JP6836724B2 - Modified agent for cellulose ester resin, cellulose ester resin composition, optical film and liquid crystal display device - Google Patents

Description

The present invention relates to a modifier for a cellulose ester resin, which can obtain an optical film having a small moisture permeability and a small change in dimensions due to a change in humidity. The present invention also relates to a cellulose ester resin composition containing the modifier, an optical film obtained by using the composition, and a liquid crystal display device having the optical film.

The cellulose ester resin (CA) film has excellent transparency, optical isotropic property, and toughness, and also has adhesiveness to polyvinyl alcohol (hereinafter, abbreviated as "PVA"), which is a material for a polarizer of a liquid crystal display device. Since it is good, it is used as an optical film such as a polarizing plate protective film constituting a polarizing plate of a liquid crystal display device such as a television or a notebook computer.

Generally, a polarizing plate of a liquid crystal display device has a structure in which polarizing plate protective films made of cellulose ester are attached to both sides of a polarizing plate in which dichroic molecules are oriented on a PVA film. The polarizing plate protective film made of cellulose ester easily allows moisture to pass through (poor moisture permeability, that is, high moisture permeability), and easily takes in moisture from the outside into the inside of the polarizing plate. The polarizing plate to which the polarizing plate protective film made of cellulose ester is attached has a drawback that the polarizer is easily deteriorated due to this humidity.

In order to reduce the moisture permeability of the cellulose ester resin film, conventionally, a film has been obtained by using a cellulose ester resin composition to which a phosphoric acid ester-based compound such as triphenyl phosphate is added. However, in recent years, as the liquid crystal display device has become thinner, the thickness of the polarizing plate protective film has been reduced from 80 μm to 10 to 50 μm, and the phosphoric acid ester compound has improved moisture permeability. It is becoming difficult to grant enough. When the amount of the phosphoric acid ester compound added to the cellulose ester resin is increased in order to improve the moisture permeation resistance, there are problems such as deterioration of the heat resistance of the film and bleeding of the phosphoric acid ester compound to the film surface. Will occur. When the phosphoric acid ester compound bleeds, the film becomes cloudy, and as a result, the sharpness of the obtained image is reduced.

A modifier that can reduce the moisture permeability when compared with the same amount of addition has sufficient moisture permeability for thinning without causing a decrease in the heat resistance of the film or the problem of bleeding. Can be given. Therefore, there is an urgent need for a modifier that can reduce the moisture permeability with the same amount of addition.

As a modifier capable of imparting good moisture permeability to the cellulose ester resin film, for example, a glycol having 2 to 5 carbon atoms and an aromatic (anhydrous) dicarboxylic acid having 8 to 12 carbon atoms or A modifier for a cellulose ester resin obtained by reacting the esterified product with an aromatic monocarboxylic acid having 5 to 11 carbon atoms and comprising an ester compound having a number average molecular weight of 300 to 5,000. Is disclosed (see, for example, Patent Document 1). However, even with the modifier disclosed in Patent Document 1, it is difficult to develop a sufficiently small moisture permeability corresponding to the thinning of the cellulose ester resin film.

Further, when obtaining a cellulose ester resin film, a cellulose ester resin and an aromatic monocarboxylic acid compound having a structure in which some or all of hydrogen atoms on the aromatic ring such as hydroxybenzoic acid are substituted with hydroxyl groups and 2-. A technique using a composition containing a modifier containing an ester compound with a monoalcohol such as ethylhexanol or isodecanol is disclosed (see, for example, Patent Document 2). However, the technique described in Patent Document 2 discloses as a problem that it suppresses elution to the saponification liquid during the saponification treatment of the polarizing plate protective film, and reduces failures during the production of the polarizing plate due to the eluate, foreign matter, etc. It is not intended to impart moisture permeation resistance to the film. Even if the modifier disclosed in Patent Document 2 is used, it is not possible to impart sufficient moisture permeation resistance corresponding to the thinning.

Further, as a modifier capable of imparting good moisture permeation resistance to the cellulose ester resin film, for example, a part or all of hydrogen atoms on the aromatic ring such as hydroxybenzoic acid used in Patent Document 2 are replaced with hydroxyl groups. An ester compound of an aromatic monocarboxylic acid compound having the above-mentioned structure and a 2 to 10-valent polyfunctional alcohol having 2 to 12 carbon atoms is disclosed (see, for example, Patent Document 3). By using the modifier disclosed in Patent Document 3, a cellulose ester resin film having improved moisture permeation resistance can be obtained as compared with the case where the modifier disclosed in Patent Documents 1 and 2 is used. However, the cellulose ester resin film has a problem that the size of the film changes due to taking in moisture (moisture absorption) into the film. The cellulose ester resin film obtained by using the modifier disclosed in Patent Document 3 has improved moisture permeation resistance, but causes a dimensional change of the film due to moisture taken into the film. A liquid crystal display board using a film whose size changes due to moisture absorption as a polarizer protective film causes a decrease in image contrast due to a change in film size due to a change in the usage environment.

Japanese Unexamined Patent Publication No. 2006-282987 Japanese Unexamined Patent Publication No. 2010-271620 Japanese Unexamined Patent Publication No. 2015-083646

An object to be solved by the present invention is to provide a modifier for a cellulose ester resin capable of obtaining an optical film having a small moisture permeability and a small change in size due to a change in humidity. Another object to be solved by the present invention is to provide a cellulose ester resin composition containing the modifier, an optical film made of the resin composition, and a liquid crystal display device using the optical film.

As a result of diligent research, the present inventors have made a modifier disclosed in Patent Document 3, specifically, a polyhydric alcohol having 2 to 10 carbon atoms and an aromatic monocarboxylic acid having a hydroxyl group on the aromatic ring. By using an ester compound obtained by reacting with an acid and a polyester polyol obtained by using a dicarboxylic acid and a diol as essentials and having a number average molecular weight and a hydroxyl value in a specific range, the moisture permeability is small and the resistance to resistance is small. The present invention is completed by finding that a cellulose ester resin resin film having excellent moisture permeability can be obtained, that the film has little change in dimensions due to changes in humidity, that the film can be suitably used as an optical film, and the like. It came to.

That is, the present invention has the following equation (1).

（式中Ｇは、炭素原子数２〜１０の多価アルコールの残基である。Ａは芳香環上の水素原子の一部乃至全部が水酸基に置換された構造を有する芳香族モノカルボン酸残基である。ｎは２〜６の整数である。）
で表されるエステル化合物（Ｘ１）と、主鎖骨格中に炭素原子数２〜８のアルキレンジカルボン残基または炭素原子数６〜１２の芳香族ジカルボン酸残基と、炭素原子数２〜６のアルキレングリコール残基または炭素原子数４〜６のオキシアルキレングリコール残基とを有し、数平均分子量が３００〜１，５００であり、水酸基価が５０〜３５０であるポリエステルポリオール（Ｘ２）とを含有することを特徴とするセルロースエステル樹脂用改質剤を提供するものである。

(G in the formula is a residue of a polyhydric alcohol having 2 to 10 carbon atoms. A is an aromatic monocarboxylic acid residue having a structure in which some or all of hydrogen atoms on the aromatic ring are substituted with hydroxyl groups. Group. N is an integer of 2-6.)
The ester compound (X1) represented by, an alkylene dicarboxylic acid residue having 2 to 8 carbon atoms or an aromatic dicarboxylic acid residue having 6 to 12 carbon atoms in the main chain skeleton, and an aromatic dicarboxylic acid residue having 2 to 6 carbon atoms. Contains a polyester polyol (X2) having an alkylene glycol residue or an oxyalkylene glycol residue having 4 to 6 carbon atoms, a number average molecular weight of 300 to 1,500, and a hydroxyl value of 50 to 350. The present invention provides a modifier for a cellulose ester resin, which is characterized by the above.

