Patent ID: 6080798
Filing Date: 2000-06-27
Classification: B29C,C08J

Abstract:
A method for producing a closed cell polymer foam, comprising(a) selecting a suitable polymer and inert blowing agent combination, wherein the polymer is in a solid or melt state, and the blowing agent is in the form of a gas or a volatile liquid,(b) exposing the polymer to the blowing agent in the gas or liquid state at a conditioning temperature, pressure and exposure time, selected according to the thermodynamic properties of the polymer/blowing agent combination to provide a polymer/blowing agent solution having a desired solubility up to a maximum of saturation solubility of the blowing agent in the polymer,(c) slowly depressurizing the polymer/blowing agent solution to ambient pressure to prevent premature foam formation,(d) applying an external compressive stress to the polymer-blowing agent solution at a temperature at which the polymer is conditioned with the blowing agent up to about the T.sub.g of the neat polymer, wherein the amount of stress applied is dependent upon the thermodynamic properties of the polymer/blowing agent combination and the amount of blowing agent dissolved in the polymer, to induce cell nucleation and foam formation, and(e) quenching the foam by rapid cooling to a lower temperature.