JP2021080419A - Resin composition for optical material, optical film and image display device - Google Patents

Abstract

To provide a resin composition for optical material capable of producing an optical film which suppresses expression of in-plane and out-of-plane phase differences of a cyclic olefin resin without impairing transparency and heat resistance.SOLUTION: A resin composition for optical material contains a cyclic olefin resin, and a polyester resin represented by the following formula (1). In the formula (1), B1 each independently represents an aliphatic monocarboxylic acid residue having 7 to 20 carbon atoms.SELECTED DRAWING: None

Description

The present invention relates to a resin composition for an optical material, an optical film, and an image display device.

A display of a smartphone, a laptop computer, a television, or the like is a laminate of optical films having various functions, and the optical film comprises, for example, a circularly polarizing plate having a function of canceling external light reflection entering the display. Includes a polarizing plate protective film, a touch panel base film that senses changes in capacitance, and the like.
Cellulose acetate film has been conventionally used as the optical film, but the cellulose acetate film has high hygroscopicity, and has problems in performance change and durability under high humidity. Therefore, instead of the cellulose acetate film, a low hygroscopic cyclic olefin resin (cycloolefin polymer, COP) film is being used.

For example, in organic EL displays for smartphones, a structure in which a touch panel is installed inside a circularly polarizing plate has come out in order to further reduce the thickness. In order to achieve a high degree of external light reflection prevention in this configuration, it is necessary to use a film having a small phase difference Rth in the thickness direction as the base film of the touch panel. However, when the cyclic olefin resin has a positive intrinsic birefringence and a phase difference Rth in the thickness direction is likely to occur due to stress generated in the filming process, the cyclic olefin resin film is used as the base film of the touch panel. In addition, there is a problem that the image quality is deteriorated due to light leakage of external light reflection when viewed from an angle.

In the process of manufacturing an optical film, a stretching process is usually carried out in order to improve smoothness and strength. In the cyclic olefin resin film, the resin chains are oriented due to the stress generated during stretching, which is considered to be a factor of Rth expression.
In order to reduce the stress during stretching, there is a method of stretching at a temperature significantly higher than the glass transition temperature of the resin to reduce the Rth, but in that case, there is a problem that the physical properties of the film deteriorate.

When it is difficult to improve the characteristics of the optical film only by changing the manufacturing conditions as described above, there is a method aiming at improving the characteristics by using an additive. As an additive for the cyclic olefin resin film, it has been proposed to use a polyester-based additive for the purpose of suppressing water vapor permeation (Patent Document 1). By adding the polyester-based additive to the cyclic olefin resin film, the obtained film tends to have a low Rth, but the Rth reduction effect is not sufficient. Further, for example, the base film of a touch panel requires high heat resistance (high glass transition temperature) because high temperature treatment is required in the manufacturing process, but the cyclic olefin resin containing a large amount of additives has a glass transition temperature. There is a problem that the heat resistance is impaired due to a large decrease in heat resistance.

JP-A-2018-048250

An object to be solved by the present invention is to provide a resin composition for an optical material capable of producing an optical film in which the development of in-plane and out-of-plane retardation of a cyclic olefin resin is suppressed without impairing transparency and heat resistance. That is.

As a result of diligent studies to solve the above problems, the present inventors have made a resin composition for an optical material containing a polyester resin having an aliphatic monocarboxylic acid residue having 7 to 20 carbon atoms and a cyclic olefin resin. If this is the case, it has been found that an optical film in which the on-plane and out-of-plane retardation is suppressed without impairing the transparency and heat resistance can be obtained, and the present invention has been completed.

That is, the present invention relates to a resin composition for an optical material containing a cyclic olefin resin and a polyester resin represented by the following formula (1).

（前記式（１）中、
Ｂ_１は、それぞれ独立に、炭素原子数７〜２０の脂肪族モノカルボン酸残基を表す。
Ｇは、炭素原子数２〜１５のアルキレングリコール残基、炭素原子数４〜１２のオキシアルキレングリコール残基、又はポリオキシアルキレングリコール残基を含む２価の連結基を表す。
Ａは、炭素原子数２〜１２のアルキレンジカルボン酸残基又は炭素原子数６〜１２のアリールジカルボン酸残基を表す。
ｍは括弧で括られた繰り返し単位数を表し、ｍは０以上の整数である。
括弧で括られた繰り返し単位毎にＡ及びＧはそれぞれ同一でもよく、異なっていてもよい。）

(In the above formula (1),
B ₁ independently represents an aliphatic monocarboxylic acid residue having 7 to 20 carbon atoms.
G represents a divalent linking group containing an alkylene glycol residue having 2 to 15 carbon atoms, an oxyalkylene glycol residue having 4 to 12 carbon atoms, or a polyoxyalkylene glycol residue.
A represents an alkylene dicarboxylic acid residue having 2 to 12 carbon atoms or an aryl dicarboxylic acid residue having 6 to 12 carbon atoms.
m represents the number of repeating units enclosed in parentheses, and m is an integer of 0 or more.
A and G may be the same or different for each repeating unit enclosed in parentheses. )

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a resin composition for an optical material capable of producing an optical film in which the occurrence of in-plane and out-of-plane retardation is suppressed without impairing transparency and heat resistance.

Hereinafter, an embodiment of the present invention will be described. The present invention is not limited to the following embodiments, and can be carried out with appropriate modifications as long as the effects of the present invention are not impaired.
As used herein, the term "(meth) acrylic acid" refers to one or both of acrylic acid and methacrylic acid.

[Resin composition for optical materials]
The resin composition for an optical material of the present invention contains a cyclic olefin resin and a polyester resin, and the polyester resin is a polyester resin having an aliphatic monocarboxylic acid residue having 7 to 20 carbon atoms.
In the resin composition for optical materials of the present invention, the polyester resin can exhibit high motility by introducing an aliphatic monocarboxylic acid residue having 7 to 20 carbon atoms, and the polyester resin causes a cyclic olefin. The orientation of the main chain of the resin can be effectively disturbed. As a result, relaxation of the optical film after stretching is promoted, and an optical film in which in-plane and out-of-plane retardation is suppressed can be obtained.
Further, since the polyester resin having an aliphatic monocarboxylic acid residue having 7 to 20 carbon atoms has high motility, the effect can be exhibited even if a small amount is added, and the transparency and heat resistance of the obtained optical film are impaired. There is no such thing.