The present invention also provides an optical film containing the cellulose ester resin composition.

Furthermore, the present invention provides a liquid crystal display device characterized by having the optical film.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a modifier for a cellulose ester resin capable of obtaining an optical film having a small moisture permeability and a small change in size due to a change in humidity. As described above, the modifier for cellulose ester resin of the present invention imparts excellent moisture permeability to the optical film and has little volatilization from the optical film, so that even in a harsh environment of high temperature and high humidity. Maintenance of moisture permeation resistance can be expected. The optical film of the present invention can be suitably used as a member of a liquid crystal display device.

The modifier for cellulose ester resin of the present invention has the following formula (1).

（式中Ｇは、炭素原子数２〜１０の多価アルコール残基である。Ａは芳香環上の水素原子の一部乃至全部が水酸基に置換された構造を有する芳香族モノカルボン酸残基である。ｎは２〜６の整数である。）
で表されるエステル化合物（Ｘ１）と、主鎖骨格中に炭素原子数２〜８のアルキレンジカルボン残基または炭素原子数６〜１２のアリールジカルボン酸残基と、炭素原子数２〜６のアルキレングリコール残基または炭素原子数４〜６のオキシアルキレングリコール残基とを有し、数平均分子量が３００〜１，５００であり、水酸基価が５０〜３５０であるポリエステルポリオール（Ｘ２）とを含有することを特徴とする。

(G in the formula is a polyhydric alcohol residue having 2 to 10 carbon atoms. A is an aromatic monocarboxylic acid residue having a structure in which some or all of the hydrogen atoms on the aromatic ring are substituted with hydroxyl groups. N is an integer of 2 to 6).
The ester compound (X1) represented by, an alkylene dicarboxylic acid residue having 2 to 8 carbon atoms or an aryldicarboxylic acid residue having 6 to 12 carbon atoms in the main chain skeleton, and an alkylene having 2 to 6 carbon atoms. It contains a polyester polyol (X2) having a glycol residue or an oxyalkylene glycol residue having 4 to 6 carbon atoms, a number average molecular weight of 300 to 1,500, and a hydroxyl value of 50 to 350. It is characterized by that.

The "polyhydric alcohol residue", "alkylene glycol residue", and "oxyalkylene glycol residue" represent an organic group excluding the hydroxyl group of the polyhydric alcohol, alkylene glycol, or oxyalkylene glycol. Further, the "aromatic monocarboxylic acid residue", "alkylene dicarboxylic acid residue", and "aromatic dicarboxylic acid residue" refer to the carboxyl group of the aromatic monocarboxylic acid, the alkylene dicarboxylic acid, and the aromatic dicarboxylic acid. Represents the excluded organic group. Further, the “chain” described later means that the ring is not included, and the chain includes a linear chain and a branched chain.

The ester compound (X1) used in the present invention will be described in detail below. G in the ester compound (X1) is a polyhydric alcohol residue having 2 to 10 carbon atoms. Examples of the polyhydric alcohol residue having 2 to 10 carbon atoms include an aliphatic polyhydric alcohol residue having 2 to 10 carbon atoms, an aromatic polyhydric alcohol residue having 2 to 10 carbon atoms, and the like. Be done. In the present invention, the "carbon atom number" means the number of carbon atoms not containing carbonyl carbon.

Examples of the aliphatic polyhydric alcohol residue having 2 to 10 carbon atoms include a chain aliphatic polyhydric alcohol residue having 2 to 10 carbon atoms and a cyclic aliphatic polyhydric residue having 2 to 10 carbon atoms. Hyvalent alcohol residues and the like can be mentioned. Examples of the chain aliphatic polyhydric alcohol residue having 2 to 10 carbon atoms include an ethylene glycol residue, a propylene glycol residue, a 1,3-propanediol residue, and 2-methyl-1,3-. Propanediol residue, 1,2-butanediol residue, 1,3-butanediol residue, 1,4-butanediol residue, 2,3-butanediol residue, 1,5-pentanediol residue, 3-Methyl-1,5-pentanediol residue, 1,6-hexanediol residue, 1,7-heptanediol residue, 1,8-octanediol residue, 1,9-nonanediol residue, 1 , Divalent aliphatic alcohol residues such as 10-decanediol residues; glycerin residues, 1,2,3-butanetriol residues, 1,2,4-butanetriol residues, 1,2,3- Trivalent aliphatic residues such as heptatriol residues, 1,2,4-heptatriol residues, 1,2,5-heptatriol residues, 2,3,4-heptatriol residues, and trimethylpropane residues. Alcohol residues; tetravalent aliphatic alcohol residues such as pentaerythritol residues and erythritol residues; pentavalent aliphatic alcohol residues such as xylitol residues; hexavalent aliphatic alcohol residues such as sorbitol residues And so on.

Examples of the cyclic aliphatic polyhydric alcohol residue having 2 to 10 carbon atoms include a cyclopentanediol residue, a cyclopentanedimethanol residue, a cyclohexanediol residue, a cyclohexanedimethanol residue, and a cycloheptanediol residue. Groups, cycloheptane dimethanol residues and the like can be mentioned.

In the present invention, the "aliphatic polyhydric alcohol residue" includes a structure having an ether group (-O-) in the aliphatic structure. In this case, the number of carbon atoms refers to the total number of carbon atoms of the aliphatic groups present via the ether group. Examples of the residue containing a structure having an ether group (-O-) in the aliphatic structure include diethylene glycol residue, triethylene glycol residue, dipropylene glycol residue, tripropylene glycol residue, and dipentaerythritol residue. Group etc. can be mentioned.

Examples of the aromatic polyhydric alcohol residue having 2 to 10 carbon atoms include 1,2-benzenedimethanol residue, 1,3-benzenedimethanol residue, and 1,4-benzenedimethanol residue. Can be mentioned.

Among G in the ester compound (X1), a chain aliphatic polyhydric alcohol residue having 2 to 8 carbon atoms is preferable because it can impart excellent moisture permeation resistance to the film, and has 2 to 6 carbon atoms. Linear aliphatic polyhydric alcohol residues or branched aliphatic polyhydric alcohol residues having 2 to 6 carbon atoms are more preferable, and ethylene glycol residues, propylene glycol residues, and 1,3-propanediol residues are preferable. More preferably, one or more residues selected from the group consisting of groups, 2-methyl-1,3-propanediol residues and 3-methyl-1,5-pentanediol residues.

The n is an integer of 2 to 6. n is preferably an integer of 2 to 3 because it can impart excellent moisture permeability to the film. Here, n corresponds to the valence of a polyhydric alcohol having 2 to 10 carbon atoms, which will be described later.

