Coating solution for forming composite metal oxide film and process for making same

A process for producing a coating solution for forming a composite metal oxide film comprising the steps of:

• reacting component (A) with component (B) and subsequently incorporating component (C) wherein,
• component (A) is at least one member selected from the group consisting of a reaction product, a partial hydrolyzate of said reaction product, and a partial acylated product of said reaction product wherein said reaction product is obtained by a reaction between a .beta.-diketone compound and at least one metal compound represented by formula (I):
• M.sub.1 A.sub.n (I)
• wherein M.sub.1 is Ti, Zr, Nb, Hf or Ta;
• A is --OR or a halogen atom, R is a saturated or unsaturated hydrocarbon having 1-6 carbon atoms;
• and n is an integer of 2-5;
• component (B) is a polyhydric alcohol compound;
• and
• component (C) is at least one metal compound selected from the group consisting of formulas (II), (III) and (IV);
• wherein,
• formula (II) is a metal carboxylate compound represented by:
• M.sub.2 (OCOR).sub.m (II)
• wherein M.sub.2 is Pb, Sr, Ba, Mg, Zn, La, Y or Li;
• R is a saturated or unsaturated hydrocarbon having 1-6 carbon atoms;
• and m is an integer of 1-4;
• formula (III) is a metal nitrate compound represented by:
• M.sub.2 (NO.sub.3).sub.m (III)
• wherein M.sub.2 is Pb, Sr, Ba, Mg, Zn, La, Y or Li;
• and m is an integer of 1-4;
• and,
• formula (IV) is a metal nitrite compound represented by:
• M.sub.3 (NO.sub.2)l (IV)
• wherein M.sub.3 is Sr, Ba or Li;
• and l is an integer of 1 or 2.