Improved process for the preparation of aliphatic hydroxytelechelic polycarbonates by direct phosgenation, and the products so obtained.

摘要

1. Process for the synthesis of straight or branched chain aliphatic or cycloaliphatic hydroxytelechelating polycarbonates of molecular weight between 500 and 5000, by direct phosgenation of one or more polyols having 2 or 3 hydroxy functions per molecule, some or all of said polyols having a chemical structure in which a single carbon atom bears at least two hydroxymethyl groups, characterized in that the reagents are introduced in such manner that said polyols, having a chemical structure in which a single carbon atom bears at least two hydroxymethyl groups, are all the time either in the exclusive presence of chloroformate functions or in the presence of a 10 % stoichiometric excess of phosgene above the amount necessary for converting all the hydroxy functions of said polyols into chloroformate functions.