JP2010248312A - Production apparatus of polyester - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a production apparatus of polyester, the apparatus having no structural brittleness and producing polyester having average viscosity of not less than 1,000 Pa s. <P>SOLUTION: The apparatus for continuously producing polyester from dicarboxylic acid or its derivative and glycol includes: a first reactor for producing an oligomer by reacting a liquid to be processed containing the source materials; a second reactor for producing a prepolymer by polycondensation of the oligomer; and a third reactor for producing a polymer by further polycondensation of the prepolymer. The third reactor is equipped with a stirring device including: a framework which includes concentric circle assemblies composed of a plurality of hollow concentric circles and ribs connecting the circles in radial directions, and supports connecting the concentric circle assemblies in a direction along the rotation axis; and stirring blades composed of plates, punched plates, meshes or wires disposed on faces 501a to 501d defined by the ribs and supports, faces defined by the outermost circumference of the concentric circles and the supports, and/or faces defined by the ribs and the outermost circumference of the concentric circles. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a continuous process for producing polyester such as polybutylene terephthalate, polyethylene terephthalate, polytrimethylene terephthalate, polybutylene succinate, and polyethylene succinate, and an apparatus therefor.

  Polybutylene terephthalate, polyethylene terephthalate, polytrimethylene terephthalate, polybutylene succinate, polyethylene succinate, and other polyesters are made from dicarboxylic acid and glycol as raw materials. Through the process, it becomes polyester. In the polycondensation step, monomers produced by esterification reaction of two carboxyl groups of dicarboxylic acid with each glycol undergo a polycondensation reaction to produce a polyester having an average degree of polymerization of 3 or more. An apparatus for producing polyester is known, for example, in JP-A-11-92555 (Patent Document 1).

  Patent Document 1 mentions the structure of a final polymerization vessel for polymerizing a polyester having an average degree of polymerization of 90 or more. According to this method, the final polymerization apparatus is composed of three blocks, a low viscosity stirring block, a medium viscosity stirring block, and a high viscosity stirring block. In the low viscosity stirring block, the medium viscosity stirring is performed by dropping the liquid to be treated by the bucket. In the block and the high-viscosity stirring block, the evaporation area and the surface renewal speed are ensured by forming a thin film of the liquid to be processed by the wheel-type disk.

JP-A-11-92555

  The final polymerization apparatus described in Patent Document 1 is composed of a single reactor composed of a plurality of completely different blocks, such as a low viscosity stirring block, a medium viscosity stirring block, and a high viscosity stirring block, so that the structure changes. There is a problem that the structural strength may become weak at the block boundary surface.

  Further, in the wheel type disk used in the high viscosity stirring block of the final polymerization apparatus described in Patent Document 1, the liquid to be treated adheres to the disk at a viscosity exceeding 1000 Pa · s, and a thin film is not formed. Therefore, it is difficult to polymerize a high molecular polyester having a higher viscosity.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a polyester production apparatus that enables polymerization of polyester in a reactor that produces polyester having an average viscosity of 1000 Pa · s or more and has no structural brittleness.

  As a result of investigations to solve the above problems, the inventors of the present invention connected a plurality of hollow concentric circles and these in the radial direction to a final polymerization vessel that further prepolymerizes the prepolymer to produce a polyester having an average degree of polymerization of 90 or more. A concentric circle assembly comprising ribs and a skeleton comprising a support connecting the concentric circle assemblies in the direction of the rotation axis, a surface defined by the rib and support, a surface defined by the concentric outermost circumference and the support, and / or Polymerization of high-molecular-weight polyester having a viscosity exceeding 1000 Pa · s can be achieved by installing a stirrer having a stirring blade with a flat plate, perforated flat plate, mesh, or wire group installed on the surface defined by the outermost circumference of the concentric circle with the rib. The present inventors have found that a polyester production apparatus that can be made and does not have structural fragility is obtained, and the present invention has been completed.

