GB839188A - Improvements in or relating to the manufacture of cellular polymeric materials - Google Patents

Abstract

A process for the manufacture of blown, cellular materials by reaction of a polyisocyanate with a polyester, if necessary in the presence of water and/or a catalyst, is characterized in that the ingredients are allowed to react at a sub-atmospheric pressure. The process can be performed by initially mixing the reactants at atmospheric or superatmospheric pressure, transferring the mixture to a mould and then reducing the pressure. Suitably, the foaming mass is maintained at a final pressure of 200 to 600 mm. below atmospheric pressure until the reaction is substantially completed. The ester employed in the reaction may suitably be that employed in the process of Specification 790,420. Suitable polyisocyanates are hexamethylene, toluylene, diphenyl methane-4,41, m- and p-phenylene, monochlorophenyl and dicyclohexylmethane diisocyanates. Triethylamine, dimethylcyclohexylamine, di-(b -diethylaminoethyl) adipate, N : N-diethylbenzylamine, N-ethylhexamethyleneimine, N-ethylpiperidine and a -methylbenzyldimethylamine are suitable catalysts. As emulsifying agents for addition to the reaction mixture there may be employed turkey red oil, oleic acid partially neutralized with diethylamine, cetyltrimethylammonium bromide, cetylpyridinium bromide, oleyl sodium sulphate and ethylene oxide condensation products with, for example, alkylphenols. The reactants may be mixed in a continuous manner, such as in the process of Specification 839,183. In examples, foamed products are prepared by mixing a diethylene glycol/pentaerythritol/adipic acid polyester, a 60 : 40 mixture of 2 : 4- and 2 : 6-toluylene diisocyanates, water, diethylamine oleate and di-(b -diethylaminoethyl) adipate, introducing the mixture into a vertical cylindrical mould, and when the depth of the mixture reaches 5 times its original value, reducing the pressure from atmospheric to 250 mm. Specifications 553,733 and 839,185 also are referred to.