Coating method of electrically conductive substrate, water-based coating and cross-linking agent containing blocked NCO group

摘要

The present invention relates to an alkaline dry-dipping process, wherein the electro-immersion primer used in the process comprises (I) a first step wherein (a) diphenylmethane diisocyanate and (b) a mixture of monoalcohols or monoalcohols are reacted (II) reacting the intermediate product (A) with (c) a polyol or a mixture of polyols to obtain an intermediate product (B) containing a hydroxyl group, (D) substitution, aliphatic or araliphatic polyisocyanate or a mixture of such polyisocyanates and (e) a single potency blocker or a mixture of such blockers, or (f) reacting with a partially blocked polyisocyanate prepared from (d) and (e) to obtain an isocyanate-free cross-linking agent It contains a primary binder.