JP2002139621A - Optical compensation sheet, polarization plate and liquid crystal display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display of high display quality. SOLUTION: An optical compensation sheet, composed of a sheet of a cellulose acetate film, containing cellulose acetate with the acetylation degree in 59.0-61.5% range and 0.01-20 pts.mass aromatic compound with at least two aromatic rings per 100 pts.mass cellulose acetate, and having a thickness in 10-70 μm range, having Re retardation value in 20-70 nm range and having Rth retardation value in 70-400 nm range is used for the liquid crystal display device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical compensatory sheet, a polarizing plate using the same, and a liquid crystal display.

[0002]

2. Description of the Related Art A liquid crystal display device comprises a polarizing plate and a liquid crystal cell. Currently the mainstream TN (Twisted Nemati
c) In a mode TFT (Thin Film Transistor) liquid crystal display device, an optical compensation film is inserted between a polarizing plate and a liquid crystal cell as described in JP-A-8-50206,
A liquid crystal display device with high display quality has been realized. However, this method has a problem that the liquid crystal display device itself becomes thick. JP-A-1-68940 discloses that
A statement that front contrast can be increased without increasing the thickness of the liquid crystal display device by using an optical compensation sheet (retardation plate) on one side of the polarizing film and an elliptically polarizing plate having a protective film on the other side. There is. However, in the optical compensatory sheet of the present invention, a phase difference is easily generated due to distortion such as heat, and the phase difference causes a frame-like transmittance increase (light leakage) at the time of black display of the liquid crystal display device, resulting in an endurance. It turned out that there was a problem with sex. To solve the problem of phase difference due to distortion, Japanese Patent Application Laid-Open No. Hei 7-191217 and European Patent No. 0911656A2 disclose an optical compensation sheet in which an optically anisotropic layer made of a discotic compound is coated on a transparent support. By using the film as a protective film for a polarizing plate, the above-mentioned problem relating to durability is solved without increasing the thickness of the liquid crystal display device.

[0003]

However, when a polarizing plate using the above-described optical compensation film as a protective film is mounted on a large panel of 17 inches or more, the frame-shaped transmittance increase due to thermal distortion is completely prevented. Turned out to be gone. An object of the present invention is to provide a liquid crystal display device having a high display quality without causing any problem by disposing an optical compensation sheet on one side of a polarizing film. Another object of the present invention is to provide an optical compensation sheet having stable optical compensation characteristics against thermal distortion. Still another object of the present invention is to provide an optical compensatory sheet that can be disposed on one side of a polarizing film in a continuous process. Yet another object of the present invention is to increase the number of components of the polarizing plate,
The purpose is to add an optical compensation function to the polarizing plate.

[0004]

The inventors of the present invention have made intensive studies and found that the above-mentioned problem of the frame-shaped increase in transmittance is caused by the following two causes. The first cause is
This is a change in wet heat conditions in the environment where the liquid crystal display device is placed. The optical compensation sheet disposed on the liquid crystal display device is fixed to a polarizing film or a liquid crystal cell with an adhesive or the like. Since the expansion or shrinkage of the polymer film due to the change in the moist heat condition is suppressed as the entire optical compensation sheet (fixed to a liquid crystal cell or the like), the optical characteristics of the optical compensation sheet change, causing light leakage. I understood that.
The second cause is that a temperature distribution is generated in the surface of the optical compensation sheet due to lighting of a backlight used in the liquid crystal display device or the like. It has been found that thermal distortion occurs in the optical compensatory sheet due to this temperature distribution, and the thermal distortion causes the same change in optical characteristics as described above to cause light leakage.
In particular, it has been found that a polymer having a hydroxyl group such as a cellulose ester is greatly affected by changes in environmental conditions.

In order to eliminate the light leakage, the change in the optical characteristics of the optical compensation sheet may be reduced, and the temperature distribution generated in the optical compensation sheet may be reduced. It has been found that the change in the optical characteristics is determined by the product of the photoelastic coefficient, the thickness, the virtual strain due to the change in environmental conditions, and the elastic modulus of the optical compensation sheet. Therefore, light leakage is significantly reduced by reducing the photoelastic coefficient, reducing the thickness, reducing distortion due to changes in environmental conditions, and reducing the elastic modulus of the optical compensation sheet. Further, the temperature distribution generated in the optical compensation sheet is reduced by increasing the thermal conductivity of the optical compensation sheet, and light leakage is reduced.

Accordingly, an object of the present invention is to provide the following (1) to
This was achieved by the optical compensation sheet of (11), the polarizing plate of (12) to (13) below, and the liquid crystal display of (14) to (16) below. (1) Cellulose acetate having a degree of acetylation in the range of 59.0 to 61.5%, and cellulose acetate 10
It is composed of one sheet of cellulose acetate film containing 0.01 to 20 parts by mass of an aromatic compound having at least two aromatic rings and having a thickness of 10 to 70 μm with respect to 0 parts by mass. An optical compensatory sheet wherein the Re retardation value defined by I) is in the range of 20 to 70 nm, and the Rth retardation value defined by the following formula (II) is in the range of 70 to 400 nm. (I) Re = (nx−ny) × d (II) Rth = {(nx + ny) / 2−nz} × d where nx is the refractive index in the slow axis direction in the film plane; , Is the refractive index in the fast axis direction in the film plane; nz is the refractive index in the film thickness direction; and d is the film thickness. (2) The cellulose acetate film further contains 0.1 to 30 parts by mass of polyester urethane based on 100 parts by mass of cellulose acetate, and the polyester urethane is formed of a polyester and a diisocyanate represented by the following general formula. The optical compensation sheet according to (1), which is a reactant. H-(-O- (CH ₂ ) _q -OOC- (CH ₂ ) _m -CO) _n -O- (CH ₂ ) _q -OH wherein q represents an integer of 2 to 4; Represents an integer of 2 to 4; n represents an integer of 1 to 100.

(3) Cellulose acetate having a degree of acetylation in the range of 59.0 to 61.5%, and an aromatic compound having at least two aromatic rings in an amount of 0.01 part by mass per 100 parts by mass of cellulose acetate. An optically anisotropic layer formed from a liquid crystal compound is provided on a cellulose acetate film having a thickness of 10 to 70 μm, the cellulose acetate film having the following formula (I): An optical compensation sheet characterized by having a Re retardation value defined by the following formula (1) in the range of 20 to 70 nm and an Rth retardation value defined by the following formula (II) in the range of 70 to 400 nm. (I) Re = (nx−ny) × d (II) Rth = {(nx + ny) / 2−nz} × d where nx is the refractive index in the slow axis direction in the film plane; , Is the refractive index in the fast axis direction in the film plane; nz is the refractive index in the film thickness direction; and d is the film thickness. (4) The cellulose acetate film further contains 0.1 to 30 parts by mass of polyester urethane based on 100 parts by mass of cellulose acetate, and the polyester urethane is formed of a polyester represented by the following general formula and a diisocyanate. the optical compensation sheet according to (2) that is a reaction product: H - (- O- (CH 2) q -OOC- (CH 2) m -CO) n -O- (CH 2) q In the formula, q represents an integer of 2 to 4; m represents an integer of 2 to 4; n represents an integer of 1 to 100.

(5) The optical compensation sheet according to (3) or (4), wherein the liquid crystal compound is a discotic liquid crystal compound. (6) The optical compensatory sheet according to (1), wherein the cellulose acetate film is a stretched product stretched at a stretch ratio of 3 to 100%. (7) The cellulose acetate film according to any one of (1) to (4), wherein the cellulose acetate film contains high thermal conductive particles, and has a thermal conductivity of 1 W / (m · K) or more. 4. The optical compensation sheet according to item 1. (8) A heat conductive layer containing high heat conductive particles is provided on at least one surface of the cellulose acetate film, and the cellulose acetate film having the heat conductive layer has a heat conductivity of 1 W / (m · K) or more. The optical compensation sheet according to any one of (1) to (4), wherein

(9) The optical compensation according to any one of (1) to (4), wherein the aromatic compound has at least one 1,3,5-triazine ring. Sheet. (10) The optical compensation sheet according to any one of (1) to (4), wherein the cellulose acetate film is formed by a co-casting method. (11) The optical compensation sheet according to any one of (1) to (4), wherein the cellulose acetate film is a biaxially stretched film.

(12) A polarizing plate comprising a polarizing film and two transparent protective films disposed on both sides thereof, wherein one of the transparent protective films has an acetylation degree of 59.0 to 61.5%. And 0.01 to 20 parts by mass of an aromatic compound having at least two aromatic rings with respect to 100 parts by mass of cellulose acetate, and one sheet of cellulose having a thickness of 10 to 70 μm. The cellulose acetate film has a Re retardation value defined by the following formula (I) in the range of 20 to 70 nm, and an Rth retardation value defined by the following formula (II) of 70 to 400 nm. And the slow axis of the cellulose acetate film is substantially parallel to the transmission axis of the polarizing film. A polarizing plate characterized in that it is disposed. (I) Re = (nx−ny) × d (II) Rth = {(nx + ny) / 2−nz} × d where nx is the refractive index in the slow axis direction in the film plane; , Is the refractive index in the fast axis direction in the film plane; nz is the refractive index in the film thickness direction; and d is the film thickness.

(13) A polarizing plate comprising a polarizing film and two transparent protective films disposed on both sides thereof, wherein one of the transparent protective films has an acetylation degree in the range of 59.0 to 61.5%. And 0.01 to 20 parts by mass of an aromatic compound having at least two aromatic rings with respect to 100 parts by mass of cellulose acetate and cellulose acetate film having a thickness of 10 to 70 μm. Is provided with an optically anisotropic layer formed from a liquid crystal compound, the cellulose acetate film has a Re retardation value defined by the following formula (I) in the range of 20 to 70 nm, and The Rth retardation value defined by (II) is in the range of 70 to 400 nm, and the cellulose acylate film A polarizing plate characterized in that the axis and the transmission axis of the polarizing film are arranged so as to be substantially parallel. (I) Re = (nx−ny) × d (II) Rth = {(nx + ny) / 2−nz} × d where nx is the refractive index in the slow axis direction in the film plane; , Is the refractive index in the fast axis direction in the film plane; nz is the refractive index in the film thickness direction; and d is the film thickness.

(14) A liquid crystal display device comprising a liquid crystal cell and two polarizing plates disposed on both sides thereof, wherein the polarizing plate comprises a polarizing film and two transparent protective films disposed on both sides thereof. At least one of the two transparent protective films disposed between the liquid crystal cell and the polarizing film has an acetylation degree of 5
It contains 0.01 to 20 parts by mass of an aromatic compound having at least two aromatic rings with respect to cellulose acetate in a range of 9.0 to 61.5% and 100 parts by mass of cellulose acetate, and has a thickness of 10 to 10 parts by mass. To 7
A cellulose acetate film having a Re retardation value of 20 μm in the range of 0 μm, defined by the following formula (I):
And the Rth retardation value defined by the following formula (II) is 70 to 400 n.
m, wherein the slow axis of the cellulose acetate film and the transmission axis of the polarizing film adjacent to the cellulose acetate film are arranged substantially parallel to each other. (I) Re = (nx−ny) × d (II) Rth = {(nx + ny) / 2−nz} × d where nx is the refractive index in the slow axis direction in the film plane; , Is the refractive index in the fast axis direction in the film plane; nz is the refractive index in the film thickness direction; and d is the film thickness.

(15) A liquid crystal display device comprising a liquid crystal cell and two polarizing plates disposed on both sides thereof, wherein the polarizing plate comprises a polarizing film and two transparent protective films disposed on both sides thereof. At least one of the two transparent protective films disposed between the liquid crystal cell and the polarizing film has an acetylation degree of 5
It contains 0.01 to 20 parts by mass of an aromatic compound having at least two aromatic rings with respect to cellulose acetate in a range of 9.0 to 61.5% and 100 parts by mass of cellulose acetate, and has a thickness of 10 to 10 parts by mass. To 7
An optically anisotropic layer formed of a liquid crystal compound is provided on a cellulose acetate film having a thickness of 0 μm, and the cellulose acetate film has a Re retardation value defined by the following formula (I) of 20.
And the Rth retardation value defined by the following formula (II) is 70 to 400 n.
m, wherein the slow axis of the cellulose acetate film and the transmission axis of the polarizing film close to the cellulose acetate film are arranged substantially parallel to each other. (I) Re = (nx−ny) × d (II) Rth = {(nx + ny) / 2−nz} × d where nx is the refractive index in the slow axis direction in the film plane; , Is the refractive index in the fast axis direction in the film plane; nz is the refractive index in the film thickness direction; and d is the film thickness. (16) TN mode, VA mode, MVA
2. A liquid crystal cell of a mode or an OCB mode.
16. The liquid crystal display device according to 4 or 15.

In this specification, "substantially parallel" means that the angle is within a range of less than ± 5 ° from the strict angle. This range is preferably less than ± 4 °, more preferably less than ± 3 °, and
Most preferably, it is less than 2 °. Also, in this specification, "slow axis" means the direction in which the refractive index is maximum, and "transmission axis" means the direction in which the transmittance is maximum.

[0015]

The present inventor solves the problem of frame-like transmittance increase (light leakage) of a liquid crystal display device due to thermal distortion by adjusting manufacturing conditions such as reducing the thickness of an optical compensation sheet. Succeeded. The use of the optical compensation sheet of the present invention succeeded in optically compensating the liquid crystal cell with no side effect at the conventional thickness or less. Since the optical compensation sheet of the present invention has a small thickness, the manufacturing cost of the liquid crystal display device can be reduced, and the thickness of the liquid crystal display device can be reduced. Further, by using the optical compensation sheet of the present invention as one protective film of a conventional polarizing plate in which transparent protective films are provided on both sides of the polarizing film, an optical compensation function can be imparted to the polarizing plate. The optical compensatory sheet and the polarizing plate using the optical compensatory sheet as a protective film are VA (Vertically Aligned) type, OCB
(Optically Compensated Bend), TN (Twisted Nema)
The present invention can be particularly advantageously used for a tic) type liquid crystal display device and a reflection type liquid crystal display device.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [Prevention of Light Leakage] According to the inventor's intensive research, the frame-shaped transmittance increase in a liquid crystal display device can be achieved by an optical compensation sheet (polarizing film) interposed between a polarizing film and a liquid crystal cell. It was found that the dimensional change due to the heat and humidity of the protective film (including the protective film) was suppressed by the adhesive, and the stress generated thereby caused birefringence (photoelasticity). The transmittance has a correlation with the product (phase difference) of the developed birefringence and the thickness of the sheet, and the transmittance increases as the phase difference increases. Therefore, by reducing the thickness, even if the same birefringence is developed, the phase difference is reduced, and the increase in transmittance is reduced. However, if the thickness is too small, the durability of the polarizing film is lowered, or the handling when attaching the polarizing film to the liquid crystal panel is deteriorated. Therefore, the thickness of the optical compensatory sheet required to prevent the frame-shaped transmittance from increasing in the liquid crystal display device is 1
It is preferably in the range of 0 to 70 μm, more preferably in the range of 20 to 60 μm, and more preferably in the range of 30 to 5 μm.
Most preferably, it is in the range of 0 μm.

As described above, in order to prevent a frame-shaped increase in transmittance (light leakage) of a liquid crystal display device, a change in optical characteristics of the optical compensation sheet is reduced, and a temperature distribution generated in the optical compensation sheet is reduced. Just do it. It has been found that the change in the optical characteristics is determined by the product of the photoelastic coefficient, the thickness, the virtual strain due to the change in environmental conditions, and the elastic modulus of the optical compensation sheet. Therefore, by further reducing the photoelastic coefficient of the optical compensatory sheet, reducing distortion due to changes in environmental conditions, and reducing the elastic modulus, light leakage is significantly reduced. Further, the temperature distribution generated in the optical compensation sheet is reduced by increasing the thermal conductivity of the optical compensation sheet, and light leakage is reduced.

