Reactor, method for producing vinyl polymers, and method for producing vinyl polymers

Abstract

This batch-type reaction apparatus used for producing a polymer by suspension polymerization using a dispersion auxiliary agent comprises: a reactor having a cylindrical straight body part; a plurality of first cooling pipes disposed inside the reactor and used for circulating a refrigerant; and a stirring shaft disposed inside the reactor, having a stirring blade attached thereto, and configured so as to be rotatable. A representative point of each of the plurality of first cooling pipes in a plane substantially perpendicular to the extension direction of the straight body part is substantially positioned on the circumference of any one of a plurality of virtual circles disposed substantially concentrically in the substantially perpendicular plane. The number Nc [number] of the plurality of virtual circles and the ratio CZ [mg (dispersion auxiliary agent) / kg (monomer)] of the mass of the dispersion auxiliary agent to the mass of one or more types of monomers which are starting materials for the polymer, satisfy a specific relationship.

Description

[Technical field]

[0001] The present invention relates to a reactor, a process for producing vinyl polymers, and a method for producing vinyl polymers. [Background technology]

[0002] Patent Document 1 discloses a polymerization apparatus equipped with a baffle and a serpentine pipe through which a coolant can flow. Patent Document 2 discloses a polymerization apparatus equipped with a baffle and a coiled cooling pipe through which a coolant can flow. Patent Document 3 discloses a resin synthesis apparatus equipped with a baffle through which a heat transfer medium can flow and a stirring means having a helical ribbon blade and an anchor blade. [Prior art document] [Patent documents] [Patent Document 1] Japanese Patent Application Laid-Open No. 7-233202 [Patent Document 2] Japanese Patent Application Laid-Open No. 7-233206 [Patent Document 3] JP 2013-151621 A General Disclosure

[0003] In a first aspect of the present invention, a reaction apparatus is provided. The reaction apparatus is used, for example, to produce a polymer by suspension polymerization using a dispersion aid. The reaction apparatus is, for example, a batch reaction apparatus. The reaction apparatus includes, for example, a reactor having a cylindrical straight body. The reaction apparatus includes, for example, a plurality of first cooling pipes arranged inside the reactor for circulating a coolant. The reaction apparatus includes, for example, a stirring shaft arranged inside the reactor, to which stirring blades are attached, and configured to be rotatable.

[0004] In the above reaction apparatus, the representative points of the first cooling pipes on a plane substantially perpendicular to the extension direction of the body are located, for example, on the circumference of one of a plurality of imaginary circles arranged substantially concentrically on the substantially perpendicular plane. In the above reaction apparatus, when the number Nc of the imaginary circles is 1, 2, or 3, the number Nc of the imaginary circles and the ratio CZ (mg-dispersing agent / kg-monomer) of the mass of the dispersing agent to the mass of one or more types of monomers serving as raw materials for the polymer satisfy, for example, the relationship shown in the following formula A1. (Formula A1) 15Nc+300 <CZ<175Nc+2000

[0005] In any of the above reaction apparatuses, when the number Nc of the multiple virtual circles is 4 or more, the ratio CZ [mg / kg] may satisfy the relationship shown in the following formula A2. (Formula A2) 15×3+300 <CZ<175×3+2000

[0006] In any of the above reaction apparatuses, when the number Nc [pieces] of the multiple virtual circles is 1, 2 or 3, the number Nc [pieces] and the ratio CZ [mg-dispersing aid / kg-monomer] may satisfy the relationship shown in the following formula B1. (Formula B1) 15Nc+310 <CZ<175Nc+1550

[0007] In any of the above reaction apparatuses, when the number Nc [pieces] of the multiple virtual circles is 1, 2 or 3, the number Nc [pieces] and the ratio CZ [mg-dispersing aid / kg-monomer] may satisfy the relationship shown in the following formula C1. (Formula C1) 15Nc+400 <CZ<175Nc+1850

[0008] In any of the above reaction apparatuses, when the number Nc [pieces] of the multiple virtual circles is 1, 2 or 3, the number Nc [pieces] and the ratio CZ [mg-dispersing aid / kg-monomer] may satisfy the relationship shown in the following formula D1. (Formula D1) 15Nc+400 <CZ<175Nc+1550

[0009] Any of the above reaction devices may be provided with a dispersion aid injection part that injects a dispersion aid into the reactor. In any of the above reaction devices, the dispersion aid injection part may inject a dispersion aid so that when the number Nc [pieces] of the multiple virtual circles is 1, 2 or 3, the number Nc [pieces] and the ratio CZ [mg-dispersion aid / kg-monomer] satisfy the relationship shown in the above formula A1, formula B1, formula C1 or formula D1.

[0010] In a second aspect of the present invention, a reaction apparatus is provided. The reaction apparatus is used, for example, to produce a polymer by suspension polymerization using a dispersion aid. The reaction apparatus is, for example, a batch-type reaction apparatus. The reaction apparatus includes, for example, a reactor having a cylindrical straight body. The reaction apparatus includes, for example, a plurality of first cooling pipes arranged inside the reactor for circulating a coolant. The reaction apparatus includes, for example, a stirring shaft arranged inside the reactor, to which one or more stirring blades are attached and which is configured to be rotatable. The reaction apparatus includes, for example, a dispersion aid input section for inputting a dispersion aid into the reactor.

[0011] In the above-mentioned reaction apparatus, the representative points of each of the first cooling pipes on a plane substantially perpendicular to the extension direction of the straight body portion are, for example, located on the circumference of one of a plurality of imaginary circles arranged substantially concentrically on the substantially perpendicular plane. In the above-mentioned reaction apparatus, the dispersion aid introduction section introduces the dispersion aid so that, for example, when the number Nc [pieces] of the plurality of imaginary circles is 1, 2 or 3, the number Nc [pieces] of the plurality of imaginary circles and the mass ratio CZ [mg-dispersion aid / kg-monomer] of the dispersion aid to the mass of one or more types of monomers serving as raw materials for the polymer satisfy the relationship shown in the following formula A1. (Formula A1) 15Nc+300 <CZ<175Nc+2000

[0012] In any of the reaction devices according to the first or second aspect, the stirring shaft may be configured so that multiple stirring blades can be attached at different positions in the extension direction of the stirring shaft. In any of the reaction devices described above, the dimension of the straight body part, the dimension of at least one of the multiple stirring blades, and the set value of the rotation speed of the stirring shaft may satisfy the relationship shown in the following formula 1. (Formula 1) N(b / d)(L / D) / n≦6.0 In formula 1, N represents the number of impellers, b represents the maximum impeller width [m] of the impellers, d represents the maximum impeller diameter [m] of the impellers, L represents the length [m] of the straight body portion in the extension direction, D represents the maximum diameter [m] of the inscribed circles that are approximately inscribed in the straight body portion in each of the cross sections formed by the multiple planes that are approximately perpendicular to the extension direction of the straight body portion and pass through the respective mounting positions of the multiple impellers, and n represents the set value of the rotation speed [rps] of the agitator shaft.

[0013] In any of the above reaction devices, each of the plurality of first cooling pipes may have a serpentine portion that extends while repeatedly bending. In any of the above reaction devices, the serpentine portion may include a plurality of extension portions that extend linearly or curvedly. In any of the above reaction devices, the serpentine portion may include a plurality of bent portions that connect ends of two adjacent extension portions among the plurality of extension portions.

[0014] In any of the above reaction apparatuses, each of the first cooling pipes may include a plurality of ring portions having a ring shape. In any of the above reaction apparatuses, each of the first cooling pipes may include one or more connecting portions connecting the plurality of ring portions.

[0015] Any of the above reactors may include a plurality of baffles extending approximately parallel to the extending direction of the body portion. Any of the above reactors may include a second cooling pipe disposed inside at least one of the baffles for circulating a coolant.

[0016] In a third aspect of the present invention, there is provided a method for producing a vinyl polymer, which comprises, for example, polymerizing a vinyl monomer using any one of the reaction apparatuses according to the first or second aspect to produce a vinyl polymer.

[0017] In a fourth aspect of the present invention, there is provided a method for producing a vinyl polymer, for example, a method for producing a vinyl polymer by suspension polymerization using a batch-type reactor.

[0018] In the above method, the reaction apparatus includes, for example, a reactor having a cylindrical straight body portion. In the above method, the reaction apparatus includes, for example, a plurality of first cooling pipes arranged inside the reactor for circulating a coolant. In the above method, the reaction apparatus includes, for example, a stirring shaft arranged inside the reactor, to which a stirring blade is attached and configured to be rotatable. In the above method, each representative point of the plurality of first cooling pipes on a plane approximately perpendicular to the extension direction of the straight body portion is, for example, substantially located on the circumference of one of a plurality of virtual circles arranged approximately concentrically on the approximately perpendicular plane.

[0019] The above method includes, for example, a raw material introduction step of introducing a vinyl monomer, an aqueous medium, and a dispersion aid into a reactor. The above method includes, for example, a polymerization step of polymerizing a vinyl monomer to produce a vinyl polymer. In the above method, the raw material introduction step includes, for example, when the number Nc [pieces] of the multiple imaginary circles is 1, 2, or 3, introducing a dispersion aid so that the number Nc [pieces] of the multiple imaginary circles and the ratio CZ [mg-dispersion aid / kg-monomer] of the mass of the dispersion aid to the mass of the vinyl monomer satisfy the relationship shown in the following mathematical formula A1. (Formula A1) 15Nc+300 <CZ<175Nc+2000

[0020] In the above method, when the number Nc of the multiple virtual circles is 1, 2 or 3, the raw material introduction step may include a step of introducing a dispersion aid so that the number Nc and the ratio CZ satisfy the relationship shown in the following formula B1, C1 or D1. (Formula B1) 15Nc+310 <CZ<175Nc+1550 (Formula C1) 15Nc+400 <CZ<175Nc+1850 (Formula D1) 15Nc+400 <CZ<175Nc+1550

[0021] In the above method, when the number Nc of the multiple virtual circles is 4 or more, the raw material introduction step may include a step of introducing a dispersion aid so that the ratio CZ [mg-dispersion aid / kg-monomer] satisfies the relationship shown in the following mathematical formula A2. (Formula A2) 15×3+300 <CZ<175×3+2000

[0022] The above summary of the invention does not list all of the necessary features of the present invention. Also, subcombinations of these features may also be inventions. [Brief description of the drawings]

[0023] [Figure 1] A schematic cross-sectional view of an example of a polymerization apparatus 100 is shown. [Diagram 2] An example of an internal structure disposed inside the reaction vessel 110 is shown generally. [Diagram 3] A schematic cross-sectional view of an example of a reaction vessel 110 is shown. [Figure 4] A schematic plan view of an example of a reaction vessel 110 is shown. [Diagram 5] An example of the internal structure of the baffle 232 is shown diagrammatically. [Figure 6] An example of the structure of the serpentine cooling pipe 252 is shown diagrammatically. [Figure 7] Another example of the structure of the serpentine cooling tube 252 is shown diagrammatically. [Figure 8]Another example of the structure of the serpentine cooling tube 252 is shown diagrammatically. [Figure 9] An example of the main part of a polymerization apparatus 900 is shown in schematic form. [Figure 10] An example of the main part of a polymerization apparatus 1000 is shown generally. [Figure 11] An example of the main part of a polymerization apparatus 1100 is shown generally. [Figure 12] An example of the main part of the polymerization apparatus 1200 is shown in schematic form. [Figure 13] An example of the main part of a polymerization apparatus 1300 is shown generally. [Figure 14] An example of the main part of a polymerization apparatus 1400 is shown generally. [Figure 15] An example of the main part of a polymerization apparatus 1500 is shown generally. [Figure 16] An example of the main part of a polymerization apparatus 1600 is shown generally. [Figure 17] An example of the main components of a polymerization system 1700 is shown diagrammatically. [Figure 18] An example of the mounting position of the stirring blades on the stirring shaft 122 is shown generally. [Figure 19] An example of the system configuration of a polymerization system 1900 is shown generally. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] The present invention will be described below through embodiments of the invention, but the following embodiments do not limit the invention according to the claims. In addition, not all of the combinations of features described in the embodiments are necessarily essential to the solution of the invention. In this specification, when a numerical range is expressed as "A to B", the expression means A or more and B or less.

[0025] According to this embodiment, in a reaction apparatus including a reactor having a cylindrical straight body, a stirring shaft, and a plurality of stirring blades, an example of a procedure for controlling or determining the rotation speed of the stirring shaft is described. In one embodiment of the procedure for controlling or determining the rotation speed of the stirring shaft, a procedure specific to the case where a plurality of cooling pipes are arranged in a multiple manner in the radial direction of the inscribed circle of the straight body inside the reactor is described.

[0026] According to this embodiment, an example of a procedure for producing a polymer by suspension polymerization using a dispersion aid is described using a reaction apparatus equipped with a reactor having a cylindrical straight body and a stirring shaft equipped with one or more stirring blades. In the example of the procedure for producing a polymer by suspension polymerization using a dispersion aid, a procedure specific to the case where multiple cooling pipes (sometimes called cooling piping) are arranged in multiple in the radial direction of the inscribed circle of the straight body inside the reactor is described.

[0027] First, the structure of the reaction apparatus according to the embodiment will be described with reference to Figs. 1 to 16. Furthermore, the details of the procedure for controlling or determining the rotation speed of the stirring shaft will be described with reference to Fig. 17. Furthermore, an example of the mounting positions of a plurality of stirring blades on the stirring shaft will be described with reference to Fig. 18. Furthermore, an example of the procedure for producing a polymer by suspension polymerization using a dispersion aid will be described with reference to Fig. 19.

