JP2011116915A - Polymerizer of polyester - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for producing polyesters that aims elimination of structural weakness of a second reactor producing polymers. <P>SOLUTION: The apparatus for continuously producing polyesters includes a first reactor 10 for producing oligomers, a second reactor 20 for producing polymers with low degrees of polymerization, and a third reactor 30 for producing polymers with high degrees of polymerization by further performing condensation polymerization. The second reactor 20 is composed of a plurality of reaction chambers 201 and has structure in which the reaction chambers 201 are connected to each other alternately in the upper part thereof and the lower part thereof. In the apparatus, a heating device 220 is installed only inside the reaction chamber into which a reaction liquid flows from the lower part and exits from the upper part. Therefore, stirring blades, the structurally weak parts of the reactor, are eliminated while securing plug flow performance preventing backflow between reaction chambers, along with complete mixing inside the reaction chamber 201. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a continuous polyester production method 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. After that, it is manufactured. In the polymerization step, a polyester having an average degree of polymerization of 3 or more is produced by a condensation polymerization reaction between monomers produced by esterification reaction of two carboxyl groups of dicarboxylic acid with glycol. As an apparatus for producing polyester, for example, the one described in Patent Document 1 is known.

  Patent Document 1 mentions the structure of an initial polymerization vessel which is a second reactor for producing a low polymerization degree polymer having an average degree of polymerization of 20 to 70. According to this method, the initial polymerization vessel is a vertical cylindrical tank, in which there are reaction chambers that are concentrically divided into two tanks, each of which has a stirring blade and a heating device. Provided, a stirring blade is fixed to a single rotating shaft connected to a driving device attached to the upper part of the tank body, and an outlet for volatiles is provided in the upper part of the tank. Stirring is performed and the polymerization reaction proceeds.

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

  The second reactor described in Patent Document 1 is structurally fragile because a stirring blade for stirring the reaction chambers of the two inner and outer tanks is fixed to one rotating shaft. In addition, when shaft blurring occurs, the heating device installed in the reaction chamber may come into contact with the stirring blade, and the heating device and the stirring blade may be damaged. The second reactor described in Patent Document 1 also has a problem that a large amount of energy is required for driving the stirring blade.

  Accordingly, an object of the present invention is to provide a continuous polyester production apparatus that does not require stirring power and has no structural weakness in the second reactor for producing a low polymerization degree polymer having an average viscosity of 1 Pa · s or more. .

  The inventors have a structure in which a plurality of reaction chambers are formed and the reaction chambers are alternately connected to each other at the upper part or the lower part, and the reaction liquid flows only from the lower part and flows out from the upper part. By using the second reactor equipped with a heating device, it was found that a continuous polyester production apparatus that does not require stirring power and does not have structural fragility can be realized, and the present invention has been completed.

That is, the present invention includes the following inventions.
(1) A first reactor for producing an oligomer by reacting dicarboxylic acid or a derivative thereof with glycol, and a second reaction for producing a low polymerization degree polymer by polycondensing the oligomer from the first reactor. A continuous polyester production apparatus comprising: a reactor; and a third reactor for producing a high polymerization degree polymer by further condensation polymerization of the low polymerization degree polymer from the second reactor,
The second reactor is composed of a plurality of reaction chambers, and has a structure in which the reaction chambers are alternately connected to each other at the upper part or the lower part. Only the heating device is installed, the polyester continuous production device.

(2) A plurality of reaction chambers that are alternately connected to each other at the upper part or the lower part are formed by partition plates alternately inserted from above and below into a single space inside the second reactor. ) Polyester continuous production apparatus.

(3) The polyester continuous production apparatus according to (2), wherein the partition plate is movable, whereby the amount of the reaction liquid retained in the reaction chamber is variable, and the residence time of the reaction liquid in the reactor is variable.

(4) The polyester continuous production apparatus according to any one of (1) to (3), wherein a rectifying member made of a material that does not contribute to the polyester polymerization reaction is installed in the reaction chamber of the second reactor.

