JP2002363420A - Resin composition, optical film, polarizing plate and display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a resin composition excellent in optical absorption, little in bleeding-out, free from coloring, excellent in transparency, having sufficient ultraviolet absorbing performance and excellent in long-term weather resistance. SOLUTION: The resin composition contains a synthetic resin and an ultraviolet absorbing polymer contains a unit formed from an ultraviolet absorbing monomer expressed by formula (I) [wherein, R1 is a (substituted) normal or branched alkyl, or cycloalkyl; R2 and R2 are each H, a halogen or a substituent; Alk is a (substituted) normal or branched alkylene or cycloalkylene; L1 is a divalent bonding group; (n) is 0 or 1; and P is a polymerizing group including an ethylenic unsaturated functional group].

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a resin composition, an optical film, a polarizing plate, and a display device. In particular, the present invention relates to a resin composition containing a specific ultraviolet absorbing polymer, an optical film, a polarizing plate, and a display device using the same.
Further, the present invention relates to a resin composition containing a cellulosic resin composition and a specific ultraviolet absorbing polymer, an optical film, a polarizing plate, and a display device using the same. Among them, various functional films such as a protective film for a polarizing plate used for a liquid crystal display device, a retardation film, a viewing angle widening film, an antireflection film used for a plasma display,
Alternatively, the present invention relates to an optical film composed of the composition that can be used for various functional films used in an organic EL display and the like.

[0002]

2. Description of the Related Art Since a transparent resin is lighter in weight than an inorganic glass, it is used in a very large number of optical fields such as optical lenses, prisms, optical fibers and various optical films.

[0003] However, in general, when a transparent resin is exposed to light including ultraviolet rays, there is a problem that decomposition is promoted, strength is reduced, and transparency is reduced due to discoloration.

For this reason, in an optical film requiring transparency, an ultraviolet absorbent such as a benzotriazole compound or a benzophenone compound, a cyanoacrylate compound or a salicylic acid compound is mixed in advance in order to prevent deterioration due to ultraviolet rays. I was

However, these conventional ultraviolet absorbers are low-molecular-weight compounds and are liable to bleed out, precipitate on a film, increase haze and decrease transparency, and furthermore, heat. There are various problems such as a decrease in the amount of addition due to evaporation during processing, a decrease in ultraviolet absorption performance, and contamination of the production process.

[0006] Therefore, attempts have been made to eliminate these disadvantages by introducing a polymerizable substituent into the ultraviolet absorber and homopolymerizing or copolymerizing it to form an ultraviolet absorbing polymer. I have. For example, JP-A-60-38411, JP-A-62-181360, JP-A-3-281885, and 7-90184
The technique described in Japanese Patent Application Laid-Open Publication No. H10-26095 has been proposed. JP-A-6-148430 describes an example in which a protective film for a polarizing plate contains an ultraviolet absorbing polymer as an optical film.

[0007] These proposed UV-absorbing polymers are certainly effective to some extent in preventing bleed-out, precipitation and evaporation.

[0008] However, the ultraviolet absorbing ability is not enough,
In order to obtain the desired ultraviolet absorbing performance, a large amount of addition is necessary, and when these ultraviolet absorbing polymers are added in a large amount, the compatibility with the resin is not sufficient, and sufficient transparency cannot be obtained, or the film cannot be obtained. It has been difficult to put it into practical use as an optical film because of problems such as coloring itself yellow or a decrease in ultraviolet absorbing ability when stored for a long time.

By the way, as properties required for an optical film, it is required that ultraviolet light having a wavelength of 380 nm or less be sufficiently blocked and light having a wavelength of 400 nm or more be sufficiently transmitted. In order to achieve such properties, the 4'-hydroxyphenylbenzotriazole-based UV absorber 4 '
An ultraviolet absorber in which an alkoxy group is substituted at the position is preferable. A polymerized ultraviolet absorbent in which an alkoxy group is substituted at the 4'-position of a 2'-hydroxyphenylbenzotriazole-based ultraviolet absorbent is disclosed in JP-A-9-3.
No. 4057, No. 9-5929, and No. 8-179264. These publications describe the monomer represented by the general formula (I) of the present invention.

However, the compounds disclosed in the above publications are typically compounds having a hydrogen atom at the 5'-position or having a substituent at the 5- or 6-position. No suggestion is made regarding the compatibility between the ultraviolet absorbing polymer containing the unit formed from the indicated monomer and the synthetic resin.

Further, the ultraviolet absorbing polymer specifically described in these publications is a polymer latex produced by emulsion polymerization, and has poor compatibility with synthetic resins, and particularly has poor compatibility with cellulosic resins. Therefore, it cannot be used as an optical film.

[0012]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above problems, and in particular, it has excellent spectral absorption, little bleed-out, no coloring, and excellent transparency. Further, it is an object of the present invention to provide a resin composition having a sufficient ultraviolet absorbing ability and excellent in long-term weather resistance.

Another object of the present invention is to provide an optical film using the resin composition, and a polarizing plate and a display device provided with the optical film.

[0014]

Means for Solving the Problems The present inventors have made intensive studies on an ultraviolet absorbing polymer and an optical film containing the same, which can solve the above-mentioned conventional problems.
The present invention has been found that an optical film having excellent transparency and excellent long-term weather resistance can be obtained by a resin composition containing an ultraviolet absorbing polymer having a specific structure and composition, without causing evaporation, bleed-out, and precipitation. Was completed.

That is, the present invention provides a resin composition containing a synthetic resin and a UV-absorbing polymer containing a unit formed from a UV-absorbing monomer represented by the following general formula (I). They found that the problem was solved.

The present invention has been accomplished based on such findings, and the above-mentioned problems include a unit formed from a synthetic resin and an ultraviolet absorbing monomer represented by the following general formula (I). The problem is solved by a resin composition characterized by containing an ultraviolet absorbing polymer.

Formula (I) (In the general formula (I), R ₁ represents a linear or branched alkyl group or a cycloalkyl group which may have a substituent, and R ₂ and R ₃ represent a hydrogen atom, a halogen atom or a substituent. Alk represents a linear or branched alkylene group or a cycloalkylene group which may have a substituent, L ₁ represents a divalent linking group, n represents 0 or 1, and P represents It represents a polymerizable group containing an ethylenically unsaturated functional group.) In order to further solve the above-mentioned problems, the above-mentioned general formula (I)
The content of the unit formed from the ultraviolet absorbing monomer represented by the formula is 1% by mass or more of the ultraviolet absorbing polymer,
What is below the mass% is preferred. Further, it is preferable that the ultraviolet absorbing polymer is a copolymer of the ultraviolet absorbing monomer represented by the general formula (I) and a monomer copolymerizable with the ultraviolet absorbing monomer. Above all, a monomer copolymerizable with the ultraviolet absorbing monomer represented by the general formula (I) is a hydrophilic ethylenically unsaturated monomer and / or
Alternatively, those which are ethylenically unsaturated monomers having no hydrophilic group in the molecule are preferable. In particular, as the hydrophilic ethylenically unsaturated monomer which is a comonomer, a monomer using a (meth) acrylate-based monomer having a hydroxyl group or a carboxyl group in a molecule is preferable. The UV-absorbing polymer is preferably obtained by a solution polymerization method. The UV-absorbing polymer preferably has a weight average molecular weight of 2,000 to 20,000. As the synthetic resin, it is preferable to use a thermoplastic resin, especially a cellulose ester. For example, by introducing a hydrophilic substituent into a part of the constituent components of the ultraviolet absorbing polymer used in the present invention, or by increasing the weight average molecular weight of the ultraviolet absorbing polymer from 2,000 to 20,000.
In the range, the compatibility is further improved, the spectral absorption is more excellent, the bleed-out is less, there is no coloring, the transparency is excellent, and the ultraviolet absorbing ability is sufficient, and the long-term weather resistance is excellent. An optical film is obtained.

Further, the above-mentioned object is solved by an optical film characterized by being constituted by using the above resin composition.

Further, the above-mentioned object is solved by a polarizing plate comprising the above-mentioned optical film.

