Dry mineral pigment containing calcium carbonate, aqueous suspension containing said pigment, and the uses thereof

Abstract

The invention concerns a process for manufacturing a dry mineral pigment containing a product formed in situ by the multiple reaction between a calcium carbonate and the product or products of reaction of the said carbonate with one or more moderately strong to strong H3O+ ion donators and the product or products of reaction of the said carbonate with gaseous CO.sub.2 formed in situ and/or originating from an external supply and one or more compounds of formula RX together with the mineral pigment obtained by the process, and its applications in the field of paint and/or plastics.

Claims

1. A process for preparing a treated mineral pigment comprising the steps of: (a) treating calcium carbonate, that is dispersed with a dispersing agent, in an aqueous suspension for 0.2 to 10 hours with a treatment agent comprising: (i) phosphoric acid at a molar quantity, relative to the number of moles of calcium carbonate, of 0.001 to 1, (ii) gaseous CO.sub.2 formed in situ and/or coming from an external supply, and (iii) one or more compounds of formula RX at a molar quantity, relative to the number of moles of calcium carbonate, of 0.001 to 1, wherein the one or more compounds of formula RX have 8 to 24 carbon atoms and is a fatty amine, a fatty alcohol, a tallow oil, a mixture of a vegetal oil-based fatty acid and dodecylic alcohol, a stearilic alcohol, sunflower oil, a linseed oil, a coco oil, or a mixture thereof, to obtain an aqueous suspension of mineral pigment; (b) optionally adjusting the pH of the aqueous suspension of mineral pigment 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), wherein the calcium carbonate in step (a) is selected from the group consisting of ground marble, calcite, chalk, dolomite and any mixture thereof.

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

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

5. The process according to claim 1, wherein the calcium carbonate is treated in part (iii) with one or more compounds of formula RX at a molar quantity, relative to the number of moles of calcium carbonate, of 0.002 to 0.01.

6. The process according to claim 1, wherein the one or more compounds of formula RX is a fatty amine.

7. The process according to claim 1, wherein the one or more compounds of formula RX is a fatty alcohol.

8. The process according to claim 1, wherein the one or more compounds of formula. RX are selected from the group consisting of fatty amines, fatty alcohols and mixtures thereof of stearic, oleic, linoleic, myristic, or octylic type, and their mixtures.

9. The process according to claim 1, wherein the one or more compounds of formula RX are selected from the group consisting of fatty amines, fatty alcohols, and mixtures thereof having 16 to 18 carbon atoms.

10. The process according to claim 1, wherein the one or more compounds of formula RX is a natural fatty compound of animal origin.

11. The process according to claim 1, wherein the one or more compounds of formula RX is a natural fatty compound of vegetal origin.

12. The process according to claim 1, wherein the one or more compounds of formula RX is tallow oil.

13. The process according to claim 1, wherein the one or more compounds of formula RX is a mixture of a vegetal oil-based fatty acid and dodecylic alcohol.

14. The process according to claim 1, herein the one or more compounds of formula RX is stearilic alcohol.

15. The process according to claim 1, wherein the one or more compounds of formula RX is sunflower oil.

16. The process according to claim 1, wherein the one or more compounds of formula RX is linseed oil.

17. The process according to claim 1, wherein the one or more compounds of formula RX is coco oil.

18. The process according to claim 1, wherein the mineral pigment has a BET specific surface area of 1 m.sup.2/g to 200m.sup.2/g.

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

20. The process according to claim 1, wherein the mineral pigment has a moisture content of less than 1.50% after drying for 2 hours at 120 C. in an oven at atmospheric pressure.

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

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

23. The process according to claim 1, wherein steps (b) and (c) are performed.

24. The process according to claim 1, wherein steps (c) and (d) are performed.

25. process according to claim 1, wherein steps (b) and performed.

26. The process according to claim 1, wherein steps (b), (c) and (d) are performed.

Description

EXAMPLE 1

(1) This example illustrates the prior art and concerns the various processes for preparing pigment according to the prior art.

(2) Test n 1

(3) This test illustrates a process for preparing a pigment according to the prior art for which 0.5 kg, calculated as dry pigment, of natural calcium carbonate of the Norwegian marble type, of granulometry such that 65% by weight of the particles have a diameter of less than 1 m, measured using the Sedigraph 5100 of the company Micromeritics, in the form of an aqueous suspension of 75% of dry content, dispersed with 0.6% of a soda polyacrylate, is diluted until an aqueous suspension with a 15% by weight dry matter concentration is obtained, using distilled water, in the 10-litre container. The suspension thus formed is then treated with 10% of phosphoric acid in a 10% by weight solution, at 65 C. whilst stirring, for 20 minutes, at 500 rpm. The pH was then adjusted, to between 8 and 8.5, with a suspension of lime at a concentration equal to 10% by dry weight, before drying the suspension obtained using a Nara MSD 100 drying machine.

(4) The suspension of mineral pigment obtained before drying has a dry pigment concentration equal to 18.8% by mass, and a pH equal to 8.4.

(5) The granulometry measured using a Sedigraph 5100 is such that 90% by weight of the particles have a diameter of less than 2 m and 57% by weight of the particles have a diameter of less than 1 m.

(6) After drying, the product has a BET specific surface area, measured using the BET method of norm ISO 9277 equal to 30.7 m.sup.2/g.

(7) Test n 2

(8) This test illustrates a process for preparing a pigment according to the prior art for which 0.758 kg, calculated as dry pigment, of natural calcium carbonate of the French chalk type, of granulometry such that 65% by weight of the particles have a diameter of less than 1 m, measured using the Sedigraph 5100 of the company Micromeritics, in the form of an aqueous suspension of 75% of dry content, dispersed with 0.6% of a soda polyacrylate, is diluted until an aqueous suspension with a 10% by weight dry matter concentration is obtained, using distilled water, in the 10-litre ESCO reactor. The suspension thus formed is then treated with 20% of phosphoric acid in a 20% by weight solution, at 65 C. whilst stirring, for 60 minutes. The pH was then adjusted, to between 8 and 8.5, with a suspension of lime at a concentration equal to 10% by dry weight, before drying the suspension obtained using a Nara MSD 100 drying machine.

(9) The suspension of mineral pigment obtained before drying has a dry pigment concentration equal to 18.8% by mass, and a pH equal to 8.4.

(10) The granulometry measured using a Sedigraph 5100 is such that 94.4% by weight of the particles have a diameter of less than 2 m and 68.2% by weight of the particles have a diameter of less than 1 m.

(11) After drying, the product has a BET specific surface area, measured using the BET method of norm ISO 9277 equal to 31.1 m.sup.2/g.

(12) Test n 3

(13) This test illustrates a process for preparing a pigment according to the prior art for which 0.5 kg, calculated as dry pigment, of natural calcium carbonate of the Norwegian marble type, of granulometry such that 65% by weight of the particles have a diameter of less than 1 m, measured using the Sedigraph 5100 of the company Micromeritics, in the form of an aqueous suspension of 75% of dry content, dispersed with 0.6% of a soda polyacrylate, is diluted until an aqueous suspension with a 15% by weight dry matter concentration is obtained, using distilled water, in the 10-litre container. The suspension thus formed is then treated with 10% of phosphoric acid in a 10% by weight solution, at 65 C. whilst stirring, for 20 minutes, at 500 rpm. The pH was then adjusted, to between 8 and 8.5, with a suspension of lime at a concentration equal to 10% by dry weight, before drying the suspension obtained using a Nara MSD 100 drying machine.

(14) The suspension of mineral pigment obtained before drying has a dry pigment concentration equal to 18.8% by mass, and a pH equal to 8.4.

(15) The granulometry measured using a Sedigraph 5100 is such that 90% by weight of the particles have a diameter of less than 2 m and 57% by weight of the particles have a diameter of less than 1 m.

(16) After drying, the product has a BET specific surface area, measured using the BET method of norm ISO 9277 equal to 30.7 m.sup.2/g.

