Polytetrafluoroethylene powder

Patent metadata

Field	Value
Publication number	US-9902787-B2
Application number	US-201515316032-A
Country	US
Kind code	B2
Filing date	Jun 4, 2015
Priority date	Jun 4, 2014
Publication date	Feb 27, 2018
Grant date	Feb 27, 2018

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 m 2 /g or larger.

First claim

The invention claimed is:

1. 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 m 2 /g or larger, and
the powder being formed from polytetrafluoroethylene particles having a volume average particle size of 50 nm or smaller.

2. The polytetrafluoroethylene powder according to claim 1 ,
wherein the specific surface area is 35 m 2 /g or larger.

3. The polytetrafluoroethylene powder according to claim 1 , which is formed from polytetrafluoroethylene particles having a volume average particle size smaller than 20 nm.

4. The polytetrafluoroethylene powder according to claim 1 , having a specific surface area of 40 m 2 /g or larger.

5. The polytetrafluoroethylene powder according to claim 1 , which is formed from polytetrafluoroethylene particles having a volume average particle size of 0.1 nm to 50 nm.

6. The polytetrafluoroethylene powder according to claim 1 , having an average particle size of 1 to 50 μm.

7. 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 m 2 /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.

8. The polytetrafluoroethylene powder according to claim 7 , wherein the fluorosurfactant is an anionic surfactant.

9. The polytetrafluoroethylene powder according to claim 7 , wherein the fluorosurfactant is used in an amount corresponding to 4,600 to 300,000 ppm of the aqueous medium.

10. The polytetrafluoroethylene powder according to claim 7 , wherein the chain-transfer agent is used in an amount of 1 to 20,000 ppm relative to a whole amount of fluoromonomer supplied in the emulsion polymerizing.

11. The polytetrafluoroethylene powder according to claim 7 , wherein the chain-transfer agent is used in an amount of 1 to 2,000 ppm relative to a whole amount of fluoromonomer supplied in the emulsion polymerizing.

12. The polytetrafluoroethylene powder according to claim 7 , wherein the fluorosurfactant is used in an amount corresponding to 6,000 to 300,000 ppm of the aqueous medium and the chain-transfer agent is used in an amount of 100 to 10,000 ppm relative to a whole amount of fluoromonomer supplied in the emulsion polymerizing.

13. The polytetrafluoroethylene powder according to claim 7 , wherein the fluorosurfactant is used in an amount corresponding to 6,000 to 300,000 ppm of the aqueous medium, the chain-transfer agent is used in an amount of 100 to 10,000 ppm relative to a whole amount of fluoromonomer supplied in the emulsion polymerizing, the fluorosurfactant is an anionic surfactant and the chain-transfer agent comprises a saturated hydrocarbon or an alcohol.

14. The polytetrafluoroethylene powder according to claim 7 , wherein the chain-transfer agent comprises ethane or propane.

15. The polytetrafluoroethylene powder according to claim 7 , having a specific surface area of 40 m 2 /g or larger.

16. The polytetrafluoroethylene powder according to claim 7 , which is formed from polytetrafluoroethylene particles having a volume average particle size of 0.1 nm to 50 nm.

17. The polytetrafluoroethylene powder according to claim 7 , having an average particle size of 1 to 50 μm.

Assignees

• Daikin Ind Ltd

Inventors

• Nanba Yoshinori
• Fukami Dai
• YAMABE Takuya
• Kato Taketo
• Ono Makoto
• Taira Takahiro
• Yoshida Hirotoshi
• Yamanaka Taku

Classifications

• C10N2050/10

  semi-solid; greasy · CPC title

• C10N2060/08

  Halogenation · CPC title

• C10M2213/0626

  used as thickening agents · CPC title

• C08F214/262

  with fluorinated vinyl ethers · CPC title

• C10N2030/04

  Detergent property or dispersant property · CPC title