Patent ID: 6660787
Filing Date: 2003-12-09
Classification: C08G,C08K,C08L

Abstract:
A transparent, fire resistant, branched polycarbonate-polysiloxane block copolymer composition comprising:a) polycarbonate blocks having recurring units of the formula: wherein Ra and Rb each represent a monovalent hydrocarbon group and may be the same or different; p and q are each independently integers from 0 to 4; and Xa represents one of the groups of formula: wherein Rc and Rd each independently represent a hydrogen atom or a monovalent linear or cyclic hydrocarbon group and Rc is a divalent hydrocarbon group; b) a repeating or recurring polysiloxane unit derived from the reaction product of an allyl phenol and a polydiorganosiloxane of the formula: wherein R1 and R2 are each independently hydrocarbyl and where D is an integer of from about 5 to about 20; c) a polyfunctional organic branching agent containing at least three functional groups selected from the group consisting of hydroxyl, carboxyl, carboxylic anhydride, carboxylic acid chloride, and mixtures thereof; and d) flame retardant additives; wherein said polysiloxane unit is present in an amount of about 1 wt. % or less, based on the total weight of said branched polycarbonate-polysiloxane block copolymer.