Mitsubishi Chemical Industries Limited

Chieko Muramoto

Seiichi Nozawa

Osamu Kishiro

Seigo Okumura

Ken Honma

Atsushi Kasai

A process for producing a copolymeric polyester, which comprises a first step of preparing a copolymeric oligomer by reacting a starting material oligoester or polyester having repeating units of the formula: ##STR1## wherein R.sub.1 is a divalent aromatic hydrocarbon group having from 6 to 10 carbon atoms, a divalent alicyclic hydrocarbon group having from 4 to 20 carbon atoms or/and a divalent aliphatic hydrocarbon group having from 1 to 40 carbon atoms (provided a hydrogen atom in the aromatic ring of the aromatic hydrocarbon group may be substituted by a halogen atom or an alkyl or alkoxy group having from 1 to 4 carbon atoms), and R.sup.2 is a divalent aliphatic hydrocarbon group having from 2 to 40 carbon atoms, a divalent alicyclic hydrocarbon group having from 4 to 20 carbon atoms, or a divalent radical of polyalkylene oxide having a molecular weight of from 80 to 8000, in an amount from 5 to 95 mol % as represented by the amount of the repeating units constituting the oligoester or polyester, with from 5 to 95 mol % of a hydroxycarboxylic acid of the formula:

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Ichikawa, Japan

Chieko Muramoto