Thermoplastic resin composition, method of preparing the same, and molded part manufactured using the same

A method of preparing a thermoplastic resin composition, comprising:

• a step of kneading and extruding A) 20 to 50% by weight of an ASA graft copolymer comprising an acrylic rubber core having an average particle diameter of 0.05 to 1 μm and a shell obtained by polymerizing an aromatic vinyl compound and a vinyl cyanide compound, wherein the core is wrapped with the shell;
• B) 49 to 79% by weight of an aromatic vinyl compound-vinyl cyanide compound copolymer;
• and
• C) 0.01 or more and less than 2% by weight of an epoxy group-containing copolymer having a weight average molecular weight of 2,000 to 8,000 g/mol,
• wherein the epoxy group-containing copolymer is obtained by polymerizing an epoxy group-containing vinyl compound and one or more selected from an aromatic vinyl compound, a vinyl cyanide compound, and an alkyl (meth)acrylate compound,
• wherein the epoxy group-containing copolymer is represented by Formula 2 below:
• wherein R9, R10, R11, R12, R13, R14, R15, and R16 are the same or different from each other and are each independently hydrogen or an alkyl group having 1 to 20 carbon atoms;
• R17 is a bond or an alkylene group having 1 to 20 carbon atoms;
• a is an integer of 60 to 80;
• b is an integer of 10 to 40;
• c is an integer of 1 to 30;
• and n is an integer of 1 to 5.

A molded part manufactured by injection-molding a thermoplastic resin composition comprising:

• A) 20 to 50% by weight of an ASA graft copolymer comprising an acrylic rubber core having an average particle diameter of 0.05 to 1 μm and a shell obtained by polymerizing an aromatic vinyl compound and a vinyl cyanide compound, wherein the core is wrapped with the shell;
• B) 49 to 79% by weight of an aromatic vinyl compound-vinyl cyanide compound copolymer;
• and
• C) 0.01 or more and less than 2% by weight of an epoxy group-containing copolymer having a weight average molecular weight of 2,000 to 8,000 g/mol,
• wherein the epoxy group-containing copolymer is obtained by polymerizing an epoxy group-containing vinyl compound and one or more selected from an aromatic vinyl compound, a vinyl cyanide compound, and an alkyl (meth)acrylate compound, and
• wherein, when gloss is measured at 60° according to ASTM D523, the molded part has a gloss of 25 or less, and, when weather resistance (discoloration degree, ΔE) is measured according to ASTM D4355, the molded part has a weather resistance of 1.5 or less.