TWI797378B - Antiplasticizer, cellulose ester resin composition, optical film and liquid crystal display device - Google Patents

Abstract

The present invention provides 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 an anti-plasticizer for optical resins; a resin composition containing the ester resin; and a composition using the resin The obtained optical film and the liquid crystal display device using it. Specifically, using a formula with B ¹ -(G ¹ -A) _n -G ¹ -B ¹ [wherein, B ¹ is a monocarboxylic acid residue, G ¹ is an alkylene glycol residue, an alkylene oxide residue, base diol residues or aryl diol residues, A is a dicarboxylic acid residue, more than 25 moles of the total moles of A are isophthalic acid residues, n is the number of repetitions, and in each repetition G ¹ and A may be the same or different, and a plurality of B ¹ and G ¹ may be the same or different] ester resin represented by ester resin, resin composition containing it, optical film obtained by using the composition, and its use Liquid crystal display device.

Description

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

The present invention relates to ester resins, ester resin mixtures and cellulose ester resin compositions containing them, which are suitable as anti-plasticizers for resins for optical materials, optical films obtained by using the resin compositions, and liquid crystals using the same display device.

In recent years, liquid crystal displays have progressed towards thinner films, and polarizer protective films have also progressed from the previous 80 μm to 60 μm, and then to 40~25 μm. Conventionally, triacetyl cellulose resin (hereinafter referred to as TAC) is often used as a protective film of a polarizing plate from the viewpoint of easy attachment to the polarizing plate.

However, since TAC is hard and brittle, there is a problem that the strength is insufficient and breakage is likely to occur when it is formed into a film. In addition, since TAC has high moisture permeability and hygroscopicity, it is easy to cause dimensional changes due to moisture permeability and moisture absorption. Therefore, additives must be used to suppress moisture permeability and moisture absorption. Therefore, various additives have been provided (for example, refer to patent Literature 1).

Generally, when additives are added to suppress moisture transmission and moisture absorption, plasticization of the resin occurs at the same time, so it is difficult to obtain a film having both physical properties such as strength and heat resistance, and dimensional stability. Therefore, development of an additive capable of providing a film excellent in elastic modulus, heat resistance, and dimensional stability has been sought.

[Prior Art Literature] [Patent Document]

[Patent Document 1] Japanese Unexamined Patent Publication No. 2013-151699

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

The inventors of the present invention have devoted themselves to research and found that the above-mentioned problems can be solved by specifying the dicarboxylic acid component in the raw material of the ester resin, thereby completing the present invention.

That is, the present invention provides an ester resin, an ester resin mixture containing the same, an antiplasticizer containing the same, a cellulose ester resin composition, an optical film obtained by using the composition, and an optical film using the same A liquid crystal display device, wherein the ester resin is represented by the following general formula (I), B ¹ -(G ¹ -A)nG ¹ -B ¹ (I) [In the formula (1), B ¹ is a monocarboxylic acid residue ^G1 is an alkylene glycol residue, an oxyalkylene glycol residue or an aryl glycol residue, and A is a dicarboxylic acid residue, wherein A is more than 25 mole% of the total number of moles is isophthalic acid residue, n is the number of repetitions, G ¹ and A in each repetition can be the same or different, and multiple B ¹ and G ¹ can be the same or different. ].

According to the present invention, it is possible to provide an ester resin or an ester resin mixture that is excellent in balance of strength, heat resistance, and dimensional stability when processed into a film, and can be suitably used as an antiplasticizer for optical resins. In addition, by using the specific ester resin or a mixture thereof, especially in an optical film containing a cellulose ester resin, it is possible to improve the modulus of elasticity and have both heat resistance and dimensional stability without compromising transparency. Instead, it can be suitably used as an optical film used for a liquid crystal display device.

[Mode for Carrying Out the Invention]

The ester resin of the present invention is represented by the following general formula (I).

B ¹ -(G ¹ -A) _n -G ¹ -B ¹ (I)

[In formula (1), B ¹ is a monocarboxylic acid residue, G ¹ is an alkylene glycol residue, an oxyalkylene glycol residue or an aryl glycol residue, and A is a dicarboxylic acid residue , wherein more than 25 moles of the total moles of A are isophthalic acid residues, n is the number of repetitions, G ¹ and A in each repetition can be the same or different, and multiple B ¹ and G ¹ can be The same or different. ]

B ¹ in the aforementioned general formula (I) is a monocarboxylic acid residue, and specifically, an aliphatic monocarboxylic acid residue is mentioned. Here, "carboxylic acid residue" means a group other than -OH in a carboxyl group. The above-mentioned aliphatic monocarboxylic acid residues are easy to acquire moisture permeability resistance, modulus of elasticity, and optical properties from the ease of availability of raw materials and ease of esterification reaction, and when mixed with cellulose ester resin described later. From the viewpoint of the balance of carbon atoms, it is preferably an aliphatic monocarboxylic acid residue with 1 to 8 carbon atoms, for example, residues of acetic acid, propionic acid, butyric acid, hexanoic acid, octanoic acid, octyl acid, etc. , may be used alone or at the same time, especially preferably acetic acid. In addition, here, the number of carbon atoms does not include the carbon atoms in the carboxyl group.