The above-mentioned object is solved by a display device comprising the above-mentioned optical film.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION The resin composition of the present invention contains a synthetic resin and an ultraviolet absorbing polymer containing a unit formed from the ultraviolet absorbing monomer represented by the above general formula (I).

The content of the unit formed from the ultraviolet absorbing monomer represented by the general formula (I) is 1% by mass or more and 60% by mass or less of the ultraviolet absorbing polymer. or,
The ultraviolet absorbing polymer is a copolymer of an ultraviolet absorbing monomer represented by the general formula (I) and a monomer copolymerizable with the ultraviolet absorbing monomer. Above all, a monomer copolymerizable with the ultraviolet absorbing monomer represented by the general formula (I) is a hydrophilic ethylenically unsaturated monomer and / or
Alternatively, it is an ethylenically unsaturated monomer having no hydrophilic group in the molecule. In particular, the hydrophilic ethylenically unsaturated monomer that is a comonomer is a (meth) acrylate-based monomer having a hydroxyl group or a carboxyl group in the molecule. The ultraviolet absorbing polymer is obtained, in particular, by a solution polymerization method. The weight average molecular weight of the ultraviolet absorbing polymer is 2,000 or more and 20,000 or less. The synthetic resin is a thermoplastic resin, especially a cellulose ester.

The optical film of the present invention is constituted by using the above resin composition.

The polarizing plate of the present invention comprises the above optical film.

A display device according to the present invention includes the above optical film.

The details will be described below.

[Ultraviolet absorbing monomer] In the present invention, an ultraviolet absorbing monomer represented by the following general formula (I) is particularly used.

Formula (I) (In the general formula (I), R ₁ represents a linear or branched alkyl group or a cycloalkyl group which may have a substituent, and R ₂ and R ₃ represent a hydrogen atom, a halogen atom or a substituent. Alk represents a linear or branched alkylene group or a cycloalkylene group which may have a substituent, L ₁ represents a divalent linking group, n represents 0 or 1, and P represents This represents a polymerizable group containing an ethylenically unsaturated functional group.) Specific examples of the group represented by R ₁ include a linear alkyl group such as a methyl group, an ethyl group, and an n-hexyl group, or
Examples include a branched alkyl group such as an i-propyl group and a t-butyl group, and a cycloalkyl group such as a cyclopentyl group and a cyclohexyl group. These groups may further have a substituent. Incidentally, R ₁ is preferably a straight-chain alkyl group having 1 to 12 carbon atoms.

R ₂ and R ₃ are a hydrogen atom or a halogen atom or any substituent. R ₂ is preferably a hydrogen atom, a linear or branched alkyl group which may have a substituent, or a cycloalkyl group, and R ₃ is preferably a hydrogen atom or a substituent. It may be a linear or branched alkyl group, a cycloalkyl group, or a hydroxy group.

The group represented by Alk is preferably
It is an alkylene group having 2 to 10 carbon atoms, and specific examples include an ethylene group, a propylene group, and a butylene group. Particularly, a propylene group and a butylene group are preferable in terms of absorption wavelength, and an ethylene group is preferable in terms of ease of synthesis. Is preferred.

L ₁ represents a divalent linking group interposed between a group represented by Alk and a polymerizable group containing an ethylenically unsaturated functional group represented by P, wherein (n = 1) And (n = 0) is not required.

P represents a polymerizable group containing an ethylenically unsaturated functional group, and specifically, a substituent derived from an α, β-unsaturated carboxylic acid such as a methacryloyloxy group, an acryloyloxy group, and a crotonoyloxy group. , A vinylbenzyloxy group, a vinyloxy group, a vinyloxycarbonyl group and the like.

Preferred UV absorbing monomers used in the present invention are shown below. Note that the present invention is not limited to these. [Ultraviolet absorbing polymer] [Ethylenically unsaturated monomer having no hydrophilic group in the molecule copolymerizable with the ultraviolet absorbing monomer] Examples of the ethylenically unsaturated monomer copolymerizable with the ultraviolet absorbing monomer include: Methacrylic acid ester derivatives (methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, octyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate) or acrylic acid Ester derivatives (methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, i-butyl acrylate,
T-butyl acrylate, octyl acrylate, cyclohexyl acrylate, benzyl acrylate, etc., alkyl vinyl ether (methyl vinyl ether, ethyl vinyl ether, butyl vinyl ether, etc.), alkyl vinyl ester (vinyl formate, vinyl acetate, vinyl butyrate, vinyl caproate) , Vinyl stearate, etc.), acrylonitrile, vinyl chloride, styrene and the like.

[Hydrophilic ethylenically unsaturated monomer copolymerizable with ultraviolet absorbing monomer] The hydrophilic ethylenically unsaturated monomer copolymerizable with ultraviolet absorbing monomer is hydrophilic and polymerizable in the molecule. It is not particularly limited as long as it has an unsaturated double bond, for example, an unsaturated carboxylic acid such as acrylic acid or methacrylic acid, or an acrylic acid or methacrylic ester having a hydroxyl group or an ether bond (for example, methacrylic acid 2-hydroxyethyl, 2-hydroxypropyl methacrylate,
Tetrahydrofurfuryl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2,
3-dihydroxy-2-methylpropyl methacrylate, tetrahydrofurfuryl acrylate, 2-ethoxyethyl acrylate, diethylene glycol ethoxylate acrylate, 3-methoxybutyl acrylate), acrylamide, N, N-dimethyl (meth) acrylamide (N-substituted) (meth) acrylamide, N-vinylpyrrolidone, N-
And vinyl oxazolidone.

As the hydrophilic ethylenically unsaturated monomer, a (meth) acrylate having a hydroxyl group or a carboxyl group in the molecule is preferable. 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxyethyl acrylate 2-hydroxypropyl acrylate is particularly preferred.

[Composition ratio of ultraviolet absorbing polymer] Use of the above ultraviolet absorbing monomer and hydrophilic ethylenically unsaturated monomer copolymerizable therewith or ethylenically unsaturated monomer having no hydrophilic group in the molecule. The ratio is selected in consideration of the compatibility between the obtained ultraviolet absorbing copolymer and the transparent resin, and the effect on the transparency and mechanical strength of the optical film.

The content of the ultraviolet absorbing monomer is 1% by mass.
If the ultraviolet absorbing polymer is less than the above, a large amount of the polymer must be added to the synthetic resin, and the transparency tends to decrease due to an increase in haze or precipitation, and the film strength tends to decrease.

When the content of the UV-absorbing monomer is more than 60% by mass, the compatibility with the synthetic resin is remarkably reduced, so that it is difficult to produce a transparent optical film. Further, the solubility in a solvent is reduced, and the workability in forming a film is poor.

Preferably, in the ultraviolet absorbing copolymer,
It is preferable that the ultraviolet absorbing monomer is contained in an amount of 10% by mass or more and 50% by mass or less, more preferably 30% by mass or more and 50% by mass or less.

It is preferable that the hydrophilic ethylenically unsaturated monomer is contained in the ultraviolet absorbing copolymer in an amount of 0.1 to 50% by mass. If it is 0.1% by mass or less, the effect of improving the compatibility by the hydrophilic ethylenically unsaturated monomer is small, and if it is more than 50% by mass, it becomes difficult to isolate and purify the copolymer. A more preferred content of the hydrophilic ethylenically unsaturated monomer is 1% by mass or more and 20% by mass or less.

When the UV-absorbing monomer itself is substituted with a hydrophilic group, the total content of the hydrophilic UV-absorbing monomer and the hydrophilic ethylenically unsaturated monomer is preferably within the above range.

In order to satisfy the preferable contents of the ultraviolet absorbing monomer and the hydrophilic monomer, it is preferable to copolymerize an ethylenically unsaturated monomer having no hydrophilic group in the molecule in addition to both.

The UV-absorbing monomer and the (non) hydrophilic ethylenically unsaturated monomer may be copolymerized by mixing two or more kinds.

[Molecular Weight of Ultraviolet Absorbing Polymer] The weight average molecular weight of the ultraviolet absorbing copolymer used in the present invention is 2
It is preferably from 000 to 20,000, more preferably from 7000 to 15,000. When the weight average molecular weight is less than 2,000, bleeding to the film surface tends to occur, and coloring over time has been observed. On the other hand, if it is larger than 20,000, the compatibility with the resin tends to deteriorate, which is not preferable for use as an optical film.

