A method for forming chrome-free retanned leather including: (a) contacting wet white (chrome-free tanned hide) with a retanning mixture comprising from 2% to 15%, by solids weight, based on the wet weight of the wet white, of an amphoteric polymer composition comprising amine functional units and acid functional units; and (b) applying a polymeric overcoat containing an acrylic copolymer with one or more metal transition elements, with a thickness of no greater than 100 microns, to the retanned wet white, is provided. The present invention also provides a chrome-free retanned leather formed by the method.

A method for forming chrome-free retanned leather including: (a) contacting wet white (chrome-free tanned hide) with a retanning mixture comprising from 2% to 15%, by solids weight, based on the wet weight of the wet white, of an amphoteric polymer composition comprising amine functional units and acid functional units; and (b) applying a polymeric overcoat containing an acrylic copolymer with one or more metal transition elements, with a thickness of no greater than 100 microns, to the retanned wet white, is provided. The present invention also provides a chrome-free retanned leather formed by the method.

The invention discloses a method for treating an animal substrate comprising: agitating the moistened animal substrate with an aqueous treatment formulation and a solid particulate material in a sealed apparatus, wherein the aqueous treatment formulation comprises at least one colorant. There is also disclosed an animal substrate obtained by the method and finished leather goods obtained by the method.

The invention discloses a method for treating an animal substrate comprising: agitating the moistened animal substrate with an aqueous treatment formulation and a solid particulate material in a sealed apparatus, wherein the aqueous treatment formulation comprises at least one colorant. There is also disclosed an animal substrate obtained by the method and finished leather goods obtained by the method.

A recycling process for achieving near-zero emissions of tannery effluent is characterized in that effluent recycling is carried out independently in soaking, liming, re-liming, de-liming bating, pickling chrome tanning, re-tanning, neutralizing, and dyeing procedures. The effluents in the above procedures can be recycled in each step. This process greatly reduces effluent discharge and helps solve the problem of tanning pollution. The process also improves the quality of the finished leather, effectively decreases loose grain rate and increases compactness and fullness of the finished product. The project can reduce chemical material consumption by 15%-55%. For example, the consumption of chromium powder can be reduced up to 65%. Consumption of other chemical materials can be reduced by more than 90%, while certain chemical materials can be essentially completely conserved.

A recycling process for achieving near-zero emissions of tannery effluent is characterized in that effluent recycling is carried out independently in soaking, liming, re-liming, de-liming bating, pickling chrome tanning, re-tanning, neutralizing, and dyeing procedures. The effluents in the above procedures can be recycled in each step. This process greatly reduces effluent discharge and helps solve the problem of tanning pollution. The process also improves the quality of the finished leather, effectively decreases loose grain rate and increases compactness and fullness of the finished product. The project can reduce chemical material consumption by 15%-55%. For example, the consumption of chromium powder can be reduced up to 65%. Consumption of other chemical materials can be reduced by more than 90%, while certain chemical materials can be essentially completely conserved.

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 graft polymer of polysaccharides or polypeptides or its respective derivatives, obtainable by free radical polymerization of A) a monomer selected from or a monomer mixture of (a) from 20 to 100% by weight of acrylic acid or methacrylic acid or of a mixture thereof or of the alkali metal, alkaline earth metal or ammonium salts thereof, (b) from 0 to 80% by weight of other monoethylenically unsaturated monomers which are copolymerizable with the monomers (a) and (c) from 0 to 5% by weight of monomers having at least 2 ethylenically unsaturated, nonconjugated double bonds in the molecule, in the presence of either B1) polysaccharides, oxidatively, hydrolytically or enzymatically degraded polysaccharides, oxidized hydrolytically degraded or oxidized enzymatically degraded polysaccharides, or such chemically modified degraded products, chemically modified mono-, oligo-or poly-saccharides or mixtures of the stated compounds and/or B2) polypeptides, their hydrolysates or enzymaticallydegraded and optionally chemically modified products or mixtures of the stated compounds in a weight ratio A: (B1 or B2) of from 1:99 to 18:82 or in a weight ratio A:(B1+B2) of from 60:40 to 1:99 and B1:B2 of from 97:3 to 3:97 used as tanning agents.