JP7025906B2 - Manufacturing method of methacrylic resin - Google Patents

Description

The present invention relates to a method for producing a methacrylic resin.

In recent years, methacrylic resins have excellent transparency, surface hardness, and the like, and also have small optical characteristics such as double refraction. Therefore, for example, various optical products such as liquid crystal displays, plasma displays, and organic EL displays. As an optical resin for optical materials such as optical disks, optical films, plastic substrates, etc., such as flat panel displays such as small infrared sensors, micro optical waveguides, ultra-small lenses, and pickup lenses for DVD / BlueRayDisc that handle short-wavelength light. The market is expanding significantly.

In particular, it is known that a methacrylic resin having a ring structure in the main chain and a composition containing the methacrylic resin have excellent performance in both heat resistance and optical properties (for example, a patent). (Refer to Reference 1), the demand is expanding rapidly year by year. However, the methacrylic resin having a ring structure in the main chain with improved heat resistance and optical properties as described above is sometimes colored by absorption in the visible light region due to the ring structure or the like, or the transmittance is reduced. There is a problem such as. Therefore, there is disclosed a method of reducing unreacted cyclic monomers remaining in the methacrylic resin in order to obtain a methacrylic resin having a ring structure in the main chain, which is less colored and has high transparency.

For example, Patent Document 2 uses a monomer component containing an N-substituted maleimide (a) and a methacrylic acid ester (b), supplies a part of the monomer component to start polymerization, and then polymerizes. In the production method in which the remainder of the monomer component is supplied on the way, the ratio of the N-substituted maleimide (a) in the unreacted monomer component present in the reaction system at the end of the supply of the monomer component is simply By controlling the content so that it is smaller than the ratio of the N-substituted maleimide (a) in the total amount of the polymer component supplied, the amount of the residual N-substituted maleimide monomer is reduced, and the heat resistance is excellent in transparency and less coloring. A method for obtaining a sex methacrylic resin has been proposed.

Further, in Patent Document 3, in a methacrylic acid ester-based monomer / maleimide-based monomer polymerization system using a sulfur-based chain transfer agent such as mercaptan, residual maleimide is obtained by allowing an acidic substance to exist in the reaction system. A method has been proposed in which the amount of similar monomers and the maleimides generated by heating during molding are reduced to suppress coloring.

International Publication No. 2011/149808 Japanese Unexamined Patent Publication No. 9-324016 Japanese Unexamined Patent Publication No. 2001-233919

However, in recent years, the application has expanded from the optical film application to the thick molded body application such as a lens and a molded plate, and even a molded body having a long optical path length has less coloring and high transparency. It has been eagerly desired to provide a methacrylic resin molded body capable of expressing the above.

In Patent Documents 2 and 3, as a method for reducing coloring, attention is paid to N-substituted maleimide having a strong coloring property as a monomer itself, and the thermal history of N-substituted maleimide remaining in the methacrylic resin and molding processing is used. A method for solving the problem by reducing the amount of N-substituted maleimide produced has been proposed.
However, as described above, for example, as a methacrylic resin for expanding into a molded article having a long optical path length, a large amount of residual colorable N-substituted maleimide is present, and the color tone and transparency are improved. Turned out to be inadequate.

In order to improve the color tone and transparency of the methacrylic resin, it is necessary to sufficiently remove the residual colorable N-substituted maleimide.
However, in order to sufficiently remove the residual colorable N-substituted maleimide, it is necessary to carry out volatilization at a higher temperature in the manufacturing process of the methacrylic resin, and depending on the resin, coloring due to thermal history becomes remarkable. , May not be an effective solution.
Therefore, without devolatile at higher temperatures, the colorable N-substituted maleimide and low molecular weight components that induce coloring side reactions are made colorless under milder conditions, and the color tone and transparency of the methacrylic resin are improved. Further improvement is strongly desired.

Therefore, an object of the present invention is to provide a method for producing a methacrylic resin having improved color tone and transparency without impairing low birefringence.

As a result of diligent studies to solve the above-mentioned problems, the present inventors have added a compound having an allyl group to the polymerization solution, so that the low birefringence is not impaired, the coloring is less, and the transparency is higher. We have found a method for producing a methacrylic resin having a property.

That is, the present invention is as follows.
[1] A structural unit (X) having a ring structure in the main chain is included.
(A) The glass transition temperature (Tg) is more than 120 ° C and 160 ° C or less.
(B) The absolute value of the photoelastic coefficient is 3.0 × ^10-12 Pa ^-1 or less.
(C) The structural unit (X) is at least one selected from the group consisting of a structural unit derived from an N-substituted maleimide monomer, a glutarimide-based structural unit, and a lactone ring structural unit.
It is a method for manufacturing methacrylic resin.
After (co) polymerization of one or more monomer components, including a methacrylic acid ester monomer and a monomer having a ring structure and forming a structural unit (X) in the main chain, and / or After a cyclization reaction of a resin containing a structural unit derived from a methacrylic acid ester monomer obtained by (co) polymerization, the resin contained in the obtained resin and / or in a molten state is subjected to the above. A method for producing a methacrylic resin, which comprises adding 0.10 to 5.0 parts by mass of an allyl compound to 100 parts by mass of a total amount of monomer components and mixing them.
[2] The method for producing a methacrylic resin according to the above [1], wherein the amount of the allyl compound added is 0.50 to 3.0 parts by mass with respect to 100 parts by mass of the total amount of the monomer components.
[3] The method for producing a methacrylic resin according to the above [1] or [2], wherein the allyl compound is at least one selected from the group consisting of an allyl alkyl compound, an allyl aryl compound, and an allyl ether compound.
[4] The method for producing a methacrylic resin according to any one of [1] to [3], wherein the allyl compound has a boiling point in the range of 90 to 300 ° C.
[5] The method for producing a methacrylic resin according to the above [4], wherein the allyl compound has a boiling point in the range of 120 to 250 ° C.
[6] The method for producing a methacrylic resin according to any one of [1] to [5] above, wherein the temperature of the solution to which the allyl compound is added is 100 ° C. or higher, and the mixture is stirred and mixed for 30 minutes or longer.

According to the present invention, it is possible to provide a method for producing a methacrylic resin having high heat resistance, highly controlled birefringence, and improved color tone and transparency.

Hereinafter, embodiments for carrying out the present invention (hereinafter referred to as “the present embodiment”) will be described in detail, but the present invention is not limited to the following description and is within the scope of the gist thereof. It can be modified in various ways.

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

Hereinafter, each monomer structural unit will be described.

-Structural unit derived from methacrylic acid ester monomer-
The structural unit derived from the methacrylic acid ester monomer is formed from, for example, a monomer selected from the following methacrylic acid esters. Examples of the methacrylic acid ester include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate and methacrylic acid. Cyclopentyl, cyclohexyl methacrylate, cyclooctyl methacrylate, tricyclodecyl methacrylate, dicyclooctyl methacrylate, tricyclododecyl methacrylate, isobornyl methacrylate, phenyl methacrylate, benzyl methacrylate, 1-phenylethyl methacrylate, methacrylic acid Examples thereof include 2-phenoxyethyl, 3-phenylpropyl methacrylate, 2,4,6-tribromophenyl methacrylate and the like.
These monomers may be used alone or in combination of two or more.
Of the above methacrylic acid esters, methyl methacrylate and benzyl methacrylate are preferable because the obtained methacrylic acid resin is excellent in transparency and weather resistance.
The structural unit derived from the methacrylic acid ester monomer may contain only one kind or two or more kinds.

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

Hereinafter, the structural unit (X) having a ring structure will be described.

-Structural unit derived from N-substituted maleimide monomer-
Next, the structural unit derived from the N-substituted maleimide monomer will be described.
The structural unit derived from the N-substituted maleimide monomer may be at least one selected from the monomer represented by the following formula (1) and / or the monomer represented by the following formula (2). Preferably, it is formed from both the monomers represented by the following formula (1) and the following formula (2).

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

In the formula (1), R ¹ represents any of an arylalkyl group having 7 to 14 carbon atoms and an aryl group having 6 to 14 carbon atoms, and R ² and R ³ are independent hydrogen atoms and oxygen atoms, respectively. , A sulfur atom, an alkyl group having 1 to 12 carbon atoms or an aryl group having 6 to 14 carbon atoms.
When R ² is an aryl group, R ² may contain a halogen as a substituent.
Further, 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 and a benzyl group.

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

In the 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 are independent hydrogen atoms, respectively. An oxygen atom, a sulfur atom, an alkyl group having 1 to 12 carbon atoms, or an aryl group having 6 to 14 carbon atoms is shown.

A specific example is shown below.
Examples of the monomer represented by the formula (1) include N-phenylmaleimide, N-benzylmaleimide, N- (2-chlorophenyl) maleimide, N- (4-chlorophenyl) maleimide, and N- (4-bromo). Phenyl) maleimide, N- (2-methylphenyl) maleimide, N- (2-ethylphenyl) maleimide, N- (2-methoxyphenyl) maleimide, N- (2-nitrophenyl) maleimide, N- (2,4) , 6-trimethylphenyl) maleimide, N- (4-benzylphenyl) maleimide, N- (2,4,6-tribromophenyl) maleimide, N-naphthylmaleimide, N-anthrasenyl maleimide, 3-methyl-1 -Phenyl-1H-Phenyl-2,5-dione, 3,4-dimethyl-1-phenyl-1H-Phenyl-2,5-dione, 1,3-diphenyl-1H-Pyrol-2,5-dione, 1 , 3,4-Triphenyl-1H-pyrrole-2,5-dione and the like.
Of these monomers, N-phenylmaleimide and N-benzylmaleimide are preferable because the obtained methacrylic resin has excellent heat resistance and optical properties such as birefringence.
These monomers may be used alone or in combination of two or more.

Examples of the monomer represented by the formula (2) include N-methylmaleimide, N-ethylmaleimide, Nn-propylmaleimide, N-isopropylmaleimide, Nn-butylmaleimide, and N-isobutylmaleimide. Ns-butylmaleimide, Nt-butylmaleimide, Nn-pentylmaleimide, Nn-hexylmaleimide, Nn-heptylmaleimide, Nn-octylmaleimide, N-laurylmaleimide, N-cyclopentyl Maleimide, N-cyclohexylmaleimide, 1-cyclohexyl-3-methyl-1H-pyrrole-2,5-dione, 1-cyclohexyl-3,4-dimethyl-1H-pyrrole-2,5-dione, 1-cyclohexyl-3 -Phenyl-1H-pyrrole-2,5-dione, 1-cyclohexyl-3,4-diphenyl-1H-pyrrole-2,5-dione and the like can be mentioned.
Among these monomers, N-methylmaleimide, N-ethylmaleimide, N-isopropylmaleimide, and N-cyclohexylmaleimide are preferable from the viewpoint of excellent weather resistance of the methacrylic resin, and are low in recent years required for optical materials. N-cyclohexylmaleimide is particularly preferable because it has excellent hygroscopicity.
These monomers may be used alone or in combination of two or more.

In the methacrylic resin of the present embodiment, the use of the monomer represented by the formula (1) and the monomer represented by the formula (2) in combination produces highly controlled birefringence characteristics. It is particularly preferable because it can be expressed.
The molar ratio of the content (X1) of the structural unit derived from the monomer represented by the formula (1) to the content (X2) of the structural unit derived from the monomer represented by the formula (2), (X1). / X2) is preferably more than 0 and 15 or less, and more preferably more than 0 and 10 or less.
When the molar ratio (X1 / X2) is in this range, the methacrylic resin of the present embodiment maintains transparency, is not accompanied by yellowing, and has good heat resistance and good environmental resistance. It develops photoelastic properties.

