JP2010248531A - Apparatus for producing polybutylene terephthalate, and method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for producing polybutylene terephthalate (PBT) designed to afford higher efficiency of a first reactor for producing an oligomer, and to provide a method therefor. <P>SOLUTION: The apparatus for continuously producing the PBT includes: a first reactor 10 for producing the oligomer; a second reactor 20 for producing a low-polymerization degree polymer; and a third reactor 30 for further carrying out polycondensation, and producing a high-polymerization degree polymer. The first reactor 10 is composed of a vertical type cylindrical vessel. A plurality of heat transfer tubes 112 connected so as to pass a gas-phase or liquid-phase heating medium between an upper header 113 and a lower header 111 on the outer periphery thereof in the vessel are disposed, and stirring blades 120 for producing a flow in a liquid which is to be treated and fed among the heat transfer tubes, respectively over a plurality of the heat transfer tubes are installed in the central part. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for continuously producing a polyester polymer such as polybutylene terephthalate and polyethylene terephthalate and an apparatus therefor.

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

  Incidentally, a method for manufacturing PBT and an apparatus therefor are known in Japanese Patent Laid-Open No. 2003-64171 (Patent Document 1).

  In the above Patent Document 1, the following is described. That is, the outer peripheral portion of the esterification reaction tank (first reactor) has a jacket structure for maintaining the treatment liquid at the reaction temperature, and inside the liquid is a calandria type heat exchanger as a liquid heating means. Is installed, the processing liquid flowing in the multi-tube is heated by an external heat source, and the internal liquid is removed only by natural circulation due to the synergistic effect due to density change and temperature difference due to volatile gas generated in the esterification reaction process. The reaction proceeds while circulating. The most desirable reactor type here is preferably a Calandria type in which the processing liquid in the reactor is naturally circulated by utilizing the natural evaporation action of the side reaction product produced by the esterification reaction. However, the present invention is not limited to this apparatus, and a reactor having a stirring blade may be used for process reasons. The water produced by the reaction in the reaction vessel takes the form of water vapor and forms a gas phase part with vaporized BD vapor and by-product THF vapor. As reaction conditions to be recommended at this time, the temperature is 220 ° C. to 250 ° C., and reduced pressure or slightly pressurized conditions are desirable. In particular, the optimum pressure condition is determined by the molar ratio (hereinafter referred to as B / T) of the raw material BD (1,4-butanediol) and TPA (terephthalic acid). When B / T = 2.0 or more, the target esterification rate can be reached in a predetermined residence time because the BD concentration in the treatment liquid is secured even when the pressure is atmospheric pressure or more.

  Further, Patent Document 1 discloses that a PBT having an average polymerization degree of 20 to 70 obtained from an initial polymerization machine (second reactor) is sent to a third reactor which is a final polymerization machine, and a PBT having a higher IV value. In order to obtain the above, it is described that a fourth reactor is installed after the third reactor, and the final polymerization apparatus has two stages.

  Further, a spectacle blade type polymerization apparatus (continuous stirring apparatus) provided with a partition plate is known in Japanese Patent Publication No. 8-19241 (Patent Document 2).

JP 2003-64171 A Japanese Patent Publication No. 8-19241

  However, the first reactor described in Patent Document 1 is provided with a calandria type heat exchanger that heats the processing liquid flowing in the multi-tube by an external heat source, so that the heat transfer efficiency is poor. The problem was that the residence time was long.

  Moreover, since the third reactor (final polymerization machine) is composed of two apparatuses, there is a problem that the apparatus cost increases.

  The object of the present invention is to solve the above problems by reacting an aromatic dicarboxylic acid mainly composed of terephthalic acid with glycols mainly composed of 1,4-butadiol and having an average degree of polymerization of about 2 to 5. An object of the present invention is to provide an apparatus and a method for producing polybutylene terephthalate in which the efficiency of a first reactor for producing an oligomer is improved.