^G in the aforementioned general formula (I) is an alkylene diol residue, an oxyalkylene glycol residue or an aryl diol residue, and the diol residue represents a group obtained by removing a hydrogen atom from a hydroxyl group .

The above-mentioned alkylene glycol residue is preferably an alkylene glycol residue having 2 to 12 carbon atoms, for example, ethylene glycol , 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-butyl-2-ethyl-1,3-propanediol (3,3-dimethylolheptane), 3-methyl-1,5-pentanediol, 1,6-hexanediol alcohol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol, 2-methyl-1,8-octanediol, 1,9- Residues such as nonanediol, 1,10-decanediol, and 1,12-dodecanediol may be present alone or in combination of two or more. Among them, from the viewpoint of being an ester resin having better compatibility when mixed with the cellulose ester resin described later, the one that does not contain branches between OH groups and has 3 or less carbon atoms is preferred. Preferably, among them, residues of ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 2-methyl-1,3-propanediol are preferred, and ethylene glycol is more preferred , 1,2-propanediol residues, most preferably 1,2-propanediol residues.

The above-mentioned oxyalkylene glycol residue is preferably an oxyalkylene glycol residue having 4 to 12 carbon atoms from the viewpoint of making it easier to exhibit the effect of the present invention, for example, diethylene glycol Residues such as diol, triethylene glycol, tetraethylene glycol, dipropylene glycol, and tripropylene glycol may be used alone or in combination of two or more.

The above-mentioned aryl diol residue is preferably an aryl diol residue having 6 to 18 carbon atoms, for example, hydroquinone, resorcinol, Residues of diphenol, bisphenol A, alkylene oxide adducts of bisphenol A, bisphenol F, alkylene oxide adducts of bisphenol F, biphenol, alkylene oxide adducts of biphenol, etc., The system may be used alone or in combination of two or more.

Also, A in the aforementioned general formula (I) is a dicarboxylic acid residue, specifically, an alkylene dicarboxylic acid residue (A1) or an aryl dicarboxylic acid residue (A2), the total of A The number of moles of isophthalic acid residues in the number of moles must be 25 mole % or more. Here, the dicarboxylic acid residue refers to a group obtained by removing -OH in the carboxyl group.

In the above-mentioned ester resin represented by the general formula (I), by using a large amount of isophthalic acid as a dicarboxylic acid as a raw material, the optical resin, especially cellulose, will not be mixed with the optical resin described later. Ester resin is plasticized, and when it is processed into a film, it can increase the modulus of elasticity and impart heat resistance without compromising the original transparency of the optical resin, making it suitable for optical film applications that are developing toward thinning .

From the viewpoint of exhibiting the aforementioned effects, the molar number of isophthalic acid residues in dicarboxylic acid residues must be 25 mole % or more. The residue content is preferably in the range of 25 to 100 mol%, more preferably in the range of 40 to 100%, most preferably in the range of 70 to 90%.

The above-mentioned alkylene dicarboxylic acid residue (A1) which may be present at the same time as the isophthalic acid residue is preferably one having 2 to 12 carbon atoms, from the viewpoint that the effects of the present invention are more likely to be exhibited. Alkylene dicarboxylic acid residues, for example, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, fumaric acid, 1,2-dicarboxy Residues such as cyclohexane and 1,2-dicarboxycyclohexene may be used alone or in combination of two or more. Among these, residues of succinic acid, adipic acid, and 1,2-dicarboxycyclohexane are preferred from the viewpoint of obtaining an optical film with more excellent film transparency, and hexane diacid residues.

As the above-mentioned aryl dicarboxylic acid residue (A2) that may be present at the same time as the isophthalic acid residue, for example, phthalic acid, terephthalic acid, 1,4-naphthalene dicarboxylic acid, 2,3 - Residues of naphthalene dicarboxylic acid, 2,6-naphthalene dicarboxylic acid, 2,7-naphthalene dicarboxylic acid, 1,8-naphthalene dicarboxylic acid, etc. may be present alone or in combination of two or more. Among them, residues of phthalic acid and terephthalic acid are preferable, and residues of phthalic acid are most preferable from the viewpoint of obtaining an optical film with higher strength.

In the present invention, the above-mentioned ester resin represented by the general formula (I) may be a mixture of compounds whose B ¹ , G ¹ , and A are identical and differ only in n, that is, the number of repetitions, or may be a compound of the general formula ( B ¹ , G ¹ , A and n in I) are mixtures of different compounds.

From the point of view of further demonstrating the effect of the present invention, in general formula (I), preferably, B ¹ is a residue of acetic acid, propionic acid, octanoic acid, G ¹ is ethylene glycol, 1,2-propylene glycol, 1 , 3-propanediol, 1,2-butanediol, 2-methyl-1,3-propanediol residues, the A1 that can be possessed at the same time is succinic acid, adipic acid, 1,2-dicarboxycyclohexane A2 is the residue of phthalic acid and terephthalic acid, especially the best series ^B1 is the residue of acetic acid, and ^G1 is the residue of ethylene glycol and 1,2-propanediol, which can have both The A1 is the residue of adipic acid, and A2 is the residue of phthalic acid.

