Method of stretching film below the natural draw ratio without necking
US3995007A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 24, 1974 |
| Grant date | Nov 30, 1976 |
| Priority date | — |
| Expiry date | Jul 24, 1994 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB29C55/02
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
A method for producing a synthetic crystalline thermoplastic resin film suitable for stretching without necking including adding 5 to 300 parts by weight of a filler to 100 parts of a synthetic crystalline thermoplastic resin film such as polyethylene on isotactic polypropylene having a degree of crystallization of more than 60%, pressing the film against a rigid blade having a radius of curvature of 0.01 to 1.0 millimeter, bending the film around the blade using the blade as a fulcrum to a bending angle between 20.degree. and 170.degree., moving the film relative to the blade while keeping the bending angle constant thereby whitening the film, said whitening of the film being conducted without positively heating or stretching the film, and stretching the film after whitening at a draw ratio below the natural draw ratio of the film.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.