Method of and apparatus for increasing the production output of stretched flat film webs composed of thermoplastic material
US4076785A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 26, 1975 |
| Grant date | Feb 28, 1978 |
| Priority date | — |
| Expiry date | Jun 26, 1995 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S264/73
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
This invention relates to an improvement in a method for increasing the production of stretched flat film webs of thermoplastic material in which a melt of thermoplastic material is extruded from a slot die, the melt is solidified to form a film, the film is transversely stretched, the stretched film is heat-set, divided into narrower webs, and wound up, the improvement comprising extruding the melt from a slot die wider than the die normally employed for the production of a preliminary film, which usually corresponds to the width of a transverse stretching frame, dividing the melt in the longitudinal direction into at least two films, superposing the film webs, and transversely stretching said superposed webs. The invention also relates to an apparatus for performing the method.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.