Process for preparing pre-expanded particles of thermoplastic resin
US4778829A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 11, 1987 |
| Grant date | Oct 18, 1988 |
| Priority date | — |
| Expiry date | Aug 11, 2007 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC08J2323/02
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
A process for preparing pre-expanded particles of a thermoplastic resin, which comprises heating an aqueous dispersion of thermoplastic resin particles containing a volatile blowing agent to a high temperature under pressure in a pressure vessel, and releasing the dispersion into an atmosphere maintained at a lower pressure than the pressure in the pressure vessel and at a temperature of not lower than 40.degree. C. According to the process of the present invention, there can be obtained pre-expanded thermoplastic resin particles with a large average diameter of cells. By molding the pre-expanded particles obtained by the present invention, molded articles which are small in dimensional shrinkage and excellent in surface appearance can be obtained without imparting expandability to the particles or aging the particles under pressure prior to molding.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.