TWI773857B - Plasticizer for cellulose ester resin, cellulose ester resin composition, optical film and liquid crystal display device - Google Patents

Abstract

The present invention is based on the provision of an ester resin (a cellulose ester resin which can be suitably used as a plasticizer, can improve moisture permeability resistance when processed into a film form, and is also excellent in storage stability in a humid heat environment) above), a resin composition containing it, an optical film obtained by using the resin composition, and a liquid crystal display device using the same, and to provide an ester resin, a cellulose ester resin composition comprising the same, and a cellulose ester resin composition comprising the same. Optical film and liquid crystal display device of the composition, wherein the ester resin is of formula B-(AG) _n -AB[B is an aliphatic monoalcohol residue, G is an alkanediol residue, an oxanediol residue or an aromatic residue. diol residue, A is an alkylene dicarboxylic acid residue (A1) or an aryl dicarboxylic acid residue (A2), and in the total (A1+A2) of (A1) and (A2), ( The content of A2) is 70 to 100 mol %, and n is the number of repetitions. ] The ester resin shown, and the number average molecular weight is 350~1000.

Description

Plasticizer for cellulose ester resin, cellulose ester resin composition, optical film and liquid crystal display device

The present invention relates to a suitable ester resin as a plasticizer for a cellulose ester resin, 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.

In recent years, the thinning of liquid crystal displays has progressed, and the polarizer protective film has also been thinned from the conventional 80 μm to 40 μm to 20 μm. From the viewpoint of easy bonding with a polarizer, as a protective film of a polarizing plate, triacetyl cellulose resin (hereinafter referred to as TAC) has been used in many cases.

However, TAC has high moisture permeability and is prone to dimensional change due to moisture absorption and hydrolysis under moist heat conditions. Therefore, it is necessary to suppress moisture absorption by additives, and various additives have been provided so far (for example, refer to Patent Documents 1 and 2).

However, especially in the case of ester-based additives, since the additives themselves are hydrolyzed, further improvement in the storage stability of the resin composition or the film formed by molding it is required.

prior art literature Patent Literature

Patent Document 1 Japanese Patent Application Laid-Open No. 2009-191219

Patent Document 2 Japanese Patent Application Laid-Open No. 2009-046531

In view of the above-mentioned actual situation, the problem to be solved by the present invention is to provide an ester resin, a resin composition containing the same, an optical film obtained by using the resin composition, and a liquid crystal display device using the same; the ester resin is especially It can be suitably used as a plasticizer for a cellulose ester resin that can improve the moisture permeability resistance when processed into a film, and is also excellent in storage stability in a humid heat environment.

As a result of intensive research, the present inventors found that the above-mentioned problems can be solved by setting the raw material components in the ester resin to be specific, and completed the present invention.

That is, the present invention provides an ester resin characterized in that it is an ester resin represented by the following general formula (1) and has a number average molecular weight of 350 to 1000: B-(AG) _n -AB (1)

[In formula (1), B is an aliphatic monoalcohol residue with 4 to 20 carbon atoms, G is an alkanediol residue, an oxanediol residue or an aryldiol residue, and A is an alkylene diol Carboxylic acid residue (A1) or aryldicarboxylic acid residue (A2), and the total of alkylene dicarboxylic acid residue (A1) and aryldicarboxylic acid residue (A2) (A1+A2) Among them, the content of aryldicarboxylic acid residues (A2) is 70~100 mol%, n is the number of repetitions, and in each repeating unit, G and A may be the same or different, and a plurality of A and B can be the same or different. ].

According to the present invention, an ester resin, a resin composition containing the same, an optical film obtained by using the resin composition, and a liquid crystal display device using the same can be provided; the ester resin can be suitably used as a plasticizer On the cellulose ester resin, which can improve the moisture permeability resistance when processed into a film form, and also has excellent storage stability in a humid and heat environment.