In the present invention, in the optical film obtained by mixing the resin for optical materials described later, especially cellulose ester resin, in order to reduce the non-volatile components in the film production process and obtain an optical film excellent in moisture absorption dimensional stability , it is desired to reduce the amount of residual diol in the ester resin represented by the aforementioned general formula (I) by distillation or the like. The amount of residual diol in the ester resin is preferably at most 1.5% by mass, most preferably at most 1.0% by mass. In addition, the above-mentioned remaining diol amount can be measured by gas chromatography.

Also, regarding the ester resin of the present invention, from the viewpoint of both compatibility and film physical properties, its number average molecular weight is preferably in the range of 350-2000, particularly preferably in the range of 400-1500, most preferably in the range of 500 ~1200 range. Also, from the viewpoint of both compatibility and film physical properties, the average value of the number of repetitions n in the aforementioned general formula (I) is preferably in the range of 1.0 to 10.0, more preferably 1.0 to 8.0 The range is preferably 1.5 to 7.0. 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 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 SuperHZ-2000" + "TSK gel SuperHZ-2000" manufactured by TOSOH Co., Ltd. Detector: RI (Differential Refractometer) Data processing: "EcoSEC Data Analysis version 1.07" manufactured by TOSOH Co., Ltd. Column temperature: 40°C Developing solvent: tetrahydrofuran Flow rate: 0.35mL/min Measurement sample: 7.5 mg of a sample was dissolved in 10 ml of tetrahydrofuran, and the obtained solution was filtered with a microfilter, and this was used as a measurement sample. Sample injection volume: 20μl Standard sample: According to the measurement manual of the aforementioned "HLC-8320GPC", the following monodisperse polystyrene whose molecular weight is known is used.

(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. Made by TOSOH Co., Ltd. "F-1" Made by TOSOH Co., Ltd. "F-2" "F-4" made by TOSOH Co., Ltd. "F-10" made 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.

Furthermore, 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 can be produced, for example, by subjecting the aforementioned raw materials to an esterification reaction at a temperature range of 180 to 250° C. for 10 to 25 hours in the presence of an esterification catalyst as needed. In addition, conditions such as temperature and time of the esterification reaction are not particularly limited, and can be appropriately set. As for the monocarboxylic acid and the dicarboxylic acid, the acid itself can be used as a raw material, or its esterified product, an acid chloride, an anhydride of a dicarboxylic acid, or the like can be used as a raw material.

As for the aforementioned esterification catalyst, for example, titanium-based catalysts such as tetraisopropyl titanate and tetrabutyl titanate; tin-based catalysts such as dibutyltin oxide; organic sulfonic acid-based catalysts such as p-toluenesulfonic acid; Media etc.

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

The properties of the ester resin of the present invention vary with 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 ester resins includes a method in which a compound having a hydroxyl group at the end reacts with a monocarboxylic acid, wherein the compound having a hydroxyl group at the end uses the above-mentioned alkylene glycol, oxyalkylene diol, etc. Alcohol or aryl diol and dicarboxylic acid obtained. Here, the aforementioned alkylene glycol, oxyalkylene glycol or aryl glycol, and dicarboxylic acid and monocarboxylic acid can be added to the reaction system at one time and then allowed to react; or it can be obtained After using alkylene diol, oxyalkylene diol or aryl diol and dicarboxylic acid to obtain a compound having a hydroxyl group at the end, the monocarboxylic acid is further added to the reaction system for successive reactions.

In the present invention, the aforementioned ester resin may be used alone, and may be added to resins for optical materials such as cellulose ester resin described later, or a diester compound represented by the following general formula (II) may be used in combination. B ² -G ² -B ² (II) [In formula (II), B ² is an aryl monocarboxylic acid residue or an aliphatic monocarboxylic acid residue, G ² is an alkylene glycol residue, an oxygen extension Alkyl diol residues or aryl diol residues, a plurality of B ² may be the same or different. ]

^B2 in the aforementioned general formula (II) is a monocarboxylic acid residue, specifically, an aryl monocarboxylic acid residue or an aliphatic monocarboxylic acid residue. Here, the "carboxylic acid residue" means a group other than -OH in a carboxyl group. Regarding the aforementioned aryl monocarboxylic acid residue, it is easy to obtain moisture permeability resistance, elastic modulus, and dimensional stability from the ease of availability of raw materials, ease of esterification reaction, and ease of mixing with cellulose ester resin described later. In view of the balance of properties, it is preferably an aryl monocarboxylic acid residue having 6 to 12 carbon atoms, for example, benzoic acid, dimethylbenzoic acid, trimethylbenzoic acid, tetramethylbenzoic acid , ethylbenzoic acid, propylbenzoic acid, butylbenzoic acid, p-isopropylbenzoic acid, p-tertiary butylbenzoic acid, o-toluic acid, m-toluic acid, p-toluic acid, ethoxybenzoic acid, propyl Oxybenzoic acid, p-methoxybenzoic acid, naphthoic acid, etc. may be used alone or in combination of two or more. In particular, residues of benzoic acid, p-toluic acid, and dimethylbenzoic acid are preferable, and residues of benzoic acid and p-toluic acid are more preferable from the viewpoint of easier expression of the effects of the present invention. Also, here, the number of carbon atoms does not include carbon atoms in carboxyl groups. In addition, it may be a residue of aromatic niacin, furoic acid, etc., which may have a substituent.

