KR102534517B1 - Ester resin, semi-plasticizer, cellulose ester resin composition, optical film and liquid crystal display device - Google Patents

Abstract

An ester resin that is excellent in balance of strength, heat resistance, and dimensional stability when processed into a film and can be suitably used as a semi-plasticizer for optical resins, a resin composition containing the same, and a resin composition obtained by using the resin composition. An optical film and a liquid crystal display device using the same are provided. Specifically, general formula
H-(G ¹ -A) _n -G ¹ -H (I)
[In formula (I), G ¹ is an alkylene glycol residue, an oxyalkylene glycol residue, or an aryl glycol residue, A is a dicarboxylic acid residue, 25 mol% or more of the total number of moles of A is an isophthalic acid residue, and n is number of repetitions, G ¹ and A may be the same or different for each repetition, and a plurality of G ¹ may be the same or different] An ester resin characterized by being represented by, a resin composition containing the same, and use of the composition A film for optics thus obtained and a liquid crystal display device using the film for optics are used.

Description

Ester resin, semi-plasticizer, cellulose ester resin composition, optical film and liquid crystal display device

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

In recent years, liquid crystal displays are progressing in thinning, and polarizing plate protective films are also progressing in thinning from conventional 80 μm to 60 μm, and furthermore, from 40 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 hygroscopicity, and dimensional change due to moisture permeation and moisture absorption easily occurs, it is necessary to suppress moisture permeation and moisture absorption with additives, and various additives have been provided (see, for example, Patent Document 1 ).

Usually, when an additive is added to suppress moisture permeation or moisture absorption, plasticization of the resin occurs at the same time, making it difficult to achieve both physical properties such as strength and heat resistance of the resulting film and dimensional stability. Therefore, there is a need to develop an additive capable of providing a film having excellent elastic modulus, heat resistance and dimensional stability.

Japanese Unexamined Patent Publication No. 2013-151699

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

As a result of intensive studies, the inventors of the present invention have found that the above problems can be solved by making the dicarboxylic acid component in the raw material of the ester resin a specific one, and have completed the present invention.

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

H-(G ¹ -A) _n -G ¹ -H (I)

[In formula (I), G ¹ is an alkylene glycol residue, an oxyalkylene glycol residue, or an aryl glycol residue, A is a dicarboxylic acid residue, 25 mol% or more of the total number of moles of A is an isophthalic acid residue, and n is It is the number of repetitions, and for each repetition, G ¹ and A may be the same or different, and when a plurality of G ¹ exist, G ¹ may be the same or different]

An ester resin characterized by being represented by and an ester resin mixture containing the same, a semi-plasticizer comprising the same, a cellulose ester resin composition, an optical film obtained using the composition, and a liquid crystal display device using the optical film is to provide

According to the present invention, it is possible to provide an ester resin or an ester resin mixture that has an excellent balance of strength, heat resistance, and dimensional stability when processed into a film and can be suitably used as a semi-plasticizer for optical resins. In addition, by using the specific ester resin or a mixture thereof, in an optical film containing a cellulose ester resin in particular, it is possible to improve the elastic modulus, heat resistance, and dimensional stability without impairing transparency, It can be used suitably as an optical film used for a liquid crystal display device.

The ester resin of the present invention,

The following general formula (I)

H-(G ¹ -A) _n -G ¹ -H (I)

[In formula (I), G ¹ is an alkylene glycol residue, an oxyalkylene glycol residue, or an aryl glycol residue, A is a dicarboxylic acid residue, 25 mol% or more of the total number of moles of A is an isophthalic acid residue, and n is It is the number of repetitions, and for each repetition, G ¹ and A may be the same or different, and when a plurality of G ¹ exist, G ¹ may be the same or different]

It is characterized by being displayed as.

G ¹ in the general formula (I) 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, more preferably a residue of ethylene glycol or 1,2-propylene glycol, It is most preferably a residue of 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 (I) 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 25 mol% or more. Here, the dicarboxylic acid residue refers to a group from which -OH in the carboxyl group has been removed.

In the ester resin represented by the general formula (I), 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 being made, it can be suitably used for optical film applications in which thinning progresses without impairing the transparency originally possessed by the resin for optics, while improving the elastic modulus and imparting heat resistance.