That is, the present invention includes the following inventions.
(1) An apparatus for continuously producing polyester from dicarboxylic acid or a derivative thereof and glycol,
A first reactor for producing an oligomer by reacting a liquid to be treated containing dicarboxylic acid or a derivative thereof and glycol, a second reactor for producing a prepolymer by condensation polymerization of the oligomer, and further condensation polymerization of the prepolymer A third reactor for producing the polymer
The third reactor has a skeleton composed of a plurality of concentric hollow concentric circles and a concentric circular assembly composed of ribs that connect these in the radial direction, and a support that connects the concentric circular assemblies in the rotational axis direction, and is defined by the rib and the support. A stirring device having a stirring blade in which a flat plate, a perforated flat plate, a mesh, or a group of wires is installed on a surface defined by a concentric outermost surface and a support, and / or a surface defined by a concentric outermost circle and a rib. Said apparatus comprising:
(2) The stirring device of the third reactor is a flat plate or a perforated flat plate among the surface defined by the rib and the support, the surface defined by the concentric outermost circumference and the support, and the surface defined by the rib and the concentric outermost circumference. The apparatus according to (1), comprising three or more kinds of stirring blades having different surfaces on which a mesh or a wire group is installed.
(3) The stirrer of the third reactor has a stirring blade in which a flat plate or a perforated flat plate is installed on at least the surface defined by the outermost concentric circle and the rib in the region where the prepolymer is introduced from the second reactor. A perforated flat plate or mesh is provided at least on the surface defined by the outermost concentric circle and the support, and the surface defined by the outermost concentric circle and the rib is open The apparatus according to (2), further comprising a stirring blade in which a mesh or a group of wires is installed on at least a surface defined by the rib and the support in a region subsequent thereto.
(4) In the region where the prepolymer is introduced from the second reactor, the stirring device of the third reactor has a surface defined by the rib and the support, a surface defined by the concentric outermost circumference and the support, and a concentric circle with the rib It has a stirring blade in which perforated flat plates are installed on all the surfaces defined by the outermost circumference, and in the area after it, only the surface defined by the concentric outermost circumference and the support and the surface defined by the rib and the support are meshed. The apparatus according to (3), further comprising a stirring blade in which a wire group is installed only on a surface defined by a rib and a support in a region subsequent to the stirring blade.
(5) A method for continuously producing polyester from dicarboxylic acid or a derivative thereof and glycol,
A step of producing an oligomer by reacting a liquid to be treated containing dicarboxylic acid or a derivative thereof and glycol in the first reactor, a step of producing a prepolymer by polycondensing the oligomer in a second reactor, and a third reaction. A step of further polymerizing the prepolymer in a vessel to produce a polymer,
The third reactor has a skeleton composed of a plurality of concentric hollow concentric circles and a concentric circular assembly composed of ribs that connect these in the radial direction, and a support that connects the concentric circular assemblies in the rotational axis direction, and is defined by the rib and the support. A stirring device having a stirring blade in which a flat plate, a perforated flat plate, a mesh, or a wire group is installed on a surface, a surface defined by a concentric outermost circumference and a support, and / or a surface defined by a concentric outermost circumference with a rib. Said method, comprising:

  According to the present invention, it is possible to polymerize a high molecular weight polyester having a viscosity exceeding 1000 Pa · s, and to realize a polyester manufacturing apparatus having no structural weakness.

It is a block diagram which shows one Embodiment of the polyester manufacturing apparatus of this invention. It is a longitudinal cross-sectional view which shows one Embodiment of the 1st reactor (esterification reactor) which concerns on this invention. It is a longitudinal cross-sectional view which shows one Embodiment of the 2nd reactor (initial polymerization device) which concerns on this invention. It is the plane partial sectional view (a) and front partial sectional view (b) which show one embodiment of the 3rd reactor (final polymerization device) concerning the present invention. It is side surface sectional drawing which shows one Embodiment of the 3rd reactor (final polymerization device) shown in FIG. It is one Embodiment of the stirring blade of the stirring apparatus installed in the 3rd reactor (final polymerization device) which concerns on this invention. It is one Embodiment of the stirring blade of the stirring apparatus installed in the 3rd reactor (final polymerization device) which concerns on this invention. It is one Embodiment of the stirring blade of the stirring apparatus installed in the 3rd reactor (final polymerization device) which concerns on this invention.

  The polyester production apparatus of the present invention includes a first reactor for producing an oligomer by reacting a liquid to be treated containing dicarboxylic acid or a derivative thereof and glycol, a second reactor for producing a prepolymer by condensation polymerization of the oligomer, And a third reactor for further polymerizing the prepolymer to produce a polymer. A case where an additional reactor is provided before the first reactor, between the first reactor and the second reactor, or after the third reactor is also included in the present invention. In addition, the present invention includes a case where a plurality of reactors are provided as the first reactor, the second reactor, and the third reactor, respectively.

  The polyester that can be produced in the present invention is not particularly limited as long as it can be produced from dicarboxylic acid or a derivative thereof and glycol. For example, polybutylene terephthalate produced from terephthalic acid or a derivative thereof and butanediol (for example, 1,4-butanediol), polyethylene terephthalate produced from terephthalic acid or a derivative thereof and ethylene glycol, terephthalic acid or a derivative thereof and Manufactured from polytrimethylene terephthalate made from methylene glycol, polybutylene succinate made from butanediol (eg, 1,4-butanediol) and succinic acid or derivatives thereof and ethylene glycol. Polyethylene succinate. Examples of the dicarboxylic acid derivatives include monoalkyl esters (for example, methyl esters and ethyl esters) of dicarboxylic acids and dialkyl esters (for example, dimethyl esters and diethyl esters).

