COATING FILM FORMATION AND HARDENED BODY OBTAINED THEREBY

摘要

PROBLEM TO BE SOLVED: To improve durable adhesion strength of a new coating to a deteriorated coating film at the time of coating for renewal coating by forming a coating film of a coating composition for under coating selected from specified groups and further forming a coating film of coating composition for a specified over coating thereon. SOLUTION: A coating film of a coating composition for one type of under coatings selected from groups (I), (II) is formed on a substrate and further a coating film of a coating composition for an over coating (III) is formed thereon to give a coating film having a photocatalytic function and high adhesive strength. (I) a coating composition for an under coating containing an organosilane (a) having the formula (R1)nSi(OR2)4-n (R1 is an organic group; R2 is an alkyl group or an acyl group) together with water or an organic solvent. (II) a coating composition for an under coating containing (a) together with a polymer (b) containing a silyl group. (III) a coating composition for an over coating containing a photocatalyst together with (a) and (b).