Clay mineral giving specified particle size on stirring in water is used as a leather tanning agent, especially in combination with an organic tanning agent

摘要

Use is claimed as a tanning agent (or an intermediate for a tanning agent) of a clay mineral which, after 30 minutes intensive stirring in water at 50degreesC, gives a laser and light scattering-determined ISO 13320-1 number average particle diameter (D) below 2 mu or a bimodal distribution of (i) 10-90 wt.% of a fraction with D below 0.5 mu and (ii) a coarser fraction of D below 5 mu. An Independent claim is also included for a formulation for use in chromium-free or chrome tanning comprising (a) a clay mineral as above and (b) one or more of an organic polymer, an aldehyde-, sulfone- , resin-, phenol- or vegetable-tanning agent, dubbing material, dye or pigment.