Form for carrying out the invention

The feature of the ester resin of the present invention is an ester resin characterized by the following; it is an ester resin represented by the following general formula (1), and the number average molecular weight is 350 to 1000: B-(AG) _n -AB ( 1)

[In formula (1), B is an aliphatic monoalcohol residue with 4 to 20 carbon atoms, G is an alkanediol residue, an oxanediol residue or an aryldiol residue, and A is an alkylene diol Carboxylic acid residue (A1) or aryldicarboxylic acid residue (A2), and the total of alkylene dicarboxylic acid residue (A1) and aryldicarboxylic acid residue (A2) (A1+A2) Among them, the content of aryldicarboxylic acid residues (A2) is 70-100 mol%, n is the number of repetitions, and in each repeating unit, G and A may be the same or different, and a plurality of A and B can be the same or different. ].

B in the aforementioned general formula (1) is an aliphatic monoalcohol residue having 4 to 20 carbon atoms. Here, the monoalcohol residue refers to a group obtained by removing a hydrogen atom from a hydroxyl group. The aforementioned aliphatic may have a branched structure, or may Those that are linear, for example, 1-butanol, 2-butanol, isobutanol, tertiary butanol, 1-pentanol, isoamyl alcohol, tertiary pentanol, cyclopentanol, 1- Hexanol, cyclohexanol, 1-heptanol, 1-octanol, 2-ethyl-1-hexanol, isononanol, 1-nonanol, tertiary nonanol, decanol, dodecanol, ten Residues such as dialkylhexanol, dodecyloctanol, allyl alcohol, oleyl alcohol, etc., B in the general formula (1) may be a resin composed of the same or different ones. mixture.

Among these, aliphatic having 6 to 12 carbon atoms is preferred from the viewpoint of good compatibility with cellulose ester resin, better storage stability as a resin composition, and better storage stability as a film The monoalcohol residue is more preferably an aliphatic monoalcohol residue having 9 to 12 carbon atoms, particularly preferably a nonanol residue or an isonononanol residue.

G in the aforementioned general formula (1) is an alkanediol residue, an oxanediol residue, or an aryldiol residue. The diol residue refers to a group obtained by removing a hydrogen atom from a hydroxyl group.

Among the above-mentioned alkanediol residues, those having 2 to 12 carbon atoms are preferable from the viewpoint that the effects of the present invention are more easily exhibited, and examples thereof include ethylene glycol and 1,2-propanediol. , 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-butane Ethyl-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-hexanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10-decanediol Residues such as diol and 1,12-dodecanediol may be used alone or in combination of two or more. Among these, from From the viewpoint of an ester resin having better compatibility when mixed with a cellulose ester resin described later, it is preferable that the number of carbon atoms not including branches between OH groups is 3 or less, among which ethylene glycol, 1, Residues of 2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 2-methyl-1,3-propanediol, and neopentyl glycol are preferred, and the Residues of ethylene glycol and 1,2-propanediol are more preferable.

Among the above-mentioned oxyalkanediol residues, oxyalkanediol residues having 4 to 12 carbon atoms are preferable from the viewpoint that the effects of the present invention are more easily exhibited, for example, diethylene glycol, triethyl Residues such as diol, tetraethylene glycol, dipropylene glycol, and tripropylene glycol may be used alone or in combination of two or more.

Among the above-mentioned aryl diol residues, those having 6 to 18 carbon atoms are preferable from the viewpoint that the effects of the present invention are more easily exhibited, and examples thereof include hydroquinone and resorcinol. , Residues of bisphenol A, alkylene oxide adduct of bisphenol A, bisphenol F, alkylene oxide adduct of bisphenol F, biphenol, alkylene oxide adduct of biphenol, etc. , and two or more types may be combined.

In addition, A in the aforementioned general formula (1) is an alkylene dicarboxylic acid residue (A1) or an aryl dicarboxylic acid residue (A2). Here, the dicarboxylic acid residue refers to a group obtained by removing -OH in a carboxyl group.

Regarding the aforementioned alkylene dicarboxylic acid residue (A1), the alkylene dicarboxylic acid residue having 2 to 12 carbon atoms is preferable from the viewpoint of more easily exhibiting the effects of the present invention, for example: Residues of oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, fumaric acid, 1,2-dicarboxycyclohexane, 1,2-dicarboxycyclohexene, etc., alone, Two or more types may be combined. Among them, the residues of succinic acid, adipic acid, and 1,2-dicarboxycyclohexane are preferred, and the residues of adipic acid are preferred because an optical film with better moisture permeability resistance can be obtained. for the best.

