JP2004002902A - Method and apparatus for producing polybutylene terephthalate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a method for continuously producing a polybutylene terephthalate (PBT) which keeps the number of reactors necessary for the reaction to a minimum and minimizes the agitation consumption power necessary for the reaction. <P>SOLUTION: The apparatus for producing a polybutylene terephthalte (PBT) shall have a total of three reactors of one esterification reactor, one initial polymerization reactor and one final polymerization reactor, and the esterification reactor and the initial polymerization reactor shall have no external agitation power source, and the final polymerization reactor shall be a reactor of the horizontal-uniaxial low-speed rotation type. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to a method and apparatus for continuously producing polyester-based polymers such as polybutylene terephthalate and polyethylene terephthalate.

Polybutylene terephthalate (hereinafter abbreviated as PBT) resin has excellent crystallization properties and excellent mechanical properties, electrical properties, heat resistance, etc., and has recently been applied to electrical equipment, electronic parts, mechanical parts, automotive applications, etc. Demand is growing.

Conventionally, as a general method for producing PBT, a dialkyl terephthalate having dimethyl terephthalate as a main component and a glycol having 1,4-butanediol (hereinafter referred to as BD) as a main component are mixed at an appropriate ratio as raw materials. The mixture is placed in a tank, the transesterification catalyst is added and adjusted, and then sent to a transesterification reaction tank set at a predetermined reaction temperature by a pump.

In this transesterification reaction, two to three stirring tanks with stirring blades are arranged in series, and methanol, which is a by-product, tetrahydrofuran (hereinafter referred to as THF) generated by decomposition of BD and water are distilled in a distillation column. To separate. Next, a polymerization catalyst is added and the process proceeds to a polymerization reaction step. First, a plurality of vertical stirring tanks and horizontal stirring tanks are installed as a pre-polymerization step, and a horizontal stirring tank is installed as a final polymerization step. Condensers are installed in the tanks of these polymerization steps to remove BD, THF, and water that are produced as by-products, and the tanks are operated in a high-temperature, reduced-pressure atmosphere.

In the conventional continuous production process of PBT, the number of reactors is 4 to 6 cans, each reactor is equipped with a stirring blade and its power source, and a distillation column and condenser for separating and removing by-products are installed. is set up. In these manufacturing processes, the resin is exposed to a high-temperature reaction state for a long time, so that a part of the polymerized resin is broken by a thermal decomposition reaction so that the degree of polymerization is reduced, and the acid value of the resin (polymer end group Carboxyl group concentration), and the quality deteriorates. Further, since the polymerization step is operated in a reduced-pressure atmosphere, the vacuum means must be operated by another apparatus, and the operation of the production apparatus requires high maintenance costs and equipment costs.

従 来 Japanese Patent Application Laid-Open No. 52-51495 is known as this kind of prior art.

JP-A-52-51495

The problem of the present invention is to improve the known process for the production of high molecular weight polybutylene terephthalate, to increase the efficiency of the whole apparatus and to operate more economically by saving energy of factory equipment.

An object of the present invention is to improve the above-mentioned conventional technology and to suppress the thermal decomposition of the resin during the production by the minimum necessary reactor configuration, to obtain a polymer having good moldability and excellent thermal stability with minimum energy. An object of the present invention is to provide a continuous polycondensation apparatus and a continuous polycondensation method for efficiently reacting a resin having excellent hydrolysis resistance.

The above objective is to use terephthalic acid (hereinafter referred to as TPA) and BD as raw materials for PBT production, a direct esterification reaction step and a polymerization reaction step composed of three or four reaction tanks, and a tank requiring stirring power. This is achieved by minimizing the thermal history of the high temperatures experienced during resin production by reducing the residence time and reducing the unreacted terminal carboxyl groups in the resin.

に よ り With the minimum required reactor configuration, high quality PBT polymer can be efficiently produced with minimum energy cost.

ADVANTAGE OF THE INVENTION According to this invention, the efficiency of the whole apparatus is improved by making the continuous production apparatus of PBT into one reactor of a direct esterification process and three reactors of an initial polymerization process and a final polymerization process, and the energy of the production equipment is improved. It operates more economically with savings.

According to the present invention, a bulk polymerization treatment is performed by adding a reactor for high viscosity treatment to a total of three reactors of a direct esterification process and a total of three reactors of an initial polymerization process and a final polymerization process. Can produce a PBT having a high degree of polymerization, thereby saving energy in production equipment.

Further, according to the present invention, a wide variety of PBTs can be produced by branching the second and subsequent reactors of the PBT continuous production facility into a high polymerization degree production line and a lower polymerization degree production line. . In addition, the production amount of these varieties can be adjusted, and the PBT continuous production facility can be operated economically.

