Polycarbonate-polysiloxane copolymer compositions for mobile phone housing applications

1. A polycarbonate composition comprising:

30 to 95 wt % of one or more bisphenol A polycarbonate homopolymers; and

5 to 70 wt % of a poly(carbonate-siloxane) copolymer with a siloxane content of 10 wt. % to 25 wt. % based on the total weight of the poly(carbonate-siloxane), in an amount effective to provide a total siloxane content of 0.5 wt. % to 17.5 wt. % based on the total weight of the composition;

the poly(carbonate-siloxane) copolymer

comprising bisphenol carbonate units of the formula

wherein

R a and R b are each independently C 1-12 alkyl, C 1-12 alkenyl, C 3-8 cycloalkyl, or C 1-12 alkoxy,

p and q are each independently 0 to 4, and

X a is a single bond, —O—, —S—, —S(O)—, —S(O) 2 —, —C(O)—, a C 1-11 alkylidene of formula —C(R c )(R d )— wherein R c and R d are each independently hydrogen or C 1-10 alkyl, or a group of the formula —C(═R e )— wherein R e is a divalent C 1-10 hydrocarbon group; and

siloxane units of the formulas

or a combination comprising at least one of the foregoing, wherein

R is each independently a C 1-13 monovalent hydrocarbon group,

Ar is each independently a C 6-30 aromatic group,

R 2 is each independently a C 2-8 alkylene group, and

E has an average value of 10 to 100;

wherein in the poly(carbonate-siloxane) copolymer less than 0.5 mol % of the siloxane units are directly coupled to another siloxane units; and further

wherein the composition has a tensile yield strength retention of 80% and higher after exposure of an ISO tensile bar for 24 hours to sunscreen under 0.5% strain compared to a non-exposed reference tested according to ISO 22088-3; and

an elongation at break retention of 75% and higher after exposure of an ISO tensile bar for 24 hours to sunscreen under 0.5% strain compared to a non-exposed reference tested according to ISO 22088-3.

2. The composition of claim 1 wherein the composition has a melt volume rate (“MVR”), determined in accordance with ASTM D1238 under a load of 1.2 kg at 300° C., higher than 5 and a ductile/brittle transition temperature of less than or equal to −10° C. determined in accordance with ASTM D256-2010 on a molded part having a thickness of 3.2 mm.

3. The composition of claim 1 further comprising a colorant composition, wherein

a molded sample having a thickness of 1 mm formed from the composition has an average L* value of 29 or less as measure by the CIE Lab method, 10 degree observer, D65 illuminant, specular component included, measured in reflectance mode.

4. The composition of claim 1 , wherein a molded article of the composition has reduced aesthetic defects comprising one or more of the following: black streaking; knitline visibility; gate blush; or pearlescence compared to a molded article of a reference composition having the same siloxane loading, but containing a poly(carbonate-siloxane) copolymer comprising bisphenol A carbonate units and siloxane units wherein greater than 20 mol % of the siloxane units are directly coupled to another siloxane unit.

5. The composition of claim 1 , wherein a molded article of the composition passes a ball drop impact test without failure after dropping a steel ball of 500 g from a height of 500 mm after Non Conductive Vacuum Metallization (NCVM).

6. The composition of claim 1 , wherein a molded article of the composition with a thickness of 3.2 mm thickness has a transmission higher than 50% and a haze less than 25%, measured by HazeGard (ASTM D1003-00).

7. The composition of claim 1 , wherein the bisphenol carbonate units of the poly(carbonate-siloxane) are bisphenol A carbonate units and siloxane units of the poly(carbonate-siloxane) are of the formula

or a combination comprising at least one of the foregoing, wherein E has an average value of 10 to 100.

8. The composition of claim 1 , wherein the poly(carbonate-siloxane) is present in an amount of 10 to 30 wt. % based on the sum of the weights of the bisphenol A polycarbonate homopolymer and the poly(carbonate-siloxane).

9. The composition of claim 3 wherein the colorant composition comprises carbon black in an amount of greater than zero and less than 1.5 wt. % based on the total weight of the colorant composition.

10. The composition of claim 1 , further comprising a filler composition.

11. The compositions of claim 10 , wherein the filler composition comprises TiO 2 .

12. The composition of claim 10 , wherein the filler composition is present in an amount from 1 wt % to 20 wt % based on the total weight of the polycarbonate composition.

13. The composition of claim 1 , further comprising a flame retardant, an anti-drip agent, or a combination comprising at least one of the foregoing, wherein optionally the flame retardant comprising an alkali metal salt of a perfluorinated C 1 -C 16 alkyl sulfonate, an inorganic acid complex salt, or a combination comprising at least one of the foregoing.

14. The composition of claim 1 further comprising no more than 5 wt. % based on the weight of the composition of a processing aid, a heat stabilizer, an antioxidant, an ultra violet light absorber, or a combination comprising at least one of the foregoing.

15. An article selected from a molded article, a thermoformed article, an extruded film, an extruded sheet, a honeycomb structure, one or more layers of a multi-layer article, a substrate for a coated article, and a substrate for a metallized article made from the composition of claim 1 .

16. The article of claim 15 wherein the article is a component of a consumer electronic device selected from a gaming console, a gaming controller, a portable gaming device, a cellular telephone, a television, a personal computer, a tablet computer, a laptop computer, a personal digital assistant, a portable media player, a digital camera, a portable music player, an appliance, a power tool, a robot, a toy, a greeting card, a home entertainment system, and active loudspeaker, or a soundbar,

or the article is an electronic housing for an adapter, a cell phone, a smart phone, a GPS device, a laptop computer, a tablet computer, an e-reader, a copier, or a solar apparatus,

or the article is an electrical junction box, an electrical connector, an electrical vehicle charger, an outdoor electrical enclosure, a smart meter enclosure, a smart grid power node, a photovoltaic frame, a miniature circuit breaker,

or the article is an automotive, scooter, and motorcycle exterior and interior component comprising panels, quarter panels, rocker panels, trim, fenders, battery covers, doors, deck-lids, trunk lids, hoods, bonnets, roofs, bumpers, fascia, grilles, mirror housings, pillar appliqués, cladding, body side moldings, wheel covers, hubcaps, door handles, spoilers, window frames, headlamp bezels, headlamps, tail lamps, tail lamp housings, tail lamp bezels, license plate enclosures, roof racks, and running boards.

17. A method of manufacture of an article, comprising molding, extruding, casting, or shaping the composition of claim 1 to form the article.