The content of the structural unit 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, but the methacrylic resin is 100% by mass. It is preferably in the range of 5 to 40% by mass, more preferably in the range of 5 to 35% by mass.
When it is within this range, the methacrylic resin can obtain a more sufficient effect of improving heat resistance, and can obtain a more preferable effect 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 decreases during the polymerization reaction, and the amount of unreacted monomer remains large. It is effective in preventing the deterioration of the physical properties of the methacrylic resin due to the formation.

The methacrylic resin having a structural unit derived from the N-substituted maleimide monomer in the present embodiment can be copolymerized with the methacrylic acid ester monomer and the N-substituted maleimide monomer as long as the object of the present invention is not impaired. It may contain structural units derived from other monomers.
For example, other copolymerizable monomers include aromatic vinyl; unsaturated nitriles; acrylic acid esters having a cyclohexyl group, a benzyl group, or an alkyl group having 1 to 18 carbon atoms; glycidyl compounds; unsaturated carboxylic acids. Can be mentioned. Examples of the aromatic vinyl include styrene, α-methylstyrene, divinylbenzene and the like. Examples of the unsaturated nitrile include acrylonitrile, methacrylonitrile, and etacrylonitrile. Examples of the acrylic acid ester include methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl acrylate and the like. Further, examples of the glycidyl compound include glycidyl (meth) acrylate and the like. Examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, and semi-esterified products or anhydrides thereof.
The structural unit derived from the other copolymerizable monomer may have only one kind, or may have two or more kinds.

The content of the structural unit derived from these other copolymerizable monomers is preferably 0 to 10% by mass, more preferably 0 to 9% by mass, with the methacrylic resin as 100% by mass. It is preferably 0 to 8% by mass, and more preferably 0 to 8% by mass.
When the content of the structural unit derived from other monomers is in this range, the moldability and mechanical properties of the resin can be improved without impairing the original effect of introducing the ring structure into the main chain, which is preferable.

The content of structural units derived from the N-substituted maleimide monomer and the content of structural units derived from other copolymerizable monomers shall be determined by ¹ H-NMR measurement and ¹³ C-NMR measurement. Can be done. ^{1 1} H-NMR measurement and ¹³ C-NMR measurement can be carried out at a measurement temperature of 40 ° C. using, for example, CDCl ₃ or DMSO-d ₆ as a measurement solvent.

-Glutarimide-based structural unit-
Examples of the methacrylic resin having a glutarimide-based structural unit in the main chain include JP-A-2006-249202, JP-A-2007-009182, JP-A-2007-009191, JP-A-2011-186482, and re-applied. It is a methacrylic resin having a glutarimide-based structural unit described in Published Patent No. 2012/114718, etc., and can be formed by the method described in the publication.
The glutarimide-based structural unit constituting the methacrylic-based resin of the present embodiment may be formed after the resin polymerization.
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。

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

In the methacrylic resin having a glutarimide-based structural unit, the content of the glutarimide-based structural unit is not particularly limited as long as it satisfies the range of the glass transition temperature preferable for the composition of the present embodiment, but is methacrylic-based. The resin is 100% by mass, preferably in the range of 5 to 70% by mass, and more preferably in the range of 5 to 60% by mass.
When the content of the glutarimide-based structural unit is within the above range, a resin having good molding processability, heat resistance, and optical properties can be obtained, which is preferable.
The content of the glutarimide-based structural unit in the methacrylic resin can be determined by using the method described in the above-mentioned patent document.

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

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

-Lactone ring structure unit-
Examples of the methacrylic resin having a lactone ring structural unit in the main chain include JP-A-2001-151814, JP-A-2004-168882, JP-A-2005-146804, JP-A-2006-96960, and JP-A. It can be formed by the methods described in JP-A-2006-171464, JP-A-2007-63541, JP-A-2007-297620, JP-A-2010-180305, and the like.

The lactone ring structural unit constituting the methacrylic resin of the present embodiment may be formed after the resin polymerization.
The lactone ring structure unit in the present embodiment is preferably a 6-membered ring because of its excellent ring structure stability.
As the lactone ring structural unit which is a 6-membered ring, for example, the structure represented by the following general formula (4) is particularly preferable.

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

In the above general formula (4), R ¹⁰ , R ¹¹ and R ¹² are hydrogen atoms or organic residues having 1 to 20 carbon atoms independently of each other.
Examples of the organic residue include a saturated aliphatic hydrocarbon group having 1 to 20 carbon atoms (alkyl group, etc.) such as a methyl group, an ethyl group, and a propyl group; and a non-saturated aliphatic hydrocarbon group having 2 to 20 carbon atoms such as an ethenyl group and a propenyl group. Saturated aliphatic hydrocarbon group (alkenyl group, etc.); Aromatic hydrocarbon group having 6 to 20 carbon atoms (aryl group, etc.) such as phenyl group and naphthyl group; these saturated aliphatic hydrocarbon group, unsaturated aliphatic hydrocarbon Examples include a group in which one or more of the hydrogen atoms in the group and the 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.

In the lactone ring structure, for example, an acrylic acid-based monomer having a hydroxy group and a methacrylic acid ester monomer such as methyl methacrylate are copolymerized 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 an ester group or a carboxyl group.

Examples of the hydroxy group-containing acrylic acid-based monomer used for polymerization include 2- (hydroxymethyl) acrylic acid, 2- (hydroxyethyl) acrylic acid, and 2- (hydroxymethyl) alkyl acrylate (for example, 2-). Methyl (hydroxymethyl) acrylate, ethyl 2- (hydroxymethyl) acrylate, isopropyl 2- (hydroxymethyl) acrylate, n-butyl 2- (hydroxymethyl) acrylate, t- (hydroxymethyl) acrylate Examples thereof include butyl) and alkyl 2- (hydroxyethyl) acrylate, preferably 2- (hydroxymethyl) acrylate and alkyl 2- (hydroxymethyl) acrylate, which are monomers having a hydroxyalkyl moiety. , Particularly preferred are 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 preferable for the composition of the present embodiment, but the methacrylic resin. It is preferably 5 to 40% by mass, more preferably 5 to 35% by mass with respect to 100% by mass.
When the content of the lactone ring structure unit is within this range, the ring structure introduction effect such as improvement of solvent resistance and surface hardness can be exhibited while maintaining molding processability.
The content of the lactone ring structure in the methacrylic resin can be determined by using the method described in the above-mentioned patent document.

The methacrylic resin having a lactone ring structural unit in the main chain has a structural unit derived from the above-mentioned methacrylic acid ester monomer and other monomers copolymerizable with the acrylic acid-based monomer having a hydroxy group. May be.
Examples of such copolymerizable monomers include styrene, vinyltoluene, α-methylstyrene, α-hydroxymethylstyrene, α-hydroxyethylstyrene, acrylonitrile, methacrylonitrile, metallic alcohol, and ethylene. , Styrene, 4-methyl-1-pentene, vinyl acetate, 2-hydroxymethyl-1-butene, methylvinylketone, N-vinylpyrrolidone, N-vinylcarbazole and other monomers having a polymerizable double bond. Can be mentioned.
These other monomers (constituent units) may have only one kind or two or more kinds.

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

The methacrylic resin in the present embodiment preferably has at least one ring structural unit selected from the group consisting of a structural unit derived from an N-substituted maleimide monomer, a glutarimide-based structural unit, and a lactone ring structural unit. Above all, it is particularly preferable to have a structural unit derived from an N-substituted maleimide monomer from the viewpoint that it is easy to highly control optical properties such as a photoelastic coefficient without blending with other thermoplastic resins.

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

The content of the allyl compound in the methacrylic resin of the present embodiment is not particularly limited, but is preferably 10 mass ppm or more and 2000 mass ppm or less, more preferably 100 mass ppm or more, with respect to 100 parts by mass of the methacrylic resin. It is 1000 mass ppm or less, more preferably 200 mass ppm or more and 600 mass ppm or less. When the content of the allyl compound is within these ranges, the unreacted N-substituted maleimide monomer remaining in the methacrylic resin of the present embodiment, the NH bond of the acrylamide group and the O- of the hydroxymethyl group remain. Even if the H bond is desorbed during the molding process, it is advantageous because it reacts again with the residual allyl compound and the decolorizing effect is maintained.

-Characteristics of methacrylic resin-
--Glass-transition temperature--
The glass transition temperature (Tg) of the methacrylic resin in the present embodiment is more than 120 ° C and 160 ° C or less.
If the glass transition temperature of the methacrylic resin exceeds 120 ° C., it is easier to obtain sufficient heat resistance as an optical component such as a lens molded body in recent years, an automobile component such as an in-vehicle display, and a film molded body optical film for a liquid crystal display. Can be obtained. The glass transition temperature (Tg) is more preferably 125 ° C. or higher, still more preferably 130 ° C. or higher, from the viewpoint of dimensional stability under the operating environment temperature.
On the other hand, when the glass transition temperature (Tg) of the methacrylic resin is 160 ° C. or lower, melting processing at an extremely high temperature can be avoided, thermal decomposition of the resin or the like can be suppressed, and a good product can be obtained.
The glass transition temperature (Tg) is preferably 150 ° C. or lower for the above-mentioned reasons.
The glass transition temperature (Tg) can be determined by measuring in accordance with JIS-K7121. Specifically, it can be obtained by the method described in Examples described later.

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

The weight average molecular weight (Mw), number average molecular weight (Mn), and Z average molecular weight (Mz) of the methacrylic resin can be measured with the following devices and conditions.
-Measuring device: Gel Permeation Chromatography manufactured by Tosoh Corporation (HLC-8320GPC)
·Measurement condition:
Column: One TSKguardcolum SuperH-H, two TSKgel SuperHM-M, and one TSKgel SuperH2500 are connected in series in order for use.
Column temperature: 40 ° C
The developing solvent: tetrahydrofuran, the flow rate: 0.6 mL / min, and 2,6-di-t-butyl-4-methylphenol (BHT) as an internal standard are added at 0.1 g / L.
Detector: RI (differential refractometer) detector Detection sensitivity: 3.0 mV / min Sample: 0.02 g Tetrahydrofuran 20 mL solution injection amount of methacrylic resin: 10 μL
Standard sample for calibration curve: Weight peak of monodisperse The following 10 types of polymethylmethacrylate (manufactured by Polymer Laboratories; PMMA Calibration Kit M-M-10) having a known molecular weight and different molecular weights are used.
Weight peak molecular weight (Mp)
Standard sample 1 1,916,000
Standard sample 2 625,500
Standard sample 3 298,900
Standard sample 4 138,600
Standard sample 5 60, 150
Standard sample 6 27,600
Standard sample 7 10,290
Standard sample 8 5,000
Standard sample 9 2,810
Standard sample 10 850
Under the above conditions, the RI detection intensity with respect to the elution time of the methacrylic resin or the methacrylic resin is measured.
Based on each calibration curve obtained by the measurement of the standard sample for the calibration curve, the weight average molecular weight (Mw), the number average molecular weight (Mn), and the Z average molecular weight (Mz) of the methacrylic resin and the methacrylic resin are obtained. The molecular weight distribution (Mw / Mn) and (Mz / Mw) are determined using the obtained values.

－－Methanol insoluble component －－
In the methacrylic resin of the present embodiment, the ratio of the amount of the insoluble methanol to 100% by mass of the total amount of the insoluble methanol and the soluble methanol is preferably 95% by mass or more, more preferably. Is 95.5% by mass or more, more preferably 96% by mass or more, still more preferably 96.5% by mass or more, particularly preferably 97% by mass or more, and most preferably 97.5% by mass. % Or more. By setting the ratio of the amount of insoluble methanol to 95% by mass or more, it is possible to suppress problems during molding such as cast roll stains during film molding and silver streaks during injection molding.
The methanol-insoluble and methanol-soluble components are reprecipitated by making a methacrylic resin into a chloroform solution and then dropping the solution into a large excess amount of methanol to separate the filtrate and the filtrate, and then each of them. Refers to what is obtained by drying.

