JPH03157444A - Styrene-based resin composition - Google Patents

Abstract

PURPOSE:To obtain a styrene-based resin composition having a high impact strength and excellent gloss and heat resistance and suitable for OA apparatuses, household appliances, etc., by using a rubber-modified styrene-based resin composition in which the dispersed rubber state has an occlusion structure. CONSTITUTION:A styrene-based resin composition obtained by blending (A) 95-55wt.%, preferably 90-60wt.% rubber-modified styrene-based resin composition in which the dispersed rubber state has an occlusion structure and <=45wt.%, especially <=40wt.% rubber-modified styrene-based resin composition having a salami structure may be contained with (B) 5-45wt.%, preferably 10-40wt.% copolymer composed of a styrene-based monomer and an unsaturated carboxylic acid anhydride and/or the aforementioned copolymer modified with rubber and (C) 0-30wt.%, preferably 0-25wt.% rubber-like polymer containing a styrene- based component. The contents of a styrene-based polymer and the rubber-like polymer in the component (A) are respectively preferably within the ranges of 72-90wt.% and 28-10wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a novel styrenic resin composition. More specifically, the present invention covers office automation equipment, home appliances,
The present invention relates to a styrene-based resin composition that is suitable as a material for automobile parts and has an excellent balance of physical properties, such as high impact strength, excellent gloss, and heat resistance. [Prior Art] Rubber-modified styrenic resin compositions have excellent impact resistance and rigidity, and have good moldability, and are therefore widely used in various applications. Furthermore, in order to improve the heat resistance of this rubber-modified styrenic resin composition, a styrene-maleic anhydride copolymer is mixed therein. However, although the heat resistance of the composition obtained by mixing a styrene-maleic anhydride copolymer with a conventionally known rubber-modified styrenic resin composition having a salami structure improves heat resistance, it has the drawback of significantly decreasing impact resistance. There was (Unexamined Japanese Patent Publication No. 1983)
-161836). [Problems to be Solved by the Invention] The present invention overcomes the drawbacks of conventional heat-resistant styrenic resin compositions and improves physical properties such as high impact strength, excellent gloss and heat resistance. Excellent balance
; It was made for the purpose of providing a styrenic resin composition. [Means for Solving the Problems 1] The present inventor has conducted intensive research to develop a styrenic resin composition with an excellent balance of physical properties such as impact resistance, gloss, and heat resistance. We have discovered that the use of a rubber-modified styrene-based resin composition in which the dispersed rubber form has an occlusion structure is suitable for the above-mentioned purpose, and based on this knowledge, we have completed the present invention. two. That is, the present invention provides (a) rubber-modified styrenic resin compositions 95 to 95 in which the dispersed rubber form has an occlusion structure.
and (b) a copolymer consisting of a styrene monomer and an unsaturated dicarboxylic acid anhydride, or the copolymer is rubber-modified and t: 5 to 45% by weight of the copolymer or a mixture thereof (c ) A styrenic resin composition characterized in that it consists of 0 to 30% by weight of a rubbery polymer containing a styrene component. The present invention will be explained in detail below. The rubber-modified styrenic resin composition of component (a) in the styrenic resin composition of the present invention needs to have an occlusion structure in the form of the dispersed rubber. If the dispersed rubber form does not have an occlusal structure, the impact resistance and gloss will be poor. Here, the occlusal structure means that in one rubber particle,
It refers to a structure in which the core is a styrene polymer and the shell is a rubber-like polymer, and it contains 5 or less internal occlusions, and at least 50% of them have one internal occlusion. In the present invention, the occlusion structure as described above is
It is preferable that the content is 0% or more, and if 30% or more of particles such as salami structure are mixed, there is a possibility that good gloss cannot be obtained. The rubber-modified styrenic resin composition of component (a) consists of a styrene polymer and a rubbery polymer. The styrenic polymer may be a styrene homopolymer or a copolymer of a monomer copolymerizable with styrene. Examples of the copolymerizable monomer include α-methylstyrene, vinyltoluene, vinylethylbenzene, vinylxylene, pt-butylstyrene, α
Examples include aromatic monovinyl compounds such as -methyl-p-methylstyrene and vinylnaphthalene, acrylonitrile, methyl methacrylate, methyl acrylate, methacrylic acid, acrylic acid, maleic anhydride, and phenylmaleimide. These monomers may be used alone or in combination of two or more types, but they usually account for 50% by weight or less, preferably 40% by weight or less, based on the total monomers containing styrene. Used in percentages. On the other hand, there is no particular fM limit for the type of rubbery polymer, and those conventionally used in rubber-modified styrene resin compositions, such as natural rubber, polybutadiene rubber, polyisoprene rubber, styrene-butadiene rubber, etc. Copolymer rubber, styrene-isoprene copolymer rubber, butyl rubber,
Synthetic rubber such as ethylene-propylene copolymer rubber,
Alternatively, a graft copolymer rubber of these rubbers and styrene can be used, but among these, styrene-butadiene block copolymer rubber or styrene-butadiene block copolymer rubber and polybutadiene rubber can be used. It is preferable to use a combination of the following. When styrene-butadiene copolymer rubber and polybutadiene rubber are used together, the ratio is preferably from 1070 to 6/4 (weight ratio) of the former/latter.
