The Harshaw Chemical Company

J William Vogt

James E Owen

A coherent, weak agglomerated dustless solid particulate mass is formed from a mixture of discrete particles in the size range from less than about 1 micron to about 2,000 microns, and fibrillatable polytetrafluoroethylene (hereinafter referred to as PTFE) in an amount from about 0.02, but less than 1 percent and preferably less than 0.75 percent by weight based on total solids, by working the mixture in a dry or relatively dry state with a working action in an unconfined zone at a temperature in excess of 20.degree. C., but below the sintering temperature of PTFE or a temperature deleterious to said particles, whichever is lower, without changing the primary particle size range of the material.

Agglomerate containing fibrous polytetrafluoroethylene

A method is disclosed for preventing segregation of particles within a finely divided powder having disparate particle size ranges, compositions or densities. The method includes working the powder with a minute amount, preferably less than about 1% by weight of the powder, of a finely divided fibrillatable polytetrafluoroethylene resin (hereinafter referred to as PTFE) to form a mixture with the powder. The PTFE resin may be added to the powder as a colloidal aqueous dispersion or as a fine powder obtained by coagulation of the colloidal dispersion. Whichever form is used, the PTFE is intimately mixed with the finely divided powder to form a dry mixture. Alternatively, the PTFE resin may be blended with the powder in a wet treatment to facilitate the homogenous dispersion of the resin. In any event, the mixture of resin and powder is worked either in the wet state, preferably as a paste, or as a dry blend, using a masticating or kneading action to fibrillate the PTFE. Sufficient working is carried out to produce a random network of PTFE fibers sufficient to loosely entrap the powdery material and to prevent segregation thereof.

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South Russell, OH, United States of America

J William Vogt