SURFACE-REACTED CALCIUM CARBONATE FUNCTIONALIZED WITH IRON OXIDE SPECIES FOR COSMETIC, PAINT AND COATING APPLICATIONS

Abstract

A method of manufacturing a pigment comprising the steps of a) providing at least one surface-reacted calcium carbonate, b) providing at least one water-soluble iron compound, c) providing at least one treatment agent, d) combining the at least one surface-reacted calcium carbonate of step a) with the at least one water-soluble iron compound of step b) in an aqueous medium, e) adding the at least one treatment agent to the mixture of step d), f) dewatering the mixture of step e), g) thermally treating the mixture of step f) at a temperature of from 80 to 150 C., wherein the surface-reacted calcium carbonate is a reaction product of ground natural calcium carbonate-containing mineral or precipitated calcium carbonate with carbon dioxide and one or more H.sub.3O.sup.+ ion donors; a pigment obtained by said method and products thereof.

Claims

1. A method for the manufacture of a pigment comprising the steps of a) providing at least one surface-reacted calcium carbonate, b) providing at least one water-soluble iron compound, c) providing at least one treatment agent, d) combining the at least one surface-reacted calcium carbonate of step a) with the at least one water-soluble iron compound of step b) in an aqueous medium, e) adding the at least one treatment agent to the mixture of step d), f) dewatering the mixture of step e), g) thermally treating the mixture of step f) at a temperature of from 80 to 150 C., wherein the surface-reacted calcium carbonate is a reaction product of ground natural calcium carbonate-containing mineral (GNCC) or precipitated calcium carbonate (PCC) with carbon dioxide and one or more H.sub.3O.sup.+ ion donors and wherein the carbon dioxide is formed in situ by the H.sub.3O.sup.+ ion donors treatment and/or is supplied from an external source.

2. The method according to claim 1, wherein the at least one surface-reacted calcium carbonate of step a) has a) a volume median particle size d.sub.50 (vol) in the range from of from 1 to 75 m, and/or b) a top cut particle size d.sub.98 (vol) of from 2 to 150 m, and/or c) a specific surface area (BET) of from 10 m.sup.2/g to 200 m.sup.2/g, and/or d) an intra-particle intruded specific pore volume in the range from 0.1 to 2.3 cm.sup.3/g, calculated from mercury porosimetry measurement.

3. The method according to claim 1, wherein the at least one water-soluble iron compound of step b) is selected from the group comprising iron(II) sulfate; iron(III) sulfate; iron(II) halides, such as iron(II) chloride or iron(II) bromide; iron(III) halides, such as iron(III) chloride or iron(III) bromide; iron(II) nitrate; iron(III) nitrate; iron(II) phosphate; iron(III) phosphate; iron(II) oxalate; iron(III) oxalate; iron(II) acetate; iron(III) acetate; hydrates, and mixtures thereof.

4. The method according to claim 1, wherein the at least one water-soluble iron compound of step b) is added in an amount of from 0.05 to 40 wt %, relating to the iron content in relation to the total dry weight of the surface-reacted calcium carbonate.

5. The method according to claim 1, wherein the at least one treatment agent of step c) is selected from precipitation agents forming a water-insoluble iron compound when combined with the water-soluble iron compound.

6. The method according to claim 1, wherein the at least one treatment agent of step c) is selected from reducing agents forming elemental iron when combined with the water-soluble iron compound.

7. The method according to claim 1, characterized in that wherein the at least one water-soluble iron compound of step b) is added in an amount such that the amount of water-insoluble iron compound and/or the amount of elemental iron resulting from the reaction of the at least one water-soluble iron compound of step b) and the at least one treatment agent of step c) is from 0.05 to 40 wt % based on the total dry weight of the surface-reacted calcium carbonate.

8. The method according to claim 1 wherein in relation to the iron content of the water-soluble iron compound of step b), the at least one treatment agent of step c) is provided in a molar ratio of treatment agent:Fe of from 1:1 to 15:1.

9. The method according to claim 1 wherein steps d) and/or e), independently from each other, are carried out under stirring and/or at a temperature of from 25 to 95 C.

10. The method according to claim 1 wherein dewatering step f) is carried out by filtration, centrifugation, spray drying, evaporation, optionally under vacuum.

11. The method according to claim 1 wherein thermal treatment step g) is carried out at a temperature of from 90 to 140 C.

12. The method according to claim 1 wherein, after thermal treatment step g), a further thermal treatment step h) is carried out at a temperature of from more than 150 to 600 C.

13. A pigment obtained by the method according to claim 1.

14. A method of using a pigment obtained by the method of claim 1 further comprising the step of adding the pigment into a cosmetic application or paint and coating applications.

15. A product comprising a pigment obtained by the method of claim 1, wherein the product is selected from the group comprising cosmetic products, paints and coatings.

16. A method for the manufacture of a cosmetic product, paint or coating comprising the steps of a) providing at least one surface-reacted calcium carbonate, b) providing at least one water-soluble iron compound, c) providing at least one treatment agent, d) combining the at least one surface-reacted calcium carbonate of step a) with the at least one water-soluble iron compound of step b) in an aqueous medium, e) adding the at least one treatment agent to the mixture of step d), f) dewatering the mixture of step e), g) thermally treating the mixture of step f) at a temperature of from 80 to 150 C. to obtain a pigment, i) adding the pigment obtained in step g) to a cosmetic formulation, paint or coating, wherein the surface-reacted calcium carbonate is a reaction product of ground natural calcium carbonate-containing mineral (GNCC) or precipitated calcium carbonate (PCC) with carbon dioxide and one or more H.sub.3O.sup.+ ion donors and wherein the carbon dioxide is formed in situ by the H.sub.3O.sup.+ ion donors treatment and/or is supplied from an external source.

17. A product comprising a pigment obtained by the method of claim 16, wherein the product is selected from the group comprising cosmetic products, paints and coatings.

Description

FIGURES

[0143] FIG. 1 illustrates colours and colour shades obtainable by inventive pigments manufactured using NaOH as the treatment agent

[0144] FIG. 2 illustrates colours and colour shades obtainable by inventive pigments manufactured using NaBH 4 as the treatment agent

[0145] FIG. 3 illustrates the reflectance properties of inventive samples having a molar ratio of NaOH:Fe of 1:1 and being heat treated at a temperature of 125 C., and a comparative untreated sample.

