Pigment products
AssigneeImerys Pigments, Inc.
InventorsJohn Claude Husband, Desmond Charles Payton, Michele Susan Renals
Life of this patent
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Abstract
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 whose particles have a particle size distribution such that at least 80% by weight of the particles have an equivalent spherical diameter less than 2 μm and not less than 8%, preferably not less than 12%, by weight of the particles have an equivalent spherical diameter less than 0.25 μm and whose particles have a shape factor of at least 45, preferably at least 50.
Claims32
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 whose particles have a particle size distribution such that at least 80% by weight of the particles have an equivalent spherical diameter less than 2 μm and not less than 8% by weight of the particles have an equivalent spherical diameter less than 0.25 μm and whose particles have a shape factor of at least 45.
A method of treating a kaolin clay to increase the particle fineness and shape factor thereof which includes the steps of:
- (a) treating an aqueous suspension of the clay by a first comminution process to give delamination of the clay, in which an energy of not more than 75 kWh per tonne of clay on a dry weight basis is dissipated;
- (b) treating the clay after delamination in step (a) by a second comminution process to give particle comminution in which an energy of from 40 to 120 kWh per tonne of clay on a dry weight basis is dissipated.
Dependencies are inferred from the claim text.