Treatment of surface-reacted calcium carbonate

Abstract

The present invention relates to a method for the treatment of a surface-reacted calcium carbonate, wherein the treatment agent is selected from the group consisting of ascorbic acid and/or salts thereof, gallic acid and/or salts thereof, unsaturated fatty acids and/or salts thereof, elemental iron, iron (II)-salts, iron (II)-comprising oxides, iron (II, III)-comprising oxides and mixtures thereof, a treated surface-reacted calcium carbonate as well as a use of the treated surface-reacted calcium carbonate as oxygen scavenger.

Claims

1. A method for the treatment of a surface-reacted calcium carbonate, the method comprising the steps of: a) providing surface-reacted calcium carbonate, wherein the surface-reacted calcium carbonate is a reaction product of natural ground calcium carbonate or precipitated calcium carbonate with carbon dioxide and one or more H.sub.3O.sup.+ ion donors, 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; b) providing a treatment agent being selected from the group consisting of ascorbic acid and/or salts thereof, gallic acid and/or salts thereof, unsaturated fatty acids and/or salts thereof, elemental iron, iron (II)-salts, iron (II)-comprising oxides, iron (II, III)-comprising oxides and mixtures thereof, and c) combining the surface-reacted calcium carbonate of step a) with the treatment agent of step b) in one or more steps at a temperature of from 10 to 200° C. under mixing, such that the total weight of the treatment agent added is from 0.01 to 40 mg/m.sup.2, based on the surface-reacted calcium carbonate of step a), wherein the surface-reacted calcium carbonate provided in step a) has a moisture content of less than 10.0 wt.-% based on the dry weight of the surface-reacted calcium carbonate provided in step a), and wherein the one or more H.sub.3O.sup.+ ion donors is selected from the group consisting of hydrochloric acid, sulphuric acid, sulphurous acid, phosphoric acid, citric acid, oxalic acid, acetic acid, formic acid, and mixtures thereof.

2. The method according to claim 1, wherein the natural ground calcium carbonate is selected from calcium carbonate containing minerals selected from the group comprising marble, chalk, dolomite, limestone and mixtures thereof; and that the precipitated calcium carbonate is selected from the group comprising precipitated calcium carbonates having aragonitic, vateritic or calcitic mineralogical crystal forms or mixtures thereof.

3. The method according to claim 1, wherein the surface-reacted calcium carbonate has i) a specific surface area of from 15 m.sup.2/g to 200 m.sup.2/g, measured using nitrogen and the BET method according to ISO 9277, and/or ii) a volume median grain diameter d.sub.50 of from 1 to 75 μm, and/or iii) an intra-particle pore size in a range of from 0.004 to 1.6 μm, determined from a mercury porosimetry measurement, and/or iv) an intra-particle intruded specific pore volume within the range of 0.1 to 2.3 cm.sup.3/g, calculated from mercury porosimetry measurement.

4. The method according to claim 1, wherein the treatment agent is a) liquid at 25° C. and ambient pressure, or b) in molten form, and/or c) dissolved in a solvent, or d) dispersed in a suspension.

5. The method according to claim 1, wherein the total weight of the treatment agent of step b) added in step c) is from 0.1 to 40 mg/m.sup.2, based on the surface-reacted calcium carbonate of step a).

6. The method according to claim 1, wherein the treatment agent of step b) is added in step c) in an amount of from 0.01 to 80.0 wt.-%, based on the total dry weight of surface-reacted calcium carbonate of step a).

7. The method according to claim 1, wherein the unsaturated fatty acid is selected from the group consisting of oleic acid, linoleic acid, linolenic acid, crotonic acid, myristoleic acid, palmitoleic acid, sapienic acid, elaidic acid, vaccenic acid, gadoleic acid, erucic acid, nervonic acid, ecosadienoic acid, docosadienoic acid, pinoleic acid, eleostearic acid, mead acid, dihomo-γ-linolenic acid, eicosatrienoic acid, stearidonic acid, arachidonic acid, eicosatetraenoic acid, adrenic acid, bosseopentaenoic acid, eicosapentaenoic acid, ozubondo acid, sardine acid, tetracosanolpentaenoic acid, docosahexaenoic acid, herring acid, salts of these acids and mixtures thereof.

8. The method according to claim 1, wherein the treatment agent is ascorbic acid and/or salts thereof, gallic acid and/or thereof and mixtures thereof.

9. The method according to claim 1, wherein the method comprises a further step d) of treating the surface-reacted calcium carbonate obtained in step c) with at least one supplemental agent which is a hydrophobising agent.

10. The method according to claim 1, wherein the method comprises a further step of encapsulating the surface-reacted calcium carbonate obtained in step c) .

11. A treated surface-reacted calcium carbonate comprising a) a surface-reacted calcium carbonate, wherein the surface-reacted calcium carbonate is a reaction product of natural ground calcium carbonate or precipitated calcium carbonate with carbon dioxide and one or more H.sub.3O.sup.+ ion donors, 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, and b) a treatment agent is located as a treatment layer on at least a part of the surface of the surface-reacted calcium carbonate and/or the treatment agent is loaded into at least a part of the pores as a pore filler of the surface-reacted calcium carbonate, wherein i) the treatment layer or the pore filler consists of a treatment agent selected from the group consisting of ascorbic acid and/or salts thereof, gallic acid and/or salts thereof, unsaturated fatty acids and/or salts thereof, elemental iron, iron (II)-salts, iron (II)-comprising oxides, iron (II, III)-comprising oxides and mixtures thereof, and/or reaction products thereof, ii) the total weight of the treatment agent on the total surface area or in the pores of the surface-reacted calcium carbonate is from 0.01 to 40 mg/m.sup.2, based on the surface-reacted calcium carbonate of step a), and iii) the surface-reacted calcium carbonate provided in a) has a moisture content of less than 10.0 wt.-% based on the dry weight of the surface-reacted calcium carbonate provided in step a) wherein the one or more H.sub.3O.sup.+ ion donors is selected from the group consisting of hydrochloric acid, sulphuric acid, sulphurous acid, phosphoric acid, citric acid, oxalic acid, acetic acid, formic acid, and mixtures thereof.

12. The treated surface-reacted calcium carbonate according to claim 11, wherein the total weight of the treatment agent on the total surface area or in the pores of the surface-reacted calcium carbonate is from 0.01 to 40 mg/m.sup.2.

