| 摘要 |
PROBLEM TO BE SOLVED: To provide a solution for forming a coating film, which can form a coating film on a surface of a metal material without using any strongly alkaline aqueous solution for forming a coating film, and can form an easily removable coating film, which can be removed by a simple means of washing out with water.SOLUTION: Glass containing a main component of BOis brought in contact with water. When a total of concentrations of respective elements in a liquid is set at 100 mass%, the respective concentrations of B, R, Si, and R' (R: one or two or more of alkali metal(s); and R': one or two or more of Mg, Ca, Sr, Ba, and Zn) are always maintained within ranges of "B concentration: 47-70 mass%, R concentration: 16-36 mass%, Si concentration: 0.5-22 mass%, and R' concentration: 0.3-17 mass%". |
