Process for processing a semicrystalline thermoplastic
US6174479A · kind A · utility
2Cited by
7References
8Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Sep 17, 1997 |
| Grant date | Jan 16, 2001 |
| Priority date | — |
| Expiry date | Sep 17, 2017 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/31855
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
A process for preparing thermoplastics comprising the steps of cooling an extrudate to a temperature T.sub.1, drawing the molten extrudate, relaxing the extrudate at a temperature T.sub.3 for a duration of at least the average relaxation time of the thermoplastic at the relaxation temperature, and quenching the extrudate to a temperature T.sub.4. The process enables the manufacture of films consisting of at least one propylene homopolymer with a thickness of 100 to 250 .mu.m and having a hot shrinkage of at most 20%, a haze of less than or equal to 3% and a total transparency with respect to air of greater than 70%.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.