It is preferable to set it as 1010-6.5/3.5 (weight ratio). This styrene-butadiene block copolymer rubber has a molecular weight in the range of 50,000 to soo, ooo, and a content of polymer blocks formed from styrenes in the range of 10 to 60% by weight. Particularly preferred. If the molecular weight is less than so or ooo, the impact resistance will not be sufficient, and if it exceeds soo or ooo, the fluidity during molding will decrease, which is not preferable. In addition, the content of polymer blocks formed from styrenes is 10% by weight.
If it is less than 60% by weight, the gloss is poor, and if it exceeds 60% by weight, there is a tendency for impact resistance to decrease. In addition, this styrene-butadiene block copolymer rubber has a molecular weight of s.
o, o o o - about 1,000,000 polybutadiene rubber may be appropriately blended and used. The molecular weight of this rubbery polymer is the weight average molecular weight in terms of polystyrene determined by GPC. The rubbery polymer has an occlusion structure and has an area average particle size (diameter) of 0.1 to 0.7 μm, preferably 0.2 to 0.5 μm, and an area average particle size relative to the number average particle size (diameter). The diameter ratio is 1.0 to 2.5, preferably 1
．． It is preferable that the particles be dispersed in the styrene polymer of component (a) as particles of 0 to 1.8. If the area average particle diameter is less than 0.1/1 m, the impact resistance will not be sufficient, and if it exceeds 0.7 μm, the gloss will tend to decrease. Furthermore, when the area average particle diameter relative to the number average particle diameter exceeds 2.5, gloss tends to decrease. I; The styrenic polymer and the rubbery polymer may be contained in proportions of 70 to 92% by weight and 30 to 8% by weight, preferably 72 to 90% by weight and 28 to 10% by weight, respectively. suitable. Rubbery polymer content is 8% by weight
If it is less than 30% by weight, the effect of improving impact resistance tends to be insufficient, and if it exceeds 30% by weight, gloss and fluidity tend to decrease. The rubber-modified styrenic resin composition of component (a) can be produced by blending a styrenic polymer and a rubbery polymer. Preferably, it is prepared by polymerizing a polymerizable monomer. Next, an example of a preferred method for producing the resin composition of the present invention using a bulk-suspension two-stage polymerization method will be described. First, styrene or a mixture of styrene and a monomer copolymerizable with
Add the rubbery polymer and heat as necessary to dissolve. It is preferable to perform this dissolution as uniformly as possible. Next, a molecular weight regulator (chain transfer agent) such as an alkyl mercaptan and a polymerization initiator such as an organic peroxide to be used as necessary are added to this solution, and while heating to a temperature of about 70 to 150 °C, , the degree of polymerization is 10-80 under stirring.