As said aryl dicarboxylic acid residue (A2), phthalic acid, terephthalic acid, isophthalic acid, 1, 4- naphthalene dicarboxylic acid, 2, 3- naphthalene dicarboxylic acid are mentioned, for example. Residues such as carboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, and 1,8-naphthalenedicarboxylic acid may be used alone or in combination of two or more. Among them, the residues of phthalic acid, terephthalic acid, and isophthalic acid are preferable, and the residues of phthalic acid are the most preferable, because optical films with higher strength can be obtained.

In order to take into account the moisture permeability resistance and storage stability of the effect of the present invention, A in the aforementioned general formula (1) is in the alkylene dicarboxylic acid residue (A1) and the aryl dicarboxylic acid residue (A2). In the total number of moles (A1+A2), the content of aryl dicarboxylic acid residues (A2) must be 70~100 mole%, preferably 75~100 mole%, and the best is 90~ 100 mol%.

For the purposes of the present invention, it is an ester resin represented by the aforementioned general formula (1), which may be a mixture of compounds in which B, G, and A are the same, but only differ in n (ie, the number of repetitions), or , and may be a mixture of compounds in which B, G, A, and n in the general formula (1) are different, respectively.

Incidentally, the GPC measurement in the present invention was carried out under the following conditions.

[GPC measurement conditions]

Measuring device: High-speed GPC device "HLC-8320GPC" manufactured by TOSOH Co., Ltd.

Column: "TSK GURDCOLUMN SuperHZ-L" made by TOSOH Co., Ltd. + "TSK gel SuperHZM-M" made by TOSOH Co., Ltd. + "TSK gel SuperHZM-M" made by TOSOH Co., Ltd. + "TSK gel made by TOSOH Co., Ltd." SuperHZ-2000" + TOSOH Co., Ltd. "TSK gel SuperHZ-2000"

Detector: RI (differential refractometer)

Data processing: "EcoSEC Data Analysis Version 1.07" manufactured by TOSOH Co., Ltd.

Column temperature: 40℃

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 with a microfilter was used as a measurement sample.

Sample injection volume: 20μl

Standard sample: The following monodisperse polystyrene having a known molecular weight was used according to the measurement manual of the aforementioned "HLC-8320GPC".

(monodisperse polystyrene)

"A-300" manufactured by TOSOH Co., Ltd.

"A-500" manufactured by TOSOH Co., Ltd.

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

"A-2500" manufactured by TOSOH Co., Ltd.

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

"F-1" manufactured by TOSOH Co., Ltd.

"F-2" manufactured by TOSOH Co., Ltd.

"F-4" manufactured by TOSOH Co., Ltd.

"F-10" manufactured by TOSOH Co., Ltd.

"F-20" manufactured by TOSOH Co., Ltd.

"F-40" manufactured by TOSOH Co., Ltd.

"F-80" manufactured by TOSOH Co., Ltd.

"F-128" manufactured by TOSOH Co., Ltd.

"F-288" manufactured by TOSOH Co., Ltd.

From the viewpoint that the effect of the present invention will be further exhibited, in the general formula (1), it is preferable that B is an aliphatic monoalcohol residue having 6 to 12 carbon atoms, and G is an alkanediol having 2 to 12 carbon atoms. Residue, oxanediol residue with carbon number 4~12 or aryldiol residue with carbon number 6~18, the alkylene dicarboxylic acid residue (A1) in A is carbon number 2~12 The alkylene dicarboxylic acid residue in A, the aryl dicarboxylic acid residue (A2) in A is an aryl dicarboxylic acid residue with a carbon number of 6 to 12; it is particularly preferable that B is a nonanol residue or an isononanol residue, G is a residue of ethylene glycol and 1,2-propanediol, A1 is a residue of adipic acid, and A2 is a residue of phthalic acid.

