JPH11269339A - Rubber modified styrene-based resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a rubber-modified styrene-based resin composition capable of presenting formed bodies having flame retardance and excellent in balance between rigidity and impact resistance and appearance. SOLUTION: This rubber-modified styrene-based resin composition comprises a rubbery polymer having graft chains of-styrene-based resin, dispersed to be particulate in a styrene-based polymer matrix and containing a halogen-based or a phosphor-based flame retardant having <=250 deg.C melting point. In the resin composition, (1) a content of a rubbery polymer RW (wt.%) and a specific particle number RN have the relation expressed by the formula: 1.0×10<6> <RW×RN<5.0×10<6> , (2) the content RW (wt.%) of the rubbery polymer and 2-butanone-insoluble fraction GW have a relation expressed by the formula: 100<[(GW-RW)/RW]×100<200 and (3) the ratio of styrene-based polymer having <=40,000 molecular weight in a matrix phase is equal to or less than 30 wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber-modified styrene resin composition containing a flame retardant,
The present invention relates to a rubber-modified styrenic resin composition having flame retardancy, and capable of obtaining a molded article having excellent balance between rigidity and impact resistance and excellent surface appearance.

[0002]

2. Description of the Related Art Conventionally, a rubber-modified styrene-based resin in which a rubber-like polymer having a graft chain of a styrene-based polymer is dispersed in the matrix phase of a styrene-based polymer in the form of particles has been known to have impact resistance and the like. Because of its excellent mechanical properties and dimensional stability, and because of its low price, it is widely used for parts of home electric appliances and the like. However, when a rubber-modified styrenic resin is added with a flame retardant for imparting flame retardancy,
The impact resistance, such as surface impact strength, and the surface appearance, such as surface gloss, are significantly reduced, and various improvements such as increasing the content of the rubber-like polymer have been studied. At present, it has not yet been possible to satisfy market demands for flame-retardant materials while maintaining a balance between resistance and impact resistance and surface appearance.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and provides a molded article having flame retardancy, excellent rigidity and impact resistance, and excellent surface appearance. It is an object of the present invention to provide a rubber-modified styrenic resin composition that can be used.

[0004]

According to the present invention, there is provided a rubber-modified styrenic resin in which a rubbery polymer having a graft chain of the styrenic polymer is dispersed in a matrix phase of the styrenic polymer. A rubber-modified styrene-based resin composition containing a halogen-based or phosphorus-based flame retardant having a melting point of 250 ° C. or lower, wherein the rubber-modified styrene-based resin has the following (1), (2), and ( The gist is a rubber-modified styrenic resin composition that satisfies 3). (1) and the specific particle number R _N of the dispersed particles of the rubber-like polymer content R _W (wt%) of the rubber-like polymer, 1.0 × 10 ⁶ <
R _W ³ × R _N <5.0 × 10 ⁶ . (2) When the content of the rubber-like polymer R _W (% by weight) of 2-butanone insolubles G _W (wt%), but 100 <[(G _W -
R _W ) / R _W ] × 100 <200. (3) The ratio of the styrene polymer having a molecular weight of 40,000 or less in the matrix phase is 30% by weight or less.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a rubber-modified styrenic resin is contained in a matrix phase of a styrenic polymer.
A known polymer in which a rubber-like polymer having a graft chain of a styrene-based polymer is dispersed in the form of particles, and in the presence of the rubber-like polymer, one or more styrene-based monomers, or Is obtained by polymerizing monomers copolymerizable by bulk polymerization, or bulk / suspension two-stage polymerization, etc., and further includes the case where a rubber-unmodified styrene-based resin is mixed therein. .

The styrene monomer includes, for example, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene,
Nuclear alkyl-substituted styrenes such as ethylstyrene and pt-butylstyrene, α-methylstyrene, α-methyl-p
Α-alkyl-substituted styrene such as -methylstyrene, o-
Nuclear halogen-substituted styrenes such as chlorostyrene, m-chlorostyrene, p-chlorostyrene, p-bromostyrene, 2-methyl-1,4-chlorostyrene, and 2,4-bromostyrene, and the like. Alternatively, it is used as a mixture of two or more. Examples of other copolymerizable monomers include, for example, acrylic acid such as acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, and the like. Methacrylic acid esters,
Examples include acrylonitrile, methacrylonitrile, maleic anhydride, maleimide, and nucleus-substituted maleimide.

