KR102483672B1 - Antiplasticizer of resin for optical film, cellulose ester resin composition, optical film and liquid crystal display device - Google Patents

Abstract

In particular, an ester resin that is excellent in strength when processed into a film form, moisture permeability resistance, and balance of optical properties and can be suitably used as a semi-plasticizer for optical resins, a resin composition containing the same, and the resin composition are used. An optical film thus obtained and a liquid crystal display device using the same are provided. Specifically, B-(GA) _n -GB [wherein B is a monocarboxylic acid residue, G is an alkylene glycol residue, oxyalkylene glycol residue or aryl glycol residue, A is a dicarboxylic acid residue, and the sum of A 20 mol% or more of the number of moles is an isophthalic acid residue, n is the number of repetitions, G and A may be the same or different for each repetition, and a plurality of B and G may be the same or different] An ester resin, a cellulose ester resin composition containing the same, an optical film and a liquid crystal display device containing the composition.

Description

Semiplasticizer for resins for optical materials, cellulose ester resin compositions, optical films and liquid crystal displays

The present invention relates to an ester resin suitable as a semiplasticizer for resin for optical materials, a cellulose ester resin containing the same, an optical film obtained using the resin composition, and a liquid crystal display device using the same.

In recent years, liquid crystal displays are being thinned, and polarizing plate protective films are also being thinned from conventional 80 μm to 60 μm to 25 μm. For the protective film of the polarizing plate, many conventional triacetyl cellulose resins (hereinafter referred to as TAC) have been used from the viewpoint of easy attachment to the polarizer.

However, since TAC is hard and brittle, when it is used as a film, it has insufficient strength and causes problems such as easy breakage. In addition, since TAC has high moisture permeability and easily undergoes dimensional change due to moisture absorption, it is necessary to suppress moisture absorption with an additive, and various additives have been provided (see Patent Document 1, for example).

Usually, when an additive is added to suppress moisture permeation, plasticization of the resin occurs at the same time, so it is difficult to achieve both the strength and moisture permeability resistance of the obtained film. Therefore, development of an additive (= semi-plasticizer) capable of suppressing moisture permeation and improving the modulus of elasticity has been demanded.

Japanese Unexamined Patent Publication No. 2013-151699

In view of the above circumstances, the problem to be solved by the present invention is an excellent balance of strength, moisture permeability resistance, and optical properties when processed into a film, particularly, and can be suitably used as a semi-plasticizer for optical resins. It is providing an ester resin, a resin composition containing this, an optical film obtained using the resin composition, and a liquid crystal display device using the same.

As a result of earnest studies, the inventors of the present invention have found that the above-mentioned problems can be solved by adjusting the proportion of raw materials in ester resins, particularly dicarboxylic acids, and have completed the present invention.

That is, the present invention, the following general formula (1)

B-(GA) _n -GB (1)

[In formula (1), B is a monocarboxylic acid residue, G is an alkylene glycol residue, oxyalkylene glycol residue or aryl glycol residue, A is a dicarboxylic acid residue, and 20 mol% or more of the total moles of A are iso A phthalic acid residue, n is the number of repetitions, G and A may be the same or different for each repetition, and a plurality of B and G may be the same or different]

It is to provide an ester resin characterized by being represented by, a resin composition containing the same, an optical film obtained using the composition, and a liquid crystal display device using the optical film.

ADVANTAGE OF THE INVENTION According to this invention, the balance of intensity|strength at the time of processing into a film form, resistance to moisture permeability, and optical characteristics is excellent, and it can provide the ester resin which can be used suitably as a semiplasticizer for resin for optics. In addition, by using the specific ester resin, in an optical film containing a cellulose ester resin in particular, it is possible to achieve both improvement of the elastic modulus, suppression of moisture permeation, and maintenance of optical properties, and as an optical film used for a liquid crystal display device. can be used appropriately.

The ester resin of the present invention has the following general formula (1)

B-(GA) _n -GB (1)

[In formula (1), B is a monocarboxylic acid residue, G is an alkylene glycol residue, oxyalkylene glycol residue or aryl glycol residue, A is a dicarboxylic acid residue, and 20 mol% or more of the total moles of A are iso A phthalic acid residue, n is the number of repetitions, G and A may be the same or different for each repetition, and a plurality of B and G may be the same or different]

It is characterized by being displayed as.

B in the said general formula (1) is a monocarboxylic acid residue, Specifically, an aryl monocarboxylic acid residue or an aliphatic monocarboxylic acid residue is mentioned. Here, "carboxylic acid residue" shows groups other than -OH in a carboxy group. As the aryl monocarboxylic acid residue, an aryl monocarboxylic acid residue having 6 to 12 carbon atoms is advantageous in terms of ease of availability of raw materials, ease of esterification reaction, and resistance to moisture permeability, elastic modulus, and optical properties when mixed with a cellulose ester resin described later. Preferred from the viewpoint of easy balance, for example, benzoic acid, dimethylbenzoic acid, trimethylbenzoic acid, tetramethylbenzoic acid, ethylbenzoic acid, propylbenzoic acid, butylbenzoic acid, cuminic acid, paratertiary butylbenzoic acid, orthotoluic acid, metatoluic acid , p-toluic acid, ethoxybenzoic acid, propoxybenzoic acid, anisic acid, naphthoic acid, etc. may be mentioned, and may be used alone or in combination of two or more. In particular, it is preferably a residue of benzoic acid, p-toluic acid, or dimethylbenzoic acid, and more preferably a residue of benzoic acid, from the viewpoint of more easily expressing the effect of the present invention. In addition, the number of carbon atoms here shall not contain the carbon atom in a carboxy group. Furthermore, residues such as nicotinic acid and furoic acid, which may have a substituent and have aromaticity, may be used.

