High grade green chrome oxide pigments mfr. - by heating mixt. of sodium di:chromate and ammonium salt with addn. of water or sodium hydroxide soln.

摘要

In the parent patent, mfr. of chrome oxide pigments is carried out using a stoichiometric mixt. of (a) Na2Cr2O7, 2H2O of 2mm; with (b) (NH4)2SO4 or NH4Cl of 0.5mm; and opt. =10 wt. % of (in)organic modifiers. After dry mixng, the mixt. is heated in 15 minutes to 800-1100 degrees C. and held at this temp. to form the pigment, which is then sepd. from the salts. In the addition, 1-10 wt. % water is added to the mixt., based on the wt. of materials (a + b). Instead of water, 5-15% NaOH soln. may be used. High grade pigment is obtd.