Regarding the aforementioned aliphatic monocarboxylic acid residues, it is easy to obtain moisture permeability resistance, elastic modulus, and dimensional stability from the ease of availability of raw materials and ease of esterification reaction, and when mixed with cellulose ester resin described later. From the viewpoint of the balance of properties, it is preferably an aliphatic monocarboxylic acid residue having 1 to 8 carbon atoms, for example, residues of acetic acid, propionic acid, butyric acid, hexanoic acid, octanoic acid, octyl acid, etc. The bases may be used alone or in combination, and acetic acid is particularly preferred. Also, here, the number of carbon atoms does not include carbon atoms in carboxyl groups.

^G2 in the aforementioned general formula (II) is an alkylene glycol residue, an oxyalkylene glycol residue or an aryl glycol residue. The diol residue means a group obtained by removing a hydrogen atom from a hydroxyl group.

The above-mentioned alkylene glycol residue is preferably an alkylene glycol residue having 2 to 12 carbon atoms, for example, ethylene glycol , 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-butyl-2-ethyl-1,3-propanediol (3,3-dimethylolheptane), 3-methyl-1,5-pentanediol, 1,6-hexanediol alcohol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol, 2-methyl-1,8-octanediol, 1,9- Residues such as nonanediol, 1,10-decanediol, and 1,12-dodecanediol may be present alone or in combination of two or more. Among these, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, and 1,3-butanediol are preferable from the viewpoint of improving the strength of the film. Residues of alcohols, 2-methyl-1,3-propanediol, 1,5-pentanediol.

The above-mentioned oxyalkylene glycol residue is preferably an oxyalkylene glycol residue having 4 to 12 carbon atoms from the viewpoint of making it easier to exhibit the effect of the present invention, for example, diethylene glycol Residues such as diol, triethylene glycol, tetraethylene glycol, dipropylene glycol, and tripropylene glycol may be used alone or in combination of two or more.

The above-mentioned aryl diol residue is preferably an aryl diol residue having 6 to 18 carbon atoms, for example, hydroquinone, resorcinol, Residues of diphenol, bisphenol A, alkylene oxide adducts of bisphenol A, bisphenol F, alkylene oxide adducts of bisphenol F, biphenol, alkylene oxide adducts of biphenol, etc., The system may be used alone or in combination of two or more.

From the point of view of further demonstrating the effect of the present invention, in the general formula (II), preferably, B ² is a residue of benzoic acid or p-toluic acid, and G ² is ethylene glycol, 1,2-propanediol, 1 ,3-propanediol, 2-methyl-1,3-propanediol, diethylene glycol, dipropylene glycol residues.

The aforementioned diester compound (II) can be a synthetic compound or a commercially available compound. During synthesis, the reaction conditions (catalyst, temperature, time, etc.) can be, for example, the ester resin (I) used in the present invention. conditions used in the synthesis.

The ester resin mixture of the present invention is preferably in the range of 100/0 to 50/50 in the mass ratio [ester resin/diester compound] from the viewpoint of being suitably used as an anti-plasticizer for optical resins described later. Contains the aforementioned ester resin (I) and diester compound (II).

If such a diester compound (II) is contained, it can be preferably placed in the gaps of resins for optical materials, especially cellulose ester resins, and as a result, the effect of improving moisture permeability resistance, elastic modulus, and dimensional stability can be further exhibited , while ensuring compatibility with resins for optical materials, it is possible to more effectively maintain the transparency that can be used as an optical film.

From the point of view of further exhibiting these effects, and being easy to suppress contamination of the production line due to volatilization, or maintain the transparency of optical films, etc., the ester in the total mass of the above-mentioned ester resin (I) and diester compound (II) The ratio of the resin (I) is preferably from 50 to 100% by mass, more preferably from 60 to 95% by mass, most preferably from 65 to 90% by mass.

The ester resin mixture of the present invention may be composed only of the aforementioned ester resin (I) and diester compound (II), or may contain polyesters other than the ester resin (I) and diesters other than the diester compound (II). compound. In addition, modifiers other than ester resin (I) and diester compound (II) known as so-called optical resins may be contained, and those used in the production of ester resin (I) and diester compound (II) may also be contained. Unreacted substances of raw materials.

The ester resin or ester resin mixture of the present invention obtained by such a method etc. can be blended into the resin for optical materials, so that the obtained film can have elastic modulus, heat resistance, and dimensional stability. Those with excellent balance can be used as so-called anti-plasticizers, and the obtained films are particularly suitable as optical films.

The aforementioned resin for optical materials is not particularly limited as long as it is highly transparent and can be processed into a film, and examples include (meth)acrylic resins, cyclic olefin resins, polycarbonate resins, fiber Ester resin, etc. In particular, it is preferable to use a cellulose ester resin from the viewpoint of further expressing the effects of the present invention.

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

As the said cellulose ester resin, the thing which esterified some or all of the hydroxyl groups which the cellulose which obtained from cotton linters, wood pulp, kenaf, etc. have, etc. can be illustrated, for example.