As the aliphatic monocarboxylic acid residue, an aliphatic monocarboxylic acid residue having 1 to 8 carbon atoms is easy to obtain raw materials and easy to esterify, and when mixed with a cellulose ester resin described later, moisture permeability resistance, elastic modulus, and optical characteristics balance It is preferable from the viewpoint of easy matching, and examples thereof include residues such as acetic acid, propionic acid, butanoic acid, hexanoic acid, octanoic acid, and octylic acid, which may be used alone or in combination of two or more, particularly acetic acid. it is desirable In addition, the number of carbon atoms here shall not contain the carbon atom in a carboxy group.

G in the said general formula (1) is an alkylene glycol residue, an oxyalkylene glycol residue, or an aryl glycol residue. A glycol residue represents a group after removing a hydrogen atom from a hydroxyl group.

As the alkylene glycol residue, an alkylene glycol residue having 2 to 12 carbon atoms is preferable from the viewpoint of more easily expressing the effect of the present invention, and examples thereof include ethylene glycol, 1,2-propylene glycol, 1 ,3-propanediol, 1,2-butanediol, 1,3-butanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1, 3-propanediol (neopentyl glycol), 2,2-diethyl-1,3-propanediol (3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3-propanediol ( 3,3-dimethylolheptane), 3-methyl-1,5-pentanediol, 1,6-hexanediol, 2,2,4-trimethyl 1,3-pentanediol, 2-ethyl-1,3-hexane residues such as diol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, and 1,12-dodecanediol; You can do it. Among these, from the viewpoint of being an ester resin with more excellent compatibility when mixed with a cellulose ester resin described later, those having 3 or less carbon atoms without branching between OH groups are preferable, and among these, ethylene glycol, 1,2- It is preferably a residue of propylene glycol, 1,3-propanediol, 1,2-butanediol, or 2-methyl-1,3-propanediol, and more preferably a residue of ethylene glycol or 1,2-propylene glycol.

As the oxyalkylene glycol residue, an oxyalkylene glycol residue having 4 to 12 carbon atoms is preferable from the viewpoint of more easily expressing the effect of the present invention, and examples thereof include diethylene glycol, triethylene glycol, tetra Residues, such as ethylene glycol, dipropylene glycol, and tripropylene glycol, are mentioned, and may be individual, or may use 2 or more types together.

As the aryl glycol residue, an aryl glycol residue having 6 to 18 carbon atoms is preferable from the viewpoint of more easily expressing the effects of the present invention, and examples thereof include hydroquinone, resorcinol, bisphenol A, and alkylene oxides of bisphenol A. and residues such as adducts, bisphenol F, alkylene oxide adducts of bisphenol F, biphenol, and alkylene oxide adducts of biphenol.

Further, A in the above general formula (1) is a dicarboxylic acid residue, specifically an alkylenedicarboxylic acid residue (A1) or an aryldicarboxylic acid residue (A2), and the isophthalic acid residue in the total number of moles of A It is essential that the mole number is 20 mol% or more. Here, the dicarboxylic acid residue refers to a group excluding -OH in the carboxy group.

In the ester resin represented by the general formula (1), by using a large amount of isophthalic acid as the dicarboxylic acid of the raw material, when mixed with the optical resin described later, the optical resin, particularly the cellulose ester resin, is calcined When processed into a film form without making it into a film, the elastic modulus is improved and moisture permeability resistance is imparted, and the optical properties originally possessed by the resin for optics are not impaired. .

From the viewpoint of exhibiting the above effects, it is essential that the number of moles of isophthalic acid residues in the dicarboxylic acid residues is 20 mol% or more, and in particular, from the viewpoint of exhibiting the effect more, the content of isophthalic acid residues is 25 to 100 mol% It is preferable that the range of

As the alkylene dicarboxylic acid residue (A1), which may coexist with an isophthalic acid residue, an alkylene dicarboxylic acid residue having 2 to 12 carbon atoms is preferable from the viewpoint of more easily expressing the effect of the present invention. For example, , residues such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, fumaric acid, 1,2-dicarboxycyclohexane, and 1,2-dicarboxycyclohexene, may be used alone, You may use 2 or more types together. Among these, since an optical film more excellent in moisture permeability resistance is obtained, residues of succinic acid, adipic acid, and 1,2-dicarboxycyclohexane are preferred, and residues of adipic acid are most preferred.

Examples of the aryldicarboxylic acid residue (A2), which may coexist with the isophthalic acid residue, include phthalic acid, terephthalic acid, 1,4-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, and 2,6-naphthalenedicarboxylic acid. , residues such as 2,7-naphthalenedicarboxylic acid and 1,8-naphthalenedicarboxylic acid may be used alone or in combination of two or more. Among these, since an optical film with higher strength is obtained, a residue of phthalic acid or terephthalic acid is preferred, and a residue of phthalic acid is most preferred.

