JPH05271501A - Polystyrenic resin composition having excellent impact resistance, heat resistance and weather resistance - Google Patents

Abstract

PURPOSE:To obtain a polystyrenic resin composition having excellent impact resistance, heat resistance and weather resistance. CONSTITUTION:This polystyrenic resin composition comprises (A) 97-60 pts.wt. polystyrenic resin having syndiotactic structure and (B) 3-40 pts.wt. graft polymer obtained by subjecting a monomer mixture consisting of 1-59wt.% aromatic vinyl-based monomer, 1-20wt.% acrylic monomer, 0-20wt.% copolymerizable vinyl-based monomer and 0-5wt.% polyfunctional monomer to graft polymerization in the presence of 40-90wt.% acrylic rubber polymer latex containing >=50wt.% acrylic rubber comprising 60-99.9wt.% acrylic alkyl ester and 0.1-5wt.% polyfunctional monomer, having >=0.2mum weight-average particle diameter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polystyrene resin composition having a modified impact resistance. More specifically, the present invention relates to a polystyrene resin composition having a syndiotactic structure, which has high heat resistance and excellent impact resistance and weather resistance.

[0002]

2. Description of the Related Art A thermoplastic resin having excellent heat resistance, which uses polystyrene having a syndiotactic structure, has already been disclosed in JP-A-62-257950. Further, JP-A-63-268711 discloses a method of improving the moldability of syndiotactic polystyrene. However, this polystyrene having a syndiotactic structure is inferior in heat resistance, impact resistance, and weather resistance, and thus has a drawback that it cannot be practically used in a limited field. Further, when a commercially available ABS resin or MBS resin is added, there is a drawback that the weather resistance is deteriorated.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a polystyrene resin composition having a syndiotactic structure, which is excellent in heat resistance, impact resistance and weather resistance.

[0004]

The present invention provides "(A) 97-60 parts by weight of a polystyrene resin having a syndiotactic structure, and (B) an alkyl acrylate 60-
99.9% by weight, and 0.1 to 5% by weight of polyfunctional monomer
Of acrylic rubber having a weight average particle size of 0.2 μm
In the presence of 40 to 90% by weight (as solid content) of an acrylic rubber polymer latex containing 50% by weight or more of the above, 1 to 59% by weight of an aromatic vinyl monomer, 1 to 59% of an acrylic monomer. 20% by weight, copolymerizable vinyl monomer 0
Of 20 to 20% by weight and 0 to 5% by weight of a polyfunctional monomer, or 3 to 40 parts by weight of a graft copolymer (B) obtained by graft polymerization of a monomer mixture. And a polystyrene-based resin composition having excellent impact resistance, heat resistance, and weather resistance.

The polystyrene resin used in the present invention has a syndiotactic structure, that is, a three-dimensional structure in which a side chain phenyl group or a substituted phenyl group is alternately located in the opposite direction with respect to the main chain composed of carbon-carbon bonds. Is to have. As the polystyrene resin, polystyrene, poly (alkylstyrene), poly (halogenated styrene) poly (alkoxystyrene), poly (benzoic acid ester styrene) and a mixture thereof, or a copolymer containing them as a main component is used. Used. The poly (alkylstyrene) includes poly (methylstyrene), poly (ethylstyrene), poly (isopropylstyrene), poly (tertiarybutylstyrene), and the like, and the poly (halogenated styrene) includes poly (alkylstyrene). Chlorostyrene), poly (bromostyrene), etc.
Examples of poly (alkoxystyrene) include poly (methoxystyrene) and poly (ethoxystyrene).

Next, the graft copolymer (B) used in the present invention will be described in detail. The graft copolymer (B) is used for the purpose of improving impact resistance. By using an acrylic rubber for the graft copolymer (B) instead of a diene rubber, it can be used as an impact resistance modifier having excellent weather resistance. The acrylic rubber polymer latex used for the preparation of this graft copolymer is 50% by weight or more, preferably 70% by weight or more, of a "large particle size" acrylic rubber polymer latex having a weight average particle diameter of 0.2 µm or more. % Of the acrylic rubber polymer latex (solid content conversion).