[0146] FIG. 4 illustrates the absorption properties (calculated) of samples having a molar ratio of NaOH:Fe of 1:1 and being heat treated at a temperature of 125 C., and a comparative untreated sample.

[0147] FIG. 5 illustrates the reflectance properties of samples having a molar ratio of NaOH:Fe of 1:1 and being calcined at a temperature of 500 C., and a comparative untreated sample.

[0148] FIG. 6 illustrates the absorption properties (calculated) of samples having a molar ratio of NaOH:Fe of 1:1 and being calcined at a temperature of 500 C., and a comparative untreated sample.

[0149] FIG. 7 illustrates the reflectance properties of samples having a molar ratio of NaOH:Fe of 5:1 and being heat treated at a temperature of 125 C., and a comparative untreated sample.

[0150] FIG. 8 illustrates the absorption properties (calculated) of samples having a molar ratio of NaOH:Fe of 5:1 and being heat treated at a temperature of 125 C., and a comparative untreated sample.

[0151] FIG. 9 illustrates the reflectance properties of samples having a molar ratio of NaOH:Fe of 5:1 and being calcined at a temperature of 500 C., and a comparative untreated sample.

[0152] FIG. 10 illustrates the absorption properties (calculated) of samples having a molar ratio of NaOH:Fe of 5:1 and being calcined at a temperature of 500 C., and a comparative untreated sample.

[0153] FIG. 11 illustrates the reflectance properties of samples having a molar ratio of NaBH.sub.4:Fe of 1:1 and being heat treated at a temperature of 125 C., and a comparative untreated sample.

[0154] FIG. 12 illustrates the absorption properties (calculated) of samples having a molar ratio of NaBH.sub.4:Fe of 1:1 and being heat treated at a temperature of 125 C., and a comparative untreated sample.

[0155] FIG. 13 illustrates the reflectance properties of samples having a molar ratio of NaBH.sub.4:Fe of 1:1 and being calcined at a temperature of 500 C., and a comparative untreated sample.

[0156] FIG. 14 illustrates the absorption properties (calculated) of samples having a molar ratio of NaBH.sub.4:Fe of 1:1 and being calcined at a temperature of 500 C., and a comparative untreated sample.

[0157] FIG. 15 illustrates the reflectance properties of samples having a molar ratio of NaBH.sub.4:Fe of 5:1 and being heat treated at a temperature of 125 C., and a comparative untreated sample.

[0158] FIG. 16 illustrates the absorption properties (calculated) of samples having a molar ratio of NaBH.sub.4:Fe of 5:1 and being heat treated at a temperature of 125 C., and a comparative untreated sample.

[0159] FIG. 17 illustrates the reflectance properties of samples having a molar ratio of NaBH.sub.4:Fe of 5:1 and being calcined at a temperature of 500 C., and a comparative untreated sample.

[0160] FIG. 18 illustrates the absorption properties (calculated) of samples having a molar ratio of NaBH.sub.4:Fe of 5:1 and being calcined at a temperature of 500 C., and a comparative untreated sample.

[0161] FIG. 19 illustrates the results of a comparison of mixtures of surface-reacted calcium carbonate with commercial pigments and inventive pigments.

[0162] FIGS. 20 to 24 illustrate W/O and 01W creams containing the pigments of the invention in different colour ranges.

[0163] FIG. 25 illustrates the coverage of two formulations comprising pigments according to the invention at a concentration of 5 wt % and 10 wt %.

EXAMPLES

[0164] 1. Analytical Methods

[0165] Particle Size Distribution

[0166] Volume determined median particle size d.sub.50 (vol) and the volume determined top cut particle size d.sub.98(vol) as well as the volume particle sizes d.sub.90 (vol) and d.sub.10 (vol) may be evaluated in a wet unit using a Malvern Mastersizer 2000 or 3000 Laser Diffraction System (Malvern Instruments Plc., Great Britain). If not otherwise indicated in the following example section, the volume particle sizes were evaluated in a wet unit using a Malvern Mastersizer 2000 Laser Diffraction System (Malvern Instruments Plc., Great Britain). The d.sub.50 (vol) or d.sub.98(vol) value 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 was analyzed using the Mie theory, with a particle refractive index of 1.57 and an absorption index of 0.005. The methods and instruments are known to the skilled person and are commonly used to determine particle size distributions of fillers and pigments. The sample was measured in dry condition without any prior treatment.

[0167] 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 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 supersonicated.

[0168] The processes and instruments are known to the skilled person and are commonly used to determine particle sizes of fillers and pigments.

[0169] BET Specific Surface Area of a Material

[0170] The specific surface area (expressed in m.sup.2/g) of a material as used throughout the present document is determined by the Brunauer Emmett Teller (BET) method with nitrogen as adsorbing gas and by use of a ASAP 2460 instrument from Micromeritics. The method is well known to the skilled person and defined in ISO 9277:2010. Samples are conditioned at 100 C. under vacuum for a period of 60 min prior to measurement. The total surface area (in m.sup.2) of said material can be obtained by multiplication of the specific surface area (in m.sup.2/g) and the mass (in g) of the material.

[0171] Pore Volume/Porosity

[0172] For the purpose of the present invention the porosity or pore volume refers to the intra-particle intruded specific pore volume.

[0173] In the context of the present invention, the term pore is to be understood as describing the space that is found between and/or within particles, i.e. that is formed by the particles as they pack together under nearest neighbour contact (interparticle pores), such as in a powder or a compact, and/or the void space within porous particles (intraparticle pores), and that allows the passage of liquids under pressure when saturated by the liquid and/or supports absorption of surface wetting liquids.

[0174] The specific pore volume is measured using a mercury intrusion porosimetry measurement using a Micromeritics Autopore 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 m. The equilibration time used at each pressure step is 20 s. The sample material is sealed in a 5 cm.sup.3 chamber powder penetrometer for analysis. The data are corrected for mercury compression, penetrometer expansion and sample material elastic 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, 1996, 35(5), 1753-1764).

[0175] The total pore volume seen in the cumulative intrusion data is separated into two regions with the intrusion data from 214 m down to about 1 to 4 m showing the coarse packing of the sample between any agglomerate structures contributing strongly. Below these diameters lies the fine interparticle packing of the particles themselves. If they also have intraparticle pores, then this region appears bimodal, and by taking the specific pore volume intruded by mercury into pores finer than the modal turning point, i.e. finer than the bimodal point of inflection, the specific intraparticle 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.

