High-extraction chrome tanning process

US4919680A · kind A · utility

Assignee

• BAYER HEALTHCARE LLC · DE

Inventors

• Bernhard Wehling · Bensberg, DE
• Bernd Makowka · Bensberg, DE
• Heinz Klein · Bonn, DE
• Gertrud A. Klein · Kaarst, DE
• Helga Rosentreter · Leverkusen, DE

Key dates

• Filing date: Aug 11, 1988
• Grant date: Apr 24, 1990
• Expiry date: Aug 11, 2008

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C14C3/06
• WIPO field: Chemical engineering
• WIPO sector: Chemistry

Abstract

Crome tanning of pickled animal hides with a tanning agent comprising a reaction product of a basic chromium (III) sulfate and aliphatic C.sub.4 -C.sub.6 dicarboxylic acids or their salts is improved by preparing the reaction product in an aqueous solution from basic chromium (III) sulfate and 0.2 to 0.8 mol of the aliphatic dicarboxylic acids per mol chromium oxide of the basic chromium sulfate with subsequent adjustment of the theoretical basicity to 0 to 50% with alkali metal hydroxide or carbonate, the reaction product being added to a hide pickling liquor in the form of an aqueous solution having a chromium oxide content of at least 5% or in powder form in a quantity of 0.9 to 1.5% chromium oxide, based on hide weight, with a liquor volume less than 100%, based on hide weight, the final pH value being above 4.0 and the final temperature above 40.degree. C.