JP2009086379A - Optical compensation film, polarizing plate, and liquid crystal display device - Google Patents

Abstract

An optical compensation film excellent in retardation adjustment, a polarizing plate using the optical compensation film, and a liquid crystal display device having the polarizing plate are provided.
An optical compensation film comprising two or more layers disposed between at least one liquid crystal cell and a polarizing film, comprising at least a first optical anisotropic layer and a second optical anisotropic layer. The angle formed between the slow axis of the second optically anisotropic layer and the slow axis of the first optically anisotropic layer is 0 ° to 42 ° or 48 ° to 90 °. Optical compensation film.
[Selection] Figure 1

Description

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

  As a liquid crystal display device (LCD), for example, one having a liquid crystal cell containing rod-like liquid crystal molecules and a pair of polarizing plates sandwiching the liquid crystal cell is known. The polarizing plate of the liquid crystal display device (LCD) includes an optical compensation film for adjusting the phase difference of light transmitted through the liquid crystal cell.

  As the optical compensation film, for example, an optically anisotropic layer containing a discotic compound is formed on a support such as triacetyl cellulose (TAC) having excellent permeability and optical isotropy. (For example, Patent Document 1).

  In recent years, liquid crystal display devices are sometimes used in vehicles as car navigation systems, instrumental panels, head-up displays, and the like.

  An OCB (Optically Compensatory Bend) mode liquid crystal cell is used in a liquid crystal display device that is used in an environment such as a vehicle where the temperature change is large. The liquid crystal cell has a high response speed, and is particularly preferable as a liquid crystal cell for a liquid crystal display device such as a vehicle because the response speed does not decrease even in a low temperature environment.

  Further, since the OCB mode has a self-optical compensation function, it has a feature that the viewing angle is wider than other liquid crystal modes such as the TN mode. However, when a particularly wide viewing angle is required, such as a vehicle, it is indispensable to perform optical compensation with an optical compensation film even in an OCB mode liquid crystal cell.

  Under the circumstances as described above, there is an increasing demand for an optical compensation film having a high degree of freedom in adjusting optical compensation (for example, Non-Patent Document 1).

"A Novel Optical Compensation Film for OCB-LCDs", IDW / AD'05 FMC12-1 2005, Vol. 2 p. 1328

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 an optical compensation film excellent in retardation adjustment, a polarizing plate using the optical compensation film, and a liquid crystal display device having the polarizing plate.

Means for solving the above problems are as follows. That is,
<1> At least one optical compensation film comprising two or more layers disposed between a liquid crystal cell and a polarizer, comprising at least a first optical anisotropic layer and a second optical anisotropic layer The angle formed by the slow axis of the second optically anisotropic layer and the slow axis of the first optically anisotropic layer is 0 ° to 42 ° or 48 ° to 90 °, It is an optical compensation film.
<2> An optical compensation film comprising at least one layer disposed between at least one of the liquid crystal cell and the polarizer, comprising at least a first optical anisotropic layer and a second optical anisotropic layer The optical compensation film according to <1>, wherein an angle formed by the slow axis of the second optically anisotropic layer and the slow axis of the first optically anisotropic layer is substantially orthogonal or substantially parallel. is there.
<3> The in-plane retardation (Re2) of the second optically anisotropic layer having a slow axis that is substantially orthogonal or substantially parallel to the slow axis of the first optically anisotropic layer is The optical compensation film according to <2>, wherein the optical retardation film has a relationship of 1 nm <| Re2 | <| Re1 | with the in-plane retardation (Re1) of the isotropic layer.
<4> An optical compensation film composed of at least one of two or more layers disposed between the liquid crystal cell and the polarizing film, comprising at least a first optical anisotropic layer and a second optical anisotropic layer The angle formed by the slow axis of the second optically anisotropic layer and the slow axis of the first optically anisotropic layer is 30 ° to 42 ° or 48 ° to 60 ° <1> It is an optical compensation film as described.
<5> In-plane retardation of the second optically anisotropic layer having a slow axis whose angle to the slow axis of the first optically anisotropic layer is 30 ° to 42 ° or 48 ° to 60 ° ( The optical compensation film according to <4>, wherein Re2) is | Re1 | / 2 <| Re2 | with respect to the in-plane retardation (Re1) of the first optically anisotropic layer.
<6> The optical compensation film according to <1> to <5>, wherein the in-plane retardation (Re1) of the first optically anisotropic layer satisfies 10 nm <Re1 <50 nm.
<7> A direction inclined by 40 ° from the normal to the plane direction of the first optically anisotropic layer within a plane including the orientation axis, the in-plane orthogonal direction and the normal line of the first optically anisotropic layer The in-plane retardation (Re1 (40 °) measured from the above and the retardation value Re1 (−40 °) measured from the direction inclined by 40 ° from the normal line, the following formula (1) or (2)
When Re1 (40 °)> Re1 (−40 °) 3 ≦ Re1 (40 °) / Re1 (−40 °) ≦ 20 (1)
When Re1 (40 °) <Re1 (−40 °) 3 ≦ Re1 (−40 °) / Re1 (40 °) ≦ 20 (2)
The optical compensation film according to <1>, wherein <1> is satisfied.
<8> The optical compensation according to <1> to <7>, wherein the first optically anisotropic layer contains at least one of a discotic liquid crystal and a rod-like liquid crystal fixed in a hybrid alignment state in the film thickness direction. It is a film.
<9> From the above <1>, wherein the first optically anisotropic layer contains at least one non-liquid crystalline polymer selected from the group consisting of polyamide, polyimide, polyester, polyetherketone, polyamideimide, and polyesterimide. <7> The optical compensation film according to the above.
<10> The optical device according to <1> to <7>, wherein the second optically anisotropic layer is a cellulose acylate film, a cyclic olefin copolymer (COC) film, or a cyclic olefin polymer (COP) film. Compensation film.
<11> The optical compensation film according to <10> to <10>, wherein the first optical anisotropic layer, the second optical anisotropic layer, and the polarizer are arranged in an integrated state. It is the polarizing plate used.
<12> The slow axis of the first optically anisotropic layer is about 45 ° with respect to the roll longitudinal direction, and a laminate of a polarizer prepared in a roll shape and the third optically anisotropic layer And the 1st optically anisotropic layer and 2nd optically anisotropic layer produced by roll shape are the polarizing plates of said <11> produced by bonding together by a roll to roll.
<13> The slow axis of the second optically anisotropic layer having a slow axis substantially perpendicular or substantially parallel to the orientation axis direction of the first optically anisotropic layer is about 45 ° with respect to the roll longitudinal direction. <2> or produced by laminating a polarizer, a first optically anisotropic layer and a second optically anisotropic layer produced in a roll, and a roll to roll. A polarizing plate using the optical compensation film according to <3>.
<14> The slow axis of the second optically anisotropic layer having a slow axis that is substantially orthogonal or substantially parallel to the slow axis of the first optically anisotropic layer is substantially perpendicular to the roll longitudinal direction, or The optical compensation film according to the above <2> or <3>, wherein the optical compensation film is produced in a substantially parallel manner and is bonded to a sheet for each unit length at an angle of 40 ° to 50 ° with the other layers and the film longitudinal direction. It is the polarizing plate used.
<15> The slow axis of the second optically anisotropic layer having a slow axis whose angle with the slow axis of the first optically anisotropic layer is 30 ° to 42 ° or 48 ° to 60 °. In a direction shifted by 3 ° or more from the direction perpendicular to or parallel to the longitudinal direction of the roll, and further, a polarizing film produced in a roll shape and first and second optically anisotropic layers produced in a roll shape Is a polarizing plate using the optical compensation film according to the above <4> or <5>.
<16> The in-plane retardation (Re0) of the liquid crystal cell when displaying in black or white is the total value of the in-plane retardation (Re_total) in the direction orthogonal to the alignment axis of the liquid crystal cell of the optical compensation film comprising two or more layers. A liquid crystal panel using the optical compensation film according to <1> to <7>, which is substantially coincident with the above.
<17> The liquid crystal panel according to <16>, wherein the in-plane retardation (Re_total) in the direction orthogonal to the alignment axis of the liquid crystal cell of the optical compensation film comprising two or more layers is substantially the same for the front side and the back side.
<18> The liquid crystal panel according to claim 16 or 17, wherein a retardation (Rth2) in the thickness direction of the second optically anisotropic layer satisfies 0 nm <Rth2 <Δnd / 2. However, (DELTA) n represents the birefringence of the liquid crystal cell of a drive voltage non-application state, and d represents the thickness (nm) of the liquid crystal layer of a liquid crystal cell.
<19> The liquid crystal panel according to <16> to <18>, wherein Δnd of the liquid crystal cell satisfies 500 nm <Δnd <1300 nm.
<20> A liquid crystal panel using one or more polarizing plates according to <11> to <15>, wherein the liquid crystal cell is a liquid crystal cell in a bend alignment mode or a horizontal alignment mode.
<21> a second optically anisotropic layer disposed between at least one liquid crystal cell and the polarizing film, and supporting the first optically anisotropic layer and having optical anisotropy A method for adjusting a retardation of an optical compensation film having an optically anisotropic layer, wherein an angle formed by a slow axis of a first optically anisotropic layer and a slow axis of a second optically anisotropic layer Is adjusted from 0 ° to 42 ° or from 48 ° to 90 °.

