Process for brigthening polymeric diphenylmethane diisocyanate and use of brightened diphenylmethane diisocyanate for the preparation of polyurethane plastics

摘要

Color lightening of polymeric diphenylmethane diisocyanate (MDI) for use in polyurethane preparation comprises irradiating at 250-2500 nm. Independent claims are included for: (i) The composition of the polymer, which comprises a mixture containing up to 70 wt.% 4,4'-, 2,4'- and 2,2'-isomers of MDI; and (ii) preparation of the polymer, comprising irradiation at 300-450 nm for 2 seconds to 30 minutes and the MDI is dissolved in an organic solvent, preferably monochlorobenzene.