Continuous production system and preparation method of biodegradable copolyester and copolyester

Abstract

The invention discloses a continuous production system and a preparation method of biodegradable copolyester and copolyester. An esterification system in the production system comprises a first esterification kettle and a second esterification kettle which are connected in sequence; the interiors of the first esterification kettle and the second esterification kettle are separated into inner and outer cavity structures by an annular partition plate which is coaxially arranged with a kettle cavity so that reactants in the inner cavity are conveyed to the outer cavity through the partition plate, and conveying outside the kettle is completed. According to the preparation method, sequential esterification of aliphatic dibasic acid and aromatic dibasic acid is realized by utilizing inner and outer chamber structures of the first esterification kettle and the second esterification kettle and a specific catalyst, decarboxylation side reaction is effectively avoided, and the sequence length of an aromatic dibasic acid ester chain segment can be effectively controlled not to be higher than 2, the continuously produced aliphatic-aromatic copolyester has the characteristics of good biodegradability, low terminal carboxyl group content and good hue.

Description

technical field [0001] The invention belongs to the technical field of polymer material synthesis, and in particular relates to a continuous production system and preparation method of biodegradable copolyester and copolyester. Background technique [0002] Biodegradable aliphatic-aromatic copolyester is a copolyester of aliphatic dibasic acid and aromatic dibasic acid and aliphatic diol, which has good biodegradability and flexibility of aliphatic polyester It has good heat resistance and mechanical properties with aromatic polyesters, and has been widely used in the production of shopping bags, agricultural mulch films, express packaging bags, garbage bags, disposable lunch boxes and paper cups, etc. [0003] At present, the continuous polymerization production process of biodegradable aliphatic-aromatic copolyester mainly includes parallel esterification method and co-esterification method. The obtained polyester oligomers enter the polycondensation system for pre-conden...

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Problems solved by technology

[0003] At present, the continuous polymerization production process of biodegradable aliphatic-aromatic copolyester mainly includes parallel esterification method and co-esterification method. Parallel esterification process refers to Aliphatic dibasic acids and aromatic dibasic acids are esterified separately in two esterification tanks, and the obtained polyester oligomers enter the polycondensation system together for pre-condensation reaction and final polycondensation reaction to obtain biodegradable fat The advantage of this esterification process is that it can effectively solve the problem of large temperature gradient in the esterification reaction of aliphatic dibasic acid and aromatic dibasic acid, and can realize the synthesis of aliphatic dibasic acid at low temperature. Esterification avoids high-temperature decarboxylation side reactions; however, aliphatic dibasic acids and aromatic dibasic acid esters tend to generate homopolymers with multiple degrees of polymerization in parallel and independent esterification processes, resulting in the final preparation of biodegradable fats The randomness of the aromatic-aromatic copolyester is reduced, and the content of the aromatic dibasic acid ester segment with a sequence length greater than 2 that is not degradable by microorganisms increases

[0004]The co-esterification process refers to the esterification reaction of aliphatic dibasic acid and aromatic dibasic acid in the same reactor and at the same esterification temperature. Then pre-condensation reaction and final polycondensation reaction are carried out sequentially to obtain biodegradable aliphatic-aromatic copolyester. The advantage of this esterification process is that the process is simple, but it is difficult to find a suitable matching temperature. Efficient esterification of acid and aromatic dibasic acid at the same time may easily cause sublimation or decarboxylation of aliphatic dibasic acid due to high esterification temperature or insufficient esterification of aromatic dibasic acid due to low esterification temperature, resulting in Pipeline clogging accidents are prone to occur during the continuous polymerization of biodegradable aliphatic-aromatic copolyesters, and the intrinsic viscosity of the produced sliced ​​products is low and the content of terminal carboxyl groups is high, which makes biodegradable aliphatic-aromatic copolyesters The processing use of polyester is limited

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