  ADVANTAGE OF THE INVENTION According to this invention, the optical compensation film excellent in adjustment of phase difference, the polarizing plate using this optical compensation film, and the liquid crystal display device which has this polarizing plate can be provided.

  Hereinafter, the optical compensation film of the present invention, a polarizing plate using the optical compensation film, and a liquid crystal display device using the polarizing plate will be described.

〔Polarizer〕
The polarizing plate of the present invention has at least a polarizer and an optical compensation film.

<Polarizer>
As the polarizer, a known one can be appropriately selected and used. Optiva Inc. And a polarizer comprising 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 cross-linking 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.
The modified polyvinyl alcohol is obtained by introducing a modifying group into polyvinyl alcohol by copolymerization modification, chain transfer modification or block polymerization modification. The copolymerization modification, as the modifying group _can be introduced _{COONa, Si (OH) 3,} N (CH 3) 3 · Cl, C 9 H 19 COO, SO3Na, the _C 12 _{H 25.} 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.

<Method for producing polarizer>
Although the said polarizer is suitably manufactured using a well-known method, after extending | stretching a binder to the longitudinal direction (MD direction) of a polarizer, it is preferable to dye | stain with an iodine and a dichroic dye.

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.

It is preferable to arrange protective films on both sides of the polarizer, and it is preferable to use a part of the roll-shaped optical film of the present invention as the protective film on one side.
For example, it is laminated in the order of protective film / polarizer / third optical anisotropic layer / second optical anisotropic layer / first optical anisotropic layer, or protective film / polarizer / third The layers are preferably laminated in the order of optically anisotropic layer / second optically anisotropic layer / alignment film / first optically anisotropic layer.
However, the present invention is not limited to this configuration, and the polarizer and the surface side of the first optical anisotropic layer may be bonded together. An adhesive may be used for bonding, for example, using a polyvinyl alcohol resin (including modified polyvinyl alcohol by an acetoacetyl group, a sulfonic acid group, a carboxyl group, or an oxyalkylene group) or a boron compound aqueous solution as the adhesive. Can do. Among these, polyvinyl alcohol resin is preferable.
The thickness of the adhesive layer is preferably in the range of 0.01 to 10 μm after drying, and particularly preferably in the range of 0.05 to 5 μm.

[Optical compensation film]
The optical compensation film includes at least a first optical anisotropic layer and an optical anisotropic layer other than the first optical anisotropy.

<First optically anisotropic layer>
The first optically anisotropic layer is preferably an optically anisotropic layer formed from a liquid crystal compound.
Examples of the liquid crystal compound used for forming the first optically anisotropic layer include a rod-like liquid crystal compound and a discotic liquid crystal compound. The rod-like liquid crystal compound and the discotic liquid crystal compound may be a high-molecular liquid crystal or a low-molecular liquid crystal, and further include those in which the low-molecular liquid crystal is cross-linked and no longer exhibits liquid crystallinity.

(Bar-shaped liquid crystal compound)
Examples of the rod-like 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. 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, 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. Also included are compounds. The molecule or the assembly of molecules is preferably a compound having rotational symmetry and imparting a certain orientation.
When the first optically anisotropic layer is formed from a discotic liquid crystal compound, the compound finally contained in the first 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 be polymerized or crosslinked to increase the molecular weight. When an anisotropic layer is formed, the compound contained in the first optical 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 the discotic liquid crystal compound 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.
Accordingly, the discotic liquid crystal compound having a polymerizable group is preferably a compound represented by the following general formula (I).

In the above general formula (I), 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 (I), 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 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.

  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-AR-O-AL-CO-
L17: -O-CO-AR-O-AL-O-CO-
L18: -O-CO-AR-O-AL-O-AL-O-CO-
L19: -O-CO-AR-O-AL-O-AL-O-AL-O-CO-
L20: -S-AL-
L21: -S-AL-O-
L22: -S-AL-O-CO-
L23: -S-AL-S-AL-
L24: -S-AR-AL-

The polymerizable group (Q) of the general formula (I) 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.
Moreover, in the said general formula (I), n is an integer of 4-12. A specific number 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.

Regarding the orientation of the liquid crystal compound in the first optically anisotropic layer, the average direction of the molecular symmetry axis of the first optically anisotropic layer is preferably 43 ° to 47 ° with respect to the longitudinal direction. .
In the hybrid alignment, the angle between the molecular symmetry axis of the liquid crystal compound and the surface of the second optical anisotropic layer is the depth direction of the first optical anisotropic layer and the surface of the second optical anisotropic layer Increases or decreases with increasing distance from.
The angle preferably increases with increasing distance. Further, the change in angle can be continuous increase, continuous decrease, intermittent increase, intermittent decrease, change including continuous increase and continuous decrease, or intermittent change including increase and decrease. The intermittent change includes a region where the inclination angle does not change in the middle of the thickness direction.
Even if the angle includes a region where the angle does not change, the angle only needs to increase or decrease as a whole. Furthermore, it is preferred that the angle changes continuously.

The average direction of the molecular symmetry axis of the liquid crystal compound can be generally adjusted by selecting a material of the liquid crystal compound or alignment film or by selecting a rubbing treatment method.
As a preferred embodiment of the present invention, in the case of an optical film in which the slow axes of the second optically anisotropic layer and the liquid crystal compound layer are not orthogonal or parallel to each other, they are different from the slow axis of the second optically anisotropic layer. By performing the rubbing treatment in the direction, the slow axis of the liquid crystal compound layer can be adjusted in a simple manner.
Moreover, the molecular symmetry axis direction of the liquid crystal compound on the surface side (air side) can be generally adjusted by selecting the type of the liquid crystal compound or the additive used together with the liquid crystal compound.
Examples of the additive used together with the liquid crystal compound include a plasticizer, a surfactant, a polymerizable monomer, and a polymer. Similar to the above, the degree of change in the orientation direction of the molecular symmetry axis can be adjusted by selecting the liquid crystal compound and the additive. In particular, with respect to the surfactant, it is preferable to achieve compatibility with the above-described surface tension control of the coating solution.

The plasticizer, surfactant, and polymerizable monomer used together with the liquid crystal compound are preferably compatible with the discotic liquid crystal compound and can change the tilt angle of the liquid crystal compound or do not inhibit the alignment. As the polymerizable monomer, a compound having a vinyl group, a vinyloxy group, an acryloyl group, and a methacryloyl group is preferable.
Moreover, the addition amount of the said compound exists in the range of 1-50 mass% generally with respect to a liquid crystal compound, and it is preferable to exist in the range of 5-30 mass%. In addition, when a monomer having 4 or more polymerizable reactive functional groups is mixed and used, adhesion between the alignment film and the first optically anisotropic layer can be improved.

When a discotic liquid crystal compound is used as the liquid crystal compound, it is preferable to use a polymer that has a certain degree of compatibility with the discotic liquid crystal compound and can change the tilt angle of the discotic liquid crystal compound.
A cellulose ester can be mentioned as an example of a polymer. Preferred examples of the cellulose ester include cellulose acetate, cellulose acetate propionate, hydroxypropyl cellulose, and cellulose acetate butyrate.
The addition amount of the polymer is preferably in the range of 0.1 to 10% by mass, and in the range of 0.1 to 8% by mass with respect to the discotic liquid crystal compound so as not to inhibit the orientation of the discotic liquid crystal compound. It is more preferable that it is in the range of 0.1 to 5% by mass.
The discotic nematic liquid crystal phase-solid phase transition temperature of the discotic liquid crystal compound is preferably 70 to 300 ° C, more preferably 70 to 170 ° C.

  In the present invention, the thickness of the first optically anisotropic layer is preferably 0.1 to 20 μm, more preferably 0.5 to 15 μm, and particularly preferably 1 to 10 μm.

The first optical anisotropic layer may be directly formed on the surface of another optical anisotropic layer (second optical anisotropic layer) described later, or on the other optical anisotropic layer. An alignment film may be formed on the alignment film and formed on the alignment film.
Moreover, it is also possible to produce the optical compensation film of the present invention by transferring a liquid crystal compound layer formed on another substrate onto the other optically anisotropic layer using an adhesive or the like. .

