| 摘要 |
PURPOSE:To remarkably enhance durability by forming a topcoating film of a two-ply structure, increase pigment concentration of film on the lower ply and reduce the pigment concentration of film on the upper ply. CONSTITUTION:After forming a zinc phosphate film 2 on a pretreated material 1 to be coated such as cold-rolled steel plate, a prime-coating film 3 is formed by electrolytic coating. If necessary, after an intercoating film is formed, baked and cured, a topcoating film of two-ply structure consisting of a primary topcoating film 4 and a secondary topcoating film 5 is gradually formed over the whole of material 1 to be coated, all of which are baked and cured simultaneously. By increasing pigment concentration of the primary topcoating film 4 more than that of the secondary topcoating film 5, penetration rate of ultraviolet rays is decreased to a remarkable extent which prevents ply separation, choking and bronzing.
|
