Flame retardant thermoplastic resin composition having excellent weatherability

1. A flame retardant thermoplastic resin composition comprising:

(A) about 100 parts by weight of a rubber modified aromatic vinyl resin;

(B) about 0.1 to about 10 parts by weight of a ring-shaped alkyl phosphonate ester compound; and

(C) about 0.05 to about 3 parts by weight of a hindered amine light stabilizer (HALS) compound.

2. The flame retardant thermoplastic resin composition of claim 1 , wherein said rubber modified aromatic vinyl resin (A) comprises (a 1 ) about 15 to about 100% by weight of a grafted copolymer resin prepared by graft-polymerizing about 5 to about 65% by weight of a rubbery polymer, about 10 to about 95% by weight of an aromatic vinyl monomer and about 0 to about 40% by weight of a monomer copolymerizable with said aromatic vinyl monomer; and (a 2 ) about 0 to about 85% by weight of a copolymer resin prepared by polymerizing about 40 to about 90% by weight of an aromatic vinyl monomer and about 10 to about 60% by weight of a monomer copolymerizable with said aromatic vinyl monomer.

3. The flame retardant thermoplastic resin composition of claim 2 , wherein said rubbery polymer is a diene rubber, a saturated rubber in which hydrogen is added to said diene rubber, an isoprene rubber, an acrylic rubber, an ethylene-propylene rubber, an ethylene-propylene-diene terpolymer (EPDM) or a combination thereof.

4. The flame retardant thermoplastic resin composition of claim 2 , wherein said aromatic vinyl monomer is styrene, α-methyl styrene, p-methyl styrene or a combination thereof.

5. The flame retardant thermoplastic resin composition of claim 2 , wherein said monomer copolymerizable with the aromatic vinyl monomer is a cyanide vinyl-containing compound, an unsaturated nitrile-containing compound, acrylic acid, methacrylic acid, maleic anhydride, N-substituted maleimide or a combination thereof.

6. The flame retardant thermoplastic resin composition of claim 1 , wherein said rubber modified aromatic vinyl resin (A) is selected from copolymers of acrylonitrile-butadiene-styrene (ABS), copolymers of acrylonitrile-acrylic rubber-styrene (AAS), copolymers of acrylonitrile-ethylenepropylene rubber-styrene (AES), high impact polystyrene resins (HIPS), and combinations thereof.

7. The flame retardant thermoplastic resin composition of claim 1 , wherein said ring-shaped alkyl phosphonate ester compound is represented by the following Formula 1:

wherein R 1 and R 2 are independently of each other C 1 -C 4 alkyl group and x is 0 or 1.

8. The flame retardant thermoplastic resin composition of claim 1 , wherein said HALS compound (C) has a hindered amine structural unit represented by the following Formula 2:

wherein R is hydrogen, C 1 -C 3 alkyl group or acetyl group.

9. The flame retardant thermoplastic resin composition of claim 1 , further comprising about 0.1 to about 10 parts by weight of an aromatic phosphate ester compound based on 100 parts by weight of the rubber modified aromatic vinyl resin.

10. The flame retardant thermoplastic resin composition of claim 9 , wherein said aromatic phosphate ester compound is represented by the following Formula 3:

wherein R 3 , R 4 and R 5 independently of one another are hydrogen or C 1-4 alkyl group; X is C 6-20 aryl group or alkyl-substituted C 6-20 aryl group derived from resorcinol, hydroquinol or bisphenol-A; and n is about 0 to 4.

11. The flame retardant thermoplastic resin composition of claim 1 , further comprising about 0.001 to about 30 parts by weight of at least one additive selected from the group consisting of a heat stabilizer, an anti-oxidant, a light stabilizer, a compatibilizer, a pigment, a dye, and an inorganic filler, and combinations thereof.

12. A molded article comprising a thermoplastic resin composition comprising (A) about 100 parts by weight of a rubber modified aromatic vinyl resin; (B) about 0.1 to about 10 parts by weight of a ring-shaped alkyl phosphonate ester compound; and (C) about 0.05 to about 3 parts by weight of a hindered amine light stabilizer (HALS) compound.

13. The molded article of claim 12 , wherein said article has a flame retardancy of at least V2, measured in accordance with UL94 VB using a test specimen having a thickness of 1/12″ inch and exhibits a color change of 1.0 or less, measured in, accordance with ASTM D 4459 using a 4 cm×5 cm×0.3 cm test specimen exposed for 300 hours.

14. The molded article of claim 13 , wherein said article exhibits a color change of 0.5 or less, measured in accordance with ASTM D 4459 using 4 cm×5 cm×0.3 cm test specimens exposed for 300 hours.

15. The molded article of claim 14 , wherein said article exhibits a color change of 0.23 or less, measured in accordance with ASTM D 4459 using 4 cm×5 cm×0.3 cm test specimens exposed for 300 hours.

16. The molded article of claim 15 , wherein said article exhibits a color change of 0.15 or less, measured in accordance with ASTM D 4459 using 4 cm×5 cm×0.3 cm test specimens exposed for 300 hours.

17. The flame retardant thermoplastic resin composition of claim 1 , wherein:

said ring-shaped alkyl phosphonate ester compound is represented by the following Formula 1:

wherein R 1 and R 2 are independently of each other C 1 -C 4 alkyl group and x is 0 or 1; and

said HALS compound (C) has a hindered amine structural unit represented by the following Formula 2:

wherein R is hydrogen, C 1 -C 3 alkyl group or acetyl group.

18. The flame retardant thermoplastic resin composition of claim 17 , wherein said composition has a flame retardancy of at least V2, measured in accordance with UL94 VB using a test specimen having a thickness of 1/12″ inch and exhibits a color change of 1.0 or less, measured in accordance with ASTM D 4459 using a 4 cm×5 cm×0.3 cm test specimen exposed for 300 hours.

19. The flame retardant thermoplastic resin composition of claim 18 , wherein said composition exhibits a color change of 0.5 or less, measured in accordance with ASTM D 4459 using 4 cm×5 cm×0.3 cm test specimens exposed for 300 hours.

20. The flame retardant thermoplastic resin composition of claim 17 , further comprising about 0.1 to about 10 parts by weight of an aromatic phosphate ester compound based on 100 parts by weight of the rubber modified aromatic vinyl resin, wherein said aromatic phosphate ester compound is represented by the following Formula 3:

wherein R 3 , R 4 and R 5 independently of one another are hydrogen or C 1-4 alkyl group; X is C 6-20 aryl group or alkyl-substituted C 6-20 aryl group derived from resorcinol, hydroquinol or bisphenol-A; and n is about 0 to 4.

21. The molded article of claim 12 , said ring-shaped alkyl phosphonate ester compound is represented by the following Formula 1:

wherein R 1 and R 2 are independently of each other C 1 -C 4 alkyl group and x is 0 or 1; and

said HALS compound (C) has a hindered amine structural unit represented by the following Formula 2:

wherein R is hydrogen, C 1 -C 3 alkyl group or acetyl group.

22. The molded article of claim 21 , wherein said article has a flame retardancy of at least V2, measured in accordance with UL94 VB using a test specimen having a thickness of 1/12″ inch and exhibits a color change of 1.0 or less, measured in accordance with ASTM D 4459 using a 4 cm×5 cm×0.3 cm test specimen exposed for 300 hours.

23. The molded article of claim 22 , wherein said article exhibits a color change of 0.5 or less, measured in accordance with ASTM D 4459 using 4 cm×5 cm×0.3 cm test specimens exposed for 300 hours.