US 12,383,480 B2
Dyeing method for keratin fibers comprising a direct azo-dye and an organic alkalizing agent, and kit-of-parts thereof
Bernd Nöcker, Darmstadt (DE); Steven Breakspear, Darmstadt (DE); Fariba Ghiasi, Darmstadt (DE); and Anna Neu, Darmstadt (DE)
Assigned to KAO CORPORATION, Tokyo (JP)
Appl. No. 18/716,616
Filed by KAO CORPORATION, Tokyo (JP)
PCT Filed Dec. 20, 2022, PCT No. PCT/EP2022/086937
§ 371(c)(1), (2) Date Jun. 5, 2024,
PCT Pub. No. WO2023/118103, PCT Pub. Date Jun. 29, 2023.
Claims priority of application No. 21217424 (EP), filed on Dec. 23, 2021.
Prior Publication US 2025/0041181 A1, Feb. 6, 2025
Int. Cl. A61Q 5/10 (2006.01); A61K 8/41 (2006.01); A61K 8/49 (2006.01); A61Q 5/06 (2006.01)
CPC A61K 8/41 (2013.01) [A61K 8/494 (2013.01); A61Q 5/065 (2013.01); A61Q 5/10 (2013.01); A61K 2800/4322 (2013.01); A61K 2800/4324 (2013.01); A61K 2800/88 (2013.01)] 20 Claims
 
1. A method for dyeing keratin fibers, comprising:
mixing an aqueous dyeing composition comprising a dye compound which is an anionic azo dye, a non-ionic azo dye, a salt thereof, or a mixture thereof, and an alkalizing agent having at least one basic functional group whose conjugated acid has a pKa value in a range of 6.0 to 8.0 determined by acid-base titration in water of a 0.1 M solution of the alkalizing agent at 20° C. under atmospheric conditions, with a second aqueous composition having a pH in a range of 1 to 6 to yield a ready-to-use composition having a pH in a range of 7 to 12;
applying the ready-to-use composition onto the keratin fibers and leaving it for a time period in a range of 1 min to 60 min; and
rinsing-off the keratin fibers,
wherein the alkalizing agent is triethanolamine, 2-[4-(2-hydroxyethyl)-piperazin-1-yl]-ethane-1-sulfonic acid, a salt thereof, or a mixture thereof.