Patent ID: 8702954

Claim:
A process for producing a surface-treated metal substrate, comprising the steps of: (i) forming a film on a metal substrate comprising immersing the metal substrate as a cathode in a treatment composition (I), and applying an electric current for 10 to 600 seconds by superposing an AC voltage (Va) with a frequency of 0.1 to 1,000 Hz and a peak-to-peak voltage of 1 to 40 V onto a 1 to 50 V DC voltage (Vd) to obtain the formed film comprising at least one substance selected from the group consisting of a metal oxide, a metal fluoride and a metal hydroxide, and (ii) forming a coating film on the formed film by performing an electrodeposition coating using a cationic electrodeposition coating composition, wherein the treatment composition (I) comprises water and a metal compound component (A) comprising one or more compound(s) of at least one metal (a), wherein the metal (a) is selected from the group consisting of zirconium, titanium, cobalt, vanadium, tungsten, molybdenum, copper, zinc, indium, bismuth, yttrium, iron, nickel, manganese, gallium, silver and lanthanide, and wherein the metal compound component (A) is contained in an amount of 5 to 20,000 ppm in the treatment composition (I), calculated as a total quantity of metal, on a mass basis.