JP2000327762A - Production and manufacturing equipment for polybutylene terephthalate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a continuous production process for PBT that minimizes the reactors that are needed for the reactions and minimizes the power consumption in agitation needed for the reaction. SOLUTION: This PBT production system comprises three tanks of the transesterification reactor 3, the initial polymerization reactor 7 and the final polymerization reactor 11 where the transesterification reactor 3 and the initial polymerization reactor 7 have no outer power source for agitation equipped, while the final polymerization reactor 11 is a horizontal type and made slowly rotatable around the single shaft. The construction of the reactor system is minimized and the PBT polymer of high quality can be produced efficiently in the minimized energy costs.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a continuous production method and apparatus suitable for continuous production of polyester-based polymers such as polybutylene terephthalate and polyethylene terephthalate, especially polybutylene terephthalate.

[0002]

2. Description of the Related Art Polybutylene terephthalate (hereinafter referred to as PB)
Resins have excellent crystallization properties and excellent mechanical properties, electrical properties, heat resistance, etc., and have recently been applied to electrical, electronic, mechanical, and automotive applications, and demand has steadily increased. I have.

The following method is considered as a method for manufacturing PBT. Dialkyl terephthalate containing dimethyl terephthalate as a main component and 1,4-
Glycol containing butanediol (hereinafter referred to as BD) as a main component is put in a mixing tank at an appropriate ratio, a transesterification catalyst is added and adjusted, and then the mixture is transferred to a transesterification reaction tank set at a predetermined reaction temperature by a pump. send. In this transesterification reaction, two to three stirring tanks with stirring blades are arranged in series, and methanol as a by-product and tetrahydrofuran generated by decomposition of BD (hereinafter referred to as THF)
And water are separated in a distillation column. 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 are operated in a reduced pressure atmosphere. In the conventional continuous production process of PBT, the number of reactors is 4
Each reactor is equipped with a stirring blade and its power source, and a distillation column and a condenser for separating and removing by-products are installed. 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.

[0004]

In the above manufacturing method,
It requires a lot of equipment and requires a large amount of energy to operate factory equipment, which is considered to be economically inferior.

An object of the present invention is to provide a method and an apparatus for continuously producing polybutylene terephthalate which are excellent in economical efficiency.

Another object of the present invention is to provide a continuous polycondensation apparatus and a continuous polycondensation method for efficiently reacting high-quality polybutylene terephthalate with minimum energy by using a minimum necessary reactor configuration. .

[0007]

SUMMARY OF THE INVENTION The object of the present invention is to provide a method for producing PBT by using terephthalic acid (hereinafter referred to as TPA) and 1,4.
-Butanediol (BD), the direct esterification reaction step, the pre-polymerization reaction step, and the final polymerization reaction step are each made into one tank, and the tank requiring stirring power is only provided in the final polymerization step.

[0008]

