Styrene polymer foam and the preparation thereof

Claim 1

An alkenyl aromtic thermoplastic synthetic resinous elongate foam body having a machine direction and a transverse direction, the body defining a plurality of closed noninterconnecting gas containing cells therein, the cells having an average cell size of from about 1.2 to 3 millimeters, the foam body being a generally uniform cellular structure and being without discontinuities, being without substantial variation in average cell size when cell size is measured by averaging cell diameter across the minimum cross-sectional dimension of the body, the elongate body having a cross-sectional area of at least 18 square inches and having a minimum cross-sectional dimension of at least one inch, the foam body having a water vapor permeability not greater than 1.8 perm inches, a density of from about 1.4 to about 5 pounds per cubic foot the body being a continuous hardened thermoplastic gel with the further limitation that the cells contain a blowing agent having as a major component thereof at least 70 weight percent of a member selected from the group consisting of chlorofluoromethane, bromochlorodifluoromethane, and mixtures thereof.