(17) The product is then treated with 3% of stearic acid. The treatment was undertaken at 120 C. for ten minutes in a laboratory mixer from MTI; the rotational speed was 1500 rpm.

EXAMPLE 2

(18) This example illustrates the invention and concerns the process for manufacturing a dry mineral pigment containing a product formed in situ by the multiple reaction between a natural calcium carbonate and the product or products of reaction of the said carbonate with one or more moderately strong to strong H3O+ ion donators and the product or products of reaction of the said carbonate with gaseous CO.sub.2 formed in situ and/or originating from an external supply and one or more compounds of formula RX together with the mineral pigment obtained by the process.

(19) Test n 4

(20) This test illustrates the invention and concerns a process to obtain the pigment according to the invention in which the treatment with 2% of a mixture of palmitic acid and stearic acid (in a ratio of approximately 1/1 by weight) takes place during the reaction of the calcium carbonate with phosphoric acid.

(21) To accomplish this, 0.746 kg, calculated as dry pigment, of natural calcium carbonate of the French chalk type, of granulometry such that 65% by weight of the particles have a diameter of less than 1 m, measured using the Sedigraph 5100 of the company Micromeritics, in the form of an aqueous suspension of 78% of dry content, dispersed with 0.5% of a soda polyacrylate, is diluted until an aqueous suspension with a 10% by weight dry matter concentration is obtained, using distilled water, in a 10-litre ESCO reactor. The suspension thus formed is then treated with 25% of phosphoric acid in a solution 20% by weight, at 60 C. whilst stirring, for 60 minutes, at 500 rpm. 2% of fatty acid of the Palmitic Acid/Stearic Acid mixture type, in a ratio of 1/1 by weight, is then added as powder and mixed for 30 minutes before drying the suspension obtained using a Nara MSD-100 drying machine.

(22) The suspension of mineral pigment obtained before drying has a dry pigment concentration equal to 9.5% by mass, and a pH equal to 6.4.

(23) The granulometry measured using a Sedigraph 5100 is such that 90.9% of the particles have a diameter of less than 2 m and 66.8% of the particles have a diameter of less than 1 m.

(24) After drying the product has a BET specific surface area, measured using the BET method of norm ISO 9277, equal to 33.4 m.sup.2/g and a median diameter, determined by a measurement using the Sedigraph 5100, equal to 0.72 micrometer, and a moisture content equal to 1.32% determined using the method described above.

(25) Test n 5

(26) This test illustrates the invention and concerns a process to obtain pigment according to the invention in which the treatment with 2% of stearic acid takes place before the reaction of the calcium carbonate with the phosphoric acid.

(27) To accomplish this, 0.750 kg, calculated as dry pigment, of natural calcium carbonate of the French chalk type, of granulometry such that 65% by weight of the particles have a diameter of less than 1 m, measured using the Sedigraph 5100 of the company Micromeritics, in the form of an aqueous suspension of 78% of dry content, dispersed with 0.5% of a soda polyacrylate, is diluted until an aqueous suspension with a 10% by weight dry matter concentration is obtained, using distilled water, in the 10-litre container. 2% of pure stearic acid from Fluka is then added, heated to 70 C. and mixed for 15 minutes, before treating the suspension thus formed by 25% of phosphoric acid in a 20% by weight solution, at 60 C., whilst stirring for 60 minutes at 500 rpm. It is left to react for 30 minutes before drying the suspension thus obtained using a Nara MSD-100 drying machine.

(28) The suspension of mineral pigment obtained before drying has a dry pigment concentration equal to 9.4% by mass, and a pH equal to 6.4.

(29) The granulometry measured using a Sedigraph 5100 is such that 91.7% of the particles have a diameter of less than 2 m and 66.9% of the particles have a diameter of less than 1 m.

(30) After drying, the product has a BET specific surface area, measured using the BET method of norm ISO 9277, equal to 34.5 m.sup.2/g and a median diameter, determined by measurement using the Sedigraph 5100, equal to 0.73 micrometer.

(31) Test n 6

(32) This test illustrates the invention and concerns a process to obtain pigment according to the invention in which the treatment with 3% of stearic acid takes place before the reaction of the calcium carbonate with the phosphoric acid.

(33) To accomplish this, 0.750 kg, calculated as dry pigment, of natural calcium carbonate of the French chalk type, of granulometry such that 65% by weight of the particles have a diameter of less than 1 m, measured using the Sedigraph 5100 of the company Micromeritics, in the form of an aqueous suspension of 78% of dry content, dispersed with 0.5% of a soda polyacrylate, is diluted until an aqueous suspension with a 10% by weight dry matter concentration is obtained, using distilled water, in the 10-litre container. 3% of pure stearic acid from Fluka is then added, heated to 70 C. and mixed for 15 minutes, before treating, leaving it to cool to 60 C., the suspension thus formed by 25% of phosphoric acid in a 20% by weight solution, at 60 C., whilst stirring for 60 minutes at 500 rpm. It is left to react for 30 minutes before drying the suspension thus obtained using a Nara MSD-100 drying machine.

(34) The suspension of mineral pigment obtained before drying has a dry pigment concentration equal to 9.5% by mass, and a pH equal to 6.4.

(35) The granulometry measured using a Sedigraph 5100 is such that 93.0% of the particles have a diameter of less than 2 m and 73.1% of the particles have a diameter of less than 1 m.

(36) After drying, the product has a BET specific surface area, measured using the BET method of norm ISO 9277, equal to 28.8 m.sup.2/g and a median diameter, determined by measurement using the Sedigraph 5100, equal to 0.57 micrometer.

(37) Test n 7

(38) This test illustrates the invention and concerns a process to obtain the pigment according to the invention in which the treatment with 5% of stearic acid takes place before the reaction of the calcium carbonate with the phosphoric acid.

(39) To accomplish this, 0.750 kg, calculated as dry pigment, of natural calcium carbonate of the French chalk type, of granulometry such that 65% by weight of the particles have a diameter of less than 1 m, measured using the Sedigraph 5100 of the company Micromeritics, in the form of an aqueous suspension of 78% of dry content, dispersed with 0.5% of a soda polyacrylate, is diluted until an aqueous suspension with a 10% by weight dry matter concentration is obtained, using distilled water, in the 10-litre container. 5% of pure stearic acid from Fluka is then added, heated to 70 C. and mixed for 15 minutes, before treating, leaving it to cool to 60 C., the suspension thus formed by 25% of phosphoric acid in a 20% by weight solution, at 60 C., whilst stirring for 60 minutes at 500 rpm. It is left to react for 30 minutes before drying the suspension thus obtained using a Nara MSD-100 drying machine.

(40) The suspension of mineral pigment obtained before drying has a dry pigment concentration equal to 9.6% by mass, and a pH equal to 6.4.

(41) The granulometry measured using a Sedigraph 5100 is such that 85.3% of the particles have a diameter of less than 2 m and 61.9% of the particles have a diameter of less than 1 m.

(42) After drying, the product has a BET specific surface area, measured using the BET method of norm ISO 9277, equal to 26.5 m.sup.2/g and a median diameter, determined by measurement using the Sedigraph 5100, equal to 0.75 micrometer.

(43) Test n 8

(44) This test illustrates the invention and concerns a process to obtain the pigment according to the invention in which the treatment with 2% of stearic acid takes place during the reaction of the calcium carbonate with the phosphoric acid.

(45) To accomplish this, 200 kg, calculated as dry pigment, of natural calcium carbonate of the French chalk type, of granulometry such that 65% by weight of the particles have a diameter of less than 1 m, measured using the Sedigraph 5100 of the company Micromeritics, in the form of an aqueous suspension of 78% of dry content, dispersed with 0.5% of a soda polyacrylate, is diluted until an aqueous suspension with a 10% by weight dry matter concentration is obtained, using distilled water, in a 3000-litre recipient. The suspension thus formed is then treated with 36% of phosphoric acid in a 10% by weight solution, at 70 C. whilst stirring, for 120 minutes, at 500 rpm. 2% of stearic acid (of technical quality corresponding to a C16-C18 mixture) in powder form is then added and mixed for 30 minutes before drying the suspension obtained using a Nara MSD-100 drying machine.

