Method for the production of granules comprising surface-reacted calcium carbonate

Abstract

The present invention relates to a method for the production of granules comprising surface-reacted calcium carbonate, as well as to the granules obtained thereby and their use.

Claims

1. A method for the production of granules comprising surface-reacted calcium carbonate, the method comprising: a) providing surface-reacted calcium carbonate, wherein the surface-reacted calcium carbonate is a reaction product of natural ground or precipitated calcium carbonate with carbon dioxide and one or more H.sub.3O.sup.+ ion donors in an aqueous medium, 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 one or more active ingredient(s) in liquid form, c) saturating the surface-reacted calcium carbonate with the one or more active ingredient(s) in liquid form, d) providing one or more binder, and e) combining the saturated surface-reacted calcium carbonate obtained in step c) with the one or more binder of step d) under agitation in an agitation device, and wherein the granules comprising surface-reacted calcium carbonate obtained after step e) have a volume median particle size of from 0.1 to 6 mm determined by sieve fractioning.

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 intruded specific pore volume in the range from 0.1 to 2.3 cm.sup.3/g, calculated from mercury porosimetry measurement, and/or iv) a grain diameter d.sub.98 (vol) of from 2 to 150 μm.

4. The method according to claim 1, wherein in step b), the one or more active ingredient(s) is/are dissolved in a solvent selected from the group consisting of water, methanol, ethanol, n-butanol, isopropanol, n-propanol, acetone, dimethylsulphoxide, dimethylformamide, tetrahydro furane, vegetable oils and derivatives thereof, animal oils and the derivatives thereof, molten fats and waxes, and mixtures thereof.

5. The method according to claim 1, wherein in step b), the one or more active ingredient(s) is/are selected from the group consisting of fragrances, flavours, herbal extracts, fruit extracts, nutrients, trace minerals, repellents, food, cosmetics, sweeteners, flame retardants, enzymes, pesticides, fertilizers, preserving agents, antioxidants, reactive chemicals, pharmaceutically active agents or pharmaceutically inactive precursors thereof, and mixtures thereof.

6. The method according to claim 1, wherein the one or more binder of step d) is selected from the group consisting of synthetic polymers and natural binders and mixtures thereof.

7. The method according to claim 1, wherein the one or more binder of step d) is added in an amount of from 0.1 to 50 wt.-%, based on the total dry weight of surface-reacted calcium carbonate of step a).

8. The method according to claim 1, wherein in step e), the agitation device is selected from the group consisting of Eirich mixers, fluidized bed dryers/granulators, plate granulators, table granulators, drum granulators, disc granulators, dish granulators, ploughshare mixer, vertical or horizontal mixers, high or low shear mixer, high speed blenders and rapid mixer granulators.

9. The method according to claim 1, wherein in step e), the one or more binder is added to the agitation device simultaneously with or after the saturated surface-reacted calcium carbonate obtained in step c).

10. The method according to claim 1, wherein the method further comprises a step f) of adding further surface-reacted calcium carbonate or saturated surface-reacted calcium carbonate or mixtures thereof, and/or solvent, to the mixture obtained in step e) until an agglomeration of the particles is observed.

11. The method according to claim 10, wherein the further surface-reacted calcium carbonate or saturated surface-reacted calcium carbonate or mixtures thereof is added in an amount of from 1 to 30 wt, based on the total dry weight of the surface-reacted calcium carbonate provided in step a).

12. The method according to claim 10, wherein the method further comprises a step g) of removing the solvent from the mixture obtained in step c) and/or e) and/or f).

13. The method according to claim 12, wherein in step g), the solvent is removed by means of separating the solvent from the resulting granules.

14. The method according to claim 1, wherein the granules comprising surface-reacted calcium carbonate obtained after step e) have a specific surface area of from 10 to 180 m.sup.2/g, measured using nitrogen and the BET method according to ISO 9277.

