JPH02117922A - Production of respective modified polystyrene-based resin and composition thereof - Google Patents

Abstract

PURPOSE:To improve and modify mold releasability, abrasion resistance, lubricity, etc., in molding while holding essential mechanical strength by reacting a styrene-based copolymer having a specific molecular composition with a reactive polysiloxane. CONSTITUTION:(A) A styrene-based copolymer containing maleic anhydride units is reacted with (B) a reactive polysiloxane having amino group at one terminal to afford a modified polystyrene-based resin. Further, the component (A) is preferably a copolymer with 0.01-20wt.% maleic anhydride unit content and a polysiloxane having <=100000 weight-average molecular weight is preferably used as the component (B). The ratio of the components (B) to (A) is preferably 0.05-70% wt.%. Furthermore, the components (A) and (B) are preferably reacted in the presence of a styrene-based polymer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a polystyrene resin modified by grafting polysiloxane and a composition thereof.

[Conventional technology]

Polystyrene resin is hard, has excellent high-frequency electrical insulation, is resistant to acids and alkalis, and does not soften at around 90°C.
Since it becomes a viscous liquid at about 30°C, injection molding is easy. On the other hand, since the surface of the molded product has insufficient sliding properties such as lubricity, there are problems with mold releasability, wear resistance, and lubricity during molding.

Conventionally, the above-mentioned drawbacks of polystyrene resins have been improved by the following methods.

1) Spraying 1 ton of silicone oil such as polydimethylsiloxane onto the mold during molding 2) Blending silicone oil such as polydimethylsiloxane 3) Blending styrene with an olefin compound having polydimethylsiloxane chains Copolymerization 4) Blend of a copolymer of styrene and an olefin compound having a polydimethylsiloxane chain with another styrenic resin that does not have a polysiloxane chain as a constituent unit 5) Block copolymerization having a polystyrene unit and a polysiloxane unit 6) Ho! j Blending of a block copolymer having a styrene unit and a polysiloxane unit with a styrenic resin having no other polysiloxane chain as a constituent unit 7) Graft copolymerization of a styrene monomer to a polysiloxane chain 8) Graft copolymerization to a polysiloxane chain A blend of a copolymer grafted with a styrene monomer and a styrenic resin that does not have other polysiloxane chains as a constituent unit [Problem to be solved by the invention] Method of spraying silicone oil onto a mold among conventional techniques In addition to the fact that the oil sprayed as a mold release agent remains on the surface of the product, it is also necessary to frequently spray the mold release agent on the molding die, which is inefficient. Not useful for improvement.

Polystyrene-based resins that have been improved by blending silicone oil tend to separate or bleed out during molding or kneading because silicone generally has poor compatibility with the resin, or they do not mix uniformly or have a poor appearance. Problems such as significant damage, easy formation of flakes, deterioration of physical properties, etc. occur.

A copolymer of styrene and an olefin compound having a polydimethylsiloxane chain is Yuh 5uke K;
Kam i, R, A, N, Murtori and Yuy
A paper by Yamashita (Die Makr
Omolekulare Chemie Volume 185, 9
Although it is possible to synthesize by radical or anionic copolymerization, such as the method described in Page (1984), the degree of polymerization and yield are insufficient with the current method, and furthermore, homopolystyrene is insufficient. A large amount of by-products,
This is difficult to remove and difficult to produce industrially. Therefore, it is also difficult to blend this type of copolymer with other resins.