13. The treated surface-reacted calcium carbonate according to claim 11, wherein the treated surface-reacted calcium carbonate has a moisture pick up susceptibility in the range from 0.05 to 100 mg/g.

14. The treated surface-reacted calcium carbonate according to claim 11, wherein the treated surface-reacted calcium carbonate comprises at least one supplemental agent which is a hydrophobising agent which at least partially covers the treated surface-reacted calcium carbonate or is loaded into at least a part of the pores of treated surface-reacted calcium carbonate.

15. The treated surface-reacted calcium carbonate according to claim 14, wherein the total weight of the at least one hydrophobising agent on the total surface area or in the pores of the treated surface-reacted calcium carbonate is from 0.001 to 10 mg/m.sup.2.

16. A product comprising the treated surface-reacted calcium carbonate of claim 11 as an oxygen scavenger.

17. The product use according to claim 16, wherein the product is selected from the group consisting of polymer compositions, coatings, polymer coatings, paper coatings, products in food applications, products in filter and/or cosmetic applications.

18. The method according to claim 9, wherein the method comprises a further step of encapsulating the surface-reacted calcium carbonate obtained in step d).

19. A method for the treatment of a surface-reacted calcium carbonate, the method consists of the steps of: a) providing surface-reacted calcium carbonate, wherein the surface-reacted calcium carbonate is a reaction product of natural ground calcium carbonate or precipitated calcium carbonate with carbon dioxide and one or more H.sub.3O.sup.+ ion donors, 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; b) providing a treatment agent being selected from the group consisting of ascorbic acid and/or salts thereof, gallic acid and/or salts thereof, unsaturated fatty acids and/or salts thereof, elemental iron, iron (II)-salts, iron (II)-comprising oxides, iron (II, III)-comprising oxides and mixtures thereof, c) combining the surface-reacted calcium carbonate of step a) with the treatment agent of step b) in one or more steps at a temperature of from 10 to 200° C. under mixing, such that the total weight of the treatment agent added is from 0.01 to 40 mg/m.sup.2, based on the surface-reacted calcium carbonate of step a), d) optionally treating the surface-reacted calcium carbonate obtained in step c) with at least one supplemental agent which is a hydrophobising agent, e) optionally encapsulating the surface-reacted calcium carbonate obtained in step c) or, if present, step d), and f) optionally drying the surface-reacted calcium carbonate obtained in step c), step d), or step e), wherein the surface-reacted calcium carbonate provided in step a) has a moisture content of less than 10.0 wt.-% based on the dry weight of the surface-reacted calcium carbonate provided in step a), and wherein the one or more H.sub.3O.sup.+ ion donors is selected from the group consisting of hydrochloric acid, sulphuric acid, sulphurous acid, phosphoric acid, citric acid, oxalic acid, acetic acid, formic acid, and mixtures thereof.

20. The method according to claim 1, wherein the treatment agent is gallic acid and/or salts thereof.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows the results of oxygen scavenging tests of linoleic acid treatment in Examples 14, 15, and 16, in terms of O.sub.2 scavenged (mL O.sub.2/g total powder).

(2) FIG. 2 shows the results of oxygen scavenging tests of linoleic acid treatment in Examples 14, 15, and 16, in terms of O.sub.2 scavenged (mL O.sub.2/g linoleic acid).

(3) FIG. 3 shows the results of oxygen scavenging tests of oleic acid treatment in Examples 17, 18, and 19, in terms of O.sub.2 scavenged (mL O.sub.2/g total powder).

(4) FIG. 4 shows the results of oxygen scavenging tests of oleic acid treatment in Examples 17, 18, and 19, in terms of O.sub.2 scavenged (mL O.sub.2/g oleic acid).

(5) FIG. 5 shows the results of oxygen scavenging tests of ascorbic acid treatment and isoascorbic acid treatment in Examples 21 and 22, in terms of O.sub.2 scavenged (mL O.sub.2/g total powder).

(6) FIG. 6 shows the results of oxygen scavenging tests of ascorbic acid treatment and isoascorbic acid treatment in Examples 21 and 22, in terms of O.sub.2 scavenged (mL O.sub.2/g active agent).

(7) FIG. 7 shows the results of oxygen scavenging tests of gallic acid treatment in Example 20, in terms of O.sub.2 scavenged (mL O.sub.2/g total powder).

(8) FIG. 8 shows the results of oxygen scavenging tests of gallic acid treatment in Example 20, in terms of O.sub.2 scavenged (mL O.sub.2/g active compound).

(9) FIG. 9 shows the results of oxygen scavenging tests of iron sulphate pentahydrate treatment and iron nanopowder in Examples 23 and 24, in terms of O.sub.2 scavenged (mL O.sub.2 /g total powder).

(10) FIG. 10 shows the results of oxygen scavenging tests of paper coated with oleic acid in Example 25, in terms of O.sub.2 scavenged (mL O.sub.2/g coating).

EXAMPLES

(11) 1 Measurement Methods

(12) In the following the measurement methods implemented in the examples are described.

(13) Moisture Content of Calcium Carbonate

(14) A 10 g powder sample was heated in an oven at 150° C. until the mass is constant for 20 minutes. The mass loss was determined gravimetrically and is expressed as wt.-% loss based on the initial sample mass. This mass loss has been attributed to the sample humidity.

(15) Moisture Pick Up Susceptibility

(16) The moisture pick up susceptibility of a material as referred to herein was determined in mg moisture/g after exposure to an atmosphere of 10 and 85% relative humidity, respectively, for 2.5 hours at a temperature of +23° C. (±2° C.). For this purpose, the sample was first kept at an atmosphere of 10% relative humidity for 2.5 hours, then the atmosphere is changed to 85% relative humidity at which the sample is kept for another 2.5 hours. The weight increase between 10 and 85% relative humidity was then used to calculate the moisture pick-up in mg moisture/g of sample.

(17) The moisture pick up susceptibility in mg/g divided by the specific surface area in m.sup.2/g (calculated based on the specific surface area BET) corresponds to the “normalized moisture pick up susceptibility” expressed in mg/m.sup.2 of sample.

(18) Solids Content

(19) The suspension solids content (also known as “dry weight”) was determined using a Moisture Analyser MJ33 (Mettler-Toledo, Switzerland), with the following settings: drying temperature of 150° C., automatic switch off if the mass does not change more than 1 mg over a period of 30 sec, standard drying of 5 to 20 g of suspension.