% by bulk polymerization method. In this prepolymerization step, the rubbery polymer is dispersed into particles by stirring. Next, the prepolymerization solution is suspended in an aqueous phase using tricalcium phosphate, polyvinyl alcohol, or the like as a suspending agent,
Usually, suspension polymerization (main polymerization) is carried out until the degree of polymerization approaches 100%. Note that, if necessary, heating may be continued after this main polymerization step. Examples of the molecular weight regulator include mercaptans such as a-methylstyrene dimer, n-dodecylmercaptan, t-dodecylmercaptan, 1-phenylbutene-2-fluorene, dipentene, and chloroporm, terpenes, and halogen compounds. Can be done. Examples of the polymerization initiator used as desired include 1.1-bis(t-butylperoxy)cyclohexane, 1. l-bis(1-butylperoxy) 3.3
．． Peroxyketals such as 5-trimethylcyclohexane, dialkyl peroxides such as dimethyl-2.5-di(t-butylperoxy)hexane, dialkyl peroxides such as benzoyl peroxide and m-toluoyl peroxide, and simiristyl peroxydicarbonate. Examples include organic peroxides such as peroxydicarbonates, ketone heloquinides such as t-butylperoxyisopropyl carbonate and cyclohexanone peroxide, and hydroperoxides such as p-menthane hydroperoxide. The particle size, particle size distribution, and particle structure of the rubbery polymer can be controlled by changing the stirring rotation speed and the amount of molecular weight regulator used, and the amount of gel and expansion index can be controlled by the type and amount of catalyst, It can be controlled by reaction temperature, reaction time, etc. Next, the slurry obtained in this manner is treated with a conventional method to remove the bead-shaped reactants, dried, and then pelletized according to a conventional method, whereby the dispersed rubber is modified to have an occlusion structure. A styrenic polymer is obtained. The molecular weight of the matrix portion of the rubber-modified styrenic resin composition obtained in this way is too, 000 to 300,
000. Advantageously, it is preferably in the range 130,000 to 280,000. This molecular weight is 100,00
If it is less than 0, impact resistance will be poor, and if it exceeds 300,000, fluidity during molding will be insufficient. Note that the rubber-modified styrenic resin composition in which the dispersion rubber form of component (a) has an occlusion structure may contain a rubber-modified styrenic resin composition in which the dispersion rubber form has a salami structure. A rubber-modified styrenic resin composition having a salami structure is
Consists of styrene polymer and rubbery polymer. These styrenic polymers and rubber-like polymers are similar to the styrenic polymers and rubber-like polymers of the rubber-modified styrenic resin compositions in which the dispersed rubber form has an occlusion structure, but the rubber-like polymers Preferred is polybutadiene rubber. A rubber-modified styrenic resin having a salami structure is one in which 50% or more of rubber particles have six or more occlusions in which the core is a styrene polymer and the shell is a rubbery polymer. be. The content ratio of the rubber-modified styrenic resin composition having a salami structure is 45% by weight of the total amount of the rubber-modified styrenic resin composition whose dispersed rubber form has an occlusion structure and the rubber-modified styrenic resin composition which has a salami structure. % or less, particularly preferably 40% by weight or less. When the content of the rubber-modified styrenic resin composition having a salami structure exceeds 45% by weight, gloss tends to decrease. In the present invention, as component (b), a copolymer consisting of a styrene monomer and an unsaturated dicarboxylic anhydride, a rubber-modified copolymer of the copolymer, or a mixture thereof is used. In addition to styrene, the styrene monomer in the copolymer consisting of a styrene monomer and an unsaturated dicarboxylic acid anhydride includes α-methylstyrene, low methylstyrene, m
- Contains styrene derivatives such as methylstyrene, p-methylstyrene, 2,4-dichlorostyrene, 2,5-dichlorostyrene, and dimethylstyrene. Furthermore, some of these styrene monomers can be converted into methacrylic acid, methyl methacrylate, methyl acrylate, ethyl methacrylate, acrylonitrile, methacrylonitrile,
Other copolymerizable heptamers such as halogen-containing vinyl heptamers can also be substituted. In addition, as the unsaturated dicarboxylic acid anhydride, maleic anhydride is particularly useful, but itaconic acid, citraconic acid,
