Flame retardants for polyurethane foam prepn. - by partial esterification of phosphorous-contg. alcohols with acid anhydrides

摘要

Polyethers are prepd. as in parent patent by reaction of white P with alkali hydroxide, water and aldehydes in presence of alcohols, at 30-75 degrees C, addition of a strong, anhydrous mineral acid and reaction of the free bis-(hydroxyalkane) phosphinic acids with epoxy cpds., are esterified by heating with acid anhydrides which are pref. of 2-4C carboxylic acids, in an amt. sufficient to reduce the OH value to 10-400, and the reaction is at 20-120 degrees C. Prods. can be used as flame retardants in soft and semi-rigid polyurethane foams, where the known polyethers cause cross-linking and excessive change in props. of the foams.