JP7177724B2 - Molded body manufacturing method - Google Patents

Description

The present invention relates to a method for producing a molded article.

In the past, glass was used for optical parts such as lenses and prisms, but in recent years, plastic has been used due to the high degree of freedom in design, such as weight reduction and miniaturization, as well as the use of aspherical lenses. It has become to. Methacrylic resins, styrene resins, polycarbonates, cyclic olefin resins and the like are generally known as plastics used for optical parts.

In general, plastics tend to have birefringence due to orientation during molding, which adversely affects imaging performance when used as an optical component. Furthermore, when injection molding, which has high productivity, is used as a molding method, a greater degree of orientation is likely to occur, and the effect on imaging performance becomes significant. Methacrylic resins, typified by polymethyl methacrylate, have high transparency and low intrinsic birefringence, so that orientation birefringence can be made relatively low, and they have been suitably used as optical components. However, due to the increasing demand for higher optical performance, there is a demand for materials capable of reducing the orientation birefringence.

For example, Patent Documents 1 and 2 disclose orientation birefringence and photoelastic birefringence using a copolymer obtained by copolymerizing monomers including methyl methacrylate, 2,2,2-trifluoroethyl methacrylate, and benzyl methacrylate. It is disclosed that the refraction can be low. This is done by selecting a plurality of monomers having different signs of intrinsic birefringence and photoelastic coefficient when they are homopolymers, combining them and copolymerizing them to adjust the composition, thereby obtaining orientation birefringence and It is based on the idea of reducing photoelastic birefringence. However, since this copolymer has a low glass transition temperature, there is a problem that its use in electronic devices, automobiles, etc., where the interior temperature can be high, is limited. Furthermore, the problem of color tone and the problem of further deterioration of color tone when used in a high-temperature environment have not been resolved.

Therefore, as a resin for injection molding with improved orientation birefringence and heat resistance, the aromatic double bond of a copolymer obtained by polymerizing a monomer composition containing a (meth)acrylic acid ester monomer and an aromatic vinyl monomer (Patent Document 3) and a (meth)acrylic resin having a ring-structured glutarimide unit in the main chain (Patent Document 4) have been proposed. However, although the orientation birefringence of these resins is low, the photoelastic coefficient is not sufficiently reduced, so there is a drawback that birefringence occurs due to residual strain during molding and stress generated when optical parts are fixed to equipment. rice field.

Therefore, a non-birefringent resin material (Patent Document 5) composed of a composition containing a resin such as a glutarimide acrylic resin and a graft copolymer, or a methacrylate monomer and two or more N-substituted maleimide monomers are used. Resin materials that reduce both orientation birefringence and photoelasticity in injection molded pieces and have high heat resistance, such as methacrylic copolymers (Patent Document 6) having a ring structure in the main chain obtained from monomers containing Proposed. However, a composition containing a plurality of resins that are not completely compatible, such as that disclosed in Patent Document 5, has limited application as an optical component because the thicker the molded article, the higher the haze and the worse the transparency. In addition, although the methacrylic resin of Patent Document 6 has low orientation birefringence and photoelastic coefficient even as an injection molded product, it has problems of color tone deterioration due to N-substituted maleimide, and complex molding such as lenses and prisms with varying thickness. When used for a body or a thin molded body such as a light guide plate, it is necessary to perform high-temperature molding for the purpose of increasing the fluidity, and furthermore, there has been a problem that the color tone is lowered.
Accordingly, there is a demand for a resin composition that has excellent heat resistance and higher transparency as a substitute for glass, while reducing both orientation birefringence and photoelasticity.

Japanese Patent Application Laid-Open No. 2006-308682 WO2015/098980 JP 2008-15199 A JP-A-2006-328330 WO2015/098775 WO2011/149088

An object of the present invention is to provide a method for producing a molded article made of a methacrylic resin composition containing a methacrylic resin containing a structural unit having a ring structure in its main chain and having an improved color tone.

As a result of intensive studies to solve the above-described problems of the prior art, the present inventors have found that a molded article made of a methacrylic resin composition containing a methacrylic resin containing a structural unit having a ring structure in the main chain is specified. It has been clarified that the above problems can be solved by irradiating light with a wavelength of .

That is, the present invention is as follows.
(1)
irradiating a molded body made of a methacrylic resin composition containing a methacrylic resin containing a structural unit having a ring structure in its main chain with light having a wavelength of 200 to 480 nm ,
A method for producing a molded article, wherein the integrated light quantity of the light to be irradiated is 0.005 W·hr/mm ² or more and 100 W·hr/mm ² or less .
(2)
The method for producing a molded article according to (1 ), wherein the wavelength is 315 to 480 nm.
(3)
The method for producing a molded article according to (1) or (2) , wherein the wavelength is 400 to 480 nm.
(4)
According to any one of (1) to (3) , the temperature of the molded article when irradiated with light is 20° C. or higher and 20° C. or lower than the glass transition temperature of the methacrylic resin composition. A method for producing a molded article.

ADVANTAGE OF THE INVENTION According to this invention, the molded object which consists of the methacrylic-type resin composition containing the methacrylic-type resin containing the structural unit which has a cyclic structure in a main chain which improved the color tone can be obtained.

1 is a schematic diagram of strip-shaped pieces used in Examples and Comparative Examples. FIG. It is the schematic which demonstrates the irradiation position of the laser beam to the strip molding piece used in Examples 1 and 2. FIG. FIG. 10 is a schematic diagram for explaining the irradiation position of LED light on the strip-shaped piece used in Example 3. FIG. 4 is a diagram showing measurement results of spectral transmittance in Example 1. FIG. FIG. 10 is a diagram showing measurement results of spectral transmittance in Example 2; FIG. 10 is a diagram showing measurement results of spectral transmittance in Example 3; It is a figure which shows the measurement result of the spectral transmittance|permeability of a comparative example.

Hereinafter, the mode for carrying out the present invention (hereinafter referred to as "this embodiment") will be described in detail, but the present invention is not limited to the following description, and within the scope of the gist Various modifications can be made.

(methacrylic resin)
The methacrylic resin of the present embodiment is a methacrylic resin containing a methacrylic acid ester monomer unit (A) and a structural unit (B) having a ring structure in its main chain. The structural unit (B) having a ring structure in the main chain includes a structural unit (B-1) derived from an N-substituted maleimide monomer, a glutarimide structural unit (B-2), and a lactone ring structural unit (B-3). ), etc. It also optionally contains other vinyl-based monomer units (C) copolymerizable with methacrylic acid ester monomers.

Each monomer structural unit will be described below.

- Structural unit (A) derived from methacrylic acid ester monomer -
First, the structural unit (A) derived from the methacrylic acid ester monomer will be described.
The structural unit (A) derived from a methacrylic acid ester monomer is formed, for example, from a monomer selected from the methacrylic acid esters shown below.
Examples of methacrylates 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.
These monomers may be used alone or in combination of two or more.
Among the above methacrylic acid esters, methyl methacrylate and benzyl methacrylate are preferable because the methacrylic resin to be obtained has excellent transparency and weather resistance.
Structural units (A) derived from methacrylic acid ester monomers may be contained alone or in combination of two or more.

The content of the structural unit (A) derived from the methacrylic acid ester monomer is, from the viewpoint of sufficiently imparting heat resistance to the methacrylic resin by the structural unit (B) having a ring structure in the main chain described later, The methacrylic resin is 100% by mass, preferably 50 to 97% by mass, more preferably 55 to 97% by mass, even more preferably 55 to 95% by mass, still more preferably 60 to 93% by mass, particularly preferably 60% by mass. ~90% by mass.
The content of the structural unit (A) derived from the methacrylic acid ester monomer can be determined by ¹ H-NMR measurement and ¹³ C-NMR measurement. ¹ H-NMR measurement and ¹³ C-NMR measurement can be performed at a measurement temperature of 40° C. using, for example, CDCl ₃ or DMSO-d ₆ as a measurement solvent.

The structural unit (B) having a ring structure in its main chain is described below.
-Structural unit (B) having a ring structure in the main chain-
-- Structural unit (B-1) derived from N-substituted maleimide monomer --
Next, the structural unit (B-1) derived from the N-substituted maleimide monomer will be described.
The structural unit (B-1) derived from the N-substituted maleimide monomer is at least selected from monomers represented by the following formula (1) and/or monomers represented by the following formula (2) It may be one, and is preferably formed from both 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、炭素数１～１２のアルキル基、炭素数６～１４のアリール基のいずれかを示す。
また、Ｒ²がアリール基の場合には、Ｒ²は、置換基としてハロゲンを含んでいてもよい。
また、Ｒ¹は、ハロゲン原子、炭素数１～６のアルキル基、炭素数１～６のアルコキシ基、ニトロ基、ベンジル基等の置換基で置換されていてもよい。

^In formula ( ¹ ), R ¹ represents either an arylalkyl group having 7 to 14 carbon atoms or an aryl group having 6 to 14 carbon atoms; It represents either an alkyl group of 1 to 12 or an aryl group of 6 to 14 carbon atoms.
Moreover, when R ² is an aryl group, R ² may contain a halogen as a substituent.
Also, 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、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. , an alkyl group having 1 to 12 carbon atoms, or an aryl group having 6 to 14 carbon atoms.

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

Examples of the monomer represented by formula (2) include N-methylmaleimide, N-ethylmaleimide, Nn-propylmaleimide, N-isopropylmaleimide, Nn-butylmaleimide, N-isobutylmaleimide, Ns-butylmaleimide, Nt-butylmaleimide, Nn-pentylmaleimide, Nn-hexylmaleimide, Nn-heptylmaleimide, Nn-octylmaleimide, N-laurylmaleimide, N-stearyl maleimide, N-cyclopentylmaleimide, N-cyclohexylmaleimide, 1-cyclohexyl-3-methyl-1-phenyl-1H-pyrrole-2,5-dione, 1-cyclohexyl-3,4-dimethyl-1-phenyl-1H- pyrrole-2,5-dione, 1-cyclohexyl-3-phenyl-1H-pyrrole-2,5-dione, 1-cyclohexyl-3,4-diphenyl-1H-pyrrole-2,5-dione and the like.
Among these monomers, N-methylmaleimide, N-ethylmaleimide, N-isopropylmaleimide, and N-cyclohexylmaleimide are preferred from the viewpoint of excellent weather resistance of methacrylic resins. N-cyclohexylmaleimide is particularly preferred because of its excellent hygroscopicity.
These monomers can 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 properties. It is particularly preferable because it can be expressed.
The molar ratio (B1/ B2) is preferably greater than 0 and 15 or less, more preferably greater than 0 and 10 or less.
When the molar ratio B1/B2 is in this range, the methacrylic resin molded article of the present embodiment maintains transparency, does not yellow, and does not impair environmental resistance, and has good heat resistance and good heat resistance. It expresses photoelastic properties.

The content of the structural unit (B-1) derived from the N-substituted maleimide monomer is not particularly limited as long as the obtained composition satisfies the range of the glass transition temperature of the present embodiment. 100% by mass, preferably in the range of 5 to 40% by mass, more preferably in the range of 5 to 35% by mass.
Within this range, the methacrylic resin molded article has a more sufficient effect of improving heat resistance, and more favorable effects of improving weather resistance, low water absorption, and 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 is lowered during the polymerization reaction, and the amount of unreacted residual monomer is large. It is effective in preventing deterioration of the physical properties of the methacrylic resin molded product due to deterioration.

-- Glutarimide structural unit (B-2) --
Methacrylic resins having a glutarimide-based structural unit in the main chain, for example, JP-A-2006-249202, JP-A-2007-009182, JP-A-2007-009191, JP-A-2011-186482, Re It is a methacrylic resin having a glutarimide-based structural unit, which is described in Japanese Patent Publication No. 2012/114718, etc., and can be formed by the method described in the publication.

The glutarimide-based structural unit that constitutes the methacrylic resin of this embodiment may be formed after the resin is polymerized.
Specifically, the glutarimide-based 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。
グルタルイミド系構造単位を有するメタクリル系樹脂において、グルタルイミド系構造単位の含有量については、本実施形態の組成物として好ましいガラス転移温度の範囲を満たすものであれば特に制限はないが、メタクリル系樹脂を１００質量％として、好ましくは５～７０質量％の範囲、より好ましくは５～６０質量％の範囲である。
グルタルイミド系構造単位の含有量が上記範囲にあると、成形加工性、耐熱性、及び光学特性の良好な樹脂が得られることから好ましい。
グルタルイミド系構造単位を有するメタクリル系樹脂は、必要に応じて、芳香族ビニル単量体単位をさらに含んでいてもよい。
芳香族ビニル単量体としては特に限定されないが、スチレン、α－メチルスチレンが挙げられ、スチレンが好ましい。
グルタルイミド系構造単位を有するメタクリル系樹脂における芳香族ビニル単位の含有量としては、特に限定されないが、グルタルイミド系構造単位を有するメタクリル系樹脂を１００質量％として、０～２０質量％が好ましい。
芳香族ビニル単位の含有量が上記範囲にあると、耐熱性と優れた光弾性特性との両立が可能となり好ましい。

In general formula (3) above, preferably R ⁷ and R ⁸ are each independently hydrogen or a methyl group, R ⁹ is hydrogen, a methyl group, a butyl group, or a cyclohexyl group, and more Preferably, ^R7 is a methyl group, ^R8 is hydrogen and ^R9 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-based structural unit, the content of the glutarimide-based structural unit is not particularly limited as long as it satisfies the preferred glass transition temperature range for the composition of the present embodiment. Based on 100% by mass of the resin, the content is preferably in the range of 5 to 70% by mass, more preferably in the range of 5 to 60% by mass.
When the content of the glutarimide-based structural unit is within the above range, it is preferable because a resin having excellent moldability, heat resistance, and optical properties can be obtained.
A methacrylic resin having a glutarimide structural unit may further contain an aromatic vinyl monomer unit, if necessary.
Examples of the aromatic vinyl monomer include, but are not limited to, 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 within the above range, it is possible to achieve both heat resistance and excellent photoelastic properties, which is preferable.