Anhydrides such as mesaconic acid, ethylmaleic acid, methylitaconic acid, chlormaleic acid, etc. can also be used. The copolymer consisting of a styrenic monomer and an unsaturated dicarboxylic anhydride can be obtained by polymerizing the above styrene monomer and an unsaturated dicarboxylic anhydride by a solution polymerization method, a bulk polymerization method, or a bulk-suspension polymerization method. It is copolymerized by a known method such as. Copolymers obtained by rubber-modifying this copolymer include those obtained by blending a copolymer consisting of a styrene monomer and an unsaturated dicarboxylic acid anhydride with a rubber component, and those obtained by blending a styrene monomer with a rubber component in the presence of a rubber component. and unsaturated dicarboxylic anhydride are copolymerized. Examples of the rubber component include polybutadiene rubber, butyl rubber, styrene-butadiene rubber, styrene-methyl methacrylate-butadiene rubber, acrylonitrile rubber, ethylene-propylene rubber, and natural rubber. As the above component (b), a styrene-maleic anhydride copolymer is suitable. The styrene-maleic anhydride copolymer preferably has a maleic anhydride content of 1 to 30% by weight, and particularly preferably has a maleic anhydride content of 3 to 25% by weight. If the maleic anhydride content of the styrene-maleic anhydride copolymer is less than 11% by weight, the heat resistance will be poor, and if the maleic anhydride content exceeds 30% by weight, the impact resistance will decrease, so it is preferable. do not have. Further, the molecular weight is preferably 100,000 to 300,000. Loo, if it is less than 000, the impact resistance is insufficient,
If it exceeds 300,000, fluidity decreases. In addition to components (a) and (b), the styrenic resin composition of the present invention may contain a rubber-like polymer containing a styrene component as component (c). Various rubbery polymers containing styrene components can be used, such as styrene-citadiene block copolymer rubber, styrene-isoprene block copolymer rubber, and styrene-butadiene block copolymer rubber. Rubber with partially or completely hydrogenated butadiene moiety (
SEBS), styrene-butadiene copolymer rubber (SB
R), methyl acrylate-butadiene-styrene copolymer rubber, acrylonitrile-butadiene-styrene copolymer rubber (ABS rubber), acrylonitrile-alkyl acrylate-butadiene-styrene copolymer rubber (A)
ABS), methyl methacrylate-alkyl acrylate-styrene copolymer rubber (MAS), methyl methacrylate-alkyl acrylate-butadiene-styrene copolymer rubber (MABS), and the like. Rubber-like copolymers containing these styrene compounds as one of their components have styrene units, so they have good fractionability with respect to components (a) and (b), and as a result, the effect of improving physical properties is remarkable. Component (a) in the styrenic resin composition of the present invention, (
The content ratio of component b) and component (c) is that component (a) is 9
5 to 55% by weight, preferably 90 to 60% by weight,
It is necessary that the component (b) is 5 to 45% by weight, preferably 10 to 40% by weight, and the component (c) is 0 to 30% by weight, preferably 0 to 25% by weight. If component (a) exceeds 95% by weight, heat resistance will be insufficient;
If it is less than 5% by weight, impact strength will decrease. If component (b) is less than 5% by weight, heat resistance will be insufficient, and if it exceeds 45% by weight, impact strength will decrease. Moreover, if the content of component (c) exceeds 30% by weight, the heat resistance decreases, which is not preferable. The styrenic resin composition of the present invention can be obtained by blending predetermined amounts of each of these components, and its production may be carried out by conventional methods. For example, each component may be premixed using a mixer such as a Henschel mixer or a tumbler blender, and then kneaded using an extruder, or heated rolls,
Manufactured by melt-kneading in a Banbury mixer. The order of mixing and kneading each component is not particularly limited, and (a
Components (b) and (c) may be mixed and kneaded simultaneously, or any two components may be mixed and kneaded and then the other components may be mixed and kneaded. If desired, the styrenic resin composition of the present invention may contain various commonly used additives, such as stearic acid, behenic acid, zinc stearate, calcium stearate, magnesium stearate, and ethylene bisstearamide. lubricant, organic polysiloxane, mineral oil, 2,6-di-t-butyl-4-methylphenol, stearin-β-(3,5-di-t-butyl-
Hindered phenols such as 4-hydroxyphenyl) propionate, triethylene glycol-bis-3-(3-t-butyl-4-hydroxy-5-methylphenyl) propionate, and tri(2,4-di-t-butyl) phosphorus-based antioxidants such as phenyl) phosphite, '4.4°-butylidene bis(3-methyl-6-(-butylphenyl-di-tridecyl) phosphite), other ultraviolet absorbers, antistatic agents, and release agents. Molding agents, plasticizers, dyes, pigments, various fillers, etc. can be added. Other polymers, such as polystyrene and polyphenylene ether, can also be added. Styrenic resin compositions have an excellent balance of physical properties such as impact resistance, gloss, and rigidity, and are suitably used as materials for, for example, OA equipment, home appliances, automobile parts, etc. [Example] Next, Examples The present invention will be explained in more detail by
The present invention is not limited in any way by these examples. Production Example 1 In an autoclave with an internal capacity of 5 tons and equipped with an Ikari type stirring blade,
Styrene-butadiene block copolymer (BL6533 manufactured by Bayer, molecular weight 230.000, styrene content 40%) 5279, polybutadiene (B manufactured by Ube Industries, Ltd.)
