Surface Treatment of Inorganic Pigments by Nε-Acyllysine

Inorganic pigments(calcium carbonate, iron oxide, and titanium dioxide) were treated with Ne-lauroyl-L-lysine, which is almost insoluble in both polar and nonpolar solvents. Two methods were employed for the treatment: (1) grinding of various weight proportional mixtures of pigment and the N-acyllysine; (2) adsorption of the N-acyllysine from its calcium ethylate solution on pigment. In method(1), the sufficient hydrophobic treatment was made when the weight percent of the N-acyllysine in the mixture was above about 30%. On the other hand, in method(2), although the amount adsorbed of the N-acyllysine was about in the range of 10−6 mol/g, the treated pigment showed a hydrophobicity. The critical surface tension of the treated samples estimated by using various mixtures of methanol and water was in the range from 23 to 39 dyn/cm.