JP2006342227A - Cellulose ester film, polarizing plate, and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cellulose ester film having stabilized optical performance and high moist stability, and produced in high productivity without failure by a foreign matter caused by generation of chips at film formation; and to provide a polarizing plate and a liquid crystal display device having high durability by using the cellulose ester film. <P>SOLUTION: The cellulose ester film contains the following compound (J) and at least one kind of compounds represented by the following (K) or (L): (J) a polyester obtained by the polycondensation reaction of (a) glycols having average 2-3.5 carbons with (b) a dibasic acids having average 4-4.5 carbons, and having ≥1,500 and ≤10,000 number average molecular weight; (K) a polyhydric alcohol ester; and (L) an aromatic terminal ester represented by general formula (1): B-(G-A)n-G-B and having ≥300 and <1,500 molecular weight. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a high-productivity cellulose ester film that has high humidity stability of optical performance and at the same time, is less likely to generate chips by a slitter during manufacturing and has few foreign matter failures. The present invention also relates to a polarizing plate and a liquid crystal display device using the cellulose film.

  Liquid crystal display devices are attracting attention for use in large televisions. Large LCD TVs have stricter specifications such as usage environment, viewing angle, and contrast than conventional notebook computers and LCD monitors. Strict specifications are similarly demanded for polarizing plates used for liquid crystal display devices and cellulose ester films used for polarizing plates. In particular, the stretched cellulose ester film has a great influence on the optical performance, so that strict specifications are required as an important member.

  The performance which has become strict by being used in large-sized televisions has humidity stability of optical performance, and conventional cellulose ester films have high hygroscopicity, so this humidity stability has been a problem.

  Heretofore, some proposals have been made to incorporate a polyester into a cellulose ester (see, for example, Patent Documents 1 to 4). They do not suggest an improvement in the humidity stability of the optical performance, and most of them become cloudy or bleed out when they are contained in an amount of 10% or more.

The present inventor has found that the humidity stability of the optical performance of the cellulose ester film is improved by using a specific polyester. (Filed on Aug. 25, 2004; Japanese Patent Application No. 2004-244772)
However, when processed into a polarizing plate and subjected to a durability test under high temperature and high humidity for a long time, it was found that the polarizer still deteriorated and the function of the polarizing plate deteriorated remarkably.

Further, when the polyester is contained in the cellulose ester, cutting with a slitter deteriorates, and a lot of fine powder of the cellulose ester film called a cut powder is generated. This swarf floats in the film forming process and adheres to the cellulose ester film, which causes a foreign matter failure and deteriorates the productivity of the film.
Japanese Patent Laid-Open No. 2002-22756 JP 2002-267846 A JP 2004-175971 A JP 2004-175972 A

  Accordingly, an object of the present invention is to obtain a cellulose film having high productivity, having stable optical performance, high humidity stability, and no foreign matter failure due to generation of chips during film formation. It is to obtain a highly durable polarizing plate and liquid crystal display device using a film.

  The above object of the present invention can be achieved by the following means.

(Claim 1)
A cellulose ester film comprising a compound (J) shown below and at least one compound represented by (K) or (L).
(J) Number average molecular weight Mn obtained from a polycondensation reaction between glycols (a) having an average carbon number of 2 to 3.5 and dibasic acids (b) having an average carbon number of 4 to 4.5 Polyester (K) polyhydric alcohol ester (L) having a molecular weight of 300 or more and less than 1500 represented by the following general formula (1):
B- (GA) n-GB
(In the formula, B represents a benzene monocarboxylic acid residue. G represents an alkylene glycol residue having 2 to 12 carbon atoms, an aryl glycol residue, or an oxyalkylene glycol residue having 4 to 12 carbon atoms. A represents carbon. Represents an alkylene dicarboxylic acid residue having 4 to 12 carbon atoms and an aryl dicarboxylic acid residue having 6 to 12 carbon atoms, n is an integer of 1 to 5.)
(Claim 2)
The cellulose ester film according to claim 1, wherein a cellulose ester having a total acyl group substitution degree of 2.4 or more and less than 2.8 is used.

(Claim 3)
The cellulose ester film according to claim 1 or 2, wherein a retardation value Ro defined by the following formula (I) or (II) is 30 to 200 nm and Rt is 70 to 400 nm.

Formula (I) Ro = (nx−ny) × d
Formula (II) Rt = {(nx + ny) / 2−nz} × d
(Where nx is the refractive index in the direction with the largest refractive index in the film plane, ny is the refractive index in the film plane in the direction perpendicular to nx, nz is the refractive index in the thickness direction of the film, and d is the (Thickness (nm) is shown respectively.)
(Claim 4)
The cellulose ester film according to any one of claims 1 to 3, further comprising an ultraviolet-absorbing copolymer synthesized from an ultraviolet-absorbing monomer represented by the following general formula (2).

(In the formula, n represents an integer of 0 to 3, R _{1 to} R ₅ represent a hydrogen atom, a halogen atom, or a substituent, and X represents —COO—, —CONR ₇ —, —OCO—, —NR _7. CO—, wherein R ₆ and R _{7 each} represent a hydrogen atom, an alkyl group, or an aryl group, provided that the group represented by R ₆ has a polymerizable group as a partial structure.
(Claim 5)
The polarizing plate which uses the cellulose-ester film of any one of Claims 1-4.

(Claim 6)
The liquid crystal display device using the cellulose-ester film of any one of Claims 1-4.

  According to the present invention, a polarizing plate and a liquid crystal display device that can obtain a cellulose ester film that has a low foreign matter failure, an excellent optical performance, a good durability, and a high productivity can be obtained. Can be obtained.

  The best mode for carrying out the present invention will be described below.

  Until now, it has been considered that the deterioration of the polarizing plate is due to the deterioration of the moisture permeability of the film. However, as a result of our examination, it has been found that the deterioration of the polarizing film does not necessarily correlate with the deterioration of the moisture permeability of the film. As a result of various studies, we have found that the use of a polyhydric alcohol ester or a polyester plasticizer having a specific structure eliminates the deterioration of the polarizing plate.

  In addition, when a specific polyester plasticizer is contained in the cellulose ester, the slitter is not cut well, and a lot of fine powder (called swarf) of the cellulose ester film is generated, and this swarf is formed in the film forming process. The problem of floating and adhering to the cellulose ester film, resulting in foreign matter failure and reducing film productivity, can be solved by using the polyhydric alcohol ester or ester plasticizer with a specific structure in combination. I found out that

  The cellulose ester used in the present invention will be described.

  The cellulose ester used in the cellulose ester film according to the present invention is obtained by using cellulose selected from linter pulp, wood pulp and kenaf pulp and reacting them with acetic anhydride, propionic anhydride or butyric anhydride by a conventional method. Thus, cellulose triacetate, cellulose acetate propionate, cellulose acetate butyrate, and cellulose acetate propionate butyrate having a total acyl group substitution degree of 2.4 to less than 2.8 with respect to the hydroxyl group of cellulose are preferably used. If the substitution degree of the total acyl group is less than 2.4, it is preferable for the expression of retardation values Ro and Rt, but the humidity stability is inferior from the viewpoint of moisture permeability, and the contact angle is reduced by alkali saponification treatment. It is hard to do, and adhesiveness with a polarizer is inferior. When the degree of substitution of the total acyl group is 2.8 or more, particularly when the polyester polyol is contained, the expression of retardation values Ro and Rt is poor. In order to express the retardation value within the range of the present invention, the substitution degree of the total acyl group is preferably 2.4 or more and less than 2.8.

  In the present invention, cellulose triacetate (hereinafter sometimes abbreviated as TAC) and cellulose acetate propionate (hereinafter sometimes abbreviated as CAP) are preferable. In particular, cellulose acetate propionate is preferable. As a measuring method of the substitution degree of the acyl group of a cellulose ester, it can implement according to ASTM D-817-91. The molecular weight of these cellulose esters is preferably in the range of 70,000 to 300,000 as the number average molecular weight (Mn), since the mechanical strength when formed into a film is strong. Furthermore, 80000-200000 are preferable. Cellulose ester usually becomes flake shape after treatment such as washing after reaction, and is used in its shape, but the particle size is accelerated by increasing the particle size in the range of 0.05 to 2.0 mm. Is preferable.

  In addition, the average molecular weight of a cellulose ester can be measured by a well-known method using a high performance liquid chromatography (after-mentioned).

  A solution in which a cellulose ester is dissolved in an organic solvent is referred to as a dope. The concentration of the cellulose ester in the dope is about 10 to 35% by mass. More preferably, it is 15-25 mass%.

  As a solvent for the cellulose ester, an organic solvent such as methyl acetate, acetone, methylene chloride, or ethanol is preferably used to form a dope. The formed cellulose ester dope is cast on a metal support, peeled, stretched and dried to produce a cellulose ester film.

  The cellulose ester film of the present invention is suitable for a protective film for a polarizing plate. The feature of the cellulose ester film is that the cellulose ester film contains a polymer mainly composed of polyester, so that it is precipitated, volatilized or evaporated from the film. After the polarizing plate is formed, the cloudiness does not bleed out and the humidity stability of the optical performance can be improved. Further, in the process of forming a cellulose ester film, since there is no generation of chips with a slitter or the like, there are few foreign matter failures that reduce productivity.

  The ester plasticizer useful in the present invention is selected so that phase separation does not occur in the cellulose ester dope or the cellulose ester film.

  Hereinafter, the ester plasticizer used for the cellulose ester film of the present invention will be described.

(polyester)
One polyester useful as a plasticizer in the present invention will be described.

  One of the polyesters used in the present invention is dehydration of glycol (a) having an average carbon number of 2 to 3.5 and dibasic acid (b) having an average carbon number of 4 to 5.5. It is produced by a conventional method by a condensation reaction or addition and dehydration condensation reaction of the glycol (a) and dibasic anhydride (b) having an average carbon number of 4 to 5.5.

  Examples of the glycol (a) used in the polyester include ethylene glycol, diethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 2-methyl-1,3-propanediol, 1,4-butylene glycol, Neopentyl glycol, 3-methyl-1,5-pentanediol, 1,6-hexanediol and the like can be mentioned. These are used alone or in combination of two or more. For example, ethylene glycol or ethylene glycol and diethylene glycol can be used. A mixture or the like is particularly preferably used.

  Regarding the glycol (a), it is important that the average number of carbon atoms of the glycol (a) is in the range of 2 to 3.5. When the average number of carbon atoms of the glycol (a) is less than 2, it is difficult to produce a polyester, and when it is more than 3.5, the modifier for cellulose ester has poor compatibility with cellulose, and properties such as transparency. Becomes an inferior cellulose film. The glycol (a) preferably has an average carbon number of 2.1 to 2.8 or 3.2 to 3.5, and by using the glycol (a) in such a range, crystals of the polyester The melting point and melting point are close to those of conventional ones, and the productivity itself is good.

  When a mixture of ethylene glycol and diethylene glycol is used as the glycol (a), the ethylene glycol / diethylene glycol molar ratio is preferably 25-100 / 75-0, and has excellent compatibility with the cellulose ester. A cellulose ester modifier can be obtained. Furthermore, it is more preferably 25-40 / 75-60, and 60-95 / 40-5, and by adjusting to such a range, the crystallinity and melting point of the polyester are close to conventional ones, and are themselves Productivity is also improved.

  Next, examples of the dibasic acid (b) constituting these polyesters used in the present invention include succinic acid, glutaric acid, adipic acid, and sebacic acid. These may be used alone or in combination of two or more. For example, succinic acid or a mixture of succinic acid and terephthalic acid is particularly preferably used.

