STABLE LIQUID DIPHENYLMETHANE DIISOCYANATES

摘要

1,194,050. Stabilized polyisocyanate compositions. IMPERIAL CHEMICAL INDUSTRIES Ltd. 28 Oct., 1968 [12 Dec., 1967], No. 56498/67. Heading C2C. Polyisocyanate compositions comprising a diphenylmethane diisocyanate in which from 1% to 50% of the isocyanate groups have been reacted with a non-sterically hindered aromatic carbodiimide other than a carbodiimide derived from diphenylmethane diisocyanate are obtained by mixing the diisocyanate and the carbodiimide and allowing the compounds to react. The reaction is suitably effected at a temperature of 40-150� C., optionally in the presence of a solvent. The sterically hindered aromatic carbodiimides employed are those in which the aromatic rings are free from substituents in the ortho positions adjacent to the carbodiimide group. A suitable class of carbodiimides are those of the formula wherein R1-R6 are hydrogen, hydrocarbon, hydrocarbyloxy, halogen, nitro, carboxyester, isocyanate or substituted hydrocarbon groups; other diimides are, however, specified. The resulting compositions probably contain uretonimines formed by addition of an isocyanate group to one of the double bonds of the carbodiimide. Specific examples describe the reaction of 4:41-diisocyanatodiphenyl methane (containing a small proportion of the 2:41-isomer) with (i) di-p-tolyl carbodiimide, (ii) diphenyl carbodiimide, and (iii) di-p-chlorophenyl carbodiimide.