JP2014181256A - Resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin composition having improved heat resistance.SOLUTION: A resin composition comprises an acrylic copolymer including a first structural unit represented by the following formula (1), a second structural unit represented by the following formula (2), and a third structural unit represented by the following formula (3), and a phosphaphenanthrene compound represented by the following formula (A). The content of the phosphaphenanthrene compound is 0.01-2 pts.mass based on 100 pts.mass of the acrylic copolymer. The acrylic copolymer comprises, on the basis of the total amount of the acrylic copolymer, 50-95 mass% of the first structural unit, 0.1-20 mass% of the second structural unit, and 0.1-49.9 mass% of the third structural unit.

Description

  The present invention relates to a resin composition.

  In recent years, with the progress of flat panel displays such as liquid crystal display devices, plasma displays, organic EL display devices, infrared sensors, optical waveguides, etc., not only has excellent transparency, but also optical characteristics as optical materials (so-called low birefringence) ) Has been demanded (Patent Document 1).

  On the other hand, when assuming automotive parts, for example, tail lamps are larger than conventional optical materials in terms of both the increase in size of the lamp itself, the increase in heat generation resulting from increased illuminance, and the reduction in thickness due to cost reduction. Optical materials having high heat resistance are required. In addition, for example, in the case of a vehicle instrument cover, in recent years, from the viewpoint of the design of the vehicle interior, the visibility of the instruments, etc., the case where it is attached to a position that is easily exposed to direct sunlight has increased. There is a need for heat-resistant optical materials for parts that are extremely hot under direct sunlight, such as motorcycle cover for motorcycles and water heater covers that use solar thermal energy. (Patent Document 2).

  Methyl methacrylate / styrene / maleic anhydride as a resin with excellent mechanical properties, weather resistance and transparency equivalent to those of conventional methacrylic resins, and excellent heat resistance that conventional methacrylic resins could not have Copolymers are widely known (Patent Document 1, Patent Document 3). As a methacrylic resin having heat resistance and low birefringence, a copolymer comprising a methyl methacrylate monomer and one or more N-substituted maleimide monomer units is known ( Patent Document 4).

  Since the copolymer has higher heat resistance than ordinary methacrylic resin (for example, PMMA), high temperature molding is required, and at that time, it is easy to be colored (thermal coloring). Various studies have been made to improve this thermal coloring. For example, in the above-described system for maleic anhydride polymerization, general-purpose phenolic compounds, amine compounds, metals as thermal coloring and thermal degradation inhibitors for thermoplastic resins. Even if soap, a phosphite compound, a phosphate compound, and a sulfur-containing compound are added, a remarkable effect on thermal stability cannot be obtained, and the combined use of these compounds also provides a sufficient effect on thermal coloring. And the only phosphaphenanthrene compound has been found to be effective in improving thermal stability. (Patent Document 5)

  Further, by combining a specific phosphorus compound with a low birefringence methacrylic resin (methyl methacrylate / styrene / maleic anhydride / benzyl methacrylate copolymer) whose birefringence is improved to be smaller than that of ordinary PMMA, A technique is known that improves thermal stability while maintaining heat resistance (Patent Document 6).

  On the other hand, methacrylic resins having extremely small birefringence, excellent heat resistance, and long-term stability of birefringence under wet heat conditions are known. The methacrylic resin is a copolymer resin containing a methyl methacrylate monomer unit, an N-aromatic substituted maleimide monomer unit and an N-alicyclic alkyl substituted maleimide monomer unit as essential components. Refractive properties, orientation birefringence, and photoelastic birefringence are all zero (so-called optical isotropy) (Patent Document 7).

Japanese Patent No. 2886893 Japanese Patent Laid-Open No. 60-60150 International Publication No. 2007/061041 Japanese Patent Laid-Open No. 6-242301 Japanese Examined Patent Publication No. 6-99610 JP 2011-001526 A International Publication No. 2011/149088

  However, the methyl methacrylate / styrene / maleic anhydride / benzyl methacrylate copolymer is easily changed in the resin structure due to the influence of moisture in the atmosphere (the ring structure is ring-opened by hydrolysis). May not be suitable. In addition, methyl methacrylate / N-aromatic substituted maleimide / N-cycloaliphatic alkyl substituted maleimide copolymer has high melt resin viscosity at the time of molding and requires high-temperature melt molding, so it is thermally stable. There is a need for improvement in performance.

  Therefore, an object of the present invention is to provide a resin composition having improved thermal stability.

  The present invention is based on the finding of the present inventors that a resin composition containing a specific acrylic copolymer and a specific organophosphorus compound is remarkably excellent in thermal stability.

［式中、Ｒ^１は、水素原子、炭素数１〜１２のアルキル基、炭素数５〜１２のシクロアルキル基、炭素数７〜１４のアリールアルキル基、炭素数６〜１４のアリール基、又は、下記Ａ群より選ばれる少なくとも一種の置換基を有する炭素数６〜１４のアリール基、を示す。
Ａ群：ハロゲン原子、ヒドロキシル基、ニトロ基、炭素数１〜１２のアルコキシ基及び炭素数１〜１２のアルキル基。］

［式中、Ｒ^２は、炭素数７〜１４のアリールアルキル基、炭素数６〜１４のアリール基、又は、下記Ｂ群より選ばれる少なくとも一種の置換基を有する炭素数６〜１４のアリール基、を示し、Ｒ^３及びＲ^４はそれぞれ独立に、水素原子、炭素数１〜１２のアルキル基又は炭素数６〜１４のアリール基を示す。
Ｂ群：ハロゲン原子、ヒドロキシル基、ニトロ基、炭素数１〜１２のアルコキシ基、炭素数１〜１２のアルキル基及び炭素数７〜１４のアリールアルキル基。］

［式中、Ｒ^５は、水素原子、炭素数３〜１２のシクロアルキル基、炭素数１〜１２のアルキル基、又は、下記Ｃ群より選ばれる少なくとも一種の置換基を有する炭素数１〜１２のアルキル基、を示し、Ｒ^６及びＲ^７はそれぞれ独立に、水素原子、炭素数１〜１２のアルキル基又は炭素数６〜１４のアリール基を示す。
Ｃ群：ハロゲン原子、ヒドロキシル基、ニトロ基及び炭素数１〜１２のアルコキシ基。］

［式中、Ｒ^１０は、水素原子、ヒドロキシル基、炭素数１〜４のアルキル基又は炭素数１〜４のアルコキシ基を示し、Ｒ^１１及びＲ^１２はそれぞれ独立に、水素原子、炭素数１〜８のアルキル基又は炭素数１〜８のアルコキシ基を示す。］
［２］ヒンダードフェノール系化合物、チオジプロピオン酸系化合物、及び、フォスファフェナンスレン系化合物に属しない亜リン酸エステル系化合物からなる群より選ばれる少なくとも１種の化合物を０．０１〜１質量部更に含む［１］記載の樹脂組成物。
［３］アクリル系共重合体におけるハロゲン原子の含有率が、アクリル系共重合体の総量基準で０．４７質量％未満である［１］又は［２］記載の樹脂組成物。
［４］第三の構造単位の含有量に対する第二の構造単位の含有量のモル比が、０より大きく１５以下である［１］〜［３］のいずれか１つに記載の樹脂組成物。
［５］アクリル系共重合体のＧＰＣ測定法によるポリメチルメタクリレート換算の重量平均分子量が、３０００〜１００００００であり、分子量分布が、１．５〜４．０である［１］〜［４］のいずれか１つに記載の樹脂組成物。 That is, the present invention relates to the following.
[1] Acrylic having a first structural unit represented by the following formula (1), a second structural unit represented by the following formula (2), and a third structural unit represented by the following formula (3) A phosphaphenanthrene compound represented by the following formula (A), wherein the content of the phosphaphenanthrene compound is 100 parts by mass with respect to 100 parts by mass of the acrylic copolymer. 0.01 to 2 parts by mass, and the acrylic copolymer is, based on the total amount, 50 to 95% by mass of the first structural unit, 0.1 to 20% by mass of the second structural unit, A resin composition having 0.1 to 49.9% by mass of a third structural unit.

[Wherein, R ¹ represents a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 5 to 12 carbon atoms, an arylalkyl group having 7 to 14 carbon atoms, an aryl group having 6 to 14 carbon atoms, or And an aryl group having 6 to 14 carbon atoms and having at least one substituent selected from the following group A.
Group A: a halogen atom, a hydroxyl group, a nitro group, an alkoxy group having 1 to 12 carbon atoms, and an alkyl group having 1 to 12 carbon atoms. ]

[Wherein, R ² represents an arylalkyl group having 7 to 14 carbon atoms, an aryl group having 6 to 14 carbon atoms, or an aryl group having 6 to 14 carbon atoms having at least one substituent selected from the following group B: R ³ and R ⁴ each independently represent a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, or an aryl group having 6 to 14 carbon atoms.
Group B: a halogen atom, a hydroxyl group, a nitro group, an alkoxy group having 1 to 12 carbon atoms, an alkyl group having 1 to 12 carbon atoms, and an arylalkyl group having 7 to 14 carbon atoms. ]

[Wherein, R ⁵ represents a hydrogen atom, a cycloalkyl group having 3 to 12 carbon atoms, an alkyl group having 1 to 12 carbon atoms, or at least one substituent having at least one substituent selected from the following group C. R ⁶ and R ⁷ each independently represents a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, or an aryl group having 6 to 14 carbon atoms.
Group C: a halogen atom, a hydroxyl group, a nitro group, and an alkoxy group having 1 to 12 carbon atoms. ]

[Wherein, R ¹⁰ represents a hydrogen atom, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, and R ¹¹ and R ¹² each independently represent a hydrogen atom, 1 carbon atom. -8 alkyl group or a C1-C8 alkoxy group is shown. ]
[2] At least one compound selected from the group consisting of a hindered phenol compound, a thiodipropionic acid compound, and a phosphite compound not belonging to a phosphaphenanthrene compound is 0.01 to The resin composition according to [1], further including 1 part by mass.
[3] The resin composition according to [1] or [2], wherein the content of halogen atoms in the acrylic copolymer is less than 0.47% by mass based on the total amount of the acrylic copolymer.
[4] The resin composition according to any one of [1] to [3], wherein the molar ratio of the content of the second structural unit to the content of the third structural unit is greater than 0 and 15 or less. .
[5] The weight average molecular weight in terms of polymethyl methacrylate as determined by GPC measurement of the acrylic copolymer is 3000 to 1000000, and the molecular weight distribution is 1.5 to 4.0. [1] to [4] The resin composition as described in any one.