Moreover, the ester resin of the present invention has a number average molecular weight in the range of 350 to 1,000, particularly preferably in the range of 400 to 800, from the viewpoint of achieving compatibility with compatibility and film properties. In addition, the average value of the number of repetitions n in the aforementioned general formula (1) is also preferably in the range of 0.2 to 3 from the viewpoint of achieving both compatibility and film properties. In addition, the average value of this number average molecular weight and n is also the value measured by the said GPC measurement.

Furthermore, from the viewpoint of better compatibility with the cellulose ester resin, the acid value of the ester resin of the present invention is preferably 5 or less, more preferably 1 or less. Moreover, from the same viewpoint, the hydroxyl value of the ester resin is preferably 50 or less, more preferably 20 or less.

The ester resin of the present invention can be produced, for example, by subjecting the aforementioned raw materials to an esterification reaction in the temperature range of, for example, 180 to 250° C. for 10 to 25 hours in the presence of an esterification catalyst as required. In addition, conditions, such as temperature and time of an esterification reaction, are not specifically limited, What is necessary is just to set suitably. For the dicarboxylic acid, an acid itself may be used as a raw material, or its ester product, acid chloride, anhydride, or the like may be used as a raw material.

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

The usage-amount of the said esterification catalyst can be set suitably, Usually, it is preferable to use it in the range of 0.001-0.1 mass part with respect to the total amount of 100 mass parts of raw materials.

The properties of the ester resin of the present invention vary depending on important factors such as the number average molecular weight and the combination of raw materials, but are usually liquid, solid, paste, etc. at room temperature.

A more specific method for producing an ester resin includes a compound having a carboxyl group at the terminal obtained by using the aforementioned alkanediols, oxanediols, or aryldiols, and dicarboxylic acids, and mixing the compounds with aliphatic acids. A method for carrying out the reaction of a group of monoalcohols. Here, the aforementioned alkanediols, oxanediols or aryldiols, dicarboxylic acids and monoalcohols can be fed into the reaction system at one time, and the reaction can be made; After the compound having a carboxyl group at the end obtained from the diol, oxyalkylene diol or aryl diol and dicarboxylic acid, the monoalcohol is fed into the reaction system for successive reactions.

The ester resin obtained above can be used as it is as the ester resin of the present invention, or, for example, a thin-film distillation apparatus can be used. The content rate of n=0 components and the content rate of high molecular weight components are adjusted by methods such as distillation method, column adsorption method, solvent separation and extraction method, etc.

The ester resin of the present invention obtained by such a method or the like can be blended into a cellulose ester resin, and the obtained film can be made into a film having a good balance of moisture permeability resistance and storage stability, and can be used as a so-called so-called It is especially suitable for use as an optical film.

The blending amount of the ester resin of the present invention with respect to the cellulose ester resin may be determined according to the intended performance (moisture permeability resistance, storage stability, transparency, etc.), for example, relative to 100 parts by mass of fibers The plain ester resin is in the range of 0.1 to 50 parts by mass, preferably in the range of 1 to 30 parts by mass, and particularly preferably in the range of 5 to 20 parts by mass.

As the cellulose ester resin, for example, a part or all of the hydroxyl groups which can be obtained from cellulose such as cotton linter, wood pulp, kenaf and the like are esterified and the like is exemplified.

The aforementioned cellulose ester resins include, for example, cellulose acetate, cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate phthalate, cellulose nitrate, and the like; as a protective film for polarizing plates In the case of use, it is preferable to use cellulose acetate because a film having excellent mechanical properties and transparency can be obtained. These cellulose ester resins may be used alone or in combination of two or more.

In the aforementioned cellulose acetate, the degree of polymerization is preferably in the range of 250 to 400, and the degree of acetylation is preferably in the range of 54.0 to 62.5 mass %, more preferably in the range of 58.0 to 62.5 mass %. When the degree of polymerization and the degree of acetylation of the aforementioned cellulose acetate are in such ranges, it is possible to obtain Film with excellent mechanical properties. In the present invention, it is more preferable to use so-called cellulose triacetate. In addition, the degree of acetylation referred to in the present invention is the mass ratio of acetic acid produced by saponifying the cellulose acetate with respect to the total amount of cellulose acetate.

