Process for producing aqueous dispersion of purified polytetrafluoroethylene
US7238735B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 21, 2005 |
| Grant date | Jul 3, 2007 |
| Priority date | — |
| Expiry date | Nov 21, 2025 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC08F6/16
- WIPO fieldMacromolecular chemistry, polymers
- WIPO sectorChemistry
Abstract
A process for producing an aqueous dispersion of purified polytetrafluoroethylene (PTFE), comprising passing a crude aqueous dispersion of PTFE comprising from 10 to 50 mass % of PTFE fine particles having an average particle diameter of from 0.1 to 0.5 μm, from 0.05 to 1.0 mass %, based on PTFE, of a fluorine-containing carboxylic acid salt (APFO) and from 2 to 20 mass %, based on PTFE, of a nonionic surfactant through a column packed with a weak basic AER upward at a linear velocity of 0.1 to 2 mm/sec with a contact time of 0.2 to 4 hours to reduce the APFO concentration. The process can increase the absorption of APFO by the anion exchange resin, prevents agglomeration of PTFE during passage and makes it easy to elute the absorbed APFO.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.