A method for synthesizing a block copolymer having polystyrene units and polysiloxane units is J, C, 5aa
n 1D, J, Gardon and S, Lind
A paper by Say (Macromo1ecules No. 3)
Volume 1, page 1 (1970)), paper by A. Marsiat and V. Gallot (Die Makrom
olekulare Chemie Volume 176 1641
Page (1975”), J.G., Zillox,
J, E, L, Roovers and S, Bywa
Paper by Ter (Macromolecules No. 8)
A basic monofunctional initiator such as butyl lithium as described in Vol.
Paper by S. Brown, K. U. Fulcher and R. E. Wetton (Journa
l of Polymer 5science Poly
merLetter Edition Vol. 8, p. 659 (1970)), an article by J.W. Dean (
Journal of Polymer Science
Polymer Letter Edition Vol. 8, p. 677 (1970)), D, J, Leg
rant (Journal of Poly
mer 5science volume 8 page 195 (1970
)), paper by H, G, Kim (Macromo1e
cules Vol. 5, p. 594 (1972)), C, P
r1ce % A, G, Warson and M, T,
Paper by Chov (Polymer Vol. 13, 333)
Page (1972)), an article by F. R. Jones (European Polymer Journal
10, p. 249 (1974), etc., using difunctional initiators such as sodium naphthalene and lithium naphthalene, P. Bajaj.
%S, in the paper by Varshney and A. Misra (Journal of Polymer 5
science PolymerChemistry E
It can be obtained by the method of anionically polymerizing styrene using lithium biphenyl as an initiator as described in J.D. Ddition, Vol. 18, p. 295 (1980), and then polymerizing hexamethylcyclotrisiloxane or octamethylcyclotetrasiloxane. In addition to requiring special reaction equipment, it also has drawbacks such as long reaction times.Furthermore, it is difficult to maintain appropriate reaction conditions, making it difficult to adjust the molecular weight of each polystyrene unit and polysiloxane unit, and to improve the quality of the final product. It is difficult to control the molecular weight, the types of polymers that can be synthesized are limited, and it is difficult to obtain products with the desired composition. Therefore, it is also difficult to blend this type of copolymer with other resins. In addition, this type of block copolymer has been described in a paper by A.
It can also be obtained by a condensation reaction between polystyrene modified with silanol at both ends and polysiloxane having a chlorinated functional group at both ends, as described in Vol. 4, p. 268 (1971). However, this method produces different numbers of block parts, it is difficult to adjust the molecular weight of each polystyrene unit and polysiloxane unit, and it is difficult to adjust the molecular weight of the final product.The types of polymers that can be synthesized are limited, and it is difficult to achieve the desired composition. It is difficult to obtain the product and therefore it is also difficult to blend this copolymer of I1 with other resins.

A graft copolymer of styrene monomer to a polysiloxane chain has the potential to become a material with good mold releasability, wear resistance, and lubricity during molding. Traditional methods of synthesizing P, Baja
j, II C, Gupta and K.

A paper by varshung (Polymer Eng.
ineringand 5science volume 23 82
5 pages (1983)) and the article by J. A. Barry and Munday (Journal of
As described in Membrance 5science Vol. 13, p. 175 (1983), styrene is removed from the vinyl group of polydimethylsiloxane-polymethyl and nylsiloxane block copolymer or methylvinylsiloxane-dimethylsiloxane copolymer by radical or ll0co. It is obtained by graft copolymerization, which is polymerized by irradiation, but this also involves a crosslinking reaction, and it is difficult to maintain appropriate reaction conditions, so it is necessary to adjust the molecular weight of each polystyrene unit and polysiloxane unit, and the molecular weight of the final product. It is difficult to obtain a product with the desired composition, and because the resulting graft copolymer has a molecular structure in which styrene is grafted onto a polysiloxane chain, it is difficult to obtain a product with the desired composition. There are disadvantages such as problems with compatibility when blended with styrenic resins that do not have the same properties, and the expected effects on mold release, wear resistance, lubricity, etc. when molding the final product resin are not achieved.

[Means to solve the problem]

A graft copolymer of polysiloxane to a polystyrene chain is obtained by graft copolymerizing a polysiloxane chain to a polystyrene resin by chemical treatment, etc.
Although this can be expected, there have been no reports of this type of graft copolymer being obtained. However, when this type of graft copolymer is blended with a styrenic resin that does not have other polysiloxane chains as a constituent unit, it has good compatibility, and it is possible to selectively modify only the surface of the resin, especially by adding a small amount. You can expect it.

Therefore, if it is possible to bond a polystyrene resin with a specific molecular weight and composition to a polysiloxane with a specific molecular weight and composition without breaking each molecular chain, it will improve mold release properties, wear resistance, and lubricity during molding. It should be possible to produce an excellent polystyrene resin that does not require a mold release agent during molding, has excellent surface lubricity, and has improved wear resistance.

The present inventors focused on the above-mentioned problems with the surface properties of polystyrene resins, and as a result of intensive research into the modification of polystyrene resins, they arrived at the present invention. That is, the present invention provides (1) a modified polystyrene resin characterized by reacting a reactive polysiloxane having an amino group at one end with a styrene copolymer containing maleic anhydride units; Production method.

