Process for making molded polymeric product with multipass expansion of polymer bead with low blowing agent content

US5110524A · kind A · utility

Assignee

• BASF SE

Inventors

• William H. Harclerode · Ewing, US
• William E. Volz · Suffolk, US
• John V. Wiman · Morristown, US
• John Charles Voss · Redwood City, US
• Barry J. Pekich · Bridgeton, US
• John C. Knutsen · Highland Park, US

Key dates

• Filing date: Oct 15, 1991
• Grant date: May 5, 1992
• Expiry date: Oct 15, 2011

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S264/15
• WIPO field: Other special machines
• WIPO sector: Mechanical 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. 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.