Hereinafter, each component contained in the resin composition for an optical material of the present invention will be described.
(Cyclic olefin resin (A))
The cyclic olefin resin (A) is a polymer compound having a main chain composed of carbon-carbon bonds and having a cyclic hydrocarbon structure in at least a part of the main chain, and has a cyclic hydrocarbon structure such as norbornene or tetracyclododecene. It is a polymer compound having a structural unit derived from a compound (cyclic olefin) having at least one polymerizable carbon-carbon unsaturated bond therein.
The structure of the cyclic olefin resin (A) is not particularly limited and may be chain-like, branched or crosslinked, but is preferably linear.

The cyclic olefin resin (A) is, for example, an addition (co) polymer of a cyclic olefin or a hydrogenated product thereof (1), an addition copolymer of a cyclic olefin and an α-olefin or a hydrogenated product thereof (2), a cyclic olefin. It is classified into a ring-opening (co) polymer of the above or a hydrogenated product thereof (3).

Examples of the cyclic olefin include cyclopentene, cyclohexene, cyclooctene; and monocyclic cyclic olefins such as cyclopentadiene and 1,3-cyclohexadiene;
Bicyclo [2.2.1] hepta-2-ene (trivial name: norbornene), 5-methyl-bicyclo [2.2.1] hepta-2-ene, 5,5-dimethyl-bicyclo [2.2. 1] Hept-2-ene, 5-ethyl-bicyclo [2.2.1] hepta-2-ene, 5-butyl-bicyclo [2.2.1] hepta-2-ene, 5-ethylidene-bicyclo [ 2.2.1] Hept-2-ene, 5-hexyl-bicyclo [2.2.1] hepta-2-ene, 5-octyl-bicyclo [2.2.1] hepta-2-ene, 5- Octadecyl-bicyclo [2.2.1] hepta-2-ene, 5-methylidene-bicyclo [2.2.1] hepta-2-ene, 5-vinyl-bicyclo [2.2.1] hepta-2- Bicyclic olefins such as ene, 5-propenyl-bicyclo [2.2.1] hepta-2-ene;

Tricyclo [4.3.0.12.5] deca-3,7-diene (trivial name: dicyclopentadiene), tricyclo [4.3.0.12.5] deca-3-ene; tricyclo [4. 4.0.12.5] Undeca-3,7-diene or tricyclo [4.4.0.12.5] Undeca-3,8-diene or partial hydrogenation of these (or addition of cyclopentadiene and cyclohexene) Tricyclo [4.4.0.12.5] undeca-3-ene; 5-cyclopentyl-bicyclo [2.2.1] hepta-2-ene, 5-cyclohexyl-bicyclo [2.2. 1] Three-ring cyclic olefins such as hepta-2-ene, 5-cyclohexenylbicyclo [2.2.1] hepta-2-ene, 5-phenyl-bicyclo [2.2.1] hepta-2-ene, etc. ;

Tetracyclo [4.4.0.12.5.17.10] dodeca-3-ene (tetracyclododecene), 8-methyltetracyclo [4.4.0.12.5.17.10] dodeca- 3-ene, 8-ethyltetracyclo [4.4.0.12.5.17.10] Dodeca-3-ene, 8-methylidenetetracyclo [4.4.0.12.5.17.10] ] Dodeca-3-ene, 8-ethylidenetetracyclo [4.4.0.12.5.17.10] Dodeca-3-ene, 8-vinyltetracyclo [4.4.0.12.5.17] .10] 4-ring cyclic olefins such as dodeca-3-ene and 8-propenyl-tetracyclo [4.4.0.12.5.17.10] dodeca-3-ene;

8-Cyclopentyl-tetracyclo [4.4.0.12.5.17.10] dodeca-3-ene, 8-cyclohexyl-tetracyclo [4.4.0.12.5.17.10] dodeca-3-en En, 8-cyclohexenyl-tetracyclo [4.4.0.12.5.17.10] Dodeca-3-ene, 8-phenyl-cyclopentyl-tetracyclo [4.4.0.12.5.17.10] ] Dodeca-3-ene; Tetracyclo [7.4.13.6.01.9.02.7] Tetradeca-4,9,11,13-Tetraene (1,4-methano-1,4,4a, 9a) -Tetrahydrofluorene), Tetracyclo [8.4.14.7.01.10.03.8] Pentadeca-5,10,12,14-Tetraene (1,4-methano-1,4,4a, 5,10) , 10a-hexahydroanthracene); pentacyclo [6.6.1.13.62.02.7.09.14] -4-hexadecene, pentacyclo [6.5.1.13.62.02.7. 09.13] -4-pentadecene, pentacyclo [7.4.0.02.7.13.6.110.13] -4-pentadecene; heptacyclo [8.7.0.12.99.14.7. 111.17.03.8.8.012.16] -5-eikosen, heptacyclo [8.7.0.12.93.03.8.14.7.7.012.17.1113.16]-14-eikosen; Examples thereof include polycyclic cyclic olefins such as cyclopentadiene tetramers.
Each of these cyclic olefins can be used alone or in combination of two or more.

Specific examples of the α-olefin copolymerizable with the cyclic olefin include, for example, ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 3-methyl-1-butene, and 3-methyl-1-. Penten, 3-ethyl-1-pentene, 4-methyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-hexene, 4,4-dimethyl-1-pentene, 4-ethyl -1-Hexene, 3-ethyl-1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, etc. Examples thereof include ethylene and α-olefin.
These α-olefins can be used individually by 1 type or in combination of 2 or more types.
The amount of these α-olefins used is, for example, in the range of 5 to 200 mol% with respect to the cyclic olefin.

The polymerization method of the cyclic olefin or the cyclic olefin and the α-olefin and the hydrogenation method of the obtained polymer are not particularly limited, and can be carried out according to a known method.

The cyclic olefin resin (A) may have a polar group such as a carboxyl group, an acid anhydride group, an epoxy group, an amide group, an ester group, or a hydroxyl group.
When the cyclic olefin resin (A) has a polar group, a laminated film in which another film such as an acrylic resin film or a cellulose ester resin film and an optical film of the present invention are laminated via an adhesive layer is produced. An optical film having good adhesion to the adhesive layer can be obtained.

The cyclic olefin resin having a polar group is, for example, not having a polar group when producing a cyclic olefin resin (A) in which an unsaturated compound having a polar group is graft-polymerized after producing the cyclic olefin resin (A). It can be obtained by a method such as including a saturated compound in the reaction raw material of the cyclic olefin resin.

