Process and composition for treating metal surfaces using trivalent chromium compounds
First Claim
1. A composition for treating a metal surface, said composition comprising water, a trivalent chromium compound, an organo-functional silane, a compound of a group IV-B element, and at least one polymer comprising a plurality of carboxylic functional groups and poly (vinyl alcohol).
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Abstract
An acidic, aqueous composition contains a trivalent chromium compound, an organo-functional silane, and a compound of a group IV-B element. The composition protects metal surfaces, preferably aluminum and aluminum alloys, against corrosion and improves their paint adhesion. The trivalent chromium compound may comprise chromium fluoride and optionally others, such as chromium nitrate. The organo-functional silane is preferably an aminopropyltriethoxy silane, and the compound of a group IV-B element is preferably fluorozirconic acid. The composition can either be dried-in-place or rinsed before a further coating layer is applied. The composition may also include at least one polymer having a plurality of both carboxylic functional groups, alone or with hydroxyl groups. A process uses the aqueous composition either with or without the organo-functional silane along with a sealing step following the application of the aqueous composition; the sealing step involves applying a sealing composition, including an organo-functional silane, to the metal surface.
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Citations
32 Claims
- 1. A composition for treating a metal surface, said composition comprising water, a trivalent chromium compound, an organo-functional silane, a compound of a group IV-B element, and at least one polymer comprising a plurality of carboxylic functional groups and poly (vinyl alcohol).
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13. A composition for treating a metal surface, said composition consisting essentially of water, at least one trivalent chromium compound, an organo-functional silane, fluorozirconic acid, and at least one polymer comprising a plurality of carboxylic functional groups and poly (vinyl alcohol).
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28. A process for treating a metal surface, said process comprising the steps of:
- contacting a metal surface with a composition comprising water, a trivalent chromium compound, an organo-functional silane a compound of a group IV-B element, and at least one polymer comprising a plurality of carboxylic functional groups and poly(vinyl alcohol);
sealing the metal surface by contacting the metal surface with a sealing composition comprising water and an organofunctional silane. - View Dependent Claims (29, 30, 31, 32)
- contacting a metal surface with a composition comprising water, a trivalent chromium compound, an organo-functional silane a compound of a group IV-B element, and at least one polymer comprising a plurality of carboxylic functional groups and poly(vinyl alcohol);
Specification