[0176] 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 interparticle pore region and the intraparticle pore region, if present. Knowing the intraparticle pore diameter range it is possible to subtract the remainder interparticle and interagglomerate 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.

[0177] X-Ray Diffraction (XRD)

[0178] XRD experiments are performed on the samples using rotatable PMMA holder rings. Samples are analyzed with a Bruker D8 Advance powder diffractometer obeying Bragg's law. This diffractometer comprises a 2.2 kW X-ray tube, a sample holder, a --goniometer, and a VNTEC-1 detector. Nickel-filtered Cu-K radiation is employed in all experiments. The profiles are chart recorded automatically using a scan speed of 0.7 per min in 2 (XRD GV_7600). The resulting powder diffraction patterns are classified by mineral content using the DIFFRACsuite software packages EVA and SEARCH, based on reference patterns of the ICDD PDF-2 database (XRD LTM_7603).

[0179] Quantitative analysis of diffraction data refers to the determination of amounts of different phases in a multi-phase sample and has been performed using the DIFFRACsuite software package TOPAS. In detail, quantitative analysis allows to determine structural characteristics and phase proportions with quantifiable numerical precision from the experimental data itself. This involves modelling the full diffraction pattern using the Rietveld approach such that the calculated pattern(s) duplicates the experimental one.

[0180] Reflectance and Absorption Analysis

[0181] Reflectance analysis is carried out with a double beam PerkinElmer Lambda 950 UV/Vis/NIR spectrophotometer equipped with a 150 mm integrating sphere with PMT and InGaAs detectors. The samples are measured by diffuse reflectance spectroscopy. The analysis is performed with the samples loaded into a sealed aluminum cup for powder samples which is placed flush with the reflectance port of the integrating sphere. Measurements are performed in a specular-excluded configuration, that is, the specular component of the reflected light is lost from the measurement by opening the corresponding section of the integrating sphere.

[0182] The spectrophotometer is scanned in the range 250 nm-2500 nm in steps of 5 nm. A Spectralon white standard is used as 100% baseline. CIE colour coordinates L*, a*, b* are calculated with the OptLab-SPX software using the measured reflectance spectra in the range 380-780 nm, and considering a D65 standardized illuminant with an observer angle of 10 degrees. Given a reference colour (L.sub.1,a.sub.1,b.sub.1) and another colour (L.sub.2,a.sub.2,b.sub.2), their colour difference is evaluated as E.sub.1,2={square root over ((L.sub.2L.sub.1).sup.2+(a.sub.2a.sub.1).sub.2+(b.sub.2b.sub.1).sup.2)}.

[0183] To get a proxy for the absorption spectrum of the samples, the measured reflectance spectrum is converted using the Kubelka-Munk equation KM=K/S=(1R).sup.2/2R, where R is the reflectance as measured above and K and S are the absorption and scattering coefficient, respectively.

[0184] Covering

[0185] The covering power, i.e. the power of the covering agent to cover and/or to opacify the skin surface, can be measured by spreading a cosmetic and/or skin care compositions comprising the covering agent on a contrast paper and subsequently measuring the colour values Rx, Ry, Rz of the composition by the means of a colorimeter. By comparison of the colour values of the cosmetic composition and that of the contrast paper, the contrast is calculated. The contrast directly refers to the covering power. Contrast ratio values are determined according to ISO 2814 at a spreading rate of approx. 20 m.sup.2/l. The contrast ratio is calculated as described by the equation below:

[00001]$\mathrm{Contrast}\mathrm{ratio}\left[\%\right]=\frac{{\mathrm{Ry}}_{\mathrm{black}}}{{\mathrm{Ry}}_{\mathrm{white}}}100\%$

[0186] with Ry.sub.black and Ry.sub.white being obtained by the measurement of the colour values.

[0187] 2. Material

[0188] Mineral Material

[0189] Surface-reacted calcium carbonate (SRCC) having a d.sub.50 (vol) of 4.5 m, a d.sub.98 (vol) of 8.6 m; a BET specific surface area of 96 m.sup.2/g with an intra-particle intruded specific pore volume of 1.588 cm.sup.3/g (for the pore diameter range of 0.004 to 0.4 m).

[0190] It was prepared as follows:

[0191] In a mixing vessel, 10 liters of an aqueous suspension of ground limestone calcium carbonate was prepared by adjusting the solids of a ground limestone calcium carbonate having a particle size distribution of 90 wt % below 2 m based on the total weight of the ground calcium carbonate, such that a solids content of 15 wt % based on the total weight of the aqueous suspension is obtained.

[0192] Whilst mixing the slurry, 2.8 kg phosphoric acid was added in the form of an aqueous solution containing 30 wt % phosphoric acid to said suspension over a period of 10 minutes. Throughout the whole procedure the temperature of the suspension was maintained at 70 C. After the addition of the acid, the suspension was stirred for additional 5 minutes before removing it from the vessel and drying.

[0193] Water-Soluble Iron Salt

[0194] FeSO.sub.4 7H.sub.2O (from Sigma Aldrich; CAS No. 7782-63-0)

[0195] Treatment Agent

[0196] NaOH (from Sigma Aldrich; CAS No. 1310-73-2)

[0197] NaBH.sub.4 (from Sigma Aldrich; CAS No. 16940-66-2)

[0198] Commercially Available Iron Pigments

[0199] Ferroxide Black 78P (CAS No. 1317-61-9)

[0200] Pur Oxy Yellow BC (CAS No. 51274-00-1)

[0201] Ferroxide Red 226P (CAS No. 1309-37-1)

[0202] Solvent

[0203] Distilled water

[0204] 3. Pigment Preparation

[0205] 3.1. Preparation Using a Precipitation Agent

[0206] Prior to the preparation, surface-reacted calcium carbonate was dried overnight at 125 C. Subsequently, water was added into the reactor, a 3-neck round bottom flask, followed by the surface-reacted calcium carbonate. The slurry was stirred thoroughly during 30 minutes at room temperature. An aqueous solution of iron(II) sulfate heptahydrate was prepared, by solubilizing it in water. Subsequently, the solution was added dropwise to the surface-reacted calcium carbonate slurry. The mixture was kept under thorough mixing for 60 minutes.