The rubbery polymer has a glass transition temperature of preferably 0 ° C. or lower, more preferably -20 ° C. or lower, for example, polybutadiene, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer Rubber such as polyisoprene, isoprene-isobutylene copolymer, ethylene-propylene copolymer, ethylene-propylene-non-conjugated diene copolymer, acrylic polymer, urethane polymer, and styrene-butadiene block copolymer And thermoplastic elastomers such as styrene-isoprene block copolymers and hydrogenated products thereof. Among them, polybutadiene rubber, styrene-butadiene copolymer rubber, ethylene-propylene copolymer rubber, ethylene-propylene -Non-conjugated diene copolymer rubber, acrylic polymer, Styrene - butadiene block copolymer elastomer, styrene - isoprene block copolymer elastomer or hydrogenated products thereof elastomers are preferred, polybutadiene rubber, styrene - butadiene copolymer rubber are particularly preferred. These are used alone or as a mixture of two or more.

[0008] In the present invention, the rubber-modified styrene-based
The resin has a rubbery polymer content R_W(Wt%) and rubbery
Number R of intrinsic particles of polymer dispersed particles_NIs 1.0 × 10
⁶<R_W ^Three× R_N<5.0 × 10⁶Satisfying the relationship
Is required, 2.0 × 10 ⁶<R_W ^Three× R_N<3.5
× 10⁶It is preferable to satisfy the following relationship. R_W ^Three× R _N
Is less than the above range, the impact strength of the composition is
On the other hand, above the above range, the rigidity of the composition is
Inferior, and the surface appearance such as gloss is reduced.

Here, the content of the rubbery polymer R
_W (% by weight) is obtained by dissolving the rubber-modified styrene resin in chloroform, adding iodine monochloride to react double bonds in the rubber component, and then adding potassium iodide to remove the remaining iodine monochloride. And then back titrated with sodium thiosulfate.

[0010] Also, the unique number of particles R _N of the dispersed particles of the rubber-like polymer, and is calculated by the following method. From a 3% by weight dimethylformamide solution of a rubber-modified styrene-based resin, particles were obtained from a volume-based particle size distribution of a rubbery polymer measured using a laser diffraction / scattering type particle size distribution analyzer (“LA-700” manufactured by Horiba, Ltd.). The section from 0.05 μm to 262.4 μm in diameter was divided into 64 equally spaced logarithmic widths, and for each divided section, the volume% of the total volume of the particles in that section was divided by the particle volume of the maximum particle diameter in that section. calculating a value, and the sum of all sections of this value as the intrinsic particle number R _N of the dispersed particles.

[0011] For example, when volume frequency of particles in a certain divided section of V _d%, as particles having a maximum particle diameter d of the section exists V _d%, the inherent particle number R _N is expressed by the following formula The Rukoto.

[0012]

(Equation 1)

(However, the division width of the particle diameter is a value obtained by dividing the section from 0.05 μm to 262.4 μm into 64 logarithmically equally spaced sections, the first section being 0.05 to 0.06 μm. , Π are pi.)

[0014] In the present invention, the rubber-modified styrenic resin, the content of the rubber-like polymer R _W (% by weight) 2
- and butanone insolubles G _W (wt%), but 100 <[(G
It is essential to satisfy the relationship of _W− R _W ) / R _W ] × 100 <200, and 120 <[(G _W− R _W ) / R _W ] ×
It is preferable that the relationship of 100 <180 is satisfied. [(G
_{When the value of W−} R _W ) / R _W ] × 100 is less than the above range,
The impact resistance of the composition is inferior. On the other hand, above the above range, the rigidity of the composition is inferior.

[0015] Here, 2-butanone insolubles G _W (wt%) is, after dissolving the rubber-modified styrenic resin 1g 2-butanone 30 ml, centrifuge (Hitachi Koki Co., Ltd., "CR26H" )), The mixture was centrifuged at 20 ° C. for 30 minutes using a rotor having a radius of 11.4 cm, the supernatant was removed, and the mixture was dried under reduced pressure. Yes, it can be regarded as the amount of the styrene polymer grafted and encapsulated in the rubbery polymer.