(2) The first method, wherein the styrenic copolymer containing maleic anhydride units is a styrenic copolymer having a maleic anhydride unit content o of 01 to 20 by weight.
A method for producing a modified polystyrene resin as described in .

(3) The modified polystyrene resin according to item 1 or 2, wherein the reactive polysiloxane having an amino group at one end is a reactive polysiloxane having a weight average molecular weight of 100,000 or less. Production method.

(4) When reacting a reactive polysiloxane having an amino group at one end with a styrene copolymer containing maleic anhydride units, a styrene copolymer containing maleic anhydride units of the reactive polysiloxane is used. 4. The method for producing a modified polystyrene resin according to any one of items 1 to 3, characterized in that the proportion to the copolymer is 0.05 to 70% by weight.

(5) A method for producing a modified polystyrene resin composition, which comprises mixing the modified polystyrene resin according to any one of items 1 to 4 with a styrene polymer.

(6) A modified polystyrene resin composition characterized in that a styrene copolymer containing maleic anhydride units is blended with a styrene polymer and then reacted with a reactive polysiloxane having an amino group at one end. How things are manufactured.

(The modification according to item 6, wherein the styrenic copolymer containing maleic anhydride units is a styrenic copolymer having a maleic anhydride unit content of 0.01 to 20% by weight. A method for producing a polymethylene-based resin composition.

(8) The modified polystyrene resin composition according to item 6 or 7, wherein the reactive polysiloxane having an amino group at one end is a reactive polysiloxane having a weight average molecular weight of 100,000 or less. How things are manufactured.

(9) Items 5 to 8, wherein the styrenic polymer is one type of polymer or a mixture of two or more types of polymers selected from the group consisting of styrene polymers and styrene copolymers. A method for producing a modified polystyrene resin composition according to any one of the above.

It is.

It has been pointed out for some time that polystyrene-based resins made by graft copolymerizing polystyrene with polysiloxane may be effective in improving surface wear resistance and lubricity, as well as improving mold release properties during molding. . Nevertheless, these polystyrene resins have problems in the production of modifiers for polystyrene resins and in the modification of resins, and a technical method based on a unified principle has not yet been established. In particular, polystyrene resin has poor reactivity, and it has been extremely difficult to carry out graft copolymerization. An advantage of the present invention is that a modified polystyrene with a clearly controlled structure is obtained by reacting a reactive polysiloxane having an amino group at one end with a styrenic copolymer containing maleic anhydride units. This resin solves these unresolved problems all at once, improving the mold release properties, abrasion resistance, and
The point is that it has made it possible to improve and modify lubricity.

Polystyrene resin is inexpensive, hard, water resistant, has excellent high-frequency electrical insulation properties, is not attacked by acids or alkalis, and is easy to injection mold, so its uses are very wide. When carrying out modifications and improvements, it is necessary to be able to respond flexibly to the diversity of requirements.

The modified polystyrene resin of the present invention is obtained by reacting a styrene copolymer containing maleic anhydride units with a reactive polysiloxane having an amino group at one end. The molecular composition, molecular weight, molecular structure, etc. of both the polystyrene copolymer containing maleic anhydride units and the reactive polysiloxane having an amino group at one end, which are the raw materials, can be changed at any time depending on the purpose. Therefore, the modified polystyrene resin of the present invention has excellent diversity, flexibility, and ease in designing the molecular composition, molecular weight, and molecular structure according to requirements.

The styrenic copolymer containing maleic anhydride units in the present invention is preferably a polystyrene copolymer containing 0.01 to 20 maleic anhydride units by weight, and the maleic anhydride unit content is particularly high. The preferred range is 0.05 to 15% by weight. If the anhydride is less than -7'v, it will be difficult to react the maleic anhydride units with the reactive polysiloxane having an amino group at one end, and it will be difficult to form a graft copolymer. 20 weight again! If the amount exceeds t%, unreacted acid anhydride groups will remove the modifying function of the polysiloxane chain, reducing the sliding properties such as the lubricity of the surface of the molded product, and reducing the mold releasability, abrasion resistance, and This may adversely affect lubricity.