  Moreover, regarding the above-mentioned dibasic acid (b), it is important that the average carbon number of the dibasic acid (b) is in the range of 4 to 5.5. If the average number of carbon atoms of the dibasic acid (b) is less than 4, it is difficult to produce polyester, and if it is greater than 5.5, the cellulose ester modifier is inferior in compatibility with cellulose. It becomes a cellulose film inferior in physical properties such as properties. The dibasic acid (b) preferably has an average carbon number of 4.1 to 4.8 or 5.2 to 5.5, and by using the dibasic acid (b) in such a range, The crystallinity and melting point of the polyester are close to conventional ones, and the productivity and storage stability of the polyester itself are good.

  When a mixture of succinic acid and terephthalic acid is used as the dibasic acid (b), the molar ratio of succinic acid / terephthalic acid is preferably 25-100 / 75-0 and is in phase with the cellulose ester. A modifier for cellulose ester having excellent solubility can be obtained. Furthermore, it is more preferably 25-40 / 75-60, and 60-95 / 40-5, and by adjusting to such a range, the crystallinity and melting point of the polyester are close to those of conventional ones, Productivity is also improved.

  The glycol (a) and dibasic acid (b) constituting the polyester used in the present invention include combinations other than the above, but the average number of carbon atoms of the glycol (a) and the dibasic acid (b) The combination whose total with the average of carbon number is 6-7.5 is preferable.

  The polyester obtained from the glycol (a) and the dibasic acid (b) may have a number average molecular weight in the range of 1500 or more and 200,000 or less, more preferably 1500 to 5000 basically hydroxyl-terminated polyester. Those having a number average molecular weight of 1500 to 4000 are particularly preferably used. By using a polyester having a number average molecular weight in such a range, a plasticizer for cellulose ester having excellent compatibility with the cellulose ester can be obtained.

  In order to obtain the effects of the present invention, it is preferable to contain 10 to 30% by mass of the polyester having a number average molecular weight of 1500 or more in the film. More preferably, it is 10-20 mass%. When the number average molecular weight is larger than the above range, the compatibility is deteriorated and the effect of reducing moisture permeability is thin, but rather the retention property tends to be deteriorated. Therefore, the range of the number average molecular weight as described above is preferable. Actually, the content of the polymer in the film depends on the type of polymer and the weight average molecular weight, and the performance such as dimensional stability, retentivity, and transmittance is within the range in which dope, web, and phase separation do not occur after film formation. It is decided accordingly.

  On the other hand, the carboxyl group terminal in the polyester used in the present invention reduces the effect of improving the physical properties of the cellulose ester modifier of the present invention, so its content is the number of moles of 1/20 or less of the hydroxyl terminal. Preferably, it is more preferable to stop at 1/40 or less.

  In producing the above-described polyester, conventionally known esterification catalysts such as metal organic acid salts or metal chelate compounds such as titanium, zinc, lead and zirconium, or antimony oxide can be used. As the esterification catalyst, for example, tetraisopropyl titanate, tetrabutyl titanate and the like are preferably used, and 0.0005 to 0.02 mass relative to 100 mass parts in total of glycol (a) and dibasic acid (b) used. Are preferably used.

  Polycondensation of polyester is performed by a conventional method. For example, a direct reaction between the dibasic acid and glycol, the dibasic acid or an alkyl ester thereof, for example, a polyesterification reaction or transesterification reaction between a dibasic acid methyl ester and a glycol, or a hot melt condensation method, Alternatively, it can be easily synthesized by any method of dehydrohalogenation reaction between acid chloride of these acids and glycol, but it is preferable that polyester having a number average molecular weight not so large is by direct reaction. Polyester having a high distribution on the low molecular weight side has very good compatibility with the cellulose ester, and after forming the film, it is possible to obtain a cellulose ester film having low moisture permeability and high transparency. A conventional method can be used as the molecular weight adjusting method without any particular limitation. For example, although depending on the polymerization conditions, the method can be controlled by the amount of addition of these monovalent ones by blocking the molecular ends with a monovalent acid or monovalent alcohol. In this case, a monovalent acid is preferable from the viewpoint of polymer stability. For example, acetic acid, propionic acid, butyric acid, pivalic acid, benzoic acid, and the like can be mentioned. However, during the polycondensation reaction, such monovalent acid is not removed from the system but stopped. Those which are easy to be distilled off when being removed from the system are selected, but these may be mixed and used. In the case of direct reaction, the number average molecular weight can also be adjusted by measuring the timing at which the reaction is stopped by the amount of water distilled off during the reaction. In addition, it can be adjusted by biasing the number of moles of glycol or dibasic acid to be charged or by controlling the reaction temperature.

  The content of the polyester according to the present invention is preferably 1 to 20% by mass, particularly preferably 3 to 11% by mass, in the cellulose ester film.

(Polyhydric alcohol ester)
The polyhydric alcohol ester used in the present invention comprises an ester of a dihydric or higher aliphatic polyhydric alcohol and a monocarboxylic acid, and preferably has an aromatic ring or a cycloalkyl ring in the molecule.

  The polyhydric alcohol used is represented by the following general formula (I).

Formula (I)
R _1- (OH) _n
In the formula, R ₁ represents an n-valent organic group, n represents a positive integer of 2 or more, and the OH group represents an alcoholic or phenolic hydroxyl group.

  Examples of preferred polyhydric alcohols include the following, but the present invention is not limited to these. Adonitol, arabitol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, 1,2-butanediol, 1,3- Butanediol, 1,4-butanediol, dibutylene glycol, 1,2,4-butanetriol, pentaerythritol, 1,5-pentanediol, 1,6-hexanediol, hexanetriol, galactitol, mannitol, 3- Examples thereof include methylpentane-1,3,5-triol, pinacol, dipentaerythritol, sorbitol, trimethylolpropane, trimethylolethane, xylitol and the like. Of these, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, sorbitol, trimethylolpropane, and xylitol are preferable.

  There is no restriction | limiting in particular as monocarboxylic acid used for the polyhydric alcohol ester concerning this invention, Well-known aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, aromatic monocarboxylic acid, etc. can be used. Use of an alicyclic monocarboxylic acid or aromatic monocarboxylic acid is preferable in terms of improving moisture permeability and retention. Examples of preferred monocarboxylic acids include the following, but the present invention is not limited thereto.

  As the aliphatic monocarboxylic acid, a fatty acid having a straight chain or a side chain having 1 to 32 carbon atoms can be preferably used. It is more preferable that it is C1-C20, and it is especially preferable that it is C1-C10. The use of acetic acid is preferred because the compatibility with the cellulose ester is increased, and it is also preferred to use a mixture of acetic acid and another monocarboxylic acid.

  Preferred aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanecarboxylic acid, undecylic acid, lauric acid, tridecylic acid , Saturated fatty acids such as myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicic acid, and laccelic acid, undecylenic acid, Examples thereof include unsaturated fatty acids such as oleic acid, sorbic acid, linoleic acid, linolenic acid and arachidonic acid. Examples of preferable alicyclic monocarboxylic acids include cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, cyclooctanecarboxylic acid, and derivatives thereof. Examples of preferred aromatic monocarboxylic acids include those in which an alkyl group is introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, and two or more benzene rings such as biphenyl carboxylic acid, naphthalene carboxylic acid, and tetralin carboxylic acid. Aromatic monocarboxylic acids possessed by them, or derivatives thereof. In particular, benzoic acid is preferred.

  The molecular weight of the polyhydric alcohol ester is preferably in the range of 300 to 1500, and more preferably in the range of 350 to 750. A higher molecular weight is preferred because it is less likely to volatilize, and a smaller one is preferred in terms of moisture permeability and compatibility with cellulose ester. The carboxylic acid used for the polyhydric alcohol ester may be one kind or a mixture of two or more kinds. Moreover, all the OH groups in the polyhydric alcohol may be esterified, or a part of the OH groups may be left as they are. The specific compound of a polyhydric alcohol ester is shown below.

  The content of the polyhydric alcohol ester according to the present invention is preferably 1 to 15% by mass, particularly preferably 3 to 10% by mass in the cellulose ester film.

(Aromatic terminal ester represented by the general formula (1))
Although it does not specifically limit as a preferable aromatic terminal ester in this invention, For example, it can represent with following General formula (1).

General formula (1)
B- (GA) n-GB
In the formula, B is a benzene monocarboxylic acid residue, G is an alkylene glycol residue having 2 to 12 carbon atoms, an aryl glycol residue having 6 to 12 carbon atoms, or an oxyalkylene glycol residue having 4 to 12 carbon atoms, A Represents an alkylene dicarboxylic acid residue having 4 to 12 carbon atoms or an aryl dicarboxylic acid residue having 6 to 12 carbon atoms, and n represents an integer of 1 or more.

  These aromatic terminal esters are represented by the benzene monocarboxylic acid residue represented by B and the alkylene glycol residue, oxyalkylene glycol residue or aryl glycol residue represented by G, or A in the general formula (1). It is composed of an alkylene dicarboxylic acid residue or an aryl dicarboxylic acid residue, and can be obtained by the same reaction as a normal polyester plasticizer.

  Examples of the benzene monocarboxylic acid component of the aromatic terminal ester used in the present invention include benzoic acid, para-tert-butylbenzoic acid, orthotoluic acid, metatoluic acid, p-toluic acid, dimethylbenzoic acid, ethylbenzoic acid, and normalpropyl. There exist benzoic acid, aminobenzoic acid, acetoxybenzoic acid, etc., and these can be used as 1 type, or 2 or more types of mixtures, respectively.

  Examples of the alkylene glycol component having 2 to 12 carbon atoms of the aromatic terminal ester according to the present invention include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, and 1,3-butane. Diol, 1,2-propanediol, 2-methyl 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol) 2,2-diethyl-1,3-propanediol (3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3-propanediol (3,3-dimethylolheptane), 3- Methyl-1,5-pentanediol 1,6-hexanediol, 2,2,4-trimethyl 1,3-pentanediol, 2 Examples include ethyl 1,3-hexanediol, 2-methyl 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-octadecanediol, and the like. Used as a mixture of two or more. In particular, an alkylene glycol having 2 to 12 carbon atoms is particularly preferable because of excellent compatibility with a cellulose ester.

  Examples of the oxyalkylene glycol component having 4 to 12 carbon atoms of these aromatic terminal esters include diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, and the like. It can be used as a seed or a mixture of two or more.

  Examples of the alkylene dicarboxylic acid component having 4 to 12 carbon atoms of these aromatic terminal esters include succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, and dodecanedicarboxylic acid. These are used as one kind or a mixture of two or more kinds, respectively. Examples of the arylene dicarboxylic acid component having 6 to 12 carbon atoms include phthalic acid, terephthalic acid, isophthalic acid, 1,5 naphthalene dicarboxylic acid, and 1,4 naphthalene dicarboxylic acid.

  The aromatic terminal ester used in the present invention has a number average molecular weight of preferably 300 to 1500, more preferably 400 to 1000. The acid value is preferably 0.5 mgKOH / g or less, the hydroxyl value is 25 mgKOH / g or less, more preferably the acid value is 0.3 mgKOH / g or less, and the hydroxyl value is 15 mgKOH / g or less.

  Hereafter, the synthesis example of the aromatic terminal ester which concerns on this invention is shown.

<Sample No. 1 (Aromatic terminal ester sample)>
A reaction vessel was charged with 410 parts of phthalic acid, 610 parts of benzoic acid, 737 parts of dipropylene glycol, and 0.40 part of tetraisopropyl titanate as a catalyst. While refluxing the monohydric alcohol, heating was continued at 130 to 250 ° C. until the acid value became 2 or less, and water produced was continuously removed. Subsequently, the distillate was removed at 200 to 230 ° C. under a reduced pressure of 100 to finally 4.00 MPa, and then filtered to obtain an aromatic terminal polyester having the following properties.

Viscosity (25 ° C., mPa · s); 43400
Acid value: 0.2
<Sample No. 2 (Aromatic terminal ester sample)>
Sample No. 1 was used except that 410 parts of phthalic acid, 610 parts of benzoic acid, 341 parts of ethylene glycol, and 0.35 part of tetraisopropyl titanate as a catalyst were used in the reaction vessel. In the same manner as in No. 1, an aromatic terminal ester having the following properties was obtained.

