JP2002071957A - Optical film, polarizing plate, optical film roll, display using optical film, and method of producing optical film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical film having such characteristics as to ensure a larger phase difference at a longer wavelength and also having good resistance to high temperature and high humidity and to provide a method for producing the optical film with superior productivity. SOLUTION: The optical film contains a cellulose ester having a 2-4C acyl group as a substituent. When the degree of substitution of acetyl groups is represented by A and the degree of substitution of propionyl or butyryl groups by B, the cellulose ester satisfies the expressions 2.0<=A+B<=3.0 (I) and A<2.4 (II). The refractive index Nx of the optical film at 590 nm wavelength in the direction of a backward phase axis and the refractive index Ny in the direction of a forward phase axis satisfy the expression 0.0005<=Nx-Ny<=0.0050 (III).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a retardation function that has a smaller retardation as the wavelength becomes shorter for use in an optical element such as a liquid crystal display or an anti-glare film, and can be used as a polarizing plate protective film. The present invention relates to an optical film and a method for manufacturing an optical film.

[0002]

2. Description of the Related Art Polarizing plates used in liquid crystal display devices and the like are:
In general, it is configured by laminating protective films made of a polymer film on both surfaces of a polarizer. The polarizer includes a polyvinyl alcohol-based film, an ethylene vinyl alcohol-based film, a cellulose-based film, and a polycarbonate-based film. A stretched system film or a stretched polyvinyl alcohol-based film followed by iodine dyeing is generally used. As a protective film, optical anisotropy is small,
Cellulose triacetate films are generally used because of their excellent transparency and adhesion to polarizers. As a polarizing plate protective film, in addition to the above properties,
It is important to be excellent in dimensional stability, ultraviolet absorption function for preventing deterioration of the polarizer, moisture barrier function and the like. The polarizer and the protective film are made of an adhesive or a resin mainly composed of natural rubber, synthetic rubber, acrylic resin, butyral resin, epoxy resin, polyester resin, polyamide resin, polyvinyl alcohol resin. It is bonded using an adhesive.

A retardation plate used in a liquid crystal display device or the like is used to solve problems such as color compensation and expansion of a viewing angle by being used in combination with a polarizing plate. It has the function of converting linearly polarized light to circularly polarized light with respect to wavelength and vice versa. 1
In order to obtain the above-mentioned effect with two retardation plates, it is preferable that the phase difference is λ / 4 at the wavelength (λ) incident on the retardation plate. Such a retardation plate can be used in a reflective liquid crystal display device having a configuration in which, for example, only one polarizing plate is used and the back electrode also functions as a reflective electrode, whereby a reflective display device with excellent image quality can be obtained. it can. In addition, for the observer of the guest-host type liquid crystal layer, this retardation plate may be used on the back side, or a circularly polarized light of a reflective polarizing plate composed of a cholesteric liquid crystal that reflects only one of the left and right circularly polarized light. Is similarly used as an element for converting into a linearly polarized light.

[0004] Further, by using as an anti-reflection film on a front plate of a plasma display or a display using an organic EL element, coloring of reflected light can be reduced. It can also be used for antireflection of touch panels and the like.

Conventionally, as a material of the retardation plate, there are polycarbonate, polysulfone, polyethersulfone, amorphous polyolefin and the like. These polymer films have the property that the retardation becomes smaller as the wavelength becomes longer, and it has been difficult to provide ideal retardation properties to all wavelengths in the visible light region.

To solve this problem, Japanese Patent Application Laid-Open No. 2000-137
No. 116 proposes to use an oriented film of cellulose acetate having a degree of acetylation of 2.5 to 2.8 as a retardation plate. According to this method, the longer the wavelength is, the larger the phase difference becomes, and an ideal phase difference characteristic is obtained for all wavelengths in the visible light region.

[0007] When the retardation plate is used in combination with a polarizing plate, the above-described effects can be obtained. Heretofore, a polarizing plate and a retardation plate have been configured as separate optical elements in a liquid crystal display device. Therefore, a process of bonding the polarizing plate and the retardation plate is necessary, which complicates the manufacturing process and generates defective products due to the intrusion of bubbles and foreign substances and wrinkles during bonding. There were many problems such as doing.

[0008] The present inventors thought that the manufacturing process of the liquid crystal display device could be shortened and the occurrence of defects could be reduced by attaching a retardation plate to the polarizer instead of the protective film of the polarizing plate.

A conventional retardation plate using polycarbonate cannot be saponified, so that it has poor adhesion to a polarizer and is difficult to use as a protective film for a polarizing plate. According to the above-mentioned Japanese Patent Application Laid-Open No. 2000-137116, since the material of the retardation plate is cellulose acetate, the problem of the adhesiveness to the polarizer was considered to be improved. However, since the degree of acetylation is lower than that of ordinary cellulostriacetate, the moisture content of the film becomes too large, and the barrier property of moisture is significantly reduced. It has been found that when exposed for a long time, the polarizer and the protective film are peeled off or the polarizer is deteriorated. Even when used as a retardation film separately from the polarizing plate protective film,
Further, a retardation plate having excellent dimensional stability has been demanded. Further, a retardation film having excellent production stability and surface quality has also been required.

[0010] Recently, liquid crystal display devices are also provided with portability, the number of opportunities to use them outdoors is increasing, and the usage of such devices in a vehicle is increasing. Has been receiving special attention in recent years. Considering the conditions of use, the durability of the polarizing plate should be 8
It is necessary that the polarizing plate does not deteriorate when exposed for 1000 hours in an environment of 0 ° C. and 90% RH. Further, there is also a demand for a retardation film having little change in retardation characteristics under high temperature and high humidity conditions.

As described above, an optical film having a phase difference function of increasing the phase difference as the wavelength is longer and having good resistance to high temperature and high humidity has not yet been put to practical use. Met.

[0012]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an optical film which has a characteristic that the longer the wavelength is, the larger the phase difference becomes, and which has good resistance to high temperature and high humidity and excellent productivity. It is to provide a manufacturing method.

[0013]

The above object has been attained by the structure described in the claims of the present invention.

Hereinafter, the present invention will be described in detail.

The cellulose ester used in the present invention has an acyl group having 2 to 4 carbon atoms as a substituent and satisfies the following formulas (I) and (II) simultaneously. (I) 2.0 ≦ A + B ≦ 3.0 (II) A <2.4 Here, A is the degree of substitution of an acetyl group, and B is the degree of substitution of an acyl group having 3 or 4 carbon atoms.

Cellulose has three hydroxyl groups in one glucose unit, and the degree of substitution is a numerical value indicating on average how many acyl groups are bonded to one glucose unit. . Therefore, the maximum degree of substitution is 3.0. These acyl groups may be substituted at the 2-, 3-, and 6-positions of the glucose unit on average, or may be substituted with a distribution. Further, cellulose esters having different degrees of substitution of acyl groups may be blended to fall within the above range as the cellulose ester as a whole.

The degree of substitution of the acetyl group and the degree of substitution of the other acyl group were determined by ASTM-D817-96.

It is particularly preferable that the following formulas (IV) and (V) are simultaneously satisfied.

(IV) 2.4 ≦ A + B ≦ 2.8 (V) 1.4 ≦ A ≦ 2.0 When the degree of substitution between the acetyl group and the acyl group having 3 to 4 carbon atoms is within the above range. In addition, it is possible to obtain an optical film having a characteristic that the retardation becomes larger as the wavelength becomes longer, and also has a good moisture content and water barrier properties.

It is particularly preferable that the average degree of substitution of the acetyl group is less than 2.0, since the dispersion of the retardation during stretching is small.

The viscosity-average degree of polymerization (degree of polymerization) of the cellulose ester used in the present invention is preferably from 200 to 700, particularly preferably from 250 to 500. By being in the above range, an optical film excellent in mechanical strength can be obtained.

The viscosity average degree of polymerization (DP) is determined by the following method. [Viscosity average degree of polymerization (DP)] 0.2 g of absolutely dried cellulose ester is precisely weighed and dissolved in 100 ml of a mixed solvent of methylene chloride and ethanol (mass ratio 9: 1). This is measured for drop seconds at 25 ° C. using an Ostwald viscometer, and the degree of polymerization is determined by the following equation. ηrel = T / Ts [η] = (lnηrel) / CDP = [η] / Km where T is the number of seconds of falling of the measurement sample, Ts is the number of seconds of falling of the solvent, and C is the concentration of cellulose ester (g). / L), Km =
It is 6 × 10 ^-4 .

The raw cellulose for the cellulose ester used in the present invention includes cotton linter and wood pulp (derived from softwood or hardwood). Cellulose esters of different raw materials may be used alone or in combination. The cellulose ester acylated with an acetyl group and an acyl group having 3 or 4 carbon atoms used in the present invention is also called a mixed fatty acid ester of cellulose.

Examples of the acyl group having 3 or 4 carbon atoms include a propionyl group and a butyryl group. Propionyl group or n-butyryl group is preferred from the viewpoint of mechanical strength when formed into a film, ease of dissolution and the like,
Particularly, a propionyl group is preferable.

In the acylation of cellulose, when an acid anhydride or an acid chloride is used as an acylating agent, an organic acid such as acetic acid or methylene chloride is used as an organic solvent as a reaction solvent. You.

When the acylating agent is an acid anhydride, a protic catalyst such as sulfuric acid is preferably used, and the acylating agent is an acid chloride (eg, CH ₃ C).
In the case of (H ₂ COCl), a basic compound is used.

The most common industrial synthesis method of mixed fatty acid esters of cellulose is to convert cellulose to fatty acids (acetic acid, propionic acid, acetic acid, propionic acid, etc.) corresponding to acetyl groups and other acyl groups.
This is a method of acylating with a mixed organic acid component containing valeric acid or the like or an acid anhydride thereof.

The cellulose ester used in the present invention can be synthesized, for example, by the method described in JP-A-10-45804.

The optical film of the present invention has a wavelength of 400 to 7
In the range of 00 nm, a longer wavelength shows a larger phase difference.

Here, the in-plane retardation R ₀ of the film is obtained by the following equation: R ₀ = (Nx−Ny) × d. Here, Nx represents the refractive index in the slow axis direction in the plane of the film, Ny represents the refractive index in the fast axis direction in the plane of the film, and d represents the film thickness (nm) of the film.

In the present invention, an optical film having an R ₀ of 50 to 1000 nm can be obtained according to the application, but more preferably 70 to 700 nm, and particularly preferably 100 to 400 nm.
nm optical films are preferred.

[0032] In particular, Nx, if the wavelength of the light for obtaining the Ny is determined in 590nm and R _590, wavelength similarly 4
R ₄₅₀ is obtained when the light is obtained with 50 nm light, and the wavelength is 650 nm.
When it is determined that _R650 is obtained with the light of the above, it is determined that the range of 0.5 < _R450 / _R590 <1.0 1.0 < _R650 / _R590 <1.5 is satisfied. It is preferable because it has excellent polarization function. More preferably, 0.7 < _R450 /
R ₅₉₀ <0.95, 1.01 <R ₆₅₀ / R ₅₉₀ <1.2, particularly preferably 0.8 <R ₄₅₀ / R ₅₉₀ <0.9
3,1.02 <is _{R 65 0 / R 590 <1.1} .

