Light-Colored Polycarbonate Compositions and Methods
A composition containing a bulk polycarbonate-containing resin component; a polycarbonate-siloxane copolymer in an amount sufficient to provide an amount of siloxane of at least 3% by weight of the total composition; and a colorant composition comprising titanium dioxide having an organic coating, for example a coating comprising a polysiloxane, in which the amount of titanium dioxide is from 1 to 2.5 %, preferably 1 to 2.0% and more preferably 1 to 1.5% by weight of the total composition has both light color and good flame-retardance. The composition can be used to prepare shaped article s, particularly those with thin wall region that achieve a V0 UL fire rating at the first thickness.
1 . A composition comprising:
(a) a bulk resin component comprising a polycarbonate resin;
(b) a polycarbonate-siloxane copolymer in an amount sufficient to provide an amount of siloxane of at least 3% by weight of the total composition; and
(c) a colorant composition comprising titanium dioxide having an organic coating, wherein the amount of titanium dioxide is from 1 to 2.5% by weight of the total composition.
2 . The composition of claim 1 , wherein the bulk resin component makes up at least 50% of the composition.
3 . The composition of claim 2 , wherein the amount of titanium dioxide is from 1 to 1.5% by weight of the total composition.
4 . The composition of claim 3 , further comprising a rubbery impact modifier.
5 . The composition of claim 4 , wherein the rubbery impact modifier is selected from the group consisting of acrylic rubbers, ASA rubbers, diene rubbers, organosiloxane rubbers, EPDM rubbers, styrene-butadiene-styrene (SBS) or styrene-ethylene-butadiene-styrene (SEBS) rubbers, ABS rubbers, MBS rubbers and glycidyl ester impact modifiers, and mixtures thereof.
6 . The composition of claim 5 , wherein the rubbery impact modifier is present in an amount of from 1 to 30% by weight.
7 . The composition of claim 6 , further comprising an antidrip agent.
8 . The composition of claim 7 , wherein the antidrip agent is styrene-acrylonitrile copolymer encapsulated polytetrafluoroethylene.
9 . The composition of claim 8 , further comprising an effective flame-retarding amount of flame retardant.
10 . The composition of claim 9 , wherein the flame retardant is a phosphate flame retardant.
11 . The composition of claim 10 , wherein the phosphate flame retardant is bis-phenol A tetraphenyl diphosphate.
12 . The composition of claim 9 , wherein the flame retardant is a sulfonate.
13 . The composition of claim 12 , wherein the sulfonate is a perfluoroalkane sulfonate.
14 . The composition of claim 13 , wherein the perfluoroalkane sulfonate is potassium perfluorobutane sulfonate.
15 . The composition of claim 3 , wherein the organic coating comprises an organosiloxane.
16 . The composition of claim 15 , wherein the amount of titanium dioxide is from 1 to 1.5% by weight of the total composition.
17 . The composition of claim 16 , further comprising an effective flame-retarding amount of flame retardant.
18 . The composition of claim 17 , wherein the flame retardant is a phosphate flame retardant.
19 . The composition of claim 18 , wherein the phosphate flame retardant is bis-phenol A tetraphenyl diphosphate.
20 . The composition of claim 17 , wherein the flame retardant is a sulfonate.
21 . The composition of claim 20 , wherein the sulfonate if a perfluoroalkane sulfonate.
22 . The composition of claim 21 , wherein the perfluoroalkane sulfonate is potassium perfluorobutane sulfonate.
23 . The composition of claim 15 , wherein the organic coating comprises a trimethylolpropanol.
24 . The composition of claim 23 , wherein the bulk component further comprises a rubbery impact modifier.
25 . The composition of claim 24 , wherein the rubbery impact modifier is selected from the group consisting of acrylic rubbers, ASA rubbers, diene rubbers, organosiloxane rubbers, EPDM rubbers, styrene-butadiene-styrene (SBS) or styrene-ethylene-butadiene-styrene (SEBS) rubbers, ABS rubbers, MBS rubbers and glycidyl ester impact modifiers, and mixtures thereof.
26 . The composition of claim 23 , further comprising an effective flame-retarding amount of flame retardant.
27 . The composition of claim 2 , wherein the organic coating comprises trimethylolpropanol.
28 . The composition of claim 27 , wherein the amount of titanium dioxide is from 1 to 1.5% by weight of the total composition.
29 . The composition of claim 2 , wherein the bulk component further comprises an engineering thermoplastic.
30 . The composition of claim 29 , wherein the engineering thermoplastic is a styrene acrylonitrile copolymer or polymethyl(methacrylate).
31 . An article, having a wall thickness greater than a first thickness, said article being formed from a molding composition comprising:
(a) a bulk resin component comprising a polycarbonate resin;
(b) a polycarbonate-siloxane copolymer; and
(c) a colorant composition comprising titanium dioxide, wherein the titanium dioxide has an organic coating, and the amount of polycarbonate-siloxane copolymer is selected such that molding composition achieves a V0 UL fire rating at the first thickness.