Viscosity (25 ° C., mPa · s); 31000
Acid value: 0.1
<Sample No. 3 (Aromatic terminal ester sample)>
Sample No. 1 was used except that 410 parts of phthalic acid, 610 parts of benzoic acid, 418 parts of 1,2-propanediol, and 0.35 part of tetraisopropyl titanate as the catalyst were used in the reaction vessel. In the same manner as in No. 1, an aromatic terminal ester having the following properties was obtained.

Viscosity (25 ° C., mPa · s); 38000
Acid value: 0.05
<Sample No. 4 (Aromatic terminal ester sample)>
Sample No. 4 was used except that 410 parts of phthalic acid, 610 parts of benzoic acid, 418 parts of 1,3-propanediol, and 0.35 part of tetraisopropyl titanate as a catalyst were used in the reaction vessel. In the same manner as in No. 1, an aromatic terminal ester having the following properties was obtained.

Viscosity (25 ° C., mPa · s); 37000
Acid value: 0.05
<Sample No. 5 (Aromatic terminal ester sample)>
Sample No. 1 was used except that 146 parts of succinic acid, 610 parts of benzoic acid, 737 parts of dipropylene glycol, and 0.35 part of tetraisopropyl titanate as a catalyst were used in the reaction vessel. In the same manner as in No. 1, an aromatic terminal ester having the following properties was obtained.

Viscosity (25 ° C., mPa · s); 45100
Acid value: 0.1
<Sample No. 6 (Aromatic terminal ester sample)>
Sample No. 1 was used except that 146 parts of succinic acid, 610 parts of benzoic acid, 341 parts of ethylene glycol, and 0.35 part of tetraisopropyl titanate as a catalyst were used in the reaction vessel. In the same manner as in No. 1, an aromatic terminal ester having the following properties was obtained.

Viscosity (25 ° C., mPa · s); 41600
Acid value: 0.1
<Sample No. 7 (Aromatic terminal ester sample)>
Sample No. 1 was used except that 146 parts of succinic acid, 610 parts of benzoic acid, 418 parts of 1,2-propanediol, and 0.35 part of tetraisopropyl titanate as a catalyst were used in the reaction vessel. In the same manner as in No. 1, an aromatic terminal ester having the following properties was obtained.

Viscosity (25 ° C., mPa · s); 48500
Acid value: 0.05
<Sample No. 8 (Aromatic terminal ester sample)>
Sample No. 1 was used except that 146 parts of succinic acid, 610 parts of benzoic acid, 418 parts of 1,3-propanediol, and 0.35 part of tetraisopropyl titanate as a catalyst were used in the reaction vessel. In the same manner as in No. 1, an aromatic terminal ester having the following properties was obtained.

Viscosity (25 ° C., mPa · s); 47200
Acid value: 0.1
In the above, the viscosity was measured with a BH type rotational viscometer according to JIS K 6833. The acid value was measured according to JIS K0070.

  Although the specific compound of an aromatic terminal ester plasticizer is shown below, this invention is not limited to this.

  The content of the aromatic terminal ester according to the present invention is preferably 1 to 20% by mass, particularly preferably 3 to 11% by mass in the cellulose ester film.

  The total content of the polyester according to the present invention, the polyhydric alcohol ester, and the aromatic terminal polyester is preferably 5 to 20% by mass, particularly preferably 7 to 15% by mass in the cellulose ester film.

(UV absorber)
The polarizing plate protective film and other films used in the liquid crystal image display device contain an ultraviolet absorber, and the ultraviolet absorber serves to prevent deterioration of the liquid crystal and the polarizing film when used outdoors. In the present invention, an ultraviolet absorber is preferably used. As the ultraviolet absorber, those excellent in performance of absorbing ultraviolet rays having a wavelength of 370 nm or less and having as little absorption of visible light as possible with a wavelength of 400 nm or more are preferably used. In particular, the transmittance at a wavelength of 370 nm needs to be 10% or less, preferably 5% or less, more preferably 2% or less. Examples of the ultraviolet absorber that can be used in the present invention include oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex compounds, and the like. A benzotriazole-based compound with little coloring is preferable. Benzotriazole ultraviolet absorbers and benzophenone ultraviolet absorbers having stability against light are preferable, and benzotriazole ultraviolet absorbers with less unnecessary coloring are particularly preferable. For example, TINUVIN109 (UV-1), TINUVIN171, TINUVIN326, TINUVIN327, and TINUVIN328 manufactured by Ciba Specialty Chemicals Co., Ltd. can be preferably used. In addition, the amount added may be 3 to 10% by mass because it may deposit on the web or volatilize during film formation.

  In the present invention, it is more preferable that a high molecular weight ultraviolet absorber that is less likely to precipitate than the above low molecular weight ultraviolet absorber is contained in the cellulose ester film together with the polymer according to the present invention. Ultraviolet rays can be sufficiently cut in a stable state without impairing the wetness and without phase separation in the film. As the polymer ultraviolet absorber useful in the present invention, the polymer ultraviolet absorber described in JP-A-6-148430 and a polymer containing an ultraviolet absorber monomer can be used without limitation.

  In particular, the present invention preferably contains an ultraviolet-absorbing copolymer (polymer ultraviolet absorber) synthesized from the ultraviolet-absorbing monomer represented by the general formula (2).

In the general formula (2), n represents an integer of 0 to 3, and when n is 2 or more, the plurality of R ₅ may be the same or different, and may be connected to each other to form 5 to 7 A member ring may be formed.

R _{1 to} R ₅ each represents a hydrogen atom, a halogen atom or a substituent. As a halogen atom, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom etc. are mentioned, for example, Preferably they are a fluorine atom and a chlorine atom. Examples of the substituent include an alkyl group (for example, methyl group, ethyl group, isopropyl group, hydroxyethyl group, methoxymethyl group, trifluoromethyl group, t-butyl group), alkenyl group (for example, vinyl group). , Allyl group, 3-buten-1-yl group, etc.), aryl group (eg, phenyl group, naphthyl group, p-tolyl group, p-chlorophenyl group, etc.), heterocyclic group (eg, pyridyl group, benzimidazolyl group) , Benzthiazolyl group, benzoxazolyl group, etc.), alkoxy group (eg methoxy group, ethoxy group, isopropoxy group, n-butoxy group etc.), aryloxy group (eg phenoxy group etc.), heterocyclic oxy group (eg For example, 1-phenyltetrazol-5-oxy group, 2-tetrahydropyranyloxy group, etc.), Ruoxy group (for example, acetoxy group, pivaloyloxy group, benzoyloxy group, etc.), acyl group (for example, acetyl group, propanoyl group, butyroyl group, etc.), alkoxycarbonyl group (for example, methoxycarbonyl group, ethoxycarbonyl group, etc.), aryl Oxycarbonyl group (for example, phenoxycarbonyl group), carbamoyl group (for example, methylcarbamoyl group, ethylcarbamoyl group, dimethylcarbamoyl group, etc.), amino group, alkylamino group (for example, methylamino group, ethylamino group, diethylamino group) Anilino group (for example, anilino group, N-methylanilino group, etc.), acylamino group (for example, acetylamino group, propionylamino group, etc.), hydroxyl group, cyano group, nitro group, sulfonamide (Eg, methanesulfonamide group, benzenesulfonamide group, etc.), sulfamoylamino group (eg, dimethylsulfamoylamino group, etc.), sulfonyl group (eg, methanesulfonyl group, butanesulfonyl group, phenylsulfonyl group, etc.) , Sulfamoyl group (eg, ethylsulfamoyl group, dimethylsulfamoyl group, etc.), sulfonylamino group (eg, methanesulfonylamino group, benzenesulfonylamino group, etc.), ureido group (eg, 3-methylureido group, 3 , 3-dimethylureido group, 1,3-dimethylureido group etc.), imide group (eg phthalimide group etc.), silyl group (eg trimethylsilyl group, triethylsilyl group, t-butyldimethylsilyl group etc.), alkylthio group (Eg methylthio Group, ethylthio group, n-butylthio group and the like), arylthio group (for example, phenylthio group and the like), and the like, preferably an alkyl group and an aryl group.

In General Formula (2), when each group represented by R _{1 to} R ₅ is a further substitutable group, it may further have a substituent, and adjacent R _{1 to} R ₄ are They may be connected to each other to form a 5- to 7-membered ring.

R ₆ represents a hydrogen atom, an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic ring. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, n- Examples thereof include a butyl group, an isobutyl group, a t-butyl group, an amyl group, an isoamyl group, and a hexyl group. The alkyl group may further have a halogen atom or a substituent, and examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Examples of the substituent include An aryl group (eg, phenyl group, naphthyl group, p-tolyl group, p-chlorophenyl group, etc.), acyl group (eg, acetyl group, propanoyl group, butyroyl group, etc.), alkoxy group (eg, methoxy group, ethoxy group, Isopropoxy group, n-butoxy group, etc.), aryloxy group (eg, phenoxy group, etc.), amino group, alkylamino group (eg, methylamino group, ethylamino group, diethylamino group etc.), anilino group (eg, anilino group) Group, N-methylanilino group, etc.), acylamino group (for example, acetylamino group, propioni) Amino group, etc.), hydroxyl group, cyano group, carbamoyl group (eg, methylcarbamoyl group, ethylcarbamoyl group, dimethylcarbamoyl group, etc.), acyloxy group (eg, acetoxy group, pivaloyloxy group, benzoyloxy group, etc.), alkoxycarbonyl group (For example, a methoxycarbonyl group, an ethoxycarbonyl group, etc.) and an aryloxycarbonyl group (for example, a phenoxycarbonyl group, etc.) are mentioned.

  Examples of the cycloalkyl group include saturated cyclic hydrocarbons such as a cyclopentyl group, a cyclohexyl group, a norbornyl group, and an adamantyl group, which may be unsubstituted or substituted.

  Examples of the alkenyl group include a vinyl group, an allyl group, a 1-methyl-2-propenyl group, a 3-butenyl group, a 2-butenyl group, a 3-methyl-2-butenyl group, and an oleyl group. Is a vinyl group, 1-methyl-2-propenyl group.

  Examples of the alkynyl group include ethynyl group, butadiyl group, phenylethynyl group, propargyl group, 1-methyl-2-propynyl group, 2-butynyl group, 1,1-dimethyl-2-propynyl group, Preferably, they are an ethynyl group and a propargyl group.

  Examples of the aryl group include a phenyl group, a naphthyl group, and an anthranyl group. The aryl group may further have a halogen atom or a substituent. Examples of the halogen atom include a fluorine atom and chlorine. Atoms, bromine atoms, iodine atoms and the like. Examples of the substituent include alkyl groups (for example, methyl group, ethyl group, isopropyl group, hydroxyethyl group, methoxymethyl group, trifluoromethyl group, t-butyl group). Etc.), acyl groups (eg acetyl group, propanoyl group, butyroyl group etc.), alkoxy groups (eg methoxy group, ethoxy group, isopropoxy group, n-butoxy group etc.), aryloxy groups (eg phenoxy group etc.) ), Amino group, alkylamino group (for example, methylamino group, ethylamino group, diethyl) Mino group etc.), anilino group (eg anilino group, N-methylanilino group etc.), acylamino group (eg acetylamino group, propionylamino group etc.), hydroxyl group, cyano group, carbamoyl group (eg methylcarbamoyl group, Ethylcarbamoyl group, dimethylcarbamoyl group, etc.), acyloxy group (eg, acetoxy group, pivaloyloxy group, benzoyloxy group, etc.), alkoxycarbonyl group (eg, methoxycarbonyl group, ethoxycarbonyl group, etc.), aryloxycarbonyl group (eg, Phenoxycarbonyl group and the like).

