KR101527905B1 - Additive for cellulose ester resin, cellulose ester resin composition using same, and film - Google Patents

Abstract

At least one aromatic dicarboxylic acid compound selected from the group consisting of terephthalic acid, terephthalic acid dialkyl ester, naphthalene dicarboxylic acid, naphthalene dicarboxylic acid dialkyl ester, biphenyl dicarboxylic acid and biphenyl dicarboxylic acid dialkyl ester (A) having a number average molecular weight of 300 to 3,000 obtained by an esterification reaction of the ester compound (a2). The additive for cellulose ester resin can provide an optical film which can impart excellent optical performance and moisture resistance by adding it to an optical film made of a cellulose ester resin and has excellent anti-bleeding properties under high temperature and high humidity.

Optical film, additive for cellulose ester resin, ester compound

Description

ADDITIVE FOR CELLULOSE ESTER RESIN, CELLULOSE ESTER RESIN COMPOSITION USING SAME, AND FILM BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an additive for a cellulose ester resin,

The present invention relates to a cellulose ester resin additive comprising an ester compound capable of imparting excellent optical performance to an optical film such as a polarizer protective film by being added to a cellulose ester resin, a cellulose ester resin composition using the same, .

2. Description of the Related Art In recent years, information devices such as a laptop computer and a television equipped with a liquid crystal display device capable of clearly displaying images and characters have been supplied to the market at a later date. In order to meet these demands, there is a demand for a high-contrast, high-contrast, high-contrast, and high- And so on.

The realization of the thinning of the information device is intended to reduce the width of the liquid crystal display device provided in the information device. The liquid crystal display device is roughly composed of a laminated structure body having a layer made of an electrode and a layer made of a liquid crystal material between two glass substrates. A polarizer is attached to a surface of the glass substrate opposite to the liquid crystal layer. As the polarizer, a protective film is usually pasted on both surfaces of a polarizer made of polyvinyl alcohol (PVA). The polarizer protective film is generally a cellulose ester resin film having high transparency, suitable strength and excellent adhesion to PVA.

However, in the above-mentioned cellulose ester resin film, penetration of moisture (moisture) can not be sufficiently prevented, and as a result, there is a problem that deterioration of the polarizer and peeling between the polarizer and the film occur. Therefore, conventionally, as a polarizer protective film, a film obtained by adding a plasticizer such as triphenyl phosphate to a cellulose ester resin has been used as one having good moisture permeability.

The polarizer protective film may vary depending on the structure of the liquid crystal display device and the like, but in general, a film having a thickness of about 80 탆 is often used. 2. Description of the Related Art In recent years, along with the progress of thinning of a liquid crystal display device, studies have been made on making a thinned protective film and a film having a thickness of about 30 to 50 m as a reference.

While such thinning is being studied, the conventional polarizer protective film containing the plasticizer and the cellulose ester resin has a problem that the moisture resistance is significantly lowered when the film thickness is reduced to a required level .

Further, since the plasticizer has insufficient compatibility with the cellulose ester resin, bleeding (bleeding) of the plasticizer from the film surface may occur due to the influence of heat and humidity. Therefore, when it is used in a liquid crystal display device, the plasticizer bleeds on the surface of the film due to the influence of the heat of the backlight and the like, so that blurring occurs and images and the like can not be clearly displayed.

In addition, the polarizer protective film is required to have excellent surface smoothness at a level that does not inhibit display such as a clear image. Thus, in order to obtain surface smoothness, the polarizer protective film is produced by the so-called solution softening method in which the organic solvent solution of the cellulose ester resin composition containing the above plasticizer is dripped into a film and subsequently heated and dried. However, since the plasticizer is a compound having a low molecular weight, there is a problem that the volatile plasticizer tends to volatilize in the heating and drying process, and adhere to a web or a roll constituting the film production apparatus to contaminate the apparatus.

The ease of bleeding and volatilization of the plasticizer has hitherto been problematic in applications other than the above-mentioned polarizer protective film, for example, in the use of toys and food utensils. As a plasticizer for solving this problem, there have been proposed plasticizers or phthalic acid-based polyesters mainly comprising an acetylated product of a sugar alcohol (for example, see Patent Documents 1 and 2).

However, a film obtained by molding a resin composition containing a phthalic acid-based polyester obtained by reacting acetylated sugar alcohol with phthalic anhydride and 1,3-butanediol specifically described as phthalic acid-based polyester as a plasticizer, They do not have the moisture permeability at a level that can be used as a polarizer protective film, and these plasticizers still have a problem that they are still easy to bleed under high temperature and high humidity.

Furthermore, it has been reported that a film containing an ester compound and a cellulose resin obtained by reacting 2-ethyl-2-butyl-1,3-propanediol with benzoic acid has excellent moisture permeability (see, for example, 3).

However, the film containing the ester compound and the cellulose-based resin is generally used at a thickness of about 80 占 퐉, but when it is thinned to about 40 to 50 占 퐉, sufficient moisture permeability can not be maintained, . Further, since the ester compound is a relatively low molecular weight compound, it is easily volatilized during the heating and drying process in the production of the film, and there is a problem that the rolls constituting the film production apparatus are contaminated.

[0003] However, in addition to the above-mentioned thinning, various characteristics are demanded for an information device having a liquid crystal display device depending on its use. Particularly, in a liquid crystal television, there is a strong demand for a wide viewing angle accompanying a large screen.

The optical viewing angle of the liquid crystal display device has been studied more than ever before. For example, in order to impart an optical compensation function to the polarizer protective film made of a cellulose ester resin, which can contribute to a wide viewing angle, retardation A method of adding an aromatic compound as a synergist has been proposed (see, for example, Patent Document 4).

Here, the optical compensation film compensates the phase difference caused by the liquid crystal material constituting the liquid crystal display device, and plays an important role in realizing "wide viewing angle". If the phase difference is not compensated, there is a problem that the color or shape of the image or the like displayed when the liquid crystal screen is viewed in the oblique direction is different from the original one.

Therefore, as an optical compensation film, a film having optical anisotropy is used in order to develop a wide viewing angle. Here, the optical performance in the present invention refers to optical anisotropy, and in general, the degree of optical anisotropy can be grasped by the retardation value. The retardation value (hereinafter referred to as " Rth value ") of the retardation value of the optical compensation film in the thickness direction of the film can be adjusted to any desired value by adding something called a retardation increasing agent. However, the general retardation enhancer described in Patent Document 4 has a problem in that compatibility with the cellulose ester resin is insufficient, so that bleeding occurs when the optical compensation film is left under high temperature and high humidity, and transparency is lost .

The Rth value in the thickness direction is a value defined by the following equation (1).

Rth = {(nx + ny) / 2-nz} d (nm) (1)

(Where nx is the refractive index in the direction of the slow axis in the film plane, ny is the refractive index in the direction of the fast axis in the film plane, nz is the refractive index in the thickness direction of the film, Film thickness (nm)

Thus, the present inventors have found that, as an additive for imparting excellent optical performance to a polarizer protective film, an ester compound comprising a mixture of a diester compound having an aromatic group at both terminals and a polyester compound having both terminals and an aromatic cyclic structure in the molecular chain (See Patent Document 5).

However, the optical compensation film has been required to have higher optical performance, that is, a higher Rth value, as the technology level becomes higher. If an optical compensation film made of a cellulose ester resin having an excellent retardation compensation function can be obtained, the number of films required for four films can be further reduced, and the film can be made thinner. A polarizing plate, and further a liquid crystal display device, but such a material has not yet existed.

[Patent Literature]

[Patent Document 1] Japanese Patent Application Laid-Open No. 2000-351871

[Patent Document 2] JP-A-61-276836

[Patent Document 3] JP-A-2003-096236

[Patent Document 4] Japanese Patent Application Laid-Open No. 2000-284124

[Patent Document 5] Japanese Unexamined Patent Application Publication No. 2008-069225

A problem to be solved by the present invention is to provide a film made of a cellulose ester resin which can impart excellent optical performance and moisture permeability to an ester compound having excellent resistance to bleeding under high temperature and humidity, , And a cellulose ester resin composition using the same.

