Color and heat stable polycarbonate compositions and methods of making
View Patent ↗Provided herein are branched polycarbonate resin compositions The compositions include a first heat stabilizer, a second heat stabilizer, a branched polycarbonate, a cyclic siloxane, and a flame retardant salt. The compositions withstand discoloration and increased melt viscosity when exposed to elevated temperatures. These compositions are useful in the manufacture of various shaped, formed and/or molded articles.
1. A polycarbonate resin composition comprising
47-50 wt % of a first branched polycarbonate that is a bisphenol-A polycarbonate resin having a carbonate end-capping group derived from p-hydroxybenzonitrile (HBN) and branching derived from tris-(hydroxyphenyl)ethane (THPE) as a branching agent;
22-28 wt % of a second branched polycarbonate that is a bisphenol-A polycarbonate resin having branching derived from tris-(hydroxyphenyl)ethane (THPE) as a branching agent;
21-31 wt % of a high flow polycarbonate that is a bisphenol-A polycarbonate homopolymer having a melt volume flow rate (MVR) of between 21.9 and 31.8 cm 3 /10 min, and a low flow polycarbonate that is a bisphenol-A polycarbonate homopolymer having a melt volume flow rate (MVR) of between 5 and 7 cm 3 /10 min;
0.014-0.016 wt % of a first heat stabilizer that is tris(2,4-di-t-butylphenyl)phosphite;
0.016-0.017 wt % of a second heat stabilizer that is bis(2,4-dicumylphenyl)pentaerythritol diphosphite;
a cyclic siloxane;
a flame retardant salt; and
0.047-0.05 wt % of a hindered phenol heat stabilizer.
2. The resin composition of claim 1 , wherein the cyclic siloxane is at least one of the following: octaphenylcyclotetrasiloxane, hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecmethylcyclohexasiloxane, trimethyltriphenylcyclotrisiloxane, and/or tetramethyltetraphenylcyclotetrasiloxane.
3. The resin composition of claim 1 , wherein the cyclic siloxane is octaphenylcyclotetrasiloxane.
4. The resin composition of claim 1 , comprising 0.05-0.1 wt % of the cyclic siloxane.
5. The resin composition of claim 1 , wherein the flame retardant salt is at least one of the following: alkali metal salt of perfluorinated C 1 -C 16 alkyl sufonates; potassium perfluorobutane sulfonate; potassium perfluoroctane sulfonate; tetraethylammonium perfluorohexane sulfonate; sodium toluene sulfonate; sodium diphenylsulfone sulfonate; and potassium diphenylsulfone sulfonate.
6. The resin composition of claim 1 , wherein the flame retardant salt is potassium perfluorobutane sulfonate.
7. The resin composition of claim 1 , comprising 0.05-0.1 wt % of the flame retardant salt.
8. The resin composition of claim 1 , wherein the cyclic siloxane is octaphenylcyclotetrasiloxane that is present in the composition at 0.05-0.1 wt %, and the flame retardant salt is potassium perfluorobutane sulfonate that is present in the composition at 0.05-0.1 wt %.
9. The resin composition of claim 1 , wherein the hindered phenol heat stabilizer is octadecyl-3(3,5-ditertbutyl-4-hydroxyphenyl)propionate.
10. The resin composition of claim 1 , further comprising a release agent.
11. The resin composition of claim 1 , further comprising a UV additive.
12. The resin composition of claim 1 , further comprising a linear siloxane having the formula:
wherein R 23 is a C 1 -C 18 alkyl group, R 24 is a phenyl, and x 1 and y 1 sum to 1.
13. The resin composition of claim 1 , wherein the resin composition has a viscosity of at least 500 Poise at 300° C.
14. The resin composition of claim 1 , wherein the resin composition has a viscosity build of no greater than 20% after 30 minutes at 300° C.
15. The resin composition of claim 1 , wherein the resin composition has a viscosity build of no greater than 15% after 30 minutes at 300° C.
16. The resin composition of claim 1 , wherein the resin composition has a viscosity build of no greater than 10% after 30 minutes at 300° C.
17. The resin composition of claim 1 , wherein a 3.2 mm thick article formed from the composition has a yellowing index (Yi) of less than 3.