[Polymerization method] The polymerization method of the ultraviolet absorbing copolymer of the present invention is not particularly limited. For example, conventionally known methods can be widely used, and examples thereof include radical polymerization, anionic polymerization, and cationic polymerization. Examples of the initiator for the radical polymerization method include azo compounds and peroxides, and azobisisobutyronitrile (AI
BN), azobisisobutyric acid diester derivatives, benzoyl peroxide and the like. The polymerization solvent is not particularly limited, for example, aromatic hydrocarbon solvents such as toluene and chlorobenzene, halogenated hydrocarbon solvents such as dichloroethane and chloroform, ether solvents such as tetrahydrofuran and dioxane, amide solvents such as dimethylformamide, Alcohol solvents such as methanol, methyl acetate, ester solvents such as ethyl acetate, acetone, cyclohexanone, ketone solvents such as methyl ethyl ketone,
A water solvent and the like can be mentioned. Depending on the selection of the solvent, solution polymerization in which polymerization is performed in a homogeneous system, precipitation polymerization in which the formed polymer precipitates, and emulsion polymerization in which micelles are formed can be performed. However, ultraviolet absorbing latex obtained by emulsion polymerization is not suitable for optical film applications.

The weight average molecular weight of the ultraviolet absorbing copolymer of the present invention can be adjusted by a known molecular weight controlling method. Examples of such a molecular weight adjusting method include a method of adding a chain transfer agent such as carbon tetrachloride, lauryl mercaptan, and octyl thioglycolate.
The polymerization temperature is usually from room temperature to 130 ° C, preferably from 50 ° C to 100 ° C.

[Synthetic Resin] In the present invention, the synthetic resin is not particularly limited, and conventionally known synthetic resins can be used. However, a thermoplastic resin is preferable in consideration of the ease of adding the ultraviolet absorbing polymer.

Examples of the thermoplastic resin include polyvinyl chloride, polyvinylidene chloride, polyolefin, alicyclic olefin resin, polycarbonate, polystyrene, acrylic resin, methacrylic resin, polyamide, polyester, acrylonitrile-butadiene-styrene (AB
S) Resin, thermoplastic polyurethane resin, vinyl chloride-vinylidene chloride-acrylonitrile copolymer, acrylonitrile-styrene (AS) resin, vinyl acetate resin, polyphenylene ether, polyether sulfone, polyether ketone, liquid crystal plastic, and cellulose ester type Resins can be mentioned.

The resin for the optical film is preferably a transparent resin, such as a cellulose ester resin (eg, cellulose acetate, cellulose propionate, cellulose butyrate), or an alicyclic olefin resin (eg, APEL, ZEON).
EX, ARTON, etc.), polycarbonate, alicyclic acrylic resin (for example, Optrez OZ series, etc.), and polyester having fluorene in a side chain (O-PET, etc.) are preferable. Particularly, a cellulose ester resin is preferable.

The ultraviolet absorbing polymer used in the present invention is preferably mixed with these synthetic resins at a ratio of 0.01 to 40% by weight, more preferably 0.5 to 40% by weight.
It is preferable to mix at a ratio of 10 wt%. In the case of optical film applications, there is no particular limitation as long as the haze when the optical film is formed is 0.5 or less, but preferably the haze is 0.2 or less. More preferably, the haze when forming the optical film is 0.2 or less, and
The transmittance at 380 nm is 10% or less.

When the ultraviolet absorbing polymer of the present invention is mixed with a synthetic resin, it can be used together with other low molecular weight compounds, high molecular weight compounds, inorganic compounds and the like, if necessary. For example, the ultraviolet absorbing polymer of the present invention,
It is also a preferred embodiment to mix another low molecular ultraviolet absorber with the transparent resin at the same time. Similarly, simultaneous addition of additives such as an antioxidant, a plasticizer, and a flame retardant is one of the preferable embodiments.

[Cellulose Ester Film] A method for producing a cellulose ester film according to a preferred embodiment of the present invention will be described.

The preferred film forming step used in the method for producing a cellulose ester film of the present invention comprises the following dissolving step, casting step, solvent evaporation step, peeling step, drying step and winding step. Hereinafter, each step will be described.

[Dissolution Step] In the present invention, the cellulose ester solution is referred to as cellulose ester dope or simply dope. The dissolving step is a step of dissolving the flakes in cellulose ester flakes in a dissolving vessel in an organic solvent mainly composed of a good solvent described below while stirring to form a dope.

In the present invention, the solid concentration in the dope is 15
It is preferable to adjust the amount to not less than 18% by mass.
% By mass is preferably used.

If the solid content concentration in the dope is too high, the viscosity of the dope becomes too high, and sharkskin or the like may be formed during casting to deteriorate the film flatness. Therefore, the content is preferably 35% by mass or less. .

The viscosity of the dope is preferably adjusted within the range of 10 to 50 Pa · s.

The dissolution may be carried out at normal pressure, at a temperature lower than the boiling point of a preferable organic solvent (ie, a good solvent), at a pressure higher than the boiling point of the good solvent, at a pressure higher than the boiling point of the good solvent, or at a cooling dissolution method. There are various dissolving methods and the like, such as a method at a high pressure. As a method of dissolving at a temperature not lower than the boiling point of a good solvent and applying a pressure that does not boil, 0.14 to 40.4 to 120 ° C.
By applying a pressure of 1.50 MPa, foaming can be suppressed and dissolution can be achieved in a short time.

As the cellulose ester used in the present invention, a lower fatty acid ester of cellulose is preferably used.

The lower fatty acid in the lower fatty acid ester of cellulose ester means a fatty acid having 6 or less carbon atoms, for example, cellulose acetate, cellulose propionate, cellulose butyrate, and the like.
Examples of mixed fatty acid esters such as cellulose acetate propionate and cellulose acetate butyrate described in U.S. Pat. Nos. 0-45804 and 8-231762 and U.S. Pat. No. 2,319,052 are examples of lower fatty acid esters of cellulose. It is listed as.

The degree of substitution of the acyl group of the cellulose ester can be measured according to ASTM-D-817-96.

Among the above fatty acids, cellulose acetate and cellulose acetate propionate are preferably used. In the case of the cellulose ester film of the present invention, from the viewpoint of film strength, the polymerization degree is particularly preferably from 250 to 250.
400 are preferably used.

The cellulose ester film of the present invention is preferably a cellulose ester having a total degree of substitution of 2.5 to 3.0, and particularly preferably a cellulose ester having a total degree of substitution of 2.55 to 2.85. When the total substitution degree is 2.55 or more, the mechanical strength of the film containing the compound represented by the general formula (I) of the present invention increases, and when the total substitution degree is 2.85 or less, the solubility of the cellulose ester is improved,
It is more preferable because generation of foreign matter is reduced.

In the case of cellulose acetate propionate, the degree of acetyl group substitution is X and the degree of propionyl group substitution is Y
In this case, those in the range of 2.55 ≦ X + Y ≦ 2.85 1.5 ≦ X ≦ 2.4 are preferably used.

As the cellulose ester, a cellulose ester synthesized from cotton linter, a cellulose ester synthesized from wood pulp, and a cellulose ester synthesized from other raw materials can be used alone or in combination.

The solvent used in preparing the dope is not particularly limited as long as it is a solvent capable of dissolving the cellulose ester, but a solvent that cannot be dissolved alone can be dissolved by mixing with another solvent. Anything that can be used can be used. In general, a mixed solvent composed of a poor solvent of methylene chloride and a cellulose ester, which is a good solvent, is used.
Those containing 30 to 30% by mass are preferably used.

Other good solvents which can be used include, for example, methylene chloride, methyl acetate, ethyl acetate, amyl acetate, acetone, tetrahydrofuran, 1,3-dioxane, 1,4-dioxane, cyclohexanone, ethyl formate, 2,2 , 2-trifluoroethanol, 2,
2,3,3-tetrafluoro-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, nitroethane and the like, and organic halogen compounds such as methylene chloride, dioxane derivatives, methyl acetate, ethyl acetate, acetone and the like are preferable organic solvents (that is, good solvents).
The use of methyl acetate is particularly preferred because the resulting film has less curl.

