GB790933A - Tanning, retanning and filling processes - Google Patents

Abstract

Water-soluble cationic resins suitable for making leather are prepared by condensing organic nitrogen compounds containing amino or imino groups with oxo compounds. Specifically mentioned nitrogen compounds are urea, thiourea, methylenediurea, cyanamide, guanidine, alkylguanidines, dicyandiamide, dicyandiamidine guanamine, ammeline, ammelide and melamine. Oxo compounds specified are formaldehyde, acetaldehyde (or corresponding aldehyde-yielding compounds) acrolein, furfural and methylethylketone. Increased cationic character can be given to resins obtained from said components by further condensation with e.g. polyamino compounds such as polyalkylenepolyamines, e.g. triethylenetetramine, tetraethylenepentamine, hydroxyalkylamines such as dimethylaminoethanol, diethylamine, oxazolidine, and polyphenyldiguanides. Examples refer to the use of a resin consisting of 0.5 mols. of dicyandiamide, 0.5 mols. of guanidine hydrochloride and 3 mols. of formaldehyde; of 1 mol. of melamine and 3 mols. of formaldehyde; of 1 mol. of dicyandiamide and 5 mols. of formaldehyde; and of 1 mol. of guanylurea hydrochloride and 5.3 mols. of formaldehyde. Insoluble, neutral, salt-like compounds of these condensation products are produced in the leather by previously or subsequently treating it with a solution of a salt (e.g. an alkali metal, ammonia or organic base salt) of a polymeric silicic, phosphoric, acrylic or methacrylic acid.