Process for preparing self-binding pigment particles

Patent metadata

Field	Value
Publication number	US-9611587-B2
Application number	US-201314394632-A
Country	US
Kind code	B2
Filing date	Apr 29, 2013
Priority date	May 11, 2012
Publication date	Apr 4, 2017
Grant date	Apr 4, 2017

Abstract

The present invention concerns a process for preparing self-binding pigment particles from an aqueous suspension of a calcium carbonate containing material, wherein an anionic binder and at least one cationic polymer are mixed with the suspension.

First claim

The invention claimed is:

1. A process for preparing self-binding pigment particles comprising the following steps:
a) providing a suspension comprising at least one calcium carbonate containing material,
b) providing an anionic polymeric binder that comprises at least one modified polysaccharide,
c) providing at least one cationic polymer selected from the group consisting of one or more polyamines, polyethyleneimines, polyacrylamides, cationic epichlorohydrin resins, polydiallyldimethylammonium chlorides, cationic starches, cationic guars, and any mixture thereof,
d) mixing the suspension of step a) and the binder of step b), and
e) grinding the mixed suspension of step d) so that the particle size of the calcium carbonate material is reduced and self-binding pigment particles are obtained, wherein the at least one cationic polymer of step c):
i) is mixed in step d) with the suspension of step a) and the binder of step b), and/or
ii) is mixed with the suspension obtained after grinding step e), and the obtained mixture is deagglomerated,
wherein the binder of step b) is added in an amount from 0.001 to 20 wt.-% based on the total weight of the dry calcium carbonate containing material, and
wherein the at least one cationic polymer of step c) is added in an amount from 0.001 to 20 wt.-% based on the total weight of the dry calcium carbonate containing material, and
wherein the grinding step e) is carried out until the fraction of self-binding pigment particles having a particle size of less than 2 μm is greater than 20 wt.-% based on the total weight of the pigment particles, as measured with a Mastersizer 2000.

2. The process of claim 1 , wherein in step d) the suspension of step a) is, in a first step, mixed with the binder of step b), and then, in a second step, is mixed with the at least one cationic polymer of step c).

3. The process of claim 2 , wherein in the first step the suspension of step a) is mixed with a first part the binder of step b), the obtained mixture is ground and then mixed with the remaining part of the binder of step b).

4. The process of claim 1 , wherein in step d) the binder of step b) is, in a first step, mixed with the cationic polymer of step c), and then, in a second step, is mixed with the suspension of step a).

5. The process of claim 1 , wherein in step d) the suspension of step a) is mixed with the binder of step b) and the cationic polymer of step c) in one step.

6. The process of claim 1 , wherein the cationic polymer is added in an amount such that the charge density of the obtained self-binding pigment particles is lower compared to self-binding pigment particles not containing the cationic polymer.

7. The process of claim 1 , wherein the cationic polymer is added in an amount such that the charge density of the obtained self-binding pigment particle is between −100 and −5 μEq/g.

8. The process of claim 1 , wherein the cationic polymer is added in an amount such that the charge density of the obtained self-binding pigment particle is between −80 and −10 μEq/g.

9. The process of claim 1 , wherein the cationic polymer is added in an amount such that the charge density of the obtained self-binding pigment particle is between −70 and −15 μEq/g.

10. The process of claim 1 , wherein the at least one calcium carbonate containing material is selected from the group consisting of calcium carbonate, calcium carbonate containing minerals, mixed calcium carbonate based fillers, and any mixture thereof.

11. The process of claim 1 , wherein the at least one calcium carbonate containing material is ground calcium carbonate.

12. The process of claim 1 , wherein the at least one calcium carbonate containing material of step a) is provided in form of particles having a weight median particle diameter d 50 value from 0.1 to 100 μm.

13. The process of claim 1 , wherein the at least one calcium carbonate containing material of step a) is provided in form of particles having a weight median particle diameter d 50 value from 0.5 to 50 μm.

14. The process of claim 1 , wherein the at least one calcium carbonate containing material of step a) is provided in form of particles having a weight median particle diameter d 50 value from 5.0 to 25 μm.

15. The process of claim 1 , wherein the at least one calcium carbonate containing material is provided in form of particles have a specific surface area of from 0.1 to 200 m 2 /g.

16. The process of claim 1 , wherein the at least one calcium carbonate containing material is provided in form of particles have a specific surface area of from 1 to 25 m 2 /g.

17. The process of claim 1 , wherein the at least one calcium carbonate containing material is provided in form of particles have a specific surface area of from 2 to 15 m 2 /g.

18. The process of claim 1 , wherein the suspension of step a) has a solid content of at least 1 wt.-% based on the total weight of the suspension.

19. The process of claim 1 , wherein the suspension of step a) has a solid content of from 1 to 90 wt.-% based on the total weight of the suspension.

20. The process of claim 1 , wherein the suspension of step a) has a solid content of from 20 to 75 wt.-% based on the total weight of the suspension.

21. The process of claim 1 , wherein the suspension of step a) has a solid content of from 45 to 65 wt.-% based on the total weight of the suspension.

22. The process of claim 1 , wherein the at least one modified polysaccharide is a carboxymethyl derivate, a carboxymethyl hydroxypropyl derivate, and/or a carboxymethyl hydroxyethyl derivate of a polysaccharide.

23. The process of claim 1 , wherein the at least one modified polysaccharide is selected from the group consisting of one or more carboxymethylcelluloses, anionic starches, anionic guars, and any mixture thereof.

24. The process of claim 1 , wherein the at least one modified polysaccharide has a degree of substitution of hydroxyl groups from 0.4 to 2.0.

25. The process of claim 1 , wherein the at least one modified polysaccharide has a degree of substitution of hydroxyl groups from 0.5 to 1.8.

26. The process of claim 1 , wherein the at least one modified polysaccharide has a degree of substitution of hydroxyl groups from 0.6 to 1.6.

27. The process of claim 1 , wherein the at least one modified polysaccharide has a degree of substitution of hydroxyl groups from 0.7 to 1.5.

28. The process of claim 1 , wherein the binder of step b) is a carboxymethylcellulose having an intrinsic viscosity from 5 to 500 ml/g.

29. The process of claim 1 , wherein the binder of step b) is a carboxymethylcellulose having an intrinsic viscosity from 10 to 400 ml/g.

30. The process of claim 1 , wherein the binder of step b) is a carboxymethylcellulose having an intrinsic viscosity from 20 to 350 ml/g.

31. The process of claim 1 , wherein the binder of step b) is in form of a solution or dry material.

32. The process of claim 1 , wherein the binder of step b) is in form of a solution having a binder concentration from 1 to 70 wt.-% based on the total weight of the solution.

33. The process of claim 1 , wherein the binder of step b) is in form of a solution having a binder concentration from 2 to 30 wt.-% based on the total weight of the solution.

34. The process of claim 1 ,

Assignees

• Omya Int Ag

Inventors

• Gantenbein Daniel
• Gane Patrick A C
• Schoelkopf Joachim
• Laufmann Maximilian
• Andersson Lars

Classifications

• C09C3/041

  Grinding · CPC title

• D21H19/385

  Oxides, hydroxides or carbonates · CPC title

• D21H17/32

  Guar {or other polygalactomannan} gum · CPC title

• C01P2004/62

  Submicrometer sized, i.e. from 0.1-1 micrometer · CPC title

• A01N59/06

  Aluminium; Calcium; Magnesium; Compounds thereof · CPC title