Chromium-free process for improving paint adhesion after thin-layer anodization
AssigneeHenkel Kommanditgesellschaft auf Aktien
InventorsWolf-Achim Roland, Andreas Nowak
Life of this patent
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Abstract
A process for improving the adherence of paint applied after thin-film anodization is characterized in that the anodized metal surfaces are brought into contact with an aqueous solution containing one or more of the following components: (a) 200 to 2000 ppm of a homopolymer or copolymer of acrylic acid, methacrylic acid, and/or their esters; (b) 200 to 3000 ppm of a poly(vinyl phenol) compound in which at part of the phenol rings carry an alkylamino substituent; (c) 200 to 3000 ppm of hexafluorotitanic acid, hexafluorozirconic acid, and/or their anions.
Claims20
A process for improving the adhesion of subsequently applied paint to an anodized metal surface after thin-layer anodization, said process comprising a step of contacting the anodized metal surface after thin-layer anodization with an aqueous solution containing one or both of the following groups a) and b of components:
- a) a.1) from 200 to 2,000 ppm of a homopolymer or copolymer of at least one of acrylic acid, methacrylic acid, esters of acrylic acid, and esters of methacrylic acid, said homopolymer or copolymer having an average molecular weight of 20,000 to 15,000;
- and
- a.2) from 5 to 50 ppm of hydrofluoric acid, anions thereof, or both hydrofluoric acid and anions thereof;
- and
- b) from 200 to 3,000 ppm in total of
- b.1) at least one of unneutralized hexafluorotitanic acid and hexafluorozirconic acid;
- and
- b.2) ammonium salts of at least one of hexafluorotitanic acid and hexafluorozirconic acid.
Dependencies are inferred from the claim text.