(5) The polyester continuous production apparatus according to any one of (1) to (4), wherein an air diffuser is installed in the vicinity of the bottom surface of the reaction chamber of the second reactor.

(6) A first reactor, a second reactor, and a third reactor are provided, the second reactor is composed of a plurality of reaction chambers, and the reaction chambers alternate with each other at the upper part or the lower part. A continuous polyester manufacturing apparatus in which a heating apparatus is installed only in a reaction chamber in which a reaction liquid flows in from the lower part and flows out from the upper part. The step of producing an oligomer by reacting dicarboxylic acid or a derivative thereof with glycol in the reactor of No. 2 and the step of polymerizing the oligomer from the first reactor in the second reactor to produce a low polymerization degree polymer. The method, comprising the step of producing a high polymerization degree polymer by further condensation polymerization of the low polymerization degree polymer from the second reactor in the third reactor.

(7) A plurality of reaction chambers that are alternately connected to each other at the upper part or the lower part are formed by partition plates alternately inserted from above and below into a single space inside the second reactor. ) The method described.

(8) The method according to (7), wherein the amount of reaction liquid retained in the reaction chamber is changed by moving the partition plate and / or the residence time of the reaction liquid in the reactor is changed.

(9) Any one of (6) to (8), wherein a rectifying member made of a material that does not contribute to the polyester polymerization reaction is installed in the reaction chamber of the second reactor, thereby preventing the reaction liquid from staying. The method described in 1.

(10) The method according to any one of (6) to (9), wherein an aeration device is installed in the vicinity of the bottom surface of the reaction chamber of the second reactor, thereby preventing stagnation of the reaction solution.

  According to the present invention, it is possible to realize a polyester manufacturing apparatus that does not require stirring power and has low structural vulnerability.

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 Embodiment of the 1st reactor (esterification reactor) in this invention. It is a longitudinal cross-sectional view which shows one Embodiment of the 2nd reactor (initial polymerization device) in this invention. It is a longitudinal cross-sectional view which shows one Embodiment of the 2nd reactor (initial polymerization device) in this invention. It is a longitudinal cross-sectional view which shows one Embodiment of the 3rd reactor (final polymerization device) in this invention. It is side surface sectional drawing of one Embodiment of the 3rd reactor (final polymerization device) shown in FIG.

  The polyester continuous production apparatus of the present invention has at least a first reactor, a second reactor, and a third reactor. The second reactor is composed of a plurality of reaction chambers, and has a structure in which the plurality of reaction chambers are alternately connected to each other at the upper part or the lower part, and the reaction chamber in which the reaction liquid flows in from the lower part and flows out from the upper part. A heating device is installed only inside. The 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. Further, 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 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 tri Manufactured from polytrimethylene terephthalate made from methylene glycol, succinic acid or a derivative thereof and polybutylene succinate made from butanediol (eg, 1,4-butanediol), and made from succinic acid or a derivative 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 200 Torr to 800 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 the first reactor, a reactor usually used when producing polyester by esterification 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. 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 preferably to the first reactor. Added. A catalyst can be used individually or in combination of 2 or more types.

  As the catalyst (polymerization reaction catalyst), a wide range 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 of the produced polyester, such as hue and thermal stability. 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 oligomer supplied from the first reactor is subjected to a condensation polymerization reaction based on the transesterification reaction at a predetermined temperature and pressure to produce a low polymerization degree polymer. Here, the low polymerization degree polymer refers to the polyester after the esterification reaction and before the final condensation polymerization reaction (before entering the third reactor), and is usually a polyester having an average degree of polymerization of about 20 to 70, or an average viscosity of 1 Pa. -Refers to polyester of s or more and less than 100 Pa.s.

