| 摘要 |
PURPOSE:To obtain a zinc phosphate film having high adhesion to paint film and corrosion resistance suitable for cationic electrodeposition painting, by subjecting the surface of a metal to spray treatment with an acidic phosphate treating liquid which contains zinc ion, phosphate ion and nitrite ion and of which the free acidity is prescribed. CONSTITUTION:An acidic phosphate treating liquid containing 0.01-0.05W/V% zinc ion; 1.5-3.0W/V% phosphate ion and 0.001-0.02W/V% nitrite ion and having free acidity of 0.1-0.3 point is prepared. By using this treating liquid, the surface of a metal is subjected to spray treatment, for example, under such conditions that a temp. is 40-70 deg.C, spray pressure is 0.5-3kg/cm<2> and a treating time is 40sec or more. In this case, as the aforementioned objective metal, iron, zinc or alloys thereof are designated. |
