Transparent cobalt blue pigment prodn. - from cobalt and aluminium salt solns. by two=stage pptn. at controlled pH, for use in lacquers and plastics

摘要

In the prodn. of transparent cobalt blue (I) from a Co and an Al salt soln. by pptn. of Co hydroxide (IIA) or Co carbonate (IIB) with alkali or soda, a ppte. of Al hydroxide (IIIA) or Al carbonate (IIIB) is formed on the (II) suspension with pH is approx. 8 by simultaneous addn. of an Al salt soln. and an alkali or soda soln. (I) is used as pigment for transparent lacquers and plastics. These pigments extend the range of applications of (I) and also broaden the palette of transparent blue colours. They have better lightfastness, esp. in pale tones, then familiar transparent blue colours.