Electrodeposition coatings for use over aluminum substrates
AssigneePPG Industries Ohio, Inc.
InventorsJoseph T. Valko, Robin M. Peffer, Craig A. Wilson, Alan J. Kaylo
Life of this patent
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Abstract
A process for applying a coating on aluminum substrates by anionic electrodeposition of a phosphated epoxy resin made by phosphating a polyepoxide with both phosphoric acid and an organophosphonic acid and/or an organophosphinic acid. The coating has a reduced tendency to form pinholes.
Claims21
A process for providing a coating on an aluminum substrate by passing electric current between the substrate acting as an anode and a cathode in electrical contact with an electrodeposition bath containing an aqueous dispersion of a base-neutralized resinous composition comprising a curing agent and an ungelled phosphated epoxy resin in which the phosphated epoxy resin comprises a mixture of the reaction product of one or more polymeric epoxy compounds with phosphoric acid and with an organophosphonic acid and/or an organophosphinic acid, wherein the phosphated epoxy resin contains from 0.1 to 0.8 moles of phosphoric acid to one equivalent of epoxy and from 0.01 to 0.4 moles of phosphonic and/or an organophosphinic acid per equivalent of epoxy;
- in which the phosphated epoxy resin is resent in an amount of 50 to 90 percent by weight and the curing agent is present in an amount of 10 to 50 percent by weight, the percentages being based on the total solids weight of the phosphated epoxy resin and the curing agent.
An aqueous resinous dispersion comprising:
- (a) a base-neutralized resinous composition comprising a curing agent and an ungelled phosphated epoxy resin in which the phosphated epoxy resin comprises a mixture of the reaction product of one or more polymeric epoxy compounds with phosphoric acid and with an organophosphonic acid and/or an organophosphinic acid, wherein the phosphated epoxy resin contains from 0.1 to 0.8 moles of phosphoric acid and from 0.01 to 0.4 moles of phosphonic and/or an organophosphinic acid per equivalent of epoxy with the molar ratio of phosphoric acid to organophosphonic and/or organophosphinic acid being within the range of 1:0.01 to 0.5;
- in which the phosphated epoxy resin is present in an amount of 50 to 90 percent by weight and the curing agent is present in an amount of 10 to 50 percent by weight, the based on the total solids weight phosphated epoxy resin and the curing agent;
- and
- (b) an azole.
An aqueous resinous dispersion comprising:
- (a) a base-neutralized resinous composition comprising a curing agent and an ungelled phosphated epoxy resin in which the phosphated epoxy resin comprises a mixture of the reaction product of one or more polymeric epoxy compounds with phosphoric acid and with an organophosphonic acid and/or an organophosphinic acid;
- in which the phosphated epoxy resin is present in an amount of 50 to 90 percent by weight and the curing agent is present in an amount of 10 to 50 percent by weight, the percentages being based on the total solids weight of the phosphated epoxy resin and the curing agent;
- and
- (b) an azole.
Dependencies are inferred from the claim text.