The present invention also provides a film or an optical film comprising the cellulose ester resin composition.

As a result of intensive studies, the present inventors have found that when an ester compound having a molecular weight within a specific range among ester compounds obtained by esterifying a diol and a specific aromatic dicarboxylic acid compound is used as an additive for cellulose ester resin, It has been found that an additive for a cellulose ester resin can be obtained which can impart excellent optical performance and moisture permeability to a film and is excellent in bleeding resistance under high temperature and humidity and is hard to volatilize during the production process of a film.

That is, the present invention relates to a process for producing a diol (a1) which comprises reacting a diol (a1) with at least one member selected from the group consisting of terephthalic acid, terephthalic acid dialkyl ester, naphthalene dicarboxylic acid, naphthalene dicarboxylic acid dialkyl ester, biphenyldicarboxylic acid and biphenyldicarboxylic acid dialkyl ester A cellulose ester resin additive comprising an ester compound (A) obtained by esterifying an aromatic dicarboxylic acid compound (a2) having a number average molecular weight of 300 to 3,000, a cellulose ester resin composition containing the additive, And to provide an optical film.

The additive for cellulose ester resin of the present invention can impart excellent optical performance and moisture resistance to a film by adding it to a cellulose ester resin. Further, the additive for cellulose ester resin of the present invention has an excellent effect that it has anti-bleeding property under high temperature and humidity, and is hardly volatilized in the film production process. Further, the film comprising the cellulose ester resin composition containing the additive for cellulose ester resin of the present invention can be used for various optical films, and is particularly useful for a polarizer protective film requiring an optical compensation function.

The ester compound (A) which is an additive for the cellulose ester resin of the present invention will be described.

Examples of the ester compound (A) of the present invention include an ester compound having a structure represented by the following general formulas (I) to (VI), characterized in that the terminal thereof is a hydroxyl group or an alkyl ester group.

(Wherein G in the general formula (I) represents a residue of a diol (a1), T represents a residue of an aromatic dicarboxylic acid compound (a2), R represents an alkyl group, n represents a repeating unit, Integer)

The above-mentioned " residue " means the following. The "residue" of the diol (a1) represents the remaining organic groups having two hydroxyl groups of the diol (a1) removed. The "residue" of the aromatic dicarboxylic acid compound (a2) refers to an aromatic dicarboxylic acid compound (a2) in the case where the aromatic dicarboxylic acid compound (a2) is an aromatic carboxylic acid, the remaining organic group in which the carboxyl group of the aromatic carboxylic acid is removed, In the case of an aromatic carboxylic acid alkyl ester, it represents the remaining organic group in which the alkoxycarbonyl group of the aromatic carboxylic acid alkyl ester is removed.

More specifically, n in the general formulas (I) to (VI) may be an integer of 1 or more, but is preferably an integer of 1 to 15. The ester compound (A) is usually a mixture of a plurality of ester compounds having different n numbers. For example, the ester compound (A1) in which n is 1 in the general formulas (I) to (VI) is used in the range of 25 to 40 mass%, the general formulas (I) to (VI) (A3) in the range of 20 to 40 mass%, and n in the formulas (I) to (VI) is in the range of 35 to 45 mass% (A) is capable of imparting further excellent optical performance and moisture resistance to an optical film comprising a cellulose ester resin, and is excellent in bleeding resistance under high temperature and humidity, A) is difficult to volatilize.

The hydroxyl group value (hydroxyl value) of the ester compound (A) of the present invention is preferably in the range of 0.1 to 200, more preferably in the range of 1 to 150. When the hydroxyl value of the ester compound (A) is within this range, the optical film has good anti-bleeding property and moisture resistance. Further, when an optical film is used for the polarizer protective film, deterioration of the polarizer can be further suppressed. This hydroxyl value is derived from the terminal hydroxyl group of the ester compound (A) and the diol (a1) used as a raw material.

The additive for cellulose ester resin of the present invention is required to have high volatility particularly when used in an optical film. The volatility may be determined by measuring the heating loss value of the additive. For example, when used in a polarizer protective film of an optical film, the heating loss value of the cellulose ester resin additive is 1.0% by mass or less, By mass to 1.0% by mass, more preferably 0.01 to 0.80% by mass, and particularly preferably 0.01 to 0.50% by mass. When the heating weight loss value is within this range, the durability of the polarizer protective film, the molding processability, and the recycling of the organic solvent used in the production of the film by the solution casting method are excellent, and there is no problem in terms of production and practical use. Details of the conditions for measuring the weight loss value are described in Examples.

The number average molecular weight of the ester compound (A) as the additive for the cellulose ester resin of the present invention is in the range of 300 to 3,000 in order to impart the volatility and the compatibility with the cellulose ester resin (B) and the bleeding resistance. It is more preferable that the number average molecular weight is in the range of 330 to 2,700. An optical film comprising a cellulose ester resin composition containing an ester compound (A) having a number average molecular weight range has excellent optical performance and moisture permeability, and is capable of providing an ester compound (A) even under high temperature conditions, Can be suppressed and a film having excellent durability under a humid condition can be obtained.

When the number average molecular weight of the ester compound (A) is 300 or less, a large amount of a monomer component or a low molecular weight component remains, so that the volatility remarkably deteriorates. On the other hand, when the number average molecular weight of the ester compound (A) is 3,000 or more, the compatibility with the cellulose ester resin (B) is deteriorated, so transparency of the film is lost and it becomes difficult to use it as an optical film in particular.

The number average molecular weight of the ester compound (A) can be measured by using a gel permeation chromatograph (GPC) using tetrahydrofuran (THF) as an eluent and converted into standard polystyrene. Detailed measurement conditions will be described in Examples.

The ester compound (A) is at least one compound selected from the group consisting of terephthalic acid, terephthalic acid dialkyl ester, naphthalene dicarboxylic acid, naphthalene dicarboxylic acid dialkyl ester, biphenyl dicarboxylic acid and biphenyl dicarboxylic acid dialkyl ester Can be produced by subjecting at least one aromatic dicarboxylic acid compound (a2) to an esterification reaction.

The reaction equipment of the ester compound (A) of the present invention can be produced by using reaction equipment corresponding to pressurization and depressurization. The reaction equipment can be produced by using a general apparatus having a reactor, a stirrer, a rectification tower, a cooler, a pump for depressurizing, and the like.

The ester compound (A) can be obtained, for example, by charging the diol (a1) and the aromatic dicarboxylic acid compound (a2) into a reactor equipped with a thermometer, a stirrer and a reflux condenser, raising the temperature, And the reaction is carried out at a predetermined temperature. After the reaction, unreacted monomers and low molecular weight components can be obtained by performing a reduced pressure reaction for the purpose of promoting the reaction.

The diol (a1) used in the present invention will be specifically described below.

Examples of the diol (a1) include ethylene glycol, 1,2-propanediol (propylene glycol), 1,3-propanediol, 1,2-butanediol, 1,3- Pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,3-propanediol, 3,3-dibutyl-1,3-propanediol, 1, 2-dodecanediol, 1,4-cyclohexanedimethanol, neopentyl glycol, , 2-pentanediol, 1,3-pentanediol, 2,3-pentanediol, 2,4-pentanediol, 2-methyl- , 4-pentanediol, 1,2-hexanediol, 1,3-hexanediol, 1,4-hexanediol, 1,5-hexanediol, n-butoxyethylene glycol, cyclohexanedimethanol, Diethylene glycol, dipropylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, hexylene glycol, and the like. These diols may be used alone or in combination of two or more.

As the diol (a1), an aromatic diol may also be used. Examples of the aromatic diol include bisphenol A, ethylene oxide adducts of bisphenol A, and propylene oxide adducts.

Of the diols (a1), the most preferred diols include those having a carbon number of 2 to 12. Specific examples thereof include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 1,2-butanediol, Butanediol, 1,5-pentanediol, neopentyl glycol, 1,2-cyclopentanediol, 1,3-cyclopentanediol, 1,4-cyclohexanediol, 1,6- . These diols may be used alone or in combination of two or more.