Further, in the present invention, the rubber-modified styrenic resin must have a styrene-based polymer having a molecular weight of 40,000 or less in the matrix phase in a proportion of 30% by weight or less, and 5 to 15% by weight. It is preferred that If the proportion of the styrene-based polymer having a molecular weight of 40,000 or less exceeds the above range, the impact resistance of the composition will be inferior, and if it is less than the above range, the moldability of the composition tends to decrease.

Here, the molecular weight 4 in the matrix phase
The ratio of the styrene-based polymer of 10,000 or less was determined by measuring the gel permeation chromatograph of the 2-butanone-soluble part, using elution curves of 15 types of monodisperse polystyrene having different molecular weights as a calibration curve, and calculating the cumulative percentage and the molecular weight. It is obtained from the value.

[0018] In the present invention, the content R _W of the rubber-like polymer of the rubber-modified styrenic resin is usually 3
15% by weight, preferably 4 to 12% by weight, more preferably 6 to 9% by weight. When the content of the rubber-like polymer is less than the above range, the impact resistance as a composition tends to be inferior. On the other hand, when the content is more than the above range, the rigidity of the composition is inferior, and the surface appearance such as gloss decreases. It becomes a tendency.

In the present invention, the weight average molecular weight of the styrene polymer constituting the matrix phase of the rubber-modified styrene resin is preferably 150,000 to 300,000, and the molecular weight distribution (weight average molecular weight) / Number average molecular weight)
Is preferably from 1.5 to 3.0.

In the present invention, the rubber-modified styrene resin is prepared by dissolving or dispersing a rubbery polymer in a styrene monomer in advance by a known method, and further adding a solvent such as ethylbenzene and a polymerization initiator. The solution thus obtained is continuously supplied to a first reactor of a complete mixing type, and polymerized until the solid content concentration becomes about 30% by weight. On the other hand, the styrene-based monomer and the polymerization initiator are continuously supplied to the second reactor of the complete mixing type, and polymerization is performed until the solid content concentration becomes about 20% by weight. The polymerization liquid continuously taken out from the first reactor and the second reactor was transferred into a mixer by a gear pump and mixed under high shear, and further continuously fed to two plug flow reactors installed in series. Then, the polymerization is carried out while continuously adding a chain transfer agent or the like to a solid content concentration of about 85% by weight. The obtained polymerization liquid is guided to a devolatilizer to remove unreacted styrene-based monomer and a solvent such as ethylbenzene, and then extruded into a strand and cooled to form a pellet. .

[0021] Here, the content R _W of the rubber-like polymer in the rubber-modified styrenic resin, and the amount of the rubber-like polymer to be dissolved or dispersed in advance styrene monomer, the first reactor and the second
Flow rate of both polymerization solution continuously removed from the reactor, or, by operating such as by changing the final polymerization rate, specific particle number R _N of the dispersed particles of the rubbery polymer, the polymerization solution extracted from the first reactor the solids concentration was manipulated by such varying, 2-butanone insolubles G _W, and operated such as by changing the final polymerization rate, also the following molecular weight of 40,000 of the matrix phase of the styrenic polymer The ratio is controlled by changing the temperature of the polymerization liquid flowing through the two plug flow reactors and / or the amount of the chain transfer agent added.

In the production of the rubber-modified styrene resin, as a polymerization initiator, for example, 1,1-bis (t-butylperoxy) cyclohexane, 1,1-bis (t-butylpaoxy) -3, Peroxy ketals such as 3,5-trimethylcyclohexane, di-t-butyl peroxide, 2,5-dimethyl-2,5-di (t
Dibutyl peroxides such as -butylperoxy) hexane; diacyl peroxides such as benzoyl peroxide and m-toluoyl peroxide; peroxy dipercarbonates such as dimyristyl peroxy dipercarbonate; Oxyisopropyl carbonate, t-butyl peroxybenzoate,
Peroxyesters such as t-butylperoxyacetate; ketone peroxides such as cyclohexanone peroxide; hydroperoxides such as p-menthane hydroperoxide; and the like, alone or in combination of two or more. Used as

As the chain transfer agent, for example, n-octyl mercaptan, n-dodecyl mercaptan, t-
Examples thereof include mercaptans such as dodecyl mercaptan, α-methylstyrene dimer, terpinolene, and the like, and these may be used alone or in combination of two or more.