  Another object of the present invention is to make the final polymerization machine one stage, and from a PBT having a viscosity of about 0.1 to 45 Pa · s (or a polymerization degree of 20 to 70) to a viscosity of 500 to 2500 Pa · s (or a polymerization degree of 150). It is an object of the present invention to provide a polybutylene terephthalate production apparatus and method for reducing the apparatus cost and the production cost of the PBT so that a PBT of about 200 to 200) can be produced.

  To achieve the above object, the present invention produces an oligomer by reacting a liquid to be treated comprising an aromatic dicarboxylic acid containing terephthalic acid as a main component and glycols containing 1,4-butanediol as a main component. A second reactor for producing a polymer having a low degree of polymerization having an average degree of polymerization of 20 to 70 by condensation polymerization of the oligomer from the first reactor, and the second reaction And a third reactor (final polymerization machine) for producing a polymer having a high degree of polymerization with an average degree of polymerization of 150 to 200 by further condensation polymerization of a polymer with a low degree of polymerization having an average degree of polymerization of 20 to 70 from the vessel. An apparatus and method for continuously producing polybutylene terephthalate, wherein the third reactor is composed of a single horizontal reaction vessel, and is installed in the reaction vessel so as to face in the horizontal direction. According to each of the two stirring shafts A pair of spectacle-shaped stirring blades that rotate in opposite directions with a phase difference of 90 degrees from each other are provided and configured with a spectacle-blade type polymerizer, and an inlet side to which a polymer with a low degree of polymerization having an average degree of polymerization of 20 to 70 is supplied. It is characterized by being provided with a partition plate that is partitioned into at least two regions and has holes or slits that can pass therethrough.

  Further, the present invention is characterized in that a heat medium is passed through the partition plate.

  According to the present invention, in the first reactor (esterification reaction tank) constituting the continuous production apparatus (system) of PBT (polybutylene terephthalate), the heat exchange efficiency to the liquid to be treated by the heating means is improved. The residence time can be shortened, and as a result, high-quality polybutylene terephthalate can be efficiently and continuously produced.

  Further, according to the present invention, PBT (polybutylene terephthalate) having a viscosity of 500 to 2500 Pa · s (or a polymerization degree of 150 to 200) is obtained from a treatment liquid having a viscosity of 0.1 to 45 Pa · s (or a polymerization degree of 20 to 70). The final polymerization machine (third reactor) that constitutes the continuous production equipment (system) for continuous polymerization can be constructed with a single equipment, reducing equipment costs and reducing the production cost of polybutylene terephthalate. it can.

1 is an overall apparatus (system) configuration diagram showing an embodiment of a continuous production process of PBT (polybutylene terephthalate) according to the present invention. It is a longitudinal cross-sectional view which shows one Example of the 1st reactor (esterification reaction tank) which concerns on this invention. It is a perspective view which shows the case where many heat-transfer tubes are arrange | positioned in the 1st reactor (esterification reaction tank) which concerns on this invention. It is a figure which shows the flow condition of a to-be-processed liquid about one Example of the 1st reactor (esterification reaction tank) which concerns on this invention, (a) is the top view, (b) is the longitudinal cross-sectional view. is there. It is a longitudinal cross-sectional view which shows one Example of the 2nd reactor (initial polymerization tank) concerning this invention. It is a figure which shows one Example of the last superposition | polymerization machine (3rd reactor) comprised by 1 unit | set concerning this invention, (a) is a plane partial cross section, (b) is a front partial cross section. It is side surface sectional drawing (partition plate illustration abbreviate | omitted) of one Example of the last superposition | polymerization machine (3rd reactor) shown in FIG. (A) (b) is a side view which shows the Example of a partition plate, respectively. (A) (b) is a side view which shows the other Example of a partition plate, respectively.

  An embodiment of a polybutylene terephthalate (PBT) manufacturing apparatus and method according to the present invention will be described with reference to the drawings.

