Process for making expanded polymeric product with low level of emission of blowing agent

US5240657A · kind A · utility

Assignee

• BASF SE

Inventors

• William H. Harclerode · Ewing, US
• Eugene K. Zimmermann · Hamilton Square, US
• Barry J. Pekich · Bridgeton, US
• John C. Knutsen · Highland Park, US
• John V. Wiman · Morristown, US
• John Charles Voss · Redwood City, US

Key dates

• Filing date: Oct 15, 1991
• Grant date: Aug 31, 1993
• Expiry date: Oct 15, 2011

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S264/09
• WIPO field: Other special machines
• WIPO sector: Mechanical engineering

Abstract

A method for making low density (0.8-2 lb/cu.ft.) expanded polymeric products uses blowing agent in an amount of only from 2 to 4.4 weight percent, the process emitting blowing agent during processing in an amount of from only about 0.3 to about 2.5 weight percent. The process uses 2 to 5 expansion steps together with 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 commercially viable processes for making expanded polystyrene products. The process can be used with or without a molding step.