  According to the present invention, a resin composition having improved thermal stability can be provided.

  Hereinafter, preferred embodiments of the present invention will be described in detail.

[Resin composition]
The resin composition of the present embodiment contains a specific acrylic copolymer and a specific phosphaphenanthrene compound. According to this resin composition, an excellent anti-coloring effect (that is, high thermal stability) is exhibited even when heat molding is performed at a high temperature.

[Acrylic copolymer]
The acrylic copolymer according to this embodiment has a first structural unit, a second structural unit, and a third structural unit.

(First structural unit)
The first structural unit is a structural unit represented by the following formula (1).

式中、Ｒ^１は、水素原子、炭素数１〜１２のアルキル基、炭素数５〜１２のシクロアルキル基、炭素数７〜１４のアリールアルキル基、炭素数６〜１４のアリール基、又は、下記Ａ群より選ばれる少なくとも一種の置換基を有する炭素数６〜１４のアリール基、を示す。ここで、Ａ群は、ハロゲン原子、ヒドロキシル基、ニトロ基、炭素数１〜１２のアルコキシ基及び炭素数１〜１２のアルキル基からなる群である。

In the formula, R ¹ is a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 5 to 12 carbon atoms, an arylalkyl group having 7 to 14 carbon atoms, an aryl group having 6 to 14 carbon atoms, or The C6-C14 aryl group which has at least 1 type of substituent chosen from the following A group is shown. Here, group A is a group consisting of a halogen atom, a hydroxyl group, a nitro group, an alkoxy group having 1 to 12 carbon atoms, and an alkyl group having 1 to 12 carbon atoms.

  In the present specification, the alkyl group may be linear or branched. Further, the alkyl group in the arylalkyl group and the alkyl group in the alkoxy group may be linear or branched.

Examples of the alkyl group having 1 to 12 carbon atoms in R ^1, preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms. The alkyl group having 1 to 12 carbon atoms in ^{R 1,} a methyl group, an ethyl group, n- propyl group, an isopropyl group, n- butyl group, an isobutyl group, t- butyl, 2-ethylhexyl, nonyl , A decanyl group, a lauryl group, etc. Among them, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group in terms of further improving the transparency and weather resistance of the acrylic copolymer. Group, isobutyl group, t-butyl group and 2-ethylhexyl group are preferable, and methyl group is more preferable.

Examples of the cycloalkyl group having 5 to 12 carbon atoms in R ¹ include a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a tricyclodecyl group, a bicyclooctyl group, a tricyclododecyl group, an isobornyl group, an adamantyl group, a tetra Examples thereof include a cyclododecyl group, and among these, a cyclopentyl group, a cyclohexyl group, a cyclooctyl group, a tricyclodecyl group, a bicyclooctyl group, a tricyclododecyl group, and an isobornyl group are preferable.

Examples of the arylalkyl group having 7 to 14 carbon atoms in R ¹ include benzyl group, 1-phenylethyl group, 2-phenylethyl group, 3-phenylpropyl group, 6-phenylhexyl group, and 8-phenyloctyl group. Of these, benzyl, 1-phenylethyl, 2-phenylethyl, and 3-phenylpropyl are preferred.

Examples of the aryl group having 6 to 14 carbon atoms in R ¹ include a phenyl group, a naphthyl group, and an anthracenyl group, and among these, a phenyl group is preferable.

R ¹ may be an aryl group having 6 to 14 carbon atoms having a substituent, wherein the substituent is a halogen atom, a hydroxyl group, a nitro group, an alkoxy group having 1 to 12 carbon atoms, or an alkyl group having 1 to 12 carbon atoms. These are groups selected from the group consisting of alkyl groups (group A).

In R ¹ , the aryl group having 6 to 14 carbon atoms having a substituent is preferably a phenyl group having a substituent. Examples of the aryl group having 6 to 14 carbon atoms having a substituent include 2,4,6-tribromophenyl group, 2-chlorophenyl group, 4-chlorophenyl group, 2-bromophenyl group, 4-bromophenyl group, 2-methylphenyl group, 4-methylphenyl group, 2-ethylphenyl group, 4-ethylphenyl group, 2-methoxyphenyl group, 4-methoxyphenyl group, 2-nitrophenyl group, 4-nitrophenyl group, 2, Examples include 4,6-trimethylphenyl group. Among these, 2,4,6-tribromophenyl group is preferable in terms of imparting flame retardancy.

  The content of the first structural unit is preferably contained in an amount superior to other structural units in order to maintain the excellent transparency, weather resistance and mechanical properties of the acrylic copolymer. It is 50 to 95% by mass based on the total amount of the polymer, preferably 60 to 95% by mass, more preferably 65 to 95% by mass, still more preferably 70 to 90% by mass, and particularly preferably 70 to 85% by mass. . If content of a 1st structural unit is 50 mass% or more, a total light transmittance and environmental resistance will also improve.

  The acrylic copolymer may contain only one kind of the first structural unit, or may contain two or more kinds of the first structural unit.

For example, the acrylic copolymer may have a structural unit in which R ¹ is an alkyl group and a structural unit in which R ¹ is an arylalkyl group or an aryl group. At this time, the content of the latter structural unit is preferably 0.1 to 10% by mass, more preferably 0.1 to 8% by mass, based on the total amount of the acrylic copolymer, More preferably, it is -6 mass%. According to the acrylic copolymer in this range, an effect of improving optical properties such as birefringence can be obtained without a large decrease in heat resistance.

  The first structural unit is formed from, for example, a first monomer selected from methacrylic acid monomers and methacrylic acid esters. The first monomer can be represented by the following formula (1-a).

式中、Ｒ^１は式（１）におけるＲ^１と同義である。

Wherein, ^{R 1} has the same meaning as ^{R 1} in Formula (1).

  Examples of the methacrylic acid ester include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate; methacrylic acid. Cyclopentyl, cyclohexyl methacrylate, cyclooctyl methacrylate, tricyclodecyl methacrylate, fine cyclooctyl methacrylate, tricyclododecyl methacrylate, isobornyl methacrylate, phenyl methacrylate, benzyl methacrylate, 1-phenylethyl methacrylate, methacrylic acid Examples include 2-phenoxyethyl, 3-phenylpropyl methacrylate, 2,4,6-tribromophenyl methacrylate, and the like. These first monomers may be used alone or in combination of two or more. Of the methacrylic acid esters, methyl methacrylate and benzyl methacrylate are preferred in that the acrylic copolymer obtained has excellent transparency and weather resistance. Moreover, 2,4,6-tribromophenyl methacrylate is preferable in terms of imparting flame retardancy.

(Second structural unit)
The second structural unit is a structural unit represented by the following formula (2).

式中、Ｒ^２は、炭素数７〜１４のアリールアルキル基、炭素数６〜１４のアリール基、又は、下記Ｂ群より選ばれる少なくとも一種の置換基を有する炭素数６〜１４のアリール基、を示し、Ｒ^３及びＲ^４はそれぞれ独立に、水素原子、炭素数１〜１２のアルキル基又は炭素数６〜１４のアリール基を示す。Ｂ群は、ハロゲン原子、ヒドロキシル基、ニトロ基、炭素数１〜１２のアルコキシ基、炭素数１〜１２のアルキル基及び炭素数７〜１４のアリールアルキル基からなる群である。

In the formula, R ² is an arylalkyl group having 7 to 14 carbon atoms, an aryl group having 6 to 14 carbon atoms, or an aryl group having 6 to 14 carbon atoms having at least one substituent selected from the following group B; R ³ and R ⁴ each independently represent a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, or an aryl group having 6 to 14 carbon atoms. Group B is a group consisting of a halogen atom, a hydroxyl group, a nitro group, an alkoxy group having 1 to 12 carbon atoms, an alkyl group having 1 to 12 carbon atoms, and an arylalkyl group having 7 to 14 carbon atoms.

Examples of the arylalkyl group having 7 to 14 carbon atoms in R ² include benzyl group, 1-phenylethyl group, 2-phenylethyl group, 3-phenylpropyl group, 6-phenylhexyl group, and 8-phenyloctyl group. Of these, a benzyl group is preferred in terms of further improving optical properties such as heat resistance and low birefringence.

Examples of the aryl group having 6 to 14 carbon atoms in R ² include a phenyl group, a naphthyl group, and an anthracenyl group. Among these, in terms of further improving optical characteristics such as heat resistance and low birefringence, A phenyl group is preferred.

