JP6874912B2 - Ester resin, anti-plasticizer, cellulose ester resin composition, optical film and liquid crystal display device - Google Patents

Description

The present invention comprises an ester resin suitable as a antiplasticizer for a resin for an optical material, an ester resin mixture, a cellulose ester resin composition containing these, an optical film obtained by using the resin composition, and a liquid crystal using the same. Regarding display devices.

In recent years, liquid crystal displays have been thinned, and polarizing plate protective films have also been thinned from the conventional 80 μm to 60 μm, and further to 40 to 25 μm. Conventionally, a triacetyl cellulose resin (hereinafter referred to as TAC) has been widely used as a protective film for a polarizing plate from the viewpoint of easy bonding with a polarizer.

However, since TAC is hard and brittle, there is a problem that the strength is insufficient when it is formed into a film and it is easily damaged. Further, since TAC has high moisture permeability and hygroscopicity and is liable to change in size due to moisture permeability and moisture absorption, it is necessary to suppress moisture permeability and moisture absorption by an additive, and various additives have been provided (for example, patents). Reference 1).

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

Japanese Unexamined Patent Publication No. 2013-151699

In view of the above circumstances, the problem to be solved by the present invention is particularly excellent in the balance of strength, heat resistance, and moisture absorption dimensional stability when processed into a film, and is suitable as an antiplasticizer for optical resins. It is an object of the present invention to provide an ester resin, an ester resin mixture, a cellulose ester resin composition containing the same, an optical film obtained by using the resin composition, and a liquid crystal display device using the same.

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

That is, the present invention has the following general formula (I).
H- (G ^1- A) _n- G ^1- H (I)
[In formula (I), G ¹ is an alkylene glycol residue, an oxyalkylene glycol residue or an aryl glycol residue, A is a dicarboxylic acid residue, and 25 mol% or more of the total number of moles of A is isophthalic acid. an acid residue, n is a repeating number, G ¹ for each ^repetition, a is may be the same or different, and G ¹ there are a plurality of may be the same or different. ]
An ester resin represented by the above, an ester resin mixture containing the same, an antiplasticizer composed of these, a cellulose ester resin composition, an optical film obtained by using the composition, and the optical film. It provides a liquid crystal display device using a film.

According to the present invention, there is provided an ester resin and an ester resin mixture which are excellent in balance of strength, heat resistance and dimensional stability when processed into a film and can be suitably used as an antiplasticizer for an optical resin. be able to. Further, by using the specific ester resin or a mixture thereof, it is possible to improve the elastic modulus, heat resistance, and dimensional stability without impairing the transparency, especially in the optical film containing the cellulose ester resin. It can be suitably used as an optical film used in a liquid crystal display device.

The ester resin of the present invention is
The following general formula (I)
H- (G ^1- A) _n- G ^1- H (I)
[In formula (I), G ¹ is an alkylene glycol residue, an oxyalkylene glycol residue or an aryl glycol residue, A is a dicarboxylic acid residue, and 25 mol% or more of the total number of moles of A is isophthalic acid. an acid residue, n is a repeating number, G ¹ for each ^repetition, a is may be the same or different, and G ¹ there are a plurality of may be the same or different. ]
It is characterized by being represented by.

^{G 1} in the general formula (I) is an alkylene glycol residue, an oxyalkylene glycol residue or an aryl glycol residue. The glycol residue refers to a group after removing a hydrogen atom from a hydroxyl group.

The alkylene glycol residue is preferably an alkylene glycol residue having 2 to 12 carbon atoms from the viewpoint of more easily exhibiting the effects of the present invention. For example, ethylene glycol, 1,2-propylene glycol, 1 , 3-Propanediol, 1,2-butanediol, 1,3-butanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl -1,3-Propanediol (neopentyl glycol), 2,2-diethyl-1,3-propanediol (3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3-propane Diol (3,3-dimethylolheptan), 3-methyl-1,5-pentanediol, 1,6-hexanediol, 2,2,4-trimethyl1,3-pentanediol, 2-ethyl-1,3 Residues such as −hexanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, and 1,12-dodecanediol can be mentioned, and two or more of them can be used alone. You may have. Among these, from the viewpoint of being an ester resin having excellent compatibility when mixed with a cellulose ester resin described later, those having no branching between OH groups and having 3 or less carbon atoms are preferable, and among these, ethylene glycol, It is preferably a residue of 1,2-propylene glycol, 1,3-propanediol, 1,2-butanediol, 2-methyl-1,3-propanediol, and of ethylene glycol and 1,2-propylene glycol. It is more preferably a residue, most preferably a residue of 1,2-propylene glycol.

The oxyalkylene glycol residue is preferably an oxyalkylene glycol residue having 4 to 12 carbon atoms from the viewpoint of more easily exhibiting the effects of the present invention. For example, diethylene glycol, triethylene glycol, or tetraethylene glycol is preferable. , Dipropylene glycol, tripropylene glycol and the like, and may be used alone or in combination of two or more.