Examples of the heterocyclic group include a pyridyl group, a benzimidazolyl group, a benzthiazolyl group, and a benzoxazolyl group. R ₆ is preferably an alkyl group.

In the formula (2), X is _{-COO -, - CONR 7 -,} - OCO- or an -NR ₇ CO-.

R ₇ represents a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group or a heterocyclic group, and examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, Examples thereof include a t-butyl group, an amyl group, an isoamyl group, and a hexyl group. Such an alkyl group may further have a halogen atom or a substituent. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Examples of the substituent include an aryl group. Group (for example, phenyl group, naphthyl group, p-tolyl group, p-chlorophenyl group, etc.), acyl group (for example, acetyl group, propanoyl group, butyroyl group, etc.), alkoxy group (for example, methoxy group, ethoxy group, iso group) Propoxy group, n-butoxy group, etc.), aryloxy group (eg, phenoxy group, etc.), amino group, alkylamino group (eg, methylamino group, ethylamino group, diethylamino group, etc.), anilino group (eg, anilino group) N-methylanilino group), acylamino group (for example, acetylamino group, propionyl) Mino group, etc.), hydroxyl group, cyano group, carbamoyl group (eg, methylcarbamoyl group, ethylcarbamoyl group, dimethylcarbamoyl group, etc.), acyloxy group (eg, acetoxy group, pivaloyloxy group, benzoyloxy group, etc.), alkoxycarbonyl group (For example, a methoxycarbonyl group, an ethoxycarbonyl group, etc.) and an aryloxycarbonyl group (for example, a phenoxycarbonyl group, etc.) are mentioned.

  Examples of the cycloalkyl group include saturated cyclic hydrocarbons such as a cyclopentyl group, a cyclohexyl group, a norbornyl group, and an adamantyl group, which may be unsubstituted or substituted.

  Examples of the aryl group include a phenyl group, a naphthyl group, and an anthranyl group. The aryl group may further have a halogen atom or a substituent, and the halogen atom includes a fluorine atom, a chlorine atom, Examples of the substituent include an alkyl group (for example, methyl group, ethyl group, isopropyl group, hydroxyethyl group, methoxymethyl group, trifluoromethyl group, t-butyl group). An acyl group (for example, acetyl group, propanoyl group, butyroyl group, etc.), an alkoxy group (for example, methoxy group, ethoxy group, isopropoxy group, n-butoxy group, etc.), an aryloxy group (for example, phenoxy group, etc.), Amino group, alkylamino group (for example, methylamino group, ethylamino group, diethylamino group) ), Anilino group (for example, anilino group, N-methylanilino group, etc.), acylamino group (for example, acetylamino group, propionylamino group, etc.), hydroxyl group, cyano group, carbamoyl group (for example, methylcarbamoyl group, ethylcarbamoyl group) Group, dimethylcarbamoyl group, etc.), acyloxy group (eg acetoxy group, pivaloyloxy group, benzoyloxy group etc.), alkoxycarbonyl group (eg methoxycarbonyl group, ethoxycarbonyl group etc.), aryloxycarbonyl group (eg phenoxycarbonyl) Group).

Examples of the heterocyclic group include a pyridyl group, a benzimidazolyl group, a benzthiazolyl group, and a benzoxazolyl group. R ₇ is preferably a hydrogen atom.

  The polymerizable group referred to in the present invention means an unsaturated ethylene-based polymerizable group or a bifunctional polycondensable group, and preferably an unsaturated ethylene-based polymerizable group. Specific examples of the unsaturated ethylene polymerizable group include vinyl group, allyl group, acryloyl group, methacryloyl group, styryl group, acrylamide group, methacrylamide group, vinyl cyanide group, 2-cyanoacryloxy group, 1,2 -An epoxy group, a vinylbenzyl group, a vinyl ether group and the like can be mentioned, and a vinyl group, an acryloyl group, a methacryloyl group, an acrylamide group, and a methacrylamide group are preferable. Moreover, having a polymerizable group as a partial structure means that the polymerizable group is bonded directly or by a divalent or higher valent linking group, and the divalent or higher valent linking group is, for example, an alkylene group. (Eg, methylene, 1,2-ethylene, 1,3-propylene, 1,4-butylene, cyclohexane-1,4-diyl, etc.), alkenylene groups (eg, ethene-1,2-diyl, butadiene-1, 4-diyl, etc.), alkynylene groups (eg, ethyne-1,2-diyl, butane-1,3-diyne-1,4-diyl, etc.), linking groups derived from compounds containing at least one aromatic group (Eg, substituted or unsubstituted benzene, condensed polycyclic hydrocarbons, aromatic heterocycles, aromatic hydrocarbon ring assemblies, aromatic heterocycle assemblies, etc.), heteroatom linking groups (oxygen, sulfur, nitrogen, silicon Although such phosphorus atoms) are exemplified, preferably an alkylene group and a group linking a heteroatom. These linking groups may be further combined to form a composite group. The polymer derived from the ultraviolet absorbing monomer preferably has a weight average molecular weight of 2,000 to 30,000, more preferably 5,000 to 20,000.

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

  The UV-absorbing polymer used in the present invention may be a homopolymer of only an UV-absorbing monomer or a copolymer with other polymerizable monomer, but other polymerizable properties capable of copolymerization are also available. Examples of the monomer include a styrene derivative (for example, styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, vinylnaphthalene, etc.), an acrylate derivative (for example, methyl acrylate, acrylic Ethyl acrylate, propyl acrylate, butyl acrylate, i-butyl acrylate, t-butyl acrylate, octyl acrylate, cyclohexyl acrylate, benzyl acrylate, etc.), methacrylate derivatives (eg, methyl methacrylate, methacrylic acid) Ethyl, propyl methacrylate, butyl methacrylate, I-butyl crylate, t-butyl methacrylate, octyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, etc.), alkyl vinyl ethers (eg, methyl vinyl ether, ethyl vinyl ether, butyl vinyl ether, etc.), alkyl vinyl esters (eg, vinyl formate) , Vinyl acetate, vinyl butyrate, vinyl caproate, vinyl stearate, etc.), crotonic acid, maleic acid, fumaric acid, itaconic acid, acrylonitrile, methacrylonitrile, vinyl chloride, vinylidene chloride, acrylamide, methacrylamide, etc. Is mentioned. Preferred are methyl acrylate, methyl methacrylate, and vinyl acetate.

  It is also preferred that the copolymer component other than the ultraviolet absorbing monomer in the polymer derived from the ultraviolet absorbing monomer contains at least one hydrophilic ethylenically unsaturated monomer.

  The hydrophilic ethylenically unsaturated monomer is not particularly limited as long as it is hydrophilic and has an unsaturated double bond polymerizable in the molecule. For example, unsaturated carboxylic acid such as acrylic acid or methacrylic acid. Or acrylic acid or methacrylic acid ester having a hydroxyl group or an ether bond (for example, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, tetrahydrofurfuryl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl acrylate, Hydroxypropyl, 2,3-dihydroxy-2-methylpropyl methacrylate, tetrahydrofurfuryl acrylate, 2-ethoxyethyl acrylate, diethylene glycol ethoxylate acrylate, 3-methoxybutyl acrylate, etc.), acrylamide, N, - dimethyl (meth) acrylamide, (N- substituted) (meth) acrylamide, N- vinylpyrrolidone, N- vinyloxazolidone and the like.

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

  These polymerizable monomers can be used alone or in combination of two or more to be copolymerized with the ultraviolet absorbing monomer.

  Although the polymerization method of the ultraviolet-absorbing copolymer used in the present invention is not particularly limited, conventionally known methods can be widely employed, and examples thereof include radical polymerization, anionic polymerization, and cationic polymerization. Examples of radical polymerization initiators include azo compounds and peroxides, and examples include azobisisobutyronitrile (AIBN), azobisisobutyric acid diester derivatives, benzoyl peroxide, and hydrogen peroxide. . 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, and amide solvents such as dimethylformamide. And alcohol solvents such as methanol, ester solvents such as methyl acetate and ethyl acetate, ketone solvents such as acetone, cyclohexanone and methyl ethyl ketone, and water solvents. Depending on the selection of the solvent, solution polymerization for polymerization in a homogeneous system, precipitation polymerization for precipitation of the produced polymer, emulsion polymerization for polymerization in a micelle state, and suspension polymerization for polymerization in a suspension state can also be performed. However, the ultraviolet-absorbing latex obtained by emulsion polymerization is not suitable for optical film applications.

  The use ratio of the above-mentioned UV-absorbing monomer, polymerizable monomer copolymerizable therewith and hydrophilic ethylenically unsaturated monomer is the compatibility of the obtained UV-absorbing copolymer polymer with other transparent polymers, It is appropriately selected in consideration of the influence on transparency and mechanical strength.

  The content of the ultraviolet absorbing monomer in the polymer derived from the ultraviolet absorbing monomer is preferably 1 to 70% by mass, and more preferably 5 to 60% by mass. When the content of the ultraviolet monomer in the ultraviolet absorbing polymer is less than 1% by mass, a large amount of the ultraviolet absorbing polymer must be used when trying to satisfy the desired ultraviolet absorbing performance. As a result, the transparency is lowered and the film strength is lowered. On the other hand, when the content of the ultraviolet monomer in the ultraviolet absorbing polymer exceeds 70% by mass, the compatibility with other polymers is lowered, so that a transparent optical film cannot be obtained. Moreover, the solubility with respect to a solvent becomes low, and the workability | operativity and productivity at the time of film preparation are inferior.

  It is preferable that 0.1-50 mass% of hydrophilic ethylenically unsaturated monomers are contained in the said ultraviolet absorptive copolymer. If it is 0.1% by mass or less, the effect of improving the compatibility with the hydrophilic ethylenically unsaturated monomer does not appear, and if it exceeds 50% by mass, it is difficult to isolate and purify the copolymer. A more preferable content of the hydrophilic ethylenically unsaturated monomer is 0.5 to 20% by mass. 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 UV-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.

  Two or more kinds of UV-absorbing monomers and (non) hydrophilic ethylenically unsaturated monomers may be mixed and copolymerized.

  Hereinafter, representative examples of the ultraviolet absorbing monomer preferably used in the present invention are exemplified, but the invention is not limited thereto.

  The ultraviolet absorbent, ultraviolet absorbent monomer and intermediate thereof used in the present invention can be synthesized with reference to known literature. For example, U.S. Pat. Nos. 3,072,585, 3,159,646, 3,399,173, 3,761,272, 4,028,331, 5,683,861 No., European Patent No. 86,300,416, JP-A Nos. 63-227575, 63-185969, Polymer Bulletin. V. 20 (2), 169-176, and Chemical Abstracts V.I. 109, no. 191389 and the like can be synthesized.

  The ultraviolet absorbent and ultraviolet absorbent polymer used in the present invention can be used together with a low molecular compound, a high molecular compound, an inorganic compound, or the like, if necessary, when mixed with another transparent polymer. For example, the ultraviolet absorber used in the present invention and other low molecular ultraviolet absorbers are simultaneously mixed with another transparent polymer, or the ultraviolet absorbent polymer and other low molecular ultraviolet absorber used in the present invention are mixed, It is also one of preferred embodiments to mix with another transparent polymer at the same time. Similarly, it is one of preferred embodiments to simultaneously mix additives such as an antioxidant, a plasticizer, and a flame retardant.

  The method for adding the ultraviolet absorber and the ultraviolet absorbing polymer used in the present invention to the optical film may be contained in the optical film or applied onto the optical film. When it is contained in the optical film, it may be added directly, but in-line addition with excellent productivity is preferred. In-line addition is a method in which an in-line mixer or the like is added to the dope composition after dissolving in advance in an organic solvent (for example, methanol, ethanol, methylene chloride, etc.).

