FIELD: chemistry.
SUBSTANCE: invention relates to the method of producing polyisocyanate, which involves (a) formation of polyisocyanate in a reaction system through reaction of polyamine, on which polyisocyanate is based, in a solution of inert solvent with phosgene, optionally in a solution of inert solvent; (b) separation of solvent from polyisocyanate, formed at stage (a) by evaporation or fractional distillation; (c) bringing the separated solvent to temperature between 10°C and 150°C and subsequent processing of the separated solvent with isocyanate trimerisation catalyst for trimerisation of isocyanate impurities in the separated solvent; (d) transferring the processed solvent from stage (c) to the reaction system at stage (a).
EFFECT: repeated use of solvent in the process, free from trace amounts of isocyanate and with low level of impurities.
10 cl, 1 dwg
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