| 摘要 |
Polyisocyanates are isolated from crude mixtures by mixing the latter with a polyalkylene polyether and distilling the polyisocyanate from an agitated thin film of the resultant mixture. In examples, tolylene diisocyanate is thus obtained from a tolylenediamine phosgenation product in o-dichlorobenzene, by addition of polyoxypropylated-isooctanol or -butanol; and distillation from a wiped-wall thin film evaporator. |