Specifically, it can be obtained as follows. After dissolving 5 g of the methacrylic resin in 100 mL of chloroform, the solution is placed in a dropping funnel and added dropwise to 1 L of methanol stirred with a stirrer over about 1 hour to perform reprecipitation. After dropping the entire amount and allowing it to stand for 1 hour, suction filtration is performed using a membrane filter (T050A090C manufactured by Advantech Toyo Co., Ltd.) as a filter. The filtrate is vacuum dried at 60 ° C. for 16 hours to make it insoluble in methanol. Further, the filtrate may remain in the eggplant-shaped flask after the solvent is removed by using the rotary evaporator at a bath temperature of 40 ° C. and gradually lowering the degree of vacuum from the initial setting of 390 Torr to finally 30 Torr. The dissolved component is recovered and used as a methanol-soluble component. Weigh each of the mass of methanol insoluble and the mass of methanol soluble, and the ratio (mass) of the amount of methanol soluble to the total amount (100% by mass) of the amount of methanol soluble and the amount of methanol insoluble. %) (Methanol-soluble fraction) is calculated.

--Yellowness index (YI) and transmittance ---
The methacrylic resin in the present embodiment has a yellowness index (YI) of 0 to 7, preferably 0.5 to 6, measured using a 10 cm optical path length cell for a 20 w / v% chloroform solution having an insoluble methanol content. It is more preferably 0.8 to 5, still more preferably 1 to 4.
Further, the methacrylic resin in the present embodiment preferably has a transmittance of 90% or more, more preferably 91% or more, and more preferably 92%, at 680 nm measured under the same conditions as those in the above-mentioned YI measurement. % Or more is more preferable.
When the yellowness index (YI) and the transmittance are in this range, a molded product suitable for optical use can be obtained. Further, by adding the allyl compound described later, it can be expected that the YI of the insoluble methanol is reduced and the transmittance is improved.

The yellowness index (YI) and transmittance are a solution prepared by dissolving the methanol-insoluble content of the methacrylic resin in a 20 w / v% chloroform solution (that is, dissolving 10 g of a sample in chloroform to make a 50 mL solution). ), And use it as a measurement sample. Using an ultraviolet-visible spectrophotometer (UV-2500PC, manufactured by Shimadzu Corporation), measurement wavelength 380 to 780 nm, slit width 2 nm, 10 cm optical path length cell, viewing angle 10 °, auxiliary illuminant C, reference object: chloroform , Perform transmittance measurement. According to JIS K 7373, using the XYZ color system, the following formula YI = 100 (1.2769X-1.592Z) / Y
YI (Yellowness Index) is calculated.
Further, the transmittance (%) at a wavelength of 680 nm is also recorded under the same conditions as those in the above-mentioned YI measurement.

－－Photoelastic coefficient _CR －－
The absolute value of the photoelastic coefficient _CR of the methacrylic resin having a ring structure in the main chain of the present embodiment is 3.0 × 10 ^-12 Pa ^-1 or less, preferably 2.0 × 10 ^-12 Pa ^{− −} . It is ¹ or less, more preferably 1.5 × 10 ^-12 Pa ^-1 or less, and further preferably 1.0 × 10 ^-12 Pa ^-1 or less. Photoelastic coefficients are described in various documents (see, for example, Review Articles of Chemistry, No. 39, 1998 (published by the Society Publishing Center)) and are defined by the following formulas (ia) and (ib). Is. It can be seen that the closer the value of the photoelastic coefficient C _R is to zero, the smaller the birefringence change due to the external force.
_CR = | Δn | / σ _R ... (i-a)
| Δn | = | nx-ny | ... (ib)
(In the equation, _{CR is the photoelastic coefficient, σ R is} the elongation stress, | Δn | is the absolute value of birefringence, nx is the refractive index in the extension direction, and ny is the direction perpendicular to the extension direction in the plane. The refractive index of each is shown.)
When the absolute value of the photoelastic coefficient C _R of the methacrylic resin of the present embodiment is 3.0 × 10 ^-12 Pa ^-1 , even in an injection-molded article having a relatively thin thickness and a long optical path length, light rays are emitted. An optical member having high transmittance and less uneven brightness can be obtained even when used as a light guide plate.
The photoelastic coefficient _CR is measured by using a methacrylic resin as a press film using a vacuum compression molding machine. Specifically, it can be obtained by the method described in Examples described later.

[Manufacturing method of methacrylic resin]
Hereinafter, a method for producing the methacrylic resin of the present embodiment will be described.

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

Hereinafter, as an example of a method for producing a methacrylic resin having a structural unit derived from an N-substituted maleimide monomer (hereinafter, may be referred to as “maleimide copolymer”), a radical polymerization method is used in a batch manner. The case of producing by polymerization will be specifically described.

The polymerization solvent to be used is not particularly limited as long as it can increase the solubility of the maleimide copolymer obtained by the polymerization and maintain the viscosity of the reaction solution appropriately for the purpose of preventing gelation and the like.
Specific polymerization solvents include, for example, aromatic hydrocarbons such as toluene, xylene, ethylbenzene and isopropylbenzene; ketones such as methyl isobutyl ketone, butyl cellosolve, methyl ethyl ketone and cyclohexanone; and polar solvents such as dimethylformamide and 2-methylpyrrolidone. Can be used.

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

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

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

The polymerization conversion rate at the end of polymerization of the methacrylic resin having a structural unit derived from the N-substituted maleimide monomer in the main chain of the present embodiment is not particularly limited, but is preferably 94.5% or more, more preferably. It is preferably 96.0% or more and 98.0% or less, and more preferably 96.5% or more and 97.5% or less.
Here, the polymerization conversion rate is a 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 in the polymerization system, and the monomer added in the polymerization system. It is a ratio to the total mass of. Specifically, it can be obtained by the method described in Examples described later.

The amount of N-substituted maleimide monomer remaining in the solution after polymerization (residual amount of N-substituted maleimide) is preferably 100 to 7000 mass ppm or less, preferably 200 to 5000 mass ppm or less. More preferably, it is more preferably 300 to 3000 mass ppm or less.
The higher the polymerization conversion rate and the smaller the residual amount of N-substituted maleimide, the less the monomer that goes to the solvent recovery system, so that the load on the purification system is reduced, and the basic unit is lowered, which is economical.
However, in the polymerization process, if the polymerization conversion rate is too high or the residual amount of N-substituted maleimide is too low due to a high polymerization temperature or a long polymerization time, the amount of colorable low molecular weight component or methanol is increased. The amount of soluble content may increase, which may adversely affect the color tone and moldability.
Therefore, it is preferable that the remaining N-substituted maleimide is decolorized by removal in the devolatile step described later or addition of an allyl compound.

At the time of the polymerization reaction, a polymerization initiator or a chain transfer agent may be added as needed for polymerization.

As the polymerization initiator, any initiator generally used in radical polymerization can be used, and for example, cumene hydroperoxide, diisopropylbenzenehydroperoxide, di-t-butyl peroxide, lauroyl peroxide, benzoylper. Organic peroxides such as oxides, t-butylperoxyisopropyl carbonate, t-amylperoxy-2-ethylhexanoate, t-amylperoxyisononanoate, 1,1-dit-butylperoxycyclohexane; 2,2'-Azobis (isobutyronitrile), 1,1'-azobis (cyclohexanecarbonitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), dimethyl-2,2'-azobis An azo compound such as isobutyrate; and the like can be mentioned.
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 added may be 0.01 to 1 part by mass, preferably 0.05 to 0.5 part by mass, when the total amount of the monomers used for the polymerization is 100 parts by mass.

As the chain transfer agent, a chain transfer agent used in general radical polymerization can be used, and for example, n-butyl mercaptan, n-octyl mercaptan, n-decyl mercaptan, n-dodecyl mercaptan, 2-ethylhexyl thioglycolate and the like can be used. Examples thereof include mercaptan compounds; halogen compounds such as carbon tetrachloride, methylene chloride and bromoform; unsaturated hydrocarbon compounds such as α-methylstyrene dimer, α-terpinene, dipentene and turpinolene; and the like.
These may be used alone or in combination of two or more.
These chain transfer agents may be added at any stage as long as the polymerization reaction is in progress, and are not particularly limited.
The amount of the chain transfer agent added may be 0.01 to 1 part by mass, preferably 0.05 to 0.5 part by mass, when the total amount of the monomers used for the 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, the method of bubbling the inert gas in the polymerization solution and the operation of pressurizing the container containing the polymerization solution with the inert gas to about 0.2 MPa and then releasing the pressure are repeated before the polymerization. A method such as a method or a method of passing an inert gas through a container containing a polymerization solution can be appropriately selected.

The method for recovering the polymer from the polymerization solution obtained by solution polymerization is not particularly limited, but for example, a poor solvent such as a hydrocarbon solvent or an alcohol solvent that does not dissolve the polymerization product obtained by the polymerization. After adding the polymerization solution in the presence of an excessive amount of solvent, the unreacted monomer is treated with a homogenizer (emulsion dispersion), and the unreacted monomer is subjected to pretreatment such as liquid-liquid extraction and solid-liquid extraction. Examples thereof include a method of separating from the polymerization solution; or a method of separating the polymerization solvent and the unreacted monomer via a step called a devolatile step and recovering the polymerization product.
Here, the devolatile step refers to a step of removing volatile components such as a polymerization solvent, a residual monomer, and a reaction by-product under heating and reduced pressure conditions.

As the device used in the devolatilization process, for example, a devolatilization device consisting of a tubular heat exchanger and a devolatilization tank; a thin film evaporator such as Wybren and Exeba manufactured by Kobelco Eco-Solutions Co., Ltd., a contra and a tilted blade contra manufactured by Hitachi, Ltd .; Extruders with vents that have sufficient residence time and surface area to exhibit volatilization performance; and the like.
A volatilization step using a devolatilization device in which any 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, and even more preferably 200 to 280 ° C. By setting the temperature to the lower limit or higher, the residual volatile matter can be suppressed, and by setting the temperature to the upper limit or lower, the coloring and decomposition of the obtained methacrylic resin can be suppressed.

The degree of vacuum in the devolatilizer is preferably 10 to 500 Torr, more preferably 10 to 300 Torr. If the degree of vacuum exceeds 500 Torr, volatile matter may easily remain. On the contrary, if the degree of vacuum is less than 10 Torr, industrial implementation may be difficult.
The treatment time is appropriately selected depending on the amount of residual volatile matter, but a shorter treatment time is preferable in order to suppress coloring and decomposition of the obtained methacrylic resin.

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

When an extruder with a vent is used as the devolatilization device, the devolatilization step and the granulation step may be combined.

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

Examples of the methacrylic resin having a glutarimide-based structural unit in the main chain include JP-A-2006-249202, JP-A-2007-009182, JP-A-2007-009191, JP-A-2011-186482, International. It is a methacrylic resin having a glutarimide-based structural unit described in Publication No. 2012/114718 and the like, and can be formed by the method described in the publication.
Hereinafter, as an example of a method for producing a methacrylic resin having a glutarimide-based structural unit, a case of producing by radical polymerization in a batch system using a solution polymerization method will be specifically described.

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

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

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

At the time of the polymerization reaction, a polymerization initiator or a chain transfer agent may be added as needed for polymerization.

The polymerization initiator is not particularly limited, but 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.
These polymerization initiators may be added at any stage as long as the polymerization reaction is in progress.
The amount of the polymerization initiator 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 the 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.

As the chain transfer agent, a chain transfer agent used in general radical polymerization can be used, and 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 added is not particularly limited as long as the desired degree of polymerization can be obtained under the polymerization conditions used, but preferably the total amount of the monomers used for the polymerization is 100 parts by mass. In this case, the amount may be 0.01 to 1 part by mass, preferably 0.05 to 0.5 part by mass.

