SURFACE-REACTED CALCIUM CARBONATE WITH FUNCTIONAL CATIONS

Abstract

A method of preserving, controlling an odor, and/or enhancing and/or mediating antimicrobial activity of a substrate is described, the method comprising administering a surface-reacted calcium carbonate. The surface-reacted calcium carbonate is obtained by a process comprising treating a calcium carbonate-comprising material with at least one H.sub.3O.sup.+ ion donor, carbon dioxide, and at least one water-soluble metal cation source in an aqueous medium to form an aqueous suspension of surface-reacted calcium carbonate.

Claims

1. A method of preserving, controlling an odor, and/or enhancing and/or mediating antimicrobial activity of a substrate, the method comprising administering a surface-reacted calcium carbonate in an amount sufficient to act as a preservative, to control the odor and/or enhance and/or mediate the antimicrobial activity of the substrate, wherein the surface-reacted calcium carbonate is obtained by a process comprising the steps of: a) providing a calcium carbonate-comprising material, wherein the calcium carbonate-comprising material is a natural ground calcium carbonate, b) providing at least one H.sub.3O.sup.+ ion donor, wherein the at least one H.sub.3O.sup.+ ion donor is phosphoric acid, c) providing at least one water-soluble metal cation source, and d) treating the calcium carbonate-comprising material of step a) with the at least one H.sub.30.sup.+ ion donor of step b) and carbon dioxide in an aqueous medium to form an aqueous suspension of surface-reacted calcium carbonate, wherein in step d) the calcium carbonate-comprising material is treated with a solution comprising the at least one H.sub.3O.sup.+ ion donor of step b) and the at least one water-soluble metal cation source of step c), wherein the at least one water-soluble metal cation source is selected from the group consisting of copper nitrate, copper sulphate, copper acetate, copper chloride, copper bromide, copper iodide, zinc nitrate, zinc sulphate, zinc acetate, zinc chloride, zinc bromide, zinc iodide, hydrates thereof, and mixtures thereof, wherein the carbon dioxide is formed in-situ by the H.sub.3O.sup.+ ion donor treatment of the calcium carbonate-comprising material and/or is supplied from an external source, and wherein the at least one water-soluble metal cation source of step c) is added during step d).

2. (canceled)

3. The method of claim 1, wherein the calcium carbonate-comprising material is in the form of particles having a weight median particle size d.sub.50(wt) from 0.05 μm to 10 μm and/or a weight top cut particle size d.sub.98(wt) from 0.15 μm to 55 μm.

4. (canceled)

5. The method of claim 1, wherein the molar ratio of the at least one H.sub.3O.sup.+ ion donor to the calcium carbonate-comprising material is from 0.01 to 4.

6. (canceled)

7. The method of claim 1, wherein the at least one water-soluble metal cation source is provided in an amount from 0.01 wt.-% to 60 wt.-%, based on the total weight of the calcium carbonate-comprising material.

8. (canceled)

9. The method of claim 1, wherein in step d) the calcium carbonate-comprising material is treated with a first solution comprising a first part of the at least one H.sub.3O.sup.+ ion donor of step b), and subsequently, with a second solution comprising the remaining part of the at least one H.sub.3O.sup.+ ion donor of step b) and the at least one water-soluble metal cation source of step c).

10. The method of claim 1, wherein step d) is carried out at a temperature from 20° C. to 90° C.

11. The method of claim 1, wherein the process further comprises a step e) of separating the surface-reacted calcium carbonate from the aqueous suspension obtained in step d).

12. The method of claim 1, wherein the process further comprises a step f) of drying the surface-reacted calcium carbonate after step d) at a temperature in the range from 60° C.

13. (canceled)

14. (canceled)

15. The method of claim 1, wherein the surface-reacted calcium carbonate has a specific surface area of from 15 m.sup.2/g to 200 m.sup.2/g measured using nitrogen and the BET method.

16. The method of claim 1, wherein the surface-reacted calcium carbonate has a volume determined median particle size d.sub.50(vol) from 1 μm to 75 μm and/or a volume determined top cut particle size d.sub.98(vol) from 2 μm to 150 μm.

17. The method of claim 1, wherein the surface-reacted calcium carbonate has an intra-particle intruded specific pore volume in the range from 0.1 cm.sup.3/g to 2.3 cm.sup.3/g calculated from mercury porosimetry measurement.

18. The method of claim 1, wherein the surface-reacted calcium carbonate has an intra-particle pore size in a range of from 0.004 μm to 1.6 μm determined from mercury porosity measurement.

19. The method of claim 1, wherein the administering a surface-reacted calcium carbonate comprises administering a composition comprising the surface-reacted calcium carbonate and an additional surface-reacted calcium carbonate, wherein the additional surface-reacted calcium carbonate is a reaction product of natural ground calcium carbonate or precipitated calcium carbonate with carbon dioxide and at least one H.sub.3O.sup.+ ion donor, wherein the carbon dioxide is formed in-situ by the H.sub.3O.sup.+ ion donor treatment and/or is supplied from an external source.