When the weight-average particle diameter of the above-mentioned "large particle size" acrylic rubber polymer latex is less than 0.2 μm, the impact strength of the finally obtained resin composition should be sufficiently enhanced. I can't. Further, when the proportion of the "large particle size" acrylic elastic latex in the acrylic rubber polymer latex is less than 50% by weight, the effect of using the "large particle size" rubber latex is reduced, and 2μ
Similar to the case where the acrylic elastic latex having a particle size of less than m is used alone, only a resin composition having a low impact strength can be obtained.

The alkyl acrylate used as a component of the acrylic rubber which is a constituent of the graft copolymer (B) in the present invention has an alkyl group having 2 to 10 carbon atoms, and its specific examples are as follows. As an example, ethyl acrylate, propyl acrylate, acrylic acid n-
Butyl, isobutyl acrylate, hexyl acrylate,
Examples thereof include n-octyl acrylate and 2-ethylhexyl acrylate.

The acrylic rubber must contain a polyfunctional monomer that facilitates the graft cross-linking, and the amount of the acrylic rubber used is 0.1 based on the acrylic rubber.
~ 5% by weight. If it is less than 0.1% by weight, sufficient graft cross-linking cannot be obtained, and if it exceeds 5% by weight, elastic properties are impaired, which is not preferable.
Specific examples of the polyfunctional monomer include divinylbenzene, diacrylic acid ester or dimethacrylic acid ester which is an ester of acrylic acid or methacrylic acid and polyhydric alcohol, and those having an allyl group, for example, triallyl cyanurate and isocyanuric acid. Examples thereof include triallyl acid, allyl acrylate, allyl methacrylate, diallyl itaconate and diallyl phthalate. From the viewpoint of graft crossing property, an allyl group-containing polyfunctional monomer is particularly preferable.

The acrylic rubber is preferably produced by a usual emulsion polymerization method. Examples of emulsifiers include anionic surfactants such as fatty acid salts, alkyl sulfate salts, alkylbenzene sulfonates, alkyl phosphate salts, dialkyl sulfosuccinates, polyoxyethylene alkyl ethers and polyoxyethylene fatty acid esters. , Nonionic surfactants such as sorbitan fatty acid ester and glycerin fatty acid ester, and cationic surfactants such as alkylamine salts can be used. These surfactants can be used alone or in combination. Also, depending on the type of emulsifier,
When the pH is on the alkaline side, an appropriate pH adjusting agent can be used to prevent hydrolysis of the alkyl acrylate.

As the polymerization initiator, an ordinary inorganic initiator such as persulfate, an organic peroxide, an azo compound or the like may be used alone, or the above compound and a sulfite, a hydrogen sulfite or a thiosulfate may be used. , A first metal salt, sodium formaldehyde sulfoxylate, etc. may be combined and used as a redox initiator. Preferred persulfates as the initiator are sodium persulfate, potassium persulfate, ammonium persulfate and the like, and as the organic peroxide, t-butyl hydroperoxide, cumene hydroperoxide, benzoyl peroxide, lauroyl peroxide and the like. Is.

A chain transfer agent may be used for controlling the molecular weight of the polymer, and alkyl mercaptan having 5 to 20 carbon atoms can be used. The polymerization can be carried out at a temperature equal to or higher than the decomposition temperature of the polymerization initiator under ordinary emulsion polymerization conditions. The polymerization can be carried out at once with the total amount of the monomer or the mixture of the monomers, or while continuously adding the entire amount or a part thereof. However, from the viewpoints of stability of polymerization, removal of heat of polymerization reaction, etc., it is preferable to carry out polymerization while adding all or a part thereof.

The weight average particle size of these acrylic rubber polymer latices can be measured from an electron micrograph of the latex or by a light scattering method or the like. These measuring methods are described in detail in "Chemistry of Polymer Latex" by Soichi Muroi (published by Polymer Publishing Co., Ltd. on May 5, 1945). The graft copolymer (B) used in the present invention is obtained by emulsion graft polymerization of an aromatic vinyl monomer and an acrylic monomer in the presence of the above acrylic rubber polymer latex. Is. At this time, another copolymerizable vinyl monomer may be used in combination.

Typical examples of the aromatic vinyl compound include styrene, but in addition, α-substituted styrene, nucleus-substituted styrene and its derivatives such as α-methylstyrene, chlorostyrene, vinyltoluene and the like may be used. .. As the acrylic monomer, those having an alkyl group having 1 to 4 carbon atoms are preferable, and for example, methyl methacrylate, ethyl methacrylate, propyl methacrylate,
Isopropyl methacrylate, n-butyl methacrylate,
Examples thereof include isobutyl methacrylate and tert-butyl methacrylate, and methyl methacrylate is particularly preferable.