[0028] (Overview of Polymerization Apparatus 100) An example of the polymerization apparatus 100 will be described in detail with reference to Figures 1, 2, 3, and 4. The polymerization apparatus 100 is used, for example, for producing a polymer. The polymerization apparatus 100 may be used for suspension polymerization.

[0029] More specifically, the polymerization apparatus 100 is used for producing a vinyl polymer. An example of a method for producing a vinyl polymer is a method having a step of polymerizing a vinyl monomer using the polymerization apparatus 100 to produce a vinyl polymer. The method for producing the vinyl polymer includes, for example, a step of storing a raw material containing a vinyl monomer in a reactor disposed in the polymerization apparatus 100. The method for producing the vinyl polymer includes, for example, a step of initiating a polymerization reaction of the vinyl monomer to produce a vinyl polymer.

[0030] FIG. 1 shows a schematic cross-sectional view of an example of a polymerization apparatus 100. In this embodiment, the polymerization apparatus 100 includes a reaction vessel 110, an agitator 120, one or more (sometimes simply referred to as one or more) baffles 130, one or more serpentine cooling tubes 140, one or more serpentine cooling tubes 150, a jacket 170, and a reflux condenser 180. In this embodiment, the agitator 120 includes a stirring shaft 122, a stirring blade 124, and a power mechanism 126. In this embodiment, the baffle 130 includes a main body 132 and one or more supports 134. In this embodiment, the jacket 170 includes a flow path 172 for a heat medium. In this embodiment, the reflux condenser 180 includes a flow path 182 for a heat medium.

[0031] In this embodiment, the stirring shaft 122 and the stirring blades 124 are disposed inside the reaction vessel 110. In this embodiment, each of the one or more baffles 130 is disposed inside the reaction vessel 110. In this embodiment, each of the one or more serpentine cooling tubes 140 is disposed inside the reaction vessel 110. In this embodiment, each of the one or more serpentine cooling tubes 150 is disposed inside the reaction vessel 110.

[0032] In this embodiment, the power mechanism 126 is disposed outside the reaction vessel 110. In this embodiment, the jacket 170 is disposed outside the reaction vessel 110. In this embodiment, the reflux condenser 180 is disposed outside the reaction vessel 110.

[0033] In this embodiment, the serpentine cooling pipe 140 and the serpentine cooling pipe 150 are arranged so as to have different distances from the inner surface of the reaction vessel 110. Specifically, the serpentine cooling pipe 150 is arranged at a position closer to the side surface of the reaction vessel 110 than the serpentine cooling pipe 140. In this case, the distance P C2 is the distance P between the serpentine cooling tube 150 and the side surface of the reaction vessel 110 C1 Greater than.

[0034] Distance P between the serpentine cooling pipe 140 and the side of the reaction vessel 110 C2 may be the minimum value of the distance between the center of the cross section of the serpentine cooling tube 140 and the side surface of the reaction vessel 110. The distance P C1 may be the minimum distance between the center of the cross section of the serpentine cooling tube 150 and the side surface of the reaction vessel 110. For example, when the serpentine cooling tube 140 or the serpentine cooling tube 150 is a circular tube, the cross section of the serpentine cooling tube 140 or the serpentine cooling tube 150 is a circular tube, and the center of the cross section of the serpentine cooling tube 140 or the serpentine cooling tube 150 is the center of the circle.

[0035] As a result, according to this embodiment, heat inside the reaction vessel 110 can be efficiently removed. For example, when the polymerization apparatus 100 is used for producing a polymer, the polymerization apparatus 100 can efficiently remove reaction heat generated in a polymerization reaction.

[0036] Incidentally, in suspension polymerization of vinyl chloride monomers or monomer mixtures mainly composed of vinyl chloride compounds (both may be collectively referred to as vinyl chloride monomers), when internal structures such as a cooling coil and a draft tube are provided inside the reaction vessel 110, the power required for the agitator 120 increases. In addition, the shape, size and installation position of the internal structures affect the mixing performance of the polymerization apparatus 100. Therefore, depending on the internal structures, slow flow areas may occur inside the reaction vessel 110. If slow flow areas occur inside the reaction vessel 110, the temperature inside the reaction vessel 110 becomes non-uniform. As a result, the particle size and / or degree of polymerization of the produced polymer may become non-uniform, or polymer scale may easily adhere to the inner wall of the reaction vessel 110 or the surface of the internal structure. The scale may cause fish eyes that impair the quality of molded products using the polymer.

[0037] Furthermore, under the same heat removal efficiency conditions, there is a trade-off between increasing the size of the reaction vessel 110 and shortening the reaction time. Therefore, in order to increase the size of the reaction vessel 110 while shortening the reaction time, it is desirable to increase the heat removal efficiency of the polymerization apparatus 100.

[0038] One method for increasing the heat removal efficiency of the polymerization apparatus 100 is to lower the temperature of the coolant. However, lowering the temperature of the coolant increases the production cost of the polymer. Another method for increasing the heat removal efficiency of the polymerization apparatus 100 is to increase the amount of heat removed by the jacket 170 or the reflux condenser 180. In particular, 3 In the case of a large-scale polymerization vessel as described above, the amount of heat removal by the jacket 170 alone is insufficient, so it is considered to greatly increase the amount of heat removal by the reflux condenser 180. However, if the heat removal load of the reflux condenser 180 is increased, the amount of foaming of the polymer slurry inside the reaction vessel 110 may increase. If the amount of foaming of the polymer slurry increases, the heat removal capacity of the reflux condenser 180 may decrease, or polymer scale may adhere to the inside of the reflux condenser 180.

[0039] In addition, for example, when the capacity of the polymerization vessel is increased using the polymerization vessel described in Patent Document 1, if the heat transfer area of ​​the serpentine pipe is insufficient, it may be difficult to shorten the reaction time while maintaining the quality of the product. On the other hand, in the polymerization vessel described in Patent Document 2, the heat transfer area can be increased by a relatively simple structure. However, due to the structure of the vessel, the baffle and the coiled cooling tube cannot be arranged on approximately the same circumference. Therefore, the ratio of the area in which the coiled cooling tube can be installed to the capacity of the vessel is relatively small. When the capacity of the polymerization vessel is increased using the polymerization vessel described in Patent Document 2, if the distance between the coiled cooling tubes is reduced to increase the heat transfer area, the mixing performance of the polymerization vessel may decrease. In addition, if scale or clumped reactants are generated on the surface of the coiled cooling tube due to disturbances, etc., the work inside the vessel becomes complicated, making it difficult to sufficiently remove the scale, etc.

[0040] In contrast, according to the polymerization apparatus 100 of this embodiment, the serpentine cooling pipe 140 and the serpentine cooling pipe 150 are arranged so that the distances from the inner surface of the reaction vessel 110 are different. This allows the heat transfer area to be increased using a relatively simple structure that has little effect on the mixing performance of the polymerization apparatus 100. In addition, according to the polymerization apparatus 100 of this embodiment, the degree of freedom regarding the installation positions of the serpentine cooling pipe 140 and the serpentine cooling pipe 150 is large. For example, at least one of the one or more serpentine cooling pipes 140 and the one or more serpentine cooling pipes 150 and the baffle 130 can be arranged on approximately the same circumference. This allows the heat transfer area of ​​the entire apparatus to be increased while further reducing the effect of the serpentine cooling pipe 150 on the mixing performance of the polymerization apparatus 100.

[0041] (Overview of each part of the polymerization apparatus 100) In this embodiment, the reaction vessel 110 stores raw materials for a synthesis reaction. When the polymerization apparatus 100 is used for producing a polymer, for example, a polymerizable monomer, a polymerization initiator, an aqueous medium, a dispersion aid, and the like are charged into the reaction vessel 110, and then polymerization is initiated. As the dispersion aid, for example, any surfactant can be used.

[0042] The reaction vessel 110 has, for example, a cylindrical shape. The reaction vessel 110 may have a cylindrical shape or a rectangular tubular shape. The reaction vessel 110 is installed, for example, such that the extension direction of the reaction vessel 110 (z direction in the figure) is vertical. The reaction vessel 110 includes, for example, a straight body portion and a mirror portion. In the figure, the total length of the reaction vessel 110 in the extension direction is denoted as H.

[0043] Examples of the shape of a cross section (sometimes referred to as a transverse section) of the reaction vessel 110 cut along a plane (xy plane in the drawing) perpendicular to the extension direction of the reaction vessel 110 include a circle, an ellipse, a polygon, etc. The shape of the transverse section of the reaction vessel 110 may be a shape that can be substantially regarded as a circle, an ellipse, or a polygon.

[0044] The internal volume of the reaction vessel 110 is not particularly limited, but the internal volume of the reaction vessel 110 is, for example, 1 to 300 ml. 3 The lower limit of the internal volume of the reaction vessel 110 is 40 ml. 3 It may be 80m 3 may be 100m 3 It may be 120m 3 It may be 130m 3 It may be 150m 3 It may be 200m 3 It may be 250m 3 The upper limit of the internal volume of the reaction vessel 110 may be 300 ml. 3 The upper limit of the internal volume of the reaction vessel 110 is 350 ml. 3 It may be 400m 3 The larger the internal volume of the reaction vessel 110, the more advantageous the improvement in cooling capacity according to this embodiment.

[0045] The internal capacity of the reaction vessel 110 is determined as the capacity when the reaction vessel 110 stores liquid up to a predetermined upper limit position of the reaction vessel 110. The internal capacity of the reaction vessel 110 is, for example, the internal volume of the reaction vessel 110 when no internal structure such as a stirring shaft, blades, baffles, coils, etc. is disposed inside the reaction vessel 110.

[0046] As described above, there is a trade-off between increasing the size of the reaction vessel 110 and shortening the reaction time. 3 If the internal volume of the reaction vessel 110 is more than 80 m, the heat removal efficiency of the polymerization apparatus 100 becomes insufficient, and it becomes difficult to shorten the reaction time while increasing the size of the reaction vessel 110. 3 In the above cases, the effects of the polymerization apparatus 100 according to this embodiment are more pronounced. The details of the reaction vessel 110 will be described later.

[0047] In this embodiment, the agitator 120 agitates the liquid stored inside the reaction vessel 110. In this embodiment, the agitator shaft 122 holds the agitator blade 124 and rotates the agitator blade 124. In this embodiment, the agitator blade 124 is attached to the agitator shaft 122 and agitates the liquid stored inside the reaction vessel 110.

[0048] The shape of the agitating blade 124 is not particularly limited, but examples of the shape of the agitating blade 124 include Pfaudle blades, blue margin blades, paddle blades, inclined paddle blades, turbine blades, propeller blades, and combinations thereof. As a result, when the agitating shaft 122 rotates, a discharge flow is generated that radially moves from the agitating shaft 122 toward the outer periphery. The number of blades that the agitating blade 124 has is not particularly limited, but examples of the number of blades are 2 to 6. The installation position and the installation number of the agitating blades 124 are not particularly limited, but it is preferable that the agitating blades 124 are installed in multiple stages. Examples of the number of stages of the agitating blades 124 are 2 to 6 stages.

[0049] In this embodiment, the power mechanism 126 rotates the agitation shaft 122. The power mechanism 126 includes, for example, a power unit (not shown) that generates power, and a power transmission unit (not shown) that transmits the power generated by the power unit to the agitation shaft 122. An example of the power unit is an electric motor. An example of the power transmission unit is a reducer.

[0050] The rotation speed of the stirring shaft 122, and the shape, size, number of blades, installation position, installation quantity and installation interval C of the stirring blades 124 i is appropriately determined depending on the application of the polymerization apparatus 100. The rotation speed of the stirring shaft 122, the shape, size, number of blades, installation position, installation quantity and installation interval C of the stirring blades 124 i is determined taking into consideration, for example, the internal volume of the reaction vessel 110, the shape of the reaction vessel 110, the internal structure disposed inside the reaction vessel 110, the configuration of the heat removal means, the heat removal capacity, and the composition of the raw materials charged for polymerization.

[0051] For example, when the polymerization apparatus 100 is used for suspension polymerization, the stirring energy applied to the contents (in this case, an aqueous suspension mixture) is 80 to 200 kgf m / s m 3 The rotation speed of the agitator shaft 122 is determined so that the agitation energy is equal to or greater than the energy A applied to the agitator drive motor disposed in the power mechanism 126 during operation of the polymerization apparatus 100. The "agitation energy" applied to the contents is defined as the net energy required for agitation per unit amount of contents (sometimes referred to as unit content amount), calculated by subtracting various energy losses B, such as motor efficiency and conduction loss and mechanical loss, from the energy A applied to the agitator drive motor disposed in the power mechanism 126 during operation of the polymerization apparatus 100. Examples of the unit amount include unit mass and unit volume. For example, when the volume of the contents is C, the agitation energy is calculated by the following formula E. (Formula E) (AB) / C [kgf m / s m 3 ]

[0052] The energy applied to the drive motor for the agitator can be electrically measured using a measuring device such as a wattmeter. The agitation energy can be easily adjusted by changing the rotation speed of the agitator shaft 122.

[0053] The rotation speed of the agitator shaft 122 is set to, for example, 10 to 1000 [rpm]. The above set value can be suitably adopted, for example, when the polymerization apparatus 100 is used for suspension polymerization. Examples of a method for determining the rotation speed of the agitator shaft 122 so that the agitation energy falls within the above numerical range include (i) a method using a scale-up test, and (ii) a method using a relational formula such as an experimental formula or an empirical formula.

