Method of manufacture of tannin with titanium, tannin obtained by said process, with the use of said tannin for the tanning of the skins and hides treated by means of said tannin

摘要

The present invention relates to methods for preparing a titanium tanning agent from sulphuric-acid titanium-ferriferous solutions and use thereof for leather tanning. The method for preparing a titanium tanning agent from titanium-ferriferous sulphate solutions comprises introduction, into said solution, of an oxidizing agent comprising a sulphuric-acid solution of a peroxy-titanium complex, follows by the addition of ammonium sulphate and sulphuric acid to precipitate a double salt of titanyl and ammonium sulphate in the monohydrate form (NH4)2TiO(SO4)2.H2O. The precipitation of this salt is preferably effected prior to its formation in an amount of 75-85% based on TiO2. The resulting salt is separated and washed; the filtrate and washings are combined and treated with ammonium sulphate to afterprecipitate the salt which is separated and recycled into the starting solution. The thus-prepared salt is used for tanning hides pretreated with a tanning promotor: sodium salt of disulphodinaphthylmethane or phthalic anhydride, or aluminium alum, or a mixture of aluminium alum with urotropin; ammoniumtitanylsulphate or phenol oligomers dispersed in lignosulphonic acids. Tanning of delimed, or delimed and pickled, or delimed pickled and chromed hides is effected using the titanium tanning agent in the presence of lactic acid, aluminium alum or products of condensation of synthetic fatty acids with triethanolamine. The present invention is useful in the leather industry.