JP2006104376A - Methacrylic resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a methacrylic resin composition that prevents heat discoloration by an organic disulfide compound without impairing heat stability. <P>SOLUTION: The methacrylic resin composition is obtained by mixing a methacrylic resin with an organic disulfide compound and a phosphorous ester compound represented by formula (I) (R<SP>1</SP>, R<SP>2</SP>, R<SP>4</SP>and R<SP>5</SP>are each independently a hydrogen atom, an alkyl group, a cycloalkyl group, an alkylcycloalkyl group, an aralkyl group or a phenyl group; R<SP>3</SP>is a hydrogen atom or an alkyl group; X is a single bond, a sulfur atom or a bifunctional group represented by formula (I-1); A is an alkylene group or a bifunctional group represented by formula (I-2); one of Y and Z is a hydroxy group, an alkoxy group or an aralkyloxy group and the other is a hydrogen atom or an alkyl group). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a methacrylic resin composition, and more particularly to a methacrylic resin composition in which an organic disulfide compound is blended with a methacrylic resin.

Since the methacrylic resin is excellent in transparency, the methacrylic resin molded product obtained by heating and melting the methacrylic resin is used for various indoor and outdoor uses such as optical parts, signboards, lighting fixtures, and nameplates. .

However, the methacrylic resin has a problem that heat stability is low and thermal decomposition is likely to occur due to heat melting.

A methacrylic resin composition in which an organic disulfide compound is blended with a methacrylic resin is known as a material that has excellent thermal stability and can suppress the thermal decomposition of the methacrylic resin due to heat melting to give a methacrylic resin molded product. The composition has a problem that a slight coloration occurs upon heating and melting.

As a method for preventing thermal coloring by an organic disulfide compound, Patent Document 1 (Japanese Patent Laid-Open No. Sho 54-122351) discloses a method of further blending phosphorous acid triesters. In addition, the phosphorous acid triesters have a problem in that the thermal stability is impaired, and the molded body tends to have a poor appearance.

JP 54-122351 A JP-A-10-273494 J. et al. R. Hwand K. S. Rthiraj “Science of Synthesis”, Vol. 4, ed. by I. Fleming, Georg Thieme Verlag (2002) p187

〔式中、式中、Ｒ¹、Ｒ²、Ｒ⁴およびＲ⁵はそれぞれ独立して水素原子、炭素数１〜８の
アルキル基、炭素数５〜８のシクロアルキル基、炭素数６〜１２のアルキルシクロアルキル基、炭素数７〜１２のアラルキル基またはフェニル基を示し、Ｒ³は水素原子または炭素数１〜８のアルキル基を示し、Ｘは単結合、硫黄原子または式（Ｉ−１）

（式中、Ｒ⁶は水素原子、炭素数１〜８のアルキル基または炭素数５〜８のシクロアルキル基を示す。）
で示される２価の基を示し、Ａは炭素数２〜８のアルキレン基または式（Ｉ−２）

（式中、Ｒ⁷は単結合または炭素数１〜８のアルキレン基を示し、＊は酸素原子側に結合していることを示す。）
で示される２価の基を示し、ＹおよびＺは、いずれか一方がヒドロキシル基、炭素数１〜８のアルコキシ基または炭素数７〜１２のアラルキルオキシ基を示し、もう一方が水素原子または炭素数１〜８のアルキル基を示す。〕
で示される亜リン酸エステル化合物を配合して得られる組成物は、熱安定性に優れ、加熱溶融時の着色をも防止できることを見出し、本発明に至った。 Therefore, as a result of intensive studies to develop a methacrylic resin composition capable of preventing thermal coloring by an organic disulfide compound without impairing thermal stability, the present inventor, together with the organic disulfide compound and the methacrylic resin, the compound of formula (I)

[Wherein, R ¹ , R ² , R ⁴ and R ⁵ are each independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms, or 6 to 12 carbon atoms. An alkylcycloalkyl group, an aralkyl group having 7 to 12 carbon atoms or a phenyl group, R ³ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, X is a single bond, a sulfur atom or a compound represented by formula (I-1 )

