Over coating layer (OCL) materials were prepared by mixing acrylate copolymer and epoxy compound. The shelf life of the OCL materials could be extended, because of suppression of the crosslinking reaction between the acrylic acid and epoxy groups during storage at room temperature. However, the microphase separation between the acrylate copolymer and the epoxy compound was caused during the post-baking process, leading to the formation of rough surface, and consequently decrease in the transparency. The compounds having longer alkyl chains and acid group such as palmitic acid and 2-ethylhexyl maleate were found to prevent the microphase separation.