--Lactone ring structural unit (B-3)--
Methacrylic resins having a lactone ring structural unit in the main chain, for example, JP-A-2001-151814, JP-A-2004-168882, JP-A-2005-146084, JP-A-2006-96960, JP-A-2006-96960, It can be formed by 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.
As the lactone ring structural unit in the present embodiment, a six-membered ring is preferable because the stability of the ring structure is excellent.
As the 6-membered lactone ring structural unit, for example, a structure represented by the following general formula (4) is particularly preferred.

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。
ラクトン環構造は、例えば、ヒドロキシ基を有するアクリル酸系単量体と、メタクリル酸メチル等のメタクリル酸エステル単量体とを共重合して、分子鎖にヒドロキシ基とエステル基又はカルボキシル基とを導入した後、これらヒドロキシ基とエステル基又はカルボキシル基との間で、脱アルコール（エステル化）又は脱水縮合（以下、「環化縮合反応」ともいう）を生じさせることにより形成することができる。
重合に用いるヒドロキシ基を有するアクリル酸系単量体としては、例えば、２－（ヒドロキシメチル）アクリル酸、２－（ヒドロキシエチル）アクリル酸、２－（ヒドロキシメチル）アクリル酸アルキル（例えば、２－（ヒドロキシメチル）アクリル酸メチル、２－（ヒドロキシメチル）アクリル酸エチル、２－（ヒドロキシメチル）アクリル酸イソプロピル、２－（ヒドロキシメチル）アクリル酸ｎ－ブチル、２－（ヒドロキシメチル）アクリル酸ｔ－ブチル）、２－（ヒドロキシエチル）アクリル酸アルキル等が挙げられ、好ましくは、ヒドロキシアリル部位を有する単量体である２－（ヒドロキシメチル）アクリル酸や２－（ヒドロキシメチル）アクリル酸アルキルであり、特に好ましくは２－（ヒドロキシメチル）アクリル酸メチル、２－（ヒドロキシメチル）アクリル酸エチルである。

In general formula (4) above, 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 organic residues include saturated aliphatic hydrocarbon groups (alkyl groups, etc.) having 1 to 20 carbon atoms such as methyl group, ethyl group and propyl group; saturated aliphatic hydrocarbon groups (alkenyl groups, etc.); aromatic hydrocarbon groups having 6 to 20 carbon atoms such as phenyl groups and naphthyl groups (aryl groups, etc.); these saturated aliphatic hydrocarbon groups, unsaturated aliphatic hydrocarbons a group in which one or more hydrogen atoms in an aromatic hydrocarbon group are 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 monomer having a hydroxy group and a methacrylic acid ester monomer such as methyl methacrylate to form a hydroxy group and an ester group or a carboxyl group in the 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 groups and ester groups or carboxyl groups.
Examples of acrylic acid-based monomers having a hydroxy group used for polymerization include 2-(hydroxymethyl)acrylic acid, 2-(hydroxyethyl)acrylic acid, and alkyl 2-(hydroxymethyl)acrylate (e.g., 2- (Hydroxymethyl) methyl acrylate, 2-(hydroxymethyl) ethyl acrylate, 2-(hydroxymethyl) isopropyl acrylate, 2-(hydroxymethyl) n-butyl acrylate, 2-(hydroxymethyl) t-acrylate butyl), 2-(hydroxyethyl)alkyl acrylate, etc., preferably 2-(hydroxymethyl)acrylic acid or 2-(hydroxymethyl)alkyl acrylate, which are monomers having a hydroxyallyl moiety. , and particularly preferably methyl 2-(hydroxymethyl)acrylate and ethyl 2-(hydroxymethyl)acrylate.

The content of the lactone ring structural unit in the methacrylic resin having the lactone ring structural unit in the main chain is not particularly limited as long as it satisfies the range of the glass transition temperature of the methacrylic resin of the present embodiment. It is preferably 5 to 40% by mass, more preferably 5 to 35% by mass, based on 100% by mass.
When the content of the lactone ring structural unit is within this range, the effects of introducing the ring structure, such as improved solvent resistance and improved surface hardness, can be exhibited while maintaining moldability.
In addition, the content of the lactone ring structure in the methacrylic resin can be determined using the method described in the aforementioned patent document.

The content of the structural unit (B) having a ring structure in the main chain is 3, based on 100% by mass of the methacrylic resin, from the viewpoint of the heat resistance, thermal stability, strength, and fluidity of the methacrylic resin of the present embodiment. to 40% by mass, the lower limit is more preferably 5% by mass or more, still more preferably 7% by mass or more, and even more preferably 8% by mass or more, and the upper limit is more preferably It is 30% by mass or less, more preferably 28% by mass or less, even more preferably 25% by mass or less, particularly preferably 20% by mass or less, even more preferably 18% by mass or less, and most preferably less than 15% by mass.

-Other vinyl-based monomer unit (C) copolymerizable with methacrylic acid ester monomer-
Other vinyl-based monomer units (C) copolymerizable with methacrylic acid ester monomers that can constitute the methacrylic resin of the present embodiment (hereinafter sometimes referred to as (C) monomer units) ) include aromatic vinyl-based monomer units (C-1), acrylic acid ester monomer units (C-2), vinyl cyanide-based monomer units (C-3), and other units A mer unit (C-4) is included.
Other vinyl-based monomer units (C) copolymerizable with the methacrylic acid ester monomer may be used singly or in combination of two or more.
The (C) monomer unit can be appropriately selected according to the properties required for the methacrylic resin, but properties such as thermal stability, fluidity, mechanical properties, and chemical resistance are particularly required. is selected from the group consisting of an aromatic vinyl-based monomer unit (C-1), an acrylate monomer unit (C-2), and a vinyl cyanide-based monomer unit (C-3) At least one is preferred.

前記一般式（４）中、Ｒ¹³は、水素原子、又は炭素数が１～６のアルキル基を表し、当該アルキル基は、例えば、水酸基で置換されていてもよい。
Ｒ¹⁴は、水素原子、炭素数が１～１２のアルキル基、炭素数が１～１２のアルコキシ基、炭素数が６～８のアリール基、炭素数が６～８のアリーロキシ基からなる群より選択されるいずれかであり、Ｒ¹⁴は、全て同じ基であっても、異なる基であってもよい。また、Ｒ¹⁴同士で環構造を形成してもよい。
ｎは、０～５の整数を表す。
上記一般式（５）で表される単量体の具体例としては、特に限定されるものではないが、スチレン、ｏ－メチルスチレン、ｍ－メチルスチレン、ｐ－メチルスチレン、２，４－ジメチルスチレン、２，５－ジメチルスチレン、３，４－ジメチルスチレン、３，５－ジメチルスチレン、ｐ－エチルスチレン、ｍ－エチルスチレン、о－エチルスチレン、ｐ－ｔｅｒｔ－ブチルスチレン、１－ビニルナフタレン、２－ビニルナフタレン、１，１－ジフェニルエチレン、イソプロペニルベンセン（α－メチルスチレン）、イソプロペニルトルエン、イソプロペニルエチルベンゼン、イソプロペニルプロピルベンゼン、イソプロペニルブチルベンゼン、イソプロペニルペンチルベンゼン、イソプロペニルヘキシルベンゼン、イソプロペニルオクチルベンゼン、α－ヒドロキシメチルスチレン、α－ヒドロキシエチルスチレン等が挙げられる。
上記の中でも、スチレン、イソプロペニルベンゼンが好ましく、流動性付与や、重合転化率の向上による未反応モノマー類の低減等の観点から、スチレンがより好ましい。
これらは、本実施形態のメタクリル系樹脂において、要求される特性に応じて適宜選択してよい。
芳香族ビニル系単量体単位（Ｃ－１）を使用する場合の含有量は、耐熱性、残存モノマー種の低減、流動性のバランスを考慮すると、（Ａ）単量体単位と（Ｂ）構造単位との合計量を１００質量％とした場合に、２３質量％以下であることが好ましく、より好ましくは２０質量％以下、さらに好ましくは１８質量％以下、さらにより好ましくは１５質量％以下、よりさらに好ましくは１０質量％以下である。
芳香族ビニル系単量体単位（Ｃ－１）を、上述したマレイミド系構造単位（Ｂ－１）と併用する場合、（Ｂ－１）構造単位の含有量に対する（Ｃ－１）単量体単位の含有量の割合（質量比）（すなわち、（Ｃ－１）含有量／（Ｂ－１）含有量）としては、フィルムを成形加工する際の加工流動性や、残存モノマー低減によるシルバーストリークス低減効果等の観点から、０．３～５であることが好ましい。
ここで、良好な色調や耐熱性を保持する観点から、上限値は、５以下であることが好ましく、より好ましくは３以下、さらに好ましくは１以下である。また、残存モノマー低減の観点から、下限値は、０．３以上であることが好ましく、より好ましくは０．４以上である。
上述した芳香族ビニル系単量体（Ｃ－１）は、１種のみを単独で用いてもよく、２種以上を組み合わせて用いてもよい。 [Aromatic vinyl-based monomer unit (C-1)]
The monomer forming the aromatic vinyl-based monomer unit (C-1) constituting the methacrylic resin of the present embodiment is not particularly limited, but is represented by the following general formula (5) Aromatic vinyl monomers are preferred.

In general formula (4), R ¹³ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and the alkyl group may be substituted with, for example, a hydroxyl group.
R ¹⁴ is selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aryl group having 6 to 8 carbon atoms, and an aryloxy group having 6 to 8 carbon atoms. Any one selected, and R ¹⁴ may all be the same group or different groups. Also, R ¹⁴ may form a ring structure together.
n represents an integer of 0 to 5;
Specific examples of the monomer represented by the general formula (5) are not particularly limited, but styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethyl styrene, 2,5-dimethylstyrene, 3,4-dimethylstyrene, 3,5-dimethylstyrene, p-ethylstyrene, m-ethylstyrene, o-ethylstyrene, p-tert-butylstyrene, 1-vinylnaphthalene, 2-vinylnaphthalene, 1,1-diphenylethylene, isopropenylbenzene (α-methylstyrene), isopropenyltoluene, isopropenylethylbenzene, isopropenylpropylbenzene, isopropenylbutylbenzene, isopropenylpentylbenzene, isopropenylhexylbenzene, isopropenyloctylbenzene, α-hydroxymethylstyrene, α-hydroxyethylstyrene and the like.
Among the above, styrene and isopropenylbenzene are preferred, and styrene is more preferred from the viewpoint of imparting fluidity and reducing unreacted monomers by improving polymerization conversion.
These may be appropriately selected according to the properties required for the methacrylic resin of the present embodiment.
When the aromatic vinyl-based monomer unit (C-1) is used, the content is, considering heat resistance, reduction of residual monomer species, and balance of fluidity, (A) monomer unit and (B) When the total amount with the structural unit is 100% by mass, it is preferably 23% by mass or less, more preferably 20% by mass or less, still more preferably 18% by mass or less, and even more preferably 15% by mass or less, Even more preferably, it is 10% by mass or less.
When the aromatic vinyl-based monomer unit (C-1) is used in combination with the maleimide-based structural unit (B-1) described above, the (C-1) monomer relative to the content of the (B-1) structural unit The ratio of the unit content (mass ratio) (that is, (C-1) content / (B-1) content) is the processing fluidity during film molding and the silver streak due to the reduction of residual monomers. It is preferably 0.3 to 5 from the viewpoint of the effect of reducing noise.
Here, from the viewpoint of maintaining good color tone and heat resistance, the upper limit is preferably 5 or less, more preferably 3 or less, and even more preferably 1 or less. From the viewpoint of reducing residual monomers, the lower limit is preferably 0.3 or more, more preferably 0.4 or more.
The aromatic vinyl-based monomer (C-1) described above may be used alone or in combination of two or more.