In the rubber-modified styrenic resin composition of the present invention, the flame-retardant contained in the rubber-modified styrenic resin may be a halogen-based or phosphorus-based flame retardant having a melting point of 250 ° C. or less. Required, 100-2
Preferably, it has a melting point of 00 ° C. When the flame retardant has a melting point of more than 250 ° C., it is difficult to satisfy impact resistance and surface appearance as a composition.

In the present invention, examples of the flame retardant include tris (tribromoneopentyl) phosphate, triphenyl phosphate, tricresyl phosphate, hexabromocyclododecane, tetrabromobisphenol A, and tetrabromobisphenol A. Bis (2,3-dibromopropyl ether) and the like. These may be used alone or in combination of two or more.

The content of the flame retardant in the rubber-modified styrenic resin composition of the present invention is preferably 4 to 9 parts by weight based on 100 parts by weight of the rubber-modified styrenic resin. When the content of the flame retardant is less than the above range, sufficient flame retardancy tends not to be imparted to the composition. On the other hand, when the content is more than the above range, the impact resistance and heat resistance of the composition tend to decrease.

The rubber-modified styrenic resin composition of the present invention comprises the rubber-modified styrenic resin and the flame retardant as essential components. If necessary, antimony trioxide may be further used as a flame retardant auxiliary. May be contained, and the content of antimony trioxide at that time may be in the range of 100% by weight.
It is preferably 1 to 3 parts by weight based on parts by weight.

If necessary, phenol derivatives such as hindered phenols, quinoline derivatives, p-
Antioxidants such as phenylenediamine derivatives, hydroquinone derivatives, thiocarbamate derivatives, phosphite derivatives, antioxidants, coloring inhibitors, salicylate derivatives, benzophenone derivatives, benzotriazole derivatives, benzoate derivatives, Cyanoacrylate derivatives, hindered amine derivatives,
Light stabilizers such as nickel complex salts, organopolysiloxanes, aliphatic hydrocarbon waxes, ester waxes of higher fatty acids and higher alcohols, lubricants such as bisamides of higher fatty acids, higher fatty acids and metal salts of higher fatty acids, dioctyl phthalate, dibenzyl Lubricants such as phthalate, chlorinated aliphatic esters, chlorinated paraffin, mineral oil, antistatic agents, release agents, dyes and pigments, calcium carbonate, magnesium hydroxide, barium sulfate, titanium oxide, zinc oxide, magnesium oxide, silica, Additives such as inorganic fillers such as talc and clay may be added. These additives can be added not only to the rubber-modified styrenic resin after polymerization but also to the raw material before the polymerization of the rubber-modified styrenic resin starts, the reaction liquid during the polymerization, and the like.

The production of the rubber-modified styrenic resin composition of the present invention comprises the above-mentioned rubber-modified styrenic resin, the above-mentioned flame retardant, and if necessary, the above-mentioned flame-retardant auxiliary and the above-mentioned additives.
Flame retardants, flame retardant aids, additives and the like are optionally masterbatches, melt kneaders usually used for the production of thermoplastic resin compositions, for example, single-screw extruders, twin-screw extruders, rolls, Banbury mixers, This is performed by melt-kneading under ordinary conditions using a kneader or the like.

The rubber-modified styrenic resin composition of the present invention described above is formed into a molded article by a commonly used molding method, for example, an injection molding method, an extrusion molding method, a hollow molding method, a thermoforming method, and the like. Used for various purposes such as home electric parts and office equipment.

[0031]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the present invention. The rubber-modified styrene resin, flame retardant, and flame retardant auxiliary used in the following Examples and Comparative Examples are shown below.

[0032]Rubber-modified styrenic resin PS-1; produced by the method described below,
Polymer content R_W7.2% by weight, dispersion of rubbery polymer
Eigenparticle number R of particles_N6542,2-butanone insoluble matter G
_W18.5% by weight, thus R_W ^Three× R_N= 2.44 ×
10⁶, [(G _W-R_W) / R_W] X 100 = 157
Styrene with a molecular weight of 40,000 or less in the matrix phase
14.1% by weight of the system polymer.

