JP4506342B2 - Transparency resin composition and optical film - Google Patents

Description

  The present invention relates to a transparent resin composition exhibiting negative birefringence that is excellent in transparency, heat resistance, etc., and excellent in thermal stability during high-temperature processing, and an optical film comprising the transparent resin composition. is there.

  In recent years, liquid crystal display devices (hereinafter referred to as LCDs) take advantage of low voltage, low power consumption, and light weight, and are portable devices, mobile communication devices, mobile devices, personal computers, televisions, and home appliances. Widely used as display devices for products, audio products, industrial equipment, etc. An LCD is known as an optical element that sandwiches liquid crystal molecules between two polarizing plates and performs black and white display using the optical filter function of the polarizing plates and the birefringence characteristics of the liquid crystal molecules. The LCD includes a polarizing film and a polarizing film. Optical films such as polarizing plates, retardation films, light diffusion films, and transparent electrode films made of protective films (hereinafter referred to as polarizing film protective films) are used.

  Optical films used in LCDs have excellent optical properties such as transparency and phase difference, but there are defects such as foreign matter and irregularities on the surface of the film, resulting in poor LCD display properties. It is difficult to use because it may cause

  One factor that deteriorates the appearance of the film is thermal degradation of the resin that may occur in post-processing steps such as granulation, film manufacturing, stretch molding, bonding, and LCD assembly. Thermal deterioration of the resin may cause burns and gels, yellowing, transparency deterioration, generation of decomposition gas, etc., and may deteriorate the appearance of the film. Is required to have high thermal stability.

  Since such thermal deterioration of the resin is often caused by oxidation, generally, the thermal stability of the resin is improved by blending an antioxidant. Antioxidants include those that bind to oxygen radicals such as phenolic antioxidants and phosphorus antioxidants, and those that bind to carbon radicals such as lactone stabilizers. Widely known. The effect of improving the thermal stability by such antioxidants varies greatly depending on various factors such as the structure and properties of the resin, the conditions for receiving thermal history, and the required performance after molding. It is difficult to discuss stability improvement.

  On the other hand, a copolymer having an N-phenyl-substituted maleimide unit has characteristics such as excellent optical properties such as transparency and low birefringence, excellent heat resistance and surface hardness, and further exhibits negative birefringence. It is disclosed that it can be used as resin (for example, refer patent document 1). The resin or resin composition exhibiting negative birefringence in the present invention refers to a direction different from the orientation direction (for example, an orthogonal direction) when the main chain molecules of the resin are stretched and oriented in one direction. It refers to a resin or resin composition that exhibits optical anisotropy that maximizes the refractive index. Examples of resins that exhibit negative birefringence include polymethyl methacrylate (hereinafter referred to as PMMA), polystyrene (hereinafter referred to as PMMA). Known as PS), acrylonitrile / styrene copolymer (hereinafter referred to as AS), and the like.

  Further, it is disclosed that a resin exhibiting negative birefringence has an effect of reducing the birefringence of a resin exhibiting positive birefringence when mixed with a resin exhibiting positive birefringence. (For example, refer nonpatent literature 1-3.). In addition, it is disclosed that such a resin exhibiting negative birefringence can be a retardation film exhibiting negative birefringence (see, for example, Patent Document 2).

  Further, in order to improve the stability of a resin composition comprising a maleimide / olefin copolymer resin and a styrene / acrylonitrile copolymer resin, a resin composition containing a stabilizer has been proposed (for example, Patent Document 3, 4).

JP 05-117334 A J. et al. Appl. Polym. Sci. 13 pp2541 1969 Plaster un Kautschuk 29 pp618 1982 Functional Materials March Issue 1987 pp21 JP 2001-194530 A JP 2003-26943 A JP 2004-107371 A

  However, the copolymer described in Patent Document 1 can be a resin exhibiting negative birefringence and has characteristics such as excellent transparency, heat resistance, surface hardness, etc. There was a problem of poor toughness. In addition, although there is a description that an antioxidant such as hindered phenol and organic phosphate ester may be added to prevent thermal deterioration, the type and content of the antioxidant, the thermal stability of the resin, etc. There is no specific indication about.

  On the other hand, PMMA, PS, and AS have negative birefringence and characteristics such as transparency, workability, and surface hardness, but have poor heat resistance. For example, they can be used as optical films. Have difficulty.

  Patent Documents 3 and 4 do not specifically propose any N-phenyl substituted maleimide / olefin copolymer and N-phenyl substituted maleimide / olefin copolymer composition, and negative birefringence. There is no mention of sex.

  Accordingly, the present invention provides a transparent resin composition having excellent negative transparency and heat resistance, excellent thermal stability during high-temperature processing, and exhibiting negative birefringence, and an optical film comprising the transparent resin composition. It is intended to do.

  As a result of intensive studies on the above problems, the present inventor has found that an N-phenyl-substituted maleimide / olefin copolymer having a specific structure, a styrene copolymer having a specific structure, a phenol-based antioxidant and / or a phosphorus-based copolymer. It has been found that a transparent resin composition comprising a specific proportion of an antioxidant exhibits negative birefringence, excellent transparency, heat resistance, etc., and excellent thermal stability during high temperature molding. The invention has been completed.

That is, the present invention comprises a unit represented by the following general formula (I) and a unit represented by the following general formula (II), and has a number average molecular weight of 1 × 10 ³ or more and 5 × 10 ⁶ or less. From 30 to 95% by weight of maleimide / olefin copolymer and at least one monomer selected from the group consisting of styrene monomers and vinyl cyanide compounds, alkyl acrylates and alkyl methacrylates To 100 parts by weight of the total amount of 70 to 5% by weight of the styrene-based copolymer, 0.001 to 2 parts by weight of a phenol-based antioxidant and / or phosphorus-based antioxidant , and a lactone-based stabilizer 0.001 to The present invention relates to a transparent resin composition comprising 2 parts by weight and exhibiting negative birefringence, and an optical film comprising the transparent resin composition.

（ここで、Ｒ１はフェニル基、ナフチル基、ハロゲン系元素，カルボン酸，カルボン酸エステル，水酸基，シアノ基，ニトロ基，炭素数１〜８の直鎖状アルキル基，炭素数１〜８の分岐状アルキル基により置換されたフェニル基又はナフチル基を示す。）

(Where R1 is phenyl group, naphthyl group, halogen element, carboxylic acid, carboxylic ester, hydroxyl group, cyano group, nitro group, linear alkyl group having 1 to 8 carbon atoms, branched chain having 1 to 8 carbon atoms. Represents a phenyl group or a naphthyl group substituted with a linear alkyl group.)

（ここで、Ｒ２、Ｒ３は各々独立して水素又は炭素数１〜６のアルキル基を示す。）
以下に本発明を詳細に説明する。

(Here, R2 and R3 each independently represent hydrogen or an alkyl group having 1 to 6 carbon atoms.)
The present invention is described in detail below.

The N-phenylmaleimide / olefin copolymer used in the present invention is a copolymer comprising a unit represented by the general formula (I) and a unit represented by the general formula (II), and has a number average molecular weight of 1 ×. N-phenylmaleimide / olefin copolymer having 10 ³ or more and 5 × 10 ⁶ or less.

  R1 of the unit represented by the general formula (I) is a phenyl group, a naphthyl group, a halogen element, a carboxylic acid, a carboxylic ester, a hydroxyl group, a cyano group, a nitro group, a linear alkyl group having 1 to 8 carbon atoms, A phenyl group or a naphthyl group substituted by a branched alkyl group having 1 to 8 carbon atoms is shown. Here, examples of the halogen element include fluorine, bromine, chlorine, and iodine. Examples of the carboxylic acid ester include methyl carboxylic acid ester and ethyl carboxylic acid ester. Examples of the linear alkyl group having ˜8 or the branched alkyl group having 1 to 8 carbon atoms include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, s-butyl group, t -Butyl group, n-pentyl group, 2-pentyl group, n-hexyl group, 2-hexyl group, n-heptyl group, 2-heptyl group, 3-heptyl group, n-octyl group, 2-octyl group, 3 -An octyl group etc. can be mentioned, and since it becomes a resin composition excellent in especially heat resistance, transparency, and mechanical strength, R1 shown by general formula (I) is a phenyl group and a 2-methylphenyl group. Rukoto is preferable.

