CaZn.sub.2 (PO.sub.4).sub.2 .2H.sub.2 O anticorrosion pigment

Abstract

An anticorrosion pigment suited for paints and lacquers and consisting of CaZn.sub.2 (PO.sub.4).sub.2 . 2H.sub.2 O crystallizing in the Scholzite lattice and having a specific surface according to BET of from 0.1 to 50 m.sup.2 /g is produced by a process wherein (a) (i) a salt solution containing calcium and zinc cations in a ratio of about 1:2 is normally, inversely or simultaneously precipitated in air at temperatures of up to about 100.degree. C. with an equivalent or substantially equivalent quantity of a solution containing an alkali metal or ammonium phosphate ion; or (ii) compounds of calcium and zinc, which can be decomposed with relatively strong acids or neutralized with acids, in a ratio of about 1:2, have phosphoric acid or ammonium phosphate added to them in approximately the quantity which is required for decomposition or neutralization, or in a slight excess of that quantity, at temperatures of up to about 100.degree. C.; and (b) the suspension obtained in accordance with (a) (i) or (ii) is heated in air to a temperature of up to about 100.degree. C. or in an autoclave to a temperature of up to about 175.degree. C. over a period of up to about 10 hours, e.g. about 1 to 8 hours, the pigment suspension obtained is washed, filtered off and dried.

Dependencies are inferred from the claim text.