JP2006104377A - 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 an organosilicon compound represented by formula (I) (R<SB>1</SB>-R<SB>6</SB>are each independently a hydrogen atom, a residue of a 1-30C organic compound or a residue of a compound containing one or more silicon atoms; m is an integer of ≥0; l and n are each independently an integer of ≥1). <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 phosphite triesters. There was a problem that the thermal stability was impaired by the esters, and appearance defects were likely to occur in the molded product.

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

〔Ｒ₁〜Ｒ₆はそれぞれ独立に水素原子、炭素数１〜３０の有機化合物の残基またはケイ素原子を１つ以上含む化合物の残基を表す。ｍは０以上の整数を表し、ｌおよびｎはそれぞれ独立に１以上の整数を表す。但し、Ｒ₁とＲ₂とが結合してＳｉと一緒になって炭素数５〜７の非芳香族環を形成してもよい。そして、該非芳香族環はさらに１〜２個のベンゼン環と縮環してもよい。また、Ｒ₃とＲ₄とが結合してＳｉと一緒になって炭素数５〜７の非芳香族環を形成してもよい。そして、該非芳香族環はさらに１〜２個のベンゼン環と縮環してもよい。さらに、Ｒ₅とＲ₆とが結合してＳｉと一緒になって炭素数５〜７の非芳香族環を形成してもよい。そして、該非芳香族環はさらに１〜２個のベンゼン環と縮環してもよい。〕
で示される有機ケイ素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)

[R _{1 to} R ₆ each independently represents a hydrogen atom, a residue of an organic compound having 1 to 30 carbon atoms, or a residue of a compound containing one or more silicon atoms. m represents an integer of 0 or more, and l and n each independently represents an integer of 1 or more. However, R ₁ and R ₂ may combine to form a non-aromatic ring having 5 to 7 carbon atoms together with Si. The non-aromatic ring may further be condensed with 1 to 2 benzene rings. R ₃ and R ₄ may be bonded together with Si to form a non-aromatic ring having 5 to 7 carbon atoms. The non-aromatic ring may further be condensed with 1 to 2 benzene rings. Furthermore, R ₅ and R ₆ may be combined with Si to form a non-aromatic ring having 5 to 7 carbon atoms. The non-aromatic ring may further be condensed with 1 to 2 benzene rings. ]
The composition obtained by blending the organosilicon 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 a methacrylic resin and an organic disulfide compound and an organosilicon compound represented by the above formula (I).

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, preferably di-tert-alkyl disulfide, and more preferably di-tert-dodecyl disulfide. 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.

〔Ｒ₇〜Ｒ₉は、それぞれ独立に、水素原子、炭素数１〜３０のアルキル基、炭素数１〜３０のアルコキシル基、炭素数３〜８のシクロアルキル基、単環のアリール基、二環のアリール基、三環のアリール基、単環のアリールオキシ基、二環のアリールオキシ基、三環のアリールオキシ基、単環のアリールアルキル基、二環のアリールアルキル基または三環のアリールアルキル基を表す。但し、Ｒ₁〜Ｒ₉で表される炭素数３〜８のシクロアルキル基、単環のアリール基、二環のアリール基、三環のアリール基、単環のアリールオキシ基、二環のアリールオキシ基、三環のアリールオキシ基、単環のアリールアルキル基、二環のアリールアルキル基および三環のアリールアルキル基は、それぞれ、環を構成する炭素原子に結合する水素原子が置換基で置換されていてもよい。〕
で示される基などが挙げられる。 Examples of the residue of the organic compound having 1 to 30 carbon atoms represented by R _{1 to} R ₆ in formula (I) include an alkyl group having 1 to 30 carbon atoms, an alkoxyl group having 1 to 30 carbon atoms, and 3 carbon atoms. ˜8 cycloalkyl group, monocyclic aryl group, bicyclic aryl group, tricyclic aryl group, monocyclic aryloxy group, bicyclic aryloxy group, monocyclic arylalkyl group, bicyclic aryl Alkyl group, tricyclic arylalkyl group, formula (II)

[R _{7 to} R ₉ are each independently a hydrogen atom, an alkyl group having 1 to 30 carbon atoms, an alkoxyl group having 1 to 30 carbon atoms, a cycloalkyl group having 3 to 8 carbon atoms, a monocyclic aryl group, Ring aryl group, tricyclic aryl group, monocyclic aryloxy group, bicyclic aryloxy group, tricyclic aryloxy group, monocyclic arylalkyl group, bicyclic arylalkyl group or tricyclic aryl Represents an alkyl group. However, a cycloalkyl group having 3 to 8 carbon atoms represented by R _{1 to} R ₉ , a monocyclic aryl group, a bicyclic aryl group, a tricyclic aryl group, a monocyclic aryloxy group, and a bicyclic aryl In the oxy group, tricyclic aryloxy group, monocyclic arylalkyl group, bicyclic arylalkyl group and tricyclic arylalkyl group, the hydrogen atoms bonded to the carbon atoms constituting the ring are each substituted with a substituent. May be. ]
The group etc. which are shown are mentioned.