Exemplary embodiments of the present invention are described below:
(1) An oligomer having an average degree of polymerization of 2.2 to 5 or less is produced by reacting an aromatic dicarboxylic acid containing terephthalic acid as a main component or a derivative thereof with a glycol containing 1,4-butanediol as a main component. The second reactor, which produces a low polymer having an average degree of polymerization of 25 to 40 by polycondensing the oligomer from the first reactor and the first reactor, and further polycondensing the low polymer from the second reactor A polybutylene terephthalate continuous production apparatus comprising a third reactor for producing a high molecular weight polyester having good thermal stability and excellent hydrolysis resistance, which is subjected to polycondensation from an average degree of polymerization of 70 to 130, or a terephthalic acid. An aromatic dicarboxylic acid or its derivative as a main component is reacted with a glycol as a main component in 1,4-butanediol to form an orifice having an average degree of polymerization of 2.2 to 5 or less. A first reactor for producing sesame; a second reactor for producing a low polymer having an average degree of polymerization of 25 to 40 by polycondensing the product; and further polymerizing the low polymer to an average degree of polymerization of 70 to 130. A third reactor for producing a high molecular weight polyester by condensation and a fourth reactor for producing a high molecular weight polyester having good thermal stability and excellent hydrolysis resistance by polycondensing the polyester with an average degree of polymerization of 150 to 200; In the continuous production apparatus of polybutylene terephthalate comprising
(I) Do not use a reactor having an agitation function by an external power source for the first and second reactors.
(Ii) The first reactor is a substantially cylindrical vessel-shaped reactor, having an inlet and an outlet for the liquid to be treated at the lower part of the vessel body, and an opening through which volatiles and reaction by-products flow at the upper part of the body. And a calandria type heat exchanger formed in the container main body in the longitudinal direction and close to the inner wall of the main body so as to be immersed in the processing liquid, and the processing liquid supplied from the lower part of the container main body is heated. Heating to a predetermined reaction temperature by an exchanger, and stirring and mixing by natural convection in the vessel due to a density difference caused by a temperature difference between a volatile by-product gas generated at that time and a processing liquid.
(Iii) The second reactor is a flow-type reactor having a substantially cylindrical container shape, and has a double cylindrical structure having an inner cylindrical opening in a container, and a lower part of the double cylindrical structure is provided with a liquid to be treated. The processing liquid has an inlet, and the processing liquid is heated to a predetermined reaction temperature through the tube side of the multi-tube heat exchanger outside the inner cylinder of the double cylindrical structure provided at the upper part thereof, and flows above the container body. To reach the inner tube opening level, flow down the inner tube, and have an opening at the top of the main body through which volatiles and reaction by-products flow.
(Iv) The eighth reactor is a horizontal cylindrical container-type reactor having an inlet and an outlet for the liquid to be treated at one lower end and the other lower end in the longitudinal direction of the container main body, respectively. There is provided a stirring rotor that rotates in proximity to the inside of the main body in the longitudinal direction inside the main body, the stirring rotor inside the main body is constituted by a plurality of stirring blade blocks according to the viscosity of the processing liquid, The stirring blades shall not have a rotating shaft in the center of the stirring rotor.
(V) The fourth reactor is a horizontal, substantially cylindrical container-type reactor having an inlet and an outlet for the liquid to be treated at one lower end and the other lower end in the longitudinal direction of the container main body, respectively. And a stirring rotor that rotates in the longitudinal direction inside the main body and close to the inside of the main body, and each of the rotors has a stirring blade.

