| abstract |
The present invention a process and apparatus for the production of methylene diphenyl diisocyanate (MDI) isomer mixtures with a low 2,2'-MDI isomer content and a high 2,4'-MDI isomer content. The resulting mixtures have an increased reactivity and are acceptable in food grade application due to the reduction in primary aromatic amines formed during the curing process. The process and apparatus also include controlling the amount of 4,4'-MDI, which is the most reactive isomer in the mixture allowing use in a wide variety of applications. |