A in the ester compound (X1) is an aromatic monocarboxylic acid residue having a structure in which a part or all of hydrogen atoms on the aromatic ring are substituted with hydroxyl groups. Examples of aromatic monocarboxylic acid residues having a structure in which some or all of the hydrogen atoms on the aromatic ring are substituted with hydroxyl groups include monohydroxybenzoic acid residues, dihydroxybenzoic acid residues, and trihydroxybenzoic acid residues. Groups, monohydroxynaphthalenecarboxylic acid residues and the like can be mentioned.

Examples of the monohydroxybenzoic acid residue include 2-hydroxybenzoic acid (salicylic acid) residue, 3-hydroxybenzoic acid residue, 4-hydroxybenzoic acid (parahydroxybenzoic acid) residue, and 3,5-. Examples thereof include di-tert-butyl-4-hydroxybenzoic acid residues.

Examples of the dihydroxybenzoic acid residue include 2,3-dihydroxybenzoic acid (2-pyrocatechuic acid) residue, 2,4-dihydroxybenzoic acid (β-resorcinic acid) residue, and 2,5-dihydroxybenzoic acid. (Gentidic acid) residue, 2,6-dihydroxybenzoic acid (γ-resorcinic acid) residue, 3,4-dihydroxybenzoic acid (protocatechuic acid) residue, 3,5-dihydroxybenzoic acid (α-resorcinic acid) Residues and the like can be mentioned.

Examples of the trihydroxybenzoic acid residue include 3,4,5-trihydroxybenzoic acid residue, 2,4,6-trihydroxybenzoic acid residue and the like.

Examples of the monohydroxynaphthalene carboxylic acid residue include 2-hydroxy-1-naphthoic acid residue, 1-hydroxy-2-naphthoic acid residue, 3-hydroxy-2-naphthoic acid residue, and 6-hydroxy-2-. Examples include naphthoic acid residues.

Among the above A, the aromatic monocarboxylic acid residue (monohydroxybenzoic acid residue) having a structure in which one of the hydrogen atoms on the aromatic ring is substituted with a hydroxyl group imparts excellent moisture permeability and water resistance to the film. It is preferable because it can be formed, and a 4-hydroxybenzoic acid (parahydroxybenzoic acid) residue is more preferable.

In the present invention, n in the general formula (1) is an integer of 2 to 6. The number of "-OCO-A" in the general formula (1) changes depending on the integer represented by n. A plurality of "-A" in "-OCO-A" existing in the general formula (1) may be the same or different. Further, the modifier for a cellulose ester resin of the present invention is, in addition to the compound represented by the general formula (1), another compound, specifically, in the general formula (1), the hydroxyl group of the polyhydric alcohol. A compound such as a compound in which a part of the residue remains may be contained within a range that does not impair the effects of the present invention.

Examples of the ester compound (X1) used in the present invention include a polyhydric alcohol (g) having a hydroxyl group valence of 2 to 6 and a carbon atom number of 2 to 10, and a part or all of hydrogen atoms on the aromatic ring. It is a reaction product with an aromatic monocarboxylic acid (a) having a structure substituted with a hydroxyl group. In such a reactant, for example, a polyhydric alcohol (g) having 2 to 6 valences of hydroxyl groups and 2 to 10 carbon atoms and a part or all of hydrogen atoms on the aromatic ring were substituted with hydroxyl groups. It can be obtained by reacting with an aromatic monocarboxylic acid (a) having a structure.

Examples of the polyhydric alcohol (g) include an aliphatic polyhydric alcohol having 2 to 10 carbon atoms, an aromatic polyhydric alcohol having 2 to 10 carbon atoms, and the like. Examples of the aliphatic polyhydric alcohol having 2 to 10 carbon atoms include a chain aliphatic polyhydric alcohol having 2 to 10 carbon atoms and a cyclic aliphatic polyhydric alcohol having 2 to 10 carbon atoms. Can be mentioned.

Examples of the chain aliphatic polyhydric alcohol having 2 to 10 carbon atoms include ethylene glycol, propylene glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, and 1,2-butane. Diol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 1, Divalent aliphatic alcohols such as 7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol; glycerin, 1,2,3-butanetriol, 1,2,4 -Trivalent aliphatics such as butanetriol, 1,2,3-heptatriol, 1,2,4-heptatriol, 1,2,5-heptatriol, 2,3,4-heptatriol and trimethylpropane. Alcohols; tetravalent aliphatic alcohols such as pentaerythritol and erythritol; pentavalent aliphatic alcohols such as xylitol; hexavalent aliphatic alcohols such as sorbitol and the like can be mentioned. One type of the aliphatic polyhydric alcohol (g) may be used, or two or more types may be used in combination.

Examples of the cyclic aliphatic polyhydric alcohol having 2 to 10 carbon atoms include cyclopentanediol, cyclopentanedimethanol, cyclohexanediol, cyclohexanedimethanol, cycloheptanediol, cycloheptanedimethanol and the like.

In the present invention, as the aliphatic polyhydric alcohol (g), a polyhydric alcohol having an ether group (−O−) in the aliphatic structure can also be used. Examples of such alcohols include diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, dipentaerythritol and the like.

Examples of the aromatic polyhydric alcohol having 2 to 10 carbon atoms include 1,2-benzenedimethanol, 1,3-benzenedimethanol, 1,4-benzenedimethanol and the like.

Among the polyhydric alcohols (g), a chain aliphatic polyhydric alcohol having 2 to 8 carbon atoms is preferable because it can impart excellent moisture permeability and water resistance to the film, and has 2 to 6 carbon atoms. Linear aliphatic polyhydric alcohols or branched aliphatic polyhydric alcohols having 2 to 6 carbon atoms are more preferable, and ethylene glycol, propylene glycol, 1,3-propanediol, 2-methyl-1,3- More preferably, one or more alcohols selected from the group consisting of propanediol and 3-methyl-1,5-pentanediol.

Examples of the aromatic monocarboxylic acid (a) include 2-hydroxybenzoic acid (salicylic acid), 3-hydroxybenzoic acid, 4-hydroxybenzoic acid (parahydroxybenzoic acid), and 3,5-di-tert-butyl. Monohydroxybenzoic acid such as -4-hydroxybenzoic acid; 2,3-dihydroxybenzoic acid (2-pyrocatecic acid), 2,4-dihydroxybenzoic acid (β-resorcinic acid), 2,5-dihydroxybenzoic acid (gentidine) Acids), dihydroxybenzoic acids such as 2,6-dihydroxybenzoic acid (γ-resorcinic acid), 3,4-dihydroxybenzoic acid (protocatechuic acid), 3,5-dihydroxybenzoic acid (α-resorcinic acid); 3, Trihydroxybenzoic acids such as 4,5-trihydroxybenzoic acid and 2,4,6-trihydroxybenzoic acid; 2-hydroxy-1-naphthoic acid, 1-hydroxy-2-naphthoic acid, 3-hydroxy-2-naphthoe Examples thereof include acids, monohydroxynaphthalenecarboxylic acids such as 6-hydroxy-2-naphthoic acid and the like.