The copolymerizable vinyl monomers include methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, i-butyl acrylate, t-butyl acrylate, and acrylic acid 2. -Acrylic acid alkyl esters such as -ethylhexyl and n-octyl acrylate, and acrylonitrile can be used.
Further, as the polyfunctional monomer, divinylbenzene, triallyl cyanurate, triallyl isocyanurate, acrylic acid acrylate, allyl methacrylate, diallyl itaconic acid, diallyl phthalate and the like can be used.

The proportion of the acrylic rubber polymer in the graft copolymer (B) is preferably 40 to 90% by weight in terms of solid content. When this proportion exceeds 90% by weight, the mixing property of the final resin composition is remarkably lowered, and a problem of deteriorating the surface appearance of so-called spots, fish eyes, etc. occurs, and conversely less than 40% by weight. Then
The effect of improving the impact resistance of the resin composition is small, and either case is not preferable.

The ratio of the aromatic vinyl monomer, acrylic monomer, copolymerizable vinyl monomer and polyfunctional monomer used for emulsion graft polymerization is such that the resulting graft copolymer is obtained. From the viewpoint of affinity with the syndiotactic polystyrene resin mixed in the subsequent step, 1 to 59% by weight of the aromatic vinyl monomer and 1 to 20 of the acrylic monomer.
%, Copolymerizable vinyl monomers 0 to 20% by weight and polyfunctional monomers 0 to 5% by weight, and more preferably aromatic vinyl monomers 5 to 40% by weight. , Acrylic monomer 5-20% by weight, copolymerizable vinyl monomer 0-20% by weight and polyfunctional monomer 0-3% by weight
Is.

In the composition of the present invention, the graft copolymer (B) used as an impact modifier is preferably produced by a usual emulsion graft polymerization method. In this emulsion graft polymerization, as the emulsifier, the same ones as those exemplified above as the emulsifier used for producing the acrylic rubber can be used. Depending on the type of emulsifier, the pH of the polymerization system
When is on the alkaline side, an appropriate pH adjusting agent can be used to prevent hydrolysis of the alkyl acrylate.

As the polymerization initiator, the same ones as those exemplified above as the polymerization initiator used for the production of acrylic rubber can be used. A chain transfer agent or a cross-linking agent may be used to control the molecular weight and graft ratio of the graft copolymer. As the chain transfer agent, an alkyl mercaptan having 5 to 20 carbon atoms can be used. As such, a polyfunctional monomer such as divinylbenzene or 1,3 butylene glycol dimethacrylate can be used.

The emulsion graft polymerization is carried out at a temperature not lower than the decomposition temperature of the polymerization initiator under ordinary emulsion polymerization conditions. In this polymerization, the polymerization in each stage can be carried out at once with the total amount of each monomer or mixture of monomers being added at one time, or while continuously adding all or a part thereof. However,
From the viewpoint of stability of polymerization, removal of heat of polymerization reaction, etc., it is preferable to carry out polymerization while adding all or a part thereof. The obtained latex of graft copolymer is usually salted out or acidified and coagulated, filtered, washed with water and recovered in powder form, or spray dried, freeze dried or the like to be recovered in powder form. it can.

In the present invention, the blend of the graft copolymer (B) used as the impact modifier and the syndiotactic polystyrene resin is preferably in powder form, for example, by a ribbon blender, a Henschel mixer or the like. It is carried out uniformly, and subsequently, it is kneaded by a known kneading machine such as a mixing roll or a Banbury mixer, and molded by an extruder, an injection molding machine or the like.

The polystyrene resin composition of the present invention may further contain known stabilizers, plasticizers, lubricants, ultraviolet absorbers, release agents, release agents, colorants, flame retardants, etc., if necessary. You may. The polystyrene resin composition of the present invention,
It can be advantageously used as household products, electric products, automobile materials, or various mechanical parts materials.

