	US 11,851,722 B2
	Chromium tanning agents
Volker Rabe, Leverkusen (DE); Susanne Doeppert, Leverkusen (DE); and Juergen Reiners, Leverkusen (DE)
Assigned to TFL Ledertechnik GmbH, Rheinfelden (DE)
Appl. No. 16/962,484
Filed by TFL Ledertechnik GmbH, Rheinfelden (DE)
PCT Filed Jan. 11, 2019, PCT No. PCT/EP2019/050672 § 371(c)(1), (2) Date Dec. 14, 2020, PCT Pub. No. WO2019/141603, PCT Pub. Date Jul. 25, 2019.
Claims priority of application No. 18151874 (EP), filed on Jan. 16, 2018.
Prior Publication US 2021/0102267 A1, Apr. 8, 2021
Int. Cl. C14C 3/06 (2006.01)

CPC C14C 3/06 (2013.01)

20 Claims

1. Protein-masked chrome tanning agents comprising chromium in the oxidation state 3 and proteins obtained by basic hydrolysis of collagen, wherein the chrome tanning agents have a flocculation point in the range from 66 to 150% basicity, and the flocculation point is determined by preparing an aqueous solution of the chrome tanning agent containing 2.6 wt % of chromium oxide, calculated as Cr₂O₃, stirring the solution continuously at room temperature for 8 h and titrating it with 1.5 molar aqueous sodium carbonate solution until permanent flocculation is apparent.