Patent ID: 6638984
Filing Date: 2003-10-28
Classification: B01J,C08J

Abstract:
A method of forming a microcellular foam, comprising the steps of:solvating a polymer, co-polymer, or polymer blend with an appropriate solvent; combining the solvated polymer, co-polymer or polymer blend with a blowing agent to give a mixture; forming microscopic droplets from the mixture; removing the solvent from the microscopic droplets to precipitate out the polymer and blowing agent; and isolating the precipitated polymer and blowing agent product to give thermo-expandable but unexpanded microspheres comprising a polymeric wall surrounding one or more pockets of blowing agent within the microsphere and wherein the polymeric wall comprises reactive functionalities that allow fusion to other microspheres upon expansion of the microspheres; and heating the thermo-expandable microspheres at a temperature that causes the microspheres to expand, to give expanded microbubbles, at least a portion of the microbubbles being fused to each other to give a microcellular foam.