In the first reactor, an oligomer is produced by an esterification reaction of dicarboxylic acid or a derivative thereof with glycol at a predetermined temperature and pressure. Therefore, the first reactor may be referred to as an esterification reactor. In the present invention, the oligomer produced in the first reactor usually has an average degree of polymerization of about 3 to 7, preferably about 2 to 5. The reaction temperature in the first reactor is usually 220 ° C. to 260 ° C., preferably 240 ° C. to 250 ° C., and the pressure is 100 Torr to
600 Torr, preferably 200 Torr to 400 Torr. As a heating method in the reactor, a method generally used in this technical field can be used. For example, a heating medium jacket is installed on the outer periphery of the reactor, and the reaction liquid is heated by heat transfer through the reactor wall surface. There are a method and a method of heating by heat transfer through a heat transfer tube (coil) inside the reactor, and these may be used alone or in combination. As a 1st reactor, the reactor normally used when manufacturing polyester by esterification can be utilized. As such a reactor, a vertical reactor, a horizontal reactor, or a tank reactor can be used. Paddle blades, turbine blades, anchor blades, double motion blades, helical ribbon blades and the like can be used as the stirring blades in the stirring device of the reactor. Moreover, you may install a some reactor as a 1st reactor which implements esterification reaction.

  The polymerization reaction catalyst may be added either in the first reactor, between the first reactor and the second reactor, or in the second reactor, but is preferably added to the first reactor. A catalyst can be used individually or in combination of 2 or more types. As the catalyst, a wide variety of catalysts used for transesterification can be used. For example, a metal compound containing a metal such as Li, Mg, Ca, Ba, La, Ce, Ti, Zr, Hf, V, Mn, Fe, Co, Ir, Ni, Zn, Ge, Sn, for example, an organic acid salt Organic metal compounds such as metal alkoxides and metal complexes (such as acetylacetonate), and inorganic metal compounds such as metal oxides, metal hydroxides, carbonates, phosphates, sulfates, nitrates and chlorides. The Among these metal compound catalysts, titanium compounds, particularly organic titanium compounds such as titanium alkoxides such as titanium tetraethoxide, titanium tetraisopropoxide, and titanium tetrabutoxide are preferable. It may be preferred to use a tin compound such as tin octylate or an antimony compound such as antimony trioxide.

  It is well known that the catalyst not only has a different reaction rate depending on its type and combination, but also has a great influence on the quality, such as hue and thermal stability, of the produced polyester. As the catalyst, the most commonly used industrial titanium compound is excellent in price and performance. However, coloring of the produced polyester polymer is inevitable even when this catalyst is used. For this reason, it is preferable to improve by using a phosphorus stabilizer (for example, phosphoric acid, a trimethyl phosphate, a triphenyl phosphate etc.) together as a stabilizer. In addition, the quality can be stabilized by devising the input position of the catalyst and stabilizer. When an organic titanium compound is used as the catalyst, the amount of the catalyst is usually 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 phosphorus metal.

  In the second reactor, the ester supplied from the first reactor is subjected to a polycondensation reaction based on the transesterification reaction at a predetermined temperature and pressure to produce a prepolymer having a hydroxyl group at the terminal. Here, the prepolymer refers to the polyester before the final condensation polymerization reaction (before entering the third reactor) after the esterification reaction, and usually refers to a polyester having an average degree of polymerization of about 20 to 70.

  The reaction temperature in the second reactor is usually 200 to 260 ° C, preferably about 230 to 255 ° C. The pressure is usually low (for example, about 0.5 to 20 kPa). As a heating method in the prepolymer reactor, a method usually used in the art can be used. For example, a jacket of a heat medium is installed on the outer periphery of the reactor, and the reaction liquid is transferred by heat transfer through the reactor wall surface. There are a method of heating, a method of heating by heat transfer through a heat transfer tube (coil) inside the reactor, and these may be used alone or in combination.

  As the second reactor, a reactor usually used when producing polyester can be used. As such a reactor, a vertical reactor, a horizontal reactor, or a tank reactor can be used. Paddle blades, turbine blades, anchor blades, double motion blades, helical ribbon blades and the like can be used as the stirring blades in the stirring device of the reactor. The distillate discharged from the second reactor is cooled and condensed by a heat exchanger, and then flows into a distillation column installed at the upper part of the second reactor to recover glycol contained in the high-boiling fraction, The first reactor or the preceding stage may be refluxed and reused. Moreover, you may install a some reactor as a 2nd reactor which implements a polycondensation reaction.

  In the third reactor, the prepolymer supplied from the second reactor is further subjected to a condensation polymerization reaction at a predetermined temperature and pressure to produce a polyester having a high polymerization degree. The reaction temperature in the third reactor is usually about 200 to 260 ° C, preferably about 230 to 255 ° C. The pressure is usually low (for example, about 0.05 kPa to 1.0 kPa). The polyester finally produced in the third reactor usually has an average degree of polymerization of 90 or higher or an average viscosity of 100 Pa · s or higher.

