Claims
- 1. A pigment product comprising a kaolin having a particle size distribution such that at least about 80% by weight of the particles have an equivalent spherical diameter less than about 2 μm and from about 15% to about 40% by weight of the particles have an equivalent spherical diameter less than about 0.25 μm and the particles have a shape factor in the range of from about 35 to about 60 and wherein the pigment product comprises a blend of
Component A: a particulate kaolin in which the particles have a shape factor of at least about 45, and Component B: a particulate kaolin in which the particles have a shape factor of less than about 20.
- 2. The pigment product according to claim 1, wherein from about 85% to about 95% by weight of the particles have an equivalent spherical diameter less than about 2 μm.
- 3. The pigment product according to claim 1, wherein from about 90% to about 93% by weight of the particles have an equivalent spherical diameter less than about 2 μm.
- 4. The pigment product according to claim 1, wherein from about 20% to about 30% by weight of the particles have an equivalent spherical diameter less than about 0.25 μm.
- 5. The pigment product according to claim 1, wherein from about 25% to about 30% by weight of the particles have an equivalent spherical diameter less than about 0.25 μm.
- 6. The pigment product according to claim 1, wherein the shape factor of the particles is in the range of from about 35 to about 50.
- 7. The pigment product according to claim 6, wherein the shape factor of the particles is in the range of from about 35 to about 45.
- 8. The pigment product according to claim 7, wherein the shape factor of the particles is in the range of from about 40 to about 45.
- 9. A method of making a pigment product a kaolin having a particle size distribution such that at least about 80% by weight of the particles have an equivalent spherical diameter less than about 2 μm and from about 15% to about 40% by weight of the particles have an equivalent spherical diameter less than about 0.25 μm and the particles have a shape factor in the range of from about 35 to about 60, the method comprising
blending Component A: a particulate kaolin in which the particles have a shape factor of at least about 45; with Component B: a particulate kaolin in which the particles have a shape factor of less than about 20.
- 10. A method according to claim 9, wherein the blend ratio of the Component A to the Component B is from about 1:1 to about 100:1, by weight.
- 11. A method according to claim 10, wherein the blend ratio of Component A to Component B is from about 2:1 to about 50:1, by weight.
- 12. A method according to claim 11, wherein the blend ratio of Component A to Component B is from about 2:1 to about 10:1, by weight.
- 13. A method according to claim 9, wherein Component A is prepared by treating a sedimentary kaolin.
- 14. A method according to claim 9, wherein Component A is prepared by
(a) mixing a raw or partially processed kaolin clay with water to form an aqueous suspension; (b) attrition grinding the suspension produced by step (a) such that the average shape factor of the kaolin clay is increased by at least about 10; (c) separating the suspension of ground kaolin clay from the particulate grinding medium, and (d) dewatering the suspension of ground kaolin clay separated in step (c).
- 15. A method according to claim 14, wherein in step (b), the average shape factor is increased by at least about 20.
- 16. A method according to claim 9, wherein Component B is prepared by the steps of
(a) dispersing a kaolin clay in an aqueous suspension of a water soluble dispersing agent to form an aqueous clay suspension; (b) delaminating the kaolin clay in the aqueous clay suspension; (c) separating the kaolin clay suspension into a coarse fraction and a fine fraction, admixing a portion of the fine fraction with the coarse fraction; (d) surface treating the kaolin clay particles by admixing into the aqueous clay suspension a member from the group consisting of a water soluble amine, aluminum sulfate, and mixtures thereof; and (e) obtaining the kaolin clay from the aqueous clay suspension.
- 17. The method according to claim 16, wherein the kaolin clay suspension is treated with a water soluble bleaching agent after surface treatment.
- 18. A coating composition for use in producing gloss coatings on paper and other substrates, which composition comprises an aqueous suspension of a particulate pigment and a hydrophilic adhesive, wherein the particulate pigment comprises the pigment product of claim 1.
- 19. A composition according to claim 18, wherein the adhesive forms from about 4% to about 30% of the solids of the composition on a dry weight basis.
- 20. A composition according to claim 18, wherein the solids content of the composition is from about 60% to about 90% by weight of the composition.
- 21. A composition according to claim 18, wherein at least about 80% by weight of the particulate pigment of the composition comprises the pigment product according to claim 1.
- 22. A composition according to claim 18, wherein the adhesive comprises a modified or unmodified starch.
- 23. A composition according to claim 18, wherein the adhesive comprises a binder other than starch.
- 24. A method of use of the coating composition according to claim 18 which comprises coating a sheet of paper with said composition and calendering the paper to form a gloss coating thereon.
PRIORITY CLAIM
[0001] This application claims the benefit of U.S. provisional application No. 60/272,253, filed Feb. 28, 2001, and U.S. provisional application No. 60/279,148, filed Mar. 27, 2001, both of which are incorporated herein by reference.
Provisional Applications (2)
|
Number |
Date |
Country |
|
60272253 |
Feb 2001 |
US |
|
60279148 |
Mar 2001 |
US |