(46) The suspension of mineral pigment obtained before drying has a dry pigment concentration equal to 9.2% by mass, and a pH equal to 6.8.

(47) The granulometry measured using a Sedigraph 5100 is such that 74.2% of the particles have a diameter of less than 2 m and 37.5% of the particles have a diameter of less than 1 m.

(48) After drying the product has a BET specific surface area, measured using the BET method of norm ISO 9277, equal to 31.4 m.sup.2/g and a median diameter, determined by a measurement using the Sedigraph 5100, equal to 1.31 micrometer, and a moisture content equal to 1.40% determined using the method described above.

(49) Test n 9

(50) This test illustrates the invention and concerns a process to obtain the pigment according to the invention in which the treatment with 2% of stearic acid takes place during the reaction of the calcium carbonate with the phosphoric acid, but before the dosing of the said acid.

(51) To accomplish this, 9 kg, calculated as dry pigment, of natural calcium carbonate of the French chalk type, of granulometry such that 65% by weight of the particles have a diameter of less than 1 m, measured using the Sedigraph 5100 of the company Micromeritics, in the form of an aqueous suspension of 78% of dry content, dispersed with 0.5% of a soda polyacrylate, is diluted until an aqueous suspension with a 10% by weight dry matter concentration is obtained, using distilled water, in a 135-litre Ldige type fluidised bed. The suspension thus formed is then treated with 13% of phosphoric acid in a 10% by weight solution, at 70 C. whilst stirring, for 24 minutes, at 500 rpm. 2% of stearic acid (of technical quality corresponding to a C16-C18 mixture) in powder form is then added and mixed for 30 minutes before drying the suspension obtained using a Nara MSD-100 drying machine.

(52) The suspension of mineral pigment obtained before drying has a dry pigment concentration equal to 8.2% by mass, and a pH equal to 7.1.

(53) The granulometry measured using a Sedigraph 5100 is such that 87.6% of the particles have a diameter of less than 2 m and 59.3% of the particles have a diameter of less than 1 m.

(54) After drying, the product has a BET specific surface area, measured using the BET method of norm ISO 9277, equal to 21.7 m.sup.2/g and a median diameter, determined by measurement using the Sedigraph 5100, equal to 0.83 micrometer.

(55) Test n 10

(56) This test illustrates the invention and concerns a process to obtain the pigment according to the invention in which the treatment with 1% of stearic acid takes place before the reaction of the calcium carbonate with the phosphoric acid.

(57) To accomplish this, 0.750 kg, calculated as dry pigment, of natural calcium carbonate of the French chalk type, of granulometry such that 65% by weight of the particles have a diameter of less than 1 m, measured using the Sedigraph 5100 of the company Micromeritics, in the form of an aqueous suspension of 75% of dry content, dispersed with 0.45% of a soda polyacrylate, is diluted until an aqueous suspension with a 10% by weight dry matter concentration is obtained, using distilled water, in a 10-litre ESCO reactor. 1% of stearic acid (of technical quality corresponding to a mixture of type palmitic/stearic, C16-C18) is then added and the mixture mixed for 15 minutes. The suspension thus formed is then treated with 10% of phosphoric acid in a 20% by weight solution, at 60 C. whilst stirring, for 60 minutes. It is left to react for 30 minutes before drying the suspension thus obtained using a Nara MSD-100 drying machine.

(58) The suspension of mineral pigment obtained before drying has a dry pigment concentration equal to 9.6% by mass, and a pH equal to 6.6.

(59) The granulometry measured using a Sedigraph 5100 is such that 94.8% of the particles have a diameter of less than 2 m and 67.0% of the particles have a diameter of less than 1 m.

(60) After drying, the product has a BET specific surface area, measured using the BET method of norm ISO 9277, equal to 18.9 m.sup.2/g and a median diameter, determined by measurement using the Sedigraph 5100, equal to 0.73 micrometer.

(61) Test n 11

(62) This test illustrates the invention and concerns a process to obtain the pigment according to the invention in which the treatment with 0.5% of stearic acid takes place before the reaction of the calcium carbonate with the phosphoric acid.

(63) To accomplish this, 0.750 kg, calculated as dry pigment, of natural calcium carbonate of the French chalk type, of granulometry such that 65% by weight of the particles have a diameter of less than 1 m, measured using the Sedigraph 5100 of the company Micromeritics, in the form of an aqueous suspension of 75% of dry content, dispersed with 0.5% of a soda polyacrylate, is diluted until an aqueous suspension with a 10% by weight dry matter concentration is obtained, using distilled water, in a 10-litre ESCO reactor. 0.5% of stearic acid (of technical quality corresponding to a C16-C18 mixture) is then added and the mixture mixed for 15 minutes. The suspension thus formed is then treated with 20% of phosphoric acid in a 20% by weight solution, at 60 C. whilst stirring, for 60 minutes. It is left to react for 30 minutes before drying the suspension thus obtained using a Nara MSD-100 drying machine.

(64) The suspension of mineral pigment obtained before drying has a dry pigment concentration equal to 9.3% by mass, and a pH equal to 6.6.

(65) The granulometry measured using a Sedigraph 5100 is such that 94.8% of the particles have a diameter of less than 2 m and 68.2% of the particles have a diameter of less than 1 m.

(66) After drying, the product has a BET specific surface area, measured using the BET method of norm ISO 9277, equal to 32.1 m.sup.2/g and a median diameter, determined by measurement using the Sedigraph 5100, equal to 0.74 micrometer.

(67) Test n 12

(68) This test illustrates the invention and concerns a process to obtain the pigment according to the invention in which the treatment with 1% of stearic acid takes place before the reaction of the calcium carbonate of marble type with the phosphoric acid.

(69) To accomplish this, 0.750 kg, calculated as dry pigment, of natural calcium carbonate of the Norwegian marble type, of granulometry such that 65% by weight of the particles have a diameter of less than 1 m, measured using the Sedigraph 5100 of the company Micromeritics, in the form of an aqueous suspension of 78% of dry content, dispersed with 0.62% of a soda polyacrylate, is diluted until an aqueous suspension with a 10% by weight dry matter concentration is obtained in a 10-litre ESCO reactor. 1% of stearic acid (technical quality corresponding to a C16-C18 mixture) is then added and the mixture mixed for 15 minutes. The suspension thus formed is then treated with 20% of phosphoric acid in a 20% by weight solution, at 60 C. whilst stirring, for 60 minutes. It is left to react for 30 minutes before drying the suspension thus obtained using a Nara MSD-100 drying machine.

(70) The suspension of mineral pigment obtained before drying has a dry pigment concentration equal to 9.5% by mass, and a pH equal to 6.6.

(71) The granulometry measured using a Sedigraph 5100 is such that 89.6% of the particles have a diameter of less than 2 m and 64.5% of the particles have a diameter of less than 1 m.

(72) After drying the product has a BET specific surface area, measured using the BET method of norm ISO 9277, equal to 40.2 m.sup.2/g and a median diameter, determined by a measurement using the Sedigraph 5100, equal to 0.75 micrometer and a moisture content equal to 1.41% determined using the method described above.

(73) Test n 13

(74) This test illustrates the invention and concerns a process to obtain pigment according to the invention in which the treatment with stearic acid takes place before the reaction of the calcium carbonate with the phosphoric acid, since the test uses Winnofil SPT from the company Solvay which is a precipitated calcium carbonate treated by a fatty acid the granulometry of which measured using the Sedigraph 5100 is such that 89.6% of the particles have a diameter of less than 2 m and 64.5% of the particles have a diameter of less than 1 m, and the BET specific surface area is equal to 17.8 m.sup.2/g (measured using the BET method of norm ISO 9277).