(In the formula, R ⁶ represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or a cycloalkyl group having 5 to 8 carbon atoms.)
Wherein A represents an alkylene group having 2 to 8 carbon atoms or a compound represented by formula (I-2)

(In the formula, R ⁷ represents a single bond or an alkylene group having 1 to 8 carbon atoms, and * represents that it is bonded to the oxygen atom side.)
Y and Z are either a hydroxyl group, an alkoxy group having 1 to 8 carbon atoms or an aralkyloxy group having 7 to 12 carbon atoms, and the other is a hydrogen atom or carbon. The alkyl group of number 1-8 is shown. ]
The composition obtained by blending the phosphite compound represented by the above has been found to be excellent in thermal stability and prevent coloration upon heating and melting, and has led to the present invention.

That is, the present invention provides a methacrylic resin composition comprising an organic disulfide compound and a phosphite compound represented by the above formula (I) in a methacrylic resin.

According to the methacrylic resin composition of the present invention, it is possible to produce a methacrylic resin molded body by molding without causing thermal decomposition or coloring during heating and melting.

The methacrylic resin used in the present invention is a polymer obtained by polymerizing a monomer containing methyl methacrylate as a main component, specifically a monomer containing 50% by mass or more of methyl methacrylate, Polymethyl methacrylate obtained by polymerizing methyl acid alone may be used, or may be a copolymer of 50% by mass or more of methyl methacrylate and 50% by mass or less of a monomer copolymerizable therewith. Good. Examples of monomers copolymerizable with methyl methacrylate include ethyl methacrylate, propyl methacrylate, butyl methacrylate, benzyl methacrylate, 2-ethylhexyl acrylate, cyclohexyl methacrylate, bornyl methacrylate, adamantyl methacrylate, and methacrylic acid. Methacrylate esters such as cyclopentadienyl acid,
Acrylic esters such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, bornyl acrylate, adamantyl acrylate, and cyclopentadienyl acrylate ,
Unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, itaconic acid, maleic anhydride, itaconic anhydride and their anhydrides, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxy acrylate Hydroxyl group-containing monomers such as propyl, monoglycerol acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, monoglycerol methacrylate, acrylamide, methacrylamide, acrylonitrile, methacrylonitrile, diacetone acrylamide, methacryl Nitrogen-containing monomers such as dimethylaminoethyl acid, epoxy group-containing monomers such as allyl glycidyl ether, glycidyl acrylate, and glycidyl methacrylate, and styrene and α-methylstyrene. Such as alkylene monomer and the like.

Examples of the organic disulfide compound include dimethyl disulfide, diethyl disulfide, di-n-propyl disulfide, di-n-butyl disulfide, di-sec-butyl disulfide, di-tert-butyl disulfide, di-tert-amyl disulfide, dicyclohexyl disulfide , Di-tert-octyl disulfide, di-n-dodecyl disulfide, di-tert-dodecyl disulfide and the like. Di-tert-alkyl disulfide is preferable, and di-tert-dodecyl disulfide is more preferable. These compounds are used alone or in combination of two or more.

The amount of the organic disulfide compound is usually 0.1 ppm or more in that the effect of suppressing thermal decomposition is sufficient, and an effect commensurate with the amount added is obtained, and 5000 ppm in that it is economically advantageous. It is below, Preferably it is the range of 1 ppm-2000 ppm.

Examples of the alkyl group having 1 to 8 carbon atoms represented by R ¹ , R ² , R ⁴ and R ⁵ in the phosphite compound represented by the formula (I) include, for example, a methyl group, an ethyl group, and an n-propyl group. I-propyl group, n-butyl group, i-butyl group, s-butyl group, t-butyl group, t-pentyl group, i-octyl group, t-octyl group, 2-ethylhexyl group, etc. Examples of the cycloalkyl group having 5 to 8 carbon atoms include a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group. Examples of the alkylcycloalkyl group having 6 to 12 carbon atoms include 1-methyl Examples thereof include a cyclopentyl group, 1-methylcyclohexyl group, 1-methyl-4-i-propylcyclohexyl group, and examples of the aralkyl group having 7 to 12 carbon atoms include Examples include a benzyl group, an α-methylbenzyl group, an α, α-dimethylbenzyl group.

