GB481748A - Method of reducing the corrosive effect of nitrogenous bases on metals - Google Patents

Abstract

To reduce or prevent the corrosive action of nitrogenous bases which normally have a corrosive action on iron, there is added an alkaline earth metal compound which is convertible by aqueous carbon dioxide into a water-insoluble carbonate. Examples of such metal compounds are water-soluble salts of alkaline earth metals with acetic, formic or other lower fatty acid, and alkaline earth hydroxides. Compositions and the use of compositions containing alkaline earth metal salts in concentrations above 2 per cent are disclaimed. The method may be applied in processes wherein cellulose esters are treated with aqueous solutions of organic bases to change their solubility properties, in processes for stabilizing and reducing the viscosity of nitrocellulose, in the treatment of cellulosic materials with organic bases to increase their affinity for dyestuffs, and in the saponifying of organic esters of cellulose. The metal with which the nitrogenous base comes into contact may be pretreated by heating with an aqueous solution of boric acid. The examples relate (1) to the treatment of regenerated cellulose artificial silk to increase the affinity for cotton dyes, and to the saponifying of cellulose ester materials, using a composition containing aqueous ethylene diamine and calcium acetate; (2) treatments as in (1) using calcium hydroxide in place of calcium acetate; (3) increasing the affinity of regenerated cellulose artificial silk for cotton dyes by treatment in an aqueous bath containing ethylene diamine and calcium hydroxide or calcium acetate; (4) reducing the acetyl content of cellulose acetate artificial silk using the bath in example (1); and (5) carrying out the process of (4) but using milk of lime instead of calcium acetate, and adding it during the process so as to maintain a slight excess of lime. Specifications 429,103, 453,302, and 479,341 are referred to.