JP6614469B2 - Ester resin, antiplasticizer, cellulose ester resin composition, optical film and liquid crystal display device - Google Patents

Description

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

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

  However, since TAC is hard and brittle, there is a problem that when it is formed into a film, its strength is insufficient and breakage easily occurs. Moreover, since TAC has high moisture permeability and dimensional change due to moisture absorption is likely to occur, it is necessary to suppress moisture absorption by additives, and various additives have been provided (see, for example, Patent Document 1).

  Usually, when an additive is added to suppress moisture permeation, plasticization of the resin occurs at the same time. Therefore, it is difficult to achieve both strength and moisture resistance of the obtained film. Therefore, development of an additive (= anti-plasticizer) capable of achieving both moisture permeation suppression and improvement in elastic modulus is demanded.

JP 2013-151699 A

  In view of the above situation, the problem to be solved by the present invention is particularly excellent in the balance of strength, moisture permeability and optical properties when processed into a film, and is suitable as an antiplasticizer for optical resins. It is to provide an ester resin that can be used, a resin composition containing the ester resin, an optical film obtained using the resin composition, and a liquid crystal display device using the optical film.

  As a result of intensive studies, the present inventors have found that the above-mentioned problems can be solved by adjusting the ratio of the raw material in the ester resin, particularly dicarboxylic acid, and have completed the present invention.

That is, the present invention provides the following general formula (1)
B- (GA) _n -GB (1)
[In the formula (1), B is a monocarboxylic acid residue, G is an alkylene glycol residue, an oxyalkylene glycol residue or an aryl glycol residue, A is a dicarboxylic residue, and the total mole of A 20 mol% or more of the number is an isophthalic acid residue, n is the number of repetitions, G and A may be the same or different for each repetition, and a plurality of B and G may be the same or different . ]
The ester resin characterized by these, the resin composition containing this, the optical film obtained using this composition, and the liquid crystal display device using the said optical film are provided.

  ADVANTAGE OF THE INVENTION According to this invention, the ester resin which is excellent in the balance of the intensity | strength at the time of processing into a film form, moisture permeability, and an optical characteristic, and can be used suitably as an antiplasticizer with respect to optical resin can be provided. In addition, by using the specific ester resin, particularly in an optical film containing a cellulose ester resin, it is possible to achieve both improvement in elastic modulus, suppression of moisture transmission, and maintenance of optical properties, and as an optical film used in a liquid crystal display device It can be used suitably.

The ester resin of the present invention has the following general formula (1)
B- (GA) _n -GB (1)
[In the formula (1), B is a monocarboxylic acid residue, G is an alkylene glycol residue, an oxyalkylene glycol residue or an aryl glycol residue, A is a dicarboxylic residue, and the total mole of A 20 mol% or more of the number is an isophthalic acid residue, n is the number of repetitions, G and A may be the same or different for each repetition, and a plurality of B and G may be the same or different . ]
It is represented by.

  B in the general formula (1) is a monocarboxylic acid residue, and specific examples include an aryl monocarboxylic acid residue or an aliphatic monocarboxylic acid residue. Here, the “carboxylic acid residue” refers to a group other than —OH in the carboxy group. When the aryl monocarboxylic acid residue is an aryl monocarboxylic acid residue having 6 to 12 carbon atoms, the raw material is easily available, the esterification reaction is easy, and the cellulose ester resin described later is mixed. In addition, from the viewpoint of easily balancing moisture resistance, elastic modulus, and optical properties, for example, benzoic acid, dimethylbenzoic acid, trimethylbenzoic acid, tetramethylbenzoic acid, ethylbenzoic acid, propylbenzoic acid, butylbenzoic acid, Examples include cumic acid, para-tert-butylbenzoic acid, orthotoluic acid, metatoluic acid, p-toluic acid, ethoxybenzoic acid, propoxybenzoic acid, anisic acid, naphthoic acid, etc., which may be used alone or in combination of two or more. . In particular, from the viewpoint of easily expressing the effects of the present invention, a residue of benzoic acid, p-toluic acid, or dimethylbenzoic acid is preferable, and a residue of benzoic acid is more preferable. Here, the number of carbon atoms does not include the carbon atom in the carboxy group. Further, it may be a residue such as nicotinic acid or furoic acid having an aromaticity, which may have a substituent.