(2) An aromatic dicarboxylic acid containing terephthalic acid as a main component or a derivative thereof and a glycol containing 1,4-butanediol as a main component are reacted in a first reactor to obtain an average degree of polymerization of 2.2 to 5 A first step of producing the following oligomer, a second step of producing a low polymer having an average degree of polymerization of 25 to 40 by polycondensing the product in a second reactor, and further subjecting the low polymer to a third reaction In a continuous process for producing polybutylene terephthalate comprising a third step of producing a high molecular weight polyester having good thermal stability and excellent hydrolysis resistance by polycondensation to an average degree of polymerization of 70 to 130 in a vessel, or terephthalic acid Of an aromatic dicarboxylic acid or a derivative thereof having as a main component a glycol having 1,4-butanediol as a main component in a first reactor to form an oligomer having an average degree of polymerization of 2.2 to 5 or less. A second step of producing a low polymer having an average degree of polymerization of 25 to 40 by polycondensing the product in a second reactor, and further subjecting the low polymer to a third reactor. The third step of producing a high molecular weight polyester by polycondensation from an average degree of polymerization of 70 to 130, and the polymer is further polycondensed to an average degree of polymerization of 150 to 200 in a fourth reactor, and has good heat stability and hydrolysis resistance. (I), (ii), (iii), (iv) and (v) according to the above (1) in a continuous process for producing polybutylene terephthalate comprising a fourth step of producing a high molecular weight polyester excellent in the above. And a molar ratio of the aromatic dicarboxylic acid or its derivative mainly composed of terephthalic acid as a raw material to the glycol mainly composed of 1,4-butanediol is 1: 1.7. ~ 1: 3.0 range, the first Degree of temperature 220 ° C. to 250 DEG ° C., the pressure is 33KPa～150kPa, temperature of the second step is 230 ° C. to 255 ° C., the pressure is 100KPa～0.133KPa, temperature of the third step and the fourth step 230 ° C. ~
255 ° C., the pressure is in the range of 0.665 kPa to 0.067 kPa, the rotation speed of the stirring blades of the third and fourth reactors is from 0.5 rpm to 10 rpm, the first step, the second step The total reaction time of the third step is between 4 and 7.5 hours, or the total reaction time of the first step, the second step, the third step and the fourth step is 6 to 8.5 hours. The aromatic dicarboxylic acid containing terephthalic acid as the main component and the glycols containing 1,4-butanediol as the main component have a molar ratio of the former to the latter of 1: 1.7 to 1: 3.0. The prepared slurry is added to the esterification reaction catalyst or the polymerization reaction catalyst and supplied to the first step. A plurality of third reactors are provided in parallel with the third reactor in the third step, Different polymerization degrees of different grades produced in the main series of 4th and 3rd reactors It is characterized in that by increasing the number of types of polybutylene terephthalate produced or adjusting the operating conditions for each third reactor, the number of types of polybutylene terephthalate to be produced, detailed quality adjustment management, and control of the production amount are performed.

FIG. 1 shows an embodiment of the present invention. FIG. 1 is an apparatus training diagram of a continuous PBT manufacturing process of the present invention. As an industrial polyester production method, the direct esterification method is very economically advantageous. Therefore, in recent years, the direct esterification method has often been adopted for the production of polyester. In FIG. 1, reference numeral 1 denotes a raw material adjusting tank for mixing and stirring TPA and BD, which are raw materials of PBT, at a predetermined ratio. In the production process, additives such as a polymerization reaction catalyst, a stabilizer, and a quality control agent may be added at this stage. In this embodiment, the polymerization reaction catalyst and the additives are used as raw materials immediately before the entrance to the esterification reaction tank. The catalyst is supplied from the catalyst supply line 10 to the supply line 2 and supplied to the esterification reaction tank. Examples of the polymerization catalyst include known metal compounds such as organic titanium, organic tin, and organic zirconia. Depending on the type and combination of the catalyst used, not only the reaction rate differs, but also the hue and thermal stability of the PBT produced. It is well-known that it has a great effect on the quality of the product. In particular, it is known that the catalyst of an organic titanium compound is affected by the moisture present in the surroundings, and the catalytic action is reduced. In this embodiment, the catalyst is added immediately before the entrance of the esterification reaction tank to minimize this effect.

こ と This allows the added catalyst to minimize the deactivation ratio, thereby reducing the amount of catalyst to be added and producing a resin having a good hue. Furthermore, since these reactions are carried out at a high temperature for a long time in the presence of a catalyst, various side reactions are involved, and the polymer is colored, and the content of THF and the concentration of terminal carboxyl groups are increased to appropriate values. Physical properties such as quality deterioration and strength of the PBT are deteriorated.

新 し い New catalysts have been developed to solve these problems, but the most industrially used organic titanium is currently superior in price and performance. However, even if this catalyst is used, coloring of the produced polyester polymer cannot be avoided. For this reason, the use of a phosphorus-based stabilizer (for example, phosphoric acid, trimethyl phosphate, triphenyl phosphate, etc.) as a stabilizer has been improved. Further, in another manufacturing process, the quality is stabilized by devising a position where a polymerization catalyst and a stabilizer are charged. In a normal process, the amount of the catalyst is preferably 20 to 100 ppm in terms of titanium metal, and the amount of the stabilizer is preferably 0 to 600 ppm in terms of P metal, if necessary.

The raw material and the catalyst adjusted as described above are supplied via a catalyst addition line 10 which is adjusted at a different place from the supply line 2 for supplying the raw material to the first esterification reaction tank 3 and joins the supply line 2. Is done. The outer periphery of the esterification reaction tank (first reactor) 3 has a jacket structure (not shown) for keeping the processing liquid at a reaction temperature, and a calandria type heat exchange as a liquid heating means is provided inside the liquid. The processing solution flowing in the multi-tube is heated by an external heat source, and the internal liquid is only circulated by natural circulation due to the synergistic effect of the density change and the temperature difference caused by the volatile gas generated in the esterification reaction step. The reaction proceeds while circulating.

