Disclosed is a surface-treated precoated
metal sheet of which resistance against
contamination with a photocatalyst and a self-cleaning function can be retained for a long period. Also disclosed are a method and a surface-treating solution for producing the surface-treated precoated
metal sheet properly. The surface-treated precoated
metal sheet is characterized by comprising a precoated
metal sheet comprising an under
metal sheet and an organic
resin coating layer provided on the surface of the under
metal sheet and a
coating film having at least two
layers, having a photocatalytic activity and formed on the precoated metal sheet, wherein the
coating film having at least two
layers comprises an inorganic-organic composite resin composed of a condensed product of an alkoxysilane selected from a group consisting of an alkoxysilane having an
organic group selected from a group consisting of an
alkyl group having 1 to 12 carbon atoms, an
aryl group, a carboxyl group, a
hydroxy group and a combination of two or more of these groups, an alkoxysilane having an
epoxy group, an alkoxysilane having an amino group, a tetraalkoxysilane and a combination of two or more of the alkoxysilanes and contains a substance having a photocatalytic activity in such an amount that the content of the substance is highest in the outermost layer of the
coating film and is gradually decreased toward an inner layer of the coating film.