Time-efficient process for making expanded polymeric products with multipass expansion of polystyrene bead
US5110836A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 26, 1990 |
| Grant date | May 5, 1992 |
| Priority date | — |
| Expiry date | Nov 26, 2010 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S264/15
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
A method for making low density (0.8-1.1 lb/cu.ft.) expanded polymeric products uses blowing agent in an amount of only from 2 to 4.4 weight percent and aging periods of from 1 to 80 hours after each expansion step. The process uses 2 to 5 expansion steps and a polymer having a particular polydispersity, weight average molecular weight and M.sub.z :M.sub.n, this polymer having a greater expandability than conventional polymers. The process requires only about half of the amount of blowing agent currently being used in commerically viable processes for making expanded polystyrene products. The process can be used with or without a molding step.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.