JP2019099593A - Methacrylic resin, methacrylic resin composition, molded body, optical member and automobile component - Google Patents

Abstract

To provide a methacrylic resin of which color tone and transparency are improved without deteriorating low birefringence, and a methacrylic resin composition.SOLUTION: There is provided a methacrylic resin containing a structural unit (X) having a ring structure in a main chain, having (a) glass transition temperature (Tg) of over 120°C and 160°C or less, (b) absolute value of photoelastic coefficient of 3.0×10Paor less, and containing (c) an allyl compound of 10 mass.ppm to 2000 mass.ppm based on 100 pts.mass of the methacrylic resin.SELECTED DRAWING: None

Description

  The present invention relates to a methacrylic resin, a methacrylic resin composition, a molded body, an optical member and an automobile part.

  In recent years, methacrylic resins, in addition to their excellent transparency, surface hardness and the like, have small birefringence which is an optical property, and thus, for example, various optical products such as liquid crystal displays, plasma displays, organic EL displays Notable as an optical resin for optical materials such as optical disks, optical films, plastic substrates, etc. Flat panel displays such as LCD, small infrared sensors, fine optical waveguides, micro lenses, pickup lenses for DVD / BlueRay Disk handling short wavelength light Market is expanding significantly.

  In particular, a methacrylic resin having a ring structure in the main chain and a composition containing the methacrylic resin are known to have excellent performance in both heat resistance and optical properties (for example, a patent) The demand is rapidly expanding year by year). However, as described above, methacrylic resins having a ring structure in the main chain with improved heat resistance and optical properties sometimes become colored due to absorption of light in the visible light region due to the ring structure etc., or the transmittance decreases. There is a problem like that. Therefore, in order to obtain a methacrylic resin having a ring structure in its main chain with less coloring and high transparency, a method of reducing the unreacted cyclic monomer remaining in the methacrylic resin is disclosed.

  For example, Patent Document 2 uses a monomer component containing N-substituted maleimide (a) and methacrylic acid ester (b), supplies part of the monomer component to start polymerization, and then performs polymerization. In the production method in which the remainder of the monomer component is supplied halfway, the ratio of the 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 By controlling to be less than the ratio of N-substituted maleimide (a) in the total supply amount of the monomer component, the amount of remaining N-substituted maleimide monomer is reduced, and the heat resistance is excellent in transparency and little in coloration. It has been proposed to obtain an acrylic methacrylic resin.

  Further, Patent Document 3 discloses residual maleimide by causing an acidic substance to be present in a reaction system in a methacrylic acid ester-based monomer / maleimides monomer polymerization system using a sulfur-based chain transfer agent such as mercaptan. There has been proposed a method of reducing the coloration by reducing the analog monomers and the maleimide monomers generated by heating at the time of molding processing and the like.

International Publication No. 2011/149088 Japanese Patent Application Laid-Open No. 9-324016 JP 2001-233919 A

  However, in recent years, while its use extends from optical film applications to thick molded articles such as lenses and molded plates, even if it is a molded article having a long optical path length, it is less colored and has high transparency. It has been strongly desired to provide a methacrylic resin molding capable of expressing

Patent Documents 2 and 3 pay attention to N-substituted maleimide having strong coloring property as a monomer itself as a method of reducing coloring, and N-substituted maleimide remaining in methacrylic resin and heat history such as molding processing Methods have been proposed to solve the problem by reducing the amount of N-substituted maleimide formed.
However, as described above, for example, as a methacrylic resin to cope with the extension to a molded object application having a long optical path length, the amount of coloring N-substituted maleimide remaining is large, and as the improvement of color tone and transparency It turned out to be inadequate.

In order to improve the color tone and transparency of the methacrylic resin, it is necessary to sufficiently remove the remaining colored N-substituted maleimide.
However, in order to sufficiently remove the remaining colored N-substituted maleimide, it is necessary to carry out degassing at a higher temperature, and depending on the resin, the coloring due to the heat history becomes remarkable, which is not an effective solution There is a case.
Therefore, without degassing at a higher temperature, the coloring N-substituted maleimide and low molecular weight components that induce coloring side reactions are made colorless under milder conditions, and the color tone and transparency of the methacrylic resin are improved. Further improvement is strongly desired.

  Then, an object of this invention is to provide the methacrylic resin which improved color tone and transparency, and this methacrylic resin composition, without impairing low birefringence.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have less coloring and high transparency without impairing low birefringence by adding a compound having an allyl group to the polymerization solution. It has been found that a methacrylic resin having can be prepared.

That is, the present invention is as follows.
[1] A methacrylic resin containing a structural unit (X) having a ring structure in its main chain, and (a) having a glass transition temperature (Tg) of more than 120 ° C. and not more than 160 ° C. (b) absolute value of photoelastic coefficient Of not more than 3.0 × 10 ^-12 Pa ^-1 and (c) an allyl compound contained in an amount of 10 to 2000 mass ppm based on 100 parts by mass of the methacrylic resin. .
[2] The methacrylic resin according to the above [1], wherein the absolute value of the photoelastic coefficient is 2.0 × 10 ⁻¹² Pa ⁻¹ or less.
[3] The methacrylic resin according to the above [1], wherein the absolute value of the photoelastic coefficient is 1.5 × 10 ⁻¹² Pa ⁻¹ or less.
[4] The methacrylic resin according to the above [1], wherein the absolute value of the photoelastic coefficient is 1.0 × 10 ⁻¹² Pa ⁻¹ or less [5] The allyl compound is an allyl alkyl compound, an allyl aryl compound, and The methacrylic resin according to any one of the above [1] to [4], which is at least one selected from the group consisting of allyl ether compounds.
[6] The above [1], wherein the structural unit (X) is at least one selected from the group consisting of structural units derived from N-substituted maleimide monomers, glutarimide structural units, and lactone ring structural units. The methacrylic resin according to any one of [5].
[7] A methacrylic resin composition comprising the methacrylic resin according to any one of the above [1] to [6].
[8] A molded article comprising the methacrylic resin according to any one of [1] to [6] or the methacrylic resin composition according to [7].
[9] An optical member comprising the molded body according to the above [8].
[10] The optical member according to [9], which is a light guide plate.
[11] An automobile part comprising the molded body according to the above [10].

  According to the present invention, it is possible to provide a methacrylic resin having improved color tone and transparency, and the methacrylic resin composition without impairing low birefringence.

  Hereinafter, a mode for carrying out the present invention (hereinafter referred to as “the present embodiment”) will be described in detail, but the present invention is not limited to the following description, and within the scope of the gist thereof Various modifications are possible.

[Methacrylic resin]
The methacrylic resin in the present embodiment includes a structural unit (X) having a ring structure in the main chain and a structural unit derived from a methacrylic acid ester monomer. Examples of the structural unit (X) having a ring structure include at least one ring structure selected from the group consisting of structural units derived from N-substituted maleimide monomers, glutarimide structural units, and lactone ring structural units. .

  Hereinafter, each monomer structural unit is demonstrated.

-Structural unit derived from methacrylic acid ester monomer-
The structural unit derived from a methacrylic acid ester monomer is formed, for example, from a monomer selected from methacrylic acid esters shown below. Examples of methacrylic acid esters 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 2-phenoxyethyl, 3-phenylpropyl methacrylate, 2,4,6-tribromophenyl methacrylate and the like can be mentioned.
These monomers may be used alone or in combination of two or more.
Among the above-mentioned methacrylic acid esters, methyl methacrylate and benzyl methacrylate are preferable in that the transparency and weather resistance of the resulting methacrylic resin are excellent.
The structural unit derived from the methacrylic acid ester monomer may contain only one or two or more.

The content of a structural unit derived from a methacrylic acid ester monomer is a methacrylic resin from the viewpoint of sufficiently imparting heat resistance to a methacrylic resin by a structural unit (X) having a ring structure described later in the main chain. Is preferably 50 to 97% by mass, more preferably 55 to 97% by mass, still more preferably 55 to 95% by mass, still more preferably 60 to 93% by mass, particularly preferably 60 to 90% by mass. %.
In addition, content of the structural unit derived from a methacrylic acid ester monomer can be calculated | required by < ¹ > H-NMR measurement and < ¹³ > C-NMR measurement. ¹ H-NMR measurement and ¹³ C-NMR measurement can be performed, for example, at a measurement temperature of 40 ° C., using CDCl ₃ or DMSO-d ₆ as a measurement solvent.

  The structural unit (X) having a ring structure is described below.

-Structural unit derived from N-substituted maleimide monomer-
Next, structural units derived from N-substituted maleimide monomers are described.
The structural unit derived from the N-substituted maleimide monomer may be at least one selected from a monomer represented by the following formula (1) and / or a monomer represented by the following formula (2), Preferably, it is formed from both of the monomers 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、酸素原子、硫黄原子、炭素数１〜１２のアルキル基又は炭素数６〜１４のアリール基のいずれかを示す。
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 an oxygen atom Or a sulfur atom, an alkyl group having 1 to 12 carbon atoms, or an aryl group having 6 to 14 carbon atoms.
When R ² is an aryl group, R ² may contain halogen as a substituent.
In addition, 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１〜１２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、酸素原子、硫黄原子、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 a hydrogen atom, a cycloalkyl group having 3 to 12 carbon atoms, or an alkyl group having 1 to 12 carbon atoms, and R ⁵ and R ⁶ each independently represent a hydrogen atom, It represents any of an oxygen atom, a sulfur atom, an alkyl group having 1 to 12 carbon atoms, and an aryl group having 6 to 14 carbon atoms.

Specific examples are shown below.
Examples of the monomer represented by the formula (1) include N-phenylmaleimide, N-benzylmaleimide, N- (2-chlorophenyl) maleimide, N- (4-chlorophenyl) maleimide, and N- (4-bromo). Phenyl) maleimide, N- (2-methylphenyl) maleimide, N- (2-ethylphenyl) maleimide, N- (2-methoxyphenyl) maleimide, N- (2-nitrophenyl) maleimide, N- (2, 4 , 6-trimethylphenyl) maleimide, N- (4-benzylphenyl) maleimide, N- (2,4,6-tribromophenyl) maleimide, N-naphthylmaleimide, N-anthracenylmaleimide, 3-methyl-1 -Phenyl-1H-pyrrole-2,5-dione, 3,4-dimethyl-1-phenyl-1H-pyrrole-2,5- One, 1,3-diphenyl -1H- pyrrole-2,5-dione, 1,3,4-triphenyl -1H- pyrrole-2,5-dione, and the like.
Among these monomers, N-phenyl maleimide and N-benzyl maleimide are preferable from the viewpoint of excellent heat resistance of the resulting methacrylic resin and optical properties such as birefringence.
These monomers may be used alone or in combination of two or more.

Examples of the monomer represented by the formula (2) include N-methyl maleimide, N-ethyl maleimide, N-n-propyl maleimide, N-isopropyl maleimide, N-n-butyl maleimide, N-isobutyl maleimide, N-s-butyl maleimide, N-t-butyl maleimide, N-n-pentyl maleimide, N-n-hexyl maleimide, N-n-heptyl maleimide, N-n-octyl maleimide, N-lauryl maleimide, N-cyclopentyl Maleimide, 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-pyrrole-2,5-dione, 1-cyclohexyl-3, - diphenyl -1H- pyrrole-2,5-dione, and the like.
Among these monomers, N-methyl maleimide, N-ethyl maleimide, N-isopropyl maleimide, and N-cyclohexyl maleimide are preferable from the viewpoint that the weather resistance of the methacrylic resin is excellent, and low as recently required for optical materials N-cyclohexyl maleimide is particularly preferable because of its excellent hygroscopicity.
These monomers may be used alone or in combination of two or more.

In the methacrylic resin of the present embodiment, the combined use of the monomer represented by the formula (1) and the monomer represented by the formula (2) provides highly controlled birefringence characteristics. Particularly preferred is the ability to be expressed.
The molar ratio of the content (X1) of the structural unit derived from the monomer represented by the formula (1) to the content (X2) of the structural unit derived from the monomer represented by the formula (2), (X1 / X2) is preferably more than 0 and 15 or less, more preferably more than 0 and 10 or less.
When the molar ratio (X1 / X2) is in this range, the methacrylic resin of the present embodiment maintains transparency, is not accompanied by yellowing, and has good heat resistance and good without impairing the environmental resistance. Express photoelastic properties.

The content of the structural unit derived from the N-substituted maleimide monomer is not particularly limited as long as the composition to be obtained satisfies the range of the glass transition temperature of the present embodiment, but 100% by mass of a methacrylic resin Preferably, it is 5 to 40% by mass, more preferably 5 to 35% by mass.
When it is in this range, the methacrylic resin can obtain a more sufficient heat resistance improvement effect, and further, a more preferable improvement effect can be obtained with respect to the weather resistance, the low water absorption and the optical properties. When the content of the structural unit derived from the N-substituted maleimide monomer is 40% by mass or less, the reactivity of the monomer component decreases during the polymerization reaction, and the amount of unreacted monomer remains large. It is effective to prevent the physical properties of the methacrylic resin from being lowered due to

The methacrylic resin having a structural unit derived from the N-substituted maleimide monomer in the present embodiment can be copolymerized with the methacrylic acid ester monomer and the N-substituted maleimide monomer within the range not impairing the object of the present invention. May contain structural units derived from other monomers.
For example, as another copolymerizable monomer, aromatic vinyl; unsaturated nitrile; acrylic acid ester having a cyclohexyl group, benzyl group or alkyl group having 1 to 18 carbon atoms; glycidyl compound; unsaturated carboxylic acids Can be mentioned. Examples of the aromatic vinyl include styrene, α-methylstyrene, divinylbenzene and the like. Examples of the unsaturated nitrile include acrylonitrile, methacrylonitrile, ethacrylonitrile and the like. Moreover, methyl acrylate, an ethyl acrylate, a propyl acrylate, an isopropyl acrylate, a butyl acrylate etc. are mentioned as said acrylic ester. Moreover, as a glycidyl compound, glycidyl (meth) acrylate etc. are mentioned. Examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, and their half esters or anhydrides.
The structural units derived from the other copolymerizable monomers may have only one kind or two or more kinds.

