| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a method for producing a polyisocyanate by which the load on the environment can be reduced while effectively utilizing hydrogen chloride by-produced in a polyisocyanate production process. <P>SOLUTION: Carbonyl chloride is produced by feeding additional chlorine and carbon monoxide to a reaction vessel 2 for producing the carbonyl chloride at a start-up operation between the start of the operation and the stable operation, and the polyisocyanate is produced at an isocyanate-forming reaction vessel 3 while by-producing hydrogen chloride gas. Reclaimed chlorine is produced by oxidizing the hydrogen chloride gas at a hydrogen chloride-oxidizing vessel 6. In the loadup operation thereafter, the carbonyl chloride is produced by feeding the additional chlorine, the reclaimed chlorine and the carbon monoxide to the reaction vessel 2 for producing the carbonyl chloride. Further, the polyisocyanate is produced at the isocyanate-forming reaction vessel 3 while by-producing the hydrogen chloride gas, and the reclaimed chloride is produced by oxidizing the hydrogen chloride gas at the hydrogen chloride-oxidizing vessel 6. The loadup operation is repeated until the production amount of the polyisocyanate achieves that at the stable operation. <P>COPYRIGHT: (C)2006,JPO&NCIPI</p> |
