Method for coating metallic surfaces with a multi-component aqueous composition
AssigneeChemetall GmbH
InventorsThomas Kolberg, Peter Schubach, Manfred Walter, Carola Komp, Michael Dröge
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Abstract
A method for coating metallic surfaces with aqueous compositions, wherein a silane-based aqueous composition containing at least one silane and/or a related silicon-containing compound and optionally additional components is treated further, for example, at temperatures above 70° C., in a pretreatment step without drying the coating, by using at least one aqueous rinse step after this pretreatment step and then performing an electrodeposition coating, in which at least one surfactant is added at least in the last rinse step of the aqueous rinse steps. Coated metallic surfaces are also described.
Claims22
A method for improving the throwing power of an electrodeposition coating, the method comprising:
- applying to a metallic surface two aqueous treatment compositions having different contents of at least one iron compound dissolved in water prior to contacting the metallic surface with an aqueous silane-based pretreatment composition;
- contacting the metallic surface with the aqueous silane-based pretreatment composition that comprises:
- a) at least one compound selected from silanes, silanols, siloxanes, and polysiloxanes, of which at least one of these compounds is still condensable, and
- b) at least one titanium, hafnium, and zirconium compound, and
- c) at least one type of cation selected from cations of metals of Groups IB to IIIB and VB to VIIIB, including lanthanides, and of main group II, of the periodic table of the elements, and/or at least one corresponding compound c), and/or
- d) at least one organic compound selected from monomers, oligomers, polymers, copolymers, and block copolymers, and
- e) water, and optionally at least one organic solvent and/or at least one substance to adjust the pH,
- thereby forming a pretreatment coating;
- rinsing the pretreatment coating at least once with water optionally comprising a surfactant;
- and
- applying an electrodeposition coating after the rinsing,
- wherein the aqueous silane-based pretreatment composition has a pH of from 1.5 to 9, and
- wherein the pretreatment coating is not completely dried, so that the at least one compound a) is not highly condensed before the rinsing of the pretreatment coating with water and/or before the coating with the electrodeposition coating.
Dependencies are inferred from the claim text.