The content of structural units derived from these other copolymerizable monomers is preferably 0 to 10% by mass, more preferably 0 to 9% by mass, based on 100% by mass of the methacrylic resin. Preferably, it is 0 to 8% by mass.
When the content of structural units derived from other monomers is in this range, it is preferable because the molding processability and mechanical properties of the resin can be improved without impairing the original effect of introducing a ring structure into the main chain.

In addition, the content of the structural unit derived from the N-substituted maleimide monomer and the content of the structural unit derived from another copolymerizable monomer are determined by ¹ H-NMR measurement and ¹³ C-NMR measurement. Can. ¹ H-NMR measurement and ¹³ C-NMR measurement can be performed, for example, at a measurement temperature of 40 ° C., using CDCl ₃ or DMSO-d ₆ as a measurement solvent.

-Glutarimide type structural unit-
Examples of methacrylic resins having a glutarimide structural unit in the main chain are, for example, JP-A-2006-249202, JP-A-2007-009182, JP-A-2007-009191, and JP-A-2011-186482. It is a methacrylic resin which has a glutar imide type | system | group structural unit described in Unexamined-Japanese-Patent No. 2012/114718 grade | etc., And can be formed by the method described in the said gazette.
The glutarimide-based structural unit constituting the methacrylic resin of the present embodiment may be formed after resin polymerization.
Specifically, the glutarimide structural unit may be represented by the following general formula (3).

上記一般式（３）において、好ましくはＲ⁷及びＲ⁸は、それぞれ独立して、水素又はメチル基であり、Ｒ⁹は、水素、メチル基、ブチル基、シクロヘキシル基のいずれかであり、より好ましくは、Ｒ⁷は、メチル基であり、Ｒ⁸は、水素であり、Ｒ⁹は、メチル基である。
グルタルイミド系構造単位は、単一の種類のみを含んでいてもよいし、複数の種類を含んでいてもよい。

In the above general formula (3), preferably R ⁷ and R ⁸ are each independently hydrogen or a methyl group, R ⁹ is any of hydrogen, a methyl group, a butyl group and a cyclohexyl group Preferably, R ⁷ is a methyl group, R ⁸ is hydrogen and R ⁹ is a methyl group.
The glutarimide-based structural unit may contain only a single type, or may contain a plurality of types.

In the methacrylic resin having a glutarimide structural unit, the content of the glutarimide structural unit is not particularly limited as long as it satisfies the preferable range of the glass transition temperature as the composition of the present embodiment, but the methacrylic resin The resin content is 100% by mass, preferably in the range of 5 to 70% by mass, and more preferably in the range of 5 to 60% by mass.
When the content of the glutarimide structural unit is in the above range, it is preferable because a resin having good moldability, heat resistance, and optical properties can be obtained.
In addition, content of the glutar imide type | system | group structural unit in methacrylic resin can be determined using the method of the above-mentioned patent document.

The methacrylic resin having a glutarimide structural unit may further contain an aromatic vinyl monomer unit, if necessary.
The aromatic vinyl monomer is not particularly limited, and examples thereof include styrene and α-methylstyrene, with styrene being preferred.

The content of the aromatic vinyl unit in the methacrylic resin having a glutarimide structural unit is not particularly limited, but is preferably 0 to 20% by mass, based on 100% by mass of the methacrylic resin having a glutarimide structural unit.
When the content of the aromatic vinyl unit is in the above range, it is possible to achieve both heat resistance and excellent photoelasticity, which is preferable.

-Lactone ring structural unit-
The methacrylic resin having a lactone ring structural unit in its main chain is, for example, disclosed in JP 2001-151814, JP 2004-168882, JP 2005-146084, JP 2006-96960, JP They can be formed by the methods described in JP-A-2006-171464, JP-A-2007-63541, JP-A-2007-297620, JP-A-2010-180305, and the like.

The lactone ring structural unit constituting the methacrylic resin of the present embodiment may be formed after resin polymerization.
The lactone ring structural unit in the present embodiment is preferably a six-membered ring because of excellent stability of the ring structure.
As a lactone ring structural unit which is a six-membered ring, for example, a structure represented by the following general formula (4) is particularly preferable.

上記一般式（４）において、Ｒ¹⁰、Ｒ¹¹及びＲ¹²は、互いに独立して、水素原子、又は炭素数１〜２０の有機残基である。
有機残基としては、例えば、メチル基、エチル基、プロピル基等の炭素数１〜２０の飽和脂肪族炭化水素基（アルキル基等）；エテニル基、プロペニル基等の炭素数２〜２０の不飽和脂肪族炭化水素基（アルケニル基等）；フェニル基、ナフチル基等の炭素数６〜２０の芳香族炭化水素基（アリール基等）；これら飽和脂肪族炭化水素基、不飽和脂肪族炭化水素基、芳香族炭化水素基における水素原子の一つ以上が、ヒドロキシ基、カルボキシル基、エーテル基、エステル基からなる群から選ばれる少なくとも１種の基により置換された基；等が挙げられる。

In the above general formula (4), R ¹⁰ , R ¹¹ and R ¹² are each independently a hydrogen atom or an organic residue having 1 to 20 carbon atoms.
Examples of the organic residue include saturated aliphatic hydrocarbon groups having 1 to 20 carbon atoms such as methyl, ethyl and propyl (such as alkyl groups); and non-C 2 to 20 carbons such as ethenyl and propenyl. Saturated aliphatic hydrocarbon group (alkenyl group, etc.); C6-20 aromatic hydrocarbon group such as phenyl group, naphthyl group etc. (aryl group etc.); these saturated aliphatic hydrocarbon groups, unsaturated aliphatic hydrocarbon And groups in which at least one hydrogen atom in the group or aromatic hydrocarbon group is substituted with at least one group selected from the group consisting of a hydroxy group, a carboxyl group, an ether group, and an ester group; and the like.

  The lactone ring structure is obtained, for example, by copolymerizing an acrylic acid-based monomer having a hydroxy group with a methacrylic acid ester monomer such as methyl methacrylate to form a hydroxy group and an ester group or a carboxyl group in a molecular chain. After introduction, it can be formed by causing dealcoholization (esterification) or dehydration condensation (hereinafter also referred to as “cyclization condensation reaction”) between these hydroxy group and ester group or carboxyl group.

  Examples of acrylic acid monomers having a hydroxy group used for polymerization include 2- (hydroxymethyl) acrylic acid, 2- (hydroxyethyl) acrylic acid, and alkyl 2- (hydroxymethyl) acrylate (for example, 2- (hydroxymethyl) acrylic acid). Methyl (hydroxymethyl) acrylate, ethyl 2- (hydroxymethyl) acrylate, isopropyl 2- (hydroxymethyl) acrylate, n-butyl 2- (hydroxymethyl) acrylate, t- 2- (hydroxymethyl) acrylate Butyl), alkyl 2- (hydroxyethyl) acrylate and the like, preferably 2- (hydroxymethyl) acrylic acid and alkyl 2- (hydroxymethyl) acrylate, which are monomers having a hydroxyalkyl moiety. , Particularly preferably 2- (hydroxymethyl) acrylic acid methyl , 2- (hydroxymethyl) acrylate.

The content of the lactone ring structural unit in the methacrylic resin having a lactone ring structural unit in the main chain is not particularly limited as long as it satisfies the range of the glass transition temperature preferable as the composition of the present embodiment, but the methacrylic resin It is preferable that it is 5-40 mass% with respect to 100 mass%, More preferably, it is 5-35 mass%.
When the content of the lactone ring structural unit is within this range, ring structure introduction effects such as solvent resistance improvement and surface hardness improvement can be exhibited while maintaining molding processability.
In addition, content of the lactone ring structure in methacrylic resin can be determined using the method of the above-mentioned patent document.

A methacrylic resin having a lactone ring structural unit in its main chain has a structural unit derived from the above-described methacrylic acid ester monomer and another monomer copolymerizable with an acrylic acid monomer having a hydroxy group. It may be
As such other copolymerizable monomers, for example, styrene, vinyl toluene, α-methylstyrene, α-hydroxymethylstyrene, α-hydroxyethylstyrene, acrylonitrile, methacrylonitrile, methallyl alcohol, ethylene Monomers having a polymerizable double bond, such as propylene, 4-methyl-1-pentene, vinyl acetate, 2-hydroxymethyl-1-butene, methyl vinyl ketone, N-vinylpyrrolidone, N-vinylcarbazole, etc. It can be mentioned.
These other monomers (constituent units) may have only one type or two or more types.

The content of structural units derived from these other copolymerizable monomers is preferably 0 to 20% by mass with respect to 100% by mass of the methacrylic resin, and from the viewpoint of weatherability, 10% by mass. It is more preferable that it be less than%, and it is further preferable that it be less than 7% by mass.
The methacrylic resin in the present embodiment may have only one type of the above-mentioned copolymerizable other monomer-derived structural unit, or may have two or more types.

  The methacrylic resin in the present embodiment preferably has at least one ring structural unit selected from the group consisting of a structural unit derived from an N-substituted maleimide monomer, a glutarimide structural unit, and a lactone ring structural unit, Among them, it is particularly preferable to have a structural unit derived from an N-substituted maleimide monomer, in particular, from the viewpoint of easily controlling optical properties such as photoelastic coefficient without blending other thermoplastic resins.

-Allyl compound-
The methacrylic resin in the present embodiment contains an allyl compound from the viewpoint of improving the color tone of the polymer.
The allyl compound is not particularly limited, and examples include allyl alkyl compounds, allyl aryl compounds, allyl ether compounds, allyl sulfide compounds, allyl amine compounds and the like. Specifically, it is an allyl compound described later with respect to the addition of the allyl compound in the method for producing a methacrylic resin.
These allyl compounds may contain one kind alone, or may contain two or more kinds in combination.

  The content of the allyl compound in the methacrylic resin of the present embodiment is 10 mass ppm or more and 2000 mass ppm or less, preferably 100 mass ppm or more and 1000 mass ppm or less, more preferably 200 parts by mass with respect to 100 parts by mass of the methacrylic resin. It is mass ppm or more and 600 mass ppm or less. If the content of the allyl compound falls within these ranges, the unreacted N-substituted maleimide monomer remaining in the methacrylic resin of the present embodiment, the N—H bond of the acrylamide group or the O— of the hydroxymethyl group Even if the H bond is desorbed during molding, it reacts with the residual allyl compound again, and the decoloring effect is maintained.

-Characteristics of methacrylic resin-
-Glass transition temperature-
The glass transition temperature (Tg) of the methacrylic resin in the present embodiment is more than 120 ° C. and 160 ° C. or less.
If the glass transition temperature of the methacrylic resin exceeds 120 ° C., the heat resistance necessary for optical components such as lens molded bodies in recent years, automobile parts such as in-vehicle displays, and film molded body optical films for liquid crystal displays can be made easier Can be obtained. The glass transition temperature (Tg) is more preferably 125 ° C. or more, and still more preferably 130 ° C. or more, from the viewpoint of dimensional stability at the operating environment temperature.
On the other hand, when the glass transition temperature (Tg) of the methacrylic resin is 160 ° C. or less, melt processing at an extremely high temperature can be avoided, thermal decomposition of a resin or the like can be suppressed, and a good product can be obtained.
The glass transition temperature (Tg) is preferably 150 ° C. or less for the reasons described above.
In addition, a glass transition temperature (Tg) can be determined by measuring based on JIS-K7121. Specifically, it can be determined by the method described in the examples below.

-Molecular weight and molecular weight distribution-
In the methacrylic resin in the embodiment, the weight average molecular weight (Mw) in terms of polymethyl methacrylate measured by gel permeation chromatography (GPC) is preferably in the range of 100,000 to 170,000, and more preferably 100. It is in the range of 1,000 to 150,000, more preferably in the range of 120,000 to 150,000. When the weight average molecular weight (Mw) is in the above range, the mechanical strength and the balance of fluidity are also excellent.

In addition, the weight average molecular weight (Mw), number average molecular weight (Mn), and Z average molecular weight (Mz) of methacrylic resin are measured by the following apparatus and conditions.
-Measuring device: gel permeation chromatography (HLC-8320 GPC) manufactured by Tosoh Corporation
·Measurement condition:
Column: One TSKguard column SuperH-H, two TSKgel SuperHM-M, and one TSKgel SuperH2500 are sequentially connected in series and used.
Column temperature: 40 ° C
Developing solvent: tetrahydrofuran, flow rate: 0.6 mL / min, and 2,6-di-t-butyl-4-methylphenol (BHT) as an internal standard is added at 0.1 g / L.
Detector: RI (differential refraction) detector Detection sensitivity: 3.0 mV / min Sample: 0.02 g of methacrylic resin in tetrahydrofuran 20 mL solution injection amount: 10 μL
Standard sample for calibration curve: The following 10 polymethyl methacrylates (manufactured by Polymer Laboratories; PMMA Calibration Kit M-M-10) having known monodispersed weight peak molecular weights and different molecular weights are 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 8 5,000
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 or the methacrylic resin is measured.
The weight average molecular weight (Mw), number average molecular weight (Mn), and Z average molecular weight (Mz) of the methacrylic resin and the methacrylic resin based on the calibration curves obtained by the measurement of the standard samples for calibration curve described above The molecular weight distribution (Mw / Mn) and (Mz / Mw) are determined using these values.

