V and a black display of 5V. Using the measurement ratio (EZ-Contrast 160D, manufactured by ELDIM) with the transmittance ratio (white display / black display) as the contrast ratio, the viewing angle can be adjusted in 8 steps from black display (L1) to white display (L8). It was measured. Further, the front contrast (CR: white display brightness / black display brightness) was obtained. Further, the transmittance of the liquid crystal cell was obtained from the brightness of white display / the brightness of only the backlight.

(Evaluation with TN liquid crystal cell)
A pair of polarizing plates provided in a liquid crystal display device (AQUAS LC20C1S, manufactured by Sharp Corporation) using a TN type liquid crystal cell is peeled off, and a polarizing plate (HB-1) is used instead of this polarizing plate as an optical compensation film. A single sheet was affixed to the observer side and the backlight side via an adhesive so that (KH-1) was on the liquid crystal cell side. At this time, the transmission axis of the polarizing plate on the viewer side and the transmission axis of the polarizing plate on the backlight side were arranged so as to be orthogonal to each other.
About the produced liquid crystal display device, the viewing angle was measured in eight steps from black display (L1) to white display (L8) using the measuring machine (EZ-Contrast160D, ELDIM company make).

(Evaluation of optical compensation film, polarizing plate, and liquid crystal display device)
-Evaluation of durability crack-
A sample in which the polarizing plate (HB-1) produced in Example 1 was attached to glass was used as a sample. After being allowed to stand for 24 hours under conditions of a temperature of 60 ° C. and a relative humidity of 90%, the sample was returned to room temperature. The crack (durability crack) of the sample was observed visually and with a stereomicroscope (SMZ1500, manufactured by Nikon Corporation). The degree of durability cracking was determined based on the following evaluation criteria.

[Evaluation criteria]
(Double-circle): The crack did not generate | occur | produce at all.
○: A minute crack that cannot be visually observed is generated, but this is not a problem as a product.
Δ: Cracks are generated, but there is no problem as a product.
X: A crack that can be observed visually is generated and cannot be used as a product.

-Evaluation of smoothness-
The smoothness of the coating layer after drying at the time of producing the alignment film is obtained by placing the sample and the level sample on a high-luminance flat light source (FP701, manufactured by Gunma Ushio Electric Co., Ltd.) Evaluation was performed based on the following evaluation criteria with the naked eye from a viewing angle of 45 ° with respect to the normal direction of the light source. The results are shown in Table 1.

[Evaluation criteria]
A: Unevenness is not visible.
○: Concavities and convexities can be visually recognized, but the degree of concavities and convexities is lower than the level sample.
Δ: Unevenness can be visually recognized, which is equivalent to a level sample.
X: Unevenness can be visually recognized, and the degree of unevenness is higher than the level sample.

[Evaluation of liquid crystal display devices]
-Evaluation of unevenness on the panel-
The liquid crystal display device was adjusted to a halftone on the entire surface, and unevenness was evaluated. No unevenness was observed from any direction.

(Examples 2 to 24)
In Example 1, an optical compensation film was obtained in the same manner as in Example 1 except that the ultraviolet irradiation amount (illuminance and irradiation time) and the polymerization initiator content on the alignment film were changed as shown in Table 1. And the polarizing plate was produced.
Further, with respect to the prepared optical compensation film and polarizing plate, durability cracks and smoothness were evaluated in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 1)
In Example 1, an optical compensation film and a polarizing plate were produced in the same manner as in Example 1 except that ultraviolet irradiation was not performed before the rubbing step.
Further, with respect to the prepared optical compensation film and polarizing plate, durability cracks and smoothness were evaluated in the same manner as in Example 1. The results are shown in Table 1.