Examples of the unsaturated compound having a polar group include (meth) acrylic acid, maleic acid, maleic anhydride, itaconic anhydride, glycidyl (meth) acrylate, (meth) acrylic acid alkyl ester, and maleic acid alkyl ester. Examples thereof include meth) acrylamide and -2-hydroxyethyl (meth) acrylate.

When a polar group is introduced into the cyclic olefin resin (A), the amount of the polar group introduced is such that another film such as an acrylic resin film or a cellulose ester resin film and the optical film of the present invention are laminated via an adhesive layer. When producing a film, it is preferable that the amount is 0.1 to 1 mol per 1 kg of the cyclic olefin resin (A) because an optical film having good adhesion to the adhesive layer can be obtained.

The cyclic olefin resin (A) is preferably a resin containing at least one of the repeating units represented by the following formulas (A-1) to (A-15).

The number average molecular weight (Mn) of the cyclic olefin resin (A) is preferably 5,000 to 300,000, preferably 10,000 to 150,000, because an optical film having excellent strength and easy to manufacture can be obtained. More preferably, 15,000 to 150,000 is even more preferable.

In the present invention, the weight average molecular weight (Mw) and the number average molecular weight (Mn) are polystyrene-equivalent values based on gel permeation chromatography (GPC) measurement. The measurement conditions of GPC are as follows.

[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

As the cyclic olefin resin (A), a commercially available product can be used, and the commercially available products include APL5014DP, APL6011T, APL6013T, APL6015T, APL5514ML, APL6013T (all manufactured by Mitsui Chemicals, Inc.); D5450, D4540, D4531, D4531F, D4532, D4520, F5023, F4520, G7810, RH5200, FX4727 (all manufactured by JSR Corporation); ZEONEX K26R, ZEONEX K22R, ZEONEX E48R, ZEONEX E48R, ZEONEX F52R, ZEONEX (Made by Co., Ltd.), etc.

(Polyester resin (B))
The polyester resin (B) is a polyester resin represented by the following formula (1).

（前記式（１）中、
Ｂ_１は、それぞれ独立に、炭素原子数７〜２０の脂肪族モノカルボン酸残基を表す。
Ｇは、炭素原子数２〜１５のアルキレングリコール残基、炭素数原子数４〜１２のオキシアルキレングリコール残基、又はポリオキシアルキレングリコール残基を含む２価の連結基を表す。
Ａは、炭素原子数２〜１２のアルキレンジカルボン酸残基又は炭素原子数６〜１２のアリールジカルボン酸残基を表す。
ｍは括弧で括られた繰り返し単位数を表し、ｍは０以上の整数である。
括弧で括られた繰り返し単位毎にＡ及びＧはそれぞれ同一でもよく、異なっていてもよい。）

(In the above formula (1),
B ₁ independently represents an aliphatic monocarboxylic acid residue having 7 to 20 carbon atoms.
G represents a divalent linking group containing an alkylene glycol residue having 2 to 15 carbon atoms, an oxyalkylene glycol residue having 4 to 12 carbon atoms, or a polyoxyalkylene glycol residue.
A represents an alkylene dicarboxylic acid residue having 2 to 12 carbon atoms or an aryl dicarboxylic acid residue having 6 to 12 carbon atoms.
m represents the number of repeating units enclosed in parentheses, and m is an integer of 0 or more.
A and G may be the same or different for each repeating unit enclosed in parentheses. )

Two B ₁ represents, it may be the same as one another or different.
When there are two or more A's, the two or more A's may be the same or different from each other.
When there are two or more Gs, the two or more Gs may be the same or different from each other.

In the polyester resin represented by the formula (1), when m = 0, it is the following formula (1-1) diester compound, and the polyester resin (B) contains the diester compound.

（前記式（１−１）中、Ｂ_１及びＧは前記式（１）と同じである。）

(In the above formula (1-1), B ₁ and G are the same as the above formula (1).)

In the present invention, the "carboxylic acid residue" refers to the remaining organic group excluding the carboxyl group of the carboxylic acid. Regarding the number of carbon atoms of the "carboxylic acid residue", it is assumed that the carbon atom in the carboxy group is not included.
In the present invention, the "alcohol residue" refers to the remaining organic group obtained by removing the hydroxyl group from the alcohol.
In the present invention, the "glycol residue" refers to the remaining organic group obtained by removing the hydroxyl group from the glycol.

Examples of the aliphatic monocarboxylic acid residue having 7 to 20 carbon atoms of B ₁ include caprylic acid residue, capric acid residue, lauric acid residue, myristic acid residue, pentadecic acid residue, and particic acid residue. , Margaric acid residue, stearic acid residue, arachidic acid residue and the like.

B ₁ is preferably an aliphatic monocarboxylic acid residue having 11 to 17 carbon atoms, and more preferably a lauric acid residue, a myristic acid residue, a palmitic acid residue or a stearic acid residue.
Of the two B ₁ of polyester resin represented by the formula (1), at least one can improve the motility of the polyester resin by an aliphatic monocarboxylic acid residue having 11 to 17 carbon atoms.

Examples of the alkylene dicarboxylic acid residue having 2 to 12 carbon atoms of A include succinic acid residue, maleic acid residue, fumaric acid residue, glutaric acid residue, adipic acid residue, azelaic acid residue, and sebacic acid. Examples thereof include acid residues, dodecanedicarboxylic acid residues, cyclohexanedicarboxylic acid residues, and hexahydrophthalic acid residues.

Examples of the aryldicarboxylic acid residue having 6 to 12 carbon atoms of A include a phthalic acid residue, a terephthalic acid residue, an isophthalic acid residue, a dimethyl terephthalate residue, and a 2,6-naphthalenedicarboxylic acid residue. 1,5-naphthalenedicarboxylic acid residue, 1,4-naphthalenedicarboxylic acid residue, 2,6-naphthalenedicarboxylic acid dimethyl residue, 1,5-naphthalenedicarboxylic acid dimethyl residue, 1,4-naphthalenedicarboxylic acid dimethyl Residues and the like can be mentioned.

A is preferably an alkylene dicarboxylic acid residue having 4 to 12 carbon atoms, more preferably an alkylene dicarboxylic acid residue having 7 to 12 carbon atoms, and further preferably an alkylene dicarboxylic acid having 8 to 12 carbon atoms. It is an acid residue, and particularly preferably an azelaic acid residue, a sebacic acid residue, or a dodecanedioic acid residue.
By setting A as described above, the motility of the polyester resin can be enhanced.