R ² may be an aryl group having 6 to 14 carbon atoms having a substituent, wherein the substituent is a halogen atom, a hydroxyl group, a nitro group, an alkoxy group having 1 to 12 carbon atoms, or an alkyl group having 1 to 12 carbon atoms. And a group selected from the group consisting of an alkyl group having 7 to 14 carbon atoms (group B).

  Examples of the halogen atom as a substituent include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

  As a C1-C12 alkoxy group as a substituent, a C1-C10 alkoxy group is preferable and a C1-C8 alkoxy group is more preferable. Moreover, as a C1-C12 alkoxy group as a substituent, a methoxy group, an ethoxy group, n-propyloxy group, isopropyloxy group, n-butyloxy group, isobutyloxy group, t-butyloxy group, 2-ethylhexyl An oxy group, 1-decyloxy group, 1-dodecyloxy group, etc. are mentioned.

Examples of the alkyl group having 1 to 12 carbon atoms and the arylalkyl group having 7 to 14 carbon atoms as the substituent are exemplified as the alkyl group having 1 to 12 carbon atoms and the arylalkyl group having 7 to 14 carbon atoms in R ¹ . Groups are exemplified as well.

In R ² , the aryl group having 6 to 14 carbon atoms having a substituent is preferably a phenyl group having a substituent or a naphthyl group having a substituent. Examples of the aryl group having 6 to 14 carbon atoms having a substituent include 2,4,6-tribromophenyl group, 2-chlorophenyl group, 4-chlorophenyl group, 2-bromophenyl group, 4-bromophenyl group, 2-methylphenyl group, 4-methylphenyl group, 2-ethylphenyl group, 4-ethylphenyl group, 2-methoxyphenyl group, 4-methoxyphenyl group, 2-nitrophenyl group, 4-nitrophenyl group, 2, Examples include 4,6-trimethylphenyl group. Among these, 2,4,6-tribromophenyl group is preferable in that flame retardancy is imparted.

Examples of the alkyl group having 1 to 12 carbon atoms in R ³ and ^{R 4,} preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms. Moreover, as a C1-C12 alkyl group in R < ³ > and R < ⁴ >, a methyl group, an ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, 2-ethylhexyl group , Nonyl group, decanyl group, lauryl group, etc. Among these, in terms of further improving the transparency and weather resistance of the acrylic copolymer, methyl group, ethyl group, n-propyl group, isopropyl group, An n-butyl group, an isobutyl group, a t-butyl group and a 2-ethylhexyl group are preferable, and a methyl group is more preferable.

Examples of the aryl group having 6 to 14 carbon atoms in R ³ and R ⁴ include a phenyl group, a naphthyl group, and an anthracenyl group, and among these, optical characteristics such as heat resistance and low birefringence are further improved. In this respect, a phenyl group is preferred.

R ³ and R ⁴ are preferably a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a phenyl group, and more preferably a hydrogen atom.

  The content of the second structural unit is from 0.1 to 20% by mass, preferably from 0.1 to 18% by mass, more preferably from the viewpoint of heat resistance and optical properties, based on the total amount of the acrylic copolymer. Is 0.1 to 16% by mass, more preferably 1 to 16% by mass. If the content of the second structural unit is within this range, the transparency of the resin is maintained, the yellowing does not occur, and the heat resistance is improved without impairing the environmental resistance.

  The acrylic copolymer may contain only one kind of the second structural unit, or may contain two or more kinds of the second structural unit.

  The second structural unit is formed from, for example, a second monomer selected from N-substituted maleimide compounds represented by the following formula (2-a).

^Wherein, R 2, ^{R 3} and ^{R 4} have the same meaning as ^R 2, ^{R 3} and ^{R 4} in each formula (2).

  As the second monomer, N-phenylmaleimide, N-benzylmaleimide, N- (2-chlorophenyl) maleimide, N- (4-chlorophenyl) maleimide, N- (4-bromophenyl) maleimide, N- ( 2-methylphenyl) maleimide, N- (2-ethylphenyl) maleimide, N- (2-methoxyphenyl) maleimide, N- (2-nitrophenyl) maleimide, N- (2,4,6-trimethylphenyl) maleimide N- (4-benzylphenyl) maleimide, N- (2,4,6-tribromophenyl) maleimide, N-naphthylmaleimide, N-anthracenylmaleimide, 3-methyl-1-phenyl-1H-pyrrole 2,5-dione, 3,4-dimethyl-1-phenyl-1H-pyrrole-2,5-dione, 1,3-diph Sulfonyl -1H- pyrrole-2,5-dione, 1,3,4-triphenyl -1H- pyrrole-2,5-dione, and the like. These second monomers may be used alone or in combination of two or more. Of these second monomers, N-phenylmaleimide and N-benzylmaleimide are preferred because the acrylic copolymer has excellent heat resistance and optical properties such as birefringence. Moreover, N- (2,4,6-tribromophenyl) maleimide is preferable in terms of imparting flame retardancy.

(Third structural unit)
The third structural unit is a structural unit represented by the following formula (3).

式中、Ｒ^５は、水素原子、炭素数３〜１２のシクロアルキル基、炭素数１〜１２のアルキル基、又は、下記Ｃ群より選ばれる少なくとも一種の置換基を有する炭素数１〜１２のアルキル基、を示し、Ｒ^６及びＲ^７はそれぞれ独立に、水素原子、炭素数１〜１２のアルキル基又は炭素数６〜１４のアリール基を示す。Ｃ群は、ハロゲン原子、ヒドロキシル基、ニトロ基及び炭素数１〜１２のアルコキシ基からなる群である。

In the formula, R ⁵ is a hydrogen atom, a C 3-12 cycloalkyl group, a C 1-12 alkyl group, or a C 1-12 having at least one substituent selected from the following group C. An alkyl group, and R ⁶ and R ⁷ each independently represent a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, or an aryl group having 6 to 14 carbon atoms. Group C is a group consisting of a halogen atom, a hydroxyl group, a nitro group, and an alkoxy group having 1 to 12 carbon atoms.

Examples of the cycloalkyl group having 3 to 12 carbon atoms in R ⁵ include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a tricyclodecyl group, a bicyclooctyl group, a tricyclododecyl group, Isobornyl group, adamantyl group, tetracyclododecyl group, etc., among these, cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group are preferred, and acrylic copolymer A cyclohexyl group is more preferable from the viewpoint that optical properties such as weather resistance and transparency are further improved and low water absorption can be imparted to the acrylic copolymer.

Examples of the alkyl group having 1 to 12 carbon atoms in R ^5, preferably an alkyl group having 1 to 10 carbon atoms, more preferably an alkyl group having 1 to 8 carbon atoms. The alkyl group having 1 to 12 carbon atoms in ^{R 5,} a methyl group, an ethyl group, n- propyl group, an isopropyl group, n- butyl group, an isobutyl group, t- butyl group, n- pentyl group, n- Hexyl group, n-octyl group, n-dodecyl group, n-octadecyl group, 2-ethylhexyl group, 1-decyl group, 1-dodecyl group and the like, among these, the weather resistance and the acrylic copolymer A methyl group, an ethyl group, and an isopropyl group are preferable because optical properties such as transparency are further improved.

R ⁵ may be a C 1-12 alkyl group having a substituent, wherein the substituent is a group consisting of a halogen atom, a hydroxyl group, a nitro group and a C 1-12 alkoxy group (Group C). ).

  Examples of the halogen atom as a substituent include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

  As a C1-C12 alkoxy group as a substituent, a C1-C10 alkoxy group is preferable and a C1-C8 alkoxy group is more preferable. Moreover, as a C1-C12 alkoxy group as a substituent, a methoxy group, an ethoxy group, n-propyloxy group, isopropyloxy group, n-butyloxy group, isobutyloxy group, t-butyloxy group, 2-ethylhexyl An oxy group, 1-decyloxy group, 1-dodecyloxy group, etc. are mentioned.

In R ⁵ , examples of the alkyl group having 1 to 12 carbon atoms having a substituent include a dichloromethyl group, a trichloromethyl group, a trifluoroethyl group, and a hydroxyethyl group, and among these, a trifluoroethyl group is preferable. It is.

Examples of the alkyl group having 1 to 12 carbon atoms in R ⁶ and ^{R 7,} preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms. The alkyl group having 1 to 12 carbon atoms in ^{R 6} and ^{R 7,} methyl group, ethyl group, n- propyl group, an isopropyl group, n- butyl group, an isobutyl group, t- butyl group, a 2-ethylhexyl group , Nonyl group, decanyl group, lauryl group, etc. Among these, in terms of further improving the transparency and weather resistance of the acrylic copolymer, methyl group, ethyl group, n-propyl group, isopropyl group, An n-butyl group, an isobutyl group, a t-butyl group and a 2-ethylhexyl group are preferable, and a methyl group is more preferable.

Examples of the aryl group having 6 to 14 carbon atoms in R ⁶ and R ⁷ include a phenyl group, a naphthyl group, and an anthracenyl group, and among these, optical characteristics such as heat resistance and low birefringence are further improved. In this respect, a phenyl group is preferred.

R ⁶ and R ⁷ are preferably a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a phenyl group, and more preferably a hydrogen atom.

  The content of the third structural unit is 0.1 to 49.9% by mass based on the total amount of the acrylic copolymer from the viewpoint of optical properties such as weather resistance, low water absorption, and transparency, preferably It is 0.1-40 mass%, More preferably, it is 0.1-35 mass%, More preferably, it is 1-30 mass%. If content of a 3rd structural unit is this range, transparency will be maintained and low hygroscopicity will be exhibited.

