JP2018009141A - Methacrylic resin, manufacturing method thereof, molded body, optical component or automobile component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a methacrylic resin having high heat resistance, highly controlled birefringence, and excellent color tone and transparency. SOLUTION: The methacrylic resin contains 5 to 40% by mass of a structural unit (B) derived from an N-substituted maleimide monomer in a main chain, and the structural unit (B) derived from an N-substituted maleimide monomer is contained. , The content of the component having a glass transition temperature of more than 120 ° C. and 160 ° C. or less and having an absorbance at a wavelength of 400 nm in the methanol-soluble component is a single amount of N-phenylmaleimide, including the structural unit represented by the formula (1). A methacrylic resin having a body equivalent of 2% by mass or less, and a method for producing the same, a molded body, an optical part, or an automobile part. [Selection diagram] None

Description

  The present invention relates to a methacrylic resin having high heat resistance, highly controlled birefringence, excellent color tone and transparency, and a method for producing the same, a molded product, an optical component, and an automotive component.

  In recent years, methacrylic resins have excellent transparency, surface hardness, etc., and low birefringence, which is an optical property, and therefore, for example, various optical products such as liquid crystal displays, plasma displays, and organic EL displays. Flat panel displays, small infrared sensors, fine optical waveguides, ultra-small lenses, DVD / BlueRayDisk pickup lenses that handle short-wavelength light, optical disks, optical films, light guide plates, diffuser plates, lenses, plastic substrates, etc. It is attracting attention as an optical resin for optical materials, and its market is greatly expanding.

  In particular, methacrylic resins having a ring structure in the main chain and compositions containing the methacrylic resins are known to have excellent performance in both heat resistance and optical properties (for example, patents). Ref. 1), the demand is growing rapidly year by year. However, methacrylic resins having a ring structure in the main chain with improved heat resistance and optical properties as described above are sometimes colored due to absorption in the visible light region due to the ring structure, etc. Such a problem has arisen. Therefore, a method for reducing unreacted cyclic monomers remaining in the methacrylic resin has been disclosed in order to obtain a methacrylic resin having a ring structure in the main chain with little coloring and high transparency.

  For example, in Patent Document 2, a monomer component containing an N-substituted maleimide (a) and a methacrylic acid ester (b) is used, a part of the monomer component is supplied to initiate polymerization, and then polymerization is performed. In the production method of supplying the remainder of the monomer component in the middle, the ratio of N-substituted maleimide (a) in the unreacted monomer component present in the reaction system at the end of the supply of the monomer component is simply The amount of residual N-substituted maleimide monomer is reduced by controlling it to be less than the proportion of N-substituted maleimide (a) in the total supply amount of the monomer component, and it is excellent in transparency and heat resistant with little coloring. A method for obtaining a functional methacrylic resin has been proposed.

  Patent Document 3 discloses the content of unreacted N-substituted maleimide in a copolymer obtained by performing polymerization in the presence of a specific polymerization initiator without using another polymerization initiator. There is proposed a method for obtaining an N-substituted maleimide-containing methacrylic resin that is less in heat resistance, excellent in heat resistance, and less colored.

  Further, in Patent Document 4, in a methacrylate monomer / maleimide monomer polymerization system using a sulfur chain transfer agent such as mercaptan, an acidic substance is allowed to exist in the reaction system, thereby remaining maleimide. There has been proposed a method for reducing coloration by reducing the monomer and the maleimide monomer generated by heating during molding.

As another method for obtaining a methacrylic resin having a ring structure in the main chain with little coloring, a method for suppressing impurities present in the raw material and impurities generated during polymerization is disclosed.
For example, Patent Document 5 discloses that a monomer component containing an N-substituted maleimide is polymerized in the presence of a non-radically polymerizable acid anhydride and / or a non-radically polymerizable carboxylic acid to thereby form an N-substituted maleimide. There has been proposed a method of reacting with an amine component, which is an impurity of the above, to convert it into an amide, thereby making it difficult to cause oxidative coloring.
Further, in Patent Document 6, in the method for producing a heat-resistant acrylic resin copolymerized with a maleimide monomer, by adding a specific alcohol during polymerization, coloring impurities generated during the copolymerization are suppressed. A method has been proposed.

International Publication No. 2011/149088 Japanese Patent Laid-Open No. 9-324016 Japanese Patent Laid-Open No. 9-12640 JP 2001-233919 A Japanese Patent Laid-Open No. 10-45852 JP-A-5-310853

  However, in recent years, the use has expanded from optical film applications to thick molded object applications such as lenses and molded plates. For example, even for molded object applications having a long optical path length, and less coloring, and It has been eagerly desired to provide a resin that can exhibit high transparency.

  In Patent Documents 2, 3 and 4, as a method for reducing coloring, attention is paid to N-substituted maleimide having strong coloring property as a monomer itself, and the amount of N-substituted maleimide remaining in methacrylic resin is reduced or molded. A method has been proposed in which attention is paid to the amount of N-substituted maleimide due to thermal history such as processing, and a solution is achieved by reducing it.

  However, as described above, it has been found that, for example, as a methacrylic resin for coping with expansion to a molded product having a long optical path length, the coloring degree and transparency are insufficient.

Patent Documents 5 and 6 propose a method of suppressing the generation of coloring impurities by adding a specific compound during copolymerization. However, the transmittance of light may be lowered in a molded article having a long optical path length due to the influence of a compound to be added or a substance produced by reaction with the compound.
Therefore, it is strongly desired to further improve the colorability and transparency of the methacrylic resin.

  An object of the present invention is to provide a methacrylic resin having high heat resistance, highly controlled birefringence, and excellent color tone and transparency.

  As a result of intensive studies to solve the above-mentioned problems of the prior art, the present inventors, for example, in order to develop high transparency with less coloring even in a molded product having a long optical path length. The inventors have found that the above-mentioned problems can be solved by suppressing specific components in the colored oligomer contained in the methanol-soluble component in the methacrylic resin, and have come to the present invention.

（式（１）中、Ｒ¹は、炭素数７〜１４のアリールアルキル基、炭素数６〜１４のアリール基のいずれかを示し、Ｒ²及びＲ³は、それぞれ独立に、水素原子、炭素数１〜１２のアルキル基、炭素数６〜１４のアリール基のいずれかを示す。また、Ｒ²がアリール基の場合には、Ｒ²は、置換基としてハロゲンを含んでいてもよい。）
ガラス転移温度が１２０℃超１６０℃以下であり、
メタノール可溶分中における波長４００ｎｍに吸光を持つ成分の含有量がＮ−フェニルマレイミド換算で２質量％以下である、
ことを特徴とする、メタクリル系樹脂。
［２］
メタノール可溶分中における分子量２０００以下の成分の含有量が４０質量％以下である、［１］に記載のメタクリル系樹脂。
［３］
前記メタクリル系樹脂が、前記メタクリル系樹脂を１００質量％として、主鎖に、メタクリル酸エステル単量体単位（Ａ）：５０〜９５質量％と、メタクリル酸エステル単量体に共重合可能なその他のビニル系単量体単位（Ｃ）：０〜２０質量％と、を含有する、［１］又は［２］に記載のメタクリル系樹脂。
［４］
前記（Ｂ）構造単位の含有量が、前記（Ｂ）構造単位と前記（Ｃ）単量体単位との合計量を１００質量％として、４５〜１００質量％である、［３］に記載のメタクリル系樹脂。
［５］
前記（Ｃ）単量体単位が、アクリル酸エステル単量体、芳香族ビニル系単量体、シアン化ビニル系単量体からなる群より選ばれる少なくとも一種の構造単位を含む、［３］又は［４］に記載のメタクリル系樹脂。
［６］
光弾性係数が−２×１０^-12〜＋２×１０^-12Ｐａ^-1である［１］〜［５］のいずれかに記載のメタクリル系樹脂。
［７］
メタクリル酸エステル単量体とＮ−置換マレイミド単量体とを含む２種以上の単量体成分を、溶媒中でラジカル重合する方法において、
前記Ｎ−置換マレイミド単量体が、アリール基又はアリールアルキル基でＮ−置換されたＮ−置換マレイミド単量体を含み、
前記Ｎ−置換マレイミド単量体の最終転化率が９７％以上であり、
前記メタクリル酸エステル単量体の最終転化率が８８〜９６％である
ことを特徴とする、メタクリル系樹脂の製造方法。
［８］
前記メタクリル酸エステル単量体の一部と前記Ｎ−置換マレイミド単量体とを共重合させ、前記メタクリル酸エステル単量体の転化率が８０〜９５％となった段階で、メタクリル酸エステル単量体の残部を添加する、［７］に記載のメタクリル系樹脂の製造方法。
［９］
［１］〜［６］のいずれかに記載のメタクリル系樹脂又は該メタクリル系樹脂を含むメタクリル系樹脂組成物からなることを特徴とする、成形体。
［１０］
［７］又は［８］に記載の製造方法によって得られるメタクリル系樹脂又は該メタクリル系樹脂を含むメタクリル系樹脂組成物からなることを特徴とする、成形体。
［１１］
［９］又は［１０］に記載の成形体からなることを特徴とする、光学部品又は自動車部品。 That is, the present invention is as follows.
[1]
A methacrylic resin containing 5 to 40% by mass of a structural unit (B) derived from an N-substituted maleimide monomer in the main chain,
The structural unit (B) derived from the N-substituted maleimide monomer includes a structural unit represented by the following formula (1):

(In the formula (1), R ¹ represents either an arylalkyl group having 7 to 14 carbon atoms or an aryl group having 6 to 14 carbon atoms, and R ² and R ³ are each independently a hydrogen atom, carbon Any one of an alkyl group having 1 to 12 carbon atoms and an aryl group having 6 to 14 carbon atoms, and when R ² is an aryl group, R ² may contain a halogen as a substituent.
The glass transition temperature is over 120 ° C. and below 160 ° C.,
The content of the component having an absorption at a wavelength of 400 nm in the methanol-soluble component is 2% by mass or less in terms of N-phenylmaleimide.
A methacrylic resin characterized by that.
[2]
The methacrylic resin according to [1], wherein the content of the component having a molecular weight of 2000 or less in the methanol-soluble component is 40% by mass or less.
[3]
The methacrylic resin is based on 100% by mass of the methacrylic resin, the main chain has a methacrylic acid ester monomer unit (A): 50 to 95% by mass, and other copolymerizable with the methacrylic acid ester monomer. The methacrylic resin according to [1] or [2], comprising: vinyl monomer unit (C): 0 to 20% by mass.
[4]
The content of the (B) structural unit is 45 to 100% by mass, where the total amount of the (B) structural unit and the (C) monomer unit is 100% by mass, according to [3]. Methacrylic resin.
[5]
The (C) monomer unit includes at least one structural unit selected from the group consisting of an acrylate monomer, an aromatic vinyl monomer, and a vinyl cyanide monomer, [3] or The methacrylic resin according to [4].
[6]
The methacrylic resin according to any one of [1] to [5], which has a photoelastic coefficient of −2 × 10 ⁻¹² to + 2 × 10 ⁻¹² Pa ⁻¹ .
[7]
In a method of radical polymerization of two or more monomer components including a methacrylic acid ester monomer and an N-substituted maleimide monomer in a solvent,
The N-substituted maleimide monomer includes an N-substituted maleimide monomer N-substituted with an aryl group or an arylalkyl group;
The N-substituted maleimide monomer has a final conversion rate of 97% or more;
A method for producing a methacrylic resin, wherein a final conversion rate of the methacrylic acid ester monomer is 88 to 96%.
[8]
When a part of the methacrylic acid ester monomer is copolymerized with the N-substituted maleimide monomer and the conversion of the methacrylic acid ester monomer becomes 80 to 95%, The method for producing a methacrylic resin according to [7], wherein the remainder of the monomer is added.
[9]
A molded product comprising the methacrylic resin according to any one of [1] to [6] or a methacrylic resin composition containing the methacrylic resin.
[10]
A molded product comprising a methacrylic resin obtained by the production method according to [7] or [8] or a methacrylic resin composition containing the methacrylic resin.
[11]
[9] An optical part or an automobile part comprising the molded article according to [10].

  According to the present invention, a methacrylic resin having high heat resistance, highly controlled birefringence, and excellent color tone and transparency can be provided.

  Hereinafter, although the form for implementing this invention (henceforth "this embodiment") is demonstrated in detail, this invention is not limited to the following description, In the range of the summary Various modifications can be made.

(Methacrylic resin)
The methacrylic resin in the present embodiment includes a methacrylic acid ester monomer unit (A) and a structural unit (B) derived from an N-substituted maleimide monomer, and optionally, together with a methacrylic acid ester monomer. It also contains other vinyl monomer units (C) that can be polymerized.

  Hereinafter, each monomer structural unit will be described.

-Structural unit derived from methacrylic acid ester monomer (A)-
First, the structural unit (A) derived from a methacrylic acid ester monomer will be described.
The structural unit (A) derived from a methacrylic acid ester monomer is formed from, for example, a monomer selected from methacrylic acid esters shown below.
Examples of the methacrylate ester include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, and methacrylic acid. Cyclopentyl, cyclohexyl methacrylate, cyclooctyl methacrylate, tricyclodecyl methacrylate, dicyclooctyl 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 monomers may be used alone or in combination of two or more.
Of the above methacrylic acid esters, methyl methacrylate and benzyl methacrylate are preferred in that the obtained methacrylic resin is excellent in transparency and weather resistance.
The structural unit (A) derived from the methacrylic acid ester monomer may contain only one kind or two or more kinds.

  As a content of the structural unit (A) derived from the methacrylic acid ester monomer, a viewpoint of sufficiently imparting heat resistance to the methacrylic resin by the structural unit (B) derived from the N-substituted maleimide monomer described later. Therefore, the methacrylic resin is 100% by mass, preferably 50 to 95% by mass, more preferably 60 to 93% by mass, and still more preferably 70 to 90% by mass.

