Light coloured mixts. of di:phenylmethane di:isocyanate cpds. - and poly:phenyl poly:methylene poly:isocyanate cpds. are prepd. by treating reaction mixt. with a chloroformate and heating

摘要

Mixts. (I) of the diisocyanates and polyisocyanates with reduced iodine number are prepd. by (1) reacting corresp. mixt. of diphenylamethane diamines and polyphenylpolymethylene polyamines with COCl2 in presence of at least one inert organic solvent at raised temp.. (2) after phosgenation, sepg. off excess COCl2 and solvent, and (3) heating. An effective amt. of Cl-contg. agent (II) which is a carboxylic acid chloride and/or chloroformate is incorporated after phosgenation has ended. USE/ADVANTAGE - (I) for prepn. of polyisocyanate polyaddn. prods., e.g., foams contg. urethane and opt. isocyanurate gps., also for isolation of 4,4'-diphenyl-methane diisocyanate (4,4'-MDI), intermediate for polyurethane elastomers, fibres, sealing compsns., adhesives, etc.. Light coloured (I), required for prodn. of light coloured polyaddn. prods., etc., are obtd. without addn. of water which increases corrosive action of Cl2, HCl, and COCl2 on appts. and could lead to leakage of toxic COCl2 or COCl2-contg. reaction mixt..