Hollow-strand foam and preparation thereof

摘要

The method involves extruding a foamable composition which is in gel state, through a die having apertures, provided each aperture yields a hollow extrudate. The foamable composition comprises a blowing agent composition and film-forming composition. The hollow extrudate is converted into foamed strands at temperature that promotes foam bubble stability. The extrudate strands are allowed to contact each other while they retain at least some surface tackiness in order to effect adhesion between adjacent individual strands and yield a hollow multi-strand foam extrudate. The blowing agent comprises carbon dioxide, nitrogen, nitrous oxide, noble gas, air, hydrocarbon, ether, 1-6C lower alcohols, partially halogenated hydrocarbon, ammonia and/or water. The film-forming composition comprises polystyrene and optionally ethylene/styrene interpolymer. Independent claims are also included for the following: (a) Extrusion die for processing foamable polymer composition; (b) Cellular foam structure; (c) Article fabricated from foam structure.