The aryl glycol residue is preferably an arylglycol residue having 6 to 18 carbon atoms from the viewpoint of more easily exhibiting the effects of the present invention. For example, hydroquinone, resorcin, bisphenol A, alkylene oxide of bisphenol A. Residues such as adducts, bisphenol F, alkylene oxide adducts of bisphenol F, biphenols, and alkylene oxide adducts of biphenols may be mentioned, and they may be used alone or in combination of two or more.

Further, A in the general formula (I) is a dicarboxylic acid residue, and specific examples thereof include an alkylene dicarboxylic acid residue (A1) or an aryldicarboxylic acid residue (A2), which is included in the total number of moles of A. It is essential that the number of moles of isophthalic acid residue in the above is 25 mol% or more. Here, the dicarboxylic acid residue refers to a group in the carboxy group excluding -OH.

In the ester resin represented by the general formula (I), by using a large amount of isophthalic acid as the raw material dicarboxylic acid, when mixed with the optical resin described later, the optical resin, particularly the cellulose ester resin, is subjected to. When it is processed into a film without plasticizing it, the elasticity is improved and heat resistance is imparted, and the transparency that the optical resin originally has is not impaired, and the thin film progresses. It can be suitably used for film applications.

From the viewpoint of exerting the above-mentioned effect, it is essential that the number of moles of the isophthalic acid residue in the dicarboxylic acid residue is 25 mol% or more, and particularly from the viewpoint of exerting the effect more, the content of the isophthalic acid residue is contained. The rate is preferably in the range of 25 to 100 mol%, more preferably in the range of 40 to 100%, and most preferably in the range of 70 to 90%.

The effect of the present invention is more exhibited when the alkylene dicarboxylic acid residue (A1), which may be present together with the isophthalic acid residue, is an alkylene dicarboxylic acid residue having 2 to 12 carbon atoms. It is preferable from the viewpoint of ease, and examples thereof include residues such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, fumaric acid, 1,2-dicarboxycyclohexane, and 1,2-dicarboxycyclohexene. , It may be used alone or in combination of two or more. Among these, residues of succinic acid, adipic acid, and 1,2-dicarboxycyclohexane are preferable, and residues of adipic acid are most preferable, because an optical film having more excellent film transparency can be obtained.

Examples of the aryldicarboxylic acid residue (A2) that may be present together with the isophthalic acid residue include phthalic acid, terephthalic acid, 1,4-naphthalenedicarboxylic acid, and 2,3-naphthalenedicarboxylic acid, 2. , 6-Naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid and other residues can be mentioned, and may be used alone or in combination of two or more. Among these, phthalic acid and terephthalic acid residues are preferable, and phthalic acid residues are most preferable, because an optical film having higher strength can be obtained.

In the present invention, an ester resin represented by the general formula ^(I), G 1, ^A is the same thing, n, i.e. be a mixture of a repeating number of different compounds or, generally G ¹ of in formula ^(I), a and n may be a mixture of different compounds.

From the viewpoint that the effects of the present invention are further exhibited, in the general formula (I), G ¹ is ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 1,2-butanediol, 2-methyl. -1,3-Propylenediol residue, A1 that may be present together is a residue of succinic acid, adipic acid, 1,2-dicarboxycyclohexane, and A2 is a residue of phthalic acid and terephthalic acid. In particular, ^{it is most preferable that G 1} is a residue of ethylene glycol and 1,2-propylene glycol, A1 which may be present in combination is an adipic acid residue, and A2 is a residue of phthalic acid. ..

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

The number average molecular weight of the ester resin of the present invention is preferably in the range of 350 to 2000, particularly preferably in the range of 400 to 1500, and preferably in the range of 500 to 1500, from the viewpoint of achieving both compatibility and film physical characteristics. Most preferably, it is in the range of 1200. Further, the average value of the number of repetitions n in the general formula (I) is preferably in the range of 1.0 to 10.0, preferably 1.0 to 10.0, from the viewpoint of achieving both compatibility and film physical characteristics. The range of 8.0 is more preferable, and the range of 1.5 to 7.0 is most preferable. The number average molecular weight and the average value of n are values measured by GPC measurement.

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 Corporation
Column: "TSK GURDCOLUMN SuperHZ-L" manufactured by Tosoh Corporation + "TSK gel SuperHZM-M" manufactured by Tosoh Corporation + "TSK gel SuperHZM-M" manufactured by Tosoh Corporation + "TSK gel SuperHZ-2000" manufactured by Tosoh Corporation + "TSK gel Super HZ-2000" manufactured by Tosoh Corporation
Detector: RI (Differential Refractometer)
Data processing: "EcoSEC Data Analysis version 1.07" manufactured by Tosoh Corporation
Column temperature: 40 ° C
Developing solvent: tetrahydrofuran Flow velocity: 0.35 mL / min Measurement sample: 7.5 mg of the sample was dissolved in 10 ml of tetrahydrofuran, and the obtained solution was filtered through a microfilter to prepare a measurement sample.
Sample injection volume: 20 μl
Standard sample: The following monodisperse polystyrene having a known molecular weight was used in accordance with the measurement manual of the above-mentioned "HLC-8320 GPC".

