| http://www.w3.org/ns/prov#value | - To prepare the polyester polyols, the organic, for example aromatic and preferably aliphatic polycarboxylic acids and/or derivatives and polyhydric alcohols can be polycondensed in the absence of catalysts or preferably in the presence of esterification catalysts, advantageously in an atmosphere of inert gas such as nitrogen, carbon monoxide, helium, argon, etc., in the melt at from 150??? to 250?
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