From the viewpoint of exhibiting the above-mentioned effects, it is essential that the number of moles of isophthalic acid residues in the dicarboxylic acid residues is 25 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 preferably in the range of , more preferably in the range of 40 to 100%, and most preferably in the range of 70 to 90%.

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 having more excellent film transparency can be 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 (I) may be a mixture of compounds in which G ¹ and A are the same and differ only in n, that is, the number of repetitions, or G in the general formula (I) A mixture of compounds in which ¹ , A and n are different from each other may be used.

From the viewpoint of further expressing the effects of the present invention, in general formula (I), G ¹ is ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 1,2-butanediol, 2-methyl- Residue of 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, ^G1 is ethylene It is a residue of glycol or 1,2-propylene glycol, and it is most preferable that A1 which may be present together is an adipic acid residue and A2 is a phthalic acid residue.

In the present invention, in an optical film obtained by mixing with a resin for an optical material described later, particularly a cellulose ester resin, in order to reduce non-volatile components in the film manufacturing process and to obtain an optical film having more excellent moisture absorption dimensional stability, It is preferable to reduce the amount of residual glycol in the ester resin represented by the general formula (I) by distillation or the like. The amount of residual glycol in the ester resin is preferably 1.5% by mass or less, and most preferably 1.0% by mass or less. In addition, the amount of residual glycol can be measured by gas chromatography.

In addition, the number average molecular weight of the ester resin of the present invention is preferably in the range of 350 to 2000, particularly preferably in the range of 400 to 1500, and preferably in the range of 500 to 1200, from the viewpoint of achieving both compatibility and film properties. is most preferable Also, the average value of the number of repeats n in the general formula (I) is preferably in the range of 1.0 to 10.0, more preferably in the range of 1.0 to 8.0, and more preferably in the range of 1.0 to 8.0, from the viewpoint of achieving both compatibility and film properties. A range of 7.0 is most preferred. In addition, this number average molecular weight and the average value of n are the values measured by GPC measurement.

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.

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.

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 acid and dicarboxylic acid, the acid as it is 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 number average molecular weight and combinations of raw materials, but are usually liquid, solid, pasty 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 dicarboxylic acid may be reacted. After obtaining the compound which has a hydroxyl group at the terminal obtained using carboxylic acid, the sequential reaction which further introduce|throws-in a monocarboxylic acid into a reaction system may be sufficient.

In the present invention, the above-described ester resin may be used alone and added to a resin for optical materials such as a cellulose ester resin described later, or the following general formula (II)

BG ² -B (II)

[In formula (II), B is an aryl monocarboxylic acid residue or an aliphatic monocarboxylic acid residue, G ² is an alkylene glycol residue, an oxyalkylene glycol residue, or an aryl glycol residue, and when a plurality of B exists, B is the same It can be done or it can be different]

You may use together the diester compound represented by.

B in the said general formula (II) 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 has advantages in the availability of raw materials, ease of esterification reaction, and resistance to moisture permeability, elastic modulus, and dimensional stability 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, para-toluic acid, or dimethylbenzoic acid, and more preferably a residue of benzoic acid or para-toluic 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 as a raw material and easy to esterify, and when mixed with a cellulose ester resin described later, moisture permeability resistance, elastic modulus, and dimensional stability balance It is preferable from the viewpoint of easy capture, 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 ² in the general formula (II) 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, ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 2-methyl-1,3-propane It is preferably a diol or a residue of 1,5-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 (II), B is benzoic acid or paratoluic acid residue, G ² is ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, It is preferably a residue of 2-methyl-1,3-propanediol, diethylene glycol or dipropylene glycol.

The diester compound (II) may be synthesized, or may be commercially available, and when synthesized, the reaction conditions (catalyst, temperature, time, etc.) are, for example, the ester resin used in the present invention ( Conditions used in the synthesis of I) may be used.

The ester resin mixture of the present invention contains the ester resin (I) and the diester compound (II) in a mass ratio [ester resin/diester compound] in the range of 100/0 to 50/50, as described later. It is preferable at the point which can be used suitably as a semiplasticizer of resin for optics.