  As the aliphatic monocarboxylic acid residue, it is an aliphatic monocarboxylic acid residue having 1 to 8 carbon atoms, which is mixed with raw material availability, ease of esterification reaction, and cellulose ester resin described later. In particular, it is preferable from the viewpoint of easily balancing moisture resistance, elastic modulus, and optical properties. For example, residues such as acetic acid, propionic acid, butanoic acid, hexanoic acid, octanoic acid, octylic acid, etc. More than one species may be present, and acetic acid is particularly preferred. Here, the number of carbon atoms does not include the carbon atom in the carboxy group.

  G in the general formula (1) 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 expressing 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-dimethylol heptane), 3-methyl-1,5-pentanediol, 1,6-hexanediol, 2,2 4-trimethyl 1,3-pentanediol, 2-ethyl-1,3-hexanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12- Residues such as dodecanediol are mentioned, and they may be used alone or in combination of two or more. Among these, from the viewpoint of being an ester resin that is more excellent in compatibility when mixed with a cellulose ester resin to be described later, those having 3 or less carbon atoms that do not include a branch between OH groups are preferable, among which ethylene glycol, It is preferably a residue of 1,2-propylene glycol, 1,3-propanediol, 1,2-butanediol, 2-methyl-1,3-propanediol. More preferably, it is a residue.

  The oxyalkylene glycol residue is preferably an oxyalkylene glycol residue having 4 to 12 carbon atoms from the viewpoint of more easily expressing the effects of the present invention. For example, diethylene glycol, triethylene glycol, tetraethylene glycol And residues such as dipropylene glycol and tripropylene glycol may be used alone or in combination of two or more.

  The aryl glycol residue is preferably an aryl glycol residue having 6 to 18 carbon atoms from the viewpoint that the effects of the present invention are more easily expressed. For example, hydroquinone, resorcin, bisphenol A, alkylene oxide of bisphenol A Examples include residues such as adducts, bisphenol F, alkylene oxide adducts of bisphenol F, biphenols, alkylene oxide adducts of biphenols, etc., which may be used alone or in combination of two or more.

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

  In the ester resin represented by the general formula (1), by using a large amount of isophthalic acid as a raw dicarboxylic acid, when mixed with the optical resin described later, the optical resin, particularly the cellulose ester resin, is used. When it is processed into a film without plasticizing it, the elastic modulus is improved and moisture permeability is imparted, and the optical properties inherent to the optical resin are not impaired, and the thinning proceeds. It can use suitably for an optical film use.

  From the viewpoint of achieving the above-mentioned effects, it is essential that the number of moles of isophthalic acid residues in the dicarboxylic acid residue is 20 mol% or more. The rate is preferably in the range of 25-100 mol%.

  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, so that the effects of the present invention are more manifested. Preferred from the viewpoint of easy, for example, residues such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, fumaric acid, 1,2-dicarboxycyclohexane, 1,2-dicarboxycyclohexene These may be used alone or in combination of two or more. Among these, a residue of succinic acid, adipic acid, and 1,2-dicarboxycyclohexane is preferable, and an adipic acid residue is most preferable because an optical film having more excellent moisture resistance can be obtained.

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

  In the present invention, the ester resin represented by the general formula (1), wherein B, G, and A are the same, and n, that is, a mixture of compounds that differ only in the number of repetitions, or It may be a mixture of compounds in which B, G, A and n in the general formula (1) are different. In the present invention, in an optical film obtained by mixing with a resin for optical materials described below, in particular, a cellulose ester resin, it is represented in the general formula (1) in order to combine improvement of moisture permeability and elastic modulus. In the area ratio in the GPC measurement of the ester resin, n = 0 component in the general formula (1) is 10 to 50%, and n is an area% of a component of 3 or more and n = 0 component area%. The ratio (n ≧ 3) / (n = 0) is more preferably 3 or less.

  By setting such n = 0 component, so-called diester compound, to a specific content, it is suitably placed in the gap between the resin for optical materials, particularly the cellulose ester resin, and as a result, the effect of suppressing moisture permeability is manifested. In addition, by relatively reducing the content of components having n of 3 or more, compatibility with the optical material resin can be ensured, and transparency that can be used as an optical film can be more effectively maintained. .