The ester compound (A) obtained by using a diol having branched alkyl chains such as 1,2-propanediol, 2-methyl-1,3-propanediol, neopentyl glycol and the like can be obtained by subjecting a cellulose ester resin (B) It is also preferable that the optical film is excellent in compatibility and excellent in bleeding resistance under an environment of high temperature and high humidity as an optical film.

The use of ethylene glycol (a1-1) and 1,2-propanediol (a1-2) together as the diol (a1) is particularly preferable because an optical film having excellent optical performance, that is, a polarizer protective film can be obtained Do.

When the ethylene glycol (a1-1) and the 1,2-propanediol (a1-2) are used in combination, the ethylene glycol (a1-1) and the 1,2-propanediol (a1- (A1-1) / (a1-2) of the structural units derived from the structural units derived from the structural units (A) and (B) is preferably in the range of 85/15 to 10/90 (mol% ) Is more preferable. When the molar composition ratio (a1-1) / (a1-2) of the ethylene glycol (a1-1) and the 1,2-propanediol (a1-2) falls within this range, compatibility with the cellulose ester resin (B) In the case of producing a film by the method, since the solubility in an organic solvent becomes favorable, sufficient transparency can be imparted to the film. In addition, the optical performance can be sufficiently manifested.

When the above-mentioned ethylene glycol (a1-1) and 1,2-propanediol (a1-2) are used in combination, alcohols other than these diols may be used. Specific examples of the monoalcohols include methanol, ethanol, 1-butanol, 2-butanol, hexanol, cyclohexanol, amyl alcohol, octyl alcohol, lauryl alcohol, methyl lactate, ethyl lactate, Butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1 , 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,4-cyclohexanedimethanol, neopentyl glycol, 3 1,3-propanediol, 3,3-dibutyl-1,3-propanediol, 1,2-pentanediol, 1,3-pentanediol, 2,3- Pentanediol, 1, 2-hexanediol, 1, 3-hexanediol, 1, 2-pentanediol, Hexane diol, 1,5-hexane diol, n-butoxyethylene glycol, cyclohexane dimethanol, hydrogenated bisphenol A, dimer diol, diethylene glycol, dipropylene glycol, triethylene glycol, Alkylene may be a glycol, polypropylene glycol, tetramethylene glycol, hexylene glycol, bisphenol A, bisphenol A ethylene oxide adducts, propylene oxide adducts and the like. Examples of other polyhydric alcohols include glycerin, sorbitol, ribitol, and pentaerythritol. These alcohols may be used alone or in combination of two or more.

Next, at least one aromatic dicarboxylic acid selected from the group consisting of terephthalic acid, terephthalic acid dialkyl ester, naphthalene dicarboxylic acid, naphthalene dicarboxylic acid dialkyl ester, biphenyl dicarboxylic acid and biphenyl dicarboxylic acid dialkyl ester used in the present invention The compound (a2) will be specifically described below.

The aromatic dicarboxylic acid compound (a2) used in the present invention is selected from the group consisting of terephthalic acid, terephthalic acid dialkyl ester, naphthalene dicarboxylic acid, naphthalene dicarboxylic acid dialkyl ester, biphenyl dicarboxylic acid and biphenyl dicarboxylic acid dialkyl ester Or more.

Examples of the alkyl group of the terephthalic acid dialkyl ester, naphthalenedicarboxylic acid dialkyl ester and biphenyl dicarboxylate dialkyl ester include those having 1 to 8 carbon atoms, and the number of carbon atoms or more may be a straight chain alkyl group or a branched alkyl group. Examples of such alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, pentyl, hexyl, cyclohexyl, heptyl and octyl. The two alkyl groups of the aromatic dicarboxylic acid dialkyl ester may be the same or different. The aromatic dicarboxylic acid dialkyl ester may be used singly or in combination of two or more kinds.

Examples of the terephthalic acid dialkyl ester include dimethyl terephthalate, diethyl terephthalate, dipropyl terephthalate, dibutyl terephthalate, dipentyl terephthalate, dihexyl terephthalate, diheptyl terephthalate and the like. Among these terephthalic acid dialkyls, dimethyl terephthalate is preferable because it can give excellent optical performance to an optical film made of a cellulose ester resin composition and also has excellent bleed resistance under high temperature and high humidity conditions, thereby obtaining a film having durability .

Examples of the naphthalenedicarboxylic acid dialkyl ester include dimethyl naphthalenedicarboxylate, diethyl naphthalenedicarboxylate, dipropylenedicarboxylate, dibutyl naphthalenedicarboxylate, dipentyl naphthalenedicarboxylate, dihexyl naphthalenedicarboxylate, diheptyl naphthalenedicarboxylate . In these naphthalene dicarboxylic acid dialkyl esters, there are various substitution positions of the carboxylic acid alkyl ester, but it is preferable that the 2,6-position of the naphthalene is a carboxylic acid alkyl ester, and the 2,6-naphthalene di More preferred is dimethylcarboxylate.

Examples of the biphenyldicarboxylate dialkyl ester include diethyl biphenyl dicarboxylate, diethyl biphenyl dicarboxylate, diphenyl biphenyl dicarboxylate, dibutyl biphenyl dicarboxylate, dipentyl biphenyl dicarboxylate, dihexyl biphenyl dicarboxylate , Diheptyl biphenyl dicarboxylate, and the like. In these biphenyldicarboxylate dialkyl esters, there are various substitution positions of the alkyl carboxylate ester, but it is preferable that the 4,4 'position of the biphenyl is a carboxylic acid alkyl ester, and the 4, More preferred is 4'-biphenyldicarboxylate.

In the production of the ester compound (A), other dicarboxylic acids, alkyl ester compounds thereof, or carbonate compounds may be used in combination as long as the present invention is not impaired. As the dicarboxylic acid or its alkyl ester compound, an aliphatic dicarboxylic acid or an aromatic dicarboxylic acid or an alkyl ester compound thereof may be used. Examples of the aliphatic dicarboxylic acid or its alkyl ester compound include succinic acid, dimethyl succinate, glutaric acid, dimethyl glutarate, adipic acid, dimethyl adipate, diethyl adipate, dibutyl adipate, , Dimethyl pimelate, suberic acid, dimethylsuberate, azelaic acid, dimethyl azelate, sebacic acid, dimethyl sebacate, decanedicarboxylic acid, decanedicarboxylic acid dimethyl, cyclohexanedicarboxylic acid, dimethylcyclohexanedicarboxylic acid dimethyl, dimer acid , Dimethyl dimer acid, fumaric acid, dimethyl fumarate and the like. Examples of the aromatic dicarboxylic acid or its alkyl ester compound include phthalic acid, dimethyl phthalate, isophthalic acid, dimethyl isophthalate, and the like. Examples of the carbonate compound include dimethyl carbonate, diethyl carbonate, and dibutyl carbonate. These other dicarboxylic acids or their alkyl ester compounds or carbonate compounds may be used alone or in combination of two or more.

When the diol (a1) and the aromatic dicarboxylic acid compound (a2) are subjected to the esterification reaction, the reaction may be carried out in the presence of an esterification catalyst, if necessary, for the purpose of promoting the reaction.

As the esterification catalyst, there may be mentioned at least one kind of metal or organometallic compound selected from the group consisting of Group 2, Group 3, and Group 4 of the periodic table. More specifically, it includes, for example, metals such as titanium, tin, zinc, aluminum, zirconium, magnesium, hafnium, and germanium; Titanium tetrabutoxide, titanium oxyacetyl acetonato, tin octanoate, tin 2-ethylhexane, acetylacetonato zinc, zirconium tetrachloride, zirconium tetrachloride tetrahydrofuran complex, hafnium tetrachloride, 4 Metal complex compounds such as hafnium chloride tetrahydrofuran complex, germanium oxide, and tetraethoxy germanium. Among these, titanium alkoxides having good reactivity with the diol (a1) and the aromatic dicarboxylic acid compound (a2), ease of handling and storage stability of the ester compound (A) obtained by the esterification reaction, specifically titanium alkoxides having titanium tetraisopropoxide Titanium tetrabutoxide, titanium oxyacetylacetonato, and the like are preferably used.