The number average molecular weight of the aforementioned cellulose acetate is preferably in the range of 70,000 to 300,000, more preferably in the range of 80,000 to 200,000. When the number average molecular weight of the aforementioned cellulose acetate is within this range, a film having excellent mechanical properties can be easily obtained.

In the optical film of the present invention, a cellulose ester resin composition containing the ester resin of the present invention and a cellulose ester resin is used, and a resin composition containing other various additives and the like may be used as required.

In order to obtain the optical film of the present invention, methods such as extrusion molding and casting molding can be used, for example. Specifically, an 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 aforementioned ester resin, cellulose ester resin, and other additives in advance can also be used. It is melted and kneaded, and directly extruded.

The aforementioned additives include, for example, modifiers other than the ester resin of the present invention, thermoplastic resins, ultraviolet absorbers, matting agents, anti-deterioration agents (for example, antioxidants, peroxide decomposers, radical inhibitors) agents, metal deactivators, acid scavengers, etc.), dyes, etc.

As for the aforementioned other modifiers, within the range that does not impair the effects of the present invention, ester resins other than the ester resins specified in the present invention, triphenyl phosphate (TPP), tricresyl phosphate (tricresyl phosphate) can be used. ), phosphates such as cresyl diphenyl phosphate, benzene such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate, and di-2-ethylhexyl phthalate Diformate, ethyl phthalyl ethyl glycollate, butyl butyl phthalate, trimethylolpropane tribenzoate, neopentyl Tetraol tetraacetate, acetyl tributyl citrate, etc.

The thermoplastic resin is not particularly limited, and examples thereof include polyester resins other than the ester resin of the present invention, polyester ether resins, acrylic resins, urethane resins, epoxy resins, and tosylamide. resin, etc.

The ultraviolet absorber is not particularly limited, and examples thereof include oxybenzophenone-based compounds, benzotriazole-based compounds, salicylate-based compounds, benzophenone compounds, and cyanoacrylates. series compounds, nickel zirconium salt series compounds, etc. 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 aforementioned matting agents 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 matting agent in the range of 0.1-0.3 mass part with respect to 100 mass parts of said cellulose ester resins.

As for the above-mentioned dyestuffs, the types and blending amounts are not particularly limited as long as they are within a range that does not inhibit the purpose of the present invention.

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

According to the aforementioned solution casting method, the orientation of the aforementioned cellulose ester resin in the film can be suppressed in the middle of forming, so that the obtained film can substantially exhibit optical isotropy. The above-mentioned film exhibiting optical isotropy can be used for optical materials such as liquid crystal displays, and among them, it is useful as a protective film for polarizing plates. In addition, the thin film obtained by the above-mentioned method is less likely to form irregularities on the surface, and is also excellent in surface smoothness.

The aforementioned solution casting method usually consists of the following steps: the first step is to dissolve the aforementioned cellulose ester resin composition in an organic solvent, and to cast the obtained resin solution on a metal support; The organic solvent contained in the cast resin solution is distilled off and dried to form a thin film; and, following the third step, the thin film formed on the metal support is peeled off from the metal support and dried by heating.

The metal support used in the above-mentioned first step can be exemplified by a ring-shaped or drum-shaped metal support, for example, a stainless steel and a mirror-finished surface can be used.

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

The drying method of the second step is not particularly limited, but for example, the above-mentioned casted metal can be blown by blowing the wind in the temperature range of 30 to 50°C on the top surface and/or the bottom surface of the metal support body. A method of forming a thin film on the aforementioned metal support by evaporating 50 to 80% by mass of the organic solvent contained in the resin solution.

Next, the third step is a step of peeling the thin film formed in the second step from the metal support, and heating and drying it at a temperature higher than that of the second step. As for the above-mentioned heating and drying method, for example, a method of increasing the temperature stepwise under the temperature condition of 100 to 160° C. is preferable because good dimensional stability can be obtained. The organic solvent remaining in the thin film after the second step can be substantially completely removed by heating and drying under the aforementioned temperature conditions.

In addition, in the above-mentioned 1st step - 3rd step, the organic solvent can also be recovered and reused.

