# US 12,760,131 B2 · Method for producing polytetrafluoroethylene

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- Number: US 12,760,131 B2
- Document ID: US12760131B2
- Status: Granted
- Kind: B2
- Application number: 17/424,715
- Filed: 2020-01-31
- Published: 2022-04-21
- Granted: 2026-10-13
- Earliest claimed: 2019-02-01
- Assignees: Daikin Industries, Ltd.
- Applicants: Daikin Industries, Ltd.
- Inventors: Taketo Kato; Yohei Fujimoto; Kenji Ichikawa; Hiroyuki Sato; Yoshinori Nanba; Hirotoshi Yoshida; Kengo Ito; Taku Yamanaka
- Web page: https://patentgrep.com/patent/US12760131B2

## CPC

- C08F 114/26: Tetrafluoroethene
- C08F: MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS

## Abstract

A method for producing polytetrafluoroethylene includes a step of polymerizing tetrafluoroethylene in an aqueous medium in the presence of a hydrocarbon surfactant and a polymerization initiator to obtain polytetrafluoroethylene and a step of adding at least one selected from the group consisting of a radical scavenger and a decomposer of a polymerization initiator after the initiation of polymerization.

## Claims

### Claim 1

A method for producing polytetrafluoroethylene comprising:
polymerizing tetrafluoroethylene in an aqueous medium in the presence of a hydrocarbon surfactant and a polymerization initiator to obtain a polytetrafluoroethylene; and
adding at least one selected from the group consisting of a radical scavenger and a decomposer of the polymerization initiator after an initiation of polymerization,
wherein an amount of the radical scavenger added is an amount corresponding to 5 to 100% (molar basis) of a polymerization initiator concentration,
an amount of the decomposer of the polymerization initiator added is an amount corresponding to 5 to 100% (molar basis) of a polymerization initiator concentration, and
in the polymerization, tetrafluoroethylene is polymerized substantially in the absence of a fluorine-containing surfactant.

### Claim 2 (depends on 1)

The method according to claim 1, wherein the at least one selected from the group consisting of the radical scavenger and the decomposer of the polymerization initiator is added when the concentration of the polytetrafluoroethylene formed in the aqueous medium is 5% by mass or more.

### Claim 3 (depends on 1)

The method according to claim 1, wherein the radical scavenger is at least one selected from the group consisting of an aromatic hydroxy compound, an aromatic amine, N,N-diethylhydroxylamine, a quinone compound, a terpene, a thiocyanate, and cupric chloride (CuCl2).

### Claim 4 (depends on 1)

The method according to claim 1, wherein the decomposer of the polymerization initiator is at least one selected from the group consisting of a sulfite, a bisulfite, a bromate, diimine, a diimine salt, oxalic acid, an oxalate, a copper salt, and an iron salt.

### Claim 5 (depends on 1)

The method according to claim 1, wherein the polymerization initiator is an oil-soluble radical polymerization initiator or a water-soluble radical polymerization initiator.

### Claim 6 (depends on 1)

The method according to claim 1, wherein the hydrocarbon surfactant is a carboxylic acid-type hydrocarbon surfactant.

### Claim 7 (depends on 1)

The method according to claim 1, wherein the polytetrafluoroethylene is stretchable.

### Claim 8 (depends on 1)

The method according to claim 1, wherein the radical scavenger is at least one selected from the group consisting of N,N-diethylhydroxylamine, a quinone compound, a terpene, a thiocyanate, and cupric chloride (CuCl2).

### Claim 9 (depends on 1)

The method according to claim 1, wherein a standard specific gravity (SSG) of the polytetrafluoroethylene is 2.180 or less.