PRECIPITATED CALCIUM CARBONATE, A METHOD FOR ITS MANUFACTURE AND USES THEREOF

Abstract

The present invention relates to precipitated calcium carbonate particles being at least partially in the form of nanofibers or nanochain like agglomerates, wherein the particles are at least partially coated with at least one coating agent, use of such precipitated calcium carbonate particles and a process for the manufacture of such precipitated calcium carbonate particles.

Claims

1. A composition comprising precipitated calcium carbonate particles, wherein the particles are at least partially in the form of nanofibers or nanochain like agglomerates, and the particles are at least partially coated with at least one coating agent.

2. A composition according to claim 1, wherein the nanofibers or nanochain like agglomerates have an average specific surface area of equal to or lower than 60 m.sup.2/g before coating (measured by the BET technique described in ISO 9277).

3. A composition according to claim 1, wherein the nanofibers or nanochain like agglomerates are further aggregated to form microshells or microsheaves.

4. A composition according to claim 1, wherein the at least one coating agent is selected from the group consisting of sulfur organic compounds, fatty acids and the salts thereof, preferably wherein the at least one coating agent is a fatty acid or salt thereof or an organic sulfonic acid, its ester and/or salt.

5. A composition according to claim 1, wherein the at least one coating agent comprises at least one fatty acid with a hydroxy group or salt thereof.

6. A composition according to claim 5, wherein the fatty acid with a hydroxy group or salt thereof comprises a linear or branched aliphatic carboxylic acid having 8 to 22 carbon atoms with a hydroxy group or salt thereof.

7. A composition according to claim 5, wherein the fatty acid with a hydroxy group or salt thereof has a saturated aliphatic chain.

8. A composition according to claim 5, wherein the fatty acid with a hydroxy group or salt thereof is hydroxy stearic acid or salt thereof.

9. A composition according to claim 4, wherein the organic sulfonic acid is selected from alkylsulfonic acids, arylsulfonic acids, alkylarylsulfonic acids, and the esters and salts thereof.

10. A composition according to claim 9, wherein the coating agent comprises a compound represented by general formula (I-A) or (I-B) ##STR00002## wherein R.sup.1, R.sup.7, R.sup.9 and R.sup.10 are independently a single bond, O, C.sub.1-C.sub.18-alkylene- or C.sub.2-C.sub.18-alkenylene- (wherein in the alkylene- or in the alkenylene-chain optionally 1, 2 or 3 CH.sub.2 groups may be replaced by O); R.sup.2, R.sup.3, R.sup.4, R.sup.5 and R.sup.6 are independently H, C.sub.1-C.sub.18-alkyl (wherein in the alkyl-chain optionally 1, 2 or 3 CH.sub.2 groups may be replaced by O), OH, F, Cl, CN, CO.sub.2H, COC.sub.1-C.sub.6-alkyl, CO.sub.2C.sub.1-C.sub.6-alkyl, OCOC.sub.1-C.sub.6-alkyl, NO.sub.2, NH.sub.2, NHC.sub.1-C.sub.6-alkyl or N(C.sub.1-C.sub.6-alkyl).sub.2; R.sup.8 is H or C.sub.1-C.sub.6-alkyl; and R.sup.11 and R.sup.12 are independently H, C.sub.1-C.sub.18-alkyl (wherein in the alkyl-chain optionally 1, 2 or 3 CH.sub.2 groups may be replaced by O), NH.sub.2, NHC.sub.1-C.sub.6-alkyl or N(C.sub.1-C.sub.6-alkyl).sub.2.

11. A composition according to claim 9, wherein the at least one coating agent is a salt of alkylbenzenesulfonic acid.

12. A composition according to claim 9, wherein the at least one coating agent is a sodium salt of alkylbenzenesulfonic acid.

13. A composition according to claim 1, wherein the at least one coating agent comprises from 0.01 wt % to 15 wt % of the composition.

14. A composition according to claim 1, wherein the precipitated calcium carbonate further comprises at least one crystallization controller, wherein the crystallization controller preferably is selected from the group consisting of polyacrylic acid, salts thereof and mixtures thereof, citric acid, sodium dioctylsulfosuccinate, polyaspartic acid and Ethylenediaminetetraacetic acid (EDTA).