  As a heating method in the third reactor, a method generally used in the art can be used. For example, a jacket of a heat medium is installed on the outer periphery of the reactor, and the reaction liquid is transferred by heat transfer through the reactor wall surface. There are a method of heating, a method of heating by heat transfer through a heat transfer tube (coil) inside the reactor, and these may be used alone or in combination. The distillate discharged from the third reactor is cooled and condensed by a wet condenser, and then flowed into a distillation tower installed at the top of the third reactor to recover glycol contained in the high boiling point fraction. One reactor or the preceding stage may be refluxed and reused.

  The present invention provides a skeleton comprising a plurality of (preferably two) concentric circular concentric circles and ribs connecting them radially in the third reactor, and a support connecting the concentric circular assemblies in the rotational axis direction. A flat plate, a perforated flat plate, a mesh, or a group of wires on the surface defined by the rib and the support, the surface defined by the concentric outermost circumference and the support, and / or the surface defined by the outermost circumference of the concentric circle and the rib. It is characterized by using a stirring device having a stirring blade installed. The number of ribs that connect a plurality of hollow concentric circles in the radial direction is usually 2 to 8, preferably 3 to 5. The number of supports connecting concentric circle assemblies in the direction of the rotation axis is usually 2 to 8, and preferably 3 to 5 for each concentric circle. Preferably, the number of ribs and the number of supports per concentric circle are the same, and the rib and the support are connected on a concentric circle.

  The hollow concentric circles refer to, for example, the structures represented by 401a and 402a in FIGS. 5 to 8, and the ribs connecting these in the radial direction are represented by 411a to d in FIGS. The support that connects the concentric circular assemblies in the direction of the rotation axis refers to, for example, the structures represented by 421a to d and 422a to d in FIGS.

  Further, assuming that the rotation direction of the stirring blade in FIG. 5 is counterclockwise, it is the angle formed by the tangent line of the outermost hollow concentric circle and the rib at the contact point between the outermost hollow concentric circle 402a and the ribs 411a to 411d. The side angle θ600 is 0 ° to 90 °, preferably 30 ° to 60 °. By setting the angle θ to an acute angle, when a flat plate, perforated flat plate, mesh, or wire group is installed on the surface defined by the rib and support, the effect of scraping the liquid to be treated is expected at the position where the angle θ 600 is formed. it can.

  The surface defined by the rib and the support indicates, for example, surfaces (501a to 501d) on which meshes are installed in FIG. The concentric outermost circumference and the surface defined by the support refer to, for example, the surfaces (511a to d) on which the mesh is installed in FIG. 8, the surface (521a-d, 522a-d) where the mesh is installed is indicated. It may be preferred that a flat plate, perforated flat plate, mesh, or group of wires is installed on all these surfaces.

  The perforated flat plate refers to a flat plate having perforations, and the perforation rate is usually 50 to 30%. When the perforations are circular, the diameter of one perforation is usually 1 to 10 cm, preferably 2 to 5 cm. It is. When the perforations are elliptical, the average of the major axis and the minor axis is within the above range of diameters. When the wire group is installed, it means the case where the wire is stretched only in one direction unlike the mesh. In that case, the wire is preferably installed in equilibrium with the stirring shaft (rotating shaft) of the stirring device.

  In a final polymerizer (third reactor) for producing a polymer with a high degree of polymerization having an average degree of polymerization of 90 or more or an average viscosity of 100 Pa · s or more, a stirring blade for the liquid to be treated as disclosed in JP-A-11-92555 When a disk installed perpendicularly to the center of rotation is used, the viscosity of the liquid to be treated is 1000 Pa · s or less because there is a disk that is a constituent member of the stirring blade on the same plane as the liquid dropping direction. Then, a thin film can be formed on the surface of the disk to form an evaporation surface. However, in the case of an ultrahigh viscosity of 1000 Pa · s or more, the liquid to be treated adheres on the surface of the disk and prevents free fall of the liquid to be treated. The evaporation surface cannot be formed. However, by installing the stirring device as described above in the third reactor, the structure existing on the same plane as the dropping direction of the liquid to be treated is minimized, and even at an ultrahigh viscosity of 1000 Pa · s or more. The evaporation surface forming performance can be ensured.

  The third reactor is preferably a horizontal reactor having a stirrer whose stirring shaft (rotating shaft) is substantially horizontal. The horizontal reactor has a prepolymer inlet for introducing the prepolymer supplied from the second reactor and a polymer outlet for discharging the produced polyester, and the reactant in the reactor is discharged from the prepolymer inlet to the polymer outlet. As the process proceeds, the degree of polymerization increases and the viscosity increases. Therefore, it is preferable to install a stirrer having different types of stirring blades for each region where reactants having different viscosities exist in the reactor. Of the surface defined by the rib and the support, the surface defined by the concentric outermost circumference and the support, and the surface defined by the rib and the concentric outermost circumference, the stirring device of the third reactor is a flat plate, perforated flat plate, mesh, Or it is preferable to have 3 or more types of stirring blades in which the surface where the wire group is installed differs.

