Process for manufacturing aqueous suspensions of mineral materials or dried mineral materials, the obtained products, as well as uses thereof
The invention relates to a process for manufacturing aqueous mineral material suspensions or dried mineral materials using at least one lithium ion neutralized water-soluble organic polymer, the ground mineral materials obtained by this process, the use of the mineral materials in paper, paints and plastics, as well as the use of the lithium ion neutralized water-soluble organic polymer in the manufacturing process as a dispersing and/or grinding enhancer.
1. A process for manufacturing an aqueous mineral material comprising the steps of:
(a) providing at least one mineral material comprising calcium carbonate in the form of an aqueous suspension or in dry form,
(b) providing at least one partially or totally lithium-neutralized water-soluble polyacrylic acid, wherein the molar rate of lithium neutralized acid groups is 50% to 100% and the molar rate of non-lithium neutralized acid groups is 50% to 0%, so that 100% of the acid groups of the water-soluble polyacrylic acid are neutralized; and
(c) grinding the at least one mineral matter of step (a) at a temperature of from 80 to 105° C. in the presence of from 0.05 wt % to 1 wt %, relative to the total dry mineral material, of the at least one partially or totally lithium-neutralized water-soluble organic polyacrylic acid of step (b) in water to obtain an aqueous mineral material comprising calcium carbonate and the at least one partially or totally lithium-neutralized water-soluble polyacrylic acid.
2. The process according to claim 1 , wherein the at least one mineral material comprises calcium carbonate and one or more of magnesium, talc, clay, kaolin, aluminium hydroxide, mica, synthetic fibres, natural fibres, and titanium dioxide.
3. The process according to claim 1 , wherein the at least one mineral material is a natural calcium carbonate (GCC), a precipitated calcium carbonate (PCC), a mixture of GCC and PCC, a mixture of GCC and PCC and clay, or a mixture of GCC and PCC and talc.
4. The process according to claim 1 , wherein the at least one mineral material is a natural calcium carbonate (GCC), marble, chalk, calcite or limestone, or precipitated calcium carbonate (PCC), aragonitic PCC, calcitic PCC, rhombohedral PCC or scalenohedral PCC.
5. The process according to claim 1 , wherein the at least one mineral matter is natural calcium carbonate (GCC).
6. The process according to claim 1 , wherein in step (c) the at least one mineral material and the at least one partially or totally lithium-neutralized water-soluble polyacrylic acid are subjected to grinding at a pH of above 7.
7. The process according to claim 1 , wherein in step (c) the at least one mineral material and the at least one partially or totally lithium-neutralized water-soluble polyacrylic acid are subjected to grinding at a pH of between 8.5 and 10.5.
8. The process according to claim 1 , wherein in step (c) the at least one mineral material and the at least one partially or totally lithium-neutralized water-soluble polyacrylic acid are subjected to grinding at a pH of between 9 and 10.
9. The process according to claim 1 , wherein the at least one partially or totally lithium neutralized water-soluble polyacrylic acid is totally or partially neutralized by a lithium ion containing base or by a combination of a lithium ion containing base with one or more neutralization agents having a monovalent neutralizing function or a polyvalent neutralizing function, or any mixture thereof.
10. The process according to claim 9 , wherein the monovalent function is selected from the group consisting of an alkaline cation, sodium, potassium, ammonium, a primary, secondary or tertiary aliphatic and/or cyclic amine, stearylamine, monoethanolamine, diethanolamine, triethanolamine, cyclohexylamine, methylcyclohexylamine, aminomethylpropanol, morpholine, an alkaline earth divalent cation, magnesium, calcium, zinc, strontium, a trivalent cation, aluminium, or a cation of higher valency.
11. The process according to claim 9 , wherein the lithium ion-containing base is lithium hydroxide, or an oxide thereof, in dry form or in solution, and is contacted with the monomer before polymerization and/or with the polymer after polymerization of the monomer.
12. The process according to claim 1 , wherein the at least one partially or totally lithium-neutralized water-soluble polyacrylic acid is a lithium neutralized polyacrylic acid.
13. The process according to claim 1 , wherein the at least one partially or totally lithium-neutralized water-soluble polyacrylic acid is a lithium/sodium neutralized polyacrylic acid.
14. The process according to claim 1 , wherein the at least one mineral material comprises GCC and PCC, wherein the PCC is present in amount of from 10 to 90 wt %, based on the total weight of PCC and GCC.
15. The process according to claim 1 , wherein the at least one mineral material comprises GCC and PCC, wherein the PCC is present in amount of from 20 to 80 wt %, based on the total weight of PCC and GCC.
16. The process according to claim 1 , wherein the at least one mineral material comprises GCC and PCC, wherein the PCC is present in amount of from 30 to 70 wt %, based on the total weight of PCC and GCC.
17. The process according to claim 1 , wherein the grinding in step (c) is performed in an aqueous suspension at a solids concentration of mineral material of from 10 to 82% by dry weight of mineral material.
18. The process according to claim 1 , wherein the grinding in step (c) is performed in an aqueous suspension at a solids concentration of mineral material of from 40 to 81% by dry weight of mineral material.
19. The process according to claim 1 , wherein the grinding in step (c) is performed in an aqueous suspension at a solids concentration of mineral material of from 60 to 80% by dry weight of mineral material.
20. The process according to claim 1 , wherein the grinding in step (c) is performed in an aqueous suspension at a solids concentration of mineral material of from 65 to 72% by dry weight of mineral material.
21. The process according to claim 1 , wherein the water-soluble polyacrylic acid has a weight average molecular weight of 3000 to 12,000 g/mol.
22. The process according to claim 1 , wherein aqueous mineral material obtained in step (c) has a solids content of 65 to 80 wt. %, or is adjusted to have a solids content of 65 to 80 wt. %.
23. The process according to claim 1 , wherein aqueous mineral material obtained in step (c) has a solids content of 70 to 78 wt. %, or is adjusted to have a solids content of 70 to 78 wt. %.
24. The process according to claim 1 , wherein the aqueous mineral material obtained after grinding or solids content adjustment has a final solids content of 60 to 81 wt. % and a Brookfield viscosity of less than 1000 mPa·S after 1 minute of stirring at a rotation speed of 100 rpm at room temperature, when measured one hour after production of the aqueous mineral material and after eight days of unstirred storage of the aqueous mineral material.
25. The process according to claim 1 , wherein the aqueous mineral material obtained after grinding or solids content adjustment has a final solids content of 60 to 81 wt. % and a Brookfield viscosity of less than 500 mPa·S after 1 minute of stirring at a rotation speed of 100 rpm at room temperature, when measured one hour after production of the aqueous mineral material and after eight days of unstirred storage of the aqueous mineral material.
26. The process according to claim 1 , wherein the aqueous mineral material obtained after grinding or solids content adjustment has a final solids content of 60 to 81 wt. % and a Brookfield viscosity of less than 200 mPa·S after 1 minute of stirring at a rotation speed of 100 rpm at room temperature, when measured one hour after production of the aqueous mineral material and after eight days of unstirred storage of the aqueous mineral material.