JP2003287622A - Optical compensation plate and polarizing plate using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical compensation plate having an optical compensation layer whose cracking under pressure has been inhibited. <P>SOLUTION: A crack preventive layer is formed directly on an optical compensation layer surface by applying a curable adhesive on at least one surface of the optical compensation layer and curing the adhesive. The crack preventive layer prevents generation of the cracking in the optical compensation layer. The optical compensation layer is preferably a layer having a cholesteric structure. The constituent material thereof may preferably be a non-liquid-crystal polymer formed by polymerization of an oriented liquid crystal monomer, or an oriented liquid crystal polymer. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an optical compensation film, a polarizing plate using the same, and an image display device.

[0002]

2. Description of the Related Art In a liquid crystal display device, a polarizer is generally arranged on both sides of a liquid crystal cell holding a liquid crystal. Then, in order to visually compensate the phase difference due to the birefringence of the liquid crystal cell in the front direction and the perspective direction, a birefringent layer is further arranged as an optical compensation layer between the liquid crystal cell and the polarizer. As the birefringent layer, a negative birefringent layer in which cholesteric liquid crystal molecules are aligned on an alignment substrate and which has a negative uniaxial refractive index (nx, ny, nz) “nx = ny> nz” is usually used. It is used. The leading rate (nx, n
y and nz) respectively indicate the refractive indices in the three axial directions of the birefringent layer. Specifically, the axial direction of the refractive index (nx, ny, nz) in the birefringent layer is indicated by an arrow in the schematic diagram of FIG. As described above, the refractive indices nx, ny, and nz represent the refractive indices in the X-axis, Y-axis, and Z-axis directions, respectively, and as shown in the figure, the X-axis is the axis showing the maximum refractive index in the plane. Direction, the Y-axis is an axial direction perpendicular to the X-axis in the plane, and the Z-axis is a thickness direction perpendicular to the X-axis and the Y-axis.

As such an optical compensation layer, for example,
An optical compensation layer in which an alignment film is formed on a support and discotic liquid crystal is tilt-aligned on the alignment film has been reported (for example, Patent Documents 1 and 2).

Further, a liquid crystal polymer is coated on an alignment substrate,
It has also been reported that the liquid crystal polymer is aligned to form a cholesteric liquid crystal layer and this is used as an optical compensation layer (for example, Patent Document 3).

[0005]

[Patent Document 1] Japanese Patent No. 2692035

[Patent Document 2] Japanese Patent No. 2802719

[Patent Document 3] Japanese Patent No. 2660601

[0006]

However, the optical compensation layer formed of the cholesteric layer as described above is
For example, there is a problem that cracks (for example, cracks, cracks, etc.) occur when pressure is locally applied due to vibration during transportation. When a crack is generated in the optical compensation layer as described above, when the optical compensation layer is used in a liquid crystal display device, it also causes a problem in display characteristics such as color loss in a display portion.

Therefore, an object of the present invention is to provide, for example, an optical compensation plate including an optical compensation layer in which the generation of cracks due to vibration or pressure is suppressed, a polarizing plate including the same, and various image display devices. .

[0008]

In order to achieve the above-mentioned object, the optical compensator of the present invention is an optical compensator including an optical compensating layer, wherein at least one surface of the optical compensating layer is a curable type. It is characterized in that a crack prevention layer made of an adhesive is directly laminated.

As described above, by directly providing the adhesive layer (that is, the crack preventing layer) formed of the curable adhesive on at least one surface of the optical compensation layer, for example, the above-mentioned vibration or local It is possible to suppress the occurrence of cracks in the optical compensation layer due to various pressures.

The crack prevention layer may be laminated on only one side of the optical compensation layer or may be laminated on both sides. Even when the crack prevention layer is laminated only on one surface of the optical compensation layer, the generation of cracks can be sufficiently suppressed, and the thickness can be further reduced. On the other hand, when a crack prevention layer is laminated on both sides of the optical compensation layer, the resistance is further increased by vibration and pressure, and the occurrence of cracks can be further prevented.

Next, the polarizing plate of the present invention is characterized by including a polarizer, a transparent protective layer, and the optical compensation plate of the present invention. As described above, since the optical compensation plate of the present invention is included, high quality can be maintained without cracking even when the polarizing plate of the present invention is vibrated or pressured. Furthermore, the polarizing plate of the present invention is useful for a liquid crystal panel and suitable for use in a liquid crystal display device. Further, it is not limited to the liquid crystal display device, but is also useful for a self-luminous display device such as an electroluminescence (EL) display, a plasma display (PD) and an FED (Field Emission Display).

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION As described above, the optical compensatory plate of the present invention is an optical compensatory plate containing an optical compensatory layer, in which at least one surface of the optical compensatory layer is made of a curable adhesive to prevent cracks. It is characterized in that the layers are directly laminated.

The crack prevention layer is not particularly limited as long as it is formed from the curable adhesive. For example, the indentation hardness (Microhardness) is 0.1 to 0.5 G.
It is preferably in the range of Pa, more preferably 0.0.
It is in the range of 2 to 0.5 GPa, particularly preferably 0.3 to
It is in the range of 0.4 GPa. Since the indentation hardness has a known correlation with Vickers hardness, it can be converted to Vickers hardness.

The indentation hardness is, for example, a thin film hardness meter (trade name: MH400, manufactured by NEC Corporation).
0, trade name MHA-400, etc.) can be used to calculate from the indentation depth and indentation load.

The type of the curable adhesive is not particularly limited, and examples thereof include photocurable adhesives such as ultraviolet curable adhesives, moisture curable adhesives, thermosetting adhesives, and the like. Of these, preferred are adhesives. Moisture-curing adhesive.

As a concrete curable adhesive, for example,
Examples thereof include thermosetting resin-based adhesives such as epoxy resin, isocyanate resin and polyimide resin, and moisture-curable adhesives such as isocyanate resin-based adhesive. Among these, an isocyanate resin-based adhesive which is a moisture-curable adhesive is preferable. The isocyanate resin adhesive is a general term for polyisocyanate adhesives and polyurethane resin adhesives.

In the optical compensation plate of the present invention, the thickness of the crack preventing layer is preferably in the range of 0.1 to 20 μm, more preferably 0.5 to 15 μm, and particularly preferably 1 to It is in the range of 10 μm. The thickness of the cholesteric layer is, for example, 0.5 to
The range is 10 μm, more preferably 1 to 8 μm, and particularly preferably 2 to 6 μm.

In the optical compensation plate of the present invention, the optical compensation layer is preferably a cholesteric layer in which the constituent molecules are oriented in a cholesteric structure.

In the present invention, the cholesteric layer is a pseudo layer structure called a so-called plane structure or Grandjean structure in which the constituent molecules of the layer have a helical structure and the helical axis is oriented substantially perpendicular to the plane direction. It can be said that it has a layer. Further, in the present invention, "the constituent molecules have a cholesteric structure" is not limited to, for example, the case where the liquid crystal compound has a cholesteric liquid crystal phase, and the non-liquid crystal compound is not a liquid crystal phase, It also includes those that are aligned in a twisted state like the cholesteric liquid crystal phase. Therefore, examples of the constituent molecules of the cholesteric layer include a liquid crystal polymer and a non-liquid crystal polymer as described later.

The cholesteric layer has, for example, a refractive index (nx, ny, n) in the three axial directions as described above.
It is preferable that z) is nx≈ny> nz. The optical compensation plate including the optical compensation layer having such optical characteristics can be used as a so-called negative C-Plate retardation plate.

In the optical compensation plate of the present invention, the selective reflection wavelength band of the cholesteric layer is, for example, 10
The range is 0 nm to 320 nm, and the upper limit is 300.
It is preferably nm or less. On the other hand, the lower limit is 1
It is preferably 50 nm or more. When the selective reflection wavelength is in such a range, for example, coloring of the cholesteric layer and light leakage in a crossed Nicols state can be sufficiently avoided, and thus when the optical compensation plate of the present invention is used in various image display devices. In addition, even more excellent display characteristics can be provided in both the front direction and the perspective direction.

The center wavelength of the selective reflection wavelength band λ (nm) can be represented by the following formula, for example, when the cholesteric layer is formed by using a liquid crystal monomer as described later. λ = n · P In the above formula, n is the average refractive index of the liquid crystal monomer, and P is the helical pitch (μ) of the cholesteric layer.
m) is shown. The average refractive index n is represented by "(n _o + n _e ) / 2", and is usually in the range of 1.45 to 1.65, and n _o is
The normal light refraction of the liquid crystal monomer, the n _e shows the extraordinary refractive index of the liquid crystal monomer.

