Tfl Ledertechnik Gmbh

Jens Fennen

Catherine Gabagnou

Grigore Daniel Herta

Nina Schulte

Campbell Thomas Page

Nina Schulte-Gauczinski

Eric Kientz

Florian Döppert

Jon Louis McHugh

Lorenzo Mejias

Rodolfo Ampuero

Andreas Lang

Wolfgang Herrmann

A composition including an acetal of an aldehydic tanning agent for tanning hides and/or pelts, as well as a method for tanning hides and/or pelts in order to produce leather, wherein an acetal of an aldehydic tanning agent is used. By reducing the pH, the aldehydic tanning agent can be released, whereby a tanning step is initiated. The composition according to the invention and the method according to the invention are characterized by lower toxicity compared to conventional compositions and tanning methods based on aldehydic tanning agents. Furthermore, improved penetration of the tanning agents into deeper layers of the hide and/or the pelt is possible, so that particularly homogeneous tanning is achieved.

Tanning composition and method based on an acetal of an aldehydic tanning agent

A composition including an acetal of an aldehydic tanning agent for tanning hides and/or pelts, as well as a method for tanning hides and/or pelts in order to produce leather, wherein an acetal of an aldehydic tanning agent is used. By reducing the pH, the aldehydic tanning agent can be released, whereby a tanning step is initiated. The composition and the method are characterized by lower toxicity compared to conventional compositions and tanning methods based on aldehydic tanning agents. Furthermore, improved penetration of the tanning agents into deeper layers of the hide and/or the pelt is possible, so that particularly homogeneous tanning is achieved.

The present invention is directed to a process for retanning leather comprising the steps of: a) providing tanned or pre-tanned leather b) treating the tanned leather of step a) with a composition comprising hollow microspheres, preferably as an aqueous composition, the hollow microspheres have a true density of from 0.01 to 0.10 g/cm(25&#xb0; C.) and/or a bulk density of the dry powder of 0.005 to 0.06 g/cm(25&#xb0; C.), c) drying, whereby the temperature of the leather during drying does not exceed 75&#xb0; C. as well as to leather obtained by said process.

Process for retanning leather

Tanned leather is (a) pretreated in an aqueous and alkaline medium either with ammonia, primary amines or a mixture of ammonia and primary amines and then with a polyfunctional organic compound containing at least one aldehyde group as a functional group, or (b) in an aqueous and acidic medium with a polyfunctional organic compound and then ammonia, primary amines or a mixture of ammonia and primary amines, and (c) then dyed in an aqueous and alkaline medium with a water-soluble dye containing at least one functional group which is capable of reacting with one of the functional groups of the organic compound, forming a covalent bond. A tanned and dyed leather is obtainable with a high color intensity, outstanding wet fastness and excellent grain tightness, wherein the dye is permanently and covalently bonded to the leather via a bridging group, preferably in the region of the surface, and the bridging group is essentially bonded to the leather via &#x2014;N&#x2550;CH&#x2014; groups.

Dyed leather and method for dyeing tanned leather

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Grenzach-Wyhlen, Germany

Jens Fennen