[Retardation of Film] The Re retardation value and Rth retardation value of a film are defined by the following formulas (I) and (II), respectively. (I) Re = (nx−ny) × d (II) Rth = {(nx + ny) / 2−nz} × d In the formulas (I) and (II), nx is a slow axis direction in the film plane ( (The direction in which the refractive index becomes the maximum). In the formulas (I) and (II), ny is the refractive index in the fast axis direction (direction in which the refractive index is minimum) in the film plane. In the formula (II), nz is the refractive index in the thickness direction of the film. In formulas (I) and (II), d
Is the film thickness in nm.

In the present invention, the Re retardation value of the cellulose acetate film is adjusted to 20 to 70 nm, and the Rth retardation value is adjusted to 70 to 400 nm. When two optically anisotropic cellulose acetate films are used in a liquid crystal display device, the Rth of the film
The retardation value is preferably from 70 to 250 nm. When one sheet of optically anisotropic cellulose acetate film is used for a liquid crystal display device, the Rth of the film
The retardation value is preferably from 150 to 400 nm. The birefringence (Δn: nx−ny) of the cellulose acetate film is preferably from 0.00028 to 0.020. Further, the birefringence in the thickness direction of the cellulose acetate film ｛(nx + n
y) / 2-nz} is preferably 0.001 to 0.04.

[Cellulose Acetate] In the present invention, cellulose acetate having an acetylation degree of 59.0 to 61.5% is used. The acetylation degree means the amount of bound acetic acid per unit mass of cellulose. The degree of acetylation is ASTM: D-
According to the measurement and calculation of the degree of acetylation in 817-91 (test method for cellulose acetate and the like). The viscosity average degree of polymerization (DP) of the cellulose ester is preferably 250 or more, more preferably 290 or more. Further, the cellulose ester used in the present invention,
Mw / by gel permeation chromatography
It is preferable that the molecular weight distribution of Mn (Mw is a mass average molecular weight, Mn is a number average molecular weight) is narrow. Specific Mw / Mn
Is preferably from 1.0 to 1.7, more preferably from 1.3 to 1.65,
Most preferably, it is 1.4 to 1.6.

[Retardation increasing agent] In order to adjust the retardation of the cellulose acetate film,
An aromatic compound having at least two aromatic rings is used as a retardation increasing agent. The aromatic compound is
0.01 parts by mass relative to 100 parts by mass of cellulose acetate
It is used in the range of 20 to 20 parts by mass. The aromatic compound is preferably used in an amount of 0.05 to 15 parts by mass with respect to 100 parts by mass of cellulose acetate.
More preferably, it is used in the range of 10 to 10 parts by mass. Two or more aromatic compounds may be used in combination. In the aromatic ring of the aromatic compound, in addition to the aromatic hydrocarbon ring,
Including aromatic heterocycle.

The aromatic hydrocarbon ring is a six-membered ring (ie,
Benzene ring). Aromatic heterocycles are generally unsaturated heterocycles. The aromatic hetero ring is preferably a 5-, 6-, or 7-membered ring, more preferably a 5- or 6-membered ring.
Aromatic heterocycles generally have the most double bonds.
As the hetero atom, a nitrogen atom, an oxygen atom and a sulfur atom are preferable, and a nitrogen atom is particularly preferable. Examples of the aromatic hetero ring include a furan ring, a thiophene ring, a pyrrole ring,
Oxazole ring, isoxazole ring, thiazole ring,
Isothiazole ring, imidazole ring, pyrazole ring, furazane ring, triazole ring, pyran ring, pyridine ring, pyridazine ring, pyrimidine ring, pyrazine ring and 1,3,
Includes a 5-triazine ring. As the aromatic ring, benzene ring, furan ring, thiophene ring, pyrrole ring, oxazole ring, thiazole ring, imidazole ring, triazole ring, pyridine ring, pyrimidine ring, pyrazine ring and 1,3,5-triazine ring are preferable, A benzene ring and a 1,3,5-triazine ring are more preferred. It is particularly preferred that the aromatic compound has at least one 1,3,5-triazine ring.

The number of aromatic rings in the aromatic compound is 2
To 20, preferably 2 to 12, more preferably 2 to 8, and most preferably 2 to 6. The bonding relationship between two aromatic rings is as follows: (a) when forming a condensed ring, (b)
It can be classified into a case where a single bond is directly bonded and a case where it is bonded via a (c) connecting group (a spiro bond cannot be formed due to an aromatic ring). The connection relationship may be any of (a) to (c).

Examples of the condensed ring of (a) (condensed ring of two or more aromatic rings) include an indene ring, a naphthalene ring, an azulene ring, a fluorene ring, a phenanthrene ring, an anthracene ring, an acenaphthylene ring, a naphthacene ring, Pyrene ring, indole ring, isoindole ring, benzofuran ring, benzothiophene ring, indolizine ring, benzoxazole ring, benzothiazole ring, benzimidazole ring, benzotriazole ring, purine ring, indazole ring, chromene ring, quinoline ring, isoquinoline Ring, quinolidine ring, quinazoline ring, cinnoline ring, quinoxaline ring, phthalazine ring, pteridine ring, carbazole ring, acridine ring,
It includes a phenanthridine ring, a xanthene ring, a phenazine ring, a phenothiazine ring, a phenoxatiin ring, a phenoxazine ring and a thianthrene ring. Preferred are a naphthalene ring, an azulene ring, an indole ring, a benzoxazole ring, a benzothiazole ring, a benzimidazole ring, a benzotriazole ring and a quinoline ring. The single bond in (b) is preferably a bond between carbon atoms of two aromatic rings. By joining two aromatic rings with two or more single bonds,
An aliphatic ring or a non-aromatic heterocyclic ring may be formed between two aromatic rings.

The connecting group (c) is also preferably bonded to carbon atoms of two aromatic rings. The linking group is an alkylene group, alkenylene group, alkynylene group, -CO-, -O
-, -NH-, -S- or a combination thereof is preferred. Examples of the linking group consisting of a combination are shown below. Note that the left and right relationships in the following examples of the linking group may be reversed. c1: -CO-O-c2: -CO-NH-c3: -alkylene-O-c4: -NH-CO-NH-c5: -NH-CO-O-c6: -O-CO-O-c7: -O-alkylene-O-c8: -CO-alkenylene-c9: -CO-alkenylene-NH-c10: -CO-alkenylene-O-c11: -alkylene-CO-O-alkylene-O-CO
-Alkylene-c12: -O-alkylene-CO-O-alkylene-O-
CO-alkylene-O-c13: -O-CO-alkylene-CO-O-c14: -NH-CO-alkenylene- c15: -O-CO-alkenylene-

The aromatic ring and the linking group may have a substituent. Examples of the substituent include a halogen atom (F, C
l, Br, I), hydroxyl, carboxyl, cyano, amino, nitro, sulfo, carbamoyl, sulfamoyl, ureido, alkyl, alkenyl, alkynyl, aliphatic acyl, aliphatic acyloxy, alkoxy, alkoxycarbonyl , Alkoxycarbonylamino group, alkylthio group, alkylsulfonyl group, aliphatic amide group, aliphatic sulfonamide group, aliphatic substituted amino group, aliphatic substituted carbamoyl group, aliphatic substituted sulfamoyl group, aliphatic substituted ureido group and non-aromatic Group heterocyclic groups.

The alkyl group preferably has 1 to 8 carbon atoms. A chain alkyl group is preferable to a cyclic alkyl group, and a linear alkyl group is particularly preferable.
The alkyl group may further have a substituent (eg, hydroxy, carboxy, alkoxy group, alkyl-substituted amino group). Examples of alkyl groups (including substituted alkyl groups) include methyl, ethyl, n-butyl, n-hexyl,
-Hydroxyethyl, 4-carboxybutyl, 2-methoxyethyl and 2-diethylaminoethyl. The alkenyl group preferably has 2 to 8 carbon atoms. A chain alkenyl group is preferable to a cyclic alkenyl group, and a linear alkenyl group is particularly preferable.
The alkenyl group may further have a substituent. Examples of the alkenyl group include vinyl, allyl and 1-hexenyl. The alkynyl group preferably has 2 to 8 carbon atoms. A chain alkynyl group is preferable to a cyclic alkynyl group, and a linear alkynyl group is particularly preferable. The alkynyl group may further have a substituent. Examples of the alkynyl group include ethynyl, 1-butynyl and 1-hexynyl.

The number of carbon atoms of the aliphatic acyl group is 1 to 1
It is preferably 0. Examples of the aliphatic acyl group include acetyl, propanoyl and butanoyl. The aliphatic acyloxy group preferably has 1 to 10 carbon atoms. Examples of the aliphatic acyloxy group include acetoxy. The alkoxy group preferably has 1 to 8 carbon atoms. The alkoxy group may further have a substituent (eg, an alkoxy group). Examples of alkoxy groups (including substituted alkoxy groups) include methoxy, ethoxy, butoxy and methoxyethoxy. The alkoxycarbonyl group preferably has 2 to 10 carbon atoms. Examples of the alkoxycarbonyl group include methoxycarbonyl and ethoxycarbonyl. The alkoxycarbonylamino group preferably has 2 to 10 carbon atoms. Examples of the alkoxycarbonylamino group include methoxycarbonylamino and ethoxycarbonylamino.

The number of carbon atoms of the alkylthio group is 1 to 1
It is preferably 2. Examples of the alkylthio group include methylthio, ethylthio and octylthio.
The alkylsulfonyl group preferably has 1 to 8 carbon atoms. Examples of the alkylsulfonyl group include methanesulfonyl and ethanesulfonyl. The aliphatic amide group preferably has 1 to 10 carbon atoms. Examples of the aliphatic amide group include acetamide. The aliphatic sulfonamide group preferably has 1 to 8 carbon atoms. Examples of the aliphatic sulfonamide group include methanesulfonamide, butanesulfonamide and n-octanesulfonamide. The aliphatic substituted amino group preferably has 1 to 10 carbon atoms. Examples of the aliphatic substituted amino group include dimethylamino, diethylamino and 2-carboxyethylamino. The aliphatic substituted carbamoyl group preferably has 2 to 10 carbon atoms. Examples of the aliphatic substituted carbamoyl group include methylcarbamoyl and diethylcarbamoyl. The aliphatic substituted sulfamoyl group preferably has 1 to 8 carbon atoms. Examples of the aliphatic substituted sulfamoyl group include methylsulfamoyl and diethylsulfamoyl. The aliphatic substituted ureido group preferably has 2 to 10 carbon atoms. Examples of the aliphatic substituted ureido group include methyl ureide. Examples of the non-aromatic heterocyclic group include piperidino and morpholino. The molecular weight of the retardation increasing agent is preferably from 300 to 800.

[Production of Cellulose Acetate Film]
The cellulose acetate film is preferably produced by a solution casting method. It is more preferable to produce a cellulose acetate film by a solvent casting method using an organic solvent as a solvent for casting. In the solvent casting method, a film is manufactured using a solution (dope) in which cellulose acetate is dissolved in an organic solvent. The organic solvent is a solvent selected from ethers having 3 to 12 carbon atoms, ketones having 3 to 12 carbon atoms, esters having 3 to 12 carbon atoms, and halogenated hydrocarbons having 1 to 6 carbon atoms. It is preferable to include ether,
Ketones and esters may have a cyclic structure. A compound having two or more functional groups of ether, ketone and ester (that is, -O-, -CO- and -COO-) can also be used as the organic solvent. The organic solvent may have another functional group such as an alcoholic hydroxyl group. In the case of an organic solvent having two or more types of functional groups, the number of carbon atoms may be within the specified range of the compound having any one of the functional groups.

Examples of the ethers having 3 to 12 carbon atoms include diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolan, tetrahydrofuran, anisole and phenetole. Examples of the ketones having 3 to 12 carbon atoms include acetone, methyl ethyl ketone, diethyl ketone, diisobutyl ketone, cyclohexanone and methylcyclohexanone. Examples of the esters having 3 to 12 carbon atoms include ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate and pentyl acetate. Examples of the organic solvent having two or more types of functional groups include
Includes 2-ethoxyethyl acetate, 2-methoxyethanol and 2-butoxyethanol. The number of carbon atoms of the halogenated hydrocarbon is preferably 1 or 2, and most preferably 1. The halogen of the halogenated hydrocarbon is preferably chlorine. The proportion of halogen atoms substituted by halogen atoms in halogenated hydrocarbons is preferably 25 to 75 mol%, and preferably 3 to 75 mol%.
The content is more preferably 0 to 70 mol%, still more preferably 35 to 65 mol%, and 40 to 60 mol%.
Most preferably, it is mol%. Methylene chloride is a typical halogenated hydrocarbon. Two or more organic solvents may be used as a mixture.

A cellulose acetate solution can be prepared by a general method. The general method means that the treatment is performed at a temperature of 0 ° C. or higher (normal temperature or high temperature). The solution can be prepared using a dope preparation method and apparatus in a usual solvent casting method. In the case of a general method, it is preferable to use a halogenated hydrocarbon (particularly, methylene chloride) as the organic solvent. The amount of cellulose acetate is adjusted so that the obtained solution contains 10 to 40% by mass. More preferably, the amount of cellulose acetate is 10 to 30% by mass. In the organic solvent (main solvent), any additives described below may be added. The solution can be prepared by stirring cellulose acetate and an organic solvent at normal temperature (0 to 40 ° C.). The highly concentrated solution may be stirred under pressure and heating conditions. Specifically, the cellulose acetate and the organic solvent are put in a pressurized container and hermetically sealed, and the mixture is stirred while being heated under pressure to a temperature not lower than the boiling point of the solvent at normal temperature and in a range where the solvent does not boil. The heating temperature is usually 40 ° C. or higher, preferably 60 to 200 ° C., and more preferably 80 to 110 ° C.

Each component may be roughly mixed in advance and then placed in a container. Moreover, you may put in a container sequentially. The container must be configured to be able to stir. The container can be pressurized by injecting an inert gas such as nitrogen gas. Further, an increase in the vapor pressure of the solvent due to heating may be used.
Alternatively, each component may be added under pressure after the container is sealed. When heating, it is preferable to heat from outside the container. For example, a jacket-type heating device can be used. Alternatively, a plate heater may be provided outside the container, and the entire container may be heated by circulating the liquid through piping. It is preferable to provide a stirring blade inside the container and stir using the stirring blade. The stirring blade preferably has a length reaching the vicinity of the container wall. At the end of the stirring blade, a scraping blade is preferably provided to renew the liquid film on the container wall. Instruments such as a pressure gauge and a thermometer may be installed in the container. Dissolve each component in the solvent in the container.
The prepared dope is taken out of the vessel after cooling, or is taken out and then cooled using a heat exchanger or the like.

The solution can be prepared by a cooling dissolution method. In the cooling dissolution method, cellulose acetate can be dissolved even in an organic solvent that is difficult to dissolve by a normal dissolution method. In addition, even if it is a solvent which can dissolve cellulose acetate by an ordinary dissolution method, the cooling dissolution method has an effect that a uniform solution can be obtained quickly. In the cooling dissolution method, first, cellulose acetate is gradually added to an organic solvent at room temperature while stirring. It is preferable that the amount of cellulose acetate is adjusted to be 10 to 40% by mass in the mixture. More preferably, the amount of cellulose acetate is 10 to 30% by mass. Further, an optional additive described below may be added to the mixture.

Next, the mixture is cooled to -100 to -10 ° C (preferably -80 to -10 ° C, more preferably -50 to -10 ° C).
To -20 ° C, most preferably -50 to -30 ° C). The cooling can be performed, for example, in a dry ice / methanol bath (−75 ° C.) or a cooled diethylene glycol solution (−30 to −20 ° C.). Upon such cooling, the mixture of cellulose acetate and the organic solvent solidifies. The cooling rate is preferably 4 ° C./min or more, more preferably 8 ° C./min or more.
Most preferably, the temperature is at least ° C / min. The cooling rate is preferably as fast as possible, but 10,000 ° C./sec is the theoretical upper limit, 1000 ° C./sec is the technical upper limit, and
00 ° C / sec is a practical upper limit. The cooling rate is
This is a value obtained by dividing the difference between the temperature at which cooling is started and the final cooling temperature by the time from when cooling is started to when the temperature reaches the final cooling temperature.