  FIG. 1 is an overall apparatus (system) configuration diagram showing an embodiment of a continuous production process of PBT according to the present invention. As an industrial polyester production method, a direct esterification method is very advantageous economically, and recently, a direct esterification method has been widely used for producing a polyester. In the figure, 1 is a raw material adjusting tank in which TPA (terephthalic acid) and BD (1,4-butanediol), which are PBT raw materials, are mixed and stirred at a predetermined ratio. The raw material obtained from the raw material adjustment tank 1 is supplied from the raw material supply line 2 to the esterification reaction tank (first reactor) 10 from the raw material inlet 105. At this stage, an additive (ADD) such as a polymerization reaction catalyst (CAT), a stabilizer or a quality adjusting agent may be added. In this embodiment, the polymerization reaction catalyst and the additive are added to the esterification reactor 10 as a catalyst input line. 14 through the catalyst supply port 108. Examples of the polymerization reaction catalyst include known metal compounds such as organic titanium, organic tin, and organic zirconia. Not only the reaction rate varies depending on the type and combination of the catalysts used, but also the hue and thermal stability of the produced PBT, etc. It is well known that it greatly affects the quality of As the catalyst, organic titanium, which is currently used most industrially, is superior in price and performance. However, coloring of the produced polyester polymer is inevitable even when this catalyst is used. For this reason, a phosphorus stabilizer (for example, phosphoric acid, trimethyl phosphate, triphenyl phosphate, etc.) is used in combination as a stabilizer. In another process, the quality is stabilized by devising the position of the polymerization catalyst and stabilizer. In a normal process, the amount of catalyst is preferably 20 to 100 ppm in terms of titanium metal, and the amount of stabilizer is preferably 0 to 600 ppm in terms of P metal as required.

  Next, the esterification reaction tank (first reactor) 10 that is a feature of the present invention will be specifically described. That is, the outer peripheral portion of the esterification reaction tank 10 has a structure using the heat medium jacket 101 in order to keep the liquid to be treated at the reaction temperature as shown in FIG. A jacket liquid phase heat medium outlet or gas phase heat medium inlet 102 and a jacket liquid phase heat medium inlet or gas phase heat medium outlet 103 are connected to the heat medium jacket 101. Reference numeral 105 denotes a raw material inlet, and 106 denotes an oligomer outlet. Reference numeral 107 denotes a BD supply port, and reference numeral 108 denotes a catalyst supply port. 130 is a steam outlet.

  Further, as shown in FIGS. 2 to 4, a plurality of ring-shaped heat transfer tube lower headers 111 and a plurality of ring-shaped heat transfer tube upper headers are immersed in the treatment liquid 104 in the esterification reaction tank 10. A heating means 11 configured by connecting several thousand multi-heat transfer tubes (a heat transfer tube having a diameter of about 20 mm and a length of about 100 to 150 cm) 112 to and from 113 is installed. When the heat medium having a temperature of 225 to 255 ° C. is a liquid phase heat medium, the liquid phase heat medium is supplied from the outside to the heat transfer tube lower header 111 through the heat transfer tube liquid phase heat medium inlet 110, and the supplied liquid The phase heat medium flows in the multi heat transfer tube 112 from the lower part to the upper part, and flows out from the heat transfer pipe upper header 113 to the outside through the heat transfer tube liquid phase heat medium outlet 114. When the heat medium is a gas phase heat medium (steam gas) such as oil, the gas phase heat medium is supplied from the outside to the heat transfer tube upper header 113 through the heat transfer tube gas phase heat medium inlet 114, and the supplied liquid The phase heat medium flows from the upper part to the lower part in the multi-heat transfer tube 112 and flows out from the heat transfer tube lower header 111 to the outside through the heat transfer tube liquid phase heat medium outlet 110. Furthermore, in the esterification reaction tank 10, by stirring with the stirring blade 120 provided in the lower part of the stirring shaft 121 driven by the stirring drive source 122, as shown in FIG. The liquid flows downward from the upper part to the lower part. In the lower part, the liquid flows in the outer peripheral direction as shown in FIG. 4 (a). Further, as shown in FIG. 4 (b), the liquid is arranged in a ring shape from the lower part to the upper part. As a result, the flow rises through the space between several thousand heat transfer tubes 112. As a result, the treatment liquid is efficiently heated by the multi-heat transfer tube 112, and the reaction proceeds by a synergistic effect due to the density change and temperature difference caused by the volatile gas generated in the esterification reaction step. The heat exchange amount Q of the heating means 11 is expressed by the following equation (1).

