JP2012007115A - Reactor and polymer synthesis equipment in which the reactor is used - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reactor in which the heat transfer efficiency from a treatment tank to a liquid raw material or the like is improved without causing an increase in equipment cost or occupying space, and to provide polymer synthesis equipment.SOLUTION: The reactor includes: a supply treatment tank 31 of a liquid raw material in a molten state or the like; and a stirring mechanism 40 which has stirring blades 45 disposed in the treatment tank 31 and a rotation driving part 42 for the stirring blades 45. A raw material supply port 35 is provided at an upper part of the treatment tank 31, a discharge port 36 is provided at the bottom part of the tank 31. The rotation shaft line of the stirring mechanism 40 is vertically arranged, and flowing-down barrier plates 46 are each disposed immediately above and/or immediately below each stirring blade 45. Further, weirs 38 are provided, in accordance with the flowing-down barrier plates 46 in the inner peripheral wall 32i of the treatment tank 31, to protrude inward in the horizontal direction so that the flow of the raw material may be inhibited. The weirs 38 are each provided substantially in the same plane as that of each flowing-down barrier plate 46, and a flowing-down gap α having a width of ≤10% of the outer diameter of the flowing-down barrier plate 46 is formed between the inner peripheral end face of each weir 38 and the outer circumferential end face of each flowing-down barrier plate 46.

Description

  The present invention relates to a processing tank to which a liquid raw material including a molten state is supplied and a reactor including a stirring blade rotatably disposed in the processing tank, and in particular, a polymer is obtained from a molten polymer raw material. The present invention relates to a reactor suitable for use in a polymer synthesis facility for synthesis.

  When a polymer is synthesized by a ring-opening polymerization reaction, quality degradation such as partial thermal decomposition and coloration of the polymer may be a problem due to a prolonged temperature history or accumulation of reaction heat accompanying polymerization.

  Polylactic acid, which is one of the polymers synthesized by ring-opening polymerization reaction, is a colorless and transparent polyester made from lactic acid as a raw material. One of the methods for synthesizing polylactic acid from lactic acid is to condense lactic acid to produce oligomers, and then add a catalyst such as antimony oxide to depolymerize to produce lactide, and then lactate to tin octylate, etc. There is a method of ring-opening polymerization by adding the above catalyst.

  Even in this case, during the ring-opening polymerization, the polylactic acid may be partly thermally decomposed and colored due to the temperature rise accompanying the heat of reaction. Since this coloration impairs the colorless transparency which is one of the characteristics of polylactic acid, it is desired to suppress it.

  Therefore, the applicant of the present invention previously prepared a plurality of reactors for ring-opening polymerization of lactide, as seen in Patent Document 1, and in the initial stage of the reaction, a horizontal reactor (see FIG. 4), a ring-opening polymerization reaction is performed to suppress the mixing of polymers having different degrees of polymerization and viscosities, and a method of suppressing the lengthening of the temperature history due to variation in residence time is proposed. .

Patent 04177769 (Japanese Patent Laid-Open No. 2005-220203)

  However, in the method described in Patent Document 1, (1) the reactor (the treatment tank and the stirring mechanism) is installed horizontally, so that the molten raw material is placed only in the lower half of the treatment tank. Since the upper half is a dead space, a reactor (processing tank) with a volume approximately twice the required processing amount is required, which increases the equipment cost and occupies the processing amount. In addition, there is a problem such as a large space, and (2) since the molten raw material is operated only in the lower half of the treatment tank, the transfer from the treatment tank functioning as a cooling heat jacket to the molten raw material is performed. Issues such as poor thermal efficiency remain.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a reactor capable of improving heat transfer efficiency to a liquid raw material without causing an increase in apparatus cost and occupied space, and the reaction. Another object of the present invention is to provide a polymer synthesis facility that can efficiently synthesize a high-quality polymer from a raw material in a molten state using a vessel.

  In order to achieve the above object, a reactor according to the present invention basically includes a treatment tank to which a liquid raw material including a molten state is supplied, a stirring blade rotatably disposed in the treatment tank, and A stirring mechanism having a drive unit for rotationally driving the stirring blade, and the treatment tank is provided with a raw material supply port at the top and a discharge port at the bottom of the processing tank. The rotation axis is arranged substantially vertically, and the falling barrier plate is arranged directly above and / or directly below the stirring blade.

  In a preferred embodiment, a weir is projected inward in the horizontal direction so as to inhibit the flow of the raw material on the inner peripheral wall of the treatment tank, corresponding to the flow-down barrier plate, and the weir and the flow-down barrier plate are In between, a flow-down gap having a predetermined width is formed.

  Moreover, the polymer synthesis equipment according to the present invention comprises a reaction device composed of one or more reactors that perform a polymerization reaction by heating a reaction solution containing a molten raw material and a catalyst, and constitute this reaction device. The reactor having the above-described configuration is used as at least one reactor.

  Since the reactor according to the present invention has a vertical configuration with respect to the conventional horizontal reactor, the heat transfer efficiency to the liquid raw material (reaction liquid) can be improved without causing an increase in apparatus cost and occupied space. obtain. Further, in a preferred embodiment, since a kind of damming plate having a flow-down gap having a predetermined width is provided, which includes a flow-down barrier plate and a dam, a molten raw material having a low viscosity and a polymer having a low degree of polymerization / viscosity are used to some extent. Mixing with a polymer having undergone a polymerization reaction is effectively suppressed, and piston flowability in the treatment tank can be ensured.

