Expandable styrene resin particles, expandable beads, and foamed article
US6797733B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | May 7, 2003 |
| Grant date | Sep 28, 2004 |
| Priority date | — |
| Expiry date | May 7, 2023 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC08J2325/06
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
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 vol % 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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.