Examples of poor solvents for cellulose esters include methanol, ethanol, n-propanol and is
Alcohols having 1 to 8 carbon atoms such as o-propanol, n-butanol, sec-butanol, tert-butanol, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, propyl acetate, monochlorobenzene,
Examples thereof include benzene, cyclohexane, tetrahydrofuran, methyl cellosolve, and ethylene glycol monomethyl ether. These poor solvents can be used alone or in an appropriate combination of two or more.

In the production of the cellulose ester film of the present invention, it is preferable to use a cooling dissolution method when dissolving the cellulose ester. As a cooling dissolution method,
For example, JP-A-9-95538 and JP-A-9-95544,
The method described in JP-A-9-95557 can be used. Also, the high-pressure dissolution method described in JP-A-11-21379 can be preferably used.

After dissolution, cellulose ester solution (dope)
Is preferably filtered through a filter medium, defoamed and sent to the next step by a pump.At that time, in the dope, a plasticizer, an antioxidant, an ultraviolet absorber, a dye, fine particles and the like are preferably added. .

These additives may be added together with the cellulose ester and the solvent when preparing the cellulose ester solution, or during or after the solution preparation.

A plasticizer can be added to the cellulose ester film of the present invention. These can be used in combination with a compound having a structure represented by the general formula (I).

Examples of the plasticizer that can be used include, but are not limited to, a phosphate ester plasticizer, a phthalate ester plasticizer, and a citrate ester plasticizer. Phosphate esters include triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, tributyl phosphate, and the like.Phthalate esters include diethyl phthalate, dimethoxyethyl phthalate Dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, butyl benzyl phthalate, dibenzyl phthalate, butyl phthalyl butyl glycolate, ethyl phthalyl ethyl glycolate, methyl phthalyl ethyl glycolate, etc. Triethyl citrate as an acid ester plasticizer,
Tri-n-butyl citrate, acetyl triethyl citrate, acetyl tri-n-butyl citrate, acetyl tri-n- (2-ethylhexyl) citrate and the like can be preferably used.

It is preferable to use these alone or in combination, and these plasticizers may be used in combination of two or more if necessary. The amount of the plasticizer to be used is preferably 1 to 30% by mass, more preferably 2 to 25% by mass, further preferably 2 to 15% by mass, particularly preferably 3 to 12% by mass, based on the cellulose ester. % By mass.

The cellulose ester film of the present invention may contain, besides the above-mentioned plasticizer, an additive having the same action as the plasticizer. As long as these additives are low molecular organic compounds capable of plasticizing the cellulose ester film, the effects of the present invention can be obtained in the same manner as the plasticizer. These components are not added for the purpose of directly plasticizing the film as compared with the plasticizer, but exhibit the same action as the above-mentioned plasticizer depending on the amount.

It is preferable to add an ultraviolet absorber to the cellulose ester film of the present invention. For example, from the viewpoint of preventing deterioration of the liquid crystal, those having excellent absorption of ultraviolet light having a wavelength of 370 nm or less and having little absorption of visible light having a wavelength of 400 nm or more are preferably used from the viewpoint of good liquid crystal display properties. In the present invention, in particular, a wavelength of 380 nm
Is preferably 10% or less, more preferably 5% or less, and still more preferably 1% or less.

In the present invention, for example, a blue dye or the like may be used as an additive to adjust the color of the film. Preferred dyes include anthraquinone dyes. The anthraquinone-based dye can have any substituent at positions 1 to 8 of the anthraquinone. Preferred substituents include an optionally substituted anilino group, a hydroxyl group, an amino group, a nitro group, and a hydrogen atom. The amount of these dyes added to the film is 0.1 to 10 to maintain the transparency of the film.
00 μg / m ² , preferably 10 to 100 μg / m ² .

Further, it is preferable to add fine particles as a matting agent to the cellulose ester film of the present invention in order to impart lubricity to the film. It is preferable that these fine particles are surface-treated with an organic substance because the haze of the film can be reduced.

Preferred organic substances for the surface treatment include halosilanes, alkoxysilanes, silazane, siloxane and the like.

The larger the average diameter of the fine particles, the greater the matting effect, and the smaller the average diameter, the better the transparency. Therefore, in the present invention, the average diameter of the primary particles of the fine particles is preferably from 5 to 50 nm, more preferably 7 to 20 nm.

The fine particles are not particularly limited. For example, AEROSIL 200, 2 manufactured by Nippon Aerosil Co., Ltd.
00V, 300, R972, R972V, R974, R
202, R812, OX50, TT600 and the like, and preferably AEROSIL200V and R972V.

These fine particles usually have an average particle size of 0.01
These particles form secondary particles having a thickness of about 1.0 μm, and these fine particles are present as an aggregate of primary particles in the film, and form irregularities of 0.01 to 1.0 μm on the film surface. The content of these fine particles is preferably 0.005 to 0.3% by mass based on the cellulose ester.

In particular, the cellulose ester film of the present invention preferably contains fine particles of silicon dioxide, and a cellulose ester solution containing the compound of the present invention, an ultraviolet absorbent having a distribution coefficient of 8.5 or more, and fine particles of silicon dioxide. Casting a cellulose ester film using the above method is particularly preferable, since foreign matter failure due to aggregation of fine particles in the cellulose ester solution is significantly reduced.

For obtaining the cellulose ester film of the present invention, as a method for preparing a dispersion of fine particles, there are, for example, the following three methods.

[Preparation Method A] After stirring and mixing the solvent and the fine particles, the mixture is dispersed with a disperser. This is used as a fine particle dispersion. The fine particle dispersion is added to the dope and stirred.

[Preparation Method B] After stirring and mixing the solvent and the fine particles, the mixture is dispersed with a disperser. This is used as a fine particle dispersion. Separately, a small amount of a cellulose ester is added to a solvent and dissolved by stirring. The fine particle dispersion is added thereto and stirred.
This is used as a fine particle addition liquid. The fine particle addition liquid is sufficiently mixed with the dope liquid using an in-line mixer.

[Preparation Method C] A small amount of a cellulose ester is added to a solvent and dissolved by stirring. Fine particles are added thereto and dispersed by a disperser. This is used as a fine particle addition liquid. The fine particle addition liquid is sufficiently mixed with the dope liquid using an in-line mixer.

Preparation method A is excellent in dispersibility of silicon dioxide fine particles, and preparation method C is excellent in that silicon dioxide fine particles are less likely to re-aggregate. Above all, the above-mentioned preparation method B is a preferable preparation method which is excellent in both the dispersibility of the silicon dioxide fine particles and the difficulty of re-aggregation of the silicon dioxide fine particles.

[Dispersion method] When silicon dioxide fine particles are mixed with a solvent and dispersed, the concentration of silicon dioxide is 5 to 30.
% By mass is preferable, and 10 to 25% by mass is more preferable.
15-20% by mass is most preferred. The higher the dispersion concentration, the lower the liquid turbidity with respect to the amount added, which is preferable because haze and aggregates are improved.

As the solvent to be used, lower alcohols preferably include methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol and the like. The solvent other than the lower alcohol is not particularly limited, but it is preferable to use a solvent used in forming a cellulose ester film.

Using the dope thus obtained, a cellulose ester film can be obtained through a casting process described below.

[Casting Step] The dope is fed to a pressurizing die through a pressurized metering gear pump, and at a casting position, an endless metal belt or a casting support for a rotating metal drum (hereinafter, referred to as an infinity). It may simply be a support)
In this step, a dope is cast from a pressure die. The surface of the casting support is a mirror surface.

Other casting methods include a doctor blade method in which the thickness of the cast dope film is adjusted with a blade, and a reverse roll coater method in which the film is adjusted with a counter-rotating roll. A pressure die that can adjust the shape and easily make the film thickness uniform is preferable. Examples of the pressure die include a coat hanger die and a T die, and any of them is preferably used.

In order to increase the film forming speed, two or more pressure dies may be provided on the casting support, and the doping amount may be divided to form an overlap. Alternatively, the inside of the die is divided by slits, and a plurality of dope solutions having different compositions are simultaneously cast (also called co-casting).
Thus, a cellulose ester film having a laminated structure can be obtained.

