A 2-liter flask fitted with a stirrer, an air introduction tube, a condensing pipe and a thermostat was charged with 222 parts of isophorone diisocyanate and 50 parts of methyl isobutyl ketone. While blowing a dry air into a liquid phase, they were stirred and heated to 70° C. To the mixture was added 0.3 part of dibutyltin dilaurate, followed by adding dropwise 232 parts of 2-hydroxyethyl acrylate for 1 hour. Even after the dropwise addition, the mixture was heated and kept at 70° C. The reaction mixture was collected with the lapse of time and absorption of -NCO was ascertained by IR. A time when the absorption of -NCO disappeared was made the termination of the reaction. There resulted a blocked 90% isophorone diisocyanate/2-hydroxyethyl acrylate solution. The 70% solids content bubble viscosity (solvent composition: 10% of methyl isobutyl ketone and 20% of n-butyl acrylate) was GH.