Further, the temperature is raised to 0 to 200 ° C. (preferably 0 to 150 ° C., more preferably 0 to 120 ° C.,
When heated to the temperature (most preferably 0 to 50 ° C.), the cellulose acetate dissolves in the organic solvent. The temperature may be raised only at room temperature or may be heated in a warm bath. The heating rate is preferably 4 ° C./min or more, and 8 ° C./min.
Minutes or more, and most preferably 12 ° C./minute or more. The heating rate is preferably as high as possible, but the theoretical upper limit is 10,000 ° C./sec.
0 ° C./sec is a technical upper limit, and 100 ° C./sec is a practical upper limit. Note that the heating rate is a value obtained by dividing the difference between the temperature at which heating is started and the final heating temperature by the time from when the heating is started until the final heating temperature is reached. . As described above, a uniform solution is obtained. If the dissolution is insufficient, the operation of cooling and heating may be repeated. Whether or not the dissolution is sufficient can be determined only by visually observing the appearance of the solution.

In the cooling dissolution method, it is preferable to use a closed container in order to avoid water contamination due to dew condensation during cooling. Also, in the cooling and heating operation, pressurization during cooling,
By reducing the pressure during the heating, the dissolution time can be shortened. In order to perform pressurization and decompression, it is desirable to use a pressure-resistant container. According to differential scanning calorimetry (DSC), a 20% by mass solution of cellulose acetate (degree of acetylation: 60.9%, viscosity average polymerization degree: 299) dissolved in methyl acetate by a cooling dissolution method was 3%.
A pseudo phase transition point between the sol state and the gel state exists near 3 ° C., and below this temperature, the gel state becomes uniform. Therefore,
This solution must be maintained at a temperature equal to or higher than the pseudo phase transition temperature, and preferably at a temperature of about 10 ° C. plus the gel phase transition temperature. However, this pseudo phase transition temperature differs depending on the acetylation degree of cellulose acetate, the viscosity average polymerization degree, the solution concentration and the organic solvent used.

From the prepared cellulose acetate solution (dope), a cellulose acetate film is produced by a solvent casting method. The dope is cast on a drum or band and the solvent is evaporated to form a film. The concentration of the dope before casting is preferably adjusted so that the solid content is 18 to 35%. It is preferable that the surface of the drum or the band is finished in a mirror state. The casting and drying methods in the solvent casting method are described in U.S. Pat. Nos. 2,336,310 and 23,676.
No. 03, No. 2492078, No. 2492977, No. 2492978, No. 2607704, No. 27390
Nos. 69 and 2739070, British Patent 640731
Nos. 736892 and JP-B-45-455.
No. 4, No. 49-5614, JP-A-60-176834.
And JP-A-60-203430 and JP-A-62-115035. The dope is preferably cast on a drum or band having a surface temperature of 10 ° C. or less.
After casting, it is preferable to dry by blowing on air for 2 seconds or more. The obtained film can be peeled off from the drum or band, and further dried with high-temperature air having a temperature gradually changed from 100 to 160 ° C. to evaporate the residual solvent. The above method is described in JP-B-5-17844. According to this method, the time from casting to stripping can be reduced. In order to carry out this method, it is necessary that the dope gels at the surface temperature of the drum or band during casting.

The film can also be formed by a co-casting method in which two or more layers are cast using the prepared cellulose acetate solution (dope). In this case, it is preferable to produce a cellulose acetate film by a solvent casting method. The dope is cast on a drum or band and the solvent is evaporated to form a film. The concentration of the dope before casting is preferably adjusted so that the solid content is 10 to 40%. It is preferable that the surface of the drum or the band is finished in a mirror state.

When two or more cellulose acetate solutions are cast, a plurality of cellulose acetate solutions can be cast, and a plurality of casting ports provided at intervals in the traveling direction of the support. Alternatively, a film containing cellulose acetate may be cast and laminated to form a film. For example, Japanese Patent Application Laid-Open No. 61-158414
, JP-A-1-122419, and JP-A-11-
The method described in each specification of 198285 can be used. The film can also be formed by casting a cellulose acetate solution from two casting ports. For example, Japanese Patent Publication No. 60-27562,
-94724, JP-A-61-947245, JP-A-61-104814, JP-A-61-158413,
Further, the method described in each specification of JP-A-6-134933 can be used. Also, Japanese Patent Application Laid-Open No. 56-162
No. 617, a method of casting a cellulose acetate film by wrapping a flow of a high-viscosity cellulose acetate solution with a low-viscosity cellulose acetate solution and simultaneously extruding the high- and low-viscosity cellulose acetate solution can also be used.

Further, by using two casting ports, the film formed on the support by the first casting port is peeled off, and the second casting is performed on the side in contact with the support surface. Films can also be made. For example, Japanese Patent Publication No. 44-2
No. 0235 can be mentioned.
The same cellulose acetate solution may be used for casting, or different cellulose acetate solutions may be used. In order to give a function to a plurality of cellulose acetate layers, a cellulose acetate solution corresponding to the function may be extruded from each casting port. Furthermore, the cellulose acetate solution of the present invention can be cast simultaneously with other functional layers (for example, an adhesive layer, a dye layer, an antistatic layer, an antihalation layer, an ultraviolet absorbing layer, a polarizing layer, etc.).

In the conventional single-layer liquid, it is necessary to extrude a high-concentration and high-viscosity cellulose acetate solution in order to obtain a required film thickness. In this case, the stability of the cellulose acetate solution is poor and the This often causes problems such as a bumpy failure or poor flatness. By casting a plurality of cellulose acetate solutions from the casting port, it is possible to simultaneously extrude a high-viscosity solution onto the support, thereby improving the flatness and producing an excellent planar film as well as a thick film. By using a suitable cellulose acetate solution, a reduction in the drying load can be achieved, and the production speed of the film can be increased.

A plasticizer can be added to the cellulose acetate film in order to improve mechanical properties or to increase the drying speed. As a plasticizer,
Phosphate or carboxylate esters are used. Examples of phosphate esters include triphenyl phosphate (TPP) and tricresyl phosphate (TCC).
P) is included. Representative carboxylic esters include phthalic esters and citric esters. Examples of phthalate esters include dimethyl phthalate (DM
P), diethyl phthalate (DEP), dibutyl phthalate (DBP), dioctyl phthalate (DOP), diphenyl phthalate (DPP) and diethylhexyl phthalate (DEHP). Examples of citrate esters include O-acetyl triethyl citrate (OACT
E) and tributyl O-acetylcitrate (OACT
B) is included. Examples of other carboxylic esters include butyl oleate, methylacetyl ricinoleate,
It includes dibutyl sebacate and various trimellitate esters. Phthalate ester plasticizers (DMP, DE
P, DBP, DOP, DPP, DEHP) are preferably used. DEP and DPP are particularly preferred. The amount of the plasticizer added is 0.1 to 25 times the amount of the cellulose ester.
%, More preferably 1 to 20% by mass, most preferably 3 to 15% by mass.

The cellulose acetate film may contain a deterioration inhibitor (eg, an antioxidant, a peroxide decomposer, a radical inhibitor, a metal deactivator, an acid scavenger, an amine). Regarding the deterioration inhibitor, see JP-A-3-19920.
No. 1, 5-1907073, 5-194789
And JP-A-5-271471 and JP-A-6-107854. The amount of the deterioration inhibitor added is preferably 0.01 to 1% by mass, more preferably 0.01 to 0.2% by mass of the solution (dope) to be prepared. When the amount is less than 0.01% by mass, the effect of the deterioration inhibitor is hardly recognized. 1% by mass
Exceeding the limit may cause bleed-out (bleeding-out) of the deterioration inhibitor to the film surface. Particularly preferred examples of the deterioration inhibitor include butylated hydroxytoluene (BHT) and tribenzylamine (TBA).

[Polyester Urethane] Next, the polyester urethane used in the present invention will be described. It is preferable to add polyester urethane to the cellulose acetate film in order to improve mechanical properties. Further, the polyester urethane is preferably a reaction product of a polyester represented by the following general formula (1) and a diisocyanate, and is further preferably soluble in dichloromethane. (1) H - (- O- (CH 2) q -OOC- (CH 2) m -CO) n -O- (CH 2) in _q -OH formulas, q is an integer of 2 to 4; m represents an integer of 2 to 4; n represents an integer of 1 to 100. More specifically, in the constituent polyester, the glycol component is ethylene glycol, 1,3-propanediol, or 1,4-butanediol, and the dibasic acid component is succinic acid, glutaric acid, or adipine. It is a polyester having both less than two hydroxyl groups consisting of an acid, and its degree of polymerization n is in the range of 1-100. Degree of polymerization n
May be in the range of 1 to 100, but the optimum degree of polymerization slightly varies depending on the type of glycol and dibasic acid used, and it is particularly preferable that the molecular weight of the polyester be in the range of 1,000 to 4,500. The dichloromethane-soluble polyester urethane resin is obtained by reacting the polyester of the formula (1) with a diisocyanate,
The general formula is a compound having a repeating unit represented by the formula (2).

(2) CONH-R-NHCO- (O- (CH ₂ ) _q -OOC- (C
H ₂ ) _m —CO) _n —O— (CH ₂ ) _q —O) — wherein q represents an integer of 2 to 4; m represents an integer of 2 to 4; Represents an integer of 100; R is
Represents a divalent atomic group residue. Examples of the divalent group residue include, for example, the following formulas.

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Examples of the diisocyanate component used in the polyurethane compound include polymethylene diisocyanate represented by ethylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate and the like. General formula: O
CN (CH ₂ ) _p NCO (p represents an integer of 2 to 8)), p-phenylene diisocyanate, tolylene diisocyanate, p · p′-diphenylmethane diisocyanate, 1,5-naphthylene diisocyanate Examples include aromatic diisocyanates such as nato and m-xylylene diisocyanate, but are not limited thereto. Among these, tolylene diisocyanate, m-xylylene diisocyanate, and tetramethylene diisocyanate are easily available, relatively stable and easy to handle, and when polyurethane is formed, they are used in combination with cellulose acetate. This is preferred because of its excellent compatibility.

The molecular weight of the polyester urethane resin is 2
It is preferably in the range of 000 to 50,000, and is appropriately selected depending on the type, molecular weight, and the like of the component polyesters or the diisocyanate component that is a connecting group thereof. The molecular weight of the polyester urethane resin is 5,000 to 150 in terms of improvement in mechanical properties of the cellulose acetate film and compatibility with the cellulose acetate.
More preferably, it is in the range of 00. The synthesis of a dichloromethane-soluble polyester urethane can be easily obtained by mixing a polyester diol represented by the formula (1) with a diisocyanate and heating with stirring. The polyesters represented by the formula (1) are prepared by hot-melt condensation by a polyesterification reaction or transesterification reaction of a corresponding dibasic acid or an alkyl ester thereof with a glycol, or an acid chloride of these acids. The compound can be easily synthesized by appropriately adjusting the terminal group to a hydroxyl group by any of the interfacial condensation methods with glycols. The dichloromethane-soluble polyester urethane resin used in the present invention has extremely good compatibility with cellulose acetate having an acetylation degree of 58% or more. Although a slight difference is recognized depending on the structure of the resin, when the molecular weight of the polyester urethane is 10,000 or less, the polyester urethane is compatible with 200 parts by mass of the polyester urethane with respect to 100 parts by mass of the cellulose acetate.

Accordingly, when the polyester urethane resin is mixed with cellulose acetate to improve the mechanical properties of the film, the content of the polyester urethane resin is appropriately determined depending on the type and molecular weight of the urethane resin and the desired mechanical properties. Should be determined. In the case where mechanical properties are to be improved while maintaining the properties of cellulose acetate, it is preferable that the polyester urethane resin is contained in the range of 0.1 to 30 parts by mass with respect to 100 parts by mass of cellulose acetate. This polyester urethane resin is stable and does not thermally decompose at least up to 180 ° C. The dichloromethane-soluble polyester urethane has extremely good compatibility with cellulose acetate having a degree of acetylation of 58% or more. Therefore, when both are mixed to form a film, a film having extremely high transparency can be obtained. Moreover, these polyester urethanes have a high average molecular weight, so that unlike conventional low-molecular plasticizers, they have almost no volatility even at high temperatures. Therefore, a film obtained by forming a film from these mixtures has less inconvenience due to volatilization and migration of the plasticizer observed in the conventional plasticizer in the subsequent processing.

By adding the polyester urethane to the cellulose acetate film, the bending strength and the tear strength at high and low temperatures are increased, and the inconvenience of tearing the film is eliminated. Conventionally,
A low-molecular plasticizer has been used to improve the bending strength and tear strength of the film. This method has a certain effect in a normal temperature and high humidity state, but loses flexibility of a film in a low temperature and high humidity state, so that a satisfactory result was not always obtained. Further, when an attempt is made to improve the mechanical properties by using a low-molecular plasticizer, the mechanical properties such as the tensile strength generally decrease significantly with the addition amount of the plasticizer. When a dichloromethane-soluble polyester urethane resin is added to cellulose acetate, a slight decrease in tensile strength is observed with the amount of the resin added, but the decrease in strength is clearly smaller than when a low-molecular plasticizer is added, A tough film having a large bending strength and almost the same as in the case of no addition can be obtained. Further, by mixing the polyester urethane, the transfer of the plasticizer at low temperature and high humidity can be prevented. Therefore, a transparent and glossy film which does not adhere to each other, is very flexible, and does not wrinkle can be obtained.

[High Thermal Conductive Particles] The thermal conductivity of the cellulose acetate film is preferably 1 W / (m · K) or more. The value of the thermal conductivity is preferably as high as possible, but when adjusted by the following method, 10 W / (m ·
K) It is generally the following. In order to control the thermal conductivity of the cellulose acetate film, it is preferable to add highly thermally conductive particles to the (dope) used for producing the cellulose acetate film. Further, in order to control the thermal conductivity, a thermal conductive layer containing high thermal conductive particles may be separately provided on one surface of the cellulose acetate film. The heat conductive layer may be provided by co-casting a polymer containing highly heat conductive particles with cellulose acetate, or may be provided by applying the polymer to a cellulose acetate film. Examples of the material of the high thermal conductive particles include:
Examples thereof include aluminum nitride, silicon nitride, boron nitride, magnesium nitride, silicon carbide, aluminum oxide, silicon oxide, zinc oxide, magnesium oxide, carbon, diamond, and metal. It is preferable to use transparent particles so as not to impair the transparency of the film.

It is preferable that the compounding amount of the high heat conductive particles in the cellulose acetate film is in the range of 5 to 100 parts by mass based on 100 parts by mass of the cellulose acetate. When the amount is less than 5 parts by mass, the improvement in heat conduction is poor, and when the amount exceeds 50 parts by mass, productivity is difficult and the cellulose acetate film becomes brittle. The average particle size of the high thermal conductive particles is preferably in the range of 0.05 to 80 μm, and 0.1 to 1 μm.
More preferably, it is in the range of 0 μm. Spherical particles may be used, or acicular particles may be used.

In the present invention, the thermal conductivity of the cellulose acetate film was measured as follows. The cellulose acetate film is sandwiched between the TO-3 type heater case and the copper plate, and compressed to 10% of the film thickness. Then, a power of 5 W is applied to the copper heater case and the temperature is maintained for 4 minutes, and the temperature difference between the copper heater case and the copper plate is measured. The thermal conductivity was calculated by the following equation. Thermal conductivity {W / (m · K)} = {power (W) × thickness (m)} / {temperature difference (K) × measured area (m ² )}

[Stretching of Cellulose Acetate Film] In order to reduce virtual distortion, it is preferable to stretch the cellulose acetate film. By stretching the film, virtual distortion in the stretching direction can be reduced. Therefore, in order to reduce distortion in all directions in the plane, it is more preferable to stretch the film biaxially. Preferably, the cellulose acetate film is stretched at a stretching ratio in the range of 3 to 100%. For biaxial stretching,
There are a simultaneous biaxial stretching method and a sequential biaxial stretching method. The sequential biaxial stretching method is preferable from the viewpoint of continuous production. In the biaxial stretching method, after casting the dope, the film is peeled off from the band or drum, stretched in the width direction, and then stretched in the longitudinal direction. This stretching may be performed in the longitudinal direction and then in the width direction. The method of stretching in the width direction is described in, for example, JP-A-62-115035 and JP-A-4-1521.
No. 25, No. 4-284221, No. 4-298310
And No. 11-48271. The stretching of the film is performed at normal temperature or under heating conditions. The heating temperature is preferably equal to or lower than the glass transition temperature of the film. The film can be stretched during the drying process, and is particularly effective when the solvent remains.
In the case of stretching in the longitudinal direction, the film is stretched, for example, by adjusting the speed of the film transport roller so that the film winding speed is faster than the film peeling speed. In the case of stretching in the width direction, the film can be stretched by conveying the film while holding it with a tenter and gradually increasing the width of the tenter. After drying the film, the film can be stretched using a stretching machine (preferably, uniaxial stretching using a long stretching machine). The stretching ratio of the film (the ratio of the increase by stretching to the original length) is 5
Preferably in the range of 10 to 40%.
%, More preferably 15 to 35%.
Is most preferably within the range.

