Composite pigments
AssigneeThiele Kaolin Company
InventorsZhenzhong Zhang, Yaping Li
Life of this patent
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Abstract
Composite pigments are provided which comprise a mineral pigment (such as kaolin clay, titanium dioxide, talc, mica or a mixture of two or more of these mineral pigments) and calcium carbonate precipitated in-situ on the surfaces of the particles of the mineral pigment.
Claims26
A high brightness composite pigment which comprises a mineral pigment and in-situ precipitated calcium carbonate and which is produced by a plurality of carbonation cycles precipitating a calcium carbonate coating on surfaces of particles of the mineral pigment,
- wherein the composite pigment has a reduced amount of particles of less than 0.2 micron compared to the starting mineral pigment and an equivalent amount of particles of less than 2 microns compared to the starting mineral pigment,
- wherein the composite pigment comprises a uniform coating of precipitated calcium carbonate on the surfaces of the mineral pigment particles, in contrast to non-uniform unevenly distributed discrete calcium carbonate particles or aggregates of calcium carbonate particles on the surfaces of the mineral pigment particles;
- and
- wherein the content of particles less than 2 microns is at least 84.1% and not more than 93.7%.
A high brightness composite pigment which comprises a mineral pigment and precipitated calcium carbonate particles deposited as a coating on surfaces of particles of the mineral pigment,
- (a) wherein the composite pigment comprises a uniform coating of precipitated calcium carbonate on the surfaces of the mineral pigment particles, in contrast to non-uniform unevenly distributed discrete calcium carbonate particles or aggregates of calcium carbonate particles on the surfaces of the mineral pigment particles;
- and
- (b) wherein the difference between the percentage of particles less than 2 microns and the percentage of particles less than 0.2 microns is at least 67.2 and not more than 83.2.
A high brightness composite pigment which comprises a mineral pigment and in-situ precipitated calcium carbonate and which is produced by a plurality of carbonation cycles precipitating a calcium carbonate coating on surfaces of particles of the mineral pigment,
- wherein the composite pigment has a reduced amount of particles of less than 0.2 micron compared to the starting mineral pigment and an equivalent amount of particles of 1-2 microns compared to the starting mineral pigment,
- wherein the composite pigment comprises a uniform coating of precipitated calcium carbonate on the surfaces of the mineral pigment particles, in contrast to non-uniform unevenly distributed discrete calcium carbonate particles or aggregates of calcium carbonate particles on the surfaces of the mineral pigment particles;
- and
- wherein the content of particles less than 2 microns is at least 84.1% and not more than 93.7%.
Dependencies are inferred from the claim text.