PBT Molding compositions containing mica and a composite polymer

Claim 1

Polyester molding composition consisting essentially of at least about 40 wt% poly (C 2 -C 4 alkylene terephthalate) with at least about 50 wt% of such poly (C 2 -C 4 alkylene terephthalate) being polybutylene terephthalate having an intrinsic viscosity between about 0.5 and about 2.0 dl/g, such composition containing: (a) between about 1 and about 40 wt% based on total molding composition of phlogophite mica flakes having an average particle size between about 40 and 325 mesh with at least 90% of all mica flakes present in the composition having particle sizes between about 40 and about 200 mesh; and (b) between about 5 and about 30 wt% based on total molding composition of a multiphase composite polymer comprising; (1) about 25 to about 95 wt% of a first elastomeric phase polymerized from a monomer system comprising about 75 to 99.8% by weight C 1 to C 6 alkyl acrylate, 0.1 to 5% by weight crosslinking monomer, and 0.1 to 5% by weight graftlinking monomer, said crosslinking monomer being a polyethylenically unsaturated monomer having a plurality of addition polymerizable reactive groups all of which polymerize at substantially the same rate of reaction, and said graftlinking monomer being a polyethylenically unsaturated monomer having a plurality of addition polymerizable reactive groups, at least one of which polymerizes at a substantially different rate of polymerization from at least one other of said reactive groups; and (2) about 75 to 5 wt% of a final, rigid thermoplastic phase polymerized in the presence of said elastomeric phase.