The steps from casting to post-drying may be performed in an air atmosphere or an inert gas atmosphere such as nitrogen gas. The winding machine used in the production of the cellulose acetate film used in the present invention may be a commonly used winding machine, such as a constant tension method, a constant torque method, a taper tension method, and a program tension control method with a constant internal stress. Can be wound up by the method.

[Hygroscopic Expansion Coefficient] The hygroscopic expansion coefficient indicates the amount of change in the length of the sample when the relative humidity is changed at a constant temperature. In order to prevent the frame-shaped transmittance from increasing, the coefficient of hygroscopic expansion of the cellulose acetate film is 30 × 1.
0 ^-5 /% RH or less, preferably 15 × 10 ^-5
/% RH or less, more preferably 10 × 10 ^−5.
/% RH or less. The smaller the coefficient of hygroscopic expansion is, the better.
^-5 /% RH or more. The method for measuring the coefficient of hygroscopic expansion will be described below. 5 mm width from the prepared polymer film (retardation plate). A sample having a length of 20 mm was cut out, and one end was fixed and hung under an atmosphere of 25 ° C. and 20% RH (R ₀ ). A 0.5 g weight was hung on the other end, and left for 10 minutes to measure the length (L ₀ ). Next, the temperature is kept at 25 ° C. and the humidity is set to 80% RH (R ₁ ).
The length (L ₁ ) was measured. The coefficient of hygroscopic expansion was calculated by the following equation. The measurement was performed for 10 samples for the same sample, and the average value was adopted. Hygroscopic expansion coefficient [/% RH] = {(L ₁ −L ₀ ) / L ₀ }
/ (R ₁ -R ₀ )

It has been found that the dimensional change due to moisture absorption can be achieved by reducing the free volume in the polymer film.
What largely affects the free volume is the amount of the residual solvent at the time of film formation. A common technique for reducing residual solvent is to dry at high temperature and for a long time, but if it is too long, the productivity naturally drops. Therefore, the amount of the residual solvent based on the cellulose acetate film is preferably in the range of 0.01 to 1% by mass, more preferably in the range of 0.02 to 0.07% by mass, and more preferably 0.03 to 0. Most preferably, it is in the range of 05% by mass. By controlling the amount of the residual solvent, a polarizing plate having optical compensation ability can be manufactured at low cost and with high productivity.

As another method of reducing the dimensional change due to moisture absorption, it is preferable to add a compound having a hydrophobic group. The material having a hydrophobic group is not particularly limited as long as the material has a hydrophobic group such as an alkyl group or a phenyl group in the molecule. The corresponding material is particularly preferably used. Examples of these preferred materials include triphenyl phosphate (TPP),
Tribenzylamine (TBA) and the like can be mentioned. The addition amount of these compounds having a hydrophobic group is preferably in the range of 0.01 to 10% by mass, more preferably in the range of 0.1 to 5% by mass, based on the solution (dope) to be adjusted. It is most preferably in the range of 1 to 3% by mass.

[Surface Treatment of Cellulose Acetate Film] The cellulose acetate film is preferably subjected to a surface treatment. Specific methods include corona discharge treatment, glow discharge treatment, flame treatment, acid treatment, alkali treatment, and ultraviolet irradiation treatment. In addition, Japanese Patent Application Laid-Open
As described in JP-A-333433, it is also preferable to provide an undercoat layer. The surface energy of the film after the surface treatment is preferably 55 mN / m or more, more preferably 60 mN / m or more and 75 mN / m or less. From the viewpoint of maintaining the flatness of the film,
In these treatments, the temperature of the cellulose acetate film is lowered to Tg (glass transition temperature) or lower, specifically, 150 ° C.
It is preferable to set the following. When used as a transparent protective film for a polarizing plate, it is particularly preferable to perform an acid treatment or an alkali treatment, that is, a saponification treatment on cellulose acetate, from the viewpoint of adhesion to the polarizing film.

Hereinafter, a specific description will be given using an alkali saponification treatment as an example. The alkali saponification treatment is preferably performed in a cycle in which the film surface is immersed in an alkaline solution, neutralized with an acidic solution, washed with water and dried. Examples of the alkaline solution include a potassium hydroxide solution and a sodium hydroxide solution.
More preferably, it is in the range of 0N. The alkali solution temperature is preferably in the range of room temperature to 90 ° C,
More preferably, it is in the range of 40 to 70 ° C. The surface energy of the solid can be determined by the contact angle method, the heat of wetting method, and the adsorption method as described in “Basic and Applied Wetting” (Realize 1989.12.10). In the case of the cellulose acetate film of the present invention,
It is preferable to use the contact angle method. Specifically, two types of solutions whose surface energies are known are dropped on a cellulose acetate film, and at the intersection between the surface of the droplet and the film surface, the angle between the tangent drawn to the droplet and the film surface is determined. The angle containing the drop is defined as the contact angle, and the surface energy of the film can be calculated by calculation.

[Optical Anisotropic Layer] In the present invention, the optically anisotropic layer formed of a liquid crystalline compound is formed on an alignment film provided on a cellulose acetate film.
The liquid crystal compound used for the optically anisotropic layer includes a rod-shaped liquid crystal compound and a discotic liquid crystal compound. The rod-shaped liquid crystal compound and the discotic liquid crystal compound may be high-molecular liquid crystals or low-molecular liquid crystals, and further include those in which the low-molecular liquid crystals are crosslinked and no longer exhibit liquid crystal properties. The optically anisotropic layer is
It can be formed by applying a coating solution containing a liquid crystal compound and, if necessary, a polymerizable initiator and optional components on the alignment film.

As a solvent used for preparing the coating solution, an organic solvent is preferably used. Examples of organic solvents include amides (eg, N, N-dimethylformamide), sulfoxides (eg, dimethylsulfoxide), 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. The application of the coating liquid is performed by a known method (eg, a wire bar coating method, an extrusion coating method,
Direct gravure coating method, reverse gravure coating method, die coating method). The thickness of the optically anisotropic layer is preferably 0.1 to 20 μm, more preferably 0.5 to 15 μm, and most preferably 1 to 10 μm. As the liquid crystalline compound used in the present invention, a discotic liquid crystalline compound is preferably used.

[Rod-shaped liquid crystalline compound] Examples of the rod-shaped liquid crystalline compound include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic esters,
Cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines, phenyldioxanes, tolanes, and alkenylcyclohexylbenzonitrile are preferably used. Note that the rod-like liquid crystal compound also includes a metal complex. Also, a liquid crystal polymer containing a rod-like liquid crystal compound in a repeating unit,
It can be used as a rod-like liquid crystalline compound. In other words, the rod-like liquid crystalline compound may be bonded to a (liquid crystal) polymer. Regarding the rod-like liquid crystal compound, see Quarterly Chemistry Review Vol. 22, Chapters 4, 7 and 11 of Liquid Crystal Chemistry (1994) edited by The Chemical Society of Japan, and Liquid Crystal Device Handbook edited by the 142nd Committee of the Japan Society for the Promotion of Science. See Chapter 3. The birefringence of the rod-shaped liquid crystalline compound is 0.001.
It is preferably in the range of 0.7 to 0.7. The rod-shaped liquid crystalline compound preferably has a polymerizable group in order to fix the alignment state. Examples of the polymerizable group (Q) are shown below.

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The polymerizable group (Q) is an unsaturated polymerizable group (Q1
To Q7), an epoxy group (Q8) or an aziridinyl group (Q9), more preferably an unsaturated polymerizable group, and more preferably an ethylenically unsaturated polymerizable group (Q
1 to Q6) are most preferred. The rod-shaped liquid crystalline compound preferably has a molecular structure that is substantially symmetric with respect to the minor axis direction. For that purpose, it is preferable to have a polymerizable group at both ends of the rod-shaped molecular structure. Hereinafter, examples of the rod-like liquid crystalline compound will be described.

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The optically anisotropic layer is formed of a rod-shaped liquid crystalline compound, a polymerizable initiator described below, and optional additives (eg, plasticizer, monomer, surfactant, cellulose ester, 1,3,5
-A liquid crystal composition (coating solution) containing a triazine compound and a chiral agent) is applied on the alignment film.

[Discotic Liquid Crystalline Compound] Examples of the discotic (discotic) liquid crystalline compound include C.I. Destr
ade et al., Mol. Cryst. 71 volumes, 1
Benzene derivatives described on page 11 (1981); Destrade et al., Mol. Cr
yst. 122, 141 pages (1985), Phys
ics lett, A, vol. 78, p. 82 (1990); Kohne et al., Angew. Chem. 96 volumes, 70 pages (1
984) and the cyclohexane derivative described in J.
M. J. Lehn et al. Chem. Commu
n. , P. 1794 (1985); Research report by Zhang et al. Am. Chem. Soc. 116 volumes, 2
Examples thereof include azacrown-based and phenylacetylene-based macrocycles described on page 655 (1994). Further, as the discotic liquid crystalline compound,
In general, they have a structure in which these are used as a core of a molecular center, and a linear alkyl group, an alkoxy group, a substituted benzoyloxy group, or the like is linearly substituted in the form of a straight line to exhibit liquid crystallinity. However, the molecule is not limited to these as long as the molecule itself has negative uniaxiality and can impart a certain orientation. Further, in the present invention, the optically anisotropic layer formed from the discotic liquid crystalline compound does not need to be a compound finally formed, and for example, a low molecular discotic liquid crystalline compound may be heat, light, or the like. And the like, and as a result, those which are polymerized or cross-linked by a reaction with heat, light, or the like to have a high molecular weight and lose liquid crystallinity are also included. Preferred examples of the discotic liquid crystalline compound are described in JP-A-8-50206. The polymerization of a discotic liquid crystalline compound is described in JP-A-8-27284.

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

(III) D (-LP) _{n wherein} D is a discotic core; L is a divalent linking group, P is a polymerizable group, and n is from 4 to 12 Is an integer. Examples of the disc-shaped core (D) are shown below. In each of the following examples, LP (or PL) means a combination of a divalent linking group (L) and a polymerizable group (P).

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In the formula (III), the divalent linking group (L)
Is an alkylene group, alkenylene group, arylene group,-
It is preferably a divalent linking group selected from the group consisting of CO-, -NH-, -O-, -S- and a combination thereof. The divalent linking group (L) is an alkylene group, an arylene group, -CO-, -NH-, -O- and -S-
The divalent linking group is more preferably a combination of at least two divalent groups selected from the group consisting of The divalent linking group (L) is an alkylene group, an arylene group,-
Most preferably, it is a divalent linking group obtained by combining at least two divalent groups selected from the group consisting of CO- and -O-. The alkylene group has 1 to 1 carbon atoms.
It is preferably 2. The alkenylene group preferably has 2 to 12 carbon atoms. The arylene group preferably has 6 to 10 carbon atoms.

Examples of the divalent linking group (L) are shown below. The left side is bonded to the discotic core (D), and the right side is a polymerizable group (P).
To join. AL represents an alkylene group or an alkenylene group, and AR represents an arylene group. Note that 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-OC
O-L19: -O-CO-AR-O-AL-O-AL-OA
L-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 (P) of the formula (III) is determined according to the type of the polymerization reaction. Examples of the polymerizable group (P) are shown below.

[0097]

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[0098]

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[0099]

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[0100]

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[0101]

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[0102]

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The polymerizable group (P) is an unsaturated polymerizable group (P
1, P2, P3, P7, P8, P15, P16, P1
7) or an epoxy group (P6, P18), more preferably an unsaturated polymerizable group,
Ethylenically unsaturated polymerizable groups (P1, P7, P8, P1
5, P16, P17). In the formula (III), n is an integer of 4 to 12. Specific numbers are determined according to the type of the disc-shaped core (D). The combination of a plurality of L and P may be different, but is preferably the same.

When a discotic liquid crystalline compound is used, the optically anisotropic layer is a layer having negative birefringence, and the surface of the discotic structural unit is inclined with respect to the cellulose acetate film surface, and It is preferable that the angle between the surface of the structural unit and the surface of the cellulose acetate film changes in the depth direction of the optically anisotropic layer.

The angle (inclination angle) of the surface of the disc-shaped structural unit is
Generally, it increases or decreases in the depth direction of the optically anisotropic layer and as the distance from the bottom surface of the optically anisotropic layer increases.
Preferably, the tilt angle increases with increasing distance.
Further, the change in the inclination angle may include a continuous increase, a continuous decrease, an intermittent increase, an intermittent decrease, a change including the continuous increase and the continuous decrease, and an intermittent change including the increase and the decrease. it can. The intermittent change includes a region where the inclination angle does not change in the thickness direction. The inclination angle is preferably increased or decreased as a whole, even if it includes a region where the inclination angle does not change. Further, the inclination angle is preferably increased as a whole, and is particularly preferably changed continuously.

The tilt angle of the disc-shaped unit on the support side can be generally adjusted by selecting a disc-shaped liquid crystalline compound or a material for an alignment film, or by selecting a rubbing treatment method. Further, the inclination angle of the discotic unit on the surface side (air side) can be generally adjusted by selecting a discotic liquid crystalline compound or another compound used together with the discotic liquid crystalline compound. Examples of the compound used together with the discotic liquid crystalline compound include a plasticizer, a surfactant, a polymerizable monomer and a polymer. Further, the degree of change of the inclination angle can be adjusted by the same selection as described above.

The plasticizer, surfactant and polymerizable monomer used together with the discotic liquid crystalline compound are compatible with the discotic liquid crystalline compound and can change the tilt angle of the discotic liquid crystalline compound. Alternatively, any compound can be used as long as it does not hinder the alignment. Among these, a polymerizable monomer (eg, a compound having a vinyl group, a vinyloxy group, an acryloyl group, and a methacryloyl group) is preferable. The addition amount of the above compound is generally in the range of 1 to 50% by mass relative to the discotic liquid crystalline compound,
It is preferably in the range of 30% by mass.

As the polymer to be used together with the discotic liquid crystalline compound, any polymer may be used as long as it has compatibility with the discotic liquid crystalline compound and can change the tilt angle of the discotic liquid crystalline compound. Can be. Examples of the polymer include a cellulose ester. Preferred examples of the cellulose ester include cellulose acetate, cellulose acetate propionate, hydroxypropylcellulose and cellulose acetate butyrate. In order not to hinder the orientation of the discotic liquid crystalline compound, the amount of the polymer added is generally 0.1 to 10 with respect to the discotic liquid crystalline compound.
%, More preferably 0.1 to 8% by mass, even more preferably 0.1 to 5% by mass.

The optically anisotropic layer is generally formed by applying a solution in which a discotic liquid crystalline compound and other compounds are dissolved in a solvent onto an alignment film, drying the solution, and then heating the solution to a discotic nematic phase forming temperature. It is obtained by cooling while maintaining the state (discotic nematic phase). Alternatively, the optically anisotropic layer is formed by applying a solution in which a discotic liquid crystalline compound and another compound (for example, a polymerizable monomer and a photopolymerization initiator) are dissolved in a solvent, on the alignment film,
Drying, then heating to the discotic nematic phase formation temperature and then polymerizing (by UV light irradiation, etc.)
It is obtained by further cooling. The discotic nematic liquid crystal phase-solid phase transition temperature of the discotic liquid crystalline compound used in the present invention is preferably from 70 to 300C, particularly preferably from 70 to 170C.

