Corrosion inhibiting pigment and a process for the manufacturing thereof
AssigneeColores Hispania, S.A.
InventorsJuan A. Vallvey, Oscar L. Francia, Carlos M. Sole
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Abstract
The pigment comprises a mixture of crystalline phase and an amorphous phase in which the crystalline phase represents from 10 to 70 wt % of the mixture and is constituted by zinc phosphate in the form of substantially spheroidal particles having a maximum size of between 0.5 to 5 microns and the amorphous phase represents from 30 to 90 wt % and comprises ferric phosphate and ferrous phosphate in a mole ratio lying between 1:001 and 1:03. The process comprises a reaction giving ferrous phosphate, partial oxidation thereof and association with zinc phosphate.
Claims13
A corrosion inhibiting pigment, characterised in that it comprises a mixture of a crystalline phase and an amorphous phase in which the crystalline phase represents from 10 to 70 wt % of the mixture and is constituted by zinc phosphate in the form of generally spheroidal particles having a maximum dimension lying between 0.5 and 5 microns and the amorphous phase represents correspondingly from 90 to 30 wt % and comprises ferric phosphate and ferrous phosphate in a mole ratio lying between 1:0.001 and 1:0.3.
A corrosion inhibiting primer comprising at least an organic binder and a pigment according to any one of the previous claims.
A process for the manufacture of a corrosion inhibiting pigment, formed by an association of a crystalline phase and an amorphous phase, in which the crystalline phase represents from 10 to 70 wt % of the association and is formed by zinc phosphate in the form of generally spheroidal particles having maximum dimensions lying between 0.5 and 5 microns and the amorphous phase represents from 30 to 90 wt % of the association and comprises ferric phosphate and ferrous phosphate in a mole ratio lying between 1:0.001 and 1:0.3, characterised in that it comprises the following steps, listed without implying any particular order of preference:
- (a) reacting a ferrous salt with a phosphate ion containing compound to give ferrous phosphate;
- (b) washing of said ferrous phosphate;
- (c) drying and oxidising of said ferrous phosphate to give an oxidation product maintaining a divalent iron content lying between 0.2 and 47 wt % of the total iron present in the oxidation product;
- and (d) associating with a crystalline phase constituted by zinc phosphate.
Dependencies are inferred from the claim text.