In the present invention, the ester resin represented by the general formula (1) may be a mixture of compounds in which B, G, and A are the same and differ only in n, that is, the number of repetitions, or B in the general formula (1) , G, A and n may be a mixture of compounds each different from each other. In the present invention, in the optical film obtained by mixing with a resin for an optical material described later, particularly a cellulose ester resin, in order to have both moisture permeability resistance and improvement in elastic modulus, in the GPC measurement of the ester resin represented by the general formula (1) In the area ratio, the ratio of the area % of the n = 0 component and the area % of the n = 0 component in which the n = 0 component in the above formula (1) is 10 to 50% (n ≥ 3) / (n = 3 or more) 0) is more preferably 3 or less.

By setting such a n = 0 component, the so-called diester compound, to a specific content rate, the resin for optical materials, particularly the cellulose ester resin, is suitably disposed between the gaps, and as a result, the effect of suppressing moisture permeability is expressed, while n Compatibility with resin for optical materials is ensured and transparency usable as an optical film can be maintained more effectively by reducing the content rate of these 3 or more components comparatively.

These effects are further expressed, and from the viewpoint of suppression of contamination of production lines or the like due to volatilization and easy maintenance of the transparency of the optical film, the above general formula (1) in the area ratio in GPC measurement ), the n = 0 component in ) is preferably 20 to 50%, and the ratio of the area % of the n = 0 component to the area % of the n = 0 component (n ≥ 3) / (n = 0) is 0.2 to 0.2 It is preferably in the range of 1.5.

In addition, the GPC measurement in this invention was performed under the following conditions.

[GPC measurement conditions]

Measuring device: Tosoh Corporation's high-speed GPC device "HLC-8320GPC"

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 + manufactured by Tosoh Corporation "TSK gel SuperHZ-2000" + "TSK gel SuperHZ-2000" made 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 rate: 0.35mL/min

Measurement sample: A sample obtained by dissolving 7.5 mg of the sample in 10 ml of tetrahydrofuran and filtering the obtained solution through a microfilter was used as 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 "HLC-8320GPC" described above.

(monodisperse polystyrene)

"A-300" made by Toso Co., Ltd.

"A-500" made by Tosoh Corporation

"A-1000" manufactured by Toso Co., Ltd.

"A-2500" by Tosoh Corporation

"A-5000" manufactured by Toso Co., Ltd.

"F-1" made by Toso Co., Ltd.

"F-2" made by Toso Co., Ltd.

"F-4" made by Toso Co., Ltd.

"F-10" made by Toso Co., Ltd.

"F-20" made by Toso Co., Ltd.

"F-40" made by Toso Co., Ltd.

"F-80" made by Toso Co., Ltd.

"F-128" made by Toso Co., Ltd.

"F-288" made by Toso Co., Ltd.

(GPC analysis conditions)

The area % of the n = 0 component and the component in which n is 3 or more in the ester resin of the present invention is computable as follows. GPC measurement of the ester resin was performed to determine the molecular weight in terms of polystyrene of each component corresponding to the detected peak, and the content ratio (area fraction) of each component corresponding to the detected peak was calculated from the ratio of the detected peak areas.

From the viewpoint of further expressing the effect of the present invention, in general formula (1), B is benzoic acid or acetic acid residue, G is ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 1,2 - Residues of butanediol and 2-methyl-1,3-propanediol, A1 which may be present in combination is preferably a residue of succinic acid, adipic acid or 1,2-dicarboxycyclohexane, and A2 is a residue of phthalic acid or terephthalic acid In particular, it is most preferable that B is a residue of benzoic acid, G is a residue of ethylene glycol or 1,2-propylene glycol, A1, which may be present together, is an adipic acid residue, and A2 is a phthalic acid residue.

Moreover, as for the ester resin of this invention, the weight average molecular weight is preferably in the range of 350 to 1200, and particularly preferably in the range of 350 to 800 from the viewpoint of achieving both compatibility and film properties. In addition, as an average value of the repetition number n in the said General formula (1), it is preferable that it is the range of 0.2-3 from a viewpoint of making compatibility and film physical property compatible similarly. In addition, this weight average molecular weight and the average value of n are also values measured by the said GPC measurement.

The acid value of the ester resin of the present invention is preferably 5 or less, more preferably 1 or less, from the viewpoint of better compatibility with the resin for optical materials. From the same viewpoint, the hydroxyl value of the ester resin is preferably 50 or less, and more preferably 20 or less.

The ester resin of the present invention is obtained, for example, by subjecting the above-mentioned raw materials to an esterification reaction in the presence of an esterification catalyst as needed, for example, within a temperature range of 180 to 250°C for 10 to 25 hours. can be manufactured Moreover, conditions, such as temperature and time of esterification reaction, are not specifically limited, You may set suitably. Regarding monocarboxylic acids and dicarboxylic acids, the acid itself may be used as a raw material, or an ester compound, an acid chloride thereof, an anhydride of dicarboxylic acid, or the like may be used as a raw material.

Examples of the esterification catalyst include titanium catalysts such as tetraisopropyl titanate and tetrabutyl titanate; tin catalysts such as dibutyltin oxide; Organic sulfonic acid type catalysts, such as p-toluenesulfonic acid, etc. are mentioned.

Although the usage-amount of the said esterification catalyst may be set suitably, it is preferable to normally use it in the range of 0.001-0.1 mass part with respect to 100 mass parts of whole amounts of raw materials.