R15HB. Molecular weight 550,000) 1329, styrene 30009
and n-dodecyl mercaptan 19 as a chain transfer agent.
was added, and a bulk polymerization reaction was carried out at 130° C. for 4 hours while stirring at 400 rpm. Next, the content! (L of Ikari was placed in an autoclave equipped with stirring blades, the reaction mixture 30009, water 30009,
Add polyvinyl alcohol 109 as a suspension stabilizer, 6 g of benzoyl peroxide and 3 g of dicumyl peroxide as polymerization initiators, and raise the temperature from 80 °C to 140 °C at a temperature increase rate of 30 °C/hr while stirring at 300 rpm. The reaction mixture was further reacted at that temperature for 4 hours to obtain beads of a rubber-modified polystyrene composition. The beads were pelletized using a single screw extruder at 220°C. When the obtained pellet was analyzed using an electron microscope, it was found that
An occlusion structure with an area average particle size of 0.50 μm and a ratio of area average particle size to number average particle size of 2.2 is 85
%. The physical properties of the molded article were 96% gloss, 14 Izot impact strength, and 8 kgcm/cts. This copolymer has a rubbery polymer content of 18% by weight.
and the molecular weight was 210.000. Production Example 2 Production Example 1 was carried out in the same manner as Production Example 1 except that the rotation speed of the stirring blade in bulk polymerization was set to 50 Orpm. The obtained rubber-modified polystyrene composition had a 90% occlusion structure with an area average particle size of 0.41 μm and a ratio of area average particle size to number average particle size of 2.1, a gloss of 99%, and an isot Impact strength is 10,6k
gcrx/cm. This copolymer has a rubbery polymer content of 18% by weight and a molecular weight of 215.00%.
It was 0. Example 1 The rubber-modified polystyrene composition obtained in Production Example 1 and the styrene-maleic anhydride copolymer (Idemitsu Moremax UG830, manufactured by Idemitsu Petrochemical Co., Ltd.) were respectively 80% by weight and 2% by weight.
They were blended at a blending ratio of 0% by weight, melt-kneaded using a single-screw extruder at a cylinder temperature of 210°C, and injection molded to prepare test pieces. The physical properties of this test piece are shown in Table 1. Example 2 In Example 1, the rubber modified polystyrene composition was
40% by weight of styrene-maleic anhydride copolymer
% by weight, and a rubber-modified polystyrene composition having a salami structure (Idemitsu Styrene HT manufactured by Idemitsu Petrochemical Co., Ltd.)
The same procedure as in Example 1 was carried out except that the blending ratio of 54) was 25% by weight. Table 1 shows the physical properties of the obtained test piece. Example 3 The rubber-modified polystyrene composition obtained in Production Example 2, the rubber-modified polystyrene composition having a salami structure (Idemitsu Styrene HT50 manufactured by Idemitsu Petrochemical Co., Ltd.), and the rubber-modified styrene-maleic anhydride copolymer (manufactured by Idemitsu Petrochemical Co., Ltd.) 85% by weight and 5% by weight of Dylark D350 (manufactured by Kogyo Co., Ltd.), respectively.
, blended at a blending ratio of 10% by weight, melt-kneaded using a single-screw extruder at a cylinder temperature of 210°C, and injection molded to prepare test pieces. The physical properties of this test piece are shown in Table 1. Example 4 In Example 3, the rubber modified polystyrene composition was approximately 70
Styrene-maleic anhydride copolymer (manufactured by Idemitsu Petrochemical Co., Ltd., Idemitsu Moremax UG83) was used instead of 5% by weight of a rubber-modified polystyrene composition having a salami structure.
The same procedure as in Example 3 was conducted except that 20% by weight of 0) was added. Table 1 shows the physical properties of the obtained test piece. Example 5 In Example 3, 45% by weight of the rubber-modified polystyrene composition having a salami structure was added to the rubber-modified styrene composition.
25% by weight of styrene-maleic anhydride copolymer (Idemitsu Moremax UG830 manufactured by Idemitsu Petrochemical Co., Ltd.) was added instead of 10% by weight of maleic anhydride copolymer, and 25% by weight of methyl methacrylate-butadiene-styrene rubber (Mitsubishi Rayon) was added. The same procedure as in Example 3 was carried out except that 25% by weight of C223) was used. Table 1 shows the physical properties of the obtained test piece. Example 6 In Example 4, the rubber modified polystyrene composition was
30% by weight of the styrene-maleic anhydride copolymer.