15. Granules comprising surface-reacted calcium carbonate formed by the method according to claim 1.

16. A fragrance delivery system, flavour delivery system, nutraceutical delivery system, pesticide delivery system, preservation delivery system, antioxidant delivery system, crop protection delivery system, fertilization delivery system, a catalytic system, a shielding system for delicate molecules, a carrier system, a chemical delivery system or pharmaceutical delivery system comprising the granules of claim 15.

17. The method according to claim 10, wherein the granules comprising surface-reacted calcium carbonate obtained after steps e) and f) or step f) alone have a volume median particle size of from 0.1 to 6 mm, determined by sieve fractioning.

18. The method according to claim 12, wherein the granules comprising surface-reacted calcium carbonate obtained after steps e), f) and g) or steps e) and f) or steps f) and g) or step f) alone or step g) alone have a volume median particle size of from 0.1 to 6 mm, determined by sieve fractioning.

19. The method according to claim 1, wherein the granules comprising surface-reacted calcium carbonate obtained after step e) have a volume median particle size of from 0.2 to 4 mm, determined by sieve fractioning.

20. The method according to claim 1, wherein the granules comprising surface-reacted calcium carbonate obtained after step e) have a volume median particle size of from 0.2 to 0.6 mm, determined by sieve fractioning.

21. The method according to claim 1, wherein the granules comprising surface-reacted calcium carbonate obtained after step e) have a volume median particle size of from 0.6 to 2 mm, determined by sieve fractioning.

Description

DESCRIPTION OF THE FIGURES

(1) FIG. 1 shows SEM images of (E)-cinnamaldehyde loaded granules of different sieving fractions. A) 1-2 mm; B) 600 μm-1 mm; C) 300 μm-600 μm; D) <300 μm.

(2) FIG. 2 shows SEM images of eugenol loaded granules of different sieving fractions. A) 1-2 mm; B) 600 μm-1 mm; C) 300 μm-600 μm; D) <300 μm.

EXAMPLES

(3) 1, Measurement Methods

(4) The following measurement methods were used to evaluate the parameters given in the examples and claims.

(5) BET Specific Surface Area (SSA) of a Material

(6) The BET specific surface area was measured via the BET process according to ISO 9277 using nitrogen, following conditioning of the sample by heating at 250° C. for a period of 30 minutes. Prior to such measurements, the sample was filtered, rinsed and dried at 110° C. in an oven for at least 12 hours.

(7) Particle Size Distribution (Volume % Particles with a Diameter <X), d.sub.50 Value (Volume Median Grain Diameter) and d.sub.98 Value of a Particulate Material:

(8) Volume median grain diameter d.sub.50 was evaluated using a Malvern Mastersizer 2000 Laser Diffraction System. The d.sub.50 or d.sub.98 value, measured using a Malvern Mastersizer 2000 Laser Diffraction System, indicates a diameter value such that 50% or 98% by volume, respectively, of the particles have a diameter of less than this value. The raw data obtained by the measurement is analysed using the Mie theory, with a particle refractive index of 1.57 and an absorption index of 0.005.

(9) The weight median grain diameter is determined by the sedimentation method, which is an analysis of sedimentation behaviour in a gravimetric field. The measurement is made with a Sedigraph™ 5100 of Micromeritics Instrument Corporation. The method and the 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 stirrer and sonicated.

(10) A vibrating sieve tower was used to analyze the particle size distribution of the granules. Aliquots of 120 g of granules were put on steel wire screen (Retsch, Germany) with mesh sizes of 300 μm, 600 μm, 1 mm and 2 mm. The sieving tower was shaken for 3 minutes with 10 seconds interval at a shaking displacement of 1 mm.

(11) The processes and instruments are known to the skilled person and are commonly used to determine grain size of fillers and pigments.

(12) Intra-Particle Intruded Specific Pore Volume (in cm.sup.3/g)

(13) 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 μm (˜nm). 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, p 1753-1764.).

(14) The total pore volume seen in the cumulative intrusion data can be separated into two regions with the intrusion data from 214 μm down to about 1-4 μm showing the coarse packing of the sample between any agglomerate structures contributing strongly. Below these diameters lies the fine inter-particle packing of the particles themselves. If they also have intra-particle pores, then this region appears bi modal, and by taking the specific pore volume intruded by mercury into pores finer than the modal turning point, i.e. finer than the bi-modal point of inflection, we thus define the specific intra-particle pore volume. 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.