Among the aromatic monocarboxylic acids (a), the aromatic monocarboxylic acid (monohydroxybenzoic acid) having a structure in which one of the hydrogen atoms on the aromatic ring is substituted with a hydroxyl group provides the film with excellent moisture permeation resistance. It is preferable because it is given, and parahydroxybenzoic acid is more preferable.

The ester compound (X1) used in the present invention contains, for example, the polyhydric alcohol (g) and the aromatic monocarboxylic acid (a) in the presence of an esterification catalyst, for example, at 100 to 250 ° C. It can be produced by subjecting it to an esterification reaction within the temperature range of 2 to 25 hours. The conditions such as the temperature and time of the esterification reaction are not particularly limited and may be set as appropriate.

Examples of the esterification catalyst include titanium-based catalysts such as tetraisopropyl titanate and tetrabutyl titanate; tin-based catalysts such as dibutyltin oxide; and organic sulfonic acid-based catalysts such as p-toluenesulfonic acid.

The amount of the esterification catalyst used may be appropriately set, but it is usually preferable to use the esterification catalyst in the range of 0.001 to 0.1 parts by mass with respect to 100 parts by mass of the total amount of the raw material.

When obtaining the ester compound (X1) used in the present invention, a carboxylic acid other than the aromatic monocarboxylic acid (a) or an alcohol other than the polyhydric alcohol (g) is used as long as the effect of the present invention is not impaired. You may.

Examples of the carboxylic acid other than the aromatic monocarboxylic acid (a) include an aliphatic dicarboxylic acid, an aliphatic monocarboxylic acid, an aromatic dicarboxylic acid, and an aromatic monocarboxylic acid having no hydroxyl group.

Examples of the aliphatic dicarboxylic acid include succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, decandicarboxylic acid, cyclohexanedicarboxylic acid, dimer acid, fumaric acid and the like, and the aliphatics thereof. Examples thereof include methyl ester of dicarboxylic acid and acidified product.

Examples of the aliphatic monocarboxylic acid include acetic acid, propanoic acid, butanoic acid, pentanoic acid, hexanoic acid, heptanic acid, octanoic acid, 2-ethylhexylic acid, nonanoic acid and the like, and methyl of these aliphatic monocarboxylic acids. Examples thereof include esters, acidified compounds and acid anhydrides.

Examples of the aromatic dicarboxylic acid include phthalic acid, isophthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, methyl esters of these aromatic dicarboxylic acids, acidified products, and the like. Examples thereof include acid anhydrides.

Examples of the aromatic monocarboxylic acid having no hydroxyl group include benzoic acid, dimethyl benzoic acid, trimethyl benzoic acid, tetramethyl benzoic acid, ethyl benzoic acid, propyl benzoic acid, butyl benzoic acid, cumic acid, and parataste. Butyl benzoic acid, ortho-toluic acid, meta-toluic acid, para-toluic acid, ethoxybenzoic acid, propoxybenzoic acid, naphthoic acid, nicotinic acid, floric acid, anisic acid, etc. and methyl esters, acidifieds and acids of these aromatic monocarboxylic acids. Anhydrous and the like can be mentioned.

Examples of alcohols other than the polyhydric alcohol (g) include methanol, ethanol, 1-butanol, 2-butanol, isobutanol, t-butanol, 1-pentanol, isopentyl alcohol, tert-pentyl alcohol, and cyclopen. Monoalcohols such as tanol, 1-hexanol, cyclohexanol, 1-heptanol, 1-octanol, 2-ethyl-1-hexanol, isononyl alcohol, 1-nonyl alcohol, amyl alcohol, lauryl alcohol, methyl lactate, ethyl lactate; Examples thereof include hydrogenated bisphenol A, dimer diol, bisphenol A, ethylene oxide adduct of bisphenol A, propylene oxide adduct, diols such as polyethylene glycol, polypropylene glycol and polytetramethylene glycol.

When a carboxylic acid other than the above aromatic monocarboxylic acid (a) or an alcohol other than the polyhydric alcohol (g) is used, it is easy to obtain an ester compound (X1) that does not impair the effects of the present invention. Therefore, out of 100 parts by mass of the raw material of the ester compound (X1) used in the present invention, a total of 0.1 to 50 parts by mass is preferable, and 0.1 to 30 parts by mass is more preferable.

The number average molecular weight (Mn) of the ester compound (X1) used in the present invention is preferably in the range of 200 to 1,000, more preferably in the range of 250 to 700, because it gives the film excellent moisture permeability and water resistance. ..

Here, the number average molecular weight (Mn) is a value converted to polystyrene based on gel permeation chromatography (GPC) measurement. The measurement conditions of GPC are as follows.

[GPC measurement conditions]
Measuring device: High-speed GPC device "HLC-8320GPC" manufactured by Tosoh Corporation
Column: "TSK GURDCOLUMN SuperHZ-L" manufactured by Tosoh Corporation + "TSK gel SuperHZM-M" manufactured by Tosoh Corporation + "TSK gel SuperHZM-M" manufactured by Tosoh Corporation + "TSK gel SuperHZ-2000" manufactured by Tosoh Corporation + "TSK gel Super HZ-2000" manufactured by Tosoh Corporation
Detector: RI (Differential Refractometer)
Data processing: "EcoSEC Data Analysis version 1.07" manufactured by Tosoh Corporation
Column temperature: 40 ° C
Developing solvent: tetrahydrofuran Flow velocity: 0.35 mL / min Measurement sample: 15 mg of the sample was dissolved in 10 ml of tetrahydrofuran, and the obtained solution was filtered through a microfilter to prepare a measurement sample.
Sample injection volume: 20 μl
Standard sample: The following monodisperse polystyrene having a known molecular weight was used in accordance with the measurement manual of the above-mentioned "HLC-8320 GPC".

(Unidispersed polystyrene)
"A-300" manufactured by Tosoh Corporation
"A-500" manufactured by Tosoh Corporation
"A-1000" manufactured by Tosoh Corporation
"A-2500" manufactured by Tosoh Corporation
"A-5000" manufactured by Tosoh Corporation
"F-1" manufactured by Tosoh Corporation
"F-2" manufactured by Tosoh Corporation
"F-4" manufactured by Tosoh Corporation
"F-10" manufactured by Tosoh Corporation
"F-20" manufactured by Tosoh Corporation
"F-40" manufactured by Tosoh Corporation
"F-80" manufactured by Tosoh Corporation
"F-128" manufactured by Tosoh Corporation
"F-288" manufactured by Tosoh Corporation

The properties of the ester compound (X1) used in the present invention vary depending on the number average molecular weight (Mn), composition, and the like, but are usually liquid, solid, paste, or the like at room temperature.

The polyester polyol (X2) used in the present invention will be described in detail below. As described above, the polyester polyol (X2) has an alkylene dicarboxylic acid residue having 2 to 8 carbon atoms or an aromatic dicarboxylic acid residue having 6 to 12 carbon atoms and 2 to 6 carbon atoms in the main chain skeleton. It has an alkylene glycol residue or an oxyalkylene glycol residue having 4 to 6 carbon atoms, has a number average molecular weight of 300 to 1,500, and has a hydroxyl value of 50 to 350.