  For example, in the third reactor, a first reaction region in which a polyester having an average viscosity of 0.1 Pa · s to 30 Pa · s is produced, and a polyester in which a polyester having an average viscosity of 30 Pa · s to 100 Pa · s in the subsequent stage is produced. The reaction system is divided into two reaction regions and a third reaction region for producing a polyester having an average viscosity of 100 Pa · s to 1000 Pa · s or higher in the subsequent stage. In the first to third regions, stirrers having different stirring blades are installed.

  Preferably, in the region where the prepolymer is introduced from the second reactor, for example, in the first reaction region where polyester having an average viscosity of 0.1 Pa · s to 30 Pa · s is formed, it is defined by at least a concentric outermost circumference and ribs. A stirring blade in which a flat plate or a perforated flat plate is installed on the surface is preferable. In the region, it is more preferable that a flat plate or a perforated flat plate is provided on the surface defined by the outermost circumference of the concentric circle and the support and the surface defined by the rib and the support. The surface defined by the outermost circumference of the concentric circle and the rib is normally divided into a plurality of sections as shown in FIG. 8, but flat plates or perforated flat plates are installed on all of these surfaces (521a-d, 522a-d). However, it is preferable that they are installed on all surfaces. The same applies to the surface defined by the outermost circumference of the concentric circle and the support and the surface defined by the rib and the support.

  In the subsequent region, for example, in the second reaction region where polyester having an average viscosity of 30 Pa · s to 100 Pa · s is produced, perforated flat plates or meshes are installed on at least the surface defined by the concentric outermost circumference and the support. However, a stirring blade having an open surface defined by the outermost circumference of the concentric circle and the rib is preferable. In the region, it is more preferable that a perforated flat plate or a mesh is installed on the surface defined by the rib and the support. The surface defined by the outermost circumference of the concentric circle and the support is usually divided into a plurality of sections as shown in FIG. 7, but even if all of these surfaces (511a to 511d) are not provided with perforated flat plates or meshes. Although it is good, it is preferable that it is installed on all surfaces. The same applies to the surface defined by the rib and support. The hole diameter of the perforated flat plate and the roughness of the mesh are preferably finer on the side closer to the inlet and rougher toward the outlet.

  Further, in a third reaction region for producing a polyester having an average viscosity of 100 Pa · s to 1000 Pa · s or more, for example, in a subsequent region, a stirring blade in which a mesh or a wire group is installed on at least a surface defined by a rib and a support Is preferred. In the said area | region, in any other surface, neither a flat plate, a perforated flat plate, a mesh, or a wire group exists, but it is preferable that it is opening. The surface defined by the rib and the support is usually divided into a plurality of sections as shown in FIG. 6, but the mesh or the wire group may not be installed on all of these surfaces (501a to 501d). It is preferable to be installed on all surfaces. It is desirable that the roughness of the mesh and the interval between the wire groups are finer on the side closer to the entrance and become rougher toward the exit. It is desirable to install the wire group parallel to the rotation axis.

  In this way, by having a structure that gradually reduces the area occupied by the structure in the stirring blade as it goes from low viscosity to high viscosity, it is possible to form an efficient evaporation surface according to the change in viscosity of the liquid to be treated. Become. On the other hand, even if the structure of the stirring blade is different for each region, the skeletal structure is the same. Therefore, at the boundary between the first reaction region and the second reaction region and the boundary between the second reaction region and the third reaction region, There are few discontinuities on the top and less fragility on structural strength.

  Hereinafter, an embodiment of a continuous production process of polyester according to the present invention will be described with reference to the drawings. This embodiment demonstrates the case where PBT (polybutylene terephthalate) is manufactured as polyester. In FIG. 1, 1 is a raw material preparation 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 preparation tank 1 is supplied from the raw material supply line 2 to the esterification reactor (first reactor) 10 through the raw material inlet 105. At this stage, an additive (ADD) such as a polymerization reaction catalyst (CAT), a stabilizer, and 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. In this embodiment, an organotitanium compound is used as a catalyst, and is added so that the titanium metal equivalent concentration is 20 to 100 ppm.

  In the present embodiment, the outer periphery of the esterification reactor 10 has a structure using a 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.

  Furthermore, as shown in FIG. 2, a portion immersed in the liquid 104 to be treated in the esterification reactor 10 includes a plurality of ring-shaped heat transfer tube lower headers 111 and a plurality of ring-shaped heat transfer tube upper headers 113. A heating means 11 configured by connecting several thousand heat transfer tubes (heat transfer tubes having a diameter of about 20 mm and a length of about 100 to 150 cm) 112 between them is installed. When the heat medium having a temperature of about 245 to 260 ° 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. The liquid 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 through the heat transfer pipe liquid phase heat medium outlet 114 to the outside. 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.