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

(16) 2. Material and Equipment

(17) 2.1. Equipment Lödige (Model L5, 51 Mixer)

(18) 2.2. Material

(19) Surface-Reacted Calcium Carbonate Surface-reacted calcium carbonate (SRCC) 1 (d.sub.50=6.6 μm, d.sub.98=13.7 μm, SSA=59.9 m.sup.2g.sup.−1) with an intra-particle intruded specific pore volume is 0.939 cm.sup.3/g (for the pore diameter range of 0.004 to 0.51 μm). SRCC 1 was obtained by preparing 350 litres of an aqueous suspension of ground calcium carbonate in a mixing vessel by adjusting the solids content of a ground limestone calcium carbonate from Omya SAS, Orgon having amass based median particle size of 1.3 μm, as determined by sedimentation, such that a solids content of 10 wt.-%, based on the total weight of the aqueous suspension, is obtained. Whilst mixing the slurry at a speed of 6.2 m/s, 11.2 kg phosphoric acid was added in form of an aqueous solution containing 30 wt.-% phosphoric acid to said suspension over a period of 20 minutes at a temperature of 70° C. After the addition of the acid, the slurry was stirred for additional 5 minutes, before removing it from the vessel and drying using a jet-dryer.

(20) Binder Locust beam gum from Ceratorin siliqua seeds from Sigma-Aldrich (Galactomannan polysaccharide; G0753; CAS number 9000-40-2; EC number 232-541-5) Pectin Citrus, Powder, CAS No. 9000-69-5, Alfa Aesar

(21) Active: Ingredient (AI) (E)-Cinnamaldehyde, ≥98%, FCC, FG, Sigma Aldrich, W228605, CAS No. 14371-10-9 Eugenol, ≥98%, FCC, FG, Sigma Aldrich, W246700, CAS No. 97-53-0, EC No. 202-589-1 Vanillin, FCC, CAS No. 121-33-5, Sigma Aldrich

(22) 3. Granulation Experiments

(23) Lödige Mixer Granulation

Examples 1 and 2 (Inventive)

(24) 300 g surface-reacted calcium carbonate SRCC 1 was saturated with either (E)-cinnamaldehyde (Example 1) or eugenol (Example 2) and added to the Lödige mixer. Subsequently, 2.5 g Locust beam gum was added, dry, and the combination was mixed for several minutes to ensure proper blending. Subsequently, using a spray bottle, tap water was added over time, while mixing the powder with both the blending element (speed varied between 500 rpm and the maximum speed 850 rpm) and the cutter until the material started to look a little clumpy. The sample was mixed a few more minutes until individual granules were formed. The respective amounts from SRCC, active ingredient, binder and water, as well as the blending speed, can be taken from Table 1.

(25) TABLE-US-00001 TABLE 1 Binder wt.-% Active on Blending Exam- SRCC Ingredient Binder Binder SRCC speed ple [g] (AI) [g] type 1 [rpm] 1 300 (E)- 2.5 Locust 0.8% 650-850 cinnamal- beam gum dehyde 2 300 eugenol 2.5 Locust 0.8% 650-850 beam gum

(26) A vibrating sieve tower was used to analyze the particle size distribution of the granules. The obtained granules were put on steel wire screens (Retsch, Germany) with mesh sizes of 300 μm, 600 μm, 1 mm and 2 mm. The sieving tower was shaken for 3 minutes with 10 seconds interval at a shaking displacement of 1 mm. The percentage of each fraction can be taken from Table 2. Example SEM images of the fractions can be observed in FIGS. 1 and 2.

(27) TABLE-US-00002 TABLE 2 wt.-% of Particle size x [mm] Example x < 0.3 0.3 < x < 0.6 0.6 < x < 1 1 < x < 2 x > 2 1 30.5 28.4 9.3 8.9 23.0 2 21.7 12.1 17.1 27.4 21.7

(28) The above examples clearly show that granules can be produced from surface-reacted calcium carbonate being loaded with an active ingredient with standard binding agents.

