Graft copolymer, production method therefor, resin composition, and molded article

1. A method of producing a graft copolymer, comprising polymerizing a vinyl monomer (B) containing a polyfunctional vinyl monomer (b1) in the presence of a polyorganosiloxane rubber (A) comprising more than 20% by mass of a toluene-insoluble matter,

wherein a mass percentage of the polyfunctional vinyl monomer (b1) is 11 to 19% by mass based on 100% by mass of a total amount of the polyorganosiloxane rubber (A) and the vinyl monomer (B).

2. The method of producing a graft copolymer according to claim 1 , wherein the polyfunctional vinyl monomer (b1) is allyl methacrylate.

3. The method of producing a graft copolymer according to claim 1 , wherein the mass percentage of the polyfunctional vinyl monomer (b1) is 13 to 17% by mass based on 100% by mass of the total amount of the polyorganosiloxane rubber (A) and the vinyl monomer (B).

4. A graft copolymer obtained by the production method according to claim 1 .

5. A resin composition comprising 100 parts by mass of a resin and 0.5 to 20 parts by mass of the graft copolymer according to claim 4 .

6. The resin composition according to claim 5 , wherein the resin is polycarbonate.

7. A molded article obtained by molding the resin composition according to claim 5 .

8. The molded article according to claim 7 , wherein the molded article is a casing for home appliances.

9. The molded article of claim 7 , wherein a total burning time of the molded article having a thickness of 1.6 mm in a UL94V test is 40 s or less.

10. The graft copolymer according to claim 4 , wherein when 5 parts by mass of the graft copolymer is blended with 100 parts by mass of a polycarbonate having a viscosity average molecular weight of 22000, 0.3 parts by mass of a phenol antioxidant represented by the following formula (1), 0.3 parts by mass of a phosphorus antioxidant represented by the following formula (2), and 0.5 parts by mass of a polytetrafluoroethylene having a mass average molecular weight of 8000000 to 15000000,

(1) Charpy impact strength at −30° C. is 20 kJ/m 2 or more, and

(2) a total burning time of a molded article having a thickness of 1.6 mm in a UL94V test is 40 s or less:

11. The graft copolymer according to claim 10 , wherein

(3) a deflection temperature under load at a load of 1.8 MPa is 118° C. or more.

12. A resin composition comprising 100 parts by mass of a resin and 0.5 to 20 parts by mass of the graft copolymer according to claim 10 .

13. The resin composition according to claim 12 , wherein the resin is polycarbonate.

14. A molded article obtained by molding the resin composition according to claim 12 .

15. The molded article according to claim 14 , wherein the molded article is a casing for home appliances.

16. The graft copolymer of claim 4 , having a Charpy impact strength at −30° C. is 20 kJ/m 2 or more.

17. The method of claim 1 , wherein the graft copolymer has a Charpy impact strength at −30° C. is 20 kJ/m 2 or more.

18. A method of increasing heat resistance and impact resistance in a graft copolymer, the method comprising:

polymerizing a vinyl monomer (B) containing a polyfunctional vinyl monomer (b1) in the presence of a polyorganosiloxane rubber (A) comprising more than 20% by mass of a toluene-insoluble matter,

wherein a mass percentage of the polyfunctional vinyl monomer (b1) is 11 to 19% by mass based on 100% by mass of a total amount of the polyorganosiloxane rubber (A) and the vinyl monomer (B), thereby providing increased heat resistance and impact resistance at −30° C., with respect to heat resistance and impact resistance of a graft copolymer wherein a mass percentage of the polyfunctional vinyl monomer (b1) is 10% by mass.