FIG. 1 shows an embodiment of the present invention.
FIG. 1 is an apparatus training diagram of a PBT continuous manufacturing process according to the present invention. As an industrial method for producing polybutylene terephthalate, the direct esterification method is very economically advantageous. In the figure, reference numeral 1 denotes TPA and BD, which are raw materials of PBT.
Is a raw material adjustment tank for mixing and stirring at a predetermined ratio. At this stage, additives such as a polymerization reaction catalyst, a stabilizer, and a quality control agent may be added. Examples of polymerization catalysts include metal compounds such as organic titanium, organic tin, and organic zirconia. Depending on the type and combination of catalysts used, not only the reaction rate differs, but also the quality of the resulting PBT, such as hue and thermal stability. Has a great effect on Furthermore, these reactions are carried out at a high temperature for a long time in the presence of a catalyst, so that 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. P
Physical properties such as quality deterioration and strength of the BT are deteriorated. In order to solve such a problem, the most widely used organic titanium at present is excellent in price and performance. However, even if this catalyst is used, coloring of the produced polybutylene terephthalate polymer cannot be avoided. For this reason, phosphorus stabilizers (for example, phosphoric acid, trimethyl phosphate, triphenyl phosphate, etc.) are used in combination as stabilizers to improve the stability. Further, as another manufacturing process, it is conceivable to stabilize the quality by devising a charging position of the polymerization catalyst and the stabilizer. In a normal process, the amount of the catalyst is 20 to 85 ppm in terms of titanium metal, and the amount of the stabilizer is 0 to 600 ppm in terms of P metal as necessary.
It is preferable to use The raw material adjusted as described above is supplied to the esterification reaction tank 3 via the supply line 2 that supplies the raw material. Esterification reaction tank (first reactor) 3
Has a jacket structure (not shown) for keeping the processing liquid at a reaction temperature, and a multi-can heat exchanger 4 is installed inside the liquid as a heating means for the liquid, and a heat source from the outside is used. The reaction liquid is heated, and the reaction proceeds while circulating the internal liquid by natural circulation. Here, the most desirable type of reactor is a calandria type in which the processing solution in the reactor is naturally circulated by utilizing the evaporating action of a by-product produced by the self-reaction of 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, the shaft sealing device for the stirring shaft is not required, and the production cost of the reactor is low. As an example of such a reactor, an apparatus as disclosed in Japanese Patent Application No. 8-249767 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, water generated by the reaction becomes steam, and forms a gas phase portion 5 together with the vaporized BD vapor and THF vapor. The recommended reaction conditions at this time are preferably a temperature of 220 to 270 ° C. and a pressurized condition. The gas in the gas phase 5 is supplied to a rectification tower (not shown) provided on the upstream side thereof with water, THF and BD.
And BD are removed outside the water and THF system, and the BD is returned to the system again through a purification step and the like. As an advantage of the present invention, it is possible to reduce the number of rectification towers by treating the esterification step in one reactor, and not only the production cost of the rectification tower but also the control of the number of pipes and valves. The number and the like can be reduced, resulting in a significant reduction in equipment cost. Usually, the reaction time required for esterification is 2 to 5 hours, but the optimum value for the optimum reaction time is determined by the mixing ratio of the starting materials TPA and BD, the reaction temperature and the pressure. The processing solution having passed a predetermined reaction time in the esterification reaction tank 3 reaches a predetermined esterification rate,
The oligomer is supplied to the initial polymerization tank (second reactor) 7 by an oligomer pump 15 provided in the middle of the connecting pipe 6. Further, an intermediate addition device 16 is provided in the connecting pipe, and a polymerization catalyst is added or added, and an additive is charged as necessary. There is no problem to add various additives usually used in this intermediate device, for example, an antistatic agent and an ultraviolet absorber, and a dispersing device such as a static mixer or an in-line mixer is installed in a connecting pipe downstream of the adding device. You may. Thereafter, the treatment liquid supplied to the initial polymerization tank is heated to a predetermined reaction temperature by the heat exchanger 8 to perform a polycondensation reaction, thereby increasing the degree of polymerization. The reaction conditions at this time are from 220 degrees to 2 degrees.
The pressure is 266 Pa to 133 Pa at 80 degrees and the polymerization degree is 20
To about 40. Although the initial polymerization tank shown in the present embodiment is described using a reactor having no stirring blade, it is not necessarily limited to this type of reactor. However, in the initial polymerization stage, the reaction is a stage in which the polymerization reaction rate is governed by the reaction speed, and the reaction proceeds smoothly if a sufficient amount of heat required for the reaction is supplied. From this point of view, 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 separated out of the system. As an optimal reactor for such an operation, an apparatus as disclosed in Japanese Patent Application No. 8-233855 is desirable. BD, water and THF generated by the reaction are vaporized in the gas phase part 9 kept in a reduced pressure atmosphere, condensed by a condenser provided on the upstream side thereof, and then discharged out of the system. As an advantage of the present invention, it is possible to reduce the number of condensers by processing the initial polymerization process in one reactor, thereby reducing not only the production cost of the condenser but also the number of piping and valves and the number of control devices. As a result, the cost of the apparatus is greatly reduced. After a predetermined reaction time has passed in the initial polymerization tank (second reactor) 7, the processing liquid is supplied to the final polymerization machine (third reactor) 11 through the communication pipe 10. In the final polymerization machine, the polycondensation reaction is further promoted while undergoing a good surface renewing action by the stirring blade 12 having no stirring shaft at the center to increase the degree of polymerization to produce a polymer having a desired degree of polymerization. Final polymerization machine (3rd
The most suitable device for the reactor is Japanese Patent Application No. Hei 8-2338.
The device described in the specification of No. 57 has the best surface renewal performance and power consumption characteristics. In addition, since the viscosity range of the processing liquid is wide, the processing which has been conventionally performed by dividing the processing liquid into two tanks can be performed by one apparatus, and the cost of the apparatus can be greatly reduced. From the viewpoint of quality, the residence time of the entire polymerization step is in an optimal range of 2 to 4 hours.

When 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, and the reduction in the number of apparatuses requires additional equipment. Since the number of associated distillation columns and condensers is reduced, the piping, instrumentation parts and valves connecting them can be greatly saved, and the running costs are low because the utility-related costs such as vacuum sources and heat transfer devices are greatly reduced. There are advantages.

Table 1 shows an experimental example.

The limiting viscosity of the experimental example is phenol 50 wt.
%, Tetrachloroethane 50 wt% as a solvent, using an Ostwald viscometer, the value calculated from the measurement result at a measurement temperature of 30 ° C. The acid value is neutralized by heating and dissolving benzyl alcohol as a solvent at 230 ° C for 5 minutes. It is a value measured by titration. As shown in Table 1, a high-quality PB having a limiting viscosity of 0.7 or more and an acid value of 25 or less by melt polymerization alone, which is produced by a continuous production operation of direct esterification of TPA and BD.
T was obtained.