In the case where the optical film of the present invention is used as a quarter-wave plate, the phase difference R ₅₅₀ of the optical film at a wavelength of 550nm is 137.5 nm ± 20 nm is preferably further 137.5 nm ± 10 nm Is preferred. Also, R ₅₉₀ is preferably 147.5nm ± 20nm, preferably a further 147.5nm ± 10nm. With this range, a good function of a quarter-wave plate can be obtained.

In order to obtain the preferable optical characteristics as described above, the difference between the refractive index Nx in the slow axis direction and the refractive index Ny in the fast axis direction in the film plane of the optical film must be 0.00.
It is necessary to be not less than 05 and not more than 0.0050. A more preferred range is 0.0010 or more and 0.0030 or less.

The refractive index Nx in the slow axis direction, the refractive index Ny in the fast axis direction, and the refractive index N in the thickness direction in the plane of the film.
z, (Nx + Ny) / 2-Nz is 0.000
It is also effective to set it to 5 or more and 0.002 or less, and it is particularly preferable that it is 0.0010 or more and 0.0020 or less.

To make the refractive index of the film fall within the above range,
This can be achieved by stretching the film having the cellulose ester of the present invention, but the cellulose ester film generally has poor stretchability due to its high glass transition temperature and rigid molecular structure. Therefore, it was necessary to include a large amount of a plasticizer or to stretch at a high temperature. However, under such conditions, there were problems such as bleeding out of the plasticizer and deterioration and coloring of the resin.
However, the authors have developed a stretching method that does not have these problems by the method described below, and have completed the optical film of the present invention.

The retardation (R _t ) in the thickness direction of the optical film of the present invention is preferably from 1 nm to 300 nm, and particularly preferably from 75 to 200 nm, in order to obtain an optical compensation effect such as an increase in viewing angle. It is preferred in that respect.

R _t = (Nx + Ny) / 2−Nz × d where the refractive index N in the slow axis direction at a wavelength of 590 nm
x, refractive index Ny in the fast axis direction, refractive index Nz in the thickness direction,
d is the film thickness (nm) of the film.

In the optical film of the present invention, the above N
It is particularly preferable that x, Ny, and Nz have a relationship of Nx> Ny ≧ Nz.

The haze of the optical film of the present invention is preferably 1.0% or less, more preferably 0.5% or less, and particularly preferably 0 to less than 0.1%. The transmittance is preferably 90% or more, particularly 92%.
It is desirable that this is the case.

The thickness of the optical film of the present invention is usually 5
Although it is in the range of from 500 to 500 μm, when it is also used as a polarizing plate protective film, the range of from 20 to 200 μm is preferable from the viewpoint of the dimensional stability of the polarizing plate, water barrier property and the like. or,
The thickness variation in the length direction and the width direction of the roll film is preferably within ± 3%, particularly preferably within ± 1%, and more preferably within ± 0.1%.

In the optical film of the present invention, a plasticizer such as a phthalate ester or a phosphate ester, an ultraviolet absorber,
Additives such as antioxidants and matting agents can also be added.

The optical film of the present invention preferably contains a plasticizer. The plasticizer that can be used is not particularly limited, but in the case of a phosphate ester system, triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, Phthalates such as diphenylbiphenyl phosphate, trioctyl phosphate and tributyl phosphate include diethyl phthalate, dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate and dibutyl phthalate. And glycol-2-esters such as di-2-ethylhexyl phthalate, triacetin, tributyrin, butyl phthalyl butyl glycolate, ethyl phthalyl ethyl glycolate, and methyl phthalyl ethyl glycolate. Butyl phthalyl butyl glycolate, and other triacetyl citrates Le and citrate-based plasticizers such as may be used alone or in combination. If necessary, two or more plasticizers may be used in combination.

By adding these plasticizers, the moisture content of the film can be reduced and the water barrier property can be improved.

In the production of the optical film of the present invention, the solvent remaining in the film as described later is controlled by
By stretching, stretching can be performed even at a high temperature, but when this method is not used, stretching can be performed at a high temperature. When stretching at a high temperature, the stretching temperature is preferably stretched at a temperature equal to or higher than the glass transition temperature of the cellulose ester. There are cases. It is necessary to use a plasticizer capable of imparting sufficient stretchability even at a high temperature, and it has been found that a non-volatile plasticizer can be preferably used as such a plasticizer. Non-volatile plasticizers have a vapor pressure of 1333 at 200 ° C.
It is a compound having a pressure of not more than Pa, having an extremely low vapor pressure and a low volatility. The vapor pressure is more preferably 667 Pa or less, and even more preferably 133 Pa or less. For example, allylene bis (diaryl phosphate) ester is preferred. In addition, tricresyl phosphate (39 Pa, 200 ° C.), tris (2-ethylhexyl) trimellitate (67 Pa, 200 ° C.) and the like are also preferably used. Alternatively, Tokuhyo Hei 6-501040
The non-volatile phosphate described in the above item is also preferably used.

Specific examples of the nonvolatile plasticizer are shown below.

[0047]

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In addition, polyester, acrylic resin,
High molecular weight plasticizers such as polymers or oligomers such as copolymers containing polyvinyl acetate can also be preferably used.

In this case, the content of the plasticizer is preferably 0.1 to 30% by mass, particularly preferably 0.5 to 15% by mass, based on the cellulose ester. Further, if necessary, a plasticizer concentration distribution may be provided in the thickness direction of the film. Can be. For example, when the average amount of plasticizer is 1, the amount of plasticizer near both surfaces can be independently set to 0.1 to 10. By using a plasticizer in this way, the stretchability of cellulose ester at a high temperature can be improved, and in particular, an optical film having excellent surface quality and flatness can be manufactured with high productivity.

In the present invention, it is preferable that an ultraviolet absorber is contained in the cellulose ester film. The ultraviolet absorber has an excellent ability to absorb ultraviolet light having a wavelength of 370 nm or less from the viewpoint of preventing deterioration of the liquid crystal. From the viewpoint of good liquid crystal display properties, those which absorb as little as possible visible light having a wavelength of 400 nm or more are preferably used. In particular, the transmittance at a wavelength of 370 nm is desirably 10% by mass or less, preferably 5% by mass or less, and more preferably 2% by mass or less. For example, oxybenzophenone-based compounds, benzotriazo-
, A salicylic acid ester compound, a benzophenone compound, a cyanoacrylate compound, a nickel complex salt compound, and the like, but are not limited thereto. Two or more ultraviolet absorbers may be used. The ultraviolet absorber may be added to the dope after being dissolved in an organic solvent such as alcohol, methylene chloride, or dioxolane, or may be added directly to the dope composition.
Those which do not dissolve in an organic solvent such as inorganic powder are dispersed in an organic solvent and a cellulose ester using a dissolver or a sand mill, and then added to the dope. In the present invention, the amount of the ultraviolet absorber used is 0.1 to 5.0% by mass, preferably 0.5 to 2.0% by mass, based on the cellulose ester.
0 mass%, more preferably 0.8 to 2.0 mass%.

An optical film has a strict quality level against surface defects such as foreign matter and scratches. It is preferable to use an ultraviolet absorber having a distribution coefficient of 9.2 or more, because such an optical film having few surface defects can be obtained. The distribution coefficient of the ultraviolet absorbent is more preferably 10.0 or more,
0.3 or more is most preferable. The partition coefficient represents the partition ratio between octanol and water defined by the following equation.

(Partition coefficient) = Log (Po / w) where Po / w = So / Sw where So represents the solubility of the ultraviolet absorbent in n-octanol at 25 ° C., and Sw represents 25 It represents the solubility of the UV absorber in pure water at ° C.

Examples of the ultraviolet absorber having a preferable distribution coefficient include a compound represented by the following general formula 1. Among them, a compound represented by the following general formula 2 is particularly preferable. General formula 1

[0054]

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In the formula, R1, R2, R3, R4, and R5 are monovalent organic groups, which may be the same or different. However, at least R1, R2, R3
Is an unsubstituted branched or straight-chain alkyl group having 10 to 20 carbon atoms. Further, it preferably has 11 to 18 carbon atoms, and particularly preferably has 12 to 15 carbon atoms. When the number of carbon atoms is in this range, the compatibility with the cellulose ester is excellent.

Here, the monovalent organic group includes a hydrogen atom, a halogen atom, a nitro group, a hydroxyl group, an alkyl group, an alkenyl group, an aryl group, an alkoxy group, an acyloxy group, an aryloxy group, an alkylthio group. , An arylthio group, a mono- or dialkylamino group, an acylamino group or a 5- to 6-membered heterocyclic group.

Specific examples of the general formula 1 are shown below, but are not limited thereto.

[0058]

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Formula 2

[0060]

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In the formula, R1, R2, R4 and R5 are monovalent organic groups, and have the same meaning as R1 to R5 in the general formula 1. R6 is a branched alkyl group, and is a branched alkyl group having 3 to 20, preferably 3 to 15 carbon atoms, such as an isopropyl group and an isobutyl group.

The following are specific examples of the general formula 2, but the present invention is not limited thereto.

[0063]

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In addition to the above-mentioned ultraviolet absorbers, for example,
JP-A-6-148430, Japanese Patent Application No. 12-156039
The polymer ultraviolet absorber described in (1) can also be preferably used for this purpose.

Further, the cellulose ester film of the present invention preferably contains an antioxidant. As the antioxidant, a hindered phenol compound is preferably used. Di-tert-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,
5-di-t-butyl-4-hydroxyphenyl) propionate], triethyleneglycol-bis [3- (3
-T-butyl-5-methyl-4-hydroxyphenyl)
Propionate], 1,6-hexanediol-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 2,4-bis- (n-octylthio)- 6- (4-hydroxy-3,5-di-t-butylanilino) -1,3,5-triazine, 2,2-thio-diethylenebis [3- (3,5-di-t-butyl-
4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, N, N'hexamethylenebis (3,5-di-t- Butyl-4-hydroxy-hydrocinnamamide), 1,3,5-trimethyl-2,4,6
-Tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, tris- (3,5-di-t-butyl-4-hydroxybenzyl) -isocyanurate and the like. In particular, 2,6-di-t-butyl-p-crezo-
Pentaerythrityl-tetrakis [3- (3,5-
Di-tert-butyl-4-hydroxyphenyl) propionate], triethyleneglycol-bis [3- (3-t
-Butyl-5-methyl-4-hydroxyphenyl) propionate] is preferred. Also, for example, a hydrazine-based metal deactivator such as N, N'-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine or tris (2,4-di-t A phosphorus-based processing stabilizer such as (-butylphenyl) phosphite may be used in combination. The addition amount of these compounds is preferably 1 ppm to 1.0% by mass relative to the cellulose ester, and
0-1000 ppm is more preferred. Further, in the present invention, in the cellulose ester film, in order to improve the handleability, for example, silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, kaolin, talc, calcined calcium silicate, hydrated calcium silicate And inorganic fine particles such as aluminum silicate, magnesium silicate and calcium phosphate, and a matting agent such as a crosslinked polymer. Among them, silicon dioxide is preferable because the haze of the film can be reduced. The average particle size of the secondary particles of the fine particles is in the range of 0.01 to 1.0 μm,
The content is 0.005 to cellulose ester.
0.3 mass% is preferred. Fine particles such as silicon dioxide are often surface-treated with an organic substance, but such particles are preferable because the haze of the film can be reduced. Preferred organic materials for the surface treatment include halosilanes, alkoxysilanes, silazanes, siloxanes, and the like, and a treatment in which a methyl group is present on the surface is preferable. The larger the average particle size of the fine particles, the greater the matting effect, and the smaller the average particle size, the better the transparency. Therefore, the average particle size of the primary particles of the fine particles is preferably 5 to 50 nm, and more preferably 7 to 16 nm. . These fine particles are usually present in the film as aggregates, and it is preferable to form irregularities of 0.01 to 1.0 μm on the film surface.

