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.
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.
TAKAHASHI HIRONORI
MAEBA KOJI
IMAIZUMI TSUGIO
SARUWATARI MASAHITO
JP2004035492A | 2004-02-05 | |||
JP2004035489A | 2004-02-05 | |||
JP2001516333A | 2001-09-25 | |||
JP2003313155A | 2003-11-06 |
WO2005005037A1 | 2005-01-20 | |||
WO2004014845A1 | 2004-02-19 | |||
WO2004037718A2 | 2004-05-06 |