Examples of the alkylene glycol residue having 2 to 15 carbon atoms of G include ethylene glycol residue, 1,2-propylene glycol residue, 1,3-propylene glycol residue, and 1,2-butanediol residue. 1,3-Butanediol residue, 2-methyl-1,3-propanediol residue, 1,4-butanediol residue, 1,5-pentanediol residue, 2,2-dimethyl-1,3- Propanediol (neopentyl glycol) residue, 2,2-diethyl-1,3-propanediol (3,3-dimethyrolepentane) residue, 2-n-butyl-2-ethyl-1,3 propanediol ( 3,3-Dimethylol heptane) residue, 3-methyl-1,5-pentanediol residue, 1,6-hexanediol residue, cyclohexanedimethanol residue, 2,2,4-trimethyl 1,3- Pentandiol residue, 2-ethyl-1,3-hexanediol residue, 2-methyl-1,8-octanediol residue, 1,9-nonanediol residue, 1,10-decanediol residue, 1 , 12-Dodecanediol residue, 2,2'-bis (4-hydroxycyclohexyl) propane residue (hydrogenated bisphenol A residue) and the like. Of these, 1,2-propylene glycol residues, 1,3-propylene glycol residues, and 3-methyl-1,5-pentanediol residues are preferable.

Examples of the oxyalkylene glycol residue having 4 to 12 carbon atoms of G include a diethylene glycol residue, a triethylene glycol residue, a tetraethylene glycol residue, a dipropylene glycol residue, and a tripropylene glycol residue. ..

The divalent linking group containing the polyoxyalkylene glycol residue of G is, for example, an organic group containing a structure represented by the following formula (B-1), preferably represented by the following formula (B-1). It is an organic group, more preferably a polyethylene glycol residue, a polypropylene glycol residue, a polytetramethylene glycol residue, a polytetramethylene ether glycol residue or a polyneopentyl glycol residue.
The total number of carbons constituting the polyoxyalkylene glycol residue represented by the formula (B-1) is preferably 13 or more.

（前記式（Ｂ−１）中、
Ｒ_１は炭素原子数１〜６のアルキレン基である。
ｘは繰り返し数であり、ｘは例えば４以上の整数であり、好ましくは５以上の整数であり、より好ましくは８以上の整数である。ｘの上限は例えば６０である。
複数のＲ_１はそれぞれ同一でもよく、異なっていてもよい。）

(In the above formula (B-1),
R ₁ is an alkylene group having 1 to 6 carbon atoms.
x is the number of repetitions, and x is, for example, an integer of 4 or more, preferably an integer of 5 or more, and more preferably an integer of 8 or more. The upper limit of x is, for example, 60.
The plurality of R _1s may be the same or different. )

The divalent linking group containing the polyoxyalkylene glycol residue of G may be an organic group in which two polyoxyalkylene structures are bonded by a linking group containing an ether bond, and the organic group may be, for example, the following formula (B-). It is an organic group represented by 2).

（前記式（Ｂ−２）中、
Ｒ_１はそれぞれ独立に炭素原子数１〜６のアルキレン基である。
ｐ及びｑはそれぞれ括弧で括られた繰り返し単位数を表し、ｐ及びｑはそれぞれ独立に２以上の整数である。
Ｘはアルキレン基及びアリーレン基からなる群から選択される１種以上が連結した連結基である。
複数のＲ_１はそれぞれ同一でもよく、異なっていてもよい。）

(In the above formula (B-2),
R ₁ is an alkylene group having 1 to 6 carbon atoms independently.
p and q each represent the number of repeating units enclosed in parentheses, and p and q are independently integers of 2 or more.
X is a linking group in which one or more selected from the group consisting of an alkylene group and an arylene group are linked.
The plurality of R _1s may be the same or different. )

In the above formula (B-2), the alkylene group of X is, for example, an alkylene group having 1 to 6 carbon atoms, and the arylene group of Y is, for example, a phenylene group.

Specific examples of the organic group represented by the above formula (B-2) include a residue of a diol obtained by ring-opening addition of tetrahydrofuran to a hydroxyl group of neopentyl glycol, and a residue of a diol obtained by adding ethylene oxide to bisphenol A. Group etc. can be mentioned.

The molecular weight of the polyoxyalkylene glycol residue portion of the divalent linking group containing the polyoxyalkylene glycol residue contained in the polyester resin (B) is preferably 300 to 2000.
When the molecular weight of the polyoxyalkylene glycol residue is in the above range, the polyester resin B can be expected to have an Rth reducing effect due to high motility, and the transparency of the cyclic olefin resin can be easily maintained.

Regarding m in the above formula (1), the upper limit of m is not particularly limited, but is, for example, 15.
The polyester resin (B) is usually included in the resin composition for an optical material of the present invention as a mixture of polyester resins having different m in the formula (1). At this time, the average value of m is, for example, 0 to 9.
The average value of m can be confirmed from the number average molecular weight of polyester (B).

The number average molecular weight (Mn) of the polyester resin (B) is, for example, 300 to 4000, preferably 300 to 3700, and more preferably 1000 to 3600.
When the number average molecular weight (Mn) of the polyester resin (B) is in the above range, sufficient compatibility with the cyclic olefin resin can be obtained, and the transparency of the obtained optical film can be ensured.

The acid value of the polyester resin (B) is preferably 5 or less, more preferably 2 or less, because an optical film having sufficient strength can be obtained without decomposing the cyclic olefin resin (A).
The hydroxyl value of the polyester resin (B) is preferably 50 or less, more preferably 20 or less, because a resin composition for an optical material having excellent heat stability during film formation can be obtained.
The acid value and hydroxyl value of the polyester resin (B) are confirmed by the method described in Examples.

The properties of the polyester resin (B) vary depending on the number average molecular weight, composition, and the like, but are usually liquid, solid, paste, or the like at room temperature.

The content of the polyester resin (B) in the resin composition for an optical material of the present invention is, for example, 0.01 to 8 parts by mass, preferably 0.05 to 5 parts by mass, based on 100 parts by mass of the cyclic olefin resin. It is more preferably 0.1 to 5 parts by mass, further preferably 0.5 to 5 parts by mass, and particularly preferably 0.7 to 5 parts by mass.
The polyester resin (B) can exhibit a sufficient effect even if it is added in a small amount, and when the content of the polyester resin (B) is in the above range, it is in-plane without impairing transparency and heat resistance. And an optical film in which the occurrence of out-of-plane phase difference is suppressed can be obtained.