As the fine particles of silicon dioxide, AEROSIL 200, 200V, 30
0, R972, R972V, R974, R202, R8
12, OX50, TT600, etc., preferably AEROSIL R972, R972V, R9
74, R202 and R812. Two or more of these matting agents may be used in combination. When two or more kinds are used in combination, they can be mixed and used at an arbitrary ratio. In this case, a matting agent having a different average particle size or material, for example, AEROSIL
200 V and R972 V in a mass ratio of 0.1: 99.9 to
It can be used in the range of 99.9: 0.1.

Since the optical film of the present invention has a water barrier property and a low water content, it can be preferably used for a polarizing plate as a protective film for the polarizing plate. As described above, the polarizing plate is formed by attaching and laminating a protective film for a polarizing plate on at least one surface of the polarizer. As the polarizer, a conventionally known polarizer can be used. For example, a polarizer is obtained by treating a hydrophilic polymer film such as a polyvinyl alcohol film with a dichroic dye such as iodine and stretching. Lamination of the cellulose ester film and the polarizer is not particularly limited, but can be performed with an adhesive comprising an aqueous solution of a water-soluble polymer. As this water-soluble polymer adhesive, a completely saponified aqueous solution of polyvinyl alcohol is preferably used.

The polarizing plate thus obtained can be used for various display devices. Examples of the display device include a liquid crystal display device, an organic electroluminescent device, an organic EL display, a plasma display, and the like. Film / polarizer / optical film of the present invention / glass substrate / ITO transparent electrode / alignment film / TN type liquid crystal / alignment film / metal electrode / reflection film / glass substrate. In the conventional case, the polarizing plate protective film / polarizer / polarizing plate protective film / retardation plate / glass substrate / ITO transparent electrode / alignment film / TN type liquid crystal /
It has a configuration of alignment film / metal electrode / reflection film / glass substrate.
In the conventional configuration, coloring is observed due to insufficient retardation characteristics with respect to the wavelength of the retardation plate. However, by using the optical film of the present invention, a good liquid crystal display device without coloring can be obtained. In addition, the optical film of the present invention can be preferably used by being bonded to a polarizing plate as a retardation film.In addition, by using the optical film of the present invention, a polarizing plate protective film conventionally used separately and The retardation plate can be made of a single film, so that the time-consuming laminating process can be shortened.

In the case of a reflective polarizing element comprising a cholesteric liquid crystal, it can be used in the configuration of backlight / cholesteric liquid crystal layer / optical film of the present invention / polarizer / polarizer protective film. In the case of a polarizing plate using the optical film of the present invention as a quarter-wave plate, the polarizing plate can convert linearly polarized light into circularly polarized light. this is,
When it is installed on a front plate such as a plasma display or an organic EL display, it functions as an anti-reflection film or an anti-glare film, and can prevent coloring and deterioration in visibility. It can also be used to prevent reflection on touch panels.

The organic electroluminescent device is also called an organic EL device, and is introduced, for example, in Japan's Journal of Applied Physics, Vol. 25, 773 (1986). The configuration is, for example, transparent substrate / anode / organic light emitting layer / cathode, or transparent substrate / anode /
Hole injection transport layer / electron injection transport layer / cathode or transparent substrate / anode / hole injection transport layer / electron injection transport layer / cathode or transparent substrate / anode / hole injection transport layer / organic light emitting layer / electron The injection transport layer / cathode and the like are arranged in this order.
In this configuration, light from the outside enters from the transparent substrate side, and light reflected on the cathode surface is reflected, resulting in poor visibility. However, by providing a circularly polarizing plate on the surface of the transparent substrate, it is possible to block light reflected on the surface of the cathode, resulting in a display having excellent visibility.

The method for producing the optical film of the present invention is not particularly limited, but the following method can be preferably used. First, a cellulose ester is dissolved in an organic solvent capable of dissolving to form a dope. A cellulose ester flake or powder is mixed with an organic solvent and dissolved with stirring to form a dope. The dissolution may be carried out at normal pressure, at a temperature below the boiling point of the main solvent, at a pressure at or above the boiling point of the main solvent, disclosed in JP-A-9-95544, JP-A-9-95557 or JP-A-9-95538. There are various dissolving methods such as a method performed by a cooling dissolution method as described and a method performed at a high pressure as described in JP-A-11-21379. After dissolution, the dope is filtered with a filter medium, defoamed, and sent to the next step by a pump. The concentration of cellulose ester in the dope is 10-3.
About 5% by mass is preferable, and particularly 20 to 35% by mass is preferably used.

As the cellulose ester used in the present invention, those having little bright spot foreign matter are preferably used. The bright spot foreign matter is a phenomenon in which cellulosic material is present between polarizing plates arranged in crossed Nicols.
When a sester film sample is placed, illuminated from one side, and observed from the other, a point that appears shining when light from a light source is transmitted is called a bright spot foreign matter. Optical films for display devices are required to have a small number of such films.
00 / cm < ² > or less, particularly preferably substantially no, and a bright spot foreign matter having a size of 5 to 10 [mu] m is 200
Pcs / cm ² or less, preferably 50 pcs / cm ² or less, and preferably substantially no. It is desirable that the number of luminescent spot foreign matters less than 5 μm is also small. The bright spot foreign matter of the optical film can be reduced by selecting a raw material having less bright spot foreign matter of cellulose ester and filtering the cellulose ester solution used for casting. Organic solvents capable of dissolving the cellulose ester include methyl acetate, ethyl acetate, amyl acetate, ethyl formate, acetone, cyclohexanone, methyl acetoacetate, tetrahydrofuran,
3-dioxolan, 1,4-dioxane, 2,2,2-
Trifluoroethanol, 2,2,3,3-hexafluoro-1-propanol, 1,3-difluoro-2-propanol, 1,1,1,3,3,3-hexafluoro- 2-methyl-2-propanol, 1,1,1,3,
3,3-hexafluoro-2-propanol, 2,2
3,3,3-pentafluoro-1-propanol, 1,
3-dimethyl-2-imidazolidinone, nitroethane,
Methylene chloride and the like can be mentioned. Chlorine-based organic solvents such as methylene chloride may not be used in recent severe environmental problems, and non-chlorine-based organic solvents are more preferable. Among them, methyl acetate and acetone can be preferably used. Also, when a lower alcohol such as methanol, ethanol or butanol is used in combination with these organic solvents, the solubility of the cellulose ester in the organic solvent can be improved or the dope viscosity can be reduced. It is preferable because it can improve the peelability when peeling off from the support.
Particularly, ethanol having a low boiling point and low toxicity is preferred.
These lower alcohols account for 2% by mass of the total organic solvent.
As described above, the content is preferably 50% by mass or less. In the solution casting film forming method, the above-mentioned dope is filtered, sent to a die by a metering pump, and the dope is cast from the die onto a stainless belt or a metal drum whose surface is polished, and the metal is supported. On the body, the organic solvent is evaporated or cooled to solidify, the web is peeled off before the metal support goes around, and dried in a drying step to form a film.

The cellulose ester solution (hereinafter also referred to as “dope”) prepared as described above is passed through a pressurized type fixed gear pump through a pressurized fixed-quantity gear pump that can send a fixed amount of liquid with high precision by, for example, the number of rotations. Sent. The dope sent from the gear pump to the pressing die is uniformly cast from a die (slit) of the pressing die onto a support that is rotating endlessly. When the support has completed one round, it is peeled off from the support as a freshly dried film (web) and dried while being passed through a rotating roll group. It is wound up.

The casting method useful in the present invention includes a method in which the adjusted dope is uniformly extruded from a pressing die onto a support, and a method in which the dope once cast on the support is braided. A method using a doctor blade to adjust the film thickness by a method, a method using a reverse roll coater to adjust the film thickness by a roll that rotates the dope once cast on the support in the reverse direction, and the like. However, a method using a pressing die is preferable. The pressure die includes a coat hanger type and a T die type, and any of them can be preferably used. In addition to the above,
For example, JP-A-61-94724 and JP-A-61-1480.
No. 13, JP-A-4-85011 and JP-A-4-286611
No. 5-185443, No. 5-185445, No. 6-278149, and conventionally known methods described in No. 8-207210 can be preferably used,
By setting each condition in consideration of the difference in the boiling point of the solvent to be used, the same effects as those described in the respective publications can be obtained. As the endless support, a drum whose surface is mirror-finished by chrome plating or a stainless belt (also referred to as a band) whose surface is mirror-finished by surface polishing is preferably used. One or more pressing dies may be provided. Preferably, it is one or two. When two or more units are installed, the amount of the dope to be cast may be divided into various ratios for each die, and the dope is supplied to the dice at each ratio from a plurality of precision metering gear pumps. The dope cast on the support may be, for example, a method in which hot air is blown from the front side of the drum or belt, that is, a web side on the support, a method in which hot air is blown from the back of the drum or belt, or a temperature control. Contact the backside of the belt or drum
The drum or belt can be heated by heat transfer and dried by a liquid heat transfer method of controlling the surface temperature, but it is preferable to use a back liquid heat transfer method. The surface temperature of the support before the dope is cast
Any number may be used as long as it is lower than the boiling point of the solvent used in the pump. However, in order to promote drying and cause the dope to lose fluidity on the support, set the temperature to 1 to 10 ° C. lower than the boiling point of the lowest boiling solvent among the solvents used. Is preferred. The production speed varies depending on the diameter of the drum or the length of the belt, the drying method, the composition of the dope solvent, etc., but the amount of the residual solvent at the time when the formed web is separated from the drum or the belt is also affected. I do. That is, if the solvent concentration in the vicinity of the surface of the drum or belt in the thickness direction of the dope film is too high, the dope remains on the drum or belt when the formed web is peeled off, and the next casting occurs. This is because the formed web needs to be strong enough to withstand the peeling force. The amount of residual solvent at the time of peeling differs depending on the drying method, and the method of transferring heat from the back of the belt or drum is more effective in reducing the amount of residual solvent than the method of drying by blowing air from the surface of the dope. can do. A method for drying a web that has been dried and peeled on a drum or belt will be described. The web peeled at the peeling position immediately before the drum or belt makes one revolution is transported alternately through a group of rolls arranged in a staggered manner, or both ends of the peeled web are gripped with a clip or the like. It is transported by a non-contact transport method or the like. Drying is performed by a method in which air at a predetermined temperature is applied to both surfaces of the web (film) being conveyed, or a method using a heating means such as a microwave. Since rapid drying may impair the planarity of the film to be formed, it is preferable to dry at a temperature at which the solvent does not foam at the initial stage of drying, and to dry at a high temperature after the drying has progressed. In the drying step after peeling from the support, the film tends to shrink in the longitudinal direction or the width direction due to evaporation of the solvent. Shrinkage increases with drying at higher temperatures. Drying while suppressing this shrinkage as much as possible is preferable for improving the flatness of the resulting film. From this point, for example, Japanese Patent Application Laid-Open No. 62-4662.
As shown in No. 5, a method (tenter method) in which all or some of the drying steps are carried out while holding both ends of the web width in the width direction by clips or pins is preferable. The drying temperature in the drying step is 40 to 250.
C., especially 70 to 180.degree. The drying temperature, the amount of drying air, and the drying time vary depending on the solvent used, but may be appropriately selected according to the type and combination of the solvents used. In the method for producing an optical film of the present invention, the web (film) peeled from the support is preferably stretched when the residual solvent amount in the web is less than 120% by mass, and particularly preferably from 10 to 1%.
While in the range of 00% by weight, at least one direction is not limited to 1.
It is preferable that the film is stretched by 2 to 4.0 times.