[0207] A sodium hydroxide solution was prepared by adding the required amount to water. Then, the solution was added to the slurry and kept under mixing for 60 minutes. The mixture was dewatered via a filtration procedure using Whatman paper filters grade 589, washed with water (50% of the total water volume used during the preparation), then finally dried overnight at 125 C. in an oven.

[0208] Finally, the powder was manually deagglomerated and calcined in the temperature range of 300 C. up to 500 C., for a duration of 2 to 3 hours in a Nabertherm Le 6/11 muffle oven.

[0209] As can be taken from table 1, 14 samples were prepared using different amounts of iron (Fe) in the form of a water-soluble iron salt, and sodium hydroxide. The molar ratio of sodium hydroxide to iron (NaOH/Fe) was chosen to be 1 or 5. Each one of the 14 samples, was thermally treated at 125 C. (drying), and subsequently at 300 C. and 500 C. Thus, in total 52 samples were obtained.

[0210] The precipitation using NaOH occurs following the reaction:

FeSO.sub.4+2NaOHFe(OH).sub.2+Na.sub.2SO.sub.4

[0211] During the dewatering process, the sodium sulfate is removed with the filtrate. Iron hydroxide species are generated on the surface of the surface-reacted calcium carbonate and within its pores.

TABLE-US-00001 TABLE 1 Iron sulfate Sodium hydroxide wt % Iron NaOH/ SRCC slurry solution solution based Fe SRCC Water FeSO.sub.4 Water NaOH Water on the amount Molar Sample [g] [ml] 7 H.sub.2O [g] [ml] [g] [ml] of SRCC ratio A 200 1000 1 10 0.14 1 0.1 1 B 1 10 0.72 3.6 0.1 5 C 5 50 0.7 3.5 0.5 1 D 5 50 3.5 17.5 0.5 5 E 10 100 1.4 7 1 1 F 10 100 7.17 35.85 1 5 G 30 300 4.3 21.5 3 1 H 30 300 21.5 107.5 3 5 I 50 500 7.2 36 5 1 J 50 500 35.8 179 5 5 K 75 750 10.8 54 7.5 1 L 75 750 53.7 268.5 7.5 5 M 100 1000 14 70 10 1 N 100 1000 71.7 358.5 10 5

[0212] 3.2. Preparation Using a Reducing Agent

[0213] Prior to the preparation, surface-reacted calcium carbonate was dried overnight at 125 C. Subsequently, water was added into the reactor, a 3-neck round bottom flask, followed by the surface-reacted calcium carbonate. The slurry was stirred thoroughly during minutes at room temperature. An aqueous solution of iron(II) sulfate heptahydrate was prepared, by solubilizing it in water. Subsequently, the solution was added dropwise to the surface-reacted calcium carbonate slurry. The mixture was kept under thorough mixing for 60 minutes.

[0214] A NaBH.sub.4 solution was prepared by adding the required amount to water. Then, the solution was added to the slurry and kept under mixing for 60 minutes. The mixture was dewatered via a filtration procedure using Whatman paper filters grade 589, washed with water (50% of the total water volume used during the preparation), then finally dried overnight at 125 C. in a vacuum oven to prevent the oxidation of the iron species under an oxygen rich atmosphere.

[0215] Finally, the powder was deagglomerated and calcined, in the temperature range of 300 C. up to 500 C., for a duration of 2 to 3 hours in a Nabertherm Le 6/11 muffle oven.

[0216] As can be taken from table 2, 12 samples were prepared using different amounts of iron (Fe) in the form of a water-soluble iron salt and sodium borohydride. The molar ratio of sodium borohydride to iron (NaBH.sub.4/Fe) was chosen to be 1, 5 or 10. Each one of the 12 samples, was thermally treated at 125 C. (drying), and subsequently at 300 C. and 500 C. Thus, in total 36 samples were obtained.

[0217] The reduction using NaBH.sub.4 occurs according to the following reaction:

NaBH.sub.4+2H.sub.2O.fwdarw.NaBO.sub.2+4H.sub.2

[0218] The formed hydrogen reduces the Fe(II) species to elemental Fe(0). The sodium metaborate is removed during the dewatering process with the filtrate. The elementary iron species are generated on the surface of the surface-reacted calcium carbonate and within its pores.

TABLE-US-00002 TABLE 2 SRCC slurry FeSO.sub.4 solution NaBH.sub.4 solution wt % Fe based NaBH.sub.4/Fe SRCC Water FeSO.sub.4 Water NaBH.sub.4 Water on the amount Molar Sample [g] [ml] 7 H.sub.2O [g] [ml] [g] [ml] of SRCC ratio AA 200 1000 1 10 0.14 1 0.1 1 BB 1 10 0.72 3.6 0.1 5 CC 10 100 1.4 7 1 1 DD 10 100 7.2 35.85 1 5 EE 30 300 4.3 21.5 3 1 FF 30 300 21.5 107.5 3 5 GG 50 500 7.2 36 5 1 HH 50 500 35.8 179 5 5 II 100 1000 14 70 10 1 JJ 100 1000 71.7 358.5 10 5 CC/10 1 10 1.4 10 1 10 eq. FF/10 30 300 43 210.5 3 10 eq.

[0219] 3.3. Preparation without using a treatment agent (comparative examples)

[0220] Prior to the preparation, 100 g of surface-reacted calcium carbonate was dried overnight at 125 C. Subsequently, water was added into the reactor, a 3-neck round bottom flask, followed by the surface-reacted calcium carbonate. The slurry was stirred thoroughly during 30 minutes at room temperature. An aqueous solution of 100 g iron(II) sulfate heptahydrate was prepared, by solubilizing it in 1000 ml of water. Subsequently, the solution was added dropwise to the surface-reacted calcium carbonate slurry. The mixture was kept under thorough mixing for 120 minutes.

[0221] The mixture was dewatered via a filtration procedure using Whatman paper filters grade 589, washed with water (50% of the total water volume used during the preparation), then finally dried overnight at 125 C. in a vacuum oven to prevent the oxidation of the iron species under an oxygen rich atmosphere.

[0222] Finally, the powder was deagglomerated and calcined, in the temperature range of 300 C. up to 500 C., for a duration of 2 to 3 hours in a Nabertherm Le 6/11 muffle oven.