The polyester resin (B) contains, for example, an aliphatic monocarboxylic acid having 8 to 21 carbon atoms; an alkylene glycol having 2 to 15 carbon atoms, an oxyalkylene glycol having 4 to 12 carbon atoms, and a polyoxyalkylene structure. One or more glycols selected from the group consisting of glycols; and one or more dicarboxylic acids selected from the group consisting of alkylenedicarboxylic acids having 4 to 14 carbon atoms and aryldicarboxylic acids having 8 to 14 carbon atoms. It is obtained as a reaction raw material.
When the polyester resin (B) is a diester compound represented by the above formula (1-1), for example, an aliphatic monocarboxylic acid having 8 to 21 carbon atoms; and an alkylene glycol having 2 to 15 carbon atoms, It is obtained by using one or more kinds of glycols selected from the group consisting of oxyalkylene glycols having 4 to 12 carbon atoms and glycols having a polyoxyalkylene structure as reaction raw materials.
Here, the reaction raw material means a raw material constituting the polyester resin (B), and does not contain a solvent or a catalyst that does not constitute the polyester resin (B).

Hydrogenated vegetable oil fatty acids may be used as the aliphatic monocarboxylic acid used in the production of the polyester resin (B). Examples of the hydrogenated vegetable oil fatty acid include hydrogenated coconut oil fatty acid, hydrogenated palm kernel oil fatty acid, hydrogenated palm oil fatty acid, hydrogenated olive oil fatty acid, hydrogenated castor oil fatty acid, hydrogenated rapeseed oil fatty acid and the like. These are obtained by hydrogenating oils obtained from palm, palm kernel, palm, olive, castor oil, and rapeseed, respectively, and all of them contain two or more kinds of aliphatic monocarboxylic acids having 8 to 21 carbon atoms. Is a mixture of long-chain aliphatic monocarboxylic acids.
As the aliphatic monocarboxylic acid used in the production of the polyester resin (B), the above-mentioned vegetable oil fatty acid to which hydrogenation has not been added may be used as long as the effect of the present invention is not impaired. Further, the vegetable oil fatty acid is not limited to the above.

When the hydrogenated vegetable oil fatty acid is used as the aliphatic monocarboxylic acid used in the production of the polyester resin (B), the obtained polyester resin (B) is two or more kinds of polyester resins represented by the formula (1). Obtained as a mixture of.

The method for producing the polyester resin (B) is not particularly limited. The polyester resin (B) can be produced by a known method, for example, by the following production method.

The polyester resin (B) represented by the formula (1) and having m of 1 or more in the formula can be obtained, for example, by the method shown below.
Method 1: A method in which monocarboxylic acid, dicarboxylic acid and glycol constituting each residue of the polyester resin represented by the formula (1) are collectively charged and reacted.
Method 2: The dicarboxylic acid and glycol constituting each residue of the polyester resin represented by the formula (1) are reacted under the condition that the equivalent of the hydroxyl group is larger than the equivalent of the carboxyl group to make the hydroxyl group the main chain. after obtaining a polyester resin having a terminal, a method of reacting a monocarboxylic acid constituting the obtained polyester resin and B _1.

The polyester resin represented by the general formula (1) and in which m in the formula is 0 can be obtained, for example, by the method shown below.
Method 3: A method in which monocarboxylic acid and glycol constituting each residue of the polyester resin represented by the formula (1) are charged so that the equivalent of the hydroxyl group is larger than the equivalent of the carboxyl group, and these are reacted.

In the production of the polyester resin (B), the reaction of the raw materials may be carried out in the presence of an esterification catalyst, for example, in the temperature range of 180 to 250 ° C. for 10 to 25 hours.
The conditions such as the temperature and time of the esterification reaction are not particularly limited and may be set as appropriate.

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.

(Other ingredients)
The resin composition for an optical material of the present invention may include a cyclic olefin resin (A) and a polyester resin (B), and may further contain other components (arbitrary resin component and arbitrary additive) other than these components. Good.

Examples of the optional resin component include polyolefins such as polyethylene and polypropylene; thermoplastic resins such as polyamide, polyphenylene sulfide resin, polyether ether ketone resin, polysulfone, polyphenylene oxide, polyimide, polyetherimide, and polyacetal; and phenol resin. , Thermocurable resins such as melamine resin, silicone resin, epoxy resin, polyester resins other than the polyester resin represented by the above formula (1), and the like. These resin components may be contained alone or in combination of two or more.

The optional additives include, for example, inorganic fillers, pigments such as iron oxide; lubricants such as stearic acid, behenic acid, zinc stearate, calcium stearate, magnesium stearate, ethylene bisstearoamide; mold release agents; Softeners and plasticizers for paraffin-based process oils, naphthen-based process oils, aromatic process oils, paraffins, organic polysiloxanes, mineral oils, etc .; hindered phenol-based antioxidants, phosphorus-based heat stabilizers, lactone-based heat stabilizers Antioxidants such as agents, vitamin E-based heat stabilizers; light stabilizers such as hindered amine-based light stabilizers and benzoate-based light stabilizers; benzophenone-based ultraviolet absorbers, triazine-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, etc. UV absorbers; flame retardants; antistatic agents; reinforcing agents such as organic fibers, glass fibers, carbon fibers, metal whiskers; colorants, other additives, or mixtures thereof.

The resin composition for optical materials of the present invention contains, for example, 70% by mass or more, 80% by mass or more, 90% by mass or more, 95% by mass or more, 99% by mass or more, or 99.9% by mass or more, which is a cyclic olefin resin. It may be (A), a polyester resin (B), or a solvent.
The resin composition for an optical material of the present invention may essentially consist of a cyclic olefin resin (A), a polyester resin (B), and a solvent. In this case, unavoidable impurities may be contained.
Further, the resin composition for an optical material of the present invention may consist only of a cyclic olefin resin (A), a polyester resin (B) and a solvent.

The method for producing the resin composition for an optical material of the present invention is not particularly limited. For example, a cyclic olefin resin (A), a polyester resin (B), and, if necessary, the above other components are melt-kneaded using a single-screw extruder, a twin-screw extruder, a Banbury mixer, a lavender, various kneaders, or the like. It can be obtained by a method of melt-kneading.
Further, the resin composition for an optical material of the present invention can also be obtained as a solution by dissolving the cyclic olefin resin (A), the polyester resin (B), and the above other components in an organic solvent, if necessary. As the organic solvent, for example, an organic solvent used for obtaining a dope solution containing a cyclic olefin resin (A) and a polyester resin (B) in a solution flow method (solvent casting method) described later can be used.