前記一般式（６）中、Ｒ¹⁵は、水素原子、又は炭素数が１～１２のアルコキシ基を表し、Ｒ¹⁶は、炭素数が１～１８のアルキル基、炭素数が３～１２のシクロアルキル基、炭素数が６～１４のアリール基のいずれかを表す。
前記アクリル酸エステル単量体単位（Ｃ－２）を形成するための単量体としては、本実施形態のフィルム用のメタクリル系樹脂において、耐候性、耐熱性、流動性、熱安定性を高める観点から、アクリル酸メチル、アクリル酸エチル、アクリル酸ｎ－プロピル、アクリル酸イソプロピル、アクリル酸ｎ－ブチル、アクリル酸ｓｅｃ－ブチル、アクリル酸２－エチルヘキシル、アクリル酸シクロヘキシル、アクリル酸フェニル等が好ましく、より好ましくは、アクリル酸メチル、アクリル酸エチル、アクリル酸ｎ－ブチルであり、入手しやすさの観点から、アクリル酸メチル、アクリル酸エチルがさらに好ましい。
上記アクリル酸エステル単量体単位（Ｃ－２）は、１種のみを単独で用いてもよく、２種以上を併用してもよい。
アクリル酸エステル単量体単位（Ｃ－２）を使用する場合の含有量は、耐熱性及び熱安定性の観点から、（Ａ）単量体単位と（Ｂ）構造単位との合計量を１００質量％とした場合に、５質量％以下であることが好ましく、より好ましくは３質量％以下である。 [Acrylic acid ester monomer unit (C-2)]
The monomer forming the acrylic acid ester monomer unit (C-2) constituting the methacrylic resin of the present embodiment is not particularly limited, but acrylic represented by the following general formula (6) Acid ester monomers are preferred.

In the general formula (6), R ¹⁵ represents a hydrogen atom or an alkoxy group having 1 to 12 carbon atoms, R ¹⁶ represents an alkyl group having 1 to 18 carbon atoms, a cyclo It represents either an alkyl group or an aryl group having 6 to 14 carbon atoms.
As a monomer for forming the acrylic acid ester monomer unit (C-2), in the methacrylic resin for the film of the present embodiment, the weather resistance, heat resistance, fluidity, and heat stability are improved. From the point of view, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, sec-butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenyl acrylate and the like are preferable. Methyl acrylate, ethyl acrylate and n-butyl acrylate are more preferable, and methyl acrylate and ethyl acrylate are more preferable from the viewpoint of availability.
The acrylic acid ester monomer units (C-2) may be used singly or in combination of two or more.
The content when the acrylic acid ester monomer unit (C-2) is used is, from the viewpoint of heat resistance and thermal stability, the total amount of the (A) monomer unit and the (B) structural unit to 100. In terms of % by mass, it is preferably 5% by mass or less, more preferably 3% by mass or less.

[Vinyl cyanide-based monomer unit (C-3)]
The monomer forming the vinyl cyanide monomer unit (C-3) constituting the methacrylic resin of the present embodiment is not particularly limited, but examples include acrylonitrile, methacrylonitrile, ethacrylonitrile, Nitrile, vinylidene cyanide, and the like can be mentioned, and among them, acrylonitrile is preferable from the viewpoint of availability and imparting chemical resistance.
The vinyl cyanide-based monomer units (C-3) may be used alone or in combination of two or more.
When the vinyl cyanide-based monomer unit (C-3) is used, the content is the total amount of the (A) monomer unit and (B) structural unit from the viewpoint of maintaining solvent resistance and heat resistance. is preferably 15% by mass or less, more preferably 12% by mass or less, and even more preferably 10% by mass or less, when the is 100% by mass.

[monomer unit (C-4) other than (C-1) to (C-3)]
The monomer forming the monomer unit (C-4) other than (C-1) to (C-3) constituting the methacrylic resin of the present embodiment is not particularly limited, but for example , acrylamide and methacrylamide; glycidyl compounds such as glycidyl (meth)acrylate and allyl glycidyl ether; unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, maleic acid and fumaric acid, and their half esters compounds or anhydrides; unsaturated alcohols such as methallyl alcohol and allyl alcohol; olefins such as ethylene, propylene and 4-methyl-1-pentene; vinyl acetate, 2-hydroxymethyl-1-butene, methyl vinyl ketone, Examples thereof include vinyl compounds other than those mentioned above, such as N-vinylpyrrolidone and N-vinylcarbazole, and vinylidene compounds.
Furthermore, crosslinkable compounds having multiple reactive double bonds include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, and the like. Esterification of both terminal hydroxyl groups of ethylene glycol or its oligomer with acrylic acid or methacrylic acid; neopentyl glycol di(meth)acrylate, di(meth)acrylate, etc., with acrylic acid or methacrylic acid for the hydroxyl groups of two alcohols esterified ones; polyhydric alcohol derivatives such as trimethylolpropane and pentaerythritol esterified with acrylic acid or methacrylic acid; and polyfunctional monomers such as divinylbenzene.
Among the monomers constituting the (C) monomer unit described above, at least one selected from the group consisting of methyl acrylate, ethyl acrylate, styrene, and acrylonitrile is preferable from the viewpoint of availability.
The content of other vinyl-based monomer units (C) that can be copolymerized with the methacrylic acid ester monomer is 100% by mass of the methacrylic resin from the viewpoint of enhancing the effect of imparting heat resistance by the structural unit (B). is 0 to 20% by mass, preferably 0 to 18% by mass, more preferably 0 to 15% by mass.
In particular, when using a crosslinkable polyfunctional (meth)acrylate having a plurality of reactive double bonds as the monomer unit (C), the content of the monomer unit (C) is the fluidity of the polymer. From the viewpoint of , it is preferably 0.5% by mass or less, more preferably 0.3% by mass or less, and still more preferably 0.2% by mass or less.
In particular, in the present embodiment, from the viewpoint of the heat resistance and optical properties of the methacrylic resin molded product, when the total amount of the (B) structural unit and the (C) monomer unit is 100% by mass, (B) The content of structural units is 45 to 100% by mass. At this time, the content of the (C) structural unit is 0 to 55% by mass. The content of the (B) structural unit is preferably 50 to 100% by mass, more preferably 50 to 90% by mass, still more preferably 50 to 80% by mass.

The properties of the methacrylic resin of this embodiment are described below.

(Glass-transition temperature)
The glass transition temperature (Tg) of the methacrylic resin in the present embodiment is preferably above 120°C and 160°C or less.
If the glass transition temperature of the methacrylic resin exceeds 120 ° C., it is easier to obtain necessary and sufficient heat resistance for optical parts such as lens moldings in recent years, automotive parts such as in-vehicle displays, and film moldings for liquid crystal displays. can get to The glass transition temperature (Tg) is more preferably 125° C. or higher, and still more preferably 130° C. or higher, from the viewpoint of dimensional stability under the environmental temperature of use.
On the other hand, when the glass transition temperature (Tg) of the methacrylic resin is 160° C. or less, melt processing at extremely high temperatures is avoided, thermal decomposition of the resin is suppressed, and good products can be obtained. The glass transition temperature (Tg) is preferably 150° C. or lower for the reasons described above.
The glass transition temperature (Tg) can be determined by measuring according to JIS-K7121. Specifically, it can be measured using the method described in the examples below.

(Weight average molecular weight)
In the methacrylic resin of the present embodiment, the weight average molecular weight (Mw) in terms of polymethyl methacrylate measured by gel permeation chromatography (GPC) is preferably in the range of 65,000 to 220,000, more preferably It is in the range of 80,000 to 180,000, more preferably in the range of 90,000 to 150,000.
When the weight average molecular weight (Mw) is within the above range, the balance between mechanical strength and fluidity is also excellent.
Further, regarding the ratio among the Z-average molecular weight (Mz), the weight-average molecular weight (Mw), and the number-average molecular weight (Mn), which are parameters representing the molecular weight distribution, the methacrylic resin in the present embodiment has fluidity and mechanical Considering the balance with strength, Mw / Mn is preferably 1.5 to 3.0, more preferably 1.6 to 2.5, and 1.6 to 2.3 Mz/Mw is more preferably 1.3 to 2.0, more preferably 1.3 to 1.8, even more preferably 1.4 to 1.7.
The weight-average molecular weight and number-average molecular weight of the methacrylic resin can be measured by the methods described in Examples below.

(Method for producing methacrylic resin)
A method for producing the methacrylic resin of the present embodiment will be described below.
Hereinafter, a method for producing a methacrylic resin containing an N-substituted maleimide structural unit (B-1) as the structural unit (B) having a ring structure in the main chain will be described in detail.
As a method for producing a methacrylic resin having a structural unit (B-1) derived from an N-substituted maleimide monomer in the main chain in the present embodiment, a solution polymerization method is preferable.
In the production method of the present embodiment, a batch (batch) system, a semi-batch system, or a continuous system can be used as the polymerization system. Here, the batch system is a process in which the reaction is started and progressed after the total amount of raw material is introduced into the reactor, and the product is recovered after completion. It is a process in which one of them is carried out simultaneously while the reaction is in progress, and the continuous type is a process in which both the charging of raw materials and the recovery of the product are carried out simultaneously while the reaction is in progress. As a method for producing a methacrylic resin having a structural unit derived from an N-substituted maleimide monomer in the main chain in the present embodiment, from the viewpoint of precisely controlling the copolymer composition, a part of raw materials is added after the reaction is started. A semi-batch type of dosing is preferred.
In the method for producing a methacrylic resin according to the present embodiment, it is preferable to use polymerization of monomers by radical polymerization.

The polymerization solvent to be used is not particularly limited as long as it can increase the solubility of the maleimide copolymer obtained by polymerization and can maintain the viscosity of the reaction solution appropriately for the purpose of preventing gelation or the like.
Specific polymerization solvents include aromatic hydrocarbons such as toluene, xylene, ethylbenzene and isopropylbenzene; ketones such as methylisobutylketone, butylcellosolve, methylethylketone and cyclohexanone; polar solvents such as dimethylformamide and 2-methylpyrrolidone. can be used.
Alcohols such as methanol, ethanol, and isopropanol may also be used as a polymerization solvent as long as they do not inhibit the dissolution of the polymerization product during polymerization.
These may be used individually by 1 type, or may be used in combination of 2 or more types.

The amount of the solvent used during polymerization is not particularly limited as long as the polymerization proceeds, the copolymer and the monomer used do not precipitate during 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. More preferably 25 to 200 parts by mass, still more preferably 50 to 200 parts by mass, still more preferably 50 to 150 parts by mass.

The polymerization temperature is not particularly limited as long as it is a temperature at which polymerization proceeds. ~150°C. From the viewpoint of productivity, the temperature is preferably 70° C. or higher, and preferably 180° C. or lower in order to suppress side reactions during polymerization and obtain a polymer having a desired molecular weight and quality.

In addition, the polymerization time is not particularly limited as long as it is a time that can obtain the required degree of polymerization at the required conversion rate, but from the viewpoint of productivity etc., it is preferably 2 to 15 hours. More preferably 3 to 12 hours, still more preferably 4 to 10 hours.

The polymerization conversion rate at the end of polymerization of the methacrylic resin having a structural unit derived from an N-substituted maleimide monomer in the main chain in the present embodiment is preferably 93 to 99.9%, preferably 95 to 99.9. %, more preferably 97 to 99.8%.
Here, the polymerization conversion rate is the value obtained by subtracting the total mass of the monomers remaining at the end of the polymerization from the total mass of the monomers added to the polymerization system. is the ratio to the total mass of
Further, the amount of the N-substituted maleimide monomer remaining in the solution after polymerization (N-substituted maleimide residual amount) is preferably 50 to 5000 mass ppm or less, and 100 to 3000 mass ppm or less. is more preferable, and 200 to 1000 ppm by mass or less is even more preferable.
The higher the polymerization conversion rate and the lower the N-substituted maleimide residual amount, the less the monomers that go into the solvent recovery system, so the load on the purification system is reduced, and the unit consumption is increased, which is economical. If the polymerization conversion rate is too high or the amount of residual N-substituted maleimide is too low, the amount of coloring low-molecular-weight components increases, which may adversely affect color tone and moldability.

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

A polymerization initiator may be added during the polymerization reaction.
Any initiator generally used in radical polymerization can be used as the polymerization initiator. Examples include cumene hydroperoxide, diisopropylbenzene hydroperoxide, di-t-butyl peroxide, lauroyl peroxide, and benzoyl peroxide. organic peroxides such as oxide, t-butylperoxyisopropyl carbonate, t-amylperoxy-2-ethylhexanoate, t-amylperoxyisononanoate, 1,1-di-t-butylperoxycyclohexane; 2,2'-azobis(isobutyronitrile), 1,1'-azobis(cyclohexanecarbonitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl-2,2'-azobis azo compounds such as isobutyrate; and the like.
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 amount of the polymerization initiator to be added may be 0.01 to 1 part by mass, preferably 0.05 to 0.5 part by mass, when the total amount of monomers used for polymerization is 100 parts by mass.