  In the first reactor (esterification reactor) 10, water generated by the reaction takes the form of water vapor, and forms a gas phase portion 12 together with vaporized BD vapor and by-product THF vapor. In the present embodiment, the reaction is performed at a reaction temperature of 240 to 250 ° C. and a pressure of 200 to 400 Torr in the first reactor. Since the reaction by-product can be quickly removed by reducing the pressure, the target esterification rate can be reached in a residence time of 2 hours or less. 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 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 from water, THF and BD by a distillation column (not shown) provided above the esterification reactor 10 which is the first reactor. Water and THF are removed to the outside 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 again in the system or as a raw material through a purification process or the like. The circulating BD is supplied from the BD tank 40 to the raw material preparation tank 1 through the BD supply line 41. The circulating BD in the BD tank 40 is subjected to BD purification processing (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 vessel (second reactor) 20 and the final polymerization vessel (third reaction vessel) 30 is BD-circulated. The line 43 is returned to the BD tank 40 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 reactor 30, supplied from the BD circulation line 44 to the wet condenser of the second reactor 20, and supplied 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 reactor 10 is supplied to the initial polymerization reactor (second reactor) 20 via the communication pipe 13. That is, the liquid to be treated is supplied to the initial polymerization reactor (second reactor) 20 by the oligomer pump 15 provided in the middle of the connecting pipe 13 when the esterification reactor 10 reaches a predetermined esterification rate.

  Next, the second reactor (initial polymerization reactor) 20 will be described with reference to FIGS. 1 and 3. In FIG. 1, in the initial polymerization vessel 20, the outer periphery of a rigid cylindrical container body is 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 main 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. Thereby, 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 treated continuously supplied from the inlet nozzle 216 first enters the first chamber 206, is heated by the heat transfer tube 210, and undergoes a condensation polymerization 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. The liquid to be treated is heated in the heat transfer tube 211 in the second chamber 207 as in the first chamber and further undergoes the condensation polymerization reaction while being stirred by the stirring blade 209, and the produced 1,4-butanediol, etc. Volatiles are evaporated and collected in the condenser from the volatile outlet nozzle 218.

  The liquid to be treated that has undergone the reaction in this way is sent to the next final polymerization reactor (third reactor) 30 from the lower portion of the second chamber 207 through the outlet nozzle 217 of the liquid to be treated. At this time, the liquid to be treated efficiently reacts in the completely mixed state in the two stirring chambers 206 and 207 in the initial polymerization vessel 20, respectively, without a short pass, and in the sealed pipe between the first and second chambers. Therefore, 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 3 to 7 is continuously supplied from the inlet nozzle 216 to advance the condensation polymerization reaction, and the produced 1,4-butanediol and water are The vapor is separated in the initial polymerization vessel 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 vessel 20. In this embodiment, in the second reactor, the reaction is carried out at a reaction 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.

  In this embodiment, as shown in FIG. 3, the inside of the initial polymerization vessel 20 is divided into three chambers by cylindrical partition plates 205A and 205B, and the first chamber 206A and the second chamber 206B having a donut shape are cylindrical. The third chamber 207 is formed, and stirring blades 208A, 208B and 209 for rotating and stirring the respective stirring chambers 206A, 206B and 207 are attached to the rotary shaft 203, and further, the respective stirring chambers 206A, 206B and 207 are rotated. Heat transfer tubes 210A, 210B, and 211 are attached inside. In this way, by configuring three initial mixing tanks in the initial polymerization vessel 20, the polymerization reaction can be advanced in a shorter time, and a high-quality polymer with little thermal deterioration can be continuously produced. it can.

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

  Next, the final polymerizer 30 that is a feature of the present invention will be specifically described with reference to FIGS. 1 and 4 to 8. In the final polymerization vessel (third reactor) 30, from a PBT having a viscosity of about 0.1 to 45 Pa · s, which is a prepolymer having an average polymerization degree of 20 to 70 obtained from the initial polymerization vessel (second reactor) 20, A PBT 50 having an average degree of polymerization of 90 or more at a time, preferably 150 to 200, and a viscosity of 100 to 1000 Pa · s, preferably 500 to 2500 Pa · s can be produced. Therefore, as the third reactor, a reaction having a stirrer for treating a high-viscosity liquid that can be used in a range from a low viscosity of 0.1 to 45 Pa · s to a high viscosity of 500 to 2500 Pa · s as described above. You must use a vessel.