(75) To accomplish this, 0.750 kg of Winnofil SPT, calculated as dry pigment, in the form of an aqueous suspension of 78% of dry content, dispersed with 0.5% of a soda polyacrylate, is diluted until an aqueous suspension is obtained with a 10% by weight dry matter concentration is obtained, using distilled water, in the 10-litre ESCO reactor. The suspension thus formed is then treated by 20% of phosphoric acid in a 20% by weight solution, at 60 C. whilst stirring for 60 minutes before drying the suspension obtained using a Nara MSD-100 drying machine.

(76) The suspension of mineral pigment obtained before drying has a dry pigment concentration equal to 9.3% by mass, and a pH equal to 6.4.

(77) The granulometry measured using a Sedigraph 5100 is such that 62.9% of the particles have a diameter of less than 2 m and 51.4% of the particles have a diameter of less than 1 m.

(78) After drying, the product has a BET specific surface area, measured using the BET method of norm ISO 9277, equal to 52.1 m.sup.2/g and a median diameter, determined by measurement using the Sedigraph 5100, equal to 0.90 micrometer.

(79) Test n 14

(80) This test illustrates the invention and concerns a process to obtain pigment according to the invention in which the treatment with stearic acid takes place before the reaction of the calcium carbonate with the phosphoric acid, since the test uses Socal 322 from the company Solvay which is a precipitated calcium carbonate treated by a fatty acid the granulometry of which measured using the Sedigraph 5100 is such that 90.0% of the particles have a diameter of less than 2 m and 86.0% of the particles have a diameter of less than 1 m, and the BET specific surface area is equal to 17.5 m.sup.2/g (measured using the BET method of norm ISO 9277).

(81) To accomplish this, 0.750 kg of Socal 322, calculated as dry pigment, in the form of an aqueous suspension of 78% of dry content, dispersed with 0.5% of a soda polyacrylate, is diluted until an aqueous suspension with a 10% by weight dry matter concentration is obtained, using distilled water, in the 10-litre ESCO reactor. The suspension thus formed is then treated by 20% of phosphoric acid in a 20% by weight solution, at 60 C. whilst stirring for 60 minutes before drying the suspension obtained using a Nara MSD-100 drying machine.

(82) The suspension of mineral pigment obtained before drying has a dry pigment concentration equal to 9.3% by mass, and a pH equal to 6.3.

(83) The granulometry measured using a Sedigraph 5100 is such that 87.9% of the particles have a diameter of less than 2 m and 77.9% of the particles have a diameter of less than 1 m.

(84) After drying, the product has a BET specific surface area, measured using the BET method of norm ISO 9277, equal to 48.4 m.sup.2/g and a median diameter, determined by measurement using the Sedigraph 5100, equal to 0.30 micrometer.

(85) Test n 15

(86) This test illustrates the invention and concerns a process to obtain the pigment according to the invention in which the treatment with 2% of a mixture of fatty acid and fatty alcohol takes place before the reaction of the calcium carbonate of chalk type with the phosphoric acid.

(87) To accomplish this, 0.750 kg, calculated as dry pigment, of natural calcium carbonate of the French chalk type, of granulometry such that 65% by weight of the particles have a diameter of less than 1 m, measured using the Sedigraph 5100 of the company Micromeritics, in the form of an aqueous suspension of 75% of dry content, dispersed with 0.5% of a soda polyacrylate, is diluted until an aqueous suspension with a 10% by weight dry matter concentration is obtained, using distilled water, in the 10-litre ESCO reactor. 0.2% of vegetal oil-based fatty acid sold by the company Hobum Oleochemicals (Hamburg, Germany) under the acid name isomergine is then added with 1.8% of stearilic acid, and the mixture is mixed for 15 minutes. The suspension thus formed is then treated with 25% of phosphoric acid in a 30% by weight solution, at 60 C. whilst stirring, for 60 minutes. It is left to react for 30 minutes before drying the suspension thus obtained using a Nara MSD-100 drying machine.

(88) The suspension of mineral pigment obtained before drying has a dry pigment concentration equal to 9.8% by mass, and a pH equal to 6.0.

(89) The granulometry measured using a Sedigraph 5100 is such that 74.1% of the particles have a diameter of less than 2 m and 38.0% of the particles have a diameter of less than 1 m.

(90) After drying, the product has a BET specific surface area, measured using the BET method of norm ISO 9277, equal to 24.0 m.sup.2/g and a median diameter, determined by measurement using the Sedigraph 5100, equal to 1.29 micrometer.

(91) Test n 16

(92) This test illustrates the invention and concerns a process to obtain the pigment according to the invention in which the treatment with 2% of a mixture of fatty acid and fatty alcohol takes place before the reaction of the calcium carbonate of chalk type with the phosphoric acid.

(93) To accomplish this, 0.750 kg, calculated as dry pigment, of natural calcium carbonate of the French chalk type, of granulometry such that 32% by weight of the particles have a diameter of less than 1 m, measured using the Sedigraph 5100 of the company Micromeritics, in the form of an aqueous suspension of 65% of dry content, dispersed with 0.13% of a soda polyacrylate, is diluted until an aqueous suspension with a 10% by weight dry matter concentration is obtained, using distilled water, in the 10-litre ESCO reactor. 0.5% of vegetal oil-based fatty acid sold by the company Hobum Oleochemicals (Hamburg, Germany) under the acid name isomergine is then added with 1.5% of dodecylic alcohol, and the mixture is mixed for 15 minutes; subsequently the suspension thus formed is treated by 25% of phosphoric acid in a solution 30% by weight, at 60 C. whilst stirring for 60 minutes. It is left to react for 30 minutes before drying the suspension thus obtained using a Nara MSD-100 drying machine.

(94) The suspension of mineral pigment obtained before drying has a dry pigment concentration equal to 9.8% by mass, and a pH equal to 6.0.

(95) The granulometry measured using a Sedigraph 5100 is such that 57.3% of the particles have a diameter of less than 2 m and 25.3% of the particles have a diameter of less than 1 m.

(96) After drying, the product has a BET specific surface area, measured using the BET method of norm ISO 9277, equal to 31.0 m.sup.2/g and a median diameter, determined by measurement using the Sedigraph 5100, equal to 1.79 micrometer.

(97) Test n 17

(98) This test illustrates the invention and concerns a process to obtain the pigment according to the invention in which the treatment with 2% of fatty acid takes place before the reaction of the calcium carbonate of chalk type with the phosphoric acid.

(99) To accomplish this, 0.750 kg, calculated as dry pigment, of natural calcium carbonate of the French chalk type, of granulometry such that 32% by weight of the particles have a diameter of less than 1 m, measured using the Sedigraph 5100 of the company Micromeritics, in the form of an aqueous suspension of 65% of dry content, dispersed with 0.13% of a soda polyacrylate, is diluted until an aqueous suspension with a 10% by weight dry matter concentration is obtained, using distilled water, in the 10-litre ESCO reactor. 2.0% of stearilic alcohol is then added and the mixture is mixed for 15 minutes; the suspension thus formed is then treated with 25% of phosphoric acid in a 30% by weight solution, at 60 C. whilst stirring for 60 minutes. It is left to react for 30 minutes before drying the suspension thus obtained using a Nara MSD-100 drying machine.

(100) The suspension of mineral pigment obtained before drying has a dry pigment concentration equal to 9.8% by mass, and a pH equal to 6.1.

(101) The granulometry measured using a Sedigraph 5100 is such that 74.8% of the particles have a diameter of less than 2 m and 36.8% of the particles have a diameter of less than 1 m.

(102) After drying, the product has a BET specific surface area, measured using the BET method of norm ISO 9277, equal to 23.9 m.sup.2/g and a median diameter, determined by measurement using the Sedigraph 5100, equal to 1.30 micrometer.

(103) Test n 18

(104) This test illustrates the invention and concerns a process to obtain the pigment according to the invention in which the treatment with 2% of stearic acid is undertaken continuously during the manufacture of the precipitated calcium carbonate and treatment with the moderately strong to strong H3O+ ion donator.