The amount of the ultraviolet absorber and the ultraviolet absorbing polymer used in the present invention is not uniform depending on the type of compound, the usage conditions, etc., but in the case of an ultraviolet absorber, 0.2 to 3 per 1 m 2 of the optical film. 0.0 g is preferable, 0.4 to 2.0 is more preferable, and 0.5 to 1.5 is particularly preferable. Moreover, when it is a ultraviolet absorption polymer, 0.6-9.0g per 1 m < ² > of optical films is preferable, 1.2-6.0 are still more preferable, 1.5-3.0 are especially preferable.

  Furthermore, from the viewpoint of preventing liquid crystal deterioration, those having excellent ultraviolet absorption performance at a wavelength of 380 nm or less and low visible light absorption of 400 nm or more are preferable from the viewpoint of good liquid crystal display properties. In the present invention, the transmittance at a wavelength of 380 nm is particularly preferably 8% or less, more preferably 4% or less, and particularly preferably 1% or less.

  As a commercially available ultraviolet absorber monomer that can be used in the present invention, 1- (2-benzotriazole) -2-hydroxy-5- (2-methacryloyl) of a reactive ultraviolet absorber RUVA-93 manufactured by Otsuka Chemical Co., Ltd. Oxyethyl) benzene or similar compounds. A polymer or copolymer obtained by singly or copolymerizing these is also preferably used, but is not limited thereto. For example, as a commercially available polymer ultraviolet absorber, PUVA-30M manufactured by Otsuka Chemical Co., Ltd. is preferably used. Two or more kinds of ultraviolet absorbers may be used. The ultraviolet absorber may be added to the dope after the ultraviolet absorber is dissolved in an organic solvent such as alcohol, methylene chloride, dioxolane, or methyl acetate, or may be added directly into the dope composition.

  Moreover, the cellulose ester film of the present invention may contain an antioxidant. For example, it may contain a peroxide decomposing agent, a radical chain inhibitor, a metal deactivator or an acid scavenger as described in JP-A-5-197073. The amount of these compounds added is preferably 1 ppm to 1.0%, more preferably 10 to 1000 ppm in terms of mass ratio with respect to the cellulose ester.

  In the present invention, the cellulose ester film preferably contains a fine particle matting agent. Examples of the fine particle matting agent include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, kaolin, talc, and baking. It is preferable to contain inorganic fine particles such as calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, calcium phosphate, and crosslinked polymer fine particles. Of these, silicon dioxide is preferable because it can reduce the haze of the film. The average particle size of the secondary particles of the fine particles is in the range of 0.01 to 1.0 μm, and the content is preferably 0.005 to 0.3% by mass with respect to the cellulose ester. In many cases, fine particles such as silicon dioxide are surface-treated with an organic material, but such a material is preferable because it can reduce the haze of the film. Preferred organic substances for the surface treatment include halosilanes, alkoxysilanes (particularly alkoxysilanes having a methyl group), silazane, siloxane and the like. The larger the average particle size of the fine particles, the greater the mat effect, and on the contrary, the smaller the average particle size, the better the transparency. Therefore, the average particle size of the preferred primary particles is 5 to 50 nm, more preferably 7 to 16 nm. It is. These fine particles are usually present as aggregates in the cellulose ester film, and it is preferable to form irregularities of 0.01 to 1.0 μm on the surface of the cellulose ester film. As the fine particles of silicon dioxide, AEROSIL 200, 200V, 300, R972, R972V, R974, R202, R812, OX50, TT600, etc. manufactured by Aerosil Co., Ltd. can be mentioned, preferably AEROSIL 200V, R972, R972V, R974, R202 and R812. Two or more of these matting agents may be used in combination. When using 2 or more types together, it can mix and use in arbitrary ratios. In this case, matting agents having different average particle sizes and materials, for example, AEROSIL 200V and R972V can be used in a mass ratio of 0.1: 99.9 to 99.9 to 0.1.

  Next, the manufacturing method of the cellulose-ester film of this invention is described.

  A method for preparing a cellulose ester dope in the present invention will be described. The dough is formed by dissolving the flaky cellulose ester in an organic solvent mainly containing a good solvent for the cellulose ester in a dissolving kettle while stirring. For dissolution, a method carried out at normal pressure, a method carried out below the boiling point of the main solvent, a method carried out under pressure above the boiling point of the main solvent, JP-A-9-95544, 9-95557 or 9-95538 There are various dissolution methods, such as a method performed by the cooling dissolution method as described in JP-A No. 11-21379, and a method performed at a high pressure as described in JP-A No. 11-21379. After dissolution, the dope is filtered with a filter medium, defoamed, and sent to the next process with a pump. The concentration of the cellulose ester in the dope is about 10 to 35% by mass. More preferably, it is 15-25 mass%. In order to contain the polymer useful in the present invention in the cellulose ester dope, the addition method such as addition after dissolving the polymer in an organic solvent in advance or direct addition to the cellulose ester dope can be carried out without limitation. In this case, the polymer is added so as not to become cloudy or phase-separated in the dope. The amount added is as described above.

  Examples of organic solvents as good solvents for cellulose esters include methyl acetate, ethyl acetate, amyl acetate, ethyl formate, acetone, cyclohexanone, methyl acetoacetate, tetrahydrofuran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, 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, Nitroethane, 2-pyrrolidone, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, methylene chloride, Etc. can be mentioned Romopuropan, methyl acetate, acetone, are preferably used methylene chloride. However, non-chlorine organic solvents tend to be preferable due to recent environmental problems. In addition, it is preferable to use a lower alcohol such as methanol, ethanol or butanol in combination with these organic solvents because the solubility of the cellulose ester in the organic solvent can be improved and the dope viscosity can be reduced. In particular, ethanol having a low boiling point and low toxicity is preferred. The organic solvent used for the dope according to the present invention is preferably used by mixing a good solvent and a poor solvent of cellulose ester from the viewpoint of production efficiency, and the preferable range of the mixing ratio of the good solvent and the poor solvent is good. The solvent is 70 to 98% by mass, and the poor solvent is 2 to 30% by mass. With the good solvent and the poor solvent used in the present invention, those that dissolve the cellulose ester used alone are defined as good solvents, and those that do not dissolve alone are defined as poor solvents. Although it does not specifically limit as a poor solvent used for dope concerning this invention, For example, methanol, ethanol, n-butanol, cyclohexane, acetone, cyclohexanone etc. can be used preferably. For the ester plasticizer useful in the present invention, the organic solvent is preferably selected using a good solvent for cellulose ester. As described above, when using a low molecular plasticizer, it can be carried out by a normal addition method, either directly added into the dope, or dissolved in an organic solvent in advance and poured into the dope. Good.

  In the present invention, when various additives as described above are added to the cellulose ester dope, the cellulose ester dope and various additives can be added in-line to a solution in which a small amount of cellulose ester is dissolved and mixed. preferable. For example, it is preferable to use an in-line mixer such as a static mixer SWJ (Toray static type in-pipe mixer Hi-Mixer) (manufactured by Toray Engineering). When using an in-line mixer, it is preferable to apply it to a dope in which cellulose ester is concentrated and dissolved under high pressure. The type of the pressure vessel is not particularly limited and can withstand a predetermined pressure, and heated and stirred under pressure. If you can.

In the present invention, the cellulose ester dope must be filtered to remove foreign matters, particularly foreign matters that can be recognized as images in a liquid crystal image display device. It can be said that the quality of the protective film for polarizing plates is determined by this filtration. Filter media used for filtration preferably have a low absolute filtration accuracy, but if the absolute filtration accuracy is too small, the filter media is likely to be clogged, and the filter media must be frequently replaced, reducing productivity. There is a problem. For this reason, the cellulose ester-doped filter medium of the present invention preferably has an absolute filtration accuracy of 0.008 mm or less, more preferably in the range of 0.001 to 0.008 mm, and in the range of 0.003 to 0.006 mm. Further preferred. There are no particular restrictions on the material of the filter medium, and ordinary filter media can be used. However, filter fibers made of plastic fibers such as polypropylene and Teflon (registered trademark) and metal filter media such as stainless steel fibers can cause the fibers to fall off. Less preferred. Filtration of the cellulose ester dope of the present invention can be carried out by a usual method, but the method of filtration while heating under pressure at a temperature not lower than the boiling point of the solvent at a normal pressure and in a range where the solvent does not boil is used before and after the filtration. The increase in differential pressure (hereinafter sometimes referred to as filtration pressure) is small and preferable. A preferred temperature range is 45 to 120 ° C, more preferably 45 to 70 ° C, and still more preferably 45 to 55 ° C. A smaller filtration pressure is preferred. The filtration pressure is preferably 1.6 × 10 ⁶ Pa or less, more preferably 1.2 × 10 ⁶ Pa or less, and further preferably 1.0 × 10 ⁶ Pa or less. If the cellulose of the raw material contains an acyl group unsubstituted or low-substituted cellulose ester, a foreign matter failure (hereinafter sometimes referred to as a bright spot) may occur. When a cellulose ester film is placed between two polarizing plates in a crossed state (crossed nicols), light is irradiated from one side and observed with an optical microscope (50 times) from the opposite side, a normal cellulose ester film is obtained. If there is, the light is blocked and you can't see anything black, but if there is a foreign object, the light leaks out and appears to shine like a spot. The larger the diameter of the bright spot, the greater the actual harm in the case of a liquid crystal image display device, preferably 50 μm or less, more preferably 10 μm or less, and further preferably 8 μm or less. The diameter of the bright spot means a diameter measured by approximating the bright spot to a perfect circle. There are no practical problems as long as the bright spot has a diameter of 400 / cm ² or less, but 300 / cm ² or less is preferable, and 200 / cm ² or less is more preferable. In order to reduce the number and size of such bright spots, it is necessary to sufficiently filter fine foreign matters. In addition, as described in JP-A-2000-137115, a method of re-adding a pulverized product of a cellulose ester film once formed into a dope and using it as a raw material for cellulose ester and its additive is a bright spot. Since it can reduce, it can use preferably.

  Next, the process of casting the cellulose ester dope on the metal support, the drying process on the metal support, and the peeling process of peeling the web from the metal support will be described. The metal support is an endless metal belt or a rotating metal drum that moves indefinitely, and its surface is a mirror surface. The casting step is a step of feeding the dope as described above to a pressure die through a pressure type quantitative gear pump and casting the dope from the pressure die onto the metal support at the casting position. Other casting methods include a doctor blade method in which the film thickness of the cast dope film is adjusted with a blade, or a reverse roll coater method in which the film is adjusted with a reverse-rotating roll, but the slit shape of the die part is adjusted. A pressure die that is easy to make uniform in film thickness 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 metal support, and the dope amount may be divided and stacked. In order to adjust the film thickness, it is preferable to control the dope concentration, the pumped liquid amount, the slit gap of the die base, the extrusion pressure of the die, the speed of the metal support, etc. so as to obtain a desired thickness.

  The drying process on the metal support is a process in which the web (the dope film after casting on the metal support is referred to as the web) is heated on the support to evaporate the solvent. In order to evaporate the solvent, there are a method in which heated air is blown from the web side and the back side of the support, a method in which heat is transferred from the back side of the support by a heated liquid, a method in which heat is transferred from the front and back by radiant heat, and the like. A method of combining them is also preferable. Moreover, if the film thickness of a web is thin, drying will be quick. The temperature of the metal support may be the same or different depending on the position.

  In the drying method on the metal support suitable for the present invention, for example, the metal support is preferably cast at a temperature of 0 to 40 ° C., preferably 5 to 30 ° C. The drying air applied to the web is preferably about 30 to 45 ° C, but is not limited thereto.

