US 12,435,228 B2
Printing ink containing undried, coated titanium dioxide
Ingo Grosser, Hamburg (DE); Nicole Kolmer-Anderl, Langenfeld (DE); Annika Herbst, Düsseldorf (DE); and Simon Münzer, Langenfeld (DE)
Assigned to Kronos International, Inc., Leverkusen (DE)
Filed by KRONOS WORLDWIDE, INC., Dallas, TX (US)
Filed on Dec. 17, 2020, as Appl. No. 17/124,987.
Claims priority of provisional application 62/985,393, filed on Mar. 5, 2020.
Claims priority of application No. 19000569 (EP), filed on Dec. 18, 2019.
Prior Publication US 2021/0189161 A1, Jun. 24, 2021
Int. Cl. C09D 11/322 (2014.01); C09C 1/36 (2006.01); C09D 11/033 (2014.01); C09D 11/037 (2014.01)
CPC C09D 11/322 (2013.01) [C09C 1/3661 (2013.01); C09D 11/033 (2013.01); C09D 11/037 (2013.01); C01P 2004/84 (2013.01); C01P 2006/10 (2013.01)] 23 Claims
 
1. An aqueous printing ink comprising undried, coated titanium dioxide pigment particles obtained by a method comprising the steps of:
(i) providing an aqueous suspension of titanium dioxide base pigments,
(ii) forming at least one coat on said titanium dioxide base pigments, the coat is selected from the group consisting of a silica coat, an alumina coat, a zirconia coat and combinations thereof to obtain the undried, coated titanium dioxide pigment particles, wherein the step of forming at least one coat comprises forming a silica coat on the titanium dioxide base pigments, and subsequently forming an alumina coat on the titanium dioxide base pigments over the silica coat;
(iii) forming an aqueous printing ink comprising the undried coated titanium dioxide pigment particles formed in step (ii); and
wherein the coated titanium dioxide pigment particles are not subjected to a drying step having a temperature above 80° C. and have not had water removed until a constant weight was achieved;
wherein the printing ink further comprises:
12.0 to 25.0 wt. % of the titanium dioxide pigment particles with respect to the total weight of the printing ink;
at least one dispersant; and
wherein aqueous ink does not form a hard precipitate after 21 days at a temperature of 50° C.