JP2010083950A - Coating composition, method for manufacturing optical film, optical film, polarizing plate and liquid crystal display device of ocb (optically compensatory bend), tn (twisted nematic), va (vertical alignment) and ips (in-plane switching) modes - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating composition to suppress drastically the coating irregularity and drying ununiformity and to provide a related technique using the same. <P>SOLUTION: This coating composition includes a compound which is polymerizable with either the heating or the active energy-ray irradiation, and a solvent, wherein the above solvent contains two or more solvent components, and the two solvent components of A and B in the above solvent components, letting a boiling point temperature of the solvent component A be X(°C), and a boiling point temperature of the above solvent component B be Y(°C), they satisfy the following relationship, equation (1): X≤Y, and equation (2): 30<Y-X<80. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a coating composition using a solvent containing two kinds of solvent components having different boiling points, a method for producing an optical film, an optical film, a polarizing plate, and an OCB, TN, VA, and IPS mode liquid crystal display device.

  In recent years, liquid crystal display devices have been rapidly expanded for TV applications and increased in size, and the demand for display quality is increasing. The quality of films used in liquid crystal display panels is also increasing at the same time. Need to be improved.

  As a method of producing a film having a good productivity and a large size, after applying a coating composition having a polymerizable compound and a solvent, the film is dried to remove the solvent, and heat or active energy rays are used. A coating method in which the compound is polymerized by irradiation is suitable.

  However, in the coating method, when the solid content concentration is low after coating the coating composition, coating unevenness and drying unevenness of the coating film are likely to occur due to disturbances such as wind and vibration, and the film has a uniform and flat film thickness. There is a problem that it is difficult to get.

In order to solve these problems, it is known to use two or more kinds of solvent components having different characteristics for the solvent of the coating composition (see Patent Document 1).
According to Patent Document 1, it is possible to prevent film coating unevenness and drying unevenness to a certain extent according to the characteristics of each solvent component.

  However, there is no known structure that greatly improves such coating unevenness and drying unevenness, and there is no satisfactory film with a uniform and flattened (leveling) film. .

JP 2006-219632 A

  An object of the present invention is to solve the conventional problems and achieve the following objects. That is, an object of the present invention is to provide a coating composition that significantly suppresses coating unevenness and drying unevenness, and a related technique using the coating composition.

  As a result of intensive studies to achieve the above object, the inventors of the present invention, when the solvent in the coating composition contains a solvent component having a different boiling point, the low boiling point solvent is removed first, As a result, the solid content concentration can be increased, and the leveling effect is enhanced without being affected by disturbance. From here on, (1) To shorten the holding time at the low solid content concentration immediately after coating and to suppress the occurrence of film thickness unevenness, simply increase the drying temperature to accelerate the drying and shorten the holding time. Then, since Benard convection occurs, it is impossible to achieve significant suppression of film thickness unevenness. (2) The holding time in a state where the solid content concentration is higher is lengthened, and the leveling effect over time is promoted. (3) When leveling, we found that increasing the drying temperature reduces the viscosity and promotes leveling, and the first half drying is performed quickly, so a solvent component with a low boiling point is used. The inventors have found that by using a solvent component having a high boiling point, the leveling effect can be increased and the film thickness unevenness can be significantly suppressed, and the present invention has been completed.

The present invention is based on the above findings by the present inventors, and means for solving the above problems are as follows. That is,
<1> A coating composition having a compound polymerizable by either heat or active energy ray irradiation and a solvent, wherein the solvent contains two or more solvent components, and two types of the solvent components When the solvent components A and B have the boiling point temperature of the solvent component A as X (° C.) and the boiling point temperature of the solvent component B as Y (° C.), the relationship of the following formulas (1) and (2) It is a coating composition characterized by satisfy | filling.
X ≦ Y (1)
30 <YX <80 (2)
<2> When the mass of the solvent component A in the coating composition is L (kg) and the mass of the solvent component B in the coating composition is M (kg), the relationship between L and M is the following formula (3). It is a coating composition as described in said <1> which satisfy | fills.
10 ≦ M / (L + M) × 100 ≦ 90 (3)
<3> The coating composition according to <1> or <2>, wherein the polymerizable compound is a liquid crystal compound having a polymerizable group.
<4> The coating composition according to <3>, wherein the polymerizable compound is a discotic liquid crystal compound having a polymerizable group.
<5> A coating step of coating the coating composition according to any one of <1> to <4> on a support; and a solvent in the coating composition is volatilized, so that a solid content concentration of the solvent is 90%. A drying step of drying until the solid content concentration of the coating composition is 50%, and the solid content concentration of the coating composition is 50%. A first half drying temperature (° C.) of the first half drying step is different from the second half drying temperature (° C.), and the first half drying temperature (° C.) The latter half drying temperature (° C.), the boiling point temperature X (° C.) of the solvent component A, and the boiling point temperature Y (° C.) of the solvent component B satisfy the relationship of the following formulas (4) and (5). It is a manufacturing method of an optical film.
(X-60) <first half drying temperature <(X-10) (4)
(Y-60) <Late drying temperature <(Y-10) (5)
<6> An optical film produced by the production method according to <5>.
<7> A polarizing plate using the optical film according to <6>.
<8> An OCB, TN, VA, or IPS mode liquid crystal display device using the polarizing plate according to <7>.

  According to the present invention, the above-described problems can be solved and the object can be achieved, and the present invention relates to a coating composition that greatly suppresses coating unevenness and drying unevenness, and a relation using the coating composition. Providing technology can be provided.

