Paste containing polytetrafluoroethylene and method for producing same

Patent metadata

Field	Value
Publication number	US-2016372240-A1
Application number	US-201515121150-A
Country	US
Kind code	A1
Filing date	Feb 27, 2015
Priority date	Feb 27, 2014
Publication date	Dec 22, 2016
Grant date	—

Abstract

The present invention aims to provide a paste containing polytetrafluoroethylene which can be formed into a molded polytetrafluoroethylene article having a significantly small thickness of polytetrafluoroethylene and is less likely to cause defects in molding; and a method of producing the paste. The present invention provides a method of producing a paste, including the steps of coagulating primary particles of polytetrafluoroethylene in an aqueous dispersion that contains the primary particles and water to form slurry that contains secondary particles of polytetrafluoroethylene and water or secondary particles of polytetrafluoroethylene floating in water; and adding an organic solvent to at least one of the slurry and the secondary particles of polytetrafluoroethylene floating in water to provide the paste.

First claim

1 . A method of producing a paste, comprising the steps of:
coagulating primary particles of polytetrafluoroethylene in an aqueous dispersion that contains the primary particles and water to form slurry that contains secondary particles of polytetrafluoroethylene and water or secondary particles of polytetrafluoroethylene floating in water; and adding an organic solvent to at least one of the slurry and the secondary particles of polytetrafluoroethylene floating in water to provide the paste.

2 . The production method according to claim 1 ,
wherein the slurry contains not less than 60% by mass of water relative to the secondary particles.

3 . The production method according to claim 1 ,
wherein 14% to 35% by mass of the organic solvent is added relative to the secondary particles of polytetrafluoroethylene.

4 . The production method according to claim 1 ,
wherein the paste contains 14% to 35% by mass of the organic solvent relative to the secondary particles of polytetrafluoroethylene.

5 . The production method according to claim 1 ,
wherein the paste contains 5% to 50% by mass of water relative to the secondary particles of polytetrafluoroethylene.

6 . The production method according to claim 1 , further comprising the step of heating the paste to a temperature higher than the boiling point of water and lower than the boiling point of the organic solvent,
the organic solvent having a boiling point higher than the boiling point of water.

7 . The production method according to claim 6 ,
wherein the paste contains not more than 2.0% by mass of water relative to the secondary particles of polytetrafluoroethylene.

8 . A paste (A) comprising secondary particles of polytetrafluoroethylene and an organic solvent,
the paste (A) satisfying a ratio A/B of not lower than 5, wherein A is an extrusion pressure of a paste (B) at a reduction ratio of 2500 and B is an extrusion pressure of the paste (A) at a reduction ratio of 2500, the paste (B) being obtained by sintering the paste (A) at 250° C. for five hours to provide dry particles and adding the same organic solvent as contained in the paste (A) in the same mass as contained in the paste (A) to the dry particles.

9 . A coated electric wire comprising:
a core wire, and a coating layer covering the core wire, the coating layer being obtainable by extrusion molding of the paste according to claim 8 .

10 . A tube obtainable by extrusion molding of the paste according to claim 8 .

Assignees

• Daikin Ind Ltd

Inventors

• Yoshimoto Hiroyuki
• Yasuda Kohei
• Kawahara Kazuya
• Masuda Haruhisa
• Tsuji Masayuki

Classifications

• H01B13/148 Primary

  Selection of the insulating material therefor · CPC title

• H01B7/0275

  comprising one or more extruded layers of insulation · CPC title

• C09D127/18

  Homopolymers or copolymers of tetrafluoroethene · CPC title

• H01B3/445

  from vinylfluorides or other fluoroethylenic compounds · CPC title

• C08J2327/18

  Homopolymers or copolymers of tetrafluoroethylene · CPC title