As a polymerization initiator, 100 parts by weight of a solution obtained by dissolving 10.5% by weight of polybutadiene rubber ("AP-755A" manufactured by Nippon Elastomer Co., Ltd.) in 73.8% by weight of styrene and 15.7% by weight of ethylbenzene was used as a polymerization initiator. The raw material liquid mixed with 0.05 parts by weight of butyl peroxybenzoate is continuously supplied at a rate of 8 liters / hour to a 25 liter internal mixing type first reactor equipped with a double helical blade stirrer with a draft tube. And temperature 110.4
At a rotation speed of a stirring blade of 80 rpm and a residence time of 3.1 hours. The solid content concentration at the outlet of the reactor was 29.7% by weight.
And On the other hand, a raw material liquid obtained by mixing 0.05 parts by weight of t-butyl peroxybenzoate as a polymerization initiator with 100 parts by weight of styrene was used in a complete mixing type second reactor of the same type as the first reactor in an internal volume of 15 liters. The reactor was continuously supplied at a rate of 4 liters / hour, reacted at a temperature of 117.3 ° C., a rotation speed of a stirring blade of 50 rpm, and a residence time of 3.8 hours. The solid content concentration at the reactor outlet was 20.2% by weight. did. The polymerization liquid continuously taken out from the first reactor and the second reactor was transferred into a mixer having an internal volume of 1 liter by a gear pump,
The mixture was mixed under a shear of sec ^-1 and continuously supplied to two 25-liter plug-flow reactors installed in series.
-Methylstyrene dimer was continuously added so as to be 0.07% by weight and zinc stearate as a lubricant so as to be 0.05% by weight. The reaction was carried out by adjusting the temperature so that a temperature gradient of ° C was obtained. The final conversion at the reactor outlet was 85%. The resulting polymerization solution is led to a devolatilizer to remove unreacted styrene and ethylbenzene,
Next, it was extruded into a strand and cooled to form a pellet.

PS-2; by the same method as PS-1
Manufactured rubbery polymer content R _W8.3% by weight, go
Number of Dispersed Particles R of Dispersed Polymer_N2696, 2-
Butanone insolubles G_W20.0% by weight, thus R_W ^Three×
R_N= 1.50 × 10⁶, [(G_W-R_W) / R_W] ×
100 = 141, molecular weight 4 in the matrix phase
10.2% by weight of a styrene-based polymer of 10,000 or less.

PS-3; by the same method as PS-1
Manufactured rubbery polymer content R _W7.3% by weight, go
Number of Dispersed Particles R of Dispersed Polymer_N2536, 2-
Butanone insolubles G_W19.3% by weight, thus R_W ^Three×
R_N= 0.98 × 10⁶, [(G_W-R_W) / R_W] ×
100 = 164, the molecular weight 4 in the matrix phase
12.1% by weight of 10,000 or less styrene-based polymer.

PS-4; by the same method as PS-1
Manufactured rubbery polymer content R _W13.0% by weight,
Number of inherent particles R of dispersed particles of rubbery polymer_N2388, 2
-Butanone insolubles G_W26.7% by weight, thus R_W ^Three
× R_N= 5.30 × 10⁶, [(G_W-R_W) / R_W]
× 100 = 105, the molecular weight in the matrix phase
The ratio of the styrene polymer of 40,000 or less is 9.8% by weight.

PS-5; by the same method as PS-1
Manufactured rubbery polymer content R _W8.3% by weight, go
Number of Dispersed Particles R of Dispersed Polymer_N8587, 2-
Butanone insolubles G_W15.3% by weight and therefore R_W ^Three×
R_N= 4.90 × 10⁶, [(G_W-R_W) / R_W] ×
100 = 84 and the molecular weight in the matrix phase is 40,000
The ratio of the following styrene-based polymer is 11.8% by weight.

PS-6; by the same method as PS-1
Manufactured rubbery polymer content R _W7.3% by weight, go
Number of Dispersed Particles R of Dispersed Polymer_N6471, 2-
Butanone insolubles G_W18.4% by weight, thus R_W ^Three×
R_N= 2.50 × 10⁶, [(G_W-R_W) / R_W] ×
100 = 152, molecular weight 4 in the matrix phase
32.2% by weight of styrene-based polymer of not more than 10,000.

