Ecc International Limited

Imerys Pigments, Inc.

William H Pope

Robert J Pruett

Jun Yuan

Anthony V Lyons

Michael W Ginn

Christopher R L Golley

William L Garforth

Rajan R Iyer

Christopher Nutbeem

R Brock McNeely

Randolph O Smith

Raymond Brock McNeely

A kaolin clay pigment comprises a coarse kaolin clay or a blend of a coarse kaolin clay with a fine kaolin clay. The coarse kaolin clay is a delaminated and defined pigment product with an overall shape factor greater than about 12. If the coarse kaolin clay is fluid at about 65% to about 75% solids, then it is used by itself as the kaolin pigment. If it is not fluid, it is blended with a fine kaolin clay in amounts ranging from about 0.1% to about 30.0% by weight of the blend. The coarse kaolin clay fraction has a Hinckley Crystallinity Index greater than about 0.6 and the fine kaolin clay has a Hinckley Crystallinity Index less than about 0.5. The pigment has a G.E. brightness of about 90.5 and a particle size distribution such that at least about 90% by weight of the particles has an e.s.d. less than about 2 &mgr;m and about 30% by weight of the particles has an e.s.d. less than about 0.25 microns. At about 65% to about 75% solids, the Hercules viscosity is greater than 250 rpm at about 18 dynes and when used in a coating formulation, exhibits improved sheet brightness, sheet gloss, sheet opacity and print gloss.

Kaolin clay pigment for paper coating and method for producing same

An improved method for dry milling calcined kaolin clays involves use of an effective amount of an ammonium polyacrylate dry grinding aid which is applied to a calcined kaolin clay product prior to dry milling. This improves flowability of the product through the mill, resulting in an increase in the grinding efficiency and, therefore, an increase in the production rate of the mill. The final product displays an increase in Hercules high shear viscosity, and therefore, an increase in the rheology in very high solids aqueous slurries, which is particularly useful in the coating of paper and paperboard products.

Dry grinding aid for dry milling a calcined kaolin clay and a related

A process for preparing a high brightness, low abrasion calcined kaolin. A cretaceous crude is wet beneficiated by subjecting same as an aqueous slurry to degritting, classification, magnetic separation, and scrub grinding. The slurry from the foregoing is diluted to less than 15% solids and subjected while well dispersed to a separation in a centrifuge to yield an underflow and an overflow fine fraction having less than 5% solids and a P.S.D. such that at least 85% by weight are of &lt;0.5 .mu.m E.S.D. and at least 30% by weight are of &lt;0.25 .mu.m E.S.D. The overflow fine fraction slurry of dispersed kaolin is subjected to a partial filtration by passing same in cross flow relation to a microporous membrane through which substantially none of the suspended kaolin particles pass, to raise the solids content of the said slurry to at least 20%. This slurry is combined with up to 90% on a dry weight basis of a slurry of a fine particle size tertiary kaolin, and is then bleached, flocculated and filtered to yield a filter cake, which is redispersed, dried and milled to provide a calciner feed. The feed is calcined at temperatures above the kaolin exotherm to yield a calcined product having a brightness of at least 92 and an Einleiner Abrasion less than 24.

Method for producing high brightness low abrasion calcined kaolin pigment

A method for producing calcined kaolin pigments of high opacifying properties and low abrasion. A kaolin crude is selected having a G.E. brightness in the range of 70 to 80, a titania content of 2.0 to 3.0% by weight, less than 2% iron expressed as Fe.sub.2 O.sub.3, and a particle size distribution such that at least 88% by weight of the particles of said crude are of less than 2 .mu.m E.S.D.. The crude is blunged with water, and the resultant slurry degritted to form an aqueous slurry having at least 65% by weight solids. The slurry is centrifuged and a fraction recovered having over 65% solids, and in which at least 92% by weight of the particles are of less than 2 .mu.m. The recovered fraction is dried to less than 1% moisture, and pulverized to break up agglomerates. The pulverized fraction is then calcined by heating same to 1450.degree. to 1600.degree. F. after which the calcined kaolin is milled to yield a product having a G.E. brightness of 79 to 81 and an Einleiner abrasion of not mere than 2.5 mg wt loss.

Method for producing high opacifying kaolin pigment

Growing community of inventors

Sandersville, GA, United States of America

William H Pope