  Hereinafter, the structural unit (B) derived from the N-substituted maleimide monomer will be described.

-Structural unit derived from N-substituted maleimide monomer (B)-
Next, the structural unit (B) derived from the N-substituted maleimide monomer will be described.
The N-substituted maleimide monomer that forms the structural unit (B) derived from the N-substituted maleimide monomer preferably contains a monomer that forms the structural unit represented by the following formula (1) as an essential component. Is formed from both monomers forming the structural unit represented by the following formula (1) and the following formula (2).

式（１）中、Ｒ¹は、炭素数７〜１４のアリールアルキル基、炭素数６〜１４のアリール基のいずれかを示し、Ｒ²及びＲ³は、それぞれ独立に、水素原子、炭素数１〜１２のアルキル基、炭素数６〜１４のアリール基のいずれかを示す。
また、Ｒ²がアリール基の場合には、Ｒ²は、置換基としてハロゲンを含んでいてもよい。
また、Ｒ¹は、ハロゲン原子、炭素数１〜６のアルキル基、炭素数１〜６のアルコキシ基、ニトロ基、ベンジル基等の置換基で置換されていてもよい。

In Formula (1), R ¹ represents any of an arylalkyl group having 7 to 14 carbon atoms and an aryl group having 6 to 14 carbon atoms, and R ² and R ³ each independently represent a hydrogen atom or a carbon number. One of an alkyl group having 1 to 12 and an aryl group having 6 to 14 carbon atoms is shown.
When R ² is an aryl group, R ² may contain halogen as a substituent.
R ¹ may be substituted with a substituent such as a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a nitro group, or a benzyl group.

式（２）中、Ｒ⁴は、水素原子、炭素数３〜１２のシクロアルキル基、炭素数１〜１８のアルキル基のいずれかを示し、Ｒ⁵及びＲ⁶は、それぞれ独立に、水素原子、炭素数１〜１２のアルキル基、炭素数６〜１４のアリール基のいずれかを示す。

In formula (2), R ⁴ represents any one of a hydrogen atom, a cycloalkyl group having 3 to 12 carbon atoms, and an alkyl group having 1 to 18 carbon atoms, and R ⁵ and R ⁶ are each independently a hydrogen atom. , An alkyl group having 1 to 12 carbon atoms, or an aryl group having 6 to 14 carbon atoms.

Specific examples will be shown below.
Examples of the monomer that forms the structural unit represented by the formula (1) include 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- Roll-2,5-dione, 1,3-diphenyl -1H- pyrrole-2,5-dione, 1,3,4-triphenyl -1H- pyrrole-2,5-dione, and the like.
Among these monomers, N-phenylmaleimide and N-benzylmaleimide are preferable because the obtained methacrylic resin has excellent heat resistance and optical properties such as birefringence.
These monomers may be used alone or in combination of two or more.

Examples of the monomer that forms the structural unit represented by the formula (2) include N-methylmaleimide, N-ethylmaleimide, Nn-propylmaleimide, N-isopropylmaleimide, Nn-butylmaleimide, N-isobutylmaleimide, Ns-butylmaleimide, Nt-butylmaleimide, Nn-pentylmaleimide, Nn-hexylmaleimide, Nn-heptylmaleimide, Nn-octylmaleimide, N-lauryl Maleimide, N-stearylmaleimide, N-cyclopentylmaleimide, N-cyclohexylmaleimide, 1-cyclohexyl-3-methyl-1H-pyrrole-2,5-dione, 1-cyclohexyl-3,4-dimethyl-1H-pyrrole-2 , 5-dione, 1-cyclohexyl-3-phenyl-1H-pillow 2,5-dione, and 1-cyclohexyl-3,4-diphenyl -1H- pyrrole-2,5-dione can be cited.
Among these monomers, N-methylmaleimide, N-ethylmaleimide, N-isopropylmaleimide, and N-cyclohexylmaleimide are preferable because the weather resistance of the methacrylic resin is excellent. N-cyclohexylmaleimide is particularly preferable because of its excellent hygroscopicity.
These monomers can be used alone or in combination of two or more.

  In the methacrylic resin of this embodiment, a monomer that forms the structural unit represented by the formula (1) is used. Furthermore, it is preferable to use a monomer that forms the structural unit represented by the formula (2) in combination in order to develop highly controlled birefringence characteristics.

The molar ratio (B1 / B2) of the content (B1) of the structural unit represented by formula (1) to the content (B2) of the structural unit represented by formula (2) is preferably more than 0 and 15 or less. More preferably, it is more than 0 and 10 or less.
When the molar ratio B1 / B2 is in this range, the methacrylic resin of the present embodiment maintains transparency, does not cause yellowing, and does not impair the environmental resistance, and has good heat resistance and good photoelasticity. Express characteristics.

The content of the structural unit (B) derived from the N-substituted maleimide monomer is not particularly limited as long as the obtained composition satisfies the glass transition temperature range of the present embodiment. As mass%, it is the range of 5-40 mass%, Preferably it is the range of 5-30 mass%, More preferably, it is the range of 7-25 mass%.
When it is within this range, the methacrylic resin can obtain a more sufficient heat resistance improving effect, and more preferable effects of improving weather resistance, low water absorption, and optical properties. It should be noted that the content of the structural unit derived from the N-substituted maleimide monomer being 40% by mass or less reduces the reactivity of the monomer component during the polymerization reaction and increases the amount of monomer remaining unreacted. This is effective in preventing deterioration in physical properties of the methacrylic resin.

  Moreover, as content of the structural unit (B1) represented by Formula (1), methacrylic resin is 100 mass% from the point which is excellent in optical characteristics, such as heat resistance of a methacrylic resin obtained, and birefringence. Is preferably in the range of 3 to 30% by mass, more preferably in the range of 5 to 25% by mass, and still more preferably in the range of 7 to 20% by mass.

-Other vinyl monomer units (C) copolymerizable with methacrylate monomers-
Other vinyl monomer units (C) (hereinafter referred to as (C) monomer units) copolymerizable with methacrylic acid ester monomers that can constitute the methacrylic resin of this embodiment. .) Are aromatic vinyl monomer units (C-1), acrylate monomer units (C-2), vinyl cyanide monomer units (C-3), and other single units. A monomer unit (C-4) is mentioned.
As for other vinyl monomer units (C) copolymerizable with the methacrylic acid ester monomer, only one kind may be used alone, or two or more kinds may be combined.

  The monomer unit (C) can be appropriately selected depending on the properties required for the methacrylic resin of the present embodiment, but the thermal stability, fluidity, mechanical properties, chemical resistance, etc. When the characteristics are particularly necessary, it consists of an aromatic vinyl monomer unit (C-1), an acrylate monomer unit (C-2), and a vinyl cyanide monomer unit (C-3). At least one selected from the group is preferred.

[Aromatic vinyl-based monomer unit (C-1)]
Although it does not specifically limit as a monomer which makes the aromatic vinyl-type monomer unit (C-1) which comprises the methacrylic resin of this embodiment, It represents with following General formula (4). Aromatic vinyl monomers are preferred.

前記一般式（４）中、Ｒ¹は、水素原子、又は炭素数が１〜６のアルキル基を表し、当該アルキル基は、例えば、水酸基で置換されていてもよい。
Ｒ²は、水素原子、炭素数が１〜１２のアルキル基、炭素数が１〜１２のアルコキシ基、炭素数が６〜８のアリール基、炭素数が６〜８のアリーロキシ基からなる群より選択されるいずれかであり、Ｒ²は、全て同じ基であっても、異なる基であってもよい。また、Ｒ²同士で環構造を形成してもよい。
ｎは、０〜５の整数を表す。

In the general formula (4), R ¹ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and the alkyl group may be substituted with a hydroxyl group, for example.
R ² is a group consisting of a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aryl group having 6 to 8 carbon atoms, and an aryloxy group having 6 to 8 carbon atoms. Any one selected and R ² may be the same group or different groups. Further, R ² may form a ring structure.
n represents an integer of 0 to 5.

Specific examples of the monomer represented by the general formula (4) are not particularly limited, but styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethyl. Styrene, 2,5-dimethylstyrene, 3,4-dimethylstyrene, 3,5-dimethylstyrene, p-ethylstyrene, m-ethylstyrene, о-ethylstyrene, p-tert-butylstyrene, 1-vinylnaphthalene, 2-vinylnaphthalene, 1,1-diphenylethylene, isopropenyl benzene (α-methylstyrene), isopropenyl toluene, isopropenyl ethyl benzene, isopropenyl propyl benzene, isopropenyl butyl benzene, isopropenyl pentyl benzene, isopropenyl hexyl benzene, Isopropenyl octylben Zen etc. are mentioned.
Among these, styrene and isopropenylbenzene are preferable, and styrene is more preferable from the viewpoint of imparting fluidity and reducing unreacted monomers by improving the polymerization conversion rate.
These may be appropriately selected according to required characteristics in the methacrylic resin of the present embodiment.

  The content in the case of using the aromatic vinyl monomer unit (C-1) is (A) the monomer unit and (B) in consideration of the balance between heat resistance, reduction of residual monomer species, and fluidity. When the total amount with the structural unit is 100% by mass, it is preferably 23% by mass or less, more preferably 20% by mass or less, further preferably 18% by mass or less, still more preferably 15% by mass or less, More preferably, it is 10 mass% or less.

When the aromatic vinyl monomer unit (C-1) is used in combination with the above-described N-substituted maleimide structural unit (B), (C-1) monomer unit relative to the content of (B) structural unit As a content ratio (mass ratio) (ie, (C-1) content / (B) content), the processing fluidity when the film is molded and the silver streak reduction effect by reducing the residual monomer From the viewpoint of the above, it is preferably 0.3 to 5.
Here, from the viewpoint of maintaining good color tone and heat resistance, the upper limit value is preferably 5 or less, more preferably 3 or less, and even more preferably 1 or less. From the viewpoint of reducing the residual monomer, the lower limit is preferably 0.3 or more, more preferably 0.4 or more.
The aromatic vinyl monomer (C-1) described above may be used alone or in combination of two or more.

[Acrylic acid ester monomer unit (C-2)]
Although it does not specifically limit as a monomer which makes the acrylate ester monomer unit (C-2) which comprises the methacrylic resin of this embodiment, The acryl represented by following General formula (5) Acid ester monomers are preferred.

In the general formula (5), R ¹ represents a hydrogen atom or an alkoxy group having 1 to 12 carbon atoms, R ² represents an alkyl group having 1 to 18 carbon atoms and a cyclohexane having 3 to 12 carbon atoms. It represents either an alkyl group or an aryl group having 6 to 14 carbon atoms.

As a monomer for forming the acrylate ester monomer unit (C-2), in the methacrylic resin for a film of the present embodiment, weather resistance, heat resistance, fluidity, and thermal stability are improved. From the viewpoint, methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, sec-butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenyl acrylate, and the like are preferable, and more preferably, They are methyl acrylate, ethyl acrylate, and n-butyl acrylate, and methyl acrylate and ethyl acrylate are more preferable from the viewpoint of availability.
The acrylate monomer unit (C-2) may be used alone or in combination of two or more.

  In the case of using the acrylate monomer unit (C-2), the total content of the (A) monomer unit and the (B) structural unit is 100 from the viewpoints of heat resistance and thermal stability. In the case of mass%, it is preferably 5 mass% or less, more preferably 3 mass% or less.

[Vinyl cyanide monomer unit (C-3)]
The monomer constituting the vinyl cyanide monomer unit (C-3) constituting the methacrylic resin of the present embodiment is not particularly limited, and examples thereof include acrylonitrile, methacrylonitrile, and cyanide. Examples thereof include vinylidene, and among them, acrylonitrile is preferable from the viewpoint of easy availability and chemical resistance.
The vinyl cyanide monomer unit (C-3) may be used alone or in combination of two or more.

  The content when using the vinyl cyanide monomer unit (C-3) is the total amount of the (A) monomer unit and the (B) structural unit from the viewpoint of solvent resistance and heat resistance. Is preferably 15% by mass or less, more preferably 12% by mass or less, and still more preferably 10% by mass or less.

[Monomer units other than (C-1) to (C-3) (C-4)]
Although it does not specifically limit as a monomer which makes monomeric units (C-4) other than (C-1)-(C-3) which comprises the methacrylic resin of this embodiment, For example, Amides such as acrylamide, methacrylamide; ethylene glycol such as ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, or oligomers thereof One obtained by esterifying hydroxyl groups at both ends with acrylic acid or methacrylic acid; One obtained by esterifying the hydroxyl groups of two alcohols such as neopentyl glycol di (meth) acrylate and di (meth) acrylate with acrylic acid or methacrylic acid; Methylolpropane, pentaerythritol, etc. Those that have been esterified with a polyhydric alcohol derivative of acrylic acid or methacrylic acid; polyfunctional monomers such as divinylbenzene.

  Among the monomers constituting the monomer unit (C) described above, at least one selected from the group consisting of methyl acrylate, ethyl acrylate, styrene, and acrylonitrile is preferable from the viewpoint of availability.

The content of the other vinyl monomer unit (C) copolymerizable with the methacrylic acid ester monomer is 100% by mass of the methacrylic resin from the viewpoint of enhancing the effect of imparting heat resistance by the structural unit (B). As, it is preferable that it is 0-20 mass%, It is more preferable that it is 0-18 mass%, It is further more preferable that it is 0-15 mass%.
In particular, when a crosslinkable polyfunctional (meth) acrylate having a plurality of reactive double bonds is used as the monomer unit (C), the content of the monomer unit (C) is the fluidity of the polymer. In view of the above, it is preferably 0.5% by mass or less, more preferably 0.3% by mass or less, and still more preferably 0.2% by mass or less.