  In addition, according to the polymer synthesis equipment using the reactor according to the present invention, the temperature history derived from the dispersion of the residence time is prevented from being prolonged, so that deterioration of the polymer due to thermal decomposition is suppressed, and high A quality polymer can be obtained.

The schematic block diagram which shows one Embodiment of the reactor which concerns on this invention. A part of reactor shown by Drawing 1 is shown, (a) is a partial expansion perspective view, and (b) is a partial expansion sectional view. The figure which shows the modification of the reactor shown by FIG. The figure which shows a part of other embodiment (biaxial vertical reactor) of the reactor which concerns on this invention. The figure which is provided for the comparison description of the vertical reactor which concerns on this invention, and the conventional horizontal reactor. The figure which shows an example of the polymer synthesis equipment where the vertical reactor which concerns on this invention was used.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic configuration diagram showing an embodiment of a reactor according to the present invention, FIG. 2 shows a part of the reactor shown in FIG. 1, (A) is a partially enlarged perspective view, and (B) is It is a partial expanded sectional view.

  The reactor 30 in the illustrated example includes a lactide supply device 1 for supplying lactide, a lactide melting device 2 for heating and melting the lactide supplied from the lactide supply device 1, and the lactide melting device 2 as shown in FIG. A catalyst supply device 3 for adding a catalyst to the lactide melted in step 1 and a reaction solution (sometimes referred to simply as a molten raw material) containing the lactide and the catalyst in a molten state supplied from the catalyst supply device 3 Reactor 60 composed of two reactors 5 'and 6 connected in series for carrying out the polymerization reaction, and the remaining transported reaction liquid obtained from the reaction apparatus 60 is transported In the polymer synthesis facility provided with the lactide removal device 7, it is used as the first-stage reactor 5 ′ in the reaction device 60 (in place of the horizontal reactor 5 in FIG. 4 of Patent Document 1). It is intended.

  This polymer synthesis equipment 100 is basically the same as that described in Patent Document 1 except that the reactor 30 of the present embodiment is used as the first-stage reactor 5 ′ in the reactor 60. The same (the polymer synthesis facility 100 will be described in detail later).

  The reactor 30 (5 ′) of the present embodiment includes a cylindrical treatment tank 31 installed in a vertical position, and a stirring mechanism 40 in which a rotation axis O is disposed substantially vertically (perpendicular to a horizontal plane). And have.

  The treatment tank 31 has a bottomed cylindrical container part 32 whose center line C is arranged substantially vertically, and a detachable upper lid part 33 hermetically sealed thereto, A molten material supply port 35 is provided in the vicinity of the upper end portion, and a discharge port 36 is provided in the bottom portion 34 thereof. A heat medium is circulated and circulated in the inner space 32a of the processing tank 31, and the processing tank 31 heats and cools the molten raw material supplied from the supply port 35 therein. It is a jacket for cooling heat.

  The stirring mechanism 40 includes a drive unit 42 including a motor with a speed reducer disposed on the processing tank 31, and a shaft unit 44 that is pivotally supported on the center line C of the processing tank 31 and is rotationally driven by the drive unit 42. The rotating shaft 45 of the stirring mechanism 40 and the center line C of the treatment tank 31 are almost completely overlapped with each other.

  The stirring blade 45 is composed of a plurality of (for example, four) rectangular plates (rectangular blades) fixed radially to the shaft portion 44 at equiangular intervals (for example, 90 ° intervals). A plurality of stages (for example, four stages) are provided on the shaft portion 44 at predetermined intervals in the vertical direction.

  In addition, a circular flow-down barrier plate 46 is provided at the shaft portion 44 directly above and immediately below the stirring blades 45 of each stage (excluding the lowermost stage), in other words, alternately with the stirring blades 45 at predetermined intervals in the vertical direction. The inner peripheral part (center part) is fixed in a substantially horizontal state. Therefore, the stirring tool 43 including the shaft portion 44, the stirring blade 45, and the falling barrier plate 46 rotates integrally and can be moved integrally in the vertical direction.

  On the other hand, on the inner peripheral wall 32i of the container portion 32 in the processing tank 31, a plate-like weir inward in the horizontal direction so as to inhibit the flow of the raw material flowing down the vicinity of the inner peripheral wall 32i (the outer peripheral part in the processing tank 31). 38 protrudes. The weir 38 has an annular shape in plan view, has substantially the same thickness as the falling barrier plate 46, and is provided substantially on the same plane as the falling barrier plate 46. A flow-down gap α having a width of 10% or less of the outer diameter of the flow-down barrier plate 46 is formed between the outer peripheral end surface of the flow-down barrier plate 46.

  The outer diameter of the stirring blade 45 (twice the rotation radius = rotation diameter) is set to be the same as or slightly smaller than the outer diameter of the falling barrier plate 46 (twice the rotation radius = rotation diameter). . As a result, the stirring tool 43 including the shaft portion 44, the stirring blade 45, and the falling barrier plate 46 can be extracted upward from the processing tank 31, and maintenance convenience and the like can be achieved.

