| 摘要 |
<p>1,177,676. Zirconium praseodymium yellow pigments. FARBENFABRIKEN BAYER A.G. 2 March, 1967 [16 March, 1966], No. 9862/67. Heading C1M. A zirconium-praseodymium yellow pigment is produced by calcining at 850-1300‹ C. a mixture containing ZrO2, SiO2 and Pr6O11 prepared by converting ZrSiO4 above 800‹ C. with alkali in a molar ratio alkali metal : ZrSiO4 > 1 to non-refractory form, mixing the product with water, praseodymium oxide or a precursor thereof, and an inorganic acid in ratios water : ZrSiO4 > 5 : 1, praseodymium oxide : ZrSiO4 0À1-10% by weight, and 0À5 gm. equiv. acid per gm. atom alkali, and dehydrating the reaction product. Sodium or potassium fluoride or chloride, or zirconium oxyfluoride, may be added as mineralizer before calcination. Suitable alkalis are NaOH, KOH, NaHCO3, K2CO3, Li2CO3 or prefearbly Na2CO3, and the acid is preferably H2SO4. As a precursor for praseodymium oxide the oxalate, chloride, nitrate, sulphate, fluoride or carbonate may be used.</p> |