  In an initial polymerization vessel (second reactor) for producing a low polymerization degree polymer having an average polymerization degree of 20 to 70, two vertical cylindrical tanks as shown in JP-A-2003-64171 are concentrically arranged. A polymerization vessel having a structure in which a stirring blade and a heating device are provided in each of the reaction chambers divided into two, and the stirring blade is fixed to a single rotating shaft connected to a driving device attached to the upper portion of the tank body was used. In this case, since a stirring blade for stirring the reaction chambers of the two inner and outer tanks is fixed to one rotating shaft, it is structurally vulnerable to shaft shake. In addition, when shaft blurring occurs, it may come into contact with the heating device installed in the reaction chamber, and the heating device and the stirring blade may be damaged. In the polyester continuous production apparatus of the present invention, the second reactor (initial polymerization reactor) is composed of a plurality of reaction chambers, the reaction chambers are alternately connected to each other at the upper part or the lower part, and the reaction liquid flows from the lower part. Since the heating device is installed only inside the reaction chamber that flows out from the upper part, the stirring blade can be removed while maintaining the mixing performance and plug flow performance related to the polymerization.

  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). Examples of the heating method include a method of heating by heat transfer through a heat transfer tube (coil) inside the reactor. The number of reaction chambers configured in the second reactor is not particularly limited as long as it is 2 or more, but is usually 4 to 30, preferably 4 to 8.

  In the second reactor, instead of preparing a plurality of independent reaction chambers, partition plates are alternately inserted into the single space inside the reactor from above and below, so that the space between the plurality of reaction chambers and the reaction chambers is reduced. Interconnection can be realized.

  If the partition plate is movable in the second reactor, the amount of the reaction solution retained in the reaction chamber can be changed, and the residence time of the reaction solution in the reactor can be changed. As a result, it is possible to cope with increase / decrease in production amount and production of polyesters having different reaction rates.

  In the second reactor, preferably, a rectifying member made of a material that does not contribute to the polyester polymerization reaction is installed in the vicinity of the connecting portion between the inner wall of the reactor and the partition plate, thereby preventing the reaction liquid from staying.

  In the second reactor, by installing an aeration device (for example, a bubble generating device) near the bottom of the reaction chamber, it is possible to prevent the reaction solution from staying and to mix the reaction solution in the reaction chamber more completely.

  In the third reactor, a low polymerization degree polymer (polyester) is produced by further subjecting the low polymerization degree polymer supplied from the second reactor to a condensation polymerization reaction at a predetermined temperature and pressure. 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 more (preferably an average degree of polymerization of 150 to 200) or an average viscosity of 100 Pa · s or more (preferably an average viscosity of 500 to 2500 Pa · s). It is.

  The third reactor (final polymerization reactor) is not particularly limited, and a vertical reactor, a horizontal reactor, or a tank reactor can be used. Two or more reactors may be arranged in series, or one reactor may be used. As the stirring blades, lattice blades, wheel blades, glasses blades, hybrid blades, paddle blades, turbine blades, anchor blades, double motion blades, helical ribbon blades, and the like can be used. As the third reactor in which the viscosity of the reaction liquid increases, it is desirable to use a reactor provided with a twin screw stirrer. In particular, it is desirable to use a horizontal biaxial polymerization vessel capable of self-cleaning the stirring shaft. Examples of such a biaxial polymerization vessel include a lattice blade polymerization vessel (Japanese Patent No. 1899479) manufactured by Hitachi Plant Technology, and a spectacle blade polymerization vessel (Japanese Patent No. 4112908).

  A heating device for setting the reaction temperature to the above temperature is installed in the third reactor. As a heating method, a method usually 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, or There are methods such as 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 flows into a distillation column installed at the top of the third reactor to recover glycol contained in the high-boiling fraction. The first reactor or the preceding stage may be refluxed and reused.

  Hereinafter, embodiments of a polyester production apparatus according to the present invention will be described in more detail with reference to the drawings.