[Fixation of alignment state of liquid crystal compound] The aligned liquid crystal compound can be fixed while maintaining the alignment state. The immobilization is preferably performed 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. Photopolymerization reactions are preferred. Examples of the photopolymerization initiator include α-carbonyl compounds (U.S. Pat.
670), acyloin ethers (described in US Pat. No. 2,448,828), α-hydrocarbon-substituted aromatic acyloin compounds (described in US Pat. No. 2,722,512), and polynuclear quinone compounds (described in US Pat. No. 304612)
Nos. 7 and 2951758), a combination of a triarylimidazole dimer and p-aminophenyl ketone (described in US Pat. No. 3,549,367), an acridine and phenazine compound (Japanese Unexamined Patent Publication No.
-105667, U.S. Pat. No. 4,239,850) and oxadiazole compounds (U.S. Pat.
12970). The amount of the photopolymerization initiator used is preferably in the range of 0.01 to 20% by mass of the solid content of the coating solution, and more preferably in the range of 0.5 to 5% by mass. Light irradiation for the polymerization of the liquid crystal compound is preferably performed using ultraviolet light. The irradiation energy is preferably in the range of 20 mJ / cm ^{2 to} 50 J / cm ² , and 20 to 5000 mJ / cm ²
More preferably in the range of ² to 100 to 800
More preferably, it is in the range of mJ / cm ² . Light irradiation may be performed under heating conditions to accelerate the photopolymerization reaction. A protective layer may be provided on the optically anisotropic layer.

[Alignment Film] The alignment film has a function of defining the alignment direction of the liquid crystal compound. The alignment film is formed by rubbing an organic compound (preferably a polymer), obliquely depositing an inorganic compound, forming a layer having microgrooves, or an organic compound (eg, ω-trichosanoic acid) by the Langmuir-Blodgett method (LB film). , Dioctadecylmethylammonium chloride, methyl stearylate). Further, an alignment film that has an alignment function by applying an electric field, a magnetic field, or light irradiation is also known. The alignment film is preferably formed by rubbing a polymer.

The alignment film is preferably formed by rubbing a polymer. Polyvinyl alcohol is a preferred polymer. Modified polyvinyl alcohol to which a hydrophobic group is bonded is particularly preferred. The alignment film can be formed from one type of polymer, but is more preferably formed by rubbing a layer composed of two types of crosslinked polymers. As the at least one polymer, it is preferable to use either a polymer which can be crosslinked by itself or a polymer which is crosslinked by a crosslinking agent. The alignment film is formed by reacting a polymer having a functional group or a polymer obtained by introducing a functional group into the polymer by light, heat, pH change, or the like; or a cross-linking agent which is a compound having high reaction activity. Can be formed by introducing a bonding group derived from a cross-linking agent between the polymers and cross-linking the polymers.

Such crosslinking is carried out by applying an alignment film coating solution containing the above polymer or a mixture of the polymer and the crosslinking agent onto a cellulose acetate film and then heating the film. As long as durability can be ensured with the final product (optical compensatory sheet), crosslinking treatment may be performed at any stage from coating the alignment film on the cellulose acetate film to obtaining the optical compensatory sheet. Considering the orientation of the liquid crystal compound layer (optically anisotropic layer) formed on the alignment film, it is preferable that the liquid crystal compound is oriented and then sufficiently crosslinked. The crosslinking of the alignment film is generally performed by applying a coating liquid for the alignment film on the cellulose acetate film and drying by heating. It is preferable to set the heating temperature of the coating liquid to be low, and to perform sufficient crosslinking of the alignment film at the stage of heat treatment when forming the optically anisotropic layer.

As the polymer used for the alignment film, any of a polymer which can be crosslinked by itself and a polymer which is crosslinked by a crosslinking agent can be used. Of course, some polymers are both possible. Examples of the polymer include polymethyl methacrylate, acrylic acid / methacrylic acid copolymer, styrene / maleimide copolymer, polyvinyl alcohol and modified polyvinyl alcohol, poly (N-methylol acrylamide), styrene / vinyl toluene copolymer, Polymers such as 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 preferred polymers include water-soluble polymers such as poly (N-methylolacrylamide), carboxymethylcellulose, gelatin, polyvinyl alcohol and modified polyvinyl alcohol. It is preferable to use gelatin, polyvinyl alcohol and modified polyvinyl alcohol, and it is more preferable to use polyvinyl alcohol and modified polyvinyl alcohol. It is most preferable to use two types of polyvinyl alcohols or modified polyvinyl alcohols having different degrees of polymerization.

Examples of polyvinyl alcohol include saponification
Polyvinyl alcohol having a degree in the range of 70 to 100%
Le. Generally, the degree of saponification is in the range of 80 to 100%.
And more preferably in the range of 85-95%.
Good. The degree of polymerization of polyvinyl alcohol is 10
It is preferably in the range of 0 to 3000. Modified poly
Examples of vinyl alcohol include copolymerization modification, chain transfer
Modified by block polymerization or block polymerization
Vinyl alcohol and the like can be mentioned. Copolymerization
Examples of the modifying group in the case of the property include COONa, Si
(OX) _Three, N (CH_Three)_Three・ Cl, C₉, H₁₉CO
O, SO_Three, Na, C₁₂H_{twenty five}And the like. Chain transfer
An example of a modifying group in the case of modification by kinetics is COO
Na, SH, C₁₂H_{twenty five}And the like. Also, block
Examples of modifying groups in the case of modification by polymerization are
OOH, CONH_Two, COOR, C₆H_FiveEtc.
It is. Among these, the saponification degree is in the range of 80 to 100%.
Unmodified or modified polyvinyl alcohol in the box is preferred.
Good. The saponification degree is in the range of 85 to 95%.
Modified polyvinyl alcohol and modified polyvinyl alcohol
Are more preferred.

As the modified polyvinyl alcohol, it is particularly preferable to use a modified polyvinyl alcohol with a compound represented by the following general formula. This modified polyvinyl alcohol is hereinafter referred to as a specific modified polyvinyl alcohol.

[0117]

Embedded image In the formula, R ¹ is an alkyl group, an acryloylalkyl group,
W represents a methacryloylalkyl group or an epoxyalkyl group; W represents a halogen atom, an alkyl group, or an alkoxy group; X represents an active ester, an acid anhydride,
Or represents an atomic group necessary for forming an acid halide; p represents 0 or 1; and n represents an integer of 0 to 4. The above-mentioned specific modified polyvinyl alcohol is preferably a modified product of polyvinyl alcohol with a compound represented by the following general formula.

[0118]

Embedded image In the formula, X ¹ represents an atom group necessary for forming an active ester, an acid anhydride, or an acid halide, and m represents an integer of 2 to 24.

The polyvinyl alcohol used for reacting with the compounds represented by these general formulas includes:
Examples of the above-mentioned unmodified polyvinyl alcohol and modified polyvinyl alcohol such as those modified by copolymerization, that is, those modified by chain transfer and those modified by block polymerization can be exemplified. Preferred examples of the specific modified polyvinyl alcohol are described in JP-A-9-1525.
No. 09 is described in detail. Methods for synthesizing these polymers, measuring the visible absorption spectrum, and determining the modification group introduction ratio are described in detail in JP-A-8-338913.

Examples of the crosslinking agent include aldehydes, N-
Examples thereof include a methylol compound, a dioxane derivative, a compound that acts by activating a carboxyl group, an active vinyl compound, an active halogen compound, isoxazoles, and dialdehyde starch. Examples of aldehydes include formaldehyde, glyoxal, and glutaraldehyde. Examples of N-methylol compounds include dimethylol urea and methylol dimethylhydantoin. Examples of dioxane derivatives include 2,3-dihydroxydioxane. Examples of compounds that act by activating the carboxyl group include carbenium, 2-naphthalenesulfonate, 1,1-bispyrrolidino-1-.
Chloropyridinium, and 1-morpholinocarbonyl-3- (sulfonatoaminomethyl). Examples of active vinyl compounds include 1,3,5-triacroyl-hexahydro-s-triazine, bis (vinylsulfone) methane, and N, N′-methylenebis- [β- (vinylsulfonyl) propionamide]. . Examples of the active halogen compound include 2, 4
-Dichloro-6-hydroxy-S-triazine. These can be used alone or in combination. These are preferable when used in combination with the above water-soluble polymer, particularly polyvinyl alcohol and modified polyvinyl alcohol (including the above-mentioned specific modified product). In consideration of productivity, the use of aldehydes having high reaction activity, particularly glutaraldehyde, is preferred.

There is no particular limitation on the amount of the crosslinking agent added to the polymer. Moisture resistance tends to improve when a large amount of a crosslinking agent is added. However, when the cross-linking agent is added in an amount of 50% by mass or more based on the polymer, the alignment ability as an alignment film is reduced. Therefore, the amount of the crosslinking agent added to the polymer,
It is preferably in the range of 0.1 to 20% by mass,
More preferably, it is in the range of 0.5 to 15% by mass. The alignment film contains a certain amount of a cross-linking agent that has not reacted even after the cross-linking reaction has been completed. More preferably, it is at most 5% by mass. If the unreacted crosslinking agent is contained in an amount exceeding 1.0% by mass in the alignment film, sufficient durability cannot be obtained. That is, when used for a liquid crystal display device, reticulation may occur when used for a long time or when left in an atmosphere of high temperature and high humidity for a long time.

The alignment film can be formed by applying a solution containing the above polymer or a solution containing the above polymer and a crosslinking agent onto a cellulose acetate film, heating and drying (crosslinking) and rubbing. it can. The cross-linking reaction may be carried out at any time after the application of the coating solution on the cellulose acetate film. When a water-soluble polymer such as polyvinyl alcohol is used as a material for forming an alignment film, a solvent for preparing the coating liquid is an organic solvent such as methanol having defoaming action, or a mixture of an organic solvent and water. Preferably, it is a solvent. When methanol is used as an organic solvent, the ratio is water: methanol in a mass ratio of 0: 100 to 99:99.
1 is general, and more preferably 0: 100 to 91: 9. Thereby, generation of bubbles is suppressed, and defects on the surface of the alignment film and the optically anisotropic layer are significantly reduced. The coating method includes spin coating, dip coating, curtain coating, extrusion coating, bar coating, and E coating.
A mold coating method can be used. Among them, the E-type coating method is particularly preferable.

The thickness of the alignment film is preferably in the range of 0.1 to 10 μm. Heat drying is performed at a heating temperature of 20
To 110 ° C. In order to form a sufficient crosslink, the heating temperature is preferably in the range of 60 to 100 ° C, and more preferably in the range of 80 to 100 ° C. The drying time can be 1 minute to 36 hours. Preferably, it is 5 to 30 minutes. p
H is also preferably set to an optimum value for the crosslinking agent to be used.
It is preferably in the range of 5 to 5.5, especially pH 5
It is preferable that

The orientation film is provided on the cellulose acetate film or the undercoat layer. The orientation film can be obtained by subjecting the surface to a rubbing treatment after crosslinking the polymer layer as described above. The rubbing treatment is LC
A processing method widely used as a liquid crystal alignment processing step of D can be used. That is, a method of rubbing the surface of the alignment film in a certain direction using paper, gauze, felt, rubber, nylon, polyester fiber, or the like can be used to obtain the alignment. Generally, rubbing is performed several times using a cloth or the like on which fibers having a uniform length and thickness are planted on average. The alignment film functions to define the alignment direction of the liquid crystal compound provided thereon.

[Polarizing Plate] The polarizing plate comprises a polarizing film and two transparent protective films disposed on both sides thereof. As the one protective film, the above-mentioned cellulose acetate film or a cellulose acetate film provided with an optically anisotropic layer can be used. As the other protective film, a normal cellulose acetate film may be used. The polarizing film includes an iodine-based polarizing film, a dye-based polarizing film using a dichroic dye, and a polyene-based polarizing film. The iodine-based polarizing film and the dye-based polarizing film are generally manufactured using a polyvinyl alcohol-based film. The cellulose acetate film is disposed so that the slow axis of the cellulose acetate film and the transmission axis of the polarizing film are substantially parallel to each other.

It was also found that the moisture permeability of the protective film was important for the productivity of the polarizing plate. The polarizing film and the protective film are bonded with an aqueous adhesive, and the adhesive solvent is dried by diffusing in the protective film.
The higher the moisture permeability of the protective film, the faster the drying, and the higher the productivity. However, if the protective film is too high, moisture may enter the polarizing film due to the use environment (high humidity) of the liquid crystal display device. The polarization ability decreases. The moisture permeability of the optical compensation sheet is determined by the thickness, free volume, or hydrophilic / hydrophobic properties of the polymer film (and the polymerizable liquid crystal compound). When the optical compensatory sheet is used as a protective film for a polarizing plate, the optical compensatory sheet has a moisture permeability of 100 to 1000.
(G / m ² ) / 24 hrs, preferably 300 to 700 (g / m ² ) / 24 hrs.

The thickness of the optical compensatory sheet can be adjusted by adjusting the lip flow rate and the line speed, or stretching and compressing when forming a cellulose acetate film. Since the moisture permeability differs depending on the main material to be used, it is possible to adjust the thickness to a preferred range. The free volume of the optical compensation sheet can be adjusted by the drying temperature and time in the case of film formation. Also in this case, since the moisture permeability differs depending on the main material used, it is possible to adjust the free volume to a preferable range. The hydrophilicity / hydrophobicity of the optical compensation film can be adjusted by additives. By adding a hydrophilic additive to the free volume, the moisture permeability increases, and conversely, by adding a hydrophobic additive, the moisture permeability can be reduced. By adjusting the moisture permeability of the optical compensatory sheet, it becomes possible to produce a polarizing plate having optical compensating ability at low cost and with high productivity.

[Liquid crystal display device] The above-mentioned optical compensation sheet,
Alternatively, a polarizing plate using the above-described optical compensation sheet is advantageously used for a liquid crystal display device, particularly for a transmission type liquid crystal display device.
The transmission type liquid crystal display device includes a liquid crystal cell and two polarizing plates disposed on both sides of the liquid crystal cell. A liquid crystal cell carries a liquid crystal between two electrode substrates. When the optical compensatory sheet of the present invention is used for a liquid crystal display device, one optical compensatory sheet is provided between the liquid crystal cell and one of the polarizing plates, or two optical compensating sheets are provided between the liquid crystal cell and both of the polarizing plates. Place. When the polarizing plate of the present invention is used for a liquid crystal display device, the polarizing plate of the present invention may be used instead of one of the two polarizing plates. The polarizing plate of the present invention may be used in place of both polarizing plates. When the polarizing plate of the present invention is used for a liquid crystal display device, the polarizing plate is arranged such that the optical compensation sheet used as a protective film thereof is on the liquid crystal cell side.

The liquid crystal cell is preferably of a TN mode, a VA mode or an OCB mode. The VA mode includes an MVA mode.

In the TN mode liquid crystal cell, the rod-like liquid crystal molecules are substantially horizontally aligned when no voltage is applied, and are further twisted at 60 to 120 °. The TN mode liquid crystal cell is most frequently used as a color TFT liquid crystal display device, and is described in many documents.

In a VA mode liquid crystal cell, rod-like liquid crystal molecules are substantially vertically aligned when no voltage is applied. VA
The liquid crystal cell of the mode includes (1) a VA mode liquid crystal cell in a narrow sense in which rod-like liquid crystal molecules are aligned substantially vertically when no voltage is applied, and substantially horizontally when a voltage is applied (Japanese Patent Laid-Open No. 2-176625). In addition, (2) VA mode is multi-domain (M) in order to enlarge the viewing angle.
VA mode liquid crystal cell (SID97, Digest of tec)
h. Papers (Preprints) 28 (1997) 845),
(3) A liquid crystal cell (n-ASM mode) in which rod-like liquid crystalline molecules are substantially vertically aligned when no voltage is applied and twisted multi-domain alignment is applied when voltage is applied (Preprints 58 to 59 (1998). ))) And (4)
Includes SURVAIVAL mode liquid crystal cells (presented at LCD International 98).