  In particular, in this embodiment, from the viewpoint of heat resistance and optical properties of the methacrylic resin, when the total amount of (B) structural unit and (C) monomer unit is 100% by mass, (B) structural unit The content of is preferably 45 to 100% by mass. At this time, the content of the structural unit (C) is preferably 0 to 55% by mass. And content of (B) structural unit becomes like this. More preferably, it is 50-100 mass%, More preferably, it is 50-90 mass%, More preferably, it is 50-80 mass%.

  Hereinafter, the characteristics of the methacrylic resin of this embodiment will be described.

The glass transition temperature (Tg) of the methacrylic resin in this embodiment is more than 120 ° C. and 160 ° C. or less.
If the glass transition temperature of the methacrylic resin exceeds 120 ° C, it will have sufficient heat resistance necessary for recent optical parts such as lens moldings and liquid crystal display light guide plates, automotive parts, and film moldings for liquid crystal displays. It can be obtained more easily. The glass transition temperature (Tg) is more preferably 125 ° C. or higher, and still more preferably 130 ° C. or higher, from the viewpoint of dimensional stability under the use environment temperature.
On the other hand, when the glass transition temperature (Tg) of the methacrylic resin is 160 ° C. or lower, melt processing at an extremely high temperature can be avoided, thermal decomposition of the resin or the like can be suppressed, and a good product can be obtained. The glass transition temperature (Tg) is preferably 150 ° C. or lower for the reasons described above.
In addition, a glass transition temperature (Tg) can be determined by measuring based on JIS-K7121. Specifically, it can measure using the method described in the Example mentioned later.

The content of the component having a light absorption at a wavelength of 400 nm in the methanol-soluble component of the methacrylic resin in the present embodiment is 2% by mass or less, preferably 1.5% by mass or less, more preferably 1% by mass. It is as follows.
By setting the ratio of the component having light absorption at a wavelength of 400 nm to 2% by mass or less, a molded product having good color tone and suitable for optical use can be obtained.
In addition, content of the component which has light absorption in wavelength 400nm calculates | requires as follows in conversion to N-phenylmaleimide. First, using a UV detector whose wavelength is set to 400 nm as a detector, the molecular weight distribution of methanol-soluble matter is measured by gel permeation chromatography (GPC) to determine the total peak area. Separately, GPC measurement with a 400 nm detector is also performed for phenylmaleimide, and a calibration curve of sample concentration and peak area is created. Using this calibration curve, the amount of the component having absorbance at 400 nm in the methanol-soluble component was determined as the amount when converted to N-phenylmaleimide, and the absorbance at a wavelength of 400 nm was determined from the ratio to the mass of the methanol-soluble component. Content (mass% in terms of N-phenylmaleimide) is determined. Specifically, it will be described in detail in Examples described later.
In addition, methanol-soluble and methanol-insoluble components can be reprecipitated by dropping the solution into methanol after the methacrylic resin is made into a chloroform solution, separating the filtrate and the filtrate, and then drying each. Specifically, it can be obtained by the method described in Examples below.

In the methanol-soluble component of the methacrylic resin in this embodiment, the content of the component having a molecular weight of 2000 or less is preferably 40% by mass or less, more preferably 30% by mass or less, and 20% by mass or less. More preferably.
By controlling the amount of the component having a molecular weight of 2000 or less in the methanol-soluble component to 40% by mass or less, a molded product having a good color tone can be obtained, and cast roll dirt at the time of film molding and silver streak at the time of injection molding. Troubles at the time of molding such as generation of scum can be suppressed.
The amount of the component having a molecular weight of 2000 or less is calculated from the ratio of the elution area having a molecular weight of 2000 or less to the total peak area by measuring the methanol-soluble content with GPC using an RI detector. Specifically, it can be obtained by the method described in Examples below.

The ratio of the amount of methanol-soluble matter of the methacrylic resin in the present embodiment to the total amount of 100% by mass of the amount of methanol-soluble component and the amount of methanol-insoluble component is preferably 5% by mass or less, more preferably It is 4 mass% or less, More preferably, it is 3.5 mass% or less, More preferably, it is 3 mass% or less.
By setting the ratio of the amount of the soluble component to 5% by mass or less, it is possible to suppress problems during molding, such as cast roll contamination during film molding and silver streak generation during injection molding.

In the methacrylic resin in this embodiment, the weight average molecular weight (Mw) in terms of polymethyl methacrylate measured by gel permeation chromatography (GPC) is preferably in the range of 65,000 to 300,000, more preferably. It is in the range of 100,000 to 220,000, more preferably in the range of 120,000 to 180,000.
When the weight average molecular weight (Mw) is in the above range, the balance between mechanical strength and fluidity is excellent.
Moreover, regarding the ratio between the weight average molecular weight (Mw) and the number average molecular weight (Mn) as parameters representing the molecular weight distribution, in the methacrylic resin in the present embodiment, considering the balance between fluidity and mechanical strength. Mw / Mn is preferably 1.5 to 3.0, more preferably 1.6 to 2.5, and still more preferably 1.6 to 2.3.
In addition, about the weight average molecular weight of a methacrylic-type resin, and a number average molecular weight, it can measure by the method of the below-mentioned Example description.

The absolute value of the photoelastic coefficient C _R of the methacrylic resin of the present embodiment, it is possible at 3.0 × 10 ^-12 Pa ^-1 or less and preferably, 2.0 × 10 ^-12 Pa ^-1 or less More preferably, it is 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 the Academic Publishing Center)) and is defined by the following formulas (ia) and (ib). It is. 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 (ii)
| Δn | = | nx−ny | (i−b)
(Where C _R is the photoelastic coefficient, σ _R is the extension stress, | Δn | is the absolute value of birefringence, nx is the refractive index in the extension direction, and ny is perpendicular to the extension direction in the plane. Refractive index in direction is shown respectively.)
If the absolute value of the photoelastic coefficient C _R of the methacrylic resin of this embodiment is 3.0 × 10 ⁻¹² Pa ⁻¹ or less, even if it is formed into a film and used in a liquid product display device, retardation unevenness occurs. In addition, it is possible to suppress or prevent the contrast at the periphery of the display screen from decreasing or light leakage from occurring.
Photoelastic coefficient C _R of the methacrylic resin, specifically, can be determined by the method described in Examples described later.

(Method for producing methacrylic resin)
Hereinafter, it describes about the manufacturing method of the methacrylic resin of this embodiment.

Hereinafter, a method for producing a methacrylic resin will be described in detail.
A solution polymerization method is used as a method for producing a methacrylic resin in the present embodiment.
In the manufacturing method in this embodiment, a semi-batch type or a continuous type can be used as the polymerization mode. Here, the semi-batch method is a process in which either the raw material input or the product recovery is performed simultaneously during the progress of the reaction. As a method for producing a methacrylic resin in the present embodiment, a semi-batch method in which a part of raw materials are charged after the reaction starts is preferable.
Further, in the production method in the present embodiment, a plurality of reactors are connected in series, and in the first vessel, a monomer containing a part of a methacrylic acid ester monomer and an N-substituted maleimide monomer, Polymerization was performed continuously by feeding the initiator continuously and feeding the reaction solution at the outlet to the subsequent reactor, and the conversion rate of the methacrylic acid ester monomer reached 80 to 95%. Polymerization can also be performed by a method in which the remainder of the methacrylic acid ester monomer is additionally added to the subsequent reactors.
In the manufacturing method in the present embodiment, polymerization of monomers by radical polymerization is used.

  Hereinafter, the suitable manufacturing method of the methacrylic resin of this embodiment is explained in full detail.

In a preferred method for producing a methacrylic resin according to this embodiment, two or more monomer components including a methacrylic acid ester monomer and an N-substituted maleimide monomer are radically polymerized in a solvent, , N-substituted maleimide monomers include N-substituted maleimide monomers that are N-substituted with an aryl or arylalkyl group.
The final conversion rate of the N-substituted maleimide monomer is 97% or more, and the final conversion rate of the methacrylic acid ester monomer is 88% or more and 96% or less.

The final conversion rate of the N-substituted maleimide monomer is 97% or more, preferably 98% or more, more preferably 99% or more.
The final conversion rate of the methacrylic acid ester monomer is 88 to 96%, preferably 90 to 95%, more preferably 90 to 94%.
By carrying out the polymerization so that the final conversion rate of the methacrylic acid ester and the N-substituted maleimide is within this range, the content of the component having an absorption at a wavelength of 400 nm in the methanol-soluble component is suppressed, and the methacrylic compound having a good color tone is suppressed. A resin-based molded product is obtained. When radical copolymerizing a methacrylic acid ester monomer and an N-substituted maleimide monomer, the conversion rate is usually high because the consumption rate of the methacrylic acid ester monomer is higher than that of the N-substituted maleimide monomer. Easy to go up. As a result of detailed examination of the amount of coloring components in the methanol-soluble component during polymerization, the inventors have found that a large amount of N-substituted maleimide monomer remains when the polymerization conversion rate increases and the monomer concentration decreases. It has been found that the production of coloring oligomers is promoted to adversely affect the color tone of the methacrylic resin. The inventors then increased the concentration of the methacrylic acid ester monomer at the end of the polymerization to suppress the final conversion rate to 96% or less, and at the same time, set the final conversion rate of the N-substituted maleimide monomer to 97% or more. It discovered that the production | generation of a coloring oligomer can be suppressed by raising. Also, if the residual amount of methacrylic acid ester monomer is large, the load of the devolatilization process increases, and the residual volatile matter increases, which adversely affects the color tone of the methacrylic resin and the appearance of the molded product. It has been found that it is important that the monomer conversion is 88% or more.

  The method for controlling the final conversion rate of the methacrylic acid ester monomer and the N-substituted maleimide monomer within the above range is not particularly limited. For example, first, a part of the methacrylic acid ester monomer and Examples include a method of copolymerizing an N-substituted maleimide monomer and adding the remainder of the methacrylic acid ester monomer when the conversion of the methacrylic acid ester monomer reaches 80 to 95%. Here, all or a part of the N-substituted maleimide monomer may be used.

  In this case, when a part of the methacrylic acid ester monomer and the N-substituted maleimide monomer are first copolymerized, a part of the methacrylic acid ester monomer and the N- After the whole amount of the substituted maleimide monomer is charged into the reactor, the polymerization may be performed by adding a radical initiator, or the polymerization may be performed while feeding the monomer into the reactor in a semi-batch manner. . In any case, it is preferable to wait for a while until the conversion of the methacrylic acid ester monomer reaches a desired value after completion of the monomer feed.

  When the conversion rate of the methacrylic acid ester monomer reaches 80 to 95%, the remainder of the methacrylic acid ester monomer is additionally added.

In this stage, the amount of monomer to be added is preferably 5 to 35% by mass, more preferably 10 to 30% by mass, with the total monomer amount being 100% by mass, and more preferably 15 to 25%. More preferably, it is mass%.
In order to reduce the ratio of the N-substituted maleimide monomer in the unreacted monomer and suppress the formation of the coloring oligomer, the ratio of the monomer amount to be added is 5% by mass or more. In order to obtain a molded article having a high transmittance, the ratio is preferably 35% by mass or less.

During addition, a part of the N-substituted maleimide monomer may be added, or other vinyl monomers other than the methacrylic acid ester monomer and N-substituted maleimide (the above-mentioned (C) monomer) Monomers that form body units) can also be added.
From the viewpoint of increasing the conversion rate of the N-substituted maleimide monomer at the end of the polymerization, it is preferable that substantially no N-substituted maleimide monomer is added at this stage. It is preferred to use all of the N-substituted maleimide monomer with a portion of the acid ester monomer.
When adding an N-substituted maleimide monomer at the stage of additional addition, from the viewpoint of increasing the conversion rate of the N-substituted maleimide monomer, the amount of the N-substituted maleimide monomer to be added is the amount of N-substituted used. The total amount of the maleimide monomer is 100% by mass, preferably 10% by mass or less, more preferably 5% by mass or less, and particularly preferably 0% by mass.

  From the viewpoint of obtaining a molded article having a high permeability, it is preferable that the additional addition rate is close to the monomer consumption rate in the polymerization reaction, and it is preferably 30 minutes to 3 hours.

The polymerization solvent to be used is not particularly limited as long as the solubility of the maleimide copolymer obtained by polymerization is increased and the viscosity of the reaction solution can be appropriately maintained for the purpose of preventing gelation.
Specific examples of the polymerization solvent include aromatic hydrocarbons such as toluene, xylene, ethylbenzene, and isopropylbenzene; ketones such as methyl isobutyl ketone, butyl cellosolve, methyl ethyl ketone, and cyclohexanone; polar solvents such as dimethylformamide and 2-methylpyrrolidone. Can be used.
Moreover, you may use together alcohol, such as methanol, ethanol, and isopropanol, as a polymerization solvent in the range which does not inhibit melt | dissolution of the polymerization product at the time of superposition | polymerization.

  The amount of the solvent at the time of polymerization is not particularly limited as long as the polymerization proceeds and precipitation of the copolymer and the used monomer does not occur during production and can be easily removed. When the total amount is 100 parts by mass, it is preferably 10 to 200 parts by mass. More preferably, it is 25-200 mass parts, More preferably, it is 50-200 mass parts, More preferably, it is 50-150 mass parts.

  The polymerization temperature is not particularly limited as long as the polymerization proceeds, but is preferably 70 to 180 ° C, more preferably 80 to 160 ° C. More preferably, it is 90-150 degreeC, More preferably, it is 100-150 degreeC. From the viewpoint of productivity, the temperature is preferably 70 ° C. or higher, and is preferably 180 ° C. or lower in order to suppress side reactions during polymerization and obtain a polymer having a desired molecular weight and quality.