(105) To accomplish this, the process is undertaken by preparing 400 g of Ca(OH).sub.2 in 7600 g of distilled water in the 10-litre ESCO reactor, followed by the addition of CO.sub.2 in gaseous form at 30 C. until a pH equal to 6.5 is obtained.

(106) After having left it to react for 30 minutes, the suspension is heated in the reactor to 60 C., after which 2.0% of stearic acid is added and the mixture mixed for 15 minutes; the suspension thus formed is then treated with 20% of phosphoric acid in a 30% by weight solution, whilst stirring for 60 minutes. It is left to react for 30 minutes before drying the suspension thus obtained using a Nara MSD-100 drying machine.

(107) The suspension of mineral pigment obtained before drying has a dry pigment concentration equal to 5.7% by mass, and a pH equal to 6.4.

(108) The granulometry measured using a Sedigraph 5100 is such that 41.4% by weight of the particles have a diameter of less than 2 m and 18.1% by weight of the particles have a diameter of less than 1 m.

(109) After drying, the product has a BET specific surface area, measured using the BET method of norm ISO 9277, equal to 37.9 m.sup.2/g and a median diameter, determined by measurement using the Sedigraph 5100, equal to 2.29 micrometer.

(110) Test n 19

(111) This test illustrates the invention and concerns a process to obtain pigment according to the invention in which the treatment with 1% of fatty acid takes place before the reaction of the calcium carbonate of chalk type with the phosphoric acid.

(112) To accomplish this, 0.750 kg, calculated as dry pigment, of natural calcium carbonate of the French chalk type, of granulometry such that 50% by weight of the particles have a diameter of less than 1 m, measured using the Sedigraph 5100 of the company Micromeritics, in the form of an aqueous suspension of 75% of dry content, dispersed with 0.6% of a soda polyacrylate, is diluted until an aqueous suspension with a 10% by weight dry matter concentration is obtained, using distilled water, in the 10-litre ESCO reactor. 1.0% of stearic acid is then added and the mixture is mixed for 15 minutes. The suspension thus formed is then treated with 25% of phosphoric acid in a 20% by weight solution, at 60 C. whilst stirring, for 60 minutes. It is left to react for 30 minutes before drying the suspension thus obtained using a Nara MSD-100 drying machine.

(113) The suspension of mineral pigment obtained before drying has a dry pigment concentration equal to 9.3% by mass, and a pH equal to 6.5.

(114) The granulometry measured using a Sedigraph 5100 is such that 94.9% by weight of the particles have a diameter of less than 2 m and 67.0% by weight of the particles have a diameter of less than 1 m.

(115) After drying, the product has a BET specific surface area, measured using the BET method of norm ISO 9277, equal to 34.9 m.sup.2/g and a median diameter, determined by measurement using the Sedigraph 5100, equal to 0.76 micrometer.

(116) Test n 20

(117) This test illustrates the invention and concerns a process to obtain pigment according to the invention in which the treatment with 1% of fatty acid takes place after the reaction of the calcium carbonate of chalk type with the phosphoric acid.

(118) To accomplish this, 0.750 kg, calculated as dry pigment, of natural calcium carbonate of the French chalk type, of granulometry such that 50% by weight of the particles have a diameter of less than 1 m, measured using the Sedigraph 5100 of the company Micromeritics, in the form of an aqueous suspension of 75% of dry content, dispersed with 0.6% of a soda polyacrylate, is diluted until an aqueous suspension with a 10% by weight dry matter concentration is obtained, using distilled water, in the 10-litre ESCO reactor. The suspension thus formed is then treated with 20% of phosphoric acid in a 20% by weight solution, at 60 C. whilst stirring, for 60 minutes, at 500 rpm. 1% of stearic acid in powder form is then added and mixed for 30 minutes before drying the suspension obtained using a Nara MSD-100 drying machine.

(119) The suspension of mineral pigment obtained before drying has a dry pigment concentration equal to 9.5% by mass, and a pH equal to 6.5.

(120) The granulometry measured using a Sedigraph 5100 is such that 94.1% by weight of the particles have a diameter of less than 2 m and 66.2% by weight of the particles have a diameter of less than 1 m.

(121) After drying, the product has a BET specific surface area, measured using the BET method of norm ISO 9277, equal to 30.4 m.sup.2/g and a median diameter, determined by measurement using the Sedigraph 5100, equal to 0.77 micrometer.

(122) Test n 21

(123) This test illustrates the invention and concerns a process to obtain pigment according to the invention in which the treatment with 2% of sulphonic dodecylbenzene takes place after the reaction of the calcium carbonate of chalk type with the phosphoric acid.

(124) To accomplish this, 0.750 kg, calculated as dry pigment, of natural calcium carbonate of the French chalk type, of granulometry such that 50% by weight of the particles have a diameter of less than 1 m, measured using the Sedigraph 5100 of the company Micromeritics, in the form of an aqueous suspension of 75% of dry content, dispersed with 0.6% of a soda polyacrylate, is diluted until an aqueous suspension with a 10% by weight dry matter concentration is obtained, using distilled water, in the 10-litre ESCO reactor. The suspension thus formed is then treated with 25% of phosphoric acid in a 30% by weight solution, at 60 C. whilst stirring, for 60 minutes, at 500 rpm. 2% of sulphonic dodecylbenzene acid in powder form is then added and mixed for 30 minutes before drying the suspension obtained using the Nara MSD-100 drying machine.

(125) The suspension of mineral pigment obtained before drying has a dry pigment concentration equal to 10.0% by mass, and a pH equal to 6.6.

(126) The granulometry measured using a Sedigraph 5100 is such that 93.9% by weight of the particles have a diameter of less than 2 m and 59.6% by weight of the particles have a diameter of less than 1 m.

(127) After drying, the product has a BET specific surface area, measured using the BET method of norm ISO 9277, equal to 35.4 m.sup.2/g and a median diameter, determined by measurement using the Sedigraph 5100, equal to 0.87 micrometer.

(128) Test n 22

(129) This test illustrates the invention and concerns a process to obtain pigment according to the invention in which the treatment with 2% of lauric acid takes place after the reaction of the calcium carbonate of marble type with the phosphoric acid.

(130) To accomplish this, 0.750 kg, calculated as dry pigment, of natural calcium carbonate of the Norwegian marble type, of granulometry such that 65% by weight of the particles have a diameter of less than 1 m, measured using the Sedigraph 5100 of the company Micromeritics, in the form of an aqueous suspension of 78% of dry content, dispersed with 0.62% of a soda polyacrylate, is diluted until an aqueous suspension with a 10% by weight dry matter concentration is obtained in a 10-litre ESCO reactor. The suspension thus formed is then treated with 20% of phosphoric acid in a 30% by weight solution, at 60 C. whilst stirring, for 60 minutes. 2% of laurylic acid is then added and mixed for 30 minutes before drying the suspension obtained using a Nara MSD-100 drying machine.

(131) The suspension of mineral pigment obtained before drying has a dry pigment concentration equal to 9.8% by mass, and a pH equal to 6.8.

(132) The granulometry measured using a Sedigraph 5100 is such that 88.8% by weight of the particles have a diameter of less than 2 m and 64.8% by weight of the particles have a diameter of less than 1 m.

(133) After drying the product has a BET specific surface area, measured using the BET method of norm ISO 9277, equal to 35.0 m.sup.2/g and a median diameter, determined by a measurement using the Sedigraph 5100, equal to 0.65 micrometer and a moisture content equal to 1.26% determined using the method described above.

EXAMPLE 3

(134) This example concerns the use of the pigments according to the invention as a rheology regulator for the preparation of a polyvinyl chloride (PVC)-based plastisol.

(135) The charged plastisol is produced by mixing the non-charged PVC-based plastisol and the calcium carbonate, or again the mineral pigment for testing in a recipient measuring 7 cm in diameter and by blending with a spatula. The total weight of the mixture is 200 g. The mixture is then dispersed for two minutes using a Pendraulik LD50 laboratory mixing machine, where the diameter of the dispersion disk is 5 cm, and the speed of rotation of the disk is 2700 rpm (manual adjustment to position three).