R ¹ and R ⁴ are preferably each independently an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms, or an alkylcycloalkyl group having 6 to 12 carbon atoms, a t-alkyl group, More preferably, it is a cyclohexyl group or a 1-methylcyclohexyl group. R ² is preferably an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms, or an alkylcycloalkyl group having 6 to 12 carbon atoms, and preferably an alkyl group having 1 to 5 carbon atoms. More preferred is a methyl group, t-butyl group or t-pentyl group. R ⁵ is preferably a hydrogen atom, an alkyl group having 1 to 8 carbon atoms or a cycloalkyl group having 5 to 8 carbon atoms, and more preferably a hydrogen atom or an alkyl group having 1 to 5 carbon atoms.

Examples of the alkyl group having 1 to 8 carbon atoms represented by R ³ are the same as those described above. R ³ is preferably a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and more preferably a hydrogen atom or a methyl group.

When X is a divalent group represented by the formula (I-1), examples of the alkyl group having 1 to 8 carbon atoms and the cycloalkyl group having 5 to 8 carbon atoms represented by R ⁶ are the same as those described above. Things can be illustrated.

X is preferably a single bond or a divalent group represented by the formula (I-1), and more preferably a single bond. When X is a divalent group represented by the formula (I-1), R ⁶ is a hydrogen atom, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i- A butyl group or a t-butyl group is preferred.

Examples of the alkylene group having 2 to 8 carbon atoms represented by A include an ethylene group, a propylene group, a butylene group, a pentamethylene group, a hexamethylene group, an octamethylene group, and a 2,2-dimethyl-1,3-propylene group. Is mentioned. When A is a divalent group represented by the formula (I-2), examples of the alkylene group having 1 to 8 carbon atoms represented by R ⁷ include a methylene group, an ethylene group, a propylene group, and a butylene group. , Pentamethylene group, hexamethylene group, octamethylene group, 2,2-dimethyl-1,3-propylene group and the like.

A is preferably an alkylene group having 2 to 8 carbon atoms, and more preferably a propylene group. When A is a divalent group represented by the formula (I-2), R ⁷ is preferably a single bond or an ethylene group.

Examples of the alkyl group having 1 to 8 carbon atoms represented by Y or Z can include the same ones as described above. As the alkoxy group having 1 to 8 carbon atoms, the alkyl group moiety thereof is the one having 1 to 8 carbon atoms. Examples of the aralkyloxy group having 7 to 12 carbon atoms include those having the same aralkyl group as the aralkyl group having 7 to 12 carbon atoms. it can.

〔式中、Ｒ¹、Ｒ²、Ｒ³およびＸはそれぞれ前記と同じ意味を示す。〕
で示される化合物、三ハロゲン化リンおよび式（III）

〔式中、Ｒ⁴、Ｒ⁵、Ａ、ＹおよびＺはそれぞれ前記と同じ意味を示す。〕
で示される化合物を反応させることにより、製造することができる〔特許文献２：特開平１０−２７３４９４号公報〕。なお、亜リン酸エステル化合物（Ｉ）には、特許文献２〔特開平１０−２７３４９４号公報〕に記載されるように、耐加水分解性を向上させるため、アミン類やハイドロタルサイト類のような酸結合金属塩などを配合しておいてもよい。 Phosphite compound (I) is, for example, represented by the general formula (II)

[Wherein R ¹ , R ² , R ³ and X each have the same meaning as described above. ]
A compound represented by the formula: phosphorus trihalide and formula (III)

[Wherein, R ⁴ , R ⁵ , A, Y and Z each have the same meaning as described above. ]
It can manufacture by making the compound shown by react [patent document 2: Unexamined-Japanese-Patent No. 10-273494]. In addition, as described in Patent Document 2 (Japanese Patent Application Laid-Open No. 10-273494), the phosphite compound (I) includes amines and hydrotalcites so as to improve hydrolysis resistance. An acid-bonded metal salt or the like may be added.

