초록 ▼

The present invention relates to a process for the control of pitch in an aqueous medium by adding surface-reacted natural calcium carbonate or an aqueous suspension comprising surface-reacted calcium carbonate and having a pH greater than 6.0 measured at 20° C., to the medium, wherein the surface-r

The present invention relates to a process for the control of pitch in an aqueous medium by adding surface-reacted natural calcium carbonate or an aqueous suspension comprising surface-reacted calcium carbonate and having a pH greater than 6.0 measured at 20° C., to the medium, wherein the surface-reacted calcium carbonate is a reaction product of natural calcium carbonate with carbon dioxide and one or more acids, the use of the surface-reacted natural calcium carbonate for pitch control, as well as to a combination of a surface-reacted natural calcium carbonate and talc for pitch control, and the resulting composites.

대표청구항 ▼

1. A composition comprising surface-reacted natural calcium carbonate and pitch adsorbed thereon from an aqueous medium, wherein the composition is obtained by (a) contacting an aqueous medium containing pitch with (i) surface-reacted natural calcium carbonate or (ii) an aqueous suspension comprisin

1. A composition comprising surface-reacted natural calcium carbonate and pitch adsorbed thereon from an aqueous medium, wherein the composition is obtained by (a) contacting an aqueous medium containing pitch with (i) surface-reacted natural calcium carbonate or (ii) an aqueous suspension comprising surface-reacted natural calcium carbonate having a pH of greater than 6.0 measured at 20° C., wherein the surface-reacted natural calcium carbonate is a reaction product of natural calcium carbonate with carbon dioxide and one or more acids, and wherein the carbon dioxide is formed in situ by the acid treatment and/or is supplied from an external source; and (b) separating the composition from the aqueous medium. 2. The composition according to claim 1, wherein the surface-reacted natural calcium carbonate in (ii) is an aqueous suspension having a pH of greater than 6.5, measured at 20° C. 3. The composition according to claim 1, wherein the surface-reacted natural calcium carbonate in (ii) is an aqueous suspension having a pH of greater than 7.0, measured at 20° C. 4. The composition according to claim 1, wherein the surface-reacted natural calcium carbonate in (ii) is an aqueous suspension having a pH of greater than 7.5, measured at 20° C. 5. The composition according to claim 1, wherein the national calcium carbonate is marble, calcite, chalk and dolomite, limestone or mixtures thereof. 6. The composition according to claim 1, wherein the acid has a pKa at 25° C. of 2.5 or less. 7. The composition according to claim 6, wherein the acid is hydrochloric acid, sulphuric acid, sulphurous acid, hydrosulphate, phosphoric acid, oxalic acid or mixtures thereof. 8. The composition according to claim 6, wherein the acid is phosphoric acid. 9. The composition according to claim 1, wherein the natural calcium carbonate is reacted with the acid and/or the carbon dioxide in the presence of at least one silicate and/or silica, aluminium hydroxide, earth alkali metal aluminate, magnesium oxide, or mixtures thereof. 10. The composition according to claim 9, wherein the at least one silicate is aluminium silicate, calcium silicate or alkali metal silicate. 11. The composition according to claim 1, wherein the surface-reacted natural calcium carbonate has a specific surface area of from 5 m2/g to 200 m2/g, measured using nitrogen and the BET method according to ISO 9277. 12. The composition according to claim 1, wherein the surface-reacted natural calcium carbonate has a specific surface area of from 20 m2/g to 80 m2/g, measured using nitrogen and the BET method according to ISO 9277. 13. The composition according to claim 1, wherein the surface-reacted natural calcium carbonate has a specific surface area of from 30 m2/g to 60 m2/g, measured using nitrogen and the BET method according to ISO 9277. 14. The composition according to claim 1, wherein the surface-reacted natural calcium carbonate has a mean grain diameter d50 of from 0.1 to 50 μm, measured according to the sedimentation method. 15. The composition according to claim 1, wherein the surface-reacted natural calcium carbonate has a mean grain diameter d50 of from 0.5 to 25 μm, measured according to the sedimentation method. 16. The composition according to claim 1, wherein the surface-reacted natural calcium carbonate has a mean grain diameter d50 of from 0.8 to 20 μm, measured according to the sedimentation method. 17. The composition according to claim 1, wherein the surface-reacted natural calcium carbonate has a mean grain diameter d50 of from 1 to 10 μm, measured according to the sedimentation method. 18. The composition process according to claim 1, wherein the surface-reacted natural calcium carbonate has a mean grain diameter d50 of from 4 to 7 μm, measured according to the sedimentation method. 19. The composition according to claim 1, wherein the aqueous medium comprises mechanical pulp, ground wood, TMP (thermo mechanical pulp), chemithermo-mechanical pulp (CTMP), chemical pulp, kraft pulp, sulphate pulp, or recycled pulp used in the paper making process. 20. The composition according to claim 1, further comprising talc. 21. The composition according to claim 20, wherein the talc has a purity of >90 weight-%. 22. The composition according to claim 20, wherein the talc has a purity of >95 weight-%. 23. The composition according to claim 20, wherein the talc has a purity of >97 weight-%. 24. The composition according to claim 20, wherein the talc particles have a d50 value of 0.1 to 50 μm, measured according to the sedimentation method. 25. The composition according to claim 20, wherein the talc particles have a d50 value of 0.2 to 40 μm, measured according to the sedimentation method. 26. The composition according to claim 20, wherein the talc particles have a d50 value of 0.3 to 30 μm, measured according to the sedimentation method. 27. The composition according to claim 20, wherein the talc particles have a d50 value of 0.4 to 20 μm, measured according to the sedimentation method. 28. The composition according to claim 20, wherein the talc particles have a d50 value of 0.5 to 10 μm, measured according to the sedimentation method. 29. The composition according to claim 20, wherein the talc particles have a d50 value of 1, 7 or 7 μm, measured according to the sedimentation method. 30. The composition according to claim 20, wherein the talc has a specific surface area of between 3 and 100 g/m2. 31. The composition according to claim 20, wherein the talc has a specific surface area of between 7 and 80 g/m2. 32. The composition according to claim 20, wherein the talc has a specific surface area of between 9 and 60 g/m2. 33. The composition according to claim 20, wherein the talc has a specific surface area of between 10 and 50 g/m2. 34. The composition according to claim 20, wherein the talc has a specific surface area of 30 or 51 g/m2. 35. The composition according to claim 1, wherein the aqueous medium is brought into contact with the surface-reacted natural calcium carbonate by surface filtration, depth filtration and/or alluvium filtration. 36. The composition according to claim 1, wherein the composition is separated from the aqueous medium by sedimentation or filtration. 37. The composition according to claim 1, wherein the composition is separated from the aqueous medium by surface filtration, depth filtration and/or alluvium filtration. 38. The composition according to claim 1, wherein the aqueous medium is brought into contact with the surface-reacted natural calcium carbonate and the composition is separated from the aqueous medium by surface filtration, depth filtration and/or alluvium filtration.