The invention relates to a poly silsesquioxane-acrylic nanocomposite auxiliary for leather process and its preparation method. By mixing octavinyl silsesquioxane, organic solvent, ammonium persulfate, distilled water and surfactant in one system, and adding acrylic acid dropwise into the mixing system, cooling to adjust pH to obtain poly silsesquioxane-acrylic nanocomposite auxiliary for leather process. The auxiliary obtained in this invention is easily to penetrate into gap of the collagen fibers, and forms nano and micro-scale combination with the leather collagen, which can further improve the multi-point combination of the acrylic polymer with the collagen. Thus, the filling property of the leather that treated by the auxiliary is improved without affect the yield of leather, and the chromium content in the waste water is significantly reduced.

A method for tanning an animal substrate comprising the steps: i) agitating the animal substrate with a chromium-free tanning agent; and ii) agitating the animal substrate with a tanning agent having an oxazolidine group; wherein at least some of the agitation is performed in the presence of a solid particulate material having an average particle size of from 1 to 500 mm.

A method for tanning an animal substrate comprising the steps: i) agitating the animal substrate with a chromium-free tanning agent; and ii) agitating the animal substrate with a tanning agent having an oxazolidine group; wherein at least some of the agitation is performed in the presence of a solid particulate material having an average particle size of from 1 to 500 mm.

A process for leather production from a raw animal hide includes the steps of pre-soaking, soaking, unhairing and liming, re-liming, deliming and bating, pickling and tanning, degreasing, re-tanning, neutralizing, dyeing and fatliquoring, and washing the processed hide. Waste liquid is collected from at least one of the foregoing steps is recycled to at least one of the foregoing steps. The collected waste liquid can be recycled to the same step, to a different step, or to two of more steps in the process.

A process for leather production from a raw animal hide includes the steps of pre-soaking, soaking, unhairing and liming, re-liming, deliming and bating, pickling and tanning, degreasing, re-tanning, neutralizing, dyeing and fatliquoring, and washing the processed hide. Waste liquid is collected from at least one of the foregoing steps is recycled to at least one of the foregoing steps. The collected waste liquid can be recycled to the same step, to a different step, or to two of more steps in the process.

A pelt processing system that comprises a tanning unit for tanning a pelt, which has been fixated to an expanded pelt board having a pelt board top, a pelt board bottom and a connecting element at the pelt board bottom. The pelt board is further operable between an expanded state and a non-expanded state by moving the connecting element relative to the pelt board bottom. A holding unit is provided for accommodating a plurality of the elongated hollow pelt boards. The holding unit defines a top plate having a number of apertures and each of the apertures are adapted for accommodating the connecting element. A blowing unit is further provided and is compatible with the holding unit and comprises a bottom plate, which is parallel to and spaced apart from the top plate. A gas inlet is provided for receiving a stream of gas, preferably air, and a sidewall for interconnecting with the top plate in a fluid-tight manner for establishing an inner space between the top plate, the bottom plate, the gas inlet and the sidewall. The system further comprises a release mechanism for causing the pelt boards on the holding unit to assume the non-expanded state. The invention further relates to a method of drying a pelt by employing the pelt processing system.

A method of synthesizing a resin including mixing a first solution including a melamine compound with a second solution including glutaraldehyde to form a third solution, heating the third solution to 35 C. to 90 C. in at a pH above 7 for 5 to 70 minutes, and cooling the third solution to room temperature.

A method of synthesizing a resin including mixing a first solution including a melamine compound with a second solution including glutaraldehyde to form a third solution, heating the third solution to 35 C. to 90 C. in at a pH above 7 for 5 to 70 minutes, and cooling the third solution to room temperature.

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.sup.3 (25? C.) and/or a bulk density of the dry powder of 0.005 to 0.06 g/cm.sup.3 (25? C.), c) drying, whereby the temperature of the leather during drying does not exceed 75? C. as well as to leather obtained by said process.

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.sup.3 (25? C.) and/or a bulk density of the dry powder of 0.005 to 0.06 g/cm.sup.3 (25? C.), c) drying, whereby the temperature of the leather during drying does not exceed 75? C. as well as to leather obtained by said process.