Film blowing process
US5082616A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 25, 1990 |
| Grant date | Jan 21, 1992 |
| Priority date | — |
| Expiry date | Oct 25, 2010 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC08L33/08
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
A method for preparing biaxially oriented poly(vinylidene fluoride) films involving the addition of a minor amount of a polymer miscible with PVDF, particularly poly(methyl methacrylate), to the poly(vinylidene fluoride) to form a blend exhibiting reduced crystallinity and reduced rates of crystallization during the film forming process. The low crystallinity permits the blend to be subsequently formed into biaxially oriented film in a double-bubble tubular film extrusion process by retarding the rate of crystallization in the first bubble, thereby permitting formation of the second bubble without rupture. The films thus formed possess piezoelectric and other desirable characteristics.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.