The Re retardation value and Rth retardation value of the first optically anisotropic layer are defined by the following formulas (I) and (II), respectively. In the following formulas (I) and (II), nx indicates the refractive index in the slow axis direction (direction in which the refractive index is maximum) in the film plane, and ny is the fast axis direction in the film plane. The refractive index in the direction in which the refractive index is minimized, nz indicates the refractive index in the thickness direction of the film, and d indicates the thickness of the film having the unit of nm.
Re = (nx−ny) × d Expression (I)
Rth = {(nx + ny) / 2−nz} × d (II)

The optical compensation film of the present invention is a surface of the first optical anisotropic layer from the normal line in a plane including the orientation axis of the first optical anisotropic layer, the in-plane orthogonal direction, and the normal line. In-plane retardation (Re1 (40 °) measured from a direction inclined by 40 ° to the direction and retardation value Re1 (−40 °) measured from a direction inclined by 40 ° from the normal line) 1) or (2)
When Re1 (40 °)> Re1 (−40 °) 3 ≦ Re1 (40 °) / Re1 (−40 °) ≦ 20 (1)
When Re1 (40 °) <Re1 (−40 °) 3 ≦ Re1 (−40 °) / Re1 (40 °) ≦ 20 (2)
It is preferable to satisfy.

  In the optical compensation film of the present invention, the in-plane retardation (Re1) of the first optical anisotropic layer preferably satisfies 10 nm <Re1 <50 nm.

<Other optically anisotropic layers>
(Second optical anisotropic layer and third optical anisotropic layer)
The other optically anisotropic layer is laminated on the first optically anisotropic layer. The other optically anisotropic layer may be composed of one layer or two or more layers.
In the present specification, the other optical anisotropic layers may be referred to as a second optical anisotropic layer and a third optical anisotropic layer.
The other optically anisotropic layer is preferably transparent, and specifically, a transparent polymer film having a light transmittance of 80% or more is preferable.

Examples of the polymer film that can be used as the other optically anisotropic layer include polymer films made of cellulose ester (eg, cellulose acetate, cellulose diacetate), norbornene-based polymer, polymethyl methacrylate, and the like. Commercially available polymers (Arton (registered trademark) and Zeonex (registered trademark) may be used for norbornene-based polymers. Among them, a film made of cellulose ester is preferred, and a film made of lower fatty acid ester of cellulose is more preferred. The lower fatty acid means a fatty acid having 6 or less carbon atoms, particularly preferably 2 (cellulose acetate), 3 (cellulose propionate) or 4 (cellulose butyrate).
Among these, a film made of cellulose acetate is particularly preferable. Further, mixed fatty acid esters such as cellulose acetate propionate and cellulose acetate butyrate can also be used.

  Even in the case of polymers that are easily known to exhibit birefringence, such as polycarbonate and polysulfone, which are conventionally known, the birefringence can be expressed by modifying the molecule as described in International Publication WO 00/26705 pamphlet. If controlled, it can also be used as another optically anisotropic layer in the present invention.

As the polymer film, it is preferable to use cellulose acetate having an acetylation degree of 55.0 to 62.5%. The acetylation degree is more preferably 57.0 to 62.0%. Here, the degree of acetylation means the amount of bound acetic acid per unit mass of cellulose.
The degree of acetylation is determined by measurement and calculation of the degree of acetylation in ASTM: D-817-91 (test 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. 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.
The specific value of Mw / Mn is preferably 1.0 to 40, more preferably 1.0 to 1.65, and particularly preferably 1.0 to 1.6.

In cellulose acetate, the hydroxyl groups at the 2-position, 3-position and 6-position of cellulose are not evenly substituted, but the degree of substitution at the 6-position tends to be small.
In the polymer film used as another optically anisotropic layer, it is preferable that the degree of substitution at the 6-position of cellulose is the same or greater than that at the 2- and 3-positions.
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 is preferably 30 to 40%, more preferably 31 to 40%, and more preferably 32 to 40%. It is particularly preferred. Further, 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 6-position substitution degree is described in Synthesis Example 1 described in paragraphs [0043] to “0044” of JP-A No. 11-5851, Synthesis Example 2 described in paragraphs [0048] to [0049], And with reference to the method of Synthesis Example 3 described in Paragraph Nos. [0051] to [0052].

The Re retardation value and Rth retardation value of other optically anisotropic layers are defined by the following formulas (I) and (II), respectively. In the following formulas (I) and (II), nx indicates the refractive index in the slow axis direction (direction in which the refractive index is maximum) in the film plane, and ny is the fast axis direction in the film plane. The refractive index in the direction in which the refractive index is minimized, nz indicates the refractive index in the thickness direction of the film, and d indicates the thickness of the film having the unit of nm.
Re = (nx−ny) × d Expression (I)
Rth = {(nx + ny) / 2−nz} × d (II)

In addition, the other optically anisotropic layer may have an absolute value of a photoelastic coefficient of 10 × 10 ⁻¹² m ² / N or less in the film forming direction and in the direction perpendicular to the film forming direction. preferable.

  When a cellulose acetate film is used for the other optically anisotropic layer, it is preferable to contain a retardation increasing agent in the film. Preferred compound examples and production methods thereof are described, for example, in JP-A Nos. 2000-154261 and 2000-1111914.

(Alignment film)
The optical compensation film of the present invention preferably has an alignment film between the first optical anisotropic layer and another optical anisotropic layer in contact with the first optical anisotropic layer.
In the present invention, the alignment film is preferably a layer made of a crosslinked polymer.
The polymer used for the alignment film may be either a polymer that can be crosslinked by itself or a polymer that is crosslinked by a crosslinking agent.
The alignment film is formed by reacting a polymer having a functional group or a polymer having a functional group introduced therein with light, heat, pH change, or the like, or is a highly reactive compound. It can be formed by introducing a bonding group derived from a cross-linking agent between polymers using an agent and cross-linking the polymers.

The alignment film made of a crosslinked polymer is usually formed by applying a coating solution containing the polymer or a mixture of the polymer and a crosslinking agent on the second optically anisotropic layer, followed by heating or the like. be able to.
In the rubbing process described later, it is preferable to increase the degree of crosslinking in order to suppress the dust generation of the alignment film. A value (1- (Ma / Mb)) obtained by subtracting 1 from the ratio (Ma / Mb) of the amount (Ma) of the crosslinking agent remaining after crosslinking to the amount (Mb) of the crosslinking agent added to the coating solution. When Mb)) is defined as the degree of crosslinking, the degree of crosslinking is preferably from 50 to 100%, more preferably from 65 to 100%, particularly preferably from 75 to 100%.

As the polymer used for the alignment film, either a polymer that can be crosslinked by itself or a polymer that is crosslinked by a crosslinking agent can be used. A polymer having both functions can also be used.
Examples of the polymer include polymethyl methacrylate, acrylic acid / methacrylic acid copolymer, styrene / maleimide copolymer, polyvinyl alcohol, and modified polyvinyl alcohol, poly (N-methylolacrylamide), styrene / vinyltoluene copolymer. Polymers such as coalesced, chlorosulfonated polyethylene, nitrocellulose, polyvinyl chloride, chlorinated polyolefin, polyester, polyimide, vinyl acetate / vinyl chloride copolymer, ethylene / vinyl acetate copolymer, carboxymethyl cellulose, polyethylene, polypropylene and polycarbonate And compounds such as silane coupling agents.
Examples of preferable polymers are water-soluble polymers such as poly (N-methylolacrylamide), carboxymethylcellulose, gelatin, polyvinyl alcohol, and modified polyvinyl alcohol, and gelatin, polyvinyl alcohol, and modified polyvinyl alcohol are particularly preferable. Mention may be made of bil alcohol and modified polyvinyl alcohol.

Among the above polymers, polyvinyl alcohol or modified polyvinyl alcohol is preferable. The polyvinyl alcohol has, for example, a saponification degree of 70 to 100%, generally a saponification degree of 80 to 100%, and more preferably a saponification degree of 85 to 95%.
The degree of polymerization is preferably in the range of 100 to 3,000. Examples of the modified polyvinyl alcohol include those modified by copolymerization (for example, COONa, Si (OX) ₃ , N (CH ₃ ) ₃ .Cl, C ₉ H ₁₉ COO, SO ₃ , Na, C ₁₂ H ₂₅ Etc.), modified by chain transfer (for example, COONa, SH, C ₁₂ H _25, etc. are introduced as modifying groups), modified by block polymerization (modified groups, for example, COOH, CONH ₂ , COOR, C ₆ H _5, etc. are introduced).
The degree of polymerization is preferably in the range of 100 to 3,000. Among these, unmodified or modified polyvinyl alcohol having a saponification degree of 80 to 100% is preferable, and unmodified or alkylthio-modified polyvinyl alcohol having a saponification degree of 85 to 95% is more preferable.