[0054] In one embodiment, the rotation speed of the stirring shaft 122 in the polymerization apparatus 100 is determined based on, for example, a polymerization test previously performed in a pilot plant. In general, the scale-up from the pilot plant to the polymerization apparatus 100 is performed so that the stirring state of the polymerization apparatus 100 is approximately the same as that of the pilot plant. For example, in the pilot plant and the polymerization apparatus 100, the shape, size and arrangement of each internal structure are determined so that the shape and size of the reaction vessel 110 are similar to the shape, size and arrangement of the internal structures such as the stirring blade 124, the baffle 130, the serpentine cooling tube 140 and the serpentine cooling tube 150.

[0055] Therefore, according to one embodiment, the rotation speed of the stirring shaft 122 in the polymerization apparatus 100 can be determined so that the stirring energy in the polymerization apparatus 100 and the stirring energy in the pilot plant are substantially the same. As described above, the stirring energy is calculated as, for example, "(AB) / C". As a method for determining the rotation speed of the stirring shaft 122 based on the stirring energy, any known method can be adopted.

[0056] The rotation speed of the stirring shaft 122 in the pilot plant is determined, for example, by the following procedure. For example, a relationship between the rotation speed of the stirring shaft 122 in the pilot plant and the quality of the polymer is obtained by a polymerization test using the pilot plant. This determines the rotation speed of the stirring shaft 122 that will produce a polymer of the desired quality. The above quality is not particularly limited, and an example of the above quality is the particle size.

[0057] Specifically, in a polymerization test using a pilot plant, the polymerization temperature is set according to the reduced viscosity (sometimes referred to as K value) of the target polymer. Here, there is a correlation between the polymerization temperature and the average degree of polymerization of the polymer, and the K value of the polymer is widely used as an index representing the average degree of polymerization of the polymer.

[0058] In addition, in a polymerization test using a pilot plant, the polymerization time is determined according to the heat removal capacity of the pilot plant. For example, the polymerization time is determined according to (i) the amount of monomers charged as starting materials, (ii) the amount of polymerization initiator charged, and (iii) the heat removal capacity of the pilot plant, so that the amount of heat generated by the reaction does not exceed the heat removal capacity of the pilot plant.

[0059] In this way, when the polymerization time is set so that the pilot plant has sufficient heat removal capacity, a polymer having a target average degree of polymerization can be produced by setting the polymerization temperature according to the target value of the K value. Thus, for example, polymerization tests are carried out under a plurality of conditions in which the polymerization temperature and polymerization time are the same, but the rotation speed of the stirring shaft 122 is different.

[0060] The relationship between the rotation speed of the agitator shaft 122 in the pilot plant and the quality of the polymer is obtained based on the results of a plurality of tests with different rotation speeds of the agitator shaft 122. If the target value of the polymer quality is determined in this way, the rotation speed of the agitator shaft 122 that will produce a polymer of the desired quality can be determined.

[0061] When the polymerization time is set so that the pilot plant has sufficient heat removal capacity, a polymer having a desired average degree of polymerization can be produced by setting the polymerization temperature according to the target value of the K value. On the other hand, when the heat removal capacity of the pilot plant is insufficient for the set polymerization time, the polymerization temperature rises due to heat generated by the polymerization reaction. As described above, there is a correlation between the polymerization temperature and the average degree of polymerization of the produced polymer. Therefore, when the polymerization temperature rises, the error between the K value of the produced polymer and the target value of the K value increases. In addition, depending on the degree of rise in the polymerization temperature, it may become impossible to control the reaction.

[0062] In this way, the K value of the produced polymer can be used as an index regarding the heat removal capacity of the polymerization apparatus 100. For example, in the case where a polymer is produced using the polymerization apparatus 100, when a target K value is obtained for a set polymerization time, it can be determined that the polymerization apparatus 100 has sufficient heat removal capacity.

[0063] As described above, the scale-up from the pilot plant to the polymerization apparatus 100 can be performed so that the stirring state of the polymerization apparatus 100 and the stirring state of the pilot plant are approximately the same. For example, when the ratio of the size of each internal structure disposed inside the reaction vessel 110 to the inner diameter and / or the straight body height of the reaction vessel 110 in the target polymerization apparatus 100 is approximately the same as the ratio of the size of each internal structure in the pilot plant to the inner diameter and / or the straight body height of the reaction vessel in the pilot plant, and when the stirring energy in the polymerization apparatus 100 and the stirring energy in the pilot plant are approximately the same, the stirring state of the scaled-up polymerization apparatus 100 is approximately the same as the stirring state of the pilot plant.

[0064] For example, the size of the baffle 130 in the target polymerization apparatus 100 is determined so that the ratio of the length of the baffle 130 in the extension direction (vertical direction in the figure) to the height of the straight body of the reaction vessel 110 is approximately the same between the pilot plant and the target polymerization apparatus 100. The size of the baffle 130 in the target polymerization apparatus 100 is determined so that the ratio of the length of the baffle 130 in the direction approximately perpendicular to the extension direction (horizontal direction in the figure) to the inner diameter (sometimes referred to as the inner diameter) of the reaction vessel 110 is approximately the same between the pilot plant and the target polymerization apparatus 100. The number and arrangement of the baffles 130 in the target polymerization apparatus 100 are determined so that the number and arrangement of the baffles 130 are approximately the same between the pilot plant and the target polymerization apparatus 100. The same applies to other structures (for example, the stirring blades 124, the serpentine cooling pipes 140, the serpentine cooling pipes 150, etc.).

[0065] Furthermore, as described above, once the target value of the polymer quality in the scaled-up polymerization apparatus 100 is determined, the rotation speed of the agitator shaft 122 in the scaled-up polymerization apparatus 100 can be determined based on the relationship between the rotation speed of the agitator shaft 122 in the pilot plant and the polymer quality described above. Specifically, first, the rotation speed of the agitator shaft 122 in the pilot plant is determined based on (i) the target value of the polymer quality in the polymerization apparatus 100, and (ii) the relationship between the rotation speed of the agitator shaft 122 in the pilot plant and the polymer quality. Next, the rotation speed of the agitator shaft 122 in the polymerization apparatus 100 is determined so that the agitation energy in the polymerization apparatus 100 and the agitation energy in the pilot plant are approximately the same.

[0066] As a result, the shape, size, number of blades, installation position, installation quantity and installation interval C of (i) the stirring blade 124 of the target polymerization apparatus 100 i , and (ii) the mixing energy per unit capacity [kgf m / s m], taking into consideration the capacity of the reaction vessel 110, the shape of the reaction vessel 110, and the internal structure disposed inside the reaction vessel 110, 3The rotation speed of the stirring shaft 122 in the polymerization apparatus 100 may be determined without strictly measuring the rotation speed of the stirring shaft 122 in the polymerization apparatus 100. The rotation speed of the stirring shaft 122 in the polymerization apparatus 100 may be determined based on the results of a simulation of a polymerization test.

[0067] In another embodiment, the rotation speed of the stirring shaft 122 in the polymerization apparatus 100 is determined so that the dimensions of the straight body portion of the reaction vessel 110, the dimensions of at least one of the multiple stirring blades 124, and the set value of the rotation speed of the stirring shaft 122 satisfy the relationship shown in the following mathematical formula 1. (Formula 1) N(b / d)(L / D) / n≦6.0

[0068] In the formula 1, N indicates the number of the plurality of stirring blades 124. b indicates the maximum blade width [m] of the plurality of stirring blades 124. d indicates the maximum blade diameter [m] of the plurality of stirring blades 124. L indicates the length [m] of the straight body portion of the reaction vessel 110 in the extension direction. D indicates the maximum diameter [m] of the plurality of inscribed circles that are approximately inscribed in the straight body portion in each of the cross sections of the plurality of planes when the straight body portion is cut along a plurality of planes that are approximately perpendicular to the extension direction of the straight body portion and pass through the respective mounting positions of the plurality of stirring blades 124. When the reaction vessel 110 has a cylindrical straight body portion, D is the inner diameter [m] of the straight body portion. n indicates the set value of the rotation speed [rps] of the stirring shaft 122.

[0069] The blade diameter of the agitating blade 124 may be the rotation diameter of the agitating blade 124. The rotation diameter of the agitating blade 124 may be the diameter of a rotor obtained by rotating the agitating blade 124 around the agitating shaft 122. The blade diameter of the agitating blade 124 may be the overall length of the agitating blade 124 in a direction approximately perpendicular to the extension direction of the agitating shaft 122 (for example, the left-right direction in FIG. 1) when the agitating blade 124 is attached to the agitating shaft 122.

[0070] The blade width of the agitating blade 124 may be the height of a rotor obtained by rotating the agitating blade 124 around the agitating shaft 122. The blade width of the agitating blade 124 may be the total length of the agitating blade 124 in a direction approximately parallel to the extension direction of the agitating shaft 122 (for example, the vertical direction in FIG. 1) when the agitating blade 124 is attached to the agitating shaft 122.

[0071] According to this embodiment, the rotation speed of the agitator shaft 122 can be easily determined, as compared with the case where the rotation speed of the agitator shaft 122 is determined based on a polymerization test carried out in advance at a pilot plant. Even when the rotation speed of the agitator shaft 122 is determined based on a polymerization test carried out in advance at a pilot plant, the rotation speed of the agitator shaft 122 can be easily determined by considering the relationship of the above-mentioned formula 1.

[0072] It is preferable that the dimensions of the straight body of the reaction vessel 110, the dimensions of at least one of the multiple stirring blades 124, and the set value of the rotation speed of the stirring shaft 122 be determined so as to satisfy the relationship shown in the following formula 2. (Formula 2) 0.05≦N(b / d)(L / D) / n≦6.0

[0073] When the polymerization apparatus 100 is equipped with one or more serpentine cooling pipes 140 or one or more serpentine cooling pipes 150, it is preferable that the dimensions of the straight body of the reaction vessel 110, the dimensions of at least one of the multiple stirring blades 124, and the set value of the rotation speed of the stirring shaft 122 are determined so as to satisfy the relationship shown in the following mathematical formula 3. (Formula 3) 0.15≦N(b / d)(L / D) / n≦5.5

[0074] When the polymerization apparatus 100 is equipped with one or more serpentine cooling pipes 140 and one or more serpentine cooling pipes 150, it is preferable that the dimensions of the straight body of the reaction vessel 110, the dimensions of at least one of the multiple stirring blades 124, and the set value of the rotation speed of the stirring shaft 122 are determined so as to satisfy the relationship shown in the following mathematical formula 4. (Formula 4) 0.3≦N(b / d)(L / D) / n≦5.5

[0075] In one embodiment, the set value of the rotation speed of the stirring shaft 122 in the polymerization apparatus 100 is determined based on the dimension of the straight body part of the reaction vessel 110, the dimension of at least one of the plurality of stirring blades 124, and Formula 1. In another embodiment, the dimension of the straight body part of the reaction vessel 110 and the dimension of at least one of the plurality of stirring blades 124 are determined based on the set value of the rotation speed of the stirring shaft 122 in the polymerization apparatus 100 and Formula 1. Details of these embodiments will be described in relation to FIG. 17 described later.

[0076] In this embodiment, the baffle 130 improves the mixing performance of the polymerization apparatus 100. For example, the baffle 130 improves the mixing performance in the vertical direction inside the reaction vessel 110. The installation position of the baffle 130 is not particularly limited, but for example, the baffle 130 is disposed near the inner wall of the reaction vessel 110. The baffle 130 may be supported by the side wall of the reaction vessel 110. In another embodiment, the baffle 130 is supported by the top plate or bottom plate of the reaction vessel 110 and disposed near the stirring blade 124. When the polymerization apparatus 100 is used for the production of a polymer, the baffle 130 may be disposed so that the upper end of the baffle 130 is submerged in the liquid phase, or may be disposed so that the upper end of the baffle 130 is not submerged in the liquid phase.

[0077] The number of baffles 130 is preferably about 1 to 12, more preferably about 2 to 8, more preferably about 3 to 6, and even more preferably about 4 to 6. An even number of baffles 130 are preferably arranged approximately symmetrically around the extension axis (sometimes referred to as the central axis) of the reaction vessel 110. This further improves the mixing performance of the polymerization apparatus 100 and suppresses liquid retention. As a result, the generation of scale can be suppressed.

[0078] In this embodiment, the main body 132 of the baffle 130 improves the mixing performance of the polymerization apparatus 100. The shape of the main body 132 is not particularly limited, but the main body 132 has, for example, a plate-like or cylindrical shape extending approximately parallel to the extension direction of the reaction vessel 110. When the main body 132 has a cylindrical shape, the diameter of the main body 132 may be 40 to 500 mm. The length Bh (sometimes referred to as height Bh) of the main body 132 in the extension direction (z direction in the figure) is not particularly limited.

[0079] The length Bw (sometimes referred to as width Bw) in a direction (x or y direction in the drawing) approximately perpendicular to the stretching direction of the main body 132 is not particularly limited. The ratio of the width Bw of the main body 132 to the inner diameter of the reaction vessel 110 may be 1 to 10%, 2.5 to 7.5%, or 3 to 7%.

[0080] When the main body 132 has a cylindrical shape, the ratio of the total value of the cross-sectional area of ​​one or more main bodies 132 each having a cylindrical shape to the cross-sectional area of ​​the straight body part of the reaction vessel 110 may be 0.4 to 3%. When the above ratio is less than 0.4%, the function as a baffle is insufficient, and vertical mixing inside the reaction vessel 110 may be insufficient. For example, when the polymerization apparatus 100 has a single baffle 130, the above ratio may be less than 0.4%. For example, in the suspension polymerization of vinyl chloride monomers, when vertical mixing inside the reaction vessel 110 becomes insufficient, the particle size distribution of the produced polymer may become broad. As a result, when the produced polymer is molded into a sheet, for example, fish eyes may increase, and the quality of the molded product may be reduced.