(Coating composition)
The coating composition of the present invention is a coating composition having a compound polymerizable by heat or active energy ray irradiation and a solvent, wherein the solvent contains two or more solvent components, and 2 in the solvent components. When the boiling point temperature of the solvent component A is X (° C.) and the boiling point temperature of the solvent component B is Y (° C.), the following types (1) and (2) It is characterized by satisfying the relationship.
X ≦ Y (1)
30 <YX <80 (2)

<Solvent>
Two or more kinds of solvent components used in the coating composition will be described as solvent components A, B, C,.
The solvent A is not particularly limited as long as it can solubilize a polymerizable compound, and can be appropriately selected according to the purpose.
For example, as a solvent component having a boiling point of 100 ° C. or less (the numerical values in parentheses below indicate boiling point (° C.), surface tension (dyn / cm), viscosity (mPa · s) in this order), hexane (68 .7, 18.4, 0.313), heptane (98.4, 20.3, 0.418), cyclohexane (80.7, 25.3, 0.980), benzene (80.1, 28.28). 9, 0.649), dichloromethane (40.4, 28.1, 0.425), chloroform (61.2, 27.1, 0.563), carbon tetrachloride (76.7, 26.8, 0.965), 1,2-dichloroethane (83.5, 32.2, 0.840), halogenated hydrocarbons such as trichlorethylene (87.2, 29, 0.58), diethyl ether (34.6, 17.06, 0.23 ), Diisopropyl ether (68.5, 17.34, 0.329), ethers such as tetrahydrofuran (66, 16.5, 0.52), ethyl formate (54.2, 24.37, 0.419) , Methyl acetate (57.8, 24.76, 0.362), ethyl acetate (77.1, 23.9, 0.45), esters such as isopropyl acetate (89, 24.5, 0.569) , Ketones such as acetone (56.1, 23.7, 0.337), methyl ethyl ketone (MEK) (79.6, 24.6, 0.423), methanol (64.5, 22.55,. 59), ethanol (78.3, 22.1, 1.22), 2-propanol (82.4, 20.8, 2.41), 1-propanol (97.2, 23.8, 2.26). ) And other alcohols Cyano compounds such Tonitoriru (81.6,29.1,0.375), and the like carbon disulfide (46.2,32.25,0.363).

  Examples of the solvent component having a boiling point exceeding 100 ° C. include octane (125.6, 21.76, 0.542), toluene (110.6, 28.53, 0.587), xylene (138, 28.31). 0.644), tetrachlorethylene (121.2, 32.32, 0.88), chlorobenzene (131.5, 33.28, 0.803), dioxane (101.3, 34.45, 1.439) , Dibutyl ether (142.0, 23.40, 0.741), isobutyl acetate (118.3, 23.7, 0.697), cyclohexanone (155.7, 35.1, 2.45), 4- Methyl-2-pentanone (MIBK, 115.9, 25.4, 0.590), 1-pentanol (117.7, 25.60, 3.31), N, N-methylformamide ( 49.6,36.76,0.924), and the like.

  As the kind of the solvent component A, ketones, aromatic hydrocarbons, esters and alcohols are preferable, and ketones are more preferable. Of these, methyl ethyl ketone is particularly preferable.

The solvent component B satisfies the relationship of the following formulas (1) and (2) when the boiling temperature of the solvent component A is X (° C.) and the boiling temperature of the solvent component B is Y (° C.). It is.
X ≦ Y (1)
30 <YX <80 (2)
When the relationship of the expressions (1) and (2) is satisfied, the film thickness unevenness can be significantly suppressed without causing phase separation.

The solvent component B is not particularly limited as long as it satisfies the relationship of the expressions (1) and (2), and can be appropriately selected according to the purpose.
For example, when methyl ethyl ketone (MEK, 79.6, 24.6, 0.423) is selected as the solvent component A, the solvent component B may be 1-butanol (117.7, 23.8, 2. 95), 1-pentanol (137.8, 25.6, 3.31), diacetone alcohol (DAA, 167.9, 29.8, 3.2), octane (125.6, 21.76, 0.542), toluene (110.6, 28.53, 0.587), xylene (138, 28.31, 0.644), tetrachloroethylene (121.2, 32.32, 0.88), chlorobenzene ( 131.5, 33.28, 0.803), dibutyl ether (142.0, 23.40, 0.741), isobutyl acetate (118.3, 23.7, 0.697), cyclohexa (155.7, 35.1, 2.45), 4-methyl-2-pentanone (MIBK, 115.9, 25.4, 0.590), 1-pentanol (117.7, 25.60) 3.31), N, N-methylformamide (149.6, 36.76, 0.924) and the like.
When cyclohexanone (155.7, 35.1, 2.45) is selected as the solvent component A, the solvent component B includes dimethyl sulfoxide (189, 43, 2.14), propylene glycol (188). .2, 36.5, 56).

The method for determining the solvent in the case of containing three or more solvent components will be described below with an example of selecting three solvent components (solvent component A, solvent component B, solvent component C).
As the solvent component C, similarly to the solvent component B, the relationship of the above formulas (1) and (2) is satisfied (the boiling point temperature Y (° C.) of the solvent component B is the boiling point temperature Z (° C.) of the solvent component C). It is preferable that the boiling point temperature X (° C.) of the solvent component A and the boiling point temperature Z (° C.) of the solvent component C satisfy the relationship of the above formulas (1) and (2).
Therefore, when methyl ethyl ketone (79.6, 24.6, 0.423) is selected as the solvent component A, as the solvent component C, 1-butanol (117.7, 23.8, 2.95), 1-pentanol (137.8, 25.6, 3.31), diacetone alcohol (DAA, 167.9, 29.8, 3.2), octane (125. 6, 21.76, 0.542), toluene (110.6, 28.53, 0.587), xylene (138, 28.31, 0.644), tetrachlorethylene (121.2, 32.32, 0) .88), chlorobenzene (131.5, 33.28, 0.803), dibutyl ether (142.0, 23.40, 0.741), isobutyl acetate (118.3, 23.7, 0.697). , Cyclohexanone (155.7, 35.1, 2.45), 4-methyl-2-pentanone (MIBK, 115.9, 25.4, 0.590), 1-pentanol (117.7, 25. 60, 3.31), N, N-methylformamide (149.6, 36.76, 0.924) and the like.
When cyclohexanone (155.7, 35.1, 2.45) is selected as the solvent component A, dimethyl sulfoxide (189, 43, 2 and 2) is used as the solvent component C as in the case of the solvent component B. .14), propylene glycol (188.2, 36.5, 56) and the like.

Further, when the mass of the solvent component A in the coating composition is L (kg) and the mass of the solvent component B in the coating composition is M (kg), the relationship between L and M is expressed by the following formula (3). It is preferable to satisfy.
10 ≦ M / (L + M) × 100 ≦ 90 (3)
When L and M do not satisfy the relationship of the following formula (3), the leveling effect by the solvent components A and B cannot be sufficiently exhibited.
Further, the relationship between L and M and the numerical range (%) of M / (L + M) × 100 are more preferably 20 to 80.

  The viscosity of the coating composition is preferably 1 mPa · s to 6.5 mPa · s, more preferably 1 mPa · s to 3.5 mPa · s, from the viewpoint of solid content concentration and coatability.

