Kureha Corporation

Kureha Chemical Industry Company, Limited

Tomohiro Hoshi

Hiroyuki Sato

Yoshinori Suzuki

Kazuyuki Yamane

Tomoyuki Ogawa

Yukichika Kawakami

Yasushi Okada

Fumio Maeda

Kentaro Otawara

Tsutomu Kushida

A process for producing an aliphatic polyester through ring-opening polymerization of a cyclic ester, wherein a partial polymer in a molten state is continuously introduced into a twin-screw stirring device to continuously obtain a partial polymer in a solid pulverized state, the partial polymer is subjected to solid-phase polymerization, and the resultant polymer is melt-kneaded together with a thermal stabilizer to be formed into pellets. As a result, an aliphatic polyester of a high molecular weight and with little discoloration is produced efficiently.

Process for producing aliphatic polyester

A method of purifying a cyclic ester, comprising: mixing a co-distillated liquid comprising a cyclic ester produced by heating depolymerization of a hydroxycarboxylic acid oligomer in the presence of a depolymerization solvent and the depolymerization solvent with an organic solvent for washing which is mutually soluble with the depolymerization solvent and has a lower boiling point than the cyclic ester; subjecting the resultant mixture liquid to liquid-liquid separation into an organic solvent phase containing the depolymerization solvent and a cyclic ester phase containing the organic solvent; and then evaporating the organic solvent from the cyclic ester phase containing the organic solvent to recover the cyclic ester containing a reduced amount of the depolymerization solvent. As a result, purified cyclic ester is recovered at high heat efficiency, purification efficiency and operation efficiency, from the co-distillate liquid containing the depolymerization solvent and the cyclic ester from the depolymerization system for thermal decomposition of the hydroxycarboxylic acid oligomer in the presence of the depolymerization solvent.

Method for purification of cyclic ester

Disclosed is a process for purifying a hydroxycarboxylic acid, comprising: a crystallization step of subjecting a hydroxycarboxylic acid aqueous solution to crystallization for purification, a separation step of separating a hydroxycarboxylic acid crystal from a mother liquid, and a washing step of washing the hydroxycarboxylic acid crystal for further purification with a washing liquid, wherein the washing liquid is a hydroxycarboxylic acid aqueous solution. The purified or refined hydroxycarboxylic acid obtained through the above process is suitably used as a starting material for production of a polyhydroxycarboxylic acid. The above process is suitably included in a process for producing a cyclic ester and a process for producing a polyhydroxycarboxylic acid.

Process for purifying hydroxycarboxylic acid, process for producing cyclic ester, and process for producing polyhydroxycarboxylic acid

A process for producing an aliphatic polyester by subjecting a cyclic ester to ring-opening polymerization, which comprises adding water to a cyclic ester purified to the extent that a water content is at most 60 ppm to control an overall proton concentration in the cyclic ester, thereby controlling at least one physical property among melt viscosity, molecular weight and yellowness index of the resulting aliphatic polyester.

Production process of aliphatic polyester

The invention provides a polyester production process by bulk polymerization in a reactor, wherein the volume of the resulting polyester is shrunk for a release from the inner surface of the reactor, so that the polyester can be recovered in the form of a bulky mass. The invention also provides a reactor for bulk polymerization for polyester, which comprises an inner surface that enabling the resulting polyester to be released therefrom upon its volume shrinkage.

Growing community of inventors

Fukushima-ken, Japan

Tomohiro Hoshi