The styrenic copolymer can also be prepared by adding, for example, a mixture of styrene monomer and maleic anhydride monomer, a radical generator and a chain transfer agent in an appropriate molar ratio to a ketone solvent such as acetone or methyl imbutyl ketone. It can be obtained by thermally polymerizing the product at a temperature of 75 to 140°C, and then precipitating the resulting polymer using a poor solvent such as petroleum benzine or methanol. There is no problem in copolymerizing with other monomers such as acrylonitrile, butadiene, methyl methacrylate, acrylamide, maleimide, maleic acid dialkyl ester, etc. Also, various additives such as heat stabilizers, ultraviolet absorbers, etc. , lubricants, colorants or antistatic agents, or various fillers such as talc, glass fibers, etc. may be mixed. Therefore, commercially available maleic anhydride-containing polystyrene resins can also be used without any problems.

The reactive polysiloxane having an amino group at one end in the present invention has an amino group-containing substituent only at one end,
Weight average molecular weight is 100,000 or less, preferably 500
00 or less is better. It is desirable that the lower limit of the weight average molecular weight of the polysiloxane is 1,000. When the weight average molecular weight is 100,000 or more, the maleic anhydride unit is reduced to 0.
There is a possibility that the reactivity with the polystyrene copolymer containing 01 to 20% by weight fk may decrease.

However, when a reactive polysiloxane having amino groups at both ends is used, significant three-dimensionalization occurs in the reaction with a polystyrene copolymer containing 0.01 to 20 maleic anhydride units by weight. This has unfavorable effects on moldability and final appearance, such as an increase in melting temperature or a decrease in dispersibility.

The above weight average molecular weight is based on Gertsuk-meation chroma,
It can be measured with a spike. The reactive polysiloxane may be manufactured by any particular method as long as it has an amino group-containing substituent at one end, but from the viewpoint of ease of controlling the degree of polymerization and molecular weight distribution, it is preferable to use a living polymerized polysiloxane as the backbone. is particularly preferred. Such reactive polysiloxane can be produced by living polymerizing hexamethylcyclotrisiloxane in the presence of a lithium catalyst using, for example, trimethylsilanol or a double-terminated silanol dimethylsiloxane oligomer as an initiator, and then reacting it with dimethylchlorosilane to form one-terminated KSi- Introducing H-bonds,
Furthermore, by using a hydrosilylation reaction commonly used in silicon chemistry, one end can be made into an amino group-containing substituent. A styrenic copolymer containing maleic anhydride units of a reactive polysiloxane having 7 amino groups at one end is reacted with a styrenic copolymer containing maleic anhydride units. The addition ratio to the coalescence is preferably 0.05 to 70% by weight, particularly preferably 0.1 to 50% by weight. 0
．． If the weight ratio is less than 05, the surface lubricity and abrasion resistance of the final product will be insufficient, and if the weight ratio is more than 70, the graft copolymer will become grease-like, reducing compatibility, causing bleeding, and deteriorating physical properties. There is a risk of producing undesirable effects such as emitting light. The modified polystyrene resin of the present invention can be produced by any of various methods, such as known solution methods and melt methods.

When producing the modified polystyrene resin by a solution method, the above maleic anhydride-containing polystyrene resin and a reactive polysiloxane having an amino group at one end are stirred in a common solvent to remove the solvent. Just remove
Therefore, the target product can be obtained, and if necessary, the target product can be made into a fine powder, and various additives such as heat stabilizers, ultraviolet absorbers, lubricants, colorants or antistatic agents, or various fillers can be added. For example, talc, glass fibers, etc. can be added. Examples of solvents used in this case include linear or cyclic ethers such as diisopropyl ether, di-n-propyl ether, dioxane, and tetrahydrofuran; aliphatic or cyclic ethers such as acetone, methyl ethyl ketone, methyl isobutyl ketone, acetophenone, and cyclohexanone; Examples include aromatic ketones, esters such as ethyl acetate, isobutyl acetate, and isobutyl acetate, and aromatic hydrocarbons such as toluene and xylene. Even if the solvent is other than those exemplified here,
As long as there is no problem from an economic or health and safety standpoint, as long as the styrenic copolymer containing maleic anhydride units and the reactive polysiloxane having an amino group at one end are used as a common solvent, Any solvent can be used, and there is no problem in using it as a mixed solvent of two or more types.

Further, although room temperature is sufficient for the reaction temperature, there is no problem in raising the temperature to a temperature at which the solvent boils.