As the modified polyvinyl alcohol used for the alignment film, a reaction product of a compound represented by the following general formula (2) and polyvinyl alcohol is preferable. In the following general formula (2), R ¹ represents an unsubstituted alkyl group or an alkyl group substituted with an acrylolyl group, a methacryloyl group, or an epoxy group, and W represents a halogen atom, an alkyl group, or an alkoxy group. , X represents an atomic group necessary for forming an active ester, acid anhydride or acid halide, l represents 0 or 1, and n represents an integer of 0-4.

Moreover, as the modified polyvinyl alcohol used for the alignment film, a reaction product of a compound represented by the following general formula (3) and polyvinyl alcohol is also preferable. In the following general formula (3), X ¹ represents an atomic group necessary for forming an active ester, an acid anhydride or an acid halide, and m represents an integer of 2 to 24.

As the polyvinyl alcohol used for reacting with the compound represented by the general formula (2) and the general formula (3), the unmodified polyvinyl alcohol and the copolymer modified one, that is, by chain transfer. Examples thereof include modified products of polyvinyl alcohol such as modified products and modified products by block polymerization.
Preferred examples of the specific modified polyvinyl alcohol are described in detail in JP-A-8-338913.
When using a hydrophilic polymer such as polyvinyl alcohol for the alignment film, it is preferable to control the moisture content from the viewpoint of the degree of hardening, and the controlled moisture content is 0.4 to 2.5%. Is preferable, and it is more preferable that it is 0.6 to 1.6%. The water content can be measured with a commercially available Karl Fischer moisture content measuring device.
The alignment film preferably has a thickness of 10 μm or less.

The Re retardation value and Rth retardation value of the optical compensation film are defined by the following formulas (I) and (II), respectively. In the following formulas (I) and (II), nx indicates the refractive index in the slow axis direction (direction in which the refractive index is maximum) in the film plane, and ny is the fast axis direction in the film plane. The refractive index in the direction in which the refractive index is minimized, nz indicates the refractive index in the thickness direction of the film, and d indicates the thickness of the film having the unit of nm.
Re = (nx−ny) × d Expression (I)
Rth = {(nx + ny) / 2−nz} × d (II)

[Method for producing optical compensation film]
The optical compensation film includes an in-plane slow axis of the first optical anisotropic layer and an in-plane slow axis of at least one other optical anisotropic layer (for example, the second optical anisotropic layer). The first optically anisotropic layer and the other optically anisotropic layer (second optically anisotropic layer) so that the angle (angle) between the first optically anisotropic layer and the other optically anisotropic layer is 2 ° or 42 ° or 48 ° to 90 °. And are manufactured. The optical compensation film is produced by appropriately selecting a known method.

  Hereinafter, the method for producing an optical compensation film will be described by taking the method for producing a roll-shaped optical compensation film as an example.

(Method for producing roll optical film)
The manufacturing method of a roll-shaped optical film performs the following process (1)-(4) continuously.
Step (1): formed on the surface of another elongated optically anisotropic layer (for example, the second optically anisotropic layer) conveyed in the longitudinal direction or on the other optically anisotropic layer A step of rubbing the surface of the alignment film with a rubbing roll.
Process (2): The process of apply | coating the coating liquid containing a liquid crystalline compound to the said rubbing process surface.
Step (3): Simultaneously or after drying the applied coating solution, the liquid crystal compound is aligned at a temperature equal to or higher than the liquid crystal transition temperature, and the alignment is fixed to form the first optical anisotropic layer. Manufacturing step.
Step (4): A step of winding the long laminate on which the first optically anisotropic layer is formed.

Here, while orienting the liquid crystal compound at a temperature equal to or higher than the liquid crystal transition temperature in the step (3), the film surface wind speed on the surface of the liquid crystal compound blowing in a direction other than the rubbing direction is expressed by the following formula (3). It is preferable to satisfy, and in the following formula (3), V is more preferably 0 to 2.5 × 10 ⁻³ × η. In the following formula (3), V is the film surface wind speed (m / sec) on the surface of the liquid crystal compound, and η is the viscosity (cp) of the liquid crystal compound layer at the alignment temperature of the liquid crystal compound.

0 <V <5.0 × 10 ⁻³ × η ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Formula (3)

According to this manufacturing method, an optical film can be manufactured continuously and stably, which is suitable for mass production.
When the optical film of the present invention is applied to an OCB mode liquid crystal display device, the optical film and a polarizer are preferably bonded by a roll to roll.

Furthermore, in the manufacturing method of the optical film of this invention, it is desirable to include the requirements in any one of the following (a)-(d). Details of each of these steps are described in JP-A-9-73081.
(A) In the step (2), a polymerizable liquid crystal compound having a crosslinkable functional group is used as the liquid crystal compound, and in the step (3), the coating layer is continuously irradiated with light to polymerize the polymerizable liquid crystal compound. It hardens | cures and fixes to an orientation state, Then, the said process (4) is performed continuously.
(B) In the above step (1), rubbing with a rubbing roll while removing the surface of the second optically anisotropic layer or alignment film.
(C) Before the step (2), a step of removing dust on the surface of the second optically anisotropic layer or the alignment film subjected to the rubbing treatment is performed.
(D) An inspection process in which the optical characteristics of the formed first optically anisotropic layer are inspected by continuous measurement before the process (4).

  Here, the detail of the said process (1)-(4) is demonstrated below.

[Step (1)]
In the step (1), it is formed on the surface of the second optical anisotropic layer of the elongated optical anisotropic layer laminate conveyed in the longitudinal direction or on the second optical anisotropic layer. The surface of the alignment film is rubbed with a rubbing roll.

The diameter of the rubbing roll used in the step (1) is preferably 100 to 500 mm, and more preferably 200 to 400 mm, from the viewpoints of handling suitability and fabric life.
The width of the rubbing roll needs to be wider than the width of the film to be conveyed, and is preferably at least film width × ^2½ .
Further, the number of rotations of the rubbing roll is preferably set low from the viewpoint of dust generation, and depending on the orientation of the liquid crystal compound, it is preferably 100 to 1,000 rpm, and more preferably 250 to 850 rpm. preferable.

  In order to maintain the orientation of the liquid crystal compound even when the number of rotations of the rubbing roll is lowered, it is preferable to heat the second optical anisotropic layer or the orientation film during rubbing. The heating temperature is the film surface temperature of the surface of the second optically anisotropic layer or alignment film, and is preferably (material Tg−50 ° C.) to (material Tg + 50 ° C.). In the case of using an alignment film made of polyvinyl alcohol, it is preferable to control the environmental humidity of rubbing, preferably 25 to 70% RH as a relative humidity at 25 ° C., and more preferably 30 to 60% RH. It is preferably 35 to 55% RH, and particularly preferably.

  The conveyance speed of the optically anisotropic layer laminate is preferably 10 to 100 m / min, more preferably 15 to 80 m / min, from the viewpoints of productivity and liquid crystal orientation. The conveyance can be performed using various apparatuses conventionally used for film conveyance, and the conveyance method is not particularly limited.

  The alignment film is prepared by applying a coating solution prepared by dissolving the above-described material such as polyvinyl alcohol in water and / or an organic solvent to the surface of the second optically anisotropic layer and drying it. be able to. The alignment film can be prepared before the series of steps described above, and the alignment film may be continuously formed on the surface of the long second optically anisotropic layer to be conveyed.

[Step (2)]
In the said process (2), the coating liquid containing a liquid crystalline compound is apply | coated to the said rubbing process surface. As the solvent used for preparing the coating liquid for forming the first optically anisotropic layer, an organic solvent is preferably used.
Examples of organic solvents include amides (eg, N, N-dimethylformamide), sulfoxides (eg, dimethyl sulfoxide), heterocyclic compounds (eg, pyridine), hydrocarbons (eg, benzene, hexane), alkyl halides (eg, , Chloroform, dichloromethane, tetrachloroethane), esters (eg, methyl acetate, butyl acetate), ketones (eg, acetone, methyl ethyl ketone), ethers (eg, tetrahydrofuran, 1,2-dimethoxyethane). Alkyl halides and ketones are preferred. Two or more organic solvents may be used in combination.

