Compositions: coating or plastic – Materials or ingredients – Pigment – filler – or aggregate compositions – e.g. – stone,...
Patent
1993-09-16
1995-03-21
Klemanski, Helene
Compositions: coating or plastic
Materials or ingredients
Pigment, filler, or aggregate compositions, e.g., stone,...
C09C 100, C01G 2900, C01G 3100
Patent
active
053991974
DESCRIPTION:
BRIEF SUMMARY
OBJECT OF THE INVENTION
The present invention refers to inorganic yellow pigments based on bismuth phosphovanadate and/or silicovanadate as well as processes of manufacturing and obtaining said pigments.
Ideally a yellow pigment must have the following characteristics: pigment, it must hold its own vivid color; dullness or greyness; object is exposed to light; object.
Moreover many applications require a great opacifying power of the pigment, that means the capacity of covering and opacifying efficiently the colored objects.
The main yellow pigments are lead chromates, cadmium sulfides, nickel titanates, hydrated iron oxides and various organic pigments principally based on dinitrogenated compounds.
The use of the lead chromates and cadmium sulfides is presently limited by their possible toxicity; nickel titanates and iron oxides are opaque, but are deficient either in coloring power or in color purity. The organic pigments they have generally a low covering power, are expensive to very expensive and bleed frequently. The bismuth vanadate-based pigments present a very pure color, great coloring power, a good opacity and no bleeding. The present invention has as an object to provide new pigments based on bismuth phosphovanadate and/or bismuth silicovanadate which have all characteristics and qualities of pure bismuth vanadate.
The present invention also refers to new manufacturing processes for bismuth vanadate compounds according to the present invention.
CHARACTERISTIC ELEMENTS OF THE INVENTION
The new yellow inorganic pigments based on bismuth phosphovanadate and/or silicovanadate according to the present invention are non toxic and have a good covering power, a good coloring power, a great color purity, a good light solidness and do not bleed in the environments where they are used. Those pigments have the following chemical formula:
L is Si or simultaneously Si and one or various elements chosen amongst Ti, Ge or Zr; or still simultaneously Si and one or various elements chosen amongst Ti, Ge or Zr and one or various elements of the group IIIa;
M is V or simultaneously V and one or various elements chosen amongst the group Vb or P;
N is Mo or W;
a varying from 1 to 4/3, and b, c and d varying from 0 to 1;
c is higher than 0, and
if b=0 then M must represent simultaneously V and one or various elements chosen amongst the group Vb or P.
The invention also refers to manufacturing processes for bismuth phosphovanadate and silicovanadate.
According to a preferred embodiment of the invention, a precipitation of a "raw product" in wet medium is firstly made, then this raw product is converted into a pigmentary powder through a calcination step in the ambient conditions. The precipitation of the raw product is made under well controlled conditions by mixing an acid solution of bismuth with an aqueous solution containing at least vanadate anions and silicate and/or phosphate anions and possibly molybdate and/or tungstate anions or titanium, germanium, zirconium, niobium, phosphorus, boron or aluminium compounds, preferably titanate, germanate, zirconate, niobate, phosphate, borate, aluminate or silicoborate in presence of a base and at a temperature between 20.degree. and 100.degree. C., preferably between 40.degree. and 80.degree. C. The precipited product is then separated from the mother-waters. These latter are in the case of the invention exempt of heavy metals and other ions such as Bi, Mo, P, Zn, . . . The precipitate is then washed and dried. It is calcinated during 0.5 to 5 hours at a temperature of 400.degree. to 700.degree. C.
Nevertheless further embodiments of the process of manufacturing the pigments according to the present invention can be possible. Particularly, solid compounds of bismuth and vanadium, silicon, phosphorus, molybdenum can be intimately mixed and the mixture can be then directly calcinated. The formation of the bismuth vanadate-based pigmentary compound is then carried out by chemical reaction in solid phase, as it is also done for the pigments of the rutile and spinelle fami
REFERENCES:
patent: 4026722 (1977-05-01), Hess
patent: 4455174 (1984-06-01), Wienand et al.
patent: 4851049 (1989-07-01), Wienand et al.
patent: 5186748 (1993-02-01), Erkens et al.
Buyse Emile J.
Vermoortele Frank
Colour Research Company (CORECO) Ltd.
Klemanski Helene
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