  In addition, each member which comprises the reactor 30, especially the process tank 31, and the weir 38, the axial part 44, the stirring blade 45, and the flow-down barrier board 46 distribute | arranged in it, as a raw material, corrosion resistance and heat resistance Stainless steel or titanium excellent in properties is used.

  In the reactor 30 having such a configuration (hereinafter, referred to as a vertical reactor) 30, a kind of dam plate 49 having a flow-down gap α is formed by the flow-down barrier plate 46 and the dam 38 and is arranged in the treatment tank 31. For example, the four damming plates 49 define, for example, four stirring mixing cells (chambers) 50 in which the stirring blades 45 are arranged.

  The reaction conditions in the vertical reactor 30 can be appropriately determined by those skilled in the art. The average reaction temperature in the reactor 30 is usually 140 to 180 ° C., preferably 160 to 170 ° C., and the residence time is Usually, 5 to 15 hours, preferably 7 to 10 hours. The reaction conditions are preferably set so that a polymer having a weight average molecular weight of usually 50,000 to 200,000, preferably 150,000 to 200,000 is obtained from the outlet 36 of the vertical reactor 30.

  Next, operation | movement of the vertical reactor 30 which has the said structure, an effect | action, an effect, a modification, other embodiment, etc. are demonstrated.

  In the vertical reactor 30 of the above embodiment, the supply amount of the molten raw material (reaction liquid) is not particularly limited, but is usually 20 to 100%, preferably 60 to 100% with respect to the capacity of the horizontal reactor 5. Is supplied in an amount to be inserted. Therefore, compared with the conventional horizontal reactor in which the reaction solution is introduced only about half of the reactor volume, the area where the reaction solution is in contact with the inner peripheral wall 32i of the treatment tank (cooling heat jacket) 31 is large, and the heat transfer area Can be taken widely (see FIG. 5).

  As described above, in the vertical reactor 30 of the present embodiment, the apparatus cost and the occupied space are not so different from those of the conventional horizontal reactor, but the heat transfer efficiency from the treatment tank 31 functioning as a cooling heat jacket to the reaction liquid. Can also be improved. As a result, it is possible to suppress the temperature rise of the reaction liquid by removing the reaction heat accompanying the polymerization of the raw material by heat transfer, and effectively suppress the degradation due to thermal decomposition of the produced polymer at the latter stage of the polymerization reaction. And coloring can be prevented. In particular, in the ring-opening polymerization of lactide, coloring of polylactic acid can be effectively prevented. In addition, by forming unevenness on the inner peripheral wall 32i, the heat transfer area can be further increased, and the heat transfer efficiency can be further improved.

  The molten raw material (molten lactide) supplied to the vertical reactor 30 is cooled by heat from the uppermost stirring / mixing cell 50 to the lower cell 50 in order due to a head difference between the supply port 35 and the discharge port 36. The liquid flows down while being heated by the treatment tank 31 functioning as a jacket for use and being stirred by the stirring blade 45 that is rotationally driven. In each cell 50, the reaction liquid is made uniform by stirring with the stirring blade 45. That is, the influence of the raw material melt having a low viscosity and the low viscosity polymer having a low degree of polymerization flowing faster than the high viscosity polymer having a high degree of polymerization can be suppressed.

  In this case, the reaction solution freely falls from the flow-through gap α formed between the flow-down barrier plate 46 and the weir 38 by gravity and flows into the cell 50 at the subsequent stage. At this time, if the width of the gap α is too large, the speed of free fall from the gap α exceeds the speed component perpendicular to the rotation axis O generated by the stirring blade 45, so that the reaction liquid is made uniform by stirring. This is not desirable because the reaction solution falls into the subsequent cell 50 without waiting. That is, the flow rate of the reaction liquid to the downstream cell 50, in other words, the residence time (stirring time) in one cell 50 is determined by the width of the gap α, so the width of the gap α is set appropriately. There is a need to. When the vertical reactor 30 is used as the first reactor 5 ′ in the reactor 60 of the polymer synthesis facility 100, the width of the gap α is usually 0.1 to the outer diameter of the falling barrier plate 46. It is desirable to be 10%, preferably 1 to 5%.

  As described above, in the vertical reactor 30 of the present embodiment, there are provided a kind of damming plates 49, 49,... Each having a predetermined width of the flow-down gap α, which includes the flow-down barrier plate 46 and the weir 38. In addition, since some of the stirring and mixing cells (chambers) 50, 50,... Are defined by the damming plates 49, 49,. Mixing of the polymer with a polymer having undergone a polymerization reaction to some extent is effectively suppressed, and the piston flow property in the treatment tank 31 can be ensured. And it can prevent that a reaction liquid moves to the following process with unreacted, and can perform sufficient reaction in the said vertical reactor 30. FIG. Therefore, since the prolonged temperature history resulting from the dispersion | variation in residence time is prevented, deterioration of the polymer by thermal decomposition is suppressed and a high quality polymer can be obtained.

  In the above-described embodiment, the shaft portion 44 is disposed on the rotation axis O, and the stirring blade 45 and the falling barrier plate 46 are connected via the shaft portion 44. The shaft portion 44 does not necessarily exist between the falling flow barrier plates 46 to 46. For example, as shown in FIG. 3, the stirring blade 45 ′ and the falling flow barrier plate 46 are arranged at their centers. You may make it connect with the rod 48 grade | etc., In site | parts other than a part.

