CHROMIUM-FREE, CURABLE COATING COMPOSITIONS FOR METAL SUBSTRATES

摘要

A curable emulsion coating composition essentially free of chromium is provided. The composition comprises a discontinuous phase comprising at least one water-insoluble, particulate film-forming thermoplastic resin, at least one water-insoluble, film-forming thermosetting resin, and at least one water-insoluble alkali metal salt of a heavy metal-containing acid. The heavy metal may be selected from titanium, zirconium, and mixtures thereof. The composition is suitable for use over a variety of metal substrates as a pretreatment coating or as a direct-to-metal primer.Also provided is a process for coating a metal substrate by contacting the substrate with the curable composition described above and heating the coated substrate to a peak metal temperature of 170 to 350 DEG F (77 to 177 DEG C). The coated metal substrate has a cured coating weight of 250-400 mg/ft<2>.