Polyester film composites

Abstract

A polyester film composite has a primary layer comprising an oriented layer of a first linear polyester and a heat-sealable secondary layer adherent to the primary layer and comprising an essentially amorphous second linear polyester, said secondary layer containing from 0.005 to 10% by weight based upon the weight of the second linear polyester of a finely-divided particulate additive having an average particle size greater than the thickness of the secondary layer dispersed substantially uniformly throughout the secondary layer, the exposed surface of the secondary layer having anti-blocking properties produced by surface protrusions in an area concentration of at least 50 protrusion peaks per mm.sup.2 of surface having a peak height of at least 0.5 .mu.m measured from the surface of the polymer. The particulate additive preferably has an average particle size less than 30 .mu.m. The secondary layer preferably also contains 0.1 to 1% by weight of smaller particles having an average particle size of 0.005 to 1.8 .mu.m.

Dependencies are inferred from the claim text.