(136) When the dispersion is completed, the viscosity is measured using the Rheomat 120 machine, a measuring machine according to norm DIN 125, at 20 C.

(137) The pour point is determined using the Bingham model, which is well known to the skilled man in the art, after ageing for 24 hours and 30 days at a temperature of 23 C.

(138) In all the tests of the example, the aim of which is to obtain a lightened motor vehicle body with a rheology of constant formulation, the formulation of the PVC (polyvinyl chloride)-based plastisol has as its formulation the following formulation 1: 90% by weight of Henkel-Teroson's PVC resin plastisol, 10% by weight of the mineral filler for testing.

(139) Test n 23

(140) This test illustrates the prior art and uses the precipitated calcium carbonate sold by the company Solvay under the name Winnofil SPT. This test is used as a reference.

(141) Test n 24

(142) This test illustrates the prior art and uses a calcium carbonate from test n 1. The pour point after 30 days' ageing at 23 C. in formulation 1 is 63.6% higher than that of test n 23.

(143) Test n 25

(144) This test illustrates the prior art and uses a calcium carbonate from test n 3 treated with 3% of stearic acid after drying. The treatment was undertaken for ten minutes in a laboratory mixer from MTI at 120 C.; the rotational speed was 1500 rpm. The pour point after 30 days' ageing at 23 C. in formulation 1 is 49.0% lower than that of test n 23.

(145) Treatment after drying does not work.

(146) Test n 26

(147) This test illustrates the prior art and uses a precipitated calcium carbonate sold by the company Solvay under the name Socal 322. The pour point after 30 days' ageing at 23 C. in formulation 1 is 16.8% higher than that of test n 23.

(148) Test n 27

(149) This test illustrates the prior art and uses a calcium carbonate sold by the company Omya under the name Hydrocarb 120T. The pour point after 30 days' ageing at 23 C. in formulation 1 is 7.7% lower than that of test n 23.

(150) Test n 28

(151) This test illustrates the prior art and uses a calcium carbonate sold by the company Omya under the name Omyabond 302. The pour point after 30 days' ageing at 23 C. in formulation 1 is 1.4% higher than that of test n 23.

(152) Test n 29

(153) This test illustrates the prior art and uses a calcium carbonate sold by the company Omya under the name Omyabond 301. The pour point after 30 days' ageing at 23 C. in formulation 1 is 24.5% lower than that of test n 23.

(154) Test n 30

(155) This test illustrates the invention and uses the calcium carbonate of test n 4. The pour point after 30 days' ageing at 23 C. in formulation 1 is 53.1% higher than that of test n 23.

(156) Test n 31

(157) This test illustrates the invention and uses the calcium carbonate of test n 5. The pour point after 30 days' ageing at 23 C. in formulation 1 is 102.1% higher than that of test n 23.

(158) Test n 32

(159) This test illustrates the invention and uses the calcium carbonate of test n 6. The pour point after 30 days' ageing at 23 C. in formulation 1 is 36.4% higher than that of test n 23.

(160) Test n 33

(161) This test illustrates the invention and uses the calcium carbonate of test n 7. The pour point after 30 days' ageing at 23 C. in formulation 1 is 4.2% higher than that of test n 23.

(162) Test n 34

(163) This test illustrates the invention and uses the calcium carbonate of test n 8. The pour point after 30 days' ageing at 23 C. in formulation 1 is 86.7% higher than that of test n 23.

(164) All the results of the above tests are recorded in table 1 below.

(165) TABLE-US-00001 TABLE 1 Test n 23 24 25 26 27 28 29 30 31 32 33 34 Filler rate CaCO.sub.3 10 10 10 10 10 10 10 10 10 10 10 10 (% by weight) Viscosity Shearing 162 280 88 193 150 164 140 274 325 263 216 324 [Pa] at speed 20 s.sup.1 Shearing speed 756 813 556 839 650 685 738 1093 1224 1139 1037 1433 300 s.sup.1 Pour point 179 304 95 236 180 173 147 283 360 314 275 282 After ageing for 24 h Pour point 143 234 73 167 132 145 108 219 289 195 149 267 After ageing for 30 days

(166) A reading of table 1 enables it to be seen the satisfactory rheology results obtained with the products according to the invention.

EXAMPLE 4

(167) This example concerns the use of the pigments according to the invention as a rheology regulator for the preparation of a polyvinyl chloride (PVC)-based plastisol and of a formulation different to that of example 3.

(168) To accomplish this a formulation 2 is produced with the same operating method and the same equipment as in example 3.

(169) This formulation 2, a PVC-based plastisol, consists of: 24% by weight of a PVC resin Vestolit E 7031 (Vestolit, Germany), 6.0% by weight of a PVC resin Vestolit C 65 (Vestolit, Germany), 47.0% by weight of a plasticiser DINP (Diisononylphthalate), 2.0% by weight of a desiccative Super Weisskalk 40 (Omya AG, Switzerland), 1.0% by weight of an adhesion promoter EURETEK 505 (Ciba SC, Switzerland), 20.0% by weight of mineral pigment for testing.

(170) For each of the tests in the example, the viscosity and pour point measurements are undertaken using the same operating method and the same equipment as in the previous example.

(171) Test n 35

(172) This test illustrates the prior art and uses the precipitated calcium carbonate sold by the company Solvay under the name Winnofil SPT. This test is used as a reference.

(173) Test n 36

(174) This test illustrates the prior art and uses a precipitated calcium carbonate sold by the company Solvay under the name Socal 322. The pour point after 30 days' ageing at 23 C. in formulation 2 is 108.3% higher than that of test n 35.

(175) Test n 37

(176) This test illustrates the prior art and uses a calcium carbonate sold by the company Omya under the name Omyabond 302. The pour point after 30 days' ageing at 23 C. in formulation 2 is 102.8% higher than that of test n 35.

(177) Test n 38

(178) This test illustrates the prior art and uses a calcium carbonate sold by the company Omya under the name Omyabond 301. The pour point after 30 days' ageing at 23 C. in formulation 2 is 58.3% lower than that of test n 35.

(179) Test n 39

(180) This test illustrates the prior art and uses a calcium carbonate from test n 2. The pour point after 30 days' ageing at 23 C. in formulation 2 is 275% higher than for that of test no 35.

(181) Test n 40

(182) This test illustrates the invention and uses the calcium carbonate of test n 11. The pour point after 30 days' ageing at 23 C. in formulation 2 is 275% higher than that of test n 35.

(183) Test n 41

(184) This test illustrates the invention and uses the calcium carbonate of test n 12. The pour point after 30 days' ageing at 23 C. in formulation 2 is 319.4% higher than that of test n 35.

(185) Test n 42

(186) This test illustrates the invention and uses the calcium carbonate of test n 13. The pour point after 30 days' ageing at 23 C. in formulation 2 is 350% higher than that of test n 35.

(187) Test n 43

(188) This test illustrates the invention and uses the calcium carbonate of test n 14. The pour point after 30 days' ageing at 23 C. in formulation 2 is 422.2% higher than that of test n 35.

(189) All the results of the example are recorded in table 2 below.

(190) TABLE-US-00002 TABLE 2 Test n 35 36 37 38 39 40 41 42 43 Filler rate (% CaCO.sub.3 20 20 20 20 20 20 20 20 20 by weight) Viscosity Shearing 65 98 85 38 158 160 180 195 216 [Pa] at speed 20 s.sup.1 Shearing 573 614 536 465 675 692 797 968 860 speed 300 s.sup.1 Pour point 45 166 61 35 275 289 334 412 443 After ageing for 24 h Pour point 36 75 73 15 135 135 151 162 188 After ageing for 30 days

(191) A reading of table 2 enables it to be seen that the best rheology results are obtained with the products according to the invention.

EXAMPLE 5

(192) This example concerns the use of the pigments according to the invention as a rheology regulator for the preparation of a polyvinyl chloride (PVC)-based plastisol and of a formulation different to that of examples 3 and 4.

