Production of resin foam by aqueous medium

Abstract

A process for producing a resin foam by using an aqueous medium, which comprises (a) treating a resin compound with said aqueous medium to cause the aqueous medium to adhere to and be held by the resin compound, said resin compound being composed of porous agglomerated particles resulting from partial melt-adhesion of thermoplastic resin particles coated with a fine hydrophilic solid powder which does not substantially melt at the melting temperature of the resin particles, said solid powder being embedded in the resin particles but partly exposed at their surfaces, (b) melt-kneading the resin compound treated with the aqueous medium under such an elevated pressure that evaporation of the aqueous medium is substantially inhibited, and (c) thereafter releasing the kneaded resin composition from the pressurized state to foam it; and a thermoplastic resin compound used for the aforesaid process.

Dependencies are inferred from the claim text.