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

Next, an imidization reaction is carried out by reacting the (meth) acrylic acid ester polymer or the methacrylic acid ester-aromatic vinyl copolymer with an imidizing agent (imidization step). This makes it possible to produce a methacrylic resin having a glutarimide-based structural unit.

The imidizing agent is not particularly limited as long as it can generate a glutarimide-based structural unit represented by the general formula (3).
Specifically, as the imidizing agent, ammonia or a primary amine can be used. 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; and the like.
Among the above imidizing agents, ammonia, methylamine and cyclohexylamine are preferably used, and methylamine is particularly preferable, from the viewpoint of cost and physical properties.

In this imidization step, the content of the glutarimide-based structural unit in the methacrylic resin having the obtained 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, and for example, the imidization reaction can be allowed to proceed by using an extruder or a batch type reaction tank.
The extruder is not particularly limited, and for example, a single-screw extruder, a twin-screw extruder, a multi-screw extruder, or the like can be used.

Above all, it is preferable to use a twin-screw extruder. According to the twin-screw extruder, mixing of the raw material polymer and the imidizing agent can be promoted.
Examples of the twin-screw extruder include a non-meshing type isotropy type, a meshing type anisotropy type, a non-meshing type anisotropic rotation type, and a meshing type anisotropic rotation type.

The extruder exemplified above may be used alone or may be used by connecting a plurality of extruders in series.
Further, the extruder to be used is particularly equipped with a bent port capable of reducing the pressure below atmospheric pressure because the imidizing agent for the reaction, by-products such as methanol, or monomers can be removed. preferable.

In producing a methacrylic resin having a glutarimide-based structural unit, in addition to the above-mentioned imidization step, an esterification step of treating the carboxyl group of the resin with an esterifying agent such as dimethyl carbonate can be included. At that time, a catalyst such as trimethylamine, triethylamine, or tributylamine can be used in combination for treatment.
The esterification step can be carried out in the same manner as the imidization step by using, for example, an extruder or a batch type reaction vessel. Further, for the purpose of removing excess esterifying agent, by-products such as methanol, or monomers, it is preferable to equip the device to be used with a valve opening capable of reducing the pressure below atmospheric pressure.

The methacrylic resin that has undergone the imidization step and, if necessary, the esterification step is melted and extruded into strands from an extruder equipped with a porous die, and is cold-cut, aerial hot-cut, underwater strand-cut, and under. It is processed into pellets by a water cut method or the like.
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 and methylene chloride, the obtained methacrylic resin solution is filtered, and then the organic solvent is devolatile. It is also preferable to use the method.

-Manufacturing method of methacrylic resin containing lactone ring structural unit-
As a method for producing a methacrylic resin having a lactone ring structure unit in the main chain, a method of forming a lactone ring structure by a cyclization reaction after polymerization is used, but a solution using a solvent is used to promote the cyclization reaction. It is preferable to polymerize the monomer by radical polymerization by a polymerization method.
In the production method in the present embodiment, for example, a batch polymerization method, a semi-batch method, or a continuous polymerization method can be used as the polymerization form.
Examples of the methacrylic resin having a lactone ring structural unit in the main chain include JP-A-2001-151814, JP-A-2004-168882, JP-A-2005-146804, JP-A-2006-96960, and JP-A. It can be formed by the methods described in JP-A-2006-171464, JP-A-2007-63541, JP-A-2007-297620, JP-A-2010-180305, and the like.

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

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

The amount of the solvent at the time of polymerization is not particularly limited as long as the polymerization proceeds and gelation can be suppressed. For example, when the total amount of the monomers to be blended is 100 parts by mass, the amount is 50 to 200 mass. The amount is preferably 100 to 200 parts by mass, more preferably 100 to 200 parts by mass.

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

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

At the time of the polymerization reaction, a polymerization initiator or a chain transfer agent may be added to polymerize, if necessary.

The polymerization initiator is not particularly limited, but 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.
These polymerization initiators may be added at any stage as long as the polymerization reaction is in progress.
The amount of the polymerization initiator 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 the monomers used for polymerization is 100 parts by mass. In addition, it may be 0.05 to 1 part by mass.

As the chain transfer agent, a chain transfer agent used in general radical polymerization can be used, and 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 added is not particularly limited as long as the desired degree of polymerization can be obtained under the polymerization conditions used, but preferably the total amount of the monomers used for the polymerization is 100 parts by mass. If this is the case, the amount may be 0.05 to 1 part by mass.

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

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

The methacrylic resin having a lactone ring structural unit in the present embodiment can be obtained by carrying out a cyclization reaction after the completion of the above-mentioned polymerization reaction. Therefore, it is preferable to carry out the lactone cyclization reaction in a state containing the solvent without removing the polymerization solvent from the polymerization reaction solution.
The copolymer obtained by the polymerization undergoes a cyclization condensation reaction between a hydroxyl group (hydroxyl group) existing in the molecular chain of the copolymer and an ester group by heat treatment, and has a lactone ring structure. Form.
During the heat treatment for forming the lactone ring structure, a vacuum device for removing alcohol that may be by-produced by cyclization condensation, a reaction device equipped with a devolatilization device, an extruder equipped with a volatilization device, or the like can also be used. ..

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

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

The timing of addition of the cyclization condensation catalyst is not particularly limited, and for example, it may be added at the initial stage of the cyclization condensation reaction, during the reaction, or at both of them. good.
When the cyclization condensation reaction is carried out in the presence of a solvent, it is also preferably used to carry out devolatile reaction at the same time.

The apparatus used when the cyclization condensation reaction and the devolatilization step are performed at the same time is not particularly limited, but is a devolatilization apparatus consisting of a heat exchanger and a devolatilization tank, an extruder with a vent, and devolatilization. It is preferable that the device and the extruder are arranged in series, and a twin-screw extruder with a vent is more preferable.
As the twin-screw extruder with a vent to be used, an extruder with a vent having a plurality of vent ports is preferable.

When an extruder with a vent is used, the reaction treatment temperature is preferably 150 to 350 ° C, more preferably 200 to 300 ° C. If the reaction treatment temperature is less than 150 ° C., the cyclization condensation reaction may be insufficient and the residual volatile matter may increase. On the contrary, when the reaction treatment temperature exceeds 350 ° C., coloring or decomposition of the obtained polymer may occur.
When the extruder with a vent is used, the degree of vacuum is preferably 10 to 500 Torr, more preferably 10 to 300 Torr. If the degree of vacuum exceeds 500 Torr, volatile matter may easily remain. On the contrary, if the degree of vacuum is less than 10 Torr, industrial implementation may be difficult.

It is also preferable to add an alkaline earth metal and / or an amphoteric metal salt of an organic acid at the time of granulation for the purpose of inactivating the remaining cyclization condensation catalyst when the above cyclization condensation reaction is carried out.
As the alkaline earth metal and / or amphoteric metal salt of the organic acid, for example, calcium acetyl acetate, calcium stearate, zinc acetate, zinc octylate, zinc 2-ethylhexylate and the like can be used.

After undergoing the cyclization condensation reaction step, the methacrylic resin is melted and extruded into strands from an extruder attached with a porous die, and is subjected to a cold cut method, an aerial hot cut method, an underwater strand cut method, and an underwater cut method. Process into pellets.
The lactonization for forming the above-mentioned lactone ring structure unit may be performed after the production of the resin and before the production of the resin composition (described later), and during the production of the resin composition, the resin and the components other than the resin may be formed. It may be carried out in combination with the melt-kneading with.

-Improved color tone by adding allyl compound-
In the method for producing a methacrylic resin of the present embodiment, from the viewpoint of improving the color tone of the polymer, a methacrylic acid ester monomer and a monomer having a structural unit (X) having a ring structure as a main chain are used. A resin containing a structural unit derived from a methacrylic acid ester monomer obtained by (co) polymerizing and / or (co) polymerizing one or more kinds of monomer components containing the above was subjected to a cyclization reaction. Later, the allyl compound is added and mixed in the obtained solution containing the resin and / or in the molten state of the resin.
Examples of the allyl compound to be added include an allyl alkyl compound, an allyl aryl compound, an allyl ether compound, an allyl sulfide compound, and an allyl amine compound.
These allyl compounds may contain one kind alone or a combination of two or more kinds.

The alkyl group in the allylalkyl compound is not particularly limited, but for example, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, an iso-butyl group, a tert-butyl group, and the like. Examples thereof include an aliphatic group such as an n-hexyl group, an n-octyl group, an n-decyl group, an n-dodecyl group and a cyclohexyl group, or an alicyclic group.
Examples of the aryl group in the allylaryl compound include an aryl group such as a phenyl group, a naphthyl group and a benzyl group, or an arylalkyl group.
The alkyl group and aryl group may have a substituent such as a nitro group, an alkoxyl group, an alkyl group and a trifluoromethyl group.

Examples of the allyl ether compound include allylpropyl ether, allylphenyl ether, diallyl ether and the like.
Examples of the allyl sulfide compound include allyl methyl sulfide, allyl ethyl sulfide, and allyl propyl sulfide.
Examples of the allylamine compound include tertiary amines having an allyl group, and examples thereof include allyldimethylamine, allylethylmethylamine, and diallylmethylamine.

Above all, from the viewpoint of reducing the influence of the obtained resin on the double refraction, the allyl compound is preferably at least one selected from the group consisting of an allyl alkyl compound, an allyl aryl compound, and an allyl ether compound, and more preferably. Is an allylalkyl compound or an allylaryl compound.

The allyl compound preferably does not have a hydroxyl group. This is because when the allyl compound has a hydroxyl group, the hydroxyl group remains in the resin and causes coloring during devolatileization and molding. Further, in order to avoid a decrease in reactivity due to steric hindrance, it is preferable that hydrogen is substituted on the carbon at the 1st and 2nd positions of the allyl group.

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

The amount of the allyl compound added is preferably 0.10 to 5.0 parts by mass, more preferably 0.50 to 3.0, when the total mass of the monomers used for polymerization is 100 parts by mass. It is by mass, more preferably 1.0 to 2.0 parts by mass. When the addition amount is within these ranges, the color tone improving effect of the produced methacrylic resin can be sufficiently exhibited.

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

When the monomer forming the structural unit (X) having a ring structure in the main chain is an N-substituted maleimide monomer, it contains a methacrylic acid ester monomer and an N-substituted maleimide monomer. After copolymerizing two or more kinds of monomer components, in a solution containing a methacrylic resin having a structural unit derived from the obtained N-substituted maleimide monomer formed, and / or in a molten state of the resin. , Allyl compound is added and mixed. Specifically, after the completion of the polymerization, the allyl compound may be added to the (co) polymerization solution and stirred under heating, and the methacrylic resin separated or recovered through the devolatilization step or the like is melted by an extruder or the like. At the time of extrusion, an allyl compound may be added to the melted methacrylic resin and extruded.

When the monomer forming the structural unit (X) having a ring structure in the main chain is a monomer forming a glutarimide-based structural unit, a resin containing a structural unit derived from a methacrylic acid ester monomer is used. After the cyclization reaction using an imidizing agent, the allyl compound is added and mixed in the solution containing the methacrylic resin on which the obtained glutarimide-based structural unit is formed and / or in the molten state of the resin. do.

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

The allyl compound may be added to a solution containing a methacrylic resin having a structural unit (X) having a ring structure in the main chain, or may be added to the methacrylic resin in a molten state.
The temperature of the solution containing the obtained resin to which the allyl compound is added or the temperature of the resin in the molten state is not particularly limited as long as it is 100 ° C. or higher, but is 120 from the viewpoint of reaction rate and quality assurance of the polymer. It is preferably to 270 ° C, more preferably 130 to 250 ° C, and even more preferably 140 to 230 ° C.

When the allyl compound is added to the solution containing the methacrylic resin and mixed, the stirring time is preferably 30 minutes or more, more preferably 2 hours or more. When it is within these ranges, the allyl compound reacts rapidly and exhibits a decolorizing effect, which is advantageous.

