Aqueous dispersion for metal coating from colloidal silica, alkoxy silane, and polymer

Claim 1

A composition for surface treatment of metals which comprises an aqueous dispersion of a silica-organic polymer complex which is the reaction product of ingredients consisting essentially of colloidal silica wherein the silica is of 7 to 100 mμ particle size, water soluble or water dispersible organic polymer having both hydroxyl and carboxyl groups and an acid value of 20-200 selected from the group consisting of acrylic copolymer resin, alkyd resin, epoxyester resin and polybutadiene resin, the compounding ratio on a solids basis of said colloidal silica and said organic polymer being in the range of 5:95 to 95:5 by weight, and 0.5-15% by weight based on the solid weight of said colloidal silica and said organic polymer of silane compound selected from the group consisting of divinyl dimethoxy silane, divinyl di-β-methoxyethoxy silane, di(γ-glycidoxy propyl)dimethoxy silane, vinyl triethoxy silane, vinyl tris-β-methoxyethoxy silane, γ-glycidoxy propyl trimethoxy silane, γ-methacryloxypropyl trimethoxy silane, β-(3,4-epoxycyclohexyl)ethyl trimethoxy silane, N-β-aminoethyl-γ-propylmethyl dimethoxy silane, N-β-aminoethyl-γ-propyl trimethoxy silane, and γ-aminopropyl triethoxy silane.