  The acrylic copolymer may contain only one third structural unit, or may contain two or more third structural units.

  The third structural unit is formed of, for example, a third monomer selected from N-substituted maleimide compounds represented by the following formula (3-a).

^Wherein, R 5, ^{R 6} and ^{R 7} have the same meanings as ^R 5, ^{R 6} and ^{R 7} in each formula (3).

  Examples of the third monomer include N-methylmaleimide, N-ethylmaleimide, Nn-propylmaleimide, N-isopropylmaleimide, Nn-butylmaleimide, N-isobutylmaleimide, and Ns-butyl. Maleimide, Nt-butylmaleimide, Nn-pentylmaleimide, Nn-hexylmaleimide, Nn-heptylmaleimide, Nn-octylmaleimide, N-laurylmaleimide, N-stearylmaleimide, N-cyclo Propylmaleimide, N-cyclobutylmaleimide, N-cyclopentylmaleimide, N-cyclohexylmaleimide, N-cycloheptylmaleimide, N-cyclooctylmaleimide, 1-cyclohexyl-3-methyl-1-phenyl-1H-pyrrole-2,5 -Dione, 1-cyclohex 3,4-dimethyl-1-phenyl-1H-pyrrole-2,5-dione, 1-cyclohexyl-3-phenyl-1H-pyrrole-2,5-dione, 1-cyclohexyl-3,4-diphenyl- 1H-pyrrole-2,5-dione and the like can be mentioned. These third monomers may be used alone or in combination of two or more. N-methylmaleimide, N-ethylmaleimide, N-isopropylmaleimide and N-cyclohexylmaleimide are preferred in recent years because of the excellent weather resistance of acrylic copolymers and excellent optical properties such as low birefringence. N-cyclohexylmaleimide is particularly preferable because of its low hygroscopicity required for the above.

  In the acrylic copolymer, the total content of the second structural unit and the third structural unit is preferably 5 to 50% by mass, more preferably 5 to 40% based on the total amount of the acrylic copolymer. It is 10 mass%, More preferably, it is 10-35 mass%, More preferably, it is 10-30 mass%, Most preferably, it is 15-30 mass%. When it is within this range, the acrylic copolymer can provide a more sufficient heat resistance improving effect, and more preferable effects for improving weather resistance, low water absorption, and optical properties. In addition, when the content of the second structural unit and the content of the third structural unit exceeds 50% by mass, the reactivity of the monomer component is reduced during the polymerization reaction, and the monomer that remains unreacted The amount increases, and the physical properties of the acrylic copolymer may decrease.

  In the acrylic copolymer, the molar ratio (M1 / M2) of the content (M1) of the second structural unit to the content (M2) of the third structural unit is desirably greater than 0 and 15 or less. From the viewpoint of optical characteristics (low birefringence, low photoelastic coefficient) described later, the molar ratio M1 / M2 is more preferably 10 or less. When the molar ratio M1 / M2 is within this range, the acrylic copolymer of the present embodiment exhibits much better optical properties.

  In the acrylic copolymer, the total content of the first structural unit, the second structural unit, and the third structural unit may be 80% by mass or more based on the total amount of the acrylic copolymer. . As a result, the acrylic copolymer exhibits better optical characteristics.

(Fourth structural unit)
The acrylic copolymer may further have a structural unit other than the above. For example, the acrylic copolymer has a fourth structural unit derived from another monomer copolymerizable with the first, second and third monomers within a range not impairing the object of the invention. Can have.

  Other monomers that can be copolymerized include aromatic vinyl; unsaturated nitrile; cyclohexyl group, benzyl group, or acrylic acid ester having an alkyl group having 1 to 18 carbon atoms; olefin; diene; vinyl ether; vinyl ester; Examples thereof include vinyl chloride; allyl ester or methallyl ester of saturated fatty acid monocarboxylic acid such as allyl propionate; polyvalent (meth) acrylate; polyvalent arylate; glycidyl compound; unsaturated carboxylic acid. The other monomer may be one or a combination of two or more selected from these groups.

  Examples of the aromatic vinyl include styrene, α-methylstyrene, divinylbenzene, and the like. Examples of the unsaturated nitrile include acrylonitrile, methacrylonitrile, ethacrylonitrile, phenylacrylonitrile and the like. Examples of the acrylic ester include methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl acrylate, isobutyl acrylate, tert-butyl acrylate, amyl acrylate, isoamyl acrylate, and acrylic acid. Examples include octyl, 2-ethylhexyl acrylate, decyl acrylate, lauryl acrylate, cyclohexyl acrylate, and benzyl acrylate.

  Examples of the olefin include ethylene, propylene, isobutylene, diisobutylene and the like. Examples of the diene include butadiene and isoprene. Examples of the vinyl ether include methyl vinyl ether and butyl vinyl ether. Examples of the vinyl ester include vinyl acetate and vinyl propionate. Examples of the vinyl fluoride include vinylidene fluoride.

  Examples of the polyvalent (meth) acrylate include ethylene glycol (meth) acrylate, diethylene glycol (meth) acrylate, trimethylolpropane tri (meth) acrylate, hexanediol di (meth) acrylate, pentaerythritol tetra (meth) acrylate, and dipenta Erythritol hexa (meth) acrylate, di (meth) acrylate of bisphenol A ethylene oxide or propylene oxide adduct, di (meth) acrylate of halogenated bisphenol A ethylene oxide or propylene oxide adduct, isocyanurate ethylene oxide or propylene Examples thereof include di- or tri (meth) acrylates of oxide adducts.

  Examples of the polyvalent arylate monomer include diallyl phthalate and triallyl isocyanurate. Examples of the glycidyl compound monomer include glycidyl (meth) acrylate and allyl glycidyl ether. Examples of the unsaturated carboxylic acid monomer include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, and half-esterified products or anhydrides thereof.

  The content of the fourth structural unit in the acrylic copolymer is preferably 0.1 to 20% by mass, and preferably 0.1 to 15% by mass based on the total amount of the acrylic copolymer. Is more preferable, and it is still more preferable that it is 0.1-10 mass%. When the content is in the above range, the hygroscopicity of the acrylic copolymer is further improved. From the viewpoint of weather resistance, the content is preferably less than 10% by mass, and more preferably less than 7% by mass.

  The acrylic thermoplastic resin may have only one kind of the fourth structural unit, or may have two or more kinds.

  An example of the fourth structural unit is a structural unit represented by the following formula (4).

In the formula, R ⁸ represents a hydrogen atom or an alkyl group having 1 to 12 carbon atoms, and R ⁹ represents a halogen atom, a hydroxyl group, a nitro group, an alkyl group having 1 to 12 carbon atoms or an alkoxy group having 1 to 12 carbon atoms. A represents an integer of 1 to 3.

Examples of the alkyl group having 1 to 12 carbon atoms in R ^8, preferably an alkyl group having 1 to 10 carbon atoms, more preferably an alkyl group having 1 to 8 carbon atoms. Examples of the alkyl group having 1 to 12 carbon atoms in R ⁹ include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, 2-ethylhexyl group, 1- A decyl group, 1-dodecyl group, etc. are mentioned, Among these, a methyl group is suitable.

Examples of the halogen atom for R ⁹ include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

Examples of the alkyl group having 1 to 12 carbon atoms in R ^9, preferably an alkyl group having 1 to 10 carbon atoms, more preferably an alkyl group having 1 to 8 carbon atoms. Examples of the alkyl group having 1 to 12 carbon atoms in R ⁹ include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, 2-ethylhexyl group, 1- Decyl group, 1-dodecyl group and the like. Among these, in terms of further improving the transparency and weather resistance of the acrylic thermoplastic resin, methyl group, ethyl group, n-propyl group, isopropyl group, n- A butyl group, an isobutyl group, a t-butyl group, and a 2-ethylhexyl group are preferable, and a methyl group is more preferable.

The alkoxy group having 1 to 12 carbon atoms in R ^9, preferably an alkoxy group having 1 to 10 carbon atoms, more preferably an alkoxy group having 1 to 8 carbon atoms. Moreover, as a C1-C12 alkoxy group as a substituent, a methoxy group, an ethoxy group, n-propyloxy group, isopropyloxy group, n-butyloxy group, isobutyloxy group, t-butyloxy group, 2-ethylhexyl Examples thereof include an oxy group, a 1-decyloxy group, and a 1-dodecyloxy group, and among these, a methoxy group is preferable.

  The structural unit represented by the formula (4) can be formed from, for example, a monomer represented by the following formula (4-a).

式中、Ｒ^８、Ｒ^９及びａはそれぞれ式（４）におけるＲ^８、Ｒ^９及びａと同義である。

^Wherein, R 8, ^{R 9} and a have the same meanings as ^R 8, ^{R 9} and a in each formula (4).

  Examples of the fourth monomer include styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2,4-dimethylstyrene, 2,5-dimethylstyrene, and 2-methyl-4-chlorostyrene. 2,4,6-trimethylstyrene, α-methylstyrene, cis-β-methylstyrene, trans-β-methylstyrene, 4-methyl-α-methylstyrene, 4-fluoro-α-methylstyrene, 4-chloro -Α-methylstyrene, 4-bromo-α-methylstyrene, 4-t-butylstyrene, 2-fluorostyrene, 3-fluorostyrene, 4-fluorostyrene, 2,4-difluorostyrene, 2-chlorostyrene, 3 -Chlorostyrene, 4-chlorostyrene, 2,4-dichlorostyrene, 2,6-dichlorostyrene, 2-bromostyrene Down, 3-bromostyrene, 4-bromostyrene, 2,4-dibromostyrene, alpha-bromostyrene, beta-bromostyrene, 2-hydroxystyrene, 4-hydroxystyrene, and the like. These monomers may be used alone or in combination of two or more. From the point that it is excellent in copolymerizability with the first monomer, the second monomer, and the third monomer constituting the acrylic copolymer, and the optical properties can be adjusted with a small amount of use. Styrene and α-methylstyrene are particularly preferred. These fourth monomers may be used alone or in combination of two or more.

