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

1. A polycarbonate 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 organic siloxane polymer having a primary amine group, wherein said organic siloxane polymer having a primary amine group (B) is represented by following Chemical Formula 2:

wherein:

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

R 2 is C 1-8 alkylene;

each R 3 is independently hydrogen, C 1-8 alkyl, C 6-30 aryl, or C 1 -C 15 alkyl-substituted C 6-30 aryl;

each p is independently 0 or 1;

k is an integer from 1 to 5; and

m and n are repeating units, wherein the ratio of m to n of said organic siloxane polymer having a primary amine group is about 99.5:0.5 to about 55:45; and

(C) about 0.1 to about 10 parts by weight of an impact modifier.

2. The polycarbonate resin composition of claim 1 , wherein each R 1 is independently methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, t-butyl, isobutyl, isoamyl, or t-amyl, each R 3 is independently hydrogen, methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, t-butyl, isobutyl, isoamyl, or t-amyl, and R 2 is methylene, ethylene, propylene, isopropylene, butylene, sec-butylene, or t-butylene.

3. The polycarbonate resin composition of claim 1 , wherein said polycarbonate resin composition has an impact strength of about 35 kgf·cm/cm or more at 23° C. measured in accordance with ASTM D-256 using a ¼″ thick test sample, an impact strength of about 18 kgf·cm/cm or more at −20° C. and about 15 kgf·cm/cm or more at −30° C. measured in accordance with ASTM D-256 using a ¼″ thick test sample, and a flexural modulus of about 21,000 Kgf/cm 2 or more measured in accordance with ASTM D790 using a ¼″ thick test sample.

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

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

6. The polycarbonate resin composition of claim 5 , wherein said polycarbonate resin composition has an impact strength of about 70 kgf·cm/cm or more at 23° C. measured in accordance with ASTM D-256 using a ¼″ thick test sample, an impact strength of about 55 kgf·cm/cm or more at −20° C. and about 34 kgf·cm/cm or more at −30° C. measured in accordance with ASTM D-256 using a ¼″ thick test sample, and a flexural modulus of about 21,000 Kgf/cm 2 or more measured in accordance with ASTM D790 using a ¼″ thick test sample.

7. The polycarbonate resin composition of claim 1 , wherein said impact modifier (C) comprises an ethylene/alkyl(meth)acrylate copolymer as shown in chemical formula 3:

wherein:

R 4 is hydrogen or methyl;

R 5 is C 1 -C 12 alkyl; and

a and b are the degree of polymerization, and a:b is about 300:1 to about 10:90.

8. The polycarbonate resin composition of claim 1 , further comprising an additive comprising a flame retardant, flame retardant aid, lubricant, releasing agent, nucleating agent, antistatic agent, stabilizer, modifier, inorganic filler, pigment, dye, or a combination thereof.

9. A molded article produced from the polycarbonate resin composition as defined in claim 1 .

10. The polycarbonate resin composition of claim 1 , comprising (C) about 0.1 to about 7 parts by weight of said impact modifier.

11. The polycarbonate resin composition of claim 10 , comprising (C) about 0.5 to about 5.5 parts by weight of said impact modifier.

12. The polycarbonate resin composition of claim 10 , comprising (C) about 0.1 to 1.5 parts by weight of said impact modifier.

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

melt-mixing a thermoplastic polycarbonate resin and an organic siloxane polymer having a primary amine group of Chemical Formula 2;

wherein:

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

R 2 is C 1-8 alkylene;

each R 3 is independently hydrogen, C 1-8 alkyl, C 6-30 aryl, or C 1 -C 15 alkyl-substituted C 6-30 aryl;

each p is independently 0 or 1;

k is an integer of 1 to 5; and

m and n are repeating units and m:n is about 99.9:0.1 to about 50:50; and

extruding the melt-mixed mixture through an extruder.