The properties of the ester resins of the present invention vary depending on factors such as their weight average molecular weight and combination of raw materials, but are usually liquid, solid, paste or the like at room temperature.

As a more specific method for producing an ester resin, a method of reacting a compound having a hydroxyl group at the terminal obtained by using the above-described alkylene glycol, oxyalkylene glycol or aryl glycol, and a dicarboxylic acid and a monocarboxylic acid is exemplified. Here, the alkylene glycol, oxyalkylene glycol or aryl glycol, the dicarboxylic acid and the monocarboxylic acid may be collectively introduced into the reaction system and reacted, or the alkylene glycol, oxyalkylene glycol or aryl glycol and the dicarboxylic acid may be reacted. After obtaining a compound having a hydroxyl group at the terminal obtained using , a sequential reaction in which a monocarboxylic acid is further introduced into the reaction system may be used.

The ester resin obtained above may be used as it is as the ester resin of the present invention as long as the content of the isophthalic acid residue specified in the present invention is 20 mol% or more, or the composition for each repetition of n may be determined by the GPC measurement described above. After obtaining, the content of the n=0 component and the content of the high molecular weight component may be adjusted by, for example, a distillation method using a thin film distillation apparatus, a column adsorption method, a solvent separation extraction method, or the like. In particular, after distilling the content of the n = 0 component to 8% or less from the area ratio by GPC measurement with a thin film distillation apparatus, a separately prepared diester compound (II) is added as the n = 0 component, and GPC measurement is performed. In the area ratio in , the ratio of the area % of the n = 0 component in the general formula (1) is 10 to 50% and the area % of the component where n is 3 or more and the area % of the n = 0 component (n ≥ 3) / ( A method of making an ester resin that satisfies that n = 0) is 3 or less may be used. At this time, the raw material used for the ester resin and the raw material for the individually prepared diester compound may be the same or different. At this time, it is necessary to adjust so that 20 mol% or more of the total number of moles of A in the mixed ester resin is an isophthalic acid residue.

When employing the above manufacturing method, the diester compound (II) added later is preferably represented by the following general formula (2).

B2-G2-B2 (2)

(Wherein, B2 is an aryl monocarboxylic acid residue or an aliphatic monocarboxylic acid residue, G2 is an alkylene glycol residue, an oxyalkylene glycol residue or an aryl glycol residue, and a plurality of B2 may be the same or different.)

B2 in the said general formula (2) is an aryl monocarboxylic acid residue or an aliphatic monocarboxylic acid residue. Here, "carboxylic acid residue" shows groups other than -OH in a carboxy group. As the aryl monocarboxylic acid residue, an aryl monocarboxylic acid residue having 6 to 12 carbon atoms is used to balance the ease of availability of raw materials and the ease of esterification reaction, and the improvement of moisture permeability resistance and elastic modulus when mixed with a cellulose ester resin described later It is preferable from the viewpoint of easy matching, for example, benzoic acid, dimethylbenzoic acid, trimethylbenzoic acid, tetramethylbenzoic acid, ethylbenzoic acid, propylbenzoic acid, butylbenzoic acid, cuminic acid, paratertiary butylbenzoic acid, orthotoluic acid, metatoluic acid, Paratoluic acid, ethoxybenzoic acid, propoxybenzoic acid, anisic acid, naphthoic acid, etc. are mentioned, and may be used alone or in combination of two or more. In particular, it is preferably a residue of benzoic acid, p-toluic acid, or dimethylbenzoic acid, and more preferably a residue of benzoic acid, from the viewpoint of more easily expressing the effect of the present invention. In addition, the number of carbon atoms here shall not contain the carbon atom in a carboxy group. Furthermore, residues such as nicotinic acid and furoic acid, which may have a substituent and have aromaticity, may be used.

As the aliphatic monocarboxylic acid residue, an aliphatic monocarboxylic acid residue having 1 to 8 carbon atoms provides a balance between easy availability of raw materials and easy esterification reaction, and improvement in moisture permeability resistance and elastic modulus when mixed with a cellulose ester resin described later. It is preferable from the viewpoint of easy matching, and examples thereof include residues such as acetic acid, propionic acid, butanoic acid, hexanoic acid, octanoic acid, and octylic acid, which may be used singly or in combination of two or more, particularly residues of acetic acid. It is desirable to be In addition, the number of carbon atoms here shall not contain the carbon atom in a carboxy group.

G in the said general formula (1) is an alkylene glycol residue, an oxyalkylene glycol residue, or an aryl glycol residue. A glycol residue represents a group after removing a hydrogen atom from a hydroxyl group.

As the alkylene glycol residue, an alkylene glycol residue having 2 to 12 carbon atoms is preferable from the viewpoint of more easily expressing the effect of the present invention, and examples thereof include ethylene glycol, 1,2-propylene glycol, 1 ,3-propanediol, 1,2-butanediol, 1,3-butanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1, 3-propanediol (neopentyl glycol), 2,2-diethyl-1,3-propanediol (3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3-propanediol ( 3,3-dimethylolheptane), 3-methyl-1,5-pentanediol, 1,6-hexanediol, 2,2,4-trimethyl 1,3-pentanediol, 2-ethyl-1,3-hexane residues such as diol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, and 1,12-dodecanediol; You can do it. Among these, from the viewpoint of improving the strength of the film, 1,2-propylene glycol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 2-methyl-1,3-propanediol, 1 It is preferably a residue of ,5-pentanediol.

