Process for manufacturing plastic microspheres

Abstract

Spherical particles having a diameter between 0.007" and 0.040" are formed from melt extruded thermoplastic material suitable for casting on a heated mold surface and melting thereon to form a thin layer of material having a nominal thickness of 0.040" that is cooled and removed from the mold surface as a part having a porosity less than a visually observable threshold. The process includes the steps of providing microspheres formed of blended and melt extruded thermoplastic, plasticizers (if necessary) and pigment additives that constitute less than 5% by weight of the blend and shaped as a smooth round spherical particle. The microspheres may then be distributed as predetermined charge of such microspheres against the heated casting surface to melt the microspheres as a layer of thermoplastic material having a porosity less than 0.003 inches and thereafter cooling and removing the non-porous layer from the casting surface.

Dependencies are inferred from the claim text.