| abstract |
For the production of polyester or polyether-polyester polyols, polyols, preferably di- to hexafunctional polyetherols with hydroxyl numbers from 15 to 250, with at least one carboxylic acid anhydride, preferably phthalic anhydride, in the presence of N-methylimidazole, triethylenediamine and / or triphenylphosphine become a carboxylic acid half-ester esterified and this is then alkoxylated with at least one alkylene oxide, preferably ethylene oxide, in the presence of N-methylimidazole, triethylene diamine, triphenylphosphine, thiodialkylene glycol or a mixture of at least two of the compounds mentioned as a catalyst. |