The solid content concentration in the coating composition is preferably 1% by mass to 20% by mass, more preferably 1% by mass to 15% by mass, and even more preferably 1% by mass to 10% by mass. 1% by mass to 7% by mass is particularly preferable.
When the solid content concentration is from 1% by mass to 20% by mass, the wet film thickness at the time of application can be ensured in a good range, good applicability can be obtained, and drying unevenness is less likely to occur.

<Polymerizable compound>
There is no restriction | limiting in particular as said polymerizable compound, Although it can select suitably according to the objective, The liquid crystal compound which has a polymeric group is preferable.

-Liquid crystal compound having a polymerizable group-
The liquid crystal compound having a polymerizable group is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a rod-like liquid crystal compound and a discotic liquid crystal compound. Among these, a discotic liquid crystal compound is preferable. .

[Bar-shaped liquid crystal compound]
Examples of the rod-like liquid crystal compound 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, Chapters 4, 7, and 11 of the Quarterly Review of Chemical Review Vol. 22, “Chemicals of Liquid Crystal (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 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 the 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, page 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. Compounds are also included. The molecule or the assembly of molecules is preferably a compound having rotational symmetry and imparting a certain orientation.
Preferred examples of the discotic liquid crystal compound include paragraph numbers [0052] in JP-A-8-50206 and JP-A-2006-76992, and paragraph numbers [0040] in JP-A-2007-2220. To [0063].

For example, the compounds represented by the following general formulas (DI) and (DII) are preferable because they exhibit high birefringence.
Further, among the compounds represented by the following general formulas (DI) and (DII), compounds showing discotic liquid crystallinity are preferable, and compounds showing a discotic nematic phase are particularly preferable.

However, in said general formula (DI), R < ¹ >, R < ² > and R < ³ > represent the following general formula (DI-R) each independently.
H ¹ , H ² and H ³ each independently represent the following general formula (DI-A) or the following general formula (DI-B).
L ¹ , L ² and L ³ each independently represents a single bond or a divalent linking group.
Y ¹¹ , Y ¹² and Y ¹³ each independently represent a methine or nitrogen atom.

General formula (DI-R)
*-(-L ²¹ -Q ² ) _n1 -L ²² -L ²³ -Q ¹
(In the general formula (DI-R), * represents a position bonded to the H ^{1 to} H ³ side in the general formula (DI), L ²¹ represents a single bond or a divalent linking group, and Q ² represents at least 1; N1 represents an integer of 0 to 4, L ²² represents **-O-, **-O-CO-, **-CO-O-, * * -O-CO-O -, ** - S -, ** - NH -, ** - SO 2 -, ** - CH 2 -, ** - CH = CH- or ** - C≡C- ** represents a position bonded to the Q ² side, and L ²³ represents —O—, —S—, —C (═O) —, —SO ₂ —, —NH—, —CH ₂ —, -CH = CH- and -C≡C- and a divalent linking group selected from the group consisting of these, Q ¹ represents a polymerizable group or a hydrogen atom, and the polymerizable group contains a hydrogen atom When the hydrogen source If may be substituted with a substituent .n1 is 2 or more, a plurality of -L ²¹ -Q ² may each be the same or different.)

General formula DI-A
(In the general formula (DI-A), YA ¹ and YA ² each independently represents a methine or nitrogen atom, XA represents an oxygen atom, a sulfur atom, methylene or imino, and * represents the above general formula (DI). Represents the position of bonding to the L ^{1 to} L ³ side in **, and ** represents the position of bonding to the R ^{1 to} R ³ side in the general formula (DI).)

General formula DI-B
(In the general formula (DI-B), YB ¹ and YB ² each independently represent a methine or nitrogen atom, XB represents an oxygen atom, a sulfur atom, methylene or imino. * Represents the above general formula (DI) Represents the position of bonding to the L ^{1 to} L ³ side in **, and ** represents the position of bonding to the R ^{1 to} R ³ side in the general formula (DI).)

However, in said general formula (DII), LQ (or QL) means the combination of a bivalent coupling group (L) and polymeric group (Q). The divalent linking group (L) is a divalent linking group selected from the group consisting of an alkylene group, an alkenylene group, an arylene group, —CO—, —NH—, —O—, —S—, and combinations thereof. Preferably there is. The divalent linking group (L) is a combination of at least two divalent groups selected from the group consisting of an alkylene group, an arylene group, —CO—, —NH—, —O—, and —S—. More preferably, it is a valent 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.
The polymerizable group (Q) is determined according to the type of polymerization reaction. The polymerizable group (Q) is preferably an unsaturated polymerizable group or an epoxy group, more preferably an unsaturated polymerizable group, and particularly preferably an ethylenically unsaturated polymerizable group.

  In addition, preferable examples of the discotic liquid crystal compound include compounds described in JP-A-2005-301206.

(Optical film manufacturing method)

  The method for producing an optical film of the present invention includes a coating process and a drying process. Moreover, other processes are included as necessary. There is no restriction | limiting in particular as another process, According to the objective, it can select suitably, The well-known process known as a manufacturing method of an optical film can be used.

<Application process>
The coating step is a step of coating the coating composition on a support.
Examples of coating methods include curtain coating, dip coating, spin coating, print coating, spray coating, slot coating, roll coating, slide coating, blade coating, gravure coating, and wire bar. Known coating methods such as a method are listed.
You may heat when drying a coating film. The coating film is dried to remove the solvent, and at the same time, the molecules of the liquid crystal compound in the coating film are aligned to obtain a desired alignment state.

<Drying process>
The drying step is a drying step in which the solvent in the coating composition is volatilized and the solid content concentration of the solvent is dried to 90%.

  In the drying step, the first half drying step is performed such that the solid content concentration of the coating composition is 50%, and the second half drying step is performed so that the solid concentration of the coating composition is 50% or more. The first half drying temperature (° C.) of the first half drying step is different from the second half drying temperature (° C.).

