Abstract: A novel clay pigment, the manufacture thereof and the use of the pigment in the coating of lightweight groundwood paper are disclosed. The kaolin clay particles initially have a shape factor between less than 10 and a particle size distribution where between 30 to 60% by weight is less than 2 microns and 20% by weight is less than 0.25 micron e.s.d. This clay is subjected to attrition grinding to produce clay particles having a shape factor between 13 and 18 and then classified to produce a particle size distribution where 80 to 90% by weight are less than 2 microns and 20% by weight are less than 0.25 micron. These pigments have a G.E. brightness ranging from 88 to 92; are deficient in ultra-fine particles; are fluid at a high solids concentration greater than 70%, and have a low shear Brookfield viscosity below 500 cps and a high shear Hercules viscosity of 18 dyne-cm above 200 rpm when using an “A” bob.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A method of enhancing the brightness and increasing the yield of a kaolin clay by optimizing the removal of the titania and mica impurities in the clay and the amount of clay remaining in the slurry is disclosed. The method is a selective flocculation process wherein the clay is blunged, dispersed, and conditioned before flocculation. In the flocculation step, a high molecular weight anionic polymer and a low molecular weight anionic polymer, such as sodium polyacrylate, are added to the slurry after the conditioning process, whereby the titania-mica enriched flocs are separated from the suspension which is enriched with kaolin. This final kaolin product has titania levels ranging from 0.1% to 0.5%, a reduced mica level, a high usable product yield, and a brightness greater than 89.5 and at least 91.5.