Basf Aktiengesellschaft

Thorsten Raedler

Stephan Hueffer

Stefan Schroeder

Volker Bach

Tilman Luedecke Taeger

Karl Vill

Juergen Carle

Einhard Wagner

A formulation for use in chrome-free or chrome tanning is proposed, comprising a clay mineral which, after vigorous stirring for 30 minutes in water at 50&#xb0; C., has a number average particle diameter of less than 2 &#x3bc;m or a bimodal size distribution with a first, finely divided fraction whose number average particle diameter is less than 0.5 &#x3bc;m and a second, coarser fraction whose number average particle diameter is less than 5 &#x3bc;m, determined in each case by the method according to ISO 13320-1, by combined laser light diffraction and light scattering, the amount of the first, finely divided fraction being from 10 to 90% by weight, and one or more substances from one or more of the following groups: organic polymers, aldehyde tanning agents, sulfone tanning agents, resin tanning agents, phenol tanning agents, fatliquoring agents, vegetable tanning agents, dyes and pigments.

Formulation for use in chrome or chrome-free tannage

A semifinished leather product is produced from an animal hide by pretanning with the use of a chromium-free tanning agent and of a clay mineral which, after stirring for 30 minutes in water at 50&#xb0; C. at a circumferential rotor speed of from 5 to 25 m/s, has a number average particle diameter of less than 2 &#x3bc;m or a bimodal particle size distribution with a first, finely divided fraction whose number average particle diameter is less than 0.5 &#x3bc;m and a second, coarser fraction whose number average particle diameter is less than 5 &#x3bc;m, determined in each case by the method according to ISO 13320-1, by combined laser light diffraction and light scattering, a proportion of the first, finely divided fraction being from 10 to 90% by weight, and drying of the pretanned animal hide to a water content of from 5 to 45%, based on the total weight of the semifinished leather product.

Method for producing a leather semi-finished product

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Ludwigshafen, Germany

Thorsten Raedler