JP3602958B2 - Horizontal reaction tank - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to a horizontal reaction vessel used for synthesizing a condensable high molecular compound such as polyester, polyamide, and polycarbonate that produces a volatile low molecular substance by reaction.
[0002]
[Prior art]
Polymer compounds such as polyesters, polyamides and polycarbonates, particularly polyesters represented by polyethylene terephthalate and polybutylene terephthalate, are widely used for various applications because of their excellent physical and chemical properties. In particular, polyester is excellent in mechanical properties such as strength and elastic modulus, heat resistance, and the like, and is therefore widely used as industrial fibers such as clothing and tire cords, or as films and engineering plastics.
[0003]
Generally, a direct polymerization method or a transesterification method is used as a method for producing a polyester used for such various uses.
[0004]
Here, the former direct polymerization method is a method in which a polyester precursor is formed by directly esterifying an acid component and a diol component, and then the polyester precursor is subjected to polycondensation under reduced pressure to produce a polyester. is there. On the other hand, the latter transesterification method is a method in which a lower alkyl ester of an acid component is transesterified with a diol to form a polyester precursor, and then the polyester precursor is polycondensed under reduced pressure.
[0005]
Conventionally, in the polymerization of such a polyester, a batch system has been used in many cases.However, in recent years, in order to produce the polyester at a low cost while taking advantage of scale, a continuous system has been switched. . This is because adopting the continuous method has extremely large advantages such as a decrease in yield, an improvement in quality, a uniform degree of polymerization, and an improvement in operability.
[0006]
Generally, many of the production methods by continuous polymerization of polyester are performed by a process in which a plurality of transesterification or esterification reaction tanks and a polycondensation reaction tank are combined. For example, a raw material is supplied to a transesterification reaction tank or an esterification reaction tank to generate a monomer, and the obtained monomer is supplied to an initial polycondensation reaction tank and reacted under reduced pressure to produce a low polymer. Is produced, and further supplied to a polycondensation reaction tank to produce an intermediate polymer and a high polymer under reduced pressure.
[0007]
In such a polycondensation reaction tank, many methods for obtaining a higher reaction rate have been conventionally proposed and put to practical use. For example, as one of such conventional methods, in a polycondensation reaction of a polyester, a thin film reaction tank in which a reaction product is made into a thin layer and reacted for the purpose of quickly separating and removing by-products such as glycols is used. It has been practiced to use a reaction vessel that can facilitate the evaporation of the by-products by increasing the evaporation area of the reactants by using or stirring vigorously.
[0008]
Here, as the above-mentioned reaction tank, a vertical reaction tank of a wet wall type or a screw type, and a horizontal reaction tank of a uniaxial or biaxial type are generally used. Furthermore, there are many commercially available reaction tanks that take into account stirring so that the free surface area of the reactants can be increased.However, in these reaction tanks, strong stirring is required. Therefore, there is a problem that the equipment cost is expensive and a lot of energy is consumed. In addition, the reaction resulting from intense agitation has a problem that the obtained reaction product tends to cause unevenness in the degree of polymerization and the like, and the quality of the obtained polyester deteriorates. Furthermore, there is a problem that the quality of the reaction product is also deteriorated by mixing the deteriorated polymer as a foreign substance due to insufficient renewal of the polymer or the like staying in the gas phase for a long time. In the present invention, the `` horizontal reaction tank '' refers to a `` reaction tank provided such that the center axis direction of the rotation axis of the stirring blade provided in the reaction tank is substantially parallel to the horizontal plane ''. I do.
[0009]
In order to solve such a problem, by using a horizontal reaction tank as proposed in Japanese Patent Publication No. 40-3964, the reaction solution is scraped up by stirring, and then most of the scraped up reaction solution is removed. It has been practiced that a liquid film of a new reactant is constantly formed by dropping, and the reaction is performed in an extremely short time. In this horizontal reaction tank, stirring shafts each holding stirring blades are provided only at both ends of the tank, thereby adopting a structure in which the stirring shaft is eliminated from an intermediate portion inside the reaction tank. Further, the reaction vessel includes: (1) the stirring blade which opposes most of the inner peripheral wall surfaces of the reaction vessel at a small gap; and (2) two or more rotating blades integrally rotating with the stirring blade. And a partition plate having an opening at the center thereof for partitioning the inside of the reaction tank.