  From the viewpoints of these effects being further exhibited, suppression of contamination of production lines due to volatilization, and maintenance of transparency of the optical film, etc., the area ratio in the GPC measurement in the general formula (1) It is preferable that the n = 0 component is 20 to 50%, and the ratio (n ≧ 3) / (n = 0) of the area% of the component where n is 3 or more and the area% of the n = 0 component is A range of 0.2 to 1.5 is preferable.

The GPC measurement in the present invention was performed under the following conditions.
[GPC measurement conditions]
Measuring device: High-speed GPC device “HLC-8320GPC” manufactured by Tosoh Corporation
Column: "TSK GARDCOLUMN 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 SuperHZ-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 rate: 0.35 mL / min Sample to be measured: A sample obtained by dissolving 7.5 mg of a sample in 10 ml of tetrahydrofuran and filtering the obtained solution through a microfilter was used as a sample to be measured.
Sample injection volume: 20 μl
Standard sample: The following monodisperse polystyrene having a known molecular weight was used according to the measurement manual of “HLC-8320GPC”.

(Monodispersed 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

(GPC analysis conditions)
In the ester resin of the present invention, the area% of the n = 0 component and the component where n is 3 or more can be calculated as follows. GPC measurement of the ester resin is performed to determine the polystyrene equivalent molecular weight of each component corresponding to the detected peak, and the content ratio (area fraction) of each component corresponding to the detected peak from the ratio of the detected peak area Was calculated.

  From the viewpoint of further manifesting the effects of the present invention, in general formula (1), B is a residue of benzoic acid and acetic acid, G is ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 1 , 2-butanediol, 2-methyl-1,3-propanediol residue, which may be contained together, A1 is a residue of succinic acid, adipic acid, 1,2-dicarboxycyclohexane, A2 is phthalic acid , Preferably a residue of terephthalic acid, in particular, B is a residue of benzoic acid, G is a residue of ethylene glycol or 1,2-propylene glycol, and A1 which may be present together Most preferably, the adipic acid residue, A2, is a phthalic acid residue.

  Moreover, as an ester resin of this invention, it is preferable that the weight average molecular weight is the range of 350-1200 from the viewpoint of making compatibility and film physical properties compatible, and it is preferable that it is the range of 350-800 especially. Moreover, it is preferable that it is the range of 0.2-3 as an average value of the repeating number n in the said General formula (1) from a viewpoint of making compatibility and film physical properties compatible. The weight average molecular weight and the average value of n are also values measured by the GPC measurement.

  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. From the same viewpoint, the hydroxyl value of the ester resin is preferably 50 or less, and more preferably 20 or less.

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

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

  Although the usage-amount of the said esterification catalyst should just be set suitably, it is preferable to use normally in 0.001-0.1 mass part with respect to 100 mass parts of whole quantity of a raw material.

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

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

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

When employ | adopting the said manufacturing method, what is represented by following General formula (2) is preferable as diester compound (II) added later.
B2-G2-B2 (2)
(In the formula, B2 is an aryl monocarboxylic acid residue or an aliphatic monocarboxylic acid residue, G2 is an alkylene glycol residue, an oxyalkylene glycol residue or an aryl glycol residue, and a plurality of B2 are the same or different. May be.)

  B2 in the general formula (2) is an aryl monocarboxylic acid residue or an aliphatic monocarboxylic acid residue. Here, the “carboxylic acid residue” refers to a group other than —OH in the carboxy group. When the aryl monocarboxylic acid residue is an aryl monocarboxylic acid residue having 6 to 12 carbon atoms, the raw material is easily available, the esterification reaction is easy, and the cellulose ester resin described later is mixed. Further, it is preferable from the viewpoint of easy balance between moisture resistance and improvement in elastic modulus, for example, benzoic acid, dimethylbenzoic acid, trimethylbenzoic acid, tetramethylbenzoic acid, ethylbenzoic acid, propylbenzoic acid, butylbenzoic acid, cumin Examples thereof include acid, para-tert-butylbenzoic acid, orthotoluic acid, metatoluic acid, p-toluic acid, ethoxybenzoic acid, propoxybenzoic acid, anisic acid, naphthoic acid and the like, and they may be used alone or in combination of two or more. In particular, from the viewpoint of easily expressing the effects of the present invention, a residue of benzoic acid, p-toluic acid, or dimethylbenzoic acid is preferable, and a residue of benzoic acid is more preferable. Here, the number of carbon atoms does not include the carbon atom in the carboxy group. Further, it may be a residue such as nicotinic acid or furoic acid having an aromaticity, which may have a substituent.