The dope thus obtained is cast on a support such as a belt or a drum to form a film. The present invention is particularly effective in a solution casting film forming method using a belt. This is because it is easy to finely adjust the drying conditions on the support as described later.

[Solvent Evaporation Step] A web (in the present invention, a dope is cast on a casting support and the formed dope film is called a web) is heated on the casting support to remove the solvent. This is the step of evaporating. In order to evaporate the solvent, there are a method of blowing air from the web side and / or a method of transferring heat with liquid from the back surface of the support, a method of transferring heat from the front and back by radiant heat, and the like. Drying efficiency is preferred. Further, a method of combining them is also preferable. The web on the support after casting is placed in an atmosphere of 40 to 100 ° C.
Drying on a support is preferred. 40-100 ° C
In order to maintain the atmosphere, the hot air at this temperature is preferably applied to the upper surface of the web or heated by means such as infrared rays.

In particular, the cellulose ester film of the present invention desirably releases the web from the support within 30 to 90 seconds after casting. When peeled in less than 30 seconds,
Not only is the surface quality of the film deteriorated, but also the moisture permeability is not preferred. Drying for more than 90 seconds is not preferable because the surface quality is deteriorated due to deterioration of the releasability and a strong curl is generated in the film.

[Peeling Step] In this step, the web from which the solvent has evaporated on the support is peeled from the support at the peeling position. The peeled web is sent to the next step. If the residual solvent amount of the web at the time of peeling (the following formula) is too large,
On the other hand, if it is difficult to peel off or, on the other hand, is sufficiently dried on the support and then peeled off, a part of the web is peeled off in the middle.

The temperature at the peeling position on the support is preferably 10 to 40 ° C., more preferably 11 to 30 ° C.
° C. The residual solvent amount of the web at the peeling position is:
25 to 120% by mass is preferable, and more preferably 40 to 120% by mass.
100% by mass.

The amount of residual solvent in the web according to the present invention is defined by the following equation.

Residual solvent amount = (mass of web before heat treatment−
Mass after heat treatment of web) / (mass after heat treatment of web) × 100% The heat treatment when measuring the residual solvent amount is 115 ° C.
Represents that heat treatment is performed for one hour.

In order to adjust the amount of the residual solvent at the time of peeling as described above, the surface temperature of the casting support after casting is controlled so that the organic solvent can be efficiently evaporated from the web. It is preferable to set the temperature at the peeling position on the casting support within the above-mentioned temperature range. In order to control the temperature of the support, it is preferable to use a heat transfer method having good heat transfer efficiency. For example, a back surface heat transfer method using a liquid is preferable.

The heat transfer method using radiant heat or hot air is difficult to control the temperature of the support, and is not a preferable method. However, in a belt (support) machine, the temperature control at the position where the belt to be transferred comes to the lower side is performed. The belt temperature can be adjusted by gentle wind.

The temperature of the support can be partially changed by dividing the heating means, and is set to a different temperature such as a casting position, a drying section, and a peeling position of the casting support. Can be done.

As a method of increasing the film forming speed (the film forming speed can be increased because the film is peeled off while the amount of the residual solvent is as large as possible), there is a gel casting method in which the film can be peeled even if the amount of the residual solvent is large. .

There are a method in which a poor solvent for the cellulose ester is added to the dope, gelling is performed after casting the dope, and a method in which gelling is performed by lowering the temperature of the support.
There is also a method of adding a metal salt to the dope.

By gelling on the support to strengthen the film, the peeling can be accelerated and the film forming speed can be increased.

In the case where the web is peeled off at a point where the residual solvent amount is larger, if the web is too soft, the flatness at the time of peeling is impaired, and rubbing and vertical stripes are easily generated due to the peeling tension. The amount of residual solvent is determined.
The peeling tension when peeling the support and the film is usually 19
Peeling is performed at 6 to 245 N / m. When wrinkles are likely to occur at the time of peeling, it is preferable to peel at 190 N / m or less, and further, the minimum tension at which peeling can be performed is 166.6 N / m.
m, then peeling at a minimum tension of ２137.2 N / m, particularly preferably at a minimum tension of １００100 N
/ M. It is preferable that the peeling tension is lower because the in-plane retardation Ro can be kept lower. The in-plane retardation Ro is preferably less than 20 nm, more preferably less than 10 nm and then preferably less than 5 nm, most preferably 0 to 1 nm.

In the present invention, the in-plane retardation R
o was measured using an automatic birefringence meter KOBRA-21ADH (manufactured by Oji Scientific Instruments) at a wavelength of 590 nm.
A three-dimensional refractive index measurement is performed, and the obtained refractive indices nx, ny,
nz can be calculated. Further, a retardation value Rt in the film thickness direction of 0 to 300 nm is obtained, more preferably 0 to 150 nm, more preferably 0 to 70 nm.
nm is preferably obtained according to the application.

Ro = (nx−ny) × d Rt = ((nx−ny) / 2−nz) × d The cellulose ester film of the present invention has an angle θ (radian) between the slow axis direction and the film forming direction. ) And in-plane retardation Ro have the following relationship, and are particularly preferably used as optical films such as protective films for polarizing plates.

P ≦ 1−sin ² (2θ) sin ² (πRo / λ) P = 0.9999 Nx is the refractive index in the slow axis direction in the film plane, and Ny is the refraction in the fast axis direction in the film plane. Is the refractive index in the thickness direction of the film, and d is the film thickness (nm) of the film. θ is the angle (° radian) formed between the slow axis direction in the film plane and the film forming direction (straight direction of the film), and λ is the above-mentioned Nx, Ny, Nz, θ in the three-dimensional refractive index measurement for determining θ. The wavelength of light is 590 nm, and π is the circular constant.

[Drying Step] While maintaining the width using a drying device that alternately transports the web through rolls arranged in a staggered manner and / or a tenter device that transports the web while holding both ends of the web with clips or pins, This is the step of drying the web. It is preferable to maintain the transport tension in the drying step as low as possible because Ro can be kept low.
It is preferably 90 N / m or less. More preferably, it is preferably 170 N / m or less, more preferably 140 N / m or less.
It is particularly preferred that it is 30 N / m. In particular, it is effective to maintain the transport tension at or below the above-mentioned value until the amount of the residual solvent in the film becomes at least 5% by mass or less.

In general, hot air is blown on both sides of the web as a drying means, but there is also a means for heating by applying a microwave instead of the wind. Too fast drying tends to impair the flatness of the finished film. Drying at a high temperature is preferably performed when the residual solvent is about 8% by mass or less.
Throughout, the drying temperature is generally between 40 and 250 ° C. In particular, drying at 40 to 160 ° C is preferable.

In the drying step after peeling off from the surface of the casting support, the web tends to shrink in the width direction due to evaporation of the solvent. The quicker it dries at higher temperatures, the greater the shrinkage.

Drying while suppressing this shrinkage as much as possible is preferable for improving the flatness of the finished film.

From this viewpoint, for example, Japanese Patent Application Laid-Open No. 62-46
No. 625, a method of drying the whole or part of the web in the width direction while holding both ends of the web widthwise with a clip or a pin (called a tenter method), in particular, using a clip A tenter method and a pin tenter method using pins are preferably used.

At this time, the stretching ratio in the width direction is 0% to 10%.
It is preferably 0%, more preferably 5% to 20%, and more preferably 8% to 15% when used as a polarizing plate protective film.
% Is most preferable, and when used as a retardation film, 10% to 40% is more preferable, and 20% to 30% is most preferable. R0 can be controlled by the stretching ratio, and a higher stretching ratio is preferable because the resulting film has excellent flatness.

When the tenter is performed, the amount of the residual solvent in the web is preferably 20 to 100% by mass at the start of the tenter, and drying is performed while applying a tenter until the amount of the residual solvent in the web becomes 10% by mass or less. It is preferably performed, more preferably 5% by mass or less.