(20) Oxygen Scavenging Tests

(21) Oxygen-scavenging tests were performed by placing a defined amount of powder in a closed desiccator equipped with an oxygen measuring device (GOX 100, GHM Messtechnik GmbH, Germany). The relative amount of oxygen in air was recorded regularly and the total amount of oxygen scavenged by gram of sample (or active substance) estimated, assuming the gas respect the ideal gas law, and neglecting the volume occupied by the powders. Results were expressed as mL O.sub.2/g of powder, or mL O.sub.2/g of active substance.

(22) The following equations were used for the calculations:

(23) $n\left(\mathrm{gas}\right)=\frac{\mathrm{PV}}{R.Math.T}n\left(O_2\right)=n\left(\mathrm{gas}\right)\times 20.9/100m\left(O_2\right)=n\left(O_2\right)\times M\left(O_2\right)V\left(O_{2\mathrm{desiccator}}\right)=V\left(\mathrm{desiccator}\right)\times 20.9/100$
Assuming R=8.314 J.Math.K.sup.−1.Math.mol.sup.−1 T=295 K P=101 300 Pa M (O.sub.2)=32 g.Math.mol.sup.−1% O.sub.2 in air=20.9%

(24) The values presented in the experimental section are calculated as follow:

(25) $O_2\mathrm{scavenged}\left(\mathrm{mL}/g\mathrm{of}\mathrm{powder}\right)=\frac{20.\left(\%O_2\mathrm{measured}\right)}{20.9}\times \frac{V_{O2\mathrm{desiccator}}}{m\left(\mathrm{powder}\right)}{O}_2\mathrm{scavanged}\left(\mathrm{mL}/g\mathrm{of}\mathrm{surface}\mathrm{treatment}\mathrm{agent}\right)=O_2\mathrm{scavenged}\left(\mathrm{mL}/g\mathrm{of}\mathrm{powder}\right)\times \frac{m\left(\mathrm{surface}\mathrm{treatment}\mathrm{agent}\right)}{m\left(\mathrm{powder}\mathrm{after}\mathrm{treatment}\right)})$
Particle Size Distribution (Volume % Particles with a Diameter <X), d.sub.50 Value (Volume Median Particle Diameter) and d.sub.98 Value of a Particulate Material:

(26) Volume median grain diameter d.sub.50 was evaluated using a Malvern Mastersizer 2000 Laser Diffraction System (Malvern Instruments Plc., Great Britain) using the Mie theory, with a particle refractive index of 1.57 and an absorption index of 0.005. Alternatively, the measurement can be made with a HELOS particle-size-analyser of Sympatec, Germany. The measurement may be considered equivalent to weight distribution assuming a constant density throughout the particle size distribution, and reference is made to the measurement technique.

(27) Weight median grain diameter and grain diameter weight distribution of a particulate material were determined via the sedimentation method, i.e. an analysis of sedimentation behaviour in a gravimetric field. The measurement was made with a Sedigraph TM 5120.

(28) The method and instrument are known to the skilled person and are commonly used to determine grain size of fillers and pigments. The measurement is 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 mixer and ultrasound.

(29) Intra Particle Intruded Specific Pore Volume

(30) The intra-particle intruded specific pore volume has been calculated from a mercury intrusion porosimetry measurement using a Micromeritics Autopore IV 9500 mercury porosimeter having a maximum applied pressure of mercury 414 MPa (60 000 psi), equivalent to a Laplace throat diameter of 0.004 μm. The equilibration time used at each pressure step is 20 seconds. 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 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, p1753-1764.).

(31) 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 interparticle packing of the particles themselves. If they also have intraparticle pores, then this region appears bi modal. 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. 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.

(32) 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.

(33) BET Specific Surface Area of a Material

(34) Throughout the present document, the specific surface area (in m.sup.2/g) of the filler material is determined using the BET method (using nitrogen as adsorbing gas), which is well known to the skilled man (ISO 9277:2010). The total surface area (in m.sup.2) of the filler material is then obtained by multiplication of the specific surface area and the mass (in g) of the filler material prior to treatment.

(35) 2 Preparation of Treated Surface-Reacted Calcium Carbonate

(36) In the following description of the preparation of the Examples and Comparative Examples the indication of weight in form of “parts” always refers to “parts by weight”, unless indicated otherwise.

2.1 Treatments with Unsaturated Fatty Acids

2.1.1 Example 1—Powder 1

(37) 600 g of surface-reacted calcium carbonate (d.sub.50=2.4 μm, BET specific surface area=37 m.sup.2/g) was placed in a high speed mixer (MTI Mixer, MTI Mischtechnik International GmbH, Germany), and conditioned by stirring for 10 minutes (3 000 rpm, 30° C.). Then, 0.6 parts relative to 100 parts surface-reacted calcium carbonate of linoleic acid (3.6 g, Sigma-Aldrich (Germany), technical grade 60-74%) was added and stirring was continued for another 20 minutes at 30° C. This treatment level corresponds to approx. 0.16 mg/m.sup.2. Subsequently, the mixture was cooled down and taken out of the mixer. A white powder was collected (Powder 1).

2.1.2 Example 2—Powder 2

(38) 800 g of surface-reacted calcium carbonate (d.sub.50=2.4 μm, BET specific surface area=37 m.sup.2/g) was placed in a high speed mixer (MTI Mixer, MTI Mischtechnik International GmbH, Germany), and conditioned by stirring for 10 minutes (3 000 rpm, 30° C.). Then, 1.0 parts relative to 100 parts surface-reacted calcium carbonate of linoleic acid (8 g, Sigma-Aldrich (Germany), technical grade 60-74%) was added and stirring was continued for another 20 minutes at 30° C. This treatment level corresponds to approx. 0.27 mg/m.sup.2. Subsequently, the mixture was cooled down and taken out of the mixer. A white powder was collected (Powder 2).