The OCB mode liquid crystal cell is a bend alignment mode liquid crystal cell in which rod-like liquid crystal molecules are aligned (symmetrically) in substantially opposite directions at the top and bottom of the liquid crystal cell. A liquid crystal display using a bend alignment mode liquid crystal cell is disclosed in U.S. Pat. Nos. 4,583,825 and 5,410,422. Since the rod-like liquid crystal molecules are symmetrically aligned at the upper and lower portions of the liquid crystal cell, the bend alignment mode liquid crystal cell has a self-optical compensation function. Therefore, this liquid crystal mode is OCB (Optically Compensated).
(atory Bend) Also called liquid crystal mode. The bend alignment mode liquid crystal display device has an advantage that the response speed is high.

[0133]

EXAMPLES Example 1 The following composition was put into a mixing tank, and stirred while heating to dissolve each component.
A cellulose acetate solution was prepared.

<< Cellulose Acetate Solution Composition >>セ ル ロ ー ス 100% by mass of cellulose acetate having a degree of acetylation of 60.9% triphenyl phosphate (plasticizer) 7 0.8 parts by mass Biphenyldiphenyl phosphate (plasticizer) 3.9 parts by mass Methylene chloride (first solvent) 300 parts by mass Methanol (second solvent) 54 parts by mass 1-butanol (third solvent) 11 parts by mass ────────────────────────────────

A separate mixing tank was charged with 16 parts by mass of the following retardation increasing agent, 80 parts by mass of methylene chloride and 20 parts by mass of methanol, and stirred with heating to prepare a retardation increasing solution.
25 parts by mass of a retardation increasing solution was mixed with 474 parts by mass of the cellulose acetate solution, and the mixture was sufficiently stirred to prepare a dope. The addition amount of the retardation enhancer
The amount was 5.5 parts by mass based on 100 parts by mass of cellulose acetate.

[0136]

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The dope obtained was cast using a band casting machine. A film having a residual solvent content of 15% by mass
The film was transversely stretched at a stretching ratio of 25% using a tenter at 0 ° C. to produce a cellulose acetate film.
About the produced cellulose acetate film (optical compensation sheet: KH-01), an ellipsometer (M-1) was used.
50, manufactured by JASCO Corporation, the Re retardation value and the Rth retardation value at a wavelength of 550 nm were measured. The results are shown in Table 1. Further, the produced cellulose acetate film was weighed using a digital film thickness meter (K-402B, manufactured by Anritsu Corporation) in an area of 1 area.
100 points were measured in a square meter (1 m × 1 m). The average value of the film thickness is 52.0 μm, and the standard deviation is 1.5 μm.
m.

[Example 2] Cellulose acetate solution 4
A dope was prepared by mixing 56 parts by mass of a retardation increasing agent solution with 74 parts by mass of a dope (cellulose acetate 100).
Cellulose acetate film (optical compensation sheet: KH-02) was prepared in the same manner as in Example 1 except that 7.8 parts by mass of a retardation increasing agent was used with respect to parts by mass, and the stretching ratio was changed to 12%. It was prepared and evaluated. The result is first
It is shown in the table. Further, the prepared cellulose acetate film was placed in a 1.5N potassium hydroxide solution (40 ° C.) for 5 minutes.
After immersion for minutes, the mixture was neutralized with sulfuric acid, washed with pure water, and dried. The surface energy of this cellulose acetate film determined by the contact angle method was 68 mN / m. Further, the produced cellulose acetate film was transferred to a digital film thickness meter (K-402B, Anritsu Corporation).
Was measured at 100 points in an area of 1 square meter (1m × 1m). The average value was 40.0 μm and the standard deviation was 1.8 μm. A coating solution having the following composition was applied onto the cellulose acetate film using a # 16 wire bar coater at 28 ml / m ² . It was dried with hot air at 60 ° C. for 60 seconds and further with hot air at 90 ° C. for 150 seconds. Next, the slow axis of the cellulose acetate film (wavelength 63
A rubbing treatment was performed on the formed film in the direction of 45 ° with respect to (measured at 2.8 nm).

<< Composition of Alignment Film Coating Solution >>変 性 The following modified polyvinyl alcohol 10 parts by mass Water 371 parts by mass Methanol 119 parts by mass Glutaraldehyde (crosslinked Agent) 0.5 parts by mass ────────────────────────────────────

[0140]

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(Formation of Optically Anisotropic Layer) On the alignment film, 41.01 g of the following discotic (liquid crystal) compound, ethylene oxide modified trimethylolpropane triacrylate (V # 360, manufactured by Osaka Organic Chemical Co., Ltd.) ) 4.06 g, cellulose acetate butyrate (CAB551-0.
2, 0.90 g of Eastman Chemical Co., Ltd., 0.23 g of cellulose acetate butyrate (CAB531-1, manufactured by Eastman Chemical Co.), 1.35 g of photopolymerization initiator (Irgacure 907, Ciba Geigy), sensitization (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.) 0.4
A coating solution of 5 g dissolved in 102 g of methyl ethyl ketone was applied with a # 3 wire bar. This was attached to a metal frame and heated in a thermostat at 130 ° C. for 2 minutes to orient the discotic compound. Next, at 130 ° C., 120 W /
UV irradiation was performed for 1 minute using a cm high-pressure mercury lamp to polymerize the discotic compound. Then, it was left to cool to room temperature. Thus, the optical compensation sheet with an optically anisotropic layer (KH-1)
2) was produced. The Re retardation value of the optically anisotropic layer measured at a wavelength of 546 nm was 38 nm. The angle (tilt angle) between the disk surface and the cellulose acetate film surface was 40 ° on average.

[0142]

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[Example 3] Cellulose acetate 100
A cellulose acetate film (optical compensation sheet: KH-03) was prepared in the same manner as in Example 1 except that 6.0 parts by mass of a retardation increasing agent was used and the stretching ratio was changed to 30%. Was evaluated. The results are shown in Table 1. Further, the produced cellulose acetate film was immersed in a 2.0 N potassium hydroxide solution (25 ° C.) for 2 minutes, neutralized with sulfuric acid, washed with pure water, and dried.
The surface energy of this cellulose acetate film determined by a contact angle method was 63 mN / m.
Then, 100 points of the produced cellulose acetate film were measured in a 1 square meter (1 m × 1 m) area using a digital film thickness meter (K-402B, manufactured by Anritsu Corporation). The average value of the film thickness was 38.5 μm, and the standard deviation was 1.4 μm.

[Comparative Example 1] A cellulose acetate film (optical compensation sheet: KH-H1) was prepared in the same manner as in Example 1 except that the cellulose acetate solution was used as a dope without any stretching treatment. Was evaluated. The results are shown in Table 1. Further, the prepared cellulose acetate film was transferred to a digital film thickness meter (K-40).
Using 2B, manufactured by Anritsu Corporation, 100 points were measured in an area of 1 square meter (1 m × 1 m). The average value of the film thickness was 80.5 μm, and the standard deviation was 1.7 μm.

[0145]

[Table 1] Table 1- Stretching ratio of retardation film raising agent Re Rth ──────────────────────────────────── Example 1 KH-01 5.5 parts by mass 25% 40 nm 130 nm Example 2 KH-02 7.8 parts by mass 12% 20 nm 110 nm Example 3 KH-03 6.0 parts by mass 30% 50 nm 130 nm Comparative Example 1 KH-H1 None No stretching 4 nm 48 nm ─────── ─────────────────────────────

Example 4 A polarizing film was prepared by adsorbing iodine on a stretched polyvinyl alcohol film, and KH-01 (optical compensation sheet) prepared in Example 1 was polarized using a polyvinyl alcohol-based adhesive. Affixed to one side of the membrane. A commercially available cellulose triacetate film (Fujitac TD80UF, manufactured by Fuji Photo Film Co., Ltd.) was subjected to a saponification treatment, and affixed to the opposite side of the polarizing film using a polyvinyl alcohol-based adhesive. The transmission axis of the polarizing film and the slow axis of KH-01 (optical compensation sheet) manufactured in Example 1 were arranged so as to be parallel. The transmission axis of the polarizing film and the slow axis of the commercially available cellulose triacetate film were arranged so as to be orthogonal to each other. Thus, a polarizing plate was produced.

Example 5 Iodine was adsorbed on a stretched polyvinyl alcohol film to prepare a polarizing film. Using a polyvinyl alcohol-based adhesive, KH-02 (optical compensation sheet) prepared in Example 2 was attached to one side of the polarizing film so that its slow axis was parallel to the transmission axis of the polarizing film. A commercially available cellulose triacetate film (Fujitac TD80UF, manufactured by Fuji Photo Film Co., Ltd.) was subjected to a saponification treatment, and affixed to the opposite side of the polarizing film using a polyvinyl alcohol-based adhesive. Further, KH-12 (optical compensation sheet) produced in Example 2 was replaced with KH-02.
On the (optical compensation sheet) side, they were bonded via an adhesive so that their slow axes were parallel to each other. Thus, a polarizing plate was produced.

Example 6 KH-0 produced in Example 3
A polarizing plate was produced in the same manner as in Example 4 except that No. 3 (optical compensation sheet) was used.

[Example 7] A liquid crystal display device (VL-1530S, manufactured by Fujitsu Ltd.) using a vertical alignment type liquid crystal cell.
Peel a pair of polarizing plates and a pair of optical compensation sheets provided in the, instead of the polarizing plate produced in Example 4,
One sheet of KH-01 (optical compensation sheet) produced in Example 1 was attached to the viewer side via an adhesive so as to be on the liquid crystal cell side. Also, one commercially available polarizing plate (HLC2-5618HCS, manufactured by Sanritz Co., Ltd.) was attached to the backlight side. The crossed Nicols arrangement was such that the transmission axis of the polarizing plate on the viewer side was in the vertical direction, and the transmission axis of the polarizing plate on the backlight side was in the horizontal direction. About the manufactured liquid crystal display device, a measuring machine (EZ-Contrast 160) was used.
D, manufactured by ELDIM), and the viewing angle was measured in eight steps from black display (L1) to white display (L8). The results are shown in Table 2.

[Comparative Example 2] A liquid crystal display device (VL-1530S, manufactured by Fujitsu Ltd.) using a vertical alignment type liquid crystal cell.
About the measuring machine (EZ-Contrast 160D, ELDI
M) (from black display (L1) to white display (L8)).
The viewing angle was measured in eight steps up to. The results are shown in Table 2.

[0151]

[Table 2] Table 2 ──────────────────────────────────── Liquid crystal viewing angle (contrast ratio Range of 10 or more without black-side gradation inversion) Display device Direction of transmission axis 45 ° from transmission axis ───────────────────────── ─────────── Example 7> 80 ゜> 80 ゜ Comparative Example 2> 80 ゜ 44 ゜────────────── (Note) Black side gradation inversion: Inversion between L1 and L2

(Evaluation of frame-shaped transmittance increase) A 15-inch liquid crystal display (VL) using a vertical alignment type liquid crystal cell was used.
-1530SW, manufactured by Fujitsu Ltd.), a pair of polarizing plates was peeled off, and the polarizing plate produced in Example 4 was replaced with an adhesive so that the optical compensation sheet was on the liquid crystal cell side. It was stuck on the observer side and the backlight side. The transmission axis of the polarizing plate on the observer side and the transmission axis of the polarizing plate on the backlight side were arranged to be orthogonal to each other. Temperature 25
After the backlight of the manufactured liquid crystal display device was continuously turned on for 5 hours under an environmental condition of ° C. and a relative humidity of 60%, light leakage was evaluated by visually observing the entire black display state in a dark room. As a result, 15 using the polarizing plate manufactured in Example 4 was used.
No frame-like transmittance increase (light leakage) occurred in the inch liquid crystal display device.

Example 8 (Preparation 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 two glass substrates thus obtained were opposed to each other in an arrangement in which the rubbing directions were parallel, and the cell gap was set to 6 μm. Δn is 0.13 in the cell gap
96 liquid crystal compounds (ZLI1132, manufactured by Merck) were injected to prepare bend alignment liquid crystal cells. Two elliptically polarizing plates produced in Example 5 were attached so as to sandwich the produced bend alignment cell. The optically anisotropic layer of the elliptically polarizing plate was arranged so as to face the cell substrate, and the rubbing direction of the liquid crystal cell was antiparallel to the rubbing direction of the optically anisotropic layer facing the cell substrate. A rectangular wave voltage of 55 Hz was applied to the liquid crystal cell. A normally white mode of 2 V for white display and 5 V for black display was set. The transmittance ratio (white display / black display) is defined as a contrast ratio, and a measuring device (EZ-Contrast 160D, ELD
IM display) from black display (L1) to white display (L
The viewing angle was measured in eight steps up to 8). The results are shown in Table 3.

[0154]

[Table 3] Table 3 液晶 Liquid crystal viewing angle (contrast ratio Range of 10 or more without black side gradation inversion) Display device Upper Lower Left / Right ──────────────────────────────── ──── Example 8 80 ゜ 80 ゜ 80 ゜ ──────────────────────────────────── ( Note) Black side gradation inversion: inversion between L1 and L2

(Evaluation of frame-shaped transmittance increase) In the same manner as in the above bend-aligned liquid crystal cell, a bend-aligned liquid crystal cell having a panel size of 17 inches was obtained by using two elliptically polarizing plates prepared in Example 5. Produced. Temperature 25 ° C, relative humidity 6
Under an environmental condition of 0%, a backlight was arranged on the produced liquid crystal panel, and the liquid crystal panel was lit continuously for 5 hours. Then, the entire black display state was visually observed in a dark room to evaluate light leakage. As a result, no increase in frame-like transmittance (light leakage) occurred in the manufactured 17-inch liquid crystal panel.

Example 9 A pair of polarizing plates provided in a liquid crystal display device (6E-A3, manufactured by Sharp Corporation) using a TN type liquid crystal cell was peeled off, and the polarized light produced in Example 6 was used instead. The plates were adhered one by one to the observer side and the backlight side via an adhesive so that the KH-03 (optical compensation sheet) produced in Example 3 was on the liquid crystal cell side. The transmission axis of the polarizing plate on the observer side and the transmission axis of the polarizing plate on the backlight side were arranged so as to be in O mode (perpendicular). About the manufactured liquid crystal display device, a measuring machine (EZ-
Using a Contrast 160D (manufactured by ELDIM), the viewing angle was measured in eight steps from black display (L1) to white display (L8). The results are shown in Table 4.

Comparative Example 3 A liquid crystal display device (6E-A3, manufactured by Sharp Corporation) using a TN type liquid crystal cell was displayed in black (L1) using a measuring machine (EZ-Contrast 160D, manufactured by ELDIM). ) To white display (L8), the viewing angle was measured in eight steps. The results are shown in Table 4.

[0158]

[Table 4] Table 4 視野 Liquid crystal viewing angle (contrast ratio Range of 10 or more without black side gradation inversion) Display device Upper Lower Left / Right ──────────────────────────────── ──── Example 9 18 ゜ 23 ゜ 77 ゜ Comparative Example 3 15 ゜ 25 ゜ 37 ゜──────── (Note) Inversion of black side: Inversion between L1 and L2

(Evaluation of frame-shaped transmittance increase) A 20-inch liquid crystal display device (LC-2) using a TN type liquid crystal cell was used.
0V1, manufactured by Sharp Corporation), and the polarizing plate produced in Example 6 was replaced with the polarizing plate prepared in Example 6.
One sheet was attached to each of the observer side and the backlight side via an adhesive so that the optical compensation sheet was on the liquid crystal cell side. The transmission axis of the polarizing plate on the observer side and the transmission axis of the polarizing plate on the backlight side were arranged to be orthogonal to each other. Temperature 25
After the backlight of the manufactured liquid crystal display device was continuously turned on for 5 hours under an environmental condition of ° C. and a relative humidity of 60%, light leakage was evaluated by visually observing the entire black display state in a dark room. As a result, 20 using the polarizing plate manufactured in Example 6 was used.
No frame-like transmittance increase (light leakage) occurred in the inch liquid crystal display device.

Example 10 The following composition was placed in a mixing tank and stirred while heating to dissolve each component to prepare a cellulose acetate solution.