  In addition, R2 and R3 of the unit represented by the general formula (II) are each independently hydrogen or an alkyl group having 1 to 6 carbon atoms, and when the number of carbon atoms exceeds 6, the resulting resin composition has heat resistance. Is inferior. Examples of the alkyl group having 1 to 6 carbon atoms include methyl group, ethyl group, propyl group, isopropyl group, butyl group, s-butyl group, t-butyl group, pentyl group, hexyl group, cyclopropyl group, cyclobutyl group, A cyclohexyl group etc. can be mentioned, Among these, since it becomes a resin composition excellent in especially heat resistance and mechanical strength, it is preferable that it is a methyl group.

  Such N-phenyl-substituted maleimide / olefin copolymers include, for example, radicals of maleimides that derive a unit represented by general formula (I) and olefins that derive a unit represented by general formula (II). It can be obtained by a copolymerization reaction.

  In this case, maleimides for deriving the unit represented by the general formula (I) include, for example, maleimides having an unsubstituted phenyl group or a substituted phenyl group introduced as an N substituent of the maleimide compound, or maleimides having a naphthyl group introduced Specifically, N-phenylmaleimide, N- (2-methylphenyl) maleimide, N- (2-ethylphenyl) maleimide, N- (2-n-propylphenyl) maleimide, N- ( 2-isopropylphenyl) maleimide, N- (2-n-butylphenyl) maleimide, N- (2-s-butylphenyl) maleimide, N- (2-t-butylphenyl) maleimide, N- (2-n- Pentylphenyl) maleimide, N- (2-t-pentylphenyl) maleimide, N- (2,6-dimethylphenyl) ma Imido, N- (2,6-diethylphenyl) maleimide, N- (2,6-di-n-propylphenyl) maleimide, N- (2,6-di-isopropylphenyl) maleimide, N- (2-methyl -6-ethylphenyl) maleimide, N- (2-methyl-6-isopropylphenyl) maleimide, N- (2-chlorophenyl) maleimide, N- (2-bromophenyl) maleimide, N- (2,6-dichlorophenyl) Maleimide, N- (2,6-dibromophenyl) maleimide, N-2-biphenylmaleimide, N-2-diphenylethermaleimide, N- (2-cyanophenyl) maleimide, N- (2-nitrophenyl) maleimide, N- (2,4,6-trimethylphenyl) maleimide, N- (2,4-dimethylphenyl) maleimide, -Perbromophenylmaleimide, N- (2-methyl-4-hydroxyphenyl) maleimide, N- (2,6-diethyl-4-hydroxyphenyl) maleimide, N-naphthylmaleimide, etc. N-phenylmaleimide and N- (2-methylphenyl) maleimide are preferable because the resin composition is excellent in transparency and mechanical strength. The N-phenyl substituted maleimide unit may be one or a combination of two or more, and the ratio is not particularly limited.

  Examples of the compound for deriving the unit represented by the general formula (II) include olefins such as isobutene, 2-methyl-1-butene, 2-methyl-1-pentene, 2-methyl-1-hexene, Of these, isobutene is preferable because it is a resin composition excellent in heat resistance and mechanical strength.

  Further, the ratio of the unit represented by the general formula (I) and the unit represented by the general formula (II) constituting the N-phenyl-substituted maleimide / olefin copolymer used in the present invention is within a range where the object of the present invention can be achieved. In particular, the unit represented by the general formula (I) is preferably in the range of 40 to 70 mol% because it is a resin composition excellent in mechanical strength, transparency and heat resistance. A range of 50 to 70 mol% is preferred.

The N-phenyl-substituted maleimide / olefin copolymer used in the present invention has a number average molecular weight (Mn) of 1 × 10 ³ or more and 5 × 10 ⁶ or less, and is particularly excellent in a balance between toughness and molding processability. Therefore, it is preferably 1 × 10 ⁴ or more and 5 × 10 ⁵ or less. Here, when the number average molecular weight of the N-phenyl-substituted maleimide / olefin copolymer exceeds 5 × 10 ⁶ , the melt viscosity of the N-phenyl-substituted maleimide / olefin copolymer becomes too high. The properties are poor and the moldability is inferior. On the other hand, when the number average molecular weight is less than 1 × 10 ³ , the mechanical strength of the resin composition becomes poor. Here, the number average molecular weight in the present invention is a standard polystyrene conversion value obtained by gel permeation chromatography (GPC).

  Since the N-phenyl-substituted maleimide / olefin copolymer used in the present invention is a resin composition particularly excellent in heat resistance, transparency and mechanical strength, N-phenylmaleimide / isobutene copolymer, N- ( 2-Methylphenyl) maleimide / isobutene copolymer is preferred.

  Furthermore, the N-phenyl-substituted maleimide / olefin copolymer used in the present invention may contain units derived from other monomer components as long as the purpose of the present invention is not impaired, if necessary. Examples of such other monomer components include styrene derivatives such as styrene and α-methylstyrene; methacrylic acid such as methacrylic acid, methyl methacrylate, and ethyl methacrylate or esters thereof; acrylic acid, methyl acrylate, acrylic acid Acrylic acid such as ethyl or esters thereof; Vinyl esters such as vinyl acetate and vinyl benzoate; Vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, propio vinyl ether and butyl vinyl ether; Maleic anhydride; One or more selected from acrylonitrile The compound of Is preferably not more than 5 mol% as its content.

  The N-phenyl-substituted maleimide / olefin copolymer used in the present invention is obtained by polymerizing a compound derived from the unit represented by the general formula (I) and a compound derived from the unit represented by the general formula (II) by a known method. You can get it. As such a polymerization method, for example, it can be obtained by any of a bulk polymerization method, a solution polymerization method, a suspension polymerization method, a precipitation polymerization method, and an emulsion polymerization method, and among them, a resin composition particularly excellent in transparency and color tone Since a product is obtained, it is preferable to be obtained by a solution polymerization method or a suspension polymerization method.

  As a polymerization initiator used in the polymerization reaction, for example, benzoyl peroxide, lauryl peroxide, octanoyl peroxide, acetyl peroxide, di-t-butyl peroxide, t-butylcumyl peroxide, dicumyl peroxide, organic peroxides such as t-butyl peroxyacetate, t-butyl peroxybenzoate, perbutyl neodecanoate, t-butyl peroxypivalate; 2,2′-azobis (2,4-dimethylvaleronitrile) 2,2′-azobis (2-butyronitrile), 2,2′-azobisisobutyronitrile, dimethyl-2,2′-azobisisobutyrate, 1,1′-azobis (cyclohexane-1-carbohydrate) And azo initiators such as nitrile).

  Examples of the solvent used in the solution polymerization method and the precipitation polymerization method include aromatic solvents such as benzene, toluene, and xylene; alcohol solvents such as methanol, ethanol, propyl alcohol, and butyl alcohol; cyclohexane, dioxane, tetrahydrofuran, acetone, and methyl ethyl ketone. , Dimethylformamide, isopropyl acetate, a mixed solvent of an aromatic solvent and an alcohol solvent, and the like.

  The polymerization temperature at that time can be appropriately set according to the decomposition temperature of the initiator, but in general, it is preferably carried out in the range of 40 to 150 ° C.

  Alternatively, the N-phenyl-substituted maleimide / olefin copolymer can also be obtained by post-imidizing the maleic anhydride / olefin copolymer with an amine compound.