The drying temperature for the tenter is 30 to
150 ° C is preferred, 50 to 120 ° C is more preferred,
70-100 ° C is most preferred. The lower the drying temperature, the less the evaporation of the ultraviolet absorber and the plasticizer, and the better the process contamination, and the higher the drying temperature, the better the flatness of the film. Even when the drying temperature is high, the ultraviolet absorbent represented by the general formula (1) hardly evaporates, so the tenter drying temperature is high,
The effect is remarkably exhibited at the time of the production condition with a high stretching ratio.

In the film drying step, the film peeled from the support is further dried to reduce the residual solvent content to 0.5% by mass or less, more preferably 0.1% by mass or less. , More preferably 0 to 0.0
It is to be 1% by mass or less.

In the film drying step, a roll hanging method or a method in which the film is dried while being conveyed by a pin tenter method as described above is generally employed. The means for drying the film is not particularly limited, and is generally performed using hot air, infrared rays, a heating roll, microwaves, or the like. It is preferable to use hot air in terms of simplicity. Drying temperature is 3 ~ in the range of 40 ~ 150 ° C.
It is preferable that the temperature is divided into five stages and the temperature is raised gradually, and it is more preferable that the temperature is raised in the range of 80 to 140 ° C. in order to improve dimensional stability.

In the process from immediately after casting through the solution casting film forming method to drying, the atmosphere in the drying apparatus may be air, but the atmosphere in an inert gas atmosphere such as nitrogen gas, carbon dioxide gas, or argon may be used. You may go.

However, it is needless to say that the danger of the explosion limit of the evaporated solvent in the dry atmosphere must always be considered.

[Winding Step] This is a step of winding up the cellulose ester film after the amount of the residual solvent in the web becomes 2% by mass or less.
A film having good dimensional stability can be obtained by the following.

As the winding method, a generally used method may be used, and there are a constant torque method, a constant tension method, a taper tension method, a program tension control method with constant internal stress, and the like. .

To adjust the film thickness, the dope concentration, the amount of liquid fed by the pump, the slit gap of the die cap, the extrusion pressure of the die, the speed of the casting support, etc. are controlled so as to obtain the desired thickness. Good to do.

As means for making the film thickness uniform, it is preferable that the programmed feedback information is fed back to each of the above-described devices using a film thickness detecting means for adjustment.

The thickness of the cellulose ester film varies depending on the purpose of use, but as a finished film, it is usually in the range of 5 to 500 μm, and more preferably 10 to 250 μm.
Is particularly preferable as a film for a liquid crystal image display device. The cellulose ester film of the present invention is excellent in moisture permeability and dimensional stability, in particular, though it is a thin film having a thickness of 10 to 60 μm.

The moisture permeability in the present invention is defined by JIS Z
It is defined by the value measured by the method described in “0208”. Moisture permeability is preferably 20~250g ^{/ m} 2 · 24 hours, but is preferably in particular 20~200g ^{/ m} 2 · 24 hours. When the moisture permeability exceeds 250 g / m ² · 24 hours, the durability of the polarizing plate is significantly reduced.
Is less than 0g / m 2 · ²⁴ hours, a solvent such as water which is used in the adhesive during polarizer manufacturing becomes difficult to dry, is not preferable because the drying time is prolonged. More preferably 25 to 2
It is a 00g ^{/ m} 2 · 24 hours.

The dimensional stability of the cellulose ester film of the present invention can be further improved by reducing the mass change at 80 ° C. and 90% RH.

The cellulose ester film of the present invention comprises
It is more preferable that the mass change rate before and after the heat treatment at 80 ° C. and 90% RH for 48 hours is within ± 2%, whereby the thin film film with improved moisture permeability has excellent dimensional change rate. A cellulose ester film can be obtained.

The cellulose ester film of the present invention comprises
The dimensional change after heat treatment for 48 hours at 80 ° C. and 90% RH atmosphere is MD direction (film forming direction), TD
Both directions (width direction of the film) are preferably within ± 0.5%, more preferably within ± 0.3%, further preferably within ± 0.1%, and further preferably ± 0%. It is preferably within 0.05%.

The dimensional change rate in the present invention is a characteristic value representing the dimensional change in the longitudinal and lateral directions of the film under severe conditions of temperature and humidity. Specifically, the film is placed under a heating condition, a humidifying condition, and a hot and humid condition, and the vertical and horizontal dimensional changes as forced deterioration are measured. For example, a film sample to be measured is cut to a size of 150 mm in the width direction and 120 mm in the length direction, and two points are formed on the film surface at 100 mm intervals in the width direction and the length direction, respectively, with a sharp blade such as a razor. Mark the mold.
The film is conditioned in an environment of 23 ° C. and 55% RH for 24 hours or more, and the distance L1 between the marks in the width direction and the longitudinal direction before the treatment is measured with a factory microscope. Next, the sample is subjected to high-temperature and high-humidity treatment (conditions: 80 ° C., 90%
(Leave for 48 hours in an RH environment). Again, the sample is humidified in an environment of 23 ° C. and 55% RH for 24 hours, and the distance L2 between the marks in the width direction and the length direction after the treatment is measured with a factory microscope. The rate of change before and after this processing is determined by the following equation.

Dimensional change rate (%) = (L2−L1) / L1 × 100 In the formula, L1 represents a distance between marks before processing, and L2 represents a distance between marks after processing.

That is, a desired dimensional change can be measured by setting the positions of the marks to be applied in the longitudinal direction and the width direction of the film.

The dimensional change after treatment at 105 ° C. for 5 hours is preferably within ± 0.5%, more preferably within ± 0.3%, and more preferably ± 0.3%, in both the MD and TD directions. It is preferably within 0.1%.
Preferably it is within 0.05%.

The cellulose ester film of the present invention comprises
Tensile strength 90 to 170 N / mm in both MD and TD directions
² , especially 120 to 160 N / mm
It is preferably ² .

The water content is preferably from 0.1 to 5%,
0.3 to 4% is more preferable, and 0.5 to 2% is further preferable.

The cellulose ester film of the present invention comprises
The transmittance is desirably 90% or more, more preferably 92% or more, and still more preferably 93% or more. Further, the haze is preferably 0.5% or less,
In particular, it is preferably 0.1% or less, more preferably 0%.

In the cellulose ester film of the present invention, it is preferable that the curl value has a small absolute value, and the deformation direction may be either the + direction or the-direction. The absolute value of the curl value is preferably 30 or less, more preferably 2
0 or less, and particularly preferably 10 or less.
The curl value is represented by a radius of curvature (1 / m).

Hereinafter, the method for producing the cellulose ester film of the present invention by the solution casting method will be described in more detail with reference to the drawings.

FIG. 1 is a schematic view showing a preferred example of a solution casting method for forming a film. FIG. 1A is a schematic diagram of a case where the film is dried in a roll conveying / drying step after casting. FIG.
(B) is a schematic diagram in a case where after casting, drying is performed in a roll transport / drying step, and then drying is performed in a tenter transport / drying step. FIG. 1 (c) is a schematic view showing a case where, after casting, drying is performed in a tenter conveying / drying step, and then drying is performed in a roll conveying / drying step. FIG. 1D is a schematic view showing a case where after casting, drying is performed in a roll transport and drying process, then drying is performed in a tenter transport and drying process, and then drying is performed in a roll transport and drying process.

In the present invention, the steps including the tenter transport / drying step and the roll transport / drying step include a step of drying the film separated from the support and drying the film. It refers to a process having a tenter transport / drying process and a roll transport / drying process for adjusting the expansion / contraction ratio. The tenter transport / drying step refers to a step in which drying is performed simultaneously while being transported by the tenter transport apparatus, and the drying expansion / contraction ratio is adjusted. It refers to the step of adjusting the rate.

In FIG. 1, reference numeral 1 denotes a support running endlessly. A mirror-like metal strip is used as the support. Reference numeral 2 denotes a die for casting a dope obtained by dissolving a cellulose ester resin in a solvent on a support 1. Reference numeral 3 denotes a peeling point at which the film on which the dope cast on the support 1 is solidified is peeled off, and reference numeral 4 denotes a peeled-off film. Reference numeral 5 denotes a tenter conveying / drying process, and 51 denotes an exhaust port.
Reference numeral 2 denotes a drying air intake. Note that the exhaust port 51 and the dry air intake port 52 may be reversed. Reference numeral 6 denotes a tension cutting means. Examples of the tension cutting means include a nip roll and a suction roll. Incidentally, the tension cutting means may be provided between each step.