When such a diester compound (II) is included, it is suitably disposed between the gaps of the optical material resin, particularly the cellulose ester resin, and as a result, the effect of improving the moisture permeability resistance, elastic modulus, and dimensional stability is further expressed, and , compatibility with the resin for optical materials can be ensured, and transparency usable as an optical film can be maintained more effectively.

From the viewpoints of further developing these effects, suppressing contamination of production lines due to volatilization, and facilitating maintenance of the transparency of the optical film, the ester resin (I) and the diester compound (II) The proportion of the ester resin (I) in the total mass of is preferably 50 to 100% by mass, more preferably 60 to 95% by mass, and most preferably 65 to 90% by mass.

The ester resin mixture of the present invention may consist only of the ester resin (I) and the diester compound (II), and contain a polyester other than the ester resin (I) or a diester compound other than the diester compound (II). You can do it. In addition, it may contain what is known as a so-called optical resin modifier other than the ester resin (I) or the diester compound (II), and the raw materials used in the production of the ester resin (I) or the diester compound (II) It may contain a reactant.

The ester resin or ester resin mixture of the present invention obtained by such a method or the like can be used as a so-called semi-plasticizing agent, by blending the ester resin or ester resin mixture with a resin for an optical material, the resulting film can be made excellent in the balance of elastic modulus, heat resistance, and dimensional stability. It is possible, and the obtained film is particularly suitable 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.

The compounding amount of the ester resin and ester resin mixture of the present invention with respect to the resin for optical materials may be determined according to the target performance (elastic modulus, heat resistance, etc.), and is, for example, 0.1 to 0.1 to 100 parts by mass of the resin for optical materials. It is in the range of 50 parts by mass, preferably in the range of 1 to 30 parts by mass, and more preferably in the range of 3 to 20 parts by mass.

Examples of the cellulose ester resin include those obtained by esterifying some or all of the hydroxyl groups of cellulose obtained from cotton linters, wood pulp, kenaf, and the like.

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 the present invention uses a resin composition containing the ester resin or ester resin mixture of the present invention and a resin for optical materials such as a cellulose ester resin, and, if necessary, contains various other additives and the like. You may use a resin composition.

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 melting and kneading the resin for optical materials such as the ester resin, ester resin mixture, cellulose ester resin, and other additives in advance is used. Alternatively, it may be melt-kneaded during extrusion molding and then extruded as it is.

As the additives, for example, the ester resin of the present invention, other modifiers other than the diester compound, thermoplastic resins, ultraviolet absorbers, matting agents, stabilizers, deterioration inhibitors (eg, antioxidants, peroxide decomposers, radical inhibitors) agents, metal deactivators, acid trapping agents, etc.), dyes, and the like.

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

Although it does not specifically limit as said thermoplastic resin, For example, polyester resin other than the ester resin of this invention, polyester ether resin, polyurethane resin, acrylic 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.

Examples of the stabilizer include calcium hydroxide, calcium carbonate, and metal salts of fatty acids. It is preferable to use the said stabilizer in the range of 50-5000 ppm 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 a resin for optical materials such as the above 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 the is distilled off and dried.

According to the solution casting method, since the orientation of the resin for optical materials such as the cellulose ester resin in the film during molding can be suppressed, the obtained film can substantially exhibit 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 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 and drying it; It consists of the 2nd process of 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 heat-drying it.

As the metal support used in the first step, an endless belt-shaped or drum-shaped metal support can be exemplified. For example, a stainless steel support with a mirror finish 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 resin for optical materials, a good solvent As such, it is preferable to use, for example, organic halogen compounds such as methylene chloride or dioxolanes.

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 resin for optical materials in the said resin solution, 15-35 mass % is more preferable.

In the present invention, for example, the unstretched optical film obtained by the above method is longitudinally axially 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 300% or less in at least one direction, more preferably 0.2% or more and 250% or less, and most preferably 0.3% or more and 200% 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 the present invention is excellent in elasticity modulus, heat resistance, moisture permeability resistance and dimensional stability, it can be used, for example, for an optical film of a liquid crystal display device. 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 the resin for optical materials rather than the plasticizing effect. In terms of being used as a semi-plasticizer, it has performance different from that of the prior art.

In addition, since the protective film for polarizing plates can be adjusted to a desired phase difference without causing bleeding under high temperature and high humidity, it can be widely used in various liquid crystal display systems depending on the application.