Examples of the alkyl group having 1 to 30 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, a sec-butyl group, a t-butyl group, and a t-butyl group. A pentyl group, i-octyl group, t-octyl group, 2-ethylhexyl group and the like can be mentioned.

Examples of the alkoxyl group having 1 to 30 carbon atoms include methyloxy group, ethyloxy group, n-propyloxy group, i-propyloxy group, n-butyloxy group, i-butyloxy group, sec-butyloxy group, and t-butyloxy group. , T-pentyloxy group, i-octyloxy group, t-octyloxy group, 2-ethylhexyloxy group and the like.

Examples of the cycloalkyl group having 3 to 8 carbon atoms include a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group.

Monocyclic aryl group, bicyclic aryl group, tricyclic aryl group, monocyclic aryloxy group, bicyclic aryloxy group, tricyclic aryloxy group, monocyclic arylalkyl group, bicyclic aryl Examples of the alkyl group and tricyclic arylalkyl group include an unsubstituted phenyl group,
A toluyl group, a t-butylphenyl group, a methoxyphenyl group, a chlorophenyl group, a methylthiophenyl group, and the like, an alkyl group having 1 to 8 carbon atoms, an alkoxyl group having 1 to 8 carbon atoms, and an alkylthio group having 1 to 8 carbon atoms. And a phenyl group substituted with a substituent selected from the group consisting of halogen atoms,
Unsubstituted biphenyl group,
1 or a substituent selected from the group consisting of an alkyl group having 1 to 8 carbon atoms (such as a methyl group and a t-butyl group), an alkoxyl group having 1 to 8 carbon atoms (such as a methoxy group) and a halogen atom (such as chloro); A biphenyl group substituted by two,
Unsubstituted naphthyl group,
α-Substituted by an alkyl group having 1 to 8 carbon atoms or an alkoxyl group having 1 to 8 carbon atoms such as α-methylnaphthyl group, α-methoxynaphthyl group, α-ethylnaphthyl group and α-ethoxynaphthyl group Substituted naphthyl groups,
β-naphthyl substituted with an alkyl group having 1 to 8 carbon atoms or an alkoxyl group having 1 to 8 carbon atoms such as β-methylnaphthyl group, β-methoxynaphthyl group, β-ethylnaphthyl group and β-ethoxynaphthyl group Group,
Unsubstituted terphenyl group,
1 or 2 selected from the group consisting of an alkyl group having 1 to 8 carbon atoms (such as a methyl group or t-butyl group), an alkoxyl group having 1 to 8 carbon atoms (such as a methoxy group) and a halogen atom (such as chloro). A terphenyl group substituted with a substituent,
Unsubstituted anthryl group,
1 or 2 selected from the group consisting of an alkyl group having 1 to 8 carbon atoms (such as a methyl group or t-butyl group), an alkoxyl group having 1 to 8 carbon atoms (such as a methoxy group) and a halogen atom (such as chloro). A terphenyl group substituted with a substituent,
Unsubstituted phenanthryl group; selected from the group consisting of an alkyl group having 1 to 8 carbon atoms (such as a methyl group and a t-butyl group), an alkoxyl group having 1 to 8 carbon atoms (such as a methoxy group) and a halogen atom (such as chloro) A phenanthryl group substituted with 1 or 2 substituents,
Unsubstituted indenyl group,
1 or 2 selected from the group consisting of an alkyl group having 1 to 8 carbon atoms (such as a methyl group or t-butyl group), an alkoxyl group having 1 to 8 carbon atoms (such as a methoxy group) and a halogen atom (such as chloro). An indenyl group substituted by a substituent,
Unsubstituted fluorenyl group,
1 or 2 selected from the group consisting of an alkyl group having 1 to 8 carbon atoms (such as a methyl group or t-butyl group), an alkoxyl group having 1 to 8 carbon atoms (such as a methoxy group) and a halogen atom (such as chloro). A fluorenyl group substituted with a substituent,
Unsubstituted phenoxy group,
1 or 2 selected from the group consisting of an alkyl group having 1 to 8 carbon atoms (such as a methyl group or t-butyl group), an alkoxyl group having 1 to 8 carbon atoms (such as a methoxy group) and a halogen atom (such as chloro). A phenoxy group substituted with a substituent,
Unsubstituted benzyl group,
Examples include benzyl groups (α-methylbenzyl group or α, α-dimethylbenzyl group) whose side chain is substituted with an alkyl group having 1 to 8 carbon atoms.

