Pigment for paper and coatings

Patent metadata

Field	Value
Publication number	US-10253186-B2
Application number	US-201715453192-A
Country	US
Kind code	B2
Filing date	Mar 8, 2017
Priority date	Mar 8, 2016
Publication date	Apr 9, 2019
Grant date	Apr 9, 2019

Abstract

Provided is a kaolin having a finer particle size and a narrower particle size distribution, in combination with suitable morphology. Also provided are a method of preparing the kaolin product and methods of use.

First claim

What is claimed is:

1. A fully or partially calcined kaolin having a GE brightness of at least about 92 and a particle size distribution of:
equal to or greater than 99% by weight of particles with an equivalent spherical diameter (e.s.d.) of less than 10 microns;
equal to or greater than 93% by weight of particles with an e.s.d. of less than 5 microns;
equal to or greater than 85% by weight of particles with an e.s.d. of less than 2 microns;
equal to or greater than 77% by weight of particles with an e.s.d. of less than 1 micron; and
equal to or greater than 25% by weight of particles with an e.s.d. of less than 0.5 microns,
wherein the fully or partially calcined kaolin has a +325 mesh residue content of 300 ppm or less and a median particle size of from 0.50 to 0.59 microns.

2. The fully or partially calcined kaolin according to claim 1 having a particle size distribution of:
99% to 100% by weight of particles with an e.s.d. of less than 10 microns;
93% to 100% by weight of particles with an e.s.d. of less than 5 microns;
85% to 98% by weight of particles with an e.s.d. of less than 2 microns;
77% to 92% by weight of particles with an e.s.d. of less than 1 micron; and
25% to 46% by weight of particles with an e.s.d. of less than 0.5 microns.

3. The fully or partially calcined kaolin according to claim 1 , having a +325 mesh residue content of 90 ppm or less.

4. The fully or partially calcined kaolin according to claim 1 , having a sodium oxide content less than or equal to 0.1% by weight of the fully or partially calcined kaolin.

5. The fully or partially calcined kaolin according to claim 1 , having a GE brightness of at least about 92 to about 96.

6. The fully or partially calcined kaolin according to claim 1 , having an oil absorption of greater than 100 to 140 lbs oil/100 lbs fully or partially calcined kaolin.

7. The fully or partially calcined kaolin according to claim 1 , having a scattering coefficient at 457 nanometers of about 0.305 to about 0.335 m 2 /g.

8. The fully or partially calcined kaolin according to claim 1 , having a scattering coefficient at 577 nanometers of about 0.223 to about 0.230 m 2 /g.

9. The fully or partially calcined kaolin according to claim 1 , having a surface area of about 17.0 to about 25.0 m 2 /g.

10. The fully or partially calcined kaolin according to claim 1 having an Einlehner abrasion loss of 9 to 18 mg/10 5 rev.

11. The fully or partially calcined kaolin according to claim 1 having a gloss of about 30% to about 45%.

12. A paper coating formulation or paper binding formulation comprising a fully or partially calcined kaolin according to claim 1 .

13. A paint comprising a fully or partially calcined kaolin according to claim 1 .

14. A fully or partially calcined kaolin having a GE brightness of at least about 92 and a particle size distribution of:
equal to or greater than 99% by weight of particles with an equivalent spherical diameter (e.s.d.) of less than 10 microns;
equal to or greater than 93% by weight of particles with an e.s.d. of less than 5 microns;
equal to or greater than 85% by weight of particles with an e.s.d. of less than 2 microns;
equal to or greater than 77% by weight of particles with an e.s.d. of less than 1 micron; and
equal to or greater than 25% by weight of particles with an e.s.d. of less than 0.5 microns,
wherein the fully or partially calcined kaolin has a sodium oxide content of less than or equal to 0.25% by weight of the fully or partially calcined kaolin.

15. The fully or partially calcined kaolin according to claim 14 , having a +325 mesh residue content of 300 ppm or less.

16. The fully or partially calcined kaolin according to claim 14 , having a GE brightness of at least about 92 to about 96.

17. The fully or partially calcined kaolin according to claim 14 , having a median particle size (d50) of 0.50 to 0.59 microns.

18. The fully or partially calcined kaolin according to claim 14 , having a surface area of about 17.0 to about 25.0 m 2 /g.

19. The fully or partially calcined kaolin according to claim 14 having an Einlehner abrasion loss of 9 to 18 mg/10 5 rev.

20. The fully or partially calcined kaolin according to claim 14 having a gloss of about 30% to about 45%.

21. A fully or partially calcined kaolin having a GE brightness of at least about 92 and a particle size distribution of:
equal to or greater than 99% by weight of particles with an equivalent spherical diameter (e.s.d.) of less than 10 microns;
equal to or greater than 93% by weight of particles with an e.s.d. of less than 5 microns;
equal to or greater than 85% by weight of particles with an e.s.d. of less than 2 microns;
equal to or greater than 77% by weight of particles with an e.s.d. of less than 1 micron; and
equal to or greater than 25% by weight of particles with an e.s.d. of less than 0.5 microns,
wherein the fully or partially calcined kaolin has a +325 mesh residue content of 300 ppm or less and an oil absorption of from 120 to 140 lbs oil/100 lbs fully or partially calcined kaolin.

22. A method for preparing the fully or partially calcined kaolin of claim 1 , comprising the steps of:
providing a first kaolin feedstream having at least about 88-89% by weight of the particles having size of 1 μm or less;
classifying the first kaolin feedstream by centrifugation to provide a fine particle size distribution of at least about 97-98% by weight of the particles having size of 1 μm or less;
filtering the first kaolin feedstream to produce a filter cake;
dispersing the filtrate in a sodium-free dispersion agent to provide a second kaolin feedstream; and
drying and heat treating the second kaolin feedstream,
wherein the method for preparing the fully or partially calcined kaolin does not include a reductive bleaching step.

23. The method according to claim 22 , further comprising flocculating the first feedstream prior to the filtering step.

24. The method according to claim 22 , wherein the sodium-free dispersion agent is an ammonia-based dispersion agent.

25. The method according to claim 22 , wherein the second kaolin feedstream has a pH of about 10.

26. The method according to claim 22 , wherein heat treating comprises calcining at a temperature of from about 900° C. to about 1200° C. to produce a fully calcined kaolin.

27. The method according to claim 22 , wherein the providing step comprises processing a blunged/degritted hydrous kaolin crude feedstock by one or more of magnetic separation, flotation, ozonation, or selective flocculation to produce the first kaolin feedstream having at least about 88-89% by weight of the particles having size of 1 μm or less.

28. The method according to claim 22 , wherein the method excludes delamination processes.

29. The method according to claim 22 , wherein the classifying step, filtering step, dispersing step, and drying and calcining step exclude a sodium-based dispersion agent.

Assignees

• Basf Corp

Inventors

• Khokhani Ashok
• Yildirim Ismail
• Berube Richard
• Mathur Sharad
• Lake Anthony N

Classifications

• D21H19/40

  siliceous, e.g. clays · CPC title

• D21H17/68

  siliceous, e.g. clays · CPC title

• C09C1/42 Primary

  Clays · CPC title

• C08K2201/003

  Additives being defined by their diameter · CPC title

• C08K3/34

  Silicon-containing compounds · CPC title