  As the aliphatic monocarboxylic acid residue, it is an aliphatic monocarboxylic acid residue having 1 to 8 carbon atoms, which is mixed with raw material availability, ease of esterification reaction, and cellulose ester resin described later. At this time, it is preferable from the viewpoint of easy balance between moisture permeability and improvement in elastic modulus, and examples thereof include residues such as acetic acid, propionic acid, butanoic acid, hexanoic acid, octanoic acid, octylic acid, and the like. It may have both of the above, and is particularly preferably a residue of acetic acid. Here, the number of carbon atoms does not include the carbon atom in the carboxy group.

  G in the general formula (1) 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 expressing 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-dimethylol heptane), 3-methyl-1,5-pentanediol, 1,6-hexanediol, 2,2 4-trimethyl 1,3-pentanediol, 2-ethyl-1,3-hexanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12- Residues such as dodecanediol are mentioned, and they may be used alone or in combination of two or more. Among these, from the viewpoint of improving the strength of the film, 1,2-propylene glycol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 2-methyl-1,3-propane It is preferably a residue of diol 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 expressing the effects of the present invention. For example, diethylene glycol, triethylene glycol, tetraethylene glycol And residues such as dipropylene glycol and tripropylene glycol may be used alone or in combination of two or more.

  The aryl glycol residue is preferably an aryl glycol residue having 6 to 18 carbon atoms from the viewpoint that the effects of the present invention are more easily expressed. For example, hydroquinone, resorcin, bisphenol A, alkylene oxide of bisphenol A Examples include residues such as adducts, bisphenol F, alkylene oxide adducts of bisphenol F, biphenols, alkylene oxide adducts of biphenols, etc., which may be used alone or in combination of two or more.

  From the viewpoint of further manifesting the effects of the present invention, in the general formula (2), B2 is a residue of benzoic acid or acetic acid, G is 1,2-propylene glycol, 1,3-propanediol, 1,2- Preferably, it is a residue of butanediol, 1,3-butanediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, diethylene glycol, or dipropylene glycol.

  The diester compound (II) may be synthesized or commercially available. In the synthesis, the diester compound (II) is produced by using the same method as the esterification reaction described above, and the general It can be obtained by a known method such as a method of isolating the component of n = 0 in the formula (1) using an operation such as distillation or a column, and the method is not limited. In addition, sub-components other than n = 0 component may be contained, and in the mixture after being uniformly mixed with the ester resin (I), a diester can be used as long as the conditions specified in the present invention can be satisfied. A plurality of compounds made of different raw materials may be used as the compound (II).

  The ester resin of the present invention obtained by such a method should be excellent in the balance of moisture permeability, elastic modulus and optical properties of the resulting film by blending it with the resin for optical materials. It can be used as a so-called antiplasticizer, and can be particularly suitably used as an optical film.

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

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

  Examples of the cellulose ester resin include those obtained by esterifying part or all of the hydroxyl groups of cellulose obtained from cotton linter, wood pulp, kenaf, etc. Among them, cellulose obtained from cotton linter A film obtained by using a cellulose ester resin obtained by esterifying is preferable because it can be easily peeled off from a metal support constituting a film production apparatus described later, and the production efficiency of the film can be further improved.

  Examples of the cellulose ester resin include cellulose acetate, cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate phthalate, and cellulose nitrate. When used as a protective film for a polarizing plate, cellulose acetate is used. 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 cellulose acetate preferably has a degree of polymerization in the range of 250 to 400, and an acetylation degree in the range of 54.0 to 62.5% by mass, preferably 58.0 to 62.5. More preferably, it is in the range of mass%. If the cellulose acetate has a polymerization degree and an acetylation degree within a 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 acetylation degree said by this invention is the mass ratio of the acetic acid produced | generated by saponifying this cellulose acetate with respect to the whole quantity of a cellulose acetate.

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

  The optical film in the present invention uses the cellulose ester resin composition containing the ester resin of the present invention and the cellulose ester resin, and uses a resin composition containing other various additives as necessary. Also good.

  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 using an extruder 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 melting and kneading the ester resin, cellulose ester resin, and other additives in advance can be used. However, it can be extruded as it is.