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

In order to reduce the difference in the composition of bonded monomers in copolymers with different molecular weights, some monomer units are additionally added so that the composition of the monomers in the polymerization system during polymerization is as uniform as possible. It is preferable to polymerize while For example, the difference in the consumption rate of each monomer when about 70% of the total amount of monomers finally added to the system is consumed is 10% or less, more preferably 5% or less, and further The type, amount and timing of the additional monomers to be added are adjusted so that the content is preferably 3% or less. Furthermore, the polymerization is carried out so that the difference in final conversion between the monomers at the end of the polymerization is 10% or less, more preferably 5% or less, still more preferably 3% or less.

The method for recovering the polymer from the polymerization liquid obtained by solution polymerization is not particularly limited. After adding the polymerization liquid in the presence of an excess amount, treatment with a homogenizer (emulsification dispersion) is performed, and unreacted monomers are subjected to pretreatment such as liquid-liquid extraction and solid-liquid extraction. a method of separating from the polymerization liquid; or a method of separating the polymerization solvent and unreacted monomers via a step called devolatilization step to recover the polymerization product; and the like.
Here, the devolatilization step refers to a step of removing volatile matter such as a polymerization solvent, residual monomers, and reaction by-products under heating and reduced pressure conditions.

Devices used in the devolatilization process include, for example, a devolatilization device consisting of a tubular heat exchanger and a devolatilization tank; thin film evaporators such as Wyblen and Exeva manufactured by Kobelco Eco-Solutions Co., Ltd., Contra and inclined blade Contra manufactured by Hitachi; A vented extruder with sufficient residence time and surface area to exhibit vaporization performance;
A devolatilization step or the like using a devolatilization device in which two or more of these devices are combined can also be used.

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

The degree of vacuum in the devolatilizer is preferably in the range of 10 to 500 Torr, more preferably in the range of 10 to 300 Torr. By making the degree of vacuum equal to or lower than the upper limit, the residual amount of volatile matter can be suppressed. A degree of vacuum equal to or higher than the lower limit is practical for industrial implementation.

The treatment time is appropriately selected according to the amount of residual volatile matter, but the shorter the treatment time, the better, in order to suppress the coloring and decomposition of the obtained acrylic resin.

The polymer recovered through the devolatilization step may be processed into pellets in a step called granulation step.
In the granulation step, the molten resin may be extruded from a multi-hole die in the form of strands and processed into pellets by a cold cut method, an air hot cut method, or an underwater cut method.
When a vented extruder is employed as the devolatilization device, the devolatilization step and the granulation step may be combined.

Next, an example of a method for producing a methacrylic resin having a glutarimide structural unit will be described.

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

Next, the (meth)acrylic acid ester polymer or the methacrylic acid ester-aromatic vinyl copolymer is reacted with an imidizing agent to perform an imidization reaction (imidization step). Thereby, a methacrylic resin having a glutarimide structural unit can be produced.

The imidizing agent is not particularly limited as long as it can form the glutarimide structural unit represented by the general formula (3).
Specifically, ammonia or primary amine can be used as the imidizing agent. Examples of the primary amine 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;
Among the above imidization agents, ammonia, methylamine, and cyclohexylamine are preferably used, and methylamine is particularly preferably used, from the viewpoint of cost and physical properties.
In this imidization step, the content of the glutarimide-based structural unit in the obtained methacrylic resin having the glutarimide-based structural unit can be adjusted by adjusting the addition ratio of the imidizing agent.

The method for carrying out the imidization reaction is not particularly limited, but 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 the extruder is not particularly limited, for example, a single-screw extruder, a twin-screw extruder, a multi-screw extruder, or the like can be used.

Among them, it is preferable to use a twin-screw extruder. A twin-screw extruder can facilitate mixing of the starting polymer and the imidizing agent.
Examples of the twin-screw extruder include non-intermeshing co-rotating, intermeshing co-rotating, non-intermeshing counter-rotating and intermeshing counter-rotating.

The extruders exemplified above may be used alone, or may be used by connecting a plurality of them in series.
In addition, the extruder to be used is equipped with a vent port that can be reduced to atmospheric pressure or less, because it is possible to remove the imidizing agent of the reaction, by-products such as methanol, or monomers. preferable.

In producing a methacrylic resin having a glutarimide structural unit, in addition to the imidization step, an esterification step of treating the carboxyl groups of the resin with an esterification agent such as dimethyl carbonate can be included. At that time, a catalyst such as trimethylamine, triethylamine or tributylamine may be used in combination for the treatment.
The esterification step can be advanced by using, for example, an extruder or a batch-type reaction tank, like the imidization step.
For the purpose of removing excessive esterifying agent, by-products such as methanol, or monomers, the apparatus used is preferably equipped with a vent port capable of reducing pressure to atmospheric pressure or lower.

The methacrylic resin that has undergone the imidization process and, if necessary, the esterification process, is melted and extruded into strands from an extruder equipped with a multi-hole die, and is subjected to cold cut, air hot cut, under water cut, etc. and processed into pellets.
Further, 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 resulting methacrylic resin solution is filtered, and then the organic solvent is devolatilized. It is also preferred to use a method.

Hereinafter, a method for producing a methacrylic resin containing a lactone ring structural unit (B-2) as the structural unit (B) having a ring structure in the main chain will be described in detail.

As the method for producing the methacrylic resin having the lactone ring structural unit (B-2) in the main chain in the present embodiment, solution polymerization using a solvent is preferable in terms of promoting the cyclization reaction. Here, the lactone ring structure may be formed by a cyclization reaction after polymerization.

Examples of the polymerization solvent to be used 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 singly or in combination of two or more.

The amount of solvent during polymerization is not particularly limited as long as it is a condition that allows polymerization to proceed and gelation can be suppressed. parts, more preferably 100 to 200 parts by mass.

In order to sufficiently suppress the gelation of the polymerization liquid and promote the cyclization reaction after polymerization, polymerization is carried out so that the concentration of the produced polymer in the reaction mixture obtained after polymerization is 50% by mass or less. is preferred.
Moreover, it is preferable to add a polymerization solvent to the reaction mixture as appropriate to control the content to 50% by mass or less. 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 may be added intermittently. The polymerization solvent to be added may be a single solvent of only one kind or a mixed solvent of two or more kinds.

The polymerization temperature is not particularly limited as long as it is a temperature at which polymerization proceeds.

The polymerization time is not particularly limited as long as the target conversion rate is satisfied, but from the viewpoint of productivity and the like, it is preferably 0.5 to 10 hours, more preferably 1 to 8 hours.

The polymerization conversion rate at the end of the polymerization of the methacrylic resin having a lactone ring structural unit in the main chain in the present embodiment is the polymerization conversion disclosed in the method for preparing a methacrylic resin having a structural unit derived from the N-substituted maleimide monomer. rate.

During the polymerization reaction, if necessary, a chain transfer agent may be added for polymerization.
As the 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 can be used. 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 are not particularly limited.
The amount of the chain transfer agent to be added is not particularly limited as long as the desired degree of polymerization can be obtained under the polymerization conditions used, but the total amount of the monomers used in the polymerization is preferably 100 parts by mass. 0.01 to 1 part by mass, preferably 0.05 to 0.5 part by mass.

The dissolved oxygen concentration in the polymerization solution may be, for example, the value disclosed in the method for preparing the methacrylic resin having structural units derived from the N-substituted maleimide monomer.
During the polymerization reaction, a polymerization initiator may be added for polymerization.
Although the polymerization initiator is not particularly limited, for example, the polymerization initiator disclosed in the method for preparing a methacrylic resin having a structural unit derived from the N-substituted maleimide monomer can be used.
These polymerization initiators may be used alone or in combination of two or more.

The amount of the polymerization initiator to be added may be appropriately set according to the combination of monomers, reaction conditions, etc., and is not particularly limited, but when the total amount of monomers used for polymerization is 100 parts by mass. In addition, it may be 0.01 to 1 part by mass, preferably 0.05 to 0.5 part by mass.

At the time of polymerization of the methacrylic resin having a lactone ring structural unit in the present embodiment, a polymerization initiator and, if necessary, a monomer are added during polymerization, and by controlling the amount added, the system during polymerization It is possible to reduce fluctuations in the ratio of the concentration of the monomer to the concentration of radicals in the polymer, suppress the formation of low-molecular-weight components in the final stages of polymerization, and improve colorability and moldability.

A methacrylic resin having a lactone ring structural unit in the present embodiment can be obtained, for example, by performing a cyclization reaction after completion of the polymerization reaction. Therefore, it is preferable to subject the polymerization reaction solution to the lactone cyclization reaction in a state containing the solvent without removing the polymerization solvent.
The copolymer obtained by polymerization is heat-treated to cause a cyclization condensation reaction between the hydroxyl group (hydroxyl group) and the ester group present in the molecular chain of the copolymer to form a lactone ring structure. to form
During the heat treatment for forming the lactone ring structure, a reaction apparatus equipped with a vacuum device or a devolatilization device, an extruder equipped with a devolatilization device, or the like can be used to remove alcohol that may be by-produced by cyclization condensation. .

When forming the lactone ring structure, if necessary, heat treatment may be performed using a cyclization condensation catalyst in order to promote the cyclization condensation reaction.
Specific examples of cyclization condensation catalysts include methyl phosphite, ethyl phosphite, phenyl phosphite, dimethyl phosphite, diethyl phosphite, diphenyl phosphite, trimethyl phosphite, Phosphite monoalkyl esters, dialkyl esters or triesters such as triethyl phosphate; methyl phosphate, ethyl phosphate, 2-ethylhexyl phosphate, octyl phosphate, isodecyl phosphate, lauryl phosphate, stearyl phosphate, phosphoric acid isostearyl phosphate, dimethyl phosphate, diethyl phosphate, di-2-ethylhexyl phosphate, diisodecyl phosphate, dilauryl phosphate, distearyl phosphate, diisostearyl phosphate, trimethyl phosphate, triethyl phosphate, triisodecyl phosphate, phosphoric acid monoalkyl esters, dialkyl esters or trialkyl esters such as trilauryl phosphate, tristearyl phosphate and triisostearyl phosphate;
These may be used alone or in combination of two or more.

The amount of the cyclization condensation catalyst used is not particularly limited. 1 part by mass.
If the amount used is less than 0.01 part by mass, the reaction rate of the cyclization condensation reaction may not be sufficiently improved. Conversely, if the amount of the catalyst used exceeds 3 parts by mass, the resulting polymer may be colored or the polymer may be crosslinked, making melt molding difficult.

The timing of addition of the cyclization condensation catalyst is not particularly limited. For example, it may be added at the beginning of the cyclization condensation reaction, during the reaction, or both. good.
It is also preferable to perform devolatilization at the same time when the cyclization condensation reaction is performed in the presence of a solvent.
The device used when the cyclization condensation reaction and the devolatilization step are performed at the same time is not particularly limited, but a devolatilization device consisting of a heat exchanger and a devolatilization tank, a vented extruder, or a devolatilization A device and an extruder arranged in series are preferred, and a vented twin-screw extruder is more preferred.
As the vented twin-screw extruder to be used, a vented extruder having a plurality of vent ports is preferable.

When using a vented extruder, the reaction treatment temperature is preferably 150 to 350°C, more preferably 200 to 300°C. If the reaction treatment temperature is lower than 150°C, the cyclization condensation reaction may be insufficient and the residual volatile matter may increase. Conversely, if the reaction treatment temperature exceeds 350° C., the resulting polymer may be colored or decomposed.
The degree of vacuum when using a vented extruder is preferably 10 to 500 Torr, more preferably 10 to 300 Torr. When the degree of vacuum exceeds 500 Torr, volatile matter tends to remain. Conversely, if the degree of vacuum is less than 10 Torr, industrial implementation may become difficult.

For the purpose of deactivating the remaining cyclization condensation catalyst during the cyclization condensation reaction, it is also preferable to add an alkaline earth metal and/or amphoteric metal salt of an organic acid during granulation.
Examples of alkaline earth metal and/or amphoteric metal salts of organic acids that can be used include calcium acetylacetate, calcium stearate, zinc acetate, zinc octylate, and zinc 2-ethylhexylate.

After passing through the cyclization condensation reaction process, the methacrylic resin is melted and extruded into strands from an extruder equipped with a multi-hole die, and processed into pellets by a cold cut method, an air hot cut method, and an underwater cut method. .
The lactonization for forming the lactone ring structural unit described above may be performed after the production of the resin and before the production of the resin composition (described later). It may be performed in conjunction with melt-kneading with.

The methacrylic resin in the present embodiment preferably has at least one ring structural unit selected from the group consisting of N-substituted maleimide monomer-derived structural units, glutarimide structural units, and lactone ring structural units. In particular, it is particularly preferable to have a structural unit derived from an N-substituted maleimide monomer, because optical properties such as photoelastic coefficient can be controlled to a high degree without blending with other thermoplastic resins.

