Shaped composition of polymer and surface modifying block copolymer additive and method

Claim 1

A process for preparing a shaped polymeric composition of a base polymer and a block copolymer additive to which the block copolymer additive imparts the desired surface characteristics of significantly decreased wettability and friction without undesirably altering the bulk properties of the base polymer to a significant extent, said block copolymer additive being comprised of a first polymerized comonomer and a second polymerized comonomer, said first polymerized comonomer having an average block length of at least three monomer units and being sufficiently compatible with and miscible in the base polymer to make said additive stable therein, and said second polymerized comonomer having an average block length of at least five monomer units and being sufficiently surface-active in the composition to provide the desired surface characteristics which consists of blending said base polymer and said block copolymer additive to produce a substantially uniform distribution of the additive in the polymer and to permit migration of the additive to the composition surface, and shaping said composition, said base polymer being a polycarbonate of bisphenol-A and said additive being a polycarbonate of bisphenol-A-polydimethylsiloxane block copolymer, said additive being present in an amount ranging from about 0.1 to about 5 percent by weight of said base polymer.