As preferred R _{1 to} R ₆ , an alkyl group having 1 to 8 carbon atoms,
An aryl group, an aryloxy group, and a formula (II) optionally substituted with an alkoxyl group having 1 to 8 carbon atoms, a phenoxy group, an alkyl group having 1 to 8 carbon atoms, or an alkoxyl group having 1 to 8 carbon atoms. And a hydrogen atom.

R _{1 to} R ₆ are more preferably substituted by an alkyl group having 1 to 8 carbon atoms, an alkoxyl group having 1 to 8 carbon atoms, a phenoxy group, an alkyl group having 1 to 8 carbon atoms, or an alkoxyl group having 1 to 8 carbon atoms. An aryl group, an aryloxy group, a hydrogen atom, and the like, which may be used.

Particularly preferred examples of R _{1 to} R ₆ include a phenoxy group, an aryl group which may be substituted with a C 1-8 alkyl group or a C 1-8 alkoxyl group.

R _{7 to} R ₉ are preferably an alkyl group having 1 to 8 carbon atoms, an aryl group optionally having 1 to 8 carbon atoms or an alkoxyl group having 1 to 8 carbon atoms, or a hydrogen atom. An aryl group or a hydrogen atom which may be substituted with an alkyl group having 1 to 8 carbon atoms or an alkoxyl group having 1 to 8 carbon atoms is more preferable, and an alkyl group having 1 to 8 carbon atoms or an alkoxyl group having 1 to 8 carbon atoms. An aryl group which may be substituted is particularly preferred.

Examples of the organosilicon compound (I) in the present invention include the following compounds. In the following examples, “n-Pr” represents an n-propyl group. “I-Pr” represents an i-propyl group. “N-Bu” represents an n-butyl group, and “i-Bu” represents an i-butyl group. “T-Bu” represents a t-butyl group. “N-Pen” represents an n-pentyl group. “T-Pen” represents a t-pentyl group. “N-Oct” represents an n-octyl group. “T-Oct” represents a t-octyl group. “Et” represents an ethyl group. “Ph” represents a phenyl group. “Ac” represents an acetyl group. “Me” represents a methyl group. “N-Hex” represents an n-hexyl group. “T-Hex” represents a t-hexyl group.

When R ₁ and R ₂ , R ₃ and R ₄ or R ₅ and R ₆ are combined and the bond together with Si forms a non-aromatic ring having 5 to 7 carbon atoms, the non-aromatic ring As the organosilicon compound when is further condensed with two benzene rings, the following compounds are exemplified.

Such an organosilicon compound (I) can be produced, for example, by a known method of coupling a disubstituted dihydrosilane in the presence of a suitable catalyst. A compound in which l in formula (I) is 1, n is 1 and m is 0 is disclosed in Non-Patent Document 1 [J. R. Hwand K. S. Rthiraj, “Science of Synthesis”, Vol. 4, ed. by I. Fleming, Georg Thieme Verlag (2002) p187].

The compounding amount of the organosilicon compound 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, which is economically advantageous. Moreover, it is 100 mass times or less at the point which the effect which suppresses thermal decomposition is enough, Preferably it is 0.1 mass times-50 mass times.

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

The organic disulfide compound and the organosilicon compound (I) may be blended as a premixed composition or may be blended 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 methacrylic resin composition 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, an organic silicon compound (I), and a polymerization initiator are added to a monomer mainly composed of methyl methacrylate. Is added to form 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 organosilicon compound (I) may be added to the partially polymerized product obtained after bulk polymerization of the monomers and devolatilized. Further, an organic disulfide compound and an organosilicon compound (I) may be added 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 an organosilicon compound are added to a powdery or pellet-like 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, a V-type blender, etc. You may mix with a mixer, 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, any one of the organic disulfide compound and the organosilicon compound (I) is added at the time of bulk polymerization or solution polymerization, and the remaining compound is added to the powdery or pellet-like methacrylic resin or pulverized product obtained by the above method. Alternatively, melt kneading may be performed by the above method.

