Organic azo-pigment coated lithopone

Abstract

The invention relates to extended, organic pigments, their method of manufacture and their use in paint formulations, particularly those suitable for road or traffic markings. The subject pigments typically comprise a particulate lithopone core coated with a layer of an organic pigment. According to preferred embodiments, the pigment comprises an azo compound, the pigments are rosinated, and/or the core also contains a colorant or doping material, typically a metal oxide or metal salt. An exemplary method involves mixing particulate lithopone with a coupler such as acetoacet-o-anisidide. A coupler precipitator, typically an acidifier, is then added in an amount sufficient to precipitate the coupler onto the lithopone. The lithopone-bound coupler is then reacted with a diazonium ion in an azo-coupling reaction to form a pigment. The pigment-coated lithopone particles may then be heated and coated with a rosin or modified rosin soap.

Dependencies are inferred from the claim text.