Patent ID: 6395791
Filing Date: 2002-05-28
Classification: B29B,C08J,C08K,C08L

Abstract:
A process for making a polymer foam; which comprises;i) converting a grafted blend composition into a polymer melt, said composition comprising A) one or more homopolymers or interpolymers with peak crystalline melting temperature (Tm) and/or or glass transition temperature (Tg by DSC) of 90Â° C. or more; B) one or more homopolymers or interpolymers with peak crystalline melting temperature (Tm) and/or glass transition temperature (Tg by DSC) of 80Â° C. or less; and C) at least one coupling agent; â€ƒand wherein 1) the upper service temperature of said grafted blend is greater than about 80Â° C.; 2) the gel content of said grafted blend is 50 percent or less (as determined by insolubility of the gels in boiling xylene when tested according to ASTM D-2765A-84); 3) said grafted blend composition exhibits at least one of the following improvements relative to the same blend in the absence of Component C; (a) the melt strength is increased by 5% or more; and/or (b) the upper service temperature is increased by 0.5Â° C. or more. (ii) introducing, at an elevated pressure, at least one blowing agent into the polymer melt to form a foamable gel, the blowing agent being present in a total amount of from 0.05 to 5.0 gram-moles per kilogram of polymers contained in the polymer melt; (iii) cooling the foamable gel to an optimum temperature; and (iv) extruding the foamable gel from step iii through a die to a region of lower pressure to form a foam.