  As a suitable stirring apparatus for this third reactor, a concentric circle assembly comprising a plurality of hollow concentric circles (401a-b, 402a-b) and ribs (411a-d, 412a-d) connecting them in the radial direction, and It has a skeleton consisting of supports (421a-d, 422a-d) that connect concentric circle assemblies in the direction of the rotation axis, and is defined by surfaces (501a-d) defined by ribs and supports, outermost circumferences of concentric circles and supports Stirring having a stirring blade in which a flat plate, a perforated flat plate, a mesh, or a wire group is installed on the surface (511a-d) and / or the surface (521a-d, 522a-d) defined by the outermost circumference concentric with the rib Use the device. The hollow concentric circles 401a-b and 402a-b are connected to the stirring shaft 32 driven by the external power source 35 at both ends of the reactor. 5-8, the number of ribs 411a-d, 412a-d on the rotating surface is four, but is not limited to this. In the present embodiment, the angle θ600 in FIG. 5 is 45 °.

  In this embodiment, in the third reactor, the reaction is performed at a reaction temperature of 230 ° C. to 255 ° C. and a pressure of 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, it is desirable to set the reaction temperature to 250 ° C. or lower. As shown in FIGS. 4 and 5, the outer periphery of the final polymerization vessel 30 also has a heat medium jacket structure 301 in order to keep the polymer at the above 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 numeral 321 denotes a bearing of each of the stirring shafts 32.

  In the third reactor, in order to perform condensation polymerization over a wide range from low viscosity to high viscosity, the inside of the reactor is a first reaction region for producing a polyester having an average viscosity of 0.1 Pa · s to 30 Pa · s, It is divided into a second reaction region for producing a polyester having an average viscosity of 30 Pa · s to 100 Pa · s and a third reaction region for producing a polyester having an average viscosity of 100 Pa · s to 1000 Pa · s. In one reaction region, surfaces (501a to d) defined by ribs and supports, surfaces (511a to d) defined by concentric outermost circumferences and supports, and surfaces (521a to d) defined by ribs and concentric outermost circles. 522a-d) is provided with a perforated flat plate. As a result, the evaporation area and the surface renewal speed can be ensured by a series of operations that are caused by rotating the stirring blades and then dropping the liquid to be treated after it is swirled. In addition, when the viscosity of the liquid to be treated is low, the liquid to be treated flows in the axial direction, which causes a problem that the residence time for advancing the polymerization reaction cannot be ensured. This can be prevented by installing a perforated flat plate on the surfaces (521a-d, 522a-d).

  In the second reaction region following the first reaction region, the surfaces (501a to d) defined by the ribs and the support, and the outermost concentric circle and the support are provided in order to prevent the polymer from adhering to the stirring blade as the viscosity increases. The mesh is placed on any of the surfaces (511a to 511d) defined in (1). After the reaction liquid is swept up by the rotation of the mesh, the reaction liquid is dropped into a thread shape from the gap between the meshes, so that the surface area per unit volume can be secured, and the evaporation area and the surface renewal speed can be secured. The roughness of the mesh is fine on the side close to the prepolymer inlet 302 and becomes rougher toward the polymer outlet 303. The surfaces (521a to d, 522a to d) defined by the outermost circumference of the concentric circles with the ribs are openings.

  In the third reaction region, the wire group is installed only on the surfaces (501a to 501d) defined by the rib and the support. After the liquid to be reacted is swept up by the rotation of the wire group, the reaction liquid is dropped into a thread or band from the gap between the wire groups, so that the surface area per unit volume can be secured, and the evaporation area and the surface renewal rate can be secured. The distance between the wire groups is fine on the side close to the prepolymer inlet 302 and becomes rougher toward the polymer outlet 303. The wire group is installed parallel to the rotation axis.

  The low-viscosity prepolymer supplied from the inlet 302 is able to lift the reaction liquid suitable for the respective viscosities of the first reaction region, the second reaction region, and the third reaction region, and to improve the surface through a free fall mechanism. Under the action, volatile components evaporate from the inside of the prepolymer, the reaction is promoted, and the viscosity gradually increases. As a result, the polymer 50 having a high degree of polymerization having a high viscosity of about 500 to 2500 Pa · s is discharged from the outlet 303.

  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.

  According to the present invention, the third reactor (final polymerization reactor) can be subjected to polycondensation by a single device, so that the device cost can be greatly reduced and the production cost of the polyester can be reduced.

(Example)
PBT (polybutylene terephthalate) was manufactured in the polyester manufacturing apparatus shown in FIGS. As a result, PBT having a viscosity of 2500 Pa · s and an average degree of polymerization of about 200 was obtained at the outlet of the third reactor (final polymerization vessel) 30. The obtained PBT had an IV value of 0.7 to 1.2 and a b value of 0 to 4.

(Comparative example)
In the polyester production apparatus shown in FIGS. 1 to 5, a wheel-type disk described in Patent Document 1 was applied as a stirring apparatus for the third reactor, and PBT (polybutylene terephthalate) was produced. As a result, PBT having a viscosity of 500 Pa · s and an average degree of polymerization of about 150 was obtained at the outlet of the third reactor (final polymerization vessel) 30.