From the results of Table 1, in the optical compensation films and polarizing plates of Examples 1 to 24, since ultraviolet irradiation was performed before the rubbing step, it was confirmed that both the durability crack and the smoothness were kept good. . In particular, in Examples 1 to 24 in which the irradiation amount of ultraviolet rays was 60 to 600 (mJ), the results were more excellent in durability cracking and smoothness, and Example 2 in which a polymerization initiator was added to the alignment film In 3, 5, 6, 8, 9, 11, and 12, the results showed further excellent durability cracking and smoothness.
On the other hand, in the optical compensation film and the polarizing plate of Comparative Example 1, since the ultraviolet irradiation was not performed before the rubbing step, the smoothness was somewhat good, but the durability crack was poor.

  In addition, it was confirmed that the liquid crystal display devices of Examples 1 to 24 exhibited better display characteristics than the liquid crystal display device of Comparative Example 1.

  The optical compensation film of the present invention is suitable for a polarizing plate and a liquid crystal display device having the same because it has high durability when the polarizing plate is prepared and placed under high humidity and can maintain good smoothness. Can be used.

FIG. 1 is a schematic view showing an example of all steps of the method for producing an optical compensation film of the present invention.

Explanation of symbols

1a, 1b Sending machine 2 Surface dust remover 3 Coating machine 4a Long transparent film (support)
4b Transparent film (support) on which a resin layer is formed
4c Transparent film (support) on which an alignment film is formed
5a, 5b Film roll 5 Drying zone 6 Guide roller 7 Dust remover 8 Rubbing roller 9 Surface dust remover 10 Coating machine 11 Heating zone 12 Ultraviolet (UV) lamp 13 Inspection device 14 Protective film 15 Laminating machine

Claims (12)

An alignment film forming step of forming an alignment film by applying a composition for forming an alignment film containing a radical polymerizable group to at least one surface of the support, a rubbing step of rubbing the alignment film, and a rubbing treatment An optically anisotropic layer forming step of forming an optically anisotropic layer by applying a coating liquid containing a liquid crystalline compound on the alignment film subjected to
A method for producing an optical compensation film comprising a pretreatment step of crosslinking the radical polymerizable group before the optical anisotropic layer forming step.   The method for producing an optical compensation film according to claim 1, wherein a pretreatment step is performed before the rubbing step.   3. The method for producing an optical compensation film according to claim 1, wherein the pretreatment step is a treatment of irradiating the alignment film with ultraviolet rays of 60 mJ to 600 mJ.   The method for producing an optical compensation film according to any one of claims 1 to 3, wherein the radical polymerizable group is a (meth) acryloyl group.   A polymerization initiator that is radicalized by light is contained in the alignment film, and the content of the polymerization initiator is 0.05% by mass to 2.0% by mass with respect to the solid content of the polymer compound contained in the alignment film. The method for producing an optical compensation film according to any one of claims 1 to 4.   The method for producing an optical compensation film according to any one of claims 1 to 5, wherein the alignment film-forming composition contains a modified polyvinyl alcohol.   The adhesion providing treatment step of applying a saponification treatment by applying an alkaline solution having a water-soluble organic solvent and at least one of a surfactant and a compatibilizing agent before the alignment film forming step. A method for producing the optical compensation film according to claim 1.   The method for producing an optical compensation film according to claim 1, wherein the support is a cellulose acylate film.   An optical compensation film manufactured by the method for manufacturing an optical compensation film according to claim 1.   An alignment film forming step of forming an alignment film by applying a composition for forming an alignment film containing a radical polymerizable group on at least one surface of the support, a pretreatment step of crosslinking the radical polymerizable group, A rubbing step of rubbing the alignment film; and an optical anisotropic layer forming step of forming an optical anisotropic layer by applying a coating liquid containing a liquid crystalline compound on the alignment film subjected to the rubbing treatment; The optical compensation film according to claim 9, which is produced by:   A polarizing plate comprising the optical compensation film according to claim 9 and a polarizer.   A liquid crystal display device comprising the polarizing plate according to claim 11 and a liquid crystal cell.