The solid content concentration here means
Solid content concentration (%) = solid content / (volatile content + solid content) × 100
It is.
The solid content and (volatile content + solid content) can be obtained by the following equations (6) and (7) by weight measurement.
Solid content = [A: Weight of film after drying] − [B: Weight of support before coating] (6)
Volatile content + solid content = [C: weight of film sampled in a certain drying zone] − [B: weight of support before coating] (7)

As the first half drying temperature (° C.) and the second half drying temperature (° C.), these temperatures are the boiling temperature X (° C.) of the solvent component A and the boiling temperature Y (° C.) of the solvent component B. On the other hand, it is preferable to satisfy the relationship of following formula (4) and (5).
(X-60) <First half drying temperature <(X-10) (4)
(Y-60) <Late drying temperature <(Y-10) (5)
When the above formulas (4) and (5) are satisfied, the low boiling point solvent component A (boiling point temperature X) is removed by the first half drying, and the high boiling point solvent component B (boiling point temperature Y) is removed by the second half drying. Is done. At this time, the holding time on the support of the coating composition containing the solvent component A can be shortened from the start of drying, and the holding time of the coating composition containing the solvent component B on the support. Therefore, the leveling effect can be increased and the film thickness unevenness can be significantly suppressed.

  Hereinafter, although the manufacturing process of an optical film is illustrated and demonstrated with an accompanying drawing, it is not restricted to these as a manufacturing process of the optical film in this invention. FIG. 1 is a diagram showing an outline of a manufacturing process of an optical film. As the applicator 3, for example, a bar applicator provided with a wire bar can be used and is supported by a plurality of backup rollers and travels. A coating liquid is applied to the lower surface of the web to form a coating film. In the present invention, the drying device 10 is preferably divided into the first-half drying zone 4 and the second-half drying zone 5 and the temperature can be freely controlled. As a heating method, a method of controlling the temperature with a heater adjacent to the coating film or a method of controlling the temperature of the supply air by supplying and exhausting air in the drying zone may be used. The zone lengths of the first half drying zone 4 and the second half drying zone 5 can be arbitrarily set, and are preferably set in consideration of the coating speed, the amount of solvent applied and the drying time.

(Optical film)
The optical film of the present invention is characterized by being produced by the method for producing an optical film using the coating composition, and further preferably includes other optical film configurations as necessary.

  As the optical film, the coating composition as a composition containing at least one liquid crystal compound is disposed on the surface (for example, the alignment film surface), the molecules of the liquid crystal compound are brought into a desired alignment state, and cured by polymerization. The alignment state is preferably fixed. The orientation state to be fixed is preferably a hybrid orientation state. Hybrid alignment refers to an alignment state in which the director direction of liquid crystal molecules continuously changes in the layer thickness direction. In the case of a rod-like molecule, the director is in the major axis direction, and in the case of a disc-like molecule, the director is in the direction perpendicular to the disc surface.

The coating composition may contain one or more additives in order to bring the molecules of the liquid crystal compound into a desired alignment state and to improve the coating property or curability of the coating composition.
In order to hybrid-align the molecules of the liquid crystal compound (particularly rod-shaped liquid crystal compound), an additive capable of controlling the orientation of the layer on the air interface side (hereinafter referred to as “air interface orientation control agent”) may be added. Examples of the additive include low molecular weight or high molecular weight compounds having hydrophilic groups such as fluorinated alkyl groups and sulfonyl groups. Specific examples of usable air interface orientation control agents include compounds described in JP-A No. 2006-267171.

  Moreover, you may add surfactant to the said coating composition for the improvement of applicability | paintability. As the surfactant, a fluorine-based compound is preferable, and specific examples include compounds described in paragraph numbers [0028] to [0056] in JP-A-2001-330725. Commercially available “Megafac F780” (manufactured by Dainippon Ink & Chemicals, Inc.) may also be used.

Moreover, it is preferable that the coating composition contains a polymerization initiator. The polymerization initiator may be a thermal polymerization initiator or a photopolymerization initiator, but a photopolymerization initiator is preferable from the viewpoint of easy control. Examples of photopolymerization initiators that generate radicals by the action of light include α-carbonyl compounds (described in US Pat. Nos. 2,367,661 and 2,367,670) and acyloin ethers (described in US Pat. No. 2,448,828). ), Α-hydrocarbon-substituted aromatic acyloin compounds (described in US Pat. No. 2,722,512), polynuclear quinone compounds (described in US Pat. Nos. 3,046,127 and 2,951,758), triarylimidazole dimers and p-amino Combination with phenyl ketone (described in US Pat. No. 3,549,367), acridine and phenazine compounds (described in JP-A-60-105667, US Pat. No. 4,239,850) and oxadiazole compounds (US Pat. No. 4,221,970) Description), acetophenone series Compounds, benzoin ether compounds, benzyl compounds, benzophenone compounds, thioxanthone compounds and the like are preferable. Examples of the acetophenone compound include 2,2-diethoxyacetophenone, 2-hydroxymethyl-1-phenylpropan-1-one, 4′-isopropyl-2-hydroxy-2-methyl-propiophenone, 2-hydroxy -2-methyl-propiophenone, p-dimethylaminoacetone, p-tert-butyldichloroacetophenone, p-tert-butyltrichloroacetophenone, p-azidobenzalacetophenone and the like. Examples of the benzyl compound include benzyl, benzyl dimethyl ketal, benzyl-β-methoxyethyl acetal, 1-hydroxycyclohexyl phenyl ketone and the like. Examples of benzoin ether compounds include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin-n-propyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, and benzoin isobutyl ether. Examples of the benzophenone compound include benzophenone, methyl o-benzoylbenzoate, Michler's ketone, 4,4′-bisdiethylaminobenzophenone, 4,4′-dichlorobenzophenone, and the like. Examples of the thioxanthone compound include thioxanthone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-diethylthioxanthone, and the like. Among such photosensitive radical polymerization initiators composed of aromatic ketones, acetophenone compounds and benzyl compounds are particularly preferable in terms of curing characteristics, storage stability, odor, and the like. The photosensitive radical polymerization initiators composed of these aromatic ketones can be used alone or in combination of two or more according to the desired performance.
In addition to a polymerization initiator, a sensitizer may be used for the purpose of increasing sensitivity. Examples of the sensitizer include n-butylamine, triethylamine, tri-n-butylphosphine, thioxanthone and the like.

  The said photoinitiator may combine multiple types, It is preferable that the usage-amount is 0.01 mass%-20 mass% of solid content of a coating liquid, and is 0.5 mass%-5 mass%. It is more preferable. The light irradiation for polymerization of the liquid crystal compound preferably uses ultraviolet rays.

Apart from the polymerizable liquid crystal compound, the coating composition may contain a non-liquid crystalline polymerizable monomer. As the polymerizable monomer, a compound having a vinyl group, a vinyloxy group, an acryloyl group or a methacryloyl group is preferable. In addition, it is preferable to use a polyfunctional monomer having two or more polymerizable reactive functional groups, for example, ethylene oxide-modified trimethylolpropane acrylate because durability is improved.
Since the non-liquid crystalline polymerizable monomer is a non-liquid crystalline component, the addition amount thereof does not exceed 15% by mass with respect to the liquid crystal compound, and is preferably about 0 to 10% by mass.