The organic solvent that can be used when the resin composition is mixed and dissolved in an organic solvent is not particularly limited as long as it can dissolve these organic solvents. For example, when cellulose acetate is used as the cellulose ester, it is an excellent As a solvent, for example, it is preferable to use organic halogen compounds such as dichloromethane or dioxolanes.

In addition, together with the aforementioned excellent solvent, a poor solvent such as methanol, ethanol, 2-propanol, n-butanol, cyclohexane, cyclohexanone, etc. is used in combination, which is more effective in improving the production efficiency of the film. good.

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

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

In the present invention, for example, the optical film in an unstretched state obtained by the aforementioned method is uniaxially stretched in the longitudinal direction in the direction of machine travel and transversely stretched in the direction perpendicular to the direction of machine travel, as required. A stretched optical film can be obtained by uniaxial stretching. In addition, stretching is performed 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, and the like. stretched, a biaxially stretched stretched film can be obtained. 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 in this range, a stretched optical film that is preferable in terms of birefringence, heat resistance, and strength can be obtained.

The optical film of the present invention is excellent in moisture permeability resistance, transparency, and storage stability, and thus can be used for, for example, an optical film of a liquid crystal display device. The optical films of the liquid crystal display device include, for example, protective films for polarizing plates, retardation films, reflective films, viewing angle enhancement films, antiglare films, non-reflective films, antistatic films, color filters, etc. , among these, it can also be preferably used as a protective film for polarizing plates.

The 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 the aforementioned optical film is used as a protective film for polarizers In some cases, a film thickness in the range of 25 to 80 μm is suitable when trying to reduce the thickness of a liquid crystal display device, and can maintain excellent performances such as sufficient film strength, Rth stability, and moisture permeability resistance.

The optical film of the present invention is characterized in that the storage stability thereof is improved compared to the case where the ester resin is not blended. It is known that hydrolysis of cellulose ester resins generally proceeds in a moist heat environment. In order to suppress this, it is necessary to use an additive for improving the moisture permeability resistance. For ester resins other than the ester resin of the present invention, the ester resin itself may be hydrolyzed, and carboxyl groups such as acetic acid may be generated. The acid promotes the hydrolysis of the cellulose ester resin. Therefore, suppression of the hydrolysis resistance of the ester resin used as an additive leads to improvement of the storage stability in the obtained cellulose ester film.

Moreover, since the said optical film does not generate|occur|produce bleeding (bleeding) under high temperature and high humidity, and can also adjust to a desired Rth, it can be used for various liquid crystal display systems in a wide range according to an application.

Examples of the liquid crystal display system include: IPS (In-Plane Switching), TN (Twisted Nematic), VA (Vertically Aligned), and OCB (Optically Compensated Bending). Type: Optically Compensatory Bend) and so on.

The optical film according to the present invention can be suitably used as an optical material for: polarizer protective films, quarter wave plates used in displays such as liquid crystal displays, plasma displays, organic EL displays, field emission displays, rear projection televisions, etc. , 1/2 wavelength plate, viewing angle control film, liquid crystal optical compensation film and other retardation films, display front panel, etc. again, In addition to this, the resin composition of the present invention can also be used in the fields of optical communication systems, optical switching systems, and optical measurement systems for waveguides, lenses, optical fibers, substrates for optical fibers, coating materials, lenses for LEDs, and lens covers Wait.

[Example]

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

Example 1

In a 2-liter, 3-neck flask, 158 g of 90% neopentyl glycol (hereinafter referred to as "NPG") as the diol component, 422 g of phthalic anhydride (hereinafter referred to as "PA") as the dicarboxylic acid component, and 410 g of isophthalic Nonanol (hereinafter abbreviated as "INA") as an alcohol component and 0.056 g of tetraisopropyl titanate (hereinafter abbreviated as "TIPT") as a catalyst were heated to 220°C in steps under nitrogen flow through a nitrogen introduction pipe. The condensation reaction was performed at 220° C. for 8 hours, and it was confirmed that the acid value became 1.0 or less. The ester resin (1) of the present invention was obtained by removing excess diol at 200°C under reduced pressure. The obtained ester resin (1) was a pale yellow liquid at normal temperature, the acid value was 0.2, and the number average molecular weight was 520.

