| 摘要 |
PROBLEM TO BE SOLVED: To provide a formation method for a coating film capable of simultaneously performing coating of a chipping primer and coating of intermediate coating at coating of one step and obtaining the coating film with excellent anti-chipping property in a coating step of an automobile vehicle body and a part. SOLUTION: The formation method for the coating film includes step (1) for coating a substance to be coated formed with an electro-deposition coating film with a water base coating composition and step (2) for heating and curing it. In the formation method for the coating film, the water base coating composition contains a polyolefin resin (a), a water base polyester resin (b), and a melamine resin (c) and a solubility parameterδa of the polyolefin resin (a) and a solubility parameterδb of the water base polyester resin (b) satisfy a relationship of (δb-δa)>2.0. A weight average molecular weight (Mw) of the polyolefin resin (a) is 50,000-500,000 and a weight average molecular weight (Mw) of the water base polyester resin (b) is 5,000-30,000. COPYRIGHT: (C)2006,JPO&NCIPI
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