Patent ID: 6048909
Filing Date: 2000-04-11
Classification: C08J,C08L,Y10S,Y10T

Abstract:
A process for making a closed cell alkenyl aromatic polymer foam having increased heat distortion temperature, which process comprises;(I) forming a melt polymer material comprising;(A) from about 80 to about 98 percent by weight (based on the combined weight of Components 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 2 to about 20 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 1000 g/10 min, an M.sub.w /M.sub.n of about 1.5 to about 20, comprising;(1) from about 21 to about 65 mol % 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 79 mol % 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 % 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) further 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 0.2 to about 5.0 gram-moles per kilogram (based on the combined weight of Components A and B);(III) cooling the foamable gel to an optimum temperature; and(IV) extruding the gel from step III through a die to a region of lower pressure to form a foam,wherein as a result of said process the heat distortion temperature of said foam is increased by about 2.degree. C. or more relative to a corresponding foam without the substantially random interpolymer.