Hyperplaty clays and their use in paper coating and filling, methods for making same, and paper products having improved brightness

1. A composition comprising kaolin having a shape factor of at least about 80:1.

2. The composition according to claim 1 , wherein the kaolin has a shape factor of at least about 90:1.

3. The composition according to claim 1 , wherein the kaolin has a shape factor of at least about 100:1.

4. The composition according to claim 1 , further comprising a binder.

5. The composition according to claim 4 , wherein the binder is a latex binder.

6. The composition according to claim 4 , further comprising a dispersant.

7. The composition according to claim 6 , further comprising an additional pigment.

8. The composition according to claim 7 , wherein the additional pigment is TiO 2 .

9. The composition according to claim 1 , wherein the kaolin has a d 50 ranging from about 0.1 μm to about 2.0 μm.

10. The composition according to claim 1 , wherein the kaolin has a d 50 ranging from about 0.25 μm to about 1 μm.

11. The composition according to claim 1 , wherein the kaolin has a d 50 ranging from about 0.5 μm to about 1.5 μm.

12. The composition according to claim 1 , further comprising a stabilizing agent.

13. A coating composition, comprising:

kaolin having a shape factor of at least about 70:1;

a binder; and

optionally a dispersant.

14. The composition according to claim 13 , further comprising an additional pigment.

15. The composition according to claim 14 , wherein the additional pigment is TiO 2 .

16. The composition according to claim 7 , wherein said composition has a ratio of kaolin to TiO 2 of less than about 85:15 parts by weight.

17. A filler comprising kaolin having a shape factor of at least about 80:1.

18. The filler according to claim 17 , wherein the kaolin has a shape factor of at least about 90:1.

19. The filler according to claim 17 , wherein the kaolin has a shape factor of at least about 100:1.

20. An extender for paint comprising kaolin, prepared by a method comprising:

providing a kaolin slurry comprising whole crude kaolin or a blend of whole crude and coarse-particle size fractions from a centrifuge;

attrition grinding the kaolin slurry;

removing a coarse particle size fraction from the slurry by centrifugation; and attrition grinding the coarse-particle size fraction to provide a kaolin product having a shape factor of at least about 70:1.

21. The extender according to claim 20 , wherein the kaolin product has a d 50 ranging from 0.1 μm to 2.0 μm.

22. The extender according to claim 20 , wherein the kaolin product has a d 50 ranging from 0.5 μm to 1.5 μm.

23. The extender according to claim 20 , wherein the kaolin product has a shape factor ranging from about 80:1 to about 100:1.

24. The extender according to claim 20 , wherein the kaolin product has a shape factor of at least about 80:1.

25. The extender according to claim 20 , wherein the kaolin product has a shape factor of at least about 90:1.

26. The extender according to claim 20 , wherein the kaolin product has a shape factor of at least about 100:1.

27. A slurry comprising kaolin having a shape factor of greater than 70:1 and a stabilizing agent.

28. The slurry according to claim 27 , wherein said stabilizing agent comprises carboxymethylcellulose.

29. The slurry according to claim 27 , wherein said stabilizing agent comprises a smectite clay.

30. The slurry according to claim 27 , wherein said stabilizing agent comprises bentonite.

31. The slurry according to claim 27 , wherein said stabilizing agent comprises hectorite.

32. The slurry according to claim 27 , wherein said stabilizing agent is present in the slurry in an amount ranging from about 4 pounds per dry tonne kaolin to about 10 lbs per dry tonne kaolin.

33. The slurry according to claim 27 , wherein said slurry has a solids content of greater than about 45%.

34. The slurry according to claim 27 , wherein said slurry has a solids content ranging from about 50% to about 60%.