  The polymerization time is not particularly limited as long as the required degree of polymerization can be obtained at the required conversion rate, but from the viewpoint of productivity and the like, it is preferably 2 to 15 hours, More preferably, it is 3-12 hours, More preferably, it is 4-10 hours.

The polymerization conversion rate at the end of the polymerization of the methacrylic resin in the present embodiment is preferably 90 to 98%, more preferably 91 to 97%, and further preferably 92 to 96%.
Here, the polymerization conversion rate is a monomer added in the polymerization system, which is a value obtained by subtracting the total mass of monomers remaining at the end of the polymerization from the total mass of monomers added in the polymerization system. It is a ratio to the total mass of.

  During the polymerization reaction, a chain transfer agent may be added and polymerized as necessary.

As the chain transfer agent, a chain transfer agent used in general radical polymerization can be used, for example, n-butyl mercaptan, n-octyl mercaptan, n-decyl mercaptan, n-dodecyl mercaptan, 2-ethylhexyl thioglycolate and the like. Mercaptan compounds; halogen compounds such as carbon tetrachloride, methylene chloride and bromoform; unsaturated hydrocarbon compounds such as α-methylstyrene dimer, α-terpinene, dipentene and terpinolene;
These may be used alone or in combination of two or more.
These chain transfer agents may be added at any stage as long as the polymerization reaction is in progress, and are not particularly limited.
The addition amount of the chain transfer agent may be 0.01 to 1 part by mass, preferably 0.05 to 0.5 part by mass, when the total amount of monomers used for polymerization is 100 parts by mass.

In solution polymerization, it is important to reduce the dissolved oxygen concentration in the polymerization solution as much as possible. For example, the dissolved oxygen concentration is preferably 10 ppm or less.
The dissolved oxygen concentration can be measured using, for example, a dissolved oxygen meter DO meter B-505 (manufactured by Iijima Electronics Co., Ltd.). As a method for lowering the dissolved oxygen concentration, a method of bubbling an inert gas in the polymerization solution, and an operation of releasing the pressure after pressurizing the container containing the polymerization solution with an inert gas to about 0.2 MPa before the polymerization are repeated. A method such as a method and a method of passing an inert gas in a container containing a polymerization solution can be appropriately selected.

  During the polymerization reaction, a polymerization initiator is added.

As the polymerization initiator, any initiator generally used in radical polymerization can be used. For example, cumene hydroperoxide, diisopropylbenzene hydroperoxide, di-t-butyl peroxide, lauroyl peroxide, benzoyl peroxide Organic peroxides such as oxide, t-butylperoxyisopropyl carbonate, t-amylperoxy-2-ethylhexanoate, t-amylperoxyisononanoate, 1,1-di-t-butylperoxycyclohexane; 2,2'-azobis (isobutyronitrile), 1,1'-azobis (cyclohexanecarbonitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), dimethyl-2,2'-azobis Azo compounds such as isobutyrate; it can.
These may be used alone or in combination of two or more.
These polymerization initiators may be added at any stage as long as the polymerization reaction is in progress.
The addition amount of the polymerization initiator may be 0.01 to 1 part by mass, preferably 0.05 to 0.5 part by mass, when the total amount of monomers used for polymerization is 100 parts by mass.

  The method for recovering the polymer from the polymerization solution obtained by solution polymerization is not particularly limited. For example, a poor solvent such as a hydrocarbon solvent or alcohol solvent that does not dissolve the polymerization product obtained by polymerization. After adding the polymerization liquid in the presence of an excessive amount, the homogenizer is treated (emulsified and dispersed), and the unreacted monomer is subjected to pretreatment such as liquid-liquid extraction and solid-liquid extraction. Examples include a method of separating from a polymerization solution; or a method of separating a polymerization solvent and unreacted monomers via a step called a devolatilization step and recovering a polymerization product.

Here, the devolatilization step refers to a step of removing volatile components such as a polymerization solvent, a residual monomer, and a reaction by-product under heating and reduced pressure conditions.
As an apparatus used for the devolatilization process, for example, a devolatilization apparatus composed of a tubular heat exchanger and a devolatilization tank; thin film evaporators such as Wibren and Exeva manufactured by Shinko Environmental Solution Co., Ltd., Hitachi contra, and inclined blade contra; And a vented extruder having sufficient residence time and surface area to exhibit volatility.
A devolatilization process using a devolatilizer in which any two or more of these apparatuses are combined can also be used.

The treatment temperature in the devolatilizer is preferably 150 to 350 ° C, more preferably 170 to 300 ° C, and further preferably 200 to 280 ° C. Residual volatile matter can be suppressed by setting the temperature to the lower limit temperature or higher, and coloring and decomposition of the acrylic resin obtained by setting the temperature to the upper limit temperature or lower can be suppressed.
The degree of vacuum in the devolatilizer is preferably 10 to 500 Torr, and more preferably 10 to 300 Torr. By setting the degree of vacuum below the upper limit, the remaining amount of volatile matter can be suppressed. Moreover, the vacuum degree more than a lower limit is realistic on industrial implementation.
The treatment time is appropriately selected depending on the amount of residual volatile matter, but a shorter time is preferable in order to suppress coloring and decomposition of the resulting acrylic resin.

  The polymer recovered through the devolatilization process is processed into a pellet in a process called a granulation process.

  In the granulation step, the molten resin is extruded into a strand shape from a perforated die and processed into pellets by a cold cut method, an air hot cut method, an underwater strand cut method, and an underwater cut method.

  In addition, when an extruder with a vent is employ | adopted as a devolatilization apparatus, you may serve as a devolatilization process and a granulation process.

(Methacrylic resin composition)
The methacrylic resin composition of the present embodiment includes the methacrylic resin of the present embodiment described above, additives that are optionally added, other resins that are resins other than methacrylic resins, rubbery polymers, and the like. Good thing.

-Additives-
The methacrylic resin according to this embodiment may contain various additives as long as the effects of the present invention are not significantly impaired.
Additives are not particularly limited, but include, for example, antioxidants, light stabilizers such as hindered amine light stabilizers, ultraviolet absorbers, mold release agents, other thermoplastic resins, paraffin process oils, naphthenic processes. Oils, aromatic process oils, softeners / plasticizers such as paraffin, organic polysiloxane, mineral oil, flame retardants, antistatic agents, organic fibers, inorganic fillers such as pigments such as iron oxide, glass fibers, carbon fibers And reinforcing agents such as metal whiskers, colorants; organophosphorus compounds such as phosphites, phosphonites and phosphates, other additives, and mixtures thereof.

-Antioxidant-
It is preferable to add to the methacrylic resin according to the present embodiment an antioxidant that suppresses deterioration and coloration during molding or during use.
Examples of the antioxidant include, but are not limited to, hindered phenol-based antioxidants, phosphorus-based antioxidants, and sulfur-based antioxidants. The methacrylic resin of this embodiment is suitably used for various applications such as melt extrusion, injection molding, and film molding. The heat history received during processing varies depending on the processing method, but from several tens of seconds like an extruder to one that receives a heat history of several tens of minutes to several hours like thick-wall molding and sheet forming There are various.
When receiving a long thermal history, it is necessary to increase the amount of heat stabilizer added to obtain the desired thermal stability. From the viewpoint of suppressing bleed-out of the heat stabilizer and preventing sticking of the film to the roll during film formation, it is preferable to use a plurality of heat stabilizers in combination, for example, a phosphorus-based antioxidant and a sulfur-based antioxidant. It is preferable to use at least one selected from an agent together with a hindered phenolic antioxidant.
These antioxidants may be used alone or in combination of two or more.

Examples of the hindered phenol antioxidant include, but are not limited to, pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], thiodiethylene bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 3,3 ′, 3 ″, 5,5 ′, 5 ″ -hexa-tert-butyl-a, a ′, a ″-(mesitylene-2,4,6-triyl) tri-p-cresol, 4,6-bis ( Octylthiomethyl) -o-cresol, 4,6-bis (dodecylthiomethyl) -o-cresol, ethylenebis (oxyethylene) bis [3- (5-tert- Til-4-hydroxy-m-tolyl) propionate], hexamethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 1,3,5-tris (3,5- Di-tert-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-xylin) methyl] -1,3,5-triazine-2,4,6 (1H, 3H, 5H) -trione, 2,6-di-tert-butyl-4- (4 , 6-bis (octylthio) -1,3,5-triazin-2-ylamine) phenol, acrylic acid 2- [1- (2-hydroxy-3,5-di-tert-pentylphenyl) ethyl] -4, 6-di- ert- pentylphenyl, acrylic acid 2-tert-butyl-4-methyl-6- (2-hydroxy -3-tert-butyl-5-methylbenzyl) phenyl and the like.
In particular, pentaerythritol terakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, Acrylic acid 2- [1- (2-hydroxy-3,5-di-tert-pentylphenyl) ethyl] -4,6-di-tert-pentylphenyl is preferred.

The hindered phenolic antioxidant as the antioxidant may be a commercially available phenolic antioxidant, and such a commercially available phenolic antioxidant is limited to the following. However, for example, Irganox 1010 (Irganox 1010: pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], manufactured by BASF), Irganox 1076 (Irganox 1076: Octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate manufactured by BASF), Irganox 1330 (3,3 ′, 3 ″, 5,5 ′, 5 ′) '-Hexa-t-butyl-a, a', a ''-(mesitylene-2,4,6-triyl) tri p-cresol, manufactured by BASF), Irganox 3114 (Irganox 3114: 1,3,5-tris (3,5-di-tert-butyl-4-hydroxybenzyl) -1,3,5-triazine-2,4 , 6 (1H, 3H, 5H) -trione, manufactured by BASF), Irganox 3125 (Irganox 3125, manufactured by BASF), Adekastab AO-60 (pentaerythritol tetrakis [3- (3,5-di-t-butyl) -4-hydroxyphenyl) propionate], manufactured by ADEKA), ADK STAB AO-80 (3,9-bis {2- [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxyoxy] -1,1-dimethylethyl} -2,4,8,10-tetraoxaspiro [5.5] undecane, ADEKA ), Sumilizer BHT (Sumilizer BHT, manufactured by Sumitomo Chemical), Cyanox 1790 (Cyanox 1790, manufactured by Cytec), Sumilizer GA-80 (Sumilizer GA-80, manufactured by Sumitomo Chemical), Sumilizer GS (Sumilizer GS: acrylic acid 2- [ 1- (2-hydroxy-3,5-di-tert-pentylphenyl) ethyl] -4,6-di-tert-pentylphenyl, manufactured by Sumitomo Chemical Co., Ltd., Sumilizer GM (2-tert-butyl acrylate) -4-methyl-6- (2-hydroxy-3-tert-butyl-5-methylbenzyl) phenyl (manufactured by Sumitomo Chemical), vitamin E (manufactured by Eisai) and the like.
Among these commercially available phenolic antioxidants, Irganox 1010, Adekastab AO-60, Adekastab AO-80, Irganox 1076, Sumilizer GS and the like are preferable from the viewpoint of imparting thermal stability with the resin.
These may be used alone or in combination of two or more.

The phosphorus-based antioxidant as the antioxidant is not limited to the following, and examples thereof 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′-diylbisphos Phonite, bis (2,4-di-t-butylphenyl) 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'-diylbisphosphona Di-t-butyl-m-cresyl-phosphonite, 4- [3-[(2,4,8,10-tetra-tert-butyldibenzo [d, f] [1,3,2] dioxaphos Fepin) -6-yloxy] propyl] -2-methyl-6-tert-butylphenol and the like.
Furthermore, a commercially available phosphorus antioxidant may be used as the phosphorus antioxidant. Examples of such commercially available phosphorus antioxidants are not limited to the following, but include Irgaphos 168 ( Irgafos 168: Tris (2,4-di-t-butylphenyl) phosphite, manufactured by BASF), Irgafos 12 (Irgafos 12: Tris [2-[[2,4,8,10-tetra-t-butyldibenzo [ d, f] [1,3,2] dioxaphosphin-6-yl] oxy] ethyl] amine, manufactured by BASF), Irgafos 38 (Irgafos 38: bis (2,4-bis (1,1-dimethyl) Ethyl) -6-methylphenyl) ethyl ester phosphorous acid (manufactured by BASF), ADK STAB 329K (ADK STAB-229K, manufactured by ADEKA) , ADK STAB PEP-36 (ADK STAB PEP-36, manufactured by ADEKA), ADK STAB PEP-36A (ADK STAB PEP-36A, manufactured by ADEKA), ADK STAB PEP-8 (ADK STAB PEP-8, manufactured by ADEKA), ADK STAB HP-10 (ADK STAB HP-10, manufactured by ADEKA), ADK STAB 2112 (ADK STAB 2112, manufactured by ADEKA), ADK STAB 1178 (manufactured by ADK STAB 1178, manufactured by ADEKA), ADK STAB 1500 (manufactured by ADK STAB 1500, manufactured by ADEKA) ), Weston 618 (Weston 618, manufactured by GE), Weston 619G (Weston 619G, manufactured by GE), Ultranox 626 (Ultranox 6) 6, manufactured by GE), Sumizer GP (Sumilizer GP: 4- [3-[(2,4,8,10-tetra-tert-butyldibenzo [d, f] [1,3,2] dioxaphosphepine) ) -6-yloxy] propyl] -2-methyl-6-tert-butylphenol, manufactured by Sumitomo Chemical Co., Ltd.), HCA (9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, manufactured by Sanko Co., Ltd.) ) And the like.
Among these commercially available phosphorous antioxidants, Irgafos 168, ADK STAB PEP-36, ADK STAB PEP-36A, ADK STAB HP from the viewpoint of the effect of imparting thermal stability with the resin and the combined use effect with various antioxidants. −10 and ADK STAB 1178 are preferable, and ADK STAB PEP-36A and ADK STAB PEP-36 are particularly preferable.
These phosphorus antioxidants may be used alone or in combination of two or more.