  Such a post-imidation reaction includes, for example, maleic anhydride / olefin copolymer in an alcohol solvent such as methanol, ethanol and propanol; an aromatic solvent such as benzene and toluene; an ester solvent such as ethyl acetate and isopropyl acetate; An amine compound and a mixed solvent of an aromatic solvent and an alcohol solvent, dissolved or dispersed in a solvent such as N-methyl-2-pyrrolidone (hereinafter referred to as NMP), dimethylformamide (hereinafter referred to as DMF) A method in which an amidation reaction and an imidation reaction are continuously performed by reaction at a temperature of 50 to 250 ° C., an amide body is obtained by reacting with an amine compound, and then the amide body is heated to dehydrate and cyclize to form an imide It can manufacture by the method etc. which perform crystallization.

  Examples of the amine compound include aniline, 2-methylaniline, 2-ethylaniline, 2-n-propylaniline, 2-isopropylaniline, 2-n-butylaniline, 2-s-butylaniline, 2-t-butylaniline. 2-n-pentylaniline, 2-t-pentylaniline, 2,6-dimethylaniline, 2,6-diethylaniline, 2,6-di-n-propylaniline, 2,6-diisopropylaniline, 2 -Methyl-6-ethylaniline, 2-methyl-6-isopropylaniline, 2-chloroaniline, 2-bromoaniline, 2,6-dichloroaniline, 2,6-dibromoaniline, 2-biphenylamine, 2-diphenyletheramine 2-cyanoaniline, 2-nitroaniline, 2,4,6-trimethylaniline, 2,4 Examples include dimethylaniline, perbromoaniline, 2-methyl-4-hydroxyaniline, 2,6-diethyl-4-hydroxyaniline, naphthylamine, and the like. Among them, a resin composition excellent in heat resistance, transparency, and mechanical strength Therefore, aniline and 2-methylaniline are preferable as the amine compound for deriving the unit represented by the general formula (I).

  The styrene copolymer used in the present invention is a copolymer comprising a styrene monomer and at least one monomer selected from the group consisting of a vinyl cyanide compound, an alkyl acrylate ester, and an alkyl methacrylate ester. It is a polymer.

  Here, the birefringence characteristic of the resin is generally determined by the structural unit of the molecular chain constituting the resin, that is, the optical anisotropy per monomer residue unit and its orientation state, The optical anisotropy per body residue unit is expressed as intrinsic birefringence, and the orientation state is expressed as an orientation function. In addition, the intrinsic birefringence is proportional to the difference between the polarizability per monomer residue unit in the direction of the molecular chain axis and the polarizability in the direction perpendicular thereto, that is, the polarizability anisotropy of the monomer residue unit, The polarizability anisotropy of the monomer residue unit is calculated as the sum of the polarizability contributions per individual molecular bond, and it is known that the positive / negative of the birefringence of the resin can be estimated from the positive / negative of this value. In the case of a monomer residue unit having a phenyl group having a large polarizability anisotropy as a substituent, for example, a styrene monomer residue unit, the polarizability anisotropy is formed between the phenyl group and the molecular chain axis. It will be greatly influenced by the angle. For example, in the case of polystyrene, when the surface of the phenyl group is in a plane perpendicular to the main chain molecular axis, the intrinsic birefringence is likely to show a negative value, as described in “Polym. Prep. Jpn., (38), 10, 3539, 1989 ”,“ Polym. Prep. Jpn., (51), 3,431, 2002 ”and the like.

  In the present invention, by using the styrene copolymer, that is, a copolymer having a monomer residue unit having a phenyl group in the side chain, the steric arrangement of the phenyl group, the conformation, It becomes possible to express negative birefringence more efficiently, and exhibits high negative birefringence. In the present invention, since the styrene copolymer having excellent fluidity and the N-phenyl-substituted maleimide / olefin copolymer generally exhibiting high melt viscosity are blended, the composition has excellent fluidity. As a result, it is possible to obtain effects such as suppression of thermal deterioration during melt processing and further improvement of mechanical strength.

  The styrene copolymer used in the present invention includes at least one single monomer selected from the group consisting of vinyl cyanide compounds, alkyl acrylates and alkyl methacrylates in addition to styrene monomers as structural units. A copolymer consisting of a monomer, and the constituent monomer is collated with the structure, refractive index, etc. of the N-phenyl-substituted maleimide / olefin copolymer, so that the N-phenyl-substituted maleimide / olefin copolymer and When blended, it becomes a resin composition exhibiting negative birefringence with an excellent balance of transparency, heat resistance, processability, mechanical strength and the like.

  Here, examples of the styrene monomer include styrene, α-methyl styrene, o-methyl styrene, p-methyl styrene, ethyl styrene, dimethyl styrene, pt-butyl styrene, 2,4-dimethyl styrene, methoxy. Examples thereof include styrene monomers such as styrene, bromostyrene, fluorostyrene, hydroxystyrene, aminostyrene, cyanostyrene, nitrostyrene, chloromethylstyrene, acetoxystyrene, p-dimethylaminomethylstyrene, and these may be used alone or in combination. You may use above.

  Examples of the vinyl cyanide compound include acrylonitrile and methacrylonitrile, and these may be used alone or in combination of two or more.

  Examples of the acrylic acid alkyl ester include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, amyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, cyclohexyl acrylate, dodecyl acrylate, and the like. You may use above.

  Examples of the methacrylic acid alkyl ester include methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, amyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate, cyclohexyl methacrylate, dodecyl methacrylate, and the like. You may use above.

  In the styrene copolymer used in the present invention, at least one monomer residue selected from the group consisting of a styrene monomer residue unit and a vinyl cyanide compound, an alkyl acrylate ester, and an alkyl methacrylate ester. The ratio of units (hereinafter referred to as other monomer residue units) is arbitrary, and among them, styrene monomer residue units / other monomer residue units = 95/5 to 60/40 (moles) Styrene monomer residue unit / other monomer because it is a resin composition exhibiting particularly high negative birefringence and having excellent transparency, heat resistance, and thermal stability. It is preferable that the residue unit = 90/10 to 70/30 (molar ratio).

In addition, the weight average molecular weight (Mw) of the styrene copolymer used in the present invention is arbitrary, and among them, it is preferably 1 × 10 ³ or more and 5 × 10 ⁶ or less, particularly mechanical strength, toughness and moldability. It is preferable that they are 1 * 10 < ⁴ > or more and 5 * 10 < ⁵ > or less from becoming a resin composition which is excellent in the balance.

  Examples of the styrene copolymer include styrene / acrylonitrile copolymer, styrene / methyl acrylate copolymer, styrene / ethyl acrylate copolymer, styrene / butyl acrylate copolymer, styrene / hexyl acrylate. Copolymer, styrene / methyl methacrylate copolymer, styrene / ethyl methacrylate copolymer, styrene / butyl methacrylate copolymer, styrene / hexyl acrylate copolymer, etc. A styrene / acrylonitrile copolymer, a styrene / butyl acrylate copolymer, or a styrene / ethyl methacrylate copolymer is preferable because of excellent heat resistance, transparency, and mechanical strength.

  As a method for synthesizing the styrene-based copolymer, a known polymerization method can be used. For example, a styrene monomer and cyanide can be synthesized by a method such as a bulk polymerization method, a solution polymerization method, a suspension polymerization method, or an emulsion polymerization method. It can be produced by polymerizing at least one monomer selected from the group consisting of vinyl compounds, acrylic acid alkyl esters, and methacrylic acid alkyl esters. Moreover, what was obtained as a commercial item may be used.