Here, the most desirable reactor type is a calandria type in which the processing solution in the reactor is naturally circulated by utilizing the spontaneous evaporation of by-products produced by the esterification reaction. Since this type of reactor does not require an external stirring power source, there is an advantage that the apparatus configuration is simple, a shaft sealing device for the stirring shaft is not required, and the production cost of the reactor is reduced. As an example of such a reactor, an apparatus as shown in JP-A-10-85501 is desirable. However, the present invention is not limited to this apparatus, and a reactor having a stirring blade may be used for process reasons.

In the first reactor 3, the water generated by the reaction takes the form of water vapor, and forms the gas phase 5 together with the vaporized BD vapor and the by-produced THF vapor. As reaction conditions to be recommended at this time, the temperature is preferably from 220 ° C. to 250 ° C. and reduced pressure or slightly pressurized condition is desirable. In particular, the optimum pressure condition is determined by the molar ratio of BD and TPA of the raw material (hereinafter referred to as B / T). When B / T = 2.0 or more (including 2.0), even if the pressure is at or above atmospheric pressure, the BD concentration in the processing solution is ensured. , B / T = 2.0 or less (excluding 2.0), the esterification rate decreases, the reaction load in the subsequent polymerization step increases, and the vacuum system and auxiliary equipment related thereto become disadvantageous. The resulting problem arises.

た め For this reason, when B / T = 2.0 or less (excluding 2.0), it is effective to set the reaction pressure condition to a reduced pressure condition at or below atmospheric pressure. By reducing the pressure, the boiling point of BD decreases and the reaction temperature can be lowered. Normally, when the reaction temperature is lowered, the reaction rate is reduced. However, in a natural circulation type reactor such as the structure of this embodiment, the gas volume of the reaction by-product increases due to the reduced pressure, and the circulation in the reactor is reduced. It is effective for improving the reaction conditions by increasing the performance.

By reducing the pressure, the rate of desorption of water, which is a by-product of the esterification reaction, is also improved, and the positive reaction rate constant is increased. Further, the esterification reaction time is shortened by improving the esterification reaction rate, and the effect of reducing the amount of THF as a by-product is exerted in synergy with the effect of lowering the reaction temperature. It can be greatly reduced. The recommended reaction temperature at this time is 220 ° C. to 250 ° C., especially when the pressure is 50 to 80 kPa or less at atmospheric pressure, the residence time is 1.5 to 2.4 hours, and the reaction temperature is 225 ° C. to 230 ° C. Has a significant effect on improving the esterification reaction rate and reducing the amount of THF produced. The amount of THF formed at this time is about 15 to 25 mol% / h 2 in terms of the mole fraction of the raw material TPA.

The gas in the gas phase 5, which is a volatile component coming out of the processing liquid, is separated into water, THF and BD by a distillation column (not shown) provided above the first esterification reaction tank 3, and And THF are removed out of the system, and the BD is returned to the BD tank 33 via a BD circulation line 35 from the lower part of the distillation tower for use in the system or as a raw material again through a purification step or the like. The circulating BD is supplied from the BD tank 33 to the raw material adjustment tank 1 through the BD supply line 34. The circulating BD in the BD tank 33 is subjected to a BD purification process (not shown) as necessary to adjust the purity of the raw material BD. I do. Further, if necessary, the circulating BD discharged from the wet condenser (not shown) of the decompression device installed in the initial polymerization machine 14 and the final polymerization machine 18 is returned to the BD tank 33 through the BD circulation line 36, and the BD basic unit is used. To further improve. In this case, the new BD is supplied from the new BD supply line 39 to the wet condenser of the third reactor 18, is supplied from the BD circulation line 37 to the wet condenser of the second reactor 14, and is supplied from the BD circulation line 36 to the BD tank 33. Supply.

(4) The processing solution that has reached a predetermined esterification rate in the esterification reaction tank 3 is supplied to the initial polymerization reaction tank (second reactor) 16 via the communication pipe 6. A control valve 7 for adjusting the flow rate of the processing liquid is provided in the middle of the communication pipe 6. With this valve, the liquid level in the first reactor is controlled to be constant, and the reaction time is kept constant. When the treatment liquid reaches a predetermined esterification rate in the esterification reaction tank 3, it is supplied to the initial polymerization tank (second reactor) 14 by the oligomer pump 12 provided in the middle of the communication pipe 11. The treatment liquid supplied to the initial polymerization tank is heated to a predetermined reaction temperature by the multitubular heat exchanger 15 to perform a polycondensation reaction to increase the degree of polymerization. At this time, the reaction conditions are 230 ° C. to 255 ° C., the pressure is 100 kPa to 0.133 kPa, the residence time is 1.0 to 1.5 hours, and the degree of polymerization is from 25 to 40.