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

As for the above-mentioned cellulose acetate, the degree of polymerization is preferably in the range of 250 to 400, and the degree of esterification is preferably in the range of 54.0 to 62.5% by mass, more preferably in the range of 58.0 to 62.5% by mass. When the degree of polymerization and the degree of esterification of the cellulose acetate are within this range, a film having excellent mechanical properties can be obtained. In the present invention, it is more preferable to use so-called cellulose triacetate. In addition, the degree of esterification referred to in the present invention refers to the mass ratio of acetic acid produced by saponification of the cellulose acetate relative to the total amount of the cellulose acetate.

The number average molecular weight of the said cellulose acetate becomes like this. Preferably it is the range of 70,000-300,000, More preferably, it is the range of 80,000-200,000. When the number average molecular weight of the aforementioned cellulose acetate falls within this range, a film having excellent mechanical properties can be easily obtained.

The optical film of 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 cellulose ester resin, and may optionally use a resin composition containing other various additives.

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, for example, the optical film in an unstretched state can be extruded using 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 mixing resins for optical materials such as the aforementioned ester resins, ester resin mixtures, cellulose ester resins, and other additives in advance can be used. It can also be melt-mixed and directly extruded during extrusion molding.

Examples of the aforementioned additives include ester resins of the present invention, modifiers other than diester compounds, thermoplastic resins, ultraviolet absorbers, matting agents, stabilizers, deterioration inhibitors (such as antioxidants, peroxides, etc.) Decomposers, free radical inhibitors, metal deactivators, acid scavengers, etc.), dyes, etc.

For the aforementioned other modifying agents, ester resins defined in the present invention, ester resins other than diester compounds, triphenyl phosphate (TPP), triphenyl phosphate (TPP), Tricresol phosphate, cresol diphenyl phosphate and other phosphates; phthalates such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate and other phthalates; ethyl Phthaloyl ethyl glycolate, butyl phthaloyl butyl glycolate, trimethylolpropane tribenzoate, neopentylitol tetraacetate, acetyl tributyl citrate, etc.

The aforementioned thermoplastic resins are not particularly limited, and examples thereof include polyester resins, polyester ether resins, polyurethane resins, acrylic resins, epoxy resins, toluenesulfonyl resins other than the ester resins of the present invention, Amine resin, etc.

The aforementioned ultraviolet absorbers are not particularly limited, and examples include oxybenzotriazole-based compounds, benzotriazole-based compounds, salicylate-based compounds, benzophenone-based compounds, cyanoacrylate-based compounds, nickel zirconium salt 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 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 matting agent in the range of 0.1-0.3 mass parts with respect to 100 mass parts of said cellulose ester resins.

As said stabilizer, calcium hydroxide, calcium carbonate, fatty acid metal salt, etc. are mentioned, for example. 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 aforementioned dyes are not particularly limited in their type, blending amount, and the like as long as they do not hinder the object of the present invention.

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

According to the above-mentioned solution casting method, the alignment of the above-mentioned optical material resin such as cellulose ester resin in the film during molding can be suppressed, so the obtained film can exhibit substantially optical isotropy. The above-mentioned thin film exhibiting optical isotropy can be used, for example, in optical materials such as liquid crystal displays, and is especially useful as a protective film for polarizing plates. In addition, the film obtained by the aforementioned method is less likely to have irregularities on the surface, and is also considerably excellent in surface smoothness.

The above-mentioned solution casting method generally includes: dissolving the above-mentioned resin composition in an organic solvent and casting the obtained resin solution on a metal support in the first step; The second step of forming a thin film by distilling off the solvent and drying, and then the third step of peeling the thin film formed on the metal support from the metal support and performing heat drying.

As the metal support used in the first step, an endless belt-shaped or roller-shaped metal support can be exemplified, and for example, a stainless steel support with a mirror-polished surface can be used.

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

The drying method of the aforementioned second step is not particularly limited, and examples include: blowing the wind in the temperature range of, for example, 30 to 50° C. on the top and/or bottom of the aforementioned metal support to make the casting A method of forming a thin film on the 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 drying it by heating at a temperature higher than that in the second step. In order to obtain good dimensional stability, the above-mentioned heating and drying method is preferably a method of gradually increasing the temperature step under the temperature condition of 100 to 160° C., for example. By heating and drying under the aforementioned temperature conditions, it is possible to almost completely remove the organic solvent remaining in the thin film after the aforementioned second step.

Also, in the aforementioned first step to third step, the organic solvent can also be recovered and reused.

The organic solvent that can be used when mixing and dissolving the aforementioned 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 In this case, it is preferable to use organic halogen compounds such as dichloromethane and dioxolanes as good solvents.

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

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

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

In the present invention, for example, the optical film in the unstretched state obtained by the aforementioned method can be uniaxially stretched longitudinally in the direction of mechanical flow and transversely uniaxially stretched in the direction perpendicular to the direction of mechanical flow. , to obtain a stretched optical film. In addition, stretching can be performed by a sequential biaxial stretching method using roll stretching and tenter stretching, a simultaneous biaxial stretching method utilizing tenter stretching, a biaxial stretching method utilizing tubular stretching, etc. stretched to obtain a biaxially stretched stretched film. The draw ratio is preferably from 0.1% to 300% in at least one direction, more preferably from 0.2% to 250%, most preferably from 0.3% to 200%. By designing within this range, it is possible to obtain a stretched optical film which is preferable from the viewpoint of birefringence, heat resistance, and strength.

