Abstract: The invention relates to microcapsules made of a core which contains at least one rubber additive and of a shell made of a first polymer. At least one coating made of a second polymer, which differs from the first polymer, and/or of a low molecular inorganic or organic compound, is deposited on the surface of the microcapsules as sliding or wearing layer in order to reduce the static friction.

Abstract: A tanning agent formulation obtained by reacting 1 mole of an aliphatic .omega.,.omega.'- dialdehyde having 2-8 carbon atoms in the form of an aqueous solution of about 3-60% strength with about 0.2-4 moles of a hydroxy compound of the formulaR.sub.1 --O--[(C.sub.2 H.sub.4 O).sub.x --(C.sub.3 H.sub.6 O).sub.y --(C.sub.4 H.sub.8 O).sub.z ].sub.n --Hwherebyn is an integer from 0 to 10,x+y+z is an integer from 1 to 20, wherein the alkoxy groups may be arranged in any order, andR.sub.1 is H, C.sub.1 -C.sub.12 alkyl, or C.sub.1 C.sub.12 alkylhaving one or more hydroxyl groups,wherein n is not 0 for R.sub.1 =His disclosed. Pelts pretanned with the formulation have improved mold resistance and are free of tanning metal salts and formaldehyde.

Abstract: A tanning agent formulation obtained by reacting 1 mole of an aliphatic .omega.,.omega.'-dialdehyde having 2-8 carbon atoms in the form of an aqueous solution of about 3-60% strength with about 0.2-4 moles of a hydroxy compound of the formulaR.sub.1 --O--[(C.sub.2 H.sub.4 O).sub.x --(C.sub.3 H.sub.6 O).sub.y --C.sub.4 H.sub.8 O).sub.z].sub.n --Hwherebyn is an integer from 0 to 10,x+y+z is an integer from 1 to 20, wherein the alkoxy groups may be arranged in any order, andR.sub.1 is H, C.sub.1 -C.sub.12 alkyl, or C.sub.1 C.sub.12 alkylhaving one or more hydroxyl groups,wherein n is not 0 for R.sub.1 .dbd.His disclosed. Pelts pretanned with the formulation have improved mold resistance and are free of tanning metal salts and formaldehyde.