Process for the production of optically isotropic extrusion films

US5076987A · kind A · utility

Assignee

• BAYER HEALTHCARE LLC · DE

Inventors

• Joachim Wank · Dormagen, DE
• Hans-Leo Weber · Eschenried, DE
• Claus Burkhardt · Lörrach, DE
• Dieter Freitag · Krefeld, DE
• Bernhard Schulte · Krefeld, DE
• Werner Waldenrath · Cologne, DE

Key dates

• Filing date: Apr 4, 1990
• Grant date: Dec 31, 1991
• Expiry date: Apr 4, 2010

Classification

• Technology area (CPC B): Performing Operations; Transporting
• CPC primary: B29K2995/0045
• WIPO field: Other special machines
• WIPO sector: Mechanical engineering

Abstract

A process for the production of optically isotropic extrusion films is disclosed. Accordingly in a first process step a thermoplsatic resin is extruded to form a film having a thickness below 600 .mu.m. The second process step entails PA1 a) calendering said film between a ground elastic roller and a high gloss steel roller to produce a film having a high gloss surface and a matt surface, or PA1 b) calendering said film between a lacquered elastic roller and a high gloss steel roller to produce a film having high gloss on both surfaces, or PA1 c) calendering said film between a ground elastic roller and a high gloss steel roller to produce a film having a high gloss surface and a matt surface, and then coating said matt surface with a melt of said thermoplastic polymer and calendering the resulting coated film between a high gloss steel roller and a ground elastic roller, with the high gloss side of the coated film facing the roller of elastic material.