The amount of the esterification catalyst to be used is usually in the range capable of controlling the reaction between the diol (a1) and the aromatic dicarboxylic acid compound (a2) and capable of inhibiting the coloration of the ester compound (A) And is preferably in the range of 10 to 1000 ppm, more preferably in the range of 20 to 500 ppm, particularly preferably in the range of 30 to 300 ppm, based on the total amount of the diol (a1) and the aromatic dicarboxylic acid compound (a2) . Since the coloring of the ester compound (A) lowers the transparency of the film, it is necessary to pay particular attention to the use of an optical film which requires high transparency.

The timing of adding the esterification catalyst may be added at the same time as the charging of the diol (a1) and the aromatic dicarboxylic acid compound (a2), or may be added at the time of starting the decompression during the heating.

For the purpose of causing the ester compound (A) to be branched and to have a high molecular weight when reacting the diol (a1) with the aromatic dicarboxylic acid compound (a2) within a range that does not impair the effect of the present invention, Glycerin, pentaerythritol, trimellitic acid, and pyromellitic acid, and isocyanates such as carboxylic acid and hexamethylene diisocyanate may also be used.

The charging molar ratio [(a1) / (a2)] of the diol (a1) and the aromatic dicarboxylic acid compound (a2) in preparing the ester compound (A) is preferably in the range of 0.5 / 1 to 2/1 , More preferably in the range of 0.8 / 1 to 1.5 / 1. Within this range, the ester compound (A) as an additive for the cellulose ester resin of the present invention can be produced. In particular, when the charging mole ratio (a1) / (a2) is in the range of 0.5 / 1 to 1/1, the ratio of the terminal group of the ester compound (A) to the alkyl ester group is increased, An optical film having a small fluctuation range of the Rth value can be obtained.

The reaction temperature at the time of producing the ester compound (A) is preferably a temperature at which the reaction (dehydration reaction, dehydration reaction, etc.) is carried out while considering the boiling point, reactivity, sublimation property of the diol (a1) and the aromatic dicarboxylic acid compound (a2) Or a dealcoholization reaction) proceeds, the range is preferably 120 deg. C to 300 deg. C, and more preferably 150 deg. C to 280 deg. The reaction time for producing the ester compound (A) is preferably 2 hours or more, and more preferably 4 to 100 hours. The degree of reduced pressure when producing the ester compound (A) is preferably 30,000 Pa or less, more preferably 25,000 Pa or less, and particularly preferably 5,000 Pa or 20,000 Pa. Within this range, unreacted monomers and low molecular weight components can be removed quickly, and the reaction can be promoted.

The ester compound (A) may be prepared by separately preparing different kinds of the ester compound (A), and then mixing them to prepare an additive for the cellulose ester resin of the present invention. In the additive for cellulose ester resin of the present invention, an additive other than the ester compound (A) may be added at the time of production as long as the effects of the present invention are not lost. Examples of the additives other than the ester compound (A) include a catalyst deactivator for deactivating the catalytic activity of the esterification catalyst and an antioxidant for suppressing the coloration of the ester compound (A).

As the catalyst deactivator, for example, a chelating agent can be exemplified, and an organic chelating agent or an inorganic chelating agent can be used. Examples of the organic chelating agent include amino acids, phenols, hydroxycarboxylic acids, diketones, amines, oximes, phenanthrolines, pyridine compounds, dithio compounds, diazo compounds, thiols and porphyrins, nitrogen Phenols having an atom, carboxylic acids, and the like. Examples of the inorganic chelating agent include phosphorus compounds such as phosphoric acid, phosphoric acid ester, phosphorous acid and phosphorous acid ester. These are preferably added in the range of 10 to 2,000 ppm with respect to the total amount of the diol (a1) and the aromatic dicarboxylic acid compound (a2) as raw materials.

Next, the cellulose ester resin composition containing the ester compound (A) will be described.

The cellulose ester resin (B) used in the cellulose ester resin composition of the present invention is one obtained by esterifying a part or all of the hydroxyl groups of cellulose obtained from cotton linter, wood pulp, kenaf and the like. Among them, a film obtained by using a cellulose ester resin obtained by esterifying cellulose obtained from a cotton linter is easy to peel off from the metal support constituting the apparatus for producing a film, and the production efficiency of the film can be improved. Do.

Specific examples of the cellulose ester resin (B) include, for example, cellulose acetate, cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate propionate butyrate, cellulose acetate phthalate and cellulose nitrate. These cellulose ester resins may be used alone or in combination of two or more. When a film comprising the cellulose ester resin composition of the present invention is used as an optical film, particularly a polarizer protective film, it is preferable to use cellulose acetate because a film excellent in mechanical properties and transparency can be obtained.

As the cellulose acetate, the average degree of acetalization (amount of bound acetic acid) is preferably in the range of 50.0 to 62.5 mass%, more preferably in the range of 52.5 to 61.5 mass% in terms of the average degree of acetalization. By using cellulose acetate which is the average degree of acetalization in this range, the moisture permeability of the optical film made of the obtained cellulose ester resin composition can be improved. The average degree of acetalization is a mass ratio of acetic acid produced by saponifying the cellulose acetate based on the mass of the cellulose acetate.

The number average molecular weight of the cellulose ester resin (B) is preferably 30,000 to 300,000, more preferably 50,000 to 200,000. By using cellulose acetate having a number average molecular weight within this range, the mechanical properties of the obtained film can be improved.

The cellulose ester resin composition of the present invention preferably contains the ester compound (A) in an amount of 0.5 to 50 parts by mass based on 100 parts by mass of the cellulose ester resin (B). In order to further improve the compatibility and bleed resistance between the cellulose ester resin (B) and the ester compound (A), the ester compound (A) is preferably used in an amount of 1 to 40 parts by mass relative to 100 parts by mass of the cellulose ester resin (B) And more preferably in the range of 1 part by mass to 100 parts by mass. When the cellulose ester resin composition containing the ester compound (A) in this range is used, an optical film having excellent optical performance, moisture resistance, and bleeding resistance under high temperature and high humidity can be obtained.

In addition, various additives other than the ester compound (A) may be added to the cellulose ester resin composition of the present invention within a range not impairing the present invention.

Examples of the various additives include additives such as a modifier (including a plasticizer), an ultraviolet absorber, a retardation enhancer, a resin, a matting agent, a deterioration inhibitor (e.g., an antioxidant, a peroxide dissolution inhibitor, Additives, etc.), dyes, and the like. These additives may be added together when the cellulose ester resin (B) and the ester compound (A) are dissolved and mixed in an organic solvent in the solution casting method described later.

Examples of the modifier (including the plasticizer) include phosphoric acid esters such as triphenyl phosphate, tricresyl phosphate, and cresyldiphenyl phosphate; Phthalic acid esters such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate and di-2-ethylhexyl phthalate; Ethyl phthalyl ethyl glycolate, butyl phthalyl butyl glycolate, trimethylol propane tribenzoate, pentaerythritol tetraacetate, and tributyl acetyl citrate.

Examples of the ultraviolet absorber include oxybenzophenone compounds, benzotriazole compounds, salicylic ester compounds, benzophenone compounds, cyanoacrylate compounds, and nickel complex salt compounds. The blending amount of 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 (B).

As the retardation increasing agent, there is no particular limitation as long as the retardation value, that is, the Rth value, is increased. For example, a liquid crystal compound such as 4-cyano-4'-pentylbiphenyl, Dicarboxylic acid ester compounds, and compounds having 1,3,5-triazine rings. The blending amount of the retardation increasing agent is preferably 0.01 to 20 parts by mass, more preferably 1 to 10 parts by mass, per 100 parts by mass of the cellulose ester resin (B).