Further, the sulfur-based antioxidant as the antioxidant is not limited to the following, for example, 2,4-bis (dodecylthiomethyl) -6-methylphenol (Irganox 1726, BASF Corporation). ), Irganox 1520L, manufactured by BASF), 2,2-bis {[3- (dodecylthio) -1-oxopolopoxy] methyl} propane-1,3-diylbis [3-dodecylthio] propionate] (Adekastab AO-412S) , Manufactured by ADEKA), 2,2-bis {[3- (dodecylthio) -1-oxoporopoxy] methyl} propane-1,3-diylbis [3-dodecylthio] propionate] (Cheminox PLS, manufactured by Chemipro Chemical Co., Ltd.), Di (tridecyl) 3,3′-thiodipropionate (AO-503, ADEKA) Manufactured) and the like.
Among these commercially available sulfur antioxidants, Adeka Stab AO-412S and Cheminox PLS are preferable from the viewpoints of the effect of imparting thermal stability with the resin, the effect of combined use with various antioxidants, and the handleability.
These sulfur-based antioxidants may be used alone or in combination of two or more.

  The content of the antioxidant may be an amount that can improve the thermal stability. If the content is excessive, problems such as bleeding out during processing may occur. The amount is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, still more preferably 1 part by mass or less, still more preferably 0.8 parts by mass or less, and more preferably 100 parts by mass or less based on 100 parts by mass of the resin. Preferably it is 0.01-0.8 mass part, Most preferably, it is 0.01-0.5 mass part.

  The timing of adding the antioxidant is not particularly limited, a method of starting polymerization after adding to the monomer solution before polymerization, a method of adding to and mixing with the polymer solution after polymerization, and a method for subjecting to the devolatilization step, Examples thereof include a method of pelletizing after adding / mixing to a later molten polymer, and a method of adding / mixing when devolatilized / pelletized pellets are melt-extruded again. Among these, from the viewpoint of preventing thermal deterioration and coloring in the devolatilization process, after adding / mixing to the polymer solution after polymerization, adding an antioxidant before the devolatilization process, and then subjecting it to the devolatilization process preferable.

-Hindered amine light stabilizers-
A hindered amine light stabilizer can be added to the methacrylic resin of this embodiment.
The hindered amine light stabilizer is not particularly limited, but is preferably a compound containing three or more ring structures. Here, the ring structure is preferably at least one selected from the group consisting of an aromatic ring, an aliphatic ring, an aromatic heterocycle and a non-aromatic heterocycle, and two or more ring structures are formed in one compound. If they are present, they may be the same or different.

The hindered amine light stabilizer is not limited to the following, but specifically, for example, bis (1,2,2,6,6-pentamethyl-4-piperidyl) [[3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl] methyl] butyl malonate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and methyl 1,2,2,6,6 A mixture of pentamethyl-4-piperidyl sebacate, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, N, N′-bis (2,2,6,6-tetramethyl-4- Piperidyl) -N, N′-diformylhexamethylenediamine, dibutylamine, 1,3,5-triazine, N, N′-bis (2,2,6,6-tetramethyl-4-piperidyl-1,6 -Hexame Polycondensate of rangeamine and N- (2,2,6,6-tetramethyl-4-piperidyl) butylamine, poly [{6- (1,1,3,3-tetramethylbutyl) amino-1,3 , 5-triazine-2,4-diyl} {2,2,6,6-tetramethyl-4-piperidyl) imino} hexamethylene {(2,2,6,6-tetramethyl-4-piperidyl) imino} ], Tetrakis (1,2,2,6,6-pentamethyl-4-piperidyl) butane-1,2,3,4-tetracarboxylate, tetrakis (2,2,6,6-tetramethyl-4-piperidyl) ) Butane-1,2,3,4-tetracarboxylate, 1,2,2,6,6-pentamethyl-4-piperidiol and β, β, β ′, β′-tetramethyl-2,4,8, 10-tetraoxaspiro [5.5] Reaction product of ndecane-3,9-diethanol, 2,2,6,6-tetramethyl-4-piperidiol and β, β, β ′, β′-tetramethyl-2,4,8,10-tetraoxaspiro [5.5] Undecane-3,9-diethanol reactant, bis (1-undecanoxy-2,2,6,6-tetramethylpiperidin-4-yl) carbonate, 1,2,2,6,6- Examples include pentamethyl-4-piperidyl methacrylate and 2,2,6,6-tetramethyl-4-piperidyl methacrylate.
Among them, bis (1,2,2,6,6-pentamethyl-4-piperidyl) [[3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl] methyl containing three or more ring structures ] Butyl malonate, dibutylamine, 1,3,5-triazine, N, N′-bis (2,2,6,6-tetramethyl-4-piperidyl-1,6-hexamethylenediamine and N- (2 , 2,6,6-tetramethyl-4-piperidyl) butylamine polycondensate, poly [{6- (1,1,3,3-tetramethylbutyl) amino-1,3,5-triazine-2, 4-diyl} {2,2,6,6-tetramethyl-4-piperidyl) imino} hexamethylene {(2,2,6,6-tetramethyl-4-piperidyl) imino}], 1,2,2 , 6,6-pentamethyl-4-piperidi A reaction product of all and β, β, β ′, β′-tetramethyl-2,4,8,10-tetraoxaspiro [5.5] undecane-3,9-diethanol, 2,2,6,6- A reaction product of tetramethyl-4-piperidiol and β, β, β ′, β′-tetramethyl-2,4,8,10-tetraoxaspiro [5.5] undecane-3,9-diethanol is preferred.

  The content of the hindered amine light stabilizer only needs to be an amount that can improve the light stability. If the content is excessive, problems such as bleeding out during processing may occur. The amount is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, still more preferably 1 part by mass or less, and still more preferably 0.8 parts by mass or less, relative to 100 parts by mass of the methacrylic resin. More preferably, it is 0.01-0.8 mass part, Most preferably, it is 0.01-0.5 mass part.

-UV absorber-
An ultraviolet absorber can be added to the methacrylic resin of this embodiment.
Although it does not specifically limit as an ultraviolet absorber, It is preferable that it is an ultraviolet absorber which has the maximum absorption wavelength in 280-380 nm, for example, a benzotriazole type compound, a benzotriazine type compound, a benzophenone type compound, an oxybenzophenone type compound, for example Benzoate compounds, phenol compounds, oxazole compounds, cyanoacrylate compounds, benzoxazinone compounds, and the like.

Examples of the benzotriazole compound include 2,2′-methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol], 2- (3 5-Di-tert-butyl-2-hydroxyphenyl) -5-chlorobenzotriazole, 2- (2H-benzotriazol-2-yl) -p-cresol, 2- (2H-benzotriazol-2-yl)- 4,6-bis (1-methyl-1-phenylethyl) phenol, 2-benzotriazol-2-yl-4,6-di-tert-butylphenol, 2- [5-chloro (2H) -benzotriazole-2 -Yl] -4-methyl-6-tert-butylphenol, 2- (2H-benzotriazol-2-yl) -4,6-di-tert-butylphenol, 2- ( 2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol, 2- (2H-benzotriazol-2-yl) -4-methyl-6- (3,4) , 5,6-tetrahydrophthalimidylmethyl) phenol, methyl 3- (3- (2H-benzotriazol-2-yl) -5-tert-butyl-4-hydroxyphenyl) propionate / polyethylene glycol 300 reaction product 2- (2H-benzotriazol-2-yl) -6- (linear and side chain dodecyl) -4-methylphenol, 2- (5-methyl-2-hydroxyphenyl) benzotriazole, 2- [2- Hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 3- (2H-benzotriazol-2-yl ) -5- (1,1-dimethylethyl) -4-hydroxy-C7-9 side chain and linear alkyl esters.
Among these, a benzotriazole-based compound having a molecular weight of 400 or more is preferable. For example, in the case of a commercially available product, Kemisorb (registered trademark) 2792 (manufactured by Chemipro Kasei), Adekastab (registered trademark) LA31 (manufactured by ADEKA Corporation), tinuvin ( Registered trademark) 234 (manufactured by BASF).

Examples of benzotriazine compounds include 2-mono (hydroxyphenyl) -1,3,5-triazine compounds, 2,4-bis (hydroxyphenyl) -1,3,5-triazine compounds, and 2,4,6-tris. (Hydroxyphenyl) -1,3,5-triazine compounds are mentioned, and specifically, 2,4-diphenyl-6- (2-hydroxy-4-methoxyphenyl) -1,3,5-triazine, 2 , 4-Diphenyl-6- (2-hydroxy-4-ethoxyphenyl) -1,3,5-triazine, 2,4-diphenyl- (2-hydroxy-4-propoxyphenyl) -1,3,5-triazine 2,4-diphenyl- (2-hydroxy-4-butoxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-butoxyv) Nyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-hexyloxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2- Hydroxy-4-octyloxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-dodecyloxyphenyl) -1,3,5-triazine, 2,4-diphenyl -6- (2-hydroxy-4-benzyloxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-butoxyethoxy) -1,3,5-triazine, 2,4-bis (2-hydroxy-4-butoxyphenyl) -6- (2,4-dibutoxyphenyl) -1,3-5-triazine, 2,4,6-tris (2-hydroxy-4- Meto Cyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-4-ethoxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-4) -Propoxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-4-butoxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy) -4-butoxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-4-hexyloxyphenyl) -1,3,5-triazine, 2,4,6-tris ( 2-hydroxy-4-octyloxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-4-dodecyloxyphenyl) -1,3,5-triazine, 2,4 6-Tris ( 2-hydroxy-4-benzyloxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-4-ethoxyethoxyphenyl) -1,3,5-triazine, 2,4 6-tris (2-hydroxy-4-butoxyethoxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-4-propoxyethoxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-4-methoxycarbonylpropyloxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-4-ethoxycarbonylethyloxyphenyl)- 1,3,5-triazine, 2,4,6-tris (2-hydroxy-4- (1- (2-ethoxyhexyloxy) -1-oxopropan-2-yl Oxy) phenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-3-methyl-4-methoxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-3-methyl-4-ethoxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-3-methyl-4-propoxyphenyl) -1,3,5 Triazine, 2,4,6-tris (2-hydroxy-3-methyl-4-butoxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-3-methyl-4) -Butoxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-3-methyl-4-hexyloxyphenyl) -1,3,5-triazine, 2,4,6- Tris (2-hydroxy- -Methyl-4-octyloxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-3-methyl-4-dodecyloxyphenyl) -1,3,5-triazine, 2 , 4,6-tris (2-hydroxy-3-methyl-4-benzyloxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-3-methyl-4-ethoxyethoxy) Phenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-3-methyl-4-butoxyethoxyphenyl) -1,3,5-triazine, 2,4,6-tris ( 2-hydroxy-3-methyl-4-propoxyethoxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-3-methyl-4-methoxycarbonylpropyloxy) Phenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-3-methyl-4-ethoxycarbonylethyloxyphenyl) -1,3,5-triazine, 2,4,6- And tris (2-hydroxy-3-methyl-4- (1- (2-ethoxyhexyloxy) -1-oxopropan-2-yloxy) phenyl) -1,3,5-triazine.
Commercially available products may be used as the benzotriazine compounds, for example, Kemisorb 102 (manufactured by Chemipro Kasei Co., Ltd.), LA-F70 (manufactured by ADEKA Corporation), LA-46 (manufactured by ADEKA Corporation), Tinuvin 405 (BASF Corporation) Manufactured), Tinuvin 460 (manufactured by BASF), Tinuvin 479 (manufactured by BASF), Tinuvin 1577FF (manufactured by BASF) and the like can be used.
Among them, 2,4-bis (2,4-dimethylphenyl) -6- [2-hydroxy-4- (3-alkyloxy) has high compatibility with acrylic resins and excellent ultraviolet absorption characteristics. And a UV absorber having a -2-hydroxypropyloxy) -5-α-cumylphenyl] -s-triazine skeleton (“alkyloxy” means a long-chain alkyloxy group such as octyloxy, nonyloxy, decyloxy, etc.) It can be preferably used.

  The UV absorber is preferably a benzotriazole-based compound or a benzotriazine-based compound having a molecular weight of 400 or more from the viewpoint of compatibility with the resin and volatility during heating, and heating during extrusion of the UV absorber itself. From the viewpoint of inhibiting decomposition by benzotriazine, a benzotriazine-based compound is particularly preferable.

Further, the melting point (Tm) of the ultraviolet absorber is preferably 80 ° C. or higher, more preferably 100 ° C. or higher, further preferably 130 ° C. or higher, and more preferably 160 ° C. or higher. More preferred.
The ultraviolet absorber preferably has a weight loss rate of 50% or less, more preferably 30% or less, and 15% or less when the temperature is increased from 23 ° C. to 260 ° C. at a rate of 20 ° C./min. Is more preferably 10% or less, still more preferably 5% or less.

These ultraviolet absorbers may be used alone or in combination of two or more.
By using two types of ultraviolet absorbers having different structures in combination, ultraviolet rays in a wide wavelength region can be absorbed.

  The blending amount of the ultraviolet absorber is not particularly limited as long as it is an amount that does not hinder heat resistance, heat and humidity resistance, thermal stability, and moldability and exhibits the effects of the present invention, but 100 mass of methacrylic resin. It is preferably 0.1 to 5 parts by weight, preferably 0.2 to 4 parts by weight, more preferably 0.25 to 3 parts by weight, and still more preferably 0.3 to 5 parts by weight. 3 parts by mass. Within this range, the balance of ultraviolet absorption performance, moldability, etc. is excellent.

-Release agent-
A release agent can be added to the methacrylic resin of this embodiment. Examples of the release agent include, but are not limited to, for example, fatty acid esters, fatty acid amides, fatty acid metal salts, hydrocarbon lubricants, alcohol lubricants, polyalkylene glycols, carboxylic acid esters, carbonization Examples include hydrogen paraffinic mineral oils.