Reference numeral 8 denotes a roll conveying / drying step, 81 denotes a drying box, 82 denotes an exhaust port, and 83 denotes a dry air intake. In addition, the exhaust port 82 and the dry air intake 83
May be reversed. Reference numeral 84 denotes an upper transport roll,
Reference numeral 85 denotes a lower transport roll. The transfer roll 84,
Reference numeral 85 denotes one set of upper and lower parts, and is composed of a plurality of sets. Reference numeral 7 denotes a rolled-up film.

In the step shown in FIG. 1D, the roll transport / drying step before the tenter transport / drying step 5 is called a first roll transport / drying step, and the roll transporting after the tenter transport / drying step 5 is performed. -The drying step is referred to as a second roll transport / drying step. Note that a cooling step not shown in FIGS. 1A to 1D may be provided as necessary before winding.

In the present invention, the cellulose ester film may be produced by any of the above-mentioned solution casting methods.

The cellulose ester film of the present invention
From the viewpoint of good moisture permeability and dimensional stability, it is preferably used for a liquid crystal display member, more specifically, a protective film for a polarizing plate.
In particular, the cellulose ester film of the present invention is preferably used in a protective film for a polarizing plate which has strict requirements for both moisture permeability and dimensional stability.

The polarizing plate according to the present invention can be manufactured by a general method. For example, a method in which an optical film or a cellulose ester film is subjected to an alkali saponification treatment, and a polyvinyl alcohol film is immersed in an iodine solution and bonded to both surfaces of a polarizing film produced by stretching using a completely saponified polyvinyl alcohol aqueous solution. is there. The alkali saponification treatment refers to a treatment in which the cellulose ester film is immersed in a high-temperature strong alkaline solution in order to improve the wetting of the aqueous adhesive and improve the adhesiveness.

The cellulose ester film of the present invention has a hard coat layer, an antiglare layer, an antireflection layer, an antifouling layer, an antistatic layer, a conductive layer, an optically anisotropic layer, a liquid crystal layer, an alignment layer, an adhesive layer,
Various functional layers such as an adhesive layer and an undercoat layer can be provided. These functional layers can be provided by a method such as coating or vapor deposition, sputtering, plasma CVD, and atmospheric pressure plasma treatment.

The polarizing plate thus obtained is provided on one or both sides of a liquid crystal cell, and the liquid crystal display device of the present invention can be obtained using the polarizing plate.

By using the protective film for a polarizing plate composed of the cellulose ester film of the present invention, it is possible to provide a polarizing plate which is thinner and has excellent durability, dimensional stability and optical isotropy.

Further, the liquid crystal display device using the polarizing plate or the retardation film of the present invention can maintain stable display performance for a long period.

The cellulose ester film of the present invention can be used as a substrate for an antireflection film or an optical compensation film.

Hereinafter, embodiments of the present invention will be described with reference to specific examples, but the present invention is not limited thereto. In the following, "parts" represents "parts by mass".

[0156]

EXAMPLES <Synthesis of UVP-2> Tetrahydrofuran 5
To 0 ml, 4.0 g of the aforementioned UVM-1 (ultraviolet absorbing monomer represented by the general formula (I)) and 6.0 g of MMA were added, and then 30 ml of tetrahydrofuran in which 0.93 g of azoisobutyronitrile was dissolved was added. Was. Then, polymerization was carried out at 70 ° C. for 9 hours in a nitrogen atmosphere. After distilling off tetrahydrofuran under reduced pressure, the residue was redissolved in 30 ml of tetrahydrofuran and added dropwise to a large excess of methanol. The deposited precipitate was collected by filtration and dried in vacuo at 40 ° C. to obtain 9.4 g of an off-white powdery polymer.

The powder was confirmed to have a weight average molecular weight of 8,900 by GPC analysis using standard polystyrene. From the NMR spectrum and the UV spectrum, it was confirmed that the polymer was a copolymer of UVM-1 and MMA. The composition of the polymer was UVM-
1: MMA = 40: 60.

<Synthesis of UVP-7> 4.0 g of UVM-1 and 1.0 g of HEM were added to 50 ml of tetrahydrofuran.
A and 5.0 g of MMA were added, and then tetrahydrofuran 30 in which 0.90 g of azoisobutyronitrile was dissolved.
ml was added. Then, polymerization was carried out at 70 ° C. for 9 hours in a nitrogen atmosphere. After distilling off tetrahydrofuran under reduced pressure, 30
It was redissolved in ml of tetrahydrofuran and added dropwise to a large excess of methanol. The deposited precipitate was collected by filtration and dried in vacuo at 40 ° C. to obtain 9.0 g of an off-white powdery polymer.

The powder was confirmed to have a weight average molecular weight of 9,400 by GPC analysis using standard polystyrene. From the NMR spectrum and the UV spectrum, it was confirmed that the polymer was a copolymer of UVM-1, HEMA, and MMA. The composition of the polymer was UVM-1: HEMA: MMA = 40: 10: 50.
Met.

<Synthesis of Comparative UVP-C1> In 50 ml of tetrahydrofuran, 4.0 g of the following UVM-C1 was added.
0 g of HEMA and 5.0 g of MMA were added, followed by 30 ml of tetrahydrofuran in which 1.12 g of azoisobutyronitrile was dissolved. Then, under nitrogen atmosphere, 7
Polymerization was carried out at 0 ° C. for 9 hours. After the tetrahydrofuran was distilled off under reduced pressure, the residue was redissolved in 30 ml of tetrahydrofuran and added dropwise to a large excess of methanol. The deposited precipitate is collected by filtration,
Vacuum drying was performed at 40 ° C. to obtain 9.2 g of an off-white powdery polymer.

The powder was confirmed to have a weight average molecular weight of 7,700 by GPC analysis using standard polystyrene. From the NMR spectrum and the UV spectrum, it was confirmed that the polymer was a copolymer of UVM-C1, HEMA, and MMA. The composition of the polymer was UVM-C1: HEMA: MMA = 40: 10: 5.
It was 0.

The ultraviolet absorbing polymer used in the present invention can be synthesized by the same method.

The ultraviolet absorbing polymer and the comparative polymer used in this example are shown in Table 1 below.

Table 1 MMA = methyl methacrylate HEMA = 2-hydroxyethyl methacrylate [Samples 1 to 15] [Silicon oxide dispersion] Aerosil 200V (manufactured by Nippon Aerosil Co., Ltd.) 10 parts (average primary particle diameter 12 nm, apparent specific gravity 100 g / l) ethanol 90 parts or more were stirred and mixed with a dissolver for 30 minutes, and then dispersed with Menton-Gaulin. The liquid turbidity after dispersion is 93 pp
m.

[Preparation of Additive Liquid A] Ultraviolet-absorbing polymer (described in Table 2) 10 parts Methylene chloride 100 parts The above was charged into a closed container, completely dissolved while heating and stirring, and filtered. To this, 10 parts of a silicon oxide dispersion was added with stirring, and the mixture was further stirred for 30 minutes, and then filtered to prepare an additive liquid A.

[Preparation of Dope A] Cellulose triacetate synthesized from linter cotton 85 parts Cellulose triacetate synthesized from wood pulp 15 parts Triphenyl phosphate 11.5 parts Methylene chloride 475 parts Ethanol 50 parts The mixture was charged, heated, and completely dissolved with stirring, followed by filtration to prepare a dope solution A.

[Film forming process] To 100 parts of the dope solution A, the amount of the additive solution A shown in Table 2 was added, and an in-line mixer (Toray stationary type in-pipe mixer Hi-Mixer, SW
Mix well in J) and filter.

Next, using a belt casting device, the temperature was 33
The film was uniformly cast on a stainless steel band support at a temperature of 1500 mm in width. Stainless steel band support, residual solvent amount is 1
The solvent was evaporated until the peeling tension reached 127%.
m and peeled from the stainless steel band support. The peeled cellulose triacetate film was slit into a width of 1300 mm, and thereafter, 1.05 mm in the width direction with a pin tenter.
The film was double-stretched, then dried while being conveyed by a number of rolls through a drying zone, slit to a width of 1100 mm, and cellulose triacetate film samples 1 to 15 were obtained. At this time, the thickness of the cellulose triacetate film was 40 μm.

