3 9 wt and a monomer content of ipdi of 1 90 wt determined by gas chromatography 224 36 g equivalent weight 111 58 g equiv of 3 isocyanatomethyl 3 5 5 trimethylcyclohexyl isocyanate desmodur u00ae i commercial product of bayer ag leverkusen were initially introduced under inert gas nitrogen with 0 10 g of benzoyl chloride stirred and then combined with 1 00 g of dibutyltin laurate after heating to 45 u00b0 c 546 15 g equivalent weight 987 68 g equiv of desmophen u00ae 3600z polypropylene oxide glycol m n 2000 g mol commercial product bayer ag leverkusen were apportioned once the theoretical nco content of 7 9 wt had been reached a further 250 68 g equivalent weight 498 67 g equiv of desmophen u00ae 1600u polypropylene oxide glycol m n 1000 g mol commercial product bayer ag leverkusen were apportioned once addition was complete the reaction mixture was heated to 60 u00b0 c until an nco content of 3 9 wt was obtained the temperature was then reduced to room temperature the prepolymer had a viscosity of 9200 mpa u00b7 s 23 u00b0 c plate viscosimeter an nco content of 3 9 wt and a monomer content of ipdi of 2 15 wt determined by gas chromatography 230 00 g equivalent weight 111 44 g.