  The transparent resin composition of the present invention is phenolic based on a total amount of 100 parts by weight consisting of 30 to 95% by weight of the N-phenyl-substituted maleimide / olefin copolymer and 70 to 5% by weight of the styrene copolymer. It is a transparent resin composition exhibiting negative birefringence formed by blending 0.001 to 2 parts by weight of an antioxidant and / or a phosphorus-based antioxidant, and particularly in balance between heat resistance, workability and mechanical strength. Since it becomes an excellent transparent resin composition, it is preferably composed of 40 to 80% by weight of the N-phenyl-substituted maleimide / olefin copolymer and 60 to 20% by weight of a styrene copolymer. Here, when the N-phenyl-substituted maleimide / olefin copolymer is less than 30% by weight, the resulting resin composition has extremely poor heat resistance. On the other hand, when the N-phenyl-substituted maleimide / olefin copolymer exceeds 95% by weight, the mechanical strength and fluidity of the resin composition are remarkably poor, and it becomes difficult to mold the resulting resin composition.

  Further, the transparent resin composition of the present invention contains a phenolic antioxidant and / or a phosphorus antioxidant, and these antioxidants are used in the granulation step and primary molding of the transparent resin composition. Suppresses thermal degradation, burns and gels, yellowing, loss of transparency, generation of decomposition gas, etc. in processing steps, secondary molding processing steps, etc., and N-phenyl substituted maleimide / olefin copolymer and It is mix | blended in the range of 0.001-2 weight part with respect to 100 weight part of total amounts of a styrene-type copolymer, It is preferable that it is the range of 0.01-1 weight part especially, Furthermore, 0.02-0. The range is preferably 5 parts by weight. Here, when the compounding quantity of a phenolic antioxidant and / or phosphorus antioxidant is less than 0.001 weight part, the resin composition obtained becomes poor in thermal stability at the time of high temperature processing. On the other hand, when the blending amount of the phenolic antioxidant and / or the phosphorous antioxidant exceeds 2 parts by weight, the effect of improving the thermal stability accompanying an increase in the blending amount is small, and not only industrial value can be found. The transparency of the resin composition may be reduced. In addition, these antioxidants may be used alone or in combination, and among them, the antioxidant action is synergistically improved, so that it is particularly preferable to use a phenolic antioxidant and a phosphorus antioxidant together. In this case, for example, it is preferable to contain 100 to 500 parts by weight of the phosphorus antioxidant with respect to 100 parts by weight of the phenol antioxidant.

  Examples of the phenolic antioxidant used in the present invention include pentaerythritol-tetrakis (3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate), thiodiethylene-bis (3- (3, 5-di-t-butyl-4-hydroxyphenyl) propionate), octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, N, N′-hexane-1,6-diylbis (3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionamide), diethyl ((3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl) methyl) phosphate, 3, 3 ′, 3 ″, 5,5 ′, 5 ″ -hexa-t-butyl-a, a ′, a ″-(mesitylene-2,4,6-triyl) tri- -Cresol, ethylenebis (oxyethylene) bis (3- (5-t-butyl-4-hydroxy-m-tolyl) propionate), hexamethylene-bis (3- (3,5-di-t-butyl-4) -Hydroxyphenyl) propionate), 1,3,5-tris (3,5-di-t-butyl-4-hydroxybenzyl) -1,3,5-triazine-2,4,6 (1H, 3H, 5H ) -Trione, 1,3,5-tris ((4-tert-butyl-3-hydroxy-2,6-xylyl) methyl) -1,3,5-triazine-2,4,6 (1H, 3H, 5H) -trione, 2,6-di-t-butyl-4- (4,6-bis (octylthio) -1,3,5-triazin-2-ylamino) phenol, 3,9-bis (2- ( 3- (3-t-butyl-4-hydroxy 5-methylphenyl) propionyloxy) -1,1-dimethylethyl) -2,4,8,10-tetraoxaspiro (5,5) undecane and the like. Among them, the transparent resin composition is colored. Since it is difficult and extremely excellent in transparency, pentaerythritol-tetrakis (3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate), octadecyl-3- (3,5-di-) Particularly preferred are t-butyl-4-hydroxyphenyl) propionate and ethylene bis (oxyethylene) bis (3- (5-t-butyl-4-hydroxy-m-tolyl) propionate).

  Examples of phosphorus antioxidants used in the present invention include tris (2,4-di-t-butylphenyl) phosphite and bis (2,4-bis (1,1-dimethylethyl) -6-methylphenyl. ) Ethyl ester phosphorous acid, tetrakis (2,4-di-t-butylphenyl) (1,1-biphenyl) -4,4′-diylbisphosphonite, bis (2,4-di-t-butyl) Phenyl) pentaerythritol diphosphite, bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite, bis (2,4-dicumylphenyl) pentaerythritol diphosphite, tetrakis (2, 4-t-butylphenyl) (1,1-biphenyl) -4,4′-diylbisphosphonite, di-t-butyl-m-cresyl-phospho In particular, the transparent resin composition is difficult to be colored and is extremely excellent in transparency. Therefore, tris (2,4-di-t-butylphenyl) phosphite, bis (2,6 -Di-t-butyl-4-methylphenyl) pentaerythritol diphosphite, bis (2,4-bis (1,1-dimethylethyl) -6-methylphenyl) ethyl ester phosphorous acid is particularly preferred. .

  Further, since the transparent resin composition of the present invention is a transparent resin composition in which oxidative deterioration is suppressed particularly during high-temperature processing and thermal stability is further improved, an N-phenyl-substituted olefin copolymer and styrene The lactone stabilizer is further 0.001 to 2 parts by weight, more preferably 0.005 to 1 part by weight, particularly preferably 0.01 to 0.5 parts by weight, based on 100 parts by weight of the total amount of the copolymer. It is preferable to blend. Examples of the lactone antioxidant include 3- (3,4-dimethylphenyl) -5,7-di-t-butyl-3H-benzofuran-2-one.

  Furthermore, the transparent resin composition of the present invention may contain other antioxidants such as a sulfur-based antioxidant. Examples of the sulfur-based antioxidant include dilauryl-3,3-thiodipropionate, Dimyristyl-3,3′-thiodipropionate, distearyl-3,3-thiodipropionate, laurylstearyl-3,3-thiodipropionate, pentaerythritol-tetrakis- (β-lauryl-thio-propionate) 3,9-bis (2-dodecylthioethyl) -2,4,8,10-tetraoxaspiro (5,5) undecane and the like. Other antioxidants include, for example, 6- (3- (3-t-butyl-4-hydroxy-5-methyl) propoxy) -2,4,8,10-tetra-t-butyldibenz (d, f). (1,3,2) -Dioxaphosphepine, 3,4-dihydro-2,5,7,8-tetramethyl-2- (4,8,12-trimethyltridecyl) -2H-benzopyran-6 -All and the like.

  The transparent resin composition of the present invention is obtained by generally mixing and kneading an N-phenyl-substituted maleimide / olefin copolymer, a styrene-based copolymer, a phenol-based antioxidant and / or a phosphorus-based antioxidant. Examples of the mixing and kneading apparatus in this case include melt kneading apparatuses such as a single screw extruder, a twin screw extruder, a brabender, a roll, a kneader, and a Banbury mixer. Alternatively, a method may be used in which the respective components are dissolved or dispersed in a solvent and mixed.

  Further, the transparent resin composition of the present invention has a hindered amine light stabilizer, an ultraviolet absorber, a light stabilizer, for the purpose of preventing thermal coloring and light deterioration due to irradiation with light such as visible light, ultraviolet light, and near infrared light. You may contain a near-infrared absorber etc. as needed. Moreover, you may contain a plasticizer as needed in the range which does not impair transparency in order to provide fluidity | liquidity and toughness. Furthermore, pigments, lubricants, antiblocking agents, antistatic agents, surfactants, polymer electrolytes, conductive complexes, inorganic fillers, dyes, oils and the like may be contained as necessary, and transparency is not impaired. Other resins may be contained only in some cases.