  The optical film is prepared by using the coating composition as a coating solution, and applying the coating solution to, for example, the surface of an alignment film formed on a support, removing the solvent in the drying step, and The liquid crystal compound molecules can be oriented and then cured by polymerization to form.

Next, polymerization is advanced by ultraviolet irradiation or the like to fix the alignment state, thereby forming the optical film. It is preferable to use ultraviolet rays for light irradiation for polymerization. The irradiation energy is preferably 20 mJ / cm ^{2 to} 50 J / cm ² , and more preferably 100 mJ / cm ^{2 to} 800 mJ / cm ² . In order to accelerate the photopolymerization reaction, light irradiation may be performed under heating conditions.

  There is no restriction | limiting in particular in the thickness of the said optical film, Although it can select suitably according to the objective, 0.1 micrometer-10 micrometers are preferable, and 0.5 micrometer-5 micrometers are more preferable.

  The optical film is preferably formed using an alignment film. Examples of the alignment film that can be used include a polyvinyl alcohol film and a polyimide film.

(Polarizer)
The polarizing plate of the present invention is characterized by using the optical film manufactured by the method for manufacturing the optical film using the coating composition.
The polarizing plate is not particularly limited as long as it includes the optical film, and can be appropriately selected according to the purpose. For example, the polarizing plate has a polarizer and further has other configurations as necessary. Have.

(Polarizer)
The polarizer is manufactured by Optiva Inc. And a polarizer composed of a binder and iodine or a dichroic dye are preferable.
The iodine and the dichroic dye exhibit 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 such as liquid crystal.
Commercially available polarizers are made by immersing a stretched polymer in a solution of iodine or dichroic dye in a bath and allowing iodine or dichroic dye to penetrate into the binder. It is common.
In addition, commercially available polarizers have iodine or dichroic dye distributed about 4 μm from the polymer surface (about 8 μm on both sides), and a thickness of at least 10 μm is necessary to obtain sufficient polarization performance. is there. The penetrability can be controlled by the solution concentration of iodine or dichroic dye, the temperature of the bath, and the immersion time.
Therefore, as described above, the lower limit of the binder thickness is preferably 10 μm. The upper limit of the thickness 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. It is preferably not more than a commercially available polarizing plate (about 30 μm), preferably 25 μm or less, and more preferably 20 μm or less. When the thickness is 20 μm or less, the light leakage phenomenon is not observed on a 17-inch liquid crystal display device.

The binder of the polarizer may be cross-linked. As the binder for the polarizer, a polymer that can be crosslinked by itself may be used. Applying light, heat, or pH change to a polymer having a functional group, or a polymer obtained by introducing a functional group into the polymer, reacting the functional group to crosslink between the polymers to form a polarizer. it can.
Moreover, you may introduce | transduce a crosslinked structure into a polymer with a crosslinking agent. It can be formed by cross-linking between binders by introducing a bonding group derived from the cross-linking agent between binders using a cross-linking agent which is a compound having high reaction activity.
In general, the crosslinking can be carried out by applying a coating liquid containing a crosslinkable polymer or a mixture of a polymer and a crosslinking agent on a support and then heating. Since it is only necessary to ensure durability at the stage of the final product, the crosslinking treatment may be performed at any stage until the final polarizing plate is obtained.

As described above, as the binder of the polarizer, either a polymer that can be crosslinked by itself or a polymer that is crosslinked by a crosslinking agent can be used.
Examples of polymers include polymethyl methacrylate, polyacrylic acid, polymethacrylic acid, polystyrene, polyvinyl alcohol, modified polyvinyl alcohol, poly (N-methylol acrylamide), polyvinyl toluene, chlorosulfonated polyethylene, nitrocellulose, chlorinated polyolefin ( Eg, polyvinyl chloride), polyester, polyimide, polyvinyl acetate, polyethylene, carboxymethylcellulose, polypropylene, polycarbonate and copolymers thereof (eg, acrylic acid / methacrylic acid copolymer, styrene / maleimide copolymer, styrene / vinyl) Toluene copolymer, vinyl acetate / vinyl chloride copolymer, ethylene / vinyl acetate copolymer). A silane coupling agent may be used as the polymer.
Water-soluble polymers (eg, poly (N-methylolacrylamide), carboxymethylcellulose, gelatin, polyvinyl alcohol and modified polyvinyl alcohol) are preferred, gelatin, polyvinyl alcohol and modified polyvinyl alcohol are more preferred, and polyvinyl alcohol and modified polyvinyl alcohol are particularly preferred. .

The saponification degree of polyvinyl alcohol and modified polyvinyl alcohol is preferably 70 to 100%, more preferably 80 to 100%, and particularly preferably 95 to 100%. The polymerization degree of polyvinyl alcohol is preferably 100 to 5,000.
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 a modifying group. In 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. The modified polyvinyl alcohol is described in JP-A-8-338913, JP-A-9-152509, and JP-A-9-316127.
Further, unmodified polyvinyl alcohol having a saponification degree of 85 to 95% and alkylthio-modified polyvinyl alcohol are particularly preferable.
Furthermore, two or more kinds of polyvinyl alcohol and modified polyvinyl alcohol may be used in combination.

The crosslinking agent is described in US Reissue Patent 23297 and can be used in the present invention. Boron compounds (eg, boric acid, borax) can also be used as a crosslinking agent.
When a large amount of the crosslinking agent for the binder is added, the wet heat resistance of the polarizer 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. 0.1-20 mass% is preferable with respect to a binder, and, as for the addition amount of a crosslinking agent, 0.5-15 mass% is still more preferable.
The binder contains 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 polarizer with 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 dichroic dye include azo dyes, stilbene dyes, pyrazolone dyes, triphenylmethane dyes, quinoline dyes, oxazine dyes, thiazine dyes, and anthraquinone dyes. The dichroic dye is preferably water-soluble. The dichroic dye preferably has a hydrophilic substituent (eg, sulfo, amino, hydroxyl).
Examples of dichroic dyes 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 is included.
Regarding the dichroic dyes, JP-A-1-161202, JP-A-1-172906, JP-A-1-172907, JP-A-1-183602, JP-A-1-248105, JP-A-1 -265205 and JP-A-7-261024.