The residual solvent amount can be expressed by the following equation.

Residual solvent amount (% by mass) = {(M + N) / N} × 100 where M is the mass of the web at an arbitrary point in time, and N is the time when the web from which M was measured was dried at 110 ° C. for 3 hours. Is the mass of If the residual solvent amount in the web is too large, the effect of stretching cannot be obtained, and if too small, the stretching becomes extremely difficult,
Web breakage may occur. The more preferable range of the amount of the residual solvent in the web is from 10% by mass to 50% by mass, particularly preferably from 12% by mass to 40% by mass. Also, if the stretching ratio is too small, a sufficient phase difference cannot be obtained,
If it is too large, stretching may be difficult and breakage may occur. A more preferred range of the stretching ratio is from 1.25 times.
The range is 3.5 times, and more preferably 1.3 times to 2.times.
It is 0 times. A solution cast film formed using the cellulose ester of the present invention can be stretched without heating to a high temperature as long as the residual solvent amount is within a specific range. It is preferable because it can be short. However, if the temperature of the web is too high, the plasticizer volatilizes, so the range of room temperature (15 ° C) to 160 ° C or less is preferable. Stretching in biaxial directions orthogonal to each other is an effective method for keeping the refractive indexes Nx, Ny, and Nz of the film within the scope of the present invention. For example, when the film is stretched in the casting direction, if the shrinkage in the width direction is too large, the value of Nz becomes too large. In this case, the width shrinkage of the film is suppressed or
It can be improved by stretching in the width direction. In the case of stretching in the width direction, a distribution may occur in the refractive index due to the width. This may be seen, for example, when using a tenter method, but by stretching in the width direction, a contraction force is generated at the center of the film, and the phenomenon is caused by the fact that the ends are fixed. This is considered to be a so-called bowing phenomenon. Even in this case, by stretching in the casting direction,
The wing phenomenon can be suppressed, and the distribution of the phase difference in the width can be reduced and improved. Furthermore, the film thickness fluctuation of the film obtained by stretching in biaxial directions perpendicular to each other can be reduced. If the variation in the film thickness of the optical film is too large, the phase difference becomes uneven, which causes a problem such as coloring when used as a circularly polarizing plate. The variation in the thickness of the optical film is ± 3%, and further ± 1%.
% Is preferable. For the above purpose, a method of stretching in biaxial directions orthogonal to each other is effective, and the stretching ratios in the biaxial directions orthogonal to each other are 1.2 to 4.0 times and 1.0 to 1.2 times, respectively. It is preferable to make the range twice as large. The method for stretching the web is not particularly limited. For example, a method is used in which a plurality of rolls are provided with a peripheral speed difference, and the roll is stretched in the longitudinal direction by utilizing the roll peripheral speed difference. A method of spreading in the traveling direction and stretching in the vertical direction, a method of spreading in the horizontal direction and stretching in the horizontal direction, or a method of simultaneously spreading vertically and horizontally and stretching in both the vertical and horizontal directions are included. Of course, these methods may be used in combination. Also, in the case of the so-called tenter method, it is preferable to drive the clip portion by the linear drive method because smooth stretching can be performed and the risk of breakage can be reduced.

In the film obtained as described above, the amount of the residual solvent in the final film is preferably 2% by mass or less, more preferably 0.4% by mass or less, in order to obtain a film having good dimensional stability. Is preferred. Furthermore, when the amount of residual solvent is 10
It is preferable to treat the film dried to less than 5% by mass, preferably less than 5% by mass at a temperature of 130 to 200 ° C. for 10 seconds or more, preferably for 30 seconds or more, since a film having further excellent dimensional stability can be obtained. Once from room temperature to 100
More preferably, the film, which has been cooled to below ℃, is treated again at this temperature. Especially 10 ° C higher than the temperature at the time of stretching
It is effective to lower the above. The steps from the casting to the post-drying may be performed under an air atmosphere or under an inert gas atmosphere such as nitrogen gas. As the winding machine for winding the obtained cellulose ester film, a generally used winding machine can be used, and a constant tension method, a constant torque method, a taper tension method, and a constant internal stress method can be used. It can be wound by a winding method such as a program tension control method. In the optical film roll obtained as described above, the slow axis direction of the film is preferably ± 15 degrees, more preferably ± 5 degrees, with respect to the winding direction (length direction of the film). Is preferably within the range. Alternatively, the angle is preferably ± 15 degrees with respect to the direction perpendicular to the winding direction (the width direction of the film), and more preferably ± 5 degrees. In particular, the slow axis direction of the film is preferably within ± 1 degree with respect to the winding direction (length direction of the film). Alternatively, the angle is preferably within ± 1 degree with respect to the width direction of the film.

Incidentally, a circularly polarizing plate is obtained by laminating the optical film with the slow axis of 45 ° with respect to the polarizing axis of the polarizer. When the optical film of the present invention is used as a protective film for a circularly polarizing plate, if the slow axis of the optical film is at an angle of approximately 45 ° with respect to the length direction of the roll-shaped long film, the roll is rolled. It is preferable because it can be continuously bonded to a polarizer using a long film. For example, such a retardation plate can be obtained by using a method described in JP-A-2000-9912 in combination. The thickness of the finished optical film (after drying) of the present invention is adjusted to a desired thickness so that the solid content contained in the dope, the slit gap of the die, the extrusion pressure from the die, and the support It can be performed by adjusting the body speed and the like. Another method preferably used in the method for producing an optical film of the present invention will be described. In the present invention, as described above, by controlling the amount of the residual solvent in the film, the film can be stretched without increasing the temperature. However, the following method can also be used for stretching. That is, carbon number 2
When the degree of substitution of the acetyl group is A and the degree of substitution of the propionyl group or the butyryl group is B, the cellulose having the following formulas (XII) and (XIII) is satisfied at the same time. A solution obtained by dissolving a polyester and a plasticizer having a vapor pressure of 1333 Pa or less at 200 ° C. in an organic solvent is cast on a support, and the solvent is evaporated to form a cellulose ester film.
This is a method of stretching in at least one direction at a temperature of 0 ° C. so as to satisfy the following formula (XIV). (XII) 2.0 ≦ A + B ≦ 3.0 (XIII) A <2.4 (XIV) 0.0005 ≦ Nx−Ny ≦ 0.0050 The plasticizer having a specific vapor pressure and the stretching method are described above. It is on the street. The film can be stretched at a peeling residual amount of 10% by mass or less, but is particularly preferably stretched at less than 2% by mass. The optical film thus obtained is 1 /
It is useful as various retardation films such as a 4λ plate and a 1 / 2λ plate.

[0079]