[0223] 4. Characterization

[0224] 4.1. XRD Characterization of the Samples

[0225] The data presented below are extracted from the XRD analysis. From tables 3 and 4, it can clearly be taken that by varying the iron species, the amount of iron species based on the dry weight of surface-reacted calcium carbonate, the molar ratio of precipitation agent or reducing agents to iron, and the calcination temperature, the species formed on the surface of the surface-reacted calcium carbonate is controllably modified leading to tailor made pigments as regards, colours, colour shades, UV and IR reflectance, as shown below.

[0226] The transformation of the water-soluble iron compound into a water-insoluble component or elementary iron deposited on the surface of the surface-treated calcium carbonate leads to a different composition of the species after calcination. Thus, the comparative samples, which were prepared without using a treatment agent, comprise calcium sulfate, whereas the inventive samples do not contain calcium sulfate, i.e. are different in this respect. This is especially important in cosmetic applications in view of the fact that calcium sulfate may cause irritations to the skin, eyes, mucous membranes and the upper respiratory system.

TABLE-US-00003 TABLE 3 Thermal Amount treatment of Fe NaOH/Fe ( C.) (wt %) molar ratio 125 500 FeO(OH) Fe.sub.2O.sub.3 Fe.sub.2O.sub.3 Fe.sup.0 CaSO.sub.4H.sub.2O CaSO.sub.4 3 5 X X X X.sup.a X.sup.a 3 X X X.sup. X.sup.a 7.5 X X X X.sup. 7.5 X X X.sup. X.sup.a 10 X X X X.sup.a X.sup.a 10 X X X.sup. 10 .sup.b X X.sup.a X.sup.a X 10 (comparative) X X.sup.a X.sup.a X .sup.aTraces; .sup.bNo treatment agent.

TABLE-US-00004 TABLE 4 NaBH.sub.4/Fe Thermal Fe species Amount molar treatment seen using of Fe ratio ( C.) XRD technique (wt %) 5 10 125 500 FeO(OH) Fe.sub.2O.sub.3 Fe.sub.2O.sub.3 Fe.sup.0 3 X X X.sup.a X.sup.a X 3 X X X 3 X X X.sup. X.sup. X 5 X X X.sup.a X 5 X X X.sup. X.sup. X 10 X X X 10 X X X.sup.a X.sup. X.sup. X .sup.aTraces

[0227] 4.2. Colours and Colour Shades

[0228] Due to the formation of different Fe species on the surface of the surface-reacted calcium carbonate, it is possible to tailor make pigments of different colours and colour shades from e.g. light beige to dark brown and black, not only by the iron species, the amount of iron species based on the dry weight of surface-reacted calcium carbonate, and the molar ratio of precipitation agent or reducing agents to iron, but also by the calcination temperature, as can be taken from FIGS. 1 (precipitation agent) and 2 (reducing agent) and tables 5 and 6 reflecting the different shades given in the figures in terms of CIE L*a*b* values. The color analysis was performed on the powdered samples placed in a sample cup as described above.

[0229] In FIG. 1 and table 5, the effects of increasing NaOH/Fe molar ratios (1:1, 5:1) at increasing temperatures (125 C., 300 C., 500 C.) and increasing iron amounts (0.1 wt %, wt %, 1 wt %, 3 wt %, 5 wt %, 7.5 wt %, 10 wt %) are given. In FIG. 1, the fields from left to right correspond to the composition of samples A to N given in table 5 at the respective temperatures.

[0230] In FIG. 2 and table 6, the effects of increasing NaBH.sub.4/Fe molar ratios (1:1, 5:1, 10:1) at increasing temperatures (125 C., 300 C., 500 C.) and increasing iron(0) amounts (0.1 wt %, 1 wt %, 3 wt %, 5 wt %, 10 wt %) are given. In FIG. 2, the fields from left to right correspond to the composition of samples BB to JJ, and CC with 10 eq. NaBH.sub.4, and FF with eq. NaBH.sub.4 given in table 6 at the respective temperatures.

[0231] Furthermore, E values are given in tables 5 and 6, which refer to the mixtures of surface-reacted calcium carbonate and commercial pigments mentioned in table 7.

TABLE-US-00005 TABLE 5 Elemental NaOH/Fe Temp. Fe molar E E Sample [ C.] [wt %] ratio L* a* b* black yellow red A 125 0.1 1 97.4 0.5 3.0 50.7 48.9 46.7 A 300 0.1 1 96.2 1.4 4.0 49.6 47.4 45.3 A 500 0.1 1 95.4 1.3 3.8 48.7 47.3 44.6 B 125 0.1 5 97.5 0.5 2.9 50.7 49.1 46.8 B 300 0.1 5 96.2 1.4 4.0 49.6 47.4 45.3 B 500 0.1 5 94.7 1.2 3.9 48.0 47.0 44.0 C 125 0.5 1 89.3 4.3 16.1 45.8 33.4 40.4 C 300 0.5 1 86.2 5.5 16.8 43.4 31.7 37.5 C 500 0.5 1 85.4 5.7 16.6 42.6 31.6 36.7 D 125 0.5 5 88.6 4.6 17.2 45.7 32.1 40.1 D 300 0.5 5 85.2 5.9 17.1 42.7 31.1 36.7 D 500 0.5 5 84.4 5.8 16.8 41.8 31.2 35.9 E 125 1.0 1 85.1 8.0 30.9 50.3 17.6 43.7 E 300 1.0 1 75.9 11.3 29.5 43.4 18.0 35.8 E 500 1.0 1 75.5 11.4 29.3 43.0 18.3 35.4 F 125 1.0 5 83.6 7.3 21.3 43.4 26.5 36.9 F 300 1.0 5 80.5 8.5 21.6 41.2 25.7 34.3 F 500 1.0 5 79.3 9.0 21.8 40.5 25.5 33.4 G 125 3.0 1 76.0 11.7 33.1 46.2 14.5 38.7 G 300 3.0 1 68.3 14.2 31.8 41.4 19.1 33.4 G 500 3.0 1 67.4 14.2 31.2 40.5 20.1 32.4 H 125 3.0 5 75.1 12.9 34.4 46.9 13.6 39.1 H 300 3.0 5 68.2 19.4 35.1 45.9 18.5 36.3 H 500 3.0 5 67.7 19.7 34.9 45.7 19.0 36.0 I 125 5.0 1 72.0 15.4 41.5 51.5 10.2 43.6 I 300 5.0 1 60.8 18.0 36.2 43.4 22.5 35.0 I 500 5.0 1 59.8 18.0 35.7 42.6 23.6 34.3 J 125 5.0 5 69.1 14.5 36.8 46.0 14.9 38.2 J 300 5.0 5 69.3 16.8 38.9 48.5 14.2 40.1 J 500 5.0 5 68.8 16.7 38.3 47.8 14.8 39.4 K 125 7.5 1 66.4 18.5 44.3 52.4 15.2 44.3 K 300 7.5 1 54.4 20.1 36.5 42.9 28.5 34.7 K 500 7.5 1 53.4 19.9 34.8 41.2 29.9 33.0 L 125 7.5 5 56.9 10.4 29.4 33.4 28.4 28.3 L 300 7.5 5 52.3 29.5 40.1 50.6 33.5 40.3 L 500 7.5 5 51.8 30.2 40.2 51.0 34.2 40.6 M 125 10.0 1 61.9 19.0 40.6 47.9 20.2 39.6 M 300 10.0 1 54.1 19.7 35.8 42.1 28.9 34.0 M 500 10.0 1 52.0 19.5 33.6 39.8 31.5 31.8 N 125 10.0 5 49.2 5.4 19.2 20.8 41.2 20.9 N 300 10.0 5 52.5 27.6 41.6 50.8 32.0 41.1 N 500 10.0 5 51.0 27.4 39.3 48.6 33.6 38.9 Z 125 0.0 76.7 10.4 32.1 45.6 15.3 38.5 Z 500 0.0 69.7 12.5 29.9 40.2 19.7 32.5