(Unidispersed polystyrene)
"A-300" manufactured by Tosoh Corporation
"A-500" manufactured by Tosoh Corporation
"A-1000" manufactured by Tosoh Corporation
"A-2500" manufactured by Tosoh Corporation
"A-5000" manufactured by Tosoh Corporation
"F-1" manufactured by Tosoh Corporation
"F-2" manufactured by Tosoh Corporation
"F-4" manufactured by Tosoh Corporation
"F-10" manufactured by Tosoh Corporation
"F-20" manufactured by Tosoh Corporation
"F-40" manufactured by Tosoh Corporation
"F-80" manufactured by Tosoh Corporation
"F-128" manufactured by Tosoh Corporation
"F-288" manufactured by Tosoh Corporation

Further, the acid value of the ester resin of the present invention is preferably 5 or less, more preferably 1 or less, from the viewpoint of better compatibility with the resin for optical materials.

The ester resin of the present invention is produced, for example, by subjecting the above-mentioned raw materials to an esterification reaction in the presence of an esterification catalyst, for example, in a temperature range of 180 to 250 ° C. for 10 to 25 hours. be able to. The conditions such as the temperature and time of the esterification reaction are not particularly limited and may be set as appropriate. As for the monocarboxylic acid and the dicarboxylic acid, the acid itself may be used as a raw material, or an esterified product thereof, an acid chloride product, an anhydride of a dicarboxylic acid 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 acid-based catalysts such as p-toluenesulfonic acid.

The amount of the esterification catalyst used may be appropriately set, but it is usually preferable to use the esterification catalyst in the range of 0.001 to 0.1 parts by mass with respect to 100 parts by mass of the total amount of the raw material.

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

As a more specific method for producing an ester resin, a method of reacting the above-mentioned alkylene glycol, oxyalkylene glycol or aryl glycol with a compound having a hydroxyl group at the terminal obtained by using a dicarboxylic acid and a monocarboxylic acid is used. Can be mentioned. Here, the alkylene glycol, oxyalkylene glycol or aryl glycol, the dicarboxylic acid and the monocarboxylic acid may be charged into the reaction system at once and reacted with each other, or the alkylene glycol, oxyalkylene glycol or aryl glycol and the dicarboxylic acid may be reacted. A sequential reaction may be carried out in which a compound having a hydroxyl group at the terminal obtained by using an acid is obtained, and then a monocarboxylic acid is further charged into the reaction system.

In the present invention, the above-mentioned ester resin may be used alone and added to a resin for an optical material such as a cellulose ester resin described later, or the following general formula (II) may be used.
^{BG 2-} B (II)
[In formula (II), B is an aryl monocarboxylic acid residue or an aliphatic monocarboxylic acid residue, G ² is an alkylene glycol residue, an oxyalkylene glycol residue or an aryl glycol residue, and there are a plurality of B's. May be the same or different. ]
The diester compound represented by may be used in combination.

B in the general formula (II) is a monocarboxylic acid residue, and specific examples thereof include an aryl monocarboxylic acid residue and an aliphatic monocarboxylic acid residue. Here, the "carboxylic acid residue" refers to a group other than -OH in the carboxy group. The arylmonocarboxylic acid residue is an arylmonocarboxylic acid residue having 6 to 12 carbon atoms, which is easy to obtain as a raw material and an esterification reaction, and when mixed with a cellulose ester resin described later. In addition, it is preferable from the viewpoint of easily balancing moisture permeability, elasticity, and dimensional stability. For example, benzoic acid, dimethyl benzoic acid, trimethyl benzoic acid, tetramethyl benzoic acid, ethyl benzoic acid, propyl benzoic acid, butyl benzoic acid. , Cumic acid, paratershalibutylbenzoic acid, orthotoluic acid, metatoluic acid, paratoluic acid, ethoxybenzoic acid, propoxybenzoic acid, anisic acid, naphthoic acid, etc. Good. In particular, from the viewpoint of more easily exhibiting the effects of the present invention, it is preferably a residue of benzoic acid, paratoluic acid, or dimethyl benzoic acid, and more preferably a residue of benzoic acid or paratoluic acid. Here, it is assumed that the number of carbon atoms does not include the carbon atom in the carboxy group. Further, it may be a residue of aromatic nicotinic acid, floic acid or the like which may have a substituent.

As the aliphatic monocarboxylic acid residue, an aliphatic monocarboxylic acid residue having 1 to 8 carbon atoms is easy to obtain as a raw material, is easy to esterify, and is mixed with a cellulose ester resin described later. It is preferable from the viewpoint of easily balancing moisture permeability, elasticity, and dimensional stability. Examples thereof include residues such as acetic acid, propionic acid, butanoic acid, hexanoic acid, octanoic acid, and octyl acid, and may be used alone. Two or more kinds may be present together, and acetic acid is particularly preferable. Here, it is assumed that the number of carbon atoms does not include the carbon atom in the carboxy group.

