反应详情

0.2 mol of ®Voranol CP 6055 (DOW), 0.4 mol of hydroxyethyl methacrylate (HEMA), 500 ppm of 2,6-di-tert-butyl-4-methyl-phenol, based on the predicted amount of the final product, 0.46 mol of IPDI (isophorone diisocyanate) and 2*10−3 mol of dibutyltin dilaurate (DBTDL) are used as initial charge in a round-bottomed flask with reflux condenser, thermometer, stirrer, and dropping funnel, and are stirred at room temperature for one hour. The temperature of the mixture is then raised continuously to 80° C. within one hour. The temperature is then kept at 80° C. for about 5 hours until the content of isocyanate groups has fallen below 0.1%, with, above the mixture, a nitrogen-oxygen mixture using about 7% by volume of oxygen. If, despite prolonged continued reaction time, the isocyanate content fails to decrease below 0.1%, residual amounts of isocyanate groups are reacted with a stoichiometric amount of HEMA. 500 ppm of 2-tert-butyl-4,6-dimethylphenol, based on the total mass of the final product, are then added to the mixture. This reaction gives a mixture of urethane methacrylates, and this mixture can be used in further reactions without further work-up.