Verfahren zur Herstellung von thermoplastischen Polymeren

摘要

Polymeric formals containing aromatic ester units are obtained by heating a dihydric alcohol containing an aromatic ester group with formaldehyde. An acid-reacting catalyst may be used. The alcohol may be one capable of forming a polyester on its own, so that both polyformal and polyester formation takes place. The polymer may be further reacted with a cyclic oligomer of formaldehyde to polymerize the oligomer to polyoxymethylene, to obtain a copolymer containing units of the polymeric formal and polyoxymethylene units. In examples polyformals are obtained by reacting bis-hydroxyethyl terephthalate with para-formaldehyde using methanesulphonic acid and p-toluenesulphonic acid as catalysts, and the polyformal is reacted with trioxane in the presence of boron trifluoride dibutyl ether complex. Other suitable dihydric alcohols are mentioned.