  Examples of the additive include other modifiers other than the ester resin of the present invention, thermoplastic resins, ultraviolet absorbers, matting agents, deterioration inhibitors (for example, antioxidants, peroxide decomposers, radical prohibitions). Agents, metal deactivators, acid scavengers, etc.) and dyes.

  Examples of the other modifiers include ester resins other than the ester resins defined in the present invention, phosphate esters such as triphenyl phosphate (TPP), tricresyl phosphate, and cresyl diphenyl phosphate, dimethyl phthalate, diethyl phthalate, Phthalic acid esters such as dibutyl phthalate and di-2-ethylhexyl phthalate, ethyl phthalyl ethyl glycolate, butyl phthalyl butyl glycolate, trimethylol propane tribenzoate, pentaerythritol tetraacetate, tributyl acetylcitrate, etc. It can be used as long as the effect is not impaired.

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

  The ultraviolet absorber is not particularly limited, and examples thereof include oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex compounds, and the like. It is preferable to use the ultraviolet absorber in a 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, and talc. 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.

  The dye is not particularly limited in terms of type and blending amount as long as the object of the present invention is not impaired.

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

  According to the solution casting method, since the orientation of the cellulose ester resin in the film during molding can be suppressed, the resulting film can exhibit optical isotropy substantially. The film showing optical isotropy can be used for an optical material such as a liquid crystal display, and is particularly useful as a protective film for a polarizing plate. Moreover, the film obtained by the said method cannot form an unevenness | corrugation on the surface, and is excellent in surface smoothness.

  The solution casting method generally includes a first step in which the cellulose ester resin composition is dissolved in an organic solvent, and the resulting resin solution is cast on a metal support, and in the cast resin solution. The second step of distilling off and drying the organic solvent contained in the film to form a film, followed by the third step of peeling the film formed on the metal support from the metal support and drying by heating.

  Examples of the metal support used in the first step include endless belt-shaped or drum-shaped metal supports, for example, stainless steel with a mirror-finished surface can be used. .

  When casting the resin solution on the metal support, it is preferable to use a resin solution filtered with a filter in order to prevent foreign matters from entering the film obtained.

  Although it does not specifically limit as the drying method of the said 2nd process, For example, it includes in the said resin solution cast | casted by applying the wind of the temperature range of 30-50 degreeC to the upper surface and / or lower surface of the said metal support body. The method of evaporating 50-80 mass% of the organic solvent to be formed, and forming a film on the said metal support body is mentioned.

  Next, the third step is a step in which the film formed in the second step is peeled off from the metal support and heat-dried under a temperature condition higher than that in the second step. As the heat drying method, for example, a method in which the temperature is raised stepwise under a temperature condition of 100 to 160 ° C. is preferable because good dimensional stability can be obtained. The organic solvent remaining in the film after the second step can be almost completely removed by heating and drying under the temperature condition.

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

  The organic solvent that can be used when the resin composition is mixed and dissolved in an organic solvent is not particularly limited as long as it can dissolve them. For example, when cellulose acetate is used as a cellulose ester, For example, organic halogen compounds such as methylene chloride and dioxolanes are preferably used.

  In addition, 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.

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

  In the present invention, for example, the unstretched optical film obtained by the above-described method is stretched by uniaxially stretching in the mechanical flow direction and transversely uniaxially stretching in the direction orthogonal to the mechanical flow direction, as necessary. The obtained optical film can be obtained. Moreover, the stretched film biaxially stretched can be obtained by stretching by a sequential biaxial stretching method of roll stretching and tenter stretching, a simultaneous biaxial stretching method by tenter stretching, a biaxial stretching method by tubular stretching, or the like. The draw ratio is preferably 0.1% or more and 1000% or less in at least one direction, more preferably 0.2% or more and 600% or less, and more preferably 0.3% or more and 300% or less. Especially preferred. By designing in this range, a stretched optical film preferable in terms of birefringence, heat resistance and strength can be obtained.

  The optical film of the present invention is excellent in moisture permeation resistance and transparency, and is excellent in elastic modulus. Therefore, it can be used for an optical film of a liquid crystal display device, for example. 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, an antireflective film, an antistatic film, and a color filter. Among these, it can use preferably as a protective film for polarizing plates.

  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 reducing the thickness of the liquid crystal display device, and has sufficient film strength and Rth stability. Excellent performance such as moisture permeability resistance can be maintained.