Flame retardant FR-1; tris (tribromoneopentyl) phosphate (melting point: 182 ° C., bromine content: 71% by weight, “CR900” manufactured by Daihachi Chemical Co.) FR-2: Tetrabromobisphenol A bis (2,3
-Dibromopropyl ether) (melting point 90-150 ° C,
Bromine content 68% by weight, "FG310" manufactured by Teijin Chemicals Ltd.
0 "). FR-3: ethylene bis (pentabromobenzene) (melting point: 345 ° C., bromine content: 82% by weight, “Saytex 8010” manufactured by Albemarle). FR-4; ethylene bis (tetrabromophthalimide)
(Melting point 453 ° C., bromine content 67% by weight, “BT93” manufactured by Albemarle Co.). Flame retardant aid FRA-1; antimony trioxide (antimony trioxide / polystyrene = 90% by weight / 10% by weight mixture, "HM203P" manufactured by Suzuyu Chemical Co., Ltd.).

Examples 1 to 5 and Comparative Examples 1 to 8 The rubber-modified styrenic resin shown in Table 1 and a flame retardant and a flame retardant aid were mixed in the amounts shown in Table 1 with a tumbler, and then mixed with a screw feeder. The mixture was kneaded with a screw extruder to produce a rubber-modified styrenic resin composition and pelletized. In Examples 2 to 5 and Comparative Examples 1 to 8, the compounding amount of the flame retardant was such that the bromine content in Example 1 was 6 parts by weight based on 100 parts by weight of the rubber-modified styrene resin. The amount was determined so that the amount was 5 parts by weight based on 100 parts by weight of the rubber-modified styrene resin. Each of the obtained rubber-modified styrene resin composition pellets was injection-molded at a resin temperature of 200 ° C. and a mold temperature of 40 ° C. using an injection molding machine (“IS-90B”) manufactured by Toshiba Machine Co., Ltd. Was molded. For each of the obtained test specimens, the impact resistance, rigidity, surface appearance, and flame retardancy were measured and evaluated by the following method, and the results were shown in Table 1.
It was shown to.

Impact resistance The center of a 3 mm thick sheet-shaped test piece, the tip diameter of which is 1/2
An inch-shaped cone was dropped, and the surface impact strength was measured by the product of the weight and the height at which the test piece did not crack. Rigidity The tensile yield point strength was measured in accordance with JIS K7113. Per sheet specimen surface appearance thickness 3mm, JIS Z874
According to No. 1, the specular glossiness at 60 degrees was measured. Flame retardancy The V-2 test was carried out by a method based on UL94 issued by Underwriter Laboratories of the United States. The specimen thickness is 1/12 inch.

[0042]

[Table 1]

[0043]

According to the present invention, there is provided a rubber-modified styrenic resin composition which has flame retardancy, can obtain a molded article having excellent balance between rigidity and impact resistance and excellent surface appearance. Can be.

Claims (4)

[Claims] 1. A rubber-modified styrene-based resin in which a rubber-like polymer having a graft chain of a styrene-based polymer is dispersed in a matrix phase in a styrene-based polymer matrix phase,
A rubber-modified styrene-based resin composition containing a halogen-based or phosphorus-based flame retardant having a melting point of 250 ° C. or lower, wherein the rubber-modified styrene-based resin has the following (1), (2), and
A rubber-modified styrenic resin composition satisfying (3). (1) and the specific particle number R _N of the dispersed particles of the rubber-like polymer content R _W (wt%) of the rubber-like polymer, 1.0 × 10 ⁶ <
R _W ³ × R _N <5.0 × 10 ⁶ . (2) When the content of the rubber-like polymer R _W (% by weight) of 2-butanone insolubles G _W (wt%), but 100 <[(G _W -
R _W ) / R _W ] × 100 <200. (3) The ratio of the styrene polymer having a molecular weight of 40,000 or less in the matrix phase is 30% by weight or less. 2. A rubber-modified styrene resin composition according to claim 1, wherein the content R _W of the rubber-like polymer in the rubber-modified styrenic resin is 6-9% by weight. 3. The content of the halogen-based or phosphorus-based flame retardant is 4 to 4 parts by weight based on 100 parts by weight of the rubber-modified styrene resin.
The rubber-modified styrenic resin composition according to claim 1 or 2, which is 9 parts by weight. 4. The rubber-modified styrenic resin composition according to claim 3, further comprising 1 to 3 parts by weight of antimony trioxide based on 100 parts by weight of the rubber-modified styrenic resin.