^{G 2} in the general formula (II) is an alkylene glycol residue, an oxyalkylene glycol residue or an aryl glycol residue. The glycol residue refers to a group after removing a hydrogen atom from a hydroxyl group.

The alkylene glycol residue is preferably an alkylene glycol residue having 2 to 12 carbon atoms from the viewpoint of more easily exhibiting the effects of the present invention. For example, ethylene glycol, 1,2-propylene glycol, 1 , 3-Propanediol, 1,2-butanediol, 1,3-butanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl -1,3-Propanediol (neopentyl glycol), 2,2-diethyl-1,3-propanediol (3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3-propane Diol (3,3-dimethylolheptan), 3-methyl-1,5-pentanediol, 1,6-hexanediol, 2,2,4-trimethyl1,3-pentanediol, 2-ethyl-1,3 Residues such as −hexanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, and 1,12-dodecanediol can be mentioned, and two or more of them can be used alone. You may have. Among these, from the viewpoint of improving the strength of the film, ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 2-methyl-1, It is preferably a residue of 3-propanediol or 1,5-pentanediol.

The oxyalkylene glycol residue is preferably an oxyalkylene glycol residue having 4 to 12 carbon atoms from the viewpoint of more easily exhibiting the effects of the present invention. For example, diethylene glycol, triethylene glycol, or tetraethylene glycol is preferable. , Dipropylene glycol, tripropylene glycol and the like, and may be used alone or in combination of two or more.

The aryl glycol residue is preferably an arylglycol residue having 6 to 18 carbon atoms from the viewpoint of more easily exhibiting the effects of the present invention. For example, hydroquinone, resorcin, bisphenol A, alkylene oxide of bisphenol A. Residues such as adducts, bisphenol F, alkylene oxide adducts of bisphenol F, biphenols, and alkylene oxide adducts of biphenols may be mentioned, and they may be used alone or in combination of two or more.

From the viewpoint that the effects of the present invention are further exhibited, in the general formula (II), B is a residue of benzoic acid and paratoluic acid, and G ² is ethylene glycol, 1,2-propylene glycol and 1,3-propanediol. , 2-Methyl-1,3-propanediol, diethylene glycol or dipropylene glycol residues are preferred.

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

It will be described later that the ester resin mixture of the present invention contains the ester resin (I) and the diester compound (II) in a mass ratio [ester resin / diester compound] of 100/0 to 50/50. It is preferable because it can be suitably used as an antiplasticizer for an optical resin.

When such a diester compound (II) is contained, it is suitably arranged in the gaps between the resin for optical materials, particularly the cellulose ester resin, and as a result, the effect of improving moisture permeability, elastic modulus, and dimensional stability is further improved. In addition to being further expressed, compatibility with resins for optical materials can be ensured, and transparency that can be used as an optical film can be maintained more effectively.

From the viewpoints that these effects are further exhibited, the contamination of the production line due to volatilization is suppressed, and the transparency of the optical film can be easily maintained, the ester resin (I) and the diester compound (II) are used. The ratio of the ester resin (I) in the total mass is preferably 50 to 100% by mass, more preferably 60 to 95% by mass, and most preferably 65 to 90% by mass.

The ester resin mixture of the present invention may consist only of the ester resin (I) and the diester compound (II), or may contain a polyester other than the ester resin (I) or a diester compound other than the diester compound (II). It may be included. Further, a material known as a so-called optical resin modifier other than the ester resin (I) and the diester compound (II) may be contained, and the ester resin (I) and the diester compound (II) are produced. It may contain the unreacted product of the raw material used in.

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

The resin for optical materials is not particularly limited as long as it is highly transparent and can be processed into a film, and is not particularly limited. For example, (meth) acrylic resin, cyclic olefin resin, and polycarbonate. Examples thereof include resins and cellulose ester resins. In particular, it is preferable to use a cellulose ester resin from the viewpoint that the effects of the present invention are further exhibited.

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

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

Examples of the cellulose ester resin include cellulose acetate, cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate phthalate, cellulose nitrate and the like, and when used as a protective film for a polarizing plate, cellulose acetate is used. This is preferable because a film having excellent mechanical properties and transparency can be obtained. These cellulose ester resins may be used alone or in combination of two or more.

The degree of polymerization of the cellulose acetate is preferably in the range of 250 to 400, and the degree of vinegarization is preferably in the range of 54.0 to 62.5% by mass, 58.0 to 62.5. More preferably, it is in the range of% by mass. A film having excellent mechanical properties can be obtained as long as the degree of polymerization and the degree of vinegarization of the cellulose acetate are within such a range. In the present invention, it is more preferable to use so-called cellulose triacetate. The degree of vinegarization in the present invention is the mass ratio of acetic acid produced by saponification of the cellulose acetate to the total amount of the cellulose acetate.

The number average molecular weight of the 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 cellulose acetate is in this range, a film having excellent mechanical properties can be easily obtained.

The optical film in the present invention uses a resin composition containing the ester resin or the ester resin mixture of the present invention and a resin for an optical material such as a cellulose ester resin, and contains various other additives as necessary. You may use the resin composition.