--Methanol insoluble matter--
The ratio of the amount of methanol insolubles of the methacrylic resin in the present embodiment to the total amount of 100% by mass of the amount of methanol insolubles and the amount of methanol solubles is preferably 95% by mass or more, more preferably It is 95.5% by mass or more, more preferably 96% by mass or more, still more preferably 96.5% by mass or more, particularly preferably 97% by mass or more, and most preferably 97.5% by mass It is above. By setting the ratio of the amount of the insoluble matter in methanol to 95% by mass or more, it is possible to suppress troubles during molding, such as cast roll contamination during film molding and generation of silver streaks during injection molding.
The methanol-insoluble and methanol-soluble components are reprecipitated by adding a methacrylic resin to a chloroform solution and then dropping the solution into a large excess of methanol, and the filtrate and the filtrate are separated, and then each is separated. Say what was obtained by drying.

  Specifically, it can be determined as follows. After 5 g of the methacrylic resin is dissolved in 100 mL of chloroform, the solution is put into a dropping funnel and added dropwise to 1 L of methanol being stirred using a stirrer over about 1 hour to perform reprecipitation. After the entire amount has been dropped, the mixture is allowed to stand for 1 hour, and suction filtration is performed using a membrane filter (T050A090C manufactured by Advantec Toyo Kaisha, Ltd.) as a filter. The filtrate is vacuum dried at 60 ° C. for 16 hours to make it insoluble in methanol. Also, the filtrate may be left in an eggplant-type flask after the solvent is removed using a rotary evaporator with a bath temperature of 40 ° C. and a degree of vacuum gradually lowered from the initial setting of 390 Torr to a final pressure of 30 Torr. The solution is collected and made soluble in methanol. Each of the mass of methanol insolubles and the mass of methanol solubles is weighed, and the ratio (mass) of the amount of methanol solubles to the total amount (100% by mass) of the amount of methanol solubles and the amount of methanol insolubles %) (Methanol soluble fraction) is calculated.

-Yellowness index (YI) and transmittance-
The methacrylic resin in the present embodiment has a yellowness index (YI) of 0 to 7, preferably 0.5 to 6, measured using a 10 cm optical path length cell for a methanol-insoluble 20 w / v% chloroform solution. More preferably, it is 0.8-5, More preferably, it is 1-4.
In addition, it is preferable that the transmittance at 680 nm of the methacrylic resin constituting the methacrylic resin molded body in the present embodiment is 90% or more and 91% or more, which is measured under the same conditions as those in the measurement of YI described above. Is more preferably 92% or more.
When the yellowness index (YI) or the transmittance is in this range, a molded article suitable for optical applications can be obtained. In addition, the addition of an allyl compound described below can be expected to reduce the YI of the methanol insoluble portion and improve the transmittance.

In addition, yellowness index (YI) and transmittance are solutions prepared by dissolving 20 w / v% chloroform solution (ie, 10 g of sample in chloroform to make 50 mL of solution) of methanol insoluble matter of methacrylic resin As a measurement sample. Ultraviolet-visible spectrophotometer (manufactured by Shimadzu Corporation, UV-2500PC), measurement wavelength 380 to 780 nm, slit width 2 nm, 10 cm path length cell with viewing angle 10 °, auxiliary illuminant C, reference object: chloroform Perform the transmittance measurement. Following the formula YI = 100 (1.2769X-1.0592Z) / Y according to JIS K 7373 using the XYZ color system
By this, YI (yellowness index) is calculated.
In addition, the transmittance (%) at a wavelength of 680 nm is also recorded under the same conditions as in the measurement of YI.

--- Photoelastic coefficient C _R ---
The absolute value of the photoelastic coefficient C _R of the methacrylic resin having a main chain in the ring structure of the present embodiment, 3.0 × is at 10 ^-12 Pa ^-1 or less, preferably 2.0 × 10 ^-12 Pa ^{- It is 1} or less, more preferably 1.5 × 10 ⁻¹² Pa ⁻¹ or less, still more preferably 1.0 × 10 ⁻¹² Pa ⁻¹ or less. The photoelastic coefficient is described in various documents (see, for example, Chemical Review, No. 39, 1998 (published by Society Publishing Center)), and is defined by the following formulas (i-a) and (i-b) 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 (i-a)
| Δn | = | nx−ny | (i−b)
( _Wherein , C _R is a photoelastic coefficient, σ _R is a tensile stress, | Δn | is an absolute value of birefringence, nx is a refractive index in the tensile direction, and ny is a direction perpendicular to the tensile direction in the plane Indicate the refractive index of
If the absolute value of the photoelastic coefficient C _R of the methacrylic resin of the present embodiment is 3.0 × 10 ⁻¹² Pa ⁻¹ or less, the light beam is relatively thin, and even in the case of an injection molded article having a long optical path length, An optical member having a high transmittance and little unevenness in luminance can be obtained even when used as a light guide plate.
Measurement of photoelastic coefficient C _R is a methacrylic resin, carried out by the pressed film with a vacuum compression molding machine. Specifically, it can be determined by the method described in the examples below.

[Method for producing methacrylic resin]
Hereinafter, the manufacturing method of methacrylic resin of this embodiment is demonstrated.

-Process for producing methacrylic resin containing structural unit derived from N-substituted maleimide monomer-
As a method for producing a methacrylic resin having a structural unit derived from an N-substituted maleimide monomer in the main chain, any polymerization method such as bulk polymerization, solution polymerization, suspension polymerization, precipitation polymerization and emulsion polymerization can be used. These are preferably suspension polymerization, bulk polymerization, solution polymerization, and more preferably solution polymerization.
In the manufacturing method in this embodiment, any of a batch polymerization method, a semi-batch method, and a continuous polymerization method can be used as a polymerization system, for example.
In the production method in the present embodiment, it is preferable to polymerize the monomer by radical polymerization.

  Hereinafter, as an example of a method for producing a methacrylic resin (hereinafter sometimes referred to as “maleimide copolymer”) having a structural unit derived from an N-substituted maleimide monomer, a radical method is applied batchwise using a solution polymerization method. The case of production by polymerization will be specifically described.

The polymerization solvent to be used is not particularly limited as long as it can increase the solubility of the maleimide copolymer obtained by the polymerization and appropriately maintain the viscosity of the reaction solution for the purpose of preventing gelation and the like.
Specific polymerization solvents include, for example, 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 It can be used.

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

  The polymerization temperature is not particularly limited as long as the polymerization proceeds, but it is preferably 50 to 200 ° C., more preferably 80 to 200 ° C. The temperature is more preferably 90 to 150 ° C, still more preferably 100 to 140 ° C, and still more preferably 100 to 130 ° C. The temperature is preferably 70 ° C. or higher from the viewpoint of productivity, and is preferably 180 ° C. or lower in order to suppress a side reaction during polymerization and obtain a polymer having a desired molecular weight and quality.

  The polymerization time is not particularly limited as long as the target polymerization conversion rate is satisfied, but it is preferably 0.5 to 15 hours, more preferably 2 to 12 hours, further preferably from the viewpoint of productivity and the like. 4 to 10 hours.

The polymerization conversion ratio at the end of polymerization of the methacrylic resin having a structural unit derived from an N-substituted maleimide monomer in the main chain of the present embodiment is not particularly limited, but is preferably 94.5% or more. Preferably they are 96.0% or more and 98.0% or less, More preferably, they are 96.5% or more and 97.5% or less.
Here, the polymerization conversion ratio is the monomer added to the polymerization system of a value obtained by subtracting the total mass of the monomer remaining at the end of the polymerization from the total mass of the monomers added into the polymerization system. Ratio to the total mass of Specifically, it can be determined by the method described in the examples below.

The amount of N-substituted maleimide monomer remaining in the solution after polymerization (the remaining amount of N-substituted maleimide) is preferably 100 to 7000 mass ppm or less, and 200 to 5000 mass ppm or less It is more preferable that it is 300-3000 mass ppm or less.
As the polymerization conversion rate is high and the remaining amount of N-substituted maleimide is small, the amount of monomers moving to the solvent recovery system is small, so the load on the purification system is reduced, and the unit consumption is reduced, which is economical.
However, if the polymerization conversion ratio is made too high or the residual amount of N-substituted maleimide is reduced too much by increasing the polymerization temperature or prolonging the polymerization time in the polymerization process, the amount of low molecular weight components having coloring properties, or methanol The amount of solubles increases, which may adversely affect color tone and moldability.
Therefore, it is preferable that the remaining N-substituted maleimide be decolorized by removal in the volatilization step described later or addition of an allyl compound.

  At the time of the polymerization reaction, polymerization may be carried out by adding a polymerization initiator or a chain transfer agent as necessary.

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, benzoylperoxide Organic peroxides such as oxides, t-butyl peroxyisopropyl carbonate, t-amyl peroxy-2-ethylhexanoate, t-amyl peroxy isononanoate, 1,1-di-t-butylperoxycyclohexane and the like; 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 parts by mass, when the total amount of the monomers used for polymerization is 100 parts by mass.

As a 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, etc. 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; and the like.
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 is 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 parts by mass, when the total amount of the 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, for example, using a dissolved oxygen meter DO meter B-505 (manufactured by Iijima Electronics Co., Ltd.).
As a method of reducing the concentration of dissolved oxygen, a method of bubbling an inert gas into the polymerization solution, an operation of pressurizing the inside of a container containing the polymerization solution to about 0.2 MPa with inert gas before polymerization and repeating the operation of releasing pressure are repeated. A method such as a method of passing an inert gas into a container containing a polymerization solution can be appropriately selected.

The method for recovering the polymer from the polymerization solution obtained by solution polymerization is not particularly limited, but, for example, poor solvents such as hydrocarbon solvents and alcohol solvents which do not dissolve the polymerization product obtained by polymerization The polymerization liquid is added in the presence of an excess amount, and then the treatment (emulsification and dispersion) is performed by a homogenizer, and the unreacted monomer is subjected to pretreatment such as liquid-liquid extraction and solid-liquid extraction, Alternatively, a method of separating from the polymerization solution; or a method of separating a polymerization solvent or an unreacted monomer via a process called a degassing step; and recovering a polymerization product;
Here, the volatilization step refers to a step of removing volatile components such as a polymerization solvent, residual monomers, reaction byproducts, etc. under heating and reduced pressure conditions.

As an apparatus used for the volatilization process, for example, a thin film evaporator such as a degassing apparatus comprising a tubular heat exchanger and a degassing tank; Weibren and EXEVA manufactured by Shinko Environmental Solutions Co., Ltd., Contra manufactured by Hitachi Ltd., and inclined wing contra; Examples thereof include a vented extruder having a residence time and a surface area sufficient to exhibit volatilization performance.
A degassing step using a degassing apparatus in which any two or more of these devices are combined can also be used.

  The processing temperature in the devolatilizer is preferably 150 to 350 ° C, more preferably 170 to 300 ° C, and still more preferably 200 to 280 ° C. By setting the temperature to the lower limit temperature or more, the residual volatile content can be suppressed, and by setting the temperature to the upper limit temperature or less, coloring and decomposition of the obtained methacrylic resin can be suppressed.

The degree of vacuum in the volatilization apparatus is preferably 10 to 500 Torr, more preferably 10 to 300 Torr. If the degree of vacuum exceeds 500 Torr, volatile components may easily remain. Conversely, if the degree of vacuum is less than 10 Torr, industrial implementation may become difficult.
The treatment time is appropriately selected depending on the amount of residual volatile component, but in order to suppress the coloring and decomposition of the resulting methacrylic resin, the shorter, the better.

The polymer recovered through the volatilization process is processed into pellets in a process called a granulation process.
In the granulation step, the molten resin is extruded into a strand from the porous die and processed into a pellet by a cold cut method, an airborne hot cut method, an underwater strand cut method and an under water cut method.

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

-Method for producing methacrylic resin containing glutarimide structural unit-
Examples of the method for producing a methacrylic resin having a glutarimide structural unit in the main chain include bulk polymerization, solution polymerization, suspension polymerization, precipitation polymerization, and emulsion polymerization, and preferably Suspension polymerization, bulk polymerization, solution polymerization, and more preferably solution polymerization.
In the manufacturing method in this embodiment, any of a batch polymerization method, a semi-batch method, and a continuous polymerization method can be used as a polymerization system, for example.
In the production method in the present embodiment, it is preferable to polymerize the monomer by radical polymerization.

The methacrylic resin having a glutarimide structural unit in its main chain is, for example, disclosed in JP-A-2006-249202, JP-A-2007-009182, JP-A-2007-009191, JP-A-2011-186482, International It is a methacrylic resin which has a glutar imide type | system | group structural unit described in Unexamined-Japanese-Patent No. 2012/114718 grade | etc., And can be formed by the method described in the said gazette.
Hereinafter, the case where it manufactures by radical polymerization by a batch type using solution polymerization method as an example of a manufacturing method of methacrylic resin which has a glutar imide type | system | group structural unit is demonstrated concretely.

  First, a (meth) acrylic acid ester polymer is produced by polymerizing a (meth) acrylic acid ester such as methyl methacrylate. When an aromatic vinyl unit is included in a methacrylic resin having a glutarimide structural unit, (meth) acrylic acid ester and aromatic vinyl (for example, styrene) are copolymerized to obtain (meth) acrylic acid ester-aromatic To produce a group vinyl copolymer.

