The British Petroleum Company, P.l.c.

David A Pippard

Richard A Cayless

Corrosion inhibiting particles comprise an inorganic oxide which is silica or alumina, having corrosion inhibiting cations, particularly calcium or zinc cations, chemically bound to the particles. They may be prepared by contacting a silica or alumina containing hydroxyl groups with an alkaline solution containing the cations, at ambient temperature. The corrosion inhibiting particles may be incorporated into protective coatings, e.g. paints based on epoxy resins, alkyd resins, vinyl resins or chlorinated rubbers, in amounts up to 80% wt based on dry film weight, giving coatings with up to 7.2% wt corrosion inhibiting cations. Release of the cations is by ion exchange with other cations, e.g. the alkali metal cations of sea water, and does not, as is normal with corrosion inhibiting coatings, depend on the water solubility of the corrosion inhibitor.

Corrosion inhibitors, method of producing and protective coatings

Corrosion inhibiting particles comprise an inorganic oxide, particularly alumina, having corrosion inhibiting anions, particularly phosphate, chromate or benzoate anions, chemically bound to them. They may be prepared by contacting an oxide containing hydroxyl groups with an acidic solution containing the anions at ambient temperatures. The particles may be incorporated into protective coatings, e.g. paints based on epoxy resins, alkyd resins or chlorinated rubbers, in amounts up to 80% wt based on dry film weight, giving coatings with up to 4.0% corrosion inhibiting anions. Release of the anions is by ion-exchange with other anions e.g. the chloride anions of sea water or salt spray, and does not, as is normal with corrosion inhibiting coatings, depend on water solubility.

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Hampton Hill, United Kingdom

David A Pippard