In order to obtain the optical film of the present invention, for example, techniques such as extrusion molding and cast molding are used. Specifically, for example, an unstretched optical film can be extruded by using an extruder or the like equipped with a T-die, a circular die, or the like. When the optical film of the present invention is obtained by extrusion molding, a resin composition obtained by melt-kneading the ester resin, ester resin mixture, resin for optical materials such as cellulose ester resin, and other additives is used. Alternatively, it can be melt-kneaded at the time of extrusion molding and then extruded as it is.

Examples of the additive include the ester resin of the present invention, other modifiers other than the diester compound, a thermoplastic resin, an ultraviolet absorber, a matting agent, a stabilizer, and an antioxidant (for example, an antioxidant and a peroxide). Examples include degrading agents, radical prohibiting agents, metal inactivating agents, acid trapping agents, etc.), dyes, and the like.

Examples of the other modifier include ester resins other than the ester resins and diester compounds specified in the present invention, phosphoric acid esters such as triphenyl phosphate (TPP), tricresyl phosphate, and cresyl diphenyl phosphate, dimethyl phthalates, and the like. Phthalate esters such as diethylphthalate, dibutylphthalate, di-2-ethylhexylphthalate, ethylphthalyl ethylglycolate, butylphthalylbutylglycolate, trimethylpropantribenzoate, pentaerythritol tetraacetate, tributylacetylcitrate, etc. It can be used within a range that does not impair the effects of the present invention.

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, polyurethane resins, acrylic resins, epoxy resins, toluene sulfonamide resins and the like.

The ultraviolet absorber is not particularly limited, and examples thereof include an oxybenzophenone compound, a benzotriazole compound, a salicylate ester compound, a benzophenone compound, a cyanoacrylate compound, and a nickel complex salt compound. The ultraviolet absorber is preferably used in the range of 0.01 to 2 parts by mass with respect to 100 parts by mass of the cellulose ester resin.

Examples of the matting agent include silicon oxide, titanium oxide, aluminum oxide, calcium carbonate, calcium silicate, aluminum silicate, magnesium silicate, calcium phosphate, kaolin, talc and the like. The matting agent is preferably used in the range of 0.1 to 0.3 parts by mass with respect to 100 parts by mass of the cellulose ester resin.

Examples of the stabilizer include calcium hydroxide, calcium carbonate, fatty acid metal salt and the like. The stabilizer is preferably used in the range of 50 to 5000 ppm with respect to 100 parts by mass of the cellulose ester resin.

The type and amount of the dye are not particularly limited as long as they do not impair the object of the present invention.

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

According to the solution casting method, the orientation of the resin for optical materials such as the cellulose ester resin in the film during molding can be suppressed, so that the obtained film exhibits substantially optical isotropic properties. Can be done. The film exhibiting optical isotropic properties can be used as an optical material such as a liquid crystal display, and is particularly useful as a protective film for a polarizing plate. In addition, the film obtained by the above method is less likely to have irregularities on its surface and is excellent in surface smoothness.

The solution casting method is generally included in a first step of dissolving the resin composition in an organic solvent and casting the obtained resin solution on a metal support, and in the cast resin solution. The organic solvent is distilled off and dried to form a film, followed by a third step of peeling the film formed on the metal support from the metal support and heating and drying it.

Examples of the metal support used in the first step include those made of endless belt-shaped or drum-shaped metal, and for example, those made of stainless steel and whose surface is mirror-finished can be used. ..

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

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

Next, the third step is a step of peeling the film formed in the second step from the metal support and heating and drying it under a temperature condition higher than that of the second step. As the heat-drying method, for example, a method of gradually raising the temperature under a temperature condition of 100 to 160 ° C. is preferable because good dimensional stability can be obtained. By heating and drying under the above temperature conditions, the organic solvent remaining in the film after the second step can be almost completely removed.

The organic solvent can be recovered and reused in the first to third steps.

The organic solvent that can be used when the resin composition is mixed with an organic solvent and dissolved is not particularly limited as long as they can be dissolved, but for example, when cellulose acetate is used as the resin for an optical material, it is good. As the solvent, it is preferable to use, for example, an organic halogen compound such as methylene chloride or dioxolanes.

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

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

The concentration of the resin for optical materials 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 unstretched optical film obtained by the above method is stretched by longitudinal uniaxial stretching in the mechanical flow direction and horizontal uniaxial stretching in the direction orthogonal to the mechanical flow direction, if necessary. An optical film can be obtained. Further, a biaxially stretched stretched film can be obtained by stretching by a sequential biaxial stretching method of roll stretching and tenter stretching, a simultaneous biaxial stretching method by tenter stretching, a biaxial stretching method by tubular stretching, and the like. The draw ratio is preferably 0.1% or more and 300% or less in at least one direction, more preferably 0.2% or more and 250% or less, and preferably 0.3% or more and 200% or less. Most preferred. By designing in this range, a stretched optical film preferable in terms of birefringence, heat resistance, and strength can be obtained.