(Methacrylic resin composition)
The methacrylic resin composition of the present embodiment contains the methacrylic resin of the present embodiment described above. The methacrylic resin composition may optionally contain additives in addition to the methacrylic resin of the present embodiment described above, and may also contain thermoplastic resins other than methacrylic resins, rubbery polymers etc., or may contain only a methacrylic resin.
The content of the methacrylic resin in 100% by mass of the methacrylic resin composition is preferably 50% by mass or more, more preferably 60% by mass or more, still more preferably 70% by mass or more, and particularly preferably 80% by mass. It is mass % or more.

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

--Antioxidant--
The methacrylic resin composition according to this embodiment preferably contains an antioxidant that suppresses deterioration and coloration during molding or during use.
Examples of the antioxidant include, but are not limited to, hindered phenol-based antioxidants, phosphorus-based antioxidants, sulfur-based antioxidants, and the like. The methacrylic resin of the present embodiment is suitably used in various applications such as melt extrusion, injection molding, and film molding. The heat history received during processing varies depending on the processing method, but it ranges from several tens of seconds for extruders to several tens of minutes to several hours for thick product molding and sheet molding. Various.
When subjected to a long heat history, it is necessary to increase the amount of heat stabilizer added in order to obtain the desired heat stability. From the viewpoint of suppressing the bleeding out of the heat stabilizer and preventing the film from sticking to the roll during film formation, it is preferable to use a plurality of types of heat stabilizers in combination, such as a phosphorus antioxidant and a sulfur antioxidant. It is preferable to use together at least one selected from the antioxidants and a hindered phenol-based antioxidant.
These antioxidants may be used singly or in combination of two or more.

Hindered phenol 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-butyl-4-hydroxy-m-tolyl)propionate ], hexamethylenebis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl) -1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 1,3,5-tris[(4-tert-butyl-3-hydroxy-2,6-xyline)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, 2-[1-(2-hydroxy-3,5-di-tert-pentylphenyl)ethyl]-4,6-di-tert-pentylphenyl acrylic acid, 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-t-butyl-4-hydroxyphenyl)propionate, 2-[1-(2-Hydroxy-3,5-di-tert-pentylphenyl)ethyl]-4,6-di-tert-pentylphenyl acrylate is preferred.

In addition, the hindered phenol-based antioxidant as the antioxidant may be a commercially available phenol-based antioxidant, and such a commercially available phenol-based antioxidant is limited to the following. However, 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), Irganox 3114 (Irganox3114: 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], manufactured by ADEKA), Adekastab AO-80 (3 , 9-bis{2-[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethyl}-2,4,8,10-tetraoxaspiro [5.5] Undecane, manufactured by ADEKA), Sumilizer BHT (Sumilizer BHT, manufactured by Sumitomo Chemical), Cyanox 1790 (Cyanox 1790, manufactured by Cytec), Sumilizer GA-80 (Sumilizer GA-80, manufactured by Sumitomo Chemical), Sumilizer GS (Sumilizer GS: 2-[1-(2-hydroxy-3,5-di-tert-pentylphenyl)ethyl]-4,6-di-tert-pentylphenyl acrylate, manufactured by Sumitomo Chemical), Sumilizer GM (Sumilizer GM: 2-tert-butyl-4-methyl-6-(2-hydroxy-3-tert-butyl-5-methylbenzyl)phenyl acrylate, manufactured by Sumitomo Chemical), vitamin E (manufactured by Eisai), and the like.
Among these commercially available phenolic antioxidants, Irganox 1010, Adekastab AO-60, Adekastab AO-80, Irganox 1076, Sumilizer GS, etc. are preferable from the viewpoint of the effect of imparting thermal stability to the resin.
These may be used individually by 1 type, or may be used in combination of 2 or more types.

Further, the phosphorus-based antioxidant as the antioxidant is not limited to the following, but for example, tris(2,4-di-t-butylphenyl)phosphite, bis(2,4- Bis(1,1-dimethylethyl)-6-methylphenyl)ethyl ester phosphorous acid, tetrakis(2,4-di-t-butylphenyl)(1,1-biphenyl)-4,4'-diylbisphosph 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'-diylbisphosphonite, di-t-butyl-m-cresyl- Phosphonite, 4-[3-[(2,4,8,10-tetra-tert-butyldibenzo[d,f][1,3,2]dioxaphosphepin)-6-yloxy]propyl]-2 -methyl-6-tert-butylphenol and the like.
Furthermore, a commercially available phosphorus antioxidant may be used as the phosphorus antioxidant, and examples of such commercially available phosphorus antioxidants include, but are not limited to, 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]dioxaphosphefin-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), ADEKA STAB PEP-8 (ADK STAB PEP-8, manufactured by ADEKA), ADEKA STAB HP-10 (ADK STAB HP-10, manufactured by ADEKA), ADEKA STAB 2112 (ADK STAB 2112, manufactured by ADEKA) ), ADEKA STAB 1178 (ADKA STAB 1178, made by ADEKA), ADEKA STAB 1500 (ADK STAB 1500, made by ADEKA), Sandstab P-EPQ (made by Clariant), Weston 618 (Weston 618, made by GE), Weston 619G (Weston 619G, made by GE ), Ultranox 626 (manufactured by GE), 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), HCA (9,10-dihydro-9-oxa-10-phosphaphenanthrene-10 - oxide, manufactured by Sanko Co., Ltd.) and the like.
Among these commercially available phosphorus-based antioxidants, Irgafos 168, Adekastab PEP-36, Adekastab PEP-36A, Adekastab HP from the viewpoint of the effect of imparting thermal stability to the resin and the effect of combined use with various antioxidants. -10 and Adekastab 1178 are preferred, and Adekastab PEP-36A and Adekastab PEP-36 are particularly preferred.
These phosphorus-based antioxidants may be used alone or in combination of two or more.

Further, the sulfur-based antioxidant as the antioxidant is not limited to the following, but for example, 2,4-bis(dodecylthiomethyl)-6-methylphenol (Irganox 1726, BASF ), 2,4-bis(octylthiomethyl)-6-methylphenol (Irganox 1520L, manufactured by BASF), 2,2-bis{[3-(dodecylthio)-1-oxoporopoxy]methyl}propane-1 ,3-diylbis[3-dodecylthio]propionate] (adekastab AO-412S, manufactured by ADEKA), 2,2-bis{[3-(dodecylthio)-1-oxoporopoxy]methyl}propane-1,3-diylbis[3 -dodecylthio]propionate] (Cheminox PLS, manufactured by Chemipro Kasei Co., Ltd.), di(tridecyl) 3,3′-thiodipropionate (AO-503, manufactured by ADEKA), and the like.
Among these commercially available sulfur antioxidants, Adekastab AO-412S and Cheminox PLS are preferred from the viewpoints of thermal stability imparting effect in the resin, combined effect with various antioxidants, and 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 is obtained, and if the content is excessive, problems such as bleeding out during processing may occur. Based on 100 parts by mass of the system resin, 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, even more preferably 0.8 parts by mass or less. It is preferably 0.01 to 0.8 parts by mass, particularly preferably 0.01 to 0.5 parts by mass.

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

--Hindered amine light stabilizer--
The methacrylic resin composition of this embodiment can contain a hindered amine light stabilizer.
Although the hindered amine light stabilizer is not particularly limited, it 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 aromatic rings, aliphatic rings, aromatic heterocycles and non-aromatic heterocycles, and two or more ring structures are contained in one compound. If so, they may be the same or different from each other.

Examples of the hindered amine light stabilizer include, but are not limited to, bis(1,2,2,6,6-pentamethyl-4-piperidyl)[[3,5-bis (1,1-dimethylethyl)-4-hydroxyphenyl]methyl]butylmalonate, bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and methyl 1,2,2,6,6 -pentamethyl-4-piperidyl sebacate mixture, 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 - polycondensation product of hexamethylenediamine and N-(2,2,6,6-tetramethyl-4-piperidyl)butylamine, poly[{6-(1,1,3,3-tetramethylbutyl)amino-1 ,3,5-triazine-2,4-diyl}{2,2,6,6-tetramethyl-4-piperidyl)imino}hexamethylene {(2,2,6,6-tetramethyl-4-piperidyl) imino}], tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl)butane-1,2,3,4-tetracarboxylate, tetrakis(2,2,6,6-tetramethyl-4 -piperidyl)butane-1,2,3,4-tetracarboxylate, 1,2,2,6,6-pentamethyl-4-piperidiol and β,β,β',β'-tetramethyl-2,4, 8,10-tetraoxaspiro[5.5]undecane-3,9-diethanol reactants, 2,2,6,6-tetramethyl-4-piperidiol and β,β,β',β'-tetramethyl -2,4,8,10-tetraoxaspiro[5.5]undecane-3,9-diethanol reactant, bis(1-undecanoxy-2,2,6,6-tetramethylpiperidin-4-yl) carbonate, 1,2,2,6,6-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 3 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-piperidiol and β,β,β',β'-tetramethyl-2,4,8,10-tetraoxaspiro[5.5]undecane-3,9-diethanol reactant , 2,2,6,6-tetramethyl-4-piperidiol and β,β,β',β'-tetramethyl-2,4,8,10-tetraoxaspiro[5.5]undecane-3,9 - the diethanol reactant is preferred.

The content of the hindered amine photostabilizer may be any amount as long as the effect of improving photostability can be obtained, and if the content is excessive, problems such as bleeding out during processing may occur. , with respect to 100 parts by mass of the methacrylic resin, 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, still more preferably 0.8 parts by mass or less, More preferably 0.01 to 0.8 parts by mass, particularly preferably 0.01 to 0.5 parts by mass.

--Ultraviolet absorber--
The methacrylic resin composition of this embodiment can contain an ultraviolet absorber.
Although the ultraviolet absorber is not particularly limited, it is preferably an ultraviolet absorber having a maximum absorption wavelength of 280 to 380 nm. Examples include benzotriazole compounds, benzotriazine compounds, benzophenone compounds, and oxybenzophenone compounds. , benzoate-based compounds, phenol-based compounds, oxazole-based compounds, cyanoacrylate-based compounds, benzoxazinone-based compounds, and the like.

Benzotriazole compounds include 2,2′-methylenebis[4-(1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazol-2-yl)phenol], 2-(3, 5-di-tert-butyl-2-hydroxyphenyl)-5-chlorobenzotriazole, 2-(2H-benzotriazol-2-yl)-p-cresol, 2-(2H-benzotriazol-2-yl)- 4,6-bis(1-methyl-1-phenylethyl)phenol, 2-benzotriazol-2-yl-4,6-di-tert-butylphenol, 2-[5-chloro(2H)-benzotriazole-2 -yl]-4-methyl-6-t-butylphenol, 2-(2H-benzotriazol-2-yl)-4,6-di-t-butylphenol, 2-(2H-benzotriazol-2-yl)- 4-(1,1,3,3-tetramethylbutyl)phenol, 2-(2H-benzotriazol-2-yl)-4-methyl-6-(3,4,5,6-tetrahydrophthalimidylmethyl) ) phenol, reaction product of methyl 3-(3-(2H-benzotriazol-2-yl)-5-t-butyl-4-hydroxyphenyl)propionate/polyethylene glycol 300, 2-(2H-benzotriazole-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)-5-(1,1-dimethylethyl)-4-hydroxy-C7-9 side chain and linear alkyl esters.
Among these, benzotriazole-based compounds having a molecular weight of 400 or more are preferable. registered trademark) 234 (manufactured by BASF).

Benzotriazine compounds include 2-mono(hydroxyphenyl)-1,3,5-triazine compounds, 2,4-bis(hydroxyphenyl)-1,3,5-triazine compounds, 2,4,6-tris (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-butoxyphenyl)-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-methoxyphenyl)-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-octyl oxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-4-dodecyloxyphenyl)-1,3,5-triazine, 2,4,6-tris( 2-hydroxy-4-benzyloxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-4-ethoxyethoxyphenyl)-1,3,5-triazine, 2,4, 6-tris(2-hydroxy-4-butoxyethoxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-4-propoxyethoxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-4-methoxycarbonylpropyloxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-4-ethoxycarbonylethyloxyphenyl)- 1,3,5-triazine, 2,4,6-tris(2-hydroxy-4-(1-(2-ethoxyhexyloxy)-1-oxopropan-2-yloxy)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-3-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-ethoxyethoxyphenyl)- 1,3,5-triazine, 2,4,6-tris(2-hydroxy-3-methyl-4-butoxyethoxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy -3-methyl-4-propoxyethoxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-3-methyl-4-methoxycarbonylpropyloxy phenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-3-methyl-4-ethoxycarbonylethyloxyphenyl)-1,3,5-triazine, 2,4,6- and tris(2-hydroxy-3-methyl-4-(1-(2-ethoxyhexyloxy)-1-oxopropan-2-yloxy)phenyl)-1,3,5-triazine.
As the benzotriazine-based compound, commercially available products may be used, for example, Kemisorb 102 (manufactured by Chemipro Kasei Co., Ltd.), LA-F70 (manufactured by ADEKA Corporation), LA-46 (manufactured by ADEKA Corporation), Tinuvin 405 (BASF Corporation). (manufactured by BASF), Tinuvin 460 (manufactured by BASF), Tinuvin 479 (manufactured by BASF), Tinuvin 1577FF (manufactured by BASF) and the like can be used.
Among them, 2,4-bis(2,4-dimethylphenyl)-6-[2-hydroxy-4-(3-alkyloxy -2-hydroxypropyloxy)-5-α-cumylphenyl]-s-triazine skeleton ("alkyloxy" means a long-chain alkyloxy group such as octyloxy, nonyloxy, decyloxy, etc.). It can be preferably used.