初期 Although the initial polymerization tank 14 shown in the present embodiment is described using a reactor having no stirring blade, this reactor is not limited. However, in the initial polymerization stage, the reaction is a stage in which the polymerization reaction rate is controlled, and the reaction proceeds smoothly if a sufficient amount of heat required for the reaction is supplied. From this viewpoint, the treatment liquid does not need to be subjected to unnecessary stirring action by the stirring blade, and it is sufficient that the BD generated by the polycondensation reaction is released from the system. Furthermore, in order to maintain the quality of the resin to be produced well and to suppress the amount of by-product THF, it is better to operate the reaction at a temperature as low as possible. The recommended reaction temperature is 250 ° C or less (including 250 ° C). desirable. As an optimal reactor for such an operation, an apparatus as shown in JP-A-10-76102 is optimal. The BD, water and THF generated by the reaction are collected in the gas phase 16 maintained in a reduced pressure atmosphere, condensed by a condenser provided downstream thereof, and then discharged outside the system. After a predetermined reaction time has passed in the initial polymerization tank (second reactor) 14, the processing liquid is supplied to a final polymerization machine (third reactor) 18 through a communication pipe 17. In the final polymerization machine, a polycondensation reaction is further promoted while undergoing a good surface renewing action by a stirring blade 19 having no stirring shaft at the center driven by the external power source 21 to increase the polymerization degree and produce a polymer having a desired polymerization degree. I do.

As an apparatus most suitable as a final polymerization machine (third reactor), an apparatus described in JP-A-16-77348 has the best surface renewal performance and power consumption characteristics. At this time, the reaction conditions are 230 ° C. to 255 ° C., the pressure is 0.665 kPa to 0.067 kPa, and the degree of polymerization is from 70 to 130. Conventionally, polycondensation was carried out in two tanks because the viscosity range of the treatment liquid was wide. However, polycondensation can be carried out with one apparatus of the final polymerization machine, and a significant reduction in equipment cost can be obtained. The total residence time in the first to third reactors 3 to 18 is preferably from 4 to 7.5 hours, but from the viewpoint of quality, the residence time of the entire polymerization step is in the optimal range of 2 to 4 hours. . Also, the residence time can be lengthened by adjusting the temperature and pressure, if necessary, e.g., when reducing production, implemented to keep quality fluctuations to a minimum. is there. In particular, in order to lower the value of the polymer acid value, which is one of the evaluation items of the quality of PBT, as much as possible, it is desirable to set the reaction temperature to 250 ° C. or lower (including 250 ° C.).

When the PBT is continuously manufactured in the above-described apparatus configuration, the number of reactors is reduced as compared with the conventional apparatus configuration, so that the manufacturing cost of the apparatus can be reduced. It has the advantage that the number of towers and condensers can be reduced and the piping, instrumentation parts, valves, etc. connecting them can be greatly saved, and the running costs can be reduced because the utility-related costs such as vacuum sources and heating medium devices are greatly reduced. .

Further, in order to obtain a PBT having a higher IV value, the PBT can be produced by installing another final polymerization reactor (fourth reactor) after the final polymerization reactor (third reactor) 18. This embodiment is shown in FIG. The configuration and operation of the first, second and third reactors are the same as in the embodiment of FIG. The supply of the new BD is supplied to the wet condenser of the fourth reactor 28 and the BD circulation line 38 to the wet condenser of the third reactor 23, and the same operation as the embodiment of FIG. 1 is performed. The processing liquid 20 reacted in the third reactor to a degree of polymerization of about 70 to 130 is sent to the fourth reactor 23 by the polymer pump 22 provided between the connecting pipe connecting the third reactor 18 and the fourth reactor 23. Can be Since the viscosity of the processing liquid in the fourth reactor 23 is as high as several hundred kPa · s, the stirring device of the type used in the third reactor 18 can no longer be used. The phenomenon that the stagnation occurs is caused. For this purpose, a reactor having a stirring device for treating a high-viscosity liquid must be used. As the most suitable apparatus for this reactor, a two-shaft apparatus such as the apparatus described in Japanese Patent Publication No. Hei 6-21159 and Japanese Patent Application Laid-Open No. 48-102894 (Japanese Patent No. 10224745) is excellent for high viscosity liquid treatment. I have. In particular, in this embodiment, the explanation will be made by using a spectacle wing type polymerization apparatus described in JP-A-48-102894 (Japanese Patent No. 10224745), but the invention is not limited to this polymerization apparatus.

