Use of a surface-reacted calcium carbonate in tissue paper, process to prepare a tissue paper product of improved softness, and resulting improved softness tissue paper products
The present invention relates to the use of a surface-reacted natural calcium carbonate as filler in tissue paper products, to a process to prepare tissue paper products, and to a tissue paper product featuring an improved softness, wherein said surface-reacted natural calcium carbonate is the reaction product of a natural calcium carbonate with an acid and carbon dioxide, which is formed in situ by the acid treatment and/or supplied externally.
1. A tissue paper product comprising surface-reacted calcium carbonate, wherein the surface-reacted calcium carbonate is formed by treating natural calcium carbonate with carbon dioxide and one or more acids, wherein the carbon dioxide is formed in situ by the acid treatment and/or is supplied from an external source, and wherein the tissue paper product is characterized as having a softness of less than 6.0 TSA.
2. The tissue paper product according to claim 1 , comprising from 2 to 20% by weight of surface-reacted calcium carbonate relative to the total tissue paper product weight.
3. The tissue product according to claim 1 , comprising from 3 to 15% by weight of surface-reacted calcium carbonate relative to the total tissue paper product weight.
4. The tissue paper product according to claim 1 , comprising a total mineral filler of from 1 to 50% by weight relative to the tissue paper product weight.
5. The tissue paper product according to claim 1 , comprising a total mineral filler of from 1 to 25% by weight relative to the tissue paper product weight.
6. The tissue paper product according to claim 1 , comprising a total mineral filler of from 1 to 15% by weight relative to the tissue paper product weight.
7. The tissue paper product according to claim 1 , characterized as having a basis weight per tissue paper ply of 5 to 50 g/m 2 .
8. The tissue paper product according to claim 1 , comprising from 1 to 3 tissue paper plies.
9. The tissue paper product according to claim 1 , characterized as having a softness of less than 5.5 TSA.
10. The tissue paper product according to claim 1 , characterized as having a softness of less than 3.5 TSA.
11. The tissue paper product according to claim 1 , characterized in having a softness that is at least 2 standard deviations less than the TSA value of an equivalent tissue paper product, wherein the surface-reacted calcium carbonate is replaced with a standard calcium carbonate featuring a mean diameter within 10% of the mean diameter of the surface-reacted calcium carbonate, and wherein the basis weight of the tissue paper product comprising the standard calcium carbonate is within 5% of the basis weight of the tissue paper product comprising the surface-reacted calcium carbonate.
12. The tissue paper product according to claim 1 , characterized in having a softness that is at least 2 standard deviations less than the TSA value of an equivalent tissue paper product which does not contain any filler, and wherein the basis weight of the filler-free tissue paper product is within 5% of the basis weight of the tissue paper product comprising the surface-reacted calcium carbonate.
13. The tissue paper product according to claim 1 , which is a facial tissue, a toilet tissue paper, decorative and/or gift wrapping tissue, a household and/or industrial tissue paper towel, a tissue paper napkin or a tissue paper cloth.
14. The tissue paper product according to claim 1 , wherein the surface-reacted calcium carbonate is prepared as an aqueous suspension having a pH of greater than 6.5 measured at 20° C.
15. The tissue paper product according to claim 1 , wherein the surface-reacted calcium carbonate is prepared as an aqueous suspension having a pH of greater than 7.0 measured at 20° C.
16. The tissue paper product according to claim 1 , wherein the surface-reacted calcium carbonate is prepared as an aqueous suspension having a pH of greater than 7.5 measured at 20° C.
17. The tissue paper product according to claim 1 , wherein the natural calcium carbonate is a marble, a calcite, a chalk, a dolomite, a limestone, or any mixtures thereof.
18. The tissue paper product according to claim 1 , wherein the acid has a pK a at 25° C. of 2.5 or less.
19. The tissue paper product according to claim 1 , wherein the acid has a pK a at 25° C. of 0 or less.
20. The tissue paper product according to claim 19 , wherein the acid is sulphuric acid, hydrochloric acid, or mixtures thereof.
21. The tissue paper product according to claim 1 , wherein the acid has a pK a at 25° C. of from 0 to 2.5.
22. The tissue paper product according to claim 21 , wherein the acid is H 2 SO 3 , HSO 4 − , H 3 PO 4 , oxalic acid, or any mixtures thereof.
23. The tissue paper product according to claim 1 , wherein the acid is phosphoric acid.
24. The tissue paper product according to claim 1 , wherein the molar ratio of the acid to the natural calcium carbonate is from 0.05 to 4.
25. The tissue paper product according to claim 1 , wherein the molar ratio of the acid to the natural calcium carbonate is from 0.1 to 2.