2.1.3 Example 3—Powder 3

(39) 700 g of surface-reacted calcium carbonate (d.sub.50=2.4 μm, BET specific surface area=37 m.sup.2/g) was placed in a high speed mixer (MTI Mixer, MTI Mischtechnik International GmbH, Germany), and conditioned by stirring for 10 minutes (3 000 rpm, 30° C.). Then, 3.0 parts relative to 100 parts surface-reacted calcium carbonate of linoleic acid (21 g, Sigma-Aldrich (Germany), technical grade 60-74%) was added and stirring was continued for another 20 minutes at 30° C. This treatment level corresponds to approx. 0.81 mg/m.sup.2. Subsequently, the mixture was cooled down and taken out of the mixer. A white powder was collected (Powder 3).

2.1.4 Example 4—Powder 4

(40) 600 g of surface-reacted calcium carbonate (d.sub.50=2.4 μm, BET specific surface area=37 m.sup.2/g) was placed in a high speed mixer (MTI Mixer, MTI Mischtechnik International GmbH, Germany), and conditioned by stirring for 10 minutes (3 000 rpm, 30° C.). Then, 3.0 parts relative to 100 parts surface-reacted calcium carbonate of oleic acid (18 g, Fluka (Belgium)) was added and stirring was continued for another 20 minutes at 30° C. This treatment level corresponds to approx. 0.81 mg/m.sup.2. Subsequently, the mixture was cooled down and taken out of the mixer. A white powder was collected (Powder 4).

2.1.5 Example 5—Powder 5

(41) 700 g of surface-reacted calcium carbonate (d.sub.50=2.4 μm, BET specific surface area=37 m.sup.2/g) was placed in a high speed mixer (MTI Mixer, MTI Mischtechnik International GmbH, Germany), and conditioned by stirring for 10 minutes (1 000 rpm, 30° C.). Then, 10 parts relative to 100 parts surface-reacted calcium carbonate of oleic acid (70 g, Fluka (Belgium)) was added and stirring was continued for 10 minutes at 30° C./2 000 rpm, followed by 10 minutes at 40° C./3 000 rpm, and finally 20 minutes at 80° C./3 000 rpm. This treatment level corresponds to approx. 2.70 mg/m.sup.2. Subsequently, the mixture was cooled down and taken out of the mixer. A white powder was collected (Powder 5).

2.1.6 Example 6—Powder 6

(42) 500 g of surface-reacted calcium carbonate (d.sub.50=2.4 μm, BET specific surface area=37 m.sup.2/g) was placed in a Lödige mixer (M5 R-MK, Gebrüder Lödige Maschinenbau GmbH, Germany) at room temperature. Stirring was activated and 20 parts relative to 100 parts surface-reacted calcium carbonate of oleic acid (100 g, Fluka (Belgium)) was added dropwise with a peristaltic pump (addition time: approx. 1 h) and stirring was continued at room temperature for 1 hour after addition. This treatment level corresponds to approx. 5.41 mg/m.sup.2. Subsequently, the mixture was taken out of the mixer. A white powder was collected (Powder 6).

2.1.7 Example 7—Slurry 7

(43) To 500 g (100 parts) of powder 4 in a 2 L bottle was added 400 g deionized water, 120 g ethanol and 1.0 parts of a polyacrylate dispersant (11.9 g of a 42 wt.-% aqueous solution of a 100% sodium-neutralised polyacrylate, M.sub.w=3 500 g/mol, pH=8) is added dropwise under strong stirring (930 rpm) at room temperature (Pendraulik stirrer). After the end of addition, stirring was continued for 10 minutes. The slurry was used without further modifications (Slurry 7).

2.2 Treatments with Ascorbic Acid

2.2.1 Example 8—Powder 8

(44) 300 g of surface-reacted calcium carbonate (d.sub.50=2.4 μm, BET specific surface area=37 m.sup.2/g) was placed in a Lödige mixer (M5 R-MK, Gebrüder Lödige Maschinenbau GmbH, Germany) at room temperature. Stirring was activated and 10 parts relative to 100 parts surface-reacted calcium carbonate of L-ascorbic acid (reagent grade, Sigma life science, China, 133 g of a previously prepared 22.6 wt.-% aqueous solution) was added dropwise with a peristaltic pump (addition time: approx. 20 minutes) and stirring was continued at room temperature for 20 minutes after addition. This treatment level corresponds to approx. 2.70 mg/m.sup.2. Subsequently, the mixture was taken out of the mixer. A beige/brown powder was collected (Powder 8).

2.2.2 Example 9—Powder 9

(45) 300 g of dry surface-reacted calcium carbonate (d.sub.50=4.5 μm, BET specific surface area=139 m.sup.2/g) was placed in a Somakon mixer (Somakon Verfahrenstechnik UG, Germany) and conditioned by stirring at 30° C. for 10 minutes (300 rpm). Then, 5 parts relative to 100 parts surface-reacted calcium carbonate of D-isoascorbic acid (add origin, 15 g dissolved in 40 mL deionised water) was added dropwise over 15 minutes and stirring was continued at 30° C., 300 rpm for 20 minutes after addition. This treatment level corresponds to approx. 0.36 mg/m.sup.2. Subsequently, the mixture was taken out of the mixer. A yellow/beige powder was collected (Powder 9).

2.3 Surface Treatments with Gallic Acid

2.3.1 Example 10—Powder 10

(46) 400 g of dry surface-reacted calcium carbonate (d.sub.50=2.4 μm, BET specific surface area=37 m.sup.2/g) was placed in a Lödige mixer (M5 R-MK, Gebrüder Lödige Maschinenbau GmbH, Germany) and heated to 100° C. Stirring was activated and 10 parts relative to 100 parts surface-reacted calcium carbonate of gallic acid (40 g dissolved in 160 g ethanol) was added dropwise with a peristaltic pump (addition time: approx. 1 h) and stirring was continued at 100° C. for 1 h after addition. This treatment level corresponds to approx. 2.70 mg/m.sup.2. Subsequently, the mixture was taken out of the mixer and further dried in the oven (60° C., <20 mbar) for 1 h. A grey powder was collected (Powder 10).

2.4 Surface Treatments with Iron

2.4.1 Example 11—Powder 11

(47) 420 g of dry surface-reacted calcium carbonate (d.sub.50=2.4 μm, BET specific surface area=37 m.sup.2/g) was placed in a Lödige mixer (M5 R-MK, Gebrüder Lödige Maschinenbau GmbH, Germany) at room temperature. Stirring was activated and 4.8 parts relative to 100 parts surface-reacted calcium carbonate of iron sulphate heptahydrate (Sigma Aldrich, India, 90 g of a previously prepared 22.3 wt.-% aqueous solution) was added dropwise with a peristaltic pump (addition time: approx. 1 hour) and stirring was continued at room temperature for 20 minutes after addition. This treatment level corresponds to approx. 1.30 mg/m.sup.2. Subsequently, the mixture was taken out of the mixer. A beige/brown powder was collected (Powder 11).

