| abstract |
Disclosed is a non-chromate rust-preventive surface treating agent which can form, on a zinc surface of a metal member, a silica-containing coating film which hardly causes cracking or detaching and can impart good anti-rust properties to the surface. The agent comprises a solution of an alkoxysilane oligomer having a weight average molecular weight of 1,000 to 10,000 in an alcohol, wherein 2.5 to 15% of silicon atoms in the alkoxysilane oligomer molecule are substituted by titanium atoms. The alkoxysilane oligomer which is partially substituted by titanium can be produced by reacting a titanium compound with a tetraalkoxysilane monomer or an alkoxysilane oligomer in an alcoholic solution, wherein the titanium compound can be prepared by chelating about half of alkoxide groups in titanium tetraalkoxide. |