Patent ID: 6586482
Filing Date: 2003-07-01
Classification: B29C,Y10T

Abstract:
A continuous method for making a foam material comprising:(1) mixing at least two immiscible amorphous thermoplastic polymeric material and at least one physical blowing agent in an apparatus having an exit shaping orifice at a temperature and pressure sufficient to form a melt solution wherein the blowing agent is uniformly distributed throughout the polymeric material; (2) reducing the temperature of the melt solution at the exit of the apparatus while maintaining the melt solution at a pressure sufficient to keep the blowing agent in solution; and (3) passing the solution through said exit shaping orifice and exposing the solution to atmospheric pressure, whereby the blowing agent expands causing nucleation and cell formation resulting in the melt solution foaming at or about the time it exits the shaping orifice, and wherein at or about the time the melt solution exits the shaping orifice it is subjected to elongational forces causing the resulting foam to have an anisotropic morphology comprising two axes perpendicular to each other, both parallel to a major surface of the foam, said axes comprising a longitudinal axis parallel to the machine direction and a transverse axis perpendicular to the machine direction.