As the oxyalkylene glycol residue, an oxyalkylene glycol residue having 4 to 12 carbon atoms is preferable from the viewpoint of more easily expressing the effect of the present invention, and examples thereof include diethylene glycol, triethylene glycol, tetra Residues, such as ethylene glycol, dipropylene glycol, and tripropylene glycol, are mentioned, and may be individual, or may use 2 or more types together.

As the aryl glycol residue, an aryl glycol residue having 6 to 18 carbon atoms is preferable from the viewpoint of more easily expressing the effects of the present invention, and examples thereof include hydroquinone, resorcinol, bisphenol A, and alkylene oxides of bisphenol A. and residues such as adducts, bisphenol F, alkylene oxide adducts of bisphenol F, biphenol, and alkylene oxide adducts of biphenol.

From the viewpoint of further expressing the effect of the present invention, in general formula (2), B2 is benzoic acid or acetic acid residue, G is 1,2-propylene glycol, 1,3-propanediol, 1,2-butanediol, Residues of 1,3-butanediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, diethylene glycol, and dipropylene glycol are preferred.

The diester compound (II) may be synthesized or may be commercially available, and when synthesized, it is prepared using the same method as the esterification reaction described above, and in the general formula (1) It can be obtained by a known method, such as a method of isolating the component of n = 0 using operations such as distillation or a column, and is not limited as the method. In addition, subcomponents other than the n=0 component may be included, and in the mixture after mixing uniformly with the ester resin (I), as long as the conditions specified in the present invention can be satisfied, as the diester compound (II) , You may use a plurality of things made of mutually different raw materials.

The ester resin of the present invention obtained by such a method or the like can be used as a so-called anti-plasticizing agent, which can be used as a so-called semi-plasticizer, by blending this with a resin for optical materials, the obtained film can be made excellent in moisture permeability resistance, elastic modulus, and optical property balance. , In particular, it can be suitably used as an optical film.

The resin for optical materials is not particularly limited as long as it has high transparency and can be processed into a film, and examples thereof include (meth)acrylic resins, cyclic olefin resins, polycarbonate resins, and cellulose ester resins. etc. can be mentioned. In particular, it is preferable to use a cellulose ester resin from the viewpoint of further exhibiting the effect of the present invention.

What is necessary is just to determine the compounding quantity of the ester resin of this invention with respect to resin for optical materials according to the target performance (moisture permeability resistance, elastic modulus, etc.), for example, 0.1-50 mass parts with respect to 100 mass parts of resins for optical materials. It is a range, and it is preferable that it is the range of 1-30 mass parts, and it is more preferable that it is the range of 5-20 mass parts especially.

Examples of the cellulose ester resin include those obtained by esterification of some or all of the hydroxyl groups of cellulose obtained from cotton linters, wood pulp, kenaf, etc. Among them, cellulose obtained from cotton linters A film obtained using a cellulose ester resin obtained by esterification is easily peelable from a metal support constituting a film manufacturing apparatus described later and can further improve the production efficiency of the film, so it is preferable.

Examples of the cellulose ester resin include cellulose acetate, cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate phthalate, and cellulose nitrate. When used as a protective film for polarizing plates, cellulose acetate is used. This is preferable because a film having excellent mechanical properties and transparency can be obtained. These cellulose ester resins may be individual or may use 2 or more types together.

The cellulose acetate preferably has a degree of polymerization in the range of 250 to 400, and preferably has a degree of acetylation in the range of 54.0 to 62.5% by mass, more preferably 58.0 to 62.5% by mass. When the degree of polymerization and acetylation of the cellulose acetate are within these ranges, a film having excellent mechanical properties can be obtained. In this invention, it is more preferable to use so-called cellulose triacetate. In addition, the degree of acetylation as used in the present invention is a mass ratio of acetic acid produced by saponifying the cellulose acetate to the total amount of cellulose acetate.

It is preferable that it is the range of 70,000-300,000, and, as for the number average molecular weight of the said cellulose acetate, it is more preferable that it is the range of 80,000-200,000. When the number average molecular weight of the cellulose acetate is within this range, a film having excellent mechanical properties can be easily obtained.

The optical film in this invention uses the cellulose ester resin composition containing the ester resin of this invention and cellulose ester resin, You may use the resin composition formed by containing other various additives etc. as needed.

In order to obtain the optical film of the present invention, methods such as extrusion molding and cast molding are used, for example. Specifically, the unstretched optical film can be extruded using, for example, an extruder equipped with a T die, a circular die, or the like. In the case of obtaining the optical film of the present invention by extrusion molding, a resin composition obtained by melt-kneading the ester resin, cellulose ester resin, and other additives in advance may be used, and during extrusion molding, melt-kneading , it can also be extruded as it is.

Examples of the above additives include modifiers other than the ester resin of the present invention, thermoplastic resins, ultraviolet absorbers, matting agents, deterioration inhibitors (eg, antioxidants, peroxide decomposers, radical inhibitors, metals) inactivators, acid trapping agents, etc.), dyes, and the like.