20-23. (canceled)

24. The method according to claim 1, wherein the substrate is selected from the group consisting of paper products, engineered wood products, plasterboard products, polymer products, hygiene products, medical products, healthcare products, filter products, woven materials, nonwoven materials, geotextile products, agriculture products, horticulture products, clothing, footwear products, baggage products, household products, industrial products, packaging products, building products, and construction products.

25. The method of claim 2, wherein the natural ground calcium carbonate is selected from the group consisting of marble, chalk, dolomite, limestone, and mixtures thereof.

26. The method of claim 3, wherein the weight median particle size d.sub.50(wt) is from 0.2 μm to 5.0 μm and/or the weight top cut particle size d.sub.98(wt) is from 1 μm to 40 μm.

27. The method of claim 5, wherein the molar ratio is from 0.02 to 2.

28. The method of claim 7, wherein the amount of the at least one water-soluble metal cation source is from 0.05 wt.-% to 50 wt.-%.

29. The method of claim 12, wherein the drying is conducted until the moisture content of the surface-reacted calcium carbonate is from 0.01 wt.-% to 5 wt.-% based on the total weight of the dried surface-reacted calcium carbonate.

30. The method of claim 15, wherein the specific surface area is from 20 m.sup.2/g to 180 m.sup.2/g.

31. The method of claim 16, wherein the volume determined median particle size d.sub.50(vol) is from 2 μm to 50 μm and/or the volume determined top cut particle size d.sub.98(vol) is from 4 μm to 100 μm.

32. The method of claim 17, wherein the intra-particle intruded specific pore volume is from 0.2 cm.sup.2/g to 2.0 cm.sup.3/g.

33. The method of claim 18, wherein the intra-particle pore size is from 0.005 μm to 1.3 μm.

34. The method of claim 1, wherein the method comprises administering the surface-reacted calcium carbonate in an amount sufficient to act as a preservative of the substrate.

35. The method of claim 1, wherein the method comprises administering the surface-reacted calcium carbonate in an amount sufficient to control the odor of the substrate.

36. The method of claim 35, wherein the odor originates from an odorant selected from the group consisting of odorants contained in a human or animal body liquid or secretions, odorants originating from putrefaction, and odorants contained in food.

37. The method of claim 35, wherein the odor originates from an odorant selected from the group consisting of: a) an odorant originating from putrefaction of human or animal tissue; b) an odorant contained in a human or animal body liquid or secretion selected from the group consisting of menses, blood, plasma, sanies, vaginal secretions, mucus, milk, urine, feces, vomit and perspiration; and c) an odorant in a food selected from the group consisting of dairy products, meat, fish and fruit.

38. The method of claim 1, wherein the method comprises administering the surface-reacted calcium carbonate in an amount sufficient to enhance and/or mediate the antimicrobial activity of the substrate.

39. The method of claim 38, wherein the substrate is selected from the group consisting of a sheet of paper, a cardboard, a polymer material, a paint, a wood surface, concrete, and a plant.

40. The method of claim 38, wherein the antimicrobial activity is against a microorganism selected from the group consisting of bacteria, mold, yeast, and algae.

41. The method of claim 40, wherein the antimicrobial activity is against a bacteria.

42. The method of claim 41, wherein the bacteria is selected from the group consisting of Escherichia sp., Staphylococcus sp., Thermus sp., Propionibacterium sp., Rhodococcus sp., Panninobacter sp., Caulobacter sp., Brevundimonas sp., Asticcacaulis sp., Sphingomonas sp., Rhizobium sp., Ensifer sp., Bradyrhizobium sp., Tepidimonas sp., Tepidicella sp., Aquabacterium sp., Pelomonas sp., Alcaligenis sp., Achromobacter sp., Ralstonia sp., Limnobacter sp., Massilia sp., Hydrogenophaga sp., Acidovorax sp., Curvibacter sp., Delftia sp., Rhodoferax sp., Alishewanella sp., Stenotrophomonas sp., Dokdonella sp., Methylosinus sp., Hyphomicrobium sp., Methylosulfomonas sp., Methylobacteria sp., Pseudomonas sp., Enterococcus sp., Myroides sp., Burkholderia sp., Alcaligenes sp. Staphylococcus sp., and mixtures thereof.

43. The method of claim 42, wherein the bacteria is Staphylococcus sp.

Description

EXAMPLES

1. Measurement Methods

[0208] In the following, measurement methods implemented in the examples are described.

Particle Size Distribution

[0209] Volume determined median particle size d.sub.50(vol) and the volume determined top cut particle size d.sub.98(vol) was evaluated using a Malvern Mastersizer 2000 Laser Diffraction System (Malvern Instruments Plc., Great Britain). The d.sub.50 or d.sub.98 value, measured using a Malvern Mastersizer 2000 Laser Diffraction System, indicates a diameter value such that 50% or 98% by volume, respectively, of the particles have a diameter of less than this value. The raw data obtained by the measurement were analysed using the Mie theory, with a particle refractive index of 1.57 and an absorption index of 0.005.