15. A composition according to claim 1 wherein a standard polymer composition comprising the precipitated calcium carbonate displays a yield stress value of from 250 to 600 Pa.

16. A composition according to claim 1, wherein the precipitated calcium carbonate before coating has an average primary particle size (dp) of from 15 to 100 nm, and an aggregate median size of from 0.11 m to 10 m.

17. A composition according to claim 1, wherein the precipitated calcium carbonate has a loss on drying value of equal to or lower than 15 g/kg at 105 C.

18-23. (canceled)

24. A paint sealant, paper, food product, nutritional product, pharmaceutical product, ink, lacquer, polymer, or polymer composition comprising a composition according to claim 1.

25. A plastisol comprising a composition according to claim 1.

26-35. (canceled)

36. A composition comprising precipitated calcium carbonate particles, wherein the particles are at least partially in the form of nanofibers or nanochain like agglomerates, and the particles are at least partially coated with at least one coating agent so as to be dispersible in a composition selected from, the group consisting of plastisol, paint, sealant, paper, food product, nutritional product, pharmaceutical product, ink, lacquer, polymer and polymer compositions.

Description

EXAMPLE 1: PREPARATION OF PRECIPITATED CALCIUM CARBONATE (PCC)

[0088] A milk of lime with a concentration of 15% wt. Ca(OH).sub.2 and an initial temperature of 17.5 C. was enriched with 0.25 wt % polyacrylic acid (about 2500 g/mol). Carbonation of the milk of lime occurred under a 28% CO.sub.2 flow (diluted with air) at a flow rate of 15 m.sup.3/h. The final carbonation temperature was 37.8 C. A sample of the slurry was filtered, dried in an oven and analyzed with SEM. The sample was found to be constituted of nanochain like agglomerates, combined to form microshell like aggregates. Average diameter and average length were respectively 70 nm and 284 nm. These values are based on the measurement of 10 nanofibers.

EXAMPLE 2: COATING OF PRECIPITATED CALCIUM CARBONATE (PCC) WITH HYDROXYSTEARIN

[0089] The slurry obtained in experiment 1 is brought to a temperature of 70 C., and a hydroxystearin emulsion in water is added in an amount corresponding to 30 g/kg of hydroxystearin. The mixture is filtered on a planar filter and is dried in an oven for 36 h at 95 C., before milling in an Alpine 160 Z at 14 800 rpm.

[0090] Loss on drying for this product at 105 C. is 3.4 g/kg; the specific surface area is found to be 22 m.sup.2/g.

[0091] FIG. 1 shows a SEM micrography of the obtained PCC2.

EXAMPLE 3: COATING OF PRECIPITATED CALCIUM CARBONATE (PCC) WITH SODIUM ALKYLBENZENESULFONATE

[0092] The slurry obtained in experiment 1 is brought to a temperature of 50 C., and a sodium alkylbenzenesulfonate emulsion in water is added in an amount corresponding to 10 g/kg of sodium alkylbenzenesulfonate. The mixture is filtered on a planar filter and is dried in an oven for 36 h at 95 C., before milling in an Alpine 160 Z at 14 800 rpm.

[0093] Loss on drying at 105 C. is 7.9 g/kg for this product and specific surface area of 27 m.sup.2/g is found.

[0094] FIG. 2 shows a SEM micrography of the obtained PCC3.

EXAMPLE 4: APPLICATION OF PRECIPITATED CALCIUM CARBONATE IN PLASTISOL FORMULATION

[0095] The surface treated calcium carbonate particles obtained by experiment 2 (PCC2) and 3 (PCC 3) were measured according to the Yield Stress Value test described above.

[0096] The comparative example is Socal 312, which is an ultrafine PCC coated with 28 g/kg stearin. It displays an LOD value of 4.5 g/kg and a specific surface area of 22 m.sup.2/g. Socal 312 has a calcite rhombohedral crystal structure, and a cubic particle shape. The particles are not agglomerated in nanochains or nanofibres. FIG. 3 shows a SEM micrography of Socal 312.

TABLE-US-00003 PCC Yield Stress Value Comparative Example Socal 312 218 PCC 2 285 PCC 3 300