<< Composition of Cellulose Acetate Solution >>セ ル ロ ー ス 100% by mass of cellulose acetate having a degree of acetylation of 60.9% triphenyl phosphate (plasticizer) 7 0.8 parts by mass Biphenyldiphenyl phosphate (plasticizer) 3.9 parts by mass Methylene chloride (first solvent) 300 parts by mass Methanol (second solvent) 54 parts by mass 1-butanol (third solvent) 11 parts by mass ────────────────────────────────

In another mixing tank, 16 parts by mass of the retardation increasing agent used in Example 1, 80 parts by mass of methylene chloride and 20 parts by mass of methanol were charged.
The mixture was stirred while heating to prepare a retardation increasing agent solution. 32 parts by mass of a retardation increasing solution was mixed with 468 parts by mass of the cellulose acetate solution, and the mixture was sufficiently stirred to prepare a dope. The amount of the retardation increasing agent added was 4.5 parts by mass based on 100 parts by mass of cellulose acetate.

The resulting dope was cast using a band casting machine. After the film surface temperature on the band reached 40 ° C., the film was dried for 1 minute, peeled off, and then subjected to 35% transverse uniaxial stretching of a tenter under a drying air at 130 ° C. Then 1
The film is stretched 10% longitudinally and uniaxially in the transport direction under a drying wind at 40 ° C., and dried for about 15 minutes with a drying wind at 130 ° C. to produce a cellulose acetate film (thickness: 50 μm) having a residual solvent amount of 0.3% by weight. did. The prepared cellulose acetate film (KH-04) was measured for a wavelength of 5 using an ellipsometer (M-150, manufactured by JASCO Corporation).
The Re retardation value and the Rth retardation value at 50 nm were measured. The results are shown in Table 5.

[Example 11] The dope obtained in Example 10 was cast using a band casting machine. After the film surface temperature on the band reached 40 ° C., the film was dried for 1 minute, peeled off, and then subjected to a 20% transverse uniaxial stretching of a tenter under a drying air at 130 ° C. Thereafter, the film is stretched by 8% in the conveying direction under a drying wind at 140 ° C., and dried for about 15 minutes by a drying air at 130 ° C., and a cellulose acetate film having a residual solvent amount of 0.3% by weight (thickness: 58 μm) Was manufactured. About the produced cellulose acetate film (KH-05), an ellipsometer (M-150, JASCO Corporation)
Re) and Rth retardation values at a wavelength of 550 nm were measured. The results are shown in Table 5.

The prepared cellulose acetate film was immersed in a 2.0 N potassium hydroxide solution (25 ° C.) for 2 minutes, neutralized with sulfuric acid, washed with pure water, and dried. Thus, saponification treatment was performed on the cellulose acetate film. The surface energy of this cellulose acetate film determined by a contact angle method was 63 mN / m. The orientation film coating solution used in Example 2 was applied onto the cellulose acetate film using a # 16 wire bar coater at 28 ml / m ² . 60 seconds with 60 ° C warm air,
Further, it was dried with warm air of 90 ° C. for 150 seconds. Next, the longitudinal direction of the cellulose acetate film was added to the formed film.
The rubbing treatment was performed in a direction of 5 °.

(Formation of Optically Anisotropic Layer) On the alignment film, 41.01 g of the discotic (liquid crystalline) compound used in Example 2 and ethylene oxide-modified trimethylolpropane triacrylate (V # 360, Osaka Organic Chemical Co., Ltd.) 4.0
6 g, cellulose acetate butyrate (CAB551
-0.2, 0.90 g of Eastman Chemical Co., Ltd., 0.23 g of cellulose acetate butyrate (CAB531-1, manufactured by Eastman Chemical Co.), 1.35 of photopolymerization initiator (Irgacure 907, Ciba Geigy)
g, sensitizer (Kayacure DETX, Nippon Kayaku Co., Ltd.)
Co., Ltd.) was applied with a # 3.6 wire bar.
This was heated in a constant temperature zone of 130 ° C. for 2 minutes to orient the discotic compound. Next, 120 W in an atmosphere of 60 ° C.
UV irradiation was performed for 1 minute using a / cm high-pressure mercury lamp to polymerize the discotic compound. Then, it was left to cool to room temperature. Thus, an optically anisotropic layer is formed, and an optical compensation sheet (K
H-15). The Re retardation value of the optically anisotropic layer measured at a wavelength of 546 nm was 43 nm. The angle (tilt angle) with respect to the cellulose acetate film surface was 42 ° on average.

Example 12 The following composition was placed in a mixing tank and stirred while heating to dissolve each component to prepare a cellulose acetate solution.

{Composition of Cellulose Acetate Solution}セ ル ロ ー ス 100% by mass of cellulose acetate with 60.7% acetylation degree Polyester urethane (B-326, Sumitomo Bayer Urethane Co., Ltd., Desmocol 176) 16 parts by weight Methylene chloride (first solvent) 300 parts by weight Methanol (second solvent) 54 parts by weight 1-butanol (third solvent) 11 parts by weight ─────────────────────────────

In another mixing tank, 16 parts by mass of the retardation increasing agent used in Example 1, 80 parts by mass of methylene chloride and 20 parts by mass of methanol were charged.
The mixture was stirred while heating to prepare a retardation increasing agent solution. 26 parts by mass of the retardation increasing solution was mixed with 474 parts by mass of the cellulose acetate solution, and the mixture was sufficiently stirred to prepare a dope. The addition amount of the retardation increasing agent was 3.5 parts by mass with respect to 100 parts by mass of cellulose acetate.

The obtained dope was cast using a band casting machine. After the film surface temperature on the band became 40 ° C., it was dried for 1 minute and peeled off, and the residual tablet was stretched 40% in the width direction with a tenter in a state of 15%. 28% in the longitudinal direction with 5% by weight of residual solvent
The cellulose acetate film is stretched and dried at 140 ° C., and the residual solvent is 0.3% by weight (thickness: 40 μm).
m) was prepared. For the produced cellulose acetate film (KH-06), an ellipsometer (M-1) was used.
50, manufactured by JASCO Corporation, the Re retardation value and the Rth retardation value at a wavelength of 550 nm were measured. The results are shown in Table 5. In the same manner as in Example 11, a saponification treatment, formation of an orientation film, and formation of an optically anisotropic layer were performed on the produced cellulose acetate film to prepare an optical compensation sheet (KH-16).

Example 13 The following composition was placed in a mixing tank and stirred while heating to dissolve each component to prepare a cellulose acetate solution.

<< Composition of Cellulose Acetate Solution >>セ ル ロ ー ス 100% by mass of cellulose acetate having a degree of acetylation of 60.7% Methylene chloride (first solvent) 300 Parts by mass methanol (second solvent) 54 parts by mass 1-butanol (third solvent) 11 parts by mass boron nitride powder (highly thermally conductive particles) 30 parts by mass ────────────────────

In another mixing tank, 16 parts by mass of the retardation increasing agent used in Example 1, 80 parts by mass of methylene chloride and 20 parts by mass of methanol were charged.
The mixture was stirred while heating to prepare a retardation increasing agent solution. 25 parts by mass of a retardation increasing solution was mixed with 474 parts by mass of the cellulose acetate solution, and the mixture was sufficiently stirred to prepare a dope. The addition amount of the retardation increasing agent was 3.5 parts by mass with respect to 100 parts by mass of cellulose acetate.

The resulting dope was cast using a band casting machine. After the film surface temperature on the band reached 40 ° C., the film was dried for 1 minute, peeled off, and then subjected to 38% transverse uniaxial stretching using a tenter under a drying wind at 140 ° C. afterwards,
It was dried for about 20 minutes in a drying air at 135 ° C., and a cellulose acetate film having a residual solvent amount of 0.3% by weight (thickness:
65 μm). When the thermal conductivity of the obtained cellulose acetate film was measured, it was found to be 1.2 W / (m
-K). The thermal conductivity was measured by sandwiching the sheet between a TO-3 type heater case and a copper plate, compressing 10% of the sheet thickness, and applying a power of 5 W to the copper heater case.
The temperature was held for one minute, and the temperature difference between the copper heater case and the copper plate was measured and calculated by the following equation. Thermal conductivity {W / (m · K)} = {power (W) × thickness (m)} / {temperature difference (K) × measured area (m ² )} fabricated cellulose acetate film (KH-07)
, The Re retardation value and the Rth retardation value at a wavelength of 550 nm were measured using an ellipsometer (M-150, manufactured by JASCO Corporation). The results are shown in Table 5. Further, the produced cellulose acetate film (KH-07) was immersed in a 1.5 N potassium hydroxide solution (40 ° C.) for 5 minutes, neutralized with sulfuric acid, washed with pure water, and dried. The surface energy of this cellulose acetate film (KH-07) determined by a contact angle method was 68 mN / m.

(Preparation of Alignment Film) On this cellulose acetate film, the coating solution for alignment film used in Example 2 was # 1
No. 6 was applied at 28 ml / m ² using a wire bar coater.
It was dried with hot air at 60 ° C. for 60 seconds and further with hot air at 90 ° C. for 150 seconds. Next, the formed film was subjected to a rubbing treatment in the direction of 45 ° with respect to the slow axis (measured at a wavelength of 632.8 nm) of the cellulose acetate film.

(Preparation of Liquid Crystalline Compound) First, synthesis of a liquid crystal polymer and confirmation of homeotropic alignment on a non-alignment-treated substrate are performed. 4-n-heptyl benzoic acid 10mmo
l, terephthalic acid 95 mmol, methylhydroquinone diacetate 50 mmol, catechol diacetate 50
Polymerization was performed at 270 ° C. for 12 hours in a nitrogen atmosphere using 100 mmol of sodium acetate and 100 mmol. Next, the obtained reaction product was dissolved in tetrachloroethane, and then purified by reprecipitation with methanol to obtain 22.0 g of a liquid crystalline polyester. The logarithmic viscosity of this liquid crystalline polyester is 0.15, and has a nematic phase as a liquid crystal phase.
The isotropic phase-liquid crystal phase transition temperature is 240 ° C., and the glass transition point is 7
5 ° C.

Using this liquid crystalline polyester, 10w
t% phenol / tetrachloroethane mixed solvent (6 /
4 weight ratio) solution was prepared. This solution was applied on a soda glass plate by a bar coating method, and the solvent was removed.
Next, after a heat treatment at 190 ° C. for 30 minutes, it was cooled and fixed at room temperature. As a result, a uniformly oriented liquid crystalline film having a thickness of 15 μm was obtained. Conoscopic observation revealed that the polymer liquid crystal had a positive uniaxial structure, indicating that the polymer had homeotropic alignment.

(Formation of Optically Anisotropic Layer) An 8 wt% tetrachloroethane solution of the liquid crystalline polyester obtained above was prepared. Next, it was applied on the above-mentioned alignment film by a spin coating method. Next, after removing the solvent, heat treatment was performed at 190 ° C. for 20 minutes. After the heat treatment, it was air-cooled and fixed.
The obtained optical compensation sheet (KH-17) was transparent, had no alignment defect, and had a uniform film thickness (1.55 μm).

Comparative Example 4 The procedure of Example 10 was repeated, except that the cellulose acetate solution was used as a dope as it was and no stretching treatment was performed.
3.0% by weight of cellulose acetate film (KH-
H2). The thickness of the produced cellulose acetate film was 80 μm. The optical characteristics of the obtained film were measured. The results are shown in Table 5.

[0180]

TABLE 5 Film Retardation Elevator Re Rth ──────────────────────────────────── Example 10 4.5 parts by mass of KH-04 45 nm 135 nm Example 11 KH-05 4.5 parts by mass 35 nm 125 nm Example 12 KH-06 3.5 parts by mass 25 nm 120 nm Example 13 KH-07 3.5 parts by mass 50 nm 90 nm Comparative Example 4 KH-H2 None 4 nm 48 nm ─── ─────────────────────────────────

Example 14 A polarizing film was prepared by adsorbing iodine on a stretched polyvinyl alcohol film, and the optical compensation sheet (KH-04) prepared in Example 10 was polarized using a polyvinyl alcohol-based adhesive. Affixed to one side of the membrane. Commercially available cellulose triacetate film (Fujitac TD80UF, Fuji Photo Film Co., Ltd.)
Was subjected to a saponification treatment, and attached to the opposite side of the polarizing film using a polyvinyl alcohol-based adhesive. The transmission axis of the polarizing film and the slow axis of the optical compensation sheet (KH-04) were arranged in parallel. Thus, a polarizing plate was produced.

Example 15 A polarizing film was prepared by adsorbing iodine on a stretched polyvinyl alcohol film, and the optical compensation sheet (KH-15) prepared in Example 11 was prepared using a polyvinyl alcohol-based adhesive. The cellulose acetate film (KH-05) serving as the support was attached to one side of the polarizing film so that the slow axis was parallel to the transmission axis of the polarizing film. A commercially available cellulose triacetate film (Fujitac TD80UF, manufactured by Fuji Photo Film Co., Ltd.) was subjected to a saponification treatment, and affixed to the opposite side of the polarizing film using a polyvinyl alcohol-based adhesive. Thus, a polarizing plate was produced.

Example 16 A polarizing film was produced by adsorbing iodine on a stretched polyvinyl alcohol film, and the optical compensation sheet (KH-16) produced in Example 12 was produced using a polyvinyl alcohol-based adhesive. The cellulose acetate film (KH-06) as the support was attached to one side of the polarizing film so that the slow axis was parallel to the transmission axis of the polarizing film. A commercially available cellulose triacetate film (Fujitac TD80UF, manufactured by Fuji Photo Film Co., Ltd.) was subjected to a saponification treatment, and affixed to the opposite side of the polarizing film using a polyvinyl alcohol-based adhesive. Thus, a polarizing plate was produced.

Example 17 A polarizing film was prepared by adsorbing iodine on a stretched polyvinyl alcohol film, and the optical compensation sheet (KH-17) prepared in Example 13 was prepared using a polyvinyl alcohol-based adhesive. The cellulose acetate film (KH-07) as a support was attached to one side of the polarizing film so that the slow axis was parallel to the transmission axis of the polarizing film. A commercially available cellulose triacetate film (Fujitac TD80UF, manufactured by Fuji Photo Film Co., Ltd.) was subjected to a saponification treatment, and affixed to the opposite side of the polarizing film using a polyvinyl alcohol-based adhesive. Thus, a polarizing plate was produced.

Comparative Example 5 A polarizing film was prepared by adsorbing iodine on a stretched polyvinyl alcohol film, and the optical compensation sheet (KH-H2) prepared in Comparative Example 4 was polarized using a polyvinyl alcohol-based adhesive. Affixed to one side of the membrane. A commercially available cellulose triacetate film (Fujitac TD80UF, manufactured by Fuji Photo Film Co., Ltd.) was subjected to a saponification treatment, and affixed to the opposite side of the polarizing film using a polyvinyl alcohol-based adhesive. Thus, a polarizing plate was produced.

[Embodiment 18] A liquid crystal display device (VL-1530S, Fujitsu Ltd.) using a vertical alignment type liquid crystal cell
The polarizer prepared in Example 14 is peeled off instead of the pair of polarizing plates and the pair of optical compensating sheets provided on the liquid crystal cell side, so that the optical compensating sheet (KH-04) is on the liquid crystal cell side. Was pasted on the observer side.
In addition, a commercially available polarizing plate (HLC2-
5618HCS, manufactured by Sanritz Co., Ltd.). The transmission axis of the polarizing plate on the observer side is up and down, and
The crossed Nicols arrangement was such that the transmission axis of the polarizing plate on the backlight side was in the left-right direction. For the manufactured liquid crystal display device, use a measuring device (EZ-Contrast 160D, ELDIM
(Manufactured by the company), the viewing angle was measured in eight steps from black display (L1) to white display (L8). The results are shown in Table 6.

