Mineral pigment containing calcium carbonate, an aqueous suspension containing it and uses thereof

Patent metadata

Field	Value
Publication number	US-2017190915-A1
Application number	US-201715464933-A
Country	US
Kind code	A1
Filing date	Mar 21, 2017
Priority date	Mar 18, 2003
Publication date	Jul 6, 2017
Grant date	—

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 aluminium 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 aluminium 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

1 . A process comprising 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; (b) optionally adjusting the pH of the aqueous suspension of mineral pigment obtained in step (a) by the addition of a base; (c) optionally introducing at least one anionic or cationic electrolyte to the aqueous suspension of mineral pigment; and (d) optionally drying the aqueous suspension of mineral pigment obtained from step (a), step (b) and/or step (c).

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

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

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

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

8 . The process according to claim 1 , wherein the silicate of monovalent salt is sodium silicate, potassium silicate, lithium silicate, and any mixture thereof.

9 . The process according to claim 1 , wherein the silicate of monovalent salt is sodium silicate.

10 . The process 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 process 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 process according to claim 1 , wherein the natural ground calcium carbonate is obtained from ground marble, calcite, chalk, dolomite or any mixture thereof.

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

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

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

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

20 . The process according to claim 1 , wherein step (c) is performed.

21 . The process according to claim 1 , wherein step (d) is performed.

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

Assignees

• Omya Int Ag

Inventors

• Gane Patrick
• Buri Matthias
• Blum René Vinzenz

Classifications

• C01P2004/62

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

• C09C1/021 Primary

  Calcium carbonates · CPC title

• D21H19/385

  Oxides, hydroxides or carbonates · CPC title

• C01P2006/60

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

• D21H17/675

  Oxides, hydroxides or carbonates · CPC title