The cholesteric layer preferably contains a chiral agent. The chiral agent in the present invention is, for example, a compound having a function of aligning constituent molecules such as a liquid crystal monomer and a liquid crystal polymer described later so as to have a cholesteric structure.

The type of the chiral agent is not particularly limited as long as it can orient the constituent molecules of the cholesteric layer into the cholesteric structure as described above.
For example, the chiral agent described below is preferable.

Among these chiral agents, the twisting power is preferably 1 × 10 ⁻⁶ nm ⁻¹ · (wt%) ⁻¹ or more, more preferably 1 × 10 ⁻⁵ nm ⁻¹ · ( wt%) ^-1 or more, more preferably 1 × 10 ^-5 to 1 × 10 ^-2 nm ^-1 (wt%)
^{-1 in} the range, particularly preferably 1 × 10 ^-4 ~ 1 × 10 ^-3
The range is nm ⁻¹ · (wt%) ⁻¹ . If a chiral agent having such a twisting force is used, for example, the helical pitch of the formed cholesteric layer can be controlled in the range described below, and thereby the selective reflection wavelength band can be sufficiently controlled in the range. It is possible.

The term "twisting force" generally refers to the ability to give a twist to a liquid crystal material such as a liquid crystal monomer or a liquid crystal polymer, which will be described later, and to align it in a spiral shape.
It can be expressed by the following formula. Torsional force = 1 / [Cholesteric pitch (nm) x Chiral agent weight ratio (wt
%)]

In the above formula, the weight ratio of the chiral agent is, for example, the ratio (weight ratio) of the chiral agent in the mixture containing the liquid crystal monomer or liquid crystal polymer and the chiral agent.
Is expressed by the following formula. Chiral agent weight ratio (wt%) = [X / (X + Y)] × 1
00 X: weight of chiral agent Y: weight of liquid crystal monomer or weight of liquid crystal polymer

The helical pitch in the cholesteric layer is, for example, 0.25 μm or less, preferably 0.01 to 0.25 μm, more preferably 0.03 to 0.20 μm, and particularly preferably 0.03 to 0.20 μm. Preferably 0.0
It is in the range of 5 to 0.15 μm. The spiral pitch is 0.
When it is 01 μm or more, for example, sufficient orientation can be obtained, and when it is 0.25 μm or less, for example, optical rotatory power on the short wavelength side of visible light can be sufficiently suppressed, and thus when used under polarized light, Light leakage and the like can be sufficiently avoided. And, if a chiral agent with a twisting force as described above is used,
The helical pitch of the formed cholesteric layer can be controlled within the above range.

The cholesteric layer has a single hue b.
The value is, for example, preferably 1.2 or less, more preferably 1.1 or less, and particularly preferably 1.0 or less. With the cholesteric layer in such a range, for example, coloring is very little, and extremely excellent optical characteristics are exhibited. The single hue b value in such a range can be achieved by controlling the selective reflection wavelength band in the above range, for example.

The individual hue b value is obtained by Hunter Lab.
Color system (Hunter, RS: J. Opt. Soc. Amer., 38, 661
(A), 1094 (A) (1948); J. Opt. Soc. Amer., 48, 985 (195
8)). Specifically, for example, JIS K 71
In accordance with 05 5.3, the tristimulus values (X, Y, Z) of the sample are measured using a spectrophotometer or photoelectric colorimeter, and these values are shown as the color difference formula in Lab space below in the Hunter.
By substituting into the equation, the single hue b value can be calculated. A C light source is usually used for this measurement. In addition,
For example, an integrating sphere type spectral transmittance measuring device (trade name DOT-3
C; manufactured by Murakami Color Research Laboratory), the single hue b value can be measured together with the transmittance. Single hue b = 7.0 × (Y-0.847Z) / Y ^1/2

Specific examples of the constituent molecules of the cholesteric layer include a non-liquid crystal polymer. The non-liquid crystal polymer is preferably a polymer obtained by polymerizing or cross-linking a liquid crystal monomer having a cholesteric structure and oriented. . With such a configuration, as will be described later,
Since the monomer exhibits liquid crystallinity, it can be oriented by taking a cholesteric structure, and the orientation can be fixed by further polymerizing the monomers. Therefore, although a liquid crystal monomer is used, the polymerized polymer becomes non-liquid crystalline by the fixing.
In order to make the liquid crystal monomer have a cholesteric structure, for example, when a chiral agent as described below is used, the liquid crystal monomer and the chiral agent are polymerized and crosslinked to form a non-liquid crystal polymer.

As a constituent molecule of the cholesteric layer, such a non-liquid crystal polymer is preferable for the following reasons. A cholesteric layer formed from such a non-liquid crystal polymer has a cholesteric structure like a cholesteric liquid crystal phase, but since it is not composed of liquid crystal molecules as described above, for example, a temperature change peculiar to liquid crystal molecules The change to the liquid crystal phase, the glass phase, or the crystal phase due to does not occur. Therefore, the cholesteric structure serves as an optical compensation layer that is not affected by temperature changes and is extremely excellent in stability. Therefore, it can be said that the optical compensation plate of the present invention is useful, for example, as a retardation film for optical compensation.

The liquid crystal monomer is preferably a monomer represented by the chemical formula (1) described later. Such a liquid crystal monomer is generally a nematic liquid crystal monomer, but in the present invention, for example, a twist is imparted by the chiral agent, and finally, a cholesteric structure is formed. Further, in the cholesteric layer, it is necessary to polymerize or crosslink between the monomers in order to fix the orientation. Therefore, the monomer preferably contains at least one of a polymerizable monomer and a crosslinkable monomer.

When the liquid crystal monomer is used, it is preferable that the cholesteric layer further contains at least one of a polymerizing agent and a cross-linking agent. For example, a substance such as an ultraviolet curing agent, a photo-curing agent, a heat curing agent or the like. Can be used.

The proportion of the liquid crystal monomer in the cholesteric layer is preferably in the range of 75 to 95% by weight, more preferably 80 to 90% by weight. The ratio of the chiral agent to the liquid crystal monomer is preferably in the range of 5 to 23% by weight,
It is more preferably in the range of 10 to 20% by weight. Also,
The ratio of the cross-linking agent or the polymerizing agent to the liquid crystal monomer is preferably in the range of 0.1 to 10% by weight,
The range is more preferably 0.5 to 8% by weight, and particularly preferably 1 to 5% by weight.

The constituent molecules of the cholesteric layer include, for example, a liquid crystal polymer in addition to the non-liquid crystal polymer, and the liquid crystal polymer has a cholesteric structure and is oriented. May be. Examples of the liquid crystal polymer include various liquid crystal polymers disclosed in Japanese Patent No. 2660601.

The optical compensating plate of the present invention may be formed of, for example, only the optical compensating layer and the crack preventing layer as described above, but further includes a substrate, and the cholesteric layer is laminated on the substrate. It may be the body.

In such an optical compensating plate of the present invention, for example, an optical compensating layer is prepared in advance, and a curable adhesive is applied to at least one surface of the optical compensating layer. It can be prepared by curing the coating film.

As the curable adhesive, for example, a commercially available adhesive may be used, or various curable resins as described above may be dissolved or dispersed in a solvent to prepare a curable resin solution. . The content ratio of the curable resin in this solution is, for example, in the range of 10 to 80% by weight of solid content, preferably 20 to 60% by weight, and more preferably 30 to 50% by weight. Specifically, when the curable resin is an isocyanate resin, for example, the solid content weight is 2
It is in the range of 0 to 80% by weight, preferably 25 to 65% by weight, and more preferably 30 to 50% by weight.

The type of the solvent can be appropriately determined depending on the type of the curable resin, for example, ethyl acetate,
Methyl ethyl ketone, methyl isobutyl ketone, toluene, xylene and the like can be used. Moreover, you may mix and use these several solvent as needed.

The coating amount of the adhesive on the optical compensation layer can be appropriately determined depending on, for example, the desired thickness of the crack prevention layer to be formed. Specifically, when the above-mentioned curable resin solution is applied, for example, the area (cm ² ) of the optical compensation layer is in the range of 0.3 to 3 ml, preferably 0.5 to ² ml. , Particularly preferably 1-2 ml.

The method for curing the curable adhesive is not particularly limited, and can be appropriately determined depending on the type, for example. When the curable resin is a moisture-curable resin adhesive, it cures by reacting with moisture in the air, adsorbed water on the surface of the adherend, active hydrogen groups such as hydroxyl groups and carboxyl groups. Therefore, according to a conventionally known method, for example, after the adhesive is applied, it can be naturally cured by leaving it to stand. The solvent as described above contained in the adhesive may be volatilized by natural drying or heat drying.