When producing the modified polystyrene resin of the present invention by the melting method, the above-mentioned styrene resin containing maleic anhydride units is produced using a melt kneader, such as an extruder, which is used in the field of general synthetic resins. It can be obtained by reacting a copolymer with a reactive polysiloxane having an amino group at one end while melt-kneading the copolymer. At this time, the kneading temperature is preferably above the melting point of the styrene copolymer containing maleic anhydride units to be used and below 250°C. If the temperature exceeds 250° C., the stability of the reactive polysiloxane, which is one of the raw materials, may be impaired, and the stability of the styrenic copolymer containing maleic anhydride units may also be impaired. In addition, this raw material various additives,
For example, heat stabilizers, UV absorbers, lubricants, colorants or antistatic agents can optionally be added, as well as various fillers such as talc, glass fibers, etc.

Next, the modified polystyrene resin composition of the present invention can be produced by either of the following two methods. The first method is to manufacture a modified polystyrene resin as a masterbatch using the method described above, and mix this with a styrenic polymer by a melting method under the same conditions as when manufacturing the modified polystyrene resin. Depending on the method, the above-mentioned additives may be added during formulation.

The second method is a method in which the production of a modified polystyrene resin and the blending with a styrenic polymer are carried out at the same time. The polysiloxane and the styrene polymer can be mixed, melted, and reacted, for example, by the same melting method as described above, or, although this is disadvantageous in terms of cost, in some cases, they can be dissolved in a common solvent and then heated to react. Thereafter, the modified polystyrene resin composition of the present invention can be obtained by removing the solvent, if necessary. As in the first method, it is possible to add less additives.

Examples of the styrenic polymer that is a constituent unit of the composition include polystyrene, high impact polystyrene, acrylonitrile-styrene copolymer, acrylonitrile-butadiene-styrene copolymer, and acrylonitrile-styrene-acrylic. Rubber copolymer, acrylonitrile-styrene-EPDM (
Examples include ethylene-propylene-genterpolymer) copolymer, acrylonitrile-chlorinated polyethylene-styrene copolymer, methyl methacrylate-butadiene-styrene copolymer, styrene-butadiene-ethylene-styrene block copolymer, etc. However, fundamentally, any polymer containing styrene as a polymerization unit may be used without any special restrictions, but if the polymerization unit has strong polarity such as an acid anhydride group such as a maleic anhydride group or a carboxyl group, Those with a low content of highly reactive groups are preferred.

Moreover, there is no problem in using a mixture of two or more types of styrene polymers.

〔Example〕

Next, the present invention will be specifically explained using Examples, but the present invention is not limited to these Examples.

Examples 1 to 3 Styrene-maleic anhydride copolymer (maleic anhydride content: 8% by weight, melt index measured according to ASTM-D 128-73: 2.2) and powdered polystyrene resin (according to JIS K 7210) A polysiloxane with a measured melt flow rate of 21.6) and a weight average molecular weight of 5000 as measured by a gel permeation chromatograph having the structural formula below were mixed in the composition ratio shown in Table IK, and then the cylinder temperature was adjusted to 200 to 200. Cross-line extrusion was carried out using an extruder set to 220°C. Table 1 shows the physical properties of the obtained composition.

CHs C) (s CHs l 1 1 CH, CHs CHs Example 4 67 parts by weight of the same styrene-maleic anhydride copolymer used in Examples 1 to 3 was dissolved in 700 parts by weight of tetrahydrofuran, and Example 1 33 parts by weight of the same polysiloxane as in 3 to 3 was added, stirred and reacted for 15 hours, then tetrahydrofuran was removed using a rotary evaporator, and the remaining solids were pulverized and further vacuum dried to obtain a grafted product.

9 parts by weight of this graft material and 91 parts by weight of the same polystyrene resin used in Examples 1 to 3 were mixed at a cylinder temperature of 2.
Cross-line extrusion was carried out using an extruder at a temperature of 00 to 220°C. Table 1 shows the physical properties of the obtained composition.

Example 5 Powdered styrene-maleic anhydride copolymer (maleic anhydride content is 1 F!, ASTM-D128-73
3 parts by weight of the same polysiloxane as used in Examples 1 to 3 was mixed with the mixture (having a melt index of 2.5) measured according to the above method, and then kneaded and extruded using an extruder with a cylinder temperature of 200 to 220°C. Table 1 shows the physical properties of the obtained polymer.