2.4.2 Example 12—Powder 12

(48) 300 g of dry surface-reacted calcium carbonate (d.sub.50=2.4 μm, BET specific surface area=37 m.sup.2/g) was placed in a Somakon mixer (Somakon Verfahrenstechnik UG, Germany) and conditioned by heating to 120° C. for 10 minutes (500 rpm). Then, 5 parts relative to 100 parts surface-reacted calcium carbonate of citric acid (Sigma-Aldrich, 15 g dissolved in 20 mL deionised water) was added dropwise and stirring was continued at 120° C., 500 rpm for 20 minutes after addition and immediately cooled down to 40° C.

(49) In a second step, 3 parts relative to 100 parts surface-reacted calcium carbonate of iron nanopowder was added in portions (9 g, 60-80 nm particle size, Aldrich (China)), and stirring was continued for 20 minutes (40° C., 500 rpm). This treatment level corresponds to approx. 0.81 mg/m.sup.2. Subsequently, the mixture was taken out of the mixer. A grey powder was collected (Powder 12).

2.5 Comparative Examples

2.5.1 Comparative Example 1—Powder CE1

(50) Powder CE1 is untreated surface-reacted calcium carbonate (d.sub.50=2.4 μm, BET specific surface area=37 m.sup.2/g, intra-particle intruded specific pore volume=0.281 cm.sup.3/g, humidity=1.58 wt.-%).

2.5.2 Comparative Example 2—CE2

(51) Powder CE2 is commercially available linoleic acid (Sigma-Aldrich (Germany), technical grade 60-74%)

2.5.3 Comparative Example 3—CE3

(52) CE3 is commercially available oleic acid (Fluka (Belgium))

2.5.4 Comparative Example 4—Powder CE4

(53) Powder CE4 is commercially available (L)-Ascorbic acid crystalline powder (Sigma life science, reagent grade, China)

2.5.1 Comparative Example 5—Powder CE5

(54) Powder CE5 is an untreated surface-reacted calcium carbonate (d.sub.50=4.5 μm, BET specific surface area=139 m.sup.2/g, intra-particle intruded specific pore volume=0.864 cm.sup.3/g, humidity=6.77 wt.-%).

(55) Table 1 summarizes the prepared surface-reacted calcium carbonates.

(56) TABLE-US-00001 TABLE 1 Overview of prepared surface-reacted calcium carbonates Additive (parts) BET specific (L- Iron CaCO.sub.3 surface CaCO.sub.3 Linoleic Oleic ascorbic Isoascorbic sulphate Example (parts) (m.sup.2/g) acid acid acid) acid Iron (nano) pentahydrate 1 100 37 0.6 — — — — 2 100 37 1 — — — — — 3 100 37 3 — — — — — 4 100 37 —  3 — — — — 5 100 37 — 10 — — — — 6 100 37 — 20 — — — — 7 100 Slurry with powder 4 8 100 37 — —  10 — — — 9 100 139 — — 5 — — 10 100 37 10 parts gallic acid 11 100 37 — — — — — 4.8 12 100 37 — — — — 3 (+5 citric — acid) CE1 100 37 — — — — — — CE2 — — 100 — — — — — CE3 — — — 100  — — — — CE4 — — — 100 — — — CE5 100 139 — — — — — —

(57) Table 2 shows the results of several treated surface-reacted calcium carbonates with regard to the moisture pick-up susceptibility.

(58) TABLE-US-00002 TABLE 2 Water pick-up susceptibility Example Water pick-up (mg/g) CE1 22.5 CE5 69.7 2 14.5 3 11.5 5 6.2 6 6.2 8 32.7
3 Coating Colours Preparation and Paper Coating

Examples 13 (E13)

(59) Coating colour containing 100 parts of CaCO.sub.3 (w/w) and 6 parts (dry/dry) of a synthetic binder based on styrene-butadiene copolymers (Styronal D628 (BASF, Germany)) was then prepared with the slurry according to example 7 and coated on both sides of superYUPO® foils from Fischer Papier AG, Switzerland (thickness 80 μm, size: 18×26 cm.sup.2, 62 g/m.sup.2, polypropylene) and dried on a belt-drier (150° C.). After coating, the sheets were immediately stored in a closed plastic bag to limit oxygen exposure until use. The composition of the coating colours and coating weights are summarized in Table 3 below.

(60) TABLE-US-00003 TABLE 3 Coating colour preparation and coating weight Coating colour composition Solids Coating CaCO.sub.3 Styronal D628 content weight Example Slurry [parts] [parts, dry/dry] [wt.-%] [g/m.sup.2] E13 E7 100 6 48.8 68.9
4 Oxygen Scavenging Tests

4.1 Tests on Powders

(61) Oxygen-scavenging tests were performed by placing a defined amount of powder in a well closed desiccator equipped with an oxygen measuring device (GOX 100, GHM Messtechnik GmbH, Germany). The relative amount of oxygen in air is regularly recorded and the total amount of oxygen scavenged by gram of sample estimated, assuming the gas respect the ideal gas law, and neglecting the volume occupied by the powder. Results are expressed as mL O.sub.2/g of powder.

4.1.1 Example 14

(62) 500 g of the powder from Example 1 were placed in a closed desiccator having a volume of approx. 7 L, and O.sub.2 amount was recorded regularly. This treatment level corresponds to approx. 0.16 mg/m.sup.2. The results of the oxygen scavenging test are summarized in Table 4 below.

(63) TABLE-US-00004 TABLE 4 Oxygen scavenging test Time [h] 0 2.6 4 22 24 28 45 51 68 78 90 O.sub.2 [%] in 20.9 20.9 20.8 20.6 20.5 20.2 20.1 19.9 19.7 19.2 19.2 desiccator O.sub.2 scavenged 0 0 0.014 0.042 0.056 0.098 0.112 0.14 0.168 0.238 0.238 (mL/g powder) O.sub.2 scavenged 0 0 2.35 7.05 9.40 16.4 18.8 23.49 28.2 39.9 39.9 (mL/g linoleic acid

(64) The results of Example 14 are also shown in FIGS. 1 and 2.