Q = U ・ A ・ ΔT (1)
U is a heat transfer rate [W / (m ² · K)], A is a heat transfer area (m ² ) of the multi-heat transfer tube 112, and ΔT is a predetermined logarithmic average temperature difference (K).

  Thus, by arranging thousands of multi-heat transfer tubes 112 having a diameter of about 20 mm in a ring shape, the heat transfer area is increased, the multi-heat transfer tubes 112 are passed through the liquid to be treated, and a stirring blade 120 is provided at the center. Since the processing liquid flows from the lower part to the upper part so as to be entangled between the heat transfer tubes 112, the heat transfer rate U can be greatly improved to about 400, and as a result, the heat exchange amount Q of the heating means 11 is greatly increased. Thus, the residence time of the liquid to be treated can be greatly shortened to about 2 hours.

  Further, if the multi-heat transfer tubes 112 are arranged in a zigzag shape in a plane, the multi-heat transfer tubes 112 can be arranged at a higher density, and the heat passage due to the increase in the heat transfer area A due to the increase in the number and the decrease in the gap between the heat transfer tubes. The rate U can be improved.

  In the first reactor (esterification reaction tank) 10 having the above-described configuration, water generated by the reaction takes the form of water vapor, and forms the gas phase portion 12 together with the vaporized BD vapor and by-product THF vapor. As the reaction conditions to be recommended at this time, the temperature is 225 ° C. to 255 ° C., and reduced pressure or slightly pressurized conditions are desirable. In particular, the optimum pressure condition is determined by the molar ratio (hereinafter referred to as B / T) of the raw material BD (1,4-butanediol) and TPA (terephthalic acid). When B / T = 2.5 or more, the BD concentration in the liquid to be treated is ensured even at atmospheric pressure or higher, and the target esterification rate can be reached in a residence time of about 2 hours. Thus, the esterification reaction rate is improved, the esterification reaction time is shortened, and the amount of THF produced as a side reaction product can be greatly reduced. The reaction temperature to be recommended at this time is 225 ° C to 255 ° C. The amount of THF produced at this time is about 15 to 25 mol% / h in terms of the molar fraction of the raw material TPA. The gas in the gas phase section 12 which is a volatile component out of the liquid to be treated is separated into water, THF, and THF by a distillation tower (not shown) provided above the esterification reaction tank 10 which is the first reactor. It is separated into BD, water and THF are removed out of the system, and BD is returned to the BD tank 40 by the BD circulation line 42 from the lower part of the distillation column in the system or as a raw material again through a purification process or the like. The circulating BD is supplied from the BD tank 40 to the raw material adjusting tank 1 through the BD supply line 41. The circulating BD in the BD tank 40 is subjected to BD refining treatment (not shown) to adjust the purity of the raw material BD as necessary. To do. Further, if necessary, the circulation BD discharged from the wet condenser (not shown) of the decompression device installed in the initial polymerization tank (second reactor) 20 and the final polymerization tank (third reactor) 30 is removed. From the BD circulation line 43, the BD tank 40 is returned to further improve the BD basic unit. In this case, the new BD is supplied from the new BD supply line 45 to the wet condenser of the final polymerization tank 30, supplied from the BD circulation line 44 to the wet condenser of the second reactor 20, and from the BD circulation line 43 to the BD tank 40. Supply.

  The liquid to be treated that has reached a predetermined esterification rate in the esterification reaction tank 10 is supplied to the initial polymerization tank (second reactor) 20 via the communication pipe 13. That is, the liquid to be treated is supplied to the initial polymerization tank (second reactor) 20 by the oligomer pump 15 provided in the middle of the communication pipe 13 when a predetermined esterification rate is reached in the esterification reaction tank 10. .

