PROCESS FOR COATING METALLIC SURFACES OF SUBSTRATES AND ARTICLES COATED BY THIS PROCESS

摘要

The invention relates to a process for coating metallic surfaces of substrates with aqueous compositions, also called coating compositions hereinafter, in the form of a dispersion and/or suspension which contains at least one stabilized binder and a gel former and forms a coating based on an ionic gel with the cations leached out of the metallic surface in a pretreatment stage and/or during the contacting, in which the coating is effected by: I. providing a substrate with a cleaned metallic surface, II. contacting and coating metallic surfaces with a first aqueous composition in the form of dispersion and/or suspension, III. optionally rinsing the organic coating, IV. optionally drying the organic coating and V. coating with at least one further coating composition prior to drying and crosslinking all the layers applied, where the stabilized binders must fulfill the condition that a) an aqueous mixture of demineralized water, 0.2% to 2% by weight of the gel former and 5% to 20% by weight of the stabilized binder; b) is adjusted to a pH of 1 to 7; c) a cleaned substrate is dipped into the mixture according to b) at room temperature for at least 1 minute and d) a check is made as to whether an organic coating of at least 1 µm has been deposited, wherein e) a test is additionally conducted without gel former, in which a mixture of demineralized water and 5% to 20% by weight of the dispersion to be examined is produced; f) the mixture produced in e) is likewise adjusted to a pH of 1 to 7 and g) the test described in c) and d) is repeated.