  FIG. 1 is an overall apparatus (system) configuration diagram showing an embodiment of a polyester continuous production process according to the present invention. As an example of polyester, a case of PBT (polybutylene terephthalate) will be described. However, the system of FIG. 1 is not limited to the case of manufacturing PBT. As the industrial polyester production method, the direct esterification method is economically very advantageous, and recently, the direct esterification method has been widely adopted for the production of polyester. In the figure, 1 is a raw material adjusting tank in which TPA (terephthalic acid) as a dicarboxylic acid, which is a raw material of PBT, and BD (1,4-butanediol) as a glycol 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 reactor (first reactor) 10 through the raw material inlet 105. At this stage, an additive (ADD) such as a polymerization reaction catalyst (CAT) or a stabilizer and a quality adjusting agent may be added. However, in the embodiment of FIG. 1, the polymerization reaction catalyst and the additive are supplied to the esterification reactor 10. The catalyst is introduced from the catalyst introduction line 14 through the catalyst supply port 108.

  Next, the 1st reactor (esterification reactor) 10 is demonstrated easily using FIG.1 and FIG.2. That is, the outer peripheral portion of the esterification reactor 10 has a structure using the heat medium jacket 101 in order to keep the reaction liquid 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.

  In the embodiment of FIG. 2, the portion immersed in the reaction liquid 104 in the esterification reactor 10 includes a number of spaces between the multiple ring-shaped heat transfer tube lower header 111 and the multiple ring-shaped heat transfer tube upper header 113. A heating means 11 configured by being connected by a thousand multi-heat transfer tubes (heat transfer tubes having a diameter of about 20 mm and a length of about 100 to 150 cm) 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 heat transfer pipe liquid phase heat medium inlet 110 to the heat transfer pipe lower header 111 from the outside, 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 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 to the heat transfer pipe upper header 113 from the heat transfer pipe gas phase heat medium inlet 114 from the outside, and the supplied gas phase heat is supplied. The medium flows in the multi heat transfer tube 112 from the upper part to the lower part, and flows out from the heat transfer tube lower header 111 to the outside through the heat transfer tube gas phase heat medium outlet 110.

  In the first reactor (esterification reactor) 10, water produced 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. The recommended reaction conditions at this time are a temperature of 220 ° C. to 260 ° C., preferably 240 ° C. to 250 ° C., and a pressure of 200 Torr to 800 Torr, preferably 200 Torr to 400 Torr. 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 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 from the reaction solution, is separated into water, THF, and BD by a distillation column (not shown) provided above the first reactor. The BD is removed out of the system, and the BD is returned to the BD tank 40 via the BD circulation line 42 from the lower part of the distillation column again in the system or as a raw material after a purification process and 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. May be. Further, if necessary, the circulation BD discharged from the wet condenser (not shown) of the decompression device installed in the second reactor (initial polymerization reactor) 20 and the third reactor (final polymerization reactor) 30 is removed. The BD basic unit may be further improved by returning to the BD tank 40 from the BD circulation line 43. 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 from the BD circulation line 43 to the BD tank 40. To supply.

  The reaction liquid 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 reaction liquid is supplied to the initial polymerization reactor (second reactor) 20 by the oligomer pump 15 provided in the middle of the communication tube 13 when the esterification reactor 10 reaches a predetermined esterification rate.

  Next, the second reactor (initial polymerization reactor) 20 that is a feature of the present invention will be specifically described with reference to FIGS. 1 and 3 to 4. In FIG. 1, the initial polymerization vessel 20 is divided into a plurality of reaction chambers 201a-d. A reaction solution inlet nozzle 216 is attached to the lower part of the first reaction chamber 201a, and the lower part of the final reaction chamber 201d is attached to the lower part of the final reaction chamber 201d. A reaction liquid outlet nozzle 217 is attached. 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. In FIG. 1, the initial polymerization vessel 20 is composed of four reaction chambers. However, the number of reaction chambers is not limited as long as the number of reaction chambers is two or more. In FIG. 3, independent reaction chambers are connected by piping or the like, and in FIG. 4, partition plates 260a-b and 261 inserted alternately from above and below in a single space inside the reactor. A plurality of reaction chambers that are alternately connected to each other at the upper part or the lower part are formed.