In the case of the photocurable adhesive, for example, the coating film can be cured by irradiating the coating film with ultraviolet rays or visible rays, and the conditions are also in accordance with the conventionally known method. be able to.

In the present invention, the type of the optical compensation layer for laminating the crack prevention layer is not particularly limited, but the cholesteric layer having a non-liquid crystal polymer as a constituent molecule as described above is, for example, as follows. Can be prepared.

For example, a step of spreading a coating liquid containing a liquid crystal monomer, the chiral agent, and at least one of a polymerizing agent and a cross-linking agent on an alignment substrate to form a spreading layer, wherein the liquid crystal monomer is cholesteric. So as to have a structured orientation, a step of subjecting the spread layer to a heat treatment, and
In order to fix the orientation of the liquid crystal monomer to form a cholesteric layer of a non-liquid crystal polymer, the development layer may be formed by a manufacturing method including a step of subjecting at least one of a polymerization treatment and a crosslinking treatment.

First, a coating liquid containing the liquid crystal monomer, the chiral agent, and at least one of the crosslinking agent and the polymerizing agent is prepared.

The liquid crystal monomer is preferably, for example, a nematic liquid crystal monomer, and specific examples thereof include a monomer represented by the following formula (1). These liquid crystal monomers may be used alone or in combination of two or more.

[0048]

[Chemical 1] In the formula (1), A ¹ and A ² each represent a polymerizable group, and may be the same or different. Also, A ¹
One of A ² and A ² may be hydrogen. X
Are a single bond, -O-, -S-, -C = N-,-, respectively.
O-CO-, -CO-O-, -O-CO-O-, -CO
-NR-, -NR-CO-, -NR-, -O-CO-N
R -, - NR-CO- O -, - CH 2 -O- or -N
R represents R—CO—NR, R in X represents H or C ₁ -C ₄ alkyl, and M represents a mesogen group.

In the above formula (1), X may be the same or different, but it is preferable that they are the same.

Among the monomers of the above formula (1), A
It is preferable that each of ^2's is ortho to A ¹ .

[0051] The A ¹ and A ² are preferably represented by the independent formula Z-X- and _{(Sp) n ··· (2)} , A 1 and A ² are the same group Preferably there is.

In the above formula (2), Z represents a crosslinkable group, X is the same as in the above formula (1), and Sp is 1 to 3.
It represents a spacer consisting of a linear or branched alkyl group having 0 C atoms, and n represents 0 or 1. The carbon chain in Sp may be interrupted by, for example, oxygen in an ether functional group, sulfur in a thioether functional group, a non-adjacent imino group, or a C ₁ -C ₄ alkylimino group.

In the above formula (2), Z is preferably any of the atomic groups represented by the following formula. In the following formula, R is, for example, methyl, ethyl, n-
Propyl, i-propyl, n-butyl, i-butyl, t
Group such as -butyl.

[Chemical 2]

Further, in the above formula (2), Sp is preferably one of the atomic groups represented by the following formula, and in the following formula, m is 1 to 3 and p is 1 to 12. Is preferred.

[Chemical 3]

In the above formula (1), M is preferably represented by the following formula (3), and in the following (3), X is the same as X in the above formula (1). Q
Represents, for example, a substituted or unsubstituted alkylene or aromatic hydrocarbon atomic group, and may be, for example, a substituted or unsubstituted linear or branched C _{1 to} C ₁₂ alkylene.

[Chemical 4]

When Q is the aromatic hydrocarbon atomic group, for example, an atomic group represented by the following formula or a substituted analog thereof is preferable.

[Chemical 5]

Examples of the substituted analog of the aromatic hydrocarbon atomic group represented by the above formula include, for example, 1 to 1 per aromatic ring.
It may have 4 substituents and may have 1 or 2 substituents per aromatic ring or group. The substituents may be the same or different. Examples of the substituent include C ₁ -C ₄ alkyl,
Halogen such as nitro, F, Cl, Br, I, phenyl,
C ₁ -C ₄ alkoxy, and the like.

Specific examples of the liquid crystal monomer include monomers represented by the following formulas (4) to (19).

[Chemical 6]

The temperature range in which the liquid crystal monomer exhibits liquid crystallinity varies depending on its type, but is, for example, 40 to 120.
It is preferably in the range of ℃, more preferably 50 ~
It is in the range of 100 ° C, particularly preferably in the range of 60 to 90 ° C.

As described above, the chiral agent is not particularly limited as long as it twists the liquid crystal monomer to align it so as to have a cholesteric structure, but it is a polymerizable chiral agent. Preferably, the above-mentioned ones can be used. These chiral agents may be used alone or in combination of two or more.

Specifically, as the polymerizable chiral agent, for example, chiral compounds represented by the following general formulas (20) to (23) can be used. _{^{(Z-X 5) n Ch}} (20) (Z-X 2 -Sp-X 5) n Ch (21) (P 1 -X 5) n Ch (22) (Z-X 2 -Sp-X 3 - M-X ⁴ ) _n Ch (23)

In each of the above formulas, Z is the same as the above formula (2), Sp is the same as the above formula (2),
X ^2, X ³ and X ^4, independently of one another, a chemical single bond, -O -, - S -, - O-CO -, - CO-O -, -
O-CO-O-, -CO-NR-, -NR-CO-,-
O-CO-NR-, -NR-CO-O-, -NR-CO
Represents —NR—, and R represents H, C ₁ -C ₄ alkyl. X ⁵ is a chemical single bond, —O—, —S—, —
O-CO-, -CO-O-, -O-CO-O-, -CO
-NR-, -NR-CO-, -O-CO-NR-, -N
R-CO-O -, - NR-CO-NR, -CH 2 O-,
_{-O-CH 2 -, - CH} = N -, - N = CH- or -
Represents N≡N−. R is the same manner as described above represents H, C ₁ -C ₄ alkyl. M represents a mesogen group as described above,
P ¹ represents hydrogen, a C _{1 to} C ₃₀ alkyl group substituted by _{1 to} 3 C _{1 to} C ₆ alkyl, a C ₁ to ₃₀ acyl group or a C _{3 to} C ₈ cycloalkyl group, and n is It is an integer of 1 to 6. Ch represents an n-valent chiral group. Equation (2)
In 3), at least one of X ³ and X ⁴ is —O—CO—O—, —O—CO—NR—, or —NR—.
It is preferably CO-O- or -NR-CO-NR-. Further, in the above formula (22), when P ¹ is an alkyl group, an acyl group or a cycloalkyl group, for example, the carbon chain thereof is oxygen in the ether functional group, sulfur in the thioether functional group, a non-adjacent imino group or it may be interrupted by C ₁ -C ₄ alkylimino groups.

Examples of the chiral group of Ch include, for example,
An atomic group represented by the following formula can be given.

[Chemical 7]

[Chemical 8]

In the above atomic group, L is C ₁ -C ₄ alkyl, C ₁ -C ₄ alkoxy, halogen, COOR, OC.
OR, CONHR or NHCOR, wherein R represents C ₁ -C ₄ alkyl. The terminal of the atomic group represented by the above formula represents a bond with an adjacent group.

Among the above-mentioned atomic groups, the atomic group represented by the following formula is particularly preferable.

[Chemical 9]

In the chiral compound represented by the above (21) or (23), for example, n is 2, Z is H ₂ C =
CH- is represented, and Ch is preferably an atomic group represented by the following formula.

[Chemical 10]

Specific examples of the chiral compound include compounds represented by the following formulas (24) to (44). These chiral compounds have a twisting power of 1 × 10 ^-6 nm ^-1 · (wt%) ^-1 or more.

[Chemical 11]

Besides the chiral compounds as mentioned above, for example, RE-A 4342280 and German patent applications 19520660.6 and 19520704.1.
The chiral compounds listed in No. 10 can be preferably used.

The polymerization agent and the cross-linking agent are not particularly limited, but for example, the following ones can be used. Examples of the polymerization agent include benzoyl peroxide (BPO) and azobisisobutyronitrile (AI).
BN) or the like can be used, and as the crosslinking agent, for example, an isocyanate crosslinking agent, an epoxy crosslinking agent, a metal chelate crosslinking agent, or the like can be used. These may be offset or one type may be used, or two or more types may be used in combination.

