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AssigneeBASF SE
InventorsGregor Brodt, Jens Haas, Werner Hesse, Hans-Ulrich Jager
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The invention relates to a process for the electrolytic coating of metals with zinc or a zinc alloy in which matt surfaces are obtained, by deposition of zinc from an electrolyte solution comprising a zinc salt selected from zinc sulfate or an alkanesulfonate of zinc or mixtures thereof, and, if desired, further metal salts, an acid selected from sulfuric acid or an alkanesulfonic acid or a mixture of the two acids, and at least one additive for improving the surface roughness and preventing dendritic edge growth, selected from nitrogen-containing surface-active compounds, which may be ionic or nonionic, sulfur-containing anionic surface-active compounds, and surface-active compounds based on multifunctional alcohols having at least three hydroxyl groups. The invention furthermore relates to an electrolyte composition for electrolytic coating of metals with zinc or zinc alloys, and to the use of said additives for improving the surface roughness and preventing dendritic edge growth in the electrolytic coating of metals with zinc or a zinc alloy in an alkanesulfonic acid-containing electrolyte.
A process for the electrolytic coating of metals with zinc or a zinc alloy at a current density of from 10 to 400 A/dm2 in which matt surfaces are obtained, by deposition of zinc from an electrolyte solution comprising a zinc salt selected from zinc sulfate or an alkanesulfonate of zinc or mixtures thereof, and, if desired, further metal salts, an acid selected from sulfuric acid or an alkanesulfonic acid or a mixture of the two acids, and at least one additive for improving the surface roughness and preventing dendritic edge growth, selected from polyethyleneimines, products of the reaction of amines with epichlorhydrin, alkyl sulfates having at least 5 carbon atoms, sulfonates, and isethionates.
An electrolyte composition for electrolytic coating of metals with zinc or zinc alloys, comprising a zinc salt and, if desired, further metal salts, an acid selected from sulfuric acid or an alkanesulfonic acid or a mixture of the two acids, and at least one additive selected from polyethyleneimines, products of the reaction of amines with epichlorhydrin, alkyl sulfates having at least 5 carbon atoms, sulfonates, and isethionates.
The use of compounds selected from polyethyleneimines, products of the reaction of amines with epichlorhydrin, alkyl sulfates having at least 5 carbon atoms, sulfonates, and isethionates as additives for improving the surface roughness and preventing dendritic edge growth in the electrolytic coating of metals with zinc or a zinc alloy in an alkanesulfonic acid-containing electrolyte at a current density of from 10 to 400 A/dm2.
Dependencies are inferred from the claim text.