32 . The article of claim 31 , wherein the bulk resin component makes up at least 50% of the molding composition.
33 . The article of claim 32 , wherein the first thickness is 1.6 mm, and the polycarbonate-siloxane copolymer is present in an amount sufficient to provide an amount of siloxane of at least 3% by weight of the total composition.
34 . The article of claim 32 , wherein the organic coating comprises an organosiloxane.
35 . The article of claim 34 , wherein the amount of titanium dioxide is from 1 to 1.5% by weight of the total composition.
36 . The article of claim 35 , further comprising an effective flame-retarding amount of flame retardant.
37 . The article of claim 36 , wherein the flame retardant is a phosphate flame retardant.
38 . The article of claim 37 , wherein the phosphate flame retardant is bis-phenol A tetraphenyl diphosphate.
39 . The article of claim 36 , wherein the flame retardant is a sulfonate.
40 . The article of claim 39 , wherein the sulfonate if a perfluoroalkane sulfonate.
41 . The article of claim 40 , wherein the perfluoroalkane sulfonate is potassium perfluorobutane sulfonate.
42 . The article of claim 34 , wherein the organic coating comprises trimethylolpropanol.
43 . The article of claim 42 , wherein the bulk component further comprises a rubbery impact modifier.
44 . The article of claim 43 , wherein the rubbery impact modifier is selected from the group consisting of acrylic rubbers, ASA rubbers, diene rubbers, organosiloxane rubbers, EPDM rubbers, styrene-butadiene-styrene (SBS) or styrene-ethylene-butadiene-styrene (SEBS) rubbers, ABS rubbers, MBS rubbers and glycidyl ester impact modifiers, and mixtures thereof.
45 . The article of claim 42 , further comprising an effective flame-retarding amount of flame retardant.
46 . The article of claim 32 , wherein the organic coating comprises trimethylolpropanol.
47 . The article of claim 46 , wherein the first thickness is 1.6 mm, and the polycarbonate-siloxane copolymer is present in an amount sufficient to provide an amount of siloxane of at least 3% by weight of the total composition.
48 . A method for forming a light colored, flame retardant polycarbonate article comprising the steps of forming a blend comprising:
(a) a bulk resin component comprising a polycarbonate resin;
(b) a polycarbonate-siloxane copolymer in an amount sufficient to provide an amount of siloxane of at least 3% by weight of the total composition; and
(c) a colorant composition comprising titanium dioxide having an organic coating comprising an organic polysiloxane, trimethylolpropanol, or mixtures thereof, wherein the amount of titanium dioxide is from 1 to 2.0% by weight of the total composition; and
forming an article from the blend.
49 . The method of claim 48 , wherein the bulk resin component makes up at least 50% of the blend.
50 . The method of claim 49 , wherein the amount of titanium dioxide is from 1 to 1.5% by weight of the total composition.
51 . The method of claim 49 , wherein the bulk component further comprises a rubbery impact modifier selected from the group consisting of acrylic rubbers, ASA rubbers, diene rubbers, organosiloxane rubbers, EPDM rubbers, styrene-butadiene-styrene (SBS) or styrene-ethylene-butadiene-styrene (SEBS) rubbers, ABS rubbers, MBS rubbers and glycidyl ester impact modifiers, and mixtures thereof.
52 . The method of claim 51 , wherein the rubbery impact modifier is present in an amount of from 1 to 30% by weight.
53 . The method of claim 49 , further comprising an effective flame-retarding amount of flame retardant.
54 . The method of claim 53 , wherein the flame retardant is a phosphate flame retardant.
55 . The method of claim 54 , wherein the phosphate flame retardant is bis-phenol A tetraphenyl diphosphate.
56 . The method of claim 49 , wherein the flame retardant is a sulfonate.
57 . The method of claim 56 , wherein the sulfonate if a perfluoroalkane sulfonate.
58 . The method of claim 57 , wherein the perfluoroalkane sulfonate is potassium perfluorobutane sulfonate.
59 . The method of claim 49 , wherein the bulk component further comprises an engineering thermoplastic.
60 . The method of claim 59 , wherein the engineering thermoplastic is a styrene acrylonitrile copolymer or polymethyl(methacrylate).
61 . A method for enhancing the flame retardance of a light colored composition comprising a bulk resin component comprising polycarbonate; a polycarbonate-siloxane copolymer; and a colorant composition comprising titanium dioxide, said method comprising the steps of
(b) a polycarbonate-siloxane copolymer; and
(b) selecting as the titanium dioxide a titanium dioxide having an organic coating comprising a polyorganosiloxane, trimethylolpropanol, or mixtures thereof, wherein the amount of polycarbonate-siloxane copolymer is sufficient to provide an amount of siloxane of at least 3% by weight of the total composition.