Example 2

In a 2-liter, 3-necked flask, 107.6 g of propylene glycol (hereinafter referred to as "PG") was charged as the diol component, 362 g of PA as the dicarboxylic acid component, 412 g of INA as the alcohol component, and 0.062 g of TIPT as the catalyst. The nitrogen introduction pipe was heated to 220° C. in steps under nitrogen flow. The condensation reaction was performed at 220° C. for 8 hours, and it was confirmed that the acid value became 1.0 or less. exist The ester resin (2) of the present invention was obtained by removing excess diol at 200°C under reduced pressure. The obtained ester resin (2) was a pale yellow liquid at normal temperature, the acid value was 0.2, and the number average molecular weight was 560.

Synthesis Example 1 of Ester Resin for Comparative Control

In a 2-liter 3-necked flask, 383g of PG as a diol component, 381g of adipic acid (hereinafter referred to as AA), 129g of PA as a dicarboxylic acid component, and 0.054g of TIPT were fed through a nitrogen inlet pipe under nitrogen flow, The temperature was raised to 220°C in stages. The condensation reaction was carried out at 220° C. for 13 hours, and it was confirmed that the acid value became 1.0 or less. Under reduced pressure, excess diol was removed at 140°C, whereby an ester resin (1') for comparison was obtained. The obtained ester resin (1') was a pale yellow liquid at normal temperature, the acid value was 0.3, and the number average molecular weight was 760.

Synthesis Example 2 of Ester Resin for Comparative Control

In a 2-liter 3-necked flask, 390 g of PG was charged as the diol component, 658 g of AA, 222 g of PA as the dicarboxylic acid component, 253 g of n-butanol (hereinafter referred to as nBuOH) as the alcohol component, and 0.091 g of TIPT, through The nitrogen introduction pipe was heated to 220° C. in steps under nitrogen flow. The condensation reaction was carried out at 220° C. for 13 hours, and it was confirmed that the acid value became 1.0 or less. Under reduced pressure, excess diol was removed at 200°C, whereby an ester resin (2') for comparison was obtained. The obtained ester resin (2') was a pale yellow liquid at normal temperature, the acid value was 0.2, and the number average molecular weight was 1230.

Synthesis Example 3 of Ester Resin for Comparative Control

In a 2-liter 3-necked flask, 448 g of ethylene glycol (hereinafter referred to as "EG") was introduced as the diol component, 812 g of AA as the dicarboxylic acid component, and 0.038 g of TIPT, and passed through a nitrogen inlet pipe under nitrogen flow, step by step. The temperature was raised to 220°C. The condensation reaction was performed at 220° C. for 13 hours, and it was confirmed that the acid value became 1.0 or less. Under reduced pressure, excess diol was removed at 200°C, whereby an ester resin (3') for comparison was obtained. The obtained ester resin (3') was a pale yellow liquid at normal temperature, the acid value was 0.2, and the number average molecular weight was 1320.

Synthesis Example 4 of Ester Resin for Comparative Control

In a 2-liter 3-necked flask, 93 g of EG, 114 g of PG as a diol component, 601 g of adipic acid (hereinafter referred to as AA) as a dicarboxylic acid component, 415 g of INA as an alcohol component, and 0.061 g of TIPT were introduced. The nitrogen introduction pipe was heated to 220° C. in steps under nitrogen flow. The condensation reaction was carried out at 220° C. for 13 hours, and it was confirmed that the acid value became 1.0 or less. Under reduced pressure, excess diol was removed at 200°C, whereby an ester resin (4') for comparison was obtained. The obtained ester resin (4') was a pale yellow liquid at normal temperature, the acid value was 0.3, and the number average molecular weight was 1190.

<Adjustment of cellulose ester optical film>

100 parts of triacetate cellulose resin ("LT-35" manufactured by Daicel Co., Ltd.) and 10 parts of ester resin were added and dissolved in a mixed solvent composed of 810 parts of dichloromethane and 90 parts of methanol to prepare a coating liquid . The coating liquid was cast on a glass plate so as to have a thickness of 0.8 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 a thin film. and also, In Comparative Example 1, no ester resin was added, and in Comparative Example 2, a film was produced using the same amount of triphenyl phosphate instead of the ester resin. Comparative Example 3 is a commercially available triacetate cellulose film 4UY (manufactured by Konica Minolta).

