Patent ID: 7753964

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