The coating liquid can be prepared, for example, by dissolving and dispersing the liquid crystal monomer or the like in a suitable solvent. The solvent is not particularly limited, but for example, halogenated hydrocarbons such as chloroform, dichloromethane, carbon tetrachloride, dichloroethane, tetrachloroethane, methylene chloride, trichloroethylene, tetrachloroethylene, chlorobenzene, orthodichlorobenzene, phenol, p- Chlorophenol, o-chlorophenol, m-cresol, o-cresol, p
-Phenols such as cresol, aromatic hydrocarbons such as benzene, toluene, xylene, methoxybenzene, and 1,2-dimethoxybenzene, acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone, cyclohexanone, cyclopentanone, 2-pyrrolidone , N-
Ketone solvents such as methyl-2-pyrrolidone, ester solvents such as ethyl acetate and butyl acetate, t-butyl alcohol, glycerin, ethylene glycol, triethylene glycol, ethylene glycol monomethyl ether, diethylene glycol dimethyl ether, propylene glycol, dipropylene glycol. , 2-methyl-
An alcohol solvent such as 2,4-pentanediol,
Amide solvents such as dimethylformamide and dimethylacetamide, nitrile solvents such as acetonitrile and butyronitrile, ether solvents such as diethyl ether, dibutyl ether, tetrahydrofuran and dioxane, or carbon disulfide, ethyl cellosolve, butyl cellosolve. Etc. can be used. Of these, preferred are toluene, xylene, mesitylene, MEK, methyl isobutyl ketone, cyclohexanone, ethyl cellosolve, butyl cellosolve, ethyl acetate, butyl acetate, propyl acetate, and ethyl cellosolve acetate. These solvents may be, for example, one kind alone, or two or more kinds may be mixed and used.

The addition ratio of the chiral agent is appropriately determined depending on, for example, the desired helical pitch and the desired selective reflection wavelength band, but the addition ratio to the liquid crystal monomer is, for example, in the range of 5 to 23% by weight. And preferably in the range of 10 to 20% by weight. As described above, by controlling the addition ratio of the liquid crystal monomer and the chiral agent in this way, the selected wavelength band of the optical film to be formed can be set within the above range. When the ratio of the chiral agent to the liquid crystal monomer is 5% by weight or more, for example, it becomes very easy to control the selective reflection wavelength band of the formed optical film to the low wavelength side. Further, when the ratio is 23% by weight or less, the temperature range in which the liquid crystal monomer is cholesterically aligned, that is, the temperature range in which the liquid crystal monomer is in the liquid crystal phase is wide. Therefore, the temperature control in the alignment step described below should be strictly performed. Is unnecessary, and manufacturing is extremely easy.

For example, when a chiral agent having the same twisting power is used, the selective reflection wavelength band to be formed is on the lower wavelength side as the proportion of the chiral agent added to the liquid crystal monomer increases. Further, for example, when the addition ratio of the chiral agent to the liquid crystal monomer is the same, for example, the larger the twisting force of the chiral agent, the more the selective reflection wavelength band of the formed optical film is on the low wavelength side. As a specific example, the selective reflection wavelength band of the formed optical film is set to 200 to 22.
When setting in the range of 0 nm, for example, the twisting force is
A chiral agent of 5 × 10 ⁻⁴ nm ⁻¹ · (wt%) ⁻¹ may be added so as to be 11 to 13% by weight with respect to the liquid crystal monomer, and the selective reflection wavelength band is in the range of 290 to 310 nm. For example, if the twisting force is 5 × 10 ^-4 nm,
^-1 · (wt%) ^-1 chiral agent to liquid crystal monomer 7 ~
It may be blended so as to be 9% by weight.

The combination of the liquid crystal monomer and the chiral agent is not particularly limited, but specifically, the monomer agent of the formula (10) and the formula (38) are used.
And a combination of the monomer agent of the formula (11) and the chiral agent of the formula (39).

The addition ratio of the cross-linking agent or the polymerizing agent to the liquid crystal monomer is, for example, 0.1 to 10% by weight.
The range is preferably 0.5 to 8% by weight, more preferably 1 to 5% by weight. When the ratio of the cross-linking agent or the polymerizing agent to the liquid crystal monomer is 0.1% by weight or more, for example, curing of the cholesteric layer is sufficiently facilitated, and when the ratio is 10% by weight or less, for example, the liquid crystal monomer is Since the temperature range of cholesteric alignment, that is, the temperature at which the liquid crystal monomer becomes a liquid crystal phase is in a sufficient range, the temperature control in the alignment process described later becomes easier.

Further, for example, various additives may be appropriately added to the coating liquid, if necessary. Examples of the additives include antiaging agents, modifiers, surfactants, dyes, pigments, discoloration inhibitors, and ultraviolet absorbers.
One of these additives may be added, or two or more of them may be used in combination. Specifically, the antiaging agent is, for example, a phenol compound, an amine compound, an organic sulfur compound, a phosphine compound, or the like, and the modifier is, for example, glycols, silicones, alcohols, or the like. Known ones can be used. The surfactant is added, for example, to smooth the surface of the optical compensation layer. For example, a silicone-based, acrylic-based, or fluorine-based surfactant can be used, and a silicone-based surfactant is particularly preferable.

When the liquid crystal monomer is used in this way,
The prepared coating liquid exhibits a viscosity excellent in workability such as coating and spreading. The viscosity of the coating liquid usually differs depending on the concentration and temperature of the liquid crystal monomer, but when the monomer concentration in the coating liquid is in the range of 5 to 70% by weight, the viscosity is, for example, 0. 2 to 20 mPa · s, preferably 0.5 to 15 mPa · s,
Particularly preferably, it is 1 to 10 mPa · s. Specifically, when the monomer concentration in the coating liquid is 30% by weight, the range is, for example, 2 to 5 mPa · s, and preferably 3 to 4 mPa · s. The viscosity of the coating liquid is 0.
When it is 2 mPa · s or more, for example, it is possible to further prevent the generation of a liquid flow caused by running the coating liquid.
When it is 0 mPa · s or less, for example, surface smoothness is further excellent, thickness unevenness can be further prevented, and coatability is also excellent. In addition, although the said viscosity showed the range in the temperature of 20-30 degreeC, it is not limited to this temperature.

Next, the coating liquid is applied onto the alignment substrate to form a spreading layer.

The coating liquid is, for example, a roll coating method,
It may be fluidized by a conventionally known method such as a spin coating method, a wire bar coating method, a dip coating method, an extrusion method, a curtain coating method, and a spray coating method. Rouge coats are preferred.

The alignment substrate is not particularly limited as long as it can align the liquid crystal monomer, and for example, various plastic films or plastic sheets whose surfaces are rubbed with rayon cloth or the like can be used. The plastic is not particularly limited,
For example, triacetyl cellulose (TAC), polyethylene, polypropylene, poly (4-methylpentene-
1) Polyolefin, polyimide, polyimide amide, polyetherimide, polyamide, polyetheretherketone, polyetherketone, polyketone sulfide, polyethersulfone, polysulfone, polyphenylene sulfide, polyphenylene oxide, polyethylene terephthalate, polybutylene terephthalate, polyethylenena Examples thereof include phthalate, polyacetal, polycarbonate, polyarylate, acrylic resin, polyvinyl alcohol, polypropylene, cellulosic plastics, epoxy resin and phenol resin. In addition, a plastic film or sheet as described above may be arranged on the surface of a metal substrate such as aluminum, copper, or iron, a ceramic substrate, a glass substrate, or Si may be formed on the surface.
It is also possible to use a film having an O ₂ oblique vapor deposition film formed thereon. Also,
A laminated body in which a stretched film having birefringence, which has been subjected to a stretching treatment such as uniaxial stretching, is laminated as an alignment film on the above-mentioned plastic film or sheet can also be used as the alignment substrate. Furthermore, when the substrate itself has birefringence, it is preferable because the rubbing treatment as described above and laminating a birefringence film on the surface are unnecessary. As a method of imparting birefringence to the substrate itself, for example, in the formation of the substrate, a method of casting, extrusion molding or the like in addition to the stretching treatment can be mentioned.

Then, the spread layer is heat-treated to align the liquid crystal monomer in a liquid crystal state.
Since the spreading layer contains the chiral agent together with the liquid crystal monomer, the liquid crystal monomer in a liquid crystal phase (liquid crystal state) is aligned while being twisted by the chiral agent. That is, the liquid crystal monomer exhibits a cholesteric structure (helical structure).