  The optical film of the present invention is characterized in that the elastic modulus is higher than when no ester resin is blended. In general, a polyester resin blended for the purpose of enhancing the processability of cellulose ester resin is sometimes referred to as “plasticizer”, but the ester resin of the present invention is more optical than plasticizing effect. From the viewpoint of improving the strength of the resin for materials, it has a performance different from the conventional one in that it is used as an antiplasticizer.

  In addition, the polarizing plate protective film can be adjusted to a desired Rth without causing bleed under high temperature and high humidity, so that it can be used widely in various liquid crystal display systems depending on the application. Can do.

  Examples of the liquid crystal display method include IPS (In-Plane Switching), TN (Twisted Nematic), VA (Vertically Aligned), and OCB (Optical Compensatory Bend: An example is Optically Compensatory Bend).

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

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

Example 1
In a 2-liter three-necked flask, 412 g of 1,2-propylene glycol (hereinafter abbreviated as “PG”) as a glycol component, 374 g of isophthalic acid (hereinafter abbreviated as “IPA”) as a dicarboxylic acid component, and benzoic acid as a monocarboxylic acid component 611 g (hereinafter abbreviated as “BzA”) and 0.08 g of tetraisopropyl titanate (hereinafter abbreviated as “TIPT”) as a catalyst were charged, and the temperature was gradually raised to 230 ° C. in a nitrogen stream from a nitrogen introduction tube. A condensation reaction was performed at 230 ° C. for 8 hours, and it was confirmed that the acid value was 1.0 or less. Excess glycol was removed at 195 ° C. under reduced pressure to obtain the ester resin (1) of the present invention. The obtained ester resin (1) was a pale yellow liquid at room temperature, had an acid value of 0.12, a hydroxyl value of 10.0, and a weight average molecular weight of 590. In the GPC measurement, the n = 0 component was 29 area%, and (n ≧ 3) / (n = 0) was 1.0.

Example 2
The ester resin was synthesized in the same manner as in Example 1 using 412 g of PG as the glycol component, 280 g of IPA as the dicarboxylic acid component, 82 g of adipic acid (hereinafter abbreviated as “AA”), BzA611 g and 0.08 g of TIPT as the monocarboxylic acid component. 2) was obtained. The obtained ester resin (2) was a light yellow liquid at room temperature, had an acid value of 0.07, a hydroxyl value of 0.0, and a weight average molecular weight of 780. The n = 0 component in the GPC measurement was 24 area%, and (n ≧ 3) / (n = 0) was 1.1.

Example 3
The ester resin (3) was obtained by synthesizing in the same manner as in Example 1 using PG 412 g as the glycol component, IPA 187 g and AA 164 g as the dicarboxylic acid component, and BzA611 g and TIPT 0.08 g as the monocarboxylic acid component. The obtained ester resin (3) was a light yellow liquid at room temperature, an acid value of 0.05, a hydroxyl value of 1.1, and a weight average molecular weight of 670. The n = 0 component in the GPC measurement was 25 area%, and (n ≧ 3) / (n = 0) was 1.1.

Example 4
The ester resin (4) was obtained by synthesizing in the same manner as in Example 1 using PG 412 g as the glycol component, IPA 94 g and AA 245 g as the dicarboxylic acid component, and BzA611 g and TIPT 0.08 g as the monocarboxylic acid component. The obtained ester resin (4) was a light yellow liquid at room temperature, an acid value of 0.08, a hydroxyl value of 5.4, and a weight average molecular weight of 620. In the GPC measurement, n = 0 component was 31 area%, and (n ≧ 3) / (n = 0) was 0.7.

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

Example 6
As in Example 1, using 488 g of 2-methyl-1,3-propanediol (hereinafter abbreviated as “2MPD”) as the glycol component, IPA 280 g and AA 82 g as the dicarboxylic acid component, and BzA611 g and TIPT 0.08 g as the monocarboxylic acid component. (6) for ester resin was obtained. The obtained ester resin (6) was a light yellow liquid at room temperature, an acid value of 0.11, a hydroxyl value of 12.6, and a weight average molecular weight of 560. In the GPC measurement, the n = 0 component was 40 area%, and (n ≧ 3) / (n = 0) was 0.4.