Examples of the solvent used for the polymerization include aromatic hydrocarbons such as toluene, xylene and ethylbenzene; ketones such as methyl ethyl ketone and methyl isobutyl ketone; and the like.
These solvents may be used alone or in combination of two or more.
The amount of solvent at the time of polymerization is not particularly limited as long as the polymerization proceeds, precipitation of the copolymer and the monomer used does not occur at the time of production, and the amount can be easily removed. When the total amount is 100 parts by mass, it is preferably 10 to 200 parts by mass. The amount is more preferably 25 to 200 parts by mass, further preferably 50 to 200 parts by mass, and still more preferably 50 to 150 parts by mass.

The polymerization temperature is not particularly limited as long as the polymerization proceeds, but it is preferably 50 to 200 ° C., more preferably 80 to 200 ° C. The temperature is more preferably 90 to 150 ° C, still more preferably 100 to 140 ° C, and still more preferably 100 to 130 ° C. The temperature is preferably 70 ° C. or higher from the viewpoint of productivity, and is preferably 180 ° C. or lower in order to suppress a side reaction during polymerization and obtain a polymer having a desired molecular weight and quality.
The polymerization time is not particularly limited as long as the target conversion rate is satisfied, but it is preferably 0.5 to 15 hours, more preferably 2 to 12 hours, further preferably 4 from the viewpoint of productivity and the like. ~ 10 hours.

  At the time of the polymerization reaction, polymerization may be carried out by adding a polymerization initiator or a chain transfer agent as necessary.

Although it does not specifically limit as a polymerization initiator, For example, the polymerization initiator etc. which were disclosed by the preparation method of the methacrylic resin which has a structural unit derived from the said N-substituted maleimide monomer can be utilized.
These polymerization initiators 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 appropriately set according to the combination of monomers, reaction conditions and the like, and is not particularly limited, but the total amount of monomers used for polymerization is 100 parts by mass. It may be 0.01 to 1 part by mass, preferably 0.05 to 0.5 parts by mass.

As a chain transfer agent, a chain transfer agent used in general radical polymerization can be used. For example, the chain transfer agent disclosed in the method for preparing a methacrylic resin having a structural unit derived from the N-substituted maleimide monomer is used. it can.
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 is not particularly limited.
The addition amount of the chain transfer agent is not particularly limited as long as a desired degree of polymerization can be obtained under the polymerization conditions to be used, but preferably 100 parts by mass of the total amount of monomers used for the polymerization. When it is used, it may be 0.01 to 1 part by mass, preferably 0.05 to 0.5 parts by mass.

A suitable method of adding a polymerization initiator and a chain transfer agent in the polymerization step may be, for example, the method described in the method of preparing a methacrylic resin having a structural unit derived from the N-substituted maleimide monomer.
The dissolved oxygen concentration in the polymerization solution may be, for example, a value disclosed in the method for preparing a methacrylic resin having a structural unit derived from the N-substituted maleimide monomer.

  Next, an imidation reaction is performed by reacting an imidation agent with the (meth) acrylic acid ester polymer or the methacrylic acid ester-aromatic vinyl copolymer (imidation process). Thereby, a methacrylic resin having a glutarimide structural unit can be produced.

The imidization agent is not particularly limited as long as it can generate the glutarimide structural unit represented by the general formula (3).
Specifically, ammonia or a primary amine can be used as the imidization agent. Examples of the above primary amines include aliphatic hydrocarbon group-containing primary amines such as methylamine, ethylamine, n-propylamine, i-propylamine, n-butylamine, i-butylamine, tert-butylamine and n-hexylamine; Alicyclic hydrocarbon group-containing primary amines such as cyclohexylamine; and the like.
Among the above imidizing agents, ammonia, methylamine and cyclohexylamine are preferably used in terms of cost and physical properties, and it is particularly preferable to use methylamine.

  In the imidization step, the content of the glutarimide structural unit in the obtained methacrylic resin having the glutarimide structural unit can be adjusted by adjusting the addition ratio of the imidation agent.

The method for carrying out the above imidization reaction is not particularly limited, and a conventionally known method can be used. For example, the imidization reaction can be advanced by using an extruder or a batch reaction tank.
Although it does not specifically limit as said extruder, For example, a single screw extruder, a twin screw extruder, a multi-screw extruder etc. can be used.

Among them, it is preferable to use a twin-screw extruder. The twin screw extruder can promote the mixing of the raw material polymer and the imidizing agent.
As the twin-screw extruder, for example, non-engaging type same direction rotation type, meshing type same direction rotation type, non-engaging type opposite direction rotation type, meshing type opposite direction rotation type and the like can be mentioned.

The extruders exemplified above may be used alone or a plurality of them may be connected in series.
In addition, it is possible to attach a vent hole capable of reducing the pressure below atmospheric pressure to the extruder to be used, since it is possible to remove the reaction imidization agent, byproducts such as methanol, or monomers. preferable.

In producing a methacrylic resin having a glutarimide structural unit, in addition to the above-described imidization step, an esterification step can be included in which the carboxyl group of the resin is treated with an esterifying agent such as dimethyl carbonate. At that time, it is also possible to treat using a catalyst such as trimethylamine, triethylamine, tributylamine etc. in combination.
An esterification process can be advanced by using an extruder or a batch type reaction tank like the said imidation process, for example. In order to remove excess esterifying agent, by-products such as methanol, or monomers, it is preferable to equip a device to be used with a vent hole that can be depressurized below atmospheric pressure.

The methacrylic resin that has undergone the imidization process and, if necessary, the esterification process, is melted and extruded in the form of a strand from an extruder with a porous die attached, cold cut, airborne hot cut, underwater strand cut, under It is processed into pellets by a water cut method or the like.
Moreover, in order to reduce the number of foreign substances in the resin, the methacrylic resin is dissolved in an organic solvent such as toluene, methyl ethyl ketone, methylene chloride, etc., the obtained methacrylic resin solution is filtered, and then the organic solvent is removed. It is also preferred to use the method.

-Method for producing methacrylic resin containing lactone ring structural unit-
As a method for producing a methacrylic resin having a lactone ring structural unit in its main chain, a method of forming a lactone ring structure by a cyclization reaction after polymerization is used, but a solution using a solvent for promoting the cyclization reaction It is preferable to polymerize the monomer by radical polymerization in the polymerization method.
In the manufacturing method in this embodiment, any of a batch polymerization method, a semi-batch method, and a continuous polymerization method can be used as a polymerization system, for example.
The methacrylic resin having a lactone ring structural unit in its main chain is, for example, disclosed in JP 2001-151814, JP 2004-168882, JP 2005-146084, JP 2006-96960, JP They can be formed by the methods described in JP-A-2006-171464, JP-A-2007-63541, JP-A-2007-297620, JP-A-2010-180305, and the like.

Hereinafter, as an example of the method for producing a methacrylic resin having a lactone ring structural unit, a case of radical polymerization by batch polymerization using a solution polymerization method will be specifically described.
As a method of producing a methacrylic resin having a lactone ring structural unit, a method of forming a lactone ring structure by a cyclization reaction after polymerization is used, but in order to accelerate the cyclization reaction, solution polymerization using a solvent is preferable .

Examples of the solvent used for the polymerization include aromatic hydrocarbons such as toluene, xylene and ethylbenzene; ketones such as methyl ethyl ketone and methyl isobutyl ketone; and the like.
These solvents may be used alone or in combination of two or more.

  The amount of solvent at the time of polymerization is not particularly limited as long as polymerization proceeds and gelation can be suppressed, but, for example, 50 to 200 mass when the total amount of the monomers to be blended is 100 mass parts. It is preferable that it is a part, More preferably, it is 100-200 mass parts.

  In order to sufficiently suppress the gelation of the polymerization solution and promote the cyclization reaction after polymerization, the polymerization is carried out such that the concentration of the formed polymer in the reaction mixture obtained after the polymerization is 50% by mass or less Is preferred. Further, it is preferable to control the concentration to be 50% by mass or less by appropriately adding a polymerization solvent to the reaction mixture.

The method for appropriately adding the polymerization solvent to the reaction mixture is not particularly limited. For example, the polymerization solvent may be added continuously or the polymerization solvent may be added intermittently.
The polymerization solvent to be added may be only one single solvent or a mixed solvent of two or more.
The polymerization temperature is not particularly limited as long as the polymerization proceeds, but is preferably 50 to 200 ° C., more preferably 80 to 180 ° C. from the viewpoint of productivity.
The polymerization time is not particularly limited as long as the target conversion rate is satisfied, but it is preferably 0.5 to 10 hours, more preferably 1 to 8 hours from the viewpoint of productivity and the like.

  At the time of the polymerization reaction, polymerization may be carried out by adding a polymerization initiator or a chain transfer agent, if necessary.

Although it does not specifically limit as a polymerization initiator, For example, the polymerization initiator etc. which were disclosed by the preparation method of the methacrylic resin which has a structural unit derived from the said N-substituted maleimide monomer can be utilized.
These polymerization initiators 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 appropriately set according to the combination of monomers, reaction conditions and the like, and is not particularly limited, but the total amount of monomers used for polymerization is 100 parts by mass. It may be 0.05 to 1 part by mass.

As a chain transfer agent, a chain transfer agent used in general radical polymerization can be used. For example, the chain transfer agent disclosed in the method for preparing a methacrylic resin having a structural unit derived from the N-substituted maleimide monomer is used. it can.
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 is not particularly limited.
The addition amount of the chain transfer agent is not particularly limited as long as a desired degree of polymerization can be obtained under the polymerization conditions to be used, but preferably 100 parts by mass of the total amount of monomers used for the polymerization. When it is, it may be 0.05 to 1 part by mass.

  A suitable method of adding a polymerization initiator and a chain transfer agent in the polymerization step may be, for example, the method described in the method of preparing a methacrylic resin having a structural unit derived from the N-substituted maleimide monomer.

  The dissolved oxygen concentration in the polymerization solution may be, for example, a value disclosed in the method for preparing a methacrylic resin having a structural unit derived from the N-substituted maleimide monomer.

The methacrylic resin having a lactone ring structural unit in the present embodiment can be obtained by performing a cyclization reaction after the completion of the polymerization reaction. Therefore, it is preferable to use for a lactone cyclization reaction in the state containing a solvent, without removing a polymerization solvent from a polymerization reaction liquid.
The copolymer obtained by the polymerization undergoes a cyclocondensation reaction between a hydroxyl group (hydroxyl group) present in the molecular chain of the copolymer and an ester group by being heat-treated to give a lactone ring structure. Form
In the heat treatment for forming a lactone ring structure, a vacuum device for removing an alcohol which may be by-produced by cyclization condensation, a reaction device equipped with a degassing device, an extruder equipped with a degassing device, etc. can also be used .

When forming the lactone ring structure, if necessary, heat treatment may be performed using a cyclization condensation catalyst in order to accelerate the cyclization condensation reaction.
Specific examples of the cyclization condensation catalyst include, for example, methyl phosphite, ethyl phosphite, phenyl phosphite, dimethyl phosphite, diethyl phosphite, diphenyl phosphite, trimethyl phosphite, phosphite Phosphoric acid monoalkyl esters such as triethyl phosphate, dialkyl esters or triesters; methyl phosphate, ethyl phosphate, 2-ethylhexyl phosphate, octyl phosphate, isodecyl phosphate, lauryl phosphate, stearyl phosphate, phosphoric acid Isostearyl, dimethyl phosphate, diethyl phosphate, di-2-ethylhexyl phosphate, diisodecyl phosphate, dilauryl phosphate, distearyl phosphate, diisostearyl phosphate, trimethyl phosphate, triethyl phosphate, triisodecyl phosphate, Trilauryl phosphate, tristearyl phosphate, triisostearyl phosphate Phosphoric acid monoalkyl esters and the like, dialkyl ester or trialkyl esters; zinc acetate, zinc propionate, organozinc compounds such as octyl zinc; and the like.
These may be used alone or in combination of two or more.

The use amount of the cyclization condensation catalyst is not particularly limited, but is preferably 0.01 to 3 parts by mass, and more preferably 0.05 to 3 parts by mass with respect to 100 parts by mass of the methacrylic resin, for example. It is 1 part by mass.
When the amount of the catalyst used is 0.01 parts by mass or more, it is effective for improving the reaction rate of the cyclization condensation reaction, and when the amount of the catalyst used is 3 parts by mass or less, the obtained polymer is colored In addition, it is effective to prevent the polymer from being crosslinked and difficult to melt-mold.

The addition timing of the cyclization condensation catalyst is not particularly limited. For example, it may be added at the initial stage of the cyclization condensation reaction, may be added during the reaction, or both may be added. Good.
In carrying out the cyclization condensation reaction in the presence of a solvent, simultaneously carrying out the degassing is also preferably used.

The apparatus used when the cyclization condensation reaction and the degassing step are simultaneously performed is not particularly limited, but a devolatilizing apparatus comprising a heat exchanger and a devolatilizing tank, a vented extruder, a devolatilization apparatus Preferably, the apparatus and the extruder are arranged in series, and more preferably a vented twin-screw extruder.
The vented twin-screw extruder to be used is preferably a vented extruder having a plurality of vent ports.

The reaction temperature in the case of using a vented extruder is preferably 150 to 350 ° C., more preferably 200 to 300 ° C. If the reaction temperature is less than 150 ° C., the cyclocondensation reaction may be insufficient to increase the residual volatile content. Conversely, if the reaction temperature exceeds 350 ° C., coloring and decomposition of the resulting polymer may occur.
The degree of vacuum in the case of using a vented extruder is preferably 10 to 500 Torr, more preferably 10 to 300 Torr. If the degree of vacuum exceeds 500 Torr, volatile components may easily remain. Conversely, if the degree of vacuum is less than 10 Torr, industrial implementation may become difficult.

