Patent ID: 8518172

Claim:
A method for producing an aqueous inorganic zinc-rich coating composition, wherein the composition comprises a vehicle comprising an aqueous solution containing an alkali silicate represented by formula M 2 O.nSiO 2 , wherein M represents Na, K, Li, or Cs, and n is a number of 2 to 4, at a concentration of 10 to 50 mass %, an ammonium ion at a concentration of 0.01 to 0.1 M, and a halide ion at a concentration of 0.01 to 1 M, and zinc powder, wherein the composition containing the vehicle and zinc powder in such amounts that when the composition is in the form of a dried film, the dried film has a binder solid content of 5 to 10 mass % and a zinc powder content of 90 to 95 mass %, said method comprising: employing said vehicle comprising a neutralization product of a vehicle formed through partially neutralizing alkali silicate with an inorganic acid in an amount of 0.5 to 4.5 mass % with respect to the mass of the alkali silicate, and an aqueous viscous resin liquid formed through neutralizing a diluted polyacrylic acid emulsion with aqueous alkali metal hydroxide solution, wherein the vehicle contains the two ingredients in such amounts that the vehicle has a neutralized polyacrylic acid solid content of 0.5 to 3.5 mass % with respect to the mass of the alkali silicate; and mixing the vehicle and the zinc powder.