| 摘要 |
PROBLEM TO BE SOLVED: To obtain a substrate with its surface exhibiting hydrophilicity irrespectively of the influence of ultraviolet rays, wherein the surface of the substrate is coated with a hydrophilic-functional-group-containing siliceous foaming film, and the angle of contact of the surface with water has a specified or lower value. SOLUTION: This substrate is prepared by coating the surface of a substrate with a siliceous coating film having hydrophilic functional groups and optionally containing ultramicroparticulate titanium oxide having a mean primary particle diameter of 0.1μm or below so as for the surface to have an angle of contact with water of 15 deg. or below. The siliceous coating film is formed by coating a substrate with a coating fluid prepared by dissolving a hydrolyzable silane compound mixture such as a mixture of tetraalkoxysilanes at least part of which has a hydrophilic functional group or a partial hydrolyzate thereof in an organic solvent. The hydrophilic functional groups are exemplified by sulfo, carboxyl, phosphonic groups, and polyoxyalkylene groups. A sulfo-containing siliceous coating film is formed by introducing sulfonic ester groups as precursor groups and heat-decomposing them or by introducing thiol groups or sulfide groups and oxidizing them with ozone.
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