The fourth reactor 23 attaches a pair of glasses-shaped stirring blades 24 to the stirring shaft driven by the external power source 25 at predetermined intervals with a phase difference of 90 degrees. This is a two-shaft polymerization device configured with a mark. The processing liquid supplied from the inlet is extended outward due to the configuration in which the stirring blades rotate from the center to the outside. At this time, the treatment liquid undergoes a good surface renewal action, evaporating volatile components from the inside of the treatment liquid to promote the reaction, and further increases the viscosity to be discharged as the polymer 24 having a high polymerization degree. The reaction conditions are as follows: the temperature is from 230 ° C. to 255 ° C., the pressure is from 0.665 kPa to 0.067 kPa, the residence time is from 0.7 to 1.5 hours, and the degree of polymerization is from 150 to 200.

(3) An embodiment in which polybutylene terephthalate of a different type is simultaneously produced will be described with reference to FIG. In the embodiment shown in FIG. 3, another third reactor 26 is installed in parallel with the equipment for producing polybutylene terephthalate having a high degree of polymerization shown in FIG. The new BD is supplied to the respective wet condensers of the fourth reactor and the third reactor from the supply line 39, and passes through the BD circulation lines 38, 39, and 36 as described with reference to FIGS. To the BD tank 33. The third reactors 18 and 26 will be described using the reactor described in the embodiment of FIG. 1, but the present invention is not limited to this reactor. The processing liquid discharged from the second reactor 14 branches off in the middle of the communication pipe 17, and one part of the processing liquid is guided to the third reactor 18 via the flow control valve 31, while the other part is branched. It is led to the third reactor 26 via the branch connecting pipe 30 and the flow control valve 32.

Here, the embodiment of the present invention will be described with respect to an example of branching into two, but is not limited to two. One of the branched treatment liquids passes through the third reactor 18 and the fourth reactor 23 to produce polybutylene terephthalate having a high degree of polymerization. The other processing solution produces polybutylene terephthalate having a lower polymerization degree than the above-mentioned degree of polymerization in the third reactor 26. This series of polybutylene terephthalate products can be manufactured at any desired ratio by adjusting the flow control valves 31,32. Although not shown in the example of FIG. 3, by adding a third reactor, reaction conditions different from those of the third reactor 26 are set. Production of terephthalate, production of polybutylene terephthalate with a slightly changed degree of polymerization, and adjustment of the production amount can be performed. The rotation speed range of the stirring blades of the third and fourth reactors is 0.5 to 10 rpm.

(Concrete example)
Hereinafter, the present invention will be described specifically with reference to specific examples, but the present invention is not limited to these specific examples. The limiting viscosity of a specific example is 50% by weight of phenol and 50% of tetrachloroethane.
It is a value determined by measuring with an Ostwald viscometer at 30 ° C. using a wt% solvent. The acid value is a value measured by dissolving PBT under heating at 230 ° C. for 5 minutes using benzyl alcohol as a solvent and performing neutralization titration. As shown in Table 1, PBT was produced by continuous operation of the direct esterification method of TPA and BD. In Examples 1 to 3, PBT was produced under reduced pressure esterification reaction conditions, and an intrinsic viscosity of 0.85 dl / g was achieved only by melt polymerization. As shown in Example 1, in the case of the esterification reaction under reduced pressure, a high-quality PBT having an acid value of 10 eq / ton was obtained under the conditions of a low reaction temperature and a short residence time. The total reaction time at this time was 5.2 hours, and it was confirmed that polybutylene terephthalate can be efficiently produced continuously by the apparatus configuration and reaction conditions of the present invention. In order to reduce the acid value of PBT, it is effective to lower the temperature in the final polymerization reaction step and to shorten the residence time.

Of course, the esterification reaction can be performed not only under the reduced pressure conditions of Examples 1 to 3 but also under a pressurized condition.

The present invention is applicable to continuous production of polyester polymers such as polybutylene terephthalate and polyethylene terephthalate.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an apparatus configuration diagram of a PBT continuous manufacturing process showing one embodiment of the present invention. FIG. 11 is a diagram illustrating the configuration of a continuous PBT manufacturing process according to another embodiment of the present invention. FIG. 11 is a diagram illustrating the configuration of a continuous PBT manufacturing process according to another embodiment of the present invention.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 ... Raw material adjustment tank, 2 ... Raw material supply line, 3 ... 1st esterification reaction tank, 4 ... Heat exchanger, 5 ... Gas phase part, 6 ... Connecting pipe, 7 ... Control valve, 10 ... Catalyst supply line, 11 ... connecting pipe, 12 ... oligomer pump, 14 ... initial polymerization tank, 15 ... heat exchanger, 16 ... gas phase section, 17 ... connecting pipe, 18, 23, 26 ... final polymerization machine, 19, 23, 27 ... stirring blade , 20, 24, 28 ... polymer, 21, 25, 29 ... stirring power source, 22 ... polymer pump, 31, 32 ... flow control valve.