Styrene-butadiene block copolymer rubber (TR1102 manufactured by Shell Chemical Co., Ltd.) was used in the same manner as in Example 4, except that 10% by weight of styrene-butadiene block copolymer rubber (TR1102, manufactured by Shell Chemical Co., Ltd.) was used instead of the rubber-modified styrene-maleic anhydride copolymer. . The physical properties of the test pieces are shown in Table 1. Example 7 The same procedure as in Example 6 was carried out except that 0.2 parts by weight of polydimethylsiloxane (5H200 manufactured by Toshisha Co., Ltd.) was added to 100 parts by weight of the three-component composition of Example 6. The physical properties of the obtained test piece are shown in Table 1. Comparative Example 1 In Example 1, the rubber modified polystyrene composition was
3F of styrene-maleic anhydride copolymer by weight%
The same procedure as in Example 1 was carried out except that the amount of i was set as %. Comparative Example 2 In Example 1, the rubber modified polystyrene composition was
! 5% of styrene-maleic anhydride copolymer
The same procedure as in Example 1 was carried out except that the binding was 0% by weight. Comparative Example 3 The same procedure was carried out as in Example 5 except that the styrene-maleic anhydride copolymer was 20% by weight, the styrene-containing rubber was 35% by weight, and the rubber-modified polystyrene composition having a salami structure was not added. The same procedure as in Example 5 was carried out. The physical properties of Comparative Examples 1 to 3 are shown in Table 1. In addition, the physical properties of the above test piece were measured by the following method: Gloss: Based on JISK-7105. Izotsu impact strength: Based on JISK-7110 (23℃ notched). Heat distortion temperature: Based on JISK-7207. (Left below) A! = Rubber-modified polystyrene resin composition 2 produced in Production Example 1: Rubber-modified polystyrene resin composition B-1 produced in Production Example 2: Idemitsu Styrene HT50 (Ml-3 manufactured by Idemitsu Petrochemical Co., Ltd.)
, 8g/10m1n, 200°C, 5 to 9 loads) B-2 = Idemitsu Styrene HT54 (ME-2 manufactured by Idemitsu Petrochemical Co., Ltd.)
, 3s+/10mln, 200°C, 5b9 load) C-1 = Idemitsu Moremax UG30, manufactured by Idemitsu Petrochemical Co., Ltd. Styrene-maleic anhydride copolymer (ME-2,0g/10mln, 230°C, 216 to 9
Load) C-2 = Dierk D350 rubber modified styrene-maleic anhydride copolymer (Ml-1-2y/10 manufactured by Okisui Kasei Kogyo Co., Ltd.)
m1ns 230°C, 216&9 load) D-1: Mitsubishi Rayon Co., Ltd. C223 Methyl methacrylate-butadiene-styrene copolymer rubber D-2 = Shell Chemical Co., Ltd. TR1102 Styrene-butadiene block copolymer rubber E: Toshisha 5H200 by Polydimethylsiloxane E: Parts by weight based on 100 parts by weight of the total amount of rubber-modified polystyrene resin, SMA resin, and rubber (hereinafter referred to as the margin) [Effects of the Invention] The styrenic resin composition of the present invention is in the form of a dispersed rubber. Since it has an occlusion structure, it has high impact strength, excellent gloss and heat resistance, and has an excellent balance of physical properties.

Claims (1)

[Scope of Claims] 1 (a) 95 to 55% by weight of a rubber-modified styrenic resin composition whose dispersed rubber form has an occlusion structure;
) A copolymer consisting of a styrene monomer and an unsaturated dicarboxylic acid anhydride, a rubber-modified copolymer of the copolymer, or a mixture thereof 5 to 45% by weight (c) Rubber-like material containing a styrene component A styrenic resin composition comprising 0 to 30% by weight of a polymer. 2. The rubber-modified styrenic resin composition is composed of a rubber-modified styrenic resin composition in which the dispersed rubber form has an occlusion structure and a rubber-modified styrenic composition in which the salami structure is present, and the rubber-modified styrenic composition has a salami structure. The styrenic resin composition according to claim 1, wherein the content is 45% by weight or less.