The compounding amount of the phosphite compound (I) is usually 0.05 mass times or more with respect to the organic disulfide compound in terms of the effect of preventing thermal coloring, and an effect commensurate with the compounding amount is obtained. In terms of being economically advantageous and having a sufficient effect of suppressing thermal decomposition, it is 100 mass times or less, preferably 0.1 mass times to 50 mass times.

The methacrylic resin composition of the present invention is produced, for example, by a method in which an organic disulfide compound and a phosphite compound (I) are blended with a monomer mainly composed of methyl methacrylate or a partial polymer thereof and polymerized. be able to.

The organic disulfide compound and the phosphite compound (I) may be blended as a premixed composition or separately.

Examples of the polymerization method include usual polymerization methods such as bulk polymerization method (bulk polymerization method), solution polymerization method, emulsion polymerization method and suspension polymerization method, but additives for polymerization such as stabilizers and emulsifiers. Bulk polymerization and solution polymerization are preferred in that they can be easily polymerized without using any of them, and there are few impurities, and an excellent transparent optical material can be easily obtained.

In order to obtain a methacrylic resin composition by a bulk polymerization method or a solution polymerization method, specifically, for example, an organic disulfide compound, a phosphite compound (I) and a polymerization starter are added to a monomer mainly composed of methyl methacrylate. An agent is added and bulk polymerization is performed to obtain a partial polymer having a polymer content of 40% by mass to 70% by mass, and an unpolymerized monomer is devolatilized from the partial polymer to obtain a polymer. Further, the organic disulfide compound and the phosphite compound (I) may be added to the partially polymerized product obtained after bulk polymerization of the monomers, and devolatilized. Furthermore, you may add an organic disulfide compound and a phosphite compound (I) to the polymer after devolatilization. A chain transfer agent, a release agent, an ultraviolet absorber and the like may be added in advance to the monomer used in the bulk polymerization method or the solution polymerization method.

Further, an organic disulfide compound and a phosphite compound (I) are added to a powdered or pelleted methacrylic resin obtained by a method such as an emulsion polymerization method or a suspension polymerization method or a pulverized product thereof, and a Henschel mixer, V You may mix with mixers, such as a type | mold blender, and may melt-knead with kneaders, such as a uniaxial kneader and a biaxial kneader. Mixing by a mixer or melt-kneading by a kneader is preferably performed in an atmosphere of an inert gas such as nitrogen gas or argon gas.

In addition, the powdery or pellet-like methacrylic resin obtained by the above method by adding one of the organic disulfide compound and the phosphite compound (I) during bulk polymerization or solution polymerization, or the remaining compound in the pulverized product thereof And may be melt-kneaded by the above method.

Thus, the methacrylic resin composition of the present invention in which the organic disulfide compound and the phosphite compound (I) are blended with the methacrylic resin is obtained. However, since such a composition does not cause coloration during melt molding, It is suitable for various uses.

As a method for molding the methacrylic resin composition in a heated and melted state, for example, the methacrylic resin composition may be heated and melt-kneaded with a kneader and then molded with a molding machine. Examples of the molding method include an injection molding method in which an injection molding machine is used as a molding machine and injection is performed in a mold, and an extrusion molding method in which an extrusion molding machine is used as the molding machine to perform extrusion molding from a die. When a methacrylic resin composition is obtained by adding an organic disulfide compound and an organosilicon compound to a methacrylic resin and melt-kneading with a kneader, the resulting methacrylic resin composition is sent to a molding machine in a molten state. May be. The molding temperature is usually 230 ° C. or higher, but for example, molding can be performed at 260 ° C. or higher, and is usually 290 ° C. or lower.

The methacrylic resin composition of the present invention can be used for various indoor and outdoor uses such as optical parts, signboards, lighting fixtures, nameplates, etc., and in particular, lenses, prisms, conductive lenses in display devices such as liquid crystal displays and projection televisions. It can use suitably for uses, such as a light body and a front board.

EXAMPLES Hereinafter, although the Example demonstrates the manufacturing method of this invention in detail, this invention is not limited by these Examples.