[0081] On the other hand, if the above ratio exceeds 3%, the power required for the agitator 120 increases excessively. Also, the fluidity of the liquid between the baffle 130 and the inner wall surface of the reaction vessel 110 may decrease. As a result, scale may easily adhere to the reaction vessel 110 or the internal structure of the reaction vessel 110. For example, if the polymerization apparatus 100 includes more than eight baffles 130, the above ratio may exceed 3% depending on the design of the polymerization apparatus 100.

[0082] The body 132 of at least one baffle 130 may have a flow path for circulating the heat transfer medium. The flow path may be formed inside the body 132, or may be disposed outside the body 132. The flow path may be a single pipe or may have a double pipe structure.

[0083] The heat medium may be a known refrigerant. Examples of the refrigerant include water, brine, freon, and other liquefied gases. When a liquefied gas is used as the refrigerant, the liquefied gas may function as the refrigerant by evaporating inside the serpentine cooling pipe 140. The linear velocity of the refrigerant may be about 0.1 to 6.0 m / s.

[0084] The main body 132 is connected to the inner wall surface of the reaction vessel 110, for example, via a support 134. The distance between the main body 132 and the inner wall surface of the polymerization apparatus 100 is preferably 40 mm or more. If the distance is less than 40 mm, polymer scale may easily adhere between the inner wall surface of the reaction vessel 110 and the baffle 130 near the gas-liquid interface inside the reaction vessel 110. Details of the main body 132 will be described later.

[0085] In this embodiment, the support 134 holds the main body 132. For example, one end of the support 134 contacts the inner wall surface of the reaction vessel 110, and the other end of the support 134 contacts the main body 132. As described above, the support 134 may hold the main body 132 such that the distance between the main body 132 and the inner wall surface of the polymerization apparatus 100 is 40 mm or more.

[0086] (Serpentine cooling pipe 140) In this embodiment, the serpentine cooling pipe 140 has a flow path formed therein for circulating a heat medium. The serpentine cooling pipe 140 may be a single pipe. The serpentine cooling pipe 140 is disposed closer to the central axis of the reaction vessel 110 than the serpentine cooling pipe 150. The number of the serpentine cooling pipes 140 is preferably about 1 to 12, more preferably about 2 to 8, more preferably about 3 to 6, and further preferably about 4 to 6. An even number of the serpentine cooling pipes 140 are preferably disposed approximately symmetrically around the central axis of the reaction vessel 110.

[0087] The heat medium may be a known refrigerant. Examples of the refrigerant include water, brine, freon, and other liquefied gases. When a liquefied gas is used as the refrigerant, the liquefied gas may function as the refrigerant by evaporating inside the serpentine cooling pipe 140. The linear velocity of the refrigerant may be about 0.1 to 6.0 m / s.

[0088] In this embodiment, at least a part of the serpentine cooling pipe 140 extends while repeatedly bending. The length Ph of the part of the serpentine cooling pipe 140 that extends while repeatedly bending may be smaller than, substantially equal to, or larger than the length Bh of the body 132 of the baffle 130 in the extension direction (z direction in the figure). This increases the heat transfer area per installation area.

[0089] 1, the serpentine cooling pipe 140 extends substantially parallel to the extension direction of the reaction vessel 110 while repeatedly bending. In the example shown in Fig. 1, the entire serpentine cooling pipe 140 extends while repeatedly bending. The ratio of the length Ph of the portion of the serpentine cooling pipe 140 that extends while repeatedly bending to the total length Pt (not shown) of the serpentine cooling pipe 140 in the extension direction may be 0.25 or more, 0.5 or more, 0.75 or more, 0.8 or more, or 0.9 or more.

[0090] When the polymerization apparatus 100 is used for producing a polymer, the serpentine cooling pipe 140 may be arranged so that the upper end of the serpentine cooling pipe 140 is submerged in the liquid phase. If the upper part of the serpentine cooling pipe 140 is exposed to the gas phase, the heat transfer efficiency decreases and polymer scales are likely to adhere to the serpentine cooling pipe 140. At the end of the polymerization, the gas-liquid interface decreases due to liquid contraction. Therefore, it is preferable that the serpentine cooling pipe 140 is arranged at a position where there is a sufficient distance between the upper end of the serpentine cooling pipe 140 and the gas-liquid interface even at the end of the polymerization. Details of the serpentine cooling pipe 140 will be described later.

[0091] (150 serpentine cooling pipes) In this embodiment, the serpentine cooling pipe 150 has a flow path formed therein for circulating a heat medium. The serpentine cooling pipe 150 may be a single pipe. The serpentine cooling pipe 150 is disposed closer to the side wall of the reaction vessel 110 than the serpentine cooling pipe 140. The number of the serpentine cooling pipes 150 is preferably about 1 to 12, more preferably about 2 to 8, more preferably about 3 to 6, and even more preferably about 4 to 6. The number of the serpentine cooling pipes 150 may be the same as or different from the number of the serpentine cooling pipes 140. An even number of the serpentine cooling pipes 150 are preferably disposed approximately symmetrically around the central axis of the reaction vessel 110.

[0092] The heat medium may be a known refrigerant. Examples of the refrigerant include water, brine, freon, and other liquefied gases. When a liquefied gas is used as the refrigerant, the liquefied gas may function as the refrigerant by evaporating inside the serpentine cooling pipe 140. The linear velocity of the refrigerant may be about 0.1 to 6.0 m / s.

[0093] In this embodiment, at least a part of the serpentine cooling pipe 150 extends while repeatedly bending. The length Ph of the part of the serpentine cooling pipe 150 that extends while repeatedly bending may be smaller than, substantially equal to, or larger than the length Bh of the body 132 of the baffle 130 in the extension direction (z direction in the figure). This increases the heat transfer area per installation area.

[0094] 1, the serpentine cooling pipe 150 extends substantially parallel to the extension direction of the reaction vessel 110 while repeatedly bending. In the example shown in Fig. 1, the entire serpentine cooling pipe 150 extends while repeatedly bending. The ratio of the length Ph of the portion of the serpentine cooling pipe 150 that extends while repeatedly bending to the total length Pt (not shown) of the serpentine cooling pipe 150 in the extension direction may be 0.25 or more, 0.5 or more, 0.75 or more, 0.8 or more, or 0.9 or more.

[0095] When the polymerization apparatus 100 is used for producing a polymer, the serpentine cooling pipe 150 may be disposed so that the upper end of the serpentine cooling pipe 150 is submerged in the liquid phase. If the upper part of the serpentine cooling pipe 150 is exposed to the gas phase, the heat transfer efficiency decreases and polymer scales are likely to adhere to the serpentine cooling pipe 150. At the end of the polymerization, the gas-liquid interface decreases due to liquid contraction. Therefore, it is preferable that the serpentine cooling pipe 150 is disposed at a position where there is a sufficient distance between the upper end of the serpentine cooling pipe 150 and the gas-liquid interface even at the end of the polymerization.

[0096] In one embodiment, the flow direction of the coolant in the serpentine cooling pipe 150 is set so that the coolant flows from below the reaction vessel 110 toward above the reaction vessel 110. In another embodiment, the flow direction of the coolant in the serpentine cooling pipe 150 is set so that the coolant flows from above the reaction vessel 110 toward below the reaction vessel 110.

[0097] For example, the liquid returned from the reflux condenser 180 has a lower temperature and a higher density than the liquid inside the reaction vessel 110. Therefore, in the vicinity of the inlet for the liquid returned from the reflux condenser 180, the liquid inside the reaction vessel 110 tends to flow from the top to the bottom. Therefore, for example, the serpentine cooling pipe 150 disposed in the vicinity of the inlet for the liquid returned from the reflux condenser 180 can be configured so that the refrigerant flows from the bottom of the reaction vessel 110 to the top of the reaction vessel 110. The details of the serpentine cooling pipe 150 will be described later.

[0098] (Plane arrangement of the serpentine cooling pipes 140 and 150) As described above, in this embodiment, the serpentine cooling pipes 140 and 150 are arranged in multiple stages in the diameter direction of the straight body part 312 of the reaction vessel 110. According to this embodiment, in a plane (xy plane in the figure) approximately perpendicular to the extension direction of the straight body part of the reaction vessel 110 (z direction in the figure as described above), each representative point of one or more serpentine cooling pipes 140 and one or more serpentine cooling pipes 150 is located on any one of the circumferences of multiple virtual circles arranged approximately concentrically in the xy plane. The multiple virtual circles will be described in detail later.

[0099] The representative point of each of the one or more serpentine cooling pipes 140 may be any point on the center line of each pipe. When the serpentine cooling pipe 140 includes (i) a plurality of extension parts that extend linearly or curvedly, and (ii) a plurality of bent parts that connect the ends of two adjacent extension parts among the plurality of extension parts, the representative point of the serpentine cooling pipe 140 may be any point on the center line of the extension part. When the above xy plane does not pass through the center of the extension part, the representative point of the serpentine cooling pipe 140 may be any point on the center line of the above extension part projected onto the xy plane.

[0100] The representative point of each of the one or more serpentine cooling pipes 150 may be any point on the center line of each pipe. When the serpentine cooling pipe 150 includes (i) a plurality of extension parts that extend linearly or curvedly, and (ii) a plurality of bent parts that connect the ends of two adjacent extension parts among the plurality of extension parts, the representative point of the serpentine cooling pipe 150 may be any point on the center line of the extension part. When the above xy plane does not pass through the center of the extension part, the representative point of the serpentine cooling pipe 150 may be any point on the center line of the above extension part projected onto the xy plane.

[0101] In this embodiment, the jacket 170 heats or cools the reaction vessel 110 from outside the reaction vessel 110. As described above, the jacket 170 has the flow path 172 configured to allow a heat medium to flow. The jacket 170 adjusts the amount of heat to be applied to and the amount of heat to be removed from the reaction vessel 110 by controlling at least one of the temperature and the flow rate of the heat medium flowing through the flow path 172.

[0102] The heat medium may be a known refrigerant. Examples of the refrigerant include water, brine, Freon, and various liquefied gases. A liquid refrigerant is preferably used as the refrigerant. When a liquefied gas is used as the refrigerant, the liquefied gas may function as the refrigerant by evaporating inside the serpentine cooling pipe 140. The linear velocity of the refrigerant may be about 0.1 to 6.0 m / s.

[0103] In this embodiment, the reflux condenser 180 is used to remove heat from the reaction vessel 110. For example, steam from the reaction vessel 110 is supplied to the reflux condenser 180. The reflux condenser 180 cools and liquefies the steam. The reflux condenser 180 returns the liquid generated by the cooling to the reaction vessel 110. As described above, the reflux condenser 180 has a flow path 182 configured to allow a heat medium to flow. The reflux condenser 180 cools the steam from the reaction vessel 110 by heat exchange between the heat medium flowing through the flow path 182 and the steam from the reaction vessel 110. The amount of heat removed from the reaction vessel 110 can be adjusted by controlling at least one of the temperature and flow rate of the heat medium flowing through the flow path 182.

[0104] (Heat removal methods) As described above, in this embodiment, the reaction vessel 110 has the baffle 130, the serpentine cooling tube 140, the serpentine cooling tube 150, the jacket 170, and the reflux condenser 180 as heat removal means. The ratio of the amount of heat removed by each heat removal device to the total amount of heat generated is not particularly limited. The above ratio is determined, for example, in consideration of the quality of the polymer produced, the manufacturing cost, etc. For example, the ratio of the amount of heat removed by the baffle 130 to the total amount of heat generated is preferably 10 to 30%. The ratio of the total amount of heat removed by the serpentine cooling tube 140 and the serpentine cooling tube 150 to the total amount of heat generated is preferably 10 to 50%. The ratio of the amount of heat removed by the jacket 170 to the total amount of heat generated is preferably 20 to 40%. The ratio of the amount of heat removed by the reflux condenser 180 to the total amount of heat generated is preferably 10 to 50%.

[0105] In addition, the serpentine cooling pipes 140 and 150 have a ratio of the total surface area of ​​the serpentine cooling pipes 140 and 150 to the internal volume of the reaction vessel 110 of 0.1 to 0.9 [m 2 / m 3 The ratio is preferably designed to be 0.5 to 0.7 [m 2 / m 3 This makes it possible to set the ratio of the sum of the heat removal amounts of the serpentine cooling pipes 140 and 150 to the total heat generation amount to 10 to 50%.

[0106] (Materials of Each Part of Polymerization Apparatus 100) The material of each part of the polymerization apparatus 100 is appropriately determined in consideration of mechanical strength, corrosion resistance, heat transfer, and the like. For example, the material used for the stirring shaft 122, the stirring blade 124, the baffle 130, the serpentine cooling tube 140, and the serpentine cooling tube 150 is preferably stainless steel such as high chromium high purity ferritic stainless steel, two-phase stainless steel, and austenitic stainless steel. These materials have excellent heat transfer and corrosion resistance. In addition, the material of the inner wall surface of the reaction vessel 110 is exemplified by clad steel containing stainless steel. The material of the outer layer of the clad steel is preferably carbon steel, and the material of the inner layer of the clad steel is preferably stainless steel.

[0107] (Use of the polymerization apparatus 100) As described above, the polymerization apparatus 100 is used for producing a polymer. The polymerization method may be suspension polymerization or emulsion polymerization. More specifically, the polymerization apparatus 100 is used for polymerizing various vinyl monomers, for example, olefins such as ethylene and propylene, vinyl halides such as vinyl chloride and vinylidene chloride, vinyl esters such as vinyl acetate, vinyl ethers such as ethyl vinyl ether, (meth)acrylic acid esters such as methyl methacrylate, metal salts or esters of maleic acid or fumaric acid, aromatic vinyls such as styrene, diene monomers such as butadiene, chloroprene, and isoprene, acrylonitrile, and the like to produce a polymer. The polymerization apparatus 100 is particularly suitable for use in polymerizing vinyl chloride or a monomer mixture mainly composed of vinyl chloride to produce a polymer.