18. The polycarbonate resin composition of claim 1 , wherein a 3.2 mm thick article formed from the composition has a yellowing index (Yi) of less than 2.5.
19. A polycarbonate resin composition, selected from the group consisting of (a)-(c):
(a) a polycarbonate resin composition comprising: 47 wt % of first branched polycarbonate that is a bisphenol-A polycarbonate resin having a carbonate end-capping group derived from p-hydroxybenzonitrile (HBN) and branching derived from tris-(hydroxyphenyl)ethane (THPE) as a branching agent; 22 wt % of a second branched polycarbonate that is a bisphenol-A polycarbonate resin having branching derived from tris-(hydroxyphenyl)ethane (THPE) as a branching agent; 29 wt % of a high flow polycarbonate that is a bisphenol-A polycarbonate homopolymer having a melt volume flow rate (MVR) of between 21.9 and 31.8 cm 3 /10 min; 2 wt % of a low flow polycarbonate that is a bisphenol-A polycarbonate homopolymer having a melt volume flow rate (MVR) of between 5 and 7 cm 3 /10 min; 0.014 wt % of a first heat stabilizer that is tris(2,4-di-t-butylphenyl)phosphite; 0.017 wt % of a second heat stabilizer that is bis(2,4-dicumylphenyl)pentaerythritol diphosphite; 0.1 wt % of a cyclic siloxane; 0.08 wt % of a flame retardant salt; and 0.05 wt % of a hindered phenol heat stabilizer;
(b) a polycarbonate resin composition comprising: 50 wt % of first branched polycarbonate that is a bisphenol-A polycarbonate resin having a carbonate end-capping group derived from p-hydroxybenzonitrile (HBN) and branching derived from tris-(hydroxyphenyl)ethane (THPE) as a branching agent; 28 wt % of a second branched polycarbonate that is a bisphenol-A polycarbonate resin having branching derived from tris-(hydroxyphenyl)ethane (THPE) as a branching agent; 2 wt % of a high flow polycarbonate that is a bisphenol-A polycarbonate homopolymer having a melt volume flow rate (MVR) of between 21.9 and 31.8 cm 3 /10 min; 19 wt % of a low flow polycarbonate that is a bisphenol-A polycarbonate homopolymer having a melt volume flow rate (MVR) of between 5 and 7 cm 3 /10 min; 0.014 wt % of a first heat stabilizer that is tris(2,4-di-t-butylphenyl)phosphite; 0.017 wt % of a second heat stabilizer that is bis(2,4-dicumylphenyl)pentaerythritol diphosphite; 0.1 wt % of a cyclic siloxane; 0.08 wt % of a flame retardant salt; and 0.05 wt % of a hindered phenol heat stabilizer; and
(c) a polycarbonate resin composition comprising: 50 wt % of first branched polycarbonate that is a bisphenol-A polycarbonate resin having a carbonate end-capping group derived from p-hydroxybenzonitrile (HBN) and branching derived from tris-(hydroxyphenyl)ethane (THPE) as a branching agent; 28 wt % of a second branched polycarbonate that is a bisphenol-A polycarbonate resin having branching derived from tris-(hydroxyphenyl)ethane (THPE) as a branching agent; 2 wt % of a high flow polycarbonate that is a bisphenol-A polycarbonate homopolymer having a melt volume flow rate (MVR) of between 21.9 and 31.8 cm 3 /10 min; 19 wt % of a low flow polycarbonate that is a bisphenol-A polycarbonate homopolymer having a melt volume flow rate (MVR) of between 5 and 7 cm 3 /10 min; 0.016 wt % of a first heat stabilizer that is tris(2,4-di-t-butylphenyl)phosphite; 0.016 wt % of a second heat stabilizer that is bis(2,4-dicumylphenyl)pentaerythritol diphosphite; 0.1 wt % of a cyclic siloxane; 0.08 wt % of a flame retardant salt; and 0.047 wt % of a hindered phenol heat stabilizer.
20. The polycarbonate composition of claim 19 , further comprising 0.4 wt % of a linear siloxane additive.
21. The polycarbonate composition of claim 19 , further comprising 0.27 wt % of a UV additive.
22. The polycarbonate composition of claim 19 , further comprising 0.27 wt % of a release agent.