[Comparative Example 6] A liquid crystal display device (VL-1530S, manufactured by Fujitsu Limited) using a vertical alignment type liquid crystal cell.
Peeling a pair of polarizing plates and a pair of optical compensation sheets provided in the, instead of the polarizing plate produced in Comparative Example 5,
One sheet of the optical compensation sheet (KH-H2) was adhered to the viewer side via an adhesive so as to be on the liquid crystal cell side. Also,
On the backlight side, a commercially available polarizing plate (HLC2-561) was used.
8HCS, manufactured by Sanritz Co., Ltd.). The crossed Nicols arrangement was such that the transmission axis of the polarizing plate on the viewer side was in the vertical direction, and the transmission axis of the polarizing plate on the backlight side was in the horizontal direction. The viewing angle of the prepared liquid crystal display device was measured in eight stages from black display (L1) to white display (L8) using a measuring device (EZ-Contrast 160D, manufactured by ELDIM). The results are shown in Table 6.

[0188]

Table 6 Table 6 ──────────────────────────────────── Liquid crystal viewing angle (contrast ratio Range of 10 or more without black-side gradation inversion) Display device Direction of transmission axis 45 ° from transmission axis ───────────────────────── ─────────── Example 18> 80 ゜> 80 ゜ Comparative Example 6> 80 ゜ 44 ゜────────────── (Note) Black side gradation inversion: Inversion between L1 and L2

(Evaluation of frame-shaped increase in transmittance) A 15-inch liquid crystal display (VL) using a vertical alignment type liquid crystal cell was used.
-1530SW (manufactured by Fujitsu Ltd.) is peeled off, and the polarizing plate produced in Example 14 is replaced with an adhesive such that the optical compensation sheet is on the liquid crystal cell side. It was stuck on the observer side and the backlight side. The transmission axis of the polarizing plate on the observer side and the transmission axis of the polarizing plate on the backlight side were arranged to be orthogonal to each other. Similarly, the polarizing plate manufactured in Comparative Example 5 was mounted on a liquid crystal display device. After the backlight of the manufactured liquid crystal display device was continuously turned on for 5 hours under environmental conditions of a temperature of 25 ° C. and a relative humidity of 60%,
Light leakage was evaluated by visually observing the entire black display state in a dark room. As a result, in the liquid crystal display device using the polarizing plate of Comparative Example 5, frame-shaped light leakage (increase in transmittance) occurred at the peripheral portion of the panel, whereas the polarizing plate manufactured in Example 14 was used. No frame-like increase in light transmittance (light leakage) occurred in the 15-inch liquid crystal display device.

Example 19 (Preparation of Bend Alignment Liquid Crystal Cell) A polyimide film was provided as an alignment film on a glass substrate with an ITO electrode, and a rubbing treatment was performed on the alignment film. The two glass substrates thus obtained were opposed to each other in an arrangement in which the rubbing directions were parallel, and the cell gap was set to 6 μm. Δn is 0.13 in the cell gap
96 liquid crystal compounds (ZLI1132, manufactured by Merck) were injected to prepare a 17-inch bend alignment liquid crystal cell. (Production of Liquid Crystal Display Device) Two elliptically polarizing plates produced in Example 15 were attached so as to sandwich the produced bend alignment cell. The optically anisotropic layer of the elliptically polarizing plate faces the cell substrate,
The rubbing direction of the liquid crystal cell and the rubbing direction of the optically anisotropic layer facing the liquid crystal cell were arranged to be antiparallel. A rectangular wave voltage of 55 Hz was applied to the liquid crystal cell. White display 2V,
A normally white mode with black display of 5 V was set. Using the ratio of transmittance (white display / black display) as a contrast ratio, using a measuring instrument (EZ-Contrast 160D, manufactured by ELDIM), the viewing angle in eight stages from black display (L1) to white display (L8) was determined. It was measured. The results are shown in Table 7.

[Example 20] (Preparation 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 subjected to a rubbing treatment. The two glass substrates thus obtained were opposed to each other in an arrangement in which the rubbing directions were parallel, and the cell gap was set to 6 μm. Δn is 0.13 in the cell gap
96 liquid crystal compounds (ZLI1132, manufactured by Merck) were injected to prepare a 17-inch bend alignment liquid crystal cell. (Preparation of Liquid Crystal Display) Two elliptically polarizing plates prepared in Example 16 were attached so as to sandwich the prepared bend alignment cell. The optically anisotropic layer of the elliptically polarizing plate faces the cell substrate,
The rubbing direction of the liquid crystal cell and the rubbing direction of the optically anisotropic layer facing the liquid crystal cell were arranged to be antiparallel. A rectangular wave voltage of 55 Hz was applied to the liquid crystal cell. White display 2V,
A normally white mode with black display of 5 V was set. Using the ratio of transmittance (white display / black display) as a contrast ratio, using a measuring instrument (EZ-Contrast 160D, manufactured by ELDIM), the viewing angle in eight stages from black display (L1) to white display (L8) was determined. It was measured. The results are shown in Table 7.

[0192]

Table 7 Table ──────────────────────────────────── Liquid crystal viewing angle (contrast ratio Range of 10 or more without gradation inversion on the black side) Display device Upper Lower Left / Right ──────────────────────────────── Example 19 80 ゜ 80 ゜ 80 ゜ Example 20 80 ゜ 80 ゜ 80 ゜──────── (Note) Black side gradation inversion: Inversion between L1 and L2

(Evaluation of frame-shaped transmittance increase) Temperature 25
A backlight was placed on the liquid crystal panels manufactured in Examples 19 and 20 under an environmental condition of 60 ° C. and a relative humidity of 60%, and the liquid crystal panel was lit continuously for 5 hours. Was evaluated. As a result, in the liquid crystal display device using the polarizing plate of Comparative Example 5, no frame-shaped transmittance increase (light leakage) occurred in the 17-inch liquid crystal panels manufactured in Examples 19 and 20.

[Example 21] A pair of polarizing plates provided in a liquid crystal display device (6E-A3, manufactured by Sharp Corporation) using a TN type liquid crystal cell was peeled off, and Example 17 was used instead.
The polarizing plates prepared in the above were adhered one by one to the observer side and the backlight side via an adhesive so that KH-07 was on the liquid crystal cell side. The transmission axis of the polarizing plate on the observer side and the transmission axis of the polarizing plate on the backlight side were arranged to be orthogonal. About the manufactured liquid crystal display device, a measuring machine (E
The viewing angle was measured in eight steps from black display (L1) to white display (L8) using Z-Contrast 160D (manufactured by ELDIM). The results are shown in Table 8.

Table 8 Table ──────────────────────────────────── Liquid crystal viewing angle (contrast ratio Range of 10 or more without gradation inversion on the black side) Display device Upper Lower Left / Right ──────────────────────────────── ──── Example 21 35 ゜ 60 ゜ 80 ゜ ( Note) Black side tone inversion: Inversion between L1 and L2

(Evaluation of increase in frame-shaped transmittance) A 20-inch liquid crystal display device (LC-2) using a TN type liquid crystal cell was used.
(0V1, manufactured by Sharp Corporation) was peeled off, and the polarizing plate produced in Example 17 was observed through an adhesive so that the optical compensation sheet was on the liquid crystal cell side instead. One sheet was attached to each of the user side and the backlight side. The transmission axis of the polarizing plate on the observer side and the transmission axis of the polarizing plate on the backlight side were arranged to be orthogonal to each other. Temperature 2
Under an environment condition of 5 ° C. and a relative humidity of 60%, the backlight of the manufactured liquid crystal display device was continuously turned on for 5 hours, and then the entire black display state was visually observed in a dark room to evaluate light leakage. As a result, 2 using the polarizing plate prepared in Example 17 was obtained.
No frame-like increase in light transmittance (light leakage) occurred in the 0-inch liquid crystal display device.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G02F 1/13363 G02F 1/13363 // (C08L 1/12 (C08L 1/12 75:06) 75:06 ) F-term (reference) 2H049 BA02 BA06 BA25 BA42 BB44 BB49 BC03 BC22 2H091 FA08X FA08Z FA11X FA11Z FB02 HA05 HA07 HA09 KA02 LA04 LA12 4F071 AA09 AA29 AA53 AC15 AC19 AF53 AH19 BA02 BB02 EU01 EU06 EU02 EL01 EU061 EU216 EV306 EV326 GP00

Claims (16)

[Claims] 1. A cellulose acetate having an acetylation degree in the range of 59.0 to 61.5%, and an aromatic compound having at least two aromatic rings in an amount of 0.01 to 100 parts by mass of cellulose acetate. 20 parts by mass,
It is made of one sheet of cellulose acetate film having a thickness in the range of 10 to 70 μm, and has a Re retardation value defined by the following formula (I) of 20 to 70 n.
m, and the Rth retardation value defined by the following formula (II) is in the range of 70 to 400 nm: (I) Re = (nx−ny) × d ( II) Rth = {(nx + ny) / 2-nz} × d [where nx is the refractive index in the slow axis direction in the film plane; ny is the refractive index in the fast axis direction in the film plane] Nz is the refractive index in the thickness direction of the film; and d is the film thickness]. 2. The cellulose acetate film further contains 0.1 to 30 parts by mass of polyester urethane based on 100 parts by mass of cellulose acetate.
Polyester urethane, an optical compensation sheet according to claim 1 which is a reaction product of polyester and diisocyanate represented by the following general formula: H - (- O- (CH 2) q -OOC -(CH ₂ ) _m -CO) _n -O- (CH ₂ ) _q -OH wherein q is an integer of 2 to 4; m is 2 to 4
Represents an integer of 1 to 100]. 3. A cellulose acetate having an acetylation degree in the range of 59.0 to 61.5%, and an aromatic compound having at least two aromatic rings in an amount of 0.01 to 100 parts by mass of cellulose acetate. 20 parts by mass,
An optically anisotropic layer formed from a liquid crystal compound is provided on a cellulose acetate film having a thickness in the range of 10 to 70 μm, and a Re letter defined by the following formula (I) of the cellulose acetate film. An optical compensatory sheet having a retardation value in the range of 20 to 70 nm and an Rth retardation value defined by the following formula (II) in the range of 70 to 400 nm: (I) Re = (nx− ny) × d (II) Rth = {(nx + ny) / 2−nz} × d [where nx is the refractive index in the slow axis direction in the film plane; ny is the fast phase in the film plane] Is the refractive index in the axial direction; nz is the refractive index in the thickness direction of the film; and d is the thickness of the film. 4. The cellulose acetate film further contains 0.1 to 30 parts by mass of polyester urethane based on 100 parts by mass of cellulose acetate.
Polyester urethane, an optical compensation sheet according to claim 2 which is a reaction product of polyester and diisocyanate represented by the following general formula: H - (- O- (CH 2) q -OOC -(CH ₂ ) _m -CO) _n -O- (CH ₂ ) _q -OH wherein q is an integer of 2 to 4; m is 2 to 4
Represents an integer of 1 to 100]. 5. The optical compensatory sheet according to claim 3, wherein the liquid crystalline compound is a discotic liquid crystalline compound. 6. The optical device according to claim 1, wherein the cellulose acetate film is a stretched product stretched at a stretch ratio of 3 to 100%. Compensation sheet. 7. The cellulose acetate film contains high thermal conductive particles, and has a thermal conductivity of 1 W / (m · m).
The optical compensation sheet according to any one of claims 1 to 4, wherein K) or more. 8. A cellulose acylate film having a heat conductive layer containing high heat conductive particles provided on at least one surface of the cellulose acetate film, wherein the heat conductivity of the cellulose acetate film having the heat conductive layer is 1 W / (m · K). 5) The optical compensation sheet according to any one of claims 1 to 4, wherein: 9. The optical compensation sheet according to claim 1, wherein the aromatic compound has at least one 1,3,5-triazine ring. 10. The optical compensation sheet according to claim 1, wherein the cellulose acetate film is formed by a co-casting method. 11. The optical compensatory sheet according to claim 1, wherein the cellulose acetate film is a biaxially stretched film. 12. A polarizing plate comprising a polarizing film and two transparent protective films disposed on both sides thereof, wherein one of the transparent protective films has an acetylation degree in the range of 59.0 to 61.5%. Certain cellulose acetate and cellulose acetate 1
The cellulose acetate film contains 0.01 to 20 parts by mass of an aromatic compound having at least two aromatic rings and has a thickness of 10 to 70 μm with respect to 00 parts by mass. Has a Re retardation value defined by the following formula (I) in the range of 20 to 70 nm, an Rth retardation value defined by the following formula (II) in the range of 70 to 400 nm, and further comprises cellulose acetate A polarizing plate characterized in that the slow axis of the film and the transmission axis of the polarizing film are substantially parallel to each other: (I) Re = (nx−ny) × d (II) Rth = {(Nx + ny) / 2-nz} × d [where nx is the refractive index in the slow axis direction in the film plane; ny is the fast axis direction in the film plane] Nz is the refractive index in the thickness direction of the film; and d is the film thickness]. 13. A polarizing plate comprising a polarizing film and two transparent protective films disposed on both sides thereof, wherein one of the transparent protective films has an acetylation degree in the range of 59.0 to 61.5%. Certain cellulose acetate and cellulose acetate 1
The liquid crystalline compound is formed on a cellulose acetate film containing 0.01 to 20 parts by mass of an aromatic compound having at least two aromatic rings and having a thickness of 10 to 70 μm with respect to 00 parts by mass. The cellulose acetate film has a Re retardation value defined by the following formula (I) in the range of 20 to 70 nm, and an Rth defined by the following formula (II). Retardation value is 70
(I) Re = (nx) wherein the slow axis of the cellulose acetate film and the transmission axis of the polarizing film are arranged so as to be substantially parallel to each other. −ny) × d (II) Rth = {(nx + ny) / 2−nz} × d [where nx is the refractive index in the slow axis direction in the film plane; ny is the refractive index in the film plane] Is the refractive index in the direction of the phase axis; nz is the refractive index in the thickness direction of the film; and d is the thickness of the film. 14. A liquid crystal display device comprising a liquid crystal cell and two polarizing plates disposed on both sides thereof, wherein the polarizing plate comprises a polarizing film and two transparent protective films disposed on both sides thereof. At least one of the two transparent protective films disposed between the cell and the polarizing film has an acetylation degree of 59.0.
To 61.5% of cellulose acetate, and 100 parts by mass of cellulose acetate, 0.01% of an aromatic compound having at least two aromatic rings.
A cellulose acetate film having a thickness of 10 to 70 μm and a Retardation value of the cellulose acetate film defined by the following formula (I) of 20 to 70 parts by mass.
nm, the Rth retardation value defined by the following formula (II) is in the range of 70 to 400 nm, and the slow axis of the cellulose acetate film and the transmission axis of the polarizing film adjacent to the cellulose acetate film. Are arranged so as to be substantially parallel to each other: (I) Re = (nx−ny) × d (II) Rth = {(nx + ny) / 2−nz} × d [Wherein, nx is the refractive index in the slow axis direction in the film plane; ny is the refractive index in the fast axis direction in the film plane; and nz is the refractive index in the film thickness direction. And d is the thickness of the film]. 15. A liquid crystal display device comprising a liquid crystal cell and two polarizing plates disposed on both sides thereof, wherein the polarizing plate comprises a polarizing film and two transparent protective films disposed on both sides thereof. At least one of the two transparent protective films disposed between the cell and the polarizing film has an acetylation degree of 59.0.
To 61.5% of cellulose acetate, and 100 parts by mass of cellulose acetate, 0.01% of an aromatic compound having at least two aromatic rings.
Comprises an optically anisotropic layer formed from a liquid crystal compound on a cellulose acetate film having a thickness of 10 to 70 μm,
The cellulose acetate film has a Re retardation value defined by the following formula (I) of 20 to 70 nm.
And defined by the following formula (II)
th retardation value is in the range of 70 to 400 nm, and the slow axis of the cellulose acetate film and the transmission axis of the polarizing film close to the cellulose acetate film are arranged so as to be substantially parallel to each other. Liquid crystal display device: (I) Re = (nx−ny) × d (II) Rth = {(nx + ny) / 2−nz} × d [where nx is refraction in the slow axis direction in the film plane] Ny is the refractive index in the direction of the fast axis in the plane of the film; nz is the refractive index in the thickness direction of the film; and d is the thickness of the film]. 16. The liquid crystal display device according to claim 14, wherein the liquid crystal cell is a TN mode, VA mode, MVA mode, or OCB mode liquid crystal cell.