| 摘要 |
PROBLEM TO BE SOLVED: To prevent corrosion of an object to be washed without sacrificing washing ability when an out-door structure is washed by using a diphosphonic acid derivative. SOLUTION: A diphosphonic acid derivative represented by the formula is used wherein R is a 1-21C alkyl, alkenyl, alkylaryl or aryl and M1-M4 are each H, a basic-nitrogen containing compound or a metal cation. The basic- nitrogen containing compound is preferably a cation compound of monomethyldiethanolamine, triethanolamine or diethylmonoethanolamine. The metal cation is preferably Ca, Zn, Mn, Mg, Ba or Al. Concretely, a 1- hydroxyalkylidenediphosphonic acid or a derivative thereof is particularly preferable among which 1-hydroxyethylidene-1,1-diphosphonic acid or a derivative thereof is more particularly preferable. The treating agent is used preferably as an aqueous solution which preferably contains 1-30 wt.% of the diphosphonic acid derivative. |