  The peeling step is a step of evaporating the organic solvent on the metal support and peeling the web before the metal support goes around, and then the web is sent to the drying step. The position at which the web is peeled from the metal support is called the peeling point, and the roll that helps the peeling is called the peeling roll. Although it depends on the thickness of the web, if the residual solvent amount of the web at the peeling point (the following formula) is too large, it will be difficult to peel, or conversely if it is peeled off after sufficiently drying on the support, May be peeled off. Usually, the web is peeled at a residual solvent amount of 20 to 150% by mass. In the present invention, the preferable amount of residual solvent for peeling is 20 to 40% by mass or 60 to 120% by mass, and particularly preferably 20 to 30% by mass or 70 to 115% by mass. As a method for increasing the film forming speed (the film forming speed can be increased because the film is peeled off while the residual solvent amount is as large as possible), there is a gel casting method (gel casting) that can be peeled even when the residual solvent amount is large. As the method, there are a method of adding a poor solvent for the cellulose ester in the dope and casting the dope and then gelling, a method of reducing the temperature of the support and gelling. There is also a method of adding a metal salt in the dope. By gelling on the support and strengthening the film, it is possible to speed up the peeling and increase the film forming speed. When peeling at a time when the amount of residual solvent is larger, if the web is too soft, the flatness at the time of peeling will be impaired, or slippage and vertical stripes due to peeling tension will tend to occur, and the amount of residual solvent is determined by the balance between economic speed and quality. It is done.

  The amount of residual solvent used in the present invention can be expressed by the following formula.

Residual solvent amount (% by mass) = {(MN) / N} × 100
Here, M is the mass of the web at any point, and N is the mass when M is dried at 110 ° C. for 3 hours.

  Moreover, in the drying process of the cellulose ester film, it is preferable to further dry the film peeled off from the support, and to make the residual solvent amount 2.0% by mass or less, more preferably 1.0% by mass, and still more preferably. , 0.5% by mass or less.

  In the web drying process, a roll drying apparatus in which rolls are arranged in a staggered manner, and a method of drying while conveying the web with a tenter drying apparatus that holds the width of the web with clips and holds the width or extends slightly in the width direction are adopted. In the present invention, it is particularly preferable because the humidity stability of the optical performance is improved by maintaining the width or stretching in an arbitrary process after peeling from the support of the tenter drying apparatus and in an arbitrary amount of residual solvent. The means for drying the web is not particularly limited, and is generally performed by hot air, infrared rays, a heating roll, microwaves, or the like. It is preferable to carry out with hot air in terms of simplicity. The drying temperature is preferably increased stepwise in the range of 40 to 150 ° C, more preferably in the range of 50 to 140 ° C.

  The stretching operation may be performed in multiple stages, and it is preferable to perform biaxial stretching in the casting direction and the width direction. Also, when biaxial stretching is performed, simultaneous biaxial stretching may be performed or may be performed stepwise. In this case, stepwise means that, for example, stretching in different stretching directions can be sequentially performed, stretching in the same direction is divided into multiple stages, and stretching in different directions is added to any one of the stages. Is also possible.

  Simultaneous biaxial stretching includes stretching in one direction and contracting the other while relaxing the tension. The preferred draw ratio of simultaneous biaxial stretching is x1.05 to x1.5 times in the width direction and x0.8 to x1.3 times in the longitudinal direction (casting direction), particularly x1 in the width direction. 0.1 to x1.5 times, and preferably x0.8 to x0.99 times in the longitudinal direction. Particularly preferably, it is x1.1 to x1.4 times in the width direction and x0.9 to x0.99 times in the longitudinal direction.

  A thinner cellulose ester film is preferable because the resulting polarizing plate becomes thinner and the liquid crystal display can be easily made thinner. However, if it is too thin, moisture permeability, tear strength, and the like deteriorate. The film thickness of the cellulose ester film that achieves both of these is preferably 10 to 200 μm, more preferably 40 to 120 μm, and particularly preferably 50 to 70 μm.

  The width of the cellulose ester film is preferably 1.4 m or more, and preferably in the range of 1.4 m to 4 m for a large-sized liquid crystal display device from the viewpoint of productivity.

  The cellulose ester film of the present invention is preferably used for a liquid crystal display member because of its high moisture permeability and dimensional stability. A liquid crystal display member is a member used in a liquid crystal display device. For example, a polarizing plate, a protective film for a polarizing plate, a retardation plate, a reflective plate, a viewing angle improving film, an antiglare film, an antireflective film, and a charge Prevention films and the like. Among the above description, it is preferable to use for a polarizing plate and a protective film for a polarizing plate.

(Polarizer)
The polarizing plate was prepared by subjecting the formed cellulose ester film according to the present invention to a surface saponification treatment with a 2.5 mol / l sodium hydroxide aqueous solution at 40 ° C. for 60 seconds, washing with water for 3 minutes, and drying. Separately, 120 μm thick polyvinyl alcohol was immersed in 100 parts by mass of an aqueous solution containing 1 part by mass of iodine and 4 parts by mass of boric acid, and a polarizing film stretched in the vertical direction at 50 ° C. was prepared. A surface-saponified cellulose ester film is bonded to a fully saponified 5% by weight aqueous solution of polyvinyl alcohol to produce a polarizing plate.

  The stretched cellulose ester film which is a protective film for polarizing plate of the present invention has a retardation value Ro defined by the following formula (I) of 30 to 200 nm and a retardation value Rt defined by the following formula (II). It is characterized by being in the range of 70 to 400 nm.

Formula (I) Ro = (nx−ny) × d
Formula (II) Rt = {(nx + ny) / 2−nz} × d
In the formula, nx is the refractive index in the direction with the largest refractive index in the film plane, ny is the refractive index in the film plane in the direction perpendicular to nx, nz is the refractive index in the thickness direction of the film, and d is the thickness of the film. (Nm) respectively.

  By setting the retardation value within the above range, the optical performance as a retardation film for a polarizing plate can be sufficiently satisfied.

  The retardation values Ro and Rt can be measured using an automatic birefringence meter. For example, the wavelength can be obtained at 590 nm in an environment of 23 ° C. and 55% RH using KOBRA-21ADH (Oji Scientific Instruments).

  The protective film for polarizing plate of the present invention preferably has a light transmittance (of visible light) of 90% or more, more preferably 95% or more, and more preferably 94% or more even after saponification treatment. The haze is preferably less than 1%, more preferably less than 0.5%, and further preferably less than 0.1%. In particular, 0% is most preferable.

(Display device)
By incorporating the polarizing plate of the present invention into a display device, the display device of the present invention having various visibility can be manufactured. The cellulose stealth film of the present invention is a reflective type, transmissive type, transflective type LCD or TN type, STN type, OCB type, HAN type, VA type (PVA type, MVA type), IPS type, etc. Preferably used. In particular, it is suitable for a VA liquid crystal display device.

  In particular, the VA type liquid crystal display device with a large screen of 30 or more screens has the effect of improving the humidity stability of the optical performance, reducing color unevenness and wavy unevenness, and preventing eyestrain even during long-time viewing. .

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

Example 1
(Polyester synthesis example A1)
A reactor equipped with a cooling condenser was charged with 236 parts by weight of ethylene glycol, 683 parts by weight of 1,4-butylene glycol, 1180 parts by weight of succinic acid, 0.03 parts by weight of tetrabutyl titanate, and 140 ° C. For 2 hours, 220 ° C. for 2 hours, the cooling condenser was removed, and the dehydration condensation reaction was carried out at 220 ° C. for an additional 20 hours to obtain a polyester (A1) having a number average molecular weight of 2000. The average carbon number of the glycol (a) used for this was 3.33, and the carbon number of the dibasic acid (b) was 4.

(Polyester synthesis example A2)
Into a reactor equipped with a cooling condenser, 699 parts by mass of ethylene glycol, 1180 parts by mass of succinic acid, and 0.03 parts by mass of tetrabutyl titanate were added, and the same operation as in Synthesis Example A1 of polyester was performed. A polyester (A2) having an average molecular weight of 2000 was obtained. The average number of carbon atoms of glycol (a) used for this was 2, and that of dibasic acid (b) was 4.

(Polyester synthesis example A3)
A reactor equipped with a cooling condenser was charged with 702 parts by mass of ethylene glycol, 885 parts by mass of succinic acid, 365 parts by mass of adipic acid, 0.03 parts by mass of tetrabutyl titanate, and polyester synthesis example A1 and The same operation was performed to obtain a polyester (A3) having a number average molecular weight of 2000. The average number of carbon atoms of glycol (a) used for this was 2, and the number of carbon atoms of dibasic acid (b) was 4.5.

(Polyester synthesis example A4)
In a reactor equipped with a cooling condenser, 631 parts by weight of ethylene glycol, 101 parts by weight of 1,4-butylene glycol, 1062 parts by weight of succinic acid, 146 parts by weight of adipic acid, 0.03 parts by weight of tetrabutyl Titanate was added, and the same operation as in polyester synthesis example A1 was performed to obtain a polyester (A4) having a number average molecular weight of 2000. The average number of carbon atoms of glycol (a) used for this was 2.2, and that of dibasic acid (b) was 4.2.

(Polyester synthesis example A5)
A reactor equipped with a cooling condenser was charged with 226 parts by mass of ethylene glycol, 656 parts by mass of 1,4-butylene glycol, 1180 parts by mass of succinic acid, 0.03 parts by mass of tetrabutyl titanate, The same operation as in Synthesis Example A1 was performed to obtain a polyester (A5) having a number average molecular weight of 4000. The average carbon number of the glycol (a) used for this was 3.33, and the carbon number of the dibasic acid (b) was 4.

(Polyester synthesis example A6)
A reactor equipped with a cooling condenser was charged with 249 parts by weight of ethylene glycol, 721 parts by weight of 1,4-butylene glycol, 1180 parts by weight of succinic acid, 0.03 parts by weight of tetrabutyl titanate, The same operation as in Synthesis Example A1 was performed to obtain a polyester (A6) having a number average molecular weight of 1500. The average carbon number of the glycol (a) used for this was 3.33, and the carbon number of the dibasic acid (b) was 4.

(Polyester synthesis example A7)
A reactor equipped with a cooling condenser is charged with 648 parts by weight of ethylene glycol, 58 parts by weight of diethylene glycol, 1121 parts by weight of succinic acid, 83 parts by weight of terephthalic acid, 0.03 parts by weight of tetrabutyl titanate, The same operation as in Synthesis Example A1 of polyester was performed to obtain a polyester (A4) having a number average molecular weight of 3000. The average number of carbon atoms of glycol (a) used for this was 2.1, and the number of carbon atoms of dibasic acid (b) was 4.2.

(Comparative synthesis example B1 of polyester)
A reactor equipped with a cooling condenser was charged with 238 parts by weight of ethylene glycol, 693 parts by weight of 1,4-butylene glycol, 1460 parts by weight of adipic acid, 0.03 parts by weight of tetrabutyl titanate, The same operation as in Synthesis Example A1 was performed to obtain a polyester (B1) having a number average molecular weight of 2000. The average carbon number of glycol (a) used for this was 3.33, and the carbon number of dibasic acid (b) was 6.

(Comparative synthesis example B2 of polyester)
A reactor equipped with a cooling condenser was charged with 1030 parts by mass of 1,4-butylene glycol, 1180 parts by mass of succinic acid, and 0.03 parts by mass of tetrabutyl titanate, and the same operation as in polyester synthesis example A1 To obtain a polyester (B2) having a number average molecular weight of 2,000. The average number of carbon atoms of the glycol (a) used for this was 4, and the carbon number of the dibasic acid (b) was 4.

(Comparative synthesis example B3 of polyester)
A reactor equipped with a cooling condenser was charged with 706 parts by mass of ethylene glycol, 1460 parts by mass of adipic acid and 0.03 parts by mass of tetrabutyl titanate, and the same operation as in Synthesis Example A1 of polyester was performed. A polyester (B3) having an average molecular weight of 2000 was obtained. The average number of carbon atoms of glycol (a) used for this was 2, and that of dibasic acid (b) was 6.

(Synthesis example of polymer UV agent P-1)
2 (2′-Hydroxy-5′-t-butyl-phenyl) -5-carboxylic acid- (2-methacryloyloxy) ethyl ester-2H-benzotriazole (Exemplary Compound MUV-19) was prepared according to the method described below. Synthesized.

