GB469422A - Improvements in or relating to the preparation of pigments for enamels, laquers, inks and the like - Google Patents

Abstract

Pigmented base materials for the preparation of nitrocellulose and other cellulose derivative plastics, enamels, lacquers, &c., are obtained by grinding together in the presence of excess water nitrocellulose and a pigment both in the water-wet condition, simultaneously or subsequently incorporating an aqueous emulsion of an oil, which may be prepared in situ, the oil being incapable of colloiding the cellulose derivative, then breaking the emulsion, and finally separating the uncolloided but pigmented cellulose derivative from the aqueous medium. As an alternative to the oil emulsion there may be used an emulsion of an oil acid, a metal soap, a natural or synthetic resin, or a wax. Breaking of the emulsion may be effected by the addition of acid, or by selecting a pigment containing a sufficient proportion of salts. In examples, toluidine toner chrome yellow press cake, nitrocellulose and water are ground in a ball mill or by kneading or in a colloid mill, and the charge then transferred to an agitator and an aqueous emulsion of blown castor oil and triethanolamine oleate added, and later the emulsion is broken by the addition of citric acid; a similar process is employed starting with Chinese blue press cake, nitrocellulose and blown castor oil emulsion except that in this case a proportion of soya lecithin emulsion is also added; bone black, nitrocellulose and water are ground together and before adding the emulsion, in this case oleic acid emulsion, it is advantageous to wash the nitrocellulose slurry in order to remove a proportion of the salts contained in the pigment.