| 摘要 |
PURPOSE:To obtain a composition excellent in descaling properties for metal by adding chelating agents to an aq. soln. of phosphate and regulating its pH value to a specified range. CONSTITUTION:As a composition for removing oxidized scale on the surface of metal, an aq. soln. obtd. by mixing polymerized phosphate such as pyrophosphate and tripolyphosphate or water soluble phosphate such as orthophosphate, orthophosphite, phosphite and hypophosphite with one or >=two kinds among various chelating agents in the weight ratio, e.g., of (95:5) to (5:95) is prepd., and its pH value is regulated to the range of 5.5 to 9.5 by sulfuric acid, hydrochloric acid, sodium hydroxide, potassium hydroxide or the like. A safe and inexpensive descaling composition for metal showing almost neutrality and free from the need of pH treatment for waste soln. can be obtd. |
