| 摘要 |
<p>1277420 Iron/manganese pigments UNITED KINGDOM ATOMIC ENERGY AUTHORITY 23 July 1969 [20 Aug 1968] 39748/68 Heading C4A Deep grey to black temperature-stable pigments are produced by adding an aqueous solution of iron and manganese salts to an aqueous solution of a base in the presence of a protective colloid, and filtering, washing and calcining the discrete particles formed. The iron salt may be ferric nitrate or chloride, or ferrous sulphate, and the manganese salt the nitrate or sulphate. Sodium or ammonium hydroxides are used, and the colloid may be dextran, starch, gelatine, a cellulose derivative, polyvinyl alcohol, an acrylic polymer or a mixture thereof. After drying below 100‹ C., and optionally denitrating, the gel particles are calcined at 750-850‹ C. The weight ratio Fe : Mn is usually 3-12 : 1, giving a colour variation of black to deep grey with decreasing Mn content. In Example 2 the product analyses 41À5% by wt. Fe, 12À7% Mn, 11% SO 4 and 6% Na.</p> |
