Method of manufacturing polyvinyl alcohol films oriented in two orthogonal directions
US4124677A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 6, 1976 |
| Grant date | Nov 7, 1978 |
| Priority date | — |
| Expiry date | Dec 6, 1996 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB29K2029/00
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
A PVA film successively oriented in two orthogonal directions is prepared by firstly elongating the film in the longitudinal direction by more than 200% while maintaining the water content (Z .times. 100)% at a value of from 10 to 35% and the temperature in a range of from (1.50/Z +20).degree. C to 75.degree. C. The film is then preheated while maintaining its water content at least 7%, and then elongated laterally by more than 200% at a temperature of from 45.degree. to 110.degree. C. Then the film is heat treated at a temperature of 110.degree. to 210.degree. C while permitting the film to shrink by less than 15% in the lateral direction. Finally, the film is cooled to room temperature under tension.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.