Examples of the other modifier include ester resins other than the ester resins specified in the present invention, phosphate esters such as triphenyl phosphate (TPP), tricresyl phosphate, and cresyl diphenyl phosphate, dimethyl phthalate, diethyl phthalate, and dibutyl phthalate. , phthalic acid esters such as di-2-ethylhexyl phthalate, ethyl phthalyl ethyl glycolate, butyl phthalyl butyl glycolate, trimethylolpropane tribenzoate, pentaerythritol tetraacetate, tributyl acetyl citrate, etc. of the present invention It can be used within a range that does not impair the effect.

Although it does not specifically limit as said thermoplastic resin, For example, polyester resins other than the ester resin of this invention, polyester ether resin, polyurethane resin, epoxy resin, toluenesulfonamide resin, etc. are mentioned.

Examples of the ultraviolet absorber include, but are not particularly limited to, oxybenzophenone-based compounds, benzotriazole-based compounds, salicylic acid ester-based compounds, benzophenone compounds, cyanoacrylate-based compounds, and nickel complex salt-based compounds. . It is preferable to use the said ultraviolet absorber in the range of 0.01-2 mass parts with respect to 100 mass parts of said cellulose ester resins.

Examples of the mat agent include silicon oxide, titanium oxide, aluminum oxide, calcium carbonate, calcium silicate, aluminum silicate, magnesium silicate, calcium phosphate, kaolin, and talc. It is preferable to use the said mat agent in the range of 0.1-0.3 mass part with respect to 100 mass parts of said cellulose ester resins.

The dye is not particularly limited as long as it does not impair the purpose of the present invention.

In addition to the above molding method, for the optical film, for example, a resin solution obtained by dissolving the cellulose ester resin composition in an organic solvent is cast on a metal support, and then the organic solvent It can also be obtained by molding by a so-called solution casting method (solvent casting method) in which it is distilled off and dried.

According to the solution casting method, since the orientation of the cellulose ester resin in the film during molding can be suppressed, the obtained film can exhibit substantially optical isotropy. The film exhibiting the optical isotropy can be used for, for example, optical materials such as liquid crystal displays, and is particularly useful for protective films for polarizing plates. In addition, the film obtained by the above method hardly forms irregularities on its surface and has excellent surface smoothness.

The solution casting method generally includes a first step of dissolving the cellulose ester resin composition in an organic solvent and casting the obtained resin solution onto a metal support, distilling off the organic solvent contained in the casting resin solution, It consists of the 2nd process of drying and forming a film, and the 3rd process of peeling the film formed on the metal support body subsequent to it from a metal support body, and drying by heating.

As the metal support used in the first step, endless belt-shaped or drum-shaped metal supports can be exemplified. can be used

When casting a resin solution on the said metal support body, it is preferable to use the resin solution filtered by the filter in order to prevent foreign matter from mixing in the obtained film.

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

Next, the said 3rd process is a process of peeling the film formed in the said 2nd process from the metal support body, and heating and drying it under temperature conditions higher than the said 2nd process. As the heat-drying method, a method in which the temperature is raised stepwise under a temperature condition of, for example, 100 to 160°C is preferable because 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.

In the first to third steps, the organic solvent can be recovered and reused.

The organic solvent that can be used when mixing and dissolving the resin composition in an organic solvent is not particularly limited as long as it can dissolve them. For example, when cellulose acetate is used as a cellulose ester, as a good solvent, For example, it is preferable to use an organic halogen compound such as methylene chloride or dioxolane.

In addition, the use of poor solvents such as methanol, ethanol, 2-propanol, n-butanol, cyclohexane, and cyclohexanone in combination with the above-mentioned good solvent improves the production efficiency of the film. desirable.

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 mass ratio.

10-50 mass % is preferable and, as for the density|concentration of the cellulose-ester resin in the said resin solution, 15-35 mass % is more preferable.

In the present invention, for example, the optical film in an unstretched state obtained by the method described above is longitudinally uniaxially stretched in the mechanical flow direction and transversely uniaxially stretched in the direction orthogonal to the mechanical flow direction, as necessary, to obtain a stretched optical film. You can get it. Further, a biaxially stretched film can be obtained by stretching by a sequential biaxial stretching method of roll stretching and tenter stretching, a simultaneous biaxial stretching method by tenter stretching, a biaxial stretching method by tubular stretching, or the like. The draw ratio is preferably 0.1% or more and 1000% or less in at least one direction, more preferably 0.2% or more and 600% or less, and particularly preferably 0.3% or more and 300% or less. By designing within this range, a stretched optical film suitable from the viewpoints of birefringence, heat resistance and strength can be obtained.

Since the optical film of this invention is excellent in moisture permeability resistance and transparency, and also excellent in elastic modulus, it can be used for the optical film of a liquid crystal display device, for example. As an optical film of the said liquid crystal display device, a protective film for polarizing plates, retardation film, a reflective film, a viewing angle improvement film, an anti-glare film, an anti-reflective film, an antistatic film, a color filter etc. are mentioned, for example, and a polarizing plate among them It can be used suitably as a protective film for use.

The film thickness of the optical film is preferably in the range of 20 to 120 μm, more preferably in the range of 25 to 100 μm, and particularly preferably in the range of 25 to 80 μm. When using the said optical film as a protective film for polarizing plates, if the film thickness is in the range of 25-80 micrometers, it is suitable when thinning a liquid crystal display device, and also has excellent film strength, Rth stability, moisture permeability resistance, etc. which are sufficient. performance can be maintained.

