Crude di:phenyl-methane di:isocyanate mixt prodn with light colour - by phosgenating amine mixt in inert organic solvent and adding amine and/or urea cpd before thermal treatment, useful in resin and foam mfr

摘要

Prodn. of mixts. (I) of diphenylmethane diisocyanates (MDI) and polyphenyl polymethylene polyisocyanates (IA) with reduced I2 colour no. involves reacting corresp. mixts. (II) of diphenylmethane diamines (MDA) and polyphenyl polymethylene polyamines (IIA) with COCl2 in the presence of inert organic solvent(s) (III) at elevated temp., sepn. of excess COCl2 and (III) when phosgenation is complete and thermal treatment of the reaction prod. The novelty is that amines (IVA) and/or urea cpds. (IVB) are incorporated in the reaction mixt. after phosgenation. (IVA) are aromatic amines, pref. MDA and/or (IIA); and (IVB) are aliphatic and/or aromatic cpds., pref. urea derivs. of MDI and/or (IA). (IV) are added in amts. of 0.01-2.5% w.r.t. (I) in the reaction mixt. and at the time when the COCl2 content of the mixt. is 0.01-3%. USE/ADVANTAGE - (I) are useful in the prodn. of compact or foamed polyisocyanate poly-addn. prods., pref. flexible or (semi-)rigid foam contg. urethane and opt. isocyanurate gps. Addn. of (IV) reduces I2 colour no., e.g. to under 60, without the need to add water. The (I) obtd. contain 30-90, pref. 30-70 (wt.)% MDI isomers and have an NCO content of 31 +/- 2, pref. 31 +/- 1% and viscosity of max. 2000, pref. 40-700 mPa.s at 23 deg.C. (I) give light-coloured foams.