  20.0 g 3-nitro-4-amino-benzoic acid was dissolved in 160 ml water and 43 ml concentrated hydrochloric acid was added. After adding 8.0 g of sodium nitrite dissolved in 20 ml of water at 0 ° C., the mixture was stirred at 0 ° C. for 2 hours. To this solution, 17.3 g of 4-t-butylphenol was added dropwise at 0 ° C. in a solution of 50 ml of water and 100 ml of ethanol while keeping the liquidity alkaline with potassium carbonate. The solution was stirred for 1 hour while maintaining at 0 ° C., and further for 1 hour at room temperature. The reaction solution was acidified with hydrochloric acid, and the resulting precipitate was filtered and washed thoroughly with water.

  The filtered precipitate was dissolved in 500 ml of 1 mol / L NaOH aqueous solution, 35 g of zinc powder was added, and 110 g of 40% NaOH aqueous solution was added dropwise. After dropping, the mixture was stirred for about 2 hours, filtered, washed with water, and the filtrate was neutralized with hydrochloric acid to neutral. The deposited precipitate is filtered, washed with water, dried and then recrystallized with a mixed solvent of ethyl acetate and acetone to give 2 (2'-hydroxy-5'-t-butyl-phenyl) -5-carboxylic acid-2H. -Benzotriazole was obtained.

  Then 10.0 g of 2 (2′-hydroxy-5′-t-butyl-phenyl) -5-carboxylic acid-2H-benzotriazole and 0.1 g of hydroquinone, 4.6 g of 2-hydroxyethyl methacrylate, 0 .5 g of p-toluenesulfonic acid is added to 100 ml of toluene, and heated and perfused for 10 hours in a reaction vessel equipped with an ester tube. The reaction solution is poured into water, and the precipitated crystals are filtered, washed with water, dried, and recrystallized with ethyl acetate to give 2 (2'-hydroxy-5'-t-butyl-phenyl) which is the exemplified compound MUV-19. ) -5-carboxylic acid- (2-methacryloyloxy) ethyl ester-2H-benzotriazole was obtained.

  Next, a copolymer of 2 (2'-hydroxy-5'-t-butyl-phenyl) -5-carboxylic acid- (2-methacryloyloxy) ethyl ester-2H-benzotriazole and methyl methacrylate (polymer UV Agent P-1) was synthesized according to the method described below.

  To 80 ml of tetrahydrofuran, 4.0 g of 2 (2′-hydroxy-5′-t-butyl-phenyl) -5-carboxylic acid- (2-methacryloyloxy) ethyl ester-2H-benzotriazole synthesized in Synthesis Example 3 above. And 6.0 g of methyl methacrylate were added followed by 1.14 g of azoisobutyronitrile. The mixture was heated to reflux for 9 hours under a nitrogen atmosphere. Tetrahydrofuran was distilled off under reduced pressure, then redissolved in 20 ml of tetrahydrofuran and added dropwise to a large excess of methanol. The deposited precipitate was collected by filtration and vacuum-dried at 40 ° C. to obtain 9.1 g of a polymer UV agent P-1 which was an off-white powdery polymer. This copolymer was confirmed to have a number average molecular weight of 4500 by GPC analysis based on standard polystyrene. Further, from the NMR spectrum and UV spectrum, the above copolymer was found to be 2 (2′-hydroxy-5′-t-butyl-phenyl) -5-carboxylic acid- (2-methacryloyloxy) ethyl ester-2H-benzotriazole. And a copolymer of methyl methacrylate. The composition of the polymer is approximately 2 (2′-hydroxy-5′-t-butyl-phenyl) -5-carboxylic acid- (2-methacryloyloxy) ethyl ester-2H-benzotriazole: methyl methacrylate = 40: 60.

(Synthesis example of polymer UV agent P-2)
In the process of synthesizing the polymer UV agent P-1, a polymer was similarly obtained except that 5.0 g of methyl methacrylate and 1.0 g of hydroxyethyl methacrylate were used instead of 6.0 g of methyl methacrylate. UV agent P-2 was synthesized. The number average molecular weight was 4500. Further, the composition of the polymer is substantially 2 (2′-hydroxy-5′-t-butyl-phenyl) -5-carboxylic acid- (2-methacryloyloxy) ethyl ester-2H-benzotriazole: methyl methacrylate: The hydroxyethyl methacrylate was 40:50:10.

[Production of cellulose ester film]
Cellulose ester solutions were prepared using the cellulose esters, additives, fine particles, and solvents described in Tables 1 and 2 so that the dope compositions shown in Tables 3 and 4 were obtained.

  That is, the solvent was put into an airtight container, the remaining materials were put in order while stirring, and completely dissolved and mixed while heating and stirring. The fine particles were added dispersed in a part of the solvent. The solution was lowered to the temperature at which the solution was cast, allowed to stand, and subjected to a defoaming operation, and then the solution was added to Azumi Filter Paper No. Filtration using 244 gave each cellulose ester solution.

  Next, the cellulose ester solution whose temperature was adjusted to 33 ° C. was fed to a die and uniformly cast from a die slit onto a stainless steel belt. The cast part of the stainless steel belt was heated from the back with hot water of 37 ° C. After casting, the dope film on the metal support (simply referred to as the web after casting on the stainless steel belt) is dried by applying hot air of 44 ° C., and the residual solvent amount during peeling is 80% by mass. Then, it is stretched so as to have a longitudinal stretching ratio of 1.05 times by applying tension at the time of peeling, and then the web end is gripped by a tenter so that the stretching ratio is 1.30 times in the width direction. Stretched. After stretching, the width is maintained for several seconds, and after the tension in the width direction is relaxed, the width is released, and further conveyed for 20 minutes in the third drying zone set at 110 ° C. for drying. Then, cellulose ester film samples 1 to 43 having a film thickness of 80 μm having a width of 1.5 m and a knurling of 1.5 cm in width and 8 μm in height were produced.

  The produced cellulose ester films are summarized in Tables 3 and 4 with respect to the cellulose ester, additives, fine particles, solvent and the like used.

<Evaluation methods>
(Retardation Ro, Rt)
Using an automatic birefringence meter (Oji Scientific Instruments Co., Ltd., KOBRA-21ADH), cellulose ester film samples 1 to 43 were measured at 10 locations at a wavelength of 590 nm in a 23 ° C., 55% RH environment, and three-dimensional. Refractive index measurement was performed and refractive indexes nx, ny, and nz were obtained. The retardation Ro in the in-plane direction was calculated according to the formula (I), and the retardation Rt in the thickness direction was calculated according to the formula (II). Each of them was measured at 10 points and the average value was shown.

Formula (I)
Ro = (nx−ny) × d
In the formula, nx represents the refractive index of the film in a direction parallel to the film forming direction, ny represents the refractive index of the film in the direction perpendicular to the film forming direction, and d represents the thickness (nm) of the film.

Formula (II)
Rt = ((nx + ny) / 2−nz) × d
In the formula, nx is the refractive index of the film in the direction parallel to the film forming direction, ny is the refractive index of the film in the direction perpendicular to the film forming direction, nz is the refractive index of the film in the thickness direction, and d is the thickness of the film. (Nm) respectively.

(Haze)
Three film samples were superposed and measured according to ASTM-D1003-52 using T-2600DA manufactured by Tokyo Denshoku Industries Co., Ltd.

(Bleed out)
The film sample was allowed to stand for 1000 hours in a high-temperature and high-humidity atmosphere at 80 ° C. and 90% RH, and then bleed out was evaluated.

  The presence or absence of bleed out was evaluated by observing the surface of the film.

◎ ・ ・ ・ No bleed-out on the film surface ○ ・ ・ ・ Partial bleed-out is faint on the film surface △ ・ ・ ・ Full bleed-out is faint on the film surface × ・ ・ ・ Film surface Clearly shows full bleed out (Rt humidity change)
Measure the Rt of the sample conditioned for 12 hours or more in an environment of 23 ° C. and 20% RH, and then measure the Rt of the sample conditioned for 12 hours or more in an environment of 23 ° C. and 20% RH. Was calculated.

(Foreign matter failure)
An online defect inspection machine was installed immediately before the winding part of the belt casting apparatus, and the number of foreign matter failures of 50 μm or more per 100 m ^{2 of} the cellulose ester film was counted.

(Molecular weight measurement)
The average molecular weight was measured using high performance liquid chromatography.

The measurement conditions are as follows.
Solvent: Methylene chloride Column: TSKgel G2000HxL G3000HxL G4000HxL
(Used by connecting three high-performance SEC columns manufactured by Tosoh Corporation)
Column temperature: 25 ° C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (manufactured by GL Sciences)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0ml / min
<Preparation of polarizing plate>
About each cellulose ester, the polarizing plate was produced and the deterioration of the polarizer was evaluated.

  A 120 μm thick polyvinyl alcohol film 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 subjected to alkali saponification treatment on both surfaces of the polarizing film were bonded to each other using a completely saponified polyvinyl alcohol 5% aqueous solution as an adhesive to prepare polarizing plates.

<Alkali saponification treatment>
Saponification step 2N-NaOH 50 ° C. 90 seconds Water washing step Water 30 ° C. 45 seconds Step inside 10 mass% HCl 30 ° C. 45 seconds Water washing step Water 30 ° C. 45 seconds Saponification, water washing, neutralization, water washing under the above conditions And then dried at 80 ° C.

(Polarizing plate degradation)
For the polarizing plate produced by the above method, first, the parallel transmittance and the orthogonal transmittance were measured, and the degree of polarization was calculated according to the following formula. Thereafter, each polarizing plate was subjected to forced degradation for 1000 hours under the conditions of 60 ° C. and 90%, and then the parallel transmittance and the orthogonal transmittance were measured again, and the degree of polarization was calculated according to the following formula. The amount of change in polarization degree was determined by the following formula.

Polarization degree P = ((H0−H90) / (H0 + H90)) 1/2 × 100
Polarization degree change = P0−P1000
H0: parallel transmittance H90: orthogonal transmittance P0: degree of polarization before forced deterioration P1000: degree of polarization after 1000 hours of forced deterioration ◎: less than 10% change in polarization degree ○: more than 10% and less than 25% change in polarization degree × : Polarization degree change rate of 25% or more.

  From the results in Table 2, it can be seen that the cellulose film of the present invention has little foreign matter failure, small haze, and little change in Rt humidity. Moreover, there is little deterioration of a polarizer when it is used as a polarizing plate.

Example 2
<< Preparation of antireflection film >>
Using a cellulose ester film KC8UX2M (manufactured by Konica Minolta Opto Co., Ltd.), an antireflection film was produced by the following procedure.

  The refractive index of each layer constituting the antireflection layer was measured by the following method.

(Refractive index)
The refractive index of each refractive index layer was calculated | required from the measurement result of the spectral reflectance of the spectrophotometer about the sample which coated each layer on the hard coat film produced below. The spectrophotometer uses U-4000 type (manufactured by Hitachi, Ltd.), and after roughening the back side of the measurement side of the sample, light absorption treatment is performed with black spray to prevent reflection of light on the back side. The reflectance in the visible light region (400 nm to 700 nm) was measured under the condition of regular reflection at 5 degrees.

(Particle size of metal oxide fine particles)
As for the particle diameter of the metal oxide fine particles used, 100 fine particles were observed with an electron microscope (SEM), the diameter of a circle circumscribing each fine particle was taken as the particle diameter, and the average value was taken as the particle diameter.

<< Production of cellulose ester film having hard coat layer and back coat layer >>
On the cellulose ester film KC8UX2M (Konica Minolta Opto Co., Ltd.), the following hard coat layer coating solution is filtered through a polypropylene filter having a pore size of 0.4 μm to prepare a hard coat layer coating solution. After coating with a coater and drying at 90 ° C., the coating layer is cured with an ultraviolet lamp using an ultraviolet lamp with an illuminance of 100 mW / cm ² and an irradiation dose of 0.1 J / cm ² . A hard coat layer was formed to produce a hard coat film.

