Method of applying an anti-corrosion and/or adhesion promoting coating to a metal and resulting coated metal

Metal possessing the cured silane-based coating resulting from the method of:

• a) applying to said surface a curable coating composition consisting essentially of:
• (i) an aqueous solution of at least one partially or completely hydrolyzed and optionally partially condensed silane wherein the partially or completely hydrolyzed and optionally partially condensed silane is obtained from at least one hydrolyzable silane of the general Formula (1):
• wherein:
• each occurrence of R1 and R2 is independently a monovalent hydrocarbyl group of up to 20 carbon atoms, selected from an alkyl, alkenyl, arenyl, aryl, aralkyl and acyl group, optionally containing one or more etheric oxygen atoms;
• each occurrence of R3 and R4 is independently a divalent hydrocarbylene group of up to 12 carbon atoms, selected from the group consisting of an alkylene, alkenylene, arenylene, arylene and aralkylene group;
• each occurrence of R5 is independently a divalent or polyvalent hydrocarbylene group of up to 12 carbon atoms, selected from the group consisting of an alkylene, alkenylene, arenylene, arylene and aralkylene group;
• each occurrence of R6 is independently hydrogen, a monovalent hydrocarbyl group of up to 8 carbon atoms, selected from the group consisting of an alkyl, alkenyl, arenyl, aryl or aralkyl group, an —R3SiR2a(OR1)3-a group, a —C(═O)A1R5(OH)d group and an —R5(OH)d group;
• each occurrence of R7 is independently hydrogen, a monovalent hydrocarbyl group of up to 8 carbon atoms, selected from the group consisting of an alkyl, alkenyl, arenyl, aryl, and aralkyl group, an —R3SiR2a(OR1)3-a group and an —R8(OH)f group;
• each occurrence of A1 is independently divalent oxygen (—O—) or nitrogen of the structure —NR9— in which wherein R9 is hydrogen, a monovalent hydrocarbyl group of up to 8 carbon atoms, selected from the group consisting of an alkyl, alkenyl, arenyl, aryl or aralkyl group, an —R3SiR2a(OR1)3-a group and an —R8(OH)f group wherein each occurrence of R8 is independently a divalent or polyvalent hydrocarbylene group selected from alkylene, alkenylene, arenylene, arylene and aralkylene groups of up to 12 carbon atoms;
• and
• each occurrence of the subscripts a, b, c, d, e and f is independently an integer wherein a is 0 to 2;
• b is 0;
• c is 1;
• d is 1 to 4;
• e is 1;
• and, f is 1 to 4;
• and,
• (ii) at least one additional component selected from the group consisting of cosolvent, surfactant, a hydrolysable silane lacking a hydroxyl group and a pH modifier;
• and,
• b) curing the curable coating composition on the surface of the metal to provide an anti-corrosion coating thereon, wherein the curing step is carried out to provide an incompletely cured coating composition possessing a level of condensation of from 60 to 99 percent;
• and,
• c) applying a paint to the anti-corrosion coating of step (b) to provide for a metal surface coated therewith exhibiting at least 10 percent decrease in creepage value as measured by ASTM D 1654 compared with the similarly measured creepage value of a metal surface possessing a chromium sealed zinc phosphate coating of a thickness of 0.01 to 5 micrometers and the same paint of a thickness of 0.1 to 100 micrometers.