<Measurement of moisture permeability>

The measurement was performed according to the method described in JIS Z 0208. The measurement conditions were carried out at a temperature of 40° C. and a relative humidity of 90%. The smaller the obtained value, the better the moisture permeability resistance. Unit: g/m ² ‧24h

<Damp heat test>

The film was exposed to an environment of 85° C. and a relative humidity of 90% (under a humid heat environment) for 120 hours.

<HAZE>

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

<Wet heat loss>

The above-mentioned wet heat test was performed on a film of 4 cm×4 cm square, and the mass before and after the test was measured, thereby obtaining the mass reduction rate (%) after the test.

<Evaluation of Storage Stability of Cellulose Ester Resin Film>

After placing 1.2 g of the film in a 30 ml sample bottle and allowing it to exist for 1000 hours under the conditions of 85°C x 90% humidity, the acetic acid generated by hydrolysis was measured using a detection tube (Kitagawa type gas detection tube for acetic acid). quantity. The smaller the amount of acetic acid produced, the better the storage stability.

It was confirmed that the amount of acetic acid generation of the film obtained from the cellulose ester resin composition was largely suppressed in the Example, compared with the Comparative Example, and the storage stability of the film was improved. In addition, it was found that the mass reduction % after the moist heat test was small, and the compatibility with the cellulose ester resin was also high. The moisture permeability is also suppressed lower than that of the comparative example, and it can be expected that the stability as a polarizing plate will be improved.

Claims (8)

A plasticizer for cellulose ester resin, characterized in that: the cellulose ester resin is an ester resin represented by the following general formula (1), and the number average molecular weight is 350-1000: B-(AG) _n -AB (1) [In formula (1), B is an aliphatic monoalcohol residue having 4 to 20 carbon atoms, and G is an alkanediol residue having 2 to 12 carbon atoms, and an oxyalkanediol residue having 4 to 12 carbon atoms. base or an aryldiol residue with a carbon number of 6-18, A is an alkylene dicarboxylic acid residue with a carbon number of 2-12 (A1) or an aryldicarboxylic acid residue with a carbon number of 6-12 (A2 ), in the total (A1+A2) of alkylene dicarboxylic acid residues (A1) and aryl dicarboxylic acid residues (A2), the content of aryl dicarboxylic acid residues (A2) is 70~ 100 mol%, n is the number of repetitions, the average value of n is 0.2~3, and in each repeating unit, G, A can be the same or different, and multiple A, B can be the same or the same. different]. The plasticizer for cellulose ester resin according to claim 1, wherein B in the aforementioned general formula (1) is an aliphatic monoalcohol residue having 6 to 12 carbon atoms. The plasticizer for cellulose ester resin according to claim 1 or 2, wherein B in the aforementioned general formula (1) is a nonanol residue or an isononanol residue, and G is selected from the group consisting of ethylene glycol, 1, 1 or more of the group consisting of 2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 2-methyl-1,3-propanediol, and neopentyl glycol A1 is one or more residues selected from the group consisting of succinic acid, adipic acid and dicarboxycyclohexane, and A2 is selected from phthalic acid, terephthalic acid and One or more residues from the group consisting of isophthalic acid. The plasticizer for cellulose ester resin according to claim 1 or 2, wherein the alkylene dicarboxylic acid residue (A1) of A in the aforementioned general formula (1) and the aryl dicarboxylic acid residue The content rate of the aryldicarboxylic acid residue (A2) is 75 to 100 mol% in the total number of moles (A1+A2) of the acid residues (A2). A cellulose ester resin composition characterized by containing the plasticizer of the cellulose ester resin according to any one of claims 1 to 4 and the cellulose ester resin. An optical film characterized by containing the cellulose ester resin composition as claimed in claim 5. Such as the optical film of claim 6, it is used for polarizing plate protection. A liquid crystal display device characterized by having the optical film as claimed in claim 6 or 7.