  The acrylic copolymer may contain a repeating unit derived from another monomer copolymerizable with the above monomer as long as the object of the present invention is not impaired. Other monomers that can be copolymerized include aromatic vinyl; unsaturated nitrile; cyclohexyl group, benzyl group, or acrylic acid ester having an alkyl group having 1 to 18 carbon atoms; olefin; diene; vinyl ether; vinyl ester; Examples thereof include vinyl halides; allyl esters or methacrylic esters of saturated fatty acid monocarboxylic acids such as allyl propionate; polyvalent (meth) acrylates; polyvalent arylates; glycidyl compounds; unsaturated carboxylic acids. These monomers may be one or a combination of two or more selected from these groups.

  It is preferable that the weight average molecular weight (Mw) of PMMA conversion by the GPC measuring method of an acryl-type copolymer is 3000-1 million. If the weight average molecular weight is 3000 or more, the strength required as a polymer can be easily obtained. Moreover, if a weight average molecular weight is 1000000 or less, it will become easy to set it as the molded object by press molding. The weight average molecular weight of the acrylic copolymer is more preferably from 4,000 to 800,000, further preferably from 5,000 to 500,000, still more preferably from 100,000 to 500,000.

  As for the molecular weight distribution (Mw / Mn) by the GPC measuring method of an acryl-type copolymer, it is desirable that it is 1-10. The acrylic copolymer can be polymerized by a living radical polymerization method, and the molecular weight distribution can be adjusted as necessary. From the viewpoint of adjusting the resin viscosity suitable for molding processing, the molecular weight distribution (Mw / Mn) is preferably 1.1 to 7.0, more preferably 1.2 to 5.0, still more preferably 1.5 to 4.0.

  The content of halogen atoms in the acrylic copolymer is 0 or more and less than 0.47% by mass based on the mass of the entire acrylic copolymer. If the acrylic copolymer contains a large amount of halogen atoms, when the acrylic copolymer is handled at a high temperature for melt molding, etc., halogen gas is generated, corroding the equipment and affecting the working environment. There is a possibility of giving. Further, when the molded article of the acrylic copolymer is discarded, if the waste contains a large amount of halogen atoms, a halogen-based gas having a relatively large environmental load may be generated as a decomposition product.

  The glass transition temperature (Tg) of the acrylic copolymer can be arbitrarily controlled by the resin composition, but is preferably controlled to 120 ° C. or more from the viewpoint of industrial applicability. More preferably, it is controlled to 130 ° C. or higher, more preferably 135 ° C. or higher.

  The method for producing the acrylic copolymer can be produced by applying a known polymerization method such as suspension polymerization, solution polymerization or bulk polymerization, and is not particularly limited. For example, methods described in JP-B-63-1964, JP-A-60-147417, JP-B-3879364, JP-B-61-49325 and the like can be used.

  The acrylic copolymer is within the range not impairing the object of the present invention, for example, polyolefin resin such as polyethylene and polypropylene, polystyrene, styrene / acrylonitrile copolymer, styrene / maleic anhydride copolymer, styrene / methacrylic. Styrene resins such as acid copolymers, polymethacrylate resins, polyamides, polyphenylene sulfide resins, polyether ether ketone resins, polyester resins, polysulfones, polyphenylene oxides, polyimides, polyether imides, polyacetals, cyclic olefins At least one or more of thermoplastic resins such as resins and norbornene resins, and thermosetting resins such as phenol resins, melamine resins, silicone resins, and epoxy resins can be mixed.

When the acrylic copolymer is characterized, the absolute value of the photoelastic coefficient (C) of the molded body is 3.0 × 10 ⁻¹² Pa when the film or sheet-shaped molded body obtained by molding the acrylic copolymer is characterized. ⁻¹ or less, more preferably 2.0 × 10 ⁻¹² Pa ⁻¹ or less, and further preferably 1.0 × 10 ⁻¹² Pa ⁻¹ or less.

The photoelastic coefficient is described in various documents (see, for example, Chemical Review, No. 39, 1998 (published by Academic Publishing Center)), and is defined by the following equation. As the value of photoelastic coefficient C _R is close to zero, it can be seen that change in birefringence due to an external force is small.
C _R = | Δn | / σ _R
| Δn | = nx−ny
( _Wherein , C _R : photoelastic coefficient, σ _R : stretching stress, | Δn |: absolute value of birefringence, nx: refractive index in the stretching direction, ny: refractive index perpendicular to the stretching direction)

  The photoelastic coefficient (C) of an acrylic copolymer or an acrylic copolymer is sufficiently smaller than that of existing resins (for example, PMMA, PC, triacetyl cellulose resin, cyclic olefin resin, etc.). Accordingly, birefringence due to external force (photoelasticity) does not occur, so that it is difficult to undergo birefringence change. In addition, birefringence distribution in the molded body is small because birefringence (photoelasticity) due to residual stress at the time of molding hardly occurs.

Furthermore, when the film obtained by molding the acrylic copolymer of this embodiment is characterized, the birefringence (Δn (S)) and the draw ratio (S) that are expressed when the film is uniaxially stretched. In the least squares approximate linear relational expression (the following expression (A)), the value of the slope K preferably satisfies the following expression (B).
Δn (S) = K × S + C (C is a constant: birefringence value when unstretched) (A)
| K | ≦ 0.30 × 10 ⁻⁵ (B)
(Here, birefringence is a value obtained by converting a value measured for an acrylic copolymer film into a thickness of 100 μm.)

The absolute value of the slope K is more preferably | K | ≦ 0.15 × 10 ⁻⁵ , and further preferably | K | ≦ 0.10 × 10 ⁻⁵ . A smaller absolute value of the slope K is preferable because birefringence due to stretching is less likely to occur.

Here, the value of K is a value obtained by measuring the glass transition temperature (Tg) by DSC measurement of the acrylic copolymer and performing uniaxial stretching at a stretching temperature of (Tg + 20) ° C. and a stretching speed of 500 mm / min. Is the value of In general, it is known that the increase in birefringence decreases when the stretching speed is decreased. The value of K is measured, for example, the value of birefringence (Δn (S)) expressed in a uniaxially stretched film obtained by stretching the stretching ratio (S) as 100%, 200%, or 300%, These values can be calculated by plotting against the draw ratio and approximating the least squares method. The draw ratio (S) is a value represented by the following equation, where L _{0 is} the distance between chucks before stretching and L ₁ is the distance between chucks after stretching.

フィルム又はシートは、機械的強度を高めることを目的として延伸加工される場合がある。前述の関係式において、傾きＫの値は、延伸倍率（Ｓ）に対する複屈折（Δｎ（Ｓ））の変化の大きさを表し、Ｋが大きい程延伸に対する複屈折の変化量が大きく、Ｋが小さい程延伸に対する複屈折の変化量が小さいことを意味している。

The film or sheet may be stretched for the purpose of increasing mechanical strength. In the above relational expression, the value of the slope K represents the magnitude of the change in birefringence (Δn (S)) with respect to the draw ratio (S), and the greater the K, the greater the amount of change in birefringence with respect to stretching. The smaller the value, the smaller the amount of change in birefringence with respect to stretching.

  In the acrylic copolymer of the present embodiment, the value of the slope K is sufficiently smaller than that of existing resins (for example, PMMA, PC, triacetyl cellulose resin, cyclic olefin resin, etc.). Therefore, the existing resin has a characteristic that birefringence increases due to the stretch orientation during the stretching process, whereas the birefringence hardly increases even if the stretching process is performed.

  When the acrylic copolymer of this embodiment is characterized as a film or sheet-like molded article, (i) the absolute value of the in-plane direction retardation (Re) is preferably 30 nm or less. (Here, the phase difference is a value obtained by converting a value measured as a film into a thickness of 100 μm.) The absolute value of the phase difference (Re) in the in-plane direction is more preferably 20 nm or less. Preferably, it is 15 nm or less, more preferably 11 nm or less. In general, the absolute value of the phase difference is an index representing the magnitude of birefringence.

  The acrylic copolymer of this embodiment is sufficiently small with respect to the birefringence of existing resins (for example, PMMA, PC, triacetylcellulose resin, cyclic olefin resin, etc.), and has low birefringence or zero birefringence as an optical material. It is suitable for applications that require

  On the other hand, when the absolute value of the retardation in the in-plane direction exceeds 30 nm, it means that the refractive index anisotropy is high, and it cannot be used for applications requiring low birefringence or zero birefringence as an optical material. is there. Moreover, in order to improve the mechanical strength of an optical material (for example, a film, a sheet, etc.), it may be stretched, but when the absolute value of the retardation in the in-plane direction after the stretching process exceeds 30 nm, No low birefringence or zero birefringence material is obtained as an optical material.

  When the acrylic copolymer of the present embodiment is characterized as a film or sheet-like molded article, (ii) the absolute value of the thickness direction retardation (Rth) is preferably 30 nm or less. (Here, the retardation is a value obtained by converting a value measured for an acrylic copolymer film into a thickness of 100 μm.)