[Optical film]
The optical film of the present invention can be obtained by using the resin composition for an optical material of the present invention.
The optical film of the present invention has high transparency and can suppress the occurrence of in-plane and out-of-plane retardation. Further, by using the resin composition for an optical material of the present invention, for example, film shrinkage due to heating in a drying step and an annealing step during production can be prevented, and the optical film of the present invention is also excellent in heat resistance.

The optical film of the present invention can suppress the occurrence of in-plane and out-of-plane retardation. Here, the in-plane retardation (Re) and the thickness direction retardation (Rth) are defined by the following equations.
Re = (nx-ny) x d
Rth = ((nx + ny) / 2) -nz) x d
(In the formula, nx is the main refractive index in the x direction when x is the direction in which the refractive index is maximized in the optical film plane.
ny is the main refractive index in the y direction when the direction perpendicular to the x direction in the plane of the optical film is y.
nz is the main refractive index in the thickness direction of the optical film.
d is the thickness (nm) of the optical film. )

The optical film of the present invention contains, for example, 70% by mass or more, 80% by mass or more, 90% by mass or more, 95% by mass or more, 99% by mass or more, or 99.9% by mass or more of the cyclic olefin resin (A) and It may be made of polyester resin (B).
The optical film of the present invention may be essentially composed of a cyclic olefin resin (A) and a polyester resin (B). In this case, unavoidable impurities may be contained.
Further, the optical film of the present invention may consist only of the cyclic olefin resin (A) and the polyester resin (B).

As an optical material, the optical film of the present invention is a polarizing plate protective film, 1/4 wavelength plate, 1/2 wavelength used 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 plate, a viewing angle control film, a retardation film such as a liquid crystal optical compensation film, a display front plate, a light reflection prevention member, a base film for a touch panel sensor, and the like.

The film thickness of the optical film of the present invention 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.

The optical film of the present invention can be produced by using the resin composition for an optical material of the present invention.
The optical film of the present invention can be obtained, for example, by producing an unstretched film by a method such as extrusion molding or cast molding using the resin composition for an optical material of the present invention, and stretching the unstretched film.

Examples of the method for producing an unstretched film include a solution casting method (solvent casting method), which is cast molding. Hereinafter, the solution casting method will be described in detail.
The unstretched film obtained by the solution casting method exhibits substantially optical isotropic properties. 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 includes, for example, a first step of dissolving a cyclic olefin resin (A) and a polyester resin (B) in a solvent and casting the obtained resin solution on a metal support, and casting. The second step of distilling off the organic solvent contained in the resin solution and drying to form a film, followed by the third step of peeling the film formed on the metal support from the metal support and heating and drying it. It consists of processes.

The organic solvent that can be used when the cyclic olefin resin (A) and the polyester (B) are mixed with an organic solvent and dissolved is not particularly limited as long as they can be dissolved, but for example, chloroform, methylene dichloride, etc. A solvent such as methylene chloride can be mentioned.

The concentration of the cyclic olefin resin (A) in the resin solution is preferably 10 to 50% by mass, more preferably 15 to 35% by mass.

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

When the resin solution is cast on the metal support, it is preferable to use a resin solution filtered 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 solvent can be recovered and reused in the first to third steps.

The optical film of the present invention can be obtained by stretching the obtained unstretched film. Specifically, the optical film of the present invention can be obtained by stretching uniaxially in the vertical direction in the mechanical flow direction or uniaxially stretching in the direction perpendicular to the mechanical flow direction. The present invention can also be obtained by biaxially stretching the obtained unstretched film 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. Optical film can be obtained.

The draw ratio in stretching 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 0.3% or more and 300% or less. Is even more preferable. By setting the draw ratio within this range, a stretched optical film preferable from the viewpoints of birefringence, heat resistance, and strength can be obtained.

The molded product obtained from the resin composition for an optical material of the present invention is not limited to an optical film, and in the fields of optical communication systems, optical exchange systems, and optical measurement systems, waveguides, lenses, optical fibers, base materials for optical fibers, and the like. It can also be used as a coating material, an LED lens, a lens cover, and the like.

Hereinafter, the present invention will be described in more detail based on Examples and Comparative Examples. The present invention is not limited to the following examples.

Synthesis example 1
808 g of sebacic acid and 380 g of propylene glycol are placed in a 4-neck flask with an internal volume of 2 liters equipped with a thermometer, a stirrer and a reflux condenser, and the temperature is gradually raised to 220 ° C. while stirring under a nitrogen stream. It was warm. Next, 410 g of hydrogenated coconut oil fatty acid (manufactured by New Japan Chemical Co., Ltd.) and 0.1 g of tetraisopropyl titanate as an esterification catalyst were added and reacted at 220 ° C. until the acid value became 2 or less, and the produced water was continuously produced. Was removed. After the reaction, the mixture was distilled off under reduced pressure at the same temperature to obtain a polyester resin B-1 as a viscous liquid.

The hydrogenated coconut oil fatty acid contains 5% by mass of octanoic acid (8 carbon atoms), 5% by mass of caprylic acid (10 carbon atoms), 51% by mass of lauric acid (12 carbon atoms), and myristic acid (carbon). It is a mixture of aliphatic monocarboxylic acids containing 18% by mass of number 14), 10% by mass of palmitic acid (16 carbon atoms), and 11% by mass of octadecanoic acid (18 carbon atoms). As the average molecular weight of the hydrogenated coconut oil fatty acid as a mixture, a value calculated from the content and molecular weight of each of the above-mentioned fatty acids was used.

When the acid value and the hydroxyl value of the obtained polyester resin B-1 were evaluated by a method according to JIS K 0070-1992, the acid value was 1.0 mgKOH / g and the hydroxyl value was 14 mgKOH / g.
The number average molecular weight (Mn) of the obtained polyester resin B-1 was evaluated by the above method and found to be 1800.

