Patent ID: 7910211
Filing Date: 2011-03-22
Classification: B05D,Y10T

Abstract:
1. A process for the production of multi-layer coatings comprising the successive steps: 1) applying a 8 to 20 μm thick coating layer from an aqueous coating composition A onto a substrate provided with an EDC primer, 2) applying a base coat layer from an aqueous coating composition B in a film thickness, below its black/white opacity, of 5 to 10 μm onto the previously applied coating layer, 3) applying a clear coat layer onto the base coat layer, 4) jointly curing the three coating layers, wherein coating compositions A and B being different from each other, the coating composition A having a ratio by weight of pigment content to resin solids of 0.2 to 0.5:1, the pigment content consisting of 0 to 100 wt. % of at least one aluminum platelet pigment having a platelet thickness from 200 to 500 nm, 0 to 90 wt. % of at least one interference platelet pigment C selected from the group consisting of metal oxide-coated aluminum oxide platelet pigments, metal oxide-coated silicon dioxide platelet pigments and metal oxide-coated mica platelet pigments, 0 to 15 wt. % of at least one carbon black pigment, and 0 to 60 wt. % of at least one pigment other than aluminum platelet pigments, interference platelet pigments C and carbon black pigments, the sum of the wt. % being 100 wt. %, at least 40 wt. % of the pigment content being formed by the at least one aluminum platelet pigment and/or the at least one interference platelet pigment C, and a proportion of at least 20 wt. % of the at least one aluminum platelet pigment having a mean particle diameter from 6 to 15 μm, wherein the coating compositions B having problematic color shades which are distinguished in that UV light corresponding to a UV transmission of more than 0.1% in the wavelength range of from 280 to 380 nm and/or of more than 0.5% in the wavelength range of from 380 to 400 nm may penetrate through a two-layer coating structure consisting of a 10 μm thick layer applied from a mixture produced in a resin solids ratio by weight of 1.5 parts by weight coating composition B to 1 part by weight trimeric hexane diisocyanate-polyisocyanate, and a 5 μm thick layer applied from the coating composition B itself.