  Further, the stirring blade 45, the flow-down barrier plate 46, and the shaft portion 44 are integrally connected to rotate integrally. However, the flow-down barrier plate 46 is not necessarily rotated, and the treatment tank 31 is not necessarily rotated. It may be held and fixed by a stay or the like.

  The shape of the treatment tank 31 may be a tank type or a cylindrical shape, and is not particularly limited, but is preferably a cylindrical shape.

  The stirring blade 45 is not particularly limited as long as stirring is performed by rotation about the rotation axis O. The shape of the blades constituting the stirring blade 45 is not limited to the rectangular shape as in the above embodiment, and may be, for example, a circular shape, an oval shape, a triangular shape, a trapezoidal shape, a multi-leaf shape, or the like. The number of blades, the mounting posture, and the like are not particularly limited.

  In the above embodiment, the single-shaft vertical reactor 30 having only one stirrer 43 including the stirrer blade 45, the falling barrier plate 46, and the shaft portion 44 is shown, but a plurality of the stirrers 43 are arranged in parallel. You may make it install.

  FIG. 4 shows a part of an example (another embodiment) of a biaxial vertical reactor 30 ′ in which two stirring tools 43 (43 </ b> A and 43 </ b> B) are arranged side by side. The biaxial vertical reactor 30 ′ is arranged such that the stirring blades 45 and 45 are meshed with each other, and the falling barrier plates 46 and 46 are partially overlapped in plan view with a minute gap β therebetween. The stirring tool 43B is rotated in the reverse direction with respect to the stirring tool 43A.

  In such a biaxial vertical reactor 30 ′, the stirring blades 45, 45 mesh with each other, so that the reaction liquid can be prevented from adhering to the stirring tools 43 </ b> A, 43 </ b> B.

  Further, by making the gap β between the falling barrier plates 46-46 sufficiently small, the reaction solution is prevented from flowing down rapidly, and at the same time, the reaction solution flows upward due to the motion of the stirring blades 45, 45. Can be minimized.

  As a result, similarly to the uniaxial vertical reactor 30, the melt raw material having a low viscosity and the polymer having a low polymerization degree / viscosity are prevented from being mixed with the polymer having undergone a polymerization reaction to some extent. 'Piston flow can be ensured. And it can prevent that a reaction liquid moves to the following process with unreacted, and sufficient reaction can be performed in the said reactor 30 '. Therefore, since the prolonged temperature history resulting from the dispersion | variation in residence time is prevented, deterioration of the polymer by thermal decomposition is suppressed and a high quality polymer can be obtained.

  In addition, as a heating means in the vertical reactor 30, those commonly used in the technical field can be used, and a method other than the method of using the treatment tank 31 as a heating / cooling jacket through which a heating medium flows as in the above embodiment. In addition, for example, there are various methods such as a method in which a heat medium is passed through the shaft portion 44 and heated by heat transfer, a method using a heating wire heater instead of the heat medium, and these can be used alone or in combination. May be used. In addition, when heating the reactor 30, it is preferable to heat at fixed temperature.

  The molten raw material supplied into the vertical reactor 30 is initially heated and polymerized by the above heating method. However, when the temperature of the reaction liquid becomes higher than that of the heating medium due to the temperature rise caused by the reaction heat, the molten raw material is reversed from the reaction liquid. Heat escapes to the heat medium. That is, the heating method can also act as a cooling method. Therefore, in the case of a polymer in which reaction heat is generated by the polymerization reaction, heat can be effectively released, which is advantageous.

  If necessary, a heating method may be used in which the inside of the reactor is divided into a plurality of regions, and the temperature of the heating medium can be changed for each of the divided regions. Therefore, it is conceivable to use a plurality of jackets for heating and cooling. In this case, if the inside of the reactor 30 is divided by the blocking plate 49, for example, as in the above embodiment, the heat medium temperature is set high in the region where the low-temperature reaction liquid is heated, and the reaction liquid temperature is set by the reaction heat. On the contrary, in a region where heat removal is necessary and heat removal is required, the temperature of the heat medium can be set low. A temperature gradient can also be set inside the reactor 30 by supplying the heating medium heated by the heating medium heating device to the vicinity of the supply port 35. When the temperature of the heating medium is lowered, there is a possibility that part of the melt is solidified and adheres to the inner surface of the reactor.

  In this specification, “substantially vertically”, “substantially horizontally” and the like are described as having an error within about 5 degrees with respect to a completely strict vertical line or horizontal line. State.

  Next, the polymer synthesis equipment 100 using the vertical reactor 30 will be described with reference to FIG.

  The polymer synthesis facility 100 in the illustrated example is for polylactic acid synthesis, and constitutes the reaction apparatus 60. The vertical reactor 5 ′ (30) and the high-viscosity reactor 6 of the above-described embodiment connected in series It has. A lactide supply device 1, a lactide melting device 2, a catalyst supply device 3, and a lactide supply device 4 are disposed on the front side of the reaction device 60, and a residual lactide removal device 7 is disposed on the rear side of the reaction device 60. The devices are connected by a conduit or the like, and the transport piping system is provided with liquid feed pumps 8 to 13, valves 14 to 29, and the like. The liquid feed pumps 8 to 13 may be partially omitted when the liquid to be transported has a low viscosity and can be fed using gravity. Further, the valves 14 to 25 can be omitted as necessary.