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 1 liter four-necked flask, 346 g of 1,2-propylene glycol (hereinafter abbreviated as "PG") as a glycol component, 376 g of isophthalic acid (hereinafter abbreviated as "IPA") as a dicarboxylic acid component, and adipic acid (hereinafter abbreviated as "IPA") 110 g of (abbreviated as "AA") and 0.05 g of tetraisopropyl titanate (hereinafter abbreviated as "TIPT") as a catalyst were introduced, and the temperature was gradually raised to 230°C 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 excess glycol at 150 degreeC under reduced pressure. The obtained ester resin (1) was a pale yellow liquid at normal temperature, had an acid value of 0.25 and a hydroxyl value of 135, the number average molecular weight was 920, and the amount of residual PG was 0.2% by mass.

Example 2

352 g of PG as a glycol component, 257 g of IPA and 226 g of AA as a dicarboxylic acid component, and 0.05 g of TIPT as a catalyst were put into a 1 liter four-necked flask, and the temperature was raised to 230°C stepwise from a nitrogen inlet tube under a nitrogen stream. 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 (2) of this invention was obtained by removing excess glycol at 150 degreeC under reduced pressure. The obtained ester resin (2) was a pale yellow liquid at normal temperature, had an acid value of 0.27 and a hydroxyl value of 135, the number average molecular weight was 950, and the amount of residual PG was 0.2% by mass.

Comparative Example 1

Into a 3-liter four-necked flask, 922 g of PG as a glycol component, 944 g of phthalic anhydride (hereinafter abbreviated as "PA") as a dicarboxylic acid component, 310 g of AA, and 0.13 g of TIPT as a catalyst were charged, and from a nitrogen inlet tube under a nitrogen stream , and the temperature was raised to 220°C in stages. It was made to condensate at 220 degreeC for 8 hours, and when the acid value became 1 or less, the reaction product was taken out by filtration and ester resin (1') was obtained. The obtained ester resin (1') was a pale yellow liquid at normal temperature, had an acid value of 0.50 and a hydroxyl value of 163, the number average molecular weight was 790, and the amount of residual PG was 3.0% by mass.

Comparative Example 2

Ester resin (2') was obtained by removing excessive glycol from ester resin (1') at 150 degreeC under reduced pressure. The obtained ester resin (2') was a pale yellow liquid at normal temperature, had an acid value of 0.18, a hydroxyl value of 147, a number average molecular weight of 800, and the amount of residual PG was 0.5% by mass.

Examples 3 to 4, Comparative Examples 3 to 4

<Adjustment of cellulose ester optical film>

Triacetyl cellulose resin ("LT-35" manufactured by Daicel Corporation) 100 parts, ester resins (1) to (2), ester resins (1') to (2') 10 parts, methylene chloride 810 parts and methanol 90 parts It was added and dissolved in a mixed solvent composed of parts to prepare a dope liquid that is a cellulose ester resin composition. 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 further dried at 50°C for 30 minutes or 120°C for 30 minutes to form an optical film (60 µm or 40 µm). got 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

Chuck gap: 100mm

Test speed: 10 mm/min

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

<Evaluation method of elastic modulus>

×: elastic modulus of 4600 MPa or less

○: elastic modulus higher than 4600 MPa and 4650 MPa or less

◎: Elastic modulus higher than 4650 MPa

<Measurement of heat resistance of optical film>

Apparatus: RSA-III tension mode manufactured by TA Instruments

Heating rate: 3℃/min

Frequency: 1Hz

Load strain: 0.1%

Test piece film thickness: 60㎛

The peak top of tanδ is Tg, and the higher the Tg, the better the heat resistance.

<Evaluation method of heat resistance>

×: Tg is 182°C or less

○: Tg higher than 182°C

<Measurement of dimensional stability of optical film>

Device: SIINT TMA/SS6100 + humidity control unit manufactured by Hitachi High-Tech Co., Ltd.

Measurement temperature: 40℃ constant

Relative humidity: 0% to 80%

Measured load: 50 mN

Test piece film thickness: 60㎛

The rate of dimensional change when the relative humidity was set to 0% to 80% was measured. The smaller the rate of change, the better the dimensional stability.