(Hard coat layer coating solution)
The following materials were stirred and mixed to obtain hard coat layer coating solution 1.

Acrylic monomer: KAYARAD DPHA (dipentaerythritol hexaacrylate, Nippon Kayaku) 220 parts by mass Irgacure 184 (manufactured by Ciba Specialty Chemicals) 20 parts by mass Propylene glycol monomethyl ether 110 parts by mass Ethyl acetate 110 parts by mass The coating layer composition was applied by an extrusion coater so as to have a wet film thickness of 10 μm, dried at 85 ° C. and wound up to provide a backcoat layer.

(Backcoat layer composition)
Acetone 54 parts by weight Methyl ethyl ketone 24 parts by weight Methanol 22 parts by weight Diacetyl cellulose 0.6 parts by weight Ultrafine silica 2% acetone dispersion (Aerosil 200V manufactured by Nippon Aerosil Co., Ltd.) 0.2 parts by weight << Preparation of Antireflection Film >>
On the hard coat film prepared above, an antireflection layer was coated in the order of a high refractive index layer and then a low refractive index layer as described below to prepare an antireflection film.

<Preparation of antireflection layer: high refractive index layer>
On the hard coat film, the following high refractive index layer coating composition was applied with an extrusion coater, dried at 80 ° C. for 1 minute, then cured by irradiation with ultraviolet rays of 0.1 J / cm ² , and further at 100 ° C. for 1 minute. A high refractive index layer was provided so as to have a thickness of 78 nm by thermosetting.

  The refractive index of this high refractive index layer was 1.62.

<High refractive index layer coating composition 1>
Isopropyl alcohol solution of metal oxide fine particles (solid content 20%, ITO particles, particle size 5 nm) 55 parts by mass Metal compound: Ti (OBu) ₄ (tetra-n-butoxytitanium) 1.3 parts by mass Ionizing radiation curable resin : Dipentaerythritol hexaacrylate
3.2 parts by mass Photopolymerization initiator: Irgacure 184 (manufactured by Ciba Specialty Chemicals)
0.8 parts by mass 10% propylene glycol monomethyl ether solution of linear dimethyl silicone-EO block copolymer (FZ-2207, manufactured by Nippon Unicar Co., Ltd.) 1.5 parts by mass Propylene glycol monomethyl ether 120 parts by mass Isopropyl alcohol 240 parts by mass Methyl ethyl ketone 40 parts by mass << Preparation of antireflection layer: low refractive index layer >>
On the high refractive index layer, the following low refractive index layer coating composition was applied with an extrusion coater, dried at 100 ° C. for 1 minute, cured by irradiation with ultraviolet rays of 0.1 J / cm ² , and further 120 An antireflection film was prepared by thermosetting at 5 ° C. for 5 minutes and providing a low refractive index layer so as to have a thickness of 95 nm. The refractive index of this low refractive index layer was 1.37.

(Preparation of low refractive index layer coating composition)
<Preparation of tetraethoxysilane hydrolyzate A>
Hydrolyzate A was prepared by mixing 289 g of tetraethoxysilane and 553 g of ethanol, adding 157 g of 0.15% aqueous acetic acid solution thereto, and stirring in a water bath at 25 ° C. for 30 hours.

Tetraethoxysilane hydrolyzate A 110 parts by mass Hollow silica-based fine particles (P-2 below) 30 parts by mass KBM503 (silane coupling agent, manufactured by Shin-Etsu Chemical Co., Ltd.) 4 parts by mass Linear dimethyl silicone-EO block copolymer (FZ) -2207, manufactured by Nihon Unicar Co., Ltd.) 10% propylene glycol monomethyl ether solution 3 parts by mass Propylene glycol monomethyl ether 400 parts by mass Isopropyl alcohol 400 parts by mass <Preparation of hollow silica-based fine particles P-2>
A mixture of 100 g of silica sol having an average particle diameter of 5 nm and a SiO ₂ concentration of 20% by mass and 1900 g of pure water was heated to 80 ° C. The pH of this reaction mother liquor was 10.5, and 9000 g of 0.98 mass% sodium silicate aqueous solution as SiO ₂ and 9000 g of 1.02 mass% sodium aluminate aqueous solution as Al ₂ O ₃ were simultaneously added to the mother liquor. did. Meanwhile, the temperature of the reaction solution was kept at 80 ° C. The pH of the reaction solution rose to 12.5 immediately after the addition and hardly changed thereafter. After completion of the addition, the reaction solution was cooled to room temperature and washed with an ultrafiltration membrane to prepare a SiO ₂ .Al ₂ O ₃ core particle dispersion having a solid content concentration of 20% by mass. (Process (a))
1700 g of pure water is added to 500 g of this core particle dispersion and heated to 98 ° C., and while maintaining this temperature, a silicic acid solution (SiO ₂₎ obtained by dealkalizing a sodium silicate aqueous solution with a cation exchange resin. A dispersion of core particles in which 3000 g (concentration of 3.5% by mass) was added to form a first silica coating layer was obtained. (Process (b))
Next, 1125 g of pure water is added to 500 g of the core particle dispersion liquid that has been washed with an ultrafiltration membrane to form a first silica coating layer having a solid concentration of 13% by mass, and concentrated hydrochloric acid (35.5%) is further added dropwise. The pH was adjusted to 1.0 and dealumination was performed. Next, the aluminum salt dissolved in the ultrafiltration membrane was separated while adding 10 L of hydrochloric acid aqueous solution of pH 3 and 5 L of pure water, and SiO ₂ · Al from which some of the constituent components of the core particles forming the first silica coating layer were removed. A dispersion of ₂ O ₃ porous particles was prepared (step (c)).

A mixture of 1500 g of the above porous particle dispersion, 500 g of pure water, 1.750 g of ethanol, and 626 g of 28% ammonia water is heated to 35 ° C., and then 104 g of ethyl silicate (SiO ₂ 28 mass%) is added. The surface of the porous particles on which the first silica coating layer was formed was coated with a hydrolyzed polycondensate of ethyl silicate to form a second silica coating layer. Subsequently, a dispersion of hollow silica-based fine particles (P-2) having a solid content concentration of 20% by mass in which the solvent was replaced with ethanol using an ultrafiltration membrane was prepared.

The thickness of the first silica coating layer of the hollow silica-based fine particles was 3 nm, the average particle size was 47 nm, the MO _x / SiO ₂ (molar ratio) was 0.0017, and the refractive index was 1.28. Here, the average particle diameter was measured by a dynamic light scattering method.

<Antireflection film heat treatment>
The produced antireflection film was heat-treated at 80 ° C. for 4 days in a heat treatment chamber.

  Next, using the antireflection film prepared above and the cellulose ester film prepared in Example 1, polarizing plates were prepared as follows, and these polarizing plates were incorporated into a liquid crystal display panel (image display device) for visibility. Evaluated.

  According to the following method, each of the cellulose ester film prepared in Example 1 and the antireflection film was used as a polarizing plate protective film, and bonded to the polarizing film prepared below to prepare a polarizing plate.

(A) Production of Polarizing Film A long polyvinyl alcohol film having a thickness of 120 μm was uniaxially stretched (temperature: 110 ° C., stretch ratio: 5 times). This was immersed in an aqueous solution composed of 0.075 g of iodine, 5 g of potassium iodide and 100 g of water for 60 seconds, and then immersed in an aqueous solution of 68 ° C. composed of 6 g of potassium iodide, 7.5 g of boric acid and 100 g of water. . This was washed with water and dried to obtain a long polarizing film.

(B) Production of Polarizing Plate Subsequently, according to the following steps 1 to 5, the polarizing film and the polarizing plate protective film were bonded together to produce a polarizing plate.

  Step 1: The cellulose ester film prepared in Example 1 and the antireflection film were immersed in a 2 mol / L sodium hydroxide solution at 60 ° C. for 90 seconds, then washed with water and dried. A surface of the antireflection film provided with the antireflection layer was previously protected with a peelable protective film (PET).

  Process 2: The above-mentioned polarizing film was immersed for 1 to 2 seconds in the polyvinyl alcohol adhesive tank of 2 mass% of solid content.

  Step 3: Excess adhesive adhered to the polarizing film in Step 2 was lightly removed, and it was sandwiched between the cellulose ester film prepared in Example 1 and the antireflective film that had been subjected to alkali treatment in Step 1, and laminated.

Process 4: It bonded together at the speed | rate of about 2 m / min with the pressure of 20-30 N / cm < ² > with the two rotating rollers. At this time, care was taken to prevent bubbles from entering.

  Step 5: The sample prepared in Step 4 in a dryer at 80 ° C. was dried for 2 minutes to prepare a polarizing plate. Thus, the polarizing plate (Polarizing plates 1-43) which bonded each of the cellulose-ester film samples 1-43 produced in Example 1 and the cellulose ester film which processed said AR (anti-reflection; antireflection) on the other surface. ) Was produced.

  The polarizing plate on the outermost surface of a commercially available liquid crystal display panel (NEC color liquid crystal display MultiSync LCD1525J: model name LA-1529HM) was carefully peeled off, and the polarizing plate of the present invention having the polarization direction was attached thereto.

  This was left for 24 hours in an environment of 20 ° C., 20% RH and 20 ° C., 80% RH, and then the viewing angle of each was examined. As a result, the liquid crystal display device using the cellulose ester of the present invention as a protective film for a polarizing plate had less variation in viewing angle and excellent color reproducibility.

Claims (6)

A cellulose ester film comprising a compound (J) shown below and at least one compound represented by (K) or (L).
(J) Number average molecular weight Mn obtained from a polycondensation reaction between glycols (a) having an average carbon number of 2 to 3.5 and dibasic acids (b) having an average carbon number of 4 to 4.5 Polyester (K) polyhydric alcohol ester (L) having a molecular weight of 300 or more and less than 1500 represented by the following general formula (1):
B- (GA) n-GB
(In the formula, B represents a benzene monocarboxylic acid residue. G represents an alkylene glycol residue having 2 to 12 carbon atoms, an aryl glycol residue, or an oxyalkylene glycol residue having 4 to 12 carbon atoms. A represents carbon. Represents an alkylene dicarboxylic acid residue having 4 to 12 carbon atoms and an aryl dicarboxylic acid residue having 6 to 12 carbon atoms, n is an integer of 1 to 5.) The cellulose ester film according to claim 1, wherein a cellulose ester having a total acyl group substitution degree of 2.4 or more and less than 2.8 is used. The cellulose ester film according to claim 1 or 2, wherein a retardation value Ro defined by the following formula (I) or (II) is 30 to 200 nm and Rt is 70 to 400 nm.
Formula (I) Ro = (nx−ny) × d
Formula (II) Rt = {(nx + ny) / 2−nz} × d
(Where nx is the refractive index in the direction with the largest refractive index in the film plane, ny is the refractive index in the film plane in the direction perpendicular to nx, nz is the refractive index in the thickness direction of the film, and d is the (Thickness (nm) is shown respectively.) The cellulose ester film according to any one of claims 1 to 3, further comprising an ultraviolet-absorbing copolymer synthesized from an ultraviolet-absorbing monomer represented by the following general formula (2).

(In the formula, n represents an integer of 0 to 3, R _{1 to} R ₅ represent a hydrogen atom, a halogen atom, or a substituent, and X represents —COO—, —CONR ₇ —, —OCO—, —NR _7. CO—, wherein R ₆ and R _{7 each} represent a hydrogen atom, an alkyl group, or an aryl group, provided that the group represented by R ₆ has a polymerizable group as a partial structure. The polarizing plate which uses the cellulose-ester film of any one of Claims 1-4. The liquid crystal display device using the cellulose-ester film of any one of Claims 1-4.