  The reaction chambers are connected to each other at the upper part or the lower part, and the flow of the reaction liquid is vertically upward in the odd-numbered reaction chambers counted from the inlet side, and vertically downward in the even-numbered reaction chambers. That is, the flow of the reaction liquid in the entire initial polymerization vessel 20 is a meandering flow in the vertical vertical direction. Also, heating devices 220a-b are installed only in odd-numbered reaction chambers in which the flow of the reaction liquid is vertically upward.

  In such an apparatus, the reaction liquid continuously supplied from the inlet nozzle 216 first enters the first reaction chamber 201a and is heated by the heat transfer coil 220a, and the condensation polymerization reaction proceeds, and 1 as a byproduct. , 4-butanediol and other volatiles are generated as bubbles 210. The generated volatiles such as 1,4-butanediol evaporate through the liquid surface 250a and are collected in the condenser from the volatile outlet nozzle 218. At the same time, the bubbles 210 make the reaction solution in the reaction chamber 201a turbulent and mix the reaction solution as the bubbles rise, so that the reaction chamber 201a becomes a complete mixing tank. Subsequently, the reaction liquid enters the second reaction chamber 201b. However, since the heating device is not installed in the even number of reaction chambers, the generation of bubbles here is minute. Considering the flow of the reaction liquid in the reaction chambers 201a and 201b, the flow of the reaction liquid is accelerated by the bubbles 210 rising toward the liquid surface only in the reaction chamber 201a in which the flow of the reaction liquid is vertically upward. In the reaction chamber 201b in which the liquid flow is vertically downward, there is no bubble 210 that obstructs the vertically downward flow. Therefore, even if there is no driving force, the vertical meandering flow of the reaction liquid toward the outlet nozzle 217 causes a reverse flow. It is formed naturally without. The same phenomenon occurs in the third reaction chamber 201c and the fourth reaction chamber 201d. The flow from the first reaction chamber 201a to the final reaction chamber 201d is that the reaction chamber is independent in FIG. 3 and separated by the partition plates 260a-b and 261 in FIG. Since no back flow occurs, there is no short path for the reaction solution, and the reaction chamber provided with the heating device forms a complete mixing tank, so that a high-quality polymer can be continuously produced.

  At this time, the width D1 of the odd-numbered reaction chambers and the width D2 of the even-numbered reaction chambers were examined by numerical analysis. As a result, the flow velocity v1 in the odd-numbered reaction chambers and the even-numbered reaction chambers The ratio v1 / v2 of the flow velocity v2 was in the range of 0.9 to 1.1. That is, when manufacturing the device, it is desirable that the ratio of D1 and D2 is within 0.9 to 1.1, and normally 1 is preferable.

  In the reaction chambers 201a-d, rectifying members 240a-d and 241a-d made of a material that does not contribute to the polyester polymerization reaction can be installed. The installation location is preferably the same height as the reaction liquid inlet from the adjacent reaction chamber and the position facing the reaction chamber. By installing these rectifying members 240a-d and 241a-d, the flow of the reaction liquid flowing into or out of the reaction chamber is made smooth, and the stay of the reaction liquid at the position where the rectifying member is installed is prevented. be able to.

  Further, the reaction chambers 201a-d can be provided with a diffuser 230a-d in the vicinity of the bottom thereof. The installation location is preferably in the center of the bottom of the reaction chamber, but is not limited thereto. By installing the diffuser 230a-d, the diffused bubbles 231 prevent the reaction liquid from staying at the bottom of the reaction chamber, and at the same time, increase the turbulence intensity of the flow in the reaction chamber, thereby reducing the reaction liquid in the reaction chamber. Can be mixed more thoroughly.

