| abstract |
The present invention relates to a process for the preparation of bis-carbonic acid monoaryl esters of polyester-diols, lengthened via -OCOO- groups, characterized in that polyester-diols with molecular weights Mn (number-average) of over 250, preferably over 600, are heated with carbonic acid bis-aryl esters at temperatures between about 100 DEG C. and 200 DEG C., preferably between about 110 DEG C. and 180 DEG C., in vacuo below about 35 mm Hg, preferably between about 25 and 1 mm Hg, in the presence of catalysts, less than one mol of carbonic acid bis-aryl ester being employed per mol of OH group of the polyester-diol and the hydroxyaryl compounds formed being distilled off. The invention further relates to the bis-carbonic acid aryl esters of polyester-diols lengthened via -OCOO- groups. |