If the number average molecular weight is less than 300, the volatility becomes large, and as a result, it becomes difficult to obtain an optical film having a small moisture permeability, which is not preferable. Further, if the number average molecular weight exceeds 1,500, the compatibility with the cellulose ester resin becomes poor, and as a result, it becomes difficult to obtain an optical film having a small change in size with a change in humidity, which is not preferable. The number average molecular weight is preferably 350 to 1,300, more preferably 400 to 1,200.

If the hydroxyl value is smaller than 50, the compatibility with the cellulose ester resin becomes poor, and as a result, it becomes difficult to obtain an optical film having a small change in size with a change in humidity, which is not preferable. Further, when the hydroxyl value exceeds 350, the volatility becomes large, and as a result, it becomes difficult to obtain an optical film having a small moisture permeability, which is not preferable. The hydroxyl value is preferably 85 to 320, more preferably 90 to 280.

In the present invention, the hydroxyl value was measured by a method according to JIS K 0070-1992. The acid value was measured by a method according to JIS K 0070-1992.

Among polyester polyols (X2), an alkylene dicarboxylic acid residue having 2 to 4 carbon atoms or an aromatic dicarboxylic acid residue having 6 to 8 carbon atoms and an alkylene glycol residue having 2 to 4 carbon atoms in the main chain skeleton. A polyester polyol having a group is preferable because an optical film having more excellent dimensional stability with a change in humidity can be obtained, and a group consisting of a phthalic acid residue, an adipic acid residue and a succinic acid residue in the main chain skeleton. A polyester polyol having one or more residues selected from the above and an ethylene glycol residue or a propylene glycol residue is more preferable.

The polyester polyol (X2) used in the present invention can be obtained, for example, by reacting the dicarboxylic acid and glycol constituting each residue under the condition that the equivalent of the hydroxyl group is larger than the equivalent of the carboxyl group.

Examples of the dicarboxylic acid include alkylenedicarboxylic acids having 2 to 8 carbon atoms and aryldicarboxylic acid residues having 6 to 12 carbon atoms. Examples of the alkylenedicarboxylic acid having 2 to 8 carbon atoms include succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, decandicarboxylic acid, cyclohexanedicarboxylic acid, dimeric acid, fumaric acid and the like. Examples thereof include methyl esters and acidified compounds of these aliphatic dicarboxylic acids. These may be used alone or in combination of two or more.

Examples of the aryldicarboxylic acid having 6 to 12 carbon atoms include phthalic acid, isophthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid and methyl of these aromatic dicarboxylic acids. Examples thereof include esters, acidified compounds and acid anhydrides. These may be used alone or in combination of two or more.

Among the dicarboxylic acids, an alkylene dicarboxylic acid having 2 to 4 carbon atoms or an aromatic dicarboxylic acid having 6 to 8 carbon atoms is preferable because an optical film having more excellent dimensional stability with a change in humidity can be obtained. More preferably, one or more dicarboxylic acids selected from the group consisting of acids, adipic acids and succinic acids.

Examples of the glycol include alkylene glycols having 2 to 6 carbon atoms and oxyalkylene glycols having 4 to 6 carbon atoms. Examples of the alkylene glycol having 2 to 6 carbon atoms include ethylene glycol, propylene glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, 1,2-butanediol, and 1,3-. Butanediol, 1,4-butanediol, 2,3-butanediol and the like can be mentioned. These may be used alone or in combination of two or more.

Examples of the oxyalkylene glycol having 4 to 6 carbon atoms include diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, and tripropylene glycol. These may be used alone or in combination of two or more.

Among the glycols, alkylene glycol having 2 to 4 carbon atoms is preferable because an optical film having more excellent dimensional stability with a change in humidity can be obtained, and ethylene glycol or propylene glycol is more preferable.

In the polyester polyol (X2) used in the present invention, for example, the above-mentioned raw materials are subjected to an esterification reaction in the presence of an esterification catalyst, for example, in a temperature range of 180 to 250 ° C. for 10 to 25 hours. It can be manufactured by. The conditions such as the temperature and time of the esterification reaction are not particularly limited and may be set as appropriate.

Examples of the esterification catalyst include titanium-based catalysts such as tetraisopropyl titanate and tetrabutyl titanate; tin-based catalysts such as dibutyltin oxide; and organic sulfonic acid-based catalysts such as p-toluenesulfonic acid.

The amount of the esterification catalyst used may be appropriately set, but it is usually preferable to use the esterification catalyst in the range of 0.001 to 0.1 parts by mass with respect to 100 parts by mass of the total amount of the raw material.

The properties of the polyester polyol (X2) used in the present invention differ depending on the above (Mn), composition, and the like, but are usually liquid, solid, paste, or the like at room temperature.

The mixing ratio of the ester compound (X1) and the polyester polyol (X2) [(X1) / (X2)] is 5 in terms of mass ratio because it has excellent moisture permeation resistance and volatile resistance. It is preferably / 95 to 95/5, and more preferably 20/80 to 80/20.

The cellulose ester resin composition of the present invention is characterized by containing the modifier for the cellulose ester resin of the present invention and the cellulose ester resin.

The cellulose ester resin is obtained by esterifying a part or all of the hydroxyl groups of cellulose obtained from cotton linter, wood pulp, kenaf and the like. Among these, the film obtained by using the cellulose ester resin obtained by esterifying the cellulose obtained from the cotton linter is easily peeled off from the metal support constituting the film manufacturing apparatus, and improves the production efficiency of the film. It is preferable because it enables this.

Specific examples of the cellulose ester resin include cellulose acetate such as triacetyl cellulose and diacetyl cellulose, cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate propionate butyrate, cellulose acetate phthalate and cellulose nitrate. Can be mentioned. These cellulose ester resins can be used alone or in combination of two or more. When the film made of the cellulose ester resin composition of the present invention is used as an optical film, particularly a polarizing plate protective film, it is possible to obtain a film having excellent mechanical properties and transparency by using cellulose acetate. Therefore, it is preferable.

When the average degree of vinegarization (bonded acetic acid amount) of the cellulose acetate is in the range of 50.0 to 62.5% by mass, the obtained optical film made of the cellulose ester resin composition has mechanical properties and transparency. It is preferable because it produces a film having excellent properties.

Further, in order to improve the moisture permeability of the optical film, it is preferable that the average degree of vinegarization of cellulose acetate is in the range of 54 to 61.5% by mass. By using triacetyl cellulose having a higher average degree of vinegarization, a cellulose ester resin film having excellent moisture permeation resistance can be obtained. Further, in order to adjust the optical film to a high retardation value, the average degree of vinegarization of cellulose acetate is preferably in the range of 50.0 to 58% by mass.

The average degree of vinegarization is the mass ratio of acetic acid produced by saponifying the cellulose acetate with the mass of the cellulose acetate as a reference.

The cellulose ester resin preferably has a number average molecular weight in the range of 30,000 to 300,000 because it can improve the mechanical properties of the film. Further, when higher mechanical properties are required, it is more preferable to use one in the range of 50,000 to 200,000.

The content of the modifier for cellulose ester resin in the cellulose ester resin composition of the present invention is preferably in the range of 0.5 to 50 parts by mass, and 0.5 to 30 parts by mass with respect to 100 parts by mass of the cellulose ester resin. The range of parts by mass is more preferable, and the range of 5 to 15 parts by mass is more preferable. By using the modifier for cellulose ester resin in such a range, a composition having excellent moisture permeation resistance and transparency and which can be suitably used for optical applications can be obtained.