TABLE-US-00006 TABLE 6 Temp. Elemental NaBH.sub.4/Fe E E Sample [ C.] Fe (wt %) molar ratio L* a* b* black yellow red BB 125 0.1 5 98.0 0.4 2.4 51.2 49.7 47.3 BB 300 0.1 5 96.8 1.3 3.6 50.1 48.0 45.9 BB 500 0.1 5 95.7 1.1 3.2 49.0 48.0 44.9 CC 125 1.0 1 87.9 5.5 23.0 47.7 26.3 41.8 CC 300 1.0 1 81.8 8.0 23.4 43.2 24.1 36.5 CC 500 1.0 1 81.1 8.2 23.8 42.9 23.6 36.1 DD 125 1.0 5 82.5 1.1 8.6 36.9 39.9 33.5 DD 300 1.0 5 78.4 2.6 11.5 33.9 36.6 30.1 DD 500 1.0 5 82.5 5.6 17.4 40.4 30.4 34.6 EE 125 3.0 1 78.6 5.0 25.4 41.4 22.5 36.2 EE 300 3.0 1 69.0 8.9 27.0 36.6 22.6 30.4 EE 500 3.0 1 68.5 13.2 28.7 38.8 21.4 30.8 FF 125 3.0 5 56.5 0.5 2.2 9.7 55.4 17.8 FF 300 3.0 5 53.0 0.3 1.6 6.2 56.4 17.2 FF 500 3.0 5 65.6 19.1 21.7 34.8 30.0 23.3 GG 125 5.0 1 70.5 5.7 25.0 35.4 24.3 30.6 GG 300 5.0 1 61.0 8.2 24.0 29.7 29.5 24.7 GG 500 5.0 1 63.1 16.7 28.9 37.6 25.0 28.6 HH 125 5.0 5 55.0 0.9 1.4 8.2 55.4 17.8 HH 300 5.0 5 49.9 0.7 0.8 3.2 57.3 17.8 HH 500 5.0 5 54.1 7.5 9.8 14.7 45.0 11.9 II 125 10.0 1 68.4 14.1 36.9 45.6 15.2 38.0 II 300 10.0 1 60.7 16.6 34.5 41.3 23.1 33.3 II 500 10.0 1 58.0 17.1 32.2 38.7 26.6 30.5 JJ 125 10.0 5 39.9 0.4 1.9 7.1 63.7 22.0 JJ 300 10.0 5 37.7 0.2 0.5 9.2 64.0 23.1 JJ 500 10.0 5 54.5 17.9 26.0 33.0 33.2 24.1 CC/10 eq. 125 1.0 10 70.8 0.6 2.0 23.9 51.1 24.7 CC/10 eq. 300 1.0 10 67.6 0.2 1.1 20.7 50.8 22.1 CC/10 eq. 500 1.0 10 77.1 14.4 16.4 37.5 31.1 27.7 FF/10 eq. 125 3.0 10 55.4 1.0 4.3 9.3 57.8 18.7 FF/10 eq. 300 3.0 10 51.6 0.8 3.9 5.7 59.1 18.4 FF/10 eq. 500 3.0 10 63.0 18.4 18.4 30.9 33.9 19.0

TABLE-US-00007 TABLE 7 E E Sample (comparative) L* a* b* black yellow red 4.3 g SRCC + 0.7 g 46.9 0.4 0.9 0.0 58.7 17.6 Ferroxide Black 78P 4.0 g SRCC + 1.0 g 79.0 10.6 47.2 58.7 0.0 52.2 Pur Oxy Yellow BC 4.3 g SRCC + 0.7 g 53.5 16.5 2.0 17.6 52.2 0.0 Ferroxide Red 226P

[0232] A further big advantage of the compositions of the present invention is their efficiency as regards the amount of iron compound.

[0233] As can be taken from FIG. 19, in order to obtain a comparable colour, significantly less iron compound has to be used for the pigment according to the present invention compared with pigments consisting of surface-reacted calcium carbonate mixed with known pigments such as Ferroxide Black 78 P, Pur Oxy Yellow BC, or Ferroxide Red 226P.

[0234] Thus, e.g. a mixture of surface-reacted calcium carbonate and 10 wt % Pur Oxy Yellow BC leads to a comparable colour as an inventive sample at 3 wt % Fe, and a molar ratio of NaOH/Fe of 1:1 after drying at 125 C. However, the inventive sample needs a third of the iron content.

[0235] A mixture of surface-reacted calcium carbonate and 10 wt % Ferroxide Black 78P leads to a comparable colour as an inventive sample at 5 wt % Fe, and a molar ratio of NaBH.sub.4/Fe of 5:1 calcined at a temperature of 300 C. However, the inventive sample needs half of the iron content.

[0236] Finally, a mixture of surface-reacted calcium carbonate and 10 wt % Ferroxide Red 226P leads to a comparable colour as an inventive sample at 5 wt % Fe, and a molar ratio of NaBH.sub.4/Fe of 5:1 calcined at a temperature of 500 C. However, the inventive sample needs half of the iron content.

