POLYTETRAFLUOROETHYLENE AND METHOD FOR PRODUCING SAME

• US 20120028046A1
• Filed: 03/30/2010
• Published: 02/02/2012
• Est. Priority Date: 03/30/2009
• Status: Active Grant

• Current Assignee: Daikin Industries Ltd
• Original Assignee: Daikin Industries Ltd
• Inventors: Ono, Makoto, Sato, Hiroyuki, Sawauchi, Chie, Kato, Taketo
• Granted Patent: US 11,827,724 B2
• Time in Patent Office: Days
• US Class Current: 428/402
• CPC Class Codes: C08F 114/26 Tetrafluoroethene
• CPC Class Codes: C08F 14/26 Tetrafluoroethene
• CPC Class Codes: C08F 2/22 Emulsion polymerisation
• CPC Class Codes: C08F 2/24 with the aid of emulsifying agents
• CPC Class Codes: C08F 2/26 anionic
• CPC Class Codes: Y10T 428/2982 Particulate matter [e.g., sphere, flake, etc.]

Abstract

It is an object of the present invention to provide polytetrafluoroethylene suitable for forming a porous polytetrafluoroethylene film using a high water-soluble surfactant with high volatility. Polytetrafluoroethylene has non-melt-secondary-processability, standard specific gravity of 2.160 or less, an average primary particle size of 150 nm or more, stress relaxation time of 500 seconds or more, and break strength of 29.7 N or more. The polytetrafluoroethylene is obtainable by emulsion polymerization of tetrafluoroethylene in the presence of a fluorinated surfactant with LogPOW of 3.4 or less.

Claims

1. Polytetrafluoroethylene, having non-melt-secondary-processability, standard specific gravity of 2.160 or less, an average primary particle size of 150 nm or more, stress relaxation time of 500 seconds or more, and break strength of 29.7 N or more, the polytetrafluoroethylene being obtainable by emulsion polymerization of tetrafluoroethylene in the presence of a fluorinated surfactant with LogPOW of 3.4 or less.

2. The polytetrafluoroethylene according to claim 1, wherein the break strength is 32.0 to 49.0 N.

3. The polytetrafluoroethylene according to claim 1,

wherein the fluorinated surfactant is at least one selected from the group consisting of:

a compound represented by general formula CF₃OCF(CF₃)CF₂OCF(CF₃)COOX, in the formula, X being a hydrogen atom, NH₄, or an alkali metal atom; and

a compound represented by general formula CF₃CF₂OCF₂CF₂OCF₂COOX, in the formula, X being a hydrogen atom, NH₄, or an alkali metal atom.

4. A production method of polytetrafluoroethylene, comprising the steps of:

feeding a fluorinated surfactant with LogPOW of 3.4 or less, water, and tetrafluoroethylene in a polymerization vessel;

feeding a redox initiator to the polymerization vessel to initiate emulsion polymerization of the tetrafluoroethylene; and

recovering polytetrafluoroethylene,

wherein a total feed amount of the fluorinated surfactant is 1000 to 6000 ppm to a final polytetrafluoroethylene yield.

5. The production method according to claim 4,

wherein the fluorinated surfactant is at least one selected from the group consisting of:

a compound represented by general formula CF₃OCF(CF₃)CF₂OCF(CF₃)COOX, in the formula, X being a hydrogen atom, NH₄, or an alkali metal atom; and

a compound represented by general formula CF₃CF₂OCF₂CF₂OCF₂COOX, in the formula, X being a hydrogen atom, NH₄, or an alkali metal atom.