E.i. Dupont De Nemours and Company

Robert John Cavanaugh

Clay Woodward Jones

William Howard Tuminello

David William Johnson

Theodore Arthur Treat

Devin Flowers

Richard A Morgan

Kazuo Konabe

Daniel N Levy

Philippe Andre Fernand Thomas

Walter Thomas Krakowiak

Walter Krakowiak

An aqueous fluoropolymer dispersion comprising fluoropolymer particles having an average particle size of about 10 to about 400 nm. The dispersion has a solids content of at least about 35 to about 70 wt % and comprises about 0.03 wt % to about 10 wt % anionic polyelectrolyte dispersing agent based on the weight of fluoropolymer solids. The dispersion has a Gel Time of at least about 100 seconds.

Concentrated fluoropolymer dispersions stabilized with anionic polyelectrolyte dispersing agents

A stabilized aqueous fluoropolymer dispersion comprising fluoropolymer particles, wherein the dispersion contains less that about 300 ppm fluorosurfactant based on the weight of the dispersion and a cationic surfactant. The cationic surfactant aids in reducing the viscosity of the dispersion and preferred cationic surfactants are volatile in coating or film casting operations involving drying and sintering of the dispersion.

Viscosity control for reduced fluorosurfactant aqueous fluoropolymer dispersions by the addition of cationic surfactants

A process for dispersion spinning non-melt-processible fluoropolymer fiber in which a mixture of an aqueous dispersion of non-melt-processible polytetrafluoroethylene or modified polytetrafluoroethylene fluoropolymer particles and an aqueous solution of matrix polymer is formed. The non melt-processible particles have an SSG of less than about 2.40. The aqueous dispersion contains an aliphatic alcohol ethoxylate nonionic surfactant having a 20% residuals temperature determined by thermogravimetric analysis (TGA) of less than about 290&#xb0; C. and is essentially free of surfactants containing aromatic groups. The dispersion has a fluorinated surfactant content of less than about 300 ppm. The mixture is extruded into a coagulation bath containing a concentration of ions which coagulate the matrix polymer to form an intermediate fiber structure. The intermediate fiber structure is sintered to decompose the matrix polymer and coalesce. The present invention also provides a spinning composition useful for the dispersion spinning of non-melt-processible fluoropolymer fiber.

Spinning low fluorosurfactant fluoropolymer dispersions

The present invention provides a process for making a filled fluoropolymer bearing comprising providing an aqueous fluoropolymer dispersion comprising fluoropolymer particles and anionic polyelectrolyte dispersing agent in an amount sufficient for stabilization. The dispersion contains less than about 300 ppm fluorosurfactant based on the weight of the dispersion. The dispersion is coagulated to make a mush and a bearing filler is added to the dispersion prior to or after making the mush. The mush containing bearing filler is applied onto a bearing substrate to produce a coated substrate which is sintered and formed into a bearing.

Process for forming filled bearings from fluoropolymer dispersions stabilized with anionic polyelectrolyte dispersing agents

Process for forming filled bearings from fluoropolymer dispersions stabilized with anionic polyelectrolyte dispering agents

A process for reducing fluorosurfactant content of a fluorosurfactant-containing aqueous fluoropolymer dispersion stabilized with nonionic surfactant. The process includes reducing the fluorosurfactant content of the stabilized fluorosurfactant-containing aqueous fluoropolymer dispersion to a predetermined level to provide a reduced surfactant dispersion, adding non-fluorinated anionic surfactant to the reduced fluorosurfactant dispersion, and concentrating the reduced fluorosurfactant dispersion. The non-fluorinated anionic surfactant is added in stages wherein a first portion is added to the dispersion prior to concentrating and a second portion of the non-fluorinated anionic surfactant is added to the dispersion after concentrating.

Staged addition of non-fluorinated anionic surfactant to reduced fluorosurfactant fluoropolymer dispersion

An aqueous dispersion of non-melt-processible fluoropolymer, process for making same and concentrated dispersion and powder obtained from the dispersion. The fluoropolymer particles of the dispersion have a standard specific gravity (SSG) of less than 2.225 and comprise a core of high molecular weight polytetrafluoroethylene and a shell of lower molecular weight polytetrafluoroethylene or modified polytetrafluoroethylene. At least about 1.5 weight % of the fluoropolymer particles comprise substantially rod-shaped particles having a length to diameter ratio greater than about 5.

High build dispersions

A process for reducing fluorosurfactant content of a stabilized fluorosurfactant-containing aqueous fluoropolymer dispersion containing ferric ions by contacting the fluoropolymer dispersion with strong base anion exchange resin to reduce fluorosurfactant content to a predetermined level, the anion exchange resin being in the hydroxide form, separating the dispersion from the anion exchange resin, and adding an effective amount of chelating agent having an equilibrium constant when complexed with iron of at least 10prior to the contacting with the ion exchange resin for complexing ferric ions to prevent scum formation.

Process for removing fluorosurfactant from aqueous fluoropolymer dispersions and reducing scum formation

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

Perfluorinated cycloalkane solvents for dissolving high melting polymers containing tetrafluoroethylene, are disclosed. These solvents dissolve such polymers more rapidly, and/or are more stable, than previously known solvents. Also disclosed is a process for dissolution of the polymers and their resulting solutions. The solutions are useful for making polymer films, coatings and for encapsulating objects.

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Cincinnati, OH, United States of America

Robert John Cavanaugh