Comparative Example 1
A 2-liter three-necked flask was charged with PG 437 g as a glycol component, 180 g phthalic acid (hereinafter abbreviated as “PA”) as a dicarboxylic acid component, AA 178 g, and BzA 659 g and TIPT 0.09 g as a monocarboxylic acid component. The temperature was gradually raised to 220 ° C. A condensation reaction was carried out at 220 ° C. for 13 hours, and it was confirmed that the acid value was 1.0 or less. Excess glycol was removed at 195 ° C. under reduced pressure to obtain an ester resin (1 ′) for comparison. The obtained ester resin (1 ′) was a pale yellow liquid at room temperature, had an acid value of 0.09, a hydroxyl value of 1.2, and a weight average molecular weight of 640.

Comparative Example 2
A polyester resin (2 ′) for comparison was obtained by synthesizing in the same manner as in Comparative Example 1 using PG313 g, AA262 g, BzA436 g and TIPT 0.10 g as the glycol component. The obtained polyester resin for comparison (2 ′) was a pale yellow liquid at room temperature, had an acid value of 0.50, a hydroxyl value of 12.6, and a weight average molecular weight of 610.

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

Examples 7-12, Comparative Examples 4-7
<Adjustment of cellulose ester optical film>
Triacetyl cellulose resin ("LT-35" manufactured by Daicel Corporation) 100 parts, ester resins (1) to (6), ester resins (1 ') to (3') 10 parts, methylene chloride 810 parts and methanol 90 In addition to the mixed solvent consisting of parts, it was dissolved to prepare a dope solution that is a cellulose ester resin composition. In Comparative Example 7, an ester resin was not blended, and only a triacetyl cellulose resin was dissolved in a mixed solvent to obtain a dope solution. These dope 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, then dried at 50 ° C. for 30 minutes and further at 120 ° C. for 30 minutes. Thus, an optical film (60 μm or 40 μm) of the present invention was obtained. About the obtained film, the physical property was measured according to the following, and the result was 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-shaped chuck: 100 mm
Test speed: 10 mm / min
It represents that it is a hard film, so that an elasticity modulus is large.

<Measurement of retardation Rth of optical film>
The Rth value at a wavelength of 590 nm was measured using a birefringence measurement apparatus (KOBRA-WR, manufactured by Oji Scientific Instruments) in an environment where the optical film was 23 ° C. and the relative humidity was 55%.

<Measurement of moisture permeability of optical film>
Measurement was performed according to the method described in JIS Z 0208. The measurement conditions were a temperature of 40 ° C. and a relative humidity of 90%. It represents that it is excellent in moisture permeability resistance, so that the value obtained is small.

Claims (9)

The following general formula (1)
B- (GA) _n -GB (1)
[In the formula (1), B is one or more residues selected from the group consisting of acetic acid, benzoic acid, p-toluic acid and dimethylbenzoic acid, G is ethylene glycol, 1,2-propylene glycol, 1,3 -One or more residues selected from the group consisting of propanediol, 1,2-butanediol and 2-methyl-1,3-propanediol, wherein A is succinic acid, adipic acid, dicarboxycyclohexane, phthalic acid , One or more residues selected from the group consisting of terephthalic acid and isophthalic acid, and 20 mol% or more of the total number of moles of A is isophthalic acid, n is the number of repetitions, and , A may be the same or different, and a plurality of B and G may be the same or different. ]
An ester resin represented by
In the GPC measurement, the ratio of the area percentage of the component where n = 0 in the general formula (1) is 10 to 50% and n is 3 or more and the area percentage of the n = 0 component (n ≧ 3) / (n = 0) is antiplasticization agent for an optical material for a resin and an ester resin is 0.2 to 3. Antiplasticization agent according to claim 1, wherein the average value of n in the general formula (1) is 0.2 to 3. Antiplasticization agent according to claim 1 or 2, wherein the weight average molecular weight of the ester resin is in the range of 350 to 1,200. Antiplasticization agent according to any one of claims 1 to 3 25 to 100 mol% total moles of A is isophthalic acid of the general formula (1). The ratio (n ≧ 3) / anti-plasticizer of any one of claims 1~4 (n = 0) is 0.2 to 1.5. Cellulose ester resin composition characterized by containing a antiplasticization agent and the cellulose ester resin of any one of claims 1 to 5.   An optical film comprising the cellulose ester resin composition according to claim 6.   The optical film according to claim 7, which is used for protecting a polarizing plate.   A liquid crystal display device comprising the optical film according to claim 7.