  The lactide supply device 1 supplies powdered lactide to the lactide melting device 2. As a transportation method of the lactide supply apparatus 1, there are methods such as transportation using a screw feeder, transportation using ultrasonic vibration, transportation using a gas flow, and the like. In the lactide melting device 2, the sent lactide is heated and melted. The temperature at that time is not less than the melting point of lactide, and preferably not more than 160 ° C. so as not to cause deterioration due to heat. The molten lactide generated by the lactide melting device 2 is transported to the catalyst supply device 3 by the liquid feed pump 8. In the catalyst supply device 3, the catalyst is supplied to the molten lactide. The molten lactide to which the catalyst has been added is supplied to the lactide supply device 4 by the liquid feed pump 9. In the lactide supply device 4, the temperature of the molten lactide is maintained in the range of the melting point of lactide or higher and desirably 160 ° C. or lower. The lactide supply device 4 is essentially a buffer tank for the subsequent reactors 5 'and 6 and can be omitted if not necessary. The molten lactide in the lactide supply device 4 is supplied to the vertical reactor 5 ′ by the liquid feed pump 10. In addition, when the lactide supply apparatus 4 is abbreviate | omitted, the liquid feeding pump 10 is also unnecessary. The liquid supply pipes before and after the liquid supply pumps 8 to 10 are all kept at a temperature higher than the melting point of lactide, preferably within a range of 160 ° C. or lower by heating and heat retention, etc., in order to avoid lactide coagulation and blockage due to temperature drop. Is done.

  In the vertical reactor 5 ′, as described above, molten lactide flows due to the head difference between the supply port and the discharge port, and the polymerization reaction proceeds. In the vertical reactor 5 ′, the reaction liquid is heated by a cooling heat jacket. The reaction liquid in the vertical reactor 5 ′ is transported to the high viscosity vertical reactor 6 by gravity and a liquid feed pump 11. As for the liquid feed pump 11, an extraction screw, a gear pump, or the like can be selected according to the viscosity of the reaction liquid. Further, when the reaction liquid can be extracted from the vertical reactor 5 by gravity, the liquid feeding pump 11 can be omitted. The transportation piping before and after the liquid feeding pump 11 needs to be heated and kept warm in order to avoid clogging due to the solidification of the internal reaction liquid. The temperature at that time is preferably 200 ° C. or lower so that the reaction solution does not thermally decompose.

  The reaction solution is transported to a supply port installed at the upper part of the high-viscosity vertical reactor 6, flows toward the discharge port at the lower part of the high-viscosity vertical reactor 6 by gravity, and the polymerization reaction proceeds. Thereby, it can prevent that the polymer with a low polymerization degree mixes in the polymer with a high polymerization degree. In the high-viscosity vertical reactor 6, the reaction liquid is heated by a heat medium jacket on the outer periphery of the reactor.

  As the high-viscosity vertical reactor 6, one commonly used in this technical field can be used, but here, it has two rotating shafts equipped with stirring blades, which are suitable for stirring a high-viscosity polymer. A stirrer (hereinafter referred to as a biaxial stirrer) is used. The reaction liquid inside the vertical reactor 6 is transported to the residual lactide removing device 7 by gravity and a liquid feed pump 12. As the liquid feed pump 12, similarly to the liquid feed pump 11, an extraction screw, a gear pump, or the like can be selected according to the viscosity of the reaction liquid. The transportation piping before and after the liquid feed pump 12 needs to be heated and kept warm in order to avoid clogging due to the solidification of the internal reaction liquid. The temperature at that time is preferably 200 ° C. or lower so that the polymer is not thermally decomposed.

  The residual lactide removing device 7 creates a negative pressure environment while maintaining a molten state, and removes unreacted lactide. The treated reaction liquid is discharged by the liquid feed pump 13. As the liquid feed pump 13, similarly to the liquid feed pump 11, an extraction screw, a gear pump, or the like can be selected according to the viscosity of the reaction liquid. The discharged polymer is usually subjected to water cooling and pelletizing with a chip cutter.

  The polymer synthesis facility 100 of the present embodiment has the vertical reactor 5 '(30) at least in the first stage, but may further have a vertical reactor in the second and subsequent stages. The shape of the reactor other than the first stage is not particularly limited, and those usually used in this technical field can be used. The above embodiment uses a reaction apparatus including a vertical reactor in the first stage, but uses a reaction apparatus including a tank in which the polymerization reaction is not substantially performed in the previous stage. Such cases are also included in the scope of the present invention.

  Using the polymer synthesis facility 100 shown in FIG. 6, polylactic acid was synthesized in the following manner. The temperature of the lactide melting apparatus 2 was set to 120 ° C., and molten lactide (molecular weight 144) in which a catalyst and a polymerization initiator were dispersed was supplied to the vertical reactor 5 ′ at 120 ° C. In the vertical reactor 5 ′, the reaction solution was maintained at an average temperature of 170 ° C. and a residence time of 10 hours. In the first half of the residence time, it is heated by heat conduction from the jacket on the outer periphery of the reactor, and in the second half, the temperature of the polymer itself increases with the reaction heat accompanying the polymerization, but some of the reaction heat is It was removed by heat conduction through the inner wall. The polylactic acid discharged from the vertical reactor 5 ′ has a polymerization reactivity (conversion rate) of 55% (polymerization reactivity = 1−residual lactide concentration / initial lactide concentration), a weight average molecular weight of 170,000, and a viscosity of 250 Pa.・ It was about s.