When carrying out the above-mentioned cyclization condensation reaction, it is also preferable to add an alkaline earth metal and / or an amphoteric metal salt of an organic acid at the time of granulation in order to deactivate the remaining cyclization condensation catalyst.
As an alkaline earth metal and / or amphoteric metal salt of an organic acid, for example, calcium acetyl acetate, calcium stearate, zinc acetate, zinc octylate, zinc 2-ethylhexylate and the like can be used.

After undergoing the cyclocondensation reaction step, the methacrylic resin is melted and extruded in the form of a strand from an extruder having a porous die attached thereto, using a cold cut method, an air hot cut method, an underwater strand cut method, and an under water cut method Process into pellets.
The lactonization to form the lactone ring structural unit described above may be performed after the production of the resin and before the production (described later) of the resin composition, and during the production of the resin composition, the resin and components other than the resin You may carry out in combination with the melt-kneading with.

-Color tone improvement by addition of allyl compound-
In the method for producing a methacrylic resin according to the present embodiment, from the viewpoint of improving the color tone of a polymer, a methacrylic acid ester monomer, and a monomer in which a structural unit (X) having a ring structure is formed in the main chain And cyclizing a resin containing a structural unit derived from a methacrylic acid ester monomer obtained by (co) polymerizing and / or (co) polymerizing one or more monomer components including After that, the allyl compound is added to and mixed with the resin-containing solution and / or the resin in a molten state.
Examples of allyl compounds to be added include allyl alkyl compounds, allyl aryl compounds, allyl ether compounds, allyl sulfide compounds, allyl amine compounds and the like.
These allyl compounds may contain one kind alone, or may contain two or more kinds in combination.

The alkyl group in the allyl alkyl compound is not particularly limited, and, for example, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, iso-butyl group, tert-butyl group, Aliphatic groups or alicyclic groups such as n-hexyl group, n-octyl group, n-decyl group, n-dodecyl group and cyclohexyl group can be mentioned.
As an aryl group in an allyl aryl compound, aryl groups, such as a phenyl group, a naphthyl group, a benzyl group, etc. or an arylalkyl group etc. are mentioned, for example.
The alkyl group and the aryl group may have a substituent such as a nitro group, an alkoxyl group, an alkyl group or a trifluoromethyl group.

Examples of allyl ether compounds include allyl propyl ether, allyl phenyl ether, diallyl ether and the like.
Examples of allyl sulfide compounds include allyl methyl sulfide, allyl ethyl sulfide, allyl propyl sulfide and the like.
Examples of the allylamine compound include tertiary amines having an allyl group, such as allyldimethylamine, allylethylmethylamine, diallylmethylamine and the like.

  Among them, the allyl compound is preferably at least one selected from the group consisting of an allyl alkyl compound, an allyl aryl compound, and an allyl ether compound, from the viewpoint of reducing the influence of the obtained resin on birefringence. Is an allyl alkyl compound or an aryl aryl compound.

  In addition, it is preferable that an allyl compound does not have a hydroxyl group. When the allyl compound has a hydroxyl group, the hydroxyl group remains in the resin, which causes coloring during degassing and molding processing. Further, in order to avoid the decrease in reactivity due to steric hindrance, it is preferable that hydrogen be substituted on the 1st and 2nd carbons of the allyl group.

In addition, from the viewpoint of not affecting the photoelasticity of the methacrylic resin, the absolute value of the photoelastic coefficient of the methacrylic resin obtained by adding the allyl compound is 0. 0 as compared with the case where the allyl compound is not added. It is preferable that it is an allyl compound that can be controlled to a difference of 5 × 10 ⁻¹² Pa ⁻¹ or less, and more preferably it is an allyl compound that can be controlled to a difference of 0.3 × 10 ⁻¹² Pa ⁻¹ or less.
The boiling point of the allyl compound is not particularly limited, but is preferably in the range of 90 to 300 ° C, more preferably in the range of 120 to 250 ° C, and still more preferably in the range of 150 to 200 ° C.

  The amount of addition of the allyl compound is preferably 0.10 to 5.0 parts by mass, more preferably 0.50 to 3.0 parts, based on 100 parts by mass of the total mass of the monomers used for the polymerization. Preferably, it is 1.0 to 2.0 parts by mass. If the addition amount is in these ranges, it is possible to sufficiently exhibit the color tone improvement effect of the manufactured methacrylic resin.

  The timing of addition of the allyl compound is after the structural unit (X) having a ring structure is formed in the main chain in the method for producing the methacrylic resin of the present embodiment described above, and the structural unit (X) having a ring structure It differs depending on the type of monomer forming the main chain.

  When the monomer forming the structural unit (X) having a ring structure in the main chain is an N-substituted maleimide monomer, it contains a methacrylic acid ester monomer and an N-substituted maleimide monomer After copolymerizing two or more types of monomer components, the resulting resin-containing resin containing a methacrylic resin in which a structural unit derived from the obtained N-substituted maleimide monomer is formed and / or in a molten state of the resin Add allyl compound and mix. Specifically, after completion of the polymerization, an allyl compound may be added to the polymerization solution, and stirring may be performed under heating, and when a methacrylic resin separated or recovered through a devolatilization step or the like is melt extruded by an extruder or the like Alternatively, the allyl compound may be added to the molten methacrylic resin and extruded.

  When the monomer that forms the structural unit (X) having a ring structure in the main chain is a monomer that forms a glutarimide structural unit, a resin containing a structural unit derived from a methacrylic acid ester monomer, After the cyclization reaction using an imidization agent, an allyl compound is added to and mixed with a solution containing the methacrylic resin in which the obtained glutarimide structural unit is formed and / or in the molten state, and mixed. Do.

  When the monomer that forms the structural unit (X) having a ring structure in the main chain is a monomer that forms a lactone ring structural unit, to form a lactone ring structural unit with the methacrylic acid ester monomer Derived from a methacrylic acid ester monomer obtained by copolymerizing two or more kinds of monomer components including a methacrylic acid ester monomer (for example, methyl 2- (hydroxymethyl) acrylate etc.) necessary for After a resin containing a structural unit is subjected to a cyclization reaction, an allyl compound is added to and mixed with a solution containing a methacrylic resin in which the obtained lactone ring structural unit is formed and / or in a molten state, and mixed. Do.

The allyl compound may be added to a solution containing a methacrylic resin containing a structural unit (X) having a ring structure in its main chain, or may be added to the molten methacrylic resin.
There is no particular limitation on the temperature of the solution containing the obtained resin to which the allyl compound is added or the temperature of the molten resin, as long as it is 100 ° C. or higher, but from the viewpoint of the reaction rate and the quality of the polymer 120 -270 degreeC is preferable, More preferably, it is 130-250 degreeC, More preferably, it is 140-230 degreeC.

  When an allyl compound is added to a solution containing a methacrylic resin and mixed, the stirring time is preferably 30 minutes or more, more preferably 2 hours or more. When it exists in these ranges, an allyl compound reacts rapidly and is advantageous in order to express a decoloring effect.

  When an allyl compound is added to and mixed with a methacrylic resin in a molten state, the screw rotation speed by an extruder or the like is preferably 50 rpm to 300 rpm, more preferably 70 rpm to 250 rpm, and still more preferably 100 rpm. More than 200 rpm. The pressure in the vent port is preferably reduced to 400 Torr or less, more preferably 200 Torr or less, and still more preferably 100 Torr or less. By mixing under these extrusion conditions, the allyl compound reacts rapidly, and byproducts and excess allyl compound can be removed, so that the decoloring effect can be efficiently exhibited.

  Although the mechanism by which the color tone is improved by the addition of the allyl compound is not clear, the coloration due to the ene reaction with the double bond site of the remaining unreacted colored N-substituted maleimide monomer and the N of the unreacted acrylamide group The suppression of the coloring side reaction at the time of degassing and / or at the time of molding is presumed by the addition of the -H bond and / or the O-H bond of the unreacted hydroxyalkyl group to the double bond of the allyl group.

[Methacryl-based resin composition]
The methacrylic resin composition of the present embodiment includes the above-described methacrylic resin containing the structural unit (X) having a ring structure in the main chain, and further various other types within the range that the effects of the present invention are not significantly impaired. You may contain the additive.

-Additives-
Additives are not particularly limited, but, for example, antioxidants, light stabilizers such as hindered amine light stabilizers, UV absorbers, mold release agents, other thermoplastic resins, paraffinic process oils, naphthenic processes Softeners / plasticizers such as oil, aromatic process oil, paraffin, organic polysiloxane, mineral oil, flame retardants, antistatic agents, inorganic fillers such as organic fibers, pigments such as iron oxide, glass fibers, carbon fibers And reinforcing agents such as metal whiskers, coloring agents; organic phosphorus compounds such as phosphorous esters, phosphonites, phosphoric esters, other additives, or mixtures thereof.

--Antioxidant--
The methacrylic resin composition of the present embodiment preferably contains an antioxidant in order to suppress deterioration or coloring during molding processing or during use.
Examples of the antioxidant include, but are not limited to, hindered phenol-based antioxidants, phosphorus-based antioxidants, sulfur-based antioxidants, and the like.
These antioxidants may be used alone or in combination of two or more.

The methacrylic resin of the present embodiment is suitably used in various applications such as melt extrusion, injection molding, film forming applications and the like. The heat history received during processing varies depending on the processing method, but from about several tens of seconds like an extruder, to something that receives several tens of minutes to several hours of heat history like molding processing of thick articles or sheet molding It is various. When subjected to a long heat history it is necessary to increase the amount of heat stabilizer added to obtain the desired heat stability.
Therefore, it is preferable to use a plurality of heat stabilizers in combination, for example, from phosphorus-based antioxidants and sulfur-based ones, from the viewpoint of preventing bleed out of the heat stabilizers and preventing sticking of the film to the roll during film formation. It is preferable to use at least one selected from antioxidants in combination with hindered phenol-based antioxidants.

Examples of hindered phenolic antioxidants 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- Tyl-4-hydroxy-m-tolyl) propionate], hexamethylene bis [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-xillin) 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.

Moreover, the hindered phenol type antioxidant as said antioxidant may use a commercially available phenol type antioxidant, and as such a commercially available phenol type antioxidant, what is limited to the following is mentioned. For example, Irganox 1010 (Irganox 1010: pentaerythritol tetrakis [3- (3,5-di-t-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 (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 AG, Irganox 3114 (Irganox 3114: 1,3,5-tris (3,5-di-t-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], ADEKA company), Adekastab AO-80 (3, 9-bis {2- [3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy oxy] -1,1-Dimethylethyl} -2,4,8,10-tetraoxaspiro [5.5] undecane, ADEKA Made, Sumilizer BHT (Sumilizer BHT, Sumitomo Chemical), Cyanox 1790 (Cyanox 1790, Cytec), Sumilizer GA-80 (Sumilizer GA-80, 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., Sumylizer GM (Sumilizer GM: 2-tert-butyl acrylate) -4-methyl-6- (2-hydroxy-3-tert-butyl-5-methylbenzyl) phenyl, manufactured by Sumitomo Chemical Co., Ltd., vitamin E (manufactured by Eisai Co., Ltd.), and the like.
Among these commercially available phenolic antioxidants, Irganox 1010, Adekastab AO-60, Adekastab AO-80, Irganox 1076, Sumilyzer GS, etc. are preferable from the viewpoint of the heat stability imparting effect of the resin.
These may be used alone or in combination of two or more.

  Moreover, as a phosphorus type antioxidant as said antioxidant, although it is not limited to the following, For example, a tris (2, 4- di- t- butylphenyl) phosphite, bis (2, 4- 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'-diyl bisphospho , 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 can be mentioned.

Furthermore, a commercially available phosphorus-based antioxidant may be used as the phosphorus-based antioxidant, and such a commercially available phosphorus-based antioxidant is not limited to the following, for example, Irgafos 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] dioxaphosphaphin-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, Adekastab 329K (ADK STAB-229K, manufactured by ADEKA) Adekastab PEP-36 (ADK STAB PEP-36, manufactured by ADEKA), Adekastab PEP-36A (ADK STAB PEP-36A, manufactured by ADEKA), Adekastab PEP-8 (ADK STAB PEP-8, manufactured by ADEKA), Adekastab HP-10 (ADK STAB HP-10 made by ADEKA), Adekastab 2112 (ADK STAB 2112 made by ADEKA), Adekastab 1178 (ADKA STAB 1178 made by ADEKA), Adekastub 1500 (ADK STAB 1500 made by ADEKA) Sandstab P-EPQ (Klariant ), Weston 618 (Weston 618, GE), Weston 619G (Weston 619G, GE), Ultranox 626 (Ultranox 6) 6, GE product, Sumilizer GP (Sumilizer GP: 4- [3-[(2,4,8,10-tetra-tert-butyldibenzo [d, f] [1,3,2] dioxaphosphepin ) -6-yloxy] propyl] -2-methyl-6-tert-butylphenol, manufactured by Sumitomo Chemical Co., Ltd., HCA (9,10-dihydro-9-oxa-10-phosphophenanthrene-10-oxide, manufactured by Sanko Co., Ltd.) Etc.).
Among these commercially available phosphorus-based antioxidants, Irgafos 168, Adekastab PEP-36, Adekastab PEP-36A, Adekastab HP from the viewpoint of the heat stability imparting effect of the resin and the combined effect with various antioxidants. -10, Adekastab 1178 is preferred, Adekastab PEP-36A, Adekastab PEP-36 are particularly preferred.
These phosphorus antioxidants may be used alone or in combination of two or more.