Synthesis example 2
A four-necked flask with an internal volume of 1 liter equipped with a thermometer, a stirrer and a reflux condenser is charged with 455 g of sebacic acid and 230 g of propylene glycol, and gradually rises to 220 ° C. while stirring under a nitrogen stream. It was warm. Next, 180 g of lauric acid and 0.04 g of tetraisopropyl titanate as an esterification catalyst were added and reacted at 220 ° C. until the acid value became 2 or less, and the water produced was continuously removed. After the reaction, the mixture was distilled off under reduced pressure at the same temperature to obtain a polyester resin B-2 which is a viscous liquid.
As a result of evaluating the obtained polyester resin B-2 in the same manner as in Synthesis Example 1, the acid value was 0.6 mgKOH / g, the hydroxyl value was 11 mgKOH / g, and the number average molecular weight (Mn) was 1900.

Synthesis example 3
A four-necked flask with an internal volume of 3 liters equipped with a thermometer, a stirrer and a reflux condenser is charged with 1597 g of sebacic acid and 752 g of propylene glycol, and gradually rises to 220 ° C. while stirring under a nitrogen stream. It was warm. Next, 372 g of lauric acid and 0.14 g of tetraisopropyl titanate as an esterification catalyst were added and reacted at 220 ° C. until the acid value became 2 or less, and the water produced was continuously removed. After the reaction, the mixture was distilled off under reduced pressure at the same temperature to obtain a polyester resin B-3 which is a viscous liquid.
As a result of evaluating the obtained polyester resin B-3 in the same manner as in Synthesis Example 1, the acid value was 0.6 mgKOH / g, the hydroxyl value was 13 mgKOH / g, and the number average molecular weight (Mn) was 2800.

Synthesis example 4
A four-necked flask with an internal volume of 3 liters equipped with a thermometer, a stirrer and a reflux condenser is charged with 1555 g of sebacic acid and 734 g of propylene glycol, and gradually rises to 220 ° C. while stirring under a nitrogen stream. It was warm. Next, 280 g of lauric acid and 0.13 g of tetraisopropyl titanate as an esterification catalyst were added and reacted at 220 ° C. until the acid value became 2 or less, and the water produced was continuously removed. After the reaction, the mixture was distilled off under reduced pressure at the same temperature to obtain a polyester resin B-4 which is a viscous liquid.
As a result of evaluating the obtained polyester resin B-4 in the same manner as in Synthesis Example 1, the acid value was 0.8 mgKOH / g, the hydroxyl value was 14 mgKOH / g, and the number average molecular weight (Mn) was 3500.

Synthesis example 5
574 g of adipic acid, 336 g of 1,3-butanediol and 110 g of 1,6-hexanediol were placed in a four-necked flask with an internal volume of 2 liters equipped with a thermometer, a stirrer and a reflux condenser, and stirred under a nitrogen stream. While doing so, the temperature was gradually raised until it reached 220 ° C. Next, 169 g of hydrogenated coconut oil fatty acid (manufactured by New Japan Chemical Co., Ltd.) and 0.06 g of tetraisopropyl titanate as an esterification catalyst were added and reacted at 220 ° C. until the acid value became 2 or less, and the water produced was continuously produced. Was removed. After the reaction, the mixture was distilled off under reduced pressure at the same temperature to obtain a polyester resin B-5 which is a viscous liquid.
As a result of evaluating the obtained polyester resin B-5 in the same manner as in Synthesis Example 1, the acid value was 0.7 mgKOH / g, the hydroxyl value was 13 mgKOH / g, and the number average molecular weight (Mn) was 2800.

Comparative synthesis example 1
A four-necked flask with an internal volume of 3 liters equipped with a thermometer, a stirrer and a reflux condenser was charged with 554 g of dimethyl terephthalate, 476 g of propylene glycol, 817 g of paratoryl acid and 0.130 g of tetraisopropyl titanate as an esterification catalyst. The condensation reaction was carried out for a total of 19 hours by gradually raising the temperature to 220 ° C. with stirring underneath. After the reaction, unreacted propylene glycol was removed under reduced pressure to obtain a polyester resin B-6 which is a high-viscosity liquid at room temperature.
As a result of evaluating the obtained polyester resin B-6 in the same manner as in Synthesis Example 1, the acid value was 0.2 mgKOH / g, the hydroxyl value was 11 mgKOH / g, and the number average molecular weight (Mn) was 500.

Comparative synthesis example 2
In a four-necked flask with an internal volume of 5 liters equipped with a thermometer, a stirrer and a reflux condenser, 1302 g of adipic acid, 1624 g of propylene glycol, 1086 g of benzoic acid and 0.24 g of tetraisopropyl titanate as an esterification catalyst were charged, and a nitrogen stream was charged. The condensation reaction was carried out for a total of 19 hours by gradually raising the temperature to 230 ° C. with stirring underneath. After the reaction, unreacted propylene glycol was removed under reduced pressure to obtain a polyester resin B-7 which is a high-viscosity liquid at room temperature.
As a result of evaluating the obtained polyester resin B-7 in the same manner as in Synthesis Example 1, the acid value was 0.6 mgKOH / g, the hydroxyl value was 14 mgKOH / g, and the number average molecular weight (Mn) was 760.

Comparative synthesis example 3
In a four-necked flask with an internal volume of 2 liters equipped with a thermometer, agitator and a reflux condenser, 303 g of sebacic acid, 350 g of diethylene glycol, 385 g of cyclohexanemonocarboxylic acid and 0.06 g of tetraisopropyl titanate as an esterification catalyst were charged, and nitrogen was charged. The condensation reaction was carried out for a total of 26 hours by gradually raising the temperature to 220 ° C. while stirring under an air stream. After the reaction, unreacted diethylene glycol was removed under reduced pressure to obtain a polyester resin B-8 which is a high-viscosity liquid at room temperature.
As a result of evaluating the obtained polyester resin B-8 in the same manner as in Synthesis Example 1, the acid value was 0.2 mgKOH / g, the hydroxyl value was 15 mgKOH / g, and the number average molecular weight (Mn) was 600.

Comparative synthesis example 4
684 g of adipic acid, 207 g of 1,3-butanediol and 207 g of 1,4-butanediol were placed in a 4-neck flask with an internal volume of 2 liters equipped with a thermometer, a stirrer and a reflux condenser, and stirred under a nitrogen stream. While doing so, the temperature was gradually raised until it reached 220 ° C. Then, 135 g of isononyl alcohol and 0.06 g of tetraisopropyl titanate as an esterification catalyst were added and reacted at 220 ° C. until the acid value became 2 or less, and the water produced was continuously removed. After the reaction, the mixture was distilled off under reduced pressure at the same temperature to obtain a polyester resin B-9 which is a viscous liquid.
As a result of evaluating the obtained polyester resin B-9 in the same manner as in Synthesis Example 1, the acid value was 0.3 mgKOH / g, the hydroxyl value was 11 mgKOH / g, and the number average molecular weight (Mn) was 2900.