[0108] When a polymer is produced using the polymerization apparatus 100, each raw material is supplied from a supply port (not shown) of the polymerization apparatus, and when the temperature of the reaction compound charged inside the reaction vessel 110 reaches a predetermined temperature, heat removal from the reaction compound is started by circulating a coolant through each of the baffle 130, the serpentine cooling tube 140, the serpentine cooling tube 150, and the jacket 170. On the other hand, the timing to start removing heat by the reflux condenser 180 is preferably after the polymerization conversion rate reaches 4%, and more preferably when the polymerization conversion rate is 4 to 20%.

[0109] Even when a polymer is produced using the polymerization apparatus 100, various polymerization conditions may be similar to known polymerization conditions. Examples of the polymerization conditions include the charging ratio of raw materials, the charging method of raw materials, and the polymerization temperature.

[0110] For example, when a vinyl chloride polymer is produced by suspension polymerization using the polymerization apparatus 100, the aqueous medium, the vinyl chloride monomer, possibly other comonomers, a dispersing aid (sometimes simply referred to as a dispersing agent), a polymerization initiator, and the like are charged in the same manner as in known methods for producing vinyl chloride polymers. The polymerization conditions may also be the same as in known methods for producing vinyl chloride polymers. The vinyl chloride monomer and / or the other comonomers may be an example of one or more types of monomers that serve as raw materials for the polymer.

[0111] (monomer) As the monomer to be polymerized, vinyl chloride alone or a monomer mixture mainly composed of vinyl chloride (vinyl chloride 50% by mass or more) can be used. Examples of the comonomer to be copolymerized with vinyl chloride include vinyl esters such as vinyl acetate and vinyl propionate; acrylic acid esters or methacrylic acid esters such as methyl acrylate and ethyl acrylate; olefins such as ethylene and propylene; maleic anhydride; acrylonitrile; styrene; vinylidene chloride; and other monomers copolymerizable with vinyl chloride. Vinyl chloride, a monomer mixture mainly composed of vinyl chloride, and a comonomer to be copolymerized with vinyl chloride may be examples of one or more types of monomers that serve as raw materials for a polymer.

[0112] (Dispersion aid) The above-mentioned dispersion aid is a compound that is usually used in the polymerization of vinyl chloride in an aqueous medium. Examples of the above-mentioned dispersion aid include water-soluble cellulose ethers such as methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, and hydroxypropylmethyl cellulose (HPMC); water-soluble polymers such as partially saponified polyvinyl alcohol (PVA), acrylic acid polymers, and gelatin. The above-mentioned dispersion aids may be used alone or in combination of two or more.

[0113] For example, the saponification degree of the partially saponified polyvinyl alcohol may be 20 to 90 mol%. The saponification degree of the partially saponified polyvinyl alcohol may be 40 to 90 mol%, or 50 to 90 mol%. Examples of the saponification degree of the partially saponified polyvinyl alcohol include 25 mol%, 40 mol%, 48 mol%, 55 mol%, 72 mol%, 78 mol%, 80 mol%, and 88 mol%. A plurality of types of partially saponified polyvinyl alcohols having different saponification degrees may be used as a dispersing agent. The partially saponified polyvinyl alcohol may be modified.

[0114] Dispersing agents can be classified into primary dispersing agents for adjusting the particle size of the polymer and secondary dispersing agents for adjusting the porosity of the polymer. Primary dispersing agents include partially saponified PVA and HPMC. Secondary dispersing agents include partially saponified PVA and HPMC.

[0115] In one embodiment, the dispersion aid is added in an amount of, for example, 0.01 to 5 parts by mass per 100 parts by mass of the monomer to be charged. In another embodiment, the amount of the dispersion aid added (sometimes referred to as the input amount) is adjusted depending on the state of the internal structure placed inside the reaction vessel 110.

[0116] For example, the amount of dispersion aid added is adjusted according to the degree of radial multiplexing of the cooling pipes arranged inside the reaction vessel 110. As described above, in the embodiment described in relation to FIG. 1, the representative points of each of the one or more serpentine cooling pipes 140 and the one or more serpentine cooling pipes 150 are substantially located on any one of the circumferences of a plurality of imaginary circles (sometimes referred to as imaginary circles) arranged substantially concentrically in the xy plane. The representative points may be located at positions slightly away from the circumferences of the cooling pipes, for example, due to manufacturing or design errors, to the extent that the function of each cooling pipe is not impaired. The number N of the plurality of imaginary circles may be used as an index indicating the degree of radial multiplexing of the cooling pipes or the state of the internal structure.

[0117] For example, when the number N of the multiple virtual circles is 1, 2, or 3, the number Nc of the virtual circles and the ratio CZ of the mass of the dispersion aid to the mass of the monomer charged in the reaction vessel 110 (mg-dispersion aid / kg-monomer) satisfy the relationship shown in the following formula A1. For example, the amount of dispersion aid added is adjusted so as to satisfy the relationship shown in the following formula A1. (Formula A1) 15Nc+300 <CZ<175Nc+2000

[0118] When multiple types of monomers are charged into the reaction vessel 110 as raw materials for the polymer, the mass of the monomers charged into the reaction vessel 110 may be the sum of the masses of the multiple types of monomers. As described above, the amount of dispersion aid added is adjusted according to the state of the internal structure, thereby improving the stability of the liquid in the reaction vessel (sometimes referred to as a polymerization system).

[0119] Comparing the stability of the polymerization system when there are many structures (excluding the stirring shaft and stirring blades) arranged inside the reaction vessel 110 with the stability of the polymerization system when there are few structures arranged inside the reaction vessel 110, the polymerization system is likely to become unstable when there are many structures arranged inside the reaction vessel 110. For example, usually, inside the reaction vessel 110, a baffle is arranged near the inner wall of the reaction vessel 110, and the polymerization system is relatively stable. On the other hand, when a cooling pipe is arranged inside the reaction vessel 110 as in the embodiment described in relation to FIG. 1, the flow state around the cooling pipe and / or the flow state in the region between the cooling pipe and the inner wall of the reaction vessel 110 is likely to become unstable. As a result, the polymerization system is likely to become unstable.

[0120] Even in such a case, the polymerization system is stabilized by adding a dispersing aid to the polymerization system. For example, when a dispersing aid is added to the polymerization system, the dispersion characteristics of the suspension are improved. As a result, the shape of the polymer particles (sometimes called resin particles) is improved, and the plasticizer absorption performance can be improved. A buffering agent may be added to the polymerization system. The stability of the polymerization system is further improved by adding a buffering agent to the polymerization system.

[0121] In general, the amount of dispersion aid added is determined by repeated trial and error. The inventors have noticed that among the structures arranged inside the reaction vessel 110, the structure that has a large effect on the flow state of the polymerization system is the cooling pipe, and have found that there is a correlation between the number of cooling pipes in the radial direction of the reaction vessel 110 and the amount of dispersion aid added.

[0122] That is, according to this embodiment, the number Nc [pieces] of the virtual circles and the ratio CZ [mg-dispersing agent / kg-monomer] are adjusted to satisfy the relationship of the mathematical formula A1. This produces resin particles with a narrow particle size distribution and fewer fish eyes. In addition, the amount of scale adhering to the inside of the reaction vessel 110 due to the polymerization reaction is suppressed.

[0123] By producing a polymer so as to satisfy the relationship of the mathematical formula A1, it is possible to improve the yield while maintaining the quality of the polymer particles described above. For example, a yield of about 90% can be obtained. In addition, after the polymerization reaction is completed, the unreacted monomer is recovered, and the recovered monomer (sometimes called recovered monomer) may be used as a raw material in the next or subsequent reaction. By producing a polymer so as to satisfy the relationship of the mathematical formula A1, it is possible to improve the usage ratio of the recovered monomer. For example, the usage ratio of the recovered monomer can be increased to about 30%.

[0124] In addition, the inventors have found that when the amount of the dispersion aid exceeds a certain level, the effect of the dispersion aid in stabilizing the polymerization system does not increase significantly even if the amount of the dispersion aid is increased. Specifically, when the number Nc of the above virtual circles is 3, the inventors have found that a sufficient amount of the dispersion aid is added to stabilize the polymerization system.

[0125] For example, when the number Nc of the virtual circles is 4 or more, the ratio CZ [mg-dispersing agent / kg-monomer] preferably satisfies the relationship shown in the following formula A2. For example, the amount of dispersing agent added is adjusted so as to satisfy the relationship shown in the following formula A2. This prevents excessive addition of the dispersing agent and provides the above-mentioned effects. (Formula A2) 15×3+300 <CZ<175×3+2000

[0126] When the number Nc [pieces] of the virtual circles and the ratio CZ [mg-dispersing aid / kg-monomer] are adjusted to satisfy the relationship shown in the mathematical formula A1, the average degree of polymerization of the produced polymer is adjusted to, for example, about 200 to 4000. The average degree of polymerization may be adjusted to 300 to 4000, or may be adjusted to 300 to 2000. The average degree of polymerization may be adjusted to 500 to 1500.

[0127] As described above, there is a relatively strong correlation between the average degree of polymerization of a polymer and the reduced viscosity or K value of the polymer. In addition, the polymerization temperature is set according to the reduced viscosity or K value of the target polymer. Therefore, in another embodiment, instead of adjusting the average degree of polymerization of the produced polymer, the reduced viscosity or K value of the polymer, or the polymerization temperature may be adjusted.

[0128] For example, in the case of producing a polyvinyl chloride resin, when the number Nc [pieces] of the imaginary circles and the ratio CZ [mg-dispersing aid / kg-monomer] are adjusted to satisfy the relationship shown in the mathematical formula A1, the reaction temperature (sometimes referred to as polymerization temperature) is adjusted to 30 to 75° C. The reaction temperature may be adjusted to 40 to 70° C., or may be adjusted to 50 to 60° C.

[0129] In one embodiment, when the number Nc of the virtual circles is 1, 2, or 3, the number Nc of the virtual circles and the ratio CZ [mg-dispersing aid / kg-monomer] may satisfy the relationship shown in the following formula B1. For example, the amount of the dispersing aid added is adjusted so as to satisfy the relationship shown in the following formula B1. This can further suppress the amount of scale that adheres to the inside of the reaction vessel 110 due to the polymerization reaction. (Formula B1) 15Nc+310 <CZ<175Nc+1550

[0130] When the number Nc of the virtual circles is 4 or more, the ratio CZ [mg-dispersing agent / kg-monomer] may satisfy the relationship shown in the following formula B2. For example, the amount of the dispersing agent added is adjusted so as to satisfy the relationship shown in the following formula B2. This provides the above-mentioned effects. (Formula B2) 15×3+310 <CZ<175×3+1550

[0131] In another embodiment, when the number Nc of the imaginary circles is 1, 2, or 3, the number Nc of the imaginary circles and the ratio CZ [mg-dispersing aid / kg-monomer] may satisfy the relationship shown in the following formula C1. For example, the amount of dispersing aid added is adjusted so as to satisfy the relationship shown in the following formula C1. This allows the production of resin particles with extremely few fisheyes. (Formula C1) 15Nc+400 <CZ<175Nc+1850

[0132] When the number Nc of the virtual circles is 4 or more, the ratio CZ [mg-dispersing agent / kg-monomer] may satisfy the relationship shown in the following formula C2. For example, the amount of the dispersing agent added is adjusted so as to satisfy the relationship shown in the following formula C2. This provides the above-mentioned effects. (Formula C2) 15×3+400 <CZ<175×3+1850

[0133] In still another embodiment, when the number Nc of the imaginary circles is 1, 2, or 3, the number Nc of the imaginary circles and the ratio CZ [mg-dispersing aid / kg-monomer] may satisfy the relationship shown in the following formula D1. For example, the amount of the dispersing aid added is adjusted so as to satisfy the relationship shown in the following formula D1. This further suppresses the amount of scale adhering to the inside of the reaction vessel 110 due to the polymerization reaction, and allows the production of resin particles with extremely few fisheyes. (Formula D1) 15Nc+400 <CZ<175Nc+1550

[0134] When the number Nc of the virtual circles is 4 or more, the ratio CZ [mg-dispersion aid / kg-raw material solution] may satisfy the relationship shown in the following formula D2. For example, the amount of dispersion aid added is adjusted so as to satisfy the relationship shown in the following formula D2. This provides the above-mentioned effects. (Formula D2) 15×3+400 <CZ<175×3+1550

[0135] By appropriately adjusting the stirring of the polymerization system in addition to the amount of dispersion aid added, the polymerization system becomes more stable. For example, (a) the rotation speed of the stirring shaft 122 in the polymerization apparatus 100 is determined so that the dimensions of the straight body part of the reaction vessel 110, the dimensions of at least one of the multiple stirring blades 124, and the set value of the rotation speed of the stirring shaft 122 satisfy the relationship shown in the above formula 1, and (b) the number Nc [pieces] of the virtual circles and the ratio CZ [mg-dispersion aid / kg-monomer] of the mass of the dispersion aid to the mass of the monomer charged in the reaction vessel 110 satisfy the relationship shown in the above formula A1, B1, C1, or D1, particularly good results are obtained. In addition, the above correlation becomes clearer. Note that, when the number Nc of the virtual circles is 4 or more, the number Nc and the ratio CZ may satisfy the relationship shown in the above formula A2, B2, C2, or D2.