4.1.2 Example 15

(65) 500 g of the powder from Example 2 were placed in a closed desiccator having a volume of approx. 7 L, and O.sub.2 amount was recorded regularly. This treatment level corresponds to approx. 0.27 mg/m.sup.2. The results of the oxygen scavenging test are summarized in Table 5 below.

(66) TABLE-US-00005 TABLE 5 Oxygen scavenging test Time [h] 0 1.5 3.6 6.75 22 27 31.5 46.5 50 55 119 O.sub.2 [%] in 20.9 20.8 20.7 20.6 20.1 19.8 19.1 18.9 18.7 18.4 17.5 desiccator O.sub.2 scavenged 0 0.014 0.028 0.042 0.112 0.154 0.252 0.28 0.308 0.35 0.476 (mL/g powder) O.sub.2 scavenged 0 1.41 2.83 4.24 11.3 15.6 25.5 28.28 31.1 35.4 48.1 (mL/g linoleic acid

(67) The results of Example 15 are also shown in FIGS. 1 and 2.

4.1.3 Example 16

(68) 500 g of the powder from Example 3 were placed in a closed desiccator having a volume of approx. 7 L, and O.sub.2 amount was recorded regularly. This treatment level corresponds to approx. 0.81 mg/m.sup.2. The results of the oxygen scavenging test are summarized in Table 6 below.

(69) TABLE-US-00006 TABLE 6 Oxygen scavenging test Time [h] 0 1 15 18 21.5 24 38 44 47 109 113 161 O.sub.2 [%] in 20.9 20.6 18.7 18.1 17.3 16.4 12.9 11.8 10.9 5 4.8 4.6 desiccator O.sub.2 scavenged 0 0.042 0.308 0.392 0.504 0.63 1.12 1.274 1.4 2.23 2.25 2.28 (mL/g powder) O.sub.2 scavenged 0 1.44 10.6 13.5 17.3 21.6 38.5 43.8 48.1 76.4 77.4 78.4 (mL/g linoleic acid

(70) The results of Example 16 are also shown in FIGS. 1 and 2.

4.1.4 Example 17

(71) 500 g of the powder from Example 4 were placed in a closed desiccator having a volume of approx. 7 L, and O.sub.2 amount was recorded regularly. This treatment level corresponds to approx. 0.81 mg/m.sup.2. The results of the oxygen scavenging test are summarized in Table 7 below.

(72) TABLE-US-00007 TABLE 7 Oxygen scavenging test Time [h] 0 1.5 3.5 6 20 27 29 46 54 69 73 O.sub.2 [%] in 20.9 20.6 20.4 20.1 19.7 19.2 18.9 18.2 17.7 17.2 17 desiccator O.sub.2 scavenged 0 0.042 0.07 0.112 0.168 0.238 0.28 0.378 0.448 0.518 0.546 (mL/g powder) O.sub.2 scavenged 0 1.44 2.40 3.85 5.77 8.17 9.62 13.0 15.4 17.8 18.8 (mL/g oleic acid) Time [h] 77 100 166 172 190 194 210 216 237 261 325 O.sub.2 [%] in 16.7 15.4 11.6 11 9.9 9.5 8.4 7.6 6.1 4.1 2.1 desiccator O.sub.2 scavenged 0.588 0.77 1.30 1.39 1.54 1.60 1.75 1.86 2.07 2.35 2.63 (mL/g powder) O.sub.2 scavenged 20.2 26.4 44.7 47.6 52.9 54.8 60.1 63.9 71.2 80.8 90.4 (mL/g oleic acid)

(73) The results of Example 17 are also shown in FIGS. 3 and 4.

4.1.5 Example 18

(74) 110 g of the powder from Example 5 were placed in a closed desiccator having a volume of approx. 7 L, and O.sub.2 amount was recorded regularly. This treatment level corresponds to approx. 2.70 mg/m.sup.2. The results of the oxygen scavenging test are summarized in Table 8 below.

(75) TABLE-US-00008 TABLE 8 Oxygen scavenging test Time [h] 0 17 21 40 48 64 72 88 96 160 184 192 O.sub.2 [%] in 20.9 20.7 20.5 19.7 19.2 18.7 18.3 17.8 17.5 15.9 15.5 15.2 desiccator O.sub.2 0 0.127 0.255 0.764 1.08 1.4 1.66 1.97 2.16 3.18 3.44 3.63 scavenged (mL/g powder) O.sub.2 0 1.4 2.8 8.4 11.9 15.4 18.2 21.7 23.8 35 37.8 39.9 scavenged (mL/g oleic acid) Time [h] 208 240 264 328 352 376 392 424 488 496 520 544 O.sub.2 [%] in 15 14.4 14.1 13.4 13 12.6 12.2 11.7 11.3 11 10.8 10.5 desiccator O.sub.2 3.76 4.14 4.33 4.77 5.03 5.28 5.54 5.86 6.11 6.3 6.43 6.62 scavenged (mL/g powder) O.sub.2 41.3 45.5 47.6 52.5 55.3 58.1 60.9 64.4 67.2 69.3 70.7 72.8 scavenged (mL/g oleic acid) Time [h] 688 1000 1048 1144 1240 1288 1360 1384 1408 1456 1528 1576 O.sub.2 [%] in 9.6 7.9 7.5 7.3 6.7 6.4 6.3 6.1 5.9 5.9 5.9 5.9 desiccator O.sub.2 7.19 8.27 8.53 8.66 9.04 9.23 9.29 9.42 9.55 9.55 9.55 9.55 scavenged (mL/g powder) O.sub.2 79.1 91 93.8 95.2 99.4 102 102 104 105 105 105 105 scavenged (mL/g oleic acid)

(76) The results of Example 18 are also shown in FIGS. 3 and 4.

4.1.6 Example 19

(77) 35 g of the powder from Example 6 were placed in a closed desiccator having a volume of approx. 7 L, and O.sub.2 amount was recorded regularly. This treatment level corresponds to approx. 5.41 mg/m.sup.2. The results of the oxygen scavenging test are summarized in Table 9 below.

