Patent ID: 7851560

Claim:
A composition consisting essentially of, based on the total weight of polymer components in the composition: about 3 to about 15 wt % of a polysiloxane polycarbonate block copolymer comprising repeating structural units of formula (I) wherein at least 60 percent of the total number of R 1 groups are aromatic organic radicals and the balance thereof are aliphatic, alicyclic, or aromatic radicals, and repeating structural units of formula (IV) in an amount of about 1 to about 10 wt % based on total weight of the block copolymer wherein R 2 is independently at each occurrence a monovalent organic radical having 1 to 13 carbon atoms, R 3 is a divalent aliphatic radical having 1 to 8 carbon atoms or an aromatic radical having 6 to 8 carbon atoms, R 4 is independently at each occurrence a hydrogen, halogen, alkoxy having 1 to 8 carbon atoms, alkyl having 1 to 8 carbon atoms, or aryl having 6 to 13 carbon atoms; and wherein n is an integer that is less than or equal to 1,000; about 33 to about 77 wt % of a cycloaliphatic polyester having repeating units of formula (VI) wherein R 7 and R 8 are independently at each occurrence a divalent aromatic, aliphatic or cycloaliphatic group having 2 to 20 carbon atoms, with the proviso that at least one of R 7 and R 8 is a cycloaliphatic group-containing radical; and about 17 to about 65 wt % of a polycarbonate that is different from the polycarbonate block copolymer, having a weight average molecular weight of less than about 20,000 Daltons, and that comprises repeating structural units of formula (XVIII) wherein at least 60 percent of the total number of R 9 groups are aromatic organic radicals and the balance thereof are aliphatic, alicyclic, or aromatic radicals; and further wherein the composition has a melt volume rate of about 20 to about 40 cc/10 minutes, measured in accordance with ISO 1133 at 265° C. and 2.16 kg; and wherein the polycarbonate of the composition retains at least about 10% more of its initial molecular weight after aging for 28 days at 80° C., 80% relative humidity, compared to a composition without the polysiloxane polycarbonate block copolymer and wherein a sample molded from the composition is transparent and has a thickness of 3.2 mm has a Notched Izod impact strength of about 800 to about 1600 J/m, measured in accordance with ASTM D-256 at 23° C.