[0010]
Indeed, according to the reaction vessel, the inner peripheral wall of the reaction vessel is constantly updated with a new reaction solution, so that heat transfer to the reaction solution is good, and the reaction It has a great advantage that it does not adhere to the wall surface and that a stirrer shaft is not provided in the middle part of the inside of the reaction tank, so that a situation in which a lump of reactants in a dumpling form around the stirrer shaft does not occur. ing.
[0011]
However, in the reaction tank, no consideration is given to the form of the liquid film of the reactant that falls from the stirring blade, and no attempt is made to control the free surface of the falling liquid film. Absent. For this reason, in the reaction tank, the ability to form such a free surface of the liquid film is limited, and it is extremely difficult to further increase the reaction efficiency.
[0012]
[Problems to be solved by the invention]
In view of the above-mentioned problems, the problem to be solved by the present invention is that it does not require vigorous stirring and can reduce the generation of foreign substances during the reaction, thereby increasing the reaction speed or reaction efficiency and the produced polyester. It is an object of the present invention to provide an inexpensive horizontal reaction vessel capable of significantly improving the quality of the reactor.
[0013]
[Means to solve the problem]
Here, as means for solving the above-mentioned problems, “(A) a cylindrical reaction tank having an inlet and an outlet for a reaction solution at both ends or near both ends thereof, (B) both ends inside the reaction tank, A rotatable end disc provided opposite to each other, (C) an opening disc disposed between the end discs and having an opening in the center thereof, and (D) an end disc. Stirring blades that are provided between the opening disks and between the opening disks and that are provided with a predetermined gap or close contact with the inner peripheral wall surface of the reaction tank along the longitudinal direction of the reaction tank, ( E) Along the falling edge of the stirring blade where the reaction liquid starts to fall from the stirring blade, at a position where it can contact at least a part of the falling reaction liquid, substantially in parallel with the falling edge, in a double row or a single row. comprises a free surface forming member provided in a column, further, during rotation increase the gas phase portion of the reaction vessel inner periphery The edge on the side close to or close to the surface faces downward, the falling edge on the opposite side faces upward, and the edge on the side close to or close to the inner peripheral wall surface while rotating and lowering the gas phase in the reaction vessel There is provided a "horizontal reaction vessel" in which the stirring blades are inclined such that the falling edge facing upward and the opposite falling edge faces downward .
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings. FIG. 1 is a side cross-sectional view illustrating a horizontal reaction vessel for carrying out the present invention.
[0015]
In the figure, 1 is a horizontal reaction tank main body, 2 is a reaction liquid inlet, and 3 is a reaction liquid outlet, which are respectively provided at both ends or near both ends of the reaction tank 1 as shown. Reference numerals 4 and 5 denote shafts provided at both ends of the reaction tank 1. Reference numeral 6 denotes a steam outlet, which opens above the outer shell of the reaction tank and also serves as a suction port for keeping the inside of the reaction tank at reduced pressure. Reference numeral 7 denotes an inner peripheral wall surface of the reaction tank 1, and if necessary, a projection can be provided on the inner peripheral wall surface 7 so as not to interfere with the stirring blade 10. Reference numerals 8 and 9 denote end disks, which are fixed to the shafts 4 and 5, and the end disks 8 and 9 can be rotated by driving the shafts 4 and 5 by the power of a driving device (not shown). Reference numeral 10 denotes a stirring blade provided near or closely in the longitudinal direction of the inner peripheral wall surface 7, and reference numerals 11 and 12 denote free surfaces arranged in two rows in parallel with a falling edge of a reactant of the stirring blade 10. As a forming member, a round bar having a different diameter is illustrated in the embodiment of FIG. Reference numeral 13 denotes an opening disk, which is connected and fixed at predetermined intervals in the longitudinal direction by the stirring blade 10 and the round bars 11 and 12 and has an opening at the center thereof. It has the role of partitioning the interior of one into multiple rooms.
[0016]
In addition, the round bars 11 and 12, which are the free surface forming members, are positioned along the falling edge of the stirring blade where the reaction liquid starts to fall from the stirring blade 10 at a position where the reaction liquid can contact at least a part of the falling reaction liquid. , Are provided in a double row or a single row substantially parallel to the falling edge. The inside of the reaction tank 1 is partitioned into two or more chambers in the longitudinal direction by the opening disk 13 which rotates together with the stirring blade and the round bar.
