Inorganic pigment containing calcium carbonate, aqueous suspension containing same, and uses thereof

Patent metadata

Field	Value
Publication number	US-9644101-B2
Application number	US-54764104-A
Country	US
Kind code	B2
Filing date	Mar 17, 2004
Priority date	Mar 18, 2003
Publication date	May 9, 2017
Grant date	May 9, 2017

Abstract

The present invention concerns the technical sector of mineral pigments containing a product formed in situ by the double and/or multiple reaction between a calcium carbonate and the reaction product or products of the said carbonate with one or more moderately strong to strong H 3 O + ion donors and the reaction product or products of the said carbonate with gaseous CO 2 formed in situ and/or coming from an external supply, and at least one aluminum silicate and/or at least one synthetic silica and/or at least one calcium silicate and/or at least one silicate of a monovalent salt such as sodium silicate and/or potassium silicate and/or lithium silicate, and/or at least one aluminum hydroxide and/or at least one sodium and/or potassium aluminate, containing less than 0.1% by weight silicate of a monovalent salt such as sodium, potassium or lithium silicate or mixtures thereof, relative to the dry weight of calcium carbonate, having a pH greater than 7.5 measured at 20° C., and their uses in papermaking applications such as mass filling and/or the coating of paper and more particularly of printing paper, in particular for offset printing, or digital printing such as inkjet and/or laser printing.

First claim

The invention claimed is:

1. A product obtained by a process consisting of the steps of:
(a) treating a natural ground calcium carbonate-containing mineral pigment, that is dispersed with a dispersing agent, in an aqueous suspension for 0.2 to 24 hours with:
(i) phosphoric acid at a molar quantity, relative to the number of moles of calcium carbonate, of 0.05 to 1,
(ii) gaseous CO 2 formed in situ and/or coming from an external supply, and
(iii) 0.1 to 25% by dry weight, relative to the dry weight of calcium carbonate, of one or more of aluminium silicate, synthetic silica, calcium silicate, silicate of a monovalent salt, sodium aluminate and potassium aluminate,

to obtain an aqueous suspension of mineral pigment having a pH of greater than 7.5 measured at 20° C. between one hour and twenty-four hours after treatment,
wherein addition of the one or more of aluminium silicate, synthetic silica, calcium silicate, silicate of a monovalent salt, sodium aluminate and potassium aluminate to the aqueous suspension occurs before, during or after reaction of the surface of the natural ground calcium carbonate with the phosphoric acid; and
(b) optionally adjusting the pH of the aqueous suspension of mineral pigment obtained in step (a) by the addition of a base.

2. The product according to claim 1 , wherein in step (a) the mineral pigment is treated for 0.2 to 6 hours.

3. The product according to claim 1 , wherein the mineral pigment is treated in part (i) with phosphoric acid at a molar quantity, relative to the number of moles of calcium carbonate, of 0.1 to 0.5.

4. The product according to claim 1 , wherein the mineral pigment is treated in part (iii) with 5 to 10% by dry weight, relative to the dry weight of calcium carbonate, of one or more of aluminium silicate, synthetic silica, calcium silicate, silicate of a monovalent salt, sodium aluminate and potassium aluminate.

5. The product according to claim 1 , wherein in step (a) the mineral pigment is treated at temperature of between 5° C. and 100° C.

6. The product according to claim 1 , wherein in step (a) the mineral pigment is treated at temperature of between 65° C. and 90° C.

7. The product according to claim 1 , wherein the mineral pigment is treated in part (iii) with a silicate of monovalent salt.

8. The product according to claim 7 , wherein the silicate of monovalent salt is sodium silicate, potassium silicate, lithium silicate, and any mixture thereof.

9. The product according to claim 7 , wherein the silicate of monovalent salt is sodium silicate.

10. The product according to claim 1 , wherein the natural ground calcium carbonate-containing mineral pigment is treated with 0.1 to 25% by dry weight, relative to the dry weight of calcium carbonate, of aluminum silicate.

11. The product according to claim 1 , wherein the mineral pigment is a mixture of natural ground calcium carbonate with one or more of talc, kaolin, titanium dioxide, or magnesium oxide.

12. The product according to claim 1 , wherein the natural ground calcium carbonate-containing mineral pigment is obtained from ground marble, calcite, chalk, dolomite or any mixture thereof.

13. The product according to claim 1 , wherein the mineral pigment has a BET specific surface area of 25 m 2 /g to 200 m 2 /g.

14. The product according to claim 1 , wherein the mineral pigment has a BET specific surface area of 30 m 2 /g to 80 m 2 /g.

15. The product according to claim 1 , wherein the mineral pigment has a BET specific surface area of 35 m 2 /g to 60 m 2 /g.

16. The product according to claim 1 , wherein the mineral pigment has a median diameter of 0.1 to 50 micrometers.

17. The product according to claim 1 , wherein the mineral pigment has a median diameter of 0.5 to 40 micrometers.

18. The product according to claim 1 , wherein the mineral pigment has a median diameter of 1 to 10 micrometers.

19. The product according to claim 1 , wherein step (b) is performed.

20. The product according to claim 1 , wherein the dispersing agent in step (a) is sodium polyacrylate.

Assignees

• Gane Patrick
• Buri Matthias
• Blum Rene Vinzenz
• Omya Int Ag

Inventors

• Gane Patrick
• Buri Matthias
• Blum Rene Vinzenz

Classifications

• C01P2006/12

  Surface area · CPC title

• C01P2004/62

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

• C01P2006/60

  Optical properties, e.g. expressed in CIELAB-values · CPC title

• D21H19/385

  Oxides, hydroxides or carbonates · CPC title

• C01P2004/61

  Micrometer sized, i.e. from 1-100 micrometer · CPC title