The optical film of the present invention is a film containing the cellulose ester resin composition of the present invention. The film thickness of the cellulose ester film of the present invention varies depending on the intended use, but is generally preferably in the range of 10 to 200 μm.

The optical film of the present invention may have characteristics such as optical anisotropy or optical isotropic property, but when the optical film is used as a protective film for a polarizing plate, it does not hinder the transmission of light. It is preferable to use an optically isotropic film.

The optical film of the present invention can be used for various purposes. The most effective application is, for example, a protective film for a polarizing plate that requires optical isotropic properties of a liquid crystal display device, but it is also used as a support for a protective film for a polarizing plate that requires an optical compensation function. Can be done.

The optical film of the present invention can be used for liquid crystal cells in various display modes. For example, IPS (In-Plane Switching), TN (Twisted Nematic), VA (Vertically Aligned), OCB (Optically Compensatory Bend) and the like can be exemplified.

The optical film of the present invention can be produced, for example, by a melt extrusion method. Specifically, the cellulose ester resin composition containing the cellulose ester resin, the modifier for the cellulose ester resin, and various other additives as needed is melt-kneaded by, for example, an extruder or the like. , Can be obtained by molding into a film using a T-die or the like.

Further, in the optical film of the present invention, in addition to the molding method, for example, a resin solution obtained by dissolving the cellulose ester resin and the modifier for the cellulose ester resin in an organic solvent is used as a metal support. It can also be obtained by casting on top and then molding by a so-called solution casting method (solvent casting method) in which the organic solvent is distilled off and dried.

According to the solution casting method, it is difficult to form irregularities on the surface, and a film having excellent surface smoothness can be obtained. Therefore, the film obtained by the solution casting method can be preferably used for optical applications, and particularly preferably for protective films for polarizing plates.

The solution casting method generally includes a first step of dissolving the cellulose ester resin and the modifier for the cellulose ester resin in an organic solvent and casting the obtained resin solution on a metal support. The second step of distilling off the organic solvent contained in the cast resin solution and drying to form a film, followed by peeling the film formed on the metal support from the metal support and heating and drying. It consists of a third step.

Examples of the metal support used in the first step include those made of endless belt-shaped or drum-shaped metal, and for example, those made of stainless steel and whose surface is mirror-finished can be used. ..

When the resin solution is cast on the metal support, it is preferable to use a resin solution filtered through a filter in order to prevent foreign substances from being mixed into the obtained film.

The drying method in the second step is not particularly limited, but is included in the cast resin solution by, for example, blowing air in a temperature range of 30 to 50 ° C. on the upper surface and / or the lower surface of the metal support. A method of evaporating 50 to 80% by mass of the organic solvent to form a film on the metal support can be mentioned.

Next, the third step is a step of peeling the film formed in the second step from the metal support and heating and drying it under a temperature condition higher than that of the second step. As the heat-drying method, for example, a method of gradually raising the temperature under a temperature condition of 100 to 160 ° C. is preferable because a film having good dimensional stability can be obtained. By heating and drying under the above temperature conditions, the organic solvent remaining in the film after the second step can be almost completely removed.

The organic solvent can be recovered and reused in the first to third steps.

The organic solvent that can be used when the cellulose ester resin and the modifier for the cellulose ester resin are mixed and dissolved in an organic solvent is not particularly limited as long as they can be dissolved, but for example, cellulose as a cellulose ester resin. When acetate is used, it is preferable to use an organic halogen compound such as methylene chloride or dioxolanes as a good solvent.

Further, it is preferable to use a poor solvent such as methanol, ethanol, 2-propanol, n-butanol, cyclohexane and cyclohexanone together with the good solvent in order to improve the production efficiency of the film.

The mixing ratio of the good solvent and the poor solvent is preferably in the range of good solvent / poor solvent = 75/25 to 95/5 in terms of mass ratio.

The concentration of the cellulose ester resin in the resin solution is preferably 10 to 50% by mass, more preferably 15 to 35% by mass.

In the solution casting method, a fourth step of heating and stretching the film after obtaining the film which has been heat-dried in the third step can be provided.

In the fourth step, after forming a film using the cellulose ester resin composition of the present invention in the first to third steps, the obtained film is heat-stretched. The stretching operation may be carried out in a plurality of stages, or biaxial stretching may be carried out in the casting direction and the width direction. Further, when biaxial stretching is performed, simultaneous biaxial stretching may be performed, or biaxial stretching may be performed step by step. In this case, the term “stepwise” means, for example, that 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 of the steps. Is also possible.

Further, the simultaneous biaxial stretching includes a case where the drawing is performed in one direction and the tension is relaxed and contracted in the other direction. The preferred draw ratio of simultaneous biaxial stretching is, for example, × 1.05 to × 1.5 times in the width direction and × 0.8 to × 1.3 times in the longitudinal direction (flowing direction), and particularly in the width direction. It is preferably x1.1 to x2.5 times and x0.8 to x0.99 times in the longitudinal direction. Particularly preferably, it is × 1.1 to × 2.0 times in the width direction and × 0.9 to × 0.99 times in the longitudinal direction.

Examples of various other additives that can be added as needed include modifiers other than the modifier for cellulose ester resin of the present invention, thermoplastic resins, ultraviolet absorbers, matting agents, dyes, and the like. Can be mentioned.

Examples of the modifier other than the modifier for the cellulose ester resin of the present invention include phosphoric acid esters such as triphenyl phosphate (TPP), tricresyl phosphate, and cresyl diphenyl phosphate; dimethyl phthalate, diethyl phthalate, and dibutyl. Phthalates such as phthalates, di-2-ethylhexylphthalates, ethylphthalylethylglycolates, butylphthalylbutylglycolates; esters of polyhydric alcohols such as trimethylpropantribenzoate, pentaerythritol tetraacetate, tributyl acetylcitrate Compounds; polyester compounds whose ends are sealed with an aliphatic monocarboxylic acid such as acetic acid, sugar ester compounds having a flanose structure or pyranose structure such as sucrose octaacetate and sucrose benzoate; compounds having a barbituric acid structure; imidazole, triazole , Pyrazole and the like, and the like, a compound having a structure in which a 5-membered aromatic heterocycle and a 6-membered aromatic hydrocarbon ring are linked.

Examples of the thermoplastic resin include polyester resin, polyester ether resin, polyurethane resin, epoxy resin, toluenesulfone amide resin and the like.

Examples of the ultraviolet absorber include oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex salt compounds and the like. The ultraviolet absorber is preferably in the range of 0.01 to 2 parts by mass with respect to 100 parts by mass of the cellulose ester resin.

Examples of the matting agent include silicon oxide, titanium oxide, aluminum oxide, calcium carbonate, calcium silicate, aluminum silicate, magnesium silicate, calcium phosphate, kaolin, talc and the like. The matting agent is preferably in the range of 0.1 to 0.3 parts by mass with respect to 100 parts by mass of the cellulose ester resin.

The type and amount of the dye are not particularly limited as long as they do not impair the object of the present invention.