Examples of the resin include a polyester resin (for example, polyethylene terephthalate, polymethyl methacrylate, etc.), a polycarbonate resin, a polyester ether resin, a polyurethane resin, an epoxy resin, a toluene sulfonamide resin, .

Examples of the matting agent include silicon oxide, titanium oxide, aluminum oxide, calcium carbonate, calcium silicate, aluminum silicate, magnesium silicate, calcium phosphate, kaolin and talc. 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 (B).

As the dyes, conventionally known dyes generally used may be used, and the amount thereof is not particularly limited as long as the dyes do not hinder the purpose of the present invention.

The cellulose ester resin composition containing the additive for cellulose ester resin comprising the ester compound (A) of the present invention can be used for a film and also for an optical film.

The film of the present invention can be obtained by molding the cellulose ester resin composition into a film. Examples of the molding method include a method of molding the cellulose ester resin composition into a film by melt kneading the cellulose ester resin composition with an extruder or the like, and using a T-die or the like.

The film of the present invention can also be obtained by a solution casting method in which a resin solution obtained by uniformly dissolving and mixing the cellulose ester resin composition in an organic solvent is plied on a metal support and dried, . When the film is obtained by the solution casting method, since the orientation of the cellulose ester resin (B) in the film during the molding can be suppressed, the resulting film exhibits substantially optical isotropy. The film exhibiting optical isotropy can be used as a member such as a liquid crystal display as an optical film, and is particularly useful as a polarizer protective film. Further, since the film obtained by this solution casting method is characterized in that unevenness is not easily formed on its surface and excellent surface smoothness is obtained, the solution casting method is a more preferable film casting method.

The solution casting method comprises a first step of dissolving the cellulose ester resin (B) and the ester compound (A) in an organic solvent, and then causing the obtained resin solution to be poured on a metal support; A second step of drying to form a film, and a third step of removing the film formed on the metal support from the metal support and heating and drying the film.

The metal support used in the first step may be an endless belt or a metal in the form of a drum, for example, stainless steel whose surface has been subjected to mirror finish. When the resin solution is softened on the metal support, it is preferable to use a resin solution that has been filtered through a filter in order to prevent foreign matter from entering the film to be obtained.

As the drying method in the second step, for example, by bringing wind in the temperature range of 30 to 50 占 폚 into contact with the upper and lower surfaces of the metal support, about 50 to 80% by mass of the organic solvent contained in the flexible resin solution Is evaporated to form a film on the metal support.

The third step is a step of peeling the film formed in the second step from the metal support and heating and drying at a higher temperature than the second step. As the heating and drying method, for example, a method of raising the temperature stepwise in the temperature range of 100 to 160 DEG C is preferable because the dimensional stability is improved. By heating and drying in the temperature range described above, the organic solvent remaining in the film obtained in the second step can be almost completely removed.

The concentration of the solution of the cellulose ester resin composition in the resin solution is preferably in the range of 3 to 50 mass%, more preferably in the range of 5 to 40 mass%.

The organic solvent is not particularly limited as long as it can dissolve the cellulose ester resin (B) and the ester compound (A). For example, in the case of using cellulose acetate as the cellulose ester resin (B) As good solvents for acetates (good solvents), for example, organic halogen compounds such as methylene chloride and dioxolanes can be used. It is preferable to use a poor solvent (poor solvent) such as methanol, ethanol, 2-propanol, n-butanol, cyclohexane or cyclohexanone in combination with the good solvent to improve the production efficiency of the film Do. When a mixture of a good solvent and a poor solvent is used, the mass ratio is preferably in the range of good solvent / poor solvent = 75/25 to 95/5 (mass%).

The film thickness of the film of the present invention is preferably in the range of 10 to 1,000 mu m, more preferably in the range of 20 to 500 mu m, and further preferably in the range of 30 to 200 mu m. When the film of the present invention is used as an optical film, the film thickness is preferably in the range of 10 to 150 mu m. When the film is used as a polarizer protective film in an optical film, if the film thickness is in the range of 25 to 100 mu m, it is possible to make the liquid crystal display thinner. Further, it is also possible to provide a film having excellent film strength, dimensional stability, Lt; / RTI > Further, in the present invention, the bleeding resistance and the dimensional stability may be referred to as durability.

The optical film of the present invention can also be used for a polarizer protective film which requires an optical compensation function. This polarizer protective film is required to have a certain range of anisotropy in accordance with liquid crystal display systems such as TN (Twisted Nematic), VA (Vertically Aligned) and OCB (Optically Compensatory Bend).

The optical film of the present invention preferably has an Rth value of 100 nm or more, and more preferably 100 to 500 nm in Rth value because it can effectively compensate the retardation derived from the liquid crystal material.

In order to obtain a polarizer protective film having desired optical anisotropy, it is possible to adjust the compounding ratio of the additive for cellulose ester resin comprising the ester compound (A) of the present invention. Particularly, since the additive for cellulose ester resin of the present invention can obtain a high Rth value by adding a small amount, it is possible to provide a liquid crystal display device employing a liquid crystal display system such as VA, OCB, and TN in which a relatively high Rth value is required. The desired Rth value can be adjusted while maintaining the bleeding property.

The reason why the optical film of the present invention exhibits excellent optical performance is thought to be that the chemical structure of the ester compound (A) and its intermolecular interaction contribute. Specifically, it is preferable that the diol (a1) and the aromatic dicarboxylic acid compound (a2), which are the raw materials of the additive for the cellulose ester resin comprising the ester compound (A) of the present invention, It is presumed that the electron density is high because it is considered that the effect of the dicarboxylic acid compound (a2) forms a π-π bond between the molecules of the polyester. When the ester compound (A) having high planarity and high electron density is captured as a refractive index ellipsoid, the ester compound (A) forms a highly anisotropic structure in the cellulose ester resin (B) .

When ethylene glycol (a1-1) and 1,2-propanediol (a1-2) are used in combination as the diol (a1) as a raw material for the additive for cellulose ester resin comprising the ester compound (A) 1,2-propanediol (a1-2) is believed to contribute to the compatibility of the ester compound (A) and the cellulose ester resin (B) and to the improvement of the solvent solubility in the production of the film. On the other hand, It is considered that the ethylene glycol (a1-1) having a short distance and a high linearity contributes to the improvement of the optical anisotropy, that is, the Rth value. Accordingly, it is found that the compatibility with the cellulose ester resin (B) or the solvent solubility in the production of the film can be improved by using ethylene glycol (a1-1) and 1,2-propanediol (a1-2) It is presumed that the effect of exhibiting excellent optical performance can be achieved at the same time.

The moisture permeability of the optical film of the present invention will be described. If the film thickness of the optical film of the present invention is 80 탆, the film made of the cellulose ester resin composition (B) has a moisture permeability of 800 to 900 g / m ² 24 h, for example, m ² · 24 h or less, and more preferably, a moisture permeability in the range of 100 to 600 g / m ² · 24 h is obtained. Within this range, even if the thickness of the obtained optical film is reduced to about 20 to 60 탆, it has excellent moisture permeability.

The film of the present invention is not only excellent in optical performance but also excellent in moisture permeability, transparency, nonvolatility, anti-bleeding property under high temperature and high humidity, and can be used, for example, as an optical film of a liquid crystal display device or a support for a silver halide photo- have. Examples of the optical film include a polarizer protective film, a retardation film, a reflection plate, a viewing angle improving film, an anti-glare film, an anti-reflection film, an antistatic film and a color filter. Among these optical films, in addition to the excellent properties as described above, a film having a high Rth value can be used as a polarizer protective film having a viewing angle compensation function.

Hereinafter, the present invention will be described in detail by way of examples and comparative examples.

[Example 1] Production of ester compound (A-1)

392 g of 1,2-propanediol (hereinafter referred to as " PG ") and 800 g of dimethyl terephthalate (hereinafter referred to as " DMT ") were charged into a three liter four liter flask equipped with a thermometer, a stirrer and a reflux condenser And raised the temperature. When the temperature in the flask reached 130 占 폚, tetraisopropyl titanate as an esterification catalyst was added in an amount of 60 ppm relative to the total amount of PG and DMT, and while methanol was distilled off at 185 占 폚 while stirring in a nitrogen stream The reaction was carried out for 15 hours. After the reaction, the ester compound (A-1) (acid value: 0.43, hydroxyl value: 86) having a number average molecular weight of 400 and a weight average molecular weight of 500 was obtained by reducing the pressure at about 4000 Pa for 2 hours, .

