Example 3
In a four-necked flask of 1 liter equipped with a well-dried stirring blade and a thermometer, 444 g (2.00 mol) of M-600A, 0.63 g of DBTDL (0.10% by mass with respect to the total mass of M-600A and XDI), and 0.32 g of MEHQ (0.05% by mass of the total mass of M-600A and XDI) were added and stirred until the mixture was homogeneous, and then the temperature was raised to 60° C. Subsequently, 188 g of XDI (1.00 mol) was added dropwise over 1 hour. As the internal temperature rose due to the reaction heat during the drop, the drop rate was controlled so that the temperature was below 80° C. After completion of the dropping of the total amount, the reaction was carried out for 10 hours while keeping the temperature at 80° C. At this time, the proceedings of reaction were tracked by HPLC analysis to confirm the endpoint of the reaction. The product was discharged from the reactor to obtain 600 g of a bifunctional urethane acrylate (MMD-352). The viscosity at 65° C. was 6,210 mPa·s.