  This polymer was then fed to the high viscosity vertical reactor 6. In the vertical reactor 6, the polymer was maintained at an average temperature of 190 ° C. and a residence time of 5 hours. During the residence time, the temperature of the polymer itself increased with the heat of reaction accompanying the polymerization, but a part of the heat of reaction was removed by heat conduction through the inner wall of the reactor. As the polymerization reaction progresses, the heat generation rate per unit volume decreases, so while the heat generation rate exceeds the heat removal rate by heat conduction, the temperature of the polymer itself rises, but when it becomes lower, the polymer product Its temperature drops. The polylactic acid discharged from the vertical reactor 6 had a polymerization reactivity of 90%, a weight average molecular weight of 270,000, and a viscosity of about 2500 Pa · s.

  When the hue (b) of the obtained polylactic acid was measured with a chromaticity meter, b = 4. From the above, it has been clarified that the polymer synthesis facility 100 shown in FIG. 6 can obtain high-quality polylactic acid with little b = 4 or less coloring.

  In addition, the number of reactors included in the reactor 60 for polymerizing the raw material may be two or more, and is usually 2 to 4, preferably 2 to 3, more preferably 2.

  Further, in the polymer synthesis facility of the present invention, a remaining raw material removing device can be installed at the rear stage of the reaction apparatus for polymerization to remove unreacted raw materials from the reaction liquid discharged from the reaction device. In the residual raw material removing apparatus, an unreacted raw material such as lactide is removed by creating a negative pressure environment while maintaining a molten state.

  Furthermore, although the polymer obtained through the synthesis method of the present invention is usually subjected to water cooling and pelletizing treatment with a chip cutter, these treatments can be omitted.

  Nitrogen gas for purging the interior with nitrogen gas is used in the raw material melting apparatus, catalyst supply apparatus, reaction apparatus including a vertical reactor, residual raw material removal apparatus, etc. used in the polymer synthesis facility of the present invention. It is preferable that a supply pipe and an exhaust pipe are installed. And the operation of the synthesis process is basically preferably started after all the equipment in the process has been purged with nitrogen. Thereby, scorching of the reaction liquid due to the presence of oxygen can be prevented. The raw material melting apparatus, catalyst supply apparatus, raw material supply apparatus, horizontal reactor, vertical reactor and the like are preferably operated at a pressure of about atmospheric pressure. By doing so, volatilization of the molten raw material can be reduced.

  The polymer synthesis facility of the present invention is suitably used for a polymerization reaction of a polymer that generates heat of reaction with a polymerization reaction. Such polymers include those produced by ring-opening polymerization reactions or addition polymerization reactions. About the polymer produced | generated by ring-opening polymerization reaction, it uses suitably for the polymerization reaction of the polymer synthesize | combined by the ring-opening polymerization reaction of a cyclic polymer raw material, especially a cyclic dimer, especially polyester. For example, polylactic acid, a copolymer containing lactic acid as a main component, polyglycolic acid, a copolymer containing glycolic acid as a main component, and the like can be given. Examples of the polymer produced by the addition polymerization reaction in which the apparatus of the present invention is suitably used include polystyrene, polyvinylene carbonate, polyacrylonitrile, polymethyl methacrylate, polymethyl methacrylate, poly (cellulose acetate), poly (vinyl acetate), and the like. The copolymer containing is mentioned.

  The polymer synthesis facility of the present invention is particularly preferably used for the synthesis of polylactic acid by ring-opening polymerization of lactide. Here, lactide used as a raw material for polylactic acid means a cyclic ester produced by dehydrating two molecules of water from two molecules of lactic acid, and polylactic acid means a polymer mainly composed of lactic acid, Poly L-lactic acid homopolymer, poly D-lactic acid homopolymer, poly L / D-lactic acid copolymer, and other ester bond forming components such as hydroxy carboxylic acid, lactones, dicarboxylic acid and diol Copolymerized polylactic acid obtained by copolymerizing and the like, and those in which additives are mixed as secondary components are included. Examples of hydroxycarboxylic acids include glycolic acid, hydroxybutylcarboxylic acid, and hydroxybenzoic acid. Examples of lactones include butyrolactone and caprolactone. Examples of dicarboxylic acids include aliphatic dicarboxylic acids having 4 to 20 carbon atoms, phthalic acid. Examples of the acid, isophthalic acid, terephthalic acid, aromatic dicarboxylic acids such as naphthalenedicarboxylic acid, and diols include aliphatic diols having 2 to 20 carbon atoms. Polyalkylene ether oligomers and polymers such as polyethylene glycol, polypropylene glycol, and polybutylene ether are also used as copolymerization components. Similarly, oligomers and polymers of polyalkylene carbonate are also used as copolymerization components. Examples of additives include antioxidants, stabilizers, ultraviolet absorbers, pigments, colorants, inorganic particles, various fillers, mold release agents, plasticizers, and the like. The addition ratio of these copolymerization components and additives is arbitrary, but the main component is lactic acid or derived from lactic acid, and the copolymerization components and additives are preferably 50% by weight or less, particularly preferably 30% or less.

