Oriented porous polypropylene films
US4975469A · kind A · utility
52Cited by
31References
17Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Mar 20, 1989 |
| Grant date | Dec 4, 1990 |
| Priority date | — |
| Expiry date | Mar 20, 2009 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02A40/25
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
This invention relates to oriented porous films having cells with polygonal cross sections and average pore diameters of about 5 to about 30 microns and interconnecting pores between the cells which have a diameter of about 0.2 to about 20 microns which are formed from a polypropylene-based resin and a process for forming the film which comprises the steps of forming a film containing beta-spherulites, selectively extracting a portion of the beta-spherulites to form a porous film and stretching the porous film in at least one direction to form the oriented polymeric porous film.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.