The temperature condition of the heat treatment can be appropriately determined depending on, for example, the type of the liquid crystal monomer, specifically, the temperature at which the liquid crystal monomer exhibits liquid crystallinity, but is usually 40
To 120 ° C., preferably 50 to 100 ° C., and more preferably 60 to 90 ° C. When the temperature is 40 ° C. or higher, the liquid crystal monomer can be normally aligned sufficiently, and when the temperature is 120 ° C. or lower, for example, in terms of heat resistance, selection of various alignment base materials as described above is selected. It has a wide range of characteristics.

Next, the liquid crystal monomer and the chiral agent are polymerized or crosslinked by subjecting the spreading layer in which the liquid crystal monomer is oriented to a crosslinking treatment or a polymerization treatment. As a result, the liquid crystal monomers are polymerized and cross-linked with each other or polymerized and cross-linked with the chiral agent while being aligned in a cholesteric structure, and the alignment state is fixed. Then, the formed polymer becomes a non-liquid crystal polymer by fixing the alignment state.

The above-mentioned polymerization treatment or crosslinking treatment can be appropriately determined depending on, for example, the type of the polymerization agent or crosslinking agent used. For example, when a photopolymerization agent or a photocrosslinking agent is used, light irradiation may be performed, and when an ultraviolet polymerization agent or an ultraviolet crosslinking agent is used, ultraviolet irradiation may be performed.

As described above, the optical compensation layer formed of the non-liquid crystalline polymer oriented in the cholesteric structure is obtained on the oriented substrate. This optical compensation layer is non-liquid crystalline because its orientation is fixed as described above. Therefore, for example, the liquid crystal phase, the glass phase, and the crystal phase do not change due to the temperature change, and the orientation change due to temperature does not occur. Therefore, it can be used for the optical compensation plate of the present invention as a high-performance retardation film that is not affected by temperature. Further, if the selective reflection wavelength band is controlled within the above range, it is possible to suppress the light leakage as described above.

The optical compensation layer may be peeled off from the alignment substrate to form a crack prevention layer on at least one surface of the alignment substrate. A crack prevention layer may be formed on the surface of the compensation layer.

When used as a laminate of the optical compensation layer and the alignment substrate, the alignment substrate is preferably a transparent plastic film. Examples of the plastic film include cellulose such as TAC, polyethylene, polypropylene, polyolefin such as poly (4-methylpentene-1), polyimide, polyamideimide, polyamide, polyetherimide, polyetheretherketone, polyketone sulfide, Polyether sulfone, polysulfone, polyphenylene sulfide, polyphenylene oxide, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyacetal, polycarbonate, polyarylate, acrylic resin, polyvinyl alcohol, polypropylene, cellulose plastic, epoxy resin, phenol resin, polynorbornene , Polyester, polystyrene, polyvinyl chloride, polyvinyl chloride Down, the film may be mentioned that is formed from a liquid crystal polymer or the like. These films can be optically isotropic or anisotropic. Among these plastic films, from the viewpoint of solvent resistance and heat resistance, for example, each film formed of polypropylene, polyethylene terephthalate, or polyethylene naphthalate is preferable. In addition to this, for example, Japanese Patent Laid-Open No.
The polymer film described in JP-A-01-343529 (WO01 / 37007) can be used. Examples of the polymer material include a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and a nitrile group in the side chain. Can be used, for example, isobutene and N
-A resin composition having an alternating copolymer of methylene maleimide and an acrylonitrile / styrene copolymer. The polymer film may be, for example, an extruded product of the resin composition.

The transparent alignment substrate as described above is, for example,
Although it may be a single layer, it may be, for example, a laminate in which different kinds of polymers are laminated from the viewpoint of improving strength, heat resistance, and adhesion of polymer and liquid crystal monomer.

The phase difference due to the birefringence may not be generated, or the phase difference due to the birefringence may be generated for the purpose of eliminating the polarization state of the light reflected by the polarization separation layer. . Such elimination of the polarization state is friendly to the suppression of visual color layer change by improving the light utilization efficiency and making the light source light the same. As the transparent substrate that causes the phase difference due to the birefringence, for example, stretched films made of various polymers can be used, and those having a controlled refractive index in the thickness direction may be used. The control can be performed by, for example, adhering a polymer film to a heat shrinkable film and heating and stretching.

The thickness of the plastic film is usually 5 μm to 500 μm, preferably 10 to 200 μm.
And preferably 15 to 150 μm. When the thickness is 5 μm or more, the substrate has sufficient strength, so that problems such as breakage during manufacturing can be prevented.

As the optical compensation layer in the optical compensation plate of the present invention, not only such non-liquid crystal polymer but also
A liquid crystal polymer may be a constituent molecule. In this case, for example, a step of developing a coating liquid containing the above-described liquid crystal polymer and the chiral agent on an alignment substrate to form a development layer, the liquid crystal polymer has a cholesteric structure. A cholesteric layer having a liquid crystal polymer as a constituent molecule can be formed by a manufacturing method including a step of subjecting the spreading layer to a heat treatment so as to be oriented.

Next, the polarizing plate of the present invention includes a polarizer, a transparent protective layer and the optical compensator of the present invention as described above, and the polarizer and the optical compensator have the transparent protective layer. It is characterized by being laminated through.

In the polarizing plate of the present invention, the structure is not particularly limited as long as the crack prevention layer is laminated on at least one surface of the optical compensation layer, but examples thereof include the following forms. .

First, there is a mode in which the optical compensation plate and the transparent protective layer are directly adhered by the crack prevention layer in the optical compensation plate. Such a polarizing plate
For example, in producing the optical compensation plate, after coating the curable adhesive on the surface of the optical compensation layer, a laminate of a transparent protective layer and a polarizer is further added to the coating film of the curable adhesive. It can be formed by arranging and contacting the both, and then curing the coating film. In such a form, the crack prevention layer, while preventing cracks in the optical compensation layer, also plays a role of adhesion between the laminate of the polarizer and the transparent protective layer, and the optical compensation layer. A polarizing plate excellent in strength and thinning. Incidentally, the laminate of the transparent protective layer and the polarizer, the transparent protective layer is arranged so as to contact the coating film of the curable adhesive, the transparent protective layer and the crack prevention layer directly Adhesion is preferred.

The transparent protective layer may be laminated on only one surface of the polarizer, or may be laminated on both surfaces. When laminated on both sides, for example, the same type of transparent protective layer may be used, or different types of transparent protective layers may be used.

The crack prevention layer may be laminated on only one surface of the optical compensation layer,
It may be laminated on both sides.

When the crack prevention layer is laminated on only one surface of the optical compensation layer as described above, the surface of the optical compensation plate opposite to the surface of the optical compensation layer on which the crack prevention layer is laminated is provided. It is preferable that, for example, a pressure-sensitive adhesive layer is further laminated on the surface. It is preferable that the crack prevention layer and the polarizer, which are laminated on the surface of the optical compensation layer, are laminated via a transparent protective layer. In such a form, the crack prevention layer not only prevents cracks in the optical compensation layer, but also the pressure-sensitive adhesive layer facilitates, for example, a liquid crystal cell or another optical member when necessary. It becomes possible to attach it to. Further, since the pressure-sensitive adhesive layer can be made thin, the polarizing plate of the present invention can be made thin.

The thickness of the pressure-sensitive adhesive layer is not particularly limited, but is, for example, in the range of 5 to 50 μm, more preferably 10 to 40 μm, and particularly preferably 15 to 35 μm.
m.

The material for forming the pressure-sensitive adhesive layer is not particularly limited as long as it has a pressure-sensitive adhesive force. For example, conventionally known pressure-sensitive adhesives such as acrylic resin-based pressure-sensitive adhesives, rubber-based pressure-sensitive adhesives and vinyl-based pressure-sensitive adhesives. Can be used.

To form the pressure-sensitive adhesive layer on the surface of the optical compensation layer, for example, a solution or a melt of the forming material is directly added to the surface by a spreading method such as casting or coating to form a layer. It can be carried out by a method of forming, a method of forming a pressure-sensitive adhesive layer on a liner (release film) described later in the same manner, and transferring it to the surface of the optical compensation layer.

When the pressure-sensitive adhesive layer is laminated on the other surface of the optical compensation layer as described above, the pressure-sensitive adhesive layer of the above-mentioned pressure-sensitive adhesive layer can be used until the pressure-sensitive adhesive layer is put on another member for practical use. For the purpose of preventing contamination of the exposed surface and maintaining the adhesive strength, it is preferable to dispose a liner on the surface of the pressure-sensitive adhesive layer to cover the surface. This liner can be formed by a method of providing a release coat with a release agent such as silicone-based, long-chain alkyl-based, fluorine-based, molybdenum sulfide or the like on a suitable film such as a transparent protective film described below, if necessary. . Since the liner is peeled off when the polarizing plate of the present invention is used, its thickness is not particularly limited,
The thickness may be the same as that conventionally known.