Claims (17)

First, an oligomer having an average degree of polymerization of 2.2 to 5 or less is produced by reacting an aromatic dicarboxylic acid having terephthalic acid as a main component or a derivative thereof with glycols having 1,4-butanediol as a main component. A second reactor for producing a low polymer having an average degree of polymerization of 25 to 40 by polycondensing the oligomer from the first reactor and the low polymer obtained from the second reactor; An apparatus for producing polybutylene terephthalate, comprising: a third reactor for producing a high molecular weight polyester having good thermal stability and excellent hydrolysis resistance by polycondensation from an average degree of polymerization of 70 to 130; (2) A continuous production apparatus for polybutylene terephthalate using a reactor having no stirring function by an external power source. First, an oligomer having an average degree of polymerization of 2.2 to 5 or less is produced by reacting an aromatic dicarboxylic acid having terephthalic acid as a main component or a derivative thereof with glycols having 1,4-butanediol as a main component. A second reactor for producing a low polymer having an average degree of polymerization of 25 to 40 by polycondensing the formed product with an adult product, and further polymerizing the low polymer to an average degree of polymerization of 70 to 130 to produce a high molecular weight polyester. Polybutylene terephthalate comprising a third reactor to be produced and a fourth reactor to further polycondensate the polyester to an average degree of polymerization of 150 to 200 to produce a high molecular weight polyester having good thermal stability and excellent hydrolysis resistance. In the manufacturing apparatus, the first reactor and the second reactor use a reactor having no stirring function by an external power source, and a continuous production of polybutylene terephthalate. Apparatus. The first reactor according to claim 1 or 2, wherein the first reactor is a substantially cylindrical container-shaped reactor, having an inlet and an outlet for a liquid to be treated at a lower portion of a container body, and a volatile substance and a reaction by-product at an upper portion of the body. Has an opening through which a calandria type heat exchanger formed close to the inner wall of the main body in the longitudinal direction of the main body is provided so as to be immersed in the processing liquid, and is supplied from the lower part of the main body of the container. A processing liquid is heated to a predetermined reaction temperature by a heat exchanger, and is stirred and mixed by natural convection in a container due to a density difference caused by a temperature difference between a volatile by-product gas generated at that time and the processing liquid. . The second reactor according to claim 1 or 2, wherein the second reactor is a flow-type reactor having a substantially cylindrical container shape, and has a double cylindrical structure having an inner cylindrical opening in the container. The lower part has an inlet for the liquid to be treated, and the processing liquid is heated to a predetermined reaction temperature through the tube side of the multi-tube heat exchanger outside the inner cylinder having a double cylindrical structure provided at the upper part. A device that flows above the container body to reach the inner tube opening level, flows down the inner cylinder, and has an opening at the top of the body through which volatiles and reaction by-products flow. The third reactor according to claim 1 or 2, wherein the third reactor is a horizontal cylindrical container-type reactor having an inlet and an outlet for a liquid to be treated at one lower end and one lower end in the longitudinal direction of the container body, respectively. A stirring rotor having an outlet for volatiles at the top of the main body and rotating in the longitudinal direction inside the main body and close to the inside of the main body is provided, and the stirring rotor inside the main body has a plurality of stirring blades according to the viscosity of the processing liquid. An agitator with no rotating shaft at the center of the agitation rotor. In claim 2, the fourth reactor is a horizontal, substantially cylindrical container-type reactor, and has an inlet and an outlet for the liquid to be treated at one lower end and the lower end at the other end in the longitudinal direction of the container main body. An apparatus which is a reactor having a stirring blade composed of two stirring rotors having an outlet for volatiles and rotating close to the inside of the main body in the longitudinal direction inside the main body. An oligomer having an average degree of polymerization of 2.2 to 5 or less is obtained by reacting an aromatic dicarboxylic acid containing terephthalic acid as a main component or a derivative thereof with glycols containing 1,4-butanediol as a main component in a first reactor. A second step of producing a low polymer having an average degree of polymerization of 25 to 40 by polycondensing the product in a second reactor; and further averaging the low polymer in a third reactor. In the method for producing polybutylene terephthalate, which comprises the third step of producing a high molecular weight polyester having good thermal stability and excellent hydrolysis resistance by polycondensing from a polymerization degree of 70 to 130, the third reactor has a horizontal cylindrical shape. The container-type reactor has an inlet and an outlet for the liquid to be treated at one lower end and the lower end at the other end in the longitudinal direction of the container body, has an outlet for volatiles at the upper part of the body, and has a main body in the longitudinal direction inside the body. Inside Is provided, and the stirring rotor inside the main body is composed of a