The optical film of the present invention is excellent in elastic modulus, heat resistance, moisture permeability resistance, and dimensional stability, and therefore can be used, for example, as an optical film for a liquid crystal display device. As for the optical film of the aforementioned liquid crystal display device, for example, a protective film for a polarizing plate, a retardation film, a reflective film, a viewing angle enhancement film, an antiglare film, a non-reflective film, an antistatic film, a color filter, etc. are listed. Among these, it is preferable that it can be used as a protective film for polarizing plates.

The film thickness of the optical thin film is preferably in the range of 20-120 μm, more preferably in the range of 25-100 μm, particularly preferably in the range of 25-80 μm. When the aforementioned optical film is used as a protective film for polarizing plates, if the film thickness is in the range of 25 to 80 μm, it is suitable for thinning liquid crystal display devices, and sufficient film strength, Rth stability, and Excellent properties such as moisture permeability resistance.

The optical film of the present invention is characterized in that it has a higher modulus of elasticity than when no ester resin is blended. Generally, polyester resins blended with cellulose ester resins for the purpose of improving their processability are sometimes called "plasticizers." From the standpoint of strength, the ester resin of the present invention has performance different from conventional ones when used as an antiplasticizer.

In addition, since the aforementioned protective film for polarizing plates does not bleed out under high temperature and high humidity and can also be adjusted to a desired phase difference, it can be used in a wide range of various liquid crystal display systems depending on the application.

For the liquid crystal display method mentioned above, for example, IPS (In-Plane Switching), TN (Twisted Nematic), VA (Vertical Aligned), OCB (Optically Compensatory Bend: Optically Compensatory) can be exemplified. Bend) and so on.

The optical film of the present invention can be used as an optical material for polarizer protective films, 1/4 wavelength plates, 1 /2 wavelength plate, viewing angle control film, retardation film such as liquid crystal optical compensation film, display front plate, etc. In addition, the resin composition of the present invention can also be used for waveguides, lenses, optical fibers, optical fiber substrates, coating materials, and LED lenses in the fields of optical communication systems, optical switching systems, and optical measurement systems. , lens cover, etc. [Example]

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

Synthesis Example 1 Put 337g of 1,2-propanediol (hereinafter referred to as "PG") as a diol component and 376g of isophthalic acid (hereinafter referred to as "IPA") as a dicarboxylic acid component in a 1-liter 4-necked flask. 111 g of adipic acid (hereinafter abbreviated as "AA") and 0.05 g of catalyst tetraisopropyl titanate (hereinafter abbreviated as "TIPT") were gradually heated to 230° C. under the nitrogen gas flow from the nitrogen gas introduction pipe. The condensation reaction was performed at 230° C. for 8 hours, and when the acid value became 1.0 or less, the reaction product was filtered out to obtain an ester resin (1). The obtained ester resin (1) was a pale yellow liquid at normal temperature, had an acid value of 0.28, a hydroxyl value of 190, a number average molecular weight of 720, and a residual PG amount of 3.1% by mass. Furthermore, 660 g of ester resin (1) and 137 g of acetic anhydride were placed in a 1-liter 3-neck flask, and reacted at 120° C. for 2 hours under a nitrogen gas flow from a nitrogen gas introduction tube. After the reaction, excess acetic anhydride and acetic acid were distilled off under reduced pressure to obtain ester resin (1'). The ester resin (1') is a light yellow liquid at normal temperature, with an acid value of 0.58, a hydroxyl value of 0.0, a number average molecular weight of 790, and a residual PG amount of 0% by mass.

Synthesis example 2 Put 352g of PG as a diol component, 257g of IPA, 226g of AA as a dicarboxylic acid component, and 0.05g of a catalyst TIPT in a 1-liter 4-necked flask, and gradually raise the temperature to 230°C under the nitrogen flow from the nitrogen inlet pipe. ℃. The condensation reaction was performed at 230° C. for 8 hours, and when the acid value became 1.0 or less, the reaction product was filtered out to obtain an ester resin (2). Furthermore, 660 g of the obtained ester resin (2) and 133 g of acetic anhydride were placed in a 1-liter 3-neck flask, and reacted at 120° C. for 2 hours under a nitrogen gas flow from a nitrogen gas introduction tube. After the reaction, excess acetic anhydride and acetic acid were distilled off under reduced pressure to obtain ester resin (2'). The ester resin (2') is a light yellow liquid at normal temperature, with an acid value of 0.57, a hydroxyl value of 0.0, a number average molecular weight of 780, and a residual PG amount of 0% by mass.

Synthesis example 3 Put 922g of PG as a diol component, 944g of phthalic anhydride (hereinafter referred to as "PA") as a dicarboxylic acid component, 310g of AA, and 0.13g of a catalyst TIPT in a 3-liter four-necked flask. The temperature was gradually raised to 220° C. under the nitrogen gas flow of the nitrogen gas introduction tube. The condensation reaction was performed at 220° C. for 8 hours, and when the acid value became 1 or less, the reaction product was filtered out to obtain an ester resin (3). The obtained ester resin (3) was a pale yellow liquid at normal temperature, with an acid value of 0.50, a hydroxyl value of 163, a number average molecular weight of 790, and a residual PG amount of 3.0% by mass. Furthermore, the excess diol was removed from the ester resin (3) at 150°C under reduced pressure, thereby obtaining the ester resin (3'). The obtained ester resin (3') is a light yellow liquid at normal temperature, with an acid value of 0.18, a hydroxyl value of 147, a number average molecular weight of 800, and a residual PG amount of 0.5% by mass.

