E.i. Dupont De Nemours and Company

Daniel N Levy

Fabrice Aubertin

Clay Woodward Jones

Eleni Karayianni

Charles Joseph Noelke

Robert John Cavanaugh

David William Johnson

Theodore Arthur Treat

Kazuo Konabe

Philippe Andre Fernand Thomas

Michael Gene McClusky

A process for reducing the fluorosurfactant content of an aqueous fluoropolymer dispersion by filling a container with fluoropolymer dispersion, inserting into the container a fabric pouch containing a fluorosurfactant sorbent so that the sorbent contacts the fluorosurfactant-containing aqueous fluoropolymer dispersion in the container and retains the fluorosurfactant to reduce fluorosurfactant content of said fluorosurfactant-containing aqueous fluoropolymer dispersion, and removing the fabric pouch from the container.

Process for removing fluorosurfactant from an aqueous fluoropolymer dispersion using sorbent pouches

An aqueous dispersion composition of about 30 to about 70 weight % non-melt-processible fluoropolymer particles having a standard specific gravity (SSG) of less than 2.225 and about 2 to about 11 weight % surfactant based on the weight of said fluoropolymer comprising a compound or mixture of compounds of the formula:R(OCHCH)OHwherein R is a branched alkyl, branched alkenyl, cycloalkyl, or cycloalkenyl hydrocarbon group having 8-18 carbon atoms and n is an average value of 5 to 18. The fluoropolymer particles of the dispersion comprise a core of high molecular weight polytetrafluoroethylene and a shell of lower molecular weight polytetrafluoroethylene or modified polytetrafluoroethylene. Preferably, the aqueous dispersion composition comprises about 45 to about 65 weight % non-melt-processible fluoropolymer particles.

Concentrated fluoropolymer dispersions

This invention relates to an aqueous dispersion of (a) from 0.5 to 99.5 weight percent of a fluoropolymer having an average particle size of from 0.01 to 30 microns; and (b) from 0.5 to 99.5 weight percent of an ethylene copolymer which comprises at least 50% by weight ethylene, 1-35% by weight of an acid-containing unsaturated mono-carboxylic acid, and optionally 0-49% by weight of a moiety selected from at least one of alkyl acrylate, alkyl methacrylate, vinyl ether, carbon monoxide and sulfur dioxide, and further wherein the acid groups are neutralized from 0-100% by a metal ion or other cations, the weight percents being based on the total amounts of (a) and (b) only. The invention also relates to a coprecipate of this aqueous dispersion and a dry powder made by drying the aqueous dispersion or coprecipitate.

Blends of aqueous dispersions of fluoropolymers and aqueous dispersions of ethylene/acid or ionomeric copolymers

An extrusion head for use in the paste extrusion of lubricated PTFE fine powder, the extrusion head comprising an external die having an inlet, a chamber, and an outlet, a tip positioned in the chamber of the die, the tip having a circumferential ridge formed therein that extends into the chamber, the chamber having a shape complementary to the ridge so as to form a space between the external die and the tip to allow lubricated PTFE fine powder to pass therethrough, and a mandrel which extends through the external die and supports the tip in the chamber.

Paste extrusion apparatus

The present invention relates to a process of paste extruding lubricated PTFE fine powder in an extrusion device by forcing the lubricated PTFE fine powder through the extrusion device and out of an orifice as a lubricated green extrudate, wherein before exiting through the orifice, the direction of the flow of the lubricated PTFE fine powder in the extrusion device is reoriented in a direction at least 60 degrees different from the initial direction of the flow of the lubricated PTFE fine powder through the extrusion device.

Paste extrusion method

Paste extrusion of lubricated PTFE fine powder is carried out by using the extrusion head of the extruder as the ram for forcing the powder through the extrusion orifice in the extrusion head, i.e. the extrusion head is moved against the powder, whether in particle form or preform form, to cause the extrusion.

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Tannay, Switzerland

Daniel N Levy