Imerys Pigments, Inc.

Daniel John Panfil

Robert J Pruett

John Claude Husband

Jun Yuan

Anthony V Lyons

Christopher R L Golley

David O Cummings

William L Garforth

Steven M Fortier

Harry Vincent Brown, Jr

David Robert Skuse

Rajan R Iyer

Christopher Nutbeem

Mark Mortimer

Deb Thrale

The present disclosure relates to a coating composition for use in producing a coating on paper and other substrates comprising an aqueous suspension of a particulate pigment together with a binder, wherein the particulate pigment comprises a mixture of: a first pigment component comprising particulate ground calcium carbonate (GCC) having a particle size distribution (psd) steepness factor ranging from about 30 to about 45; and a second pigment component comprising particulate precipitated calcium carbonate (PCC) having a psd steepness factor ranging from about 55 to about 75. The particulate pigment may optionally further include a particulate kaolin clay.

Paper coating pigments

A pigment product suitable for use in a coating composition to provide a gloss coating on paper, the pigment product comprising a processed particulate kaolin produced from a naturally platy kaolin clay having a particle size distribution such that about 50% to 60% by weight of the particles have an esd less than 2 &mgr;m and less than 25% by weight of the particles have an esd less than 0.25 &mgr;m and a shape factor of at least 15. In processing, the crude kaolin is ground to a shape factor greater than 50 to produce even greater &ldquo;platy&rdquo; clay. The pigment product has a particle size distribution such that at least 80% by weight of the particles have an esd less than 2 &mgr;m and greater than 12% and less than 35% by weight of the particles have an esd less than 0.25 &mgr;m and whose surface area is greater than 12 m /g when measured by the BET method.

Kaolin pigments, their preparation and use

A pigment product suitable for use in a coating composition to provide a gloss coating on paper, the pigment product comprising a processed particulate kaolin produced from a naturally platy kaolin clay having a particle size distribution such that about 50% to 60% by weight of the particles have an esd less than 2 &mgr;m and less than 25% by weight of the particles have an esd less than 0.25 &mgr;m and a shape factor of at least 15. This platy clay can be blended with b-fraction clay component. In processing, the crude kaolin is ground to a shape factor greater than 50 to produce even greater &ldquo;platy&rdquo; clay. The pigment product has a particle size distribution such that at least 80% by weight of the particles have an esd less than 2 &mgr;m and greater than 12% and less than 35% by weight of the particles have an esd less than 0.25 &mgr;m and whose surface area is greater than 12 m /g when measured by the BET method.

Paper coating composition comprising an engineered kaolin pigment containing stacks and platelets of unground coarse particles where greater than 96% by weight is less than 5 microns, of which some kaolinite books or stacks are concentrated in the greater than 1 micron size fraction; 88% to 95% by weight is less than 2 microns; 65% to 85% by weight is less than 1 micron; and 15% to 25% by weight is less than 0.25 micron. A first embodiment comprises particles with a shape factor Ad between 7 and 9 which represents a significant number of stacks and some platelets. A second embodiment comprises particles with a shape factor of 11 or 12 which represents the presence of some stacks with a majority of platelets. The kaolin clay pigments form clay-water slurries of 69% solids or greater. As a coating, the composition gives a G. E. brightness between 88 and 94. The engineered pigment is processed so that the desired shape factor is met, which shape factor is equated to the aspect ratio or morphology of the pigment.

Engineered kaolin pigment composition for paper coating

Paper coating composition comprising an engineered kaolin pigment containing stacks and platelets of unground coarse particles where greater than 96% by weight is less than 5 microns, of which some kaolinite books or stacks are concentrated in the greater than 1 micron size fraction; 88% to 95% by weight is less than 2 microns; 65% to 85% by weight is less than 1 micron; and 15% to 25% by weight is less than 0.25 micron. A first embodiment comprises particles with a shape factor between 7 and 9 which represents a significant number of stacks and some platelets. A second embodiment comprises particles with a shape factor of 11 or 12 which represents the presence of some stacks with a majority of platelets. The kaolin clay pigments form clay-water slurries of 69% solids or greater. As a coating, the composition gives a G.E. brightness between 88 and 94. The engineered pigment is processed so that the desired shape factor is met, which shape factor is equated to the aspect ratio or morphology of the pigment.

Growing community of inventors

Milledgeville, GA, United States of America

Daniel John Panfil