When an allyl compound is added to a molten methacrylic resin and mixed, the screw rotation speed by an extruder or the like is preferably 50 rpm or more and 300 rpm or less, more preferably 70 rpm or more and 250 rpm or less, still more preferably 100 rpm. It is 200 rpm or less. Further, it is preferable to reduce the pressure of the vent port to 400 Torr or less, more preferably 200 Torr or less, and further preferably 100 Torr or less. By mixing under these extrusion conditions, the allyl compound reacts rapidly and by-products and excess allyl compound can be removed, so that the decolorizing effect can be efficiently exhibited.

The mechanism by which the color tone is improved by the addition of the allyl compound is not clear, but the decolorization due to the ene reaction with the double bond site of the remaining unreacted colored N-substituted maleimide monomer and the N of the unreacted acrylamide group It is presumed that the addition of the -H bond and / or the OH bond of the unreacted hydroxyalkyl group to the double bond of the allyl group suppresses the coloring side reaction during devolatile and / or molding.

[Methyl methacrylic resin composition]
The methacrylic resin composition of the present embodiment contains the above-mentioned methacrylic resin containing a structural unit (X) having a ring structure in the main chain, and further variously, within a range that does not significantly impair the effects of the present invention. It may contain an additive.

-Additive-
The additives are not particularly limited, but are, for example, light stabilizers such as antioxidants and hindered amine-based light stabilizers, ultraviolet absorbers, mold release agents, other thermoplastic resins, paraffin-based process oils, and naphthen-based processes. Oils, aromatic process oils, paraffins, organic polysiloxanes, softeners / plasticizers such as mineral oils, flame retardants, antistatic agents, organic fibers, inorganic fillers such as pigments such as iron oxide, glass fibers, carbon fibers , Reinforcing agents such as metal whiskers, colorants; organophosphorus compounds such as paraffinic esters, phosphonite, and phosphoric acid esters, other additives, and mixtures thereof.

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

The methacrylic resin of the present embodiment is suitably used in various applications such as melt extrusion, injection molding, and film molding. The heat history received during processing varies depending on the processing method, but it ranges from several tens of seconds like an extruder to tens of minutes to several hours of heat history such as thick-walled molding and sheet molding. There are various. When receiving a long heat history, it is necessary to increase the amount of the heat stabilizer added in order to obtain the desired heat stability.
Therefore, from the viewpoint of suppressing the bleed-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, for example, a phosphorus-based antioxidant and a sulfur-based antioxidant. It is preferable to use at least one selected from the antioxidants in combination with a hindered phenolic antioxidant.

The hindered phenolic antioxidant is not limited to the following, but is, for example, pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], thiodiethylenebis. [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''-(methitylen-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-xylin) methyl ] -1,3,5-triazine-2,4,6 (1H, 3H, 5H) -trione, 2,6-di-tert-butyl-4- (4,6-bis (octylthio) -1,3 , 5-Triazine-2-ylamine) phenol, acrylic acid 2- [1- (2-hydroxy-3,5-di-tert-pentylphenyl) ethyl] -4,6-di-tert-pentylphenyl, acrylic acid Examples thereof include 2-tert-butyl-4-methyl-6- (2-hydroxy-3-tert-butyl-5-methylbenzyl) phenyl.
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 is preferred.

Further, as the hindered phenol-based antioxidant as the antioxidant, a commercially available phenol-based antioxidant may be used, 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''-(methicylene-2,4,6-triyl) tri-p-cresol, manufactured by BASF), Irganox 3114 (Irganox 3114: 1,3,5) -Tris (3,5-di-t-butyl-4-hydroxybenzyl) -1,3,5-triazine-2,4,6 (1H, 3H, 5H) -Torion, manufactured by BASF), Irganox 3125 (Irganox 3125, manufactured by BASF), Adecastab AO-60 (pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], manufactured by ADEKA), Adecastab AO-80 (3) , 9-bis {2- [3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionylxyoxy] -1,1-dimethylethyl} -2,4,8,10-tetraoxaspiro [5.5] Undecan (manufactured by ADEKA), Sumilizer BHT (Sumilizer BHT, manufactured by Sumitomo Chemical), Cyanox 1790 (Cyanox 1790, manufactured by Cytec), Sumilizer GA-80 (manufactured by 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, manufactured by Sumitomo Chemical Co., Ltd.), Sumilizer GM (Sumilizer) GM: 2-tert-butyl-4-methyl-6- (2-hydroxy-3-tert-butyl-5-methylbenzyl) phenyl acrylate, manufactured by Sumitomo Chemical Co., Ltd.), vitamin E (manufactured by Eisai) and the like can be mentioned.
Among these commercially available phenolic antioxidants, Irganox 1010, Adecastab AO-60, Adecastab AO-80, Irganox 1076, Sumilyzer GS and the like are preferable from the viewpoint of the effect of imparting thermal stability in the resin.
These may be used alone or in combination of two or more.

The phosphorus-based antioxidant as the antioxidant is not limited to the following, but is, for example, tris (2,4-di-t-butylphenyl) phosphite, bis (2,4-). Bis (1,1-dimethylethyl) -6-methylphenyl) ethyl ester phosphite, tetrakis (2,4-di-t-butylphenyl) (1,1-biphenyl) -4,4'-diylbisphos Phonite, bis (2,4-di-t-butylphenyl) pentaerythritol diphosphite, bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite, bis (2,4) -Dicumylphenyl) pentaerythritol-diphosphite, tetrakis (2,4-t-butylphenyl) (1,1-biphenyl) -4,4'-diylbisphosphonite, di-t-butyl-m-cresyl- Phosphonite, 4- [3-[(2,4,8,10-tetra-tert-butyldibenzo [d, f] [1,3,2] dioxaphosphepine) -6-yloxy] propyl] -2 -Methyl-6-tert-butylphenol and the like can be mentioned.

Further, a commercially available phosphorus-based antioxidant may be used as the phosphorus-based antioxidant, and such a commercially available phosphorus-based antioxidant is not limited to the following, but is, for example, Irgafos 168 ( Irgafos 168: Tris (2,4-di-t-butylphenyl) phosphite, manufactured by BASF), Irgafos 12: Tris [2-[[2,4,8,10-tetra-t-butyldibenzo [2,4,8,10-tetra-t-butyldibenzo [ d, f] [1,3,2] dioxaphosfefin-6-yl] oxy] ethyl] amine, manufactured by BASF), Irgafos 38: bis (2,4-bis (1,1-dimethyl) Ethyl) -6-methylphenyl) ethyl ester phosphite, made by BASF), ADEKA STAB 329K (ADK STAB-229K, made by ADEKA), ADEKA STAB PEP-36 (ADK STAB PEP-36, made by ADEKA), ADEKA STAB PEP-36A (made by ADEKA) ADK STAB PEP-36A, made by ADEKA), ADEKA STAB PEP-8 (ADK STAB PEP-8, made by ADEKA), ADEKA STAB HP-10 (ADK STAB HP-10, ADEKA), ADEKA STAB 2112 (ADK STAB 2112, ADEKA). ), ADEKA STAB 1178 (ADKA STAB 1178, ADEKA), ADEKA STAB 1500 (ADK STAB 1500, ADEKA) Sandstab P-EPQ (Clariant), Weston 618 (Weston 618, GE), Weston 619G (Weston) ), Ultranox 626 (Ultranox 626, manufactured by GE), Sumilizer GP: 4- [3-[(2,4,8,10-tetra-tert-butyldibenzo [d, f] [1,3]) 2] Dioxaphosfepine) -6-yloxy] propyl] -2-methyl-6-tert-butylphenol, manufactured by Sumitomo Chemical Co., Ltd.), HCA (9,10-dihydro-9-oxa-10-phosphaphenanthrene-10) -Oxide, manufactured by Sanko Co., Ltd.) and the like.
Among these commercially available phosphorus-based antioxidants, Irgafos 168, Adecastab PEP-36, Adecastab PEP-36A, Adecastab HP from the viewpoint of the effect of imparting thermal stability in the resin and the effect of combined use with various antioxidants. -10, Adecastab 1178 are preferable, and Adecastab PEP-36A and Adecastab PEP-36 are particularly preferable.
These phosphorus-based antioxidants may be used alone or in combination of two or more.

The sulfur-based antioxidant as the antioxidant is not limited to the following, but is, 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] (ADEKA STAB 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, Adecastab AO-412S and Cheminox PLS are preferable from the viewpoints of the effect of imparting thermal stability in the resin, the effect of being used in combination with various antioxidants, and the viewpoint of 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 it has the effect of improving thermal stability, and if the content is excessive, problems such as bleeding out during processing may occur. It is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, further preferably 1 part by mass or less, still more preferably 0.8 parts by mass or less, still more preferably, with respect to 100 parts by mass of the based resin. It is preferably 0.01 to 0.8 parts by mass, and particularly preferably 0.01 to 0.5 parts by mass.

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

－－Hindered amine-based light stabilizer －－
The methacrylic resin composition constituting the methacrylic resin molded product of the present embodiment can contain a hindered amine-based light stabilizer.
The hindered amine-based light stabilizer is not particularly limited, but is preferably a compound containing three or more ring structures. Here, the ring structure is preferably at least one selected from the group consisting of aromatic rings, aliphatic rings, aromatic heterocycles and non-aromatic heterocycles, and two or more ring structures are contained in one compound. If they have, they may be the same or different from each other.

The hindered amine-based light stabilizer is not limited to the following, but specifically, for example, bis (1,2,2,6,6-pentamethyl-4-piperidyl) [[3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl] methyl] 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- Piperidine) -N, N'-diformylhexamethylenediamine, dibutylamine 1,3,5-triazine N, N'-bis (2,2,6,6-tetramethyl-4-piperidyl-1,6) -A polycondensate 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-piperididiol 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-diethanol reaction product, bis (1-undecanoxy-2,2,6,6-tetramethylpiperidine-4-yl) Examples thereof include carbonate, 1,2,2,6,6-pentamethyl-4-piperidylmethacrylate, 2,2,6,6-tetramethyl-4-piperidylmethacrylate and the like.

Among them, bis (1,2,2,6,6-pentamethyl-4-piperidyl) [[3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl] methyl containing three or more ring structures. ] Butylmalonate, dibutylamine, 1,3,5-triazine, N, N'-bis (2,2,6,6-tetramethyl-4-piperidyl-1,6-hexamethylenediamine and N- (2) , 2,6,6-Tetramethyl-4-piperidyl) butylamine polycondensate, poly [{6- (1,1,3,3-tetramethylbutyl) amino-1,3,5-triazine-2, 4-Diyl} {2,2,6,6-tetramethyl-4-piperidyl) imino} hexamethylene {(2,2,6,6-tetramethyl-4-piperidyl) imino}], 1,2,2 , 6,6-Pentamethyl-4-piperidiol and β, β, β', β'-tetramethyl-2,4,8,10-tetraoxaspiro [5.5] undecane-3,9-diethanol reaction product , 2,2,6,6-Tetramethyl-4-piperidiol and β, β, β', β'-Tetramethyl-2,4,8,10-Tetraoxaspiro [5.5] Undecane-3,9 -A reaction product of diethanol is preferred.

The content of the hindered amine-based light stabilizer may be an amount that can improve the light stability, and if the content is excessive, problems such as bleeding out during processing may occur. , 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, based on 100 parts by mass of the methacrylic resin. It is even more preferably 0.01 to 0.8 parts by mass, and particularly preferably 0.01 to 0.5 parts by mass.

