PRODUCTION OF DIPHENYLMETHANE DIISOCYANATE DIMER

摘要

PROBLEM TO BE SOLVED: To obtain the subject dimer for e.g. producting polyurethanes without losing its reactivity by reaction of a diphenylmethane diisocyanate in an aromatic hydroctarbon or its chloride as an inert solvent in the presence of a dimerization catalyst. SOLUTION: First, 4,4'-diphenylmethane diisocyanate is reacted in an aromatic hydrocarbon (e.g. toluene) cor its chloride (e.g. chlorobenzene) as an inert solvent in the presence of a dimerization catalyst (e.g. tri-n-butylphosphine) under agitation at room temperature (20-25t deg.C) for 24h; subsequently, a solid product deposited is filtered to obtain the objecttive diphenylmethane diisocyanate dimer maintaining its isocyanate groups even at high temperatures and retaining its reactivity and suitable for producing polyurethanes. The inert solvent may be a ketone (e.g. actetone) or carbocxylic ester (e.g. ethyl acetate).