The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Nov. 25, 1980
Filed:
Oct. 01, 1979
Toray Industries, Inc., Tokyo, JP;
Abstract
This invention relates to a three-layered polypropylene film consisting of a core layer of biaxially oriented polypropylene sandwiched between ethylene-propylene copolymer layers having a different degree of molecular orientation, shown by birefringence, i.e., birefringence of one copolymer layer is different from that of the other copolymer layer. The film thus prepared has not only a good heat sealing property but also a good resistance against 'hot-tack', 'blocking', and 'scratches'. The film can be provided by a process wherein one copolymer layer is biaxially stretched, while the other copolymer layer is uniaxially stretched. Three-layered films of this invention are particularly suited for making bags with lap sealed parts, where lap sealing is a heat sealing method characterized by heat sealing one side of a film with the other side of the film.