PROCESS FOR PRODUCING SACCHAROSE-BASED POLYOL POLYETHERS FOR HARD POLYURETHANE FOAMS IN AMINE CATALYSIS

The invention relates to a process for obtaining polyol polyethers for hard polyurethane foams by alkoxylation with propylenoxide and/or ethylenoxide of some saccharose/glycerine mixtures, for low or medium functionalities, or of saccharose/glycerine/finite polyether mixtures for high functionalities, at temperatures of 80...90 degree in the presence of some tertiary amines sterically blocked, as a catalyst, the completion of the reaction and the degasification of the remaining monomer. In another embodiment, the alkaline polyethers may be neutralized by the treatment with a stoichiometric amount of phtalic anhydride, related to the tertiary amine, used as a catalyst. By application of the invention, the secondary reactions are reduced to minimum, the undesirable phenomenon of saccharose concentration is avoided and there are obtained neutral polyethers, with a much lighter colour, with a less striking odour, the purifying stage being no longer necessary. Inventia se refera la un procedeu de obtinere a polieterilor polioli, pentru spume poliuretanice rigide, prin alcoxilarea cu propilenoxid si/sau etilenoxid, a unor amestecuri de zaharoza/glicerina, pentru functionalitati mici si medii, sau a unor amestecuri de zaharoza/glicerina/polieter finit, pentru functionalitati inalte, la temperaturi de 80...90 degree C, in prezenta unor amine tertiare putin impiedicate steric, drept catalizator, perfectarea reactiei si degazarea monomerului ramas. Intr-o alta varianta, polieterii alcalini pot fi neutralizati prin tratare cu o cantitate stoichiometrica de anhidrida ftalica, raportata la amina tertiara, utilizata drept catalizator. Prin aplicarea inventiei, se reduc la minimum reactiile secundare, se evita fenomenul nedorit de aglomerare a zaharozei si se obtin polieteri neutri, mult mai deschisi la culoare, cu miros mai putin pregnant, fara a mai fi necesara faza de purificare.