Sealable, opaque polyolefinic multilayer film and process therefor

US4652489A · kind A · utility

Assignee

• Hoechst GmbH · DE

Inventors

• Gunther Crass · Taunusstein, DE
• Siegfried Janocha · Wiesbaden, DE
• Lothar Bothe · Mainz, DE

Key dates

• Filing date: Dec 5, 1985
• Grant date: Mar 24, 1987
• Expiry date: Dec 5, 2005

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10T428/31913
• WIPO field: Surface technology, coating
• WIPO sector: Chemistry

Abstract

A sealable, opaque polyolefinic multilayer film composed of a polypropylene base layer, a non-sealable surface layer, and a sealable surface layer, and process therefor. The sealable surface layer has a low minimum sealing temperature and is made from a copolymer of propylene and ethylene or butene-1 units and/or a terpolymer of ethylene, propylene and butene-1 units. The non-sealable layer is a combination of a propylene homopolymer and a slip agent. The base layer contains an additive which is incompatible with polypropylene. The process includes stretching of the film, and during the stretching step, the polymer matrix is torn open around the additive particles to form vacuoles which give the base layer a degree of opacity.