In FIG. 4, the volume of the reaction liquid held in the reaction chamber of the initial polymerization reactor 20 can be changed by changing the height of the partition plates 260a-b and 261 forming the reaction chambers 201a-d. Accordingly, the residence time of the reaction liquid in the initial polymerization vessel 20 can be changed. As one method for making the height of the partition plate variable, there is a method of forming the partition plates 260a-b and 261 by cutting a groove in the inner wall of the initial polymerization vessel 20 and inserting a plurality of plates into the groove. According to this method, the height of the partition plates 260a-b and 261 can be arbitrarily set by changing the height or width of the fitted plate. As shown in FIG. 4, the height of the reaction liquid levels 250a-b is defined by the height of the partition plates 260a-b. When the height of the partition plates 260a-b is H and the internal bottom area of the initial polymerization vessel 20 is S, the volume V of the reaction liquid in the initial polymerization vessel 20 is approximately V = H × S (1)
It is represented by

On the other hand, the flow rate Q of the reaction liquid flowing from the inlet nozzle 216 is determined from the scheduled production amount of polyester per day. The average residence time τ is determined by the type of polyester to be produced and the required degree of polymerization. Q and τ are V = Q × τ (2)
Are in a relationship.

From formulas (1) and (2), H = Q × τ / S (3) between H, S, Q, and τ.
The following relational expression holds. When it is necessary to change Q or τ due to a change in production plan, etc., by setting the partition plate 260a-b to the height H calculated from the equation (3), an appropriate production amount and residence time can be set. It becomes possible to satisfy at the same time.

  The reaction solution that has progressed in this way is sent to the next final polymerization vessel 30 through the reaction solution outlet nozzle 217 from the bottom of the final reaction chamber 201d.

  When PBT is polymerized in 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 generated 1,4-butanediol and water are produced. 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 of the initial polymerization vessel 20. For example, the operating conditions are a temperature of 230 to 255 ° C. and a pressure of 0.5 to 20 kPa.

  The reaction 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 3rd reactor (final polymerization reactor) 30 is demonstrated easily using FIG. 1, FIG. The final polymerization vessel (third reactor) 30 is an average viscosity of 1 to 45 Pa · which is a low polymerization degree polymer (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 viscosity of about 500 to 2500 Pa · s, which is a polymer having a high degree of polymerization of 150 to 200 at a time, is produced from PBT of about s. Thus, the average viscosity of the reaction liquid is a reactor having a stirrer for high-viscosity liquid treatment that can be used over a range from a low viscosity of 1 to 45 Pa · s to a high viscosity of about 500 to 2500 Pa · s. There must be. As such a stirrer, the continuous stirrer (glasses blade type polymerizer) described in JP-B-8-19241 can be used.

  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 value of 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 (including 250 ° C.). Therefore, it is preferable that the outer periphery of the final polymerization vessel 30 also has a heat medium jacket structure 301 having a glasses-shaped cross section in order to keep the polymer at the reaction temperature, as shown in FIGS. Reference numeral 3011 denotes a heat medium inlet for the heat medium jacket 301, and 3012 denotes a 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.

  As shown in FIG. 6, the low-viscosity prepolymer (low polymerization degree polymer) supplied from the inlet 302 is disposed outside 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 being stretched, it receives a good surface renewal action, the volatile component evaporates from the inside of the prepolymer, the reaction is promoted and the viscosity gradually increases, and the high polymerization degree polymer 50 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 the optimum 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.

  In the continuous production of PBT (polybutylene terephthalate), the method of the present invention is not applied, and the initial polymerization vessel that is the second reactor is applied to the polymerization vessel described in Patent Document 1, and When the second reactor of the invention was applied, the average degree of polymerization of the polymer produced was equivalent to about 150. That is, according to the present invention, it has been clarified that the movable portion called the stirring blade can be eliminated while ensuring the same quality, and the structural vulnerability can be avoided.

  As described above, according to the present invention, in the second reactor (initial polymerization reactor) constituting the continuous polyester production apparatus (system), the stirring blade can be eliminated, and the structural vulnerability is reduced. As a result, it is possible to continuously produce high-quality polyester without risk of equipment trouble.

