Manufacture of film from partially crosslinked polyethylene
US4226905A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 16, 1979 |
| Grant date | Oct 7, 1980 |
| Priority date | — |
| Expiry date | Apr 16, 1999 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB29K2995/0081
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.