－－UV absorber －－
The methacrylic resin composition constituting the methacrylic resin molded product of the present embodiment may contain an ultraviolet absorber.
The ultraviolet absorber is not particularly limited, but is preferably an ultraviolet absorber having a maximum absorption wavelength of 280 to 380 nm, and is, for example, a benzotriazole-based compound, a benzotriazine-based compound, a benzophenone-based compound, or an oxybenzophenone-based compound. , Benzoate-based compounds, phenol-based compounds, oxazole-based compounds, cyanoacrylate-based compounds, benzoxadinone-based compounds and the like.

Examples of benzotriazole compounds include 2,2'-methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazole-2-yl) phenol], 2- (3). 5-Di-tert-butyl-2-hydroxyphenyl) -5-chlorobenzotriazole, 2- (2H-benzotriazole-2-yl) -p-cresol, 2- (2H-benzotriazole-2-yl)- 4,6-bis (1-methyl-1-phenylethyl) phenol, 2-benzotriazole-2-yl-4,6-di-tert-butylphenol, 2- [5-chloro (2H) -benzotriazole-2 -Il] -4-Methyl-6-t-butylphenol, 2- (2H-benzotriazole-2-yl) -4,6-di-t-butylphenol, 2- (2H-benzotriazole-2-yl)- 4- (1,1,3,3-tetramethylbutyl) phenol, 2- (2H-benzotriazole-2-yl) -4-methyl-6- (3,4,5,6-tetrahydrophthalimidylmethyl) ) Phenol, methyl 3- (3- (2H-benzotriazole-2-yl) -5-t-butyl-4-hydroxyphenyl) propionate / reaction product of polyethylene glycol 300, 2- (2H-benzotriazole-2) -Il) -6- (Linear and side chain dodecyl) -4-methylphenol, 2- (5-methyl-2-hydroxyphenyl) benzotriazole, 2- [2-hydroxy-3,5-bis (α,) α-dimethylbenzyl) phenyl] -2H-benzotriazole, 3- (2H-benzotriazole-2-yl) -5- (1,1-dimethylethyl) -4-hydroxy-C7-9 side chain and linear alkyl Esther can be mentioned.
Among these, benzotriazole-based compounds having a molecular weight of 400 or more are preferable, and for example, in the case of a commercially available product, Chemisorb (registered trademark) 2792 (Cemipro Kasei), ADEKA STAB (registered trademark) LA31 (made by ADEKA Co., Ltd.), Tinubin (manufactured by ADEKA Co., Ltd.) Examples thereof include (registered trademark) 234 (manufactured by BASF).

Examples of benzotriazine compounds include 2-mono (hydroxyphenyl) -1,3,5-triazine compounds, 2,4-bis (hydroxyphenyl) -1,3,5-triazine compounds, and 2,4,6-tris. Examples thereof include (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 (2,4,6-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- Tris (2-hydroxy-3-methyl-4- (1- (2-ethoxyhexyloxy) -1-oxopropan-2-yloxy) phenyl) -1,3,5-triazine and the like can be mentioned.

Commercially available products may be used as the benzotriazine compound, for example, Chemisorb102 (manufactured by Chemipro Kasei Co., Ltd.), LA-F70 (manufactured by ADEKA Corporation), LA-46 (manufactured by ADEKA Corporation), and Tinubin 405 (manufactured by BASF). , Chinubin 460 (manufactured by BASF), Chinubin 479 (manufactured by BASF), Chinubin 1577FF (manufactured by BASF) and the like can be used.

Among them, 2,4-bis (2,4-dimethylphenyl) -6- [2-hydroxy-4- (3-alkyloxy) is excellent in compatibility with acrylic resins and excellent ultraviolet absorption characteristics. -2-Hydroxypropyloxy) -5-α-cumylphenyl] -s-triazine skeleton (“alkyloxy” means long-chain alkyloxy groups such as octyloxy, nonyloxy, decyloxy, etc.) It can be preferably used.

As the ultraviolet absorber, benzotriazole-based compounds and benzotriazine-based compounds having a molecular weight of 400 or more are preferable from the viewpoint of compatibility with the resin and volatilization during heating, and the ultraviolet absorber itself is heated during extrusion processing. Benzotriazine-based compounds are particularly preferable from the viewpoint of suppressing decomposition by UV rays.

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

Only one kind of these ultraviolet absorbers may be used alone, or two or more kinds thereof may be used in combination. By using two kinds of ultraviolet absorbers having different structures in combination, 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, moisture heat resistance, thermal stability, and molding processability and exhibits the effects of the present invention, but is 100 mass of methacrylic resin. 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. 3 parts by mass. Within this range, the balance of ultraviolet absorption performance, moldability, etc. is excellent.

--Release agent--
The methacrylic resin composition constituting the methacrylic resin molded product of the present embodiment can contain a mold release agent. The release agent is not limited to the following, but is not limited to, for example, fatty acid esters, fatty acid amides, fatty acid metal salts, hydrocarbon-based lubricants, alcohol-based lubricants, polyalkylene glycols, carboxylic acid esters, and carbonized products. Examples thereof include hydrocarbons such as paraffin-based mineral oils.

The fatty acid ester that can be used as the release agent is not particularly limited, and conventionally known fatty acid esters can be used.
Examples of the fatty acid ester include fatty acids having 12 to 32 carbon atoms such as lauric acid, palmitic acid, heptadecanoic acid, stearic acid, oleic acid, araquinic acid and behenic acid, and monovalent fatty acids such as palmityl alcohol, stearyl alcohol and behenyl alcohol. Ester compounds with fatty alcohols and polyvalent fatty alcohols such as glycerin, pentaerythritol, dipentaerythritol, sorbitan; complex esters of fatty acids, polybasic organic acids and monovalent fatty alcohols or polyhydric alcohols. Compounds and the like can be used.

Specific examples of the fatty acid ester include cetyl palmitate, butyl stearate, stearyl stearate, stearyl citrate, glycerin monocaprylate, glycerin monocaplate, glycerin monolaurate, glycerin monopalmitate, and glycerin dipalmitate. , Glycerin monostearate, glycerin distearate, glycerin tristearate, glycerin monooleate, glycerin dioleate, glycerin trioleate, glycerin monolinoleate, glycerin monobehenate, glycerin mono12-hydroxystearate, glycerinji 12-Hydroxystearate, glycerintri 12-hydroxystearate, glycerin diacet monostearate, glycerin enoic acid fatty acid ester, pentaerythritol adipate stearic acid ester, montanic acid partially saponified ester, pentaerythritol tetrastearate, dipentaerythritol Hexasterate, sorbitan tristearate and the like can be mentioned.
These fatty acid esters can be used alone or in combination of two or more.
Examples of commercially available products include Riken Vitamin's Rikemar series, Poem series, Riquester series, Riquemaster series, Kao's Exel series, Leodor series, Exepearl series, and Coconard series. Rikemar S-100, Rikemar H-100, Poem V-100, Rikemar B-100, Rikemar HC-100, Rikemar S-200, Poem B-200, Rikestar EW-200, Rikestar EW-400, Exel S -95, Leodor MS-50 and the like can be mentioned.

The fatty acid amide is also not particularly limited, and conventionally known fatty acid amides can be used.
Examples of the fatty acid amide 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. Substituted amides such as N-stearyl steayl amide, N-oleyl oleic acid amide, N-stearyl oleic acid amide, N-oleyl stealic acid amide, N-stearyl erucate amide, N-oleyl palmitate amide; methylol stealic acid. Methylolamides such as amides and methylolbechenic acid amides; methylene bisstearic acid amides, ethylene biscapric acid amides, ethylene bislauric acid amides, ethylene bisstearic acid amides (ethylene bisstearyl amides), ethylene bisisostearic acid amides, ethylene bishydroxylates. Stealic acid amide, ethylene bisbechenic acid amide, hexamethylene bissteeric acid amide, hexamethylene bisbechenic acid amide, hexamethylene bishydroxystearic acid amide, N, N'-distealyl adipic acid amide, N, N'-disteallyl Saturated fatty acid bisamides such as sevacinic acid amides; unsaturated fatty acid bisamides such as ethylene bisoleic acid amides, hexamethylene bisoleic acid amides, N, N'-diorail adipic acid amides, N, N'-diorail sevacinic acid amides; Examples thereof include aromatic bisamides such as m-xylylene bisstearic acid amide and N, N'-distearylisophthalic acid amide.
These fatty acid amides can be used alone or in combination of two or more.
Commercially available products include, for example, Diamid series (manufactured by Nihon Kasei), Amide series (manufactured by Nihon Kasei), Nikka Amide series (manufactured by Nihon Kasei), Methylol amide series, Bis Amide series, Slipax series (Nihon Kasei). , Kao wax series (manufactured by Kao), fatty acid amide series (manufactured by Kao), ethylene bisstearic acid amides (manufactured by Dainichi Chemical Industry Co., Ltd.) and the like.

The fatty acid metal salt refers to a metal salt of a higher fatty acid, for example, lithium stearate, magnesium stearate, calcium stearate, calcium laurate, calcium ricinolate, strontium stearate, barium stearate, barium laurate, barium ricinolate, etc. Zinc stearate, zinc laurate, zinc ricinolate, zinc 2-ethylhexoate, lead stearate, lead dibasic stearate, lead naphthenate, calcium 12-hydroxystearate, lithium 12-hydroxystearate and the like can be mentioned. Among them, calcium stearate, magnesium stearate, and zinc stearate are particularly preferable because the obtained transparent resin composition has excellent processability and extremely excellent transparency.
Examples of commercially available products include SZ series, SC series, SM series, and SA series manufactured by Sakai Chemical Industry Co., Ltd.
When the fatty acid metal salt is used, 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 above-mentioned mold release agent may be used alone or in combination of two or more.

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

The content of the mold release agent may be any amount as long as the effect as a mold release agent can be obtained, and if the content is excessive, problems such as bleed-out occurrence during processing and extrusion failure due to screw slippage 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, still more preferably 0.8 parts by mass with respect to 100 parts by mass of the methacrylic resin. The amount is less than or equal to parts, more preferably 0.01 to 0.8 parts by mass, and particularly preferably 0.01 to 0.5 parts by mass. When the amount is added in the above range, the decrease in transparency due to the addition of the mold release agent is suppressed, and the mold release defect during injection molding and the sticking to the metal roll during sheet molding tend to be suppressed. preferable.

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

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. A styrene-based polymer such as a block copolymer; further, for example, JP-A-59-20221, JP-A-63-27516, JP-A-51-129449, JP-A-52-56150. , Etc.; Acrylic rubber particles having a three- to four-layer structure; a rubbery polymer disclosed in Japanese Patent Application Laid-Open No. 60-17406, Japanese Patent Application Laid-Open No. 8-245854; International Publication No. 2014-002491. , Acrylate-based rubber-containing graph copolymer particles obtained by multi-stage polymerization; and the like.
Among these, from the viewpoint of obtaining good optical properties and mechanical properties, the composition is compatible with the styrene-acrylonitrile copolymer and the methacrylic resin containing the structural unit (X) having a ring structure in the main chain. Rubber-containing graft copolymer particles having a graft portion on the surface layer thereof are preferable.

The average particle diameters of the acrylic rubber particles, the methacrylic rubber-containing graph copolymer particles, and the rubbery polymer are the viewpoints of enhancing the impact strength and optical properties of the film obtained from the composition of the present embodiment. Therefore, it is preferably 0.03 to 1 μm, and more preferably 0.05 to 0.5 μm.

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

[Manufacturing method of methacrylic resin composition]
The method for producing the methacrylic resin composition of the present embodiment is not particularly limited as long as a composition satisfying the requirements of the present invention can be obtained. For example, a method of kneading using a kneader such as an extruder, a heating roll, a kneader, a roller mixer, and a Banbury mixer can be mentioned. Among them, kneading with an extruder is preferable in terms of productivity. The kneading temperature may be in accordance with the preferable processing temperature of the polymer constituting the methacrylic resin and other resins to be mixed, and is in the range of 140 to 300 ° C., preferably 180 to 280 ° C. as a guide. Further, it is preferable that the extruder is provided with a vent port for the purpose of reducing the volatile content.