In order to produce a highly uniform first optical anisotropic layer, the surface tension of the coating solution is preferably 25 mN / m or less, and more preferably 22 mN / m or less.
In order to achieve this low surface tension, the coating solution for forming the first optically anisotropic layer is used in a surfactant or a fluorine compound, particularly a repeating unit corresponding to the monomer (i) below and the following ( It is preferable to contain a fluoropolymer such as a fluoroaliphatic group-containing copolymer containing a repeating unit corresponding to the monomer of ii).
(I) Fluoroaliphatic group-containing monomer represented by the following general formula (4) (ii) Poly (oxyalkylene) acrylate and / or poly (oxyalkylene) methacrylate

In the general formula (4), R ¹ represents a hydrogen atom or a methyl group, X represents an oxygen atom, a sulfur atom, or —N (R ² ) —, m is an integer of 1 to 6, and n is , Represents an integer of 2 to 4. R ² represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

The weight average molecular weight of the fluoropolymer added to the first optically anisotropic layer-forming coating solution is preferably 3,000 to 100,000, and more preferably 6,000 to 80,000.
Furthermore, the addition amount of the fluorine-based polymer is preferably 0.005 to 8% by mass, more preferably 0.01 to 1% by mass with respect to the coating composition (coating component excluding the solvent) mainly composed of a liquid crystal compound. Preferably, 0.05 to 0.5% by mass is more preferable.
When the addition amount of the fluorine-based polymer is less than 0.005% by mass, the effect is insufficient, and when it exceeds 8% by mass, the coating film cannot be sufficiently dried, or performance as an optical film (for example, Retardation uniformity, etc.).

  Application | coating to the rubbing process surface of the said coating liquid can be implemented by a well-known method (For example, wire bar coating method, extrusion coating method, direct gravure coating method, reverse gravure coating method, die coating method). The coating amount can be appropriately determined based on the desired thickness of the first optically anisotropic layer.

[Step (3)]
In the step (3), the liquid crystal compound is aligned at a temperature equal to or higher than the liquid crystal transition temperature at the same time as or after the applied coating solution is dried, and the alignment is fixed to obtain the first optical anisotropy. A conductive layer is prepared. The liquid crystal compound has a desired orientation by heating during drying or by heating after drying.
The drying temperature can be determined in consideration of the boiling point of the solvent used in the coating solution and the materials of the second optical anisotropic layer, the third optical anisotropic layer, and the alignment film. The alignment temperature of the liquid crystal compound can be determined according to the liquid crystal phase-solid phase transition temperature of the liquid crystal compound used.
When a discotic liquid crystal compound is used as the liquid crystal compound, the alignment temperature is preferably 70 to 300 ° C, and more preferably 70 to 170 ° C.
The liquid crystal state viscosity is preferably 10 to 10,000 cp, and more preferably 100 to 1,000 cp.
If the viscosity is too low, it is easily affected by the wind during orientation, and very accurate wind speed / wind direction control is required for continuous production. On the other hand, if the viscosity is high, it is difficult to be affected by wind, but the alignment of the liquid crystal becomes slow, and the productivity is greatly deteriorated.
The viscosity of the liquid crystal layer can be appropriately controlled by the molecular structure of the liquid crystal compound. Moreover, the method of adjusting to a desired viscosity by using an appropriate amount of the above-mentioned additive (especially cellulosic polymer etc.), a gelatinizer, etc. is used preferably.
Heating can be carried out by blowing hot air at a predetermined temperature or by conveying in a heating chamber maintained at a predetermined temperature.
As for the warm air at this time, as shown in the following formula (3), it is preferable that the wind speed other than the rubbing direction hitting the liquid crystal compound layer is controlled. In the following formula (3), V is the film surface wind speed (m / sec) on the surface of the liquid crystal compound, and η is the viscosity (cp) of the liquid crystal compound layer at the alignment temperature of the liquid crystal compound.

0 <V <5.0 × 10 ⁻³ × η Equation (3)

Further, the aligned liquid crystal compound is fixed while maintaining the alignment state to form the first optical anisotropic layer. The liquid crystal compound can be fixed by cooling to a solid phase transition temperature or by a polymerization reaction, but preferably by a polymerization reaction. 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. No. 2,367,661 and US Pat. No. 2,367,670), acyloin ether (described in US Pat. No. 2,448,828), α-hydrocarbons. A substituted aromatic acyloin compound (described in US Pat. No. 2,722,512), a polynuclear quinone compound (described in US Pat. Nos. 3,046,127 and 2,951,758), a triarylimidazole dimer, p-aminophenyl ketone, (Described in US Pat. No. 3,549,367), acridine and phenazine compounds (described in JP-A-60-105667 and US Pat. No. 4,239,850), and oxadiazole compounds (US Pat. No. 4,212,970) Is included).
The amount of the photopolymerization initiator used is preferably in the range of 0.01 to 20% by mass, more preferably in the range of 0.5 to 5% by mass, based on the solid content of the coating solution.

It is preferable to use ultraviolet rays for light irradiation for proceeding and fixing the polymerization of the liquid crystal compound. The irradiation energy is preferably in the range of 20~50J / cm ^2, more preferably in the range of 20~5,000mJ / cm ^2, and still more preferably in the range of 100 to 800 mJ / cm ^2.
In order to accelerate the photopolymerization reaction, light irradiation may be performed under heating conditions. In the light irradiation, the second optically anisotropic layer and the third optically anisotropic layer coated with the first optically anisotropic layer forming coating liquid are applied to one or more of the light sources in the vertical and horizontal directions. It can be carried out by passing through a conveyance path arranged at the position.

  Before shifting to the above step (4), a protective layer can be provided on the first optically anisotropic layer produced in the above step (3). For example, a protective layer film prepared in advance may be continuously laminated on the surface of the first optically anisotropic layer prepared in a long shape.

In the step (4), the long laminate on which the first optically anisotropic layer is formed is wound up. For winding, for example, a second optical anisotropic layer having a first optical anisotropic layer and a third optical anisotropic layer that are continuously conveyed are wound around a cylindrical core. You may go by.
Since the optical film obtained by the step (4) is in the form of a roll, it can be easily handled even when manufactured in large quantities. It can be stored and transported as it is.

  The conditions and apparatuses described in JP-A-9-73081 can be applied to the details of the conditions of each step of the production method of the present invention and the usable apparatus.

[Production method of polarizing plate]
The polarizing plate is manufactured by laminating and integrating the optical compensation film and the polarizer. When integrating, the slow axis of the first optical compensation layer of the optical compensation film and the transmission axis of the polarizer are set so as to form a predetermined angle. For integration, a known adhesive or the like can be appropriately used as long as the function of the polarizing plate is not impaired. The polarizing plate has not only a polarizing function but also an optical compensation function.

[Liquid Crystal Display]
The optical compensation film of the present invention and the polarizing plate using the optical compensation film are not mounted with an optical film such as a birefringence mode liquid crystal display device, particularly an OCB type liquid crystal display device and an ECB type reflective liquid crystal display device. It is advantageously used for a liquid crystal display device in which black / white display is difficult.
The transmissive liquid crystal display device includes a liquid crystal cell and two (a pair) 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.

  FIG. 1 is an exploded perspective view of a polarizing plate 1 according to an embodiment of the present invention. The polarizing plate 1 includes at least the optical compensation film 30 and a polarizer (polarizing film) 50. The polarizing plate 1 is disposed on the liquid crystal cell 60. For convenience of explanation, FIG. 1 shows only the polarizing plate 1 arranged on the liquid crystal display side.

  The optical compensation film 30 includes at least the first optical anisotropic layer 10 and another optical anisotropic layer (second optically different layer) which is an optical anisotropic layer other than the first optical anisotropic layer 10. (Isotropic layer) 20. The optical compensation film 30 shown in FIG. 1 includes two other optical anisotropic layers 20 (second optical anisotropic layer 21 and third optical anisotropic layer 22).

In the optical compensation film of the present invention, the angle (angle) formed by the slow axis of the first optical anisotropic layer and the second optical anisotropic layer is 0 ° to 42 ° or 48 ° to 90 °. It is characterized by being. In the optical compensation film 30 shown in FIG. 1, an angle formed by the slow axis 112 of the first optical anisotropic layer 10 and the slow axis 121 of the second optical anisotropic layer 20 (21) ( Angle) is 0 °. When the angle is 0 °, the Re value of the entire optical compensation film 30 can be made larger than the Re value of the first optical compensation film 10 alone.
If the angle is 90 °, the Re value of the entire optical compensation film 30 can be made smaller than the Re value of the first optical compensation film 10 alone.

FIG. 11 is an explanatory diagram showing the relationship between the angle (angle) formed between the slow axis 112 of the first optical anisotropic layer 10 and the slow axis 121 of the second optical anisotropic layer 20 (21). It is. The X axis and Y axis in FIG. 11 are orthogonal.
For convenience of explanation, the positions of axes such as the slow axis, the orientation axis, and the transmission axis may be expressed with reference to the X axis. For example, the position of the slow axis 112 in FIG. 11 is 135 °.