Further, the sulfur-based antioxidant as the above-mentioned antioxidant is not limited to the following, but, for example, 2,4-bis (dodecylthiomethyl) -6-methylphenol (IRGANOX 1726, BASF AG) 2,4-bis (octylthiomethyl) -6-methylphenol (IRGANOX 1520 L, manufactured by BASF), 2,2-bis {[3- (dodecylthio) -1-oxopropoxy] methyl} propane-1 2,3-diylbis [3-dodecylthio] propionate] (ADEKA STAB AO-412S, manufactured by Adeka), 2,2-bis {[3- (dodecylthio) -1-oxopropoxy] methyl} propane-1,3-diylbis [3 -Dodecylthio] propionate] (Cheminox PLS, Chemipro Chemical Industries, Ltd.), di (tridecyl) 3,3'-thiodipropionate (AO-503, ADEKA Co., Ltd.).
Among these commercially available sulfur antioxidants, Adekastab AO-412S and Cheminox PLS are preferable from the viewpoint of the heat stability imparting effect of the resin, the combined effect 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 any amount as long as the effect of improving the thermal stability can be obtained, and if the content is excessive, there is a possibility that problems such as bleeding out during processing may occur. The content 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 with respect to 100 parts by mass of the resin. The amount is preferably 0.01 to 0.8 parts by mass, particularly preferably 0.01 to 0.5 parts by mass.

  There is no particular limitation on the timing of adding the antioxidant, and the method of starting the polymerization after being added to the monomer solution before the polymerization, the method of using for the devolatilization process after being added and mixed to the polymer solution after the polymerization, devolatilization The method of pelletizing after adding to and mixing with the later polymer in the molten state, and adding and mixing when the pellets after degassing and pelletizing are again melt-extruded, etc. may be mentioned. Among these, from the viewpoint of preventing thermal deterioration and coloring in the volatilization process, after adding and mixing in the polymer solution after polymerization and adding an antioxidant before the volatilization process, it may be subjected to the volatilization process preferable.

--Hindered amine light stabilizers--
The methacrylic resin composition which comprises the methacrylic resin molded object of this embodiment can contain a hindered amine light stabilizer.
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 heterocyclic ring and a nonaromatic heterocyclic ring, and two or more ring structures in one compound are preferable. When they are contained, they may be identical to or different from each other.

  Examples of hindered amine light stabilizers include, but are not limited to, for example, specifically, 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 Mixtures 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 -Hex Polycondensate of methylenediamine and N- (2,2,6,6-tetramethyl-4-piperidyl) butylamine, poly [{6- (1,1,3,3-tetramethylbutyl) amino-1,3 5,5-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 undecane-3,9-diethanol with 2,2,6,6-tetramethyl-4-piperidiol and β, β, β ', β'-tetramethyl-2,4,8,10- Reaction product of tetraoxaspiro [5.5] undecane-3,9-diethanol, bis (1-undecanoxy-2,2,6,6-tetramethylpiperidin-4-yl) carbonate, 1,2,2,6 And 6-pentamethyl-4-piperidyl methacrylate, 2,2,6,6-tetramethyl-4-piperidyl methacrylate and the like.

  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. Butylmalonate, 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-piperi 2, 2, 6, 6--a reactant of β-, β, β ', β'- tetramethyl-2,4,8, 10-tetraoxaspiro [5.5] undecane-3,9-diethanol The reaction product of tetramethyl-4-piperidiol with β, β, β ', β'-tetramethyl-2,4,8,10-tetraoxaspiro [5.5] undecane-3,9-diethanol is preferred.

  The content of the hindered amine-based light stabilizer may be any amount as long as the effect of improving the light stability can be obtained, and 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 with respect to 100 parts by mass of the methacrylic resin. Still more preferably, it is 0.01 to 0.8 parts by mass, particularly preferably 0.01 to 0.5 parts by mass.

--UV absorber--
The methacrylic resin composition which comprises the methacrylic resin molded object of this embodiment can contain an ultraviolet absorber.
The UV absorber is not particularly limited, but is preferably a UV absorber having a maximum absorption wavelength of 280 to 380 nm. For example, benzotriazole compounds, benzotriazine compounds, benzophenone compounds, oxybenzophenone compounds And benzoate compounds, phenol compounds, oxazole compounds, cyanoacrylate compounds, benzoxazinone compounds and the like.

As benzotriazole compounds, 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-Tetrahydrophthalimidyl methyl) phenol, reaction product of methyl 3- (3- (2H-benzotriazol-2-yl) -5-t-butyl-4-hydroxyphenyl) propionate / polyethylene glycol 300 2- (2H-benzotriazol-2-yl) -6- (linear and branched 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) And 5- (1,1-dimethylethyl) -4-hydroxy-C7-9 side chain and linear alkyl esters.
Among these, benzotriazole compounds having a molecular weight of 400 or more are preferable. For example, in the case of a commercial product, Kemisorb (registered trademark) 2792 (manufactured by Chemiplo Chemical Industries, Ltd.) And the like (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 compounds. (Hydroxyphenyl) -1,3,5-triazine compounds, 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-butoxy) 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- 4- (4-hydroxy-4-butoxyphenyl)) Met Ciphenyl) -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, 2,4,4,6 6- Tris ( 2-hydroxy-4-benzyloxyphenyl) -1,3,5-triazine, 2,4,6-tris (2-hydroxy-4-ethoxyethoxyphenyl) -1,3,5-triazine, 2,4,4,6 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-i) 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- Tris (2-hydroxy-3-methyl-4- (1- (2-ethoxyhexyloxy) -1-oxopropan-2-yloxy) phenyl) -1,3,5-triazine and the like can be mentioned.

  As the benzotriazine compound, a commercially available product may be used. For example, Kemisorb 102 (manufactured by Chemipro Chemical Industries, Ltd.), LA-F70 (manufactured by ADEKA), LA-46 (manufactured by ADEKA), tinuvin 405 (BASF company) , Tinuvin 460 (BASF), Tinuvin 479 (BASF), Tinuvin 1577FF (BASF), and the like can be used.

  Among them, 2,4-bis (2,4-dimethylphenyl) -6- [2-hydroxy-4- (3-alkyloxy) is preferred because it has high compatibility with acrylic resins and is excellent in ultraviolet light absorption characteristics. -2-hydroxypropyloxy) -5-α-cumylphenyl] -s-triazine skeleton ("alkyloxy" means long-chain alkyloxy group such as octyloxy, nonyloxy, decyloxy etc. It can be used preferably.

  As the UV absorber, in particular, from the viewpoint of compatibility with the resin and volatilization during heating, benzotriazole compounds having a molecular weight of 400 or more and benzotriazine compounds are preferable, and heating during extrusion processing of the UV absorber itself From the viewpoint of the inhibition of decomposition by the compound, benzotriazine compounds are particularly preferable.

The melting point (Tm) of the ultraviolet absorber is preferably 80 ° C. or more, more preferably 100 ° C. or more, still more preferably 130 ° C. or more, and further preferably 160 ° C. or more. More preferable.
The weight loss of the ultraviolet absorber is preferably 50% or less, more preferably 30% or less, when the temperature is raised 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 different UV absorbers having different structures, UV light in a wide wavelength range can be absorbed.

  The content of the ultraviolet absorber is not particularly limited as long as it exerts the effects of the present invention without inhibiting the heat resistance, moist heat resistance, thermal stability, and moldability, but 100 mass of methacrylic resin The amount is preferably 0.1 to 5 parts by mass, preferably 0.2 to 4 parts by mass or less, more preferably 0.25 to 3 parts by mass, and still more preferably 0.3 to 3 parts by mass. If it is in this range, it is excellent in the balance of the ultraviolet ray absorbing performance, the moldability and the like.

--Mold release agent--
The methacrylic resin composition which comprises the methacrylic resin molded object of this embodiment can contain a mold release agent. Examples of the release agent include, but are not limited to, fatty acid esters, fatty acid amides, fatty acid metal salts, hydrocarbon lubricants, alcohol lubricants, polyalkylene glycols, carboxylic acid esters, and carbonization, for example. Examples thereof include paraffinic mineral oils of hydrogens.

The fatty acid ester usable as the releasing agent is not particularly limited, and conventionally known ones can be used.
Examples of the fatty acid ester include fatty acids having 12 to 32 carbon atoms such as lauric acid, palmitic acid, heptadecanoic acid, stearic acid, oleic acid, arachic acid, behenic acid, etc. Aliphatic alcohols and ester compounds with polyhydric aliphatic alcohols such as glycerin, pentaerythritol, dipentaerythritol, sorbitan; complex esters of fatty acids, polybasic organic acids and monohydric aliphatic alcohols or polyhydric aliphatic alcohols A compound etc. can be used.

Specific examples of the above fatty acid ester include cetyl palmitate, butyl stearate, stearyl stearate, stearyl citrate, glycerol monocaprylate, glycerol monocaprate, glycerol monolaurate, glycerol monopalmitate, glycerol dipalmitate, for example. Glycerin monostearate, glycerin distearate, glycerin tristearate, glycerin monooleate, glycerin dioleate, glycerin trioleate, glycerin monolinolate, glycerin monobehenate, glycerin mono 12-hydroxy stearate, glycerin di 12-hydroxy stearate, glycerin tri 12-hydroxy stearate, glycerin diacetomonostearate, glycerin citric acid fatty acid S Le, 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 esters can be used alone or in combination of two or more.
Commercially available products include, for example, RIKEN vitamin series Rikemar series, Poem series, Rike star series, Rike master series, Kao exell series, Reodore series, Exepearl series and Coconard series. In particular, Rikemar S-100, Rikemar H-100, Poem V-100, Rikemar B-100, Rikemar HC-100, Rikemar S-200, Poem B-200, Likestar EW-200, Likester EW-400, Exelles S -95, Reodore MS-50 and the like.

The fatty acid amide is also not particularly limited, and conventionally known ones can be used.
Examples of fatty acid amides include saturated fatty acid amides such as lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, hydroxystearic acid amide and the like; unsaturated fatty acid amides such as oleic acid amide, erucic acid amide and ricinoleic acid amide 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, etc. methylol stearic acid And methylol amides such as methylol behenic acid amide; methylene bis stearic acid amide, ethylene bis capric acid amide, ethylene bis lauric acid amide, ethylene bis stearic acid amide (ethylene bis stearyl amide), Tylenebisisostearic acid amide, ethylenebishydroxystearic acid amide, ethylenebisbehenic acid amide, hexamethylene bisstearic acid amide, hexamethylene bisbehenic acid amide, hexamethylene bishydroxystearic acid amide, N, N'-distearyl adipic acid Amide, saturated fatty acid bisamide such as N, N'-distearyl sebacic acid amide; ethylene bis oleic acid amide, hexamethylene bis oleic acid amide, N, N'-dioleyl adipic acid amide, N, N'-dioleyl sebacine Examples thereof include unsaturated fatty acid bisamides such as acid amides; and aromatic bisamides such as m-xylylene bisstearic acid amide and N, N'-distearyl isophthalic acid amide.
These fatty acid amides can be used alone or in combination of two or more.
As a commercial item, for example, Diamid series (made by Nippon Kasei Chemical Co., Ltd.), Amide series (made by Nippon Kasei Chemical Co., Ltd.), Nikka Amide series (made by Nippon Kasei Chemical Co., Ltd.), methylol amide series, bis Amide series, Sripax series Manufactured by Kao Co., Ltd., Kao Wax Series (manufactured by Kao Corp.), fatty acid Amide Series (manufactured by Kao Corp.), ethylenebisstearic acid amides (manufactured by Dainichi Chemical Co., Ltd.), and the like.

The fatty acid metal salt refers to a metal salt of a higher fatty acid, such as 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, lead dibasic stearate, lead naphthenate, calcium 12-hydroxystearate, lithium 12-hydroxystearate, etc. Among them, calcium stearate, magnesium stearate and zinc stearate are particularly preferable because the processability of the obtained transparent resin composition is excellent and the transparency becomes extremely excellent.
Examples of commercially available products include SZ series, SC series, SM series, and SA series manufactured by Sakai Chemical Industry Co., Ltd., as an example.
It is preferable that content in the case of using the said fatty-acid metal salt is 0.2 mass% or less with respect to 100 mass% of methacrylic resin compositions from a viewpoint of transparency maintenance.

  The above release agents may be used alone or in combination of two or more.

  As the release agent to be used, one having a decomposition start temperature of 200 ° C. or higher is preferable. Here, the decomposition initiation temperature can be measured by a 1% mass loss temperature by TGA.

  The content of the release agent may be any amount that can obtain the effect as a release agent, and if the content is excessive, problems such as occurrence of bleed out during extrusion and extrusion failure due to slip of screw occur. It 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 with respect to 100 parts by mass of the methacrylic resin. 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, the decrease in transparency due to the addition of the release agent is suppressed, and there is a tendency to suppress mold release failure during injection molding and sticking to a metal roll during sheet molding, preferable.

--Other thermoplastic resin--
The methacrylic resin composition that constitutes the methacrylic resin molded article of the present embodiment is a thermoplastic resin other than the methacrylic resin for the purpose of adjusting birefringence and improving flexibility without impairing the object of the present invention. It can also contain a resin.

As other thermoplastic resins, for example, polyacrylates such as polybutyl acrylate; polystyrene, styrene-methyl methacrylate copolymer, styrene-butyl acrylate copolymer, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene Styrene-based polymers such as block copolymers; furthermore, 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 described in JP-A No. 60-17406 and JP-A-8-245854; and those described in WO 2014-002491. And methacrylic rubber-containing graph / copolymer particles obtained by multi-stage polymerization; It is.
Among these, from the viewpoint of obtaining good optical properties and mechanical properties, a composition compatible with a styrene-acrylonitrile copolymer or a methacrylic resin containing a structural unit (X) having a ring structure in its main chain The rubber-containing graft copolymer particle which has the graft part which becomes in the surface layer is preferable.