In addition, evaluation in each Example was performed with the following method.
(1) Acrylic resin composition from 50 ° C. to 430 ° C. at a nitrogen flow rate of 200 ml / min and a heating rate of 2 ° C./min using a heat-stable TG-DTA apparatus [“TG / DTA6300”, manufactured by Seiko Instruments Inc.] Weight loss was measured while raising the temperature. The loss ratio in the range of 220 ° C. to 300 ° C. was calculated with the loss amount in the range of 220 ° C. to 430 ° C. being 100. The smaller this value, the better the thermal stability.
(2) Molding colorability The end face of the test piece obtained in each Example was polished with a polishing machine ["Plavity PB-100" manufactured by Asahi Megaro Co., Ltd.], and then the spectrophotometer ["U-4000", Hitachi Manufactured by Seisakusho Co., Ltd.], measuring 200 mm path transmittance in the wavelength range of 380 to 780 nm, obtaining XYZ values from the obtained transmittance according to the method described in JIS Z-8722, and determining the yellowness according to the method described in JIS K-7105. Asked. The average value of _yellowness (YI _avr ) determined for two test pieces was _defined as molding colorability. It shows that there is little coloring at the time of shaping _| molding, so that the average value ( _YIavr ) of _yellowness is small.

The compounds used in each example are as follows.
Compound (1): 6- [3- (3-Methyl-4-hydroxy-5-t-butylphenyl) propoxy] -2,4,8,10-tetra-t-butyldibenzo [d, f
] [1,3,2] dioxaphosphepine In this compound (1), R ¹ , R ² and R ⁴ in formula (I) are each a t-butyl group, R ³ is a hydrogen atom, A compound in which R ⁵ is a methyl group, X is a single bond, A is a propylene group, Y is a hydroxyl group, and Z is a hydrogen atom. This compound (1) was produced by the method described in Example 9 of JP-A-10-273494.

Example 1
100 parts by mass of methyl methacrylate (monomer), 0.017 parts by mass of a polymerization initiator [1,1-di (t-butylperoxy) 3,3,5-trimethylcyclohexane], di-tert-dodecyl disulfide 0.01 parts by mass of (DDS) and 0.01 parts by mass of compound (1) were blended and sealed in a small SUS pressure vessel (Om Lab Tech Co., Ltd.), and the interior was purged with nitrogen. The pressure vessel was immersed in an oil bath adjusted to 190 ° C. and heated for 10 minutes, then immersed in ice water and cooled for 30 minutes to obtain a mixture of a monomer and a polymer. The polymerization rate in this mixture was 15%. The resulting mixture was vacuum-dried at 120 ° C. overnight to volatilize the monomer to obtain a methacrylic resin composition containing polymethylmethacrylate containing DDS and compound (1). This methacrylic resin composition contains 0.067 parts by mass of DDS and 0.067 parts by mass of compound (1) per 100 parts by mass of polymethyl methacrylate. The results of evaluating the thermal stability of the resulting methacrylic resin composition are shown in Table 1.

Comparative Example 1
The thermal stability of the resulting polymer was evaluated in the same manner as in Example 1 except that di-tert-dodecyl disulfide (DDS) and 1,1,2,2-tetraphenyldisilane (TPDS) were not used. . The results are shown in Table 1.

Table 1
━━━━━━━━━━━━━━━━━━━━━━━━
Content ^{* 1} TG measurement
DDS compound (1) Thermal stability
(Mass part) (mass part)
━━━━━━━━━━━━━━━━━━━━━━━━
Example 1 0.067 0.067 20
Comparative Example 1 0.000 0.000 30
━━━━━━━━━━━━━━━━━━━━━━━━
* 1: The content per 100 parts by mass of polymethyl methacrylate is shown.
DDS: Di-tert-dodecyl disulfide