Since the optical film of the present invention is excellent in elastic modulus, heat resistance, moisture permeability resistance, and dimensional stability, it can be used, for example, as an optical film for a liquid crystal display device. Examples of the optical film of the liquid crystal display device include a protective film for a polarizing plate, a retardation film, a reflective film, a viewing angle improving film, an antiglare film, a non-reflective film, an antistatic film, a color filter and the like. Among them, it can be preferably used as a protective film for a polarizing plate.

The film thickness of the optical film is preferably in the range of 20 to 120 μm, more preferably in the range of 25 to 100 μm, and particularly preferably in the range of 25 to 80 μm. When the optical film is used as a protective film for a polarizing plate, a film thickness in the range of 25 to 80 μm is suitable for thinning the liquid crystal display device, and has sufficient film strength and Rth stability. , Excellent performance such as moisture permeability can be maintained.

The optical film of the present invention is characterized in that the elastic modulus is higher than that in the case where the ester resin is not blended. Generally, a polyester resin blended for the purpose of improving the processability of a cellulose ester resin is sometimes called a "plasticizer", but the ester resin of the present invention is more optical than the plasticizing effect. From the viewpoint of being able to improve the strength of the material resin, it has a performance different from the conventional one in that it is used as an antiplasticizer.

Further, since the protective film for a polarizing plate can be adjusted to a desired phase difference without causing bleeding under high temperature and high humidity, it is widely used in various liquid crystal display methods depending on the application. be able to.

Examples of the liquid crystal display method include IPS (In-Plane Switching), TN (Twisted Nematic), VA (Vertically Aligned), and OCB (Opticaly Compensation Bend). Optically Company Bend) and the like can be exemplified.

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

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

Example 1
In a 1-liter four-necked flask, 346 g of 1,2-propylene glycol (hereinafter abbreviated as "PG") as a glycol component, 376 g of isophthalic acid (hereinafter abbreviated as "IPA") as a dicarboxylic acid component, and adipic acid (hereinafter abbreviated as "AA"). 110 g (abbreviated as) and 0.05 g of tetraisopropyl titanate (hereinafter abbreviated as “TIPT”) as a catalyst were charged, and the temperature was gradually raised to 230 ° C. under a nitrogen stream from a nitrogen introduction tube. The condensation reaction was carried out at 230 ° C. for 8 hours, and it was confirmed that the acid value was 1.0 or less. The ester resin (1) of the present invention was obtained by removing excess glycol at 150 ° C. under reduced pressure. The obtained ester resin (1) was a pale yellow liquid at room temperature, had an acid value of 0.25 and a hydroxyl value of 135, had a number average molecular weight of 920, and had a residual PG amount of 0.2% by mass.

Example 2
In a 1-liter four-necked flask, 352 g of PG as a glycol component, 257 g of IPA and 226 g of AA as a dicarboxylic acid component, and 0.05 g of TIPT as a catalyst were charged, and the temperature was gradually raised to 230 ° C. under a nitrogen stream from a nitrogen introduction tube. .. The condensation reaction was carried out at 230 ° C. for 8 hours, and it was confirmed that the acid value was 1.0 or less. The ester resin (2) of the present invention was obtained by removing excess glycol at 150 ° C. under reduced pressure. The obtained ester resin (2) was a pale yellow liquid at room temperature, had an acid value of 0.27 and a hydroxyl value of 135, had a number average molecular weight of 950, and had a residual PG amount of 0.2% by mass.

Comparative Example 1
A 3 liter four-necked flask is charged with 922 g of PG as a glycol component, 944 g of phthalic anhydride (hereinafter abbreviated as "PA") as a dicarboxylic acid component, 310 g of AA, and 0.13 g of TIPT as a catalyst, and a nitrogen introduction tube. The temperature was gradually raised to 220 ° C. under a more nitrogen stream. The condensation reaction was carried out at 220 ° C. for 8 hours, and when the acid value became 1 or less, the reaction product was filtered and taken out to obtain an ester resin (1'). The obtained ester resin (1') was a pale yellow liquid at room temperature, had an acid value of 0.50 and a hydroxyl value of 163, had a number average molecular weight of 790, and a residual PG amount of 3.0% by mass. ..

Comparative Example 2
The ester resin (1') was obtained under reduced pressure at 150 ° C. by removing excess glycol to obtain an ester resin (2'). The obtained ester resin (2') was a pale yellow liquid at room temperature, had an acid value of 0.18 and a hydroxyl value of 147, had a number average molecular weight of 800, and had a residual PG amount of 0.5% by mass. ..

Examples 3-4, Comparative Examples 3-4
<Adjustment of cellulose ester optical film>
100 parts of triacetyl cellulose resin (“LT-35” manufactured by Daicel Co., Ltd.), ester resins (1) to (2), ester resins (1') to (2') 10 parts, methylene chloride 810 parts and methanol 90 parts. A dope solution, which is a cellulose ester resin composition, was prepared by adding and dissolving the mixture in a mixed solvent consisting of parts. These doping solutions are cast on a glass plate to a thickness of 0.8 mm or 0.5 mm, dried at room temperature for 16 hours, and then dried at 50 ° C. for 30 minutes and further at 120 ° C. for 30 minutes. An optical film (60 μm or 40 μm) was obtained. The physical characteristics of the obtained film were measured according to the following, and the results are shown in Table 1.

