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US 5,853,472 AGranted
Transparent bismuth vanadate pigments
AssigneeCiba Specialty Chemicals Corporation
InventorsLeonardus Johannes Hubertus Erkens, Gregor Schmitt, Hendrikus Maria Anna Hamers, Johannes Maria Martinus Luijten, Jozef Gertruda Emanuel Mains
Life of this patent
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Abstract
Transparent bismuth vanadate pigments and a process for their preparation. Coating bismuth vanadate pigment precursors prepared by known methods with coating compositions conventionally used for coating pigments prior to the customary calcination gives bismuth vanadate pigments of high transparency.
Claims12
A process for the preparation of transparent bismuth vanadate pigments, which comprises
- a) preparing an amorphous pigment precursor by precipitation from an acid bismuth salt solution and a vanadate solution, which solutions may contain dissolved metal salts, metal oxides or nonmetal oxides,
- b) coating the amorphous pigment precursor so obtained with 1 to 50% by weight, based on the total amount, of an inorganic coating material and subsequently
- c) heat treating it in the temperature range from 50.degree. to 800.degree. C. then deagglomerating it.
A bismuth vanadate pigment of the general composition
- Bi.sub.2 O.sub.3 .times.V.sub.2 O.sub.5,
- wherein bismuth and vanadium may be partially replaced with other metals or nonmetals, which bismuth vanadate pigments have a transparency of .DELTA.L*>4 in an alkyd melamine paint application at a pigment content of 38% and at a layer thickness, dry, of 40 .mu.m.
Dependencies are inferred from the claim text.