  Next, the second reactor (initial polymerization tank) 20 will be briefly described with reference to FIGS. 1 and 5. In FIG. 1, the initial polymerization tank 20 has an outer periphery of a rigid cylindrical container body covered with a heat medium jacket 202, and a rotating shaft 203 and a driving device 204 are attached to the upper center of the container body. The inside of the container body is divided into two chambers by a cylindrical partition plate 205, forming a doughnut-shaped first chamber 206 and a cylindrical second chamber 207, and rotating in the respective stirring chambers 206, 207 Agitation blades 208 and 209 for agitation are attached to one common half-length rotating shaft 203. Furthermore, heat transfer tubes 210 and 211 are attached to the outside of the stirring blades 208 and 209 in the respective stirring chambers 206 and 207, and heat medium inlet nozzles 214 and 213 and outlet nozzles 212 and 215 to the heat transfer tubes 210 and 211 are attached. Is attached through the container body. Further, an inlet nozzle 216 for the liquid to be processed is attached to the lower part of the first chamber 206 of the container body, and an outlet nozzle 217 for the liquid to be processed is attached to the lower center of the second chamber 207 of the container body. . Further, an outlet nozzle 218 for volatile substances is provided in the upper part of the container body, and is connected to a condenser and a vacuum evacuation device (not shown) by piping.

  Here, since the peripheral speed of the stirring blade 208 in the first chamber 206 is higher than that of the stirring blade 209 in the second chamber 207, the stirring blade 208 has a slim shape with low stirring resistance. Since the peripheral speed is low, the blade 209 has a wide shape with a large stirring resistance. As a result, both stirring blades 208 and 209 rotating at the same rotational speed can obtain the same stirring effect in both stirring chambers 206 and 207.

  In such an apparatus, the liquid to be processed continuously supplied from the inlet nozzle 216 first enters the first chamber 206, is heated by the heat transfer tube 210, and undergoes a polycondensation reaction while being stirred by the stirring blade 208. The volatiles such as 1,4-butanediol produced are evaporated and collected in the condenser from the volatile outlet nozzle 218. The liquid to be treated that has progressed in this way passes over the upper end of the partition plate 205 from the upper part of the first chamber 206 and enters the second chamber 207. In the second chamber 207, the liquid to be treated is heated in the heat transfer tube 211 and further stirred while being stirred by the stirring blade 209, and the generated 1,4-butanediol or the like Volatiles are evaporated and collected in the condenser from the volatile outlet nozzle 218.

  The liquid to be processed that has undergone the reaction in this manner is sent to the next final polymerization machine 30 from the lower portion of the second chamber 207 through the outlet nozzle 217 of the liquid to be processed. At this time, the liquid to be treated efficiently reacts in the two mixing chambers 206 and 207 in the initial polymerization tank 20 in a completely mixed state, without causing a short pass, and between the first and second chambers in a sealed pipe. Thus, it is possible to continuously produce a high-quality polymer.

  In the case of polymerizing PBT with such an apparatus, bishydroxybutyl terephthalate having an average degree of polymerization of 2 to 5 is continuously supplied from the inlet nozzle 216 to advance the polycondensation reaction, and the produced 1,4-butanediol and water In the initial polymerization tank 20, and a PBT polymer having an average polymerization degree of 20 to 70 can be obtained from the outlet nozzle 217 at the center of the initial polymerization tank 20. The operating conditions are, for example, a liquid temperature of 230 to 255 ° C., a pressure of 0.5 to 20 kPa, and a stirring blade speed of 5 to 100 times / minute.

  According to the preferred embodiment of the present invention, as shown in FIG. 5, the inside of the initial polymerization tank 20 is divided into three chambers by cylindrical partition plates 205A and 205B, and the first doughnut-shaped chamber 206A and the second chamber are divided. Agitating blades 208A, 208B, and 209 that form a chamber 206B and a cylindrical third chamber 207, and rotate and agitate in the respective agitating chambers 206A, 206B, and 207 are attached to the rotary shaft 203, and each agitating chamber Heat transfer tubes 210A, 210B, and 211 are attached in 206A, 206B, and 207. Thus, by configuring the inside of the initial polymerization tank 20 as three complete mixing tanks, the polymerization reaction can be advanced in a shorter time, and a high-quality PBT polymer with little thermal deterioration is continuously produced. be able to.