Comparative Example 1 The polystyrene resin used in Example 1 was used for comparison.

The test piece was molded using an injection molding machine with a cylinder temperature of 180 to 200°C. Table 1 shows the physical properties measured for this test piece.

Comparative Example 2 5 parts by weight of a reactive polysiloxane having the following structural formula containing amino groups at both ends and having a weight average molecular weight of 5000 and 10 parts by weight of the same styrene-maleic anhydride copolymer used in Examples 1 to 3. and 85 parts by weight of powdered polystyrene.
Cross-wire extrusion was attempted under the same conditions as in Examples 1 to 3, but the viscosity of the resin increased abnormally in the extruder cylinder in the middle of the reaction, making cross-wire extrusion impossible. The results are shown in Table-1.

CHs CHs CHs l　　　　　1　　　　　! The above physical properties were measured by the following method.

1. Tensile test: ASTM D6382, bending test:
ASTM D790 3, Dynamic friction coefficient: JIS K 7218A (Mating material: 5US304, speed: 4 cm/s, load: 2 kyf, holding time: 30 m) [Effects] ■ For the first time, the modified polystyrene resin of the present invention
While maintaining the original mechanical strength of polystyrene resin, improvements have been made in the sliding properties such as mold releasability, wear resistance, lubricity during molding, and lubricity on the surface of molded products.

■ By incorporating the modified polystyrene resin of the present invention, the styrenic polymer maintains the mechanical strength inherent to the polystyrene resin while maintaining mold releasability, wear resistance, lubricity, and lubricity on the surface of the molded product. It has become possible to improve and modify the sliding properties. This is because the modified polystyrene resin of the present invention has excellent compatibility with styrene polymers and has no decrease in mechanical strength.

■ The modified polystyrene resin of the present invention can easily control its structure, especially the structure of the polysiloxane part, compared to conventional modification methods, so depending on the purpose, the molecular weight of the polysiloxane part and the It is now possible to optimize the structure with respect to the ratio of the polysiloxane moiety, etc., and it has become possible to flexibly respond to the diversity of demands arising from the wide range of uses of styrenic polymers.

that's all

Claims (1)

[Scope of Claims] (1) A modified polystyrene resin characterized in that a reactive polysiloxane having an amino group at one end is reacted with a styrene copolymer containing maleic anhydride units. Production method. (2) The styrenic copolymer containing maleic anhydride units has a maleic anhydride unit content of 0.01 to 20% by weight.
2. The method for producing a modified polystyrene resin according to item 1, wherein the modified polystyrene resin is a styrene copolymer. (3) The modified polystyrene resin according to item 1 or 2, wherein the reactive polysiloxane having an amino group at one end is a reactive polysiloxane having a weight average molecular weight of 100,000 or less. Production method. (4) When reacting a reactive polysiloxane having an amino group at one end with a styrene copolymer containing maleic anhydride units, the styrene copolymer containing maleic anhydride units of the reactive polysiloxane is 4. The method for producing a modified polystyrene resin according to any one of items 1 to 3, characterized in that the proportion of the modified polystyrene resin to the polymer is 0.05 to 70% by weight. (5) A method for producing a modified polystyrene resin composition, which comprises mixing the modified polystyrene resin according to any one of items 1 to 4 with a styrene polymer. (6) A modified polystyrene resin composition characterized by reacting a styrene copolymer containing maleic anhydride units with a reactive polysiloxane having an amino group at one end in the presence of a styrene polymer. How things are manufactured. (7) The styrenic copolymer containing maleic anhydride units has a maleic anhydride unit content of 0.01 to 20% by weight.
7. The method for producing a modified polystyrene resin composition according to item 6, wherein the modified polystyrene resin composition is a styrene copolymer. (8) The modified polystyrene resin composition according to item 6 or 7, wherein the reactive polysiloxane having an amino group at one end is a reactive polysiloxane having a weight average molecular weight of 100,000 or less. How things are manufactured. (9) A fifth characterized in that the styrenic polymer is one type of polymer selected from the group consisting of styrene polymers and styrene copolymers or a mixture of two or more types of polymers.
9. A method for producing a modified polystyrene resin composition according to any one of items 8 to 8.