Examples 1-2, Comparative Examples 1-2 ＜Preparation of Cellulose Ester Optical Film＞ Add 100 parts of triacetyl cellulose resin ("LT-35" manufactured by DAICEL Co., Ltd.), 10 parts of ester resins (1') to (2'), and ester resins (1), (3) to the containing 810 parts of dichloromethane and 90 parts of methanol were dissolved in a mixed solvent to prepare a dope solution as a cellulose ester resin composition. These doping liquids were flow-cast on a glass plate, dried at room temperature for 16 hours, then dried at 50°C for 30 minutes, and then dried at 120°C for 30 minutes to obtain an optical film (film thickness 60 μm or 40 μm ). Table 1 shows the results of the physical properties of the obtained film measured in accordance with the following.

＜Measurement of elastic modulus of optical film＞ Device : AUTOGRAPH AG-IS manufactured by Shimadzu Corporation Test piece: 150mm×10mm, long strip with a thickness of 40μm Between chucks: 100mm Test speed: 10mm/min The higher the modulus of elasticity, the harder the film.

＜Evaluation method of modulus of elasticity＞ ×: The modulus of elasticity is 4600 MPa or less. ◯: The modulus of elasticity is higher than 4600 MPa and lower than 4700 MPa. ◎: Elastic modulus higher than 4700 MPa.

＜Heat Resistance Measurement of Optical Film＞ Device : RSA-III tensile model manufactured by TA Instruments Heating rate: 3°C/min Frequency: 1Hz Load strain: 0.1% Thickness of test piece: 60μm The peak top of tan δ is used as Tg, and the higher the Tg, the better the heat resistance.

＜Evaluation method of heat resistance＞ ×: Tg is 180°C or less. ◯: Tg is higher than 180°C.

＜Dimensional stability measurement of optical films＞ Device : SIINT TMA/SS6100+ humidity control unit manufactured by Hitachi High-Technologies Measuring temperature: constant at 40°C Relative humidity: 0% to 80% Measuring load: 50mN Thickness of test piece: 60μm Measure the dimensional change rate when the relative humidity is adjusted from 0% to 80%. The smaller the rate of change, the better the dimensional stability.

＜Evaluation method of dimensional stability＞ X: The dimensional change rate is more than 0.43%. ○: The dimensional change rate is 0.40% or more and 0.43% or less. ◎: Dimensional change rate is less than 0.40%.

＜HAZE＞ The HAZE value was measured in accordance with JIS K 7105 using a turbidimeter ("NDH 5000" manufactured by Nippon Denshoku Industries, Ltd.). The closer the resulting value is to 0%, the more transparent it is.

＜Evaluation method of transparency＞ X: The HAZE value is more than 1.0%. ○: The HAZE value is 1.0% or less.

＜Measurement of water vapor transmission rate of optical film＞ Measurement was performed in accordance with 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.

<Evaluation method of moisture permeability resistance> ×: Moisture permeability is 600 g/m ² ·24h or more. ○: Moisture permeability is less than 600g/m ² ·24h.

[Table 1]

By using isophthalic acid in the dicarboxylic acid component of the ester resin (I), the elastic modulus and Tg are improved. Moreover, by capping the end of the ester resin (I) with a monocarboxylic acid, the dimensional change after hygroscopicity can be suppressed, and the moisture permeability resistance can also be improved.

Synthesis Example 4 1,906 g of p-toluic acid as a monocarboxylic acid component, 639 g of PG as a diol component, and 0.153 g of a catalyst TiPT were placed in a 3-liter four-necked flask, and the temperature was raised to 220° C. for 11 hours to react. After the reaction, unreacted diol was distilled off under reduced pressure at 200°C. Thereafter, the reduced pressure was released and the temperature was lowered, and the reaction product was filtered out to obtain a diester compound (a) in the form of a transparent yellow liquid. The diester compound (a) had a number average molecular weight (Mn) of 310, an acid value of 0.10, and a hydroxyl value of 4.

Synthesis Example 5 Put 900g of benzoic acid (hereinafter referred to as "BzA") as a monocarboxylic acid component, 294g of PG as a diol component, 50g of dipropylene glycol, and 0.62g of a catalyst TiPT in a 2-liter 4-neck flask, and raise the temperature to 220°C React for 11 hours. After the reaction, unreacted diol was distilled off under reduced pressure at 200°C. After no unreacted alcohol flowed out, the decompression was released and the temperature was lowered, and the reaction product was filtered and taken out to obtain the diester compound (b) as a transparent yellow liquid. The diester compound (b) had a number average molecular weight (Mn) of 300, an acid value of 0.07, and a hydroxyl value of 7.

Synthesis Example 6 952 g of BzA as a monocarboxylic acid component, 124 g of PG as a diol component, 281 g of diethylene glycol, and 0.68 g of catalyst TiPT were placed in a 2-liter four-necked flask, and the temperature was raised to 220° C. for 11 hours to react. After the reaction, unreacted diol was distilled off under reduced pressure at 200°C. After no unreacted alcohol flowed out, the decompression was released and the temperature was lowered, and the reaction product was filtered out to obtain the diester compound (c) as a transparent yellow liquid. The diester compound (c) had a number average molecular weight (Mn) of 350, an acid value of 0.05, and a hydroxyl value of 3.