[Example 2] Production of ester compound (A-2)

A three-liter four-necked flask equipped with a thermometer, a stirrer, and a reflux condenser was charged with 940 g of PG and 1,600 g of DMT, and the temperature was raised. When the temperature in the flask reached 130 캜, tetraisopropyl titanate as an esterification catalyst was added in an amount of 60 ppm relative to the total amount of PG and DMT, and the reaction was carried out for 10 hours while methanol generated at 185 캜 was stirred while stirring in a nitrogen stream I did. After the reaction, the ester compound (A-2) having a number average molecular weight of 1,000 and a weight average molecular weight of 1,750 was obtained by reducing the pressure at about 4000 Pa for 2 hours and the pressure for about 1 hour at about 133 Pa when the inner temperature of the flask reached 190 캜 : 0.18, hydroxyl value: 61).

[Example 3] Production of ester compound (A-3)

1,500 g of the ester compound (A-2) obtained in Example 2 was charged into a four liter flask having an internal volume of 2 liters and the temperature was raised. (A-3) (acid value: 0.30, hydroxyl value: 25) having a number-average molecular weight of 2,200 and a weight-average molecular weight of 5,000 was obtained by reducing the pressure in the flask to 190 ° C at about 133 Pa for 1.5 hours.

[Example 4] Production of ester compound (A-4)

A 1 liter four-necked flask equipped with a thermometer, a stirrer and a reflux condenser was charged with 315 g of PG and 300 g of dimethyl 2,6-naphthalenedicarboxylate (hereinafter referred to as "NDCM") and heated. When the temperature in the flask reached 130 ° C, tetraisopropyl titanate was added as an esterification catalyst in an amount of 60 ppm relative to the total amount of PG and NDCM, and the reaction was carried out for 15 hours while methanol generated at 185 ° C was stirred while stirring in a nitrogen stream I did. After the reaction, the ester compound (A-4) (acid value: 0.34, hydroxyl value: 65) having a number average molecular weight of 400 and a weight average molecular weight of 455 was obtained by reducing the pressure at about 18,000 Pa for 1 hour, ≪ / RTI >

[Example 5] Production of ester compound (A-5)

A three-liter four-necked flask equipped with a thermometer, a stirrer and a reflux condenser was charged with 201 g of 2-methyl-1,3-propanediol (hereinafter referred to as "2-MPD" , &Quot; 1,4-BD ") and 800 g of DMT were charged, and the temperature was raised. When the temperature in the flask reached 130 占 폚, 60 ppm of tetraisopropyl titanate as an esterification catalyst relative to the total amount of 2-MPD, 1,4-BG and DMT was added, and while stirring under a nitrogen stream, The reaction was carried out for 15 hours. After the reaction, the ester compound (A-5) (acid value: 0.62, hydroxyl value: 20) having a number average molecular weight of 1,600 and a weight average molecular weight of 3,600 was obtained by reducing the pressure at about 133 Pa .

[Example 6] Production of ester compound (A-6)

2,254 g of PG and 3,500 g of terephthalic acid (hereinafter referred to as " TPA ") were charged into an internal 5-liter pressurizable reactor equipped with a thermometer, a stirrer and a reflux condenser. When the temperature in the reactor reached 120 占 폚, tetraisopropyl titanate serving as an esterification catalyst was added in an amount of 60 ppm relative to the total amount of PG and TPA. While nitrogen was passed through the reactor, the water produced at a pressure of 3.5 MPa was distilled off Lt; / RTI > Thereafter, the reaction was carried out at normal pressure for 3 hours while gradually removing the pressure. After the reaction, the ester compound (A-6) (acid value: 0.75, hydroxyl value: 70) having a number average molecular weight of 740 and a weight average molecular weight of 1,250 was obtained by reducing the pressure at about 133 Pa .

[Example 7] Production of ester compound (A-7)

223 g of ethylene glycol (hereinafter referred to as "EG"), 274 g of PG, and 1,048 g of DMT were charged in a three liter four-necked flask equipped with a thermometer, a stirrer, a rectification column and a reflux condenser. When the temperature in the flask reached 80 占 폚, tetraisopropyl titanate serving as an esterification catalyst was added in an amount of 60 ppm based on the total amount of EG, PG and DMT and the temperature was raised to 190 占 폚 at a heating rate of 10 占 폚 / . The reaction was carried out for 7 hours while distilling the produced methanol. After the reaction, the ester compound (A-1) having an average molecular weight of 730 and a weight average molecular weight of 1,220 (acid value: 0.21, hydroxyl value: 145, Weight loss value: 0.15 mass%). As a result of NMR spectrum measurement, the molar composition ratio (a1-1) / (a1-2) of ethylene glycol (a1-1) and 1,2-propanediol (a1-2) was 51/49 (mol%).

[Example 8] Production of ester compound (A-8)

213 g of EG, 261 g of PG, and 1,000 g of DMT were charged into a three liter four-necked flask equipped with a stirrer, a thermometer, a stirrer, a reflux condenser and a reflux condenser. When the temperature in the flask reached 80 占 폚, tetraisopropyl titanate serving as an esterification catalyst was added in an amount of 60 ppm based on the total amount of EG, PG and DMT and the temperature was raised to 190 占 폚 at a heating rate of 10 占 폚 / . The reaction was carried out for 9 hours while distilling the produced methanol. After the reaction, the ester compound (A-8) having an average molecular weight of 1,530 and a weight average molecular weight of 3,200 (acid value: 0.34, hydroxyl value: 90, Weight loss value: 0.08 mass%). NMR spectrum measurement revealed that the molar composition ratio (a1-1) / (a1-2) of ethylene glycol (a1-1) and 1,2-propanediol (a1-2) was 53/47 (mol%).

[Example 9] Production of ester compound (A-9)

233 g of EG, 285 g of PG and 1,165 g of DMT were charged into a three-liter four-necked flask equipped with a thermometer, a stirrer, a rectifying column and a reflux condenser. When the temperature in the flask reached 80 占 폚, tetraisopropyl titanate serving as an esterification catalyst was added in an amount of 60 ppm relative to the total amount of EG, PG and DMT, and the temperature was elevated to 190 占 폚 at a rate of temperature increase of 10 占 폚 / did. The reaction was carried out for 15 hours while distilling the generated methanol. (A-9) (acid value: 0.24, hydroxyl value: 59, average molecular weight: 2,650, weight average molecular weight: 5,580) was obtained by reducing the pressure at about 18,000 Pa for 2 hours when the internal temperature of the flask became 190 deg. Weight loss value: 0.03 mass%). NMR spectrum measurement revealed that the molar composition ratio (a1-1) / (a1-2) of the ethylene glycol (a1-1) and the 1,2-propanediol (a1-2) was 52/48 (mol%).

[Example 10] Production of ester compound (A-10)

140 g of EG, 57 g of PG and 874 g of DMT were charged into a three liter four-necked flask equipped with a stirrer, a thermometer, a stirrer, a reflux condenser and a reflux condenser. When the temperature in the flask reached 80 占 폚, tetraisopropyl titanate serving as an esterification catalyst was added in an amount of 60 ppm based on the total amount of EG, PG and DMT and the temperature was raised to 190 占 폚 at a heating rate of 10 占 폚 / . The reaction was carried out for 10 hours while distilling the produced methanol. After the reaction, the ester compound (A-10) having an average molecular weight of 730 and a weight average molecular weight of 1,220 (acid value: 0.43, hydroxyl value: 121, Weight loss value: 0.22 mass%). NMR spectrum measurement revealed that the molar composition ratio (a1-1) / (a1-2) of ethylene glycol (a1-1) and 1,2-propanediol (a1-2) was 78/22 (mol%).