EXAMPLES The present invention will be described below in more detail with reference to examples.
However, the present invention is not limited by these examples.
Not. Moisture content measurement The film sample was dried at 120 ° C for 1 hour.
The mass M0 (g) of the film at that time is measured. Then this
After leaving the sample at 23 ° C. and 55% RH for 3 days,
At this time, the mass M (g) of the film is measured. Moisture content
It is obtained by the following equation. Water content (%) = (M + M0) / M × 100 Example 1 Degree of substitution of acetyl group 2.00, degree of substitution of propionyl group
0.80, Cellulose acetate having a viscosity average degree of polymerization of 350
-100 parts by mass of topropionate, ethylphthalylethyl
Luglycolate 5 parts by mass, triphenyl phosphate
3 parts by mass, 290 parts by mass of methylene chloride, 60 ethanol
Put parts by mass in a closed container, and stir the mixture slowly.
And gradually raise the temperature to 45 ° C over 60 minutes to dissolve
Was. The pressure in the container was 1.2 atm. This dope is filtered by Azumi
Azumi filter paper No. Filtered using 244
Thereafter, the mixture was allowed to stand for 24 hours to remove bubbles in the dope. Also this
Separately, the above cellulose acetate propionate 5
Parts by mass, Tinuvin 326 (Ciba Specialty Chem
6 parts by mass of CULZ CORPORATION), Tinuvin 109 (Ciba
4 parts by mass, manufactured by Peshati Chemicals Co., Ltd.
171 (Ciba Specialty Chemicals Co., Ltd.)
5 parts by mass), 94 parts by mass of methylene chloride and ethanol
Mix 8 parts by mass, stir and dissolve, adjust UV absorber solution
did. UV absorption for 100 parts by weight of the dope
2 parts by weight of the agent solution and add it to the static mixer.
After mixing more thoroughly, put it on a stainless steel belt from the die.
Casting was performed at a loop temperature of 30 ° C. and a width of 1.6 m. stainless
The temperature is brought into contact with hot water of 25 ° C from the back of the belt.
After drying for 1 minute on a controlled stainless steel belt,
Contact the cold water of 15 ° C with the back of the stainless steel belt
After holding for 15 seconds, peel off from the stainless steel belt
Was. The amount of residual solvent in the web at the time of peeling was 100% by mass.
Was. Next, the cleaved using a simultaneous biaxial stretching tenter
Grip both ends of the web with clips, and
By simultaneously changing in the casting direction (length direction), 12
At 0 ° C, 2.0 times in the width direction and 1. in the casting direction (length direction).
The film was stretched by one time. After the stretching is completed, the film temperature is temporarily set to 80
After cooling to 13 ° C., 13
The film was stretched 1.1 times in the length direction at 0 ° C. Roller transport
While drying at 130 ° C for 10 minutes.
Of cellulose ester film (optical film 1)
Was. The optical film 1 is made of glass fiber having a core diameter of 200 mm.
1m wide and 1000m long film on reinforced resin core
The film was wound into a roll by the taper tension method. this
At the time, press an emboss ring at a temperature of 250 ° C
And apply the thickness to make the films adhere to each other.
Prevented. From the obtained film roll, the width of the film
From the opposite end, the center and the opposite end.
Refractive index Nx in the slow axis direction, refractive index Ny in the fast axis direction, thickness
The refractive index Nz in the vertical direction is measured as follows, and Nx−Ny,
(Nx + Ny) / 2-Nz, R ₀ Calculated each of
However, at the end, 0.00148, 0.000
7, 147.5 nm, and 0.0014 in the center in order.
6, 0.0008, 146.0 nm, at opposite end
Are 0.00148, 0.0008, and 148.0 nm.
Yes, both are within the scope of the present invention, and a retardation film
It was confirmed that it had preferable characteristics. Where R ₀ = (Nx-Ny) × d, where d is the fill
The direction of the slow axis is the width of the film for each sample.
Direction was within ± 2 degrees. (Refractive index in slow axis direction, refractive index in fast axis direction, thickness direction
Of the refractive index and the direction of the slow axis of an automatic birefringence meter KOB
Using RA-21ADH (manufactured by Oji Scientific Instruments),
Under the environment of 23 ° C and 55% RH, the wavelength is 590 nm.
Then, a three-dimensional refractive index measurement is performed, and the refractive indices Nx, Ny, N
z was determined. As a result of measuring the moisture content by the method described above, 1.8 was obtained.
%Met. Apart from the above, the degree of substitution of the acetyl group is 2.9.
2. Cellulose triacetate having a viscosity average degree of polymerization of 300
100 parts by mass, ethylphthalylethyl glycolate 2
Parts, 10 parts by mass of triphenyl phosphate,
A sealed container containing 350 parts by mass of styrene and 50 parts by mass of ethanol
And slowly raise the temperature while slowly stirring the mixture,
The temperature was raised to 45 ° C. over 60 minutes to dissolve. 1.2 in the container
Atmospheric pressure. Azumi filter manufactured by Azumi Filter Paper Co., Ltd.
Paper No. After filtration using 244, let stand for 24 hours.
Bubbles in the dope were removed. Separately, the above cell
5 parts by mass of rostriacetate, Tinuvin 326 (Chiba
・ Specialty Chemicals Co., Ltd.) 3 parts by mass
Nubin 109 (Ciba Specialty Chemicals)
7 parts by mass, Tinuvin 171 (Ciba Specialty)
5 parts by mass of Ruti Chemicals Co., Ltd.) and AERO
1 part by mass of SIL 200V (manufactured by Nippon Aerosil Co., Ltd.)
Was mixed with 90 parts by mass of methylene chloride and 10 parts by mass of ethanol.
The resulting mixture was stirred and dissolved to prepare an ultraviolet absorbent solution. Above
2 parts by mass of the ultraviolet absorbent solution per 100 parts by mass of
And mixed well with a static mixer.
After that, a dope temperature of 35 ° C.
, And was cast at a width of 1.6 m. The back of the stainless steel belt
Temperature controlled by contacting hot water at a temperature of 35 ° C.
After drying on a stainless steel belt for 1 minute,
Contact with cold water of 15 ° C on the back of the rack and hold for 15 seconds
After that, it was peeled off from the stainless steel belt. When peeling
The amount of residual solvent in the solution was 70% by mass. Then peel off
Dry at 120 ° C for 10 minutes while fixing both ends of the web
80 μm thick cellulose ester film (protected)
A protective film 1) was obtained. Cellulose ester obtained
Film (protective film 1 and optical film 1)
60 ° C, 2 mol / l sodium hydroxide aqueous solution
Immerse in liquid for 2 minutes, wash with water, and dry at 100 ° C for 10 minutes
Dry to obtain an alkali saponified cellulose ester film
Was. In addition, polyvinyl alcohol having a thickness of 120 μm
Aqueous solution containing 1 part by mass of iodine and 4 parts by mass of boric acid
0 parts by mass, stretched 4 times at 50 ° C., and
Photon 1) was made. On one surface of the polarizer 1, the optical fiber
Film 1 and protective film 1 on the other side are completely saponified.
Using a 5% aqueous solution of polyvinyl alcohol as an adhesive
Each of the laminated polarizing plates was manufactured (polarizing plate 1). In addition,
The optical film 1 includes both ends in the width direction of the film roll.
Cut out the film sample from each
For each of them, two polarizing plates were prepared (total of six).
Was. Angle between the polarization axis of the polarizer and the width direction of the optical film
The bonding was performed so that the degree was 45 degrees. Next,
Of the six polarizing plates, each of the widths of the optical film
A total of three polarizing plates, one at a time, at 80 ° C and 90% RH
The subject was exposed for 1000 hours. Moisture obtained as above
Three polarizing plates without heat treatment and three polarizing plates with heat treatment
Used in single-panel polarizer reflective LCD display for evaluation
did. The structure is such that the polarizing plate / glass base of the present invention is viewed from the front side.
Plate / ITO transparent electrode / alignment film / TN type liquid crystal / alignment film / gold
A metal electrode / reflection film / glass substrate. Polarizer is protective
Lum was placed in the foreground. When the power is off and
In each case of power ON, visually evaluate the degree of coloring.
The coloring was hardly observed with any of the polarizing plates.
It was found that good contrast could be obtained
Was. Example 2 Degree of substitution of acetyl group 2.30, degree of substitution of propionyl group
0.5, a cellulose acetate having a viscosity average degree of polymerization of 400
100 parts by mass of propionate, ethylphthalylethyl acetate
5 parts by mass of recollate, 3 substances of triphenyl phosphate
Parts, 290 parts by weight of methylene chloride, 60 parts by weight of ethanol
Part into a closed container and slowly stir the mixture
The temperature was raised to 45 ° C. over 60 minutes to dissolve. Content
The pressure in the vessel became 1.2 atm. Azumi filter paper
Azumi filter paper No. Filtered using 244
Thereafter, the mixture was allowed to stand for 24 hours to remove bubbles in the dope. Also this
Separately, the above cellulose acetate propionate 5
Parts by mass, Tinuvin 326 (Ciba Specialty Chem
3 parts by mass of CULZ CORPORATION), Tinuvin 109 (Ciba
4 parts by mass, manufactured by Peshati Chemicals Co., Ltd.
171 (Ciba Specialty Chemicals Co., Ltd.)
4 parts by mass and AEROSIL R972V (Japan
1 part by mass of Erosil Co., Ltd.) 94 parts by mass of methylene chloride
And 8 parts by mass of ethanol and dissolve by stirring
An agent solution was prepared. Purple with respect to 100 parts by mass of the above dope
Add 2 parts by mass of the external line absorbent solution, and
After mixing well with a mixer, remove the stainless steel bell from the die.
It was cast at a dope temperature of 39 ° C. and a width of 1.6 m. Stay
Hot water at a temperature of 39 ° C from the back of the belt
1 minute on a temperature controlled stainless steel belt
After that, cold water of 15 ° C was further contacted to the back of the stainless steel belt.
Touch and hold for 15 seconds, then peel off from stainless steel belt
did. The amount of residual solvent in the web at the time of peeling was 20% by mass.
Was. Next, the cleaved using a simultaneous biaxial stretching tenter
Grip both ends of the web with clips, and
By simultaneously changing in the casting direction (length direction), 15
Stretched 3.0 times in the width direction at 0 ° C, in the casting direction (length direction)
Was shrunk 0.98 times. After this, once the film temperature
After cooling to 60 ° C., 130
Dried at 10 ° C. for 10 minutes to form a 50 μm-thick cellulose cellulose.
A tellurium film (optical film 2) was obtained. Optical film
2 is a core made of glass fiber reinforced resin having a core diameter of 200 mm.
1m width and 1000m length film roll
-It was wound up by a tension method. At this time,
Press the emboss ring at a temperature of 230 ° C.
Thickened to prevent adhesion between films
Was. From the obtained film roll, the end in the width direction of the film
Sampling from the center, center and opposite end
Refractive index Nx in the direction, refractive index Ny in the fast axis direction, thickness direction
Is measured as follows, and Nx−Ny, (Nx
+ Ny) / 2-Nz, R ₀ Was calculated,
At the ends, 0.00297, 0.0006, 14
8.5 nm, 0.00294, 0.0
008, 147.0 nm, at the opposite end, 0.00
300, 0.0007, and 150.0 nm.
Were also within the scope of the present invention. The direction of the slow axis is
0 degrees to the width direction at the center in the width direction of the lum,
It was 15 degrees and -15 degrees. Moisture content measurement as described above
As a result, it was 1.5%. Cellulosue obtained
Steal film (optical film 2) at 60 ° C, 2mol
/ L for 2 minutes in aqueous sodium hydroxide solution
After washing with water, dry at 100 ° C for 10 minutes and saponify with alkali
The treated cellulose ester film (optical film 2)
Obtained. On one surface of the polarizer 1 obtained in Example 1, the above optical
Film 2 was coated on the opposite side with the protective film obtained in Example 1.
Completely saponified polyvinyl alcohol 5% aqueous solution
Were used as adhesives to produce laminated polarizing plates
(Polarizing plate 2). In addition, the optical film 2 is a film row.
From both ends and the center in the width direction of the film.
Samples of each sample, two for each (total 6
Sheet) polarizing plate. This optical film 2 is a film
The slow axis at the end of the roll was greatly displaced from the width direction
Cut out samples at the center and edge of the film
By changing the angle, the polarization axis of the polarizer and the retardation of the optical film
Be careful not to make an angle of 45 degrees with the phase axis.
I had to get it. Next, the above-mentioned six polarizing plates
Of the polarizers with different widths of the optical film
A total of three sheets were prepared at 80 ° C and 90% RH for 100 sheets.
Exposure was for 0 hours. Without the wet heat treatment obtained as above
Commercially available using 3 polarizing plates and 3 polarizing plates with wet heat treatment
Of backlight / cholesteric liquid crystal layer / polarizing plate 2
When the degree of coloring was evaluated visually, the coloring was almost
I was not able to admit. Example 3 Degree of substitution of acetyl group 1.60 Degree of substitution of propionyl group
1.20 cellose acetate having a viscosity average degree of polymerization of 300
100 parts by mass of propionate, ethylphthalylethyl acetate
5 parts by mass of recollate, 3 substances of triphenyl phosphate
Parts, 290 parts by weight of methylene chloride, 60 parts by weight of ethanol
Part into a closed container and slowly stir the mixture
The temperature was raised to 45 ° C. over 60 minutes to dissolve. Content
The pressure in the vessel became 1.2 atm. Azumi filter paper
Azumi filter paper No. Filtered using 244
Thereafter, the mixture was allowed to stand for 24 hours to remove bubbles in the dope. Also this
Separately, the above cellulose acetate propionate 3
Parts by mass, Tinuvin 326 (Ciba Specialty Chem
3 parts by mass of CULZ CORPORATION), Tinuvin 109 (Ciba
4 parts by mass, manufactured by Peshati Chemicals Co., Ltd.
171 (Ciba Specialty Chemicals Co., Ltd.)
5 parts by mass of 90 parts by mass of methylene chloride and 1 part of ethanol
Mix 0 parts by mass, stir and dissolve to prepare UV absorber solution
did. Dissolve UV absorber in 100 parts by mass of the above dope
Add the liquid at a ratio of 2 parts by mass, and use a static mixer.
After mixing well, dope from the die onto a stainless steel belt.
It was cast at a temperature of 35 ° C. and a width of 1.6 m. Stainless bell
Temperature control by contacting hot water of 35 ° C from the back of
After drying for 1 minute on the stainless steel belt
15 ° C cold water is brought into contact with the back of
After holding for 5 seconds, it was peeled off from the stainless steel belt. Stripping
The residual solvent amount in the web at the time of release was 100% by mass.
Next, while carrying rolls in an oven at 120 ° C,
Oven exit for roll peripheral speed just after entrance of oven
Set the roll speed just before to 3.0 times and cast
The film was stretched 3.0 times in the machine direction (length direction of the film). Stretching
Thereafter, it was immediately cooled to 60 ° C. Using a tenter
Hold both ends of the web with clips and fix the clip interval
After drying at 140 ° C for 5 minutes, the cell with a thickness of 150 μm
A rose ester film (optical film 3) was obtained. light
Film 3 is a glass fiber reinforced tree with a core diameter of 200 mm.
Film roll with a width of 1m and a length of 1000m on a core made of fat
The film was wound in a tape-tension method. At this time,
Press the embossing ring with a temperature of 270 ° C against the lum end,
Apply a 10μm thickness so that the films adhere to each other
Was prevented. Width of film from obtained film roll
Sampling from end, middle and opposite end
The refractive index Nx in the slow axis direction, the refractive index Ny in the fast axis direction,
The refractive index Nz in the thickness direction was measured as follows, and Nx-N
y, (Nx + Ny) / 2-Nz, R ₀ Is calculated as
However, at the end, 0.00093, 0.001
0, 140.0 nm, and 0.0009 at the center.
9, 0.0011, 148.0 nm, at the opposite end
Is at 0.00095, 0.0010, 142.0 nm
And both were within the scope of the present invention. Also, the slow axis
The direction is the length direction at the center in the width direction of the film.
Direction), and 1 ° and -1 ° at the end.
Was. As a result of measuring the moisture content of the film by the method described above, 2.
It was 0%. The obtained cellulose ester film is
Sodium hydroxide aqueous solution of 2mol / l concentration at 60 ℃
After immersion in water for 2 minutes and washing with water, dry at 100 ° C for 10 minutes
To obtain an alkali saponified cellulose ester film.
(Optical film 3). Of the polarizer 1 obtained in Example 1
The above-mentioned optical film 3 is provided on one side, and Example 1 is provided on the other side.
Of the protective film 1 obtained by
Laminate each using a 5% aqueous solution of call as an adhesive
A polarizing plate was produced (polarizing plate 3). In addition, the optical film 3
From the both ends and the center in the width direction of the film roll.
Cut out each film sample, and for each
Polarizing plates were prepared two by two (a total of six). Polarizer polarization
