| 摘要 |
PROBLEM TO BE SOLVED: To provide an aqueous coating agent and a coating film which are capable of improving rust prevention properties of a metal such as a galvanized steel, are excellent in film-forming properties, can be produced at low cost, and are environmentally friendly. SOLUTION: The characteristics of the aqueous coating agent and the coating film are evaluated in terms of six attributes, i.e., film-forming properties, rust prevention properties, adhesiveness, hardness, water resistance, and thermal cycle resistance. A test piece to be evaluated is prepared by using a galvanized, trivalent chromate steel sheet of 150 mm long, 70 mm wide, and 0.8 mm thick as a substrate, applying the aqueous coating agent to the substrate by an air spraying method so as to obtain a coating film of a thickness of 30μm, and drying it at 140°C for 5 min. The aqueous coating agent containing colloidal silica and SBR emulsion, in a solid content weight ratio of the colloidal silica to the SBR emulsion of larger than 10/90 and smaller than 70/30, receives at least the first rate in all six attributes. COPYRIGHT: (C)2010,JPO&INPIT |