There is no restriction | limiting in particular as fatty acid ester which can be used as the said mold release agent, A conventionally well-known thing can be used.
Examples of fatty acid esters include fatty acids having 12 to 32 carbon atoms such as lauric acid, palmitic acid, heptadecanoic acid, stearic acid, oleic acid, arachidic acid, and behenic acid, and monovalent compounds such as palmityl alcohol, stearyl alcohol, and behenyl alcohol. Esters of aliphatic alcohols and polyhydric aliphatic alcohols such as glycerin, pentaerythritol, dipentaerythritol, sorbitan; complex esters of fatty acids and polybasic organic acids and monohydric aliphatic alcohols or polyhydric aliphatic alcohols A compound or the like can be used.
Examples of such fatty acid ester lubricants include cetyl palmitate, butyl stearate, stearyl stearate, stearyl citrate, glycerol monocaprylate, glycerol monocaprate, glycerol monolaurate, glycerol monopalmitate, glycerol dipalmitate. Tate, glycerol monostearate, glycerol distearate, glycerol tristearate, glycerol monooleate, glycerol dioleate, glycerol trioleate, glycerol monolinoleate, glycerol monobehenate, glycerol mono12-hydroxystearate, glycerol Di12-hydroxystearate, glycerol tri-12-hydroxystearate, glycerol diacetomonostearate, glycerol citrate fatty acid Ester, pentaerythritol adipate stearate, montanic acid partially saponified esters, pentaerythritol tetrastearate, dipentaerythritol hexastearate, mention may be made of sorbitan tristearate and the like.
These fatty acid ester lubricants can be used alone or in combination of two or more.
Commercially available products include, for example, Riken Vitamin's Riquemar series, Poem series, Riquestar series, Riquemaster series, Kao's Exel series, Leodoll series, Exepearl series, and Coconado series. In particular, Riquemar S-100, Riquemar H-100, Poem V-100, Riquemar B-100, Riquemar HC-100, Riquemar S-200, Poem B-200, Riquemar EW-200, Riquemar EW-400, Excel S -95, Rheodor MS-50 and the like.

There is no restriction | limiting in particular also about a fatty acid amide type lubricant, A conventionally well-known thing can be used.
Examples of the fatty acid amide-based lubricant include saturated fatty acid amides such as lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, and hydroxystearic acid amide; unsaturated acids such as oleic acid amide, erucic acid amide, and ricinoleic acid amide Fatty acid amides; substituted amides such as N-stearyl stearic acid amide, N-oleyl oleic acid amide, N-stearyl oleic acid amide, N-oleyl stearic acid amide, N-stearyl erucic acid amide, N-oleyl palmitic acid amide; Methylolamides such as stearic acid amide and methylol behenic acid amide; methylene bis stearic acid amide, ethylene biscapric acid amide, ethylene bislauric acid amide, ethylene bis stearic acid amide (ethylene bisstearyl amide) ), Ethylene bisisostearic acid amide, ethylene bishydroxystearic acid amide, ethylene bisbehenic acid amide, hexamethylene bisbehenic acid amide, hexamethylene bisbehenic acid amide, hexamethylene bishydroxystearic acid amide, N, N′-distearyl Saturated fatty acid bisamides such as adipic acid amide and N, N′-distearyl sebacic acid amide; ethylene bisoleic acid amide, hexamethylene bisoleic acid amide, N, N′-dioleyl adipic acid amide, N, N′-dio Examples thereof include unsaturated fatty acid bisamides such as rail sebacic acid amide; aromatic bisamides such as m-xylylene bisstearic acid amide and N, N′-distearylisophthalic acid amide.
These fatty acid amide release agents can be used alone or in combination of two or more.
Commercially available products include, for example, the Diamond Series (Nippon Kasei Co., Ltd.), Amide Series (Nippon Kasei Co., Ltd.), Nikka Amide Series (Nippon Kasei Co., Ltd.), Methylolamide Series, Bisamide Series, and Sripax Series (Nippon Kasei). Co., Ltd.), Kao Wax Series (manufactured by Kao Corporation), Fatty Acid Amide Series (manufactured by Kao Corporation), ethylenebisstearic acid amides (manufactured by Dainichi Chemical Industry Co., Ltd.), and the like.

The fatty acid metal salt refers to a metal salt of a higher fatty acid, for example, lithium stearate, magnesium stearate, calcium stearate, calcium laurate, calcium ricinoleate, strontium stearate, barium stearate, barium laurate, barium ricinoleate, Zinc stearate, zinc laurate, zinc ricinoleate, zinc 2-ethylhexoate, lead stearate, dibasic lead stearate, lead naphthenate, calcium 12-hydroxystearate, lithium 12-hydroxystearate, etc. Among them, calcium stearate, magnesium stearate, and zinc stearate are particularly preferable because the resulting transparent resin composition has excellent processability and extremely excellent transparency.
Examples of commercially available products include SZ series, SC series, SM series, and SA series manufactured by Sakai Chemical Industry.
In the case of using the fatty acid metal salt, the blending amount is preferably 0.2% by mass or less with respect to 100% by mass of the methacrylic resin composition from the viewpoint of maintaining transparency.

  The said mold release agent may be used individually by 1 type, and may be used in combination of 2 or more type.

  As the mold release agent to be used, those having a decomposition start temperature of 200 ° C. or higher are preferable. Here, the decomposition start temperature can be measured by the 1% weight loss temperature by TGA.

  The content of the release agent may be an amount that can provide an effect as a release agent. If the content is excessive, problems such as bleed out and extrusion failure due to screw sliding occur during processing. Since there is a possibility, it is preferable that it is 5 mass parts or less with respect to 100 mass parts of methacrylic resin, More preferably, it is 3 mass parts or less, More preferably, it is 1 mass part or less, More preferably, it is 0.8 mass. Or less, more preferably 0.01 to 0.8 parts by mass, particularly preferably 0.01 to 0.5 parts by mass. When added in an amount in the above range, it is possible to suppress a decrease in transparency due to the addition of a release agent and to suppress sticking to a metal roll at the time of injection molding or sheet molding, preferable.

-Other thermoplastic resins-
Other thermoplastic resins can be blended with the methacrylic resin of the present embodiment for the purpose of adjusting the birefringence and improving flexibility without impairing the object of the present invention.
Examples of the other thermoplastic resins include polyacrylates such as polybutyl acrylate; polystyrene, styrene-methyl methacrylate copolymer, styrene-butyl acrylate copolymer, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene. Styrenic polymers such as block copolymers; and further, for example, JP-A-59-202213, JP-A-63-27516, JP-A-51-129449, JP-A-52-56150 Acrylic rubber particles having a three- to four-layer structure; rubber polymers disclosed in JP-B-60-17406 and JP-A-8-245854; described in International Publication No. 2014-002491 , Methacrylic rubber-containing graph copolymer particles obtained by multistage polymerization; It is.
Among these, from the viewpoint of obtaining good optical properties and mechanical properties, from a composition compatible with a styrene-acrylonitrile copolymer and a methacrylic resin containing a structural unit (X) having a ring structure in the main chain. The rubber-containing graft copolymer particles having a graft portion on the surface layer are preferable.
The average particle diameter of the acrylic rubber particles, the methacrylic rubber-containing graph copolymer particles, and the rubbery polymer described above is a viewpoint of improving the impact strength, optical characteristics, etc. of the film obtained from the composition of the present embodiment. Therefore, it is preferably 0.03 to 1 μm, more preferably 0.05 to 0.5 μm.

  The content of the other thermoplastic resin is preferably 0 to 50 parts by mass, more preferably 0 to 25 parts by mass when the methacrylic resin is 100 parts by mass.

Characteristics of the methacrylic resin composition of the present embodiment, specifically, the composition of the structural unit, the glass transition temperature (Tg), the content of the component having light absorption at a wavelength of 400 nm in the methanol-soluble component, the molecular weight of 2000 or less Component content, methanol soluble fraction, molecular weight, and photoelastic coefficient ( _CR ) are as described above for the methacrylic resin of this embodiment.

(Method for producing methacrylic resin composition)
Examples of the method for producing a methacrylic resin composition include a method of kneading using a kneader such as an extruder, a heating roll, a kneader, a roller mixer, and a Banbury mixer. Among these, kneading with an extruder is preferable in terms of productivity. The kneading temperature may be in accordance with the preferred processing temperature of the polymer constituting the methacrylic resin and other resins to be mixed, and is generally in the range of 140 to 300 ° C, preferably in the range of 180 to 280 ° C. The extruder is preferably provided with a vent port for the purpose of reducing volatile components.

(Molded body)
The methacrylic resin and methacrylic resin composition of the present embodiment can be suitably used as materials for various molded products.

(Method for producing molded body)
As a method for producing the molded body, various molding methods such as extrusion molding, injection molding, compression molding, calendar molding, inflation molding, and hollow molding can be used.
Examples of the use of the molded body include household goods, OA equipment, AV equipment, battery electrical equipment, lighting equipment, automobile parts use, housing use, sanitary use such as sanitary ware replacement, and optical parts use.
Examples of the automobile parts include a tail lamp, a meter cover, a head lamp, a light guide rod, a lens, and a car navigation front plate.
As optical parts, light guide plate, diffuser plate, polarizing plate protective film, 1/4 wavelength plate, 1/2 wavelength used for liquid crystal display, plasma display, organic EL display, field emission display, rear projection TV, etc. Examples thereof include a retardation film such as a plate, a viewing angle control film, and a liquid crystal optical compensation film, a display front plate, a display substrate, a lens, a touch panel, and the like, and can be suitably used for a transparent substrate used for a solar cell. In addition, in the fields of optical communication systems, optical switching systems, optical measurement systems, or optical products such as head mounted displays and liquid crystal projectors, waveguides, lenses, optical fibers, optical fiber coating materials, LED lenses, lens covers, etc. Can also be used. It can also be used as a modifier for other resins.

  Various molded products using the methacrylic resin and the resin composition of the present embodiment can be further subjected to surface functionalization treatment such as antireflection treatment, transparent conductive treatment, electromagnetic wave shielding treatment, and gas barrier treatment.

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

<1. Measurement of polymerization conversion>
A part of the polymerization solution in Examples and Comparative Examples was collected, and the amount of monomer remaining in this polymerization solution sample was dissolved in chloroform to prepare a 5 mass% solution, and n was used as an internal standard substance. -Decane was added, the concentration of the monomer remaining in the sample was measured using gas chromatography (GC-2010, manufactured by Shimadzu Corporation), and the total mass (a) of the monomer remaining in the polymerization solution was determined. Asked. Then, from this total mass (a) and the total mass (b) of the monomer added up to the time when the sample was collected, the polymerization conversion rate (%) was calculated by the formula (ba) / b × 100. Calculated.

<2. Analysis of structural units>
Unless otherwise specified in each Example and Comparative Example, the structural units of the methacrylic resins produced in Examples and Comparative Examples were identified by ¹ H-NMR measurement and ¹³ C-NMR measurement, and their abundance was calculated. . The measurement conditions for ¹ H-NMR measurement and ¹³ C-NMR measurement are as follows.
Measuring instrument: JNM-ECZ400S manufactured by JEOL Ltd.
Measurement solvent: CDCl ₃ or DMSO-d ₆
・ Measurement temperature: 40 ℃

<3. Measurement of molecular weight and molecular weight distribution>
The weight average molecular weight (Mw) and number average molecular weight (Mn) of the methacrylic resins produced in Examples and Comparative Examples were measured using the following apparatus and conditions.
Measurement device: manufactured by Tosoh Corporation, gel permeation chromatography (HLC-8320GPC)
·Measurement condition:
Column: One TSKguardcolumn SuperH-H, two TSKgel SuperHM-M, and one TSKgel SuperH2500 were connected in series in this order. Column temperature: 40 ° C
Developing solvent: Tetrahydrofuran, Flow rate: 0.6 mL / min, 0.16 g / L of 2,6-di-t-butyl-4-methylphenol (BHT) was added as an internal standard.
Detector: RI (differential refraction) detector, detection sensitivity: 3.0 mV / min Sample: 0.02 g of methacrylic resin in 20 mL of tetrahydrofuran. Injection volume: 10 μL
Standard sample for calibration curve: The following 10 polymethyl methacrylates (manufactured by Polymer Laboratories; PMMAC calibration Kit M-M-10) having different molecular weights but known monodisperse weight peak molecular weights were used.
Weight peak molecular weight (Mp)
Standard sample 1 1,916,000
Standard sample 2 625,500
Standard sample 3 298,900
Standard sample 4 138,600
Standard sample 5 60,150
Standard sample 6 27,600
Standard sample 7 10,290
Standard sample 85,000
Standard sample 9 2,810
Standard sample 10 850
Under the above conditions, the RI detection intensity with respect to the elution time of the methacrylic resin was measured.
The weight average molecular weight (Mw) and number average molecular weight (Mn) of the methacrylic resin are obtained based on the calibration curve obtained by the measurement of the standard sample for the calibration curve, and the molecular weight distribution ((Mw / Mn) was determined.

<4. Glass transition temperature>
Based on JIS-K7121, the glass transition temperature (Tg) (degreeC) of the methacrylic resin was measured.
First, 4 pieces (about 4 places) of about 10 mg each were cut out as test pieces from a sample that was conditioned (left at 23 ° C. for 1 week) under standard conditions (23 ° C., 65% RH).
Next, a differential scanning calorimeter (Diamond DSC manufactured by PerkinElmer Japan Co., Ltd.) was used under the condition of a nitrogen gas flow rate of 25 mL / min, where the temperature rose from room temperature (23 ° C.) to 200 ° C. at 10 ° C./min. Temperature (primary temperature increase), held at 200 ° C. for 5 minutes to completely melt the sample, then cooled to 10 ° C./minute from 200 ° C. to 40 ° C., held at 40 ° C. for 5 minutes, Of the DSC curve drawn during the temperature rise (secondary temperature rise) again under the above temperature rise conditions, the stepwise change partial curve at the time of the secondary temperature rise and the respective base line extension lines are equidistant in the vertical axis direction. The intersection (intermediate glass transition temperature) with a certain straight line was measured as the glass transition temperature (Tg) (° C.). Four points were measured per sample, and the arithmetic average of four points (rounded off after the decimal point) was taken as the measured value.