  The dichroic dye is used as a free acid or a salt such as an alkali metal salt, an ammonium salt, or an amine salt. By blending two or more types of dichroic dyes, polarizers having various hues can be produced. A polarizer using a compound (pigment) that exhibits a black color when the polarization axes are orthogonal to each other, or a polarizer or a polarizing plate in which various dichroic molecules are blended so as to exhibit a black color, have both a single plate transmittance and a polarization rate. Excellent and preferred.

  The polarizer is preferably dyed with iodine or a dichroic dye after stretching the binder in the longitudinal direction (MD direction) of the polarizer.

In the case of the stretching method, the stretching ratio is preferably 2.5 to 30.0 times, and more preferably 3.0 to 10.0 times. Stretching can be performed by dry stretching in air.
Moreover, you may implement wet extending | stretching in the state immersed in water. The stretch ratio of dry stretching is preferably 2.5 to 5.0 times, and the stretch ratio of wet stretching is preferably 3.0 to 10.0 times.
The stretching step may be performed in several steps. By dividing into several times, it is possible to stretch more uniformly even at high magnification.
Before stretching, a slight stretching may be performed horizontally or vertically (a degree that prevents 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.

Moreover, when using the polarizing plate of this invention for a liquid crystal display device, it is preferable to install an antireflection layer on the surface on the viewing side, and the antireflection layer may also be used as a protective layer on the viewing side of the polarizer.
From the viewpoint of suppressing a change in tint depending on the viewing angle of the liquid crystal display device, the internal haze of the antireflection layer is preferably 50% or more. Specific examples of these are described in JP-A No. 2001-33783, JP-A No. 2001-343646, and JP-A No. 2002-328228.

In order to increase the contrast ratio of the liquid crystal display device, the transmittance of the polarizer is preferably high and the degree of polarization is preferably high.
The transmittance of the polarizer of the present invention is preferably in the range of 30 to 50%, more preferably in the range of 35 to 50%, and in the range of 40 to 50% in light having a wavelength of 550 nm. Is particularly preferred.
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.

[Production method of polarizing plate]
A polarizing plate can be manufactured by bonding a polarizer to the optical film using a known technique.

(Liquid crystal display device)
The liquid crystal display device of the present invention is characterized by using the polarizing plate, and is used for an OCB liquid crystal display device, a TN liquid crystal display device, a VA liquid crystal display device, and an ISP liquid crystal display device. is there.
The liquid crystal display device includes at least the polarizing plate and a liquid crystal cell.

The polarizing plate using the optical film of the present invention is advantageously used for a liquid crystal display device that is difficult to display black / white unless an optical film is attached, such as a liquid crystal display device of a birefringence mode, particularly an OCB type liquid crystal display device. .
The transmissive liquid crystal display device includes a liquid crystal cell and two polarizing plates disposed on both sides thereof. The liquid crystal cell carries a liquid crystal between two electrode substrates.
One optical film is disposed between the liquid crystal cell and one polarizing plate, or two optical films are disposed between the liquid crystal cell and both polarizing plates.

The OCB mode liquid crystal cell is a liquid crystal display device using a bend alignment mode liquid crystal cell in which rod-like liquid crystalline molecules are aligned in a substantially opposite direction (symmetrically) between the upper part and the lower part of the liquid crystal cell. No. 4,583,825 and U.S. Pat. No. 5,410,422. Since the rod-like liquid crystal molecules are aligned symmetrically between the upper part and the lower part of the liquid crystal cell, the bend alignment mode liquid crystal cell has a self-optical compensation function.
For this reason, this liquid crystal mode is also called an OCB (Optically Compensatory Bend) liquid crystal mode. The bend alignment mode liquid crystal display device has an advantage of high response speed.
In addition, since the OCB method can be driven at high speed, it is preferably combined with the field sequential driving method.

  The liquid crystal cell used in the liquid crystal display device of the present invention has a Δnd value of 800 or more and 1,200 in a no-voltage application state (under the alignment state of the liquid crystal material in the liquid crystal cell in a state where no voltage is applied to the liquid crystal layer). It is preferable that it is less than.

Examples of the present invention will be described below, but the present invention is not limited to the following examples.
(1) Optical film production method

<Production of Support S-1>
<< Preparation of cellulose acetate solution >>
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]
Cellulose acetate having an acetylation degree of 60.9% 100 parts by mass Triphenyl phosphate 7.8 parts by mass Biphenyl diphenyl phosphate 3.9 parts by mass Methylene chloride 300 parts by mass Methanol 45 parts by mass

  In another mixing tank, 4 parts by mass of cellulose acetate (linter) having an acetylation degree of 60.9%, 25 parts by mass of the following retardation increasing agent, 0.5 parts by mass of silica fine particles (average particle size: 20 nm), methylene chloride 80 parts by mass and 20 parts by mass of methanol were added and stirred while heating to prepare a retardation increasing agent solution.

  The retardation increasing agent solution was mixed with 470 parts by mass of the cellulose acetate solution, and the dope was prepared by sufficiently stirring. The mass ratio of the retardation increasing agent to cellulose acetate was adjusted to adjust the desired optical properties.

<Preparation of alignment film>
On the saponified support S-1, an alignment film coating solution having the composition shown in Table 1 below was applied at 28 mL / m ² with a # 16 wire bar coater. 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. The thickness of the alignment film after drying was 1.1 μm.

<Alignment film coating solution composition>

-Modified polyvinyl alcohol-

<Orientation treatment>
A rubbing roll is set so that the support S-1 coated with the alignment film is rubbed at 90 ° with respect to the stretching direction, and rotated at 450 rpm to rub the alignment film installation surface. gave.

(2) Evaluation method Two polarizing plates placed in a dark room and having a high-luminance backlight are placed in a straight line, and the above-prepared sample is sandwiched between polarizing plates placed on the shakasten and transmitted through the polarizing plate. The shaft and the rubbing shaft of the sample were set so as to be 45 °, and visual sensory evaluation was performed.
◎ ⇒ Unevenness cannot be recognized ○ ⇒ Slightly visible but not bothering △ ⇒ Visible × ⇒ Visible clearly

(3) Example (Example 1)
<Preparation of coating composition>
According to the coating of the optical film, in the SUS pot, methyl ethyl ketone (MEK, boiling point 80 ° C.) as solvent component A (122.4 parts by mass) and 4-methyl- as solvent component B (81.6 parts by mass). 2-Pentanone (MIBK, boiling point 116 ° C.) was added to prepare a solvent so that the ratio of the solvent component B in the solvent was 40%.
In 204.0 parts by mass of this solvent, 90 parts by mass of the following discotic compound A, 10 parts by mass of the following discotic compound B, 3 parts by mass of a photopolymerization initiator (Irgacure 907, manufactured by Ciba Geigy), sensitizer (Kayacure DETX) , Nippon Kayaku Co., Ltd.) 1 part by mass was dissolved to prepare a coating composition.

