| 摘要 |
A mixture of isomeric diisocyanatodiphenylmethanes composed of at least 2,2'-diisocyanato-diphenylmethane, 2,4'-diisocyanatodiphenylmethane and 4,4'-diisocyanatodiphenyl-methane is distilled in at least one stage and a divided-wall column is used in at least one distillation stage.
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