[Example 11] Production of ester compound (A-11)

248 g of EG, 912 g of PG and 1,243 g of DMT were charged into a three liter four-necked flask equipped with a thermometer, a stirrer, a rectification column, and a reflux condenser. When the temperature in the flask reached 80 占 폚, tetraisopropyl titanate as an esterification catalyst was added in an amount of 60 ppm relative to the total amount of EG, PG and DMT, and the temperature was elevated to 190 占 폚 at a temperature raising rate of 10 占 폚 / hour while stirring in a nitrogen stream . The reaction was carried out for 10 hours while distilling the produced methanol. After the reaction, the ester compound (A-11) having an average molecular weight of 1,500 and a weight average molecular weight of 3,150 (acid value: 0.43, hydroxyl value: 121, Weight loss value: 0.22 mass%). NMR spectrum measurement revealed that the molar composition ratio (a1-1) / (a1-2) of ethylene glycol (a1-1) and 1,2-propanediol (a1-2) was 21/79 (mol%).

[Example 12] Production of ester compound (A-12)

158 g of EG, 194 g of PG and 498 g of TPA were charged into an autoclave having an internal volume of 1 liter equipped with a thermometer, a stirrer, a rectification column, a reflux condenser and a pressure regulating valve. When the temperature in the flask reached 80 占 폚, tetraisopropyl titanate serving as an esterification catalyst was added in an amount of 60 ppm based on the total amount of EG, PG and TPA to a pressure of 3.5 MPa. While stirring under a stream of nitrogen gas, Lt; 0 > C / hour. The reaction was carried out for 3 hours while distilling the generated water. (A-12) (acid value: 0.20, number-average molecular weight: 1,200) having a number average molecular weight of 1,200 and a weight average molecular weight of 2,400 was obtained by reducing the pressure to about 18,000 Pa for 2 hours when the inner temperature of the flask reached 190 占 폚. Hydroxyl value: 83, heat loss value: 0.18 mass%). NMR spectrum measurement revealed that the molar composition ratio (a1-1) / (a1-2) of the ethylene glycol (a1-1) and the 1,2-propanediol (a1-2) was 42/58 (mol%).

[Example 13] Production of ester compound (A-13)

155 g of EG, 190 g of PG, and 610 g of NDCM were charged into a 2-liter four-necked flask equipped with a stirrer, a thermometer, a stirrer and a reflux condenser. When the temperature in the flask reached 80 占 폚, tetraisopropyl titanate serving as an esterification catalyst was added in an amount of 60 ppm relative to the total amount of EG, PG and NDCM, and the temperature was elevated to 190 占 폚 at a temperature raising rate of 10 占 폚 / hour while stirring in a nitrogen stream . The reaction was carried out for 10 hours while distilling the produced methanol. After the reaction, the ester compound (A-13) (acid value: 0.43, hydroxyl value: 118, number average molecular weight: Weight loss value: 0.34 mass%). NMR spectrum measurement revealed that the molar composition ratio (a1-1) / (a1-2) of ethylene glycol (a1-1) and 1,2-propanediol (a1-2) was 50/50 (mol%).

[Comparative Example 1] Production of ester compound (A-14)

700 g of the ester compound (A-3) obtained in Example 3 was charged into a one liter four liter flask, and the temperature was raised. (A-14) (acid value: 0.45, hydroxyl value: 15) having a number average molecular weight of 3,300 and a weight average molecular weight of 9,600 was obtained by reducing the pressure at about 133 Pa for 2 hours when the temperature in the flask reached 190 占 폚.

[Comparative Example 2] Production of ester compound (A-15)

186 g of EG, 228 g of PG and 970 g of DMT were charged into a 2 liter four-necked flask equipped with a thermometer, a stirrer, a rectification column, and a reflux condenser. When the temperature in the flask reached 80 占 폚, tetraisopropyl titanate serving as an esterification catalyst was added in an amount of 60 ppm based on the total amount of EG, PG and DMT and the temperature was raised to 190 占 폚 at a heating rate of 10 占 폚 / . The reaction was carried out for 10 hours while distilling the produced methanol. After the reaction, the ester compound (A-15) (acid value: 0.65, hydroxyl value: 15, number-average molecular weight: 5,000) having a number average molecular weight of 3,150 and a weight average molecular weight of 8,200 was obtained by reducing the pressure at about 18,000 Pa for 3 hours, Weight loss value: 0.08 mass%). As a result of NMR spectrum measurement, the molar composition ratio (a1-1) / (a1-2) of ethylene glycol (a1-1) and 1,2-propanediol (a1-2) was 51/49 (mol%).

[Comparative Example 3] Production of ester compound (A-16)

A 4-liter four-necked flask equipped with a thermometer, a stirrer and a reflux condenser was charged with 468 g of PG, 524 g of DMT and 733 g of benzoic acid (hereinafter referred to as "BzA") and heated. Tetraisopropyl titanate as an esterification catalyst was added in an amount of 60 ppm relative to the total amount of PG, DMT and BzA at a temperature in the flask reached 130 DEG C, and the mixture was stirred at 170 DEG C for 1 hour at a rate of 10 DEG C The resulting water and methanol were heated to 220 캜 while being distilled. (A-16) (acid value: 0.32, hydroxyl value: 7) having a number average molecular weight of 450 and a weight average molecular weight of 800 was obtained by reducing the pressure at about 133 Pa for 4 hours when the inside temperature of the flask became 190 deg. ).

[Comparative Example 4] Production of ester compound (A-17)

670 g of EG and 1461 g of adipic acid (hereinafter referred to as " AA ") were charged into a three liter four-necked flask equipped with a thermometer, a stirrer and a reflux condenser. When the temperature in the flask reached 70 占 폚, tetraisopropyl titanate serving as an esterification catalyst was added in an amount of 60 ppm relative to the total amount of EG and AA, and the mixture was stirred at 150 占 폚 for 1 hour at a rate of 15 占 폚 The temperature was raised to 220 deg. After the reaction for 7 hours, an ester compound (A-17) (acid value: 0.55, hydroxyl value: 113) having a number average molecular weight of 1,000 and a weight average molecular weight of 1,850 was obtained by reducing pressure at about 1330 Pa for 3 hours when the inside temperature of the flask reached 195 deg. ).

[Comparative Example 5] Production of ester compound (A-18)

670 g of 1,3-butanediol (hereinafter referred to as "1,3-BD") and phthalic anhydride (hereinafter referred to as "PA") were placed in a three liter four liter flask equipped with a thermometer, a stirrer and a reflux condenser ) Was charged and the temperature was raised. When the temperature in the flask reached 70 占 폚, tetraisopropyl titanate serving as an esterification catalyst was added in an amount of 60 ppm based on the total amount of 1,3-BG and PA, and the mixture was stirred at 150 占 폚 for 1 hour, The temperature was raised to 220 캜 while water generated at a speed was removed. After the reaction for 7 hours, the ester compound (A-18) having an average molecular weight of 710 and a weight average molecular weight of 1,350 (acid value: 0.55, hydroxyl value: 123 ).

The number average molecular weight (Mn), the weight average molecular weight (Mw), the acid value, the hydroxyl value and the weight loss of the ester compounds (A-1) to (A-18) obtained in Examples 1 to 13 and Comparative Examples 1 to 5 Was measured by the following method. The hydroxyl value was measured in accordance with JIS K0070-1992.

[Method for measuring number average molecular weight (Mn) and weight average molecular weight (Mw) of ester compound]

(Mn) and a weight average molecular weight (Mw) of the ester compound in terms of standard polystyrene were measured using a gel permeation chromatography (GPC) measuring device (" HLC-8330 " Mw) was measured.

