Thermoplastic sheet produced by multiple stretching steps at different temperatures

US5238743A · kind A · utility

Assignee

• Hoechst GmbH · DE

Inventors

• Gerhard Grolig · Mörfelden, DE
• Werner Roth · Lenningen, DE
• Peter Lang · Gelnhausen, DE
• Horst Eberhardt · Eltville am Rhein, DE

Key dates

• Filing date: May 13, 1991
• Grant date: Aug 24, 1993
• Expiry date: May 13, 2011

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10T428/31786
• WIPO field: Surface technology, coating
• WIPO sector: Chemistry

Abstract

A plastic sheet, which initially is biaxially stretched above its glass transition temperature and heat-set, is stretched a second time monoaxially or biaxially at temperatures below its glass transition temperature, the stretching ratio in the two directions being in the range from about 0.5 to 10%. The secondary stretching is carried out at temperatures between about 30.degree. C. and 60.degree. C. This sheet which has been stretched twice is integrated into a laminated safety glass comprising a laminate, in which the plastic sheet carrying a function layer is disposed between two polyvinylbutyral sheets which, in turn, are enclosed between glass panes.