  As an average particle diameter of the above-mentioned acrylic rubber particles, methacrylic rubber-containing graph / copolymer particles, and rubber polymers, the impact strength, optical properties and the like of the film obtained from the composition of the present embodiment are improved. Therefore, the thickness is preferably 0.03 to 1 μm, and 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, based on 100 parts by mass of the methacrylic resin.

[Method for producing methacrylic resin composition]
The method for producing the methacrylic resin composition of the present embodiment is not particularly limited as long as a composition satisfying the requirements of the present invention can be obtained. For example, the method of knead | mixing using kneading machines, such as an extruder, a heating roll, a kneader, a roller mixer, and a Banbury mixer, is mentioned. Among them, kneading by 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 as a standard, it is in the range of 140 to 300 ° C., preferably in the range of 180 to 280 ° C. Moreover, it is preferable to provide a vent hole in the extruder for the purpose of reducing volatile matter.

Here, in the methacrylic resin composition according to the present embodiment, the amount of the remaining solvent (the amount of the remaining solvent) is preferably less than 1000 mass ppm, more preferably less than 800 mass ppm, and still more preferably 700 mass ppm Less than.
Here, the remaining solvent refers to the polymerization solvent (except for alcohols) used at the time of polymerization, and the solvent used at the time of dissolving the resin obtained by the polymerization again and forming it into a solution. Examples of polymerization solvents 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; Examples of the solvent used for re-dissolution include toluene, methyl ethyl ketone, methylene chloride and the like.

In the methacrylic resin composition according to this embodiment, the amount of remaining alcohol (the amount of remaining alcohol) is preferably less than 500 mass ppm, more preferably less than 400 mass ppm, and still more preferably less than 350 mass ppm. .
Here, the remaining alcohol refers to the alcohol by-produced by the cyclization condensation reaction, and specific examples thereof include aliphatic alcohols such as methanol, ethanol and isopropanol.

  The amount of residual solvent and the amount of residual alcohol can be measured by gas chromatography.

  Moreover, when using the methacrylic resin composition of this embodiment for a film use etc., in order to reduce a foreign material, a polymerization reaction process, a liquid-liquid separation process, a liquid-solid separation process, a devolatilization process, granulation In any one or more steps of the process and the forming process, for example, a sintered filter with a filtration accuracy of 1.5 to 20 μm, a pleated filter, a leaf disc type polymer filter or the like is used by adding to a filtration device Is also a preferred method.

In any of the methods selected, it is preferable to prepare the composition while reducing oxygen and water as much as possible.
For example, the dissolved oxygen concentration in the polymerization solution in solution polymerization is preferably less than 300 ppm in the polymerization step, and in the preparation method using an extruder etc., the oxygen concentration in the extruder is less than 1% Preferably less than 0.8% by volume. The water content of the methacrylic resin is preferably adjusted to 1000 mass ppm or less, more preferably 500 mass ppm or less.
Within these ranges, it is relatively easy to prepare a composition meeting the requirements of the present invention, which is advantageous.

Glass transition temperature (Tg) for the methacrylic resin composition, the ratio of the amount of methanol solubles to the total amount of methanol solubles and the amount of methanol insolubles relative to 100% by mass, yellowness index of methanol insolubles ( YI), 680 nm transmittance, Z average molecular weight (Mz), weight average molecular weight (Mw), number average molecular weight (Mn), photoelastic coefficient C _R may be the same as described above for methacrylic resin.

-Method for producing methacrylic resin molding-
The methacrylic resin molded article in the present embodiment is formed by molding the above-mentioned methacrylic resin or the above-mentioned methacrylic resin composition. The method for producing the methacrylic resin molded product is not particularly limited, and various molding methods such as extrusion molding, injection molding, compression molding, calendar molding, inflation molding, hollow molding and the like can be used.
Surface functionalization treatments such as antireflection treatment, transparent conductive treatment, electromagnetic wave shielding treatment, gas barrier treatment and the like can also be further performed on various molded articles using the methacrylic resin of the present embodiment or the resin composition thereof.

-Characteristics of methacrylic resin moldings-
It is preferable that YI in 80 mm of optical path lengths is 0-35, More preferably, it is 1-30, More preferably, the methacrylic resin molded object in this embodiment is 2-30. The Y value at an optical path length of 80 mm is preferably 60 to 95, more preferably 65 to 93, and still more preferably 68, measured under the same conditions as in the measurement of YI described above as an index of luminous transmittance. -90. When the YI or Y value at an optical path length of 80 mm is in this range, it is possible to obtain a color tone and transparency suitable for use as a molded product of a long light path such as a light guide plate.
In addition, YI and Y value in 80 mm of optical path lengths can be measured by the method of the below-mentioned Example description.

-Application of methacrylic resin molding-
Although it does not specifically limit as a use of a methacrylic resin molded object, For example, Use to household goods, OA apparatus, AV apparatus, battery electric equipment, lighting equipment, auto parts, housings, sanitary such as sanitary ware substitutes, optical parts etc. Can be mentioned.
Examples of automobile parts include tail lamps, meter covers, headlamps, light guide bars, lenses, and front plates of car navigation systems.
Optical components include light guide plates used for displays such as liquid crystal displays, plasma displays, organic EL displays, field emission displays, and rear projection televisions, diffusers, polarizing plate protective films, quarter wave plates, half wave plates And a viewing angle control film, a retardation film such as a liquid crystal optical compensation film, a display front plate, a display substrate, a lens, a touch panel and the like, and it can be suitably used as a transparent substrate used for solar cells. In addition, in the field 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, LEDs lenses, lens covers, etc. Can also be used.
Moreover, it can also be used as a modifier of other resin.

  Hereinafter, the contents of the present invention will be specifically described with reference to examples and comparative examples. The present invention is not limited to the following examples.

<1. Measurement of polymerization conversion rate>
A part of the polymerization solution is taken, the amount of monomers remaining in this polymerization solution sample is dissolved in chloroform to prepare a 5% by mass solution, and n-decane is added as an internal standard substance, The concentration of the monomer remaining in the sample was measured using gas chromatography (GC-2010, manufactured by Shimadzu Corporation) to determine the total mass (a) of the monomer remaining in the polymerization solution. Then, the total mass (a), the total mass (b) when it is assumed that all the monomers added up to the time when the sample was collected remained in the polymerization solution, and From the total mass of the monomer (c), the polymerization conversion (%) was calculated by the formula (ba) / c × 100.

<2. Determination of the amount of added allyl compound remaining in the pellet>
The pellet is collected and weighed, dissolved in chloroform to prepare a 5% by mass solution, n-decane is added as an internal standard substance, and gas chromatography (GC-2010, manufactured by Shimadzu Corporation) is used to obtain the following: The measurement was made under the conditions and determined.
Detector: FID
Column used: ZB-1
Measurement conditions: After holding for 5 minutes at 45 ° C., raise the temperature to 300 ° C. at a temperature rising rate of 20 ° C./min, and then hold for 15 minutes

<3. Glass transition temperature>
The glass transition temperature (Tg) (° C.) of the methacrylic resin was measured in accordance with JIS-K7121.
First, about 10 mg of each of four points (four points) were cut out as test pieces from a sample conditioned (set at 23 ° C. for one week) in a standard state (23 ° C., 65% RH).
Next, using a differential scanning calorimeter (PerkinElmer Japan Ltd. Diamond DSC) under conditions of nitrogen gas flow rate 25 mL / min, the temperature rises from room temperature (23 ° C) to 200 ° C. at 10 ° C./min. Warm (primary temperature rise) and hold at 200 ° C for 5 minutes to completely thaw the sample, then lower the temperature from 200 ° C to 40 ° C at 10 ° C / minute, hold at 40 ° C for 5 minutes, and Of the DSC curves drawn during the temperature rise again (secondary temperature rise) under the above temperature rise conditions, it is equidistant along the vertical axis from the step change partial curve at the second temperature rise and each baseline extension line The point of intersection with a certain straight line (midpoint glass transition temperature) was measured as the glass transition temperature (Tg) (° C.). Four points were measured per sample, and the arithmetic mean of four points (rounded off after the decimal point) was taken as the measured value.

<4. Measurement of photoelastic coefficient C _R >
The methacrylic resin obtained in Production Examples and Production Comparative Examples was used as a press film by using a vacuum compression molding machine to obtain a measurement sample.
As specific sample preparation conditions, after preheating for 10 minutes under reduced pressure (about 10 kPa) at 260 ° C. using a vacuum compression molding machine (SFV-30 type, manufactured by Shinto Metal Industry Co., Ltd.), the resin is 260 ° C., It was compressed for 5 minutes at about 10 MPa, and after reducing pressure and releasing pressure, it was transferred to a cooling compression molding machine for cooling and solidification. After curing the obtained press film in a constant temperature and humidity chamber adjusted to 23 ° C. and a humidity of 60% for 24 hours or more, a test piece for measurement (thickness: about 150 μm, width: 6 mm) was cut out.
The photoelastic coefficient C _R (Pa ⁻¹ ) was measured using a birefringence measurement device described in detail in Polymer Engineering and Science 1999, 39, 2349-2357.
Similarly, a film-like test piece was placed in a film tensioner (made by Imoto Machinery Co., Ltd.) installed in a constant temperature and humidity chamber so as to be 50 mm between the chucks. Next, the device is placed so that the laser beam path of the birefringence measuring device (Retsu-100, manufactured by Otsuka Electronics Co., Ltd.) is located at the center of the film, and the strain rate 50% / min (chuck: 50 mm, chuck moving speed: The birefringence of the test piece was measured under tensile stress at 5 mm / min.
From the relationship between the absolute value (| Δn |) of birefringence and the tensile stress (σ _R ) obtained by measurement, the slope of the straight line is determined by the least squares approximation, and the photoelastic coefficient (CR) (Pa ⁻¹ ) is calculated did. For the calculation, data with an extension stress of 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 plane perpendicular to the stretching direction)

<Measurement of color tone of 5.80 mm molded piece>
Using a methacrylic resin, a molding temperature of 250 ° C. and a mold temperature of 90 ° C. by an injection molding machine (AUTO SHOT C Series MODEL 15A, manufactured by FANUC Co., Ltd.), thickness 3 mm × width 12 mm × length A 124 mm strip-shaped piece was produced.
Thereafter, the obtained molded piece is cut to 80 mm in the longitudinal direction, and the molded piece is manufactured at a rotation speed of the cutter of 8500 rpm and at a feed speed of 1 m / min using a polishing machine (Megaro Technica Co., Ltd., manufactured by PREMIERE). Polished both end faces perpendicular to the longitudinal direction of.
Using a color difference meter (COH 300A, manufactured by Nippon Denshoku Industries Co., Ltd.), place the polished molded piece so that the polished end face is perpendicular to the light source, and use a C light source with a light path length of 80 mm in 2 ° view YI and Y value as an index of luminous transmittance were measured.

[material]
The raw materials used in the following production examples and production comparative examples are shown below.
[[Monomer]]
Methyl methacrylate (MMA): manufactured by Asahi Kasei Co., Ltd. N-phenylmaleimide (phMI): manufactured by Nippon Shokubai Co., Ltd. N-cyclohexyl maleimide (chMI): manufactured by Nippon Shokubai Co., Ltd. Styrene: manufactured by Asahi Kasei Corp. Hydroxymethyl) methyl acrylate (MHMA): Combi Bloks · monomethylamine: Mitsubishi Gas Chemical Inc. [[polymerization initiator]]
T-Butylperoxy-2-ethylhexanoate: "Perbutyl O" manufactured by NOF Corporation
1,1-di (t-amylperoxy) cyclohexane: "RUPEROX 531" manufactured by Arkema Yoshitomi Co., Ltd.
T-amyl peroxy isononanoate: "RUPEROX 570" manufactured by Arkema Yoshitomi Co., Ltd.
[[Chain transfer agent]]
N-Octyl mercaptan: manufactured by Kao Corporation n-dodecyl mercaptan: manufactured by Kao Corporation [[allyl compound]]
・ Allyl cyclohexane (boiling point 153 ° C.): made by Tokyo Chemical Industry Co., Ltd. ・ Allyl benzene (boiling point 155 ° C.): Tokyo Chemical Industry Co., Ltd. made by diallyl ether (boiling point 94 ° C.) catalyst]]
Stearyl phosphate / distearyl phosphate mixture: manufactured by Sakai Chemical Industry Co., Ltd.

  Hereinafter, the manufacturing method of the methacrylic resin of an Example and a comparative example is demonstrated concretely.

Example 1
445.5 kg of MMA, 44.0 kg of phMI, 60.5 kg of chMI, and 0.55 kg of m-Xy weighing 0.55 kg of chain transfer agent n-octylmercaptan are added to a 1.25 m ³ reactor equipped with a jacket temperature controller and stirring blades Stir to obtain a mixed monomer solution.
The solution in the reactor was bubbled with nitrogen at a rate of 30 L / min for 1 hour to remove dissolved oxygen. After that, steam was blown into the jacket to raise the solution temperature in the reactor to 130 ° C. and 1.10 kg of t-butylperoxy-2-ethylhexanoate was dissolved in 4.9 kg of mX y while stirring at 50 rpm. The polymerization was initiated by adding a polymerization initiator solution at a rate of 1 kg / hour for 6 hours. During polymerization, the solution temperature in the reactor was controlled at 130 ± 2 ° C. by temperature control with a jacket.
The polymer solution was sampled 3.3 hours, 6 hours, and 8 hours (at the end of polymerization) after initiation of polymerization, and analysis of the polymerization conversion rate was carried out from the concentration of the remaining monomer. It was 84.9% after 3 hours, 96.7% after 6 hours, and 96.8% after 8 hours.
After 8 hours had elapsed from the start of polymerization, a polymerization solution containing a methacrylic resin having a ring structure in its main chain was obtained. To this polymerization solution, 25.3 kg of allylcyclohexane was added, and the solution temperature was heated to 145 ° C. and stirred for 2.5 hours.
This polymerization solution was supplied to a concentration device consisting of a tubular heat exchanger preheated to 170 ° C. and a vaporization tank to increase the concentration of the polymer contained in the solution to 70% by mass. The obtained polymerization solution was supplied to a thin film evaporator having a heat transfer area of 0.2 m ² to carry out devolatilization. The temperature in the apparatus at this time is 280 ° C., supply amount 30 L / hr, rotation speed 400 rpm, vacuum degree 30 Torr, and the polymer after volatilization is pressurized by a gear pump and extruded from a strand die. Thus, a methacrylic resin having an N-substituted maleimide structural unit was obtained.