<Evaluation method of dimensional stability>

×: dimensional change rate greater than 0.45%

○: dimensional change rate of 0.40% or more and 0.45% or less

◎: dimensional change rate is less than 0.40%

<HAZE>

The HAZE value was measured based on JIS K 7105 using a turbidity meter (“NDH 5000” manufactured by Nippon Denshoku Kogyo Co., Ltd.). The closer the obtained value is to 0%, the more transparent it is.

<Evaluation method of transparency>

×: HAZE value greater than 1.0%

○: HAZE value is 1.0% or less

<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.

<Method for evaluating moisture permeability resistance>

×: The moisture permeability is greater than 600 g/m 2 24h

○: moisture permeability of 600 g/m 2 24 h or less

<Evaluation of non-volatility>

The amount of change in mass when the film was exposed to an environment of 85°C and a relative humidity of 90% (under a moist heat environment) for 120 hours was measured. It shows that it is excellent in non-volatility, so that the value obtained is small.

<Evaluation method of non-volatility>

×: Moist heat loss greater than 1.5%

○: Moist heat loss is 1.5% or less

[Table 1]

Elastic modulus and Tg improved by using isophthalic acid for the dicarboxylic acid component of ester resin (I). In addition, by reducing the amount of residual glycol of the ester resin (I), while the moisture absorption dimensional change is suppressed, the moisture permeability resistance and non-volatility in a moist heat environment are improved.

Synthesis Example 1

1,906 g of p-toluic acid as a monocarboxylic acid component, 639 g of PG as a glycol component, and 0.153 g of TiPT as a catalyst were added to a 3-liter four-necked flask, and then heated to 220°C and reacted for 11 hours. After the reaction, unreacted glycol was distilled off under reduced pressure at 200°C. After that, the pressure was released and the temperature was decreased, and the reaction product was collected by filtration to obtain a transparent yellow liquid diester compound (a). The number average molecular weight (Mn) of the diester compound (a) was 310, the acid value was 0.10, and the hydroxyl value was 4.

Synthesis Example 2

In a 2-liter four-necked flask, 900 g of benzoic acid (hereinafter abbreviated as "BzA") as a monocarboxylic acid component, 294 g of PG as a glycol component, 50 g of dipropylene glycol, and 0.62 g of TiPT as a catalyst were added, and the temperature was raised to 220 ° C. time reacted. After the reaction, unreacted glycol was distilled off under reduced pressure at 200°C. After the distillation of unreacted alcohol ceased, the reduced pressure was released and the temperature was decreased, and the reaction product was collected by filtration to obtain a diester compound (b) in the form of a transparent yellow liquid. The number average molecular weight (Mn) of the diester compound (b) was 300, the acid value was 0.07, and the hydroxyl value was 7.

Synthesis Example 3

952 g of BzA as a monocarboxylic acid component, 124 g of PG as a glycol component, 281 g of diethylene glycol, and 0.68 g of TiPT as a catalyst were added to a 2-liter four-necked flask, and the mixture was heated to 220°C and reacted for 11 hours. After the reaction, unreacted glycol was distilled off under reduced pressure at 200°C. After the distillation of unreacted alcohol ceased, the pressure was released and the temperature was decreased, and the reaction product was collected by filtration to obtain a diester compound (c) in the form of a transparent yellow liquid. The number average molecular weight (Mn) of the diester compound (c) was 350, the acid value was 0.05, and the hydroxyl value was 3.

Examples 5 to 11, Comparative Examples 5 to 7

<Adjustment of cellulose ester optical film>

100 parts of triacetyl cellulose resin ("LT-35" manufactured by Daicel Co., Ltd.), ester resins (1) to (2), ester resins (1') to (2') and diester compounds (a) to (c) ) at the ratios shown in Tables 2 and 3, and dissolved in a mixed solvent composed of 10 parts, 810 parts of methylene chloride, and 90 parts of methanol, to prepare a dope liquid that is a cellulose ester resin composition. 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 further dried at 50 ° C. for 30 minutes or 120 ° C. for 30 minutes. The optical film of the present invention (60 μm or 40 μm) was obtained. About the obtained film, physical properties were measured according to the above, and the results are shown in Tables 2-3.

[Table 2]

[Table 3]

The addition of the diester compound (II) greatly improved the elastic modulus, dimensional stability, and resistance to moisture permeability. All have a low HAZE value and sufficient transparency as an optical film.