Here, in the methacrylic resin composition of the present embodiment, the residual solvent amount (residual solvent amount) is preferably less than 1000 mass ppm, more preferably less than 800 mass ppm, still more preferably 700 mass ppm. Is less than.
Here, the remaining solvent refers to the polymerization solvent used at the time of polymerization (excluding alcohols) and the solvent used at the time of re-dissolving the resin obtained by the polymerization to make a solution, specifically. Examples of the polymerization solvent include aromatic hydrocarbons such as toluene, xylene, ethylbenzene and isopropylbenzene; ketones such as methylisobutylketone, butylcellosolve, methylethylketone and cyclohexanone; and polar solvents such as dimethylformamide and 2-methylpyrrolidone; Examples of the solvent used for redissolution include toluene, methyl ethyl ketone, methylene chloride and the like.

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

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

When the methacrylic resin composition of the present embodiment is used for film applications and the like, a polymerization reaction step, a liquid-liquid separation step, a liquid-solid separation step, a volatilization step, and granulation are performed for the purpose of reducing foreign substances. In one or more of the steps and the forming step, for example, a sintered filter having a filtration accuracy of 1.5 to 20 μm, a pleated filter, a leaf disk type polymer filter and the like are added to the filtration device to prepare the mixture. Is also a preferred method.

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

Glass transition temperature (Tg) for methacrylic resin composition, ratio of methanol-soluble content to total amount of methanol-soluble content and methanol-insoluble content to 100% by mass, yellowness index of methanol-insoluble content (yellowness index) YI), 680 nm permeability, Z average molecular weight (Mz), weight average molecular weight (Mw), number average molecular weight (Mn), and photoelastic coefficient _CR may be the same as described above for the methacrylic resin.

-Manufacturing method of methacrylic resin molded product-
The methacrylic resin molded product is formed by molding the methacrylic resin or the methacrylic resin composition. The method for producing the methacrylic resin molded product is not particularly limited, and various molding methods such as extrusion molding, injection molding, compression molding, calendar molding, inflation molding, and hollow molding can be used.
Various molded bodies using the methacrylic resin of the present embodiment or the resin composition thereof can be further subjected to surface functionalization treatments such as antireflection treatment, transparent conductive treatment, electromagnetic wave shielding treatment, and gas barrier treatment.

-Characteristics of methacrylic resin molded product-
The methacrylic resin molded product preferably has a YI of 0 to 35 at an optical path length of 80 mm, more preferably 1 to 30, and even more preferably 2 to 30. Further, as an index of the visual transmittance, the Y value at an optical path length of 80 mm measured under the same conditions as those in the above-mentioned YI measurement is preferably 60 to 95, more preferably 65 to 93, still more preferably 68. ~ 90. When the YI and Y values in the optical path length of 80 mm are in this range, it is possible to obtain a color tone and transparency suitable for use in a molded body of a long optical path such as a light guide plate.
The YI and Y values at an optical path length of 80 mm can be measured by the method described in Examples described later.

-Uses of methacrylic resin molded products-
The use of the methacrylic resin molded body is not particularly limited, but for example, it is used for sanitary and optical parts such as household goods, OA equipment, AV equipment, battery electrical equipment, lighting equipment, automobile parts, housings, and sanitary ware substitutes. Can be mentioned.
Examples of automobile parts include tail lamps, meter covers, headlamps, light guide bars, lenses, front plates of car navigation systems, and the like.
Optical components include light guide plates, diffusers, polarizing plate protective films, 1/4 wavelength plates, 1/2 wavelength plates used in displays such as liquid crystal displays, plasma displays, organic EL displays, field emission displays, and rear projection televisions. , A viewing angle control film, a retardation film such as a liquid crystal optical compensation film, a display front plate, a display substrate, a lens, a touch panel, and the like, and can be suitably used for a transparent substrate used for a solar cell and the like. In addition, in the fields of optical communication systems, optical exchange systems, optical measurement systems, or in optical products such as head mount displays and liquid crystal projectors, waveguides, lenses, optical fibers, optical fiber coating materials, LED lenses, lens covers, etc. Can also be used for.
It can also be used as a modifier for other resins.

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

<1. Measurement of polymerization conversion rate>
A part of the polymerization solution was collected, and the amount of the monomer remaining in the polymerization solution sample was adjusted by dissolving the sample in chloroform to prepare a 5% by mass solution, and adding n-decane as an internal standard substance. Using gas chromatography (GC-2010 manufactured by Shimadzu Corporation), the concentration of the monomer remaining in the sample was measured, and the total mass (a) of the monomer remaining in the polymerization solution was determined. Then, the total mass (a), the total mass (b) assuming that the total amount of the monomers added by the time the sample was collected remained in the polymerization solution, and the simple addition by the end of the polymerization step. From the total mass (c) of the monomer, the polymerization conversion rate (%) was calculated by the calculation formula: (ba) / c × 100.

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

<3. Glass transition temperature>
The glass transition temperature (Tg) (° C.) of the methacrylic resin was measured according to JIS-K7121.
First, about 10 mg of each of 4 test pieces (4 points) was cut out from a sample whose state was adjusted (leaved at 23 ° C. for 1 week) in a standard state (23 ° C., 65% RH).
Next, using a differential scanning calorimeter (Diamond DSC manufactured by Perkin Elmer Japan Co., Ltd.) under the condition of a nitrogen gas flow rate of 25 mL / min, the temperature rises from room temperature (23 ° C) to 200 ° C at 10 ° C / min. Warm (primary temperature rise) and hold at 200 ° C. for 5 minutes to completely thaw the sample, then cool down from 200 ° C. to 40 ° C. at 10 ° C./min, hold at 40 ° C. for 5 minutes, and then Of the DSC curves drawn during the temperature rise again (secondary temperature rise) under the above temperature rise conditions, the stepwise change partial curve at the time of the second temperature rise and each baseline extension line are equidistant in the vertical axis direction. The intersection with a certain straight line (intermediate point glass transition temperature) was measured as the glass transition temperature (Tg) (° C.). Four points were measured per sample, and the arithmetic mean of the four points (rounded to the nearest whole number) was used as the measured value.

<4. Measurement of photoelastic coefficient C _R >
The methacrylic resin obtained in the production examples and the production comparative examples was used as a press film using a vacuum compression molding machine to prepare a sample for measurement.
As specific sample preparation conditions, a vacuum compression molding machine (manufactured by Kondo Metal Industry Co., Ltd., SFV-30 type) was used, and the resin was preheated at 260 ° C. under reduced pressure (about 10 kPa) for 10 minutes, and then the resin was heated at 260 ° C. It was compressed at about 10 MPa for 5 minutes, depressurized and pressed, and then transferred to a cooling compression molding machine for cooling and solidification. The obtained press film was cured in a constant temperature and humidity chamber adjusted to 23 ° C. and a humidity of 60% for 24 hours or more, and then a test piece for measurement (thickness: about 150 μm, width: 6 mm) was cut out.
The photoelastic coefficient _CR (Pa ^-1 ) was measured using the birefringence measuring device described in detail in Polymer Engineering and Science 1999, 39, 2349-2357.
The film-shaped test piece was placed in a film tensioning device (manufactured by Imoto Seisakusho) similarly installed in a constant temperature and humidity chamber so that the chuck distance was 50 mm. Next, the device was arranged so that the laser light path of the birefringence measuring device (manufactured by Otsuka Electronics, RETS-100) was located at the center of the film, and the strain rate was 50% / min (chuck spacing: 50 mm, chuck moving speed:). The birefringence of the test piece was measured while applying tensile stress at 5 mm / min).
From the relationship between the absolute value of birefringence (| Δn |) and the elongation stress (σ _R ) obtained from the measurement, the slope of the straight line is obtained by the minimum square approximation, and the photoelastic coefficient ( _CR ) (Pa ^-1 ) is obtained. Calculated. For the calculation, data with an elongation stress between 2.5 MPa ≤ σ _R ≤ 10 MPa was used.
_CR = | Δn | / σ _R
Here, the absolute value of birefringence (| Δn |) is the value shown below.
| Δn | = | nx-ny |
(Nx: Refractive index in the stretching direction, ny: Refractive index in the direction perpendicular to the stretching direction in the plane)

<Measurement of color tone of 5.80 mm molded piece>
Using a methacrylic resin, an injection molding machine (AUTO SHOT C Series MODEL 15A, manufactured by FANUC Co., Ltd.) under the conditions of a molding temperature of 250 ° C. and a mold temperature of 90 ° C., thickness 3 mm x width 12 mm x length. A strip-shaped piece of 124 mm was produced.
After that, the obtained molded piece was cut into 80 mm in the longitudinal direction, and the molded piece was cut at a cutter rotation speed of 8500 rpm and a feed rate of 1 m / min using a polishing machine (Pla Beauty manufactured by Megalo Technica Co., Ltd.). Polished both end faces perpendicular to the longitudinal direction of.
The polished molded piece was placed using a colorimeter (COH300A, manufactured by Nippon Denshoku Kogyo Co., Ltd.) so that the polished end face was perpendicular to the light source, and the optical path length was 80 mm in a C light source 2 ° field view. The YI and the Y value as an index of the visual transmittance were measured.

[material]
The raw materials used in the production examples and production comparative examples described later are shown below.
[[Monomer]]
・ Methyl methacrylate (MMA): manufactured by Asahi Kasei Co., Ltd. ・ N-Phenyl maleimide (phMI): manufactured by Nippon Catalyst Co., Ltd. ・ N-cyclohexylmaleimide (chMI): manufactured by Nippon Catalyst Co., Ltd. Methyl hydroxymethyl) Methyl acrylate (MHMA): Combi Blocks, Monomethylamine: Mitsubishi Gas Chemical Company [[Initiator]]
-T-Butylperoxy-2-ethylhexanoate: "Perbutyl O" manufactured by NOF CORPORATION
1,1-di (t-amylperoxy) cyclohexane: "Luperox 531" manufactured by Alchema Yoshitomi Co., Ltd.
-T-Amilperoxyisononanoate: "Luperox 570" manufactured by Alchema Yoshitomi Co., Ltd.
[[Chain Transfer Agent]]
・ N-octyl mercaptan: manufactured by Kao Corporation ・ n-dodecyl mercaptan: manufactured by Kao Corporation [[allyl compound]]
-Allylcyclohexane (boiling point 153 ° C): manufactured by Tokyo Kasei Kogyo Co., Ltd.-Allylbenzene (boiling point 155 ° C): manufactured by Tokyo Kasei Kogyo Co., Ltd.-Diallyl ether (boiling point 94 ° C): manufactured by Tokyo Kasei Kogyo Co., Ltd. catalyst]]
・ Stearyl Phosphate / Distearyl Phosphate Mixture: manufactured by Sakai Chemical Industry Co., Ltd.

Hereinafter, the methods for producing the methacrylic resins of Examples and Comparative Examples will be specifically described.

