Method for producing aqueous polytetrafluoroethylene dispersion

Patent metadata

Field	Value
Publication number	US-9580590-B2
Application number	US-201214239910-A
Country	US
Kind code	B2
Filing date	Aug 27, 2012
Priority date	Aug 25, 2011
Publication date	Feb 28, 2017
Grant date	Feb 28, 2017

Abstract

The present invention aims to provide a novel method for producing an aqueous dispersion containing non-melt-processable polytetrafluoroethylene particles. The present invention relates to a method for producing an aqueous dispersion containing non-melt-processable polytetrafluoroethylene particles, the method including polymerizing tetrafluoroethylene in an aqueous medium in the presence of perfluoro hexanoic acid or its salt.

First claim

The invention claimed is:

1. A method for producing an aqueous dispersion containing non-melt-processable polytetrafluoroethylene particles, the method comprising
polymerizing tetrafluoroethylene in an aqueous medium in the presence of perfluoro hexanoic acid or its salt,
wherein tetrafluoroethylene is polymerized further in the presence of a nonionic surfactant (2),
wherein the nonionic surfactant (2) is a fluorine-free nonionic surfactant.

2. A method for producing an aqueous dispersion containing non-melt-processable polytetrafluoroethylene particles, the method comprising
polymerizing tetrafluoroethylene in an aqueous medium in the presence of perfluoro hexanoic acid or its salt,
wherein tetrafluoroethylene is polymerized further in the presence of fluoropolyether acid having a molecular weight of at least 800 g/mol or its salt (1), and
wherein the amount of the fluoropolyether acid or its salt (1) is 10 to 100 ppm based on the amount of the aqueous medium.

3. The method according to claim 2 ,
wherein the fluoropolyether acid or its salt (1) has at least one repeated structure selected from the group consisting of repeated structures represented by the formulae (1a) to (1d):
(—CFCF 3 —CF 2 —O—) n   (1a);

(—CF 2 —CF 2 —CF 2 —O—) n   (1b);

(—CF 2 —CF 2 —O—) n —(—CF 2 —O—) m   (1c); and

(—CF 2 —CFCF 3 —O—) n —(—CF 2 —O—) m   (1d),

 wherein m and n each represent an integer of 1 or more.

4. The method according to claim 2 ,
wherein the fluoropolyether acid or its salt (1) is a carboxylic acid or its salt, and has repeated structures represented by the formulae (1a):
(—CFCF 3 —CF 2 —O—) n   (1a);

wherein n represent an integer of 1 or more.

5. A method for producing an aqueous dispersion containing non-melt-processable polytetrafluoroethylene particles, the method comprising
polymerizing tetrafluoroethylene in an aqueous medium in the presence of perfluoro hexanoic acid or its salt,
wherein tetrafluoroethylene is polymerized further in the presence of a comonomer (3) having a monomer reactivity ratio of 0.1 to 8,
the amount of the comonomer (3) is 0.001 to 0.01% by mass based on the net amount of the produced polytetrafluoroethylene.

6. The method according to claim 5 ,
wherein the comonomer (3) is at least one selected from the group consisting of comonomers represented by the formulae (3a) to (3d):
CH 2 ═CH—Rf 1   (3a),

wherein Rf 1 represents a C1-C10 perfluoroalkyl group;
CF 2 ═CF—O—Rf 2   (3b),

wherein Rf 2 represents a C1-C2 perfluoroalkyl group;
CF 2 ═CF—O—(CF 2 ) n CF═CF 2   (3c),

wherein n represents 1 or 2;

wherein X 3 and X 4 each represent F, Cl, or a methoxy group, and Y is represented by the formula Y1 or Y2; and

wherein Z and Z′ each represent F or a C1-C3 fluorinated alkyl group.

7. A method for producing an aqueous dispersion containing non-melt-processable polytetrafluoroethylene particles, the method comprising
polymerizing tetrafluoroethylene in an aqueous medium in the presence of perfluoro hexanoic acid or its salt,
wherein tetrafluoroethylene is polymerized further in the presence of a reactive emulsifier (4),
wherein the reactive emulsifier (4) is at least one selected from the group consisting of compounds represented by the formulae (4a) to (4e):
CF 2 ═CF—(CF 2 ) n1 —Y 3   (4a),

wherein n1 represents an integer of 1 to 10, Y 3 represents —SO 3 M 1 or —COOM 1 , M 1 represents H, NH 4 , or an alkali metal;
CF 2 ═CF—(CF 2 C(CF 3 )F) n2 —Y 3   (4b),

wherein n2 represents an integer of 1 to 5, and Y 3 is as defined above;
CF 2 ═CF—O—(CFX 1 ) n3 —Y 3   (4c),

wherein X 1 represents F or CF 3 , n3 represents an integer of 1 to 10, and Y 3 is as defined above;
CF 2 ═CF—O—(CF 2 CFX 1 O) n4 —CF 2 CF 2 —Y 4   (4d),

wherein n4 represents an integer of 1 to 10, Y 4 represents —SO 3 M 2 or —COOM 2 , M 2 represents NH 4 or an alkali metal, and X 1 is as defined above; and
CX 2 2 ═CFCF 2 —O—(CF(CF 3 )CF 2 O) n5 —CF(CF 3 )—Y 3   (4e),

wherein X 2 s are the same as one another and represent F or H, n5 represents an integer of 0 or 1 to 10, and Y 3 is as defined above.

Assignees

• Taira Takahiro
• Yamanaka Taku
• Nanba Yoshinori
• Tanaka Atsuko
• Ono Makoto
• Tsuda Nobuhiko
• Kato Taketo
• Daikin Ind Ltd

Inventors

• Taira Takahiro
• Yamanaka Taku
• Nanba Yoshinori
• Tanaka Atsuko
• Ono Makoto
• Tsuda Nobuhiko
• Kato Taketo

Classifications

• C08F2/26

  anionic · CPC title

• C08F114/26 Primary

  Tetrafluoroethene · CPC title

• C08F214/26

  Tetrafluoroethene · CPC title

• C08F2/24

  with the aid of emulsifying agents · CPC title

• C08F214/262

  with fluorinated vinyl ethers · CPC title