| abstract |
Diphenylmethane diisocyanate, (I) partic. distilled disphenylmethane-4,4'-diisocyanate contg. =10% of 2,4-isomer and 2% other isomers, is stabilised against discolouration on storage by incorporating a small quantity of an organic base, (II), pref. a tert amine contg. >=2 alkyl, cycloalkyl, or aralkyl gps. partic. dodecyl dimethylamine. The process is used in the prepn. of esp. solid homogeneous or elastomeric polyurethanes, having improved colour, and surface coatings. Dimerising of (I) to uretodiones can be prevented by using small quantities of (II). |