In the embodiment (see FIG. 1), the angle formed by the slow axis 122 of the third optical anisotropic layer 20 (22) and the slow axis 112 of the first optical anisotropic layer 10 is 45. It is °. Therefore, the third optical anisotropic layer 20 (22) does not contribute to optical compensation.
On the other hand, the angle formed by the slow axis 121 of the second optically anisotropic layer 20 (21) and the slow axis 112 of the first optically anisotropic layer 10 is 0 °. Therefore, the second optically anisotropic layer 20 (21) contributes to optical compensation so that the Re value of the entire optical compensation film increases.
In FIG. 1, the angle formed by the transmission axis 150 of the polarizer (polarizing film 50) and the slow axis 112 of the first optically anisotropic layer 10 is 45 °. Further, reference numeral 210 in FIG. 1 represents the alignment direction of the first optical anisotropic layer 10, and reference numeral 60 represents the alignment direction of the liquid crystal cell 60.

  In the optical compensation film of the present invention, the in-plane retardation (Re2) of the second optically anisotropic layer having a slow axis that is substantially orthogonal or substantially parallel to the slow axis of the first optically anisotropic layer, It is preferable to have a relationship of 1 nm <| Re2 | <| Re1 | with the in-plane retardation (Re1) of the first optically anisotropic layer.

In the description of the present embodiment, “45 °”, “parallel” or “orthogonal” means that the angle is within a range of strictly less than ± 5 °. The error from the exact angle is preferably less than 4 °, more preferably less than 3 °.
Regarding the angle, “+” means the clockwise direction, and “−” means the counterclockwise direction.
Further, “slow axis” means a direction in which the refractive index is maximum, and “visible light region” means 380 to 780 nm.
Further, the refractive index measurement wavelength is a value in the visible light region (λ = 550 nm) unless otherwise specified.

Further, in the present embodiment, the “polarizing plate” is used to include both a long polarizing plate and a polarizing plate cut into a size incorporated in a liquid crystal device, unless otherwise specified. . Here, “cutting” includes “punching” and “cutting out”.
In the description of the present embodiment, “polarizer” and “polarizing plate” are distinguished from each other, but “polarizing plate” is a laminate having a transparent protective film for protecting the polarizer on at least one surface of “polarizer”. It shall mean the body.

In the description of the present embodiment, the “molecular symmetry axis” refers to a symmetry axis when the molecule has a rotational symmetry axis, but strictly requires that the molecule is rotationally symmetric. is not.
In general, in a discotic liquid crystalline compound, the molecular symmetry axis coincides with an axis perpendicular to the disc surface passing through the center of the disc surface, and in a rod-like liquid crystalline compound, the molecular symmetry axis is the long axis of the molecule. Match.

In this specification, Re (λ) and Rth (λ) represent in-plane retardation and retardation in the thickness direction at the wavelength λ, respectively. Re (λ) is measured with KOBRA 21ADH or WR (manufactured by Oji Scientific Instruments Co., Ltd.) by making light of wavelength λ nm incident in the normal direction of the film.
When the film to be measured is represented by a uniaxial or biaxial refractive index ellipsoid, Rth (λ) is calculated by the following method.
Rth (λ) is the film surface when Re (λ) is used and the in-plane slow axis (determined by KOBRA 21ADH or WR) is the tilt axis (rotation axis) (if there is no slow axis) Measurement is performed at a total of 6 points by injecting light of wavelength λ nm from each inclined direction in steps of 10 degrees from the normal direction to 50 ° on one side with respect to the film normal direction (with any rotation direction as the rotation axis). Then, KOBRA 21ADH or WR is calculated based on the measured retardation value, the assumed value of the average refractive index, and the input film thickness value.
In the above case, in the case of a film having a direction in which the retardation value is zero at a certain tilt angle with the in-plane slow axis from the normal direction as the rotation axis, retardation at a tilt angle larger than the tilt angle. The value is calculated by KOBRA 21ADH or WR after changing its sign to negative.
The retardation value is measured from two inclined directions with the slow axis as the tilt axis (rotation axis) (if there is no slow axis, the arbitrary direction in the film plane is the rotation axis). Rth can also be calculated from the following formula (A) and formula (II) based on the value, the assumed value of the average refractive index, and the input film thickness value.

・ ・ ・ ・ ・ ・ Formula (A)

Note that Re (θ) represents a retardation value in a direction inclined by an angle θ from the normal direction.
In the formula (A), nx represents the refractive index in the slow axis direction in the plane, ny represents the refractive index in the direction orthogonal to nx in the plane, and nz is the direction orthogonal to nx and ny. Represents the refractive index.

  Rth = ((nx + ny) / 2−nz) × d (II)

When the film to be measured is a film that cannot be expressed by a uniaxial or biaxial refractive index ellipsoid, that is, a film without a so-called optical axis, Rth (λ) is calculated by the following method.
Rth (λ) is from −50 ° to the normal direction of the film, with Re (λ) being the in-plane slow axis (determined by KOBRA 21ADH or WR) as the tilt axis (rotary axis). Measured at 11 points by making light of wavelength λ nm incident in 10 ° steps up to + 50 °, and based on the measured retardation value, average refractive index assumption value and input film thickness value. KOBRA 21ADH or WR is calculated.
In the above measurement, as the assumed value of the average refractive index, values in the polymer handbook (John Wiley & Sons, Inc.) and catalogs of various optical films can be used. If the average refractive index is not known, it can be measured with an Abbe refractometer. The average refractive index values of main optical films are exemplified below: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), Polystyrene (1.59). The KOBRA 21ADH or WR calculates nx, ny, and nz by inputting the assumed value of the average refractive index and the film thickness. Nz = (nx−nz) / (nx−ny) is further calculated from the calculated nx, ny, and nz.

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

[Example 1]
<Optical compensation film>
(Third optical anisotropic layer)
The following composition was put into a mixing tank, stirred while heating to dissolve each component, and a cellulose acetate solution A was prepared.

[Cellulose acetate A solution composition]
-Cellulose acetate with 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
・ 45 parts by mass of methanol

  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.

  34.7 parts by mass of the retardation increasing agent solution was mixed with 470 parts by mass of the cellulose acetate solution A, and the dope was prepared by sufficiently stirring. The mass ratio of the retardation increasing agent to cellulose acetate was 6.5%. After peeling the film having a residual solvent amount of 35% by mass from the band, the film was transported in an unstretched state using a film tenter at a temperature of 140 ° C., then the clip was removed and the film was dried at 130 ° C. for 45 seconds, A third optically anisotropic layer of the form was produced.

(Second optically anisotropic layer)
The following composition was put into a mixing tank and stirred while heating to dissolve each component to prepare a cellulose acetate solution B.

[Cellulose acetate solution B composition]
-Cellulose acetate with 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
・ 45 parts by mass of methanol

  The dope was prepared by mixing 1470 parts by mass of the retardation increasing agent solution with 470 parts by mass of the cellulose acetate solution and stirring sufficiently. The mass ratio of the retardation increasing agent to cellulose acetate was 3.5%. After peeling the film having a residual solvent amount of 35% by mass from the band, the film was stretched at a stretching ratio of 38% using a film tenter at a temperature of 140 ° C., then the clip was removed and the film was dried at 130 ° C. for 45 seconds. A second optically anisotropic layer in film form was produced.

On one surface of the prepared second optically anisotropic layer, 1.5N potassium hydroxide in isopropyl alcohol was applied at 25 ml / m ² and allowed to stand at 25 ° C. for 5 seconds. The film surface was dried by spraying air at 25 ° C. for 10 seconds. In this way, only one surface of the second optically anisotropic layer was saponified.

<< Formation of alignment film >>
On one surface of the saponified second optically anisotropic layer, an alignment film coating solution having the following composition was coated at 24 ml / m ² with a # 14 wire bar coater. Drying was performed with warm air of 60 ° C. for 60 seconds, and further with warm air of 90 ° C. for 150 seconds. Next, the film was rubbed.

[Alignment film coating solution composition]
・ 10 parts by weight of the following modified polyvinyl alcohol / 371 parts by weight of water / 119 parts by weight of methanol
・ 0.5 parts by mass of glutaraldehyde (crosslinking agent)

(First optical anisotropic layer)
To 204.0 parts by mass of methyl ethyl ketone, 91 parts by mass of the following discotic compound, 9 parts by mass of ethylene oxide-modified trimethylolpropane triacrylate (V # 360, manufactured by Osaka Organic Chemical Co., Ltd.), cellulose acetate butyrate (CAB531- 1, 0.5 parts by mass of Eastman Chemical Co., Ltd., 3 parts by mass of a photopolymerization initiator (Irgacure 907, Ciba Geigy), 1 part by mass of a sensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.) It melt | dissolved and the coating liquid was prepared.
The coating solution was applied to the alignment film by 5.52 ml / m ² using a # 3.2 wire bar. This was affixed to a metal frame and heated in a thermostatic bath at 130 ° C. for 2 minutes to orient the discotic compound.
Next, ultraviolet rays were irradiated for 4 minutes using a 120 W / cm high pressure mercury lamp at 90 ° C. to polymerize the discotic compound. Then, it stood to cool to room temperature. Thus, the 1st optical anisotropic layer was formed and the optical compensation film was produced.