  DESCRIPTION OF SYMBOLS 1 ... Raw material adjustment tank, 2 ... Raw material supply line, 10 ... Esterification reactor (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 ... reaction liquid, 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 ... stirring Wings, 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 ... initial polymerization vessel ( 2 reactor), 21 ... communication pipe, 22 ... prepolymer pump, 201 ... reaction chamber, 210 ... bubble, 216 ... reaction liquid inlet nozzle, 217 ... reaction liquid outlet nozzle, 218 ... volatiles outlet nozzle, 220 ... Heating device, 230 ... Air diffuser, 231 ... Air diffused bubbles, 240, 241 ... Rectifying member, 250 ... Reaction liquid level, 260, 261 ... Partition plate, 30 ... Final polymerizer (third reactor) , 301 ... Heat medium jacket, 302 ... Prepolymer inlet, 303 ... Polymer outlet, 304 ... Steam outlet, 321 ... Bearing, 31 ... Stirrer blade, 32 ... Stirrer shaft, 35 ... Stirrer drive shaft, 335 ... Heater medium inlet, 336 ... Heat medium outlet, 40 ... BD tank, 41 ... BD supply line, 42, 43, 44 ... BD circulation line, 45 ... New BD supply line, 50 ... Polymer, 3011 ... Heat medium into heat medium jacket , Heat medium outlet for 3012 ... the heating medium jacket.

Claims (10)

A first reactor for producing an oligomer by reacting dicarboxylic acid or a derivative thereof with glycol, and a second reactor for producing a low polymerization degree polymer by condensation polymerization of the oligomer from the first reactor; A polyester continuous production apparatus comprising: a third reactor for producing a high polymerization degree polymer by further condensation polymerization of the low polymerization degree polymer from the second reactor,
The second reactor is composed of a plurality of reaction chambers, and has a structure in which the reaction chambers are alternately connected to each other at the upper part or the lower part, and inside the reaction chamber where the reaction liquid flows in from the lower part and flows out from the upper part. Only the heating device is installed, the polyester continuous production device.   The plurality of reaction chambers alternately connected to each other at the upper part or the lower part are formed by partition plates alternately inserted from above and below into a single space inside the second reactor. Polyester continuous production equipment.   The continuous polyester production apparatus according to claim 2, wherein the partition plate is movable, whereby the amount of the reaction liquid retained in the reaction chamber is variable, and the residence time of the reaction liquid in the reactor is variable.   The polyester continuous production apparatus according to any one of claims 1 to 3, wherein a rectifying member made of a material that does not contribute to the polyester polymerization reaction is installed in the reaction chamber of the second reactor.   The polyester continuous production apparatus according to any one of claims 1 to 4, wherein a diffuser is installed in the vicinity of the bottom surface of the reaction chamber of the second reactor.   A first reactor, a second reactor, and a third reactor are provided, the second reactor is composed of a plurality of reaction chambers, and the reaction chambers are alternately connected to each other at the upper part or the lower part. A method for continuously producing polyester using a continuous polyester production apparatus having a heating structure installed only in a reaction chamber in which a reaction liquid flows in from the lower part and flows out from the upper part. The step of producing an oligomer by reacting a dicarboxylic acid or a derivative thereof with glycol, and the step of producing a low-polymerization polymer by subjecting the oligomer from the first reactor to polycondensation in the second reactor, 3. The method of claim 3, further comprising the step of subjecting the low polymerization degree polymer from the second reactor to a polycondensation polymerization to produce a high polymerization degree polymer.   The plurality of reaction chambers alternately connected to each other at the upper part or the lower part are formed by partition plates alternately inserted from above and below into a single space inside the second reactor. Method.   The method according to claim 7, wherein the reaction liquid holding amount in the reaction chamber is changed by moving the partition plate and / or the residence time of the reaction liquid in the reactor is changed.   The method according to any one of claims 6 to 8, wherein a rectifying member made of a material that does not contribute to the polyester polymerization reaction is installed in the reaction chamber of the second reactor, thereby preventing stagnation of the reaction liquid. .   The method according to any one of claims 6 to 9, wherein a diffuser is installed in the vicinity of the bottom of the reaction chamber of the second reactor, thereby preventing the reaction liquid from staying.

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