[0210] The weight determined median particle size d.sub.50(wt) was measured by the sedimentation method, which is an analysis of sedimentation behaviour in a gravimetric field. The measurement was made with a Sedigraph™ 5100 or 5120 of Micromeritics Instrument Corporation, USA. The method and the instrument are known to the skilled person and are commonly used to determine particle size distributions of fillers and pigments. The measurement was carried out in an aqueous solution of 0.1 wt.-% Na.sub.4P.sub.2O.sub.7. The samples were dispersed using a high speed stirrer and supersonicatcd.

Specific Surface Area (SSA)

[0211] The specific surface area was measured via the BET method according to ISO 9277:2010 using nitrogen, following conditioning of the sample by heating at 100° C. under vacuum for a period of 30 minutes. Prior to such measurements, the sample was filtered within a Buchner funnel, rinsed with deionised water and dried overnight at 90 to 100° C. in an oven. Subsequently, the dry cake was ground thoroughly in a mortar and the resulting powder was placed in a moisture balance at 130° C. until a constant weight was reached.

Intra-Particle Intruded Specific Pore Volume (in Cm.SUP.3./g)

[0212] The specific pore volume was measured using a mercury intrusion porosimetry measurement using a Micromeritics Autoporc V 9620 mercury porosimeter having a maximum applied pressure of mercury 414 MPa (60 000 psi), equivalent to a Laplace throat diameter of 0.004 μm (˜nm). The equilibration time used at each pressure step was 20 seconds. The sample material was sealed in a 3 cm.sup.3 chamber powder penetrometer for analysis. The data were corrected for mercury compression, penetrometer expansion and sample material compression using the software Pore-Comp (Gane, P. A. C., Kettle, J. P., Matthews, G. P. and Ridgway, C. J., “Void Space Structure of Compressible Polymer Spheres and Consolidated Calcium Carbonate Paper-Coating Formulations”, Industrial and Engineering Chemistry Research, 35(5), 1996, p 1753-1764).

[0213] The total pore volume seen in the cumulative intrusion data can be separated into two regions with the intrusion data from 214 μm down to about 1-4 μm showing the coarse packing of the sample between any agglomerate structures contributing strongly. Below these diameters lies the fine inter-particle packing of the particles themselves. If they also have intra-particle pores, then this region appears bi-modal, and by taking the specific pore volume intruded by mercury into pores finer than the modal turning point, i.e. finer than the bi-modal point of inflection, the specific intra-particle pore volume is defined. The sum of these three regions gives the total overall pore volume of the powder, but depends strongly on the original sample compaction/settling of the powder at the coarse pore end of the distribution.

[0214] By taking the first derivative of the cumulative intrusion curve the pore size distributions based on equivalent Laplace diameter, inevitably including pore-shielding, are revealed. The differential curves clearly show the coarse agglomerate pore structure region, the inter-particle pore region and the intra-particle pore region, if present. Knowing the intra-particle pore diameter range it is possible to subtract the remainder inter-particle and inter-agglomerate pore volume from the total pore volume to deliver the desired pore volume of the internal pores alone in terms of the pore volume per unit mass (specific pore volume). The same principle of subtraction, of course, applies for isolating any of the other pore size regions of interest.

Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES)

[0215] Powder/filter cake were dissolved in HNO.sub.3 (69%, trace select) and boiled for 3 minutes. After cooling, the solubilized samples were diluted with water. The solution was then filtered (0.2 μm) and further diluted prior to analysis.

[0216] Aqueous samples were acidified with HNO.sub.3 (69%, trace select), filtered (0.2 μm) and diluted if needed prior to analysis.

[0217] Analysis was made by ICP-OES on an Optima 3200 XL device (Copper lines Cu 224.7, Cu 324.752, Cu 327.393).

Antimicrobial Surface Activity Test

[0218] Fresh bacteria cultures of the bacteria Staphylococcus aureus DSM 346 strains were prepared by dilution streaking onto a tryptic soy agar plate (TSA, no. 236950, Becton Dickinson and Company, USA) and incubation for 16 to 20 h at 35° C.

[0219] To test the antimicrobial surface activity, the Japanese Standard Protocol JIS Z 2801 2000 was followed using fresh bacteria prepared as described above. The plating, counting and evaluation were done according to the Japanese Standard Protocol JIS Z 2801 2000 with the following amendments. For all coated samples, the bacteria were released after incubation from the test item in a petri dish using a sterile Drigalski spatula to massage the test item with medium, instead of using a stomacher bag and massaging the item by hand. Further for coated samples the test items were not sterilized with 70% ethanol prior analysis.

[0220] As described in the Japanese Standard Protocol JIS Z 2801 2000, the bacterial counts are reported as colony forming units per test item (cfu/test item) with 10 cfu/test item as limit of detection (LOD). Thereof the antimicrobial activity (R) of the test items was calculated as described in the Japanese Standard Protocol JIS Z 2801 2000. For it, after 24 h incubation at 35° C., the average number of viable bacteria on the test item (B) and the untreated control (A) are used to calculate the antimicrobial activity (R) using the following formula: R=log.sub.10(A/B). If zero cfu were detected, a value of 10 cfu/test item was used for calculation of the limit of detection of the antimicrobial activity.

