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:
Oct. 07, 1980
Filed:
Apr. 16, 1979
David A Harbourne, Kingston, CA;
Du Pont Canada Inc., Montreal, CA;
Abstract
The present invention provides a process for the manufacture of a polyethylene film having improved tear strength in the transverse direction. The process involves extruding a partially crosslinked polyethylene into film having a thickness between 10 and 100 .mu.m, by a blown film process. The blow-up ratio is in the range of 1.2:1 to 4:1 and the MD draw-down ratio is in the range of 2 to 60. Polyethylenes used in the present invention had prior to being partially crosslinked a density in the range of 0.940 to 0.970 g/cm.sup.3 and a melt index in the range of 0.2 to 15.0 g/10 min. The polyethylene is crosslinked to an extent sufficient to provide a film having an Elmendorf tear strength in the transverse direction substantially less than the tear strength of film made from the uncrosslinked polyethylene. Crosslinking may be accomplished using any known method e.g. by irradiation, through use of crosslinking agents. The film so produced is useful in packaging operations where transverse cutting or tearing performance of the film is important.