Discotic liquid crystal compound A; discotic liquid crystal compound described as D-112 in JP-A-2006-76992
Discotic liquid crystal compound B: Discotic liquid crystal compound described in Japanese Patent Application Laid-Open No. 2001-166144 as Chemical formula 44

<Application process>
As shown in FIG. 1, a coating machine 3 is used on the support S-1 supplied from the delivery unit 1 and subjected to the orientation treatment (rubbing treatment) in the rubbing treatment unit 2 by a bar coater method. The said coating composition was apply | coated with the coating amount of 5.52 mL / m < ² > with the wire bar of 3.2, and the coating film of a state with low solid content concentration was formed.

<Drying process>
After the first half drying was performed at the first half drying temperature of 50 ° C. in the first half drying zone 4 and sufficient time was taken for the MEK as the solvent A to be dried (state where the solid content concentration was 50% or more). In the latter half drying zone 5, the latter half drying was subsequently performed at the latter half drying temperature of 50 ° C. to remove the solvent. The time for passing through the first and second drying zones was 20 seconds each.
In addition, it confirmed that the solid content density | concentration of a coating film was 50% or more by measuring the film thickness of a coating film using a non-contact infrared film thickness meter (Kurabo Co., Ltd .; KG-300CM).

<Production of optical film>
The coating film from which the solvent was removed was allowed to stay in the heating zone 6 at 130 ° C. for 2 minutes to align the liquid crystal compound. Next, ultraviolet rays were irradiated at 90 ° C. using a 120 W / cm high-pressure mercury lamp (UV irradiation device 7) to polymerize the discotic liquid crystal compound, and then allowed to cool to room temperature. Thus, an optical film using the coating composition of Example 1 was produced.
About the optical film which concerns on this Example 1, the film thickness nonuniformity was evaluated with the evaluation method of said (2). The results are shown in Table 2 below.

(Example 2)
The coating composition of Example 2 was the same as Example 1 except that cyclohexanone (boiling point 156 ° C.) was used as the solvent component B instead of 4-methyl-2-pentanone (MIBK, boiling point 116 ° C.). A product was prepared.
Also, the same coating process, drying process, and production of an optical film as those in Example 1 were performed to produce an optical film according to Example 2.
About the optical film which concerns on this Example 2, the film thickness nonuniformity was evaluated with the evaluation method of said (2). The results are shown in Table 2 below.

(Example 3)
Example 3 is the same as Example 2 except that 4-methyl-2-pentanone (MIBK, boiling point 116 ° C.) is used in place of methyl ethyl ketone (MEK, boiling point 80 ° C.) as the solvent component A. A coating composition was prepared.
Moreover, the same coating process, drying process, and preparation of an optical film as Example 1 were performed, and the optical film which concerns on Example 3 was produced.
About the optical film which concerns on this Example 3, the film thickness nonuniformity was evaluated with the evaluation method of said (2). The results are shown in Table 2 below.

Example 4
A coating composition of Example 4 was prepared in the same manner as Example 3 except that diacetone alcohol (DAA, boiling point 168 ° C.) was used instead of cyclohexanone (boiling point 116 ° C.) as solvent component B. .
Moreover, the same coating process, drying process, and preparation of an optical film as Example 1 were performed, and the optical film which concerns on Example 4 was produced.
About the optical film which concerns on this Example 4, the film thickness nonuniformity was evaluated with the evaluation method of said (2). The results are shown in Table 2 below.

(Example 5)
In the same manner as in Example 2, the coating composition of Example 5 was prepared.
The drying process was performed in the same manner as in Example 2 except that the latter half drying temperature was changed from 50 ° C to 130 ° C.
Moreover, the same coating process as Example 1 and preparation of an optical film were performed, and the optical film which concerns on Example 5 was produced.
About the optical film which concerns on this Example 5, the film thickness nonuniformity was evaluated with the evaluation method of said (2). The results are shown in Table 2 below.

(Example 6)
In the same manner as in Example 4, a coating composition of Example 6 was prepared.
The drying process was performed in the same manner as in Example 4 except that the first half drying temperature was changed from 50 ° C. to 80 ° C. and the second half drying temperature was changed from 50 ° C. to 140 ° C.
Moreover, the same application process as Example 1 and the production of an optical film were performed, and the optical film according to Example 6 was produced.
About the optical film which concerns on this Example 6, the film thickness nonuniformity was evaluated with the evaluation method of said (2). The results are shown in Table 2 below.

(Example 7)
In the same manner as in Example 2, a coating composition of Example 7 was prepared.
The drying process was performed in the same manner as in Example 2 except that the first half drying temperature was changed from 50 ° C. to 10 ° C. and the second half drying temperature was changed from 50 ° C. to 130 ° C.
Moreover, the same application process as Example 1 and production of an optical film were performed, and the optical film which concerns on Example 7 was produced.
About the optical film which concerns on this Example 7, the film thickness nonuniformity was evaluated with the evaluation method of said (2). The results are shown in Table 2 below.

(Example 8)
In the same manner as in Example 2, a coating composition of Example 8 was prepared.
The drying process was performed in the same manner as in Example 2 except that the first half drying temperature was changed from 50 ° C. to 80 ° C. and the second half drying temperature was changed from 50 ° C. to 130 ° C.
In addition, an optical film according to Example 8 was manufactured by performing the same coating process and optical film as those of Example 1.
About the optical film which concerns on this Example 8, the film thickness nonuniformity was evaluated with the evaluation method of said (2). The results are shown in Table 2 below.

Example 9
In the same manner as in Example 2, a coating composition of Example 8 was prepared.
The drying process was performed in the same manner as in Example 2 except that the latter half drying temperature was changed from 50 ° C to 80 ° C.
In addition, an optical film according to Example 9 was manufactured by performing the same coating process and optical film as in Example 1.
About the optical film which concerns on this Example 9, the film thickness nonuniformity was evaluated with the evaluation method of said (2). The results are shown in Table 2 below.