Claims (14)

The following general formula (I)
H-(G ¹ -A) _n -G ¹ -H (I)
[In formula (I), G ¹ is an alkylene glycol residue, an oxyalkylene glycol residue, or an aryl glycol residue, A is a dicarboxylic acid residue, 25 mol% or more of the total number of moles of A is an isophthalic acid residue, and n is It is the number of repetitions, and for each repetition, G ¹ and A may be the same or different, and when a plurality of G ¹ exist, G ¹ may be the same or different]
An ester resin represented by and a cellulose ester resin composition containing a cellulose ester resin,
The cellulose ester resin composition in which the blending amount of the ester resin is in the range of 0.1 to 50 parts by mass with respect to 100 parts by mass of the cellulose ester resin. According to claim 1,
G ¹ in the general formula (I) is an alkylene glycol residue having 2 to 12 carbon atoms, an oxyalkylene glycol residue having 4 to 12 carbon atoms, or an aryl glycol residue having 6 to 18 carbon atoms, and the average value of n is 1.0. Cellulose ester resin composition of -10.0. According to claim 1 or 2,
The cellulose ester resin composition whose number average molecular weight of the said ester resin is the range of 350-2000. According to claim 1 or 2,
G ¹ in the general formula (I) is 1 selected from the group consisting of ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 1,2-butanediol and 2-methyl-1,3-propanediol residues of at least one species, A is at least one residue selected from the group consisting of succinic acid, adipic acid, dicarboxycyclohexane, phthalic acid, terephthalic acid and isophthalic acid, and 25 mol% or more of the total number of moles of A is isophthalic acid residues A phosphorus cellulose ester resin composition. According to claim 1 or 2,
A cellulose ester resin composition in which 40 to 100 mol% of the total number of moles of A in the general formula (I) is an isophthalic acid residue. According to claim 1 or 2,
A cellulose ester resin composition in which the amount of residual glycol in the ester resin is 1.5% by mass or less. The following general formula (I)
H-(G ¹ -A) _n -G ¹ -H (I)
[In formula (I), G ¹ is an alkylene glycol residue, an oxyalkylene glycol residue, or an aryl glycol residue, A is a dicarboxylic acid residue, 25 mol% or more of the total number of moles of A is an isophthalic acid residue, and n is It is the number of repetitions, and for each repetition, G ¹ and A may be the same or different, and when a plurality of G ¹ exist, G ¹ may be the same or different]
An ester resin represented by
The following general formula (II)
BG ² -B (II)
[In formula (II), B is an aryl monocarboxylic acid residue or an aliphatic monocarboxylic acid residue, G ² is an alkylene glycol residue, an oxyalkylene glycol residue, or an aryl glycol residue, and when a plurality of B exists, B is the same It can be done or it can be different]
An ester resin mixture containing a diester compound represented by
An ester resin mixture containing the ester resin and the diester compound in a mass ratio [ester resin/diester compound] in a range of 95/5 to 50/50. According to claim 7,
The diester compound is a mixture of ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, diethylene glycol or dipropylene glycol and benzoic acid or p-toluic acid. An ester resin mixture that is a diester. delete The following general formula (I)
H-(G ¹ -A) _n -G ¹ -H (I)
[In formula (I), G ¹ is an alkylene glycol residue, an oxyalkylene glycol residue, or an aryl glycol residue, A is a dicarboxylic acid residue, 25 mol% or more of the total number of moles of A is an isophthalic acid residue, and n is It is the number of repetitions, and for each repetition, G ¹ and A may be the same or different, and when a plurality of G ¹ exist, G ¹ may be the same or different]
A semi-plasticizer for resins for optical materials, characterized by comprising the ester resin represented by or the ester resin mixture according to claim 7 or 8. A cellulose ester resin composition comprising the semiplasticizer according to claim 10 and a cellulose ester resin, comprising 1 to 30 parts by mass of the semiplasticizer based on 100 parts by mass of the cellulose ester resin. . An optical film characterized by containing the cellulose ester resin composition according to claim 1. According to claim 12,
Optical film for protecting the polarizer. A liquid crystal display device comprising the optical film according to claim 12 or 13.