<Measurement of elastic modulus of optical film>
Equipment: Autograph AG-IS manufactured by Shimadzu Corporation
Specimen: 150 mm x 10 mm, 40 μm thick strip type Chuck spacing: 100 mm
Test speed: 10 mm / min
The larger the elastic modulus, the harder the film.

<Evaluation method of elastic modulus>
X: The elastic modulus is 4600 MPa or less.
◯: The elastic modulus is higher than 4600 MPa and is 4650 MPa or less.
⊚: Elastic modulus is higher than 4650 MPa.

<Measurement of heat resistance of optical film>
Equipment: TA Instruments RSA-III tension mode heating rate: 3 ° C / min
Frequency: 1Hz
Load strain: 0.1%
Specimen film thickness: 60 μm
The peak top of tan δ is Tg, and the higher the Tg, the better the heat resistance.

<Evaluation method of heat resistance>
X: Tg is 182 ° C. or lower.
◯: Tg is higher than 182 ° C.

<Measurement of dimensional stability of optical film>
Equipment: Hitachi High-Tech SIINT TMA / SS6100 + Humidity control unit Measurement temperature: 40 ° C constant Relative humidity: 0% -80%
Measured load: 50mN
Specimen film thickness: 60 μm
The dimensional change rate when the relative humidity was changed from 0% to 80% was measured. The smaller the rate of change, the better the dimensional stability.

<Evaluation method of dimensional stability>
X: The dimensional change rate is larger than 0.45%.
◯: The dimensional change rate is 0.40% or more and 0.45% or less.
⊚: The dimensional change rate is smaller than 0.40%.

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

<Transparency evaluation method>
X: The HAZE value is larger than 1.0%.
◯: The HAZE value is 1.0% or less.

<Measurement of moisture permeability of optical film>
Measurements were made according to the method described in JIS Z 0208. The measurement conditions were a temperature of 40 ° C. and a relative humidity of 90%. The smaller the value obtained, the better the moisture permeation resistance.

<Evaluation method of moisture permeability>
×: moisture permeability is greater than 600g ^/ m 2 · 24h.
○: moisture permeability is less than or equal to 600g ^/ m 2 · 24h.

<Evaluation of non-volatility>
The amount of mass change when the film was exposed to an environment of 85 ° C. and a relative humidity of 90% (wet and heat environment) for 120 hours was measured. The smaller the value obtained, the better the non-volatility.

<Non-volatile evaluation method>
X: Moist heat loss is larger than 1.5%.
◯: Moist heat loss is 1.5% or less.

By using isophthalic acid as the dicarboxylic acid component of the ester resin (I), the elastic modulus and Tg were improved. Further, by reducing the amount of residual glycol of the ester resin (I), the change in the hygroscopic dimension was suppressed, and the moisture permeation resistance and the non-volatility in a moist heat environment were improved.

Synthesis example 1
A 3-liter four-necked flask was charged with 1,906 g of paratolylic acid as a monocarboxylic acid component, 639 g of PG as a glycol component, and 0.153 g of TipT as a catalyst, and then the temperature was raised to 220 ° C. and reacted for 11 hours. After the reaction, unreacted glycol was distilled off under reduced pressure at 200 ° C. Then, the reduced pressure was released and the temperature was lowered, and the reaction product was filtered out to obtain a transparent yellow liquid diester compound (a). The number average molecular weight (Mn) of the diester compound (a) was 310, the acid value was 0.10, and the hydroxyl value was 4.

Synthesis example 2
A 2-liter four-necked flask is charged with 900 g of benzoic acid (hereinafter abbreviated as "BzA") as a monocarboxylic acid component, 294 g of PG as a glycol component, 50 g of dipropylene glycol, and 0.62 g of TiPT as a catalyst, and then 220 ° C. The temperature was raised to 11 hours. After the reaction, unreacted glycol was distilled off under reduced pressure at 200 ° C. After the outflow of unreacted alcohol was eliminated, the pressure was released and the temperature was lowered, and the reaction product was filtered out to obtain a transparent yellow liquid diester compound (b). The number average molecular weight (Mn) of the diester compound (b) was 300, the acid value was 0.07, and the hydroxyl value was 7.

Synthesis example 3
A 2-liter four-necked flask was charged with 952 g of BzA as a monocarboxylic acid component, 124 g of PG as a glycol component, 281 g of diethylene glycol, and 0.68 g of TipT as a catalyst, and then the temperature was raised to 220 ° C. and reacted for 11 hours. After the reaction, unreacted glycol was distilled off under reduced pressure at 200 ° C. After the outflow of unreacted alcohol was eliminated, the pressure was released and the temperature was lowered, and the reaction product was filtered out to obtain a transparent yellow liquid diester compound (c). The number average molecular weight (Mn) of the diester compound (c) was 350, the acid value was 0.05, and the hydroxyl value was 3.

