| abstract |
The present invention relates to a process for the preparation of bis-carbonic acid aryl 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° C. and 200° C., preferably between about 110° C. and 180° 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 OH group of the polyester-diol and the hydroxyaryl compounds formed being distilled off. n The invention further relates to the bis-carbonic acid aryl esters of polyester-diols lengthened via --OCOO-- groups obtained according to the instant invention and their use for the preparation of polyester diol bis-diphenol carbonates, lengthened via carbonate groups, characterized in that polyester-diol bis-aryl carbonates are reacted with a diphenol at a temperature of from about 100° to about 200° C. in vacuo below about 35 mm Hg in the presence of a catalyst, wherein more than 1 mol of diphenol is employed per mol of carbonic acid aryl ester groups of the polyester-diol bis-aryl carbonate, lengthened via carbonate groups, and the resulting hydroxyaryl compound is distilled off. n The invention finally relates to the polyester-diol bis-diphenol carbonates, lengthened via carbonate groups obtained according to the instant invention and their use for the preparation of polyester/polycarbonates and the polycarbonate/polyesters so prepared. |