The absolute value of the thickness direction retardation (Rth) is more preferably 20 nm or less, further preferably 15 nm or less, and particularly preferably 11 nm or less.
This retardation in the thickness direction is an index that correlates with the viewing angle characteristics of a display device incorporating an optical film when an optical material, particularly an optical film is used. Specifically, the smaller the absolute value of the phase difference in the thickness direction, the better the viewing angle characteristics, and the smaller the change in the color tone of the display color depending on the viewing angle and the lower the contrast.

  The acrylic copolymer of this embodiment has an absolute value of retardation in the thickness direction when used as an optical film, compared to existing resins (for example, PMMA, PC, triacetyl cellulose resin, cyclic olefin resin, etc.). It is very small.

[Phosphophenanthrene compounds]
The phosphaphenanthrene compound of the present embodiment is represented by the following formula (A).

式中、Ｒ^１０は、水素原子、ヒドロキシル基、炭素数１〜４のアルキル基又は炭素数１〜４のアルコキシ基を示し、Ｒ^１１及びＲ^１２はそれぞれ独立に、水素原子、炭素数１〜８のアルキル基、又は炭素数１〜８のアルコキシ基を示す。

In the formula, R ¹⁰ represents a hydrogen atom, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, and R ¹¹ and R ¹² each independently represent a hydrogen atom, 1 to carbon atoms. An alkyl group having 8 or an alkoxy group having 1 to 8 carbon atoms;

  Specific examples of the phosphaphenanthrene compound represented by the formula (A) include compounds represented by the following structural formula.

  In the resin composition of the present embodiment, the addition amount of the phosphaphenanthrene compound is 0.01 to 2.0 parts by mass, preferably 0.05 to 100 parts by mass with respect to 100 parts by mass of the acrylic copolymer. 1.0 part by mass. If this addition amount is less than 0.01 parts by mass, no thermal stabilization effect is observed. If it exceeds 2.0 parts by mass, the anti-coloring effect is good, but the heat distortion temperature tends to decrease.

[Other ingredients]
The resin composition of this embodiment is at least one selected from the group consisting of a hindered phenol compound, a thiodipropionic acid compound, and a phosphite compound that does not belong to the phosphaphenanthrene compound. The compound may be further contained in an amount of 0.01 to 1.0 part by mass, preferably 0.05 to 0.5 part by mass. When the addition amount of these compounds exceeds 1.0 part by mass, the heat distortion temperature is lowered and the effect on thermal coloring and thermal deterioration of the acrylic copolymer is maintained, but coloring by the additive itself. May increase. The amount of the phosphaphenanthrene compound added is preferably larger than the amount of the hindered phenol compound, thiodipropionic acid compound or phosphite compound. Moreover, you may add halogenated phosphoric acid ester 1.0-5.0 mass parts further with respect to 100 mass parts of acrylic copolymers.

  Thus, combining the phosphaphenanthrene compound and at least one of the above hindered phenol compounds, thiodipropionic acid compounds, phosphite compounds, and halogenated phosphate esters. As a result, a thermal stabilization effect equivalent to or higher than that when the phosphaphenanthrene compound is added alone is exhibited. On the other hand, a hindered phenol compound, a thiodipropionic acid compound or a phosphite compound alone does not show a heat stabilizing effect.

  Specific examples of hindered phenol compounds include 2,6-di-tert-butyl-4-methylphenol, 2,4,6-tri-tert-butylphenol, 2,2′-methylenebis- (4-methyl-6). -T-butylphenol), 1,3,5-trimethyl-2,4,6-tris- (3,5-di-t-butyl-4-hydroxybenzyl) benzene, 1,1-bis- (2-hydroxy) -3,5-dimethylphenyl) 3,5,5-trimethylhexane, tetrakis- (methylene-3,5-di-t-butyl-4-hydroxyhydrocinnamate), methane, octadecyl-3- (3,5 -Di-t-butyl-4-hydroxyphenol) propionate, 4,4'-methylenebis- (2-t-butyl-6-methylphenol), 4,4'-thiobis- (3-methyl) -6-t-butylphenol), 4,4'-thiobis - (3-methyl -5-t-butylphenol) and the like.

  Specific examples of the thiodipropionic acid compound include dioctyl thiodipropionate, dilauryl thiodipropionate, distearyl thiodipropionate, and the like.

  Specific examples of phosphite compounds not belonging to phosphaphenanthrene compounds include triphenyl phosphite, tris (nonylphenyl) phosphite, tristearyl phosphite, diphenylnonylphenyl phosphite, diphenylisodecyl phosphite. Fight etc. are mentioned.

  Examples of halogenated phosphates include tris (chloroethyl) phosphate, tris (chloropropyl) phosphate, tris (dichloropropyl) phosphate, tris (dibromopropyl) phosphate, bis (2,3-dibromopropyl) -2,3-dichloro. Examples thereof include phosphoric acid esters containing halogen atoms such as propyl phosphate and bis (chloropropyl) octyl phosphate, and polyphosphoric acid esters containing halogen atoms such as halogenated alkyl polyphosphates (so-called halogen-containing condensed phosphate esters). Among these, polyphosphoric acid esters containing halogen atoms (so-called halogen-containing condensed phosphoric acid esters) are preferred, and as these halogenated phosphoric acid esters, commercially available ones can be used, for example, "TMCPP" made eight Chemical Industry Co., Ltd., "CRP", "CR-504L", "CR-570", such as "DAIGUARD-540", and the like.

  The acrylic copolymer of the present embodiment may contain, in addition to the above compounds, known colorants, stabilizers such as ultraviolet absorbers / antioxidants, and various additives as necessary. For example, inorganic fillers, pigments such as iron oxides, lubricants such as stearic acid, behenic acid, zinc stearate, calcium stearate, magnesium stearate, ethylene bisstearamide, mold release agents, paraffinic process oil, naphthenic process Oils, aromatic process oils, paraffins, organic polysiloxanes, mineralizers and other softeners / plasticizers, hindered phenol antioxidants, phosphorus heat stabilizers and other antioxidants, hindered amine light stabilizers, benzo Examples include triazole-based ultraviolet absorbers, flame retardants, antistatic agents, organic fibers, glass fibers, carbon fibers, reinforcing agents such as metal whiskers, colorants, other additives, or mixtures thereof.

  The method for obtaining the resin composition of the present embodiment is not particularly limited, for example, a method of mixing an acrylic copolymer and an additive with a Henschel mixer, and melt-kneading into an pellet using an extruder, or Mixing can be performed by any method such as a method in which an additive is applied to pellets of an acrylic copolymer using a spreading agent or the like.

  In the resin composition of the present embodiment, the total light transmittance after heat molding is preferably 85% or more, more preferably 88% or more, and further preferably 90% or more. Here, the total light transmittance is a value obtained by converting to a thickness of 100 μm. If the total light transmittance is less than 85%, the transparency of the resin composition may be insufficient for applications requiring high transparency.

  The resin composition of the present embodiment preferably has a haze value after heat molding of 0 to 5%, more preferably 0 to 3%, and further preferably 0 to 2%. preferable.

  Moreover, it is preferable that b value after a thermoforming process is 0-3.0, as for the resin composition of this embodiment, it is more preferable that it is 0-2.5, and it is 0-1.5. Is more preferable.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment.

  Hereinafter, the contents of the present invention will be described more specifically with reference to examples and comparative examples. In addition, this invention is not limited to the following Example.

The measuring method of each measured value used for this invention is as follows.
(A) Analysis of acrylic copolymer (1) Repeating unit Acrylic copolymer obtained by polymerization was dissolved in CDCl ₃ and ¹ H-NMR, ¹³ using a DPX-400 apparatus manufactured by Bruker, Inc. C-NMR (measurement temperature: 40 ° C.) measurement was performed, and (i) the first structural unit, (ii) the second structural unit, (iii) the third structural unit, and (iv) the fourth structure. The amount of each unit was identified, and the composition was confirmed from the ratio.

(2) Glass transition temperature The glass transition temperature (Tg) of the acrylic copolymer obtained by the polymerization was determined by using a differential scanning calorimeter (Diamond DSC manufactured by PerkinElmer Japan Co., Ltd.) in a nitrogen gas atmosphere. -Based on JIS-K-7121, using alumina as a reference, about 10 mg of a sample was calculated from a DSC curve obtained by heating from room temperature to 200 ° C at a heating rate of 10 ° C / min by the midpoint method.

(3) Molecular weight The weight average molecular weight (Mw) and number average molecular weight (Mn) of the acrylic copolymer obtained by polymerization were determined using a gel permeation chromatograph (HLC-8220 manufactured by Tosoh Corporation), and the solvent was It calculated | required by the conversion of commercially available standard PMMA in tetrahydrofuran and preset temperature of 40 degreeC.

(B) Evaluation of optical properties (1) Production of optical film sample (1-a) Molding of press film Using a vacuum compression molding machine (SFV-30, manufactured by Kondo Metal Industry Co., Ltd.), under atmospheric pressure, 260 After preheating at 25 ° C. for 25 minutes, the film was compressed under vacuum (about 10 kPa) at 260 ° C. and about 10 MPa for 5 minutes to form a press film.
(1-b) Molding of stretched film A stretched film was molded by uniaxial free stretching at a stretching temperature (Tg + 20) ° C. and a stretching speed (500 mm / min) using an Instron 5t tensile tester. The draw ratio was drawn at 100%, 200%, and 300%.