[0023]

[Example 1]

(1) Synthesis of acrylic rubber (A-1) latex 180 parts of ion-exchanged water whose nitrogen was replaced in a reaction vessel,
0.3 parts of boric acid, 0.03 parts of anhydrous sodium carbonate, 1.5 parts of potassium oleate, and 0.15 parts of potassium persulfate were dissolved and maintained at 70 ° C., and acrylic acid n- was added while stirring.
A mixture of 99.5 parts of butyl and 0.5 part of allyl methacrylate was added dropwise over 4 hours. 70 after the dropping
Polymerization was completed by holding at 2 ° C for 2 hours. Polymerization rate is 99.3
%, The pH of the latex was 7.2. The particle size of the latex was 0.08 μm.

(2) Synthesis of enlargement latex (B). Ethyl acrylate 80 parts Methacrylic acid 20 parts Potassium persulfate 0.5 parts Nonsal TK-1 (Nippon Yushi KK, semi-hardened beef tallow potassium ken) 2.0 parts Ravisol 80 (Nippon Yushi KK, sodium octyl sulfosuccinate) 1 0.0 parts Water 200 parts The above components were polymerized at 70 ° C. for 4 hours to obtain an emulsion latex having a pH of 6.2.

(3) Synthesis of enlarged latex (A-2). 100 parts (solid content) of the acrylic rubber latex (A-1) was placed in a reactor equipped with a stirrer, and 2.0 parts (solid content) of the latex for enlargement (B) was stirred for 10 seconds. Added to obtain a bloated latex (A-2). This enlarged latex has a weight average particle size of 0.39.
It was a “large particle size” latex of μm.

(4) Production of mixed rubber latex (A-3). The small particle size rubber latex (A-1) and the large particle size rubber latex (A-2) obtained in the steps (1) and (3) were uniformly mixed at a weight ratio of 20/80 at room temperature. , Mixed rubber latex (A-3) was obtained. About this mixed rubber latex (A-3), a weight average particle diameter and a particle diameter of 0.2
The rubber weight ratio of not less than μm was measured. This measurement is performed by the light scattering method [dynamic light scattering photometer DL manufactured by Otsuka Electronics Co., Ltd.
S-700] and the rubber latex were individually measured by a transmission electron microscope [JEM-100S manufactured by JEOL Ltd.] photograph. It was confirmed that the weight average particle diameters were in good agreement with each other. The measurement results by the light scattering method are shown in the column of Example 1 in Table 1.

(5) Synthesis of graft copolymer (G-1). The mixed rubber latex (A-
3) 60 parts (as solid content), 0.15 parts of Rongalit as a reducing agent were charged, the internal temperature was kept at 70 ° C., and cumene hydroperoxide (hereinafter abbreviated as CHP).
A mixed solution of 8 parts of methyl methacrylate added with 0.04 part and 2 parts of ethyl acrylate was continuously added dropwise over 1 hour, and further 1 part was added.
Held for hours. Thereafter, as a second stage, 25 parts of styrene and 0.1 part of CHP were continuously added dropwise over 1 hour, and the mixture was kept for 2 hours. Then, as the third step, 4 parts of methyl methacrylate, 1 part of ethyl acrylate and CHP
A mixed solution of 0.02 part was added dropwise over 15 minutes and kept for 1 hour to complete the polymerization. The obtained latex was coagulated with a 0.2% sulfuric acid aqueous solution, washed with warm water, and dried to obtain a graft copolymer (G-1).

(6) Synthesis of syndiotactic polystyrene. The following was added to the reactor. Styrene 4.5 mol / l Ti (OBu) ₄ 1.4 × 10 ⁻¹ mol / l Methylalumoxane 1.4 × 10 ⁻¹ mol / l Toluene was used as the solvent and the total volume was 5 liters at 50 ° C. Polymerized for 7 hours. After polymerization, the produced polymer is precipitated with methanol, washed with methanol, filtered,
Dried. The polymerization yield was 15%. Next, the produced polymer was extracted with methyl ethyl ketone to obtain 94.2% insoluble portion. This polymer has a weight average molecular weight of 275,0.
00, the number average molecular weight is 56,000, and the melting point is 27.
The syndiotacticity determined by analysis by nuclear magnetic resonance at 0 ° C. was 95%.

(7) Production of thermoplastic resin composition. Graft copolymer (G-1) obtained in the step (5)
And the syndiotactic polystyrene obtained in the previous step (6) were thoroughly mixed at a weight ratio of 25/75 using a mixer, and melt-mixed at 280 ° C. using an extruder with a 25 mmφ vent to form pellets. These pellets were vacuum dried and then injection molded [SAV-60 manufactured by Sanjo Seiki Co., injection pressure 40 kg.
/ Cm ² , mold temperature 60 ° C.], impact resistance and heat resistance of the obtained molded product were measured. The results are shown in the column of Example 1 in Table 1 below. The impact resistance is notched Izod impact according to the standard of ASTM-D-256,
The heat resistance was measured by a Vickers softening temperature based on the VDE method under a load of 5 kg. The weather resistance was evaluated by measuring the Izod impact strength after accelerated exposure treatment with a weatherometer (WE-II type manufactured by Toyo Rika). The surface appearance is a visual evaluation of the molded product after molding or after 400 hours of accelerated exposure. In the table, ◯ is good and X is poor.

Examples 2, 3 and 4 The procedure described in Example 1 above was repeated. However, in the case of this example, the above step (4)
The mixing ratio of the small particle size rubber latex (A-1) and the large particle size rubber latex (A-2) indicated by was changed as shown in Table 1. Table 1 shows the results of measuring the physical properties of each molded product.
Shown in. [Comparative Examples 1, 2, 3, 4, 5, 6] The method described in Example 1 was repeated. However, in the case of this example, the above step (4)
The mixing ratio of the small particle size rubber latex (A-1) and the large particle size rubber latex (A-2) indicated by was changed as shown in Table 1. The results of measuring the physical properties of each molded product are shown in Table 1. In Comparative Example 4, the measurement was performed only with syndiotactic polystyrene. In addition, the graft copolymer (G
-1) Instead of commercially available ABS resin and commercially available MBS
The same evaluations using the resin are shown in the columns of Comparative Examples 5 and 6.

[0031]

[Table 1]

[Examples 5, 6, 7, 8, 9] The method described in Example 1 was repeated. However, in the case of this example, the weight ratio of ethyl acrylate and methacrylic acid was changed as shown in Table 2 in the synthesis of the latex for enlargement (B) in the step (2) of Example 1 above. Table 2 shows the results of measuring the physical properties of each molded product. [Comparative Examples 7, 8, 9, 10] The method described in Example 1 was repeated. However, in the case of this example, the weight ratio of ethyl acrylate and methacrylic acid was changed as shown in Table 2 in the synthesis of the polymer latex for enlargement (B) in the step (2). Table 2 shows the results of measuring the physical properties of each molded product.
In Comparative Example 10, the measurement was performed using only syndiotactic polystyrene.

[0033]

[Table 2]

[Examples 10, 11, 12, 13] (1) Production of Acrylic Rubber Copolymer (A-4) Latex 180 parts of ion-exchanged water substituted with nitrogen was placed in a reaction vessel,
0.3 parts of boric acid, 0.03 parts of anhydrous sodium carbonate, 1.5 parts of potassium oleate, and 0.15 parts of potassium persulfate were dissolved and maintained at 70 ° C., and acrylic acid n- was added while stirring.
Butyl 49.5 parts, 2-ethylhexyl acrylate 4
A mixture of 9.5 parts and 1.0 part of divinylbenzene was added dropwise over 4 hours. After the completion of dropping, the temperature was maintained at 70 ° C. for 2 hours to complete the polymerization. The polymerization rate was 99.1% and the latex pH was 7.1. The average particle size of the latex was 0.09 μm. (2) The rubber latex (A-4) is used in the above-mentioned Example 1.
In the same manner as in step (3) of Example 1 above, an enlarged latex (A-5: average particle size 0.52 μm) was obtained by using the latex for enlargement (B) in step (2) of Example 3 above. ..
Subsequently, the procedure described in steps (4) to (6) of Example 1 was repeated.

The above-mentioned acrylic copolymer rubber latex (A-4) and enlarged latex (A-5) were used in the weight ratios shown in Table 3 to obtain the mechanical properties and heat of the molded article of the thermoplastic resin composition. The physical properties were measured. The results are shown in Table 3. [Comparative Examples 11, 12, 13] The method described in Example 10 was repeated. However, in the case of this example, the weight ratio of the acrylic copolymer rubber latex (A-4) and the enlarged latex (A-5) was changed to the weight ratio shown in Table 3.
Table 3 shows the measurement results of mechanical properties and thermal properties of each molded product.