Example 1
A polyester resin B-1 produced by producing 100 parts by mass of a commercially available cyclic olefin resin, cycloolefin resin A (norbornene resin having an ester group manufactured by JSR Co., Ltd .: F5023, number average molecular weight 22,000) and Synthetic Example 1 To 1 part by mass, 390 parts by mass of methylene chloride and 10 parts by mass of methanol were added and dissolved to obtain a dope solution.
The obtained doping solution was cast on a glass plate and the solvent was distilled off (dried) to obtain a film having a film thickness of about 80 μm. The transparency and heat resistance of the obtained unstretched film were evaluated according to the following method. The results are shown in Table 1.

(Transparency of unstretched film)
The obtained unstretched film was cut out as a 40 mm square test piece, and the HAZE value of this test piece was measured with a HAZE meter NDH-5000 (manufactured by Nippon Denshoku Kogyo Co., Ltd.).
The smaller the HAZE value, the better the transparency.
(Heat resistance of unstretched film)
The glass transition temperature of the obtained unstretched film was evaluated by the midpoint method from a chart measured by a differential scanning calorimeter (DSC) device (manufactured by PerkinElmer Co., Ltd.). The heating rate was 10 ° C./min.

The unstretched film was thermally stretched under the following methods and conditions to obtain a stretched film. The optical properties and transparency of the obtained stretched film were evaluated by the following methods. The results are shown in Table 1.

(Method and conditions of thermal stretching)
The unstretched film was cut out to obtain a test piece having a width of 10 mm and a length of 30 mm, and free-end uniaxial stretching was performed using a thermal stretching machine (manufactured by UBM Co., Ltd.) under the following conditions. Immediately after the completion of stretching, the film was air-cooled to obtain a stretched film.
Magnification: 1.3 times Initial length: 20 mm
Speed: 100% / min
Temperature: At least 2 levels near the glass transition temperature of the unstretched film (thermal stretching was performed so that the stress value at the end of stretching was interpolated to 3 MPa).

(Optical characteristics of stretched film)
The stretched film was allowed to stand at 23 ° C. and 55% relative humidity for 1 hour or more, and the in-plane phase difference (Re value) at a wavelength of 590 nm and the in-plane phase difference (Re value) at a wavelength of 590 nm using a birefringence measuring device (KOBRA-WR, manufactured by Oji Measuring Instruments Co., Ltd.) The out-of-plane phase difference (Rth value) was measured. The stress value during thermal stretching is plotted on the horizontal axis, and the in-plane phase difference (Re value) and the out-of-plane phase difference (Rth value) are plotted on the vertical axis. Obtained. The smaller the Re value and the Rth value, the better the suppression of phase difference expression under the same stress.
(Transparency of stretched film)
The HAZE value of the obtained stretched film was measured with a HAZE meter NDH-5000 (manufactured by Nippon Denshoku Kogyo Co., Ltd.). The smaller the HAZE value, the better the transparency.

Example 2-6 and Comparative Example 1-8
A dope solution was prepared in the same manner as in Example 1 except that the polyester resins shown in Tables 1 and 2 were used in the amounts shown in Tables 1 and 2 instead of the polyester resin B-1, and obtained in the same manner as in Example 1. An unstretched film and a stretched film were produced from the obtained dope solution and evaluated. The results are shown in Tables 1 and 2.

Claims (12)

A resin composition for an optical material containing a cyclic olefin resin and a polyester resin represented by the following formula (1).

(In the above formula (1),
B ₁ independently represents an aliphatic monocarboxylic acid residue having 7 to 20 carbon atoms.
G represents a divalent linking group containing an alkylene glycol residue having 2 to 15 carbon atoms, an oxyalkylene glycol residue having 4 to 12 carbon atoms, or a polyoxyalkylene glycol residue.
A represents an alkylene dicarboxylic acid residue having 2 to 12 carbon atoms or an aryl dicarboxylic acid residue having 6 to 12 carbon atoms.
m represents the number of repeating units enclosed in parentheses, and m is an integer of 0 or more.
A and G may be the same or different for each repeating unit enclosed in parentheses. ) The resin composition for an optical material according to claim 1, wherein B ₁ is an aliphatic monocarboxylic acid residue having 11 to 17 carbon atoms independently. The resin composition for an optical material according to claim 1, wherein A is an alkylene dicarboxylic acid residue having 4 to 12 carbon atoms. The polyester resin reacts one or more glycols selected from alkylene glycols having 2 to 15 carbon atoms, oxyalkylene glycols having 4 to 12 carbon atoms, and glycols having a polyoxyalkylene structure with hydrogenated vegetable oil fatty acids. One or more glycols and carbon atoms selected from alkylene glycols having 2 to 15 carbon atoms, oxyalkylene glycols having 4 to 12 carbon atoms, and glycols containing a polyoxyalkylene structure, which are polyester resins used as raw materials. The optical material according to claim 1, which is a polyester resin containing one or more dicarboxylic acids selected from 4 to 14 alkylenedicarboxylic acids and aryldicarboxylic acids having 8 to 14 carbon atoms and hydrogenated vegetable oil fatty acids as reaction raw materials. Resin composition. The hydrogenated vegetable oil fatty acid is one or more selected from hydrogenated coconut oil fatty acid, hydrogenated palm kernel oil fatty acid, hydrogenated palm oil fatty acid, hydrogenated olive oil fatty acid, hydrogenated castor oil fatty acid and hydrogenated rapeseed oil fatty acid. The resin composition for an optical material according to claim 4. The resin composition for an optical material according to claim 1, wherein the number average molecular weight of the polyester resin is in the range of 300 to 4000. The resin composition for an optical material according to claim 1, wherein the content of the polyester resin is 0.1 to 5 parts by mass with respect to 100 parts by mass of the cyclic olefin resin. The resin composition for an optical material according to claim 1, wherein the cyclic olefin resin has a polar group. An optical film containing the resin composition for an optical material according to any one of claims 1 to 8. The optical film according to claim 9, which is for protecting a polarizing plate. The optical film according to claim 9, which is for a touch panel sensor. An image display device comprising the optical film according to any one of claims 9 to 11.