plurality of stirring blade blocks according to the viscosity of the processing liquid, and the stirring blade does not have a rotating shaft at the center of the stirring rotor. A continuous production method of polybutylene terephthalate. An oligomer having an average degree of polymerization of 2.2 to 5 or less, which is obtained by reacting an aromatic dicarboxylic acid containing terephthalic acid as a main component or a derivative thereof with glycols containing 1,4-butanediol as a main component in a first reactor. A second step of producing a low polymer having an average degree of polymerization of 25 to 40 by polycondensing the product in a second reactor; and further averaging the low polymer in a third reactor. The third step of producing a high molecular weight polyester by polycondensation from a polymerization degree of 70 to 130, and further polymerizing the polymer in an average polymerization degree of 150 to 200 in a fourth reactor to have good heat stability and excellent hydrolysis resistance. In the method for producing polybutylene terephthalate comprising the fourth step of producing a high-molecular-weight polyester, the third reactor is a horizontal, substantially cylindrical container-shaped reactor and includes a lower end of one end in the longitudinal direction of the container body. And two stirring rotors, each having an inlet and an outlet for the liquid to be treated at the bottom of the other end, having an outlet for volatiles at the top of the main body, and rotating close to the inside of the main body in the longitudinal direction inside the main body. Yes, the stirring rotor inside the main body is composed of a plurality of stirring blade blocks according to the viscosity of the processing liquid, the stirring blade does not have a rotating shaft at the center of the stirring rotor, and the fourth reactor is a horizontal cylinder. The reactor has a shape of a container, and has an inlet and an outlet for the liquid to be treated at one lower end and the lower end at the other end in the longitudinal direction of the container body, an outlet for volatile matter at the upper part of the body, and a main body in the longitudinal direction inside the body. A continuous production method of polybutylene terephthalate, which is a reactor having a stirring blade composed of two stirring rotors rotating close to the inside of the container. An oligomer having an average degree of polymerization of 2.2 to 5 or less is obtained by reacting an aromatic dicarboxylic acid containing terephthalic acid as a main component or a derivative thereof with glycols containing 1,4-butanediol as a main component in a second reactor. A second step of producing a low polymer having an average degree of polymerization of 25 to 40 by subjecting the product to polycondensation in a second reactor, and further averaging the low polymer in a third reactor. A third step of producing a high molecular weight polyester having good thermal stability and excellent hydrolysis resistance by polycondensation from a polymerization degree of 70 to 130, wherein terephthalic acid as a raw material is used as a main component. A glycol having an aromatic dicarboxylic acid or a derivative thereof and 1,4-butanediol as main components is supplied in a molar ratio of the former to the latter in the range of 1: 1.7 to 1: 3.0. It continued manufacturing equipment. 8. The method according to claim 7, wherein the molar ratio of the aromatic dicarboxylic acid or its derivative mainly composed of terephthalic acid as a raw material and the glycol mainly composed of 1,4-butanediol is 1: 1.7. Is supplied in the range of 工程 1: 3.0, the temperature of the first step is 220 ° C. to 250 ° C., the pressure is 33 kPa to 150 kPa, the temperature of the second step is 230 ° C. to 255 ° C., and the pressure is 100 kPa to 0.133 kPa. A continuous production method in which the third step is performed at a temperature of 230 ° C. to 255 ° C. and a pressure of 0.665 kPa to 0.067 kPa. 9. The composition according to claim 8, wherein the molar ratio of the aromatic dicarboxylic acid or its derivative mainly composed of terephthalic acid as a raw material and the glycol mainly composed of 1,4-butanediol is 1: 1.7. Is supplied in the range of 工程 1: 3.0, the temperature of the first step is 220 ° C. to 250 ° C., the pressure is 33 kPa to 150 kPa, the temperature of the second step is 230 ° C. to 255 ° C., and the pressure is 100 kPa to 0.133 kPa. A continuous manufacturing method in which the temperature of the third step and the fourth step is 230 ° C. to 255 ° C., and the pressure is 0.665 kPa to 0.067 kPa. (8) The continuous production method according to (7), wherein the rotation speed of the stirring blade of the third reactor is from 0.5 rpm to 10 rpm. (10) The continuous production method according to (8), wherein the rotation speed range of the stirring blades of the third and fourth reactors is 0.5 rpm to 10 rpm. The continuous production method according to claim 7, wherein the total reaction time of the first step, the second step, and the third step is operated between 4 and 7.5 hours. The method according to claim 8, wherein the total reaction time of the first step, the second step, the third step, and the fourth step is between 6 and 8.5 hours. In Claim 7 or Claim 8, the aromatic dicarboxylic acid containing terephthalic acid as a main component and the glycols containing 1,4-butanediol as a main component have a molar ratio of the former to the latter of 1: 1.7 to 1: 3. A continuous production method in which the slurry adjusted to 2.0 is added with an esterification reaction catalyst or a polymerization reaction catalyst and supplied to the first step. 9. The continuous production method according to claim 8, wherein a plurality of third reactors are provided in parallel with the third reactor in the third step.

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