[0237] 4.3. UV/Vis/NIR Reflectance Characterization of the Samples

[0238] From FIGS. 3 to 18, not only the effect of different iron species, the amount of iron species based on the dry weight of surface-reacted calcium carbonate, and the molar ratio of precipitation agent or reducing agents to iron in the UV, visible up to the NIR spectrum can be seen, but also the effect of calcination compared to the same samples before calcination, i.e. being only dried at 125 C.

[0239] These figures clearly illustrate that for both, samples treated with precipitation agent (NaOH) and reducing agent (NaBH.sub.4) an increase of the amount of iron species leads to a decrease of the diffuse reflectance corresponding to an increase of the absorption in the UV and visible range.

[0240] The diffuse reflectance decrease occurs also in the NIR range and is more evident at high treatment agent: Fe ratios, and especially for the samples treated with the reducing agent (NaBH.sub.4). Upon calcination, the samples retain their UV absorption properties, which in some cases are even enhanced, while the modifications in the visible range correlate with the color change of the samples. In the NIR range, the spectra of the calcined samples resemble that of the SSRC. The inventive samples have therefore an improved UV protection compared to the SRCC. Additionally, the inventive samples have similar IR properties compared to the SRCC in all cases except for the samples treated with the reducing agent (NaBH 4) at high treatment agent:Fe ratios.

[0241] 5. Cosmetic Formulations

[0242] In order to study the suitability of the inventive pigments in cosmetic applications, several formulations have been prepared and examined. The base formulations were prepared as follows:

[0243] a) Water-In-Oil Cream (W/O Cream)

TABLE-US-00008 TABLE 8 Ingredients Tradename/Supplier % w/w A Water add. 100 Magnesium sulfate 1.0 Sodium chloride Sigma Aldrich, Switzerland 1.0 Glycerin 20.0 B Polyglyceryl-3 diisostearate Plurol Diisostearique CG 5.0 (Gattefoss, France) Dicaprylyl carbonate Cetiol CC (BASF, Switzerland) 10.5 Octyldodecyl myristate MOD (Gattefoss, France) 4.5 Caprylic/capric Labrafac CC MB (Gattefoss, 1.0 triglycerides France) C Fragrance (Parfum) Perfume (Hnseler AG, Switzerland) q.s Leuconostoc Radish Root Leucidal (Hnseler AG, 3.00 Ferment Filtrate (and) Aqua Switzerland)

[0244] Phase A and B were heated separately at 80 C. Subsequently, phase B was added to phase A while stirring. The mixture was cooled down at room temperature. Subsequently, phase C was added to the mixture and homogenized resulting in a mattifying cream.

[0245] b) Oil-In-Water Cream (O/W Cream)

TABLE-US-00009 TABLE 9 Ingredients Tradename/Supplier % w/w A Cetearyl alcohol Lanette O (Cognis GmbH, Germany) 2.00 Tribehenin PEG-20 esters Emulium 22MB (Gattefoss, France) 3.00 Prunus Amygdalus Dulcis Almond Oil (Hnseler AG, Switzerland) 2.00 (Almond) oil Macadamia Ternifolia seed Macadamia Oil (Hnseler AG, 3.00 oil Switzerland) 4.00 Caprylic/capric triglyceride Miglyol 812 (Hnseler AG, Switzerland) 4.00 Octyldodecyl myristate MOD (Gattefoss, France) 1.00 Tocopheryl acetate Copherol 1250C (Sigma Aldrich, Switzerland) B Aqua (water) Water demineralized add. 100 Propanediol Propanediol Zemea (Omya Inc. USA) 5.00 Glycerin Glycerin 3.00 Xanthan gum Xanthan Gum (Omya Hamburg GmbH, 0.10 Germany) Sodium chloride Sodium Chloride 0.50 Allantoin Allantoin EP (Omya Hamburg GmbH, 0.10 Germany) C Fragrance (parfum) Perfume (Omya AG, Switzerland) q.s Leuconostoc Radish Root Leucidal (Omya Inc. USA) 3.00 Ferment Filtrate (and) Aqua

[0246] Phase A and B were heated separately at 80 C. Subsequently, phase B was added to phase A while stirring. The mixture was cooled down at room temperature. Subsequently, phase C was added to the mixture and homogenized resulting in a mattifying cream. The pH was adjusted to a pH of 6 using lactic acid (10%-solution), if necessary.

[0247] c) Pigment Addition

[0248] To these creams, pigments according to the invention were added as mentioned in the below tables and investigated as regards their colors in W/O and O/W creams.

[0249] The composition and characteristics of the used pigments can be taken from the tables above, wherein, e.g. HEI 500 means sample HEI calcined at a temperature of 500 C.

[0250] 5.1. Screening of Red Colored SRCC

TABLE-US-00010 TABLE 10 Sample 1 2 3 4 5 6 7 Description Cream W/O % HH 500 red 1% 2% 3% 6% 10% 15% 20% Rx 58.1 45.4 43.6 30.8 25.0 22.7 17.0 Ry 49.9 36.5 34.9 22.7 17.8 16.0 12.5 Rz 38.3 24.8 23.5 13.1 9.4 8.5 7.1 L* 76.0 66.9 65.6 54.8 49.2 46.9 42.0 a* 11.6 15.4 15.8 19.7 21.0 21.0 16.2 b* 13.3 17.2 17.3 20.6 21.4 20.7 17.1 Delta E 34.8 25.7 24.5 15.5 12.4 11.0 10.4

[0251] It can be seen from table 10 and FIG. 20 that it is possible to finely tune the colour of a W/O cream in the red colour range.

[0252] 5.2 Screening of Yellow Colored SRCC

TABLE-US-00011 TABLE 11 Sample 8 9 10 11 12 13 14 Description Cream W/O % E300 yellow 1% 2% 3% 6% 7% 10% 15% Rx 79.6 71.5 64.9 56.0 56.4 51.6 45.1 Ry 72.6 63.1 55.3 45.1 45.5 40.6 34.2 Rz 54.2 42.4 33.2 22.5 22.9 19.0 14.5 L* 88.2 83.5 79.2 72.9 73.2 69.9 65.1 a* 4.5 6.4 8.6 12.5 12.4 14.0 16.5 b* 16.7 21.3 25.7 31.7 31.4 33.1 34.9 Delta E 42.3 36.0 30.3 23.2 23.4 21.8 21.4

[0253] It can be seen from table 11 and FIG. 21 that it is possible to finely tune the colour of a W/O cream in the yellow colour range.

