| 摘要 |
<p>In order to obtain continuous reaction at normal pressure and to reclaim the reagents a mixture of 80% dimethylformamide and 20% copolymer is used which is heated and into which ammonia is blown, whilst stirring, at an hourly throughput rate of 20% with respect to copolymer the reaction mixt. is subjected to such treatment for 30 mins. at 140 to 150 degrees C heating and feeding in of ammonia is then stopped and when the temp. has dropped to 30 to 40 degrees C the precipitate formed is filtered off, washed with hot water so as to remove dimethylformamide and urotropin formed, then washed with acetone, and finally vacuum-dried at 60 to 80 degrees C. The product is heat-stable and may be used for injection moulding.</p> |
