Process for the production of expanded particles of a polymeric material
AssigneeJapan Styrene Paper Corporation
InventorsShohei Yoshimura, Toru Yamaguchi, Masato Kanbe, Hideki Kuwabara
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Abstract
A process is disclosed for the production of expanded particles of polymeric material wherein unexpanded particles of the material are contacted with a nitrogen-containing inorganic gas under a first pressure condition to impregnate the particles with the gas. The gas impregnated particles are heated to a temperature higher than the softening point of the material, and dispersed into a liquid medium. The resulting dispersion is subjected to a lower pressure to expand the particles. The expanded particles may be used as prefoamed particles for the molding of foamed articles.
Claims24
A process for the production of expanded particles, comprising the steps of:
- (a) providing unexpanded particles formed of a semicrystalline polymeric material;
- (b) contacting a nitrogen-containing inorganic gas with the unexpanded particles under a pressurized condition to impregnate the unexpanded particles with said gas, heating the unexpanded particles to a first temperature higher than the softening point of the polymeric material and dispersing the unexpanded particles in a liquid dispersing medium, so that a dispersion maintained at a first pressure and containing the softened, gas-impregnated, unexpanded particles is obtained;
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- (c) subjecting said dispersion to a second pressure lower than said first pressure so that the unexpanded particles are expanded.
Dependencies are inferred from the claim text.