[0254] 5.3. Screening of Black Colored SRCC

TABLE-US-00012 TABLE 12 Sample 15 16 17 18 19 20 Description Cream W/O % HH300 black 1% 2% 3% 6% 10% 15% Rx 41.3 29.7 25.5 14.1 10.9 8.8 Ry 41.1 29.5 25.5 14.1 10.8 8.8 Rz 39.9 28.6 24.7 13.6 10.4 8.4 L* 70.2 61.3 57.5 44.4 39.3 35.5 a* 0.3 0.3 0.4 0.3 0.3 0.2 b* 1.5 1.4 1.2 1.2 1.2 1.1 Delta E 36.8 27.8 24.1 11.1 6.1 2.8

[0255] It can be seen from table 12 and FIG. 22 that it is possible to finely tune the colour of a W/O cream in the grey colour range.

[0256] 5.4 Screening of brown colored SRCC

[0257] 5.4.1 Water-In-Oil Cream (W/O Cream)

TABLE-US-00013 TABLE 13 Sample 21 22 23 24 Cream W/O % M125 Description 3% 5% 8% 10% Rx 52.1 41.2 31.5 29.6 Ry 41.45 30.72 22.15 20.58 Rz 20.3 12.3 7.8 7.1 L* 70.5 62.3 54.2 52.5 a* 13.3 17.5 20.5 21.0 b* 31.7 35.5 35.5 35.3

[0258] It can be seen from table 13 and FIG. 23 that it is possible to finely tune the colour of a W/O cream in the brown colour range.

[0259] 5.4.2 Oil-in-water Cream (O/W Cream)

TABLE-US-00014 TABLE 14 Sample 25 26 27 28 Cream O/W % M125 Description 3% 5% 8% 10% Rx 51.5 44.5 37.3 33.3 Ry 40.42 33.62 26.88 23.45 Rz 19.0 14.1 9.7 8.1 L* 69.8 64.7 58.9 55.5 a* 14.5 16.9 19.6 20.7 b* 33.0 35.1 37.1 36.9

[0260] It can be seen from table 14 and FIG. 24 that it is also possible to finely tune the colour of a O/W cream in the brown colour range, wherein the colours are nearly the same as in the corresponding W/O cream samples.

[0261] 5.5. Coverage

[0262] In order to determine the covering power (coverage) of the pigment material, a base composition comprising different pigment concentrations of the pigment material, namely 5 and 10 wt %, were prepared. The covering power of the respective base compositions was determined by measuring the colour values (Rx, Ry, Rz) and then calculating the contrast ratio, as described above.

[0263] The base composition contains the ingredients listed in Table 15.

TABLE-US-00015 TABLE 15 Weight % (based on total weight Ingredients Tradenames (Suppliers) Compound of base colour) Demineralised water Demineralised water 40.0 Dispersing agent Calgon N new (BK Giulini) Sodium polyphosphate 0.2 Thickener Bermocoll EHM 200 (Akzo Cellulose ether 1.0 Nobel) pH Regulation Sodium hydroxide solution, Sodium hydroxide solution 0.6 10% (Sigma-Aldrich) Defoamer Byk 011 (Byk (Altana Group)) Polymer 2.0 Film forming agent Texanol (Eastman) Isobutyric acid, ester with 0.5 2,2,4-trimethyl-1,3- pentanediol Film forming agent Butyldiglycol acetate (Sigma- Ester 0.5 Aldrich) Film forming agent Dowanol DPnB (Dow) Dipropylene glycol n-butyl 1.0 ether Defoamer Byk 019 (Byk (Altana Group)) Polyether-modified 0.5 polydimethylsiloxane Rheology modifier Coapur 2025 (Coatex Polyurethane based 1.8 (Arkema Group)) Preservative Mergal 723 K (Troy Chemical Benzoisothiazolinone 0.2 Company) Demineralized water Demineralised water 5.0 Wetting and Ecodis P 90 (Coatex Ammonium neutralized 0.6 dispersing agent (Arkema Group)) polyacrylate Wetting agent Disperbyk-181 (Byk (Altana Alkylolammonium salt of a 1.0 Group)) polyfunctional polymer Surfactant Byk 349 (Byk (Altana Group)) Polyether-modified siloxane 0.4 Demineralized water Demineralised water 14.7 Binding agent Mowilith DM 2425, 50% Aqueous copolymer 30.0 (Celanese) dispersion based on vinyl acetate Total 100.0

[0264] The base composition was prepared as follows:

[0265] The demineralized water was added to a beaker, then, Calgon, Bermocoll and the sodium hydroxide solution were added under stirring with a lab dissolver until all ingredients were dissolved. Then the other ingredients listed in Table 16 up to Byk 349 were added while continuously stirring the mixture. Then the demineralized water was added and the resulting mixture was thoroughly mixed. Finally, the binding agent Mowilith was added during continuous stirring of the mixture at a speed of 100 rpm to obtain the final base colour.

[0266] This base composition was used for the preparation of formulations with different pigment concentrations.

[0267] As pigments, M125 and untreated SRCC were used in order to verify whether the treatment has an impact on the coverage.

[0268] The formulations were prepared by weighing the respective pigment material in the required amount and adding the respective amount of the base composition. Then the resulting mixtures were homogenized for 1 minute by use of a speed mixer at a speed of 3000 rpm. Then the mixture was mixed using a spatula and, subsequently, the mixture was again homogenized for 1 minute by use of a speed mixer at a speed of 3000 rpm. The resulting mixture was then used for the measurement of the colour values (Rx, Ry, Rz) which in turn were used for the calculation of the contrast ratio.

[0269] The contrast ratio (coverage) values for the used pigment materials at the different pigment concentrations are listed in Table 16.

TABLE-US-00016 TABLE 16 wt % pigment based on the total weight of the formulation Coverage (%) 5 wt % M125 13 10 wt % M125 36 5 wt % SRCC 13 10 wt % SRCC 43

[0270] It can be seen from these results that the treatment of SRCC according to the invention does not essentially affect the coverage of the formulation. The coverage is furthermore illustrated in FIG. 25.