Easy-to-clean, mechanically stable coating composition for metallic surfaces and process for coating a substrate using said composition

A coating composition, comprising

• (A) a mixture of at least the following components:
• at least one silane having formula (I)
• (A-R)mSiX4-m (I)
• and
• at least one compound having formula (III)
• M(Y)n, (III)
• wherein A is an organic residue which can react with an alkylol or an alkylolether group of an alkylolamine residue to yield an ether linkage, R is selected from an optionally substituted alkylene and alkenylene groups, X and Y are independent groups the bonding of which to the Si or M atom, respectively, is susceptible to hydrolyzation in the presence of water, the M is a metal selected from those of the 3rd and 4th main group of the periodic table and of metals of the transition metal group which occur in trivalent or tetravalent condition, m is independently 1 or 2 and n is 3 in the case of M being a metal of the 3rd main group or a trivalent transition metal and is 4 in the case of M being a metal of the 4th main group or a tetravalent transition metal, the compounds of said mixture being partially or fully hydrolyzed and partly or fully condensed,
• (B) at least one of an alkylolamine derivative of melamine selected from
• derivatives having formula (VI)
• (C3N3)(NR4R5)3, (VI)
• wherein R4 and R5 are independently selected from H, hydroxymethylene and alkoxymethylene, with the proviso that at least one of the R4 groups present in the molecule of formula (VI) is a hydroxymethylene or alkoxymethylene group, or
• derivatives having formula (VII)
• (C3N3)(NR4R5)3-p(NR4R6)p, (VII)
• wherein R4 and R5 are defined as for formula (VI), and R6 is —CH2—NR4(C3N3)(NR4R5)2 or —CH2—O—CH2—NR4(C3N3)(NR4R5)2, and p is 1 or 2;
• and
• at least one of the group consisting of:
• partially or fully fluorinated, at least partly hydrolyzed and condensed silane compounds having formula (IV):
• R1mSiX4-m, (IV)
• wherein R1 is a partly or fully fluorinated alkyl group having at least 5 partly or fully fluorinated carbon atoms, and X and m are defined as for the silane of formula (I) above, the silane compound(s) having formula (IV) being part of mixture (A),
• and
• partially or fully fluorinated organic compounds (C) including at least one group which may bind to hydroxy groups.