Production method of modified polytetrafluoroethylene and composition

Patent metadata

Field	Value
Publication number	US-12435213-B2
Application number	US-201917293591-A
Country	US
Kind code	B2
Filing date	Nov 19, 2019
Priority date	Nov 19, 2018
Publication date	Oct 7, 2025
Grant date	Oct 7, 2025

Abstract

A method for producing modified polytetrafluoroethylene including: polymerizing tetrafluoroethylene and a modifying monomer in an aqueous medium in the presence of a polymer (I) containing a polymerization unit (I) based on a monomer represented by the following general formula (I) to obtain a modified polytetrafluoroethylene:

CX 1 X 3 =CX 2 R(—CZ 1 Z 2 -A 0 ) m   (I)

wherein X 1 and X 3 are each independently F, Cl, H, or CF 3 ; X 2 is H, F, an alkyl group, or a fluorine-containing alkyl group; A 0 is an anionic group; R is a linking group; Z 1 and Z 2 are each independently H, F, an alkyl group, or a fluorine-containing alkyl group; and m is an integer of 1 or more. Also disclosed is a composition containing the modified polytetrafluoroethylene and the polymer (I).

First claim

The invention claimed is:

1. A method for producing modified polytetrafluoroethylene comprising:
polymerizing tetrafluoroethylene and a modifying monomer in an aqueous medium in the presence of a polymer (I) containing a polymerization unit (I) based on a monomer represented by the following general formula (I), a content of the polymerization unit (I) in the polymer (I) being 80 mol % or more based on all polymerization units, and substantially in the absence of a fluorine-containing surfactant to obtain a modified polytetrafluoroethylene:
CX 1 X 3 =CX 2 R(—CZ 1 Z 2 -A 0 ) m   (I)

wherein X 1 and X 3 are each independently F, Cl, H, or CF 3 ;
X 2 is H, F or CF 3 ;
A 0 is an anionic group;
R is a linking group;
Z 1 and Z 2 are each independently H, F, an alkyl group, or a fluorine-containing alkyl group; and
m is 1.

2. The production method according to claim 1 , further comprising:
adding the modifying monomer before the initiation of polymerization or when the concentration of particles of the modified polytetrafluoroethylene formed in the aqueous medium is 5.0% by mass or less.

3. The production method according to claim 1 , wherein the total amount of the modifying monomer is 0.000010% by mass or more based on the obtained modified polytetrafluoroethylene.

4. The production method according to claim 1 , wherein the total amount of the modifying monomer is 1.0% by mass or less based on the obtained modified polytetrafluoroethylene.

5. The production method according to claim 1 , wherein the modifying monomer includes at least one selected from the group consisting of hexafluoropropylene, a perfluoro(alkyl vinyl ether) and a (perfluoroalkyl)ethylene.

6. The production method according to claim 1 , wherein the modifying monomer is a compound represented by the following general formula (4):
CX i X k =CX j R a —(CZ 1 Z 2 ) k —Y 3   (4)

wherein X i , X j , and X k are each independently F, Cl, H, or CF 3 ; Y 3 is a hydrophilic group; R a is a linking group; Z 1 and Z 2 are each independently H, F, or CF 3 ; and k is 0 or 1.

7. The production method according to claim 1 , wherein in the polymerization, tetrafluoroethylene and the modifying monomer are polymerized further in the presence of a nucleating agent.

8. The production method according to claim 7 , wherein the nucleating agent is a nonionic surfactant.

9. The production method according to claim 1 , wherein the modified polytetrafluoroethylene has an average primary particle size of 500 nm or less.

10. The production method according to claim 1 , wherein the modified polytetrafluoroethylene has an aspect ratio of primary particles of less than 2.00.

11. The production method according to claim 1 , wherein the anionic group is an anionic group that is a sulfate group, a carboxylate group, a phosphate group, a phosphonate group, a sulfonate group, or —C(CF 3 ) 2 OM wherein M is —H, a metal atom, —NR 7 4 , imidazolium optionally having a substituent, pyridinium optionally having a substituent, or phosphonium optionally having a substituent, and R 7 is H or an organic group.

12. A composition comprising:
a modified polytetrafluoroethylene; and
a polymer (I) containing a polymerization unit (I) based on a monomer represented by the following general formula (I):
CX 1 X 3 =CX 2 R(—CZ 1 Z 2 -A 0 ) m   (I)

wherein X 1 and X 3 are each independently F, Cl, H, or CF 3 ; X 2 is H, F or CF 3 ; A 0 is an anionic group; R is a linking group; Z 1 and Z 2 are each independently H, F, an alkyl group, or a fluorine-containing alkyl group; and m is 1,
wherein a content of the polymerization unit (I) in the polymer (I) is 80 mol % or more based on all polymerization units,
which is substantially free from a fluorine-containing surfactant.

13. The composition according to claim 12 , having a breaking strength of 10.0 N or more.

14. The composition according to claim 12 , having a stress relaxation time of 50 seconds or more.

15. The composition according to claim 12 , having an extrusion pressure of 10.0 MPa or more and 30.0 MPa or less.

16. The composition according to claim 12 , having an endothermic peak temperature in the range of 333 to 347° C.

17. The composition according to claim 12 , having a standard specific gravity of 2.250 or less.

18. The composition according to claim 12 , wherein the modified polytetrafluoroethylene has an aspect ratio of primary particles of less than 2.00.

19. The composition according to claim 12 , wherein the anionic group is an anionic group that is a sulfate group, a carboxylate group, a phosphate group, a phosphonate group, a sulfonate group, or —C(CF 3 ) 2 OM wherein M is —H, a metal atom, —NR 7 4 , imidazolium optionally having a substituent, pyridinium optionally having a substituent, or phosphonium optionally having a substituent, and R 7 is H or an organic group.

20. The composition according to claim 12 , which is a powder.

Assignees

• Daikin Ind Ltd

Inventors

• Nanba Yoshinori
• Ichikawa Kenji
• Fujimoto Yohei
• Yoshida Hirotoshi
• Sato Hiroyuki
• Kato Taketo
• Ito Kengo
• Yamanaka Taku

Classifications

• C08L2205/24

  Crystallisation aids · CPC title

• C08L2205/14

  containing polymeric additives characterised by shape · CPC title

• C08L29/10

  Homopolymers or copolymers of unsaturated ethers (C08L35/08 takes precedence) · CPC title

• C08F2800/20

  as weight or mass percentages · CPC title

• C08F214/262

  with fluorinated vinyl ethers · CPC title