US 12,110,634 B2
Treated titanium dioxide pigment, process of making thereof and use thereof in paper manufacture
Robert McIntyre, Louth (GB); Julie Elizabeth Kerrod, Lincolnshire (GB); Ben Webber, Grimsby (GB); and Neil Burniston, Brigg (GB)
Assigned to Tronox LLC, Oklahoma City, OK (US)
Appl. No. 17/253,404
Filed by TRONOX LLC, Oklahoma City, OK (US)
PCT Filed Jun. 19, 2019, PCT No. PCT/US2019/037917
§ 371(c)(1), (2) Date Dec. 17, 2020,
PCT Pub. No. WO2019/246209, PCT Pub. Date Dec. 26, 2019.
Claims priority of provisional application 62/686,829, filed on Jun. 19, 2018.
Claims priority of provisional application 62/686,840, filed on Jun. 19, 2018.
Prior Publication US 2021/0262171 A1, Aug. 26, 2021
This patent is subject to a terminal disclaimer.
Int. Cl. D21H 21/28 (2006.01); C09C 1/36 (2006.01); C09C 3/06 (2006.01); D21H 17/00 (2006.01); D21H 17/67 (2006.01); D21H 17/69 (2006.01)
CPC D21H 21/285 (2013.01) [C09C 1/3661 (2013.01); C09C 3/063 (2013.01); D21H 17/675 (2013.01); D21H 17/69 (2013.01); D21H 17/73 (2013.01); C01P 2004/03 (2013.01); C01P 2004/04 (2013.01); C01P 2004/80 (2013.01); C01P 2004/84 (2013.01); C01P 2006/12 (2013.01)] 4 Claims
OG exemplary drawing
 
1. A process for the surface treatment of titanium dioxide pigments, comprising the steps in the following order:
(a) forming an aqueous suspension of titanium dioxide pigments;
(b) precipitating a layer of alumina phosphate on the surface of the pigments in said aqueous suspension formed in step (a) to form an aqueous suspension of titanium dioxide pigments having a layer of alumina phosphate precipitated on the surface of the pigments;
(c) precipitating a layer of alumina over the layer of alumina phosphate in said aqueous suspension formed in step (b) to form an aqueous suspension of titanium dioxide pigments having a layer of alumina phosphate precipitated on the surface of the pigments and a layer of alumina precipitated over the layer of alumina phosphate, wherein the precipitating of the layer of alumina over the layer of alumina phosphate comprises the following sub-steps in the following order:
(i) adding a first alumina source to said aqueous suspension formed in step (b) to form an aqueous suspension of titanium dioxide pigments having a layer of alumina phosphate precipitated on the surface of the pigments and alumina precipitated over the layer of alumina phosphate;
(ii) after sub-step (c)(i), allowing said aqueous suspension formed is sub-step (c)(1) to mature for a maturation time;
(iii) after sub-step (c)(ii), adding a second alumina source to said aqueous suspension formed in sub-step (c)(i) to form an aqueous suspension of titanium dioxide pigments having a layer of alumina phosphate precipitated on the surface of the pigments and additional alumina precipitated over the layer of alumina phosphate, wherein the second alumina source is different from the first alumina source;
(iv) after sub-step (c)(iii), allowing said aqueous suspension formed is sub-step (c)(iii) to mature for a maturation time;
(v) after sub-step (c)(iv), adding a third alumina source to said aqueous suspension formed in sub-step (c)(iii) to form an aqueous suspension of titanium dioxide pigments having a layer of alumina phosphate precipitated on the surface of the pigments and additional alumina precipitated over the layer of alumina phosphate; and
(vi) after sub-step (c)(v), allowing said aqueous suspension formed in sub-step (c)(v) to mature for a maturation time, wherein said maturation time associated with steps (c)(ii), (c)(iv) and (c)(vi) is from 1 minute to 30 minutes, and wherein the first alumina source, the second alumina source and the third alumina source are each selected from the alumina source group consisting of aluminum sulfate (Al2(SO4)3), sodium aluminate (NaAlO2), aluminum chloride (AlCl3) and combinations thereof; and
(d) after sub-step (c)(vi), recovering the titanium dioxide pigments from said aqueous suspension formed in step (c)(v).