Polytetrafluoroethylene production method
Provided is a method for producing polytetrafluoroethylene, which includes polymerizing tetrafluoroethylene in an aqueous medium in the presence of a nucleating agent and a polymer (I) containing a polymerization unit (I) based on a monomer represented by the general formula (I) to obtain 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.
1 . A method for producing polytetrafluoroethylene, comprising polymerizing tetrafluoroethylene in an aqueous medium in the presence of a nucleating agent and a polymer (I) containing a polymerization unit (I) based on a monomer represented by the general formula (I) to obtain 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,
primary particles of the polytetrafluoroethylene have an aspect ratio of less than 2.00, and
the nucleating agent is a chain transfer agent and one or both of a nonionic surfactant and fluoropolyether.
2 . The production method according to claim 1 , wherein the anionic group is at least one selected from the group consisting of a sulfate group, a carboxylate group, a phosphate group, a phosphonate group, a sulfonate group, and —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.
3 . The production method according to claim 1 , wherein the polymer (I) has a number average molecular weight of 1.0×10 4 or more.
4 . The production method according to claim 1 , wherein m in the general formula (I) is 1.
5 . The production method according to claim 1 , wherein the chain transfer agent is at least one selected from the group consisting of alcohols having 1 to 4 carbon atoms and alkanes having 2 to 4 carbon atoms.
6 . The production method according to claim 1 , wherein the chain transfer agent is at least one selected from the group consisting of isopropanol, sec-butanol, and tert-butanol.
7 . The production method according to claim 1 , wherein the nonionic surfactant is at least one selected from the group consisting of a nonionic surfactant represented by the general formula (i) and a nonionic surfactant represented by the general formula (ii):
R 3 —O-A 1 -H (i)
wherein R 3 is a linear or branched primary or secondary alkyl group having 8 to 18 carbon atoms, and A 1 is a polyoxyalkylene chain; and
R 4 —C 6 H 4 —O-A 2 -H (ii)
wherein R 4 is a linear or branched primary or secondary alkyl group having 4 to 12 carbon atoms, and A 2 is a polyoxyalkylene chain.
8 . The production method according to claim 1 , wherein the nucleating agent is the chain transfer agent and the nonionic surfactant.
9 . The production method according to claim 1 , wherein tetrafluoroethylene and a modifying monomer are polymerized.
10 . The production method according to claim 1 , wherein the polytetrafluoroethylene is low molecular weight polytetrafluoroethylene.