The optical film of the present invention is characterized in that the modulus of elasticity is higher than that in the case where no ester resin is blended. In general, for cellulose ester resins, polyester resins formulated for the purpose of improving processability are sometimes referred to as "plasticizers", but the ester resins of the present invention can improve the strength of optical material resins rather than the plasticizing effect. In terms of being used as a semi-plasticizer, it has performance different from that of the prior art.

Moreover, since the said protective film for polarizing plates can also be adjusted to desired Rth without generating bleed under high temperature and high humidity, it can use it for a wide range of liquid crystal display systems according to a use.

As the liquid crystal display method, for example, IPS (In-Plane Switching), TN (Twisted Nematic), VA (Vertically Aligned), OCB (Optically Compensatory) Bend: Optically Compensatory Bend) and the like may be exemplified.

The optical film according to the present invention, as an optical material, is a polarizing plate protective film, 1/4 wave plate, 1/2 used in displays such as liquid crystal displays, plasma displays, organic EL displays, field emission displays, and rear projection televisions. It can be used suitably for retardation films, such as a wave plate, a viewing angle control film, and a liquid crystal optical compensation film, and a front plate of a display. In addition, the resin composition of the present invention can also be used for waveguides, lenses, optical fibers, optical fiber substrates, coating materials, LED lenses, lens covers, etc. in the fields of optical communication systems, optical switching systems, and optical measurement systems. there is.

(Example)

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

Example 1

In a 2-liter three-necked flask, 412 g of 1,2-propylene glycol (hereinafter abbreviated as "PG") as a glycol component, 374 g of isophthalic acid (hereinafter abbreviated as "IPA") as a dicarboxylic acid component, and benzoic acid as a monocarboxylic acid component ( 611 g of (hereinafter abbreviated as "BzA") and 0.08 g of tetraisopropyl titanate (hereinafter abbreviated as "TIPT") as a catalyst were introduced, and the temperature was raised to 230°C stepwise under a nitrogen stream from a nitrogen inlet tube. It was made to carry out the condensation reaction at 230 degreeC for 8 hours, and it confirmed that the acid value became 1.0 or less. The ester resin (1) of this invention was obtained by removing excessive glycol at 195 degreeC under reduced pressure. The obtained ester resin (1) was a pale yellow liquid at normal temperature, had an acid value of 0.12 and a hydroxyl value of 10.0, and had a weight average molecular weight of 590. The n=0 component in the GPC measurement was 29 area%, and (n≧3)/(n=0) was 1.0.

Example 2

Ester resin by synthesizing in the same manner as in Example 1 using 412 g of PG as a glycol component, 280 g of IPA as a dicarboxylic acid component, 82 g of adipic acid (hereinafter abbreviated as "AA"), and 611 g of BzA and 0.08 g of TIPT as a monocarboxylic acid component. (2) was obtained. The obtained ester resin (2) was a pale yellow liquid at normal temperature, had an acid value of 0.07 and a hydroxyl value of 0.0, and had a weight average molecular weight of 780. The n=0 component in the GPC measurement was 24 area%, and (n≧3)/(n=0) was 1.1.

Example 3

An ester resin (3) was obtained by synthesizing in the same manner as in Example 1 using 412 g of PG as a glycol component, 187 g of IPA, 164 g of AA as a dicarboxylic acid component, and 611 g of BzA and 0.08 g of TIPT as a monocarboxylic acid component. The obtained ester resin (3) was a pale yellow liquid at normal temperature, had an acid value of 0.05 and a hydroxyl value of 1.1, and had a weight average molecular weight of 670. The n=0 component in the GPC measurement was 25 area%, and (n≧3)/(n=0) was 1.1.

Example 4

An ester resin (4) was obtained by synthesizing in the same manner as in Example 1 using 412 g of PG as a glycol component, 94 g of IPA, 245 g of AA as a dicarboxylic acid component, and 611 g of BzA and 0.08 g of TIPT as a monocarboxylic acid component. The obtained ester resin (4) was a pale yellow liquid at normal temperature, had an acid value of 0.08 and a hydroxyl value of 5.4, and had a weight average molecular weight of 620. The n=0 component in the GPC measurement was 31 area%, and (n≧3)/(n=0) was 0.7.

Example 5

Synthesis was carried out in the same manner as in Example 1 using 412 g of 1,3-propanediol (hereinafter abbreviated as "13PD") as a glycol component, 280 g of IPA and 82 g of AA as a dicarboxylic acid component, and 611 g of BzA and 0.08 g of TIPT as a monocarboxylic acid component. By doing so, an ester resin (5) was obtained. The obtained ester resin (5) was a pale yellow liquid at normal temperature, had an acid value of 0.11 and a hydroxyl value of 8.9, and had a weight average molecular weight of 640. The n=0 component in the GPC measurement was 29 area%, and (n≧3)/(n=0) was 0.8.

Example 6

Example 1 using 488 g of 2-methyl-1,3-propanediol (hereinafter abbreviated as “2MPD”) as a glycol component, 280 g of IPA and 82 g of AA as a dicarboxylic acid component, and 611 g of BzA and 0.08 g of TIPT as a monocarboxylic acid component Ester resin (6) was obtained by carrying out similarly and synthesize|combining. The obtained ester resin (6) was a pale yellow liquid at normal temperature, had an acid value of 0.11 and a hydroxyl value of 12.6, and had a weight average molecular weight of 560. The n=0 component in the GPC measurement was 40 area%, and (n≧3)/(n=0) was 0.4.