[0136] The causes of these phenomena are unclear, but it is speculated that the polymerization system becomes extremely stable due to the synergistic effect of the effect of properly managing the stirring energy and the effect of properly managing the amount of dispersion aid added. As a result, the amount of scale that adheres to the inside of the reaction vessel 110 due to the polymerization reaction can be suppressed. Also, resin particles with extremely few fish eyes can be produced.

[0137] (Polymerization initiator) As the polymerization initiator, a compound used in conventional vinyl chloride polymerization is used. As the polymerization initiator, percarbonate compounds such as diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, diethoxyethyl peroxydicarbonate, etc.; perester compounds such as α-cumyl peroxyneodecanate, t-butyl peroxyneodecanate, t-butyl peroxyneoheptanoate, hexyl peroxyneodecanate, octyl peroxyneodecanate, etc.; peroxides such as acetylcyclohexylsulfonyl peroxide, 2,4,4-trimethylpentyl-2-peroxyphenoxyacetate, etc.; azo compounds such as azobis-2,4-dimethylvaleronitrile, azobis(4-methoxy-2,4-dimethylvaleronitrile), etc. may be used alone or in combination of two or more kinds.

[0138] The amount of the polymerization initiator to be added is not particularly limited. For example, the polymerization initiator is added in an amount of 0.01 to 3 parts by mass per 100 parts by mass of the monomer. The amount of the polymerization initiator to be added is preferably 0.05 to 3 parts by mass per 100 parts by mass of the monomer.

[0139] Furthermore, various auxiliaries that are appropriately used in vinyl chloride polymerization, such as polymerization regulators, chain transfer agents, pH regulators, buffers, gelation improvers, antistatic agents, and scale inhibitors, may be added as necessary. With regard to the reduced viscosity (K value) of the vinyl chloride polymer obtained by the present invention, a polymer having a reduced viscosity in the desired range can be obtained by using the apparatus of the present invention, and preferably a polymer having a reduced viscosity in the range of 40 to 90 can be obtained.

[0140] Examples of pH adjusters or buffers include citric acid, trisodium citrate, diammonium citrate, triammonium citrate, potassium hydrogen phthalate, sodium nitrate, sodium carbonate, potassium carbonate, cesium carbonate, sodium hydrogen carbonate, sodium hydroxide, potassium hydroxide, barium hydroxide, disodium phosphate, dipotassium phosphate, tripotassium phosphate, etc. The above pH adjusters or buffers may be used alone or in combination of two or more.

[0141] The polymerization apparatus 100 may be an example of a reaction apparatus. The polymerization apparatus 100 may be an example of a batch-type reaction apparatus. The reaction vessel 110 may be an example of a reactor. The inner surface of the reaction vessel 110 may be an example of an inner wall surface of a reactor. The side surface of the reaction vessel 110 may be an example of an inner wall surface of a reactor. The flow path of the heat medium arranged in the main body 132 of the baffle 130 may be an example of a second cooling pipe. The support 134 of the baffle 130 may be an example of at least a part of the baffle. The serpentine cooling pipe 140 may be an example of a first cooling pipe. The serpentine cooling pipe 150 may be an example of a first cooling pipe. One of the serpentine cooling pipes 140 and one of the serpentine cooling pipes 150 may be an example of at least two of the multiple first cooling pipes. The flow path 172 may be an example of a third cooling pipe. The flow path 182 may be an example of a third cooling pipe.

[0142] (An example of another embodiment) In this embodiment, an example of the polymerization apparatus 100 has been described by taking as an example a case in which the serpentine cooling pipes 140 and 150 that extend while repeatedly bending are disposed inside the reaction vessel 110. As described above, the serpentine cooling pipes 140 and 150 include a plurality of extension parts that extend linearly or curvedly, and one or more bent parts that connect the ends of two adjacent extension parts. However, the polymerization apparatus 100 is not limited to this embodiment.

[0143] In another embodiment, the polymerization apparatus 100 may include a ring-shaped (sometimes referred to as a coil-shaped) cooling pipe (sometimes referred to as a ring cooling pipe) as described in JP-A-7-233206 inside the reaction vessel 110. The polymerization apparatus 100 may include a plurality of ring cooling pipes. Representative points of the plurality of ring cooling pipes may be substantially located on the circumferences of the above-mentioned plurality of imaginary circles. Each of the plurality of ring cooling pipes includes, for example, a plurality of ring portions having a ring shape and one or more connecting portions connecting the plurality of ring portions as described in JP-A-7-233206.

[0144] Even if the polymerization apparatus 100 is provided with one or more ring cooling pipes inside the reaction vessel 110, when the number Nc [pieces] of the above imaginary circles is 1, 2 or 3, the number Nc [pieces] of the imaginary circles and the ratio CZ [mg-dispersion aid / kg-monomer] of the mass of the dispersion aid to the mass of the monomer charged in the reaction vessel 110 may satisfy the relationship shown in the above formula A1, B1, C1 or D1. This provides the above-mentioned effects.

[0145] FIG. 2 is a schematic diagram of an example of an internal structure disposed inside the reaction vessel 110. In FIG. 2, the agitator 120 is omitted from the illustration for the purpose of simplifying the description. As shown in FIG. 2, the polymerization apparatus 100 includes a baffle 232, a baffle 234, a baffle 236, and a baffle 238 as one or more baffles 130. The polymerization apparatus 100 also includes a serpentine cooling pipe 242, a serpentine cooling pipe 244, a serpentine cooling pipe 246, and a serpentine cooling pipe 248 as one or more serpentine cooling pipes 140. Similarly, the polymerization apparatus 100 includes a serpentine cooling pipe 252, a serpentine cooling pipe 254, a serpentine cooling pipe 256, and a serpentine cooling pipe 258 as one or more serpentine cooling pipes 150.

[0146] Fig. 3 shows a schematic cross-sectional view of an example of the reaction vessel 110. In Fig. 3, for the purpose of simplifying the explanation, the depiction of the serpentine cooling pipe 140 is omitted. Also, for the purpose of simplifying the explanation, the installation positions of the baffle 232, the baffle 234, the baffle 236, and the baffle 238 are deformed.

[0147] 3, in this embodiment, the reaction vessel 110 includes a straight body section 312, a first end plate 314, a second end plate 316, and a base 318. In this embodiment, the straight body section 312 has a cylindrical shape. When the length of the straight body section 312 in the extension direction (z direction in the figure) is L and the inner diameter of the straight body section 312 is D, the straight body section 312 is designed to have an L / D value of, for example, 1.0 to 3.0. The straight body section 312 may be designed to have an L / D value of 1.5 to 2.5.

[0148] In this embodiment, the first end plate 314 is connected to one end of the straight body portion 312 and constitutes a bottom plate of the reaction vessel 110. In this embodiment, the second end plate 316 is connected to the other end of the straight body portion 312 and constitutes a top plate of the reaction vessel 110. In this embodiment, the base 318 holds the power mechanism 126.

[0149] As shown in FIG. 3, a refrigerant supply pipe 332 for supplying a refrigerant from a refrigerant supply source to the reaction vessel 110 and a refrigerant return pipe 334 for returning the refrigerant after heat exchange from the reaction vessel 110 to the refrigerant supply source are arranged around the polymerization apparatus 100. According to the embodiment shown in FIG. 3, the baffle 232 and the baffle 234 are connected by a connecting portion 342, and the refrigerant flowing out of the baffle 232 can flow into the baffle 234. The baffle 234 and the baffle 236 are connected by a connecting portion 344, and the refrigerant flowing out of the baffle 234 can flow into the baffle 236. Similarly, the baffle 236 and the baffle 238 are connected by a connecting portion 346, and the refrigerant flowing out of the baffle 236 can flow into the baffle 238. Details of each baffle will be described later.

[0150] According to this embodiment, the coolant supplied from the coolant supply pipe 332 to the reaction vessel 110 flows into the baffle 232, passes through the baffle 234, the baffle 236, and the baffle 238, and is discharged to the coolant return pipe 334. The flow method of the coolant is not limited to this embodiment.

[0151] For example, in another embodiment, the coolant supplied from the coolant supply pipe 332 to the reaction vessel 110 flows into the baffle 232, passes through the baffle 234, and is discharged to the coolant return pipe 334. Also, the coolant supplied from the coolant supply pipe 332 to the reaction vessel 110 flows into the baffle 238, passes through the baffle 236, and is discharged to the coolant return pipe 334. In still another embodiment, each of the baffles 232, 234, 236, and 238 is configured to be able to independently control the flow rate of the coolant supplied to each baffle.

[0152] 4 shows a schematic plan view of an example of the reaction vessel 110. In this embodiment, (i) baffle 232, baffle 234, baffle 236, and baffle 238, (ii) serpentine cooling tube 242, serpentine cooling tube 244, serpentine cooling tube 246, and serpentine cooling tube 248, and (iii) serpentine cooling tube 252, serpentine cooling tube 254, serpentine cooling tube 256, and serpentine cooling tube 258 are concentrically arranged.

[0153] In this embodiment, the serpentine cooling pipe 242, the serpentine cooling pipe 244, the serpentine cooling pipe 246, and the serpentine cooling pipe 248 are arranged on approximately the same circumference. Also, in this embodiment, (i) the baffle 232, the baffle 234, the baffle 236, and the baffle 238, and (ii) the serpentine cooling pipe 252, the serpentine cooling pipe 254, the serpentine cooling pipe 256, and the serpentine cooling pipe 258 are arranged on approximately the same circumference.

[0154] That is, in a cross section at a specific position of the straight body portion 312, the center of the cross section of the baffle 232, the baffle 234, the baffle 236, and the baffle 238 and the center of the cross section of the serpentine cooling pipe 252, the serpentine cooling pipe 254, the serpentine cooling pipe 256, and the serpentine cooling pipe 258 are arranged on approximately the same circumference. The cross section at a specific position of the straight body portion 312 may be a cross section of the reaction vessel 110 cut by a plane (xy plane in the figure) perpendicular to the extension direction (z direction in the figure) of the straight body portion 312 and passing through the centers of the serpentine cooling pipe 252, the serpentine cooling pipe 254, the serpentine cooling pipe 256, and the serpentine cooling pipe 258. In this case, the width of each pipe in the cross section corresponds to the diameter of each pipe.

[0155] In this embodiment, baffle 232, baffle 234, baffle 236, and baffle 238 are disposed at approximately symmetrical positions around the central axis of reaction vessel 110. Serpentine cooling tube 242, serpentine cooling tube 244, serpentine cooling tube 246, and serpentine cooling tube 248 are disposed at approximately symmetrical positions around the central axis of reaction vessel 110. Serpentine cooling tube 252, serpentine cooling tube 254, serpentine cooling tube 256, and serpentine cooling tube 258 are disposed at approximately symmetrical positions around the central axis of reaction vessel 110.

[0156] 4 , serpentine cooling tube 252 is disposed between baffle 232 and baffle 234. Serpentine cooling tube 254 is disposed between baffle 234 and baffle 236. Serpentine cooling tube 256 is disposed between baffle 236 and baffle 238. Serpentine cooling tube 258 is disposed between baffle 238 and baffle 232. The outer diameters of serpentine cooling tube 252, serpentine cooling tube 254, serpentine cooling tube 256, and serpentine cooling tube 258 may be smaller than the widths Bw of baffles 232, 234, 236, and 238.

[0157] In this embodiment, the diameter of the circle on which the serpentine cooling pipe 242, the serpentine cooling pipe 244, the serpentine cooling pipe 246, and the serpentine cooling pipe 248 are arranged is smaller than the diameter of the circle on which the serpentine cooling pipe 252, the serpentine cooling pipe 254, the serpentine cooling pipe 256, and the serpentine cooling pipe 258 are arranged. According to this embodiment, the serpentine cooling pipes can be arranged in multiple stages in the diameter direction of the straight body part 312 of the reaction vessel 110. This improves the degree of freedom in the arrangement of the internal structure, for example, compared to the case where a large ring-shaped or spiral-shaped pipe is arranged inside the reaction vessel 110. As a result, a polymerization apparatus 100 with excellent cooling efficiency can be manufactured.

[0158] A diameter D of an imaginary circle on which the outer circumferences of the serpentine cooling pipe 242, the serpentine cooling pipe 244, the serpentine cooling pipe 246, and the serpentine cooling pipe 248 are arranged. c The size of the stirring blade 124 is not particularly limited, but is preferably a diameter D of the rotating area of ​​the stirring blade 124. d Larger is better. D c / D d is preferably 1.1 or more, and more preferably 1.2 or more.

[0159] In this embodiment, the distances between the serpentine cooling tube 252, the serpentine cooling tube 254, the serpentine cooling tube 256, and the serpentine cooling tube 258 and the inner surface of the straight body portion 312 are all P C1 Similarly, the distances between the serpentine cooling pipe 242, the serpentine cooling pipe 244, the serpentine cooling pipe 246, and the serpentine cooling pipe 248 and the inner surface of the straight body portion 312 are all P C2 As shown in FIG. C2 >P C1 It is.

[0160] The above P C1 and P C2 The size of P is not particularly limited. C1 It is preferable that the distance between the outer periphery of each serpentine cooling pipe and the inner surface of the straight body portion 312 is set to 40 mm or more. C1 The distance or P may be set to be 40 mm or more. C1If the distance is less than 40 mm, polymer scale may easily adhere between the inner wall surface of the reaction vessel 110 and the serpentine cooling pipe 150 near the gas-liquid interface inside the reaction vessel 110.