  Using an automatic birefringence meter (KOBRA-21ADH, manufactured by Oji Scientific Instruments Co., Ltd.), the first optical anisotropic layer, the second optical anisotropic layer, and the third optical light with light having a wavelength of 550 nm Re (550 nm) values of the anisotropic layer and the optical compensation film (total) were measured. The results are shown in Table 1.

(Setting angle of slow axis)
In the optical compensation film 31, the angle (θ1) formed between the slow axis 112 and the slow axis 121 of the first optical anisotropic layer 10 and the second optical anisotropic layer 20 (21). ) Was set to 0 °.
In addition, the angle (θ2) between the slow axis 122 of the third optical anisotropic layer 20 (22) and the slow axis of the first optical anisotropic layer 10 is 45 °. Set to.

(Production of elliptically polarizing plate)
Iodine was adsorbed on the stretched polyvinyl alcohol film to prepare a polarizing film (polarizer). Next, the third optical anisotropic layer side of the produced optical compensation film was attached to one side of the polarizing film using a polyvinyl alcohol-based adhesive. The slow axis 122 of the third optical anisotropic layer 20 (22) and the transmission axis 150 of the polarizing film (polarizer) 50 were arranged in parallel (see FIG. 1).
A commercially available cellulose triacetate film (Fujitac TD80UF, manufactured by Fuji Film Co., Ltd.) was saponified in the same manner as described above, and a polyvinyl alcohol adhesive was used on the opposite side of the polarizing film (the side on which the optical film was not attached). Affixed (not shown). Thus, the elliptically polarizing plate 1 was produced.

(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 opposed to each other so that the rubbing directions were parallel to each other, and the thickness (d) of the liquid crystal cell was set to 7900 nm. A liquid crystal compound (ZLI1132, manufactured by Merck & Co., Inc.) having a Δn (birefringence of the liquid crystal cell in a state where no drive voltage is applied) 0.1396 was injected into the gap between the liquid crystal cells to produce a liquid crystal cell A having bend alignment. Δnd is 1100 nm.

(Production of liquid crystal display device)
A liquid crystal display device was fabricated by combining the bend alignment liquid crystal cell 60 and the pair of polarizing plates 1 (see FIG. 1).
The liquid crystal cell 60 and the pair of polarizing plates 1 are arranged in such a manner that the polarizing plate faces the first optical anisotropic layer and the substrate of the liquid crystal cell, and the rubbing direction of the liquid crystal cell faces the first. The rubbing direction of the optically anisotropic layer was made antiparallel.
Polarizing plates 1 were attached to the transparent side and the backlight side, respectively, on different transparent substrates so as to sandwich the produced liquid crystal cell 60.
The first optical anisotropic layer 10 of the polarizing plate 1 faces the transparent substrate, and the rubbing direction 260 of the liquid crystal cell 60 and the rubbing direction 210 of the first optical anisotropic layer 10 facing it are antiparallel. Thus, a liquid crystal display device in which the size of the liquid crystal cell 60 was 20 inches was manufactured.

<Evaluation of liquid crystal display device>
The “viewing angle wideness”, “viewing angle asymmetry” and “front Re controllability” of the liquid crystal display device were evaluated. The results are shown in Table 2.
In the evaluation of “wide viewing angle” and “viewing angle asymmetry”, the prepared liquid crystal display device was placed on the backlight in an environment of temperature: 25 ° C. and humidity: 60%, and a bend-aligned liquid crystal cell. A voltage was applied at 55 Hz rectangular wave.
While adjusting the voltage, a color luminance meter (BM-5A, manufactured by TOPCON) was used to determine the voltage with the smallest black luminance (front luminance).

<< Wide viewing angle >>
The luminance meter is used to measure black luminance and white luminance (front luminance) at the center of the screen, and the ratio of black luminance to white luminance is expressed as contrast.
The contrast was measured from the hemisphere in front of the panel from an azimuth angle of 0 ° to 350 ° and from a polar angle of 0 ° to 80 ° in 10 ° increments to evaluate the width of the viewing angle. The results are shown in Table 2.

[Evaluation criteria]
A: The contrast viewing angle is very wide (when it exceeds 160 °)
○: Wide contrast viewing angle (140 ° or more and less than 160 °)
Δ: Normal (when 110 ° or more and less than 140 °)
×: Narrow contrast viewing angle (less than 110 °)

<< View angle asymmetry >>
Using the luminance meter, the voltage applied to the cell is adjusted so that the difference between black luminance at the center of the screen and white luminance (front luminance) is equally divided into eight, and the luminance and chromaticity at each setting are adjusted. Was measured.
The brightness and chromaticity are measured from the hemisphere in front of the panel from an azimuth angle of 0 ° to 350 ° and from a polar angle of 0 ° to 80 ° in 10 ° increments. Evaluated. The results are shown in Table 2.

[Evaluation criteria]
◎: Almost symmetrical ○: Slightly left-right asymmetrical but not worried △: Left-right asymmetry is recognizable, but no problem

<< Front Re controllability >>
The range of cells Re that can be handled by one type of optically anisotropic layer 10 was evaluated.

[Evaluation criteria]
◎: Cell Re value can be selected almost freely ○: Cell Re value is somewhat restricted △: Normal ×: Only one type of cell can be supported

[Examples 2 to 8]
The optical compensation films 32 to 38 (see FIGS. 2 to 8) of Examples 2 to 8 were used as the first optical anisotropic layer, the second optical anisotropic layer, and the third optical difference shown in Table 1. It produced using the anisotropic layer, and also produced the polarizing plates 2-8 and the liquid crystal display device of Examples 2-8 using these optical compensation films 32-38.
Further, the liquid crystal display devices of Examples 2 to 8 were evaluated in the same manner as Example 1. The results are shown in Table 2.
FIG. 2 is an exploded perspective view of a liquid crystal display device including the polarizing plate 2 including the optical compensation film 32 of the second embodiment. FIG. 3 is an exploded perspective view of a liquid crystal display device including the polarizing plate 3 including the optical compensation film 33 of Example 3. FIG. 4 is an exploded perspective view of the liquid crystal display device including the polarizing plate 4 including the optical compensation film 34 of the fourth embodiment. FIG. 5 is an exploded perspective view of the liquid crystal display device including the polarizing plate 5 including the optical compensation film 35 of the fifth embodiment. FIG. 6 is an exploded perspective view of the liquid crystal display device including the polarizing plate 6 including the optical compensation film 36 of Example 6. FIG. 7 is an exploded perspective view of a liquid crystal display device including the polarizing plate 7 including the optical compensation film 37 of Example 7. FIG. 8 is an exploded perspective view of the liquid crystal display device including the polarizing plate 8 including the optical compensation film 38 of the eighth embodiment.

[Examples 9 to 12]
The optical compensation films of Examples 9 to 12 were prepared using the first optical anisotropic layer, the second optical anisotropic layer, and the third optical anisotropic layer shown in Table 1, and Using these optical compensation films, polarizing plates and liquid crystal display devices of Examples 9 to 12 were produced. Further, the liquid crystal display devices of Examples 9 to 12 were evaluated in the same manner as in Example 1, and the results are shown in Table 2.

[Comparative Examples 1 and 2]
The optical compensation films of Comparative Examples 1 and 2 were prepared using the first optical anisotropic layer, the second optical anisotropic layer, and the third optical anisotropic layer shown in Table 1, Using these optical compensation films, polarizing plates and liquid crystal display devices of Comparative Examples 1 and 2 were produced. Further, in the same manner as in Example 1, the liquid crystal display devices of Comparative Examples 1 and 2 were evaluated. The results are shown in Table 2.
FIG. 9 is an exploded perspective view of a liquid crystal display device including the polarizing plate 101 including the optical compensation film 301 of Comparative Example 1. FIG. 10 is an exploded perspective view of a liquid crystal display device including the polarizing plate 102 including the optical compensation film 302 of Comparative Example 2.

  As can be seen from the evaluation results shown in Table 2, it was found that the liquid crystal display devices including the optical compensation films of Examples 1 to 8 and Examples 9 to 12 were excellent in controllability of the front Re value.