  The treatment liquid that has passed a predetermined reaction time in the initial polymerization tank (second reactor) 20 is supplied to the final polymerization machine (third reactor) 30 by the prepolymer pump 22 through the communication pipe 21.

  Next, the final polymerization machine 30 that is a feature of the present invention will be specifically described with reference to FIGS. 1, 6, 7, and 8. The final polymerization machine (third reactor) 30 is a low polymerization degree polymer (prepolymer) having an average polymerization degree of 20 to 70 obtained from the initial polymerization machine (second reactor) 20. This is because a PBT 50 having a viscosity of about 500 to 2500 Pa · s, which is a high polymerization degree polymer having an average degree of polymerization of 150 to 200 at a time, can be produced from a PBT of about 45 Pa · s. Thus, the viscosity of the treatment liquid is a reactor having a stirrer for treating a high viscosity liquid that can be used over a range from a low viscosity of 0.1 to 45 Pa · s to a high viscosity of about 500 to 2500 Pa · s. Must be used. As an optimum apparatus for this reactor, the continuous stirring apparatus (glasses blade type polymerization machine) described in JP-B-8-19241 was further improved so that it can be realized using this apparatus. The final polymerization machine (third reactor) 30 is attached to a glass-shaped stirring blade (as shown in FIG. 7) one or a plurality of eyebrow plate members 311 and the tip of the eyebrow plate member. 31a and 31b (consisting of a scraping plate 312) are attached to stirring shafts 32a and 32b driven by an external power source 35 at predetermined intervals with a phase difference of 90 degrees, and the stirring shafts 32a and 32b. Is a biaxial polymerization apparatus constructed by adding a 90 ° phase difference. In addition, it is possible to efficiently stir the polymer when one eyeglass-shaped stirring blade is constituted by a plurality of eyebrow-shaped plate-like members 311 and a scraping plate 312 attached to the tip portion thereof. .

  The reaction conditions at this time are 230 ° C. to 255 ° C., and the pressure is 0.665 kPa to 0.067 kPa. In particular, in order to make the polymer acid value, which is one of the evaluation items of PBT quality, as low as possible, the reaction temperature is desirably 250 ° C. or lower (including 250 ° C.). Therefore, as shown in FIGS. 6 and 7, the outer periphery of the final polymerization machine 30 also has a heat medium jacket structure 301 having a cross-sectional shape of glasses in order to keep the polymer at the reaction temperature. Reference numeral 3011 denotes a heat medium inlet for the heat medium jacket 301, and 3012 denotes the heat medium outlet. 302 is a prepolymer inlet and 303 is a polymer outlet. 304 is a steam outlet. Reference numerals 321a and 321b denote bearings of the stirring shafts 32a and 32b.

  In order to perform condensation polymerization over a wide range from low viscosity to high viscosity, as shown in FIGS. 1, 8, and 9, a few stages of spectacle-shaped stirring blades 31 a and 31 b close to the prepolymer inlet 301 are shown in FIGS. In the lower half, partition plates 33a and 33b are provided to increase the residence time. However, if the partition plates 33a and 33b are simply provided, the low-polymerized polymer (prepolymer) having a viscosity of about 0.1 to 45 Pa · s proceeds by exceeding the partition plates 33a and 33b. Will be too expensive. Therefore, as shown in FIG. 8A, by providing a hole 331 at the bottom of the partition plates 33a and 33b, it becomes possible for the low-polymerized polymer (prepolymer) to advance through the hole 331, and the resistance is somewhat lowered. It becomes possible. Further, as shown in FIG. 8B, by providing the slits 332 in the partition plates 33a and 33b, it becomes possible for the low polymerization polymer (prepolymer) to travel through the slits 332, and the resistance is somewhat lowered. It becomes possible. Furthermore, a preferred embodiment is to pass a heat medium 334 through the partition plates 33a and 33b from the inlet 335 toward the outlet 336 to promote condensation polymerization, as shown in FIGS. 9 (a) and 9 (b). . In the case of the embodiment shown in FIG. 9B, it is necessary to connect the passage of the heat medium 334 with the pipe 337 in order to provide the slit 332.