2. Mineral Materials

Surface-Reacted Calcium Carbonate SRCC 1 (Inventive)

[0221] SRCC 1 was obtained by preparing 10 litres of an aqueous suspension of ground calcium carbonate in a mixing vessel by adjusting the solids content of a ground marble calcium carbonate from Hustadmarmor Norway having a mass based particle size distribution of 90% less than 2 μm, as determined by sedimentation, such that a solids content of 10 wt.-%, based on the total weight of the aqueous suspension, is obtained.

[0222] In addition a solution was prepared containing 30% by mass phosphoric acid and 1% by mass of copper sulphate pentahydrate, CuSO.sub.4.5H.sub.2O.

[0223] Whilst mixing the slurry, 1.1 kg of the phosphoric acid/copper sulphate solution was added to said suspension over a period of 10 minutes at a temperature of 70° C. Finally, after the addition of the phosphoric acid, the slurry was stirred for additional 5 minutes, before removing it from the vessel. Then, the slurry was dewatered by use of a filter press (with a maximum pressure of 4 bar) and dried in an oven at a temperature of 120° C. until dry. The obtained surface-reacted calcium carbonate had the following properties: d.sub.50=5.5 μm, d.sub.98=8.6 μm, SSA=55.5 m.sup.2g.sup.−1. The intra-particle intruded specific pore volume is 1.150 cm.sup.3/g (for the pore diameter range of 0.004 to 0.43 μm).

Surface-Reacted Calcium Carbonate SRCC 2 (Inventive)

[0224] SRCC 2 was obtained by preparing 10 litres of an aqueous suspension of ground calcium carbonate in a mixing vessel by adjusting the solids content of a ground marble calcium carbonate from Hustadmarmor Norway having a mass based particle size distribution of 90% less than 2 μm, as determined by sedimentation, such that a solids content of 10 wt.-%, based on the total weight of the aqueous suspension, is obtained.

[0225] In addition, two solutions were prepared. Solution A was prepared such that it contained 30 wt.-%, based on the total weight of the aqueous solution, of phosphoric acid. Solution B was prepared by blending copper sulphate pentahydrate, CuSO.sub.4.5H.sub.2O into a solution of phosphoric acid such that the final solution contained 28.8 wt.-%, based on the total weight of the aqueous solution, of phosphoric acid and 1.0 wt.-%, based on the total weight of the aqueous solution, of copper ion.

[0226] Whilst mixing the slurry, 534 g of solution A was added to the 10 wt.-% calcium carbonate suspension over a period of 5 minutes. Directly after solution A finished adding, 555 g of solution B was added to the suspension over a period of 6 minutes. Throughout the whole experiment the temperature of the suspension was maintained at 70° C. Finally, after the addition of solution B, the suspension was stirred for additional 5 minutes before removing it from the vessel and drying. The obtained surface-reacted calcium carbonate had the following properties: d.sub.50=5.4 μm, d.sub.98=8.0 μm, and SSA=46.4 m.sup.2g.sup.−1. The intra-particle intruded specific pore volume was 0.98 cm.sup.3/g (for the pore diameter range of 0.004 to 0.38 μm).

Surface-Reacted Calcium Carbonate SRCC 3 (Inventive)

[0227] SRCC 3 was obtained by preparing 10 litres of an aqueous suspension of ground calcium carbonate in a mixing vessel by adjusting the solids content of a ground marble calcium carbonate from Hustadmarmor Norway having a mass based particle size distribution of 90% less than 2 μm, as determined by sedimentation, such that a solids content of 10 wt.-%, based on the total weight of the aqueous suspension, is obtained.

[0228] In addition, two solutions were prepared. Solution A was prepared such that it contained 30 wt.-%, based on the total weight of the aqueous solution, of phosphoric acid. Solution B was prepared by blending copper sulphate pentahydrate, CuSO.sub.4.5H.sub.2O into a solution of phosphoric acid such that the final solution contained 27.3 wt.-%, based on the total weight of the aqueous solution, of phosphoric acid and 2.3 wt.-%, based on the total weight of the aqueous solution, of copper ion.

[0229] Whilst mixing the slurry, 534 g of solution A was added to the 10 wt.-% calcium carbonate suspension over a period of 5 minutes. Directly after solution A finished adding, 587 g of solution B was added to the suspension over a period of 6 minutes. Throughout the whole experiment the temperature of the suspension was maintained at 70° C. Finally, after the addition of solution B, the suspension was stirred for additional 5 minutes before removing it from the vessel and drying. The obtained surface-reacted calcium carbonate had the following properties: also d.sub.50=5.2 μm, d.sub.98=8.1 μm, SSA=30.3 m.sup.2g.sup.−1. The intra-particle intruded specific pore volume was 1.00 cm.sup.3/g (for the pore diameter range of 0.004 to 0.30 μm).

