Orthorhombic greenish-tinged lead chromate pigments
AssigneeCiba-Geigy Corporation
InventorsLeonardus J. H. Erkens, Herman J. J. M. Geurta, Jean L. G. M. Vandevenne, Gerben P. Algra
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Abstract
Orthorhombic greenish-tinged lead chromate pigments containing lead chromate and lead sulfate in a weight ratio of 91:9 to 100:0 and distinguished by a tinctorial strength of 0.053 to 0.066 at a standard depth of color of 1/25 in accordance with DIN 53235 are obtainable by mixing an aqueous solution of a lead salt with an aqueous solution of a chromate and, if necessary, of a sulfate under high turbulence in the presence of an aluminium salt and in the absence of zinc salts.
Claims13
An orthorhombic greenish-tinged lead chromate pigment containing lead chromate and lead sulfate in a weight ratio of 91:9 to 100:0, which has a tinctorial strength of 0.066 to 0.053 with a standard depth of color of 1/25 in accordance with DIN 53235 and is obtainable by mixing an aqueous solution of a lead salt with an aqueous solution of a chromate and, if necessary, of a sulfate under high turbulence in the presence of an aluminum salt and in the absence of zinc salts, by using an excess of lead ions of 0.003-0.12 mol per liter above the stoichiometric amount being present during or after the pigment is formed.
Dependencies are inferred from the claim text.