As the UV absorber, benzotriazole-based compounds and benzotriazine-based compounds having a molecular weight of 400 or more are preferable from the viewpoint of compatibility with resins and volatility when heated. Benzotriazine-based compounds are particularly preferred from the viewpoint of inhibiting decomposition by.

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

These ultraviolet absorbers may be used alone or in combination of two or more.
By using two types of ultraviolet absorbers having different structures together, it is possible to absorb ultraviolet rays in a wide wavelength range.

The content of the ultraviolet absorber is not particularly limited as long as it does not impair heat resistance, moist heat resistance, thermal stability, and molding processability, and is an amount that exhibits the effects of the present invention. It 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 even more preferably 0.3 to 3 parts by mass. Within this range, the balance between ultraviolet absorption performance, moldability, and the like is excellent.

--Release agent--
The methacrylic resin composition of this embodiment can contain a release agent. Examples of the release agent include, but are not limited to, fatty acid esters, fatty acid amides, fatty acid metal salts, hydrocarbon-based lubricants, alcohol-based lubricants, polyalkylene glycols, carboxylic acid esters, carbonized Hydrogen-based paraffinic mineral oils and the like are included.

Fatty acid esters that can be used as the release agent are not particularly limited, and conventionally known ones can be used.
Examples of fatty acid esters include fatty acids having 12 to 32 carbon atoms such as lauric acid, palmitic acid, heptadecanoic acid, stearic acid, oleic acid, arachidic acid and behenic acid, and monovalent acids such as palmityl alcohol, stearyl alcohol and behenyl alcohol. Ester compounds with fatty alcohols and polyhydric fatty alcohols such as glycerin, pentaerythritol, dipentaerythritol and sorbitan; Complex esters of fatty acids, polybasic organic acids and monohydric fatty alcohols or polyhydric fatty alcohols A compound or the like can be used.
Examples of such fatty acid ester-based lubricants include cetyl palmitate, butyl stearate, stearyl stearate, stearyl citrate, glycerin monocaprylate, glycerin monocaprate, glycerin monolaurate, glycerin monopalmitate, glycerin dipalmi. Tate, Glycerin Monostearate, Glycerin Distearate, Glycerin Tristearate, Glycerin Monooleate, Glycerin Dioleate, Glycerin Trioleate, Glycerin Monolinoleate, Glycerin Monobehenate, Glycerin Mono 12-Hydroxystearate, Glycerin Di-12-hydroxystearate, glycerin tri-12-hydroxystearate, glycerin diacetomonostearate, glycerin citric acid fatty acid ester, pentaerythritol adipate stearate, montanic acid partially saponified ester, pentaerythritol tetrastearate, dipenta Erythritol hexastearate, sorbitan tristearate and the like can be mentioned.
These fatty acid ester-based lubricants can be used singly or in combination of two or more.
Examples of commercially available products include Rikemal series, Poem series, Rikester series, Rikemaster series manufactured by Riken Vitamin Co., Ltd., Excel series manufactured by Kao Corporation, Rheodor series, Exceparl series, Coconard series, and more specific examples. Rikemar S-100, Rikemar H-100, Poem V-100, Rikemar B-100, Rikemar HC-100, Rikemar S-200, Poem B-200, Rikester EW-200, Rikester EW-400, Excel S -95, Rheodol MS-50 and the like.

Fatty acid amide-based lubricants are also not particularly limited, and conventionally known ones can be used.
Examples of fatty acid amide lubricants include saturated fatty acid amides such as lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, and hydroxystearic acid amide; unsaturated fatty acid amides such as oleic acid amide, erucic acid amide, and ricinoleic acid amide. fatty acid amides; substituted amides such as N-stearyl stearamide, 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; methylol Methylolamides such as stearamide and methylolbehenamide; Bishydroxystearic acid amide, ethylenebisbehenic acid amide, hexamethylenebisstearic acid amide, hexamethylenebisbehenic acid amide, hexamethylenebishydroxystearic acid amide, N,N'-distearyladipic acid amide, N,N'- Saturated fatty acid bisamides such as distearylsebacamide; unsaturated fatty acids such as ethylenebisoleic acid amide, hexamethylenebisoleic acid amide, N,N'-dioleyladipate, and N,N'-dioleylsebacic acid amide Bisamides; aromatic bisamides such as m-xylylenebisstearic acid amide and N,N'-distearyl isophthalic acid amide.
These fatty acid amide release agents can be used singly or in combination of two or more.
Examples of commercially available products include Diamid series (manufactured by Nippon Kasei Co., Ltd.), Amide series (manufactured by Nippon Kasei Co., Ltd.), Nikka Amide series (manufactured by Nippon Kasei Co., Ltd.), Methylolamide series, Bisamide series, and Slipax series (Nippon Kasei Co., Ltd.). Co., Ltd.), Kaowax series (manufactured by Kao Corporation), fatty acid amide series (manufactured by Kao Corporation), ethylenebisstearate amides (manufactured by Dainichi Chemical Industry Co., Ltd.), and the like.

Fatty acid metal salts refer to metal salts of higher fatty acids, 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, dibasic lead stearate, lead naphthenate, calcium 12-hydroxystearate, lithium 12-hydroxystearate, Among these, calcium stearate, magnesium stearate, and zinc stearate are particularly preferred because the resulting transparent resin composition has excellent processability and extremely excellent transparency.
Examples of commercially available products include SZ series, SC series, SM series, SA series manufactured by Sakai Chemical Industry Co., Ltd., and the like.
When using the fatty acid metal salt, the content is preferably 0.2% by mass or less with respect to 100% by mass of the methacrylic resin composition from the viewpoint of maintaining transparency.
The release agents may be used singly or in combination of two or more.

The release agent to be used preferably has a decomposition initiation temperature of 200° C. or higher. Here, the decomposition initiation temperature can be measured by the 1% weight loss temperature by TGA.
The content of the release agent may be any amount as long as it is effective as a release agent. If the content is excessive, problems such as bleeding out during processing and extrusion failure due to screw slippage will occur. Therefore, 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. parts by mass or less, more preferably 0.01 to 0.8 parts by mass, particularly preferably 0.01 to 0.5 parts by mass. When added in an amount within the above range, a decrease in transparency due to the addition of a mold release agent is suppressed, and mold release failure during injection molding and sticking to metal rolls during sheet molding tend to be suppressed. preferable.

- Other thermoplastic resins -
The methacrylic resin composition of the present embodiment may contain a thermoplastic resin other than the methacrylic resin for the purpose of adjusting the birefringence and improving flexibility without impairing the object of the present invention.
Other thermoplastic resins include, 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; etc., acrylic rubber particles having a three- to four-layer structure; JP-B-60-17406, a rubbery polymer disclosed in JP-A-8-245854; , methacrylic rubber-containing graft copolymer particles obtained by multistage polymerization;
Among these, from the viewpoint of obtaining good optical properties and mechanical properties, it is preferable to use a composition compatible with a styrene-acrylonitrile copolymer or a methacrylic resin containing a structural unit (X) having a ring structure in the main chain. A rubber-containing graft copolymer particle having a graft portion on its surface layer is preferred.
The average particle size of the acrylic rubber particles, the methacrylic rubber-containing graft copolymer particles, and the rubbery polymer mentioned above enhances the impact strength, optical properties, etc. of the molded article obtained from the composition of the present embodiment. From the point of view, it is preferably 0.03 to 1 μm, more preferably 0.05 to 0.5 μm.

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

(Method for producing methacrylic resin composition)
Examples of the method for producing the methacrylic resin composition include a method of kneading using a kneader such as an extruder, a heating roll, a kneader, a roller mixer, or a Banbury mixer. Among them, kneading by an extruder is preferable in terms of productivity. The kneading temperature may follow the preferred processing temperature of the polymer constituting the methacrylic resin and other resins to be mixed, and is generally in the range of 140 to 300.degree. Also, the extruder is preferably provided with a vent port for the purpose of reducing volatile matter.
The glass transition temperature (Tg), weight average molecular weight (Mw), and number average molecular weight (Mn) for the methacrylic resin composition may be the same as those described above for the methacrylic resin.

(Molded body)
The molded article of the present embodiment may contain the methacrylic resin of the present embodiment, or may contain the methacrylic resin composition of the present embodiment.

(Method for manufacturing molded body)
The method for producing a molded article of the present embodiment includes irradiating a molded article made of the methacrylic resin composition with light having a wavelength of 200 to 480 nm.

Various molding methods such as extrusion molding, injection molding, compression molding, calender molding, inflation molding, and blow molding can be used as the method for producing the molded article of the present embodiment. Among them, it is preferable to apply injection molding and injection compression molding from the viewpoint of productivity.
In general, the injection molding method consists of (1) an injection process in which the resin is melted and filled into the temperature-controlled cavity of the mold, and (2) pressure is applied to the cavity until the gate is sealed, and the injection process fills the cavity. (3) After releasing the holding pressure, the cooling step of holding the molded body until the resin is cooled, ( 4) It consists of a step of opening the mold and taking out the cooled compact.

At this time, the molding temperature is in the range of Tg+100° C. to Tg+160° C., preferably in the range of Tg+110° C. to Tg+150° C., based on the glass transition temperature of the methacrylic resin composition. Here, the molding temperature refers to the controlled temperature of the band heater wound around the injection nozzle.
The mold temperature is in the range of Tg-70°C to Tg, preferably in the range of Tg-50°C to Tg-20°C, based on the glass transition temperature (Tg) of the methacrylic resin composition. preferable.

Also, the injection speed can be appropriately selected depending on the thickness and dimensions of the injection molded article to be obtained, and can be appropriately selected, for example, from the range of 200 to 1000 mm/sec.
Further, the pressure for holding pressure can be appropriately selected depending on the shape of the injection molded article to be obtained, and can be appropriately selected within the range of, for example, 30 to 120 MPa. In the case of a thin molded body with a high solidification speed, there is a case where no holding pressure is applied.
Here, the pressure for holding pressure is the pressure held by the screw for further sending out the molten resin from the gate after the molten resin is filled.

Injection compression molding involves opening the mold slightly at the start of injection molding and filling the mold with molten resin at high speed and low pressure. It is an injection molding method in which a compression and holding pressure step is added, and it is possible to mold a molded product with excellent surface characteristics and optical characteristics.
When it is desired to obtain a thinner injection-molded article, for example, a thickness of less than 1 mm and a diagonal dimension of more than 100 mm, injection compression molding is employed to obtain a molded article having excellent optical characteristics and color tone. It is particularly preferred because it can be obtained.

Moreover, when the injection-molded article obtained using the above methacrylic resin composition is used as a light guide plate, the article may have fine irregularities formed on its surface. By providing such fine unevenness, it is preferable that there is no need to separately provide a reflective layer by printing or the like. Fine unevenness is not particularly limited, but unevenness with clear structural units such as cuboids, cylinders, elliptical cylinders, triangular prisms, spherical surfaces, and aspherical surfaces, and uneven shapes such as satin and hairline shapes, Concavities and convexities whose structural units are unclear or a combination thereof, and concavities and convexities whose structural units are clear but whose shapes, particularly sizes, are varied. As for the shape of the unevenness, the height of the shape or the concave portion is 0.1 to 500 μm, and the pitch distance between the unevenness is 10 to 1000 μm.

Surface functionalization treatments such as antireflection treatment, transparent conductive treatment, electromagnetic wave shielding treatment, and gas barrier treatment can be further applied to various molded articles using the methacrylic resin of the present embodiment and its resin composition.

-light irradiation-
The step of irradiating with light having a wavelength of 200 to 480 nm in the method for producing a molded article according to this embodiment will be described.
Although the mechanism by which light irradiation improves the transmittance (spectral transmittance) of the molded body and improves the color tone is not clear, the colored component in the molded body absorbs the irradiated light, and the colored component is considered to be due to the change to a non-colored component due to the photoreaction. That is, by irradiating light with a wavelength of 200 to 480 nm, which is the absorption region of the coloring component of the molded body, in order to cause a photoreaction, the yellowness YI value of the 80 mm optical path length of the molded body is reduced, and the transmittance is improved. It is presumed that it is possible to easily obtain a molded product with improved color tone.