[0161] Similarly, the distance P between the serpentine cooling pipe 242 and the serpentine cooling pipe 252 C The distance Pc is preferably 40 mm or more. For example, the distance Pc is determined by calculating the minimum value of the distance between the outer periphery of the serpentine cooling pipe 242 and the outer periphery of the serpentine cooling pipe 252 in the above cross section. P C If the distance is less than 40 mm, polymer scale may easily adhere.

[0162] The distance between a specific serpentine cooling pipe and the inner surface of the straight body portion 312 may be determined as the shortest distance between them in a cross section perpendicular to the extension direction of the straight body portion 312 and passing through the center of the specific serpentine cooling pipe. The distance between each serpentine cooling pipe and the inner surface of the straight body portion 312 is determined, for example, by calculating the minimum value of the distance between the center line along the extension direction of each serpentine cooling pipe and the inner surface of the straight body portion 312 in the above cross section. In this embodiment, the center line along the extension direction of each serpentine cooling pipe is curved in an arc shape. The details of the above distances will be described later.

[0163] 4, in a cross section at a specific position of the straight body portion 312, the cross sections of the serpentine cooling pipe 242, the serpentine cooling pipe 244, the serpentine cooling pipe 246, and the serpentine cooling pipe 254 have an arc-shaped cross section. Similarly, the cross sections of the serpentine cooling pipe 252, the serpentine cooling pipe 254, the serpentine cooling pipe 256, and the serpentine cooling pipe 258 have an arc-shaped cross section. The cross-sectional shapes of the serpentine cooling pipe 242, the serpentine cooling pipe 244, the serpentine cooling pipe 246, and the serpentine cooling pipe 254 and the cross-sectional shapes of the serpentine cooling pipe 252, the serpentine cooling pipe 254, the serpentine cooling pipe 256, and the serpentine cooling pipe 258 may be similar in shape. For example, when the cross sections of serpentine cooling pipe 242 and serpentine cooling pipe 252 have an arc-shaped shape, the central angle of the arc of serpentine cooling pipe 242 may be substantially the same as the central angle of the arc of serpentine cooling pipe 252. The same may be true for serpentine cooling pipe 244 and serpentine cooling pipe 254, serpentine cooling pipe 246 and serpentine cooling pipe 256, and serpentine cooling pipe 248 and serpentine cooling pipe 258.

[0164] When the shape of the serpentine cooling pipe is an arc, the magnitude of the central angle of the arc may be 270 degrees or less, 240 degrees or less, 210 degrees or less, 180 degrees or less, 150 degrees or less, 120 degrees or less, 90 degrees or less, or 60 degrees or less.

[0165] In this embodiment, the length in the extension direction of at least one of the serpentine cooling pipes 252, 254, 256, and 258 (the length of the arc in the drawing) is smaller than 2 / 3 of the length of the inner circumference of the straight body portion 312. The length in the extension direction (the length of the arc in the drawing) may be 1 / 2 or less of the length of the inner circumference of the straight body portion 312, may be smaller than 1 / 2 of the length of the inner circumference of the straight body portion 312, may be smaller than 1 / 3 of the length of the inner circumference of the straight body portion 312, may be smaller than 1 / 3 of the length of the inner circumference of the straight body portion 312, may be 1 / 4 or less of the length of the inner circumference of the straight body portion 312, may be smaller than 1 / 4 of the length of the inner circumference of the straight body portion 312, may be 1 / 6 or less of the length of the inner circumference of the straight body portion 312, or may be smaller than 1 / 6 of the length of the inner circumference of the straight body portion 312.

[0166] As described above, the coiled cooling pipe described in JP-A-7-233206 has a substantially circular shape. That is, the central angle of the arc of the cooling pipe is approximately 360 degrees. Therefore, the baffle and the coiled cooling pipe cannot be arranged on approximately the same circumference. In contrast, according to the present embodiment, at least one of the one or more serpentine cooling pipes 150 arranged at a position closer to the inside of the straight body portion 312 than the serpentine cooling pipe 140 has the above-mentioned configuration and can be arranged between the two baffles 130. This makes it possible to increase the heat transfer area of ​​the entire apparatus while reducing the effect of the serpentine cooling pipe 150 on the mixing performance of the polymerization apparatus 100.

[0167] The inner surface of the straight body portion 312 may be an example of an inner wall surface of a reactor. The serpentine cooling pipe 252 may be an example of a first cooling pipe having the shortest distance from the inner wall surface of the reactor. The serpentine cooling pipe 254 may be an example of a first cooling pipe having the shortest distance from the inner wall surface of the reactor. The serpentine cooling pipe 256 may be an example of a first cooling pipe having the shortest distance from the inner wall surface of the reactor. The serpentine cooling pipe 258 may be an example of a first cooling pipe having the shortest distance from the inner wall surface of the reactor.

[0168] (An example of another embodiment) In this embodiment, an example of the polymerization apparatus 100 has been described taking as an example a case where the serpentine cooling pipe is multiplexed twice from the center of the straight body portion 312 to the outside. However, the polymerization apparatus 100 is not limited to this embodiment. In other embodiments, the serpentine cooling pipe may be multiplexed three or more times from the center of the straight body portion 312 to the outside. It is preferable that the serpentine cooling pipe is multiplexed two to five times from the center of the straight body portion 312 to the outside.

[0169] 5 shows an example of the internal structure of the baffle 232. Note that the baffles 234, 236, and 238 may have the same internal structure as the baffle 232. In this embodiment, the baffle 232 has a double-tube structure including an inner tube 510 and an outer tube 520. The baffle 232 has an inlet 512 through which the refrigerant flows into the inner tube 510, and an outlet 522 through which the refrigerant flows out from the inner tube 520.

[0170] In this embodiment, the inlet 512 of the baffle 232 is connected to the refrigerant supply pipe 332 via a pipe 532 and a flow rate control valve 542. This adjusts the opening degree of the flow rate control valve 542, thereby adjusting the flow rate of the refrigerant flowing into the baffle 232. Similarly, the inlet 512 of the baffle 234 is connected to the refrigerant supply pipe 332 via a pipe 534 and a flow rate control valve 544.

[0171] In this embodiment, the outlet 522 of the baffle 232 is connected to the refrigerant return pipe 334 and the baffle 234 via a connecting portion 342. As shown in FIG 5, in this embodiment, the connecting portion 342 has a pipe 552, a flow rate control valve 554, a pipe 556, and a flow rate control valve 558.

[0172] The pipe 552 connects the outlet 522 and the refrigerant return pipe 334. The flow rate control valve 554 is disposed in the middle of the pipe 552 and adjusts the flow rate of the refrigerant flowing through the pipe 552. The pipe 556 connects the outlet 522 and the baffle 234. More specifically, the pipe 556 connects a position on the pipe 552 between the flow rate control valve 554 and the outlet 522 of the baffle 232 and a position on the pipe 534 between the flow rate control valve 544 and the inlet 512 of the baffle 234. The flow rate control valve 558 is disposed in the middle of the pipe 556 and adjusts the flow rate of the refrigerant flowing through the pipe 556.

[0173] (An example of another embodiment) In this embodiment, an example of the polymerization apparatus 100 has been described in which the baffle 232 has a double pipe structure, and the refrigerant that flows in from below the baffle 232 flows out from below the baffle 232 and flows into the baffle 234 from below the baffle 234. However, the polymerization apparatus 100 is not limited to this embodiment.

[0174] In another embodiment, the piping may be configured such that the coolant flowing in from below the baffle 232 flows out from above the baffle 232 and flows into the baffle 234 from above the baffle 234. In yet another embodiment, the baffle 232 may be a single pipe.

[0175] 6 shows a schematic example of the structure of the serpentine cooling pipe 252. The other serpentine cooling pipes 140 and 150 may have the same structure as the serpentine cooling pipe 252. As shown in FIG. 6, the serpentine cooling pipe 252 extends in the z direction while repeatedly bending. In this embodiment, the serpentine cooling pipe 252 has a serpentine portion 610. The serpentine portion 610 has a plurality of extension portions 612 and one or more bent portions 614.

[0176] In the serpentine cooling tube 252 described in relation to Fig. 6, the serpentine portion 610 has 15 extensions 612 and 14 bends 614. The number of extensions 612 in a single serpentine portion 610 may be referred to as the number of stages. As shown in Fig. 2, in this embodiment, the serpentine cooling tube 252 extends in the xy plane at the extensions 612 and bends in the z direction at the bends 614.

[0177] In this embodiment, each of the multiple extension parts 612 extends on approximately the same plane. For example, even if the extension parts 612 are designed to extend on the same plane, the extension parts 612 may not extend completely on the same plane due to manufacturing errors, installation errors, and the like. In such a case, the extension parts 612 may be considered to extend on approximately the same plane. Note that the case where the extension parts 612 extend on approximately the same plane is not limited to the above example.

[0178] In this respect, the serpentine cooling pipe 252 differs from a spiral cooling pipe. Since the serpentine cooling pipe 252 extends in a serpentine manner, the surface area per installation area can be increased compared to a cooling pipe extending in a spiral manner.

[0179] As described in relation to FIG. 4, in this embodiment, each of the multiple extension parts 612 extends while curving on the xy plane. L The lengths of the extension portions 612 in the extension direction may be the same, or the lengths of at least two extension portions 612 in the extension direction may be different. L is the length of the extension 612 on the xy plane. L may be the length of the extension portion 612 in an xy plane passing through the center of a cross section of the extension portion 612 when the extension portion 612 is cut by a plane approximately perpendicular to the extension direction of the extension portion 612 (in this case, a plane approximately parallel to the z direction).

[0180] As mentioned above, P L may be smaller than ⅔ of the length of the inner circumference of the body portion 312. In this respect, the serpentine cooling pipe 252 differs from the coiled cooling pipe described in JP-A-7-233206.

[0181] In a single meandering portion 610, the P of more than 1 / 2 of the multiple extension portions 612 is L However, it is acceptable for the length of the inner circumference of the straight body portion 312 to be smaller than 2 / 3 of the length of the inner circumference of the straight body portion 312. L may be 1 / 2 or less of the inner circumference length of the straight body portion 312, may be less than 1 / 2 of the inner circumference length of the straight body portion 312, may be 1 / 3 or less of the inner circumference length of the straight body portion 312, may be less than 1 / 3 of the inner circumference length of the straight body portion 312, may be 1 / 4 or less of the inner circumference length of the straight body portion 312, may be less than 1 / 4 of the inner circumference length of the straight body portion 312, may be 1 / 6 or less of the inner circumference length of the straight body portion 312, or may be less than 1 / 6 of the inner circumference length of the straight body portion 312.

[0182] Among the multiple extensions 612, P of more than 2 / 3 of the extensions 612 L However, it is acceptable for the length of the inner circumference of the straight body portion 312 to be smaller than 2 / 3 of the length of the inner circumference of the straight body portion 312. L may be 1 / 2 or less of the inner circumference length of the straight body portion 312, may be less than 1 / 2 of the inner circumference length of the straight body portion 312, may be 1 / 3 or less of the inner circumference length of the straight body portion 312, may be less than 1 / 3 of the inner circumference length of the straight body portion 312, may be 1 / 4 or less of the inner circumference length of the straight body portion 312, may be less than 1 / 4 of the inner circumference length of the straight body portion 312, may be 1 / 6 or less of the inner circumference length of the straight body portion 312, or may be less than 1 / 6 of the inner circumference length of the straight body portion 312.

[0183] In one embodiment, at least one of the multiple extension portions 612 extends in a curved manner on approximately the same plane. For example, at least one of the multiple extension portions 612 extends along a circular or elliptical arc virtually disposed on the xy plane. In another embodiment, at least one of the multiple extension portions 612 extends linearly on approximately the same plane.

[0184] In this embodiment, two of the multiple extension portions 612 extend on two substantially parallel planes. For example, two adjacent extension portions 612 extend on two substantially parallel planes. This results in a meandering portion 610 that extends in a ladder shape. In another embodiment, two of the multiple extension portions 612 may extend on two non-parallel planes. For example, two adjacent extension portions 612 extend on two intersecting planes. This results in a meandering portion 610 that extends in a zigzag shape.

[0185] In this embodiment, each of the one or more bent portions 614 connects the ends of two adjacent extension portions 612. In the embodiment shown in FIG. 6, each of the one or more bent portions 614 includes a portion bent in the z direction. As a result, the serpentine portion 610 extends in the z direction while bending. The shape of the bent portion 614 is not particularly limited. The shape of a cross section (sometimes referred to as a longitudinal section) of the bent portion 614 cut along a plane parallel to the extension direction of the serpentine cooling pipe 252 and passing through the center of the bent portion 614 may have a continuously bent shape or a shape composed of a plurality of straight lines. Examples of the continuously bent shape include a circular arc shape or an elliptical arc shape. The bent portion 614 may be composed of a portion having a continuously bent shape and a portion having a shape composed of one or more straight lines.

[0186] The diameter of the flow path of the serpentine cooling pipe 252 is not particularly limited, but the above diameter is preferably 10 to 200 mm. The number of extensions 612 (sometimes referred to as the number of stages) included in a single serpentine cooling pipe 252 is not particularly limited, but the above number of stages is preferably 2 to 70. The size of the distance (sometimes referred to as the pitch) Pp between two adjacent extensions 612 is not particularly limited, but the above Pp is preferably 60 mm or more. If Pp is less than 60 mm, polymer scale may easily adhere.

[0187] (An example of another embodiment) In the present embodiment, an example of the serpentine cooling pipe 252 has been described, taking as an example the case where the serpentine cooling pipe 252 extends in the z direction while bending. However, the serpentine cooling pipe 252 is not limited to the present embodiment. In other embodiments, the serpentine cooling pipe 252 may extend in the x direction or the y direction while bending.