  The transparent resin composition of the present invention can be formed into a molded body by a conventionally known molding method, for example, injection molding, injection compression molding, gas assist method injection molding, extrusion molding, multilayer extrusion molding, rotational molding, hot pressing. It can be formed into an injection-molded article, tube, sheet, film, pipe, bottle or the like by a method such as molding, blow molding or foam molding. Among them, an optical film is preferable because it is a film having excellent transparency, heat resistance, and appearance. Since the optical film can be used for a display device such as an LCD that requires high transparency, the haze according to JIS K7136 is 1% or less and the yellowness is 2% according to JIS K7105. In particular, it is preferable that the haze is 0.7% or less and the yellowness is 1% or less.

  Since the transparent resin composition of the present invention exhibits high negative birefringence and is excellent in heat resistance, workability, and mechanical strength, it is preferably a retardation film exhibiting negative birefringence. As a method for producing the retardation film, for example, a raw film is prepared by a publicly known method such as a solution casting method (solution casting method), a melt extrusion method, a calender method, and a compression molding method. It can be obtained by stretch molding. The stretching process includes a process performed continuously in the process of forming the raw film, a process of winding the original film once, and then subjecting the film to a stretching apparatus to perform a stretching process. In addition, film stretching methods are generally classified into flat method stretching that stretches in the film in-plane direction and tubular method stretching that swells and stretches into a tube shape, but flat method stretching with high accuracy in thickness and stretch ratio. Is particularly preferred. The flat method stretching is classified into a uniaxial stretching method and a biaxial stretching method. As the uniaxial stretching method, there are a free width uniaxial stretching method and a constant width uniaxial stretching method. On the other hand, the biaxial stretching method includes a two-stage free width biaxial stretching method, a sequential biaxial stretching method, and a simultaneous biaxial stretching method, and the sequential biaxial stretching includes an all tenter method and a roll tenter method. Any of the above stretching methods may be used as the stretching method for producing the retardation film from the transparent resin composition of the present invention, and the most suitable method depending on the required three-dimensional refractive index and retardation amount. Just choose.

  In particular, when a retardation film is formed by the uniaxial stretching method, the stretching direction is the x axis in the film plane, the orthogonal direction in the film plane with respect to the X axis is the y axis, and the vertical direction outside the film plane with respect to the axis. Is the z-axis, the x-axis direction refractive index is nx, the y-axis direction refractive index is ny, and the z-axis direction refractive index is nz, the relationship of the three-dimensional refractive index is nz ≧ ny> nx or ny ≧ nz> nx It is preferable to use a retardation film. When the retardation film is formed by biaxial stretching, the stretching direction is the x-axis in the film plane and the y-axis in the film plane, the vertical direction outside the film plane is the z-axis, and the refractive index in the x-axis direction. Is a retardation film in which the relationship of the three-dimensional refractive index is nz> ny ≧ nx or nz> nx ≧ ny, where nx is the refractive index in the y-axis direction and ny is the refractive index in the z-axis direction. .

  Furthermore, when stretch-molding, an optical film exhibiting high negative birefringence and excellent retardation accuracy, and a retardation film, the glass transition temperature of the transparent resin composition -20 ° C ~ It is preferable to extend | stretch in the temperature range of glass transition temperature +20 degreeC. The glass transition temperature here is measured by a differential scanning calorimeter at a heating rate of 10 ° C./min.

  The optical film and retardation film exhibiting negative birefringence according to the present invention can be suitably used as an optical compensation member for LCD. For example, STN LCD, TFT-TN LCD, OCB LCD, VA LCD An optical compensation member such as a retardation film for an LCD such as an IPS type LCD; a half-wave plate; a quarter-wave plate; an inverse wavelength dispersion characteristic film; and a viewing angle compensation film for a polarizing plate. In addition, as other optical films, for example, retardation films and antireflection films used in information devices such as organic EL, PDP, copying machines, printers, facsimiles, touch panels, optical files, etc .; used in flat panel displays such as LCDs. Suitable for polarizing film protective film, reflector film, separator film, light diffusion film, transparent electrode film substrate, display surface protective film, anti-glare film, anti-reflection film, electromagnetic wave shielding film, ultraviolet absorbing film, far infrared absorbing film, etc. Can be used.

In addition, the transparent resin composition of the present invention can be used, for example, for the following applications.
Recording field: electrostatic recording substrate, OHP, 2nd original, slide film, microfilm, X-ray film optical / magnetic memory field: Thermo-plastic recording, ferroelectric memory, magnetic tape, ID card, barcode prevention Fields: Meter windows, television cathode-ray tubes, clean room windows, semiconductor packaging materials, dust-proof films for photomasks, electromagnetic shielding fields: measuring instruments, medical equipment, radiation detectors, IC components, CRT
Photoelectric conversion element field: solar cell window, optical amplifier, photosensor heat ray reflection field: window (architecture, automobile, etc.), incandescent bulb, cooking oven window, furnace sight window, selective transmission film surface heating element field: defroster , Aircraft, automobile, freezer, incubator, goggles, medical equipment, liquid crystal display device electronic parts / circuit materials field: capacitors, resistors, thin film composite circuits, leadless LSI chip carrier mounting, dry film resist electrode field: paper battery Electrode light transmission filter field: UV cut filter, UV transmission filter, UV transmission visible light absorption filter, color separation filter, color temperature conversion filter, neutral density filter, contrast filter, wavelength calibration filter, interference filter, infrared transmission filter, infrared Cut filter, heat ray Collection filter, heat ray reflective filter gas selective permeable membrane field: oxygen / nitrogen separation membrane, carbon dioxide separation membrane, hydrogen separation membrane Electrical insulation field: insulating adhesive tape, motor slot liner, transformer interphase insulation, lead insulation High voltage cable insulation coating polymer sensor field: optical sensor, infrared sensor, acoustic wave sensor, pressure sensor Surface protection field: CRT, furniture, system kitchen, automotive interior / exterior, paint protective film sliding material field: hopper chute Lining, sliding material for conveyor belts, sliding material for guide rails, paper feeding rollers for copiers, computer-mouse porous film fields: moisture permeable waterproof materials, filter materials for microfiltration membranes, etc. Other fields: thermal transfer, printer ribbon, Electric cable shield, water leakage prevention film, battery separation film The transparent resin composition of the present invention can be suitably used for applications other than those described above. For example, relays, burn-in sockets, connectors, sensor housings, variable resistors, polyvaricon cases, aeration used in electrical and electronic equipment. Sealing materials for bobbins, transistors, ICs, LSIs, LEDs, etc., sealing materials for IC memories of IC cards, sealing materials for motors, capacitors, switches, sensors, etc .; used for video equipment such as cameras, VTRs, projectors, etc. Photographic lenses, viewfinders, filters, prisms, Fresnel lenses, body materials, etc .; cards, discs, pickup lenses, etc. used in optical recording equipment such as CD players, DVD players, MD players, game machines; Used in optical fiber, optical switch, optical connector Light guide plates, light guides, Fresnel lenses, prism sheets, light diffusion sheets, transparent electrode sheet substrates used in information devices such as LCDs, organic ELs, PDPs, copiers, printers, facsimiles, touch panels, optical files, etc. Display surface protection sheets, ink tanks, covers, body materials, etc .; meters, lamps, lenses, sockets, fuse cases, instrument covers, etc. used in vehicles such as automobiles and trains; used in the medical equipment field Spectacle lenses, contact lenses, endoscope lenses, syringes, artificial dialysers, chemical containers, dentures, ampoule cutter containers, etc .; lighting windows, doors, surveillance camera lenses, carports, terraces, lighting parts, etc. in the field of building materials; Lighting parts, toys, sunglasses, stationery, cosmetic containers, fishing equipment, Examples include food containers and drinking water containers.

