WATER-REPELLING METHOD, PRODUCTION OF WATER-REPELLENT POWDER, WATER-REPELLENT COATING MATERIAL, WATER- REPELLENT COATING FILM FOR PROTECTING MIRROR SURFACE, WATER-REPELLENT COATING FILM FOR PROTECTING TRANSPARENT MEMBER, WATER-REPELLENT COATING FILM FOR PREVENTING ICE OR SNOW FROM STICKING, AND WATER-REPELLENT COATING FILM FOR PROTECTING EXTERNAL WALL OF BUILDING

摘要

PROBLEM TO BE SOLVED: To provide a water-repelling treatment process applicable to a substrate formed from, e.g. a glassy material, a metallic material, a ceramic material, or the like, which process comprises applying a sol obtained by hydrolyzing a hafnium compound to a substrate and baking the resultant substrate. SOLUTION: The sol-forming hafnium compound used is exemplified by a hafnium compound which reacts with water to form a sol of hafnium oxide. More particularly, it is exemplified by a hafnium halide, a hafnium halogenite, a hafnium hypohalogenite, a hafnium halogenate, a hafnium perhalogenate, a hafnium inorganic acid salt, a hafnium organic acid salt, a hafnium alkoxide, or a hafnium complex. An example of the method for reacting the sol-forming hafnium compound with water consists of dissolving the hafnium compound in an organic solvent and bringing the solution into contact with water. This process may be performed in the presence of an acid or a base as a catalyst.