PURPOSE: To easily obtain a predetermined film thickness without generating skim or dripping, by making the surface tension force value of the film forming resin of an upper layer lower than that of the film forming resin of a lower layer by a value of a specific range.
CONSTITUTION: An aqueous paint coming to the film of an upper layer and an aqueous paint coming to the film of a lower layer are painted in layers in an uncured state but the surface tension force value of the water soluble resin constituting the aqueous paint of the upper layer is made 0.5W20dyne/cm lower than that of the resin constituting the aqueous paint of the lower layer. In this case, the surface tension force value is measured under such a condition that a water soluble resin solution consisting of 20wt% of a modified resin obtained by neutralizing the water soluble resin to a neutralization ratio of 80% in dimethylethanolamine is set to 20°C. As technique therefor, adjustment is performed by incorporating a larger amount of a hydrocarbon group having high surface activity into the resin or reducing the M.W. of the resin in the same resin type.
NOGAMI TETSUO
OGAWA HISAO
OKADA SATOSHI