On the other hand, when crack preventing layers are formed on both sides of the optical compensating layer, one crack preventing layer in the optical compensating plate and the polarizer are laminated via a transparent protective layer. It is preferable. Further, in the optical compensation plate, it is preferable that a pressure-sensitive adhesive layer and a liner are further arranged in this order on the surface of the other crack prevention layer in which the polarizer is not laminated via the transparent protective layer. By thus laminating the crack prevention layer on both sides of the optical compensation layer, the strength can be further improved, and the pressure-sensitive adhesive layer also facilitates bonding with other members.

In the polarizing plate of the present invention, the polarizer is not particularly limited, and a conventionally known polarizing film can be used. Specifically, for example, those prepared by adsorbing a dichroic substance such as iodine or a dichroic dye to various films by a conventionally known method, dyeing, crosslinking, stretching, and drying are used. it can. Among these, a film that transmits linearly polarized light when natural light is incident thereon is preferable, and a film having excellent light transmittance and polarization degree is preferable. Examples of various films for adsorbing the dichroic substance include hydrophilic polymer films such as PVA-based films, partially formalized PVA-based films, ethylene / vinyl acetate copolymer-based partially saponified films, and cellulose-based films. I can give you
In addition to these, for example, a polyene oriented film such as a dehydrated product of PVA or a dehydrochlorinated product of polyvinyl chloride can be used. Of these, PVA-based films are preferable. The thickness of the polarizing film is usually
The range is from 1 to 80 μm, but is not limited thereto.

The transparent protective layer is not particularly limited, and a conventionally known transparent film can be used.
Those having excellent transparency, mechanical strength, thermal stability, moisture barrier property, isotropic property, etc. are preferable. Specific examples of the material of such a transparent protective layer include cellulose-based resins such as triacetyl cellulose, polyester-based, polycarbonate-based, polyamide-based, polyimide-based, polyether sulfone-based, polysulfone-based, polystyrene-based, and polynorbornene. Examples include transparent resins such as resins, polyolefins, acrylics and acetates. In addition, the acrylic,
Other examples include urethane-based, acrylic urethane-based, epoxy-based, and silicone-based thermosetting resins or UV-curable resins. Among these, a TAC film having a surface saponified with an alkali or the like is preferable from the viewpoint of polarization characteristics and durability.

Further, a polymer film described in JP 2001-343529 A (WO 01/37007) may be mentioned. Examples of the polymer material include a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and a nitrile group in the side chain. Can be used, and examples thereof include a resin composition having an alternating copolymer of isobutene and N-methylenemaleimide and an acrylonitrile / styrene copolymer. The polymer film may be, for example, an extruded product of the resin composition.

The transparent protective layer preferably has no color, for example. Specifically, the retardation value (Rth) in the film thickness direction represented by the following formula is -90 nm to
The range is preferably +75 nm, more preferably -80 nm to +60 nm, and particularly preferably -7.
It is in the range of 0 nm to +45 nm. The phase difference value is -9
Within the range of 0 nm to +75 nm, the coloring (optical coloring) of the polarizing plate due to the protective film can be sufficiently eliminated. In the formula below, nx, ny, and nz respectively represent the refractive indices in the X-axis, Y-axis, and Z-axis directions of the transparent protective layer, and the X-axis is the axial direction that exhibits the maximum in-plane refractive index. And the Y-axis is an axial direction perpendicular to the X-axis in the plane, and the Z-axis is a thickness direction perpendicular to the X-axis and the Y-axis. Further, d represents the thickness of the transparent protective layer. Rth = [[(nx + ny) / 2] -nz] · d

The transparent protective layer may further have an optical compensation function. As such a transparent protective layer having an optical compensation function, for example, for the purpose of preventing coloring or the like, or enlarging the viewing angle for good visual recognition, which is caused by a change in the viewing angle based on the phase difference in the liquid crystal cell. Known ones can be used. Specific examples include various stretched films obtained by uniaxially or biaxially stretching the transparent resin described above, oriented films such as liquid crystal polymers, and laminates in which an orientation layer such as liquid crystal polymers is arranged on a transparent substrate. To be Among these, because it is possible to achieve a wide viewing angle with good visibility,
An alignment film of the liquid crystal polymer is preferable, and an optical compensation retardation plate in which an optical compensation layer composed of a tilted alignment layer of a discotic or nematic liquid crystal polymer is supported by the above-mentioned triacetyl cellulose film is particularly preferable. . Examples of such an optical compensation retardation plate include commercially available products such as "WV film" manufactured by Fuji Photo Film Co., Ltd. The optical compensation retardation plate may be one in which optical properties such as retardation are controlled by laminating two or more film supports such as the retardation film or triacetyl cellulose film.

The thickness of the transparent protective layer is not particularly limited and can be appropriately determined depending on, for example, the phase difference and the protection strength, but is usually 5 mm or less, preferably 1 mm or less, more preferably 1 to 500 μm. The following range is particularly preferable, and the range is 5 to 150 μm.

The transparent protective layer is known in the art, for example, a method of applying the various transparent resins to the polarizing film, a method of laminating the transparent resin film, the optical compensation retardation plate or the like on the polarizing film. It can be appropriately formed by a method, or a commercially available product can be used.

Further, the transparent protective layer may be further subjected to, for example, a hard coat treatment, an antireflection treatment, a treatment for the purpose of preventing or diffusing sticking, antiglare or the like. The hard coat treatment is, for the purpose of preventing scratches on the surface of the polarizing plate, for example, a treatment of forming a cured film excellent in hardness and slipperiness, which is composed of a curable resin, on the surface of the transparent protective layer. Is. As the curable resin, for example, a silicone-based, urethane-based, acrylic-based, or epoxy-based UV-curable resin can be used, and the treatment can be performed by a conventionally known method. The prevention of sticking is intended to prevent adhesion with an adjacent layer. The antireflection treatment aims at preventing reflection of external light on the surface of the polarizing plate, and can be performed by forming a conventionally known antireflection layer or the like.

The antiglare treatment is intended to prevent visual interference of light transmitted through the polarizing plate due to reflection of external light on the surface of the polarizing plate. For example, the transparent protective layer can be formed by a conventionally known method. This can be performed by forming a fine uneven structure on the surface. Examples of the method for forming such a concavo-convex structure include a surface roughening method such as a sandblast method and embossing, and a method of forming the transparent protective layer by blending transparent fine particles with the transparent resin as described above. To be

Examples of the transparent fine particles include silica, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, and antimony oxide. In addition to these, inorganic fine particles having conductivity, cross-linking or It is also possible to use organic fine particles composed of uncrosslinked polymer particles or the like. The average particle size of the transparent fine particles is not particularly limited, but is, for example, 0.5 to 20 μm.
The range is m. The blending ratio of the transparent fine particles is
Although not particularly limited, in general, the transparent resin 1 as described above is used.
The range is preferably 2 to 70 parts by mass, more preferably 5 to 50 parts by mass, per 100 parts by mass.

The anti-glare layer containing the transparent fine particles may be used as, for example, the transparent protective layer itself, or may be formed as a coating layer on the surface of the transparent protective layer. Further, the anti-glare layer may also serve as a diffusion layer (visual compensation function or the like) for diffusing the light transmitted through the polarizing plate and expanding the viewing angle.

The antireflection layer, the sticking prevention layer, the diffusion layer, the antiglare layer and the like are polarized separately from the transparent protective layer, for example, as an optical layer composed of a sheet or the like provided with these layers. It may be laminated on a plate.

In the polarizing plate of the present invention, the method for laminating the polarizer and the transparent protective layer is not particularly limited, and a conventionally known method can be used. Generally, a pressure sensitive adhesive, an adhesive or the like can be used. These types can be appropriately determined depending on the material of the polarizer and the transparent protective layer. The adhesive is not particularly limited, for example, acrylic-based, vinyl alcohol-based, silicone-based, polyester-based, polyurethane-based, polyether-based polymer adhesive or the like,
A rubber adhesive or the like can be used. Among these, for example, a material excellent in hygroscopicity and heat resistance is preferable. With such properties, for example, when the polarizer of the present invention is used in a liquid crystal display device or the like, it is possible to prevent foaming or peeling due to moisture absorption, deterioration of optical characteristics due to thermal expansion difference, warpage of a liquid crystal cell, etc. The display device has high quality and is excellent in durability.