[0017]
Here, while the stirring blade 10 is rotating and ascending the gaseous phase portion in the reaction vessel 1, the edge on the side close to or close to the inner peripheral wall surface 7 faces downward, and the falling edge on the opposite side faces upward. In addition, the stirring blade 10 is inclined . Then, while descending the gas phase portion in the reaction tank 1, the stirring blade 10 is inclined such that the edge on the side close to or close to the inner peripheral wall surface 7 faces upward, and the falling edge on the opposite side faces downward. Is preferred. In this way, the upper up to the stirring blade 10 is rising a vapor phase portion of the reaction vessel scraped along the reaction solution on the inner circumferential wall surface 7, the reaction solution over the stirring blade 10 during descending The reaction liquid flowing down from the stirring blade 10 can be brought into contact with the free surface forming member. In the case where the stirring blade 10 is brought into close contact with the inner peripheral wall surface 7, a tail can be additionally provided, and the tail fin can promote the renewal of the reaction solution attached to the inner peripheral wall 7.
[0018]
FIG. 2 is a front view of the opening disk 13. In the figure, reference numeral 10 denotes plate-like stirring blades inclined in the direction opposite to the rotation direction, and four blades are arranged at 90 ° in the circumferential direction of the reaction tank 1. On the extension of each stirring blade 10, round bars 11 and 12 are arranged in two rows substantially in parallel with each other along the falling edge of the reaction liquid of the stirring blade 10 as a free surface forming member. At this time, it is preferable that the diameter of the round bar 12 arranged closest to the rotation center of the stirring blade is larger than the diameter of the round bar 11 arranged farther from the rotation center. When the diameters of the round bars 11 and 12 are equal, or conversely, when the diameter of the round bar 11 is larger than the diameter of the round bar 12, it is difficult to form the liquid flow of the reactant as a multilayer film. . This is because, in such a case, most of the reaction liquid often droops from the gap between the stirring blade 10 and the round bar 11 in a united manner, so that a desired stable multi-layer film is formed. This is because it is difficult to sufficiently form a liquid flow having many free surfaces.
[0019]
As described above, in the present invention, the reaction liquid dripping from the stirring blade is further brought into contact with the free surface forming member, and the reaction liquid flows down from the stirring blade or the free surface forming member so that the multilayer liquid film or the free surface becomes as large as possible. One of the major features is to make it work. Instead of a round bar, a bar having a cross section of a polygon, an oval, an ellipse, or the like can be used, and a plate such as a flat plate or a curved plate can also be used. Can be made into a lattice shape or a net shape, or a perforated plate. Even in such a case, it is needless to say that it is preferable to make the conditions such that many free surfaces are formed when the reaction solution flows down. Therefore, it is needless to say that a free surface forming member is used so that the free surface is not reduced when the liquid flows down.
[0020]
Here, conditions such as the number, shape, and size of the stirring blades and the free surface forming member, and the intervals at which the stirring blades and the free surface forming member are installed differ depending on manufacturing conditions and the like. However, under these conditions, it is important that the falling reaction liquid is brought into contact with the free surface forming member to flow down while forming a liquid flow having a large free surface area such as a multilayer film. Further, since the melt viscosity of the reaction solution changes from the inlet to the outlet of the reaction tank, it goes without saying that these can be changed accordingly.
[0021]
This horizontal reaction tank has a heating means (not shown) for heating to a desired temperature, and the outer shell of the reactor can be directly operated by an electric heat source, and the outer shell of the production apparatus is shown in FIG. As described above, a double jacket structure is used, and a heating method in which an appropriate heating medium, for example, a heating medium liquid such as Dowsum or a heating medium vapor is present inside the jacket, and a method of installing a heat transfer surface in a reaction chamber are appropriately adopted. Can be adopted. The heating may be performed in each of the reaction chambers separated by the opening disk and / or further in the reaction chamber so that heating can be performed independently in each of the divided areas, and two or more reaction chambers are integrated. It can also be heated. Further, if necessary, a circulating means having a heat exchanger provided inside or separately from the horizontal reaction vessel of the present invention can be provided. The reaction pressure is not limited to reduced pressure, and it is needless to say that the reaction may be performed under an inert gas atmosphere at normal pressure or a pressure higher than normal pressure. Can be.
[0022]
Next, an experimental example in the case of producing polyethylene terephthalate using the horizontal reaction vessel of the present invention will be described. In the experimental examples, “intrinsic viscosity” is a value obtained from a viscosity measured at 35 ° C. using orthochlorophenol as a solvent, and “%” is% by weight.