(78) TABLE-US-00009 TABLE 9 Oxygen scavenging test Time [h] 0 3 24 32 48 56 72 176 234 242 258 266 O.sub.2 [%] in 20.9 20.6 20.4 20.2 20 19.8 19.6 18.8 18.7 18.4 18.3 18.2 desiccator O.sub.2 scavenged 0 0.6 1 1.4 1.8 2.2 2.6 4.2 4.4 5 5.2 5.4 (mL/g powder) O.sub.2 scavenged 0 3.60 6.00 8.40 10.8 13.2 15.6 25.2 26.4 30.0 31.2 32.4 (mL/g oleic acid) Time [h] 330 354 378 426 526 550 574 670 694 742 766 840 O.sub.2 [%] in 17.6 17.4 17.1 17 16.8 16.7 16.6 16 15.9 15.6 15.4 14.9 desiccator O.sub.2 scavenged 6.6 7 7.6 7.8 8.2 8.4 8.6 9.8 10 10.6 11 12 (mL/g powder) O.sub.2 scavenged 39.6 42.0 45.6 46.8 49.2 50.4 51.6 58.8 60.0 63.6 66.0 72.0 (mL/g oleic acid) Time [h] 916 984 1028 1076 1148 1192 1336 1408 1480 1600 1624 1888 O.sub.2 [%] in 14.8 14.1 13.6 13.5 13.2 12.8 12.7 12.3 12.2 12 12 12.1 desiccator O.sub.2 scavenged 12.2 13.6 14.6 14.8 15.4 16.2 16.4 17.2 17.4 17.8 17.8 17.6 (mL/g powder) O.sub.2 scavenged 73.2 81.7 87.7 88.9 92.5 97.3 98.5 103 105 107 107 106 (mL/g oleic acid)

(79) The results of Example 19 are also shown in FIGS. 3 and 4.

4.1.7—Example 20

(80) 200 g of the powder from Example 10 were placed in a closed desiccator having a volume of approx. 2.9 L, and O.sub.2 amount was recorded regularly. This treatment level corresponds to approx. 2.70 mg/m.sup.2. The results of the oxygen scavenging test are summarized in Table 10 below.

(81) TABLE-US-00010 TABLE 10 Oxygen scavenging test Time [h] 0 2 4 16 24 32 48 54 126 150 174 O.sub.2 [%] in 20.9 20.7 20.6 19.5 19.1 18.7 18.4 18 17 16.7 16.6 desiccator O.sub.2 scavenged 0 0.029 0.043 0.203 0.261 0.319 0.363 0.421 0.566 0.609 0.624 (mL/g powder) O.sub.2 scavenged 0 0.3 0.5 2.2 2.9 3.5 4.0 4.6 6.2 6.7 6.9 (mL/g gallic acid) Time [h] 198 222 630 702 798 O.sub.2 [%] in 16.2 15.9 14 13.9 13.9 desiccator O.sub.2 scavenged 0.682 0.725 1.00 1.02 1.02 (mL/g powder) O.sub.2 scavenged 7.5 8.0 11.0 11.2 11.2 (mL/g gallic acid)

(82) The results of Example 20 are also shown in FIGS. 7 and 8.

4.1.8 Example 21

(83) 500 g of the powder from Example 8 were placed in a closed desiccator having a volume of approx. 2.9 L, and O.sub.2 amount was recorded regularly. This treatment level corresponds to approx. 2.70 mg/m.sup.2. The results of the oxygen scavenging test are summarized in Table 11 below.

(84) TABLE-US-00011 TABLE 11 Oxygen scavenging test Time [h] 0 1 2 18 23 26 42 50 114 122 146 O.sub.2 [%] in 20.9 20.5 20.3 17 16 15.5 13.2 12.3 7.9 7.2 6.1 desiccator O.sub.2 0 0.116 0.174 1.13 1.42 1.57 2.23 2.49 3.77 3.97 4.29 scavenged (mL/g powder) O.sub.2 0 1.28 1.91 12.4 15.6 17.2 24.6 27.4 41.5 43.7 47.2 scavenged (mL/g ascorbic acid) Time [h] 170 194 314 626 O.sub.2 [%] in 5 4.6 2.1 0.7 desiccator O.sub.2 4.61 4.73 5.45 5.86 scavenged (mL/g powder) O.sub.2 50.7 52.0 60.0 64.4 scavenged (mL/g ascorbic acid)

(85) The results of Example 21 are also shown in FIGS. 5 and 6.

4.1.9 Example 22

(86) 200 g of the powder from Example 9 were placed in a closed desiccator having a volume of approx. 7 L, and O.sub.2 amount was recorded regularly. This treatment level corresponds to approx. 0.36 mg/m.sup.2. The results of the oxygen scavenging test are summarized in Table 12 below.

(87) TABLE-US-00012 TABLE 12 Oxygen scavenging test Time [h] 0 2 3 19 23 27 51 75 99 165 172 O.sub.2 [%] in 20.9 20 19.6 16.8 16.1 15.5 13.4 12.4 11.6 10.8 10.6 desiccator O.sub.2 scavenged 0 0.315 0.455 1.44 1.68 1.89 2.63 2.98 3.26 3.54 3.61 (mL/g powder) O.sub.2 scavenged 0 6.62 9.56 30.1 35.3 39.7 55.1 62.5 68.4 74.3 75.7 (mL/g isoascorbic acid) Time [h] 196 244 340 O.sub.2 [%] in 10.5 10.4 10.4 desiccator O.sub.2 scavenged 3.64 3.68 3.68 (mL/g powder) O.sub.2 scavenged 76.5 77.2 77.2 (mL/g isoascorbic acid)

(88) The results of Example 22 are also shown in FIGS. 5 and 6.

4.1.10 Example 23

(89) 100 g of the powder from Example 11 were placed in a sealed 7 L desiccator, and O.sub.2 amount was recorded regularly. This treatment level corresponds to approx. 1.30 mg/m.sup.2. The results of the oxygen scavenging test are summarized in Table 13 below.

(90) TABLE-US-00013 TABLE 13 Oxygen scavenging test Time [h] 0 1 3 24 28 72 96 168 O.sub.2 [%] in 20.9 20.7 20.6 20.4 20.4 20.2 20.2 20.1 desiccator O.sub.2 scavenged 0 0.14 0.21 0.35 0.35 0.49 0.49 0.56 (mL/g powder) O.sub.2 scavenged 0 3.06 4.59 7.64 7.64 10.7 10.7 12.2 (mL/g Iron sulphate pentahydrate)

(91) The results of Example 23 are also shown in FIG. 9.

