JPH0524170B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a method for continuously producing polyethylene terephthalate-based modified polyester copolymerized with diethylene glycol (DEG). (Prior art) Conventionally, polyethylene terephthalate-based modified polyester copolymerized with DEG is well known, and DEG is added during the esterification reaction of terephthalic acid and ethylene glycol, or DEG is added as an esterification reaction product. Bis(β-hydroxyethyl)
It is produced by adding DEG to terephthalate and/or its low polymer (referred to as oligomer) and polycondensing it under heating under reduced pressure. However, the esterification reaction is generally performed on a large scale, and the method of adding DEG during the esterification reaction is not suitable for the production of modified polyester, which is performed on a relatively small scale. Therefore, after the esterification reaction, the oligomer
The method of adding DEG is advantageous; generally, DEG is added directly to the polycondensation reactor, or DEG is added to the polycondensation reactor together with a catalyst etc. in the piping supplying oligomers to the polycondensation reactor immediately before the polycondensation reactor. A method of adding . However, in these methods, the inside of the polycondensation reactor is kept at reduced pressure and high temperature, so the added DEG
Most of the DEG is distilled out of the system, and the DEG residual rate in the polymer is as low as 3% or less. In order to obtain a polymer with a predetermined DEG content, a large amount of DEG is required.
DEG has to be added, resulting in an increase in raw material cost, an increase in heating utility cost, or a decrease in production capacity. (Problems to be Solved by the Invention) The present invention provides a method for continuously producing modified polyester by adding DEG to oligomers and carrying out heating polycondensation under reduced pressure. The present invention aims to provide a method for efficiently producing modified polyester. (Means for Solving the Problems) The present invention achieves the above object, and its gist is to continuously produce modified polyester by adding DEG to oligomers and polycondensing them under reduced pressure. A method for continuous production of modified polyester, characterized in that during production, DEG is added in the middle of the piping supplying the oligomer to the polycondensation reactor at a position where the residence time up to the polycondensation reactor is 5 minutes or more. It is in. Next, the present invention will be specifically described with reference to the drawings. FIG. 1 is a process diagram showing an embodiment of the present invention, in which 1 shows a polycondensation reactor, 2 shows an oligomer supply pipe, 3 shows a DEG addition nozzle, and 4 shows a DEG storage tank. In the middle of the oligomer supply piping 2, place it at a position where the residence time up to the polycondensation reactor 1 is 5 minutes or more.
A DEG addition nozzle 3 is provided, and DEG from the storage tank 4 passes through a metering pump 5 and a check valve 6.
It is added to the oligomer in line 2. Further, a catalyst solution addition nozzle 7 is provided at a position close to the polycondensation reactor 1, usually at a position where the residence time to the polycondensation reactor 1 is within 2 minutes, and the catalyst solution from the storage tank 8 is fed into a metering pump. 9 and check valve 10
It is added to the oligomer in the pipe 2 through the process. (The purpose of adding the catalyst solution close to the polycondensation reactor is to prevent precipitation and precipitation of the catalyst.) 11 is a mixer that uniformly mixes DEG and the catalyst solution with the oligomer to perform polycondensation. It is adapted to be supplied to reactor 1. 12 is a pressure control valve designed to maintain the pressure of the oligomer at a predetermined pressure. 13 is a distillate gas outlet from the polycondensation reactor 1;
14 is a polymer outlet. (Function) According to the method of the present invention, since DEG is retained for 5 minutes or more from the time it is added to the oligomer until it is supplied to the polycondensation reactor, the reaction between DEG and the oligomer proceeds during this time, and the It is recognized that even if DEG is supplied to a high temperature polycondensation reactor, DEG cannot be distilled out of the system and the residual rate of DEG increases. (Example) Next, the present invention will be specifically described with reference to Examples. The amount of DEG in the polymer was determined by heating and hydrolyzing the polymer in a methanol-aqueous solution of potassium hydroxide, cooling it, and analyzing and quantifying the filtrate using a gas chromatograph. Examples and Comparative Examples Modified polyester was produced according to the steps shown in FIG. That is, oligomers are continuously supplied at a predetermined ratio to a polycondensation reactor with an internal temperature of 275°C and a pressure of 25 Torr, and a predetermined amount of DEG is added in the middle of the oligomer supply piping until the residence time to the polycondensation reactor reaches a certain point. The catalyst solution was added at the time shown in Table 1, and the catalyst solution was added in the middle of the oligomer supply piping at a point where the residence time to the polycondensation reactor was 2 minutes, a polycondensation reaction was carried out, and DEG was copolymerized. A modified polyethylene terephthalate polyester was obtained. DEG content and DEG of the obtained polyester
Table 1 shows the survival rate. Note that the DEG content of polyester produced under similar conditions without adding DEG was 2.0 mol%, and the DEG residual rate was calculated taking this into consideration.

[Table] Adhesive addition (effects of the invention) According to the present invention, in the method of continuously producing a modified polyester by adding DEG to an oligomer and carrying out heating polycondensation under reduced pressure, the added DEG
Provided is an efficient method for producing modified polyester with a high residual rate.

[Brief explanation of the drawing]

FIG. 1 is a process diagram showing an embodiment of the present invention. 1: Polycondensation reactor, 2: Oligomer supply piping,
3: DEG addition nozzle.

Claims (1)

[Claims] 1 When diethylene glycol is added to bis(β-hydroxyethyl) terephthalate and/or its low polymer and polycondensed under reduced pressure to continuously produce a modified polyester, bis(β-
A modification characterized in that diethylene glycol is added in the middle of the piping that supplies (hydroxyethyl) terephthalate and/or its low polymer to the polycondensation reactor at a position where the residence time to the polycondensation reactor is 5 minutes or more. Continuous manufacturing method for high quality polyester.