  The transparent resin composition obtained by the present invention has negative birefringence, is excellent in transparency, heat resistance, etc., and is excellent in thermal stability during high temperature processing, so as an optical film, retardation film, etc. It can be preferably used.

  EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

  Various physical properties shown in the examples were measured by the following methods.

~ Number average molecular weight ~
It was determined as a standard polystyrene equivalent value by an elution curve of a maleimide / olefin copolymer and a styrene copolymer measured using gel permeation chromatography (GPC) (trade name HLC-802A, manufactured by Tosoh Corporation). .

~ Glass transfer temperature ~
Using a differential scanning calorimeter (manufactured by Seiko Denshi Kogyo Co., Ltd., trade name DSC2000), the measurement was performed at a heating rate of 10 ° C./min.

~ Haze ~
The measurement was made according to JIS K7136.

~ Yellowness ~
The measurement was performed according to JIS K7105.

~ Three-dimensional refractive index ~
Measurement was performed at a measurement wavelength of 589 nm using a sample tilt type automatic birefringence meter (trade name KOBRA-WR, manufactured by Oji Scientific Instruments).

Synthesis Example 1 (Synthesis of N-phenylmaleimide / isobutene copolymer)
A stainless steel autoclave was charged with 128 parts by weight of N-phenylmaleimide, 0.19 parts by weight of t-butyl peroxypivalate and 390 parts by weight of methyl ethyl ketone, purged several times with nitrogen, and then charged with 83 parts by weight of liquefied isobutene at 60 ° C. For 8 hours. The solution after completion of the reaction was cooled to room temperature, gradually added to 1000 parts by weight of methanol for reprecipitation treatment, and then filtered and dried to obtain a copolymer.

^{From the 1} H-NMR measurement, it was confirmed that the produced copolymer was N-phenylmaleimide / isobutene copolymer of N-phenylmaleimide residue / isobutene residue = 0.57 / 0.43 (molar ratio). did. The number average molecular weight was 90000, and the glass transition temperature was 208 ° C.

Synthesis Example 2 (Synthesis of N- (2-methylphenyl) maleimide / isobutene copolymer)
A stainless steel autoclave was charged with 137 parts by weight of N- (2-methylphenyl) maleimide, 0.19 part by weight of t-butyl peroxypivalate and 390 parts by weight of methyl ethyl ketone, purged several times with nitrogen, and then 83 parts by weight of liquefied isobutene. Polymerization was carried out at 60 ° C. for 8 hours. The solution after completion of the reaction was cooled to room temperature, gradually added to 1000 parts by weight of methanol for reprecipitation treatment, and then filtered and dried to obtain a copolymer.

^{From the 1} H-NMR measurement, the resulting copolymer was N- (2-methylphenyl) N- (2-methylphenyl) phenylmaleimide residue / isobutene residue = 0.56 / 0.44 (molar ratio). It was confirmed to be a maleimide / isobutene copolymer. The number average molecular weight was 89000, and the glass transition temperature was 206 ° C.

Synthesis Example 3 (Synthesis of N-methylmaleimide / isobutene copolymer)
A stainless steel autoclave is filled with 100 parts by weight of maleic anhydride / isobutene copolymer (trade name Isoban 10 manufactured by Kuraray Co., Ltd.) and 500 parts by weight of NMP as a solvent, and stirred at room temperature to obtain a maleic anhydride / isobutene copolymer. Dissolved in NMP. Next, after 40 parts by weight of methylamine was introduced at room temperature, the temperature was raised to 80 ° C. and stirred for 1 hour to carry out amidation reaction of maleic anhydride units. Subsequently, after the temperature was raised to 205 ° C. and the mixture was stirred for 1 hour to carry out an imidization reaction, the mixture was cooled to room temperature and reprecipitated using isopropanol to obtain a copolymer.

From the elemental analysis, infrared absorption spectrum measurement and ¹³ C-NMR measurement, the resulting copolymer was N-methylmaleimide residue / isobutene residue = 0.50 / 0.50 (molar ratio). It was confirmed to be an isobutene copolymer. The number average molecular weight was 90000, and the glass transition temperature was 159 ° C.

Synthesis Example 4 (Synthesis of styrene / butyl acrylate copolymer)
A stainless steel autoclave is charged with 100 parts by weight of deionized water, 80 parts by weight of styrene, 20 parts by weight of butyl acrylate, 0.02 parts by weight of di-t-butyl-p-cresol, and 0.2 parts by weight of sodium sulfate and stirred. The temperature was raised to 105 ° C. Next, 0.01 part by weight of di-t-butyl peroxide dissolved in a small amount of styrene was added. Thereafter, the temperature was raised to 145 ° C. to carry out a polymerization reaction, followed by cooling to room temperature, filtration, washing and drying to obtain a copolymer.

^{From the 1} H-NMR measurement, it was confirmed that the produced copolymer was a styrene / butyl acrylate copolymer of styrene residue / butyl acrylate residue = 0.83 / 0.17 (molar ratio). The number average molecular weight was 100,000 and the glass transition temperature was 92 ° C.

Synthesis Example 5 (Synthesis of styrene / ethyl methacrylate copolymer)
A stainless steel autoclave is charged with 100 parts by weight of deionized water, 75 parts by weight of styrene, 25 parts by weight of ethyl methacrylate, 0.02 parts by weight of di-t-butyl-p-cresol, and 0.2 parts by weight of sodium sulfate, and stirred. The temperature was raised to 105 ° C. Next, 0.01 part by weight of di-t-butyl peroxide dissolved in a small amount of styrene was added. Thereafter, the temperature was raised to 145 ° C. to carry out a polymerization reaction, followed by cooling to room temperature, filtration, washing and drying to obtain a copolymer.

^{From the 1} H-NMR measurement, it was confirmed that the produced copolymer was a styrene / ethyl methacrylate copolymer having a styrene residue / ethyl methacrylate residue = 0.77 / 0.23 (molar ratio). The number average molecular weight was 100,000, and the glass transition temperature was 100 ° C.

Example 1
50% by weight of the N-phenylmaleimide / isobutene copolymer obtained in Synthesis Example 1 and a styrene / acrylonitrile copolymer (manufactured by Daicel Polymer, trade name Sebian N050, weight average molecular weight = 130,000, acrylonitrile residue unit: styrene residue) Unit (weight ratio) = 25: 75) To 100 parts by weight of the total amount consisting of 50% by weight, pentaerythritol-tetrakis (3- (3,5-di-t-butyl-4-hydroxy) as a phenolic antioxidant (Phenyl) propionate) 0.05 parts by weight, 0.15 parts by weight of bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite as a phosphorus-based antioxidant was dry blended, and then 30 mmφ2 Extrusion using a shaft extruder (made by Nippon Steel Works, trade name: TEX30) To obtain a transparent resin composition. The transparent resin composition obtained had a glass transition temperature of 136 ° C.

  Next, the obtained transparent resin composition was subjected to a twin-screw extruder provided with a T die set at a T die temperature of 270 ° C. and a cooling roll temperature of 116 ° C. to obtain a film having a thickness of 100 μm.

  A 50 × 50 mm piece was cut out from the obtained film and doubled freely using a biaxial stretching device (manufactured by Imoto Seisakusho Co., Ltd.) at a temperature of 145 ° C., a distance between chucks of 40 mm, and a stretching speed of 100 mm / min. An optical film was obtained by uniaxially stretching the width. The obtained optical film exhibited negative birefringence and was excellent in transparency, color tone, and appearance, and could be applied as a retardation film. The results of measuring physical properties using this film are shown in Table 1.