[0023]
As a polymerization catalyst, a polyethylene terephthalate intermediate polymer having an intrinsic viscosity of 0.3 containing 0.04% of antimony trioxide was supplied at a rate of 43 kg / hr from the inlet 2 of the reaction vessel in FIG. The reactants were controlled to heat from 280 ° C. at the inlet to 285 ° C. at the outlet by heating from a jacket containing a heating medium. The reaction pressure was maintained at a vacuum of 1.5 mmHg by sucking the internal gas by an ejector (not shown). The number of rotations of the shafts 4 and 5 is controlled by a motor so as to be a constant rotation of 5 rpm, and the end disks 8 and 9 are rotated, and the stirring blades 10, which are connected and fixed to the end disks 8 and 9, The round bars 11 and 12 and the opening disk 13 were rotated. The supplied intermediate polymer was scraped up by the stirring blade, and was dropped while forming a stable two-layer liquid film from the stirring blade and the round bar in most cases. In addition, a part was rotated with the stirring blade, and the inner surface of the outer shell was constantly renewed with a new polymer. This agitation promotes the volatilization of ethylene glycol, promotes the polycondensation reaction, and flows into the next chamber mainly due to overflow from the central opening of the open disk 13 constituting the cut plate, and stays for about 1 hour. After an hour, a polyethylene terephthalate high polymer having an intrinsic viscosity of 0.66 was obtained from the outlet 3. Further, the inner peripheral wall surface 7 of the reaction vessel was constantly renewed with a new polymer due to the scraping effect of the stirring blades, so that polyethylene terephthalate with less foreign matter was used, and the reaction speed was about 1.4 times faster than the conventional method.
[0024]
【The invention's effect】
According to the present invention described above, there is provided an inexpensive horizontal reaction vessel that can significantly improve the reaction rate and the quality of a reaction product and that generates little foreign matter. In addition, the reaction solution having a simple structure can form a liquid flow having a large free surface area, such as a stable multi-layer film, for the reaction solution falling from the stirring blade, whereby the effect of significantly increasing the reaction speed can be obtained. For this reason, there is an effect that the size of the reaction layer can be made compact. Therefore, by using the horizontal reaction vessel of the present invention, it is possible to synthesize a polymer compound with less generation of foreign matter, and it is extremely useful as a fiber, film, or other molding material.
[Brief description of the drawings]
FIG. 1 is a side cross-sectional view illustrating a horizontal reaction tank for carrying out the present invention.
FIG. 2 shows a front view of the opening disk 13;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Outer shell of horizontal reaction tank 2 Reaction liquid inlet 3 Reaction liquid outlet 6 Steam outlet 7 Inner peripheral wall surface 8 and 9 End disk 10 Stirrer blade 11 Free surface forming member (small diameter round bar)
12 Free surface forming member (large diameter round bar)
13 Opening disk

Claims (3)

( A) a cylindrical reaction tank having an inlet and an outlet for a reaction liquid at both ends or near both ends thereof ;
(B) a rotatable end disk provided opposite to both ends inside the reaction tank ,
(C) an opening disc disposed between the end discs and having an opening in the center thereof ;
(D) A stirring blade installed between the end disk and the opening disk, and between the opening disks, and provided near or close to the inner peripheral wall surface of the reaction tank along the longitudinal direction of the reaction tank. When,
(E) Along the falling edge of the stirring blade where the reaction liquid starts to fall from the stirring blade, at a position where it can come into contact with at least a part of the falling reaction liquid, substantially in parallel with the falling edge, in a double row or (A) to (E) consisting of a free surface forming member provided in a single row, and a portion on the side close to or in close contact with the inner peripheral wall surface while rotating and rising the gas phase portion in the reaction tank. With the edge facing downward, the falling edge on the opposite side faces upward, and while rotating and descending the gas phase in the reaction tank, the edge on the side close to or close to the inner peripheral wall faces upward, and the falling edge on the opposite side faces upward. A horizontal reaction tank in which the stirring blades are inclined so that the edge faces downward . 2. The horizontal reaction tank according to claim 1, wherein the free surface forming members are rods provided in at least two rows. The said rod-shaped body is a round bar, The diameter of the round bar arrange | positioned at least the position closest to the rotation center of a stirring blade was larger than the diameter of the round bar adjacent to this round bar. Horizontal reaction tank.

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