PRODUCTION METHOD FOR POLYTETRAFLUOROETHYLENE AQUEOUS DISPERSION

• US 20150299341A1
• Filed: 12/02/2013
• Published: 10/22/2015
• Est. Priority Date: 11/30/2012
• Status: Active Grant

• Current Assignee: Daikin Industries Ltd
• Original Assignee: Daikin Industries Ltd
• Inventors: NANBA, Yoshinori
• Granted Patent: US 9,574,020 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: C08F 14/18 Monomers containing fluorine
• CPC Class Codes: C08F 2/10 Aqueous solvent
• CPC Class Codes: C08F 2/26 anionic
• CPC Class Codes: C08L 2201/54 Aqueous solutions or dispersions
• CPC Class Codes: C08L 27/18 Homopolymers or copolymers or tetrafluoroethene

Abstract

The present invention aims to provide a method of producing a fluoropolymer aqueous dispersion having a significantly small particle size and excellent dispersion stability without using a long-chain fluorosurfactant. The present invention relates to a method of producing an aqueous dispersion containing at least one fluoropolymer selected from the group consisting of polytetrafluoroethylene and melt-processible fluororesins excluding polytetrafluoroethylene. The method includes polymerizing a fluoromonomer in an aqueous medium in the presence of a fluorosurfactant having a Log POW value of not higher than 3.4 and a polymerization initiator. The amount of the fluorosurfactant corresponds to 4600 to 500000 ppm of the aqueous medium.

Claims

1. A method of producing an aqueous dispersion containing at least one fluoropolymer selected from the group consisting of polytetrafluoroethylene and melt-processible fluororesins excluding polytetrafluoroethylene, the method comprising

polymerizing a fluoromonomer in an aqueous medium in the presence of a fluorosurfactant having a Log POW value of not higher than 3.4 and a polymerization initiator,

the amount of the fluorosurfactant corresponding to 4600 to 500000 ppm of the aqueous medium.

2. The method of producing a fluoropolymer aqueous dispersion according to claim 1,

wherein the fluorosurfactant is a fluorinated compound represented by the following formula (1):

X—

(CF₂)_m1—

Y 

 

(1)

wherein X represents H or F;

m1 is an integer of 3 to 5; and

Y represents —

SO₃M, —

SO₄M, —

SO₃R, —

SO₄R, —

COOM, —

PO₃M₂, or —

PO₄M₂, where M represents H, NH₄, or an alkali metal, and R represents a C1-C12 alkyl group.

3. The method of producing a fluoropolymer aqueous dispersion according to claim 1,

wherein the polymerization is performed in the absence of a fluorinated compound represented by the following formula (2):

X—

(CF₂)_m2—

Y 

 

(2)

wherein X represents H or F;

m2 is an integer of 6 or greater; and

Y represents —

SO₃M, —

SO₄M, —

SO₃R, —

SO₄R, —

COOM, —

PO₃M₂, or —

PO₄M₂, where M represents H, NH₄, or an alkali metal, and R represents a C1-C12 alkyl group.

4. The method of producing a fluoropolymer aqueous dispersion according to claim 1,

wherein the fluoropolymer has a volume average particle size of not smaller than 0.1 nm but smaller than 20 nm.

5. The method of producing a fluoropolymer aqueous dispersion according to claim 1,

wherein the polymerization initiator is at least one selected from the group consisting of persulfates and organic peroxides.

6. The method of producing a fluoropolymer aqueous dispersion according to claim 1,

wherein the amount of the polymerization initiator corresponds to 1 to 5000 ppm of the aqueous medium.