[0036]

[Table 3]

[Examples 14, 15, 16 and 17] The procedure described in Example 1 was repeated. However, in the case of this example,
60 parts of the mixed rubber latex (A-3) obtained in the step (4) of Example 1 as a solid content and 0.15 part of Rongalit as a reducing agent were charged, and the internal temperature was kept at 70 ° C.
Examples 14, 15, 1 of Table 4 with the addition of 0.15 parts of CHP.
Methyl methacrylate, styrene in the proportions shown in 6, 17
A mixed solution of acrylonitrile and divinylbenzene was continuously added dropwise over 2 hours, and the mixture was maintained for 2 hours to complete the polymerization, coagulate and dry to obtain a graft copolymer. The mechanical properties of the molded articles of each thermoplastic resin composition are shown in Example 1 of Table 4.
It shows in the column of 4-17. [Comparative Examples 14, 15, 16, 17] The method described in Example 14 was repeated. However, in the case of this example, the weight ratio of methyl methacrylate to styrene and acrylonitrile is
The ratio was changed to that shown in Table 4. The mechanical properties of the resulting molded articles of each thermoplastic resin composition are shown in Table 4 below.

[0038]

[Table 4]

[Examples 18, 19, 20, 21] The method described in Example 1 was repeated. However, in the case of this example,
The amount of the mixed rubber latex (A-3) obtained in (4) of Example 1 was changed by weight ratio (solid content) as shown in Table 5, and the process of Example 1 was changed accordingly. (5)
The weight ratio of the grafting formulation in was changed. The mechanical properties of the molded article of the obtained thermoplastic resin composition and the visual appearance of the surface were measured. The results are shown in Table 5. [Comparative Examples 18 and 19] The method described in Example 18 was repeated. However, in the case of this example, the amount of the mixed rubber latex as the solid content was changed as shown in Table 5. The mechanical properties of the molded article of the obtained thermoplastic resin composition and the visual appearance of the surface were measured. The results are shown in Table 5.

[0040]

[Table 5]

[Examples 22 and 23] The procedure described in Example 1 was repeated. However, in the case of this example,
In the step (1) of synthesizing the acrylic rubber latex, allyl methacrylate was adjusted to 0.2 parts and 4.5 parts and evaluated in the same manner. The results are shown in Table 6. [Comparative Examples 20 and 21] The method described in Example 1 was repeated. However, in the case of this example, the step (1) of Example 1 is performed.
In the synthesis of the acrylic rubber latex, allyl methacrylate was set to 0.05 parts and 6 parts and evaluated in the same manner. The results are shown in Table 6.

[0042]

[Table 6]

[0043]

INDUSTRIAL APPLICABILITY The present invention is capable of blending acrylic rubber polymer latex, acrylic monomer, aromatic vinyl monomer and copolymerizable as an impact modifier of syndiotactic polystyrene resin. Was copolymerized in the presence of an acrylic rubber polymer latex containing 50% by weight or more of an acrylic rubber polymer latex having a weight average particle size of 0.2 μm or more as a graft copolymer with a vinyl monomer. By using the graft copolymer, the impact resistance of the syndiotactic polystyrene resin can be remarkably improved. Therefore, the composition of the present invention has not only excellent heat resistance but also excellent impact resistance, and also excellent weather resistance. The surface appearance of the molded product is also excellent.

Claims (1)

[Claims] 1. A polystyrene resin (A) having a syndiotactic structure (A) (97 to 60 parts by weight), an acrylic acid alkyl ester (60 to 99.9% by weight) and a polyfunctional monomer (0.1 to 5% by weight). In the presence of 40 to 90% by weight (in terms of solid content) of an acrylic rubber polymer latex containing 50% by weight or more of an acrylic rubber having a weight average particle size of 0.2 μm or more, the aromatic vinyl monomer 1 ~ 59 wt%, acrylic monomer 1-20 wt%, copolymerizable vinyl monomer 0-20 wt%, and polyfunctional monomer 0
A polystyrene excellent in impact resistance, heat resistance and weather resistance, which comprises 3 to 40 parts by weight of a graft copolymer (B) obtained by graft-polymerizing a monomer or a mixture of monomers of 5% by weight. -Based resin composition.