| 摘要 |
LIQUID METHYLENE DIPHENYL DIISOCYANATE Disclosed herein are processes for the production of allophanate-modified diphenylmethane diisocyanate prepolymers and the products produced by the processes which are both stable and liquid at 25.degree.C by reacting (i) 4,4'-diphenyl-methane diisocyanate containing from 2 to 60% by weight 2,4'-MDI and less than 6% by weight of the 2,2'-MDI with (ii) an aromatic alcohol containing between 6 and 18 carbon atoms such as phenol, with the resulting product being converted to the allophanate having an isocyanate group content of from 12 to 32% by weight.
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