Process for the preparation of a treated mineral filler product, the obtained mineral filler product and its uses
The present invention relates to the domain of mineral filler treatment processes. The process for the preparation of a treated mineral filler product comprises the following steps: (a) treating at least one dry mineral filler with at least one Group II or Group III salt of a C8 to C24 aliphatic monocarboxylic acid to produce an intermediate mineral filler product; followed by (b) treating the intermediate mineral filler product of step (a) with at least one C8 to C24 aliphatic monocarboxylic acid to produce a treated mineral filler product. Applications in particular to prepare treated mineral filler products (such as Ca carbonate) to be used in plastic applications such as in polypropylene (PP)- or polyethylene (PE)-based breathable or extrusion coating film applications.
1. A process for the preparation of a treated mineral filler product comprising the following sequential steps:
(a) treating at least one dry mineral filler comprising calcium carbonate with calcium stearate under heat and mixing to obtain an intermediate mineral filler product comprising the at least one dry mineral filler coated with calcium stearate; and
(b) treating the intermediate mineral filler product obtained in step (a) with a 1:1 mixture of stearic acid and palmitic acid,
wherein the weight ratio of the mixture of stearic acid and palmitic acid to calcium stearate is 1:1.5 to 1:3,
wherein the total amount of the stearic acid, palmitic acid and calcium stearate is 1.0 to 1.6 wt. %, based on the dry weight of the mineral filler, and
wherein the treated mineral filler product has a total volatile content of less than 0.23% by mass at a temperature range of 25 and 300° C.
2. The process according to claim 1 , wherein the at least one dry mineral filler subjected to treatment in step (a) is precipitated calcium carbonate (PCC) and/or natural ground calcium carbonate (NGCC).
3. The process according to claim 1 , wherein the at least one dry mineral filler subjected to treatment in step (a) is precipitated calcium carbonate (PCC) of one or more of aragonitic, vateritic and calcitic mineralogical crystal forms.
4. The process according to claim 1 , wherein the at least one dry mineral filler subjected to treatment in step (a) is natural ground calcium carbonate (NGCC) prepared from marble, limestone, or chalk, and optionally comprising dolomite.
5. The process according to claim 1 , wherein the at least one dry mineral filler subjected to treatment in step (a) comprises marble and/or dolomite.
6. The process according to claim 1 , wherein the at least one dry mineral filler is dry or wet ground prior to treatment in step (a).
7. The process according to claim 1 , wherein the at least one dry mineral filler is subjected to benefication prior to treatment in step (a).
8. The process according to claim 1 , wherein the at least one dry mineral filler is subjected to classification prior to treatment in step (a).
9. The process according to claim 1 , wherein the at least one dry mineral filler subjected to treatment in step (a) has a d 50 of 0.5 to 10 microns.
10. The process according to claim 1 , wherein the at least one dry mineral filler subjected to treatment in step (a) has a d 50 of 1.5 to 1.8 microns.
11. The process according to claim 1 , wherein the at least one dry mineral filler subjected to treatment in step (a) has a d 98 of less than 25 microns.
12. The process according to claim 1 , wherein the at least one dry mineral filler subjected to treatment in step (a) has less than 0.2% by weight of water relative to mineral filler weight.
13. The process according to claim 1 , wherein the at least one dry mineral filler subjected to treatment in step (a) has from 0.1 to 0.2% by weight of water relative to mineral filler weight.
14. The process according to claim 1 , wherein the calcium stearate introduced in step (a) is in the form of a dry powder.
15. The process according to claim 1 , wherein the calcium stearate introduced in step (a) has a d 98 of 20 microns.
16. The process according to claim 1 , wherein the calcium stearate introduced in step (a) has a viscosity of more than 100,000 mPas.
17. The process according to claim 1 , wherein the calcium stearate employed in step (a) has a viscosity of more than 1,000,000 mPas.
18. The process according to claim 1 , wherein the mixture of stearic acid and palmitic acid introduced in step (b) is in the form of a melt.
19. The process according to claim 1 , wherein a total amount of the calcium stearate introduced in step (a) and the mixture of stearic acid and palmitic acid introduced in step (b) is 0.2 to 8 mg of total calcium stearate and mixture of stearic acid and palmitic acid per m 2 of mineral filler.
20. The process according to claim 1 , wherein a total amount of the calcium stearate introduced in step (a) and the mixture of stearic acid and palmitic acid introduced in step (b) is 0.6 to 5 mg of total calcium stearate and mixture of stearic acid and palmitic acid per m 2 of mineral filler.
21. The process according to claim 1 , wherein a total amount of the calcium stearate introduced in step (a) and the mixture of stearic acid and palmitic acid introduced in step (b) is 3 to 4 mg of total calcium stearate and mixture of stearic acid and palmitic acid per m 2 of mineral filler.
22. The process according to claim 1 , wherein 0.4 by weight % of the mixture of stearic acid and palmitic acid, based on the weight of the mineral filler, is introduced in step (b), and 0.6 to 1.2 by weight % of the calcium stearate, based on the weight of the mineral filler, is introduced in step (a).
23. The process according to claim 1 , wherein 0.4 by weight % of the mixture of stearic acid and palmitic acid, based on the weight of the mineral filler, is introduced in step (b), and 0.8 by weight % of the calcium stearate, based on the weight of the mineral filler, is introduced in step (a).
24. The process according to claim 1 , wherein the mixture of stearic acid and palmitic acid in step (b) and the calcium stearate in step (a) are introduced at a weight ratio of 1:2.
25. The process according to claim 1 , wherein an additional treatment agent that does not correspond to the mixture of stearic acid and palmitic acid, nor calcium stearate, is introduced during the process.
26. The process according to claim 25 , wherein the additional treatment agent is a siloxane.
27. The process according to claim 25 , wherein the additional treatment agent is a polydimethylsiloxane (PDMS).
28. The process according to claim 26 , wherein the siloxane is dosed at 200 to 1000 ppm.
29. The process according to claim 26 , wherein the siloxane is dosed at 400 to 600 ppm.
30. The process according to claim 26 , wherein the siloxane is dosed at 500 ppm.
31. The process according to claim 26 , wherein the siloxane is introduced following step (b).