Production of oriented thermoplastic films by blown-film extrusion
US5468444A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 27, 1994 |
| Grant date | Nov 21, 1995 |
| Priority date | — |
| Expiry date | May 27, 2014 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB29C48/912
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
A process for producing an oriented blown film of a thermoplastic resin by blown film extrusion, carried out by blowing air into an extruded bubble of the resin extruded from a ring die to expand the bubble and cooling the expanded bubble with air from a cooling air ring, wherein blown film extrusion is carried out under such conditions that the ratio of (b) the final diameter of the expanded bubble to (a) the diameter of the bubble at the crystallizing temperature of the thermoplastic resin ((b)/(a)) ranges from 1.5 to 10. The process provides an oriented blown film excellent in strength, appearance, and heat shrinkage characteristics.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.