<5. Measurement of photoelastic coefficient C _R>
The methacrylic resin obtained in Examples and Comparative Examples was used as a measurement sample by using a vacuum compression molding machine as a press film.
As specific sample preparation conditions, using a vacuum compression molding machine (manufactured by Shinfuji Metal Industry Co., Ltd., SFV-30 type), preheating at 260 ° C. under reduced pressure (about 10 kPa) for 10 minutes, After compressing at about 10 MPa for 5 minutes and releasing the reduced pressure and the press pressure, it was transferred to a cooling compression molding machine and solidified by cooling. The obtained press film was cured for 24 hours or more in a constant temperature and humidity chamber adjusted to 23 ° C. and a humidity of 60%, and then a test specimen (thickness: about 150 μm, width: 6 mm) was cut out.
The photoelastic coefficient C _R (Pa ⁻¹ ) was measured using a birefringence measuring device described in detail in Polymer Engineering and Science 1999, 39, 2349-2357.
The film-shaped test piece was similarly arrange | positioned so that it might become 50 mm between chuck | zippers on the film tension apparatus (made by Imoto Seisakusho) installed in the constant temperature and humidity chamber. Next, the apparatus was arranged so that the laser beam path of the birefringence measuring apparatus (manufactured by Otsuka Electronics, RETS-100) was positioned at the center of the film, and the strain rate was 50% / min (between chucks: 50 mm, chuck moving speed: The birefringence of the test piece was measured while applying an extensional stress at 5 mm / min.
From the relationship between the absolute value of birefringence (| Δn |) and the tensile stress (σ _R ) obtained from the measurement, the slope of the straight line is obtained by least square approximation, and the photoelastic coefficient (C _R ) (Pa ⁻¹ ) is obtained. Calculated. For the calculation, data with an extensional stress between 2.5 MPa ≦ σ _R ≦ 10 MPa was used.
C _R = | Δn | / σ _R
Here, 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)

<6. Measurement of the amount of methanol soluble matter and the amount of methanol insoluble matter>
After 5 g of the methacrylic resin obtained in Examples and Comparative Examples was dissolved in 100 mL of chloroform, the solution was put into a dropping funnel and dropped into 1 L of methanol stirred with a stir bar over about 1 hour. Then, reprecipitation was performed. After dropping the whole amount, the solution was allowed to stand for 1 hour, and then suction filtration was performed using a membrane filter (T05A090C, manufactured by Advantech Toyo Co., Ltd.) as a filter.
The filtrate was vacuum-dried at 60 ° C. for 16 hours to make methanol insoluble. Further, the filtrate remains in the eggplant-shaped flask after removing the solvent by using a rotary evaporator and setting the bath temperature to 40 ° C. and gradually lowering the vacuum from the initial setting of 390 Torr to 30 Torr. Soluble components were collected and used as methanol soluble components.
Each of the mass of the methanol-insoluble part and the mass of the methanol-soluble part is weighed, and the ratio of the amount of methanol-soluble part to the total amount (100% by mass) of the amount of methanol-soluble part and the amount of methanol-insoluble part (mass) %) (Methanol soluble fraction) was calculated.

<7. Content of component having molecular weight of 2000 or less and content of component having absorbance at wavelength of 400 nm in methanol-soluble matter>
In accordance with “3. Measurement of molecular weight and molecular weight distribution”, in addition to the RI detector as a detector, the reprecipitation soluble component is a 0.030 g / mL THF solution, and a UV detector (manufactured by Tosoh Corporation, GPC measurement was performed using UV-8020, a light source as a tungsten lamp and a wavelength of 400 nm.
Using the peak elution time of standard PMMA with a weight peak molecular weight of 2000 separately measured, the elution area with a molecular weight of 2000 or less is calculated from the measurement result of the RI detector, and the molecular weight contained in the methanol soluble matter from the ratio to the total peak area Content (mass%) of 2000 or less component was computed.
In addition, a calibration curve in a UV detector with a wavelength of 400 nm for N-phenylmaleimide was prepared, and the amount of components having absorbance at a wavelength of 400 nm in terms of N-phenylmaleimide from the total elution peak area in the UV detector of methanol-soluble components And the content (% by mass) of the component having absorbance at a wavelength of 400 nm in the methanol-soluble component was calculated.
Furthermore, the content (mass%) of the N-phenylmaleimide monomer in the methanol-soluble component is also <1. The measurement was performed by measurement using gas chromatography according to the measurement of polymerization conversion>.

<8. Measurement of color tone of molded piece>
The methacrylic resins obtained in the examples and comparative examples described below were subjected to a molding temperature of 250 ° C. and a mold temperature of 90 ° C. using an injection molding machine (AUTO SHOT C Series MODEL 15A, manufactured by FANUC Corporation). A strip-shaped test piece having a thickness of 3 mm, a width of 12 mm, and a length of 124 mm was produced.
(8-1) Measurement of YI and total light transmittance at an optical path length of 3 mm Using a spectrocolorimeter (Nippon Denshoku Industries Co., Ltd., SD-5000), the light source was a molded piece. The YI (conforming to JIS K7373) and the total light transmittance (conforming to JIS K7361-1) (%) were measured with a D65 light source with a 10 ° field of view and an optical path length of 3 mm. Three measurements were taken and the average value was used.
(8-2) Measurement of YI and Y value at optical path length of 80 mm The obtained molded piece was cut into 80 mm in the longitudinal direction, and using a polishing machine (Megaro Technica Co., Ltd., Plasticity) Both end faces perpendicular to the longitudinal direction of the molded piece were polished at a rotational speed of 8500 rpm and a feed rate of 1 m / min.
Using a color difference meter (Nippon Denshoku Industries Co., Ltd., COH300A), the polished piece was placed so that the polished end face was perpendicular to the light source, and the optical path length was 80 mm with a C light source of 2 ° field of view. YI and the Y value as an index of luminous transmittance were measured.

[material]
It shows below about the raw material used in the Example and comparative example which are mentioned later.
[[Monomer]]
・ Methyl methacrylate: Asahi Kasei Corporation ・ N-Phenylmaleimide (phMI): Nippon Shokubai Co., Ltd. ・ N-cyclohexylmaleimide (chMI): Nippon Shokubai Co., Ltd. ・ Styrene (St): Asahi Kasei Co., Ltd. Agent]]
1,1-di (t-butylperoxy) cyclohexane: NOF Corporation "Perhexa C"
T-Butyl peroxyisopropyl monocarbonate: “Perbutyl I” manufactured by NOF Corporation
[[Chain transfer agent]]
-N-octyl mercaptan: manufactured by Kao Corporation-n-dodecyl mercaptan: manufactured by Kao Corporation [[Antioxidant]]
Pentaerythritol = tetrakis [3- (3 ′, 5′-di-tert-butyl-4′-hydroxyphenyl) propionate]: “Irganox 1010” manufactured by BASF
Tris (2,4-di-t-butylphenyl) phosphite: “Irgafos 168” manufactured by BASF
[Other additives]
・ Acetic anhydride: Wako Pure Chemical Industries, Ltd.

[Example 1]
340.7 kg of methyl methacrylate (hereinafter referred to as MMA), 39.6 kg of N-phenylmaleimide (hereinafter referred to as phMI), 59.7 kg of N-cyclohexylmaleimide (hereinafter referred to as chMI), n-octyl mercaptan as a chain transfer agent 0.275 kg and metaxylene 236.9 kg (hereinafter referred to as mXy) were weighed and added to a 1.25 m ³ reactor equipped with a jacket temperature controller and a stirring blade to obtain a mixed monomer solution.
Next, 123.1 kg of mXy was weighed to prepare a solvent for addition in the tank 1.
Furthermore, 110.0 kg of MMA and 90.0 kg of mXy were weighed in the tank 2 and stirred to obtain a supplemental MMA solution.
Bubbling with nitrogen is performed for 1 hour for the contents of the reactor at a rate of 30 L / min, and bubbling with nitrogen is performed for 30 minutes for each of tank 1 and tank 2 for 10 minutes to remove dissolved oxygen. did.
Thereafter, steam was blown into the jacket to raise the solution temperature in the reactor to 128 ° C., and 0.371 kg of 1,1-di (t-butylperoxy) cyclohexane was dissolved in 3.004 kg of mXy while stirring at 50 rpm. Polymerization was started by adding the polymerization initiator solution at a rate of 1 kg / hour.
During polymerization, the temperature of the solution in the reactor was controlled at 128 ± 2 ° C. by adjusting the temperature with a jacket. 30 minutes after the start of polymerization, the addition rate of the initiator solution was reduced to 0.25 kg / hour, and mXy was further added from tank 1 at 30.78 kg / hour for 3.5 hours.
Then, 4 hours after the start of polymerization, the addition rate of the initiator solution was increased to 0.75 kg / hour, and an additional MMA solution was added from tank 2 at 100 kg / hour for 2 hours.
Furthermore, 6 hours after the start of polymerization, the addition rate of the initiator solution was reduced to 0.5 kg / hour, and the addition was stopped 7 hours after the start of polymerization.
After 8 hours from the start of polymerization, a polymerization solution containing a methacrylic resin was obtained.
After 3 hours, 4 hours, and 8 hours (at the end of polymerization), the polymer solution was sampled and the polymerization conversion was analyzed from the remaining monomer concentration. MMA 87.7%, phMI 84.6%, chMI 74.7%, 4 hours later MMA 92.9%, phMI 90.3%, chMI 84.1%, 8 hours later MMA 92.2%, phMI 99.4%, chMI 98. 3%.
Next, devolatilization was performed by introducing the obtained polymer solution into a twin-screw extruder equipped with a plurality of vent ports for devolatilization. In the twin screw extruder, the obtained copolymer solution was supplied so as to be 10 kg / hour in terms of resin, and the conditions were a barrel temperature of 260 ° C., a screw rotation speed of 150 rpm, and a degree of vacuum of 10 to 40 Torr. The resin devolatilized by a twin screw extruder was extruded from a strand die, cooled with water and pelletized to obtain a methacrylic resin.
As a result of confirming the composition of the obtained pellet-like polymer, the structural units derived from MMA, phMI, and chMI monomers were 80.9 mass%, 7.7 mass%, and 11.4 mass%, respectively. there were. Moreover, the weight average molecular weight was 149,000 and Mw / Mn was 2.26. Other physical properties are shown in Table 1.

[Example 2]
A methacrylic resin was obtained in the same manner as in Example 1 except that the addition of the MMA solution for addition from the tank 2 was performed for 2 hours after 3 hours from the start of polymerization.
After 3 hours and 8 hours (at the end of polymerization), the polymer solution was sampled and the polymerization conversion was analyzed from the remaining monomer concentration. PhMI 84.6%, chMI 74.7%, 8 hours later, MMA 94.0%, phMI 99.3%, chMI 97.2%.
Moreover, when the composition of the obtained pellet-like polymer was confirmed, the structural units derived from MMA, phMI, and chMI monomers were 81.3 mass%, 7.6 mass%, and 11.1 mass%, respectively. %Met. Moreover, the weight average molecular weight was 152,000 and Mw / Mn was 2.34. Other physical properties are shown in Table 1.

[Example 3]
A methacrylic resin was obtained in the same manner as in Example 1 except that the addition of the additional MMA solution from the tank 2 was performed for 2.5 hours after 2.5 hours from the start of polymerization.
The polymer solution was sampled 2.5 hours after the start of polymerization and 8 hours after the end of the polymerization (at the end of polymerization), and the polymerization conversion was analyzed from the remaining monomer concentration. MMA 82.1%, phMI 79.7%, chMI 68.8%, MMA 95.0%, phMI 99.1%, chMI 97.1% after 8 hours.
Moreover, when the composition of the obtained pellet-like polymer was confirmed, the structural units derived from MMA, phMI, and chMI monomers were 81.5% by mass, 7.5% by mass, and 11.0% by mass, respectively. %Met. Moreover, the weight average molecular weight was 153,000 and Mw / Mn was 2.39. Other physical properties are shown in Table 1.