(Example 10)
In the same manner as in Example 2, the coating composition of Example 10 was prepared.
The drying process was performed in the same manner as in Example 2 except that the latter half drying temperature was changed from 50 ° C to 160 ° C.
Moreover, the same application process as Example 1 and the production of an optical film were performed, and the optical film according to Example 10 was produced.
About the optical film which concerns on this Example 10, the film thickness nonuniformity was evaluated with the evaluation method of said (2). The results are shown in Table 2 below.

(Example 11)
Except that the addition amount of the solvent component A was 173.4 parts by mass, the addition amount of the solvent component B was 30.6 parts by mass, and the ratio of the solvent component B in the solvent was 15%, the same as Example 5 A coating composition of Example 11 was prepared.
Further, the same coating process, drying process, and production of an optical film as those in Example 5 were carried out to produce an optical film according to Example 11.
About the optical film which concerns on this Example 11, the film thickness nonuniformity was evaluated with the evaluation method of said (2). The results are shown in Table 2 below.

Example 12
Except that the addition amount of the solvent component A was 30.6 parts by mass, the addition amount of the solvent component B was 173.4 parts by mass, and the ratio of the solvent component B in the solvent was 85%, the same as in Example 5. A coating composition of Example 12 was prepared.
Also, the same coating process, drying process, and production of an optical film as those in Example 5 were performed to produce an optical film according to Example 12.
About the optical film which concerns on this Example 12, film thickness nonuniformity was evaluated with the evaluation method of said (2). The results are shown in Table 2 below.

<Comparative Example 1>
A coating composition of Comparative Example 1 was prepared in the same manner as in Example 1 except that the solvent component B was not added.
Moreover, the application | coating process similar to Example 1, the drying process, and preparation of the optical film were performed, and the optical film which concerns on the comparative example 1 was produced.
About the optical film which concerns on this comparative example 1, film thickness nonuniformity was evaluated with the evaluation method of said (2). The results are shown in Table 2 below.

<Comparative example 2>
A coating composition of Comparative Example 2 was prepared in the same manner as in Example 1 except that the solvent component B was not added.
The drying process was performed in the same manner as in Example 1 except that the first half drying temperature was changed from 50 ° C. to 25 ° C. and the second half drying temperature was changed from 50 ° C. to 25 ° C.
Moreover, the same application process as Example 1 and the production of an optical film were performed, and the optical film according to Comparative Example 2 was produced.
About the optical film which concerns on this comparative example 2, film thickness nonuniformity was evaluated with the evaluation method of said (2). The results are shown in Table 2 below.

<Comparative Example 3>
A coating composition of Comparative Example 3 was prepared in the same manner as in Example 1 except that the solvent component B was not added.
The drying process was performed in the same manner as in Example 1 except that the first half drying temperature was changed from 50 ° C. to 80 ° C. and the second half drying temperature was changed from 50 ° C. to 80 ° C.
In addition, an optical film according to Comparative Example 3 was manufactured by performing the same coating process and optical film as those of Example 1.
About the optical film which concerns on this comparative example 3, the film thickness nonuniformity was evaluated with the evaluation method of said (2). The results are shown in Table 2 below.

<Comparative example 4>
Comparative Example 3 was the same as Example 1 except that 1-propanol (boiling point 97 ° C.) was used instead of 4-methyl-2-pentanone (MIBK, boiling point 116 ° C.) as the solvent component B. A coating composition was prepared.
Moreover, the application | coating process similar to Example 1, the drying process, and preparation of the optical film were performed, and the optical film which concerns on the comparative example 4 was produced.
About the optical film which concerns on this comparative example 4, the film thickness nonuniformity was evaluated with the evaluation method of said (2). The results are shown in Table 2 below.

<Comparative Example 5>
Comparative Example as in Example 1 except that diacetone alcohol (DAA, boiling point 168 ° C.) was used instead of 4-methyl-2-pentanone (MIBK, boiling point 116 ° C.) as solvent component B 5 coating compositions were prepared.
In addition, the same coating process, drying process, and production of an optical film as those in Example 1 were performed to produce an optical film according to Comparative Example 5.
About the optical film which concerns on this comparative example 5, film thickness nonuniformity was evaluated with the evaluation method of said (2). The results are shown in Table 2 below.

FIG. 1 is a diagram showing an outline of a manufacturing process of an optical film.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Delivery part 2 Rubbing process part 3 Coating machine 4 First half drying zone 5 Second half drying zone 6 Heating zone 7 UV irradiation apparatus 8 Winding part 10 Drying apparatus

Claims (8)

A coating composition comprising a compound polymerizable by either heat or active energy ray irradiation and a solvent, wherein the solvent contains two or more kinds of solvent components, and two kinds of solvent components A in the solvent components And B satisfy the relationship of the following formulas (1) and (2) when the boiling temperature of the solvent component A is X (° C.) and the boiling temperature of the solvent component B is Y (° C.). A characteristic coating composition.
X ≦ Y (1)
30 <YX <80 (2) Claim that L and M satisfy the relationship of the following formula (3), where L (kg) is the mass of solvent component A in the coating composition and M (kg) is the mass of solvent component B of the coating composition. Item 4. The coating composition according to Item 1.
10 ≦ M / (L + M) × 100 ≦ 90 (3)   The coating composition according to claim 1, wherein the polymerizable compound is a liquid crystal compound having a polymerizable group.   The coating composition according to claim 3, wherein the polymerizable compound is a discotic liquid crystal compound having a polymerizable group. An application step of applying the coating composition according to any one of claims 1 to 4 to a support;
And evaporating the solvent in the coating composition, and drying the solid content concentration of the solvent to 90%,
Furthermore, the drying step includes a first half drying step in which the solid content concentration of the coating composition is 50%, and a second half in which the solid content concentration of the coating composition is 50% or more. A drying process,
The first half drying temperature (° C.) of the first half drying step is different from the second half drying temperature (° C.), and the first half drying temperature (° C.), the second half drying temperature (° C.), and the boiling point temperature X ( ° C) and the boiling point temperature Y (° C) of the solvent component B satisfy the relationship of the following formulas (4) and (5).
(X-60) <first half drying temperature <(X-10) (4)
(Y-60) <Late drying temperature <(Y-10) (5)   An optical film produced by the production method according to claim 5.   A polarizing plate using the optical film according to claim 6.   An OCB, TN, VA, or IPS mode liquid crystal display device using the polarizing plate according to claim 7.