| 摘要 |
PURPOSE:To prevent the generation of pinhole, etc., by performing washing treatment of washed metal procesed body in the atmosphere of fluorinated hydrocarbons after fat removing and neutralization treatment. CONSTITUTION:Foreign matters or water dusts not removed by washing process of metal processed body completely, are removed by fron washing. For example, metal can is impregnated and washed twice for 18-35 sec, in the normal temprature water after impregnating in 7-10% caustic soda solution for 50-100sec. and washing by water. Next, said can is impregnated and washed twice for 18-35 sec. in the normal temperature water again after impregnating in 7-10% nitric acid solution for 15-25sec. and washing by water. Moreover, fron washing is performed in the shower room of fluorinated hydrocarbons (frons) having 45-48 deg.C boiling point for 110-70sec. and next, fron washing is performed in the vapor room of the same fluorinated hydrocarbons for 50-70sec. The metal can is completely dried simultaneously with the finish of the last fron washing because said hydrocarbons have a strong volatility. |
