Patent ID: 7709581

Claim:
A thermoplastic composition comprising: a polycarbonate or copolycarbonate comprising: 25 to 100 mole percent of a first carbonate unit derived from a dihydroxy aromatic compound having the formula wherein R a′ and R b′ are each independently C 1-12 alkyl, T is a C 5-16 cycloalkylene, a C 5-16 cycloalkylidene, a C 1-5 alkylene, a C 1-5 alkylidene, a arylene, a C 7-12 arylalkylene, C 7-12 arylalkylidene, a C 7-12 alkylarylene, or a arylenealkyl, and r and s are each independently 1 to 4; and 0 to 75 mole percent of a second carbonate unit derived from a dihydroxy aromatic compound, wherein the first carbonate unit and second carbonate unit are not identical, and wherein the mole percentages of each of the first carbonate unit and the second carbonate unit are based on the total number of moles of first carbonate unit and second carbonate unit; a polysiloxane-polycarbonate copolymer comprising 0.15 to 30 weight percent of a polysiloxane block comprising siloxane units of the formula wherein E is on average 4 to 60 units, and each occurrence of R is the same or different and is a C 1-13 monovalent organic group, and 70 to 99.85 weight percent of a third carbonate unit derived from a dihydroxy aromatic compound, wherein the weight percentages of each of the polysiloxane block and the third carbonate unit are based on the total weight of polysiloxane block and third carbonate unit, and a trans-esterification catalyst present in an amount of 20 to 500 parts per million based on weight, and wherein the trans-esterification catalyst is a tetraalkylphosphonium salt or a tetraalkylammonium salt, wherein an article having a thickness of 3.2 mm and molded from the thermoplastic composition has a Dynatup total energy greater than 50 Joules, as measured at a constant speed of 3.3 to 3.6 m/min at 23° C. according to ASTM D3763-02.