  As described above, the low polymerization prepolymer is stirred in the region partitioned by the partition plates 33a and 33b and proceeds beyond the holes 331 or the slits 332 and the partition plates 33a and 33b, so that the residence time is secured. After that, it becomes possible to put in a spectacle stirring blade in a region without a partition plate for obtaining a polymer of high polymerization. Of course, it is possible to increase the amount of polycondensation by increasing the amount by which the low-viscosity prepolymer is lifted by narrowing the axial spacing of the glasses stirring blades on the inlet side. On the contrary, it is possible to cope with a polymer having a high viscosity by widening the interval in the axial direction of the glasses stirring blade on the outlet side.

  That is, as shown in FIG. 7, the low-viscosity prepolymer supplied from the inlet 302 is stretched outward due to the configuration in which the respective stirring blades 31a and 31b rotate in the opposite directions from the center to the outside. While staying in each region partitioned by the partition plate 33a and the partition plate 33b sequentially, the surface is subjected to a good surface renewal action, the volatile components are evaporated from the inside of the prepolymer, the reaction is promoted, and the viscosity gradually increases. Subsequently, as shown in FIG. 7, the polymer whose viscosity is gradually increased is subjected to a good surface renewal action while the stirring blades 31a and 31b of each other are stretched outward due to the configuration in which the stirring blades 31a and 31b rotate outward from the center. The reaction is accelerated by evaporating volatile components from the inside of the prepolymer, and the polymer 50 having a high viscosity of about 500 to 2500 Pa · s is discharged from the outlet 303.

  As a result, the final polymerization machine 30 can be subjected to polycondensation by a single apparatus, and the apparatus cost can be greatly reduced. Although the residence time of the first to third reactors is 4 to 7.5 hours, from the viewpoint of quality, the residence time of the entire polymerization process is in an optimal range of 2 to 4 hours. In addition, the residence time can be lengthened by adjusting the temperature and pressure as necessary, and is carried out, for example, to keep quality fluctuations to a minimum when reducing production. is there.

  As described above, according to the present embodiment, in the first reactor (esterification reaction tank) constituting the continuous production apparatus (system) of PBT (polybutylene terephthalate), the liquid to be processed by the heating means is used. The heat exchange efficiency can be improved and the residence time can be shortened. As a result, polybutylene terephthalate with good quality can be efficiently and continuously produced.

  Further, according to the present embodiment, the final polymerization machine (third reactor) constituting the continuous production apparatus (system) of PBT (polybutylene terephthalate) can be configured with one apparatus, and the apparatus cost can be reduced. Therefore, the manufacturing cost of polybutylene terephthalate can be reduced.