Further, the above-mentioned pressure-sensitive adhesives and adhesives are difficult to peel off even under the influence of humidity and heat, and have excellent light transmittance and degree of polarization. Specifically, when the polarizer is a polyvinyl alcohol film, for example, a polyvinyl alcohol adhesive is preferable from the viewpoint of stability of the adhesive treatment. These adhesives and pressure-sensitive adhesives may be directly applied to the surface of the polarizer or the transparent protective layer, or the tape made of the pressure-sensitive adhesive may be arranged on the surface. In addition, for example, when prepared as an aqueous solution, other additives and a catalyst such as an acid may be added as necessary.

The pressure-sensitive adhesive layer may be, for example, a single layer body or a laminated body. As the laminated body, for example, a laminated body in which single layers of different compositions and different types are combined can be used. Further, when arranged on both sides of the polarizer, for example, may be the same adhesive layer,
It may have different compositions or different types of adhesive layers.

The thickness of the pressure-sensitive adhesive layer can be appropriately determined depending on, for example, the constitution of the polarizing plate, and is generally 1 to 500.
μm.

The adhesive property of the pressure-sensitive adhesive layer can be controlled by, for example, the composition and molecular weight of the base polymer forming the pressure-sensitive adhesive layer, the crosslinking method, the content ratio of the crosslinkable functional group, the mixing ratio of the crosslinking agent, and the like. This can be appropriately performed by a conventionally known method such as adjusting the degree of crosslinking or the molecular weight.

The optical compensating plate and the polarizing plate of the present invention may be treated with an ultraviolet absorber such as salicylate compound, benzophenone compound, benzotriazole compound, cyanoacrylate compound, nickel complex salt compound and the like. For example, it may have an ultraviolet absorbing ability.

The polarizing plate of the present invention is not limited to the above-mentioned constitution, and further has various optical members such as a retardation film having another refractive index structure, a liquid crystal film, a light diffusing film and a diffractive film. May be

As described above, the polarizing plate of the present invention can be used in various display devices such as liquid crystal display devices. The liquid crystal display device can be formed by a conventionally known method. That is, the liquid crystal display device is generally formed by appropriately assembling a liquid crystal cell and optical elements such as a polarizing plate, and if necessary, components such as an illumination system and incorporating a drive circuit. The display device is not particularly limited except that the polarizing plate of the present invention is used. Regarding the liquid crystal cell, for example, any type of cell such as TN type, STN type, and π type can be used.

Specifically, there is a liquid crystal display device in which the polarizing plate of the present invention is arranged on one side or both sides of a liquid crystal cell. In particular, when the polarizing plate of the present invention has an adhesive layer and a liner as described above, the liner is peeled off and the exposed adhesive layer is attached to the liquid crystal cell to arrange the polarizing plate. can do. When the retardation plate and the polarizing plate are provided on both sides of the liquid crystal cell when the polarizing plate is arranged in the liquid crystal cell, they may be the same or different. Also,
When forming a liquid crystal display device, for example, a diffusion plate, an anti-glare layer, an antireflection layer, a protection plate, a prism array sheet, a lens array sheet, a light diffusion plate, a backlight, a reflection plate, a semi-transmissive reflection plate, and brightness enhancement. One or two or more layers may be arranged at appropriate positions such as plates.

Next, the polarizing plate of the present invention can be used in an organic EL device in the same manner as in the liquid crystal display device.

Generally, in an organic EL device, a light emitting body (organic EL light emitting body) is formed by sequentially laminating a transparent electrode, an organic light emitting layer and a metal electrode on a transparent substrate. Here, the organic light emitting layer is a laminated body of various organic thin films, for example, a laminated body of a hole injection layer made of a triphenylamine derivative or the like and a light emitting layer made of a fluorescent organic solid such as anthracene or Alternatively, a structure having various combinations such as a laminated body of the light emitting layer and an electron injection layer formed of a perylene derivative or the like, or alternatively, a laminated body of the hole injection layer, the light emitting layer and the electron injection layer is known. There is.

In the organic EL device, holes and electrons are usually injected into the organic light emitting layer by applying a voltage to the transparent electrode and the metal electrode, and the holes and electrons are recombined. The energy generated by excites the fluorescent substance, and the excited fluorescent substance emits light when returning to the ground state. The mechanism of recombination in the middle is similar to that of a general diode, and as can be expected from this, the current and the emission intensity show a strong nonlinearity with rectification with respect to the applied voltage.

In the organic EL device, at least one of the electrodes is preferably transparent in order to take out light emitted from the organic light emitting layer. Usually, indium tin oxide (IT) is used.
A transparent electrode formed of a transparent conductor such as O) is used as an anode. On the other hand, it is important to use a substance having a small work function for the cathode in order to facilitate electron injection and increase the light emission efficiency, and a metal electrode such as Mg-Ag or Al-Li can be usually used.

In the organic EL device having such a structure,
The organic light emitting layer is usually formed as an extremely thin film having a thickness of about 10 nm. Therefore, the organic light emitting layer can almost completely transmit light, like the transparent electrode. As a result, when entering from the surface of the transparent substrate during non-light emission, the light transmitted through the transparent electrode and the organic light emitting layer and reflected by the metal electrode goes out to the surface side of the transparent substrate again, when viewed from the outside, Organic EL
The display surface of the device looks like a mirror surface.

In an organic EL device including an organic EL light-emitting body having a transparent electrode on the front surface side of the organic light-emitting layer which emits light when a voltage is applied and a metal electrode on the back surface side of the organic light-emitting layer, for example, a transparent electrode is used. A polarizing plate may be provided on the surface side of the electrode, and a retardation plate may be provided between the transparent electrode and the polarizing plate. As the polarizing plate, the polarizing plate of the present invention can be applied.

Since the phase plate and the polarizing plate have a function of polarizing the light incident from the outside and reflected by the metal electrode, there is an effect that the mirror surface of the metal electrode is not visually recognized from the outside by the polarization action. Especially, if the phase plate is 1 /
The mirror surface of the metal electrode can be completely shielded by using a four-wave plate and adjusting the angle between the polarization directions of the polarizing plate and the phase plate to π / 4.

That is, as for the external light incident on the organic EL device, only the linearly polarized light component is transmitted by the polarizing plate. This linearly polarized light is generally elliptically polarized light due to the phase plate,
In particular, when the phase plate is a quarter-wave plate and the angle formed by the polarization directions of the polarizing plate and the phase plate is π / 4, it becomes circularly polarized light.

[0131] The circularly polarized light is generally transparent substrate, a transparent electrode, transmitted through the organic thin film, and is reflected by the metal electrode, again organic thin film, the transparent electrode, through the transparent substrate, a phase plate and again linearly polarized light Become. Since this linearly polarized light is orthogonal to the polarization direction of the polarizing plate, it cannot pass through the polarizing plate. As a result, the mirror surface of the metal electrode can be completely shielded.

The polarizer of the present invention is not limited to the liquid crystal display device and the EL device as described above, but may be used in various self-luminous image display devices such as a plasma display and an FED display. Can also be applied.

[0133]

EXAMPLES Next, the present invention will be further described with reference to the following examples and comparative examples. The present invention is not limited to these examples.

(Example 1) 1 wt% polyvinyl alcohol (PVA) (manufactured by Nippon Synthetic Chemical Co., Ltd .; commercial product) on a 50 μm thick triacetyl cellulose (TAC) film (manufactured by Fuji Photo Film Co .; trade name T-50SH) Name NH
-18) An aqueous solution was applied and dried at 90 ° C. to form a PVA film having a film thickness of about 0.01 μm or less. The surface of this film was rubbed to form an alignment film. On the other hand, the liquid crystal monomer of the formula (6) (polymerizable rod-shaped nematic liquid crystal)
And the chiral agent of the formula (44) are mixed in a weight ratio of 8: 1, and the mixture is dissolved in toluene so that the weight ratio is 30% by weight. The toluene solution is further mixed with a photopolymerization initiator. (Trade name Irgacure: manufactured by Ciba Specialty Chemicals Co., Ltd.) was added in an amount of 3% by weight to prepare a coating solution. The coating liquid is applied to the alignment film and the temperature is 90 ° C.
After aligning the liquid crystal monomer by heat treatment for 1 minute, the liquid crystal monomer was further polymerized by UV irradiation to fix the alignment. And the T
By removing the AC film and PVA coating,
An optical compensation layer having a thickness of 5 μm was obtained. This optical compensation layer has an in-plane retardation of 1 nm and a thickness direction retardation of 200 nm.
was nm.

