Polyester-flexible polymer block copolymers and mixtures thereof

Abstract

A block copolymer of generally an AB, ABA, or A(BA).sub.n structure, or mixtures thereof where the A block is an unsaturated polyester, the B block is a flexible polymer having a Tg of 0.degree. C. or lower, and n is 2 to 5. The various block components are generally first separately prepared as polymers with the flexible polymer generally having 1 or 2 functional end groups such as an amine group, a carboxyl group, or a hydroxyl group with the later being preferred. Alternatively, for low molecular weight unsaturated polyester blocks, the block can be made in situ. The preferred reaction route is to react a mono or dihydroxy terminated flexible polymer with a diisocyanate which subsequently can be readily reacted with the polyester. The block copolymers can be utilized as toughening agents. They furthermore can be utilized to coat a fiber structure such as individual fibers, a woven structure, or a nonwoven structure such as mats, rovings, bundles, and the like, with the coated fiber structures subsequently incorporated into a polymeric matrix such as polyester.