Transparent thermoplastic resin composition and article molded thereof

A method of producing a transparent thermoplastic resin composition comprising:

• obtaining a graft copolymer (A) by graft-copolymerizing a monomer mixture (a) containing at least an aromatic vinyl-based monomer (a1) and a (meth)acrylic acid ester-based monomer (a2) in the presence of a rubbery polymer (r);
• obtaining a vinyl-based copolymer (B) by copolymerizing a monomer mixture (b) containing at least an aromatic vinyl-based monomer (b1), a (meth)acrylic acid ester-based monomer (b2), and a vinyl cyanide-based monomer (b3);
• and
• mixing at least said graft copolymer (A), said vinyl-based copolymer (B), and a polydimethyl siloxane gum (C) having a weight-average molecular weight of 300,000 or more;
• wherein said transparent thermoplastic resin composition contains:
• 100 parts by mass of a transparent thermoplastic resin composition composed of 10 to 60 parts by mass of said graft copolymer (A) and 40 to 90 parts by mass of said vinyl-based copolymer (B);
• and
• 15 ppm or more and 40 ppm or less of said polydimethyl siloxane gum (C).

A method of producing a transparent thermoplastic resin composition, comprising:

• obtaining a polydimethyl siloxane gum (C)-containing graft copolymer (A′) by graft-copolymerizing a monomer mixture (a) containing at least an aromatic vinyl-based monomer (a1) and a (meth)acrylic acid ester-based monomer (a2) in the presence of a rubbery polymer (r) and a polydimethyl siloxane gum (C) having a weight-average molecular weight of 300,000 or more;
• obtaining a vinyl-based copolymer (B) by copolymerizing a monomer mixture (b) containing at least an aromatic vinyl-based monomer (b1), a (meth)acrylic acid ester-based monomer (b2), and a vinyl cyanide-based monomer (b3);
• and
• mixing at least said polydimethyl siloxane gum (C)-containing graft copolymer (A′) and said vinyl-based copolymer (B);
• wherein said transparent thermoplastic resin composition includes 15 ppm or more and 40 ppm or less of said polydimethyl siloxane gum (C) with respect to 100 parts by mass of a transparent thermoplastic resin composition composed of 10 to 60 parts by mass of said graft copolymer (A) contained in said polydimethyl siloxane gum (C)-containing graft copolymer (A′) and 40 to 90 parts by mass of said vinyl-based copolymer (B).