Example 2
50% by weight of the N-phenylmaleimide / isobutene copolymer obtained in Synthesis Example 1 and a styrene / acrylonitrile copolymer (manufactured by Daicel Polymer, trade name Sebian N080, weight average molecular weight = 130,000, acrylonitrile residue unit: styrene residue) Unit (weight ratio) = 29: 71) Ethylene bis (oxyethylene) bis (3- (5-t-butyl-4-hydroxy-) as a phenolic antioxidant for a total amount of 100 parts by weight consisting of 50% by weight. m-tolyl) propionate) 0.06 parts by weight and 0.2 parts by weight of tris (2,4-di-t-butylphenyl) phosphite as a phosphorus-based antioxidant were dry blended and then 30 mmφ twin screw extruder (stock) A transparent resin composition was obtained by extrusion using a product manufactured by Japan Steel Works, trade name TEX30). The transparent resin composition obtained had a glass transition temperature of 136 ° C.

  Next, the obtained transparent resin composition was subjected to a twin-screw extruder provided with a T die set at a T die temperature of 270 ° C. and a cooling roll temperature of 116 ° C. to obtain a film having a thickness of 100 μm.

  A 50 × 50 mm piece was cut out from the obtained film and doubled freely using a biaxial stretching device (manufactured by Imoto Seisakusho Co., Ltd.) at a temperature of 145 ° C., a distance between chucks of 40 mm, and a stretching speed of 100 mm / min. An optical film was obtained by uniaxially stretching the width. The obtained optical film exhibited negative birefringence and was excellent in transparency, color tone, and appearance, and could be applied as a retardation film. The results of measuring physical properties using this film are shown in Table 1.

Example 3
50% by weight of the N-phenylmaleimide / isobutene copolymer obtained in Synthesis Example 1 and a styrene / acrylonitrile copolymer (manufactured by Daicel Polymer, trade name Sebian N050, weight average molecular weight = 130,000, acrylonitrile residue unit: styrene residue) Unit (weight ratio) = 25: 75) Octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) 0 as a phenolic antioxidant with respect to a total amount of 100 parts by weight consisting of 50% by weight 0.05 weight part, 0.17 part by weight of tris (2,4-di-t-butylphenyl) phosphite as phosphorus antioxidant, 3- (3,4-dimethylphenyl) -5 as lactone stabilizer , 7-di-t-butyl-3H-benzofuran-2-one 0.045 parts by weight, and dry blended, 30 mm Machine (manufactured by Japan Steel Works, Ltd., trade name TEX30) was obtained was subjected to extrusion, the transparent resin composition. The transparent resin composition obtained had a glass transition temperature of 136 ° C.

  Next, the obtained transparent resin composition was subjected to a twin-screw extruder provided with a T die set at a T die temperature of 270 ° C. and a cooling roll temperature of 116 ° C. to obtain a film having a thickness of 100 μm.

  A 50 × 50 mm piece was cut out from the obtained film and doubled freely using a biaxial stretching device (manufactured by Imoto Seisakusho Co., Ltd.) at a temperature of 145 ° C., a distance between chucks of 40 mm, and a stretching speed of 100 mm / min. An optical film was obtained by uniaxially stretching the width. The obtained optical film exhibited negative birefringence and was excellent in transparency, color tone, and appearance, and could be applied as a retardation film. The results of measuring physical properties using this film are shown in Table 1.

Example 4
100 parts by weight in total consisting of 60% by weight of the N- (2-methylphenyl) maleimide / isobutene copolymer obtained in Synthesis Example 2 and 40% by weight of the styrene / butyl acrylate copolymer obtained in Synthesis Example 4 In contrast, 0.06 parts by weight of pentaerythritol-tetrakis (3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate) as a phenolic antioxidant and bis (2, 0.18 parts by weight of 4-bis (1,1-dimethylethyl) -6-methylphenyl) ethyl ester phosphorous acid, 3- (3,4-dimethylphenyl) -5,7-di- as a lactone stabilizer After dry blending 0.09 part by weight of t-butyl-3H-benzofuran-2-one, a 30 mmφ twin screw extruder (manufactured by Nippon Steel Works, trade name TE Was subjected to 30) were obtained extruded, a transparent resin composition. The obtained transparent resin composition had a glass transition temperature of 135 ° C.

  Next, the obtained transparent resin composition was subjected to a twin-screw extruder provided with a T die set at a T die temperature of 270 ° C. and a cooling roll temperature of 116 ° C. to obtain a 100 μm film.

  A 50 × 50 mm piece was cut out from the obtained film and doubled freely using a biaxial stretching device (manufactured by Imoto Seisakusho Co., Ltd.) at a temperature of 145 ° C., a distance between chucks of 40 mm, and a stretching speed of 100 mm / min. An optical film was obtained by uniaxially stretching the width. The obtained optical film exhibited negative birefringence and was excellent in transparency, color tone, and appearance, and could be applied as a retardation film. The results of measuring physical properties using this film are shown in Table 1.

Example 5
A total amount of 100 parts by weight comprising 50% by weight of the N- (2-methylphenyl) maleimide / isobutene copolymer obtained in Synthesis Example 2 and 50% by weight of the styrene / ethyl methacrylate ester obtained in Synthesis Example 5. In contrast, 0.06 parts by weight of pentaerythritol-tetrakis (3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate) as a phenolic antioxidant and tetrakis (2, 4-di-t-butylphenyl) (1,1-biphenyl) -4,4′-diylbisphosphonite 0.18 parts by weight, 3- (3,4-dimethylphenyl) -5 as a lactone stabilizer , 7-di-t-butyl-3H-benzofuran-2-one 0.09 parts by weight, and then dry blended, 30 mmφ twin screw extruder (manufactured by Nippon Steel Works, Ltd.) Was obtained extruded, a transparent resin composition is subjected to product name TEX30). The obtained transparent resin composition had a glass transition temperature of 134 ° C.

  Next, the obtained transparent resin composition was subjected to a twin-screw extruder provided with a T die set at a T die temperature of 270 ° C. and a cooling roll temperature of 116 ° C. to obtain a film having a thickness of 100 μm.

  A 50 × 50 mm piece was cut out from the obtained film and doubled freely using a biaxial stretching device (manufactured by Imoto Seisakusho Co., Ltd.) at a temperature of 145 ° C., a distance between chucks of 40 mm, and a stretching speed of 100 mm / min. An optical film was obtained by uniaxially stretching the width. The obtained optical film exhibited negative birefringence and was excellent in transparency, color tone, and appearance, and could be applied as a retardation film. The results of measuring physical properties using this film are shown in Table 1.

Example 6
A small piece of 50 × 50 mm was cut out from the film obtained in Example 1, and using a biaxial stretching device (manufactured by Imoto Seisakusho Co., Ltd.), a temperature of 145 ° C., a distance between chucks of 40 mm, and a stretching speed of 100 mm / min. The optical film was obtained by simultaneously biaxially stretching 1.5 times. The obtained optical film exhibited negative birefringence, was excellent in transparency, color tone, and appearance, and was applicable as a retardation film. The results of measuring physical properties using this film are shown in Table 1.

Comparative Example 1
For 100 parts by weight of the N- (2-methylphenyl) maleimide / isobutene copolymer obtained in Synthesis Example 2, pentaerythritol-tetrakis (3- (3,5-di-t-butyl) was used as a phenolic antioxidant. -4-hydroxyphenyl) propionate) 0.05 parts by weight, 0.15 parts by weight of bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite as a phosphorus-based antioxidant is dry blended Then, it was subjected to extrusion using a 30 mmφ twin-screw extruder (manufactured by Nippon Steel Works, trade name: TEX30) to obtain a resin composition. The resulting resin composition had a glass transition temperature of 206 ° C.

  Next, the obtained resin composition was subjected to a twin-screw extruder provided with a T die set at a T die temperature of 320 ° C. and a cooling roll temperature of 150 ° C. to obtain a film having a thickness of 100 μm.

