Patent ID: 8128996
Filing Date: 2012-03-06
Classification: C09D

Abstract:
1. A process for primer coating a steel substrate comprising coating a steel substrate with a shop primer coating comprising a silica binder, the binder comprising an aqueous silica sol having a SiO drying the primer coating at a temperature of from 10° C. to 60° C. and, after the primer coating has dried to the extent that it is touch dry, immersing the coated substrate in water and/or storing it in an atmosphere with a relative humidity of at least 50%, wherein the coating has a dry film thickness of less than 40 microns, and wherein the primer coating optionally comprises alkali metal silicate at a weight ratio of alkali metal silicate to silica sol of less than 0.1; and, wherein said silica sol further contains an organic resin, in an amount of from 1 to 35% by weight, based on solid binder, wherein the organic resin is a latex.