Reference example 1
To a fully mixed polymerization reactor, 95.8 parts by weight of methyl methacrylate (monomer), 4.0 parts by weight of methyl acrylate (monomer), 0.17 parts by weight of a chain transfer agent [octyl mercaptan], di -Tert-dodecyl disulfide (DDS) 0.002 parts by mass, UV absorber ["Hostavin PR-25", manufactured by Clariant Co., Ltd.] 0.008 parts by mass and polymerization initiator [1,1-di (t-butylperoxy) 3,3,5-trimethylcyclohexane] at a composition ratio of 0.044 parts by mass is continuously fed, polymerized to an average polymerization rate of 56% at an average residence time of 20 minutes and a temperature of 175 ° C. A mixture containing an acid methyl copolymer and a monomer was continuously obtained. The resulting mixture was heated to 200 ° C. and led to a vented devolatilizing extruder, and the monomer was devolatilized from the vent at 240 ° C., and a mold release agent (stearyl alcohol) was added to 100 parts by mass of the polymer. It added so that it might become 0.1 mass part. The polymer after devolatilization was extruded in a molten state, cooled with water, and then cut into pellets. The obtained pellet contains 0.0037 parts by mass of di-tert-dodecyl disulfide (DDS) per 100 parts by mass of methyl methacrylate-methyl acrylate copolymer.

Example 2
0.1 parts by mass of the compound (1) is added to 100 parts by mass of the pellets obtained in Reference Example 1, and the cylinder temperature is set to 230 ° C. using a 40 mm single screw extruder (manufactured by Tanabe Plastics Co., Ltd.). Then, it was melt-kneaded and pelletized to obtain a methacrylic resin composition.

The obtained methacrylic resin composition was heated and melted at 280 ° C. using an injection molding machine [“IS130FII” manufactured by Toshiba Machine Co., Ltd.], repeatedly injection molded in a molding cycle of 1 minute, and 200 × 120 A flat molded body of 3 mm was obtained. The molding colorability of each of the 11th and 12th moldings of the molding cycle was evaluated, and YI _avr was determined. The results are shown in Table 2.

Example 3
The methacrylic resin composition was heated in the same manner as in Example 2 except that the heating and melting temperature was 280 ° C. and the molding cycle was 6 minutes. Evaluation was made to determine YI _avr . The results are shown in Table 2.

Comparative Example 2
Except that the compound (1) was not added, the same procedure as in Example 2 was carried out to obtain pellets, to obtain molded articles, and evaluation of molding colorability for the molded body at the 11th molding cycle and the 12th molded body at the molding cycle, respectively. And YI _avr was obtained. The results are shown in Table 2.

Comparative Example 3
A molded product was obtained in the same manner as in Example 2 except that the heating and melting temperature of the methacrylic resin composition was 280 ° C. and the molding cycle was 6 minutes, and the molded product of the sixth molding cycle and the seventh molded product were obtained. The molding colorability of each was evaluated and YI _avr was determined. The results are shown in Table 2.

Table 2
━━━━━━━━━━━━━━━━━━━━━━━
YI _avr
280 ° C / 1 minute 280 ° C / 6 minutes
━━━━━━━━━━━━━━━━━━━━━━━
Example 2 10 −
Example 3-16
Comparative Example 2 19 −
Comparative Example 3-29
━━━━━━━━━━━━━━━━━━━━━━━

Claims (1)

To methacrylic resin, organic disulfide compound and formula (I)

[Wherein, R ¹ , R ² , R ⁴ and R ⁵ are each independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms, or 6 to 12 carbon atoms. An alkylcycloalkyl group, an aralkyl group having 7 to 12 carbon atoms or a phenyl group, R ³ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, X is a single bond, a sulfur atom or a compound represented by formula (I-1 )

(In the formula, R ⁶ represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or a cycloalkyl group having 5 to 8 carbon atoms.)
Wherein A represents an alkylene group having 2 to 8 carbon atoms or a compound represented by formula (I-2)

(In the formula, R ⁷ represents a single bond or an alkylene group having 1 to 8 carbon atoms, and * represents that it is bonded to the oxygen atom side.)
Y and Z are either a hydroxyl group, an alkoxy group having 1 to 8 carbon atoms or an aralkyloxy group having 7 to 12 carbon atoms, and the other is a hydrogen atom or carbon. The alkyl group of number 1-8 is shown. ]
A methacrylic resin composition comprising a phosphite compound represented by the formula: