Polycarbonate-polysiloxane copolymer resin composition with high impact strength at low temperature and mechanical strength and method for preparing the same

1. A polycarbonate-polysiloxane copolymer resin composition with high impact strength at low temperature and high mechanical strength, comprising:

(A) about 100 parts by weight of a thermoplastic polycarbonate resin; and

(B) about 0.1 to about 30 parts by weight of an organo-siloxane polymer having an epoxy group represented by the following Chemical Formula:

wherein:

each R 1 is independently hydrogen, C 1 -C 8 alkyl, C 6 -C 30 aryl, or C 1 -C 15 alkyl-substituted C 6 -C 30 aryl;

R 2 is C 1 -C 8 alkylene;

each p is independently 0 or 1; and

a represents the number of repeating units and is an integer from 1 to 10.

2. The polycarbonate-polysiloxane copolymer resin composition of claim 1 , wherein each of said R 2 of said organic siloxane polymer having an epoxy group (B) is independently hydrogen methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, t-butyl, isobutyl, isoamyl, or t-amyl.

3. The polycarbonate-polysiloxane copolymer resin composition of claim 1 , wherein each of said R 2 of said organic siloxane polymer having an epoxy group (B) is independently methylene, ethylene, propylene, isopropylene, butylene, sec-butylene, or t-butylene.

4. The polycarbonate-polysiloxane copolymer resin composition of claim 1 , wherein said organic siloxane polymer having an epoxy group (B) has a viscosity of about 1 to about 50,000 cSt at 25° C.

5. The polycarbonate-polysiloxane copolymer resin composition of claim 1 , wherein said polycarbonate-polysiloxane copolymer resin composition has an impact strength of about 18 kgf·cm/cm or more at 23° C. and an impact strength of about 15 kgf·cm/cm or more at −30° C., respectively, measured in accordance with ASTM D-256 using a ¼″ thick test sample, a flexural modulus of about 18,000 Kgf/cm 2 or more measured in accordance with ASTM D790 using a ¼″ thick test sample, and a brittle fracture ratio of about 45% or less for a flat plate specimen with dimensions of 2 mm×50 mm×200 mm after exposing the specimen to −30° C. for 48 hours.

6. The polycarbonate-polysiloxane copolymer resin composition of claim 1 , further comprising about 10 or less parts by weight of an impact modifier (C).

7. The polycarbonate-polysiloxane copolymer resin composition of claim 6 , wherein said impact modifier (C) is a core-shell graft copolymer prepared by graft-polymerizing a monomer comprising an aromatic vinyl compound, a vinyl cyanide compound, a C 1 -C 8 alkyl (meth)acrylate ester, maleic anhydride, maleimide, or a combination thereof with a rubber polymer.

8. The polycarbonate-polysiloxane copolymer resin composition of claim 7 , wherein said the core-shell graft copolymer is prepared by graft-polymerizing about 5 to about 95% by weight of at least one monomer comprising styrene, α-methyl styrene, halogen- or C 1 -C 8 alkyl-substituted styrene, C 1 -C 8 alkyl methacrylate ester, C 1 -C 8 alkyl acrylate ester, acrylonitrile, methacrylonitrile, a maleic anhydride, C 1 -C 4 alkyl- or phenyl N-substituted maleimide, or a combination thereof with about 5 to about 95% by weight of a rubber comprising butadiene rubber, acrylic rubber, ethylene/propylene rubber, styrene/butadiene rubber, acrylonitrile/butadiene rubber, isoprene rubber, ethylene propylene diene monomer (EPDM), polyorganosiloxane/polyalkyl(meth)acrylate rubber composite or a combination thereof.

9. The polycarbonate-polysiloxane copolymer resin composition of claim 8 , wherein said polycarbonate-polysiloxane copolymer resin composition has an impact strength of about 75 kgf·cm/cm or more at 23° C. and an impact strength of about 27 kgf·cm/cm or more at −30° C., respectively, measured in accordance with ASTM D-256 using a ¼″ test sample, a flexural modulus of about 18,000 Kgf/cm 2 or more measured in accordance with ASTM D790 using a ¼″ thick test sample, and a brittle fracture ration of about 10% or less for a flat plate specimen with dimensions of 2 mm×50 mm×200 mm after exposing the specimen to −30° C. for 48 hours.

10. The polycarbonate-polysiloxane copolymer resin composition of claim 6 , wherein said impact modifier (C) is an ethylene/alkyl(meth)acrylate copolymer represented by the following Chemical Formula 5:

wherein:

R 7 is hydrogen or methyl;

R 8 is C 1 -C 12 alkyl; and

m and n are degrees of polymerization and the ratio of m to n is about 300:1 to about 10:90.

11. The polycarbonate-polysiloxane copolymer resin composition of claim 6 , further comprising an additive comprising a flame retardant, flame retardant aid, lubricant, releasing agent, nucleating agent, antistatic agent, stabilizer, reinforcing agent, inorganic filler, pigment, dye, or a combination thereof.

12. A molded article produced from the polycarbonate-polysiloxane copolymer resin composition as defined in claim 1 .

13. A method for preparing a polycarbonate-polysiloxane copolymer resin composition comprising:

melt-mixing a thermoplastic polycarbonate resin and an organic siloxane polymer having an epoxy group of Chemical Formula 2,

wherein:

each R 1 is independently hydrogen, C 1 -C 8 alkyl, C 6 -C 30 aryl, or C 1 -C 15 alkyl-substituted C 6 -C 30 aryl;

R 2 is C 1 -C 8 alkylene;

each p is independently 0 or 1; and

a represents the number of repeating units and is an integer from 1 to 10; and

extruding the melt-mixed mixture.