Embodiment 3～7, comparative example 3 ＜Preparation of Cellulose Ester Optical Film＞ 100 parts of triacetyl cellulose resin ("LT-35" manufactured by DAICEL Co., Ltd.), ester resin (1'), ester resin (3') and two The ester compounds (a) to (c) were added and dissolved in a mixed solvent containing 810 parts of dichloromethane and 90 parts of methanol to prepare a dope liquid as a cellulose ester resin composition. These doping liquids were flow-cast on a glass plate, dried at room temperature for 16 hours, then dried at 50°C for 30 minutes, and then dried at 120°C for 30 minutes to obtain an optical film (film thickness 60 μm or 40 μm ). Table 2 shows the results of the physical properties of the obtained thin film based on the above-mentioned measurement.

[Table 2]

By adding the diester compound (II), the modulus of elasticity, dimensional stability, and moisture permeability resistance are greatly improved. All of them have a low HAZE value and have sufficient transparency as an optical film.

none.

none.

Claims (18)

An anti-plasticizer for cellulose ester resin, which is an ester resin represented by the following general formula (I), B ¹ -(G ¹ -A) _n -G ¹ -B ¹ (I) [in formula (I) , B ¹ is an acetic acid residue, G ¹ is an alkylene glycol residue, an oxyalkylene glycol residue or an aryl glycol residue, A is a dicarboxylic acid residue, and the total molar number of A is More than 25 mol% of is isophthalic acid residues, n is the number of repetitions, G ¹ and A in each repetition can be the same or different, and multiple B ¹ and G ¹ can be the same or different]. Such as the anti-plasticizer for cellulose ester resin of claim 1, wherein ^G in the general formula (I) is an alkylene glycol residue with 2 to 12 carbon atoms, an oxygen with 4 to 12 carbon atoms An alkylene diol residue or an aryl diol residue with 6 to 18 carbon atoms, the average value of n is 1.0 to 10.0. The anti-plasticizer for cellulose ester resin according to claim 1 or 2, wherein the number average molecular weight of the ester resin is in the range of 350~2000. The anti-plasticizer for cellulose ester resin as claimed in item 1 or 2, wherein ^G in the general formula (I) is selected from the group consisting of ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1, One or more residues in the group of 2-butanediol and 2-methyl-1,3-propanediol, A is selected from the group consisting of succinic acid, adipic acid, dicarboxycyclohexane, phthalic diol One or more residues from the group of formic acid, terephthalic acid, and isophthalic acid, and 25 mol% or more of the total moles of A are isophthalic acid residues. The anti-plasticizer for cellulose ester resin according to claim 1 or 2, wherein 40-100 mol% of the total moles of A in the general formula (1) are isophthalic acid residues. Such as the anti-plasticizer for cellulose ester resin of claim 1 or 2, wherein the The residual diol amount in the ester resin is 1.5% by mass or less. The anti-plasticizer for cellulose ester resin as claimed in item 1 or 2, which further contains a diester compound represented by the following general formula (II), B ² -G ² -B ² (II) [formula (II) Among them, ^B2 is an aryl monocarboxylic acid residue or an aliphatic monocarboxylic acid residue, ^G2 is an alkylene glycol residue, an oxygen alkylene glycol residue or an aryl glycol residue, and multiple ^B2 can be the same or different]. Anti-plasticizer for cellulose ester resin as claimed in claim 7, wherein the diester compound is a diester of the following diol and benzoic acid or p-toluic acid, wherein the diol is ethylene glycol, 1,2-propanediol , 1,3-propanediol, 2-methyl-1,3-propanediol, diethylene glycol or dipropylene glycol. The anti-plasticizer for cellulose ester resin according to claim 7, which contains the ester resin and the diester compound at a mass ratio [ester resin/diester compound] of 95/5 to 50/50. The anti-plasticizer for cellulose ester resin according to claim 8, which contains the ester resin and the diester compound at a mass ratio [ester resin/diester compound] of 95/5 to 50/50. The anti-plasticizer for cellulose ester resin as claimed in item 7, wherein B ² of the general formula (II) is an aryl monocarboxylic acid residue. The anti-plasticizer for cellulose ester resin as claimed in claim 8, wherein B ² of the general formula (II) is an aryl monocarboxylic acid residue. The anti-plasticizer for cellulose ester resin as claimed in item 9, wherein B ² of the general formula (II) is an aryl monocarboxylic acid residue. The anti-plasticizer for cellulose ester resin as claimed in item 10, wherein B ² of the general formula (II) is an aryl monocarboxylic acid residue. A cellulose ester resin composition, which is a cellulose ester resin composition containing the anti-plasticizer and cellulose ester resin according to any one of claims 1 to 14, characterized in that it is relatively 100 parts by mass, containing 1 to 30 parts by mass of the anti-plasticizer. An optical film characterized by containing the cellulose ester resin composition as claimed in claim 15. The optical film as claimed in item 16 is for polarizing plate protection. A liquid crystal display device characterized by having the optical film as claimed in claim 16 or 17.