The angle between the axis and the length direction of the optical film is 45 degrees.
And bonded together. Next, the above-mentioned six polarizing plates
Of the polarizers with different widths of the optical film
A total of three sheets were prepared at 80 ° C and 90% RH for 100 sheets.
Exposure was for 0 hours. Without the wet heat treatment obtained as above
Performed using 3 polarizing plates and 3 polarizing plates with wet heat treatment
When evaluated in the same manner as in Example 1, almost no coloring was observed.
Was not. Example 4 Cellulose ester used for an optical film was converted to an acetyl group.
Of substitution 1.90, substitution degree of butyryl group 0.75, viscosity
Cellulose acetate butyrate with an average degree of polymerization of 300
Except for the change, a 100 μm optical
Film 4 and its film roll were produced. Obtained
From the roll to the end of the film in the width direction and the center
And sampled from the opposite end and refracted in the slow axis direction
Index Nx, refractive index Ny in the fast axis direction, refractive index N in the thickness direction
z is measured as follows, and Nx−Ny, (Nx + Ny) /
2-Nz, R ₀ Was calculated, and at the end,
0.00148, 0.0013, 148.0 nm,
In the center, 0.00147, 0.0012, 14
7.0 nm, 0.00148, 0. 0 at the opposite end.
0013, 148.0 nm, both of which are within the scope of the present invention.
It was an enclosure. The direction of the slow axis is the width direction of the film.
0 degree in the width direction at the center, 5 degrees and -5 degrees at the ends
It was. As a result of measuring the moisture content by the method described above,
3%. On one surface of the polarizer 1 obtained in Example 1,
The optical film 4 described above was obtained on the opposite side in Example 1.
Protective film 1 is completely saponified polyvinyl alcohol 5
Each polarizing plate is laminated using an aqueous solution
It was produced (polarizing plate 4). Note that the optical film 4 is
From both ends and the center in the width direction of the lum roll,
Cut out film samples, two for each
(Total 6) A polarizing plate was produced. This optical film is
The slow axis at the end of the film roll is slightly shifted from the width direction.
However, both the center and the edge of the film
The angle between the optical film and the width direction should be 45 degrees
And bonded together. Next, the above-mentioned six polarizing plates are used.
In addition, one polarizing plate for each width of the optical film
1000 pieces under the condition of 80 ° C and 90% RH
Exposure. Polarized light without heat treatment obtained as above
Example 1 using three polarizing plates and three polarizing plates with wet heat treatment
When evaluated in the same manner as above, from the end of the film roll
Some coloring was observed in the optical film obtained.
However, the level was practically acceptable. Example 5 Degree of substitution of acetyl group 2.00, degree of substitution of propionyl group
0.80, Cellulose acetate having a viscosity average degree of polymerization of 350
100 parts by mass of toppropionate, ethylphthalylethyl
5 parts by mass of glycolate, triphenyl phosphate 3
Parts by mass, 175 parts by mass of methyl acetate, 75 parts by mass of ethanol
Part into a closed container and slowly stir the mixture
The temperature was raised to 65 ° C. over 60 minutes to dissolve. Content
The pressure in the vessel became 1.2 atm. Azumi filter paper
Azumi filter paper No. Filtered using 244
Thereafter, the mixture was allowed to stand for 24 hours to remove bubbles in the dope. Also this
Separately, the above cellulose acetate propionate 5
Parts by mass, Tinuvin 326 (Ciba Specialty Chem
6 parts by mass of CULZ CORPORATION), Tinuvin 109 (Ciba
4 parts by mass, manufactured by Peshati Chemicals Co., Ltd.
171 (Ciba Specialty Chemicals Co., Ltd.)
5 parts by weight of 94 parts by weight of methyl acetate and 8 parts of ethanol
Mix and stir to dissolve to prepare a UV absorber solution.
Was. UV absorber solution with respect to 100 parts by mass of the above dope
At a ratio of 2 parts by mass, and
After mixing, heat the dope from the die onto a stainless steel belt.
It was cast at a temperature of 40 ° C. and a width of 1.6 m. Stainless belt
The temperature is controlled by contacting hot water of 40 ° C from the back of the
After drying on a stainless steel belt for 2 minutes,
15 ° C cold water on the back of the belt
After holding for 2 seconds, it was peeled off from the stainless steel belt. Peeling
The amount of residual solvent in the web at that time was 70% by mass. Next
At both ends of the web peeled using a simultaneous biaxial stretching tenter
With a clip, and set the clip interval in the width direction and the casting direction.
(Length direction) at the same time, the width at 150 ℃
1.5 times in the direction, 1.05 times in the casting direction (length direction)
Stretched. After the completion of stretching, temporarily raise the film temperature to 80 ° C.
After cooling, at 130 ° C using rollers with different peripheral speeds
The film was stretched 1.05 times in the length direction. Do not transport the rollers further.
And dried at 130 ° C for 10 minutes.
A lurose ester film (optical film 5) was obtained.
The optical film 5 is made of glass fiber reinforced with a core diameter of 200 mm.
A film core with a width of 1 m and a length of 1000 m on a resin core
It was wound into a tape shape by a taper tension method. At this time,
Press the emboss ring at a temperature of 250 ° C against the end of the film.
To prevent the film from sticking to each other
did. From the obtained film roll,
Sampling from end, center and opposite end
Refractive index Nx in axial direction, refractive index Ny in fast axis direction, thickness direction
The refractive index Nz of the direction is measured as follows, and Nx−Ny, (N
x + Ny) / 2-Nz, R ₀ Where each was calculated
And at the end, 0.00148, 0.0011, 1
47.5 nm, 0.00147, 0.
0010, 147.0 nm, at the opposite end, 0.0
0148, 0.0011, and 148.0 nm.
These were also within the scope of the present invention. The direction of the slow axis is
Both samples fall within ± 1 ° of the film width direction.
I was stuck. As a result of measuring the moisture content by the method described above, 1.6 was obtained.
%Met. The obtained cellulose ester film was treated with 6
0 ° C, in a 2 mol / l sodium hydroxide aqueous solution
Immersed in water for 2 minutes, washed with water, and dried at 100 ° C for 10 minutes
To obtain an alkali saponified cellulose ester film.
Was. A polarizing plate (polarizing plate 5) was produced in the same manner as in Example 1.
Then, the evaluation was performed in the same manner as in Example 1.
Little color is observed and good contrast is obtained
Was. Comparative Example 1 Substitution of an acetyl group as a cellulose ester in Example 1
Using 100 parts by mass of cellulose acetate having a degree of 2.66
Except that the thickness after drying was 10
A 0 μm comparative optical film was prepared. In the manner described above
As a result of measuring the moisture content, it was 3.5%.
Was obtained. Using this comparative optical film
Then, a polarizing plate was prepared and evaluated in the same manner as in Example 1.
Was. When a polarizing plate is subjected to long-term wet heat treatment, the polarizer and the optical
The film peels off and this optical film is
Poor thermal properties, not preferred as protective film for polarizing plate
Was obtained. A polarizing plate that has not been subjected to wet heat treatment
When the same evaluation was carried out using this, almost no coloring was observed.
I couldn't. Example 6 Degree of substitution of acetyl group 2.00, degree of substitution of propionyl group
0.80, Cellulose acetate having a viscosity average degree of polymerization of 350
100 parts by mass of toppropionate, Arylene bis (dia
(Rile phosphate) ester (1,3-phenylene)
Bis (diphenyl phosphate)) 15 parts by mass, salt
290 parts by mass of methylene chloride and 60 parts by mass of ethanol are sealed.
Put in a container and slowly raise the temperature while stirring the mixture slowly
Then, the temperature was raised to 45 ° C. over 60 minutes to dissolve. Inside the container
1.2 atm. This dope was manufactured by Azumi Filter Paper Co., Ltd.
Azumi filter paper No. 24 hours after filtration using 244
The mixture was allowed to stand, and bubbles in the dope were removed. Also, apart from this,
5 parts by mass of cellulose acetate propionate,
Bin 326 (Ciba Specialty Chemicals Co., Ltd.)
6 parts by mass, Tinuvin 109 (Chiba Specialty)
4 parts by mass of Chemicals Co., Ltd., Tinuvin 171 (H
5 parts by mass of Ba Specialty Chemicals Co., Ltd.)
And AEROSIL R972V (Nippon Aerosil)
1 part by weight of methylene chloride and 94 parts by weight of ethanol
-8 parts by mass of a mixture, and dissolve by stirring.
Prepared. UV absorption for 100 parts by weight of the above dope
2 parts by weight of the agent solution and add it to the static mixer.
After mixing more thoroughly, put it on a stainless steel belt from the die.
Casting was performed at a loop temperature of 30 ° C. and a width of 1.6 m. stainless
The temperature is brought into contact with hot water of 25 ° C from the back of the belt.
After drying for 1 minute on a controlled stainless steel belt,
Contact the cold water of 15 ° C with the back of the stainless steel belt
After holding for 15 seconds, peel off from the stainless steel belt
Was. The amount of residual solvent in the web at the time of peeling was 100% by mass.
Was. Next, the both ends of the web peeled using a tenter
Grabbed with clips, fixed clip spacing and maintained width
It dried at 120 degreeC for 10 minutes as it was. Roller transport
While drying at 130 ° C. for 10 minutes. The resulting cell
The residual solvent content in the rose ester film is 0.2% by mass.
Met. The obtained cellulose ester film was
While rolling in a 70 ° C oven, enter the oven
The roll just before the oven exit, against the roll peripheral speed just after the outlet
The peripheral speed to 1.5 times, and
In the longitudinal direction of the film). Immediately after stretching, 6
Cooled to 0 ° C, 100 μm-thick cellulose ester
A film was obtained (optical film 6). Optical film 6
Is a glass fiber reinforced resin core with a core diameter of 200 mm.
Tape in film roll shape of width 1m and length 1000m
It was wound by the tension method. At this time, warm the film edge.
Pressing the emboss ring of 200 ° C, thickness of 5μm
A soaking process was applied to prevent adhesion between the films. Profit
From the film roll to the end in the width direction of the film,
Sampling from the center and opposite end
Refractive index Nx, refractive index Ny in fast axis direction, refraction in thickness direction
The rate Nz was measured as follows, and Nx−Ny, (Nx + N
y) / 2-Nz, R ₀ Calculated respectively, the end
Then, in order, 0.00148, 0.0011, 148.0
nm, 0.00148, 0.001
1, 148.0 nm, 0.0014 at the opposite end
8, 0.0011, and 148.0 nm.
It was within the scope of the present invention. The direction of the slow axis is
For both pulls, ± 2 degrees with respect to the film length direction (film formation direction)
Was in the range. The result of the moisture content measurement
As a result, it was 1.3%. Cellulose ester obtained
The film was heated at 60 ° C with 2 mol / l sodium hydroxide
Immersed in an aqueous solution for 2 minutes, washed with water,
After drying for 10 minutes, alkali saponification
Got Lum. Hereinafter, a polarizing plate is produced in the same manner as in Example 1.
When the same evaluation was performed, almost no coloring was observed.
Was not. Example 7 In comparison with Example 3, the plasticizer was changed to ethyl phthalyl ethyl glycol.
5 parts by mass of collet, 3 parts by mass of triphenyl phosphate
15 parts by mass of tricresyl phosphate in place of
While entering rolls in an oven at 0 ° C
Roll just before the exit of the roll against the roll peripheral speed just after the mouth
Set the peripheral speed to 2.0 times, 2.0 times in the casting direction
Example 3 except that the film was stretched and the dry film thickness was changed to 100 μm.
Similarly, an optical film 7 of the present invention was obtained. Obtained
From the film roll to the edge, the center and the width of the film.
Sampling from the opposite end, measurement wavelength 550nm
, The refractive index Nx in the slow axis direction and the refractive index N in the fast axis direction
y, the refractive index Nz in the thickness direction was measured as follows, and Nx−
Ny, (Nx + Ny) / 2-Nz, R ₀ , Θ
As a result of calculation, 0.00138, 0.
0011, 138.0 nm, 0.00 in the center
138, 0.0011, 138.0 nm, opposite ends
Then, 0.00138, 0.0011, 138.0 nm
The connection between the slow axis in the film plane and the length direction (film forming direction)
The angle θ was within ± 1 ° in width. Moisture in the manner described above
As a result of measuring the ratio, it was 1.4%. Similarly, make a polarizing plate.
And evaluated in the same manner as in Example 3.
It did not fit. Example 8 Degree of substitution of acetyl group 1.60, degree of substitution of propionyl group
1.2 Cellulose acetate having a viscosity average degree of polymerization of 400
100 parts by mass of propionate, Tris trimellitic acid
(2-ethylhexyl) 10 parts by mass, methyl acetate 175
Parts by mass and 75 parts by mass of ethanol in a closed container
Gradually raise the temperature while stirring slowly, and take 60 minutes
The temperature was raised to 65 ° C. and dissolved. The pressure inside the container is 1.2 atm
Was. Azumi Filter Paper No. No. manufactured by Azumi Filter Paper Co., Ltd. 2
After filtration using No.44, the mixture was allowed to stand for 24 hours,
Bubbles were removed. Separately, the above cellulosic assay
5 parts by mass of tetrapropionate, Tinuvin 326 (Chiba)
・ Specialty Chemicals Co., Ltd. 6 parts by mass
Nubin 109 (Ciba Specialty Chemicals)
4 parts by mass, Tinuvin 171 (Ciba Specialty)
5 parts by weight of methyl acetate 9
4 parts by mass and 8 parts by mass of ethanol were mixed and dissolved by stirring.
An external absorbent solution was prepared. 100 parts by mass of the above dope
The UV absorber solution was added at a ratio of 2 parts by mass,
After thoroughly mixing with a tick mixer, the stainless steel
Cast at a dope temperature of 40 ° C and a width of 1.6m on a wrestling belt
did. Hot water at a temperature of 40 ° C from the back of the stainless steel belt
For 2 minutes on a temperature controlled stainless steel belt
After drying for 15 minutes, the surface of the stainless steel belt
After contact with cold water for 15 seconds,
Peeled from the belt. The amount of residual solvent in the web at the time of peeling is 5
It was 0% by mass. Then, using a simultaneous biaxial stretching tenter
Grab both ends of the peeled web with clips, and
Change the gap simultaneously in the width direction and the casting direction (length direction)
In this way, at 150 ° C., 1.05 times in the width direction, the casting direction (length
In the same direction). After stretching is complete,
After cooling the room temperature to 80 ° C, rollers with different peripheral speeds
The film was stretched 1.05 times in the length direction at 130 ° C. by using-.
Further dry at 130 ° C. for 10 minutes while transporting the rollers.
80 μm thick cellulose ester film (optical
Film 8) was obtained. The optical film 8 has a core diameter of 200
mm, glass fiber reinforced resin core, width 1m, length 10
Winded into a film roll of 00m by taper tension method
I wiped it. At this time, a 250 ° C temperature
Press the boss ring, apply thickness processing, and fill
To prevent close contact between the units. From the obtained film roll
From the edge in the width direction, the center and the opposite edge of the film
Sampling was performed at a measurement wavelength of 550 nm in the slow axis direction.
Refractive index Nx, refractive index Ny in fast axis direction, refraction in thickness direction
The rate Nz was measured as follows, and Nx−Ny, (Nx + N
y) / 2-Nz, R ₀ , Θ are calculated,
At the ends, 0.00173, 0.0015, 13
8.4 nm, 0.00173, 0.0
015, 138.4 nm, 0.005 at the opposite end
173, 0.0015, 138.4 nm
The angle θ between the slow axis and the length direction (film forming direction) is within the width
Was within ± 1 °. Moisture content measurement as described above
As a result, it was 1.3%. Similarly, create a polarizing plate,
When evaluation was performed in the same manner as in Example 3, coloring was observed.
Did not. Example 9 Degree of substitution of acetyl group 2.00, degree of substitution of propionyl group
0.80, Cellulose acetate having a viscosity average degree of polymerization of 350
Topropionate 100 parts by mass, 1,3-phenylenebi
(Diphenyl phosphate) 11 parts by mass, methyl chloride
290 parts by mass of ethanol and 60 parts by mass of ethanol
The mixture was gradually heated while slowly stirring,
It was heated to 45 ° C. over a minute and dissolved. 1.2 atm in the container
It became. Azumi Filter Paper N manufactured by Azumi Filter Paper Co., Ltd.
o. After filtration using 244, the mixture was allowed to stand for 24 hours,
The foam in the bottle was removed. Separately, the above-mentioned cellulo-
5 parts by mass of acetate propionate, Tinuvin 326
(Ciba Specialty Chemicals Co., Ltd.) 10 quality
94 parts by weight of methylene chloride and 8 parts by weight of ethanol
The mixture was mixed and dissolved by stirring to prepare an ultraviolet absorbent solution.