  The polymer synthesis facility of the present invention is particularly preferably used for the synthesis of polylactic acid by ring-opening polymerization of lactide. Here, lactide used as a raw material for polylactic acid means a cyclic ester produced by dehydrating two molecules of water from two molecules of lactic acid, and polylactic acid means a polymer mainly composed of lactic acid, Poly L-lactic acid homopolymer, poly D-lactic acid homopolymer, poly L / D-lactic acid copolymer, and other ester bond forming components such as hydroxy carboxylic acid, lactones, dicarboxylic acid and diol Also included are copolymerized polylactic acid obtained by copolymerizing the above, and those in which additives are mixed as secondary components. Examples of hydroxycarboxylic acids include glycolic acid, hydroxybutylcarboxylic acid, and hydroxybenzoic acid. Examples of lactones include butyrolactone and caprolactone. Examples of dicarboxylic acids include aliphatic dicarboxylic acids having 4 to 20 carbon atoms, phthalic acid. Examples of the acid, isophthalic acid, terephthalic acid, aromatic dicarboxylic acids such as naphthalenedicarboxylic acid, and diols include aliphatic diols having 2 to 20 carbon atoms. Polyalkylene ether oligomers and polymers such as polyethylene glycol, polypropylene glycol, and polybutylene ether are also used as copolymerization components. Similarly, oligomers and polymers of polyalkylene carbonate are also used as copolymerization components. Examples of additives include antioxidants, stabilizers, ultraviolet absorbers, pigments, colorants, inorganic particles, various fillers, mold release agents, plasticizers, and the like. The addition ratio of these copolymerization components and additives is arbitrary, but the main component is lactic acid or derived from lactic acid, and the copolymerization components and additives are preferably 50% by weight or less, particularly preferably 30% or less.

  The polymer synthesis equipment of the present invention is an apparatus for continuously or intermittently synthesizing a polymer by polymerizing a polymer raw material in a molten state, and heating a reaction liquid containing the raw material and a catalyst in a molten state with the reaction apparatus. The polymerization reaction is performed. The raw material means a monomer, a cyclic monomer, a cyclic dimer of the monomer, an oligomer, and the like, which are constituent elements for synthesizing a polymer by a polymerization reaction. In the synthesis of polylactic acid, lactide is used as a raw material, a reaction liquid containing raw material lactide and a catalyst in a molten state is heated in a reaction apparatus, and lactide is polymerized in a molten state by performing a ring-opening polymerization reaction of lactide. To synthesize polylactic acid continuously or intermittently. In the present specification, the reaction liquid refers to a molten polymer material, a mixture of a molten raw material and a catalyst, a mixture of a molten raw material, a catalyst, and a polymer having various degrees of polymerization, or a melt or product that circulates in a polymer synthesis process Etc. shall be included.

  In the polymer synthesis facility of the present invention, continuous or intermittent synthesis has the meaning normally used in the art, and at least partly overlaps the time period during which the raw material is supplied and the product polymer is discharged. In some cases, the raw material is supplied continuously or intermittently, and the polymer is discharged continuously or intermittently.

  When the raw material is in a molten state, the catalyst can be added to the molten raw material as it is and supplied to the reaction apparatus to be subjected to a polymerization reaction. However, if the raw material is in a solid form such as powder, the raw material melting apparatus The raw material is melted in advance by heating the raw material with The heating temperature in the raw material melting apparatus is not particularly limited as long as it is equal to or higher than the melting point of the raw material. Therefore, when the raw material is lactide, it is not particularly limited as long as it is 95 ° C. or higher, but it is usually 95 to 160 ° C., preferably 110 to 130 ° C. By setting the temperature to 160 ° C. or less, deterioration of lactide due to heat can be prevented.

  As a catalyst for the polymerization reaction, those skilled in the art can appropriately select a suitable catalyst depending on the polymer to be synthesized. For example, as the catalyst used for the ring-opening polymerization of lactide, a conventionally known polylactic acid polymerization catalyst can be used, for example, selected from the group consisting of groups IA, IVA, IVB and VA of the periodic table A catalyst comprising at least one metal or metal compound can be used.

  Examples of those belonging to the group IVA include organotin-based catalysts (for example, tin lactate, tin tartrate, tin dicaprylate, tin dilaurate, tin dipalmitate, tin distearate, tin dioleate, tin α-naphthoate). , Β-naphthoic acid tin, octylic acid tin, etc.), and powdered tin. Examples of those belonging to Group IA include alkali metal hydroxides (for example, sodium hydroxide, potassium hydroxide, lithium hydroxide), alkali metal and weak acid salts (for example, sodium lactate, sodium acetate, sodium carbonate). Sodium octylate, sodium stearate, potassium lactate, potassium acetate, potassium carbonate, potassium octylate, etc.), alkali metal alkoxides (eg sodium methoxide, potassium methoxide, sodium ethoxide, potassium ethoxide, etc.) Can be mentioned. Examples of those belonging to Group IVB include titanium compounds such as tetrapropyl titanate and zirconium compounds such as zirconium isopropoxide. Examples of those belonging to Group VA include antimony compounds such as antimony trioxide. Among these, an organotin catalyst or a tin compound is particularly preferable from the viewpoint of activity.