(2) Measurement of birefringence Measurement was performed by a rotating analyzer method using RETS-100 manufactured by Otsuka Electronics. The value of birefringence is a value for light having a wavelength of 550 nm. Birefringence (Δn) was calculated by the following formula. The obtained value was converted to a film thickness of 100 μm to obtain a measured value.
Δn = nx−ny
(Δn: birefringence, nx: refractive index in the stretching direction, ny: refractive index in the direction perpendicular to the stretching direction in the plane)
The absolute value (| Δn |) of birefringence (Δn) was determined as follows.
| Δn | = | nx−ny |

(3) Measurement of phase difference (3-a) In-plane phase difference Using RETS-100 manufactured by Otsuka Electronics Co., Ltd., measurement was performed for a wavelength range of 400 to 800 nm by a rotating analyzer method. The obtained value was converted to a film thickness of 100 μm to obtain a measured value.
The absolute value of birefringence (| Δn |) and the phase difference (Re) have the following relationship.
Re = | Δn | × d
(| Δn |: absolute value of birefringence, Re: phase difference, d: thickness of sample)
The absolute value (| Δn |) of birefringence is a value shown below.
| Δn | = | nx−ny |
(Nx: refractive index in the stretching direction, ny: refractive index in the direction perpendicular to the stretching direction in the plane)

(3-b) Thickness direction phase difference Using a phase difference measuring device (KOBRA-21ADH) manufactured by Oji Scientific Instruments Co., Ltd., the phase difference at a wavelength of 589 nm was measured, and the obtained value was adjusted to a film thickness of 100 μm. It was converted into a measured value.
The absolute value of birefringence (| Δn |) and the phase difference (Rth) have the following relationship.
Rth = | Δn | × d
(| Δn |: absolute value of birefringence, Rth: phase difference, d: thickness of sample)
The absolute value (| Δn |) of birefringence is a value shown below.
| Δn | = | (nx + ny) / 2−nz |
(Nx: refractive index in the stretching direction, ny: refractive index in the direction perpendicular to the stretching direction in the plane, nz: refractive index in the thickness direction perpendicular to the stretching direction out of the plane)
(In an ideal film, the in-plane retardation (Re) and the thickness direction retardation (Rth) are both 0 in a film that is completely optically isotropic in all three-dimensional directions.)

(4) Measurement of photoelastic coefficient
A birefringence measuring apparatus described in detail in Polymer Engineering and Science 1999, 39, 2349-2357 was used. Specifically, a film tensioning device (manufactured by Imoto Seisakusho) is placed in the laser beam path, and its birefringence is rotationally detected using RETS-100 manufactured by Otsuka Electronics Co., Ltd. while applying an extensional stress at 23 ° C. It measured about the range of wavelength 400-800 nm by the photon method. The strain rate during stretching was 50% / min (between chucks: 50 mm, chuck moving speed: 5 mm / min), and the test piece width was 6 mm. From the relationship between the absolute value of birefringence (| Δn |) and the tensile stress (σ _R ), the slope of the straight line was obtained by least square approximation, and the photoelastic coefficient (C _R ) was calculated. For the calculation, data with a tensile stress between 2.5 MPa ≦ σ _R ≦ 10 MPa was used.
C _R = | Δn | / σ _R
| Δn | = | nx−ny |
(C _R : photoelastic coefficient, σ _R : stretching stress, | Δn |: absolute value of birefringence, nx: refractive index in the stretching direction, ny: refractive index in the direction perpendicular to the stretching direction in the plane)

(5) Evaluation of durability during heat and humidity resistance The 100% stretched film formed by the method described above in (1-b) is left to stand in a constant temperature and humidity chamber at an atmospheric temperature of 80 ° C. and a humidity of 90% RH for 1000 hours. Changes in optical properties before and after were evaluated using in-plane retardation (Re).

(C) Evaluation of resin composition (1) Thermal coloring scale The b value measured with a Hunter colorimetric color difference meter was used.
(2) Total light transmittance and haze ASTM D1003 compliant

[Acrylic copolymer]
[Production Example 1] Methyl methacrylate / N-phenylmaleimide / N-cyclohexylmaleimide polymer Stirrer, temperature sensor, cooling pipe, nitrogen gas introduction nozzle, raw material solution introduction nozzle, initiator solution introduction nozzle, and polymerization solution discharge nozzle A SUS reactor (capacity 0.5 L) equipped with was used. The pressure in the polymerization reactor was slightly pressurized, and the reaction temperature was controlled at 130 ° C. with an oil bath.

  After mixing 576 g of methyl methacrylate (MMA), 61 g of N-phenylmaleimide (N-PheMI), 83 g of N-cyclohexylmaleimide (N-CyMI) and 480 g of methyl isobutyl ketone, a raw material solution was prepared by replacing with nitrogen gas. . After dissolving 8.63 g of Perhexa C (manufactured by NOF Corp .; concentration 75 wt%) in 91.37 g of methyl isobutyl ketone, nitrogen gas was substituted to prepare an initiator solution.

  The raw material solution was introduced from the raw material solution introduction nozzle at 8.25 ml / min using a pump. The initiator solution was introduced from the initiator solution introduction nozzle at 0.08 ml / min using a pump. After 30 minutes, the polymer solution was discharged from the polymerization solution discharge nozzle at a constant flow rate of 500 ml / hr using a pump.

The polymer solution was collected separately in the initial flow tank for 1.5 hours after discharge. The polymer solution was collected for 2.5 hours after 1.5 hours from the start of discharge. The obtained polymer solution and methanol as an extraction solvent were simultaneously supplied to a homogenizer and subjected to emulsion dispersion extraction. The separated and precipitated polymer was collected and dried under vacuum at 130 ° C. for 2 hours to obtain the desired acrylic copolymer.
Composition: MMA / N-PheMI / N-CyMI = 81/8/11 wt%
Molecular weight: Mw = 22.5 × 10 ⁴ ; Mw / Mn = 2.09
Tg: 135 ° C

[Production Example 2]
An acrylic copolymer was obtained in the same manner as in Production Example 1 except that MMA: 576 g, N-PheMI: 50 g, and N-CyMI: 94 g were used in Production Example 1.
Composition: MMA / N-PheMI / N-CyMI = 79/6/15 wt%
Molecular weight: Mw = 15.4 × 10 ⁴ ; Mw / Mn = 1.75
Tg: 135 ° C

[Production Example 3]
An acrylic copolymer was obtained in the same manner as in Production Example 1 except that MMA: 576 g, N-PheMI: 83 g, and N-CyMI: 61 g were used in Production Example 1.
Composition: MMA / N-PheMI / N-CyMI = 77/10 / 12wt%
Molecular weight: Mw = 14.3 × 10 ⁴ ; Mw / Mn = 1.79
Tg: 137 ° C

[Production Example 4]
An acrylic copolymer was obtained in the same manner as in Production Example 1 except that MMA: 504 g, N-PheMI: 2.4 g, and N-CyMI: 213.6 g were used in Production Example 1.
Composition: MMA / N-PheMI / N-CyMI = 70/1/29 wt%
Molecular weight: Mw = 18.7 × 10 ⁴ ; Mw / Mn = 1.81
Tg: 146 ° C

[Production Example 5] Methyl methacrylate / N-phenylmaleimide / N-cyclohexylmaleimide / styrene polymer A stirrer, temperature sensor, cooling pipe, nitrogen gas introduction nozzle, raw material solution introduction nozzle, and initiator solution introduction nozzle were provided. A glass reactor (capacity 1.0 L) was used. The pressure in the polymerization reactor was slightly pressurized, and the reaction temperature was controlled at 100 ° C. with an oil bath.

  After mixing 140 g of methyl methacrylate (MMA), 14 g of N-phenylmaleimide (N-PheMI), 34 g of N-cyclohexylmaleimide (N-CyMI), 12 g of styrene (St) and 200 g of methyl isobutyl ketone, the gas was replaced with nitrogen gas. A raw material solution was prepared. After dissolving 0.32 g of Perhexa C (manufactured by NOF Corporation; concentration 75 wt%) in 1.00 g of methyl isobutyl ketone, the initiator solution was prepared by replacing with nitrogen gas.

The raw material solution was introduced from the raw material solution introduction nozzle into the glass reactor by pressure feeding. The initiator solution was introduced from the initiator solution introduction nozzle with a syringe to start the polymerization reaction. After 3 hours from the start of the reaction, the reaction was terminated, and the polymer solution was recovered. The obtained polymer solution and methanol as a poor solvent were simultaneously supplied to a homogenizer, and emulsified, dispersed and extracted. The separated and precipitated polymer was collected and dried under vacuum at 130 ° C. for 2 hours to obtain the desired acrylic copolymer.
Composition: MMA / N-PheMI / N-CyMI / St = 70/5/20/5 wt%
Molecular weight: Mw = 15.6 × 10 ⁴ ; Mw / Mn = 2.01
Tg: 141 ° C

[Reference Example 1] Polymethyl methacrylate polymer A polymethyl methacrylate polymer (PMMA) was prepared in the same manner as in Production Example 1 except that only 960 g of methyl methacrylate and 240 g of methyl isobutyl ketone were used. )
Composition: MMA = 100 wt%
Molecular weight: Mw = 10.2 × 10 ⁴ ; Mw / Mn = 1.89
Tg: 121 ° C
Table 1 shows the composition and evaluation results of the acrylic copolymer obtained as described above.

  The acrylic copolymers of Production Examples 1 to 5 have high heat resistance, excellent low birefringence, and high durability against moisture and heat compared to the conventional polymethyl methacrylate resin (Reference Example 1). Is a feature.

[Resin composition]
The resin composition of the acrylic copolymer and the specific organophosphorus compound was prepared, and its thermal stability was evaluated.