An ultraviolet absorber solution was added at a ratio of 2 parts by mass to 100 parts by mass of the above dope, and a static mixer was added.
Then, the mixture was cast from a die onto a stainless steel belt at a dope temperature of 40 ° C. and a width of 1.6 m. After contacting warm water at a temperature of 40 ° C. from the back of the stainless steel belt and drying it on a temperature-controlled stainless steel belt for 2 minutes,
Further, cold water at 15 ° C. was brought into contact with the back surface of the stainless steel belt and held for 15 seconds, and then separated from the stainless steel belt. The residual solvent amount in the web at the time of peeling was 70% by mass. Next, the both ends of the peeled web are gripped with clips using a simultaneous biaxial stretching tenter, and the intervals between the clips are simultaneously changed in the width direction and the casting direction (length direction).
1.5 times in the width direction at 1.0 ° C, 1.0 in the casting direction (length direction)
It was stretched 5 times. After the stretching is completed, the film temperature is temporarily set to 80
After cooling to 13 ° C., 13
The film was stretched 1.05 times in the length direction at 0 ° C. Further, it is dried at 130 ° C. for 10 minutes while being transported by a roller, and has a thickness of 120 μm.
m cellulose ester film (optical film 9) was obtained.

The optical film 9 was wound on a glass fiber reinforced resin core having a core diameter of 200 mm into a film roll having a width of 1 m and a length of 1000 m by a tape tension method. At this time, an emboss ring at a temperature of 250 ° C. was pressed against the end of the film, and a thickness adjusting process was performed to prevent adhesion between the films. From the obtained film roll, a sample is taken from the edge in the width direction, the center and the opposite edge of the film, and the refractive index Nx in the slow axis direction, the refractive index Ny in the fast axis direction, and the refraction in the thickness direction. The rate Nz is measured, and Nx−Ny,
When (Nx + Ny) / 2-Nz and R ₀ were calculated, 0.00148, 0.0010,
147.5 nm, 0.00148 at the center,
0.0011, 148.0 nm, at the opposite end,
0.00148, 0.0010, and 147.5 nm, all of which were within the scope of the present invention.

The direction of the slow axis was within ± 1 degree with respect to the width direction of the film for each sample. Further, the result of measurement of the moisture content by the above-mentioned method was 1.4%.

The obtained cellulose ester film was treated with 6
It was immersed in a 2 mol / l aqueous solution of sodium hydroxide at 0 ° C. for 2 minutes, washed with water, and dried at 100 ° C. for 10 minutes to obtain an alkali saponified cellulose ester film.

Polarizing plate (polarizing plate 9) in the same manner as in Example 1.
Was prepared and further evaluated in the same manner as in Example 1. As a result, almost no coloring was observed, and good contrast was obtained.

Example 10 Cellulose acetate having a degree of substitution of acetyl group of 2.00, a degree of substitution of propionyl group of 0.80, and a viscosity average degree of polymerization of 340.
100 parts by mass of topopionate, 4 parts by mass of ethylphthalylethyl glycolate, triphenyl phosphate 7
Parts by weight, 290 parts by weight of methylene chloride, and 60 parts by weight of ethanol were placed in a closed container, and the mixture was gradually heated while slowly stirring to 45 ° C. over 60 minutes to dissolve.
The pressure in the container was 1.2 atm. Azumi Filter Paper No. No. manufactured by Azumi Filter Paper Co., Ltd. After filtration using 244, the mixture was allowed to stand for 24 hours to remove bubbles in the dope. Separately from the above, cellulose acetate propionate 5
10 parts by mass of Tinuvin 326 (manufactured by Ciba Specialty Chemicals Co., Ltd.) was mixed with 94 parts by mass of methylene chloride and 8 parts by mass of ethanol and dissolved by stirring to prepare an ultraviolet absorber solution.

An ultraviolet absorber solution was added at a ratio of 2 parts by mass to 100 parts by mass of the above-mentioned dope, and a static mixer was added.
Then, the mixture was cast from a die onto a stainless steel belt at a dope temperature of 40 ° C. and a width of 1.6 m. After contacting warm water at a temperature of 40 ° C. from the back of the stainless steel belt and drying it on a stainless steel belt whose temperature is controlled for 2 minutes, further contacting cold water of 15 ° C. with the back of the stainless steel belt and holding for 15 seconds, Peeled off the belt. Both ends of the peeled web were gripped with clips using a tenter and stretched 1.05 times in the width direction at 120 ° C. Further drying at 130 ° C. for 10 minutes while transporting the roller,
Width 1 on glass fiber reinforced resin core with core diameter 200mm
The film was wound into a film roll having a length of 1000 m and a length of 1000 m by a tape tension method. At this time, the temperature 2
An embossing ring at 50 ° C. was pressed against the film to perform a thickness processing to prevent the films from sticking to each other. The amount of residual solvent in the obtained film was about 1% by mass.