Column: " TSK gel SuperHZM-M "

"TSK gel SuperHZ-2000" × 2

Guard column: "TSK SuperH-H"

Developing solvent: tetrahydrofuran

Flow rate: 0.35 mL / min

[Method for Measuring the Molar Composition Ratio (a-1) / (a-2) of Ethylene Glycol (a-1) and 1,2-Propanediol (a-

¹ H-NMR device (Nippon den cigar unit to the manufactured, JNM-LA300) using, by analyzing the chloroform -d (CDCl ₃₎ solution of the ester compound, ethylene glycol (a-1 in forming the ester compound (A-1) / (a-2) (unit: mol%) of the 1,2-propanediol (a-

[Measurement conditions of heating loss]

About 50 g of the ester compound was placed in a gear aging tester (type "SB-P" manufactured by YASEI SEISAKUSHO CO., LTD., Inner volume 45 × 45 × 50 cm ³ ) and heated at 140 ° C. for 60 minutes in a nitrogen atmosphere The mass was measured, and the heating loss value was measured by the mass reduction rate before and after heating. When used in a polarizer protective film, when the heating weight loss value of the ester compound is about 0.5% by mass or less, the volatility is remarkably excellent.

The properties of the ester compounds (A-1) to (A-18) obtained in Examples 1 to 13 and Comparative Examples 1 to 5 are shown in Tables 1 to 3.

[Production of Evaluation Film Comprising Cellulose Ester Resin Composition]

1 g of the ester compounds (A-1) to (A-18) obtained in Examples 1 to 13 and Comparative Examples 1 to 5 and 10 g of cellulose triacetate (degree of acetatization of 61 mass%, degree of polymerization 265) were dissolved in 81 g of methylene chloride, And the mixture was homogeneously stirred to prepare a doping solution. These doping solutions were each plied on a glass plate to a thickness of about 1 mm, dried at room temperature for 16 hours, dried at 50 DEG C for 30 minutes, and further dried at 120 DEG C for 30 minutes, Films (F-1) to (F-18) were obtained.

Further, as Comparative Example 6, 1 g of triphenyl phosphate (hereinafter referred to as " TPP ") was used in place of the ester compound, and an evaluation film (F-19) having a film thickness of about 80 μm was obtained. In addition, as Comparative Example 7, an evaluation film (F-20) having a film thickness of about 80 占 퐉 was obtained by the same operation using only cellulose triacetate.

[Evaluation method of bleeding resistance of film]

The obtained film was cut into a size of 30 mm x 40 mm and left standing for 120 hours at a constant temperature and humidity of 85 DEG C and a relative humidity of 90%. Thereafter, the surface of the film was observed with naked eyes and the presence or absence of bleeding such as an ester compound was evaluated according to the following criteria.

A: No bleed water was observed on the surface of the film.

B: Bleed water was observed on the surface of the film.

The film having no observed bleed water is excellent in durability. In particular, when the film is used as a polarizer protective film, it can be said that the polarizer protective film is excellent in wet heat durability.

In order to determine the compatibility of the cellulose ester resin with the esterified product, the transparency of the film was measured with a turbidimeter (manufactured by Nihon Denshoku Kogyo K.K., ND-1001DP "), the haze value of the film was measured in accordance with JIS K7105. When used for a polarizer protective film, the haze value is preferably 1% or less in practical use, and more preferably 0.5% or less in practical use.

[Method of measuring the retardation value (Rth value) in the thickness direction of the film]

Retardation value (Rth value) in the thickness direction of the film was measured using an automatic birefringence meter ("KOBRA-WR" manufactured by Oji Paper Co., Ltd.). The measurement conditions were set at a temperature of 23 캜 and a relative humidity of 20% for 12 hours or more, and then the measurement was carried out under the same environment. The Rth value of the film varies depending on the use, but if it is about 130 nm or more, it can be used as a polarizer protective film having an optical compensation function.

[Measurement method of moisture permeability of film]

The moisture permeability of the film was measured according to the method described in JIS Z0208 and converted to a thickness of 80 mu m. The measurement conditions were a temperature of 25 ° C and a relative humidity of 90%. Furthermore, since the moisture permeability of the cellulose triacetate alone film used in this example is about 800 g / m ² 24 h (see Comparative Example 9 in Table 2), the moisture content of the film containing the additive for cellulose ester resin of the present invention is Value, it can be said that the polarizer protective film has excellent moisture permeability.

Tables 1 and 2 show the evaluation results of the films (F-1) to (F-13) using the additives for cellulose ester resin of the present invention obtained in Examples 1 to 13. (F-14) to (F-18) using the ester compound obtained in Comparative Examples 1 to 5, a film (F-19; Comparative Example 6) using TPP instead of an ester compound, and a film F-20; Comparative Example 7).

[Table 1]

[Table 2]

[Table 3]

From the results shown in Tables 1 and 2, it was found that the ester compound as the additive for the cellulose ester resin of the present invention had a very low heating loss value of 0.03 to 0.45 mass%. Further, it was found that the films (F-1) to (F-13) using the additive for cellulose ester resin of the present invention were excellent in bleeding resistance and moisture permeability and maintained high transparency even when stored under a high temperature and high humidity environment. In addition, the Rth value of the film was very high, i.e., 115 to 291 nm, which was extremely useful as an optical film.

From the results shown in Table 3, the following can be found.

Comparative Examples 1 and 2 are examples in which an ester compound exceeding 3,000, which is the upper limit of the number average molecular weight of the ester compound as the additive for cellulose ester resin of the present invention, is used. The films (F-14) and (F-15) in which the ester compound was blended had problems that the cellulose ester resin and the ester compound were very miscible with each other and therefore the film was cloudy and the bleeding resistance was poor. The haze value of the film (F-14) and the Rth value of the films (F-14) and (F-15) were not measurable because the film was cloudy. Also, since these values were impossible to measure, the moisture permeability was not measured.

Comparative Example 3 is an example in which a terminal hydroxyl group is sealed using benzoic acid as an aromatic monocarboxylic acid in addition to an aromatic dicarboxylic acid compound as a raw material for an ester compound as an additive for cellulose ester resin of the present invention. The film (F-16) in which the ester compound was blended had good bleed resistance and moisture permeability, but no improvement in the Rth value was observed.

Comparative Example 4 is an example of an ester compound using an aliphatic dicarboxylic acid instead of an aromatic dicarboxylic acid compound used in the present invention as a raw material for an ester compound as an additive for cellulose ester resin of the present invention. The film (F-17) in which the ester compound was blended had a good bleed resistance and an excellent water vapor permeability, but no improvement in the Rth value was recognized.

Comparative Example 5 is an example of an ester compound using an aromatic dicarboxylic acid compound other than the aromatic dicarboxylic acid compound defined in the present invention as a raw material for an ester compound as an additive for cellulose ester resin of the present invention. The film (F-18) containing this ester compound had good bleed resistance and moisture permeability, but no improvement in Rth value was observed.

Comparative Example 6 is an example using TPP instead of the ester compound as an additive for cellulose ester resin of the present invention. The film (F-19) in which the TPP was blended had a problem that the TPP bleeds to a large extent on the film surface even at room temperature. Further, improvement of the Rth value of the film was not recognized.

Comparative Example 7 is an evaluation example of a film (F-20) in which no ester compound or the like is blended. The film having only this cellulose ester number is excellent in transparency, but the Rth value is very low.

Claims (7)

At least one aromatic dicarboxylic acid compound selected from the group consisting of terephthalic acid, terephthalic acid dialkyl ester, naphthalene dicarboxylic acid, naphthalene dicarboxylic acid dialkyl ester, biphenyl dicarboxylic acid and biphenyl dicarboxylic acid dialkyl ester wherein the diol (a1) is ethylene glycol (a1-1) and 1,2-propanediol (a1-2), and the ethylene glycol (a1-2) (A) obtained by the combined use of the 1,2-propanediol (a1-1) and the 1,2-propanediol (a1-2) in a molar ratio (a1-1) / (a1-2) of 85/15 to 10/90, And an additive for cellulose ester resin. delete delete delete A cellulose ester resin composition characterized by containing 3 to 50 parts by mass of the ester compound (A) according to claim 1 per 100 parts by mass of the cellulose ester resin (B). A film comprising the cellulose ester resin composition according to claim 5. An optical film comprising the cellulose ester resin composition according to claim 5.