Surface-Reacted Calcium Carbonate SRCC 4 (Inventive)

[0230] SRCC 4 was obtained by preparing 10 litres of an aqueous suspension of ground calcium carbonate in a mixing vessel by adjusting the solids content of a ground marble calcium carbonate from Hustadmarmor Norway having a mass based particle size distribution of 90% less than 2 μm, as determined by sedimentation, such that a solids content of 10 wt.-%, based on the total weight of the aqueous suspension, is obtained.

[0231] In addition, two solutions were prepared. Solution A was prepared such that it contained 30 wt.-%, based on the total weight of the aqueous solution, of phosphoric acid. Solution B was prepared by blending copper sulphate pentahydrate, CuSO.sub.4.5H.sub.2O into a solution of phosphoric acid such that the final solution contained 25 wt.-%, based on the total weight of the aqueous solution, of phosphoric acid and 4.2 wt.-%, based on the total weight of the aqueous solution, of copper ion.

[0232] Whilst mixing the slurry, 534 g of solution A was added to the 10 wt.-% calcium carbonate suspension over a period of 6 minutes. Directly after solution A finished adding, 640 g of solution B was added to the suspension over a period of 8 minutes. Throughout the whole experiment the temperature of the suspension was maintained at 70° C. Finally, after the addition of solution B, the suspension was stirred for additional 5 minutes before removing it from the vessel and drying. The obtained surface-reacted calcium carbonate had the following properties: d.sub.50=5.0 μm, d.sub.98=8.8 μm, SSA=34.2 m.sup.2g.sup.−1. The intra-particle intruded specific pore volume was 0.48 cm.sup.3/g (for the pore diameter range of 0.004 to 0.20 μm).

Surface-Reacted Calcium Carbonate SRCC 5 (Inventive)

[0233] SRCC 5 was obtained by preparing 10 litres of an aqueous suspension of ground calcium carbonate in a mixing vessel by adjusting the solids content of a ground marble calcium carbonate from Hustadmarmor Norway having a mass based particle size distribution of 90% less than 2 μm, as determined by sedimentation, such that a solids content of 10 wt.-%, based on the total weight of the aqueous suspension, is obtained.

[0234] In addition, two solutions were prepared. Solution A was prepared such that it contained 30 wt.-%, based on the total weight of the aqueous solution, of phosphoric acid. Solution B was prepared by blending copper sulphate pentahydrate, CuSO.sub.4.5H.sub.2O into a solution of phosphoric acid such that the final solution contained 25 wt.-%, based on the total weight of the aqueous solution, of phosphoric acid and 4.2 wt.-%, based on the total weight of the aqueous solution, of copper ion.

[0235] Whilst mixing the slurry, 534 g of solution A was added to the 10 wt.-% calcium carbonate suspension over a period of 5 minutes. Directly after solution A finished adding, 640 g of solution B was added to the suspension over a period of 15 minutes. Throughout the whole experiment the temperature of the suspension was maintained at 70° C. Finally, after the addition of solution B, the suspension was stirred for additional 5 minutes before removing it from the vessel and drying. The obtained surface-reacted calcium carbonate had the following properties: d.sub.50=5.2 μm, d.sub.98=8.9 μm, SSA=34.8 m.sup.2g.sup.−1. The intra-particle intruded specific pore volume was 0.49 cm.sup.3/g (for the pore diameter range of 0.004 to 0.22 μm).

Surface-Reacted Calcium Carbonate SRCC 6 (Inventive)

[0236] SRCC 6 was obtained by preparing 10 litres of an aqueous suspension of ground calcium carbonate in a mixing vessel by adjusting the solids content of a ground marble calcium carbonate from Hustadmarmor Norway having a mass based particle size distribution of 90% less than 2 μm, as determined by sedimentation, such that a solids content of 10 wt.-%, based on the total weight of the aqueous suspension, is obtained.

[0237] In addition, two solutions were prepared. Solution A was prepared such that it contained 30 wt.-%, based on the total weight of the aqueous solution, of phosphoric acid. Solution B was prepared by blending zinc chloride anhydrous, ZnCl.sub.2, into a solution of phosphoric acid such that the final solution contained 27.3 wt.-%, based on the total weight of the aqueous solution, of phosphoric acid and 4.4 wt.-%, based on the total weight of the aqueous solution, of zinc ion.

[0238] Whilst mixing the slurry, 534 g of solution A was added to the 10 wt.-% calcium carbonate suspension over a period of 5 minutes. Directly after solution A finished adding, 587 g of solution B was added to the suspension over a period of 6 minutes. Throughout the whole experiment the temperature of the suspension was maintained at 70° C. Finally, after the addition of solution B, the suspension was stirred for additional 5 minutes before removing it from the vessel and drying. The obtained surface-reacted calcium carbonate had the following properties: d.sub.50=5.5 μm, d.sub.98=10.0 μm, SSA=43.2 m.sup.2g.sup.−1) The intra-particle intruded specific pore volume is 0.756 cm.sup.3/g (for the pore diameter range of 0.004 to 0.31 μm).

