| 主权项 |
1. A process for coating metallic surfaces of substrates with aqueous organic compositions, the process comprising:
I. providing a substrate with a cleaned metallic surface, II. contacting and coating the metallic surface with a first aqueous organic composition in the form of a dispersion, suspension or combination thereof, the first aqueous organic composition comprising a first stabilized binder and a gelling agent, so as to form a first organic coating, III. optionally rinsing the organic coating, IV. optionally drying the organic coating, and V. coating the first organic coating with at least one additional aqueous organic composition comprising the same or a second stabilized binder and a gelling agent before drying and crosslinking all applied layers, wherein the respective coating compositions each must fulfill the following conditions: a) be in the form of an aqueous mixture of deionized water, the gelling agent in an amount in the range of 0.2% to 2% by weight based on the weight of the coating composition and 5% to 20% by weight of the respective stabilized binder based on the weight of the coating composition; and b) be adjusted to a pH in the range of 1 to 7; and wherein c) a cleaned substrate is immersed in the aqueous mixture for at least 1 minute at room temperature, and d) a check is performed on whether an organic coating having a thickness of at least 1 μm has been deposited on the cleaned substrate,wherein each of the coatings forms a layer based on an ionogenic gel with cations that have been dissolved out of the metallic surface in a pretreatment stage and/or during the contacting, wherein the dry film thickness of all the deposited coatings after drying and crosslinking all of them is in the range of 3 to 500 μm. |