Examples of a molded article whose yellowness YI value is reduced (for example, the YI value is reduced by 1 or more) and whose transmittance is improved by irradiation with light include the above-described molded article. Among them, as described above, the above-described methacrylic acid ester is used as the structural unit (A), the content of the structural unit (A) is 50% by mass or more, and the structural unit (B) is a structural unit Using any one of (B-1), (B-2) and (B-3) (for example, using structural units represented by formulas (1) and (2)), content of structural unit (B) is 3 to 40% by mass, and the content of the methacrylic resin is 50% by mass or more, so that the yellowness YI value of the molded body is further reduced by light irradiation, and the transmittance is further improved. easier to do.

The integrated amount of light to be irradiated is preferably in the range of 0.001 to 100 W·hr/mm ² . If the integrated amount of light is lower than 0.001 W·hr/mm ² , the photoreaction does not proceed sufficiently and the color tone is not sufficiently improved. In addition, when the integrated light intensity is higher than 100 W·hr/mm ² , part of the absorbed light becomes heat energy and deactivates, but photoreaction and heat reaction cause deterioration of the resin itself and new coloring components. There is a risk that the decrease in transmittance will compete with the improvement in color tone, resulting in a decrease in color tone. The integrated amount of light is more preferably 0.005 to 50 W·hr/mm ² , still more preferably 0.01 to 10 W·hr/mm ² . However, if light with extremely high energy density is irradiated for a very short time, there is a risk that the resin will deteriorate due to excessive heat generation, even though it is momentary. In the case of irradiation, the photoreaction that would contribute to the improvement of color tone may not be activated and a sufficient color tone improvement effect may not be obtained. A range of ² is preferred. The integrated light amount and energy density preferably satisfy the above ranges at least at the surface where light enters (light incident surface), and the above ranges can be satisfied at the light incident surface and at a position 80 mm from the light incident surface in the irradiation direction. More preferably, the above range is satisfied in the entire irradiation direction from the light incident surface to the light exit surface.
The integrated light amount can be measured using an integrated photometer using a photodiode, a power meter, or the like. Since the integrated amount of light is the time (hr) integral value of the radiation density (energy density, W/ ^{mm 2} ), if the radiant flux (W) can be measured, the energy density is obtained, and the integrated amount of light is obtained according to the irradiation time. Regarding the specific position for measuring the integrated light intensity, by measuring the amount of radiant flux after passing through the 80 mm molded piece in consideration of the divergence angle of the irradiated light, at least the integrated amount of light irradiated to the entire molded piece can be estimated as
In the light irradiation described above, the light output is preferably constant during irradiation, but may be varied. When changing the light output, there is no problem if the irradiation time is adjusted so that the integrated light quantity of the irradiated light satisfies the above range. The light may be irradiated from multiple directions, or may be irradiated from one direction. In the case of light with a large spread angle (for example, 45° or more), it is preferable to irradiate the surface with the largest surface area of the molded body (for example, in the thickness direction in FIG. 1).

From the standpoint of productivity, it is preferable to set the light irradiation time in the range of about 1 to 24 hours, and the light output may be adjusted so that the integrated light amount falls within the above range. In addition, light irradiation may be performed continuously or discontinuously, but from the viewpoint of efficiency, it is preferably performed continuously. Even when the light is discontinuously irradiated, the total cumulative amount of light preferably satisfies the above range.

The light with which the molded article is irradiated contains at least light with a wavelength of 200 to 480 nm. The light may be light of a single wavelength or may include light of multiple wavelengths. For example, single-wavelength or multiple-wavelength light within the range of 200-480 nm, and light including single-wavelength or multiple-wavelength light outside the range of 200-480 nm. Among them, light having a single wavelength within the range of 200 to 480 nm is preferable from the viewpoint of easily obtaining a stable effect.
The light to be irradiated may be light in the ultraviolet region, but even in the ultraviolet region, light having a wavelength of 315 to 480 nm may cause decomposition or coloring of the resin molding depending on the light on the shorter wavelength side. (For example, light with a single wavelength within the wavelength range of 315 to 480 nm, etc.) is preferably irradiated. In addition, even with light on the long wavelength side of the ultraviolet region, the coloring of the resin molding may offset the improvement of the color tone, so light including the visible light region with a wavelength of 400 to 480 nm It is more preferable to irradiate with light of a single wavelength within the range of ~480 nm. Further, in order to reduce the above-mentioned coloring due to ultraviolet rays as much as possible, for example, it is possible to select a light source for irradiation so as not to include light with a wavelength of less than 400 nm, or to combine a filter that cuts off wavelengths in the ultraviolet region. .
Among the wavelengths of light to be irradiated, light having a wavelength longer than 480 nm may be included, and although there is almost no effect on the color tone of wavelengths longer than 480 nm, the temperature of the resin molding itself is affected by the irradiation of light in the infrared region. increases, and if the temperature rise is high, heat-induced deterioration of color tone may occur.

For the purpose of promoting the photoreaction, the temperature of the molded article when irradiated with light should be in the range of 20° C. or higher and 20° C. or lower than the glass transition temperature of the methacrylic resin composition constituting the molded article. It is preferable to perform light irradiation while heating. By irradiating with light at the above temperature, the photoreaction is promoted, and a sufficient color tone improving effect can be obtained in a shorter time. Annealing treatment is usually applied to the molded product for the purpose of removing residual stress. By performing light irradiation at the same time as the annealing treatment, the effect of removing the residual stress and improving the color tone can be obtained.
Even if the temperature for heating the molded article is lower than 20°C, a certain color tone improvement effect can be obtained, but there is a possibility that sufficient color tone improvement cannot be expected unless the light is irradiated for a longer time. On the other hand, if light irradiation is performed while heating to a temperature higher than 20° C. lower than the glass transition temperature, the molded body will be heated to a temperature above the glass transition region, resulting in a problem that the shape of the molded body cannot be maintained. .
For example, when irradiating with light in the infrared region, it can be used without problems by adjusting the temperature of the molded article to be 20° C. lower than the glass transition temperature, taking into consideration the influence of heating. Although the effect of improving the color tone can be obtained with only light without heating, it is considered that the effect of improving the color tone can be obtained in a short time by irradiating light while heating to some extent, which is preferable from the viewpoint of productivity. , the temperature can be appropriately selected within a temperature range from about 20°C to 20°C or more lower than the glass transition temperature of the methacrylic resin molding, depending on the usage conditions.
The temperature is preferably 30° C. or higher and 25° C. lower than the glass transition temperature of the methacrylic resin composition, and more preferably 40° C. or higher and 30° C. lower than the glass transition temperature.

Natural light such as sunlight or an artificial light source can be appropriately selected as the light source used for light irradiation in the present invention. Examples of artificial light sources include incandescent lamps, fluorescent lamps, halogen lamps, mercury lamps, metal halide lamps, xenon lamps, LEDs, lasers, and the like. Of these, blue LEDs and blue lasers are preferable from the viewpoint of irradiating only blue light with a wavelength of 400 to 480 nm, for example, and the light sources can be used in appropriate combinations in consideration of the shape of the molded body and the acceleration of the reaction due to heating. can also
If the temperature rise of the molded body due to light irradiation becomes a problem, it is possible to maintain the shape of the molded body and deteriorate the color tone due to the temperature above the glass transition region by installing an infrared cut filter or providing a cooling mechanism such as air cooling or water cooling. can be suppressed.

In the molded article obtained by the production method of the present embodiment, the yellowness YI value of the molded article after light irradiation at an optical path length of 80 mm is reduced by 1 or more from the yellowness YI value before light irradiation. A decrease of 2 or more is more preferable, and a decrease of 3 or more is even more preferable.
The YI value before and after light irradiation can be measured by the method described in Examples below.

The molded article obtained by the manufacturing method of this embodiment has excellent permeability. The transmittance of the molded body after light irradiation is preferably improved by 3% or more, more preferably by 6% or more, at least at one wavelength with respect to the transmittance before light irradiation. , is more preferably improved by 9% or more. The wavelength at which the transmittance is improved is preferably a low wavelength (for example, any wavelength from 400 to 480 nm or all wavelengths from 400 to 480 nm).
The transmittance (optical transmittance) before and after light irradiation can be measured by the method described in Examples below.

(Application of methacrylic resin molding)
According to the method for producing a molded article with improved color tone of the present embodiment, it is possible to obtain a molded article made of a methacrylic resin composition having low birefringence, excellent heat resistance, and improved transmittance while maintaining transparency. It can be suitably used for applications such as optical members in household goods, OA equipment, AV equipment, battery electrical components, lighting equipment, automobiles, and the like.
Optical members in household goods, OA equipment, AV equipment, battery electrical components, lighting equipment, etc. include, for example, smartphones, PDAs, tablet PCs, light guide plates used in displays such as liquid crystal televisions, display front plates, touch panels, and more. Lenses for smartphones, tablet PC cameras, etc., optical lens parts for head-mounted displays, liquid crystal projectors, etc., such as prism elements, waveguides, lenses, especially small thin and uneven thickness optical lenses, optical fibers, optical fiber coating materials , lenses, Fresnel lenses, phase plates with microlens arrays, optical cover components, and the like.
Optical parts for automobiles include light guide plates for in-vehicle displays; in-vehicle meter panels; front panels of car navigation systems, combiners, optical parts for head-up displays such as optical cover parts; in-vehicle camera lenses, light guide bars, etc. .
In addition to the above, it can also be used as parts for digital signage display devices that transmit information to thin displays connected to networks for the purpose of publicity, advertising, etc., in places such as camera focal plates, outdoors, stores, public institutions, and transportation facilities. It can be preferably used.

EXAMPLES Hereinafter, the content of the present invention will be specifically described with reference to examples and comparative examples. In addition, the present invention is not limited to the following examples.

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

<2. Analysis of Structural Units>
By ¹ H-NMR measurement and ¹³ C-NMR measurement, the structural unit of the produced methacrylic resin was identified and its abundance was calculated. The measurement conditions for ¹ H-NMR measurement and ¹³ C-NMR measurement are as follows.
・Measurement equipment: DPX-400 manufactured by Bruker
・Measurement solvent: CDCl ₃ or DMSO-d ₆
・Measurement temperature: 40°C

<3. Measurement of molecular weight and molecular weight distribution>
The weight-average molecular weight (Mw) and number-average molecular weight (Mn) of the methacrylic resins produced in Examples and Comparative Examples described later were measured using the following equipment and conditions.
・ Measuring device: Gel permeation chromatography (HLC-8320GPC) manufactured by Tosoh Corporation
·Measurement condition:
Columns: One TSKguard column SuperH-H, two TSKgel SuperHM-M, and one TSKgel SuperH2500 were connected in series and used. Column temperature: 40°C
Developing solvent: tetrahydrofuran, flow rate: 0.6 mL/min, 0.1 g/L of 2,6-di-t-butyl-4-methylphenol (BHT) was added as an internal standard.
Detector: RI (differential refraction) detector, detection sensitivity: 3.0 mV/min Sample: 0.02 g of methacrylic resin or tetrahydrofuran solution of methacrylic resin in 20 mL. Injection volume: 10 μL
Standard sample for calibration curve: The following 10 types of polymethyl methacrylate (manufactured by Polymer Laboratories; PMMACalibration Kit MM-10) with known monodisperse weight peak molecular weights and different molecular weights were used.
Weight peak molecular weight (Mp)
Standard sample 1 1,916,000
Standard sample 2 625,500
Standard sample 3 298,900
Standard sample 4 138,600
Standard sample 5 60,150
Standard sample 6 27,600
Standard sample 7 10,290
Standard sample 8 5,000
Standard sample 9 2,810
Standard sample 10 850
Under the above conditions, the RI detection intensity was measured with respect to the elution time of the methacrylic resin.
The weight average molecular weight (Mw) and number average molecular weight (Mn) of the methacrylic resin and the methacrylic resin were determined based on the calibration curve obtained by measuring the standard sample for the calibration curve.

<4. Glass transition temperature>
The glass transition temperature (Tg) (°C) of the methacrylic resin was measured according to JIS-K7121.
First, from a sample that had been conditioned under standard conditions (23° C., 65% RH) (left at 23° C. for 1 week), 4 points (4 locations) were cut out of about 10 mg each as test pieces.
Next, a differential scanning calorimeter (Diamond DSC manufactured by PerkinElmer Japan Co., Ltd.) was used under the condition of a nitrogen gas flow rate of 25 mL / min, where the temperature was raised from room temperature (23 ° C.) to 200 ° C. at 10 ° C. / min. After heating (primary temperature rise) and holding at 200 ° C. for 5 minutes to completely melt the sample, the temperature was lowered from 200 ° C. to 40 ° C. at 10 ° C./min, held at 40 ° C. for 5 minutes, and further , Among the DSC curves drawn during the temperature increase (secondary temperature increase) under the above temperature increase conditions, the stepwise change partial curve at the time of the secondary temperature increase and the extension of each baseline are equidistant in the vertical axis direction The point of intersection with a straight line (midpoint glass transition temperature) was measured as the glass transition temperature (Tg) (°C). Measurement was performed at 4 points per sample, and the arithmetic average of the 4 points (rounded off to the nearest whole number) was used as the measured value.