Examples 3, 4, 5 and 6 (Inventive)

(29) Loading

(30) A. SRCC 1 Loaded with 30 wt.-% Vanillin

(31) 550 g surface-reacted calcium carbonate SRCC 1 was loaded by spraying while mixing in the Lödige mixer at 100 rpm with 786 g of a solution of vanillin in ethanol absolute (concentration=0.338 g/ml, 236 g vanillin in 550 g ethanol-abs.) to obtain surface-reacted calcium carbonate SRCC 1 loaded with 30 wt.-% vanillin (Examples 3 and 4). The remaining ethanol was evaporated by mixing at room temperature.

(32) B. SRCC 1 Loaded with 10 wt.-% Vanillin

(33) 550 g surface-reacted calcium carbonate SRCC 1 was loaded by spraying while mixing in the Lödige mixer at 100 rpm with 336 g of a solution of vanillin in ethanol absolute (concentration=0.175 g/ml, 61 g vanillin in 275 g ethanol-abs.) to obtain surface-reacted calcium carbonate SRCC 1 loaded with 10 wt-% vanillin (Examples 5 and 6), The remaining ethanol was evaporated by mixing at room temperature.

(34) Granulation

(35) 300 g of the respective vanillin loaded surface-reacted calcium carbonate SRCC 1 was used for each of the following granulation experiments.

(36) Before adding the binder the surface-reacted calcium carbonate SRCC 1 loaded with 10 wt.-% vanillin (B) pores were saturated by spraying tap water on the mixing powder (ca. 60 g water). 2.5 g (Examples 3 and 5) or 6.0 g (Examples 4 and 6) Pectin Citrus were added, dry, to surface-reacted calcium carbonate SRCC 1 loaded with 30 wt.-% vanillin (A) or surface-reacted calcium carbonate SRCC 1 loaded with 10 wt.-% vanillin (B), and the combination was mixed for several minutes to ensure proper blending. Subsequently, using a spray bottle, tap water was added over time, while mixing the powder with both the blending element (speed varied between 500 rpm and the maximum speed 850 rpm) and the cutter until the material started to look a little clumpy. The sample was mixed a few more minutes until individual granules were formed. The granules were dried overnight at 60° C. The respective amounts from SRCC, active ingredient, binder and water, as well as the blending speed, can be taken from Table 3.

(37) TABLE-US-00003 TABLE 3 Amount of tap Binder Blending SRCC Active Binder water used Binder wt.-% on speed Example [g] Ingredient (AI) [g] [g] type SRCC 1 [rpm] 3 300 vanillin 2.5 273.4 Pectin 0.8% 500 (30 wt.-%) Citrus 4 300 vanillin 6.0 253.4 Pectin 1.92% 500 (30 wt.-%) Citrus 5 300 vanillin 2.5 269.9 Pectin 0.8% 500 (10 wt.-%) Citrus 6 300 vanillin 6.0 276.0 Pectin 1.92% 500 (10 wt.-%) Citrus

(38) A vibrating sieve tower was used to analyze the particle size distribution of the granules. The obtained granules were put on steel wire screens (Retsch. Germany) with mesh sizes of 300 μm, 600 μm, 1 mm and 2 mm. The sieving tower was shaken for 3 minutes with 10 seconds interval at a shaking displacement of 1 mm. The percentage of each fraction can be taken from Table 4.

(39) TABLE-US-00004 TABLE 4 wt.-% of Particle size x [mm] Example x < 0.3 0.3 < x < 0.6 0.6 < x < 1 1 < x < 2 x > 2 3 4.1 5.7 12.7 55.4 22.1 4 3.9 10.4 22.2 48.6 14.9 5 0.7 0.2 0.2 1.0 97.9 6 4.1 30.1 22.1 27.3 16.4

(40) The above examples clearly show that granules can be produced from surface-reacted calcium carbonate being loaded with an active ingredient with standard binding agents.