[Example 1]
Weigh MMA 445.5 kg, phMI 44.0 kg, chMI 60.5 kg, chain transfer agent n-octyl mercaptan 0.55 kg, mXy 450 kg, and add to a 1.25 m ³ reactor equipped with a temperature controller with a jacket and a stirring blade. The mixture was stirred to obtain a mixed monomer solution.
The solution in the reactor was bubbling with nitrogen at a rate of 30 L / min for 1 hour to remove dissolved oxygen. After that, steam was blown into the jacket to raise the solution temperature in the reactor to 130 ° C., and 1.10 kg of t-butylperoxy-2-ethylhexanoate was dissolved in mXy4.9 kg while stirring at 50 rpm. Polymerization was initiated by adding the polymerization initiator solution at a rate of 1 kg / hour for 6 hours. During the polymerization, the temperature of the solution in the reactor was controlled at 130 ± 2 ° C. by controlling the temperature with a jacket.
The polymer solution was sampled 3.3 hours after the start of the polymerization, 6 hours after the start of the polymerization, and 8 hours after the start of the polymerization (at the end of the polymerization), and the polymerization conversion rate was analyzed from the remaining monomer concentration. It was 84.9% after 3 hours, 96.7% after 6 hours, and 96.8% after 8 hours.
After 8 hours had passed from the start of the polymerization, a polymerization solution containing a methacrylic resin having a ring structure in the main chain was obtained. 25.3 kg of allylcyclohexane was added to this polymerization solution, heated to a solution temperature of 145 ° C., and stirred for 2.5 hours.
This polymerization solution was supplied to a concentrator consisting of a tubular heat exchanger and a vaporization tank preheated to 170 ° C., and the concentration of the polymer contained in the solution was increased to 70% by mass. The obtained polymerization solution was supplied to a thin film evaporator having a heat transfer area of 0.2 m ² and devolatile. At this time, the temperature inside the apparatus was 280 ° C., the supply amount was 30 L / hr, the rotation speed was 400 rpm, and the degree of vacuum was 30 Torr. A methacrylic resin having an N-substituted maleimide structural unit was obtained.

[Example 2]
After completion of the polymerization, methacrylic resin pellets were obtained in the same manner as in Example 1 except that the amount of allylcyclohexane to be added was changed to 16.5 kg. The physical characteristics are shown in Table 1.

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

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

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

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

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

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

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

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

[Example 11]
MMA 400.3 kg, styrene 100.2 kg, n-dodecyl mercaptan 0.396 kg (corresponding to 800 mass ppm with respect to the total mass of all the monomers put into the polymerization system), and toluene 500.4 kg were weighed and the temperature by the jacket was measured. The mixture was added to a 1.25 m ³ reactor equipped with a regulator and a stirring blade and stirred to obtain a mixed monomer solution.
The solution in the reactor was then bubbled with nitrogen at a rate of 30 L / min for 1 hour to remove dissolved oxygen.
After that, steam was blown into the jacket to raise the solution temperature in the reactor to 120 ° C., and 0.253 kg of 1,1-di (t-amylperoxy) cyclohexane was dissolved in mXy 4.748 kg while stirring at 50 rpm. Polymerization was started by adding the obtained polymerization initiator solution at a rate of 1.0 kg / hour for 5 hours. As described above, the polymerization initiator was not added at the initial stage, but was added at a constant addition rate for a certain period of time.
During the polymerization, the temperature of the solution in the reactor was controlled at 120 ± 2 ° C. by adjusting the temperature with a jacket.
The polymerization solution was sampled 6 hours after the start of the polymerization, and the polymerization conversion rate was analyzed from the remaining monomer concentration. As a result, it was 96%. (Polymerization time = 6 hours).
Then, this polymerization solution was supplied to a concentrator consisting of a tubular heat exchanger and a vaporization tank preheated to 170 ° C., and the concentration of the polymer contained in the solution was increased to 70% by mass.
The obtained polymerization solution was supplied to a thin film evaporator having a heat transfer area of 0.2 m ² and devolatile.
At this time, the temperature inside the apparatus was 280 ° C., the supply amount was 30 L / hr, the rotation speed was 400 rpm, and the degree of vacuum was 30 Torr. To obtain a methacrylic resin.
It has a glutarimide-based structural unit using the obtained methacrylic resin, monomethylamine as an imidizing agent, and a meshing type co-rotating twin-screw extruder having a diameter of 15 mm and L / D = 90. A methacrylic resin was manufactured.
At that time, the oxygen concentration in the extruder was reduced to 1% or less by flowing nitrogen gas from the popper. The set temperature of each temperature control zone of the extruder was 250 ° C., the screw rotation speed was 300 rpm, the MS resin was supplied at 1 kg / hour, and the amount of monomethylamine supplied was 20 parts by mass with respect to 100 parts by mass of the methacrylic resin. A methacrylic resin was charged from the hopper, the resin was melted and filled with a kneading block, and then monomethylamine was injected from the nozzle. A seal ring was placed at the end of the reaction zone to fill the resin. The by-products and excess methylamine after the reaction were removed by reducing the vacuum degree of the vent port to 60 Torr. The resin that came out as a strand from the die provided at the outlet of the extruder was cooled in a water tank and then pelletized with a pelletizer.
Next, in a meshing type co-rotating twin-screw extruder with a mass of 15 mm and L / D = 90, the set temperature of each temperature control zone of the extruder was set to 230 ° C. and the screw rotation speed was 150 rpm from the hopper. The pellet obtained above is charged at a supply amount of 1 kg / hr, the resin is melted and filled with a kneading block, and then 0.8 mass by mass with respect to 100 parts by mass of the pellet-shaped resin from the nozzle. 1.3 parts by mass of allylcyclohexane was injected with 100 parts by mass of dimethyl carbonate and 100 parts by mass of the monomer. A reverse flight was placed at the end of the reaction zone to fill the resin. The by-products after the reaction and excess dimethyl carbonate and allylcyclohexane were removed by reducing the vacuum degree of the vent port to 100 Torr.
The resin that came out as a strand from the die provided at the outlet of the extruder was cooled in a water tank and then pelletized again with a pelletizer to obtain a methacrylic resin having a glutarimide-based structural unit.

[Example 12]
20 parts by mass of MMA, 5 parts by mass of methyl 2- (hydroxymethyl) acrylate, 25 parts by mass of toluene, in an autoclave equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen gas introduction tube whose inside is replaced with nitrogen in advance. 0.025 parts by mass of tris (2,4-di-t-butylphenyl) phosphite was charged as an organic phosphorus compound.
Then, while introducing nitrogen gas, the temperature was raised to 100 ° C., and 0.05 part by mass of t-amylperoxyisononanoate was added as a polymerization initiator, and at the same time, t-amylperoxyisononanoate 0.075. The dropping of the toluene solution containing a part by mass was started, and while dropping this over 1.5 hours, solution polymerization was carried out at about 105 to 110 ° C. under reflux, and the polymerization was further continued for 5.5 hours. Further, 20 parts by mass of MMA, 5 parts by mass of methyl 2- (hydroxymethyl) acrylate, and 25 parts by mass of toluene were added at a constant rate from 30 minutes after the start of polymerization over 2 hours.
The polymer solution was sampled 4 hours and 7.5 hours after the start of polymerization, and the polymerization conversion rate was analyzed from the remaining monomer concentration. 84.6% and 7.5 were analyzed after 4 hours. After hours it was 94.8%. The time average of the polymerization temperature from 0 hour to 7.5 hours after the start of polymerization was 105 ° C.
To the obtained polymer solution, 0.05 parts by mass of an organophosphorus compound stearyl phosphate / distearyl phosphate mixture was added as a cyclization catalyst, and cyclization condensation was performed at about 90 to 102 ° C. for 2 hours under reflux. The reaction was carried out.
Next, the obtained polymer solution is heated to 240 ° C. by a heater consisting of a multi-tube heat exchanger, and a biaxial structure equipped with a plurality of vent ports and a plurality of side feed ports downstream for devolatilization. By introducing it into an extruder, the cyclization reaction proceeded while devolatile.
In the twin-screw extruder, the obtained copolymer solution was supplied so as to have a resin equivalent of 15 kg / hour, and the conditions were a barrel temperature of 250 ° C., a rotation speed of 100 rpm, and a vacuum degree of 10 to 300 Torr. The resin composition melt-kneaded with a twin-screw extruder was extruded from a strand die, cooled with water, and then pelletized to obtain a resin composition.
Next, with a meshing type co-rotating twin-screw extruder with a mass of 15 mm and L / D = 90, the set temperature of each temperature control zone of the extruder was set to 230 ° C. and the screw rotation speed was 150 rpm from the hopper. The pellets obtained above are charged at a supply amount of 1 kg / hr, the resin is melted and filled with a kneading block, and then 1.1 mass with the total weight of the monomer as 100 parts by mass from the nozzle. A part of allylcyclohexane was injected. A reverse flight was placed at the end of the reaction zone to fill the resin. The excess allylcyclohexane after the reaction was removed by reducing the vacuum degree of the vent port to 100 Torr.
The resin that came out as a strand from the die provided at the outlet of the extruder was cooled in a water tank and then pelletized again with a pelletizer to obtain a methacrylic resin having a lactone-based structural unit.

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

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

[Comparative Example 3]
After completion of the polymerization, methacrylic resin pellets were obtained in the same manner as in Example 1 except that the allyl compound was not added. The physical characteristics are shown in Table 1.

[Comparative Example 4]
After completion of the polymerization, methacrylic resin pellets were obtained in the same manner as in Example 11 except that the allyl compound was not added. The physical characteristics are shown in Table 1.

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

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

The methacrylic resin of the present invention and the methacrylic resin composition are not only highly heat resistant and excellent in birefringence, but also extremely excellent in color tone and transparency.
The molded product for optical components obtained by using the methacrylic resin composition of the present invention includes, for example, a light guide plate, a display front plate, a touch panel, and a smartphone used for displays such as smartphones, PDA, tablet PCs, and liquid crystal televisions. Lenses for tablet PC cameras and optical lens components such as head mount displays and liquid crystal projectors, such as prism elements, waveguides, lenses, especially small thin-walled uneven thickness optical lenses, optical fibers, optical fiber coating materials, lenses, etc. Examples include a Fresnel lens, a phase plate equipped with a microlens array, an optical cover component, and the like. Examples of automobile parts include a light guide plate for an in-vehicle display; an in-vehicle meter panel; an optical component for a head-up display such as a front plate of a car navigation system, a combiner, and an optical cover component; an in-vehicle camera lens, a light guide rod, and the like. In addition, it is particularly preferably used for display device parts for digital signage that send information to a thin display connected to a network for the purpose of advertising, advertising, etc. in places such as camera focal boards, outdoors, stores, public institutions, and transportation facilities. can.

Claims (6)

A structural unit (X) having a ring structure in the main chain is included.
(A) The glass transition temperature (Tg) is more than 120 ° C and 160 ° C or less.
(B) The absolute value of the photoelastic coefficient is 3.0 × ^10-12 Pa ^-1 or less.
(C) The structural unit (X) is at least one selected from the group consisting of a structural unit derived from an N-substituted maleimide monomer, a glutarimide-based structural unit, and a lactone ring structural unit.
It is a method for manufacturing methacrylic resin.
After (co) polymerization of one or more monomer components, including a methacrylic acid ester monomer and a monomer having a ring structure and forming a structural unit (X) in the main chain, and / or After a cyclization reaction of a resin containing a structural unit derived from a methacrylic acid ester monomer obtained by (co) polymerization, the resin contained in the obtained resin and / or in a molten state is subjected to the above. A method for producing a methacrylic resin, which comprises adding 0.10 to 5.0 parts by mass of an allyl compound to 100 parts by mass of a total amount of monomer components and mixing them. The method for producing a methacrylic resin according to claim 1, wherein the amount of the allyl compound added is 0.50 to 3.0 parts by mass with respect to 100 parts by mass of the total amount of the monomer components. The method for producing a methacrylic resin according to claim 1 or 2, wherein the allyl compound is at least one selected from the group consisting of an allyl alkyl compound, an allyl aryl compound, and an allyl ether compound. The method for producing a methacrylic resin according to any one of claims 1 to 3, wherein the allyl compound has a boiling point in the range of 90 to 300 ° C. The method for producing a methacrylic resin according to claim 4, wherein the allyl compound has a boiling point in the range of 120 to 250 ° C. The method for producing a methacrylic resin according to any one of claims 1 to 5, wherein the temperature of the solution to which the allyl compound is added is 100 ° C. or higher, and the mixture is stirred and mixed for 30 minutes or longer.