Thus, the methacrylic resin composition of the present invention in which the organic disulfide compound and the organosilicon compound (I) are blended with the methacrylic resin is obtained. However, since such a composition does not cause coloration at the time of melt molding, such as optical parts. Suitable for various applications.

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 kneading machine, the resulting methacrylic resin composition is sent to a molding machine in a molten state and molded. 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 / DTA 6300”, 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.], the 200 mm path transmittance was measured in the wavelength range of 380 to 780 nm, the XYZ value was determined from the obtained transmittance according to the method described in JIS Z-8722, and the yellowness was determined 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.

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 (DDS) 0.01 parts by mass and 1,1,2,2-tetraphenyldisilane (TPDS) 0.0009 parts by mass, and sealed in a small SUS pressure vessel (Om Labtech Co., Ltd.) The inside was replaced 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 obtained mixture was vacuum-dried at 120 ° C. overnight to volatilize the monomer to obtain a methacrylic resin composition containing polymethylmethacrylate containing DDS and TPDS. This methacrylic resin composition contains 0.067 parts by mass of DDS and 0.006 parts by mass of TPDS 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 2.

Example 2 to Example 4
The amount of 1,1,2,2-tetraphenyldisilane (TPDS) used is 0.0028 parts by mass (Example 2), 0.0046 parts by mass (Example 3), 0.0091 parts by mass (Example 4). A methacrylic resin composition was obtained in the same manner as in Example 1 except that. The evaluation results of this methacrylic resin composition are shown in Table 2.

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 TPDS Thermal stability
(Mass) (Mass)
━━━━━━━━━━━━━━━━━━━━━
Example 1 0.067 0.006 16
Example 2 0.067 0.019 22
Example 3 0.067 0.031 22
Example 4 0.067 0.061 24
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 TPDS: 1,1,2,2-tetraphenyldisilane

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 0.0036 parts by mass of di-tert-dodecyl disulfide (DDS) per 100 parts by mass of methyl methacrylate-methyl acrylate copolymer.

Example 5
To 100 parts by mass of the pellets obtained in Reference Example 1, 0.1 part by mass of 1,1,2,2-tetraphenyldisilane (TPDS) was added, and a 40 mm uniaxial extruder [manufactured by Tanabe Plastics Co., Ltd. ] Was melt-kneaded at a cylinder temperature of 230 ° C. 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 3.

Example 6
The methacrylic resin composition was heated in the same manner as in Example 5 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 3.

Comparative Example 2
Except that 1,1,2,2-tetraphenyldisilane (TPDS) was not added, the same operation as in Example 5 was performed to obtain pellets, to obtain a molded body, and to the molded body at the 11th molding cycle and the 12th time. Each molded product was evaluated for molding colorability, and YI _avr was obtained. The results are shown in Table 2.

Comparative Example 3
Except for setting the heating and melting temperature of the methacrylic resin composition to 280 ° C. and setting the molding cycle to 6 minutes, the same procedure as in Comparative Example 2 was carried out, and the molding colorability of each of the molded body at the sixth molding cycle and the seventh molded body was evaluated. And YI _avr was obtained. The results are shown in Table 2.

Table 2
━━━━━━━━━━━━━━━━━━━━━━━
YI _avr
280 ° C / 1 minute 280 ° C / 6 minutes
━━━━━━━━━━━━━━━━━━━━━━━
Example 5 10 −
Examples 6-19
Comparative Example 2 19 −
Comparative Example 3-29
━━━━━━━━━━━━━━━━━━━━━━━

Claims (1)

Methacrylic resin with organic disulfide compound and formula (I)

[R _{1 to} R ₆ each independently represents a hydrogen atom, a residue of an organic compound having 1 to 30 carbon atoms, or a residue of a compound containing one or more silicon atoms. m represents an integer of 0 or more, and l and n each independently represents an integer of 1 or more. However, R ₁ and R ₂ may combine to form a non-aromatic ring having 5 to 7 carbon atoms together with Si. The non-aromatic ring may further be condensed with 1 to 2 benzene rings. R ₃ and R ₄ may be bonded together with Si to form a non-aromatic ring having 5 to 7 carbon atoms. The non-aromatic ring may further be condensed with 1 to 2 benzene rings. Furthermore, R ₅ and R ₆ may be combined with Si to form a non-aromatic ring having 5 to 7 carbon atoms. The non-aromatic ring may further be condensed with 1 to 2 benzene rings. ]
A methacrylic resin composition comprising an organosilicon compound represented by the formula: