JP2832485B2 - Modifier composition for polystyrene resin and method for producing polystyrene resin composition - Google Patents

Description

The present invention relates to a polystyrene resin modifier composition and a method for producing a polystyrene resin composition. More specifically, the present invention relates to a method for producing polystyrene resin by grafting polysiloxane. The present invention relates to a polystyrene-based resin modifier composition comprising a modified styrene-based thermoplastic elastomer and a method for producing a polystyrene-based resin composition.

[Prior art] Polystyrene resin is hard and has excellent high-frequency electrical insulation.
Resistant to acids and alkalis, softens from around 90 ° C, 13
Since it becomes a viscous liquid from about 0 ° C., injection molding is easy. On the other hand, in addition to the disadvantage of being brittle, the molded article has insufficient lubricity such as lubricity, and thus has problems in mold release, abrasion resistance, and lubricity during molding.

Conventionally, among the above-mentioned drawbacks of polystyrene resin, high impact polystyrene, AB
It has been improved by the development of S resin, ASA resin, etc., and the slidability has been improved by the following method.

1) Spray spraying of silicone oil such as polydimethylsiloxane at the time of molding 2) Blend of silicone oil such as polydimethylsiloxane 3) Copolymerization of styrene and olefin compound having polydimethylsiloxane chain 4) Styrene and poly Blend of a copolymer with an olefin compound having a dimethylsiloxane chain and a styrene-based resin having no other polysiloxane chain in the constituent unit 5) A block copolymer having a polystyrene unit and a polysiloxane unit 6) A polystyrene unit Of a block copolymer having a polysiloxane unit and a styrene resin having no other polysiloxane chain in its constituent unit 7) Graft copolymerization of a styrene monomer onto a polysiloxane chain 8) Styrene monomer on a polysiloxane chain To Blend of grafted copolymer and styrene-based resin having no other polysiloxane chain in the constituent unit [Problems to be Solved by the Invention] In the above-described conventional technique, silicone oil is sprayed onto a mold. The method has the disadvantages that oil sprayed as a release agent remains on the surface of the product, that the mold release agent must be frequently sprayed on the molding die, which is inefficient, and that the method is inefficient. It does not help to improve mobility.

Polystyrene resin modified by blending silicone oil, silicone is generally incompatible with the resin, so the silicone oil is easy to separate during molding or kneading, easy to bleed out, and does not mix uniformly Obstacles such as remarkably impairing the appearance, dust and the like, deteriorating physical properties, and particularly lowering impact strength are caused.

Copolymers of styrene and olefin compounds with polydimethylsiloxane chains are available from Yuhsuke Kawakami and RANMu
rthy and Yuya Yamashita (Die Makromolek
It can be synthesized by radicals, anion copolymerization and the like, including the method described in ulare Chemie, Vol. 185, page 9 (1984)). The yield is not enough, and furthermore, a large amount of homopolystyrene is by-produced, and it is difficult to remove it,
It is difficult to produce industrially. Therefore, it is difficult to blend this type of copolymer with other resins.

A block copolymer having a polystyrene unit and a polysiloxane unit is synthesized by anionic polymerization. The first examples are JCSaan, DJGardon and
Paper by S. Lindsay (Macromolecules, Volume 3, Volume 1)
(1970)) and a paper by A. Marsiat and V. Gallot (Die Makromolekulare Chemie, Vol. 176, p. 1641 (1
975)), JGZillox, JELRoovers and S. Bywater
(Macromolecules, vol. 8, p. 573 (197
5)), a method using a basic monofunctional initiator such as butyllithium. As a second example, a paper by DSBrown, KUFulcher and REWetton (Journal of Polymer Science Polymer Letter E
ddition, Vol. 8, p. 659 (1970), a paper by JWDean (Journal of Polymer Science Polymer Letter Eddi
tion, Volume 8, 677 (1970)), a paper by DJLegrant (Journal of Polymer Science, B 8, 195 (1970)), a paper by HGKim (Macromolecules, 5, 594 (1972) )), C.Price, AGWarson and
A paper by MTChov (Polymer, Vol. 13, p. 333 (197
2)), a paper by FR Jones (European Polymer Journ
al., vol. 10, p. 249 (1974)), etc., with a bifunctional initiator such as sodium naphthalene or lithium naphthalene.
A paper by Bajaj, SK Varshney and A. Misra (Journa
l of Polymer Science Polymer Chemistry Edditi
on, Vol. 18, p. 295 (1980)) using lithium biphenyl as an initiator.

All are obtained by a method of polymerizing hexamethylcyclotrisiloxane or octamethylcyclotetrasiloxane after anionic polymerization of styrene, but have the drawbacks of requiring special reaction equipment and requiring a long reaction time. In addition, since it is difficult to maintain appropriate reaction conditions, it is difficult to adjust the molecular weight of each of the polystyrene unit and polysiloxane unit, and to adjust the molecular weight of the final product. And it is also difficult to blend this type of copolymer with other resins. A block copolymer of this type is also described in a paper by A. Skoulios (Macromolec
ules, vol. 4, p. 268 (1971)), condensation reaction between polystyrene modified with silanol at both ends and polysiloxane having chlorinated functional groups at both ends. However, this method produces a different number of block portions, it is difficult to adjust the molecular weight of each of the polystyrene unit and polysiloxane unit, and the molecular weight of the final product. It is difficult to obtain a product of the desired composition, and it is also difficult to blend this type of copolymer with other resins.

A graft copolymer of a styrene monomer onto a polysiloxane chain has the potential to be a material having good mold release, abrasion resistance and lubricity during molding. In the conventional method of synthesis, P. Baja j, D.
Paper by C. Gupta and K. Varshung (Polymer Enginee
ring and Science, vol. 23, p. 825 (1983)) and J.
A paper by A. Barrie and K. Munday (Journal of Membr
ance Science, vol. 13, p. 175 (1983)), styrene is converted from vinyl groups of a polydimethylsiloxane-polymethylvinylsiloxane block copolymer or a methylvinylsiloxane-dimethylsiloxane copolymer. Is obtained by graft copolymerization, which is polymerized by irradiation of radicals or ⁶⁰ Co. However, it is also difficult to maintain appropriate reaction conditions due to the cross-linking reaction, so the molecular weight of polystyrene units and polysiloxane units must be adjusted. , It is difficult to adjust the molecular weight of the final product, it is difficult to obtain a product of the desired composition,
Because the obtained graft copolymer has a molecular structure in which styrene is graft-polymerized to a polysiloxane chain, when blended with a styrene-based resin having no other polysiloxane chain in a constituent unit, a problem occurs in compatibility, There are inconveniences such as a reduction in impact strength, and the effects expected for mold release, abrasion resistance, lubricity, impact resistance, etc. at the time of resin molding of the final product have not been obtained.

The inventors of the present invention have focused on the problems of the surface characteristics and impact strength of the polystyrene resin as described above, and as a result of intensive studies on the modification of the polystyrene resin, the present invention has been achieved.

That is, an object of the present invention is to solve the above-mentioned problems, and to improve the releasability during molding, abrasion resistance, and a polystyrene-based resin having improved lubricity and a polystyrene resin modifier composition for providing the same. To provide.

[Means for Solving the Problems] The present invention relates to a polystyrene-based elastomer modified with maleic anhydride (hereinafter abbreviated as a modified polystyrene-based elastomer) and a polysiloxane having a reactive group thereto, made of polystyrene or polystyrene. In the presence of a styrene copolymer and a rubber softener, a method of producing a modifier composition for a polystyrene resin by reacting by melt-kneading, and the modifier composition and a polystyrene resin This is a method of producing a polystyrene resin by mixing.

The modified polystyrene-based elastomer in the method for producing a modifier composition for a polystyrene-based resin of the present invention (hereinafter, referred to as a modifier production method) is a polystyrene-based elastomer modified with maleic anhydride. More specifically, a polystyrene elastomer modified with maleic anhydride is selectively hydrogenated in a polybutadiene segment of a styrene-butadiene block copolymer (provided that the number of polystyrene segments and polybutadiene segments is at least one each). Graft-modified with maleic anhydride.

The styrene-butadiene block copolymer in the modifier production method of the present invention has a polystyrene segment of about
Preferably, it is comprised in the range of 15 to about 60% by weight, more preferably in the range of about 20 to about 50% by weight. When the proportion of the polystyrene segment is less than about 15% by weight, the compatibility between the reaction product of the modified polystyrene-based elastomer and the polysiloxane having a reactive group with the polystyrene or styrene-based copolymer resin is reduced. If the reaction exceeds about 60% by weight, the melting temperature rises when the modified polystyrene-based elastomer and the polysiloxane having a reactive group are reacted with the modified polystyrene-based elastomer and the polysiloxane having a reactive group. When the inventive modifier composition is added, it tends to have an unfavorable effect on moldability, such as a decrease in dispersibility, and on the final product.

As described above, the modified polystyrene-based elastomer in the modifier production method of the present invention is obtained by selectively hydrogenating a polybutadiene segment of a styrene-butadiene block copolymer and graft-modified with maleic anhydride. Among them, the polybutadiene segment preferably has a residual unsaturated bond ratio of not more than about 20% without hydrogenation, more preferably about 10% or less.
%, Most preferably about 5% or less. If the degree of unsaturation exceeds about 20%, heat resistance, heat aging resistance, and weather resistance decrease, which is not preferable. Also, the polystyrene segment
When about 10% or more is hydrogenated, the mechanical strength and impact resistance of the composition to which the modifier composition of the present invention is added tend to decrease.

The content of maleic anhydride in the modified polystyrene-based elastomer of the modifier manufacturing method of the present invention is in a range of about 0.02 to about 20% by weight, a preferred range is about 0.1 to about 10% by weight, and a particularly preferred range is about 0.2%. ~ 5% by weight. When the content of maleic anhydride is less than about 0.02%, it becomes difficult to react the maleic anhydride units of the modified polystyrene-based elastomer with the reactive polysiloxane. If the content exceeds about 20% by weight, unreacted acid anhydride groups inhibit the modifying function of the polysiloxane chain, and the surface of the molded product to which the modifier composition of the present invention is added has lubricity such as lubricity. The moldability may be reduced, and the mold release property, abrasion resistance, and lubricity during molding may be adversely affected.

Specific examples of the styrene-butadiene block copolymer used in the production of the modified polystyrene-based elastomer used in the production method of the modifier production method of the present invention are described in U.S. Pat.Nos. 4,219,627, 3,251,905 and 3,251,905. No. 3390207 and Japanese Patent Publication No. 45-29669. These publications disclose block copolymers composed of polystyrene segments and polybutadiene segments obtained by successive addition of monomers, increased addition of monomers, or coupling reactions.

Also, JP-B-58-10413, JP-B-53-15958, JP-B-41-8782, JP-A-53-94584,
U.S. Pat.Nos. 3,251,905 and 3,693,521 disclose a multi-part containing a tapered copolymer block produced by copolymerizing a mixture of butadiene and styrene by utilizing the difference in the reaction rate of copolymerization. A block copolymer is shown.

A method for hydrogenating a styrene-butadiene block copolymer is disclosed in U.S. Pat.
-37294. That is, a styrene-butadiene block copolymer or a multi-block copolymer obtained by the above method is dissolved in an inert hydrogen diluent such as cyclohexane, and hydrogenation is performed in the presence of a soluble hydrogenation catalyst. The method of graft modification is a known method, that is,
-76518, JP-A-62-250018, JP-A-62-7
It can be obtained, for example, by grafting by melt-kneading maleic anhydride and the above-mentioned hydrogenated block copolymer or multi-block polymer in the presence of a radical generator described in JP-A-9211.

When the reactive polysiloxane having an amino group-containing substituent in the method for producing a modifier of the present invention has an amino group-containing substituent at one end, the weight average molecular weight is preferably about 500 to about 100,000, and particularly preferably about 500 to about 100,000 in weight average molecular weight. 1,000 to about 50,000 is preferred. When the amino group-containing substituent is present at both terminals, the weight average molecular weight is preferably about 20,000 to about 100,000, and more preferably about 30,000 to about 70,000. In the case of a polysiloxane having an amino group-containing substituent at both ends, when the weight average molecular weight is about 20,000 or less, a significant tertiary tertiary reaction occurs with a polystyrene copolymer containing about 0.02 to about 20% by weight of maleic anhydride units. This may cause undesired effects on the moldability and the final product, such as a rise in melting temperature, an increase in the melting temperature or a decrease in the dispersibility. In the case of a polysiloxane having an amino group-containing substituent at both ends or one end, the weight average molecular weight is about
If it exceeds 100,000, the reactivity with the styrene-based thermoplastic elastomer modified with maleic anhydride may be reduced.

The weight average molecular weight can be measured by gel permeation chromatography.

The reactive polysiloxane is not particularly limited as long as it has an amino group-containing substituent at one end or at both ends, but from the viewpoint of the degree of polymerization and the ease of controlling the molecular weight distribution, living polymerized polysiloxane is preferred. Those having a siloxane skeleton are particularly preferred. Such a reactive polysiloxane is prepared by, for example, using trimethylsilanol or a silanol dimethylsiloxane oligomer at both terminals as an initiator, subjecting hexamethylcyclotrisiloxane to living polymerization in the presence of a lithium catalyst, and then reacting with dimethylchlorosilane at one end or One end or both ends are amino groups by introducing Si-H bonds at both ends and further utilizing a hydrosilylation reaction.

In the method for producing a modifier of the present invention, a polystyrene or styrene copolymer is further used. The polystyrene or styrene copolymer is a polymer of a monomer containing styrene, and has a tensile elongation at break of less than 50% as measured according to ASTM-D638. Examples of these include a rubber-modified polystyrene resin (impact-resistant polystyrene) obtained by graft copolymerizing styrene in the presence of a rubber-like elastomer, in addition to a homopolystyrene resin. Specifically, acrylonitrile-styrene copolymer, acrylonitrile-butadiene-styrene copolymer (ABS resin) and the like can be exemplified. Basically, it is a polymer containing styrene as a polymerization unit and has rubber elasticity. Those which are not shown and which have a small content of highly polar and highly reactive groups such as an acid anhydride group such as a maleic anhydride group or a carboxyl group in a polymerized unit are preferred. In addition, there is no problem even if two or more styrene-based polymers are mixed and used.

Further, the rubber softener in the modifier manufacturing method of the present invention,
Non-aromatic mineral oils or polybutenes are preferred. A non-aromatic mineral oil is generally defined as a paraffinic mineral oil or naphthene ring having a carbon number of about 30% or more in the process oil or extender oil, wherein the carbon number of the paraffin chain accounts for about 50% or more of the total carbon. ~ About 45% naphthenic mineral oil.

The method for producing a modifier of the present invention is characterized in that a modified polystyrene-based elastomer is reacted with a polysiloxane having a reactive group at a terminal by melt-kneading. Melt kneading applies a strong shearing force to molten raw material resins and additives such as single-screw extruders, twin-screw extruders, kneaders, roll mixers, and intensive mixers used in the field of general synthetic resins. The agglomeration can be performed by a device capable of crushing and uniformly dispersing the aggregate.

In this reaction, the addition ratio of the reactive polysiloxane to the modifier composition for polystyrene resin is about 5 to about 50.
5% to about 30% by weight of a styrene elastomer modified with maleic anhydride, about 20% to about 85% by weight of a polystyrene or styrene copolymer, and about 5% by weight of a rubber softener. Preferably, it is about 30% by weight. If the amount of the reactive polysiloxane added to the polystyrene-based resin modifier composition is less than about 5% by weight, when the modifier composition is added to the polystyrene-based resin, the final product has sufficient surface lubricity and resistance to resistance. In order to impart abrasion, it is necessary to add a large amount of the modifier composition, which is not preferable,
If the amount of the reactive polysiloxane exceeds about 50% by weight, the reaction in the melt kneader becomes difficult. Further, the addition ratio of the modified polystyrene-based elastomer to the modifier composition for polystyrene-based resin is preferably about 5 to about 30% by weight, and when it is about 30% by weight or more, the modified polystyrene-based elastomer undergoes a crosslinking reaction or the like. If the content is less than about 5% by weight, it is difficult to sufficiently react with the reactive polysiloxane.

The addition ratio of the polystyrene or styrene copolymer resin used in the modifier production method of the present invention to the polystyrene resin modifier composition is about 20 to about 85% by weight, preferably about 30 to about 80% by weight. %. The addition ratio is about
When the content is 20% by weight or less, the properties of the extruded strand during extrusion kneading become extremely poor, and granulation becomes difficult.

The amount of the rubber softener used in the method for producing a modifier of the present invention is preferably about 5 to about 30% by weight based on the modifier composition for a polystyrene resin. The rubber softener has a function of adjusting the shape of the strand and the pellet. It prevents the strands from becoming fibrous or spongy, easily tearing or breaking vertically, and making granulation difficult.

The method for producing a modifier of the present invention is characterized in that the reaction is carried out by melt kneading. At this time, the kneading temperature is about 250 ° C. or less, preferably about 150 to about 230 ° C. If the temperature is higher than about 250 ° C., the stability of the modified polystyrene resin may be impaired. If the temperature is lower than about 150 ° C., the polystyrene resin is not sufficiently melted, which is not preferable.

In addition, various additives such as a heat stabilizer, an ultraviolet absorber, a lubricant, a coloring agent or an antistatic agent, or various fillers such as talc and glass fiber can be arbitrarily added at the time of compounding.

Examples of the polystyrene resin used in the method for producing a polystyrene resin composition of the present invention include a homopolystyrene resin and a rubber-modified polystyrene resin obtained by graft copolymerizing styrene in the presence of a rubbery elastomer ( Impact-resistant polystyrene), acrylonitrile-styrene copolymer, acrylonitrile-butadiene-styrene copolymer, acrylonitrile-styrene-
Acrylic rubber copolymer, acrylonitrile-styrene-
EPDM (ethylene-propylene-diene terpolymer) copolymer, acrylonitrile-chlorinated polyethylene-styrene copolymer, methyl methacrylate-butadiene-styrene copolymer, styrene-butadiene-ethylene-styrene block copolymer and the like are exemplified. Can be
Basically, any polymer may be used as long as it is a polymer containing styrene as a polymerized unit, and there is no particular restriction.However, the polymerized unit has a strong polarity such as an acid anhydride group such as a maleic anhydride group or a carboxyl group, and has a strong Those having a small content of a group having high reactivity are preferable. Also, a mixture of two or more styrene-based polymers may be used.

The method for producing a polystyrene resin composition of the present invention is characterized in that a modifier and a polystyrene resin are mixed by melt-kneading. Melt kneading applies a strong shear force to molten raw material resins and additives, such as single-screw extruders, twin-screw extruders, kneaders, roll mixers, and intensive mixers, which are used in the field of general synthetic resins to form agglomerates. This can be done with a device that can be ground and evenly dispersed.

In addition, various additives such as a heat stabilizer, an ultraviolet absorber, a lubricant, a coloring agent, an antistatic agent, and various fillers such as talc and glass fiber can be optionally added at the time of compounding. Hereinafter, the present invention will be described with reference to examples.

Example 1 Specific gravity 0.91 g / cc, styrene content 28% by weight, maleic anhydride content 2% by weight, solution viscosity at 25 ° C. 6,000 cps
(Solution of 20% by weight of toluene) is subjected to block copolymerization like a styrene segment-butadiene segment-styrene segment to form 20 parts by weight of a modified polystyrene-based elastomer in which a butadiene segment is selectively hydrogenated to form a naphthene ring. 29.0% of hydrocarbons, 71.0% of hydrocarbons forming paraffin chains, average molecular weight
539, kinematic viscosity at 40 ° C. 95.54 cst, kinematic viscosity at 100 ° C. 11.25 cst paraffinic mineral oil 10 parts by weight, ASTM-D1
Melt flow index measured according to 238 (200 ° C,
5,000g) is 14g / 10min impact polystyrene resin 50
Parts by weight, 20 parts by weight of polydimethylsiloxane having an amino group at one end represented by the following formula having a weight average molecular weight of 5,000 as measured by gel permeation chromatography, and then setting the cylinder temperature to 200 to 220 ° C. The mixture was kneaded and extruded with an extruder to obtain a modifier composition for polystyrene resin. This modifier composition for polystyrene resins is referred to as "Modifier-1".

Example 2 20 parts by weight of the same modified polystyrene elastomer as in Example 1, 10 parts by weight of the same rubber softener as in Example 1, Example 1
50 parts by weight of the same impact-resistant polystyrene resin as the weight-average molecular weight measured by gel permeation chromatography
60,000, 20 parts by weight of polydimethylsiloxane having amino groups at both ends represented by the following formula were mixed, and then kneaded and extruded with an extruder having a cylinder temperature of 200 to 220 ° C., and a modifier composition for polystyrene resin was used. I got something. This modifier composition for polystyrene resins is referred to as "Modifier-2".

Comparative Example 1 Impact-resistant polystyrene having a melt flow index (200 ° C., 5,000 g) of 3.5 g / 10 minutes measured according to ASTM-D1238 was injection molded into a 25 cm square plate.
The releasability at the time of molding was poor, and the slidability was confirmed by rubbing with a flannel. The slidability was clearly insufficient.

Example 3 85% by weight of the same impact-resistant polystyrene as Comparative Example 1
"Modifier-1" was mixed at a composition ratio of 15% by weight, and then kneaded and extruded with an extruder having a cylinder temperature of 200 to 220 ° C. to carry out granulation to obtain a modified impact-resistant polystyrene resin composition. I got

As a result of injection molding this composition into a 25 cm square plate, the releasability at the time of molding was very good, and the sliding property was confirmed by rubbing with a flannel. Compared to the high-impact polystyrene not added, by adding the modifier composition of the present invention, a modified high-impact polystyrene resin composition having excellent slidability was obtained. found.

Example 4 85% by weight of the same impact-resistant polystyrene as in Comparative Example 1,
"Modifier-2" was mixed at a composition ratio of 15% by weight, and then kneaded and extruded with an extruder having a cylinder temperature of 200 to 220 ° C to perform granulation, and the modified impact-resistant polystyrene resin composition was used. I got

As a result of injection molding this composition into a 25 cm square plate, the releasability at the time of molding was very good, and the sliding property was confirmed by rubbing with a flannel. Compared to the high-impact polystyrene not added, by adding the modifier composition of the present invention, a modified high-impact polystyrene resin composition having excellent slidability was obtained. found.

[Effect of the Invention] The impact resistance is enhanced by incorporating the modifier composition for polystyrene-based resin of the present invention into a conventional polystyrene-based resin, and the mold releasability, abrasion resistance, lubricity and molding during molding are improved. It has become possible to improve and improve the slidability such as lubricity of the object surface. This is because the modifier composition for polystyrene-based resin of the present invention is an excellent elastic body and further has excellent compatibility with polystyrene-based resin.

The modifier composition for polystyrene resin of the present invention is easier to control its structure, particularly the structure of the polysiloxane portion, than the modification method according to the prior art. It is possible to optimize the ratio of the system elastomer part and the polysiloxane part, and it is possible to flexibly cope with the demanded variety coming from a wide range of uses of the polystyrene resin.

