The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 10, 2007
Filed:
Jul. 30, 2004
Makoto Kunimi, Ichihara, JP;
Tetsuya Katou, Ichihara, JP;
Makoto Saitou, Ichihara, JP;
Hiroshi Nakaguki, Ichihara, JP;
Toshio Akima, Ichihara, JP;
Makoto Kunimi, Ichihara, JP;
Tetsuya Katou, Ichihara, JP;
Makoto Saitou, Ichihara, JP;
Hiroshi Nakaguki, Ichihara, JP;
Toshio Akima, Ichihara, JP;
Hitachi Chemical Co., Ltd., Tokyo, JP;
Abstract
A process of producing expandable styrene resin particles, wherein in suspension polymerization of styrene monomers, the concentration of oxygen in a reaction vessel is kept low at least in a late stage of the polymerization, and the resulting styrene resin particles are impregnated with an expanding agent before or after completion of the polymerization. Preferably, at a polymerization rate of 60% or higher, the concentration of oxygen in the reaction vessel is kept at 7 volt % or lower. When additional styrene monomers are added during the polymerization, they are added and adsorbed to styrene resin particles in the course of polymerization while the concentration of oxygen is kept low. By this method, the particles whose internal portion has a low molecular weight and surface portion has a high molecular weight are obtained. A foamed article produced from the particles has high strength and a good appearance.