  DESCRIPTION OF SYMBOLS 1 ... Raw material adjustment tank, 2 ... Raw material supply line, 10 ... Esterification reaction tank (1st reactor), 101 ... Heat-medium jacket, 102 ... Jacket liquid phase heat-medium outlet or jacket gas-phase heat-medium inlet, 103 ... Jacket liquid phase heat medium inlet or jacket gas phase heat medium outlet, 104 ... Liquid to be treated, 105 ... Raw material inlet, 106 ... Oligomer outlet, 107 ... BD supply port, 108 ... Catalyst supply port, 110 ... Heat transfer tube liquid phase heat medium Inlet or heat transfer tube gas phase heat medium outlet, 111 ... Heat transfer tube lower header, 112 ... Multi heat transfer tube, 113 ... Heat transfer tube upper header, 114 ... Heat transfer tube liquid phase heat medium outlet or Heat transfer tube gas phase heat medium inlet, 120 ... Stirrer blade, 121 ... stirring shaft, 122 ... stirring drive shaft, 130 ... steam outlet, 11 ... heating means, 12 ... gas phase section, 13 ... communication pipe, 14 ... catalyst charging line, 15 ... oligomer pump, 20 ... first Polymerization tank (second reactor), 202 ... heat medium jacket, 203 ... rotating shaft, 204 ... drive device M, 205 ... cylindrical partition plate, 206 ... stirring chamber (first chamber), 207 ... stirring chamber ( (Second chamber), 208 ... stirring blade, 209 ... stirring blade, 210, 211 ... heat transfer tube, 213, 214 ... heating medium inlet nozzle, 212, 215 ... heating medium outlet nozzle, 216 ... inlet nozzle for liquid to be treated, 217 DESCRIPTION OF REFERENCE CHARACTERISTICS EXIT NOZZLE, 218 ... VOLATILE EXIT NOZZLE, 30 ... FINAL POLYMERIZER (Third Reactor), 301 ... Heat Medium Jacket, 302 ... Prepolymer Inlet, 303 ... Polymer Outlet, 304 ... Steam Outlet 311 ... Eyebrow shaped plate member, 312 ... scraping plate, 321a, 321b ... bearing, 31a, 31b ... glasses-shaped stirring blade, 32a, 32b ... stirring shaft, 33a, 33b ... partition plate, 331 ... hole, 332 Slit, 334 ... heat medium, 335 ... heat medium inlet, 336 ... heat medium outlet, 337 ... tube, 40 ... BD tank, 43, 44 ... BD circulation line, 45 ... new BD feed line, 50 ... polymer.

Claims (4)

A first reactor for producing an oligomer by reacting a liquid to be treated comprising an aromatic dicarboxylic acid mainly composed of terephthalic acid and a glycol mainly composed of 1,4-butanediol;
A second reactor for producing a low-polymerization polymer having an average polymerization degree of 20 to 70 by polycondensing the oligomer from the first reactor;
A third reactor for producing a polymer having a high degree of polymerization having an average degree of polymerization of 150 to 200 by further polycondensing a polymer having a low degree of polymerization having an average degree of polymerization of 20 to 70 from the second reactor. An apparatus for continuously producing polybutylene terephthalate,
The third reactor is constituted by a single horizontal reaction vessel, and each of the two stirring shafts installed in the reaction vessel so as to face each other in the horizontal direction has a phase difference of 90 degrees from each other. And provided with a spectacle-shaped stirring blade that rotates in the opposite direction and is configured by a spectacle-blade type polymerization machine, and the inlet side to which a polymer with a low polymerization degree of 20 to 70 on average is supplied is divided into at least two regions, An apparatus for continuously producing polybutylene terephthalate, comprising a partition plate in which holes or slits that can pass are provided.   The continuous production apparatus for polybutylene terephthalate according to claim 1, wherein a heat medium is passed through the partition plate. A first process for producing an oligomer by reacting a liquid to be treated comprising an aromatic dicarboxylic acid containing terephthalic acid as a main component and a glycol containing 1,4-butanediol as a main component using a first reactor. Process,
A second step in which the oligomer produced in the first step is subjected to polycondensation using a second reactor to produce a polymer having a low degree of polymerization having an average degree of polymerization of 20 to 70;
The polymer having a low degree of polymerization having an average degree of polymerization of 20 to 70 produced in the second step is further subjected to condensation polymerization using a third reactor to produce a polymer having a high degree of polymerization having an average degree of polymerization of 150 to 200. A continuous process for producing polybutylene terephthalate having a third step comprising:
The third reactor used in the third step includes one horizontal reaction vessel, two stirring shafts installed in the reaction vessel so as to face in the horizontal direction, and the stirring shaft. Each of which is provided with a spectacle-shaped stirring blade provided with spectacle-shaped stirring blades rotating in opposite directions with a phase difference of 90 degrees from each other, and having a low average polymerization degree of 20 to 70 in the reaction vessel. A method for continuously producing polybutylene terephthalate, characterized in that an inlet side to which a polymer having a degree of polymerization is supplied is divided into at least two regions, and a partition plate having holes or slits formed therein is provided.   The method for continuously producing polybutylene terephthalate according to claim 3, wherein a heating medium is passed through the partition plate provided in the third reactor used in the third step.

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