| 摘要 |
PURPOSE: To form a homogenous coating film by repeatedly performing a process applying a primary rust preventing coating material to the surface of a steel panel unidirectionally or reciprocally by using a coating line wherein a plurality of spray tips are arranged along the advance direction of the steel panel to be coated for a large-sized structure and the direction crossing the steel panel at a right angle so as to leave an interval between the spray tips. CONSTITUTION: A large-sized structure such as a ship or a bridge is constructed using a steel panel preliminarily subjected to rust preventing treatment and coated with a primary rust preventing coating material. When the primary rust preventing coating material is applied to the steel panel 1 for the large-sized structure, a coating line wherein a plurality of spray tips are arranged along the width direction of the steel panel 1 so as to leave an interval between the spray tips is used. In this case, the interval between the spray tips in the width direction of the steel panel is set to 1/n (n; integer of 2 or more) the width of a spray pattern. After the spray coating with the primary rust preventing coating material is applied to the steel panel 1 while the steel panel is unidirectionally advanced, a process wherein the spray tips are moved in a reverse direction in synchronous relation to the advance speed of the steel panel is repeated to form homogeous film thickness wherein average dry film thickness is 10-50μm and the irregularity index of film thickness is 0.18 or less.
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