4.1.11 Example 24

(92) 250 g of the powder from Example 12 were placed in a sealed 7 L desiccator, and O.sub.2 amount was recorded regularly. This treatment level corresponds to approx. 0.81 mg/m.sup.2. The results of the oxygen scavenging test are summarized in Table 14 below.

(93) TABLE-US-00014 TABLE 14 Oxygen scavenging test Time [h] 0 17 23 48 72 96 168 O.sub.2 [%] in 20.9 20.6 20.4 19.8 19.6 19.6 19.4 desiccator O.sub.2 0 0.084 0.14 0.308 0.364 0.364 0.42 scavenged (mL/g powder) O.sub.2 0 2.88 4.81 10.58 12.5 12.5 14.42 scavenged (mL/g Iron nanopowder)

(94) The results of Example 24 are also shown in FIG. 9.

4.1.10 Comparative Example 7

(95) 500 g of the powder from Comparative Example 1 were placed in a sealed 7 L desiccator, and O.sub.2 amount was recorded regularly. No noticeable change in O.sub.2 levels could be noticed after 2 weeks. The results of the oxygen scavenging test are summarized in Table 15 below.

(96) TABLE-US-00015 TABLE 15 Oxygen scavenging test Time [h] 0 1 3 48 72 144 188 260 O.sub.2 [%] in 20.9 20.9 20.9 20.8 20.8 20.9 20.9 20.9 desiccator O.sub.2 scavenged 0 0 0 0.01 0.01 0 0 0 (mL/g powder)

(97) The results of Comparative Example 7 are also shown in FIGS. 5 and 9.

4.1.11 Comparative Example 8

(98) 14.5 g of oleic acid (Comparative Example 3) were placed in a sealed 7 L desiccator, and O.sub.2 amount was recorded regularly. The results of the oxygen scavenging test are summarized in Table 16 below.

(99) TABLE-US-00016 TABLE 16 Oxygen scavenging test Time [h] 0 3 20 24 72 144 168 192 216 O.sub.2 [%] in 20.9 20.9 20.8 20.8 20.7 20.6 20.5 20.4 20.3 desiccator O.sub.2 scavenged 0 0 0.48 0.48 0.97 1.45 1.93 2.41 2.90 (mL/g oleic acid)

(100) The results of Comparative Example 8 are also shown in FIG. 4.

4.1.12 Comparative Example 9

(101) 14.5 g of linoleic acid (Comparative Example 2) were put in a 50 mL beaker and placed in a sealed 7 L desiccator, and O.sub.2 amount was recorded regularly. The results of the oxygen scavenging test are summarized in Table 17 below.

(102) TABLE-US-00017 TABLE 17 Oxygen scavenging test Time [h] 0 3 20 24 72 144 168 192 216 O.sub.2 [%] in 20.9 20.9 20.6 20.4 19.6 17.6 16.6 15.6 14.9 desiccator O.sub.2 scavenged 0 0 1.45 2.41 6.28 15.9 20.8 25.6 29.0 (mL/g linoleic acid)

(103) The results of Comparative Example 9 are also shown in FIG. 2.

4.1.13 Comparative Example 10

(104) 10 g of (L)-ascorbic acid crystalline powder (Sigma life science, reagent grade, China, powder from Comparative Example 4) were placed in a sealed 7 L desiccator, and O.sub.2 amount was recorded regularly. The results of the oxygen scavenging test are summarized in Table 18 below.

(105) TABLE-US-00018 TABLE 18 Oxygen scavenging test Time [h] 0 24 88 120 144 168 O.sub.2 [%] in desiccator 20.9 20.8 20.6 20.5 20.5 20.4 O.sub.2 scavenged (mL/g ascorbic 0 0.7 2.1 2.8 2.8 3.5 acid)

(106) The results of Comparative Example 10 are also shown in FIGS. 5 and 6.

4.1.14 Comparative Example 11

(107) 200 g of the powder from Comparative Example 5 were placed in a sealed 7 L desiccator, and O.sub.2 amount was recorded regularly. No noticeable change in O.sub.2 levels could be noticed after 2 weeks. The results of the oxygen scavenging test are summarized in Table 19 below.

(108) TABLE-US-00019 TABLE 19 Oxygen scavenging test Time [h] 0 3 23 51 75 99 165 196 244 340 364 O.sub.2 [%] in 20.9 20.9 20.9 20.8 20.8 20.8 20.9 20.8 20.8 20.9 20.9 desiccator O.sub.2 scavenged 0 0 0 0.04 0.04 0.04 0 0.04 0.04 0 0 (mL/g powder)

(109) The results of Comparative Example 11 are also shown in FIG. 5.

4.2 Tests on Coated Papers

4.2.1 Example 25: Paper from Example 13 (with Oleic Acid)

(110) 136 strips (5×18 cm.sup.2) of coated paper from Example 13 are cut in smaller pieces (each strip was cut in 4) and placed in a sealed 2.9 L desiccator, and O.sub.2 amount was recorded regularly. The estimated amount of coating (by weight) used for this test was 84 g. The results of the oxygen scavenging test are summarized in Table 20 below.

(111) TABLE-US-00020 TABLE 20 Oxygen scavenging test of the coated paper Time [h] 0 24 48 72 164 188 212 236 308 356 404 O.sub.2 [%] in 20.9 20.8 20.8 20.7 20.5 20.3 20.1 19.9 19.3 19.2 19.1 desiccator O.sub.2 scavenged 0 0.035 0.035 0.069 0.138 0.207 0.276 0.345 0.552 0.587 0.621 (mL/g coating) O.sub.2 scavenged 0 1.18 1.18 2.37 4.73 7.10 9.47 11.8 18.9 20.1 21.3 (mL/g active compound)

(112) The results of Example 25 are also shown in FIG. 10.

(113) All of the examples show that high O.sub.2 scavenging values can be achieved with the treated surface-reacted calcium carbonate. Thus, the reaction with O.sub.2 can be enhanced by using the treatment agent in combination with surface-reacted calcium carbonate, possibly through an increased available surface area. Furthermore, the scavenging speed can be increased by the using the treated surface-reacted calcium carbonate.