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US 9,902,787 B2Granted
Polytetrafluoroethylene powder
AssigneeDaikin Industries, Ltd.
InventorsYoshinori Nanba, Dai Fukami, Takuya Yamabe, Taketo Kato, Makoto Ono, Takahiro Taira, Hirotoshi Yoshida, Taku Yamanaka
Life of this patent
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Abstract
The present invention provides a polytetrafluoroethylene powder having high dispersibility in lubricants. The polytetrafluoroethylene powder includes polytetrafluoroethylene containing a tetrafluoroethylene unit alone or a tetrafluoroethylene unit and a modifying monomer unit based on a modifying monomer copolymerizable with the tetrafluoroethylene, and has a specific surface area of 32 m2/g or larger.
Claims17
A polytetrafluoroethylene powder comprising:
- polytetrafluoroethylene containing a tetrafluoroethylene unit alone or a tetrafluoroethylene unit and a modifying monomer unit based on a modifying monomer copolymerizable with the tetrafluoroethylene,
- the powder having a specific surface area of 32 m2/g or larger, and
- the powder being formed from polytetrafluoroethylene particles having a volume average particle size of 50 nm or smaller.
A polytetrafluoroethylene powder comprising:
- polytetrafluoroethylene containing a tetrafluoroethylene unit alone or a tetrafluoroethylene unit and a modifying monomer unit based on a modifying monomer copolymerizable with the tetrafluoroethylene,
- the powder having a specific surface area of 32 m2/g or larger, and being formed from polytetrafluoroethylene particles having a volume average particle size of 50 nm or smaller,
- said polytetrafluoroethylene powder being produced by a method including emulsion polymerizing tetrafluoroethylene alone or tetrafluoroethylene and a modifying monomer copolymerizable with the tetrafluoroethylene in an aqueous medium in the presence of a chain-transfer agent, a fluorosurfactant having LogPOW of 3.4 or lower, and a polymerization initiator to obtain an aqueous dispersion containing polytetrafluoroethylene particles, and coagulating the polytetrafluoroethylene particles to recover polytetrafluorooethylene powder from the resulting aqueous dispersion containing polytetrafluorooethylene particles, wherein the fluorosurfactant is used in an amount corresponding to 4,600 to 500,000 ppm of the aqueous medium.
Dependencies are inferred from the claim text.