(193) To accomplish this a formulation 3 is produced with the same operating method and the same equipment as in example 3.

(194) This formulation 3, a PVC-based plastisol, consists of: 31.0% by weight of a PVC resin Vestolit E 7031 (Vestolit, Germany), 43.0% by weight of a plasticiser DINP (Diisononylphthalate), 1.5% by weight of a desiccative Super Weisskalk 40 (Omya AG, Switzerland), 1.0% by weight of an adhesion promoter EURETEK 505 (Ciba SC, Switzerland), 1.0% by weight of a thermal stabiliser Irgastab 17 M (Ciba SC, Switzerland), 22.5% by weight of mineral pigment for testing.

(195) For each of the tests in the example, the viscosity and pour point measurements are undertaken using the same operating method and the same equipment as in the previous example.

(196) Test n 44

(197) This test illustrates the prior art and uses the precipitated calcium carbonate sold by the company Solvay under the name Winnofil SPT. This test is used as a reference.

(198) Test n 45

(199) This test illustrates the prior art and uses a precipitated calcium carbonate sold by the company Solvay under the name Socal 322. The pour point after 30 days' ageing at 23 C. in formulation 3 is 200% higher than that of test n 44.

(200) Test n 46

(201) This test illustrates the prior art and uses a calcium carbonate sold by the company Omya under the name Omyabond 302. The pour point after 30 days' ageing at 23 C. in formulation 3 is 55.3% lower than that of test n 44.

(202) Test n 47

(203) This test illustrates the prior art and uses a calcium carbonate sold by the company Omya under the name Omyabond 301. The pour point after 30 days' ageing at 23 C. in formulation 3 is 12.8% higher than that of test n 44.

(204) Test n 48

(205) This test illustrates the invention and uses the calcium carbonate of test n 15. The pour point after 30 days' ageing at 23 C. in formulation 3 is 342.6% higher than that of test n 44.

(206) Test n 49

(207) This test illustrates the invention and uses the calcium carbonate of test n 16. The pour point after 30 days' ageing at 23 C. in formulation 3 is 712.8% higher than that of test n 44.

(208) Test n 50

(209) This test illustrates the invention and uses the calcium carbonate of test n 17. The pour point after 30 days' ageing at 23 C. in formulation 3 is 459.6% higher than that of test n 44.

(210) Test n 51

(211) This test illustrates the invention and uses the calcium carbonate of test n 18. The pour point after 30 days' ageing at 23 C. in formulation 3 is 740.4% higher than that of test n 44.

(212) All the results of the example are recorded in table 3 below.

(213) TABLE-US-00003 TABLE 3 Test n 44 45 46 47 48 49 50 51 Filler rate (% CaCO.sub.3 22.5 22.5 22.5 22.5 22.5 22.5 22.5 22.5 by weight) Viscosity [Pa] Shearing 104 181 58 96 276 453 302 418 at speed 20 s.sup.1 Shearing 1111 1139 783 898 1355 1789 1383 1690 speed 300 s.sup.1 Pour point 90 158 22 69 245 400 312 307 After ageing for 24 h Pour point 47 141 21 53 208 382 263 395 After ageing for 30 days

(214) A reading of the results of table 3 shows that one also obtains satisfactory rheological results by using mixtures of fatty acids and fatty alcohols or again by using only fatty alcohols.

(215) Test n 51 shows that the invention is also applicable during the manufacture of precipitated calcium carbonate.

EXAMPLE 6

(216) This example concerns the use of the pigments according to the invention as a rheology regulator for the preparation of a polyvinyl chloride (PVC)-based plastisol the formulation of which differs from that of example 5 by the rate of filler for testing.

(217) To accomplish this a formulation 4 is produced with the same operating method and the same equipment as in example 3.

(218) This formulation 4, a PVC-based plastisol, consists of: 31.0% by weight of a PVC resin Vestolit E 7031 (Vestolit, Germany), 43.0% by weight of a plasticiser DINP (Diisononylphthalate), 1.5% by weight of a desiccative Super Weisskalk 40 (Omya AG, Switzerland), 1.0% by weight of an adhesion promoter EURETEK 505 (Ciba SC, Switzerland), 1.0% by weight of a thermal stabiliser Irgastab BZ 529 (Ciba SC, Switzerland), 15.0% to 22.5% by weight of mineral pigment for testing.

(219) For each of the tests in the example, the viscosity and pour point measurements are undertaken using the same operating method and the same equipment as in the previous example.

(220) Test n 52

(221) This test illustrates the prior art and uses 22.5% of the precipitated calcium carbonate sold by the company Solvay under the name Winnofil SPT. This test is used as a reference.

(222) Test n 53

(223) This test illustrates the prior art and uses 22.5% of the precipitated calcium carbonate sold by the company Solvay under the name Socal 322. The pour point after 30 days' ageing at 23 C. in formulation 4 is 42% higher than that of test n 52.

(224) Test n 54

(225) This test illustrates the invention and uses 20.0% of the calcium carbonate of test n 21.

(226) Test n 55

(227) This test illustrates the invention and uses 15.0% of the calcium carbonate of test n 21.

(228) Test n 56

(229) This test illustrates the invention and uses 20.0% of the calcium carbonate of test n 22.

(230) Test n 57

(231) This test illustrates the invention and uses 15.0% of the calcium carbonate of test n 22.

(232) All the results of the example are recorded in table 4 below.

(233) TABLE-US-00004 TABLE 4 Test n 52 53 54 55 56 57 Filler rate (% CaCO.sub.3 22.5 22.5 20.0 15.0 20.0 15.0 by weight) Viscosity Shearing 153 213 314 133 408 178 [Pa] at speed 20 s.sup.1 Shearing 1008 1031 1250 844 1409 925 speed 300 s.sup.1 Pour point 101 207 283 112 300 196 After ageing for 24 h Pour point 131 186 261 133 349 178 After ageing for 30 days

(234) A reading of table 4 above enables one to observe that the use of the pigment according to the invention allows a reduction of the mineral filler of the plastisols to reach the same pour point as with the pigments habitually used of approximately 33%, at least, resulting in a reduction in the weight of filled plastisol.

EXAMPLE 7

(235) This example illustrates the invention and concerns the use of the pigments according to the invention made using rigid PVC (rigid polyvinyl chloride), such as the frame of motor vehicle bodies, with a view to reducing the weight, whilst retaining control of solidity.

(236) In the various tests of the example the replacement of the calcium carbonate of the prior art by mineral pigment according to the invention was tested.

(237) In a rigid PVC formulation, it was sought to compare the influence of 100% substitution of the mineral filler of prior art by a mineral pigment according to the invention.

(238) To accomplish this, the traction resistance (which is representative of solidity for the skilled man in the art) of the following rigid PVC formulation was measured: 100 phr. of a rigid PVC resin EVIPOLSH 6521 (EVC, Germany), 1.5 phr. of a thermal stabiliser of tribasic lead sulphate Naftorin T 3 (Chemson, England), 1.5 phr. of a thermal stabiliser of dibasic lead sulphate Listab 51 (Chemson, England), 0.6 phr. of a lubricant Ca F 1 (Hoechst, Germany), 0.05 phr of a lubricant E-Wachs (Hoechst, Germany), 30 phr. mineral pigment for testing.

(239) The rigid PVC resin and the mineral filler for testing are mixed in a two-roller grinding machine (Collin, type 150400) at a temperature of 190 C. The rigid PVC plate is calendered after moulding by compression in plate form at 190 C. (Collin, type P 300 P).

(240) Specimens are formed from this plate for the traction test according to norm DIN 53 455. Traction resistance measurement is undertaken using the Zwick/Roell Z020 instrument and according to norm DIN 53 455.

(241) Test n 58

(242) This test illustrates the prior art and uses the precipitated calcium carbonate sold by the company Solvay under the name Winnofil SPT. This test is used as a reference.