[0012]

[Table 1]

[0013]

According to the present invention, the continuous production equipment for PBT is divided into three parts: a direct esterification step, a pre-polymerization step, and a final polymerization step.
The use of a single reactor improves the efficiency of the entire apparatus and operates more economically with energy savings in the production equipment.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment of an apparatus for continuously producing polybutylene terephthalate according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Raw material adjustment tank, 2 ... Raw material supply line, 3 ... Esterification reaction tank, 4 ... Heat exchanger, 5 ... Gas phase part, 6 ... Connecting pipe, 7 ...
Initial polymerization tank, 8 heat exchanger, 9 gas phase section, 10 connecting pipe, 11 final polymerization machine, 12 stirring blade, 13 polymer, 14 stirring power source, 15 oligomer pump, 16
Midway addition equipment.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Yasunari Sase 794, Higashi-Toyoi, Kazamatsu, Kudamatsu City, Yamaguchi Prefecture Inside the Kasado Works of Hitachi, Ltd. F term in the Kasado Plant of Hitachi, Ltd. (reference) 4J029 AA03 AB04 AC01 BA05 CB06A HA01 HB01 KC01 KD01 KD02 KD05 KD06 KD07 KE05 KE07 KE15 LA05 LA08 LA14

Claims (8)

[Claims] 1. A first reactor for producing an oligoester or polyester having an average degree of polymerization of 3 to 7 or less by reacting an aromatic dicarboxylic acid or a derivative thereof with a glycol, and an adult product from the first reactor. In a second reactor for producing a low polymer having an average degree of polymerization of 20 to 40, and further polycondensing the low polymer to give an average degree of polymerization of 70 to 18
Using a third reactor for polycondensing to 0 to produce high molecular weight polybutylene terephthalate,
A method for continuously producing polybutylene terephthalate, wherein at least one of the reactors has no stirring function by an external power source. 2. The third reactor according to claim 1, wherein the 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 horizontal cylindrical container main body, respectively. A stirring rotor that has a volatile material outlet and rotates in the longitudinal direction inside the main body and close to the inside of the main body, and the stirring rotor inside the main body has a plurality of stirring blade blocks according to the viscosity of the processing liquid. Wherein the reactor has a stirring blade having no rotating shaft at the center of the stirring rotor. A method for continuously producing polybutylene terephthalate. 3. A first reactor for producing an oligoester or polyester having an average degree of polymerization of 3 to 7 or less by reacting an aromatic dicarboxylic acid or a derivative thereof with a glycol, and an adult product from the first reactor. In a second reactor for producing a low polymer having an average degree of polymerization of 20 to 40, and further polycondensing the low polymer to give an average degree of polymerization of 70 to 18
And a third reactor for producing polybutylene terephthalate by polycondensation to 0, wherein the third reactor has an inlet and an outlet for the liquid to be treated at the lower end and the lower end, respectively, in the longitudinal direction of the horizontal cylindrical container body. Having an outlet for volatiles at the top of the main body, and a device provided with a stirring rotor that rotates close to the inside of the main body in the longitudinal direction inside the main body, and the stirring rotor inside the main body according to the viscosity of the processing liquid. A continuous method for producing polybutylene terephthalate, comprising a reactor comprising a plurality of stirring blade blocks and having a stirring blade having no rotating shaft at the center of a stirring rotor. 4. A method for continuously producing polybutylene terephthalate according to claim 1, wherein the molar ratio of the aromatic dicarboxylic acid or its derivative as a raw material to the glycols is from 1: 1.2 to 1: 3. .0, the first
The temperature of the reactor is 220 to 275 degrees, the pressure is 3 × 10 ⁵ Pa from atmospheric pressure, and the temperature of the second reactor is 220 to 280.
A method for continuously producing polybutylene terephthalate, wherein the temperature and the pressure of the third reactor are in the range of 220 to 280 ° C. and the pressure is in the range of 200 to 13.3 Pa. 5. The method for continuously producing polybutylene terephthalate according to claim 1, wherein the rotation speed of the stirring blade of the third reactor is 0.5 rpm to 10 rpm. A method for continuously producing terephthalate. 6. The method for continuously producing polybutylene terephthalate according to claim 1, wherein the first reactor comprises:
A continuous production method of polybutylene terephthalate, wherein the total reaction time of the second reactor and the third reactor is operated between 4 and 9 hours. 7. An oligoester or polyester having an average degree of polymerization of 3 to 7 or less is produced by reacting an aromatic dicarboxylic acid or a derivative thereof with a glycol in a first reactor. Polycondensation is performed in a reactor to produce a low polymer having an average degree of polymerization of 20 to 40, and the low polymer is further polycondensed in a third reactor, and polycondensed to an average degree of polymerization of 70 to 180, and polybutylene terephthalate is obtained. The continuous production method of polybutylene terephthalate characterized by producing. 8. A first reactor for producing an oligoester or polyester having an average degree of polymerization of 3 to 7 or less by reacting an aromatic dicarboxylic acid or a derivative thereof with a glycol, and a product from the first reactor. A second reactor that polycondenses to produce a low polymer having an average degree of polymerization of 20 to 40;
A continuous reactor for producing polybutylene terephthalate, wherein the low-polymerized product from the second reactor is further polycondensed and polycondensed to an average degree of polymerization of 70 to 180 to produce polybutylene terephthalate. .