The film thickness of the optical film of the present invention is preferably in the range of 5 to 120 μm, more preferably in the range of 8 to 100 μm, and particularly preferably in the range of 10 to 80 μm. When the optical film is used as a protective film for a polarizing plate, if the film thickness is in the range of 10 to 80 μm, it is suitable for thinning the liquid crystal display device, and has sufficient film strength and moisture permeation resistance. It is possible to maintain excellent performance such as.

Since the optical film of the present invention has good moisture permeability, it can be used as a protective film for polarizing plates, a retardation film, a reflector, a viewing angle improving film, an antiglare film, a non-reflective film, an antistatic film, a color filter, etc. It can be suitably used as a member of a liquid crystal display device.

Hereinafter, the present invention will be described in more detail based on examples. Parts and% in the example are based on mass unless otherwise specified.

Synthesis Example 1 [Ester compound (X1)]
221.0 g of p-hydroxybenzoic acid and 46.7 g of 2-methyl-1,3-propanediol were added to a 0.5 liter four-necked flask equipped with a thermometer, a stirrer and a reflux condenser. While stirring under a nitrogen stream, the temperature was gradually raised to 220 ° C., and the reaction was carried out for a total of 12.5 hours. After the reaction, unreacted 2-methyl-1,3-propanediol was removed under reduced pressure at 180 ° C. to obtain an ester compound (X1-1) used in the present invention. The ester compound (X1-1) was solid at room temperature. As a result of analysis by GPC, the number average molecular weight was 460 and the weight average molecular weight was 490.

Synthesis example 2 (same as above)
To a 1 liter four-necked flask equipped with a thermometer, a stirrer and a water separator, add 138 g of p-hydroxybenzoic acid, 39 g of ethylene glycol, 200 g of xylene, and 1.9 g of p-toluenesulfonic acid / monohydrate. It was. In order to carry out the esterification reaction under azeotropic dehydration conditions with xylene, the temperature was raised to 140 ° C. over 1.5 hours, and the reaction was carried out at 140 ° C. for 3 hours. After the reaction, the mixture was cooled to room temperature and the precipitated contents were filtered to obtain a solid. 500 g of ion-exchanged water was added to the obtained solid, the mixture was stirred for 30 minutes, filtered, and dried at 120 ° C. for 4 hours. 300 g of methanol was added to the solid obtained at this time, and after stirring for 15 minutes, the undissolved component was filtered and dried at 120 ° C. for 1 hour to obtain an ester compound (X1-2) used in the present invention. .. The ester compound (X1-2) was a solid at room temperature. As a result of analysis by GPC, the number average molecular weight was 390 and the weight average molecular weight was 393.

Synthesis example 3 (same as above)
221 g of p-hydroxybenzoic acid and 75.6 g of 3-methyl-1,5-pentanediol were added to a 0.5 liter four-necked flask equipped with a thermometer, a stirrer and a reflux condenser. While stirring under a nitrogen stream, the temperature was gradually raised to 220 ° C., and the reaction was carried out for a total of 12.5 hours. After the reaction, unreacted 3-methyl-1,5-pentanediol was removed under reduced pressure at 180 ° C. to obtain an ester compound (X1-3) used in the present invention. The ester compound (X1-3) was a highly viscous liquid at room temperature. As a result of analysis by GPC, the number average molecular weight was 440 and the weight average molecular weight was 450.

Synthesis Example 4 [Polyester polyol (X2)]
A four-necked flask with an internal volume of 3 liters equipped with a thermometer, a stirrer, and a reflux condenser was charged with 944 g of phthalic anhydride, 311 g of adipic acid, 923 g of propylene glycol, and 0.131 g of tetraisopropyl titanate as an esterification catalyst. While stirring under a nitrogen stream, the temperature was gradually raised to 210 ° C., and the condensation reaction was carried out for a total of 17 hours. By filtering after the reaction, a polyester polyol (X2-1) which is a high-viscosity liquid at room temperature was obtained. As a result of analysis by GPC, the number average molecular weight of the polyester polyol (X2-1) was 760, the hydroxyl value was 183, and the acid value was 0.8.

Synthesis example 5 (same as above)
In a four-necked flask with an internal volume of 2 liters equipped with a thermometer, agitator, and a reflux condenser, 393 g of phthalic anhydride, 314 g of succinic acid, 250 g of propylene glycol, 204 g of ethylene glycol, and tetraisopropyl titanate as an esterification catalyst 0. 03 g was charged, and the temperature was gradually raised to 210 ° C. while stirring under a nitrogen stream, and the condensation reaction was carried out for a total of 17 hours. By filtering after the reaction, a polyester polyol (X2-2) which is a high-viscosity liquid at room temperature was obtained. As a result of analysis by GPC, the number average molecular weight of the polyester polyol (X2-2) was 1,190, the hydroxyl value was 112, and the acid value was 0.6.

Synthesis example 6 (same as above)
Hexahydrophthalic anhydride (700 g), propylene glycol (219 g), ethylene glycol (179 g), and tetraisopropyl titanate (0.03 g) as an esterification catalyst were placed in a four-necked flask having an internal volume of 2 liters equipped with a thermometer, a stirrer, and a reflux condenser. The temperature was gradually raised to 220 ° C. while stirring under a nitrogen stream, and the condensation reaction was carried out for a total of 17 hours. By filtering after the reaction, a polyester polyol (X2-3) which is a high-viscosity liquid at room temperature was obtained. As a result of analysis by GPC, the number average molecular weight of the polyester polyol (X2-3) was 980, the hydroxyl value was 115, and the acid value was 0.5.

Synthesis example 7 (same as above)
In a four-necked flask with an internal volume of 2 liters equipped with a thermometer, agitator, and a reflux condenser, 348 g of hexahydrophthalic anhydride, 267 g of succinic acid, 213 g of propylene glycol, 173 g of ethylene glycol, and tetraisopropyl titanate 0 as an esterification catalyst. .03 g was charged, and the temperature was gradually raised to 220 ° C. while stirring under a nitrogen stream, and the condensation reaction was carried out for a total of 17 hours. By filtering after the reaction, a polyester polyol (X2-4) which is a high-viscosity liquid at room temperature was obtained. As a result of analysis by GPC, the number average molecular weight of the polyester polyol (X2-4) was 1,210, the hydroxyl value was 114, and the acid value was 0.5.

Synthesis Example 8 [Ester compound (X3) other than ester compound (X1) and polyester polyol (X2)]
A four-necked flask with an internal volume of 0.5 liter equipped with a thermometer, a stirrer, and a reflux condenser was charged with 132 g of trimethylolpropane, 366 g of benzoic acid, and 0.03 g of tetraisopropyl titanate as an esterification catalyst. The condensation reaction was carried out for a total of 17 hours by gradually raising the temperature to 220 ° C. with stirring underneath. By filtering after the reaction, an ester compound (X3-2) which is a high-viscosity liquid at room temperature was obtained. As a result of analysis by GPC, the number average molecular weight of the ester compound (X3-2) was 380, the hydroxyl value was 10, and the acid value was 0.3.