Surface-Reacted Calcium Carbonate SRCC 7 (Inventive)

[0239] SRCC 7 was obtained by preparing 10 litres of an aqueous suspension of ground calcium carbonate in a mixing vessel by adjusting the solids content of a ground marble calcium carbonate from Hustadmarmor Norway having a mass based particle size distribution of 90% less than 2 μm, as determined by sedimentation, such that a solids content of 10 wt.-%, based on the total weight of the aqueous suspension, is obtained.

[0240] In addition, two solutions were prepared. Solution A was prepared such that it contained 30 wt.-%, based on the total weight of the aqueous solution, of phosphoric acid. Solution B was prepared by blending zinc chloride anhydrous, ZnCl.sub.2, into a solution of phosphoric acid such that the final solution contained 25 wt.-%, based on the total weight of the aqueous solution, of phosphoric acid and 8.0 wt.-%, based on the total weight of the aqueous solution, of zinc ion.

[0241] Whilst mixing the slurry, 534 g of solution A was added to the 10 wt.-% calcium carbonate suspension over a period of 5 minutes. Directly after solution A finished adding, 640 g of solution B was added to the suspension over a period of 7 minutes. Throughout the whole experiment the temperature of the suspension was maintained at 70° C. Finally, after the addition of solution B, the suspension was stirred for additional 5 minutes before removing it from the vessel and drying. The obtained surface-reacted calcium carbonate had the following properties: d.sub.50=8.3 μm, d.sub.98=19.3 μm, SSA=30.1 m.sup.2g.sup.−1) The intra-particle intruded specific pore volume is 0.740 cm.sup.3/g (for the pore diameter range of 0.004 to 0.43 μm).

Surface-Reacted Calcium Carbonate SRCC 8 (Inventive)

[0242] SRCC 8 was obtained by preparing 10 litres of an aqueous suspension of ground calcium carbonate in a mixing vessel by adjusting the solids content of a ground limestone calcium carbonate from Orgon, France having a mass based median particle size of 3 μm, as determined by sedimentation, such that a solids content of 10 wt.-%, based on the total weight of the aqueous suspension, is obtained.

[0243] In addition, two solutions were prepared. Solution A was prepared such that it contained 30 wt.-%, based on the total weight of the aqueous solution, of phosphoric acid. Solution B was prepared by blending zinc chloride anhydrous, ZnCl.sub.2, into a solution of phosphoric acid such that the final solution contained 27.3 wt.-%, based on the total weight of the aqueous solution, of phosphoric acid and 4.4 wt.-%, based on the total weight of the aqueous solution, of zinc ion.

[0244] Whilst mixing the slurry, 534 g of solution A was added to the 10 wt.-% calcium carbonate suspension over a period of 5 minutes. Directly after solution A finished adding, 587 g of solution B was added to the suspension over a period of 6 minutes. Throughout the whole experiment the temperature of the suspension was maintained at 70° C. Finally, after the addition of solution B, the suspension was stirred for additional 5 minutes before removing it from the vessel and drying. The obtained surface-reacted calcium carbonate had the following properties: d.sub.50=11.0 μm, d.sub.98=25.3 μm, SSA=27.6 m.sup.2g.sup.−1. The intra-particle intruded specific pore volume is 0.717 cm.sup.3/g (for the pore diameter range of 0.004 to 0.75 μm).

Powder 9 (Inventive)—a Mix of SRCC 3 and SRCC 11

[0245] 400 g of a 22 wt.-% solid content filter cake from sample SRCC 3 were dispersed in 1 litres deionized water, agitated with a mechanical stirrer for approx. 20 minutes (300-350 rpm) and then filtered on a Buchner funnel. This procedure was repeated a second time, and, after the second washing step, the filter cake was dried in an oven (110° C.) and deagglomerated.

[0246] 20 g of the above powder were then mixed with 180 g of SRCC 11.

Powder 10 (Inventive)—a Mix of SRCC 5 and SRCC 11

[0247] 400 g of a 24.5 wt.-% solid content filter cake from sample SRCC 5 were dispersed in 1 L deionized water, agitated with a mechanical stirrer for Ca. 20 minutes (300-350 rpm) and then filtered on a Büchner funnel. This procedure was repeated a second time, and, after the second washing step, the filter cake was dried in an oven (110° C.) and deagglomerated.

[0248] 20 g of the above powder were then mixed with 180 g of SRCC 11.

Surface-Reacted Calcium Carbonate SRCC 11 (Comparative)

[0249] SRCC 11 is a surface-reacted calcium carbonate (d.sub.50=2.6 μm, BET=34.7 m.sup.2/g, and an intra-particle intruded specific pore volume of 0.305 cm.sup.3/g (for the pore diameter range of 0.004 to 0.19 μm), without further treatment.