[Evaluation] The obtained sample was evaluated according to the following measuring method. Durability is haze (1 sheet value) 0.2
% Or less was evaluated. The results are shown in the table below.
It is shown in FIG.

[Measurement method] UV performance Spectrophotometer U-3200
Using Hitachi (manufactured by Hitachi, Ltd.), the spectral absorption spectrum of the film was measured, the transmittance at 500 nm and 380 nm was determined, and the films were ranked as follows. The higher the transmittance at 500 nm, the better, and the lower the transmittance at 380 nm, the better. (Transmittance at 500 nm) A: 92% or more transmittance B: 90% to less than 92% transmittance C: 85% to less than 90% D: less than 85% transmittance (380 nm transmittance) A: ... Transmittance of less than 5% B ... Transmittance of 5% or more and less than 8% C ... Transmittance of 8% or more and less than 10% D ... Transmissivity of 10% or more D1003-
52, T-2600D manufactured by Tokyo Denshoku Industries Co., Ltd.
A was measured using A. (Three-sheet value) ASTM-D1003-
52, T-2600D manufactured by Tokyo Denshoku Industries Co., Ltd.
A was measured using A. Durability The bleed-out was evaluated after leaving the film sample in a high-temperature and high-humidity atmosphere of 80 ° C. and 90% RH for 1000 hours. (Bleed-out) The presence or absence of bleed-out was evaluated by observing the surface of the film. A: There is no bleed-out on the film surface. …: Partial bleed-out is slightly recognized on the film surface. Δ: Bleed-out on the entire surface of the film is slightly recognized. ×: The entire bleed-out is clearly seen on the film surface.

Table 2 As is clear from Table 2, the sample using the ultraviolet absorbing copolymer in the present invention is sufficiently suitable for practical use even when used as a polarizing plate. That is, while having sufficient ultraviolet absorption performance, haze, transpiration, bleed-out, and precipitation do not occur, the transparency is excellent, and the long-term weather resistance is excellent.

Subsequently, using the samples 1 to 9, 12 and 15, the following alkali saponification treatment, the production of a polarizing plate, and the production of a liquid crystal panel were performed, and the illuminance was 70,000 lux using a xenon long life weather meter. For 500 hours, and the light resistance was evaluated. [Light resistance] [Alkaline saponification treatment] Saponification step 2 mol / l-NaOH 50 ° C 90 seconds Rinse step Water 30 ° C 45 seconds Neutralization step 10% by mass HCl 30 ° C 45 seconds Rinse step water 30 ° C 45 seconds Under the above conditions The film sample was saponified, washed with water, neutralized, washed with water in that order, and then dried at 80 ° C. Preparation of Polarizing Plate A polyvinyl alcohol film having a thickness of 120 μm was immersed in 100 kg of an aqueous solution containing 1 kg of iodine and 4 kg of boric acid, and stretched 6 times at 50 ° C. to form a polarizing film. Cellulose ester film samples which had been subjected to an alkali saponification treatment on both sides of the polarizing film were bonded to each other using a 5% aqueous solution of completely saponified polyvinyl alcohol as an adhesive to prepare a polarizing plate.・ Production of liquid crystal panel 15 type TFT color liquid crystal display LA-1529
The polarizing plate of HM (made by NEC) was peeled off, and the two polarizing plates prepared above were attached so as to sandwich the liquid crystal cell so that the polarizing axes of the polarizing plates did not change from the original and were orthogonal to each other.
A 5-inch TFT color liquid crystal display was manufactured.

As a result, it was found that the liquid crystal panels prepared from Samples 12 and 15 had deteriorated image resolution and sharpness as compared to before the irradiation with the xenon long life weather meter, and the polarization degree was deteriorated. As a result, deterioration of the liquid crystal cell was observed.

On the other hand, in the liquid crystal panels prepared from Samples 1 to 9, no change was observed in the resolution and sharpness of the image.

[0175]

According to the present invention, a resin composition having excellent spectral absorption, low bleed-out, no coloring, excellent transparency, sufficient ultraviolet absorbing ability, and excellent long-term weather resistance can be obtained. An optical film using the resin composition, and a polarizing plate and a display device provided with the optical film are extremely excellent.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a casting film forming apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Mirror surface belt-shaped metal casting support 2 Dice 4 Cellulose ester film 5 Tenter conveyance and drying process 6 Tension cutting means 8 Roll conveyance and drying process 84 Upper conveyance roll 85 Lower conveyance roll

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G02B 1/04 G02B 1/04 5/22 5/22 5/30 5/30 (72) Inventor Osamu Ishige 1 in Konica Corporation, Hino-shi, Tokyo Konica Corporation (72) Inventor Isamu 1 in Konica Corporation, Sakura-cho, Hino-shi, Tokyo (72) Inventor Yoshinori Omae 1-3-3 Higashikawasaki-cho, Chuo-ku, Kobe-shi, Hyogo No. 3 F-term in Chemipro Kasei Co., Ltd. (Reference) 2H048 CA04 CA13 CA19 2H049 BA02 BA06 BB13 BB33 BC09 4F071 AA01 AA09 AA22X AA33X AA35X AA77 AF30 AF55 AF57 AH12 AH16 BB02 BB07 BC01 4B021 BG001 BC021 001 BG132 BK001 BN151 CF001 CG001 CH071 CH091 CK021 CL001 CN031 FD012 FD020 FD050 FD090 4J100 AB02Q AB07P AC03Q AE02Q AE03Q AE04Q AG03Q AG04Q AG05Q AG06Q AL03Q AL04Q AL08P AL08Q AM02Q AM15Q AM19Q AM21P AN01Q BA02P BA03P BA03Q BA05Q BA06Q BC04Q BC43P BC43Q BC53Q BC68Q BC73P BC79Q CA04 JA32 JA39

Claims (11)

[Claims] 1. A resin composition comprising: a synthetic resin; and an ultraviolet absorbing polymer containing a unit formed from an ultraviolet absorbing monomer represented by the following general formula (I). General formula (I) (In the general formula (I), R ₁ represents a linear or branched alkyl group or a cycloalkyl group which may have a substituent, and R ₂ and R ₃ represent a hydrogen atom, a halogen atom or a substituent. Alk represents a linear or branched alkylene group or a cycloalkylene group which may have a substituent, L ₁ represents a divalent linking group, n represents 0 or 1, and P represents Represents a polymerizable group containing an ethylenically unsaturated functional group.) 2. The method according to claim 1, wherein the content of the unit formed from the ultraviolet absorbing monomer represented by the general formula (I) is 1% by mass or more and 60% by mass or less of the ultraviolet absorbing polymer. Item 10. The resin composition according to Item 1. 3. The ultraviolet absorbing polymer represented by the general formula (I)
3. The resin composition according to claim 1, wherein the resin composition is a copolymer of an ultraviolet absorbing monomer represented by the formula: and a monomer copolymerizable with the ultraviolet absorbing monomer. 4. A monomer copolymerizable with the ultraviolet absorbing monomer represented by the general formula (I) is a hydrophilic ethylenically unsaturated monomer and / or an ethylenically unsaturated monomer having no hydrophilic group in the molecule. The resin composition according to claim 3, which is a saturated monomer. 5. The method according to claim 1, wherein the hydrophilic ethylenically unsaturated monomer is
The resin composition according to claim 4, which is a (meth) acrylate-based monomer having a hydroxyl group or a carboxyl group in a molecule. 6. The resin composition according to claim 1, wherein the ultraviolet absorbing polymer is obtained by a solution polymerization method. 7. The resin composition according to claim 1, wherein the weight average molecular weight of the ultraviolet absorbing polymer is from 2,000 to 20,000. 8. The resin composition according to claim 1, wherein the synthetic resin is a cellulose ester. 9. An optical film comprising the resin composition according to any one of claims 1 to 8. 10. A polarizing plate comprising the optical film according to claim 9. 11. A display device comprising the optical film according to claim 9.