The obtained optical compensation layer and a commercially available polarizing plate (manufactured by Nitto Denko KK; trade name SEG5224DU) were mixed with an isocyanate-based adhesive (solvent: ethyl acetate) in which the solid content of the isocyanate compound was 30% by weight. ) (Thickness 5μ
m) was used for adhesion by roll pressure bonding. The adhesive was cured by drying at 50 ° C. for 10 hours. The thickness of the crack preventing layer made of a curable adhesive formed by curing the adhesive was 5 μm, and the indentation hardness was 0.2 GPa. The adhesive was further applied to the surface of the layered product on the side of the optical compensation layer so as to have a thickness of 5 μm, and a crack preventing layer was formed in the same manner (thickness 5 μm, indentation hardness 0.2 GPa).

Next, a liner (release film) (manufactured by Nitto Denko: trade name RT-38) was formed on the exposed surface of the adhesive layer.
G, same below), acrylic adhesive (same below)
(Thickness 20 μm) was used for roll compression. This produced the polarizing plate with an optical compensation layer.

(Embodiment 2) In the same manner as in Embodiment 1,
A polarizing plate is laminated on one surface of the optical compensation layer using the isocyanate adhesive (thickness 5 μm), and the liner is roll-pressed onto the optical compensation layer side surface of the laminate using the acrylic pressure-sensitive adhesive. did. This produced the polarizing plate with an optical compensation layer. The indentation hardness of the crack prevention layer formed of the adhesive was 0.2 GPa.

Comparative Example 1 A polarizing plate with an optical compensation layer was prepared in the same manner as in Example 1 except that the acrylic adhesive was used instead of the isocyanate adhesive and the polarizing plate and the liner were laminated. A plate was made. The indentation hardness of the layer formed from the pressure-sensitive adhesive could not be measured.

The polarizing plates with optical compensation layers obtained in Examples 1 and 2 and Comparative Example 1 were cut into a sample of 50 × 150 mm to prepare samples, and cracks were generated in the optical compensation layers when a load was applied. Was observed. The method will be described below.

The sample was placed on a horizontal table with the release film side facing up. And a Haydon surface measuring instrument (manufactured by Shinto Chemical Co., Ltd .; trade name HEIDON-14
From the liner side, a predetermined load (20
The pen tip having a diameter of 0.5 mm was reciprocated twice while applying 0 g and 400 g), and the occurrence of cracks in the optical compensation layer was visually observed. Table 1 below shows these results.

(Table 1) Example 1 Example 2 Configuration of Comparative Example 1 Polarizing plate Polarizing plate Polarizing plate Isocyanate-based adhesive Isocyanate-based adhesive Acrylic pressure-sensitive adhesive Optical compensation layer Optical compensation layer Optical compensation layer Isocyanate-based adhesive Acrylic Adhesive Acrylic adhesive Load 200g No crack No crack No crack 400g No crack No crack No crack

As described above, in the polarizing plate of the example in which the crack preventive layer was formed on at least one of the optical compensation layers with a curable adhesive, unlike the comparative example, cracks did not occur even when locally pressed. I couldn't see it. Further, in the polarizing plate of Example 1 in which the isocyanate-based adhesive layer was formed on both surfaces of the optical compensation layer, cracking was not confirmed even when a load of 600 g was further applied. As described above, it has been found that the strength is improved by providing the crack prevention layer on at least one surface of the optical compensation layer.

[0143]

As described above, in the optical compensating plate of the present invention, the crack preventing layer made of a curable adhesive prevents the occurrence of cracks in the optical compensating layer due to vibration or local pressure. it can. For this reason, for example, it is difficult to be affected by vibrations in the distribution process and impacts during use, so that color fading due to cracks is prevented, and an image display device of excellent quality can be provided.

[Brief description of drawings]

FIG. 1 is a schematic view showing an axial direction of a refractive index.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takashi Yamaoka             1-2 1-2 Shimohozumi, Ibaraki City, Osaka Prefecture Nitto             Electric Works Co., Ltd. (72) Inventor Masayuki Kawai             1-2 1-2 Shimohozumi, Ibaraki City, Osaka Prefecture Nitto             Electric Works Co., Ltd. (72) Inventor, Kazuko Wazai             1-2 1-2 Shimohozumi, Ibaraki City, Osaka Prefecture Nitto             Electric Works Co., Ltd. (72) Inventor Naru Murakami             1-2 1-2 Shimohozumi, Ibaraki City, Osaka Prefecture Nitto             Electric Works Co., Ltd. F-term (reference) 2H049 BA02 BA06 BA42 BB03 BB22                       BB25 BB51 BC22                 2H091 FA08X FA08Z FA11X FA11Z                       FA12X FA12Z FB02 FB04                       FD06 FD14 GA06 KA04 LA02                       LA30

Claims (21)

[Claims] 1. An optical compensation plate including an optical compensation layer, comprising:
An optical compensation plate in which a crack prevention layer made of a curable adhesive is directly laminated on at least one surface of the optical compensation layer. 2. The indentation hardness of the crack prevention layer is
The optical compensator according to claim 1, which is in the range of 0.1 to 0.5 GPa. 3. The optical compensator according to claim 1, wherein the curable adhesive contains at least one adhesive of a photo-curable resin adhesive and a moisture-curable resin adhesive. 4. The optical compensator according to claim 1, wherein the curable adhesive is at least one thermosetting resin-based adhesive selected from the group consisting of epoxy resin, isocyanate resin and polyimide resin. 5. The optical compensator according to claim 3, wherein the moisture-curable resin adhesive is an isocyanate resin adhesive. 6. The crack prevention layer has a thickness of 0.1 to
The optical compensator according to any one of claims 1 to 5, which has a range of 20 µm. 7. The optical compensation plate according to claim 1, wherein the optical compensation layer is a cholesteric layer in which the constituent molecules are oriented in a cholesteric structure. 8. The thickness of the cholesteric layer is 0.5-1.
The optical compensator according to claim 7, wherein the optical compensator has a range of 0 μm. 9. The optical element according to claim 7, wherein the constituent molecule of the cholesteric layer is a non-liquid crystal polymer, and the non-liquid crystal polymer is a polymer obtained by polymerizing or cross-linking a liquid crystal monomer oriented in a cholesteric structure. Compensator. 10. The optical compensator according to claim 9, wherein the helical pitch of cholesteric orientation is in the range of 0.01 to 0.25 μm. 11. The optical compensator according to claim 7, wherein the constituent molecule of the cholesteric layer is a liquid crystal polymer, and the liquid crystal polymer is oriented in a cholesteric structure. 12. A polarizer, a transparent protective layer, and 1 to 1.
12. A polarizing plate comprising the optical compensatory plate according to any one of 11 above, wherein the polarizer and the optical compensatory plate are laminated via the transparent protective layer. 13. The polarizing plate according to claim 12, wherein the optical compensation plate and the transparent protective layer are directly adhered to each other by the crack prevention layer in the optical compensation plate. 14. The polarizing plate according to claim 12, wherein a pressure-sensitive adhesive layer is laminated on the surface of the optical compensation plate opposite to the surface of the optical compensation layer on which the crack prevention layer is laminated. 15. The polarizing plate according to claim 14, wherein the material for forming the pressure-sensitive adhesive layer is at least one resin-based pressure-sensitive adhesive selected from the group consisting of acrylic resin, rubber resin, and vinyl resin. 16. The optical compensation plate has a structure in which the crack prevention layer is laminated on both surfaces of the optical compensation layer, and one crack prevention layer and the polarizer are laminated via the transparent protective layer. The polarizing plate according to claim 12 or 13, which is provided. 17. The polarizing plate according to claim 16, wherein in the optical compensation plate, a pressure-sensitive adhesive layer and a liner are further arranged in this order on the surface of the crack prevention layer on which the polarizer is not laminated. 18. The polarizing plate according to claim 14, further comprising a liner disposed on the surface of the pressure-sensitive adhesive layer. 19. A liquid crystal cell, and an optical member of at least one of the optical compensating plate according to any one of claims 1 to 11 and the polarizing plate according to any one of claims 12 to 16. LCD panel. 20. A liquid crystal display device including a liquid crystal panel, wherein the liquid crystal panel is the liquid crystal panel according to claim 19. 21. Electroluminescence (EL) display, plasma display (PD) and FE.
D (Field Emission Display)
At least one image display device selected from the group consisting of: the optical compensator according to any one of claims 1 to 11, and the polarizing plate according to any one of claims 12 to 16. An image display device including at least one optical member.