Examples 5-11, Comparative Examples 5-7
<Adjustment of cellulose ester optical film>
100 parts of triacetyl cellulose resin (“LT-35” manufactured by Daicel Co., Ltd.), ester resins (1) to (2), ester resins (1') to (2') and diester compounds (a) to (c). A dope solution which is a cellulose ester resin composition was prepared by adding and dissolving in a mixed solvent consisting of 10 parts in total, 810 parts of methylene chloride and 90 parts of methanol at the ratios shown in Tables 2 to 3. These doping solutions are cast on a glass plate to a thickness of 0.8 mm or 0.5 mm, dried at room temperature for 16 hours, and then dried at 50 ° C. for 30 minutes and further at 120 ° C. for 30 minutes. The optical film (60 μm or 40 μm) of the present invention was obtained. The physical characteristics of the obtained film were measured according to the above, and the results are shown in Tables 2 and 3.

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

Claims (13)

The following general formula (I)
H- (G ^1- A) _n- G ^1- H (I)
[In formula (I), G ¹ is an alkylene glycol residue, an oxyalkylene glycol residue or an aryl glycol residue, A is a dicarboxylic acid residue, and 25 mol% or more of the total number of moles of A is isophthalic acid. an acid residue, n is a repeating number, G ¹ for each ^repetition, a is may be the same or different, and G ¹ there are a plurality of may be the same or different. ]
A cellulose ester resin composition containing the ester resin represented by and the cellulose ester resin .
A cellulose ester resin composition in which the blending amount of the ester resin is in the range of 0.1 to 50 parts by mass with respect to 100 parts by mass of the cellulose ester resin . ^{G 1} in the general formula (I) is an alkylene glycol residue having 2 to 12 carbon atoms, an oxyalkylene glycol residue having 4 to 12 carbon atoms, or an aryl glycol residue having 6 to 18 carbon atoms, and n The cellulose ester resin composition according to claim 1, wherein the average value of is 1.0 to 10.0. The cellulose ester resin composition according to claim 1 or 2, wherein the number average molecular weight of the ester resin is in the range of 350 to 2000. ^{G 1} in the general formula (I) is selected from the group consisting of ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 1,2-butanediol and 2-methyl-1,3-propanediol. One or more residues selected from the group consisting of succinic acid, adipic acid, dicarboxycyclohexane, phthalic acid, terephthalic acid and isophthalic acid, and the total of A. The cellulose ester resin composition according to any one of claims 1 to 3, wherein 25 mol% or more of the number of moles is an isophthalic acid residue. The cellulose ester resin composition according to any one of claims 1 to 4, wherein 40 to 100 mol% of the total number of moles of A in the general formula (I) is an isophthalic acid residue. The cellulose ester resin composition according to any one of claims 1 to 5, wherein the amount of residual glycol in the ester resin is 1.5% by mass or less. The following general formula (I)
H- (G ^1- A) _n- G ^1- H (I)
[In formula (I), G ¹ is an alkylene glycol residue, an oxyalkylene glycol residue or an aryl glycol residue, A is a dicarboxylic acid residue, and 25 mol% or more of the total number of moles of A is isophthalic acid. an acid residue, n is a repeating number, G ¹ for each ^repetition, a is may be the same or different, and G ¹ there are a plurality of may be the same or different. ]
Ester resin represented by
The following general formula (II)
^{BG 2-} B (II)
[In formula (II), B is an aryl monocarboxylic acid residue or an aliphatic monocarboxylic acid residue, G ² is an alkylene glycol residue, an oxyalkylene glycol residue or an aryl glycol residue, and there are a plurality of B's. May be the same or different. ]
An ester resin mixture containing a diester compound represented by .
An ester resin mixture containing the ester resin and the diester compound in a mass ratio [ester resin / diester compound] of 95/5 to 50/50. The diester compound is a diester of ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, diethylene glycol or dipropylene glycol, and benzoic acid or paratoluic acid. The ester resin mixture according to claim 7. The following general formula (I)
H- (G ^1- A) _n- G ^1- H (I)
[In formula (I), G ¹ is an alkylene glycol residue, an oxyalkylene glycol residue or an aryl glycol residue, A is a dicarboxylic acid residue, and 25 mol% or more of the total number of moles of A is isophthalic acid. an acid residue, n is a repeating number, G ¹ for each ^repetition, a is may be the same or different, and G ¹ there are a plurality of may be the same or different. ]
A antiplasticizer for a resin for an optical material, which comprises the ester resin represented by the above, or the ester resin mixture according to claim 7 or 8. It is a cellulose ester resin composition containing the antiplasticizer according to claim 9 and the cellulose ester resin, and contains 1 to 30 parts by mass of the antiplasticizer with respect to 100 parts by mass of the cellulose ester resin. A cellulose ester resin composition characterized by becoming. An optical film comprising the cellulose ester resin composition according to any one of claims 1 to 6 and 10. The optical film according to claim 11 , which is for protecting a polarizing plate. A liquid crystal display device comprising the optical film of claim 11 or 12.