Polystyrene resins are inexpensive, hard, water-resistant, have excellent high-frequency electrical insulation, are not attacked by acids or alkalis, and are easy to injection mold.
The modified polystyrene-based resin of the present invention can flexibly cope with a variety of requirements even when modifying or improving a conventional polystyrene resin.

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Claims (11)

(57) [Claims] A polystyrene elastomer modified with maleic anhydride and a polysiloxane having a reactive group are melt-kneaded in the presence of a polystyrene or styrene copolymer and a rubber softener. A method for producing a modifier composition for a polystyrene-based resin, characterized by reacting. However, in the polystyrene-based elastomer modified with maleic anhydride, the polybutadiene segment of a styrene-butadiene block copolymer (here, the polystyrene segment and the polybutadiene segment are each one or more) is selectively hydrogenated. , Graft-modified with maleic anhydride. 2. The polystyrene-based elastomer modified with maleic anhydride has a maleic anhydride unit of 0.02
The method for producing a modifier composition for a polystyrene-based resin according to claim 1, wherein the composition is not less than 20% by weight and not more than 20% by weight. 3. The styrene-butadiene block copolymer in the polystyrene elastomer modified with maleic anhydride is a styrene-butadiene block copolymer containing 15 to 60% by weight of a polystyrene segment. The method for producing a modifier composition for a polystyrene-based resin according to the above. 4. The polysiloxane having a group reactive with a polystyrene elastomer modified with maleic anhydride is a polysiloxane having an amino group at one end and having a weight average molecular weight of 500 to 100,000. (1)
The method for producing a modifier composition for a polystyrene-based resin according to any one of (1) to (3). 5. The polysiloxane having a group reactive with a polystyrene elastomer modified with maleic anhydride is a polysiloxane having amino groups at both ends and having a weight average molecular weight of 20,000 to 100,000. The method for producing a modifier composition for a polystyrene resin according to any one of (1) to (3). 6. The method according to claim 1, wherein the rubber softener is a non-aromatic mineral oil or polybutene. 7. Kneading a polystyrene elastomer modified with maleic anhydride and a polysiloxane having a reactive group thereto in the presence of a polystyrene or styrene copolymer resin and a rubber softener. The ratio of the polystyrene-based elastomer modified with maleic anhydride in the modifier composition for a polystyrene-based resin is 5 to 30% by weight when the reaction is carried out. A method for producing a modifier composition for a polystyrene resin. 8. A polystyrene elastomer modified with maleic anhydride and a polysiloxane having a reactive group thereto are melt-kneaded in the presence of a polystyrene or styrene copolymer resin and a rubber softener. In the reaction, the ratio of the reactive polysiloxane in the modifier composition for polystyrene resin is 5 to 50.
The method for producing a modifier composition for a polystyrene resin according to any one of claims (1) to (7), in which the amount is% by weight. 9. A polystyrene elastomer modified with maleic anhydride and a polysiloxane having a reactive group thereto are melt-kneaded in the presence of a polystyrene or styrene copolymer resin and a rubber softener. The polystyrene according to any one of claims 1 to 8, wherein the ratio of the polystyrene or styrene-based copolymer resin in the polystyrene-based resin modifier composition is 20 to 85% by weight. Method for producing a modifier composition for a base resin. 10. A polystyrene elastomer modified with maleic anhydride and a polysiloxane having a reactive group thereto are melt-kneaded in the presence of a polystyrene or styrene copolymer resin and a rubber softener. When the reaction is carried out, the proportion of the rubber softener in the modifier composition for polystyrene resin is 5 to 30% by weight.
The method for producing a modifier composition for a polystyrene-based resin according to any one of claims (1) to (9). 11. A polystyrene resin, which comprises mixing the polystyrene resin modifier composition obtained by the method according to any one of claims (1) to (10) with a polystyrene resin. A method for producing the composition.