DESCRIPTION OF SYMBOLS 1 ... Raw material preparation tank, 2 ... Raw material supply line, 10 ... Esterification reactor (first 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, 115 ... gap Or a gap insertion material, 120 ... stirring blade, 121 ... stirring shaft, 122 ... stirring drive shaft, 130 ... steam outlet, 11 ... heating means, 12 ... gas phase section, 13 ... communication pipe, 14 ... catalyst input line, DESCRIPTION OF SYMBOLS 5 ... Oligomer pump, 20 ... Initial polymerization reactor (2nd reactor), 21 ... Communication pipe, 22 ... Prepolymer pump, 202 ... Heat-medium jacket, 203 ... Rotating shaft, 204 ... Drive apparatus M, 205 ... Cylindrical shape 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 ... Heat medium outlet nozzle, 216 ... Process liquid inlet nozzle, 217 ... Process liquid outlet nozzle, 218 ... Volatile outlet nozzle, 30 ... Final polymerizer (third reactor), 301 ... Heat medium Jacket, 302 ... Prepolymer inlet, 303 ... Polymer outlet, 304 ... Steam outlet, 321 ... Bearing, 32 ... Stirring shaft, 335 ... Heat medium inlet, 336 ... Heat medium outlet, 40 ... BD tank, 41 ... BD supply line, 2, 43, 44 ... BD circulation line, 45 ... New BD supply line, 401, 402 ... hollow concentric circles, 411, 412 ... ribs connecting the hollow concentric circles in the radial direction, 421, 422 ... concentric circular assemblies in the rotational axis direction 501 ... surface defined by rib and support, 511 ... surface defined by concentric outermost circumference and support, 521, 522 ... surface defined by rib and concentric outermost circumference, 50 ... polymer, 600 ... The angle θ between the hollow concentric circle and the rib.

Claims (5)

An apparatus for continuously producing a polyester from dicarboxylic acid or a derivative thereof and glycol,
A first reactor for producing an oligomer by reacting a liquid to be treated containing dicarboxylic acid or a derivative thereof and glycol, a second reactor for producing a prepolymer by condensation polymerization of the oligomer, and further condensation polymerization of the prepolymer A third reactor for producing the polymer
The third reactor has a skeleton composed of a plurality of concentric hollow concentric circles and a concentric circular assembly composed of ribs that connect these in the radial direction, and a support that connects the concentric circular assemblies in the rotational axis direction, and is defined by the rib and the support. A stirring device having a stirring blade in which a flat plate, a perforated flat plate, a mesh, or a group of wires is installed on a surface defined by a concentric outermost surface and a support, and / or a surface defined by a concentric outermost circle and a rib. Said apparatus comprising:   Of the surface defined by the rib and the support, the surface defined by the concentric outermost circumference and the support, and the surface defined by the rib and the concentric outermost circumference, the stirring device of the third reactor is a flat plate, perforated flat plate, mesh, The apparatus according to claim 1, further comprising three or more kinds of stirring blades having different surfaces on which the wire group is installed.   The stirring device of the third reactor has a stirring blade in which a flat plate or a perforated flat plate is installed on a surface defined by at least the outermost concentric circle and the rib in the region where the prepolymer is introduced from the second reactor, In the subsequent stage, a perforated flat plate or mesh is installed at least on the surface defined by the outermost circumference of the concentric circle and the support, but the surface defined by the outermost circumference of the concentric circle and the rib has an agitating blade that is open. 3. The apparatus according to claim 2, further comprising a stirring blade having a mesh or a wire group installed on at least a surface defined by the rib and the support in a region subsequent thereto.   In the region where the prepolymer is introduced from the second reactor, the stirring device of the third reactor has a surface defined by a rib and a support, a surface defined by a concentric outermost circumference and a support, and a rib and a concentric outermost circumference. It has a stirring blade with a perforated flat plate installed on all the specified surfaces, and meshes are installed only on the surface defined by the outermost concentric circle and the support and on the surface defined by the rib and the support in the subsequent stage. 4. The apparatus according to claim 3, further comprising a stirring blade having a stirring blade in which a wire group is installed only on a surface defined by the rib and the support in a region subsequent to the stirring blade. A method for continuously producing a polyester from a dicarboxylic acid or a derivative thereof and glycol,
A step of producing an oligomer by reacting a liquid to be treated containing dicarboxylic acid or a derivative thereof and glycol in the first reactor, a step of producing a prepolymer by polycondensing the oligomer in a second reactor, and a third reaction. A step of further polymerizing the prepolymer in a vessel to produce a polymer,
The third reactor has a skeleton composed of a plurality of concentric hollow concentric circles and a concentric circular assembly composed of ribs that connect these in the radial direction, and a support that connects the concentric circular assemblies in the rotational axis direction, and is defined by the rib and the support. A stirring device having a stirring blade in which a flat plate, a perforated flat plate, a mesh, or a group of wires is installed on a surface defined by a concentric outermost surface and a support, and / or a surface defined by a concentric outermost circle and a rib. Said method, comprising:

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