Example 2
After completion of the polymerization, methacrylic resin pellets were obtained in the same manner as in Example 1 except that the added allylcyclohexane was changed to 16.5 kg. Physical properties are shown in Table 1.

[Example 3]
After completion of the polymerization, methacrylic resin pellets were obtained in the same manner as in Example 1 except that the added allylcyclohexane was changed to 14.3 kg. Physical properties are shown in Table 1.

Example 4
After completion of the polymerization, methacrylic resin pellets were obtained in the same manner as in Example 1 except that the amount of allylcyclohexane added was changed to 10.5 kg. Physical properties are shown in Table 1.

[Example 5]
After completion of the polymerization, methacrylic resin pellets were obtained in the same manner as in Example 1 except that the amount of allylcyclohexane added was changed to 6.6 kg. Physical properties are shown in Table 1.

[Example 6]
After completion of the polymerization, methacrylic resin pellets were obtained in the same manner as in Example 1 except that the amount of allylcyclohexane added was changed to 5.0 kg. Physical properties are shown in Table 1.

[Example 7]
After completion of the polymerization, methacrylic resin pellets were obtained in the same manner as in Example 1 except that the amount of allylcyclohexane added was changed to 3.9 kg. Physical properties are shown in Table 1.

[Example 8]
After completion of the polymerization, methacrylic resin pellets were obtained in the same manner as in Example 1 except that the amount of allylcyclohexane added was changed to 1.7 kg. Physical properties are shown in Table 1.

[Example 9]
After completion of the polymerization, methacrylic resin pellets were obtained in the same manner as in Example 1 except that the allyl compound to be added was allyl benzene and the weight was changed to 14.3 kg. Physical properties are shown in Table 1.

[Example 10]
After completion of the polymerization, methacrylic resin pellets were obtained in the same manner as in Example 1 except that the allyl compound to be added was diallyl ether, the weight was 25.3 kg, and the solution temperature at stirring after addition was changed to 120 ° C. Physical properties are shown in Table 1.

[Example 11]
Weigh 400.3 kg of MMA, 100.2 kg of styrene, 0.396 kg of n-dodecyl mercaptan (equivalent to 800 mass ppm based on the total mass of all monomers added to the polymerization system), 500.4 kg of toluene and measure the temperature by the jacket The mixture was added to a 1.25 m ³ reactor equipped with a control device and a stirring blade and stirred to obtain a mixed monomer solution.
The solution in the reactor was then bubbled with nitrogen at a rate of 30 L / min for 1 hour to remove dissolved oxygen.
Thereafter, steam is blown into the jacket to raise the solution temperature in the reactor to 120 ° C., and 0.253 kg of 1,1-di (t-amylperoxy) cyclohexane is dissolved in mXy 4.748 kg while stirring at 50 rpm. The polymerization was initiated by adding the resulting polymerization initiator solution at a rate of 1.0 kg / hour for 5 hours. Thus, the polymerization initiator was not added initially but was added at a constant addition rate for a fixed time.
During the polymerization, the solution temperature in the reactor was controlled at 120 ± 2 ° C. by temperature control with a jacket.
The polymerization solution was sampled after 6 hours from the polymerization initiation time, and analysis of the polymerization conversion rate was performed from the concentration of the remaining monomer. As a result, it was 96%. (Polymerization time = 6 hours).
Thereafter, this polymerization solution was supplied to a concentration device consisting of a tubular heat exchanger preheated to 170 ° C. and a vaporization tank to increase the concentration of the polymer contained in the solution to 70% by mass.
The obtained polymerization solution was supplied to a thin film evaporator having a heat transfer area of 0.2 m ² to carry out devolatilization.
The temperature in the apparatus at this time is 280 ° C., supply amount 30 L / hr, rotation speed 400 rpm, vacuum degree 30 Torr, and the polymer after volatilization is pressurized by a gear pump and extruded from a strand die. A methacrylic resin was obtained.
Using the obtained methacrylic resin, using monomethylamine as an imidizing agent, using a mesh-type co-rotating twin screw extruder with a bore of 15 mm and L / D = 90, having a glutarimide structural unit A methacrylic resin was produced.
At that time, the oxygen concentration in the extruder was reduced to 1% or less by flowing nitrogen gas from the popper. The set temperature of each temperature control zone of the extruder was 250 ° C., screw rotation number 300 rpm, and MS resin was supplied at 1 kg / hour, and the supply amount of monomethylamine was 20 parts by mass with respect to 100 parts by mass of methacrylic resin. A methacrylic resin was charged from the hopper, and the resin was melted and filled with a kneading block, and then monomethylamine was injected from the nozzle. A seal ring was placed at the end of the reaction zone to fill the resin. By-products after reaction and excess methylamine were removed by reducing the degree of vacuum at the vent port to 60 Torr. The resin which came out as a strand from the die provided at the extruder outlet was pelletized with a pelletizer after being cooled in a water bath.
Then, in the mesh type co-rotating twin-screw extruder with a bore of 15 mm and L / D = 90, the set temperature of each temperature control zone of the extruder is 230 ° C., and the screw rotation speed is 150 rpm. After charging the pellets obtained above at a feed rate of 1 kg / hr and melting and filling the resin with the kneading block, 0.8 mass per 100 parts by mass of the above pellet-like resin from the nozzle One hundred parts by weight of dimethyl carbonate and 1.3 parts by weight of allylcyclohexane were added to 100 parts by weight of the total weight of monomers. At the end of the reaction zone, reverse flight was introduced to fill the resin. Byproducts after reaction and excess dimethyl carbonate and allylcyclohexane were removed by reducing the degree of vacuum at the vent port to 100 Torr.
The resin which came out as a strand from the die provided at the extruder outlet was cooled in a water tank and then pelletized again by a pelletizer to obtain a methacrylic resin having a glutarimide structural unit.

[Example 12]
20 parts by mass of MMA, 5 parts by mass of methyl 2- (hydroxymethyl) acrylate, 25 parts by mass of toluene in an autoclave provided with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen gas introduction pipe, the inside of which was previously replaced with nitrogen. 0.025 parts by mass of tris (2,4-di-t-butylphenyl) phosphite was charged as the organophosphorus compound.
Thereafter, the temperature is raised to 100 ° C. while introducing nitrogen gas, and 0.05 parts by mass of t-amyl peroxy isononanoate is added as a polymerization initiator, and at the same time, t-amyl peroxy isononanoate 0.075 Solution polymerization was carried out at about 105 to 110 ° C. under reflux while starting dropwise addition of a toluene solution containing parts by mass over 1.5 hours, and polymerization was continued for 5.5 hours. Further, 20 parts by mass of MMA, 5 parts by mass of methyl 2- (hydroxymethyl) acrylate, and 25 parts by mass of toluene were added at a constant speed in 2 hours after 30 minutes from the start of polymerization.
The polymer solution was sampled 4 hours and 7.5 hours after the initiation of polymerization, respectively, and the polymerization conversion rate was analyzed from the remaining monomer concentration, and after 4 hours, it was 84.6%, 7.5 It was 94.8% after time. The time average of the polymerization temperature from 0 hour to 7.5 hours after initiation of polymerization was 105.degree.
To the obtained polymer solution, 0.05 parts by mass of a stearyl phosphate / distearyl phosphate mixture which is an organophosphorus compound as a cyclization catalyst is added, and cyclization condensation is carried out at about 90 to 102 ° C. for 2 hours under reflux. The reaction was done.
Next, the obtained polymer solution is heated to 240 ° C. with a heating device comprising a multi-tubular heat exchanger, and two axes equipped with a plurality of vent ports and a plurality of side feed ports downstream for devolatilization. By introducing into an extruder, the cyclization reaction was advanced while degassing.
In the twin-screw extruder, the obtained copolymer solution was supplied so as to be 15 kg / hour in terms of resin, and the conditions were a barrel temperature of 250 ° C., a rotation number of 100 rpm, and a vacuum degree of 10 to 300 Torr. The resin composition melt-kneaded by a twin-screw extruder was extruded from a strand die, water-cooled and then pelletized to obtain a resin composition.
Then, in the mesh type co-rotating twin-screw extruder with a bore of 15 mm and L / D = 90, the set temperature of each temperature control zone of the extruder is 230 ° C., and the screw rotation speed is 150 rpm. The pellets obtained in the above were charged at a feed rate of 1 kg / hr, and after melting and filling the resin with a kneading block, 1.1 parts by mass based on 100 parts by mass of the monomer from the nozzle. A portion of allylcyclohexane was injected. At the end of the reaction zone, reverse flight was introduced to fill the resin. The excess allylcyclohexane after the reaction was removed by reducing the degree of vacuum at the vent port to 100 Torr.
The resin which came out as a strand from the die provided at the extruder outlet was cooled in a water tank and pelletized again by a pelletizer to obtain a methacrylic resin having a lactone structural unit.

Comparative Example 1
After completion of the polymerization, methacrylic resin pellets were obtained in the same manner as in Example 1 except that the amount of allylcyclohexane added was changed to 30.3 kg. Physical properties are shown in Table 1.

Comparative Example 2
After completion of the polymerization, methacrylic resin pellets were obtained in the same manner as in Example 1 except that the amount of allylcyclohexane added was changed to 0.2 kg. Physical properties are shown in Table 1.

Comparative Example 3
After completion of the polymerization, a methacrylic resin pellet was obtained in the same manner as in Example 1 except that the allyl compound was not added. Physical properties are shown in Table 1.

Comparative Example 4
After completion of the polymerization, a methacrylic resin pellet was obtained in the same manner as in Example 11 except that the allyl compound was not added. Physical properties are shown in Table 1.

Comparative Example 5
After completion of the polymerization, methacrylic resin pellets were obtained in the same manner as in Example 12 except that the allyl compound was not added. Physical properties are shown in Table 1.

As can be seen from Table 1, in the methacrylic resin of the example, the color tone and the transparency are improved without impairing the low birefringence.
On the other hand, in the methacrylic resin of the comparative example, any one or more of low birefringence, color tone and transparency was impaired.

The methacrylic resin of the present invention and the methacrylic resin composition are not only high in heat resistance and excellent in birefringence, but also extremely excellent in color tone and transparency.
The molded article for optical parts obtained by using the methacrylic resin composition of the present invention is, for example, a light guide plate used for displays such as smartphones, PDAs, tablet PCs and liquid crystal televisions, display front plates, touch panels, and smartphones, Lenses for tablet PC cameras, etc., optical lens parts such as head mount displays, liquid crystal projectors, etc., for example, prism elements, waveguides, lenses, optical lenses of small thin uneven thickness especially, optical fibers, optical fiber coating materials, lenses, A Fresnel lens, a phase plate provided with a microlens array, an optical cover part, etc. may be mentioned. Further, examples of automobile parts include light guide plates for in-vehicle displays; in-vehicle meter panels; front panels for car navigation, combiners, optical components for head-up displays such as optical cover parts, in-vehicle camera lenses, light guide bars and the like. In addition, it is particularly preferable to use as a component for a display device for digital signage, etc., in which information is flowed to a thin display connected to a network for the purpose of advertising, advertising etc. it can.

Claims (11)

It is a methacrylic resin containing a structural unit (X) having a ring structure in its main chain,
(A) glass transition temperature (Tg) is more than 120 ° C. and not more than 160 ° C., (b) absolute value of photoelastic coefficient is 3.0 × 10 ⁻¹² Pa ⁻¹ or less,
(C) A methacrylic resin characterized in that the allyl compound is contained in an amount of 10 to 2000 mass ppm with respect to 100 parts by mass of the methacrylic resin. 2. The methacrylic resin according to claim 1, wherein the absolute value of the photoelastic coefficient is 2.0 × 10 ⁻¹² Pa ⁻¹ or less. 2. The methacrylic resin according to claim 1, wherein the absolute value of the photoelastic coefficient is 1.5 × 10 ⁻¹² Pa ⁻¹ or less. 2. The methacrylic resin according to claim 1, wherein the absolute value of the photoelastic coefficient is 1.0 × 10 ⁻¹² Pa ⁻¹ or less.   The methacrylic resin according to any one of claims 1 to 4, wherein the allyl compound is at least one selected from the group consisting of an allyl alkyl compound, an allyl aryl compound, and an allyl ether compound.   The structural unit (X) is at least one selected from the group consisting of structural units derived from N-substituted maleimide monomers, glutarimide structural units, and lactone ring structural units. The methacrylic resin as described in.   A methacrylic resin composition comprising the methacrylic resin according to any one of claims 1 to 6.   A molded article comprising the methacrylic resin according to any one of claims 1 to 6 or the methacrylic resin composition according to claim 7.   An optical member comprising the molded article according to claim 8.   The optical member according to claim 9, which is a light guide plate.   An automobile part comprising the molded article according to claim 10.