Patent · US Expired

Process for the preparation of a biaxially oriented polypropylene film

US4758396A · kind A · utility

40Cited by

10References

17Claims

0Family size

Assignee

Hoechst GmbH · DE

Inventors

Guenther Crass · Taunusstein, DE
Gunter Schloegl · Kelkheim, DE
Lothar Bothe · Mainz, DE
Herbert Peiffer · Mainz, DE

Key dates

Filing date	Sep 9, 1986
Grant date	Jul 19, 1988
Priority date	—
Expiry date	Sep 9, 2006

Classification

Technology area (CPC Y)Emerging Cross-Sectional Technologies
CPC primaryY10T428/31913
WIPO fieldOther special machines
WIPO sectorMechanical engineering

Abstract

A process for the preparation of a biaxially stretch-oriented film having at least one opaque layer is described. The opaque layer is composed essentially of propylene polymer and fillers in a quantity of about 10 to 40% by weight, relative to the total weight of propylene polymer and fillers. In production, the granules are melted in a screw extruder, are forced through a die and are formed by cooling to give a preformed film. The preformed film is then stretch-oriented both along the machine direction and transversely perpendicular to the machine direction and is then heat-set. The fillers are added in the form of a masterbatch to the granules of unfilled polymers. The masterbatch should have a filler content of more than about 30% by weight.

Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.