<5. Measurement of Composition Distribution of Structural Units>
The methacrylic resins obtained in Examples and Comparative Examples were subjected to molecular weight fractionation under the following equipment and conditions.
・Preparation device: LC-908 manufactured by Nippon Analytical Industry Co., Ltd.
・Preparation conditions:
Column: SHODEX K-2004
Eluent: chloroform, flow rate: 3 mL/min Detector: UV detector (254 nm)
Sample: 3% by mass chloroform solution Fractionation method: 3 mL of sample was injected and fractionated at 1-minute intervals during the elution time of 18 to 43 minutes.
The fractionation operation was repeated three times, and a sample selected from the obtained fractions was subjected to the above <2. Analysis of Structural Units>, the composition ratio of the structural units is obtained according to <3. Measurement of Molecular Weight and Molecular Weight Distribution>, and the peak top molecular weight (Mp) was obtained from the position of the peak apex.

<6. Measurement of color tone of injection molded piece>
Using the methacrylic resin obtained in the example, an injection molding machine (AUTO SHOT C Series MODEL 15A, manufactured by FANUC Co., Ltd.) is used to obtain a strip molded piece as shown in FIG. Injection molding was performed using a strip mold of 4 mm×10 mm width×80 mm length. First, the cylinder temperature was 250°C, the mold temperature was 90°C, and the cooling time was 20 seconds. . Next, injection molding was performed at an injection pressure of SSP+50 kgf/cm ² to obtain strip moldings for color tone measurement.
Using a long optical path spectroscopic transmission colorimeter ASA1 manufactured by Nippon Denshoku Industries Co., Ltd., the spectral transmittance and yellowness index YI of the obtained strips were measured at a wavelength of 400 to 700 nm at a long optical path of 80 mm. Changes in spectral transmittance and changes in yellowness index YI were used as indicators for evaluating the improvement in color tone of methacrylic resin moldings by light irradiation. The yellowness YI can be obtained from the tristimulus values X, Y, and Z by the formula YI=100 (1.28X-1.06Z)/Y using a spectral transmission colorimeter according to JIS K7105.

[material]
Raw materials used in production examples described later are shown below.
[[monomer]]
・Methyl methacrylate: manufactured by Asahi Kasei Corporation ・N-Phenylmaleimide (phMI): manufactured by Nippon Shokubai Co., Ltd. ・N-Cyclohexylmaleimide (chMI): manufactured by Nippon Shokubai Co., Ltd. [[polymerization initiator]]
・ 1,1-di (t-butylperoxy) cyclohexane: "Perhexa C" manufactured by NOF Corporation
[[chain transfer agent]]
・ n-octyl mercaptan: manufactured by Kao Corporation

[Example 1]
358.6 kg of methyl methacrylate (hereinafter referred to as MMA), 29.4 kg of N-phenylmaleimide (hereinafter referred to as phMI), 67.7 kg of N-cyclohexylmaleimide (hereinafter referred to as chMI), and n-octyl mercaptan as a chain transfer agent. 0.77 kg and 224.3 kg of meta-xylene (hereinafter referred to as mXy) were weighed, added to a 1.25 m 3 reactor equipped with a jacket temperature control device and stirring blades, and stirred to obtain a mixed monomer solution.
Then, 88.0 kg of MMA, 6.3 kg of phMI and 142.4 kg of mXy were weighed and added to tank 1 and stirred to obtain a mixed monomer solution for addition.
The contents of the reactor were bubbled with nitrogen at a rate of 30 L/min for 1 hour, and the tank 1 was bubbled with nitrogen at a rate of 10 L/min for 30 minutes to remove dissolved oxygen.
After that, steam was blown into the jacket to raise the temperature of the solution in the reactor to 115° C., and while stirring at 50 rpm, 0.487 kg of 1,1-di(t-butylperoxy)cyclohexane was dissolved in 1.888 kg of mXy. Polymerization was initiated by adding the polymerization initiator solution obtained at a rate of 1.0 kg/hour.
During the polymerization, the temperature of the solution in the reactor was controlled at 115±2° C. by adjusting the temperature with a jacket. Thirty minutes after the start of the polymerization, the initiator solution addition rate was reduced to 0.5 kg/h. Over 4 hours from 1 hour after the start of the polymerization, the total amount of the additional mixed monomer solution was added from the tank 1 at a constant rate.
Furthermore, the addition rate of the initiator solution was reduced to 0.25 kg/hour after 3.5 hours from the start of polymerization, and the addition was stopped after 5 hours from the start of polymerization.
Twelve hours after the initiation of polymerization, a polymer solution containing a methacrylic resin having a structural unit having a ring structure in its main chain was obtained.
After 2 hours and 12 hours from the start of polymerization, the polymer solution was sampled and the polymerization conversion rate was analyzed from the remaining monomer concentration. As a result, the polymerization conversion rate after 2 hours was 78.9% of MMA , phMI 77.3%, chMI 70.4%, and after 12 hours, MMA 97.9%, phMI 99.4%, chMI 99.3%. Considering the monomers added after 2 hours from the start of polymerization, the polymerization conversion rate after 2 hours was converted into the consumption rate with respect to the total amount of each monomer added by the end of the polymerization, MMA 67.2%, pHMI 67. .1%, chMI 70.4%.
This polymer solution was devolatilized by supplying it to a concentrating device consisting of a tubular heat exchanger preheated to 250° C. and a vaporization tank. The degree of vacuum in the vaporization tank was set to 10 to 15 Torr. The resin flowing down the vaporization tank was discharged with a gear pump, extruded through a strand die, cooled with water, and pelletized to obtain a methacrylic resin.
When the composition of the obtained pellet-shaped polymer was confirmed, the structural units derived from MMA, phMI, and chMI monomers were 81.0% by mass, 6.6% by mass, and 12.4% by mass, respectively. there were. Moreover, the weight average molecular weight was 108,000 and Mw/Mn was 2.04. The glass transition temperature was 134°C. Further, the measurement results of the composition distribution of structural units are Mp: 253,000 (MMA: 81.4% by mass, phMI: 6.5% by mass, chMI: 12.1% by mass), Mp: 176,000 (MMA: 81.1% by mass, phMI: 6.6% by mass, chMI: 12.3% by mass), Mp: 111,000 (MMA: 80.9% by mass, phMI: 6.7% by mass, chMI: 12.4 %), Mp: 88,000 (MMA: 80.8% by mass, phMI: 6.7% by mass, chMI: 12.5% by mass), Mp: 48,000 (MMA: 80.4% by mass, phMI : 6.8% by mass, chMI: 12.8% by mass).
Using the obtained methacrylic resin, strips were molded by injection molding. The spectral transmittance at a wavelength of 400 to 700 nm and the yellowness index YI were measured at a long optical path of 80 mm, and the initial values (YI=13.3) before light irradiation were used. Subsequently, the strip-molded piece is fixed on a heater block at 85°C and heated, and a blue laser with a wavelength of 450 nm (PL TB450B manufactured by Osram) is irradiated on the incident surface side of about 3 mm ² with a long optical path of 80 mm. Positioning was performed so as to have an area, and a laser was emitted with an applied current of 200 mA (FIG. 2). The light output at this time was about 0.1 W when a photodiode was installed on the light output side and measured, and the light irradiation density for the strip molded piece was about 0.1 W/3 mm ² on the light input side. 0.033 W/mm ² and 0.1 W/40 mm ² =about 0.0025 W/mm ² on the exit side. After continuous irradiation for 24 hours, the strip-shaped piece was once taken out (accumulated light amount: 0.06 to 0.8 W·hr/mm ² ), and the optical transmittance and yellowness YI were measured at a wavelength of 400 to 700 nm with a long optical path of 80 mm. , and the measured value (YI=10.8) after light irradiation. As a result, the yellowness YI was improved by 13.3-10.8=2.5. Also, when the spectrum was confirmed, it was found that the transmittance was particularly improved in the short wavelength range of 400 to 480 nm (FIG. 4). Among 400 to 480 nm, the most improved transmittance was at 420 nm, which was about 3.9% higher than the transmittance before light irradiation.

[Example 2]
The strip molded piece was irradiated with light in the same manner as in Example 1, except that the light output of the laser was changed to about 0.4W. The spectral transmittance at a wavelength of 400 to 700 nm and the yellowness index YI were measured at a long optical path of 80 mm, and the initial values (YI=12.1) before light irradiation were used. After continuous irradiation for 24 hours, the strip was once taken out (0.24 to 3.2 W·hr/mm ² as an integrated light quantity), and the optical transmittance and yellowness YI were measured at a wavelength of 400 to 700 nm in a long optical path of 80 mm, The measured value (YI=6.2) after light irradiation was used. As a result, the yellowness YI was improved by 12.1-6.2=5.9. Also, when the spectrum was confirmed, it was found that the transmittance was particularly improved in the short wavelength range of 400 to 480 nm (FIG. 5). Among 400 to 480 nm, the most improved transmittance was at 400 nm, which was about 13.3% higher than the transmittance before light irradiation.

[Example 3]
The light source was changed from laser to LED (B3838 manufactured by GENERITES, wavelength λ450 to 460 nm), and the strip-shaped piece was irradiated with light in the same manner as in Example 1 except that irradiation was performed under the following conditions (Fig. 3). At this time, the light output of the LED at an applied current of 200 mA was approximately 0.045 W. In addition, the light spread angle of the LED is larger than that of the laser, and the entire light incident surface (approximately 40 mm ² ) is irradiated with the light. The spectral transmittance at a wavelength of 400 to 700 nm and the yellowness index YI were measured at a long optical path of 80 mm, and the initial values (YI=12.0) before light irradiation were used. After continuous irradiation for 24 hours, the strip was once taken out (at least about 0.027 W·hr/mm ² as the integrated amount of light on the light incident surface), and the optical transmittance and yellowness YI were measured at a wavelength of 400 to 700 nm with a long optical path of 80 mm. and the measured value (YI=9.1) after light irradiation. As a result, the yellowness YI was improved by 12.0-9.1=2.9. Further, when the spectrum was confirmed, it was found that the transmittance was particularly improved in the short wavelength range of 400 to 480 nm (FIG. 6). Among 400 to 480 nm, the most improved transmittance was at 420 nm, which was about 5.8% higher than the transmittance before light irradiation.

[Comparative example]
Strips were produced from the methacrylic resin composition by injection molding in the same manner as in the Examples, fixed on a heater block at 85° C. without light irradiation, and heated for 24 hours. When the spectral transmittance and yellowness YI at a wavelength of 400 to 700 nm at a long optical path of 80 mm before and after heating were measured, the yellowness YI was YI = 12.3 before heating and YI = 12.2 after heating (change in YI: 12 .3-12.2=0.1) and no change was observed. Even when the spectrum was confirmed, almost no change in the transmission spectrum was observed in the range from 400 to 700 nm (Fig. 7).

The methacrylic resin of the present embodiment has high heat resistance, and birefringence is highly controlled when the methacrylic resin and its composition are injection molded. It can be suitably used for optical parts such as light plates, light guide plates for in-vehicle displays; in-vehicle meter panels; car navigation front panels, combiners, optical cover parts and other optical parts for head-up displays.

According to the production method of the present invention, a molded article having high heat resistance, highly controlled birefringence, and excellent transparency can be obtained.
The molded article obtained by the production method of the present invention can be used as an optical member in household goods, OA equipment, AV equipment, battery electrical components, lighting equipment, etc. For example, it is used in displays such as smartphones, PDAs, tablet PCs, and liquid crystal televisions. Used light guide plate, display front plate, touch panel, smart phone, tablet PC camera lens, etc., optical lens parts such as head mounted display and liquid crystal projector, such as prism element, waveguide, lens, especially small thin polarized Examples include flesh-shaped optical lenses, optical fibers, coating materials for optical fibers, lenses, Fresnel lenses, phase plates with microlens arrays, optical cover parts, and the like.
Optical parts for automobiles include light guide plates for in-vehicle displays; in-vehicle meter panels; front panels of car navigation systems, combiners, optical parts for head-up displays such as optical cover parts; in-vehicle camera lenses, light guide bars, etc. .
In addition to the above, it can also be used as parts for digital signage display devices that transmit information to thin displays connected to networks for the purpose of publicity, advertising, etc., in places such as camera focal plates, outdoors, stores, public institutions, and transportation facilities. It can be preferably used.

Claims (4)

irradiating a molded body made of a methacrylic resin composition containing a methacrylic resin containing a structural unit having a ring structure in its main chain with light having a wavelength of 200 to 480 nm ,
The integrated light amount of the light to be irradiated is 0.005 W hr/mm ² or more and 100 W hr/mm ² or less ,
A method for producing a molded article. The method for producing a molded article according to claim 1 , wherein the wavelength is 315 to 480 nm. 3. The method for producing a molded article according to claim 1, wherein the wavelength is 400-480 nm. 4. The molded body according to any one of claims 1 to 3 , wherein the temperature of the molded article when irradiated with light is 20°C or higher and 20°C or lower than the glass transition temperature of the methacrylic resin composition. A method for producing a molded article.

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