(243) Test n 59

(244) This test illustrates the prior art and uses the precipitated calcium carbonate sold by the company Solvay under the name Socal 322.

(245) Use of Socal 322 results in the same traction resistance as use of Winnofil SPT.

(246) Test n 60

(247) This test illustrates the prior art and uses the calcium carbonate sold by the company Omya under the name Hydrocarb 120T. Use of Hydrocarb 120T results in the same traction resistance as use of Winnofil SPT.

(248) Test n 61

(249) This test illustrates the prior art and uses the calcium carbonate sold by the company Omya under the name Omyabond 301.

(250) Use of Omyabond 301 results in the same traction resistance as use of Winnofil SPT.

EXAMPLE 8

(251) This example illustrates the invention and concerns mineral pigments according to the invention (tests no 62, 63, 64 and 65), their manufacturing process according to the invention (tests no 62, 63, 64 and 65), and their use according to the invention in plastisol-type PVC formulations (tests no 63, 64 and 65).

(252) Test n 62

(253) This test illustrates the invention and concerns a process to obtain the pigment according to the invention in which the treatment with 1% of a mixture of fatty acids takes place before the reaction of the calcium carbonate of marble type with the phosphoric acid.

(254) To accomplish this, 6,974 kg (by weight of dry pigment) of natural calcium carbonate of the Norwegian marble type, of granulometry such that 65% by weight of the particles have a diameter of less than 1 m, measured using the Sedigraph 5100 of the company Micromeritics, in the form of an aqueous suspension of 78% of dry content, dispersed with 0.5% of a soda polyacrylate, is diluted until an aqueous suspension with a 65% by weight of dry matter is obtained, using distilled water, in the 10-litre ESCO reactor.

(255) The suspension thus formed is then treated, at a temperature equal to 70 C., with 1% of fatty acid in suspension, consisting in a oil of sunflower, based on palmitic acid, stearic acid, oleic acid, linoleic and linolenic acid, with a CAS number equal to 67701-08-0.

(256) After 5 minutes of stirring, the suspension thus formed is treated with 1% of phosphoric acid in a 10% by weight solution, under stirring during 30 minutes.

(257) After the addition of 94 g of calcium hydroxide of 14% by weight, the suspension has a pH equal to 8.6 and a percentage of dry solid content equal to 62.2%.

(258) The suspension thus obtained is dried at 80 C., using a Nara MSD-100 drying machine.

(259) A mineral pigment according to the invention is thus obtained.

(260) Test n 63

(261) This test illustrates the invention and concerns a process to obtain the pigment according to the invention in which the treatment with 1% of a mixture of fatty acids takes place after the reaction of the calcium carbonate of marble type with the phosphoric acid.

(262) To accomplish this, 0,707 kg (by weight of dry pigment) of natural calcium carbonate of the Norwegian marble type, of granulometry such that 65% by weight of the particles have a diameter of less than 1 m, measured using the Sedigraph 5100 of the company Micromeritics, in the form of an aqueous suspension of 78% of dry content, dispersed with 0.5% of a soda polyacrylate, is diluted until an aqueous suspension with a 65% by weight of dry matter is obtained, using distilled water, in the 10-litre ESCO reactor.

(263) The suspension thus formed is then treated, at a temperature equal to 70 C., with 50% of phosphoric acid in a 10% by weight solution, under stirring during 30 minutes

(264) Then, 1% of fatty acids consisting in a mixture of palmitic acid and stearic acid in a weight ratio 1/1, in a powder form, is added

(265) After the addition of 135 g of calcium hydroxide of 14% by weight, the suspension has a pH equal to 8.1 and a percentage of dry solid content equal to 7.5%.

(266) The suspension thus obtained is dried at 80 C., using a Nara MSD-100 drying machine.

(267) A plastisol-type PVC formulation is then prepared, comprising, in percentage of weight, 33.4% of Vestolit E 7031, 44% of diisononyl phthalate, 1.6% of Weisskalk Super 40, 1% of Euretek 505 and 20% of the mineral pigment according to the invention previously obtained.

(268) The yield point of this composition, measured after 72 hours according to the methods well known by the skilled man in the art, is equal to 548 Pa.

(269) Test n 64

(270) This test illustrates the invention and concerns a process to obtain the pigment according to the invention in which the treatment with 0.5% of a mixture of fatty acids takes place after the reaction of the calcium carbonate of marble type with a mixture of phosphoric acid and sulphuric acid.

(271) To accomplish this, 0.698 kg (by weight of dry pigment) of natural calcium carbonate of the Norwegian marble type, of granulometry such that 65% by weight of the particles have a diameter of less than 1 m, measured using the Sedigraph 5100 of the company Micromeritics, in the form of an aqueous suspension of 78% of dry content, dispersed with 0.5% of a soda polyacrylate, is diluted until an aqueous suspension with a 65% by weight of dry matter is obtained, using distilled water, in the 10-litre ESCO reactor.

(272) The suspension thus formed is then treated, at a temperature equal to 70 C., with 50% of a mixture of phosphoric acid and sulphuric acid in a 10% by weight solution, under stirring during 60 minutes

(273) Then, the obtained suspension is treated with 0.5% of fatty acids in suspension, consisting in a linseed oil, with a composition in weight of 8% of fatty acids having from 12 to 16 carbon atoms, 3% of stearic acid, 19% of oleic acid, 16% of linoleic acid, 52% of linolenic acid and 2% of acid having from 20 to 22 carbon atoms.

(274) After the addition of 250 g of calcium hydroxide of 14% by weight, the suspension has a pH equal to 8.1 and a percentage of dry solid content equal to 7.55%.

(275) The suspension thus obtained is dried at 80 C., using a Nara MSD-100 drying machine.

(276) A plastisol-type PVC formulation is then prepared, comprising, in percentage of weight, 35.4% of Vestolit E 7031, 46.8% of diisononyl phthalate, 1.7% of Weisskalk Super 40, 1.1% of Euretek 505 and 15% of the mineral pigment according to the invention previously obtained.

(277) The yield point of this composition, measured after 72 hours according to the methods well known by the skilled man in the art, is equal to 510 Pa.

(278) Test n 65

(279) This test illustrates the invention and concerns a process to obtain the pigment according to the invention in which the treatment with 0.2% of a mixture of fatty acids takes place after the reaction of the calcium carbonate of marble type with the phosphoric acid.

(280) To accomplish this, 0.694 kg (by weight of dry pigment) of natural calcium carbonate of the Norwegian marble type, of granulometry such that 65% by weight of the particles have a diameter of less than 1 m, measured using the Sedigraph 5100 of the company Micromeritics, in the form of an aqueous suspension of 78% of dry content, dispersed with 0.77% of a soda polyacrylate, is diluted until an aqueous suspension with a 65% by weight of dry matter is obtained, using distilled water, in the 10-litre ESCO reactor.

(281) The suspension thus formed is then treated, at a temperature equal to 70 C., with 10% of a mixture of phosphoric acid and sulphuric acid in a 10% by weight solution, under stirring during 30 minutes.

(282) Then, the obtained suspension is treated with 2% of fatty acids in suspension, consisting in a coco oil, based on stearic acid, acid having 10 carbon atoms, acid having 12 carbon atoms, acid having 14 carbon atoms, palmitic acid, acid having from to 22 carbon atoms, with a CAS number equal to 67701-05-7.

(283) After the addition of 136 g of calcium hydroxide of 14% by weight, the suspension has a pH equal to 9.7 and a percentage of dry solid content equal to 10.1%.

(284) The suspension thus obtained is dried at 80 C., using a Nara MSD-100 drying machine.

(285) A plastisol-type PVC formulation is then prepared, comprising, in percentage of weight, 25.0% of Vestolit E 7031, 33.0% of diisononyl phthalate, 1.2% of Weisskalk Super 40, 0.8% of Euretek 505 and 40.0% of the mineral pigment according to the invention previously obtained.

(286) The yield point of this composition, measured after 72 hours according to the methods well known by the skilled man in the art, is equal to 502 Pa.