Surface-Reacted Calcium Carbonate SRCC 12 (Inventive)

[0250] SRCC 12 was obtained by preparing 0.5 a litre of an aqueous suspension of ground calcium carbonate in a mixing vessel by adjusting the solids content of a ground marble calcium carbonate from Hustadmarmor Norway having a mass based particle size distribution of 90% less than 2 μm, as determined by sedimentation, such that a solids content of 10 wt.-%, based on the total weight of the aqueous suspension, is obtained.

[0251] In addition, a solution was prepared containing 29.1% by mass phosphoric acid and 3.1% by mass of chloroplatinic acid hexahydrate, H.sub.2PtCl.sub.6.6H.sub.2O.

[0252] Whilst mixing the slurry, 91.8 g of the phosphoric acid/chloroplatinic acid hexahydrate solution was added to said suspension over a period of 10 minutes at a temperature of 70° C. Finally, after the addition of the phosphoric acid, the slurry was stirred for additional 5 minutes, before removing it from the vessel. Then, the slurry was dried by use of a rotary evaporator. The obtained surface-reacted calcium carbonate had the following properties: d.sub.50=8.8 μm, d.sub.98=19.9 μm, SSA=53.9 m.sup.2g.sup.−1. The intra-particle intruded specific pore volume is 1.415 cm.sup.3/g (for the pore diameter range of 0.004 to 0.67 μm).

Surface-Reacted Calcium Carbonate SRCC 13 (Inventive)

[0253] SRCC 13 was obtained by preparing 0.5 a litre of an aqueous suspension of ground calcium carbonate in a mixing vessel by adjusting the solids content of a ground marble calcium carbonate from Hustadmarmor Norway having a mass based particle size distribution of 90% less than 2 μm, as determined by sedimentation, such that a solids content of 10 wt.-%, based on the total weight of the aqueous suspension, is obtained.

[0254] In addition, two solutions were prepared. Solution A was prepared such that it contained 30 wt.-%, based on the total weight of the aqueous solution, of phosphoric acid. Solution B was prepared by blending chloroplatinic acid hexahydrate, H.sub.2PtCl.sub.6.6H.sub.2O into a solution of phosphoric acid such that the final solution contained 28.2 wt.-%, based on the total weight of the aqueous solution, of phosphoric acid and 2.3 wt.-%, based on the total weight of the aqueous solution, of platinum ion.

[0255] Whilst mixing the slurry, 44.5 g of solution A was added to the 10 wt.-% calcium carbonate suspension over a period of 5 minutes. Directly after solution A finished adding, 47.3 g of solution B was added to the suspension over a period of 5 minutes. Throughout the whole experiment the temperature of the suspension was maintained at 70° C. Finally, after the addition of solution B, the suspension was stirred for additional 5 minutes before removing it from the vessel and drying. The obtained surface-reacted calcium carbonate had the following properties: also d.sub.50=8.5 μm, d.sub.98=18.1 μm, and SSA=57.8 m.sup.2g.sup.−1. The intra-particle intruded specific pore volume was 1.417 cm.sup.3/g (for the pore diameter range of 0.004 to 0.67 μm).

3. Analysis

[0256]

TABLE-US-00001 TABLE 1 Quantitative Rietveld analyses (XRD) SRCC 11 SRCC 3 SRCC 4 SRCC 5 Mineral Formula (comparative) (inventive) (inventive) (inventive) Calcite CaCO.sub.3 73.7 51.2 58.5 58.8 Hydroxylapatite Ca.sub.5(OH)(PO.sub.4).sub.3 26.3 46.1 25.4 25.6 Monetite CaHPO.sub.4 — 2.7 15.8 15.4 Brochantite Cu.sub.4SO.sub.4(OH).sub.6 — — 0.3 0.2 Total 100 100 100 100 Data were normalized to 100% crystalline material.

ICP-OES

[0257]

TABLE-US-00002 TABLE 2 Composition of powder samples after filtration. SRCC 3 SRCC 5 Cu (ICP-OES, %) 0.56 2.16

TABLE-US-00003 TABLE 3 Composition of filtered washing water from Powder 5. 1 L washing Calcium 336 ± 5 ppm; ROR.sup.a): 95.0% Copper <0.1 ppm .sup.a)ROR means rate of recovery of the measurement.

[0258] The XRD measurements show that a new crystalline calcium phase (monetite) has been formed in the inventive surface-reacted calcium carbonate. Furthermore, the inventive samples SRCC4 and SRCC5 show the presence of a copper mineral phase, namely, brochantite. The XRD measurements of SRCC3 did not reveal a significant copper phase. However, it could be confirmed by ICP-OES that SRCC3 contains copper.

[0259] For the analysis according to Table 3, 400 g of SRCC 5 filter cake (corresponding to 98 g solid) are dispersed with 1 litre deionised water and agitated (mechanical agitation, ca 300 rpm) for 30 minutes. The suspension is filtered, and the filtered solution is analysed to determine the amount of copper in 1 litre water. It can be gathered from Table 3 that only a very low amount of copper was leached into the water.

