# US 9,518,170 B2 · Aqueous polymerization of perfluoromonomer using hydrocarbon surfactant

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- Number: US 9,518,170 B2
- Document ID: US9518170B2
- Status: Granted
- Kind: B2
- Application number: 14/992,421
- Filed: 2016-01-11
- Published: 2016-05-05
- Granted: 2016-12-13
- Earliest claimed: 2010-11-09
- Assignees: The Chemours Company Fc, LLC
- Applicants: The Chemours Company Fc, LLC
- Inventors: Paul Douglas Brothers; Subhash Vishnu Gangal; Dipti Dilip Khasnis
- Web page: https://patentgrep.com/patent/US9518170B2

## CPC

- C08F 2/16: Aqueous medium
- C08F 14/18: Monomers containing fluorine
- C08F 14/26: Tetrafluoroethene
- C08K 5/41: Compounds containing sulfur bound to oxygen
- C09D 127/18: Homopolymers or copolymers of tetrafluoroethene
- C08F: MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08K: Use of inorganic or non-macromolecular organic substances as compounding ingredients (paints, inks, varnishes, dyes, polishes, adhesives C09)
- C09D: COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR (cosmetics A61K; processes for applying liquids or other fluent materials to surfaces, in general, B05D; staining wood B27K5/02; glazes or vitreous enamels C03C; natural resins, French polish, drying-oils, driers, turpentine, per se, C09F; polishing compositions other than French polish, ski waxes C09G; adhesives or use of materials as adhesives C09J; materials for sealing or packing joints or covers C09K3/10; materials for stopping leaks C09K3/12; processes for the electrolytic or electrophoretic production of coatings C25D)

## Abstract

A process is provided for the polymerization of fluoromonomer to an dispersion of fluoropolymer particles in an aqueous medium in a polymerization reactor, by (a) providing the aqueous medium in the reactor, (b) adding the fluoromonomer to the reactor, (c) adding initiator to the aqueous medium, the combination of steps (b) and (c) being carried out essentially free of hydrocarbon-containing surfactant and resulting in the kickoff of the polymerization of the fluoromonomer, and (d) metering hydrocarbon-containing surfactant into the aqueous medium after the kickoff of polymerization, e.g. after the concentration of the fluoropolymer in the aqueous medium is at least 0.6 wt %, the metering being at a rate reducing the telogenic activity of said surfactant while maintaining surface activity.

## Claims

### Claim 1

Process for polymerizing one or more fluoromonomers to form a dispersion of fluoropolymer particles in an aqueous medium in a polymerization reactor, wherein the fluoropolymer is selected from the group consisting of polytetrafluoroethylene, modified polytetrafluoroethylene, and melt-processible copolymer comprising at least 40-99 mol % tetrafluoroethylene units and about 1-60 mol % of at least one other monomer, said process comprising
(a) providing an aqueous medium in said reactor,
(b) adding said one or more fluoromonomers to said reactor,
(c) adding polymerization initiator to said aqueous medium to commence polymerizing of said one or more fluoromonomers,
(d) metering hydrocarbon surfactant into said aqueous medium during the polymerization at a metering rate of at least 0.005 g/l-hr and that provides an amount of hydrocarbon surfactant in the aqueous medium sufficient to stabilize the dispersion of fluoropolymer particles formed during polymerization, wherein 100% of the monovalent substituents on the carbon atoms of the hydrocarbon surfactant are hydrogen, said metering of hydrocarbon surfactant being commenced when the concentration of said fluoropolymer in said aqueous medium is at least 0.6 wt %, and
said process further comprising providing polymerization sites dispersed in said aqueous medium prior to commencement of polymerization, said polymerization sites forming loci for the precipitation of fluoropolymer, wherein said aqueous medium contains no fluorosurfactant or contains an amount of fluorosurfactant insufficient to stabilize the dispersion of fluoropolymer particles formed during polymerization.

### Claim 2 (depends on 1)

The process of claim 1 wherein said metering of hydrocarbon surfactant is at a rate that reduces the telogenic activity of the hydrocarbon surfactant.

### Claim 3 (depends on 1)

The process of claim 1 wherein the metering of said hydrocarbon surfactant into said aqueous medium is carried out at a rate of 0.005 to 1.4 g/l-hr.

### Claim 4 (depends on 1)

The process of claim 1 wherein after said metering of hydrocarbon surfactant is commenced, said metering of hydrocarbon surfactant is continuous throughout the polymerization.

### Claim 5 (depends on 1)

The process of claim 1 wherein said polytetrafluoroethylene and modified polytetrafluoroethylene have no melt flow when measured in accordance with ASTM D-1238 using a 5 kg weight and said melt-processible copolymer has a melt flow rate of 0.1 to 200 g/10 min. when measured in accordance with ASTM D-1238 using a 5 kg weight.

### Claim 6 (depends on 1)

The process of claim 1 wherein said hydrocarbon surfactant is anionic.

### Claim 7 (depends on 1)

The process of claim 1 wherein said hydrocarbon surfactant is a compound of the formula R-L-M wherein R is an alkyl group containing from 6 to 17 carbon atoms, L is selected from the group consisting of —ArSO3−, —SO3−, —SO4−, —PO3− and —COO−, wherein Ar is an aryl group, and M is a univalent cation selected from H+, Na+, K+ and NH4+.

### Claim 8 (depends on 1)

The process of claim 1 wherein said hydrocarbon surfactant is sodium lauryl sulfate.

### Claim 9 (depends on 1)

The process of claim 1 wherein said fluoropolymer is polytetrafluoroethylene and said polymerizing is carried out to wherein said dispersion of polytetrafluoroethylene particles constitute 45 wt % or greater than 45 wt % of said aqueous medium.

### Claim 10 (depends on 9)

The process of claim 9 wherein said total amount of said hydrocarbon surfactant metered into said aqueous medium is 3000 ppm or greater than 3000 ppm, based on the weight of said polytetrafluoroethylene particles.

### Claim 11 (depends on 1)

The process of claim 1 further comprising passivating said hydrocarbon surfactant.

### Claim 12 (depends on 1)

The process of claim 1 wherein said polymerization sites dispersed in said aqueous medium are hydrocarbon-containing.

### Claim 13 (depends on 12)

The process of claim 12 wherein said hydrocarbon-containing polymerization sites dispersed in said aqueous medium are made by adding no more than 50 ppm of a water-soluble hydrocarbon-containing compound to said aqueous medium and degrading said hydrocarbon-containing compound to form said polymerization sites.

### Claim 14 (depends on 13)

The process of claim 13 wherein said aqueous medium comprising said hydrocarbon-containing polymerization sites contains no more than 50 ppm of halogen-containing surfactant.

### Claim 15 (depends on 13)

The process of claim 13 wherein after said degrading of said hydrocarbon-containing compound said aqueous medium comprising said hydrocarbon-containing polymerization sites contains no more than 40 ppm of said hydrocarbon-containing compound.

### Claim 16 (depends on 13)

The process of claim 13 wherein said water-soluble hydrocarbon-containing compound is hydrocarbon surfactant.

### Claim 17 (depends on 16)

The process of claim 16 wherein after said degrading of said hydrocarbon surfactant said aqueous medium comprising said polymerization sites contains no more than 50 ppm of surfactant.

### Claim 18 (depends on 1)

The process of claim 1 wherein no halogen-containing surfactant is added to said aqueous medium during the process.