Production method for polytetrafluoroethylene aqueous dispersion
US9243080B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Dec 2, 2013 |
| Grant date | Jan 26, 2016 |
| Priority date | — |
| Expiry date | Dec 2, 2033 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC08L2201/54
- WIPO fieldMacromolecular chemistry, polymers
- WIPO sectorChemistry
Abstract
The present invention aims to provide a method of producing a PTFE aqueous dispersion which contains PTFE particles having a small particle size and which is excellent in dispersion stability by multistage polymerization without using a long-chain fluorosurfactant. The method includes the steps of: (1) polymerizing a fluoromonomer in an aqueous medium in the presence of a fluorosurfactant and a polymerization initiator to provide an aqueous dispersion containing particles of at least one fluoropolymer selected from the group consisting of PTFE and melt-processible fluororesins excluding polytetrafluoroethylene; and (2) polymerizing TFE alone or TFE and a modifying monomer in an aqueous medium in the presence of the fluoropolymer particles and a polymerization initiator to provide an aqueous dispersion containing PTFE particles. The fluoropolymer particles have an equivalent weight (EW) of 6,000 or more and a volume average particle size of not smaller than 0.1 nm but smaller than 20 nm.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.