Example 1 (Modifier for Cellulose Ester Resin, Cellulose Ester Resin Composition and Optical Film)
100 parts of triacetyl cellulose (product name LT-35, vinegarization degree 61%, manufactured by Daicel Chemical Industries), 810 parts of methylene chloride, 90 parts of methanol, 7.5 parts of ester compound (X1-1), polyester compound (X2- 1) 2.5 was added and dissolved to obtain a dope solution containing the modifier for cellulose ester resin of the present invention. The dope solution was cast on a glass plate to a thickness of about 0.8 mm, left overnight at room temperature, and then dried at 50 ° C. for 30 minutes and 120 ° C. for 30 minutes to obtain a cellulose ester film having a film thickness of 60 μm. It was. The moisture permeability and dimensional stability of the obtained cellulose ester film with changes in humidity were evaluated according to the following method. The evaluation results are shown in Table 1.

<Evaluation method of moisture permeability>
The moisture permeability of the cellulose ester film was measured according to the method described in JIS Z 0208. The measurement conditions were a temperature of 40 ° C. and a relative humidity of 90%. Moisture resistance was evaluated according to the following criteria.
○: moisture permeability is less than or equal to 580g ^/ m 2 · 24h.
×: moisture permeability is more than 580g ^/ m 2 · 24h.

<Evaluation method of dimensional stability with changes in humidity>
The dimensional stability of the cellulose ester film (1) was evaluated by the expansion rate generated by changing the relative humidity from 20% RH to 80% RH. Specifically, the following method was followed.
Using TMA-SS6100 (manufactured by Seiko Instruments) equipped with a humidity control unit for high temperature and high humidity, a sample with a thickness of 60 μm and a width of 3 mm is fixed in a tension mode under the conditions of a load of 50 mN and a chuck distance of 20 mm. Humidity difference (80-0) increases the distance between chucks due to humidity change when humidifying from 0% RH humidity to 80% RH at a humidity rise rate of 2% RH per minute while keeping the sample temperature constant at 40 ° C. It was divided by = 80) and determined by the expansion rate (% /% RH) with respect to the change in humidity. The dimensional stability was evaluated according to the following criteria.
◯: The rate of change in moisture absorption dimension is 0.50% or less.
X: Moisture absorption dimensional change rate exceeds 0.50%.

Examples 2 to 13 and Comparative Examples 1 to 6
An optical film was obtained in the same manner as in Example 1 except that the formulations shown in Tables 1 to 5 were used. The evaluation was performed in the same manner as in the examples. The evaluation results are shown in Tables 1-5.

Footnotes in Table 5 X3-1: Sucrose benzoate

Claims (20)

The following formula (1)

(G in the formula is a residue of a polyhydric alcohol having 2 to 10 carbon atoms. A is an aromatic monocarboxylic acid residue having a structure in which some or all of hydrogen atoms on the aromatic ring are substituted with hydroxyl groups. Group. N is an integer of 2-6.)
One or more dicarboxylic acid residues selected from the group consisting of an ester compound (X1) represented by (X1) and an alkylenedicarboxylic residue having 2 to 4 carbon atoms, an orthophthalic acid residue and an isophthalic acid residue in the main chain skeleton. It contains a polyester polyol (X2) having a group and an alkylene glycol residue having 2 to 4 carbon atoms , a number average molecular weight of 300 to 1,500, and a hydroxyl value of 50 to 350. A characteristic modifier for cellulose ester resin. The modifier for cellulose ester resin according to claim 1, wherein G in the formula (1) is a residue of a chain-like aliphatic polyhydric alcohol having 2 to 8 carbon atoms. G in the formula (1) is a residue of a linear aliphatic polyhydric alcohol having 2 to 6 carbon atoms or a residue of a branched aliphatic polyhydric alcohol having 2 to 6 carbon atoms. The modifier for a cellulose ester resin according to claim 1. G in the formula (1) is an ethylene glycol residue, a propylene glycol residue, a 1,3-propanediol residue, a 2-methyl-1,3-propanediol residue, or 3-methyl-. The modifier for a cellulose ester resin according to claim 2 or 3, which is one or more residues selected from the group consisting of residues of 1,5-pentanediol. The modifier for cellulose ester resin according to claim 1, wherein A in the formula (1) is a residue of an aromatic monocarboxylic acid having a structure in which one of the hydrogen atoms on the aromatic ring is substituted with a hydroxyl group. The modifier for a cellulose ester resin according to claim 1 or 4, wherein A in the formula (1) is a residue of parahydroxybenzoic acid. The ester compound (X1) has a structure in which a polyhydric alcohol (g) having 2 to 6 valences of hydroxyl groups and 2 to 10 carbon atoms and a part or all of hydrogen atoms on the aromatic ring are substituted with hydroxyl groups. The modifier for a cellulose ester resin according to claim 1, which is obtained by reacting with an aromatic monocarboxylic acid (a) having. The modifier for a cellulose ester resin according to claim 7, wherein the polyhydric alcohol (g) having 2 to 10 carbon atoms is a chain aliphatic polyhydric alcohol having 2 to 8 carbon atoms. The polyhydric alcohol (g) having 2 to 10 carbon atoms is a linear aliphatic polyhydric alcohol having 2 to 6 carbon atoms or a branched aliphatic polyhydric alcohol having 2 to 6 carbon atoms. The modifier for a cellulose ester resin according to claim 7. The polyhydric alcohol (g) having 2 to 10 carbon atoms is ethylene glycol, propylene glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol. The modifier for a cellulose ester resin according to claim 7, which is one or more alcohols selected from the group consisting of. An aromatic monocarboxylic acid (a) having a structure in which a part or all of hydrogen atoms on the aromatic ring is substituted with a hydroxyl group is an aromatic having a structure in which one of the hydrogen atoms on the aromatic ring is substituted with a hydroxyl group. The modifier for a cellulose ester resin according to claim 7, which is a monocarboxylic acid. The modifier for cellulose ester resin according to claim 7, wherein the aromatic monocarboxylic acid (a) having a structure in which a part or all of hydrogen atoms on the aromatic ring is substituted with a hydroxyl group is parahydroxybenzoic acid. .. The modifier for a cellulose ester resin according to claim 1, wherein the polyester polyol (X2) has a number average molecular weight of 350 to 1,300 and a hydroxyl value of 85 to 320. Ortho phthalic acid residue in the polyester polyol (X2) is in the main chain skeleton, and one or more residues selected from the group consisting of adipic acid residue and succinic acid residue, an ethylene glycol residue or propylene glycol residue The modifier for a cellulose ester resin according to claim 1, which is a polyester polyol having. The one according to any one of claims 1 to 14 , wherein the mixing ratio [(X1) / (X2)] of the ester compound (X1) and the polyester polyol (X2) is 5/95 to 95/5 by mass ratio. Modifier for cellulose ester resin. A cellulose ester resin composition comprising the modifier for a cellulose ester resin according to any one of claims 1 to 15 and a cellulose ester resin. The cellulose ester resin composition according to claim 16, which contains 0.5 to 50 parts by mass of a modifier for cellulose ester resin with respect to 100 parts by mass of the cellulose ester resin. An optical film comprising the cellulose ester resin composition according to claim 16 or 17. The optical film according to claim 18, which is a polarizer protective film. A liquid crystal display device comprising the optical film according to claim 18 or 19.