Process for producing multilayer polytetrafluoroethylene porous membrane and semisintered polytetrafluoroethylene multilayer structure
US5225131A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 5, 1992 |
| Grant date | Jul 6, 1993 |
| Priority date | — |
| Expiry date | Jun 5, 2012 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB29K2027/18
- WIPO fieldChemical engineering
- WIPO sectorChemistry
Abstract
A process for producing a multilayer polytetrafluoroethylene porous membrane is disclosed, which process comprises at least two layers having different average pore diameters, the process comprising the steps of: filling the inside of a cylinder of an extruding mold distinctively with at least two kinds of polytetrafluoroethylene fine powders with each of which a liquid lubricant has been mixed; paste-extruding the powders to obtain a multilayer extrudate, which is then optionally rolled; removing the liquid lubricant from the multilayer extrudate or the rolled multilayer extrudate to obtain an unsintered multilayer structure; subsequently heating the unsintered multilayer structure at a temperature not lower than the melting point of sintered polytetrafluoroethylene to obtain a semisintered multilayer structure; and then stretching the semisintered multilayer structure at least monoaxially. A semisintered polytetrafluoroethylene multilayer structure capable of being used as an intermediate material for the above process is also disclosed.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.