[Example 4]
MMA 335.5 kg, phMI 37.4 kg, chMI 67.1 kg, chain transfer agent n-octyl mercaptan 0.300 kg, mXy 236.9 kg, 1.25 m ³ reactor equipped with jacket temperature controller and stirring blade And stirred to obtain a mixed monomer solution.
Next, 123.1 kg of mXy was weighed to prepare a solvent for addition in the tank 1.
Furthermore, 110.0 kg of MMA and 90.0 kg of mXy were weighed in the tank 2 and stirred to obtain a supplemental MMA solution.
Bubbling with nitrogen is performed for 1 hour for the contents of the reactor at a rate of 30 L / min, and bubbling with nitrogen is performed for 30 minutes for each of tank 1 and tank 2 for 10 minutes to remove dissolved oxygen. did.
Thereafter, steam was blown into the jacket to raise the temperature of the solution in the reactor to 123 ° C., and while stirring at 50 rpm, 0.481 kg of 1,1-di (t-butylperoxy) cyclohexane was dissolved in 2.644 kg of mXy. Polymerization was started by adding the polymerization initiator solution at a rate of 1 kg / hour.
During polymerization, the temperature of the solution in the reactor was controlled at 123 ± 2 ° C. by adjusting the temperature with a jacket. 30 minutes after the start of polymerization, the addition rate of the initiator solution was reduced to 0.25 kg / hour, and mXy was further added from tank 1 at 30.78 kg / hour for 3.5 hours.
Then, 4 hours after the start of polymerization, the addition rate of the initiator solution was increased to 0.75 kg / hour, and an additional MMA solution was added from tank 2 at 100 kg / hour for 2 hours.
Further, the addition rate of the initiator solution was reduced to 0.25 kg / hour after 6 hours from the start of polymerization, and the addition was stopped after 7 hours from the start of polymerization.
After 8 hours from the start of polymerization, a polymerization solution containing a methacrylic resin was obtained.
The polymer solution was sampled 4 hours after the start of the polymerization and 8 hours after the completion of the polymerization (at the end of the polymerization), and the polymerization conversion rate was analyzed from the remaining monomer concentration. PhMI 92.7%, chMI 88.3%, 8 hours later, MMA 92.0%, phMI 99.1%, chMI 97.8%.
Next, the resulting polymer solution was devolatilized by supplying it to a concentrating device consisting of a tubular heat exchanger and a vaporization tank preliminarily heated to 250 ° C. The degree of vacuum in the vaporization tank was set to 10 to 15 Torr. The resin flowing down the vaporization tank was discharged with a screw pump, extruded from a strand die, cooled with water, and pelletized to obtain a methacrylic resin.
When the composition of the obtained pellet-like polymer was confirmed, the structural units derived from MMA, phMI, and chMI monomers were 80.0% by mass, 7.2% by mass, and 12.8% by mass, respectively. there were. Moreover, the weight average molecular weight was 137,000 and Mw / Mn was 2.32. Other physical properties are shown in Table 1.

[Example 5]
Eight hours after the start of polymerization, 0.275 kg of Irganox 1010 and 0.825 kg of Irgafos 168 were added as antioxidants, and after devolatilization after stirring and mixing, a methacrylic resin composition was obtained in the same manner as in Example 4. It was.
When the composition of the obtained pellet-shaped composition was confirmed, the structural units derived from MMA, phMI, and chMI monomers were 80.0% by mass, 7.2% by mass, and 12.8% by mass, respectively. there were. Moreover, the weight average molecular weight was 139,000 and Mw / Mn was 2.28. Other physical properties are shown in Table 1.

[Comparative Example 1]
MMA 450.7kg, phMI 39.6kg, chMI 59.7kg, chain transfer agent n-octyl mercaptan 0.413kg, mXy 450.0kg, 1.25m ³ reactor equipped with jacket temperature controller and stirring blade And stirred to obtain a mixed monomer solution.
The contents of the reactor were bubbled with nitrogen at a rate of 30 L / min for 1 hour to remove dissolved oxygen.
Thereafter, steam was blown into the jacket to raise the temperature of the solution in the reactor to 125 ° C., and while stirring at 50 rpm, 0.231 kg of 1,1-di (t-butylperoxy) cyclohexane was dissolved in 2.769 kg of mXy. The polymerization was started by adding the polymerization initiator solution at a rate of 0.5 kg / hour.
During the polymerization, the temperature of the solution in the reactor was controlled at 125 ± 2 ° C. by adjusting the temperature with a jacket. The initiator solution was added at a constant rate and stopped 6 hours after the start of polymerization.
After 8 hours from the start of polymerization, a polymerization solution containing a methacrylic resin was obtained.
The polymer solution was sampled 8 hours after the start of the polymerization (at the end of the polymerization), and the polymerization conversion rate was analyzed from the remaining monomer concentration. As a result, 8 hours later, MMA 95.7% and phMI 96.6. %, ChMI 93.3%.
Next, devolatilization was performed by introducing the obtained polymer solution into a twin-screw extruder equipped with a plurality of vent ports for devolatilization. In the twin screw extruder, the obtained copolymer solution was supplied so as to be 10 kg / hour in terms of resin, and the conditions were a barrel temperature of 260 ° C., a screw rotation speed of 150 rpm, and a degree of vacuum of 10 to 40 Torr. The resin devolatilized by a twin screw extruder was extruded from a strand die, cooled with water and pelletized to obtain a methacrylic resin.
When the composition of the obtained pellet-like polymer was confirmed, the structural units derived from MMA, phMI, and chMI monomers were 82.1% by mass, 7.3% by mass, and 10.6% by mass, respectively. there were. Moreover, the weight average molecular weight was 148,000 and Mw / Mn was 2.31. Other physical properties are shown in Table 1.

[Comparative Example 2]
140.0 kg of MMA, 100.0 kg of chMI, and 250 kg of toluene were weighed and added to a 1.25 m ³ reactor equipped with a temperature control device by a jacket and a stirring blade to obtain a mixed monomer solution.
Next, 82.5 kg of MMA, 25.0 kg of chMI, 35.0 kg of styrene, and 200.0 kg of toluene were weighed and added to the tank 1 and stirred to obtain a mixed monomer solution for addition.
Further, 82.5 kg of MMA, 35.0 kg of styrene, and 50.0 kg of toluene were weighed and added to the tank 2 and stirred to obtain a mixed monomer solution for addition.
The reactor liquid was bubbled with nitrogen at a rate of 30 L / min for 1 hour, and the inner solution of each of tank 1 and tank 2 was bubbled with nitrogen at a rate of 10 L / min for 30 minutes. Was removed.
Thereafter, steam was blown into the jacket to raise the temperature of the solution in the reactor to 110 ° C., and a polymerization initiator in which 0.20 kg of t-butylperoxyisopropyl monocarbonate was dissolved in 0.8 kg of toluene while stirring at 50 rpm. Polymerization is started by adding the solution into the reactor, and a polymerization initiator solution in which 2.30 kg of t-butylperoxyisopropyl monocarbonate is dissolved in 4.70 kg of toluene is added at a rate of 3.5 kg at a rate of 2 kg / hour. Added for hours.
In addition, the content liquid in tank 1 was added at a constant rate for 3.5 hours after the start of polymerization, and then the content liquid in tank 2 was added at a constant rate for 3.5 hours thereafter. After the lapse, a polymerization solution containing a methacrylic resin was obtained.
During polymerization, the temperature of the solution in the reactor was controlled at 110 ± 2 ° C. by adjusting the temperature with a jacket.
Next, devolatilization was performed by introducing the obtained polymer solution into a twin-screw extruder equipped with a plurality of vent ports for devolatilization. In the twin screw extruder, the obtained copolymer solution was supplied so as to be 10 kg / hour in terms of resin, and the conditions were a barrel temperature of 260 ° C., a screw rotation speed of 150 rpm, and a degree of vacuum of 10 to 40 Torr. The resin devolatilized by a twin screw extruder was extruded from a strand die, cooled with water and pelletized to obtain a methacrylic resin.
When the composition of the obtained pellet-like polymer was confirmed, the structural units derived from MMA, chMI, and styrene monomers were 54.1% by mass, 28.0% by mass, and 17.9% by mass, respectively. there were. Moreover, the weight average molecular weight was 108,000 and Mw / Mn was 2.83. Other physical properties are shown in Table 1.

[Comparative Example 3]
MMA 450.0 kg, phMI 50.0 kg, toluene 500 kg, n-dodecyl mercaptan 2.0 kg, acetic anhydride 2.0 kg are weighed and added to a 1.25 m ³ reactor equipped with a temperature control device by a jacket and a stirring blade, and stirred. A mixed monomer solution was obtained. Bubbling with nitrogen was performed on the contents of the reactor at a rate of 30 L / min for 1 hour to remove dissolved oxygen.
Thereafter, steam was blown into the jacket to raise the temperature of the solution in the reactor to 110 ° C., and 1.5 kg of t-butylperoxyisopropyl monocarbonate was added to the reactor while stirring at 50 rpm. The polymerization was continued for 15 hours.
During polymerization, the temperature of the solution in the reactor was controlled at 110 ± 2 ° C. by adjusting the temperature with a jacket.
Next, devolatilization was performed by introducing the obtained polymer solution into a twin-screw extruder equipped with a plurality of vent ports for devolatilization. In the twin screw extruder, the obtained copolymer solution was supplied so as to be 10 kg / hour in terms of resin, and the conditions were a barrel temperature of 260 ° C., a screw rotation speed of 150 rpm, and a degree of vacuum of 10 to 40 Torr. The resin devolatilized by a twin screw extruder was extruded from a strand die, cooled with water and pelletized to obtain a methacrylic resin.
When the composition of the obtained pellet-shaped polymer was confirmed, the structural units derived from MMA and phMI monomers were 89.9% by mass and 10.1% by mass, respectively. Moreover, the weight average molecular weight was 152,000 and Mw / Mn was 2.58. Other physical properties are shown in Table 1.

[Comparative Example 4]
A methacrylic resin was obtained in the same manner as in Example 1 except that the addition of the MMA solution for addition from the tank 2 was performed for 2 hours after 2 hours from the start of polymerization.
The polymer solution was sampled 2 hours after the start of polymerization and 8 hours after the end of the polymerization (at the end of the polymerization), and the polymerization conversion was analyzed from the remaining monomer concentration. PhMI 73.7%, chMI 62.1%, 8 hours later were MMA 96.2%, phMI 98.9%, chMI 96.8%.
Moreover, when the composition of the obtained pellet-like polymer was confirmed, the structural units derived from MMA, phMI, and chMI monomers were 81.7% by mass, 7.4% by mass, and 10.9% by mass, respectively. %Met. Moreover, the weight average molecular weight was 156,000 and Mw / Mn was 2.36. Other physical properties are shown in Table 1.

  As shown in Table 1, since the methacrylic resin of the present embodiment has a low YI in the long optical path of the obtained molded body and excellent color tone, and has a high transmittance, the molded body is used for optical parts such as a light guide plate, It can be suitably used for automotive parts such as tail lamps, meter covers, and head lamps.

The methacrylic resin of the present invention has high heat resistance, highly controlled birefringence, and excellent color tone and transparency.
The methacrylic resin of the present invention is used as an optical material, for example, a light guide plate, a diffusion plate, a polarizing plate protective film used in displays such as liquid crystal displays, plasma displays, organic EL displays, field emission displays, rear projection televisions, etc .; / 4 wavelength plate, half wave plate, etc .; liquid crystal optical compensation film such as viewing angle control film; display front plate; display substrate; lens; transparent conductive material such as transparent substrate and touch panel used in solar cell Substrate: Optical communication systems, optical switching systems, optical measurement systems, or optical products such as head mounted displays and liquid crystal projectors, waveguides, lenses, lens arrays, optical fibers, optical fiber coating materials; LED lenses; lens covers Etc. Household appliances, OA equipment, AV equipment, battery electrical equipment, lighting equipment; tail lamp, meter cover, head lamp, light guide rod, lens, car navigation front panel and other automotive parts use; housing use; sanitary ware replacement, etc. It can be suitably used as a sanitary application.

Claims (11)

A methacrylic resin containing 5 to 40% by mass of a structural unit (B) derived from an N-substituted maleimide monomer in the main chain,
The structural unit (B) derived from the N-substituted maleimide monomer includes a structural unit represented by the following formula (1):

(In the formula (1), R ¹ represents either an arylalkyl group having 7 to 14 carbon atoms or an aryl group having 6 to 14 carbon atoms, and R ² and R ³ are each independently a hydrogen atom, carbon Any one of an alkyl group having 1 to 12 carbon atoms and an aryl group having 6 to 14 carbon atoms, and when R ² is an aryl group, R ² may contain a halogen as a substituent.
The glass transition temperature is over 120 ° C. and below 160 ° C.,
The content of the component having an absorption at a wavelength of 400 nm in the methanol-soluble component is 2% by mass or less in terms of N-phenylmaleimide.
A methacrylic resin characterized by that.   The methacrylic resin according to claim 1, wherein the content of the component having a molecular weight of 2000 or less in the methanol-soluble component is 40% by mass or less.   The methacrylic resin is based on 100% by mass of the methacrylic resin, the main chain has a methacrylic acid ester monomer unit (A): 50 to 95% by mass, and other copolymerizable with the methacrylic acid ester monomer. The methacrylic resin according to claim 1, comprising: 0 to 20% by mass of a vinyl monomer unit (C):   The content of the (B) structural unit is 45 to 100% by mass, where the total amount of the (B) structural unit and the (C) monomer unit is 100% by mass. Methacrylic resin.   The (C) monomer unit includes at least one structural unit selected from the group consisting of an acrylate monomer, an aromatic vinyl monomer, and a vinyl cyanide monomer. 4. Methacrylic resin according to 4. Photoelastic coefficient of ^{-2 × 10 -12 ~ + 2 ×} 10 -12 Pa -1, methacrylic resin according to any one of claims 1-5. In a method of radical polymerization of two or more monomer components including a methacrylic acid ester monomer and an N-substituted maleimide monomer in a solvent,
The N-substituted maleimide monomer includes an N-substituted maleimide monomer N-substituted with an aryl group or an arylalkyl group;
The N-substituted maleimide monomer has a final conversion rate of 97% or more;
A method for producing a methacrylic resin, wherein a final conversion rate of the methacrylic acid ester monomer is 88 to 96%.   When a part of the methacrylic acid ester monomer is copolymerized with the N-substituted maleimide monomer and the conversion of the methacrylic acid ester monomer becomes 80 to 95%, The method for producing a methacrylic resin according to claim 7, wherein the remainder of the monomer is added.   It consists of the methacrylic resin as described in any one of Claims 1-6, or the methacrylic resin composition containing this methacrylic resin, The molded object characterized by the above-mentioned.   A molded body comprising a methacrylic resin obtained by the production method according to claim 7 or 8, or a methacrylic resin composition containing the methacrylic resin.   An optical part or an automobile part comprising the molded body according to claim 9 or 10.