Patent ID: 6174471
Filing Date: 2001-01-16
Classification: C08J

Abstract:
A process for making an open cell foam, which process comprises;(I) forming a melt polymer material comprising;(A) from about 30 to about 99.5 percent by weight (based on the combined weights of Component A and B) of one or more alkenyl aromatic polymers, and wherein at least one of said alkenyl aromatic polymers has a molecular weight (M.sub.w) of from about 100,000 to about 500,000; and(B) from about 0.5 to about 70 percent by weight (based on the combined weight of Components A and B) of one or more substantially random interpolymers having an I.sub.2 of about 0.1 to about 50 g/min, an M.sub.w /M.sub.n of about 1.5 to about 20; comprising;(1) from about 0.5 to about 65 mol percent of polymer units derived from;(a) at least one vinyl or vinylidene aromatic monomer, or(b) at least one hindered aliphatic or cycloaliphatic vinyl or vinylidene monomer, or(c) a combination of at least one aromatic vinyl or vinylidene monomer and at least one hindered aliphatic or cycloaliphatic vinyl or vinylidene monomer, and(2) from about 35 to about 99.5 mol percent of polymer units derived from at least one of ethylene and/or a C.sub.3-20 .alpha.-olefin; and(3) from 0 to about 20 mol percent of polymer units derived from one or more of ethylenically unsaturated polymerizable monomers other than those derived from (1) and (2); and(C) optionally, one or more nucleating agents and(D) optionally, one or more other additives; and(II) incorporating into said melt polymer material at an elevated pressure to form a foamable gel(E) one or more blowing agents present in a total amount of from about 0.5 to about 5.0 gram-moles per kilogram (based on the combined weight of Components A and B);(III) cooling said foamable gel to an optimum foaming temperature; and(IV) extruding the gel from Step III through a die to a region of lower pressure to form a foam.