Comparative Example 1

Into a 2-liter three-necked flask, 437 g of PG as a glycol component, 180 g of phthalic acid (hereinafter abbreviated as "PA") and 178 g of AA as a dicarboxylic acid component, 659 g of BzA and 0.09 g of TIPT as a monocarboxylic acid component were charged, and from a nitrogen inlet pipe Under a nitrogen stream, the temperature was raised to 220°C step by step. It was made to carry out the condensation reaction at 220 degreeC for 13 hours, and it confirmed that the acid value became 1.0 or less. An ester resin (1') for comparison and control was obtained by removing excess glycol at 195°C under reduced pressure. The obtained ester resin (1') was a pale yellow liquid at normal temperature, had an acid value of 0.09 and a hydroxyl value of 1.2, and had a weight average molecular weight of 640.

Comparative Example 2

A polyester resin (2') for comparison was obtained by synthesizing in the same manner as in Comparative Example 1 using 313 g of PG, 262 g of AA, 436 g of BzA, and 0.10 g of TIPT as the glycol component. The obtained polyester resin (2') for comparison object was a pale yellow liquid at normal temperature, the acid value was 0.50, the hydroxyl value was 12.6, and the weight average molecular weight was 610.

Comparative Example 3

A polyester resin (3') for comparison was obtained by synthesizing in the same manner as in Comparative Example 1 using 460 g of PG, 466 g of dimethyl terephthalate, 586 g of BzA, and 0.09 g of TIPT as glycol components. The obtained polyester resin (3') for comparison object was a pale yellow viscous liquid at normal temperature, the acid value was 0.24, the hydroxyl value was 5.4, and the weight average molecular weight was 650.

Examples 7 to 12, Comparative Examples 4 to 7

<Adjustment of cellulose ester optical film>

Triacetyl cellulose resin ("LT-35" manufactured by Daicel Corporation) 100 parts, ester resins (1) to (6), ester resins (1') to (3') 10 parts, methylene chloride 810 parts and methanol 90 It was added and dissolved in a mixed solvent composed of parts to prepare a dope liquid that is a cellulose ester resin composition. In Comparative Example 7, a dope solution was prepared by dissolving only a triacetyl cellulose resin in a mixed solvent without blending an ester resin. These dope liquids were cast on a glass plate to a thickness of 0.8 mm or 0.5 mm, dried at room temperature for 16 hours, and then dried at 50°C for 30 minutes and further at 120°C for 30 minutes to obtain an optical film (60 µm) of the present invention. or 40 μm). About the obtained film, physical properties were measured according to the following, and the results are shown in Table 1.

<Measurement of elastic modulus of optical film>

Apparatus: Autograph AG-IS manufactured by Shimadzu Seisakujo Co., Ltd.

Test piece: 150 mm × 10 mm, 40 μm thick strip type

Between chucks: 100mm

Test speed: 10 mm/min

It shows that it is a hard film, so that elastic modulus is large.

<Measurement of phase difference Rth of optical film>

The Rth value was measured for the optical film at a wavelength of 590 nm using a birefringence measuring device (KOBRA-WR, manufactured by Oji Scientific Instruments Co., Ltd.) under an environment with a relative humidity of 55% at 23°C.

<Measurement of moisture permeability of optical film>

It was measured according to the method described in JIS Z 0208. Measurement conditions were performed at a temperature of 40°C and a relative humidity of 90%. It shows that it is excellent in moisture permeability resistance, so that the value obtained is small.

[Table 1]

Claims (11)

The following general formula (1)
B-(GA) _n -GB (1)
[In Formula (1), B is at least one residue selected from the group consisting of acetic acid, benzoic acid, p-toluic acid, and dimethylbenzoic acid, and G is ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, At least one residue selected from the group consisting of 1,2-butanediol and 2-methyl-1,3-propanediol, wherein A is selected from the group consisting of succinic acid, adipic acid, dicarboxycyclohexane, phthalic acid, terephthalic acid and isophthalic acid. At least 20 mol% of the total number of moles of A is isophthalic acid, n is the number of repetitions, G and A may be the same or different for each repetition, and a plurality of B and G are the same It can be done or it can be different]
As an ester resin represented by,
In the area ratio in GPC measurement, the ratio of the area % of the component where n = 0 in the above formula (1) is 10 to 50%, and the area % of the component where n is 3 or more and the area % of the n = 0 component (n≥3) A semi-plasticizer for resins for optical materials comprising an ester resin in which /(n = 0) is 0.2 or more and 3 or less. According to claim 1,
The semiplasticizer whose average value of n in the said General formula (1) is 0.2-3. According to claim 1 or 2,
A semi-plasticizer in which the weight average molecular weight of the ester resin is in the range of 350 to 1200. According to claim 1 or 2,
A semiplasticizer in which 25 to 100 mol% of the total number of moles of A in the general formula (1) is isophthalic acid. According to claim 1 or 2,
The semi-plasticizer whose said ratio (n≥3)/(n=0) is 0.2 or more and 1.5 or less. A cellulose ester resin composition characterized by containing the semiplasticizer according to claim 1 or 2 and a cellulose ester resin. An optical film characterized by containing the cellulose ester resin composition according to claim 6. According to claim 7,
Optical film for protecting the polarizer. A liquid crystal display device comprising the optical film according to claim 7. delete delete