CPC B05D 7/542 (2013.01) [B05D 1/06 (2013.01); B05D 1/12 (2013.01); B05D 1/36 (2013.01); B05D 3/002 (2013.01); B05D 3/0218 (2013.01); B05D 3/0254 (2013.01); B05D 3/102 (2013.01); B05D 3/12 (2013.01); B05D 7/14 (2013.01); C08K 3/22 (2013.01); C08K 5/29 (2013.01); C08K 5/32 (2013.01); C08K 5/3445 (2013.01); C09D 5/03 (2013.01); C09D 5/035 (2013.01); C09D 163/00 (2013.01); C23C 24/00 (2013.01); C23C 26/00 (2013.01); C23C 28/00 (2013.01); B05D 2202/10 (2013.01); B05D 2451/00 (2013.01); B32B 7/02 (2013.01); C08K 2003/2241 (2013.01); C09D 167/00 (2013.01); C09D 167/02 (2013.01); C09D 167/03 (2013.01); Y10T 428/31529 (2015.04)] | 18 Claims |
1. A method, comprising:
providing a metal substrate;
applying a first coating comprising a first powder coating composition including a polymeric binding resin, wherein the first powder coating composition has a flow of no more than about 40 mm and one or more pigments that exhibit a large permanent color change on exposure to a curing temperature of the first coating;
applying a second coating comprising a second powder coating composition including a polymeric binding resin wherein the second powder coating compositions has a flow more than about 50 mm and one or more pigments that exhibit a large permanent color change on exposure to a curing temperature of the second coating; and
heating the metal substrate with the first coating and second coating in a single step at a temperature of about 120° C. to about 200° C., without multiple heating cycles, to form a cured coating comprised of the first coating and second coating, the cured coating having corrosion resistance, wherein the large permanent color change of the first coating or the second coating has a ΔE of at least about 1 unit, and wherein the second coating in the cured coating covers the entire first coating.
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