4. Slurries of Surface-Reacted Calcium Carbonate Fillers and Paper Coatings

Examples 1 to 5 (E1 to E5) and Comparative Example 1 (CE1)

[0260] Slurries were prepared on a Pendraulik stirrer, by stirring mixtures of the compositions indicated in Table 4 below for 10 minutes at room temperature with 930 rpm.

TABLE-US-00004 TABLE 4 Composition of produced filler slurries. SRCC Water DA Solid Brookfield [parts by [parts by [parts by content viscosity Conductivity Example SRCC weight] weight] weight] [wt.-%] [mPas] pH [mS/cm] CE1 SRCC 11 100 100 0.7 46.7 348 9.2 1.7 E1 SRCC 1 100.sup.a 465 0.7 17.7 992 7.5 1.2 E2 SRCC 3 100.sup.b 405 0.7 19.5 1188 6.9 1.8 E3 SRCC 5 100.sup.c 435 0.7 18.7 1098 6.6 2.0 E4 Powder 9-mix of 100 125 0.7 41.4 108.4 8.9 1.8 SRCC 3 and SRCC 11 washed (90:10 mixture) E5 Powder 10-mix 100 125 0.7 41.6 138 8.7 1.9 of SRCC 5 and SRCC 11 washed (90:10 mixture) .sup.aa 20.3 wt.-% filter cake from SRCC 1 was used. .sup.ba 24.5 wt.-% filter cake from SRCC 3 was used. .sup.ca 24.5 wt.-% filter cake from SRCC 5 was used. DA = dispersing agent (100% sodium-neutralised polyacrylate, M.sub.w = 3 500 g/mol, pH = 8).

[0261] Coating colours containing 100 parts of the respective SRCC (w/w) and 6 parts (dry/dry) of Styronal D628 (BASF, Germany) were then prepared with slurries according to Examples 1 to 5 and Comparative Examples 1 and coated on superYUPO® foils from Fischer Papier AG, Switzerland (thickness 80 μm, size: 18×26 cm.sup.2, 62 g/m.sup.2, polypropylene). The composition of the coating colours and coating weights are summarized in Table 5 below.

TABLE-US-00005 TABLE 5 Coating colour preparation and coating weight. Coating colour composition Styronal SRCC D628 Solid Coating [parts by [parts, content weight Example Slurry weight] dry/dry] [wt.-%] [g/m.sup.2] CE2 CE1 (SRCC 11) 100 6 40 12.4  E6  E1 (SRCC 1) 100 6 18 4.4 E7  E2 (SRCC 3) 100 6 18 4.6 E8  E3 (SRCC 5) 100 6 18 8.1 E9  E4 (Powder 100 6 40 14.5  9-mix of SRCC 3 and SRCC 11 washed (90:10 mixture)) E10 E5 (Powder 100 6 40 13   10-mix of SRCC 5 and SRCC 11 washed (90:10 mixture))

Example 11—Antimicrobial Surface Activity of Paper Coatings

[0262] The antimicrobial activity of selected paper samples comprising a coating layer containing the surface-reacted calcium carbonate of the present invention as filler, which were prepared according to Examples 6 to 10 (E6 to E10) and Comparative Example 2 (CE2) was tested as described in the measurement method section “Antimicrobial surface activity test” above.

[0263] Tables 6 shows the cfu counts per test item and the calculated antimicrobial activity against S. aureus of the coated paper samples E6 to E10 as well as of comparative sample CE2. The term LOD in Table 6 refers to the limit of detection.

TABLE-US-00006 TABLE 6 Antimicrobial activity against S. aureus of surface coated paper samples. Antimicrobial cfu/test item activity Test item I II III Average R LOD untreated paper from 2.9 E+05 2.6 E+05 2.5 E+05 2.7 E+05 N/A N/A CE2 (SRCC 11) (before incubation) untreated paper from 3.5 E+03 1.6 E+04 1.6 E+04 1.2 E+04 0.00 3.07 CE2 (SRCC 11) Paper from E6 (SRCC 1) 1.0 E+01 1.0 E+01 1.0 E+01 1.0 E+01 3.07 3.07 Paper from E7 (SRCC 3) 1.0 E+01 1.0 E+01 1.0 E+01 1.0 E+01 3.07 3.07 Paper from E8 (SRCC 5) 1.0 E+01 1.0 E+01 1.0 E+01 1.0 E+01 3.07 3.07 Paper from E9 (Powder 1.0 E+01 1.0 E+01 1.0 E+01 1.0 E+01 3.07 3.07 9-mix of SRCC 3 and SRCC 11 washed (90:10 mixture)) Paper from E10 (Powder 1.0 E+01 1.0 E+01 1.0 E+01 1.0 E+01 3.07 3.07 10-mix of SRCC 5 and SRCC 11 washed (90:10 mixture)) N/A: Not applicable

[0264] As can be gathered from the results compiled in Table 6 above, all paper samples with a coating layer comprising the inventive surface-reacted calcium carbonate show good antimicrobial activity.