FIG. 1 is an exploded perspective view of a liquid crystal display device (Example 1) according to an embodiment of the present invention. FIG. 2 is an exploded perspective view of a liquid crystal display device (Example 2) according to another embodiment. FIG. 3 is an exploded perspective view of a liquid crystal display device (Example 3) according to another embodiment. FIG. 4 is an exploded perspective view of a liquid crystal display device (Example 4) according to another embodiment. FIG. 5 is an exploded perspective view of a liquid crystal display device (Example 5) according to another embodiment. FIG. 6 is an exploded perspective view of a liquid crystal display device (Example 6) according to another embodiment. FIG. 7 is an exploded perspective view of a liquid crystal display device (Example 7) according to another embodiment. FIG. 8 is an exploded perspective view of a liquid crystal display device (Example 8) according to another embodiment. FIG. 9 is an exploded perspective view of a conventional liquid crystal display device (Comparative Example 1). FIG. 10 is an exploded perspective view of another conventional liquid crystal display device (Comparative Example 2). FIG. 11 is an explanatory diagram showing a relationship between an angle (angle θ) formed by the slow axis of the first optically anisotropic layer and the slow axis of the second optically anisotropic layer.

Explanation of symbols

1 Polarizing plate 10 First optical anisotropic layer 20 Other optical anisotropic layer 21 Other optical anisotropic layer (second optical anisotropic layer)
22 Other optically anisotropic layers (third optically anisotropic layer)
30 Optical compensation film 50 Polarizer 60 Liquid crystal cell 112 In-plane slow axis 121 of the first optical anisotropic layer 122 In-plane slow axis 122 of the second optical anisotropic layer 122 of the third optical anisotropic layer In-plane slow axis 150 Polarizer transmission axis 260 Alignment direction 210 of liquid crystal cell Alignment direction of first optical compensation layer

Claims (21)

At least one of the optical compensation films consisting of two or more layers disposed between the liquid crystal cell and the polarizer,
Consisting of at least a first optically anisotropic layer and a second optically anisotropic layer,
An optical system characterized in that an angle formed by the slow axis of the second optically anisotropic layer and the slow axis of the first optically anisotropic layer is 0 ° to 42 ° or 48 ° to 90 °. Compensation film. At least one of the optical compensation films consisting of two or more layers disposed between the liquid crystal cell and the polarizer,
Consisting of at least a first optically anisotropic layer and a second optically anisotropic layer,
The optical compensation film according to claim 1, wherein an angle formed by the slow axis of the second optically anisotropic layer and the slow axis of the first optically anisotropic layer is substantially orthogonal or substantially parallel.   The in-plane retardation (Re2) of the second optical anisotropic layer having a slow axis that is substantially orthogonal or substantially parallel to the slow axis of the first optical anisotropic layer is the first optical anisotropic layer. The optical compensation film according to claim 2, having a relationship of 1 nm <| Re2 | <| Re1 | with respect to the in-plane retardation (Re1). At least one of the optical compensation films composed of two or more layers disposed between the liquid crystal cell and the polarizing film,
Consisting of at least a first optically anisotropic layer and a second optically anisotropic layer,
The optical system according to claim 1, wherein an angle formed by the slow axis of the second optical anisotropic layer and the slow axis of the first optical anisotropic layer is 30 ° to 42 ° or 48 ° to 60 °. Compensation film.   The in-plane retardation (Re2) of the second optically anisotropic layer having a slow axis whose angle to the slow axis of the first optically anisotropic layer is 30 ° to 42 ° or 48 ° to 60 °. 5. The optical compensation film according to claim 4, wherein | Re1 | / 2 <| Re2 | between the first optical anisotropic layer and the in-plane retardation (Re1).   6. The optical compensation film according to claim 1, wherein the in-plane retardation (Re1) of the first optical anisotropic layer satisfies 10 nm <Re1 <50 nm. Measured from a direction inclined by 40 ° from the normal to the plane direction of the first optical anisotropic layer in a plane including the orientation axis of the first optical anisotropic layer, the in-plane orthogonal direction, and the normal line In-plane retardation (Re1 (40 °) and retardation value Re1 (−40 °) measured from a direction inclined by 40 ° from the normal line) are expressed by the following formula (1) or (2).
When Re1 (40 °)> Re1 (−40 °) 3 ≦ Re1 (40 °) / Re1 (−40 °) ≦ 20 (1)
When Re1 (40 °) <Re1 (−40 °) 3 ≦ Re1 (−40 °) / Re1 (40 °) ≦ 20 (2)
The optical compensation film according to claim 1, wherein:   The optical compensation film according to claim 1, wherein the first optical anisotropic layer contains at least one of a discotic liquid crystal and a rod-like liquid crystal fixed in a hybrid alignment state in the film thickness direction.   8. The optical element according to claim 1, wherein the first optically anisotropic layer contains at least one non-liquid crystalline polymer selected from the group consisting of polyamide, polyimide, polyester, polyetherketone, polyamideimide, and polyesterimide. Compensation film.   The optical compensation film according to claim 1, wherein the second optically anisotropic layer is a cellulose acylate film, a cyclic olefin copolymer (COC) film, or a cyclic olefin polymer (COP) film.   The polarizing plate using the optical compensation film according to claim 1, wherein the first optical anisotropic layer, the second optical anisotropic layer, and the polarizer are arranged in an integrated state.   The slow axis of the first optically anisotropic layer is about 45 ° with respect to the roll longitudinal direction, and further, a bonded product of a polarizer and a third optically anisotropic layer produced in a roll shape, and a roll The polarizing plate of Claim 11 produced by bonding the 1st optically anisotropic layer and 2nd optically anisotropic layer produced in the shape of a roll to roll.   The slow axis of the second optically anisotropic layer having a slow axis that is substantially perpendicular or substantially parallel to the orientation axis direction of the first optically anisotropic layer is expressed in a direction of approximately 45 ° with respect to the roll longitudinal direction. The optical device according to claim 2, further comprising a roll-to-roll laminate of the polarizer prepared in a roll shape, the first optical anisotropic layer, and the second optical anisotropic layer. A polarizing plate using a compensation film.   The slow axis of the second optically anisotropic layer having a slow axis that is substantially orthogonal or substantially parallel to the slow axis of the first optically anisotropic layer is substantially perpendicular or substantially parallel to the longitudinal direction of the roll. 4. A polarizing plate using the optical compensation film according to claim 2 or 3, wherein the polarizing plate is produced and bonded to a sheet for each unit length at an angle of 40 ° to 50 ° with the other layer and the film longitudinal direction.   The slow axis of the second optically anisotropic layer having a slow axis whose angle with the slow axis of the first optically anisotropic layer is 30 ° to 42 ° or 48 ° to 60 ° is the roll length. A roll of polarizing film produced in a roll shape and first and second optically anisotropic layers produced in a roll shape, which is expressed in a direction deviated by 3 ° or more from the direction perpendicular to or parallel to the direction. A polarizing plate using the optical compensation film according to claim 4, which is produced by bonding with a to roll.   The total value of the in-plane retardation (Re_total) in the direction perpendicular to the alignment axis of the liquid crystal cell of the optical compensation film consisting of two or more layers is approximately the same as the in-plane retardation (Re0) of the liquid crystal cell when displaying black or white. A liquid crystal panel using the optical compensation film according to claim 1.   The liquid crystal panel according to claim 16, wherein the in-plane retardation (Re_total) in the direction orthogonal to the alignment axis of the liquid crystal cell of the optical compensation film comprising two or more layers is substantially the same for the front side and the back side. The thickness direction retardation (Rth2) of the second optically anisotropic layer is
18. The liquid crystal panel according to claim 16, wherein 0 nm <Rth2 <Δnd / 2 is satisfied.
However, (DELTA) n represents the birefringence of the liquid crystal cell of a drive voltage non-application state, and d represents the thickness (nm) of the liquid crystal layer of a liquid crystal cell.   The liquid crystal panel according to claim 16, wherein Δnd of the liquid crystal cell satisfies 500 nm <Δnd <1300 nm.   The liquid crystal panel using one or more polarizing plates according to claim 11, wherein the liquid crystal cell is a bend alignment mode or horizontal alignment mode liquid crystal cell. Arranged between at least one liquid crystal cell and the polarizing film,
A first optically anisotropic layer;
A method of adjusting a retardation of an optical compensation film that supports the first optical anisotropic layer and has a second optical anisotropic layer having optical anisotropy,
The angle formed by the slow axis of the first optically anisotropic layer and the slow axis of the second optically anisotropic layer is adjusted from 0 ° to 42 ° or from 48 ° to 90 °. Method for adjusting retardation of optical compensation film.