  A 50 × 50 mm piece was cut out from the obtained film and doubled freely using a biaxial stretching device (manufactured by Imoto Seisakusho Co., Ltd.) at a temperature of 220 ° C., a chuck distance of 40 mm, and a stretching speed of 100 mm / min. A stretched film was obtained by uniaxially stretching the width. Although the obtained stretched film showed negative birefringence, it was inferior in transparency and color tone and contained many black burnt-like foreign matters. The results of measuring physical properties using this film are shown in Table 2.

Comparative Example 2
Styrene / acrylonitrile copolymer (manufactured by Daicel Polymer, trade name Ceviane N080, weight average molecular weight = 130,000, acrylonitrile residue unit: styrene residue unit (weight ratio) = 29: 71) per 100 parts by weight of phenolic antioxidant 0.05 parts by weight of pentaerythritol-tetrakis (3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate) as an agent and bis (2,6-di-t-butyl as a phosphorus-based antioxidant After dry blending 0.15 part by weight of -4-methylphenyl) pentaerythritol diphosphite, the mixture was extruded using a 30 mmφ twin-screw extruder (manufactured by Nippon Steel Works, Ltd., trade name: TEX30) to obtain a resin composition. The resulting resin composition had a glass transition temperature of 105 ° C.

  Next, the obtained resin composition was subjected to a twin-screw extruder provided with a T die set at a T die temperature of 240 ° C. and a cooling roll temperature of 90 ° C. to obtain a film having a thickness of 100 μm.

  A 50 × 50 mm piece was cut out from the obtained film and doubled freely using a biaxial stretching apparatus (manufactured by Imoto Seisakusho Co., Ltd.) at a temperature of 115 ° C., a distance between chucks of 40 mm, and a stretching speed of 100 mm / min. A stretched film was obtained by uniaxially stretching the width. The obtained stretched film showed negative birefringence but poor heat resistance. The results of measuring physical properties using this film are shown in Table 2.

Comparative Example 3
0.05 parts by weight of pentaerythritol-tetrakis (3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate) and bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol A resin composition, a film, and a stretched film were obtained in the same manner as in Example 1 except that 0.15 parts by weight of diphosphite was not added. The resulting resin composition had a glass transition temperature of 136 ° C. Moreover, although the obtained stretched film showed negative birefringence, yellowing was recognized and it contained a black burnt-like foreign material. The results of measuring physical properties using this film are shown in Table 2.

Comparative Example 4
65% by weight of the N-methylmaleimide / isobutene copolymer obtained in Synthesis Example 3 and a styrene / acrylonitrile copolymer (manufactured by Daicel Polymer, trade name Sebian N080, weight average molecular weight = 130,000, acrylonitrile residue unit: styrene residue) Unit (weight ratio) = 29: 71) To 100 parts by weight of the total amount consisting of 35% by weight, pentaerythritol-tetrakis (3- (3,5-di-t-butyl-4-hydroxy) as a phenolic antioxidant (Phenyl) propionate) 0.05 parts by weight, 0.15 parts by weight of bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite as a phosphorus-based antioxidant was dry blended, and then 30 mmφ2 Extrusion to a shaft extruder (product name: TEX30, manufactured by Nippon Steel) To obtain a fat composition. The resulting resin composition had a glass transition temperature of 132 ° C.

  Next, the obtained resin composition was subjected to a twin-screw extruder provided with a T die set at a T die temperature of 270 ° C. and a cooling roll temperature of 110 ° C. to obtain a film having a thickness of 100 μm.

  Subsequently, a 50 × 50 mm piece was cut out from the obtained film and doubled using a biaxial stretching apparatus (manufactured by Imoto Seisakusho Co., Ltd.) at a temperature of 142 ° C., a distance between chucks of 40 mm, and a stretching speed of 100 mm / min. A stretched film was obtained by uniaxially stretching a free width. The obtained stretched film showed positive birefringence. In addition, birefringence, which is a difference in refractive index between axial directions perpendicular to each other, is very small in both the in-plane direction and the film thickness direction, and cannot be used as a retardation film. The results of measuring physical properties using this film are shown in Table 2.

Claims (8)

An N-phenyl-substituted maleimide / olefin copolymer comprising a unit represented by the following general formula (I) and a unit represented by the following general formula (II) and having a number average molecular weight of 1 × 10 ³ or more and 5 × 10 ⁶ or less. 30 to 95% by weight, and a styrene copolymer comprising at least one monomer selected from the group consisting of a styrene monomer and a vinyl cyanide compound, an alkyl acrylate ester, and an alkyl methacrylate ester A total of 100 parts by weight of 70 to 5% by weight is blended with 0.001 to 2 parts by weight of a phenolic antioxidant and / or phosphorus antioxidant and 0.001 to 2 parts by weight of a lactone stabilizer. A transparent resin composition characterized by exhibiting negative birefringence.

(Where R1 is phenyl group, naphthyl group, halogen element, carboxylic acid, carboxylic ester, hydroxyl group, cyano group, nitro group, linear alkyl group having 1 to 8 carbon atoms, branched chain having 1 to 8 carbon atoms. Represents a phenyl group or a naphthyl group substituted with a linear alkyl group.)

(Here, R2 and R3 each independently represent hydrogen or an alkyl group having 1 to 6 carbon atoms.) The phenolic antioxidant is pentaerythritol-tetrakis (3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate), octadecyl-3- (3,5-di-tert-butyl-4-hydroxy) It is at least one phenolic antioxidant selected from the group consisting of phenyl) propionate and ethylenebis (oxyethylene) bis (3- (5-t-butyl-4-hydroxy-m-tolyl) propionate). The transparent resin composition according to claim 1. Phosphorus antioxidant is tris (2,4-di-t-butylphenyl) phosphite, bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite, bis (2,4 The bis (1,1-dimethylethyl) -6-methylphenyl) ethyl ester phosphorous acid is at least one phosphorous antioxidant selected from the group consisting of phosphorous acid. The transparent resin composition in any one. An N-phenyl-substituted maleimide / olefin copolymer comprising a unit represented by the general formula (I) and a unit represented by the general formula (II) and having a number average molecular weight of 1 × 10 ³ or more and 5 × 10 ⁶ or less. 30 to 95% by weight, and a styrene copolymer comprising at least one monomer selected from the group consisting of a styrene monomer and a vinyl cyanide compound, an alkyl acrylate ester, and an alkyl methacrylate ester 4. The composition according to claim 1 , wherein 0.001 to 2 parts by weight of a phenol-based antioxidant and a phosphorus-based antioxidant are blended with 100 parts by weight of a total amount of 70 to 5% by weight. transparent resin composition according to any. Optical film characterized by comprising a transparent resin composition according to any one of claims 1 to 4. The optical film according to claim 5, wherein the optical film has a haze of 1% or less in accordance with JIS K7136 and a yellowness of 2% or less in accordance with JIS K7105. The optical film according to claim 5, wherein the optical film exhibits negative birefringence, the stretching direction is an x axis in the film plane, and the orthogonal direction in the film plane with respect to the x axis is the y axis, When the vertical direction out of the film plane with respect to the x-axis is the z-axis, the x-axis direction refractive index is nx, the y-axis direction refractive index is ny, and the z-axis direction refractive index is nz, the relationship of the three-dimensional refractive index is nz. A retardation film, wherein ≧ ny> nx or ny ≧ nz> nx. 7. The optical film according to claim 5, wherein the optical film exhibits negative birefringence, the stretching direction is an x axis in the film plane and a y axis in the film plane, and a vertical direction outside the film plane is When the z-axis, the x-axis direction refractive index is nx, the y-axis direction refractive index is ny, and the z-axis direction refractive index is nz, the relationship of the three-dimensional refractive index is nz> ny ≧ nx or nz> nx ≧ ny. A retardation film characterized by comprising: