| abstract |
Phenyl isocyanates are removed from solvent streams obtained from MDI and/or PMDI manufacturing processes by reaction in the presence of a carbodiimide catalyst to form the corresponding N,N'-diphenylcarbodiimide. The N,N'-diphenylcarbodiimides can be recycled into the MDI and/or PMDI manufacturing process, where they can be reacted with MDI and/or PMDI to form uretonimine. The uretonimine has at most minimal effect on the properties and usefulness of the MDI and/or PMDI product, and thus can remain in the MDI and/or PMDI product. |