[Example 1]
After mixing 100 parts by mass of an acrylic copolymer (Production Example 1) and 0.5 parts by mass of the phosphaphenanthrene compound represented by (A-1) with a Henschel mixer, a φ15 mm twin screw extruder (Technobel Co., Ltd .; KZW15-45MG) was used and melt-kneaded at a cylinder temperature of 230 ° C. to obtain pellets. Subsequently, injection molding was performed using an injection molding machine (manufactured by FUNAC; AUTO SHOT 15A) at a cylinder temperature of 230 ° C. to obtain a plate-like molded body having a width of 10 mm, a length of 50 mm, and a thickness of 1 mm.

[Comparative Example 1]
Except for the phosphaphenanthrene compound (A-1), an acrylic copolymer (Production Example 1) was injection-molded in the same manner as in Example 1, and a plate-like molded product similar to that in Example 1 was obtained. Obtained.

[Example 2]
After mixing 100 parts by mass of an acrylic copolymer (Production Example 2) and 1.0 part by mass of the phosphaphenanthrene compound represented by (A-4) with a Henschel mixer, a φ15 mm twin screw extruder Pellets were obtained by melt mixing at a cylinder temperature of 230 ° C. using (Technobel, KZW15-45MG). Subsequently, injection molding was performed at a cylinder temperature of 230 ° C. using an injection molding machine (manufactured by FUNAC; AUTO SHOT 15A) to obtain a plate-like molded body having the same shape as in Example 1.

[Comparative Example 2]
Except for the phosphaphenanthrene-based compound part (A-4), an acrylic copolymer (Production Example 2) was injection-molded in the same manner as in Example 2, and the same shape as in Example 1 was formed. Got the body.

[Example 3]
After mixing 100 parts by mass of an acrylic copolymer (Production Example 3) and 0.2 part by mass of the phosphaphenanthrene compound represented by (A-8) with a Henschel mixer, a φ15 mm twin screw extruder (Technobel Co., Ltd .; KZW15-45MG) was used and melt-kneaded at a cylinder temperature of 230 ° C. to obtain pellets. Subsequently, injection molding was performed at a cylinder temperature of 230 ° C. using an injection molding machine (manufactured by FUNAC; AUTO SHOT 15A) to obtain a plate-like molded body having the same shape as in Example 1.

[Comparative Example 3]
Acrylic copolymer (Production Example 3) was injection-molded in the same manner as in Example 3 except that the phosphaphenanthrene-based compound part (A-8) was removed. Got the body.

[Example 4]
After mixing 100 parts by mass of an acrylic copolymer (Production Example 4) and 0.2 parts by mass of the phosphaphenanthrene compound represented by (A-8) with a Henschel mixer, a φ15 mm twin screw extruder ( Pellets were obtained by melting and kneading at a cylinder temperature of 230 ° C. using Technobel Co., Ltd. (KZW15-45MG). Subsequently, injection molding was performed at a cylinder temperature of 230 ° C. using an injection molding machine (manufactured by FUNAC; AUTO SHOT 15A) to obtain a plate-like molded body having the same shape as in Example 1.

[Comparative Example 4]
Except for the phosphaphenanthrene compound (A-8), an acrylic copolymer (Production Example 4) was injection-molded in the same manner as in Example 4, and the same shape as in Example 1 was formed. Got the body.

[Example 5]
After mixing 100 parts by mass of an acrylic copolymer (Production Example 5) and 1.0 part by mass of the phosphaphenanthrene compound represented by (A-4) with a Henschel mixer, (manufactured by Technobel; KZW15 -45MG) to obtain a pellet by melt mixing at a cylinder temperature of 230 ° C. Subsequently, it injection-molded at the cylinder temperature of 230 degreeC using the injection molding machine (FUNAC company_made; AUTO SHOT 15A), and obtained the plate-shaped molded object.

[Comparative Example 5]
Except for the phosphaphenanthrene compound part (A-4), an acrylic copolymer (Production Example 5) was injection-molded in the same manner as in Example 5, and a plate-shaped molding having the same shape as in Example 1 Got the body.

  Table 2 shows the thermal stability evaluation results of Examples 1 to 5 and Comparative Examples 1 to 5.

[Examples 6 to 10]
For 100 parts by mass of the same acrylic copolymer as in Production Example 1, the type and amount of phosphaphenanthrene compound, hindered phenol compound, thiodipropionic acid compound, and phosphite ester As shown in Table 3, the type and addition amount of the system compound were variously changed and mixed with a Henschel mixer, then pelletized and injection-molded by the same method as in Example 1, and a molded piece (width 10 mm, long A plate-like molded body having a thickness of 50 mm and a thickness of 1 mm was obtained. These thermal stability evaluation results are shown in Table 3.

[Comparative Examples 6 to 19]
Used as a heat stabilizer for hindered phenolic compounds, thiodipropionic acid-based compounds, phosphite-based compounds, and other thermoplastic resins with respect to 100 parts by mass of the same acrylic copolymer as in Production Example 1. As shown in Table 4, various additives were added and pelletized and injection molded by the same method as in Example 1, and a molded piece (width 10 mm, length 50 mm, thickness 1 mm plate) A shaped molded body) was obtained. These thermal stability evaluation results are shown in Table 4.

In the evaluations in Tables 2 to 4, when the appearance of the molded product is good (no silver streaks (silver stripes) and no streaks), the appearance is bad (silver streaks appear, or The streak is indicated by x. It can be seen that the resin composition of the acrylic copolymer of the present invention and the specific organophosphorus compound is excellent in thermal stability. In addition, the additive used by Table 3-Table 4 is each represented by the following abbreviations.
(B-1) 2,6-di-t-butyl-4-methylphenol (B-2) 2,2′-methylenebis- (4-methyl-6-t-butylphenol)
(B-3) Tetrakis- [methylene- (3,5-di-tert-butyl-4-hydroxyhydrocinnamate)] methane (B-4) 4,4′-thiobis- (2-tert-butyl-6) -Methylphenol)
(C-1) Dilaryl thiodipropionate (C-2) Distearyl thiodipropionate (D-1) Triphenyl phosphite (D-2) Diphenylisodecyl phosphite (E-1) Di-t- Dodecyl disulfide (E-2) dioctyltin dilaurate (E-3) calcium stearate

  A resin composition of an acrylic copolymer that does not change in color during heat molding is suitable as an optical material for optical films, plastic substrates, lenses, optical fibers, optical waveguides, and the like. It is also suitable for injection molded articles such as vehicle lamp lenses, meter panels, visors, and illumination covers.

Claims (5)

Acrylic copolymer having a first structural unit represented by the following formula (1), a second structural unit represented by the following formula (2), and a third structural unit represented by the following formula (3) A phosphaphenanthrene compound represented by the following formula (A):
The content of the phosphaphenanthrene compound is 0.01 to 2 parts by mass with respect to 100 parts by mass of the acrylic copolymer,
The acrylic copolymer is, based on the total amount, 50 to 95% by mass of the first structural unit, 0.1 to 20% by mass of the second structural unit, and 0.1 to 49.9. A resin composition comprising the third structural unit in mass%.

[Wherein, R ¹ represents a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 5 to 12 carbon atoms, an arylalkyl group having 7 to 14 carbon atoms, an aryl group having 6 to 14 carbon atoms, or And an aryl group having 6 to 14 carbon atoms and having at least one substituent selected from the following group A.
Group A: a halogen atom, a hydroxyl group, a nitro group, an alkoxy group having 1 to 12 carbon atoms, and an alkyl group having 1 to 12 carbon atoms. ]

[Wherein, R ² represents an arylalkyl group having 7 to 14 carbon atoms, an aryl group having 6 to 14 carbon atoms, or an aryl group having 6 to 14 carbon atoms having at least one substituent selected from the following group B: R ³ and R ⁴ each independently represent a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, or an aryl group having 6 to 14 carbon atoms.
Group B: a halogen atom, a hydroxyl group, a nitro group, an alkoxy group having 1 to 12 carbon atoms, an alkyl group having 1 to 12 carbon atoms, and an arylalkyl group having 7 to 14 carbon atoms. ]

[Wherein, R ⁵ represents a hydrogen atom, a cycloalkyl group having 3 to 12 carbon atoms, an alkyl group having 1 to 12 carbon atoms, or at least one substituent having at least one substituent selected from the following group C. R ⁶ and R ⁷ each independently represents a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, or an aryl group having 6 to 14 carbon atoms.
Group C: a halogen atom, a hydroxyl group, a nitro group, and an alkoxy group having 1 to 12 carbon atoms. ]

[Wherein, R ¹⁰ represents a hydrogen atom, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, and R ¹¹ and R ¹² each independently represent a hydrogen atom, 1 carbon atom. -8 alkyl group or a C1-C8 alkoxy group is shown. ]   0.01 to 1 mass of at least one compound selected from the group consisting of a hindered phenol compound, a thiodipropionic acid compound, and a phosphite compound that does not belong to the phosphaphenanthrene compound The resin composition according to claim 1, further comprising a part.   The resin composition of Claim 1 or 2 whose halogen atom content rate of the said acrylic copolymer is less than 0.47 mass% on the basis of the total amount of the said acrylic copolymer.   4. The resin composition according to claim 1, wherein a molar ratio of the content of the second structural unit to the content of the third structural unit is greater than 0 and 15 or less.   The weight average molecular weight of the polymethylmethacrylate conversion by the GPC measuring method of the said acrylic copolymer is 3000-1 million, and molecular weight distribution is any one of Claims 1-4 which are 1.5-4.0. The resin composition according to item.