CLAIMS: [Claim 1]
A thermoplastic resin composition which is a thermoplastic resin composition produced by blending 40 to 90 parts by weight of a vinyl copolymer (A) prepared by copolymerization of a vinyl monomer mixture (a) comprising at least 5 to 40% by weight of an aromatic vinyl monomer (al), 30 to 80% by weight of an unsaturated alkyl carboxylate ester monomer (a2) , and 10 to 50% by weight of a cyanated vinyl monomer (a3) and 10 to 6 0 parts by weight of a graft copolymer (B) prepared by graft copolymerization of a vinyl monomer mixture (b) comprising at least 10 to 30% by weight of an aromatic vinyl monomer (bl), 30 to 80% by weight of an unsaturated alkyl carboxylate ester monomer (b2), and 1 to 10% by weight of a cyanated vinyl monomer (b3) in the presence of a rubbery polymer (r) ; wherein acetone-soluble content (C) of the thermoplastic resin composition has a number average molecular weight of 65,000 to 90,000. [Claim 2]
A thermoplastic resin composition according to claim 1 wherein the acetone-soluble content (C) of the thermoplastic resin composition has an acrylonitrile content of 8 to 50% by weight, and acetone-insoluble content (D) of the thermoplastic resin composition has an acrylonitrile content of 1 to 5% by weight. [Claim 3]
A thermoplastic resin composition according to claim 1 or 2 wherein the acetone-soluble content (C) of the thermoplastic resin composition has a dispersity of 2 . 0 to 2 . 5, and the acetone-soluble content (C) of the thermoplastic resin composition has a content of the component having a molecular weight: of at least 250,000 of 15 to 30% by weight and content

of the component having a molecular weight of less than 50,000 of less than 30% by weight. [Claim 4]
A thermoplastic resin composition according to any one of claims 1 to 3 wherein the vinyl copolymer (A) has a number average molecular weight of 80,000 to 100,000. [Claim 5]
A thermoplastic resin composition according to any one of claim 1 to 4 wherein the vinyl copolymer (A) has a dispersity of up to 2.0. [Claim 6]
A thermoplastic resin composition according to any one of claims 1 to 5 wherein acetone-soluble content of the graft copolymer (B) has a number average molecular weight of 30,000 to 50,000. [Claim 7]
A thermoplastic resin composition according to any one of claims 1 to 6 wherein the acetone-soluble content of the graft copolymer (B) has a dispersity of 2.0 to 2.5. [Claim 8]
A method for producing a thermoplastic resin composition having an acetone-soluble content (C) with a number average molecular weight of 65,000 to 90,000 comprising the steps of: conducting copolymerization of a vinyl monomer mixture (a) comprising 5 to 40% by weight of an aromatic vinyl monomer (al) , 30 to 80% by weight of an unsaturated alkyl carboxylate ester monomer (a2 ) , and 10 to 50% by weight of a cyanated vinyl monomer (a3) to produce a vinyl copolymer (A); conducting graft copolymerization of a vinyl monomer mixture (b) comprising at least 10 to 30% by weight of an aromatic vinyl monomer (bl), 30 to 80% by weight of an unsaturated alkyl carboxylate ester monomer fb2) , and 1 to 10% by weight of a cyanated vinyl monomer

(b3) in the presence of a rubbery polymer (r) to produce a graft copolymer (B); and blending at least 40 to 90 parts by weight of the vinyl copolymer (A) and 10 to 60 parts by weight of the graft copolymer (B).
[Claim 9]
A molded article comprising the thermoplastic resin composition according to any one of claims.