  The catalyst can be added to the molten raw material by a catalyst addition apparatus usually used in the art. The catalyst may be added to the molten raw material and then supplied to the reactor, or the catalyst may be added directly to the reactor.

DESCRIPTION OF SYMBOLS 1 ... Lactide supply apparatus 2 ... Lactide melting apparatus 3 ... Catalyst supply apparatus 4 ... Lactide supply apparatus 5 '... Vertical reactor 6 ... Vertical reactor for high viscosity,
7 ... Residual lactide removal device 30 ... Vertical reactor 31 ... Process tank 35 ... Supply port 36 ... Discharge port 38 ... Weir 40 ... Agitating mechanism 42 ... Drive Part 43 ... Stirring tool 44 ... Shaft part 45 ... Stirring blade 46 ... Falling barrier plate 49 ... Damping plate 50 ... Stirring mixing cell 60 ... Reactor

Claims (20)

A processing tank to which a liquid raw material including a molten state is supplied; a stirring blade rotatably disposed in the processing tank; and a stirring mechanism having a drive unit for rotationally driving the stirring blade. A reactor comprising:
The treatment tank is provided with a raw material supply port at the top and a discharge port at the bottom, the rotation axis of the stirring mechanism is disposed substantially vertically, and directly above the stirring blade and / or Alternatively, a reactor characterized in that a falling barrier plate is arranged directly below.   The reactor according to claim 1, wherein the falling barrier plate is formed in a circular shape and connected to the stirring blade.   The reactor according to claim 1, wherein the falling barrier plate is disposed substantially horizontally.   The shaft portion that is rotationally driven by the drive portion is provided on the rotation axis, and the stirring blade and the falling barrier plate are fixed to the shaft portion. The reactor described.   The reactor according to any one of claims 1 to 4, wherein the stirring blade and the falling barrier plate are connected to each other at a portion other than the central portion thereof.   The reactor according to any one of claims 1 to 5, wherein the stirring blade is composed of a plurality of blades radially arranged in a plan view.   The reactor according to any one of claims 1 to 6, wherein the stirring blades and the falling barrier plate are alternately arranged in a plurality of stages.   8. A weir is provided on the inner peripheral wall of the treatment tank so as to protrude inward in the horizontal direction so as to inhibit the flow of the raw material corresponding to the flow-down barrier plate. A reactor according to any one of the above.   The reactor according to claim 8, wherein the weir is formed in an annular shape in plan view, and a flow-down gap is formed between the weir and the flow-down barrier plate.   The weir is provided on substantially the same plane as the falling barrier plate, and is 10% or less of the outer diameter of the falling barrier plate between the inner peripheral end surface of the weir and the outer peripheral end surface of the falling barrier plate. 10. The reactor according to claim 8, wherein a flow-down gap having a width is formed.   The reactor according to any one of claims 1 to 10, wherein a center line of the treatment tank and a rotation axis of the stirring mechanism are almost completely overlapped with each other.   The reactor according to any one of claims 1 to 11, wherein a plurality of stirring tools each including the stirring blade and a falling barrier plate are arranged in parallel in the treatment tank.   The plurality of stirring tools are arranged such that their stirring blades mesh with each other, and their flow-down barrier plates are arranged so as to partially overlap in a plan view with a minute gap vertically between them. The reactor according to claim 12.   The reactor according to any one of claims 1 to 13, wherein an outer diameter or a rotating diameter of the stirring blade is set to be equal to or smaller than an outer diameter or a rotating diameter of the falling barrier plate.   The reactor according to any one of claims 1 to 14, wherein the stirring tool composed of the stirring blade, the falling barrier plate, and the like can be extracted vertically from the inside of the treatment tank.   The reactor according to any one of claims 1 to 15, further comprising heating means for heating the raw material supplied into the processing tank.   The reactor according to any one of claims 1 to 15, wherein the treatment tank is a jacket for heating and cooling for heating and cooling the raw material. A polymer synthesis facility comprising a reaction device composed of one or more reactors that perform a polymerization reaction by heating a reaction liquid containing a molten raw material and a catalyst,
A polymer synthesis facility, wherein the reactor according to any one of claims 1 to 17 is used as at least one reactor constituting the reactor. A polymer synthesis facility comprising a reaction device composed of two or more reactors connected in series to perform a polymerization reaction by heating a reaction liquid containing a molten raw material and a catalyst,
A polymer synthesis facility, wherein the reactor according to any one of claims 1 to 17 is used as a first-stage reactor in the reactor.   A lactide supply device for supplying lactide, a lactide melting device for heating and melting lactide supplied from the lactide supply device, a catalyst supply device for adding a catalyst to the molten lactide sent from the lactide melting device, and the catalyst supply device A reactor having a reactor and a high-viscosity reactor according to any one of claims 1 to 17, for carrying out a polymerization reaction by heating a reaction liquid containing a molten raw material and a catalyst supplied from A polymer synthesis facility, comprising: a residual lactide removing device that transports a reaction liquid obtained by the polymerization reaction obtained from the device.

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