The obtained cellulose ester film was
While the roll is conveyed in an oven at 160 ° C., the peripheral speed of the roll immediately before the outlet of the oven is 1.5 times the peripheral speed of the roll immediately after the entrance of the oven. Then, it was stretched 1.5 times in the casting direction (lengthwise direction of the film). After stretching, the film was immediately cooled to 60 ° C. to obtain a cellulose ester film having a thickness of 116 μm (optical film 10).

A film was sampled from the obtained film roll, and a three-dimensional refractive index was measured at a wavelength of 590 nm. The refractive index Nx in the slow axis direction and the refractive index N in the fast axis direction were measured.
y, the refractive index Nz in the thickness direction was measured, and the following results were obtained.

[0089]

[Table 1]

R ₄₅₀ / R ₅₉₀ was 0.88 and R ₆₅₀ / R ₅₉₀ was 1.03.

The direction of the slow axis was within ± 1 degree with respect to the lengthwise direction of the film. As a result of measuring the moisture content by the method described above, it was 1.5%.

The obtained cellulose ester film was treated with 6
It was immersed in a 2 mol / l aqueous solution of sodium hydroxide at 0 ° C. for 2 minutes, washed with water, and dried at 100 ° C. for 10 minutes to obtain an alkali saponified cellulose ester film.

In the same manner as in Example 1, a polarizing plate (polarizing plate 1
0) was prepared and further evaluated in the same manner as in Example 1. As a result, almost no coloring was observed, and good contrast was obtained.

Further, a polarizing plate was prepared in the same manner as in Example 1, except that the protective film 1 prepared in Example 1 was used on both sides. One surface of this polarizing plate was completely saponified with the optical film 10 having been subjected to the alkali saponification treatment by polyvinyl alcohol 5%.
Using the aqueous solution as an adhesive, a laminated polarizing plate 11 was obtained so that the angle between the polarizing axis of the polarizing plate and the slow axis of the optical film 10 was 45 degrees. Evaluation was performed in the same manner as in Example 1. As a result, almost no coloring was observed, and good contrast was obtained. In particular, in an optical film using a low-volatile plasticizer having a vapor pressure of less than 1333 Pa at 200 ° C., the transport roll in the stretching step and the subsequent drying step is less contaminated, and has excellent surface quality without dents and scratches. An optical film having excellent flatness was obtained.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G02F 1/1335 510 G02F 1/1335 510 1/13363 1/13363 // B29K 1:00 B29K 1:00 B29L 7:00 B29L 7:00 F-term (reference) 2H049 BA02 BA06 BA27 BB12 BB43 BB49 BC01 BC03 BC22 2H091 FA08X FA08Z FA11X FA11Z FB02 FB11 FC09 GA16 KA02 LA04 LA06 4F071 AA09 AC15 AE04 AF31 AH19 A02BC03A01A03 BC01 AR11 QC05 QD01 QD02 QD25 QG01 QG18 4J002 AC021 EH146 EU177 EW046 FD010 FD026 FD057 FD070 GP00

Claims (24)

[Claims] When a substituent having an acyl group having 2 to 4 carbon atoms as a substituent, a degree of substitution of an acetyl group as A, and a degree of substitution of a propionyl group or a butyryl group as B, the following formulas (I) and ( II) An optical film containing a cellulose ester that satisfies the formula at the same time, wherein the refractive index Nx in the slow axis direction and the refractive index Ny in the fast axis direction at a wavelength of 590 nm satisfy the following formula (III). An optical film characterized by satisfying. (I) 2.0 ≦ A + B ≦ 3.0 (II) A <2.4 (III) 0.0005 ≦ Nx−Ny ≦ 0.0050 2. A compound having an acyl group having 2 to 4 carbon atoms as a substituent, wherein the degree of substitution of an acetyl group is A and the degree of substitution of a propionyl group or a butyryl group is B, the following (IV)
An optical film containing a cellulose ester that satisfies the formulas (V) and (V) at the same time, and further has an in-plane refractive index Nx and a fast axis refractive index Ny at a wavelength of 590 nm of the following formula (VI): An optical film characterized by satisfying the formula: (IV) 2.4 ≦ A + B ≦ 2.8 (V) 1.4 ≦ A ≦ 2.0 (VI) 0.0010 ≦ Nx−Ny ≦ 0.0030 3. The refractive index Nx in the slow axis direction, the refractive index Ny in the fast axis direction, and the refractive index Nz in the thickness direction at a wavelength of 590 nm satisfy the following formula (VII). The optical film according to any one of claims 1 and 2. (VII) 0.0005 ≦ (Nx + Ny) / 2−Nz ≦
0.002 4. The optical film according to claim 1, wherein the viscosity average polymerization degree of the cellulose ester is from 250 to 700. 5. The optical film according to claim 1, wherein the film has a thickness of 20 to 200 μm. 6. A vapor pressure at 200 ° C. of 1333 Pa
The optical film according to any one of claims 1 to 5, comprising the following plasticizer. 7. The optical film according to claim 1, further comprising an ultraviolet absorber having a distribution coefficient of 9.2 or more. 8. A polarizing plate, wherein the optical film according to claim 1 is adhered to at least one surface of a polarizer or a polarizing plate. 9. A reflective polarizing plate comprising the optical film according to claim 1. 10. The polarizing plate according to claim 8, and / or
A display device using the optical film according to any one of claims 1 to 7. 11. Assuming that the compound has an acyl group having 2 to 4 carbon atoms as a substituent, the degree of substitution of an acetyl group is A, and the degree of substitution of a propionyl group or a butyryl group is B, the following (VI)
A film obtained by rolling an optical film containing a cellulose ester satisfying the formulas (II) and (IX) simultaneously and having an in-plane retardation (R ₀ ) at a wavelength of 590 nm of not less than 20 nm and not more than 400 nm. Roll, wherein the slow axis direction of the optical film is ± 15 degrees with respect to the length direction of the film roll or ± 15 degrees with respect to the width direction of the film roll. Optical film roll. (VIII) 2.0 ≦ A + B ≦ 3.0 (IX) A <2.4 12. When X has an acyl group having 2 to 4 carbon atoms as a substituent, the degree of substitution of an acetyl group is A, and the degree of substitution of a propionyl group or a butyryl group is B, the following (X)
A film obtained by rolling an optical film containing a cellulose ester satisfying the formulas (XI) and (XI) and having an in-plane retardation (R ₀ ) at a wavelength of 590 nm of not less than 100 nm and not more than 400 nm. Roll, wherein the slow axis direction of the optical film is ± 15 degrees with respect to the length direction of the film roll or ± 15 degrees with respect to the width direction of the film roll. Optical film roll. (X) 2.4 ≦ A + B ≦ 2.8 (XI) 1.4 ≦ A ≦ 2.0 13. When X has an acyl group having 2 to 4 carbon atoms as a substituent, the degree of substitution of an acetyl group is A, and the degree of substitution of a propionyl group or a butyryl group is B, the following (XI
A method for producing an optical film in which a solution obtained by dissolving cellulose ester satisfying the formulas (I) and (XIII) simultaneously in an organic solvent is cast on a support and the solvent is evaporated to form a cellulose ester film. The method for producing an optical film, wherein the cellulose ester film is stretched so as to satisfy the following formula (XIV). (XII) 2.0 ≦ A + B ≦ 3.0 (XIII) A <2.4 (XIV) 0.0005 ≦ Nx−Ny ≦ 0.0050 14. When an acyl group having 2 to 4 carbon atoms is used as a substituent, the degree of substitution of an acetyl group is A, and the degree of substitution of a propionyl group or a butyryl group is B, the following (X
A method for producing an optical film in which a solution obtained by dissolving a cellulose ester satisfying the formulas (V) and (XVI) simultaneously in an organic solvent is cast on a support and the solvent is evaporated to form a cellulose ester film. The method for producing an optical film, wherein the cellulose ester film is stretched so as to satisfy the following formula (XVII). (XV) 2.4 ≦ A + B ≦ 2.8 (XVI) 1.4 ≦ A ≦ 2.0 (XVII) 0.0010 ≦ Nx−Ny ≦ 0.0030 15. The cellulose ester solution is a cellulose ester solution.
14. A cellulose ester solution having a sester concentration of 20% by mass or more and 35% by mass or less.
15. The method for producing an optical film according to any one of items 14 to 14. 16. The method according to claim 1, wherein the solvent is evaporated to form a cellulose ester film, and when the amount of the residual solvent in the cellulose ester film is in the range of 10 to 100% by mass, the temperature is 15 to 160. The film is stretched in at least one direction at 1.2 ° C. by 1.2 to 4.0 times.
16. The method for producing an optical film according to any one of claims 15 to 15. 17. The method for producing an optical film according to claim 12, wherein the film is stretched in biaxial directions orthogonal to each other. 18. The method according to claim 13, wherein the stretching ratios in biaxial directions orthogonal to each other are 1.2 to 4.0 times and 1.0 to 1.2 times, respectively. Item 13. The method for producing an optical film according to item 9. 19. The method for producing an optical film according to claim 13, wherein the organic solvent contains at least one organic solvent selected from methyl acetate and acetone. 20. The method according to claim 1, wherein the amount of the residual solvent is less than 10% by mass.
The method for producing an optical film according to any one of claims 13 to 19, wherein the heat treatment is performed at a temperature of 30 to 200C for 10 seconds or more. 21. A film cooled to 100 ° C. or less and having a residual solvent content of less than 10% by mass is heat-treated again at a temperature of 130 to 200 ° C. for 10 seconds or more.
20. The method for producing an optical film according to any one of claims 19 to 19. 22. A cellulose ester solution at 200 ° C.
The method for producing an optical film according to claim 13, further comprising a plasticizer having a vapor pressure of 1333 Pa or less. 23. Assuming that an acyl group having 2 to 4 carbon atoms is a substituent, the degree of substitution of an acetyl group is A, and the degree of substitution of a propionyl group or a butyryl group is B, the following (XV
A solution containing at least a cellulose ester satisfying the formulas III) and (XIX) simultaneously, a plasticizer having a vapor pressure at 200 ° C. of not more than 1333 Pa, and an organic solvent is cast on a support, peeled off, and the solvent is removed. Was evaporated to form a cellulose ester film, and the residual solvent amount was 10
A method for producing an optical film, comprising stretching at a temperature of from 130 to 200 ° C. so as to satisfy the following formula (XX) when the amount is less than mass%. (XVIII) 2.0 ≦ A + B ≦ 3.0 (XIX) A <2.4 (XX) 0.0005 ≦ Nx−Ny ≦ 0.005
0 24. When the compound has an acyl group having 2 to 4 carbon atoms as a substituent, the degree of substitution of an acetyl group is A, and the degree of substitution of a propionyl group or a butyryl group is B, the following (XX)
A solution containing at least a cellulose ester satisfying the formulas (I) and (XXII) at the same time, a plasticizer having a vapor pressure at 200 ° C. of 1333 Pa or less, and an organic solvent is cast on a support, peeled off, and the solvent is removed. Is evaporated to form a cellulose ester film, and when the residual solvent amount is less than 2% by mass, at a temperature of 130 to 200 ° C., the following (XX)
III) A method for producing an optical film, wherein the film is stretched so as to satisfy the formula. (XXI) 2.0 ≦ A + B ≦ 2.8 (XXII) 1.4 ≦ A ≦ 2.0 (XXIII) 0.0010 ≦ Nx−Ny ≦ 0.0
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