[0188] In the present embodiment, an example of the serpentine cooling pipe 252 has been described, taking as an example a case where the extension portion 612 extends on the xy plane and the bent portion 614 is bent in the z direction. However, the serpentine cooling pipe 252 is not limited to this embodiment. In other embodiments, the bent portion 614 may have a first bent member that is bent on the xy plane and a second bent member that is bent in the z direction.

[0189] 7 shows another example of the structure of the serpentine cooling pipe 252. In this embodiment, the serpentine cooling pipe 252 extends in the z-direction while bending in a zigzag shape. In this embodiment, the serpentine cooling pipe 252 includes a supply pipe 702, an outlet pipe 704, and a serpentine portion 710. In this embodiment, the serpentine portion 710 includes a plurality of extension portions 712 and one or more bend portions 714.

[0190] The supply pipe 702 distributes the refrigerant supplied to the serpentine portion 710. The outlet pipe 704 distributes the refrigerant discharged from the serpentine portion 710. The serpentine portion 710 extends in the z direction while repeatedly bending.

[0191] The serpentine cooling pipe 252 described with reference to Fig. 7 differs from the serpentine cooling pipe 252 described with reference to Fig. 6 in that the multiple extensions 712 are not arranged substantially parallel to each other. Regarding characteristics other than the above differences, the serpentine cooling pipe 252 described with reference to Fig. 7 may have a similar configuration to the serpentine cooling pipe 252 described with reference to Fig. 6.

[0192] 8 is a schematic diagram showing another example of the structure of the serpentine cooling pipe 252. In this embodiment, the serpentine cooling pipe 252 includes a supply pipe 702, an outlet pipe 704, and a serpentine portion 810. In this embodiment, the serpentine portion 810 includes a serpentine portion 812, a connecting portion 822, a serpentine portion 814, a connecting portion 824, and a serpentine portion 816.

[0193] In this embodiment, the serpentine portion 810 extends in the z direction while repeatedly bending. In this embodiment, the serpentine portion 812 extends in the x direction while repeatedly bending. The serpentine portion 812 extends, for example, in the positive direction of the x direction. In this embodiment, the connecting portion 822 connects the serpentine portion 812 and the serpentine portion 814. In this embodiment, the serpentine portion 814 extends in the x direction while repeatedly bending. The serpentine portion 814 extends, for example, in the negative direction of the x direction. In this embodiment, the connecting portion 824 connects the serpentine portion 814 and the serpentine portion 816. In this embodiment, the serpentine portion 816 extends in the x direction while repeatedly bending. The serpentine portion 814 extends, for example, in the positive direction of the x direction.

[0194] Each of the serpentine portion 812, the serpentine portion 814, and the serpentine portion 816 may have a configuration similar to that of the serpentine portion 610. For example, at least one of the serpentine portion 812, the serpentine portion 814, and the serpentine portion 816 has a plurality of extension portions and one or more bent portions. In this case, each of the plurality of extension portions may extend on the xy plane, may extend on the xz plane, or may extend on the yz plane.

[0195] 9 is a schematic diagram of an example of a main part of a polymerization apparatus 900. The polymerization apparatus 900 differs from the polymerization apparatus 100 in that the pitch Pp of the serpentine cooling pipe 140 is different from the pitch Pp of the serpentine cooling pipe 150. Regarding characteristics other than the above differences, the polymerization apparatus 900 may have the same configuration as the polymerization apparatus 100.

[0196] The pitch Pp of the serpentine cooling pipe 140 may be larger than the pitch Pp of the serpentine cooling pipe 150. For example, when the viscosity of the slurry flowing inside the reaction vessel 110 is relatively high, the flow of the slurry becomes slow. When the flow of the slurry becomes slow, scale is likely to adhere to the surfaces of the serpentine cooling pipe 140, the serpentine cooling pipe 150, the straight body portion 312, and the like. An example of a case where the viscosity of the slurry is relatively high is suspension polymerization of vinyl chloride. Even in such a case, since the serpentine cooling pipe 140 has a relatively large pitch Pp, the discharge flow generated by the stirring blade 124 reaches the serpentine cooling pipe 150 and the straight body portion 312 while retaining sufficient momentum. As a result, the flow state in the vicinity of the serpentine cooling pipe 140, the serpentine cooling pipe 150, the straight body portion 312, and the like is improved, and adhesion of scale is prevented.

[0197] (An example of another embodiment) In other embodiments, the pitch Pp of the serpentine cooling tubes 140 may be smaller than the pitch Pp of the serpentine cooling tubes 150.

[0198] 10 is a schematic diagram of an example of a main part of a polymerization apparatus 1000. The polymerization apparatus 1000 differs from the polymerization apparatus 100 in that the number of stages of the serpentine cooling pipes 140 and the number of stages of the serpentine cooling pipes 150 are different. With respect to features other than the above differences, the polymerization apparatus 1000 may have the same configuration as the polymerization apparatus 100. Furthermore, the polymerization apparatus 1000 may have features of various polymerization apparatuses according to other embodiments, to the extent that there is no technical contradiction.

[0199] In one embodiment, the number of stages of the serpentine cooling tube 140 and the serpentine cooling tube 150 is adjusted so that the position of the upper end of the serpentine cooling tube 140 is lower than the position of the upper end of the serpentine cooling tube 150. For example, when the viscosity of the slurry flowing inside the reaction vessel 110 is relatively high, scales are likely to adhere to the gas-liquid interface and foaming is likely to occur. An example of a case where the viscosity of the slurry is relatively high is suspension polymerization of vinyl chloride. When foaming at the gas-liquid interface becomes intense, heat removal by the reflux condenser 180 is limited. Even in such a case, the height of the upper end of the serpentine cooling tube 140 arranged closer to the stirring blade 124 is suppressed, so that the flow of the gas-liquid interface becomes active and adhesion and foaming of the slurry can be suppressed. It is preferable that the number of stages of the serpentine cooling tube 140 is adjusted so that the position of the upper end of the serpentine cooling tube 140 is lower than the stirring blade 124 arranged at the top stage.

[0200] (An example of another embodiment) In another embodiment, the number of stages of the serpentine cooling pipe 140 and the serpentine cooling pipe 150 may be adjusted so that the position of the lower end of the serpentine cooling pipe 140 is higher than the position of the lower end of the serpentine cooling pipe 150. In still another embodiment, the number of stages of the serpentine cooling pipe 140 is adjusted so that the serpentine cooling pipe 140 does not interfere with the rotation of the stirring blade 124.

[0201] 11 shows a schematic diagram of an example of a main part of a polymerization apparatus 1100. The polymerization apparatus 1100 differs from the polymerization apparatus 100 in that the polymerization apparatus 1100 includes a serpentine cooling pipe 1160 between the serpentine cooling pipe 140 and the serpentine cooling pipe 150. With respect to features other than the above differences, the polymerization apparatus 1100 may have the same configuration as the polymerization apparatus 100. Furthermore, the polymerization apparatus 1100 may have features of various polymerization apparatuses according to other embodiments, to the extent that there is no technical contradiction.

[0202] 12 is a schematic diagram of an example of a main part of a polymerization apparatus 1200. The polymerization apparatus 1200 differs from the polymerization apparatus 100 in that the polymerization apparatus 1200 includes a serpentine cooling pipe 1252 having a semicircular cross section, instead of the serpentine cooling pipe 252, the serpentine cooling pipe 256, and the serpentine cooling pipe 258. With respect to features other than the above differences, the polymerization apparatus 1200 may have the same configuration as the polymerization apparatus 100. Furthermore, the polymerization apparatus 1200 may have features of various polymerization apparatuses according to other embodiments, to the extent that there is no technical contradiction.

[0203] FIG. 13 is a schematic diagram of an example of a main part of the polymerization apparatus 1300. The polymerization apparatus 1300 differs from the polymerization apparatus 100 in that the polymerization apparatus 1300 includes a serpentine cooling tube 1351, a serpentine cooling tube 1352, a serpentine cooling tube 1353, a serpentine cooling tube 1354, a serpentine cooling tube 1355, and a serpentine cooling tube 1356 each including a straight extending extension portion 612, instead of the serpentine cooling tube 252, the serpentine cooling tube 254, the serpentine cooling tube 256, and the serpentine cooling tube 258 each including a curved extending extension portion 612. The polymerization apparatus 1200 also differs from the polymerization apparatus 100 in that the polymerization apparatus 1200 includes a baffle 1331, a baffle 1332, a baffle 1333, a baffle 1334, a baffle 1335, and a baffle 1336. The polymerization apparatus 1300 may have the same configuration as the polymerization apparatus 100, except for the above differences. Furthermore, within the scope not technically inconsistent, the polymerization apparatus 1300 may have the features of various polymerization apparatuses according to other embodiments.

[0204] In this embodiment, the serpentine cooling pipe 1351, the serpentine cooling pipe 1352, the serpentine cooling pipe 1353, the serpentine cooling pipe 1354, the serpentine cooling pipe 1355, and the serpentine cooling pipe 1356 are disposed on the sides of an imaginary regular hexagon at positions approximately symmetrical around the central axis of the reaction vessel 110. Also, the baffle 1331, the baffle 1332, the baffle 1333, the baffle 1334, the baffle 1335, and the baffle 1336 are disposed at the vertices of the imaginary regular hexagon.

[0205] According to this embodiment, the number of the serpentine cooling pipes 140 is different from the number of the serpentine cooling pipes 150. For example, the number of the serpentine cooling pipes 140 is smaller than the number of the serpentine cooling pipes 150. According to this embodiment, the shape of the serpentine cooling pipe 140 is not similar to the shape of the serpentine cooling pipe 150. For example, the extension portion 612 of the serpentine cooling pipe 140 extends in a curved manner, and the extension portion 612 of the serpentine cooling pipe 150 extends in a straight manner.

[0206] (An example of another embodiment) In this embodiment, an example of the polymerization apparatus 1300 has been described in which the baffle 1331, the baffle 1332, the baffle 1333, the baffle 1334, the baffle 1335, and the baffle 1336 are arranged at the vertices of an imaginary regular hexagon. However, the polymerization apparatus 1300 is not limited to this embodiment.

[0207] In another embodiment, at least one of the baffle 1331, the baffle 1332, the baffle 1333, the baffle 1334, the baffle 1335, and the baffle 1336 may be disposed between the regular hexagon and the straight body portion 312. In yet another embodiment, at least one of the baffle 1331, the baffle 1332, the baffle 1333, the baffle 1334, the baffle 1335, and the baffle 1336 may be disposed between the regular hexagon and an imaginary circle on which the serpentine cooling tube 242, the serpentine cooling tube 244, the serpentine cooling tube 246, and the serpentine cooling tube 248 are disposed.

[0208] According to the present embodiment, an example of the polymerization apparatus 1300 has been described, taking as an example a case where the number of the serpentine cooling pipes 140 is smaller than the number of the serpentine cooling pipes 150. However, the polymerization apparatus 1300 is not limited to this embodiment. In other embodiments, the number of the serpentine cooling pipes 140 may be larger than the number of the serpentine cooling pipes 150.

[0209] According to the present embodiment, an example of the polymerization apparatus 1300 has been described in which the extension portion 612 of the serpentine cooling pipe 140 extends in a curved manner and the extension portion 612 of the serpentine cooling pipe 150 extends in a straight manner. However, the polymerization apparatus 1300 is not limited to the present embodiment. In other embodiments, the extension portion 612 of the serpentine cooling pipe 140 may extend in a straight manner and the extension portion 612 of the serpentine cooling pipe 150 may extend in a curved manner.

[0210] (An example of another embodiment) In this embodiment, an example of the polymerization device 1300 has been described by taking as an example a case in which the diameter of the virtual circle 1403 is larger than the diameter of the virtual circle 1404 and smaller than the diameter of the virtual circle 1405. However, the polymerization device 1300 is not limited to this embodiment. In other embodiments, the diameter of the virtual circle 1403 may be smaller than the diameter of the virtual circle 1404. In still other embodiments, the diameter of the virtual circle 1403 may be larger than the diameter of the virtual circle 1405.

[0211] FIG. 14 shows an example of a main part of the polymerization apparatus 1400. The polymerization apparatus 1400 differs from the polymerization apparatus 100 in that an imaginary circle 1403 on which the baffle 232, the baffle 234, the baffle 236, and the baffle 238 are arranged is arranged between an imaginary circle 1404 on which the serpentine cooling tube 242, the serpentine cooling tube 244, the serpentine cooling tube 246, and the serpentine cooling tube 248 are arranged, and an imaginary circle 1405 on which the serpentine cooling tube 252, the serpentine cooling tube 254, the serpentine cooling tube 256, and the serpentine cooling tube 258 are arranged. With respect to the characteristics other than the above differences, the polymerization apparatus 1400 may have the same configuration as the polymerization apparatus 100. Furthermore, within a technically compatible range, the polymerization apparatus 1400 may have the characteristics of various polymerization apparatuses according to other embodiments.

[0212] FIG. 15 shows an example of a main part of the polymerization apparatus 1500. The polymerization apparatus 1500 differs from the polymerization apparatus 1400 in that the baffle 232 is disposed between the serpentine cooling pipe 242 and the serpentine cooling pipe 252, the baffle 234 is disposed between the serpentine cooling pipe 244 and the serpentine cooling pipe 254, the baffle 236 is disposed between the serpentine cooling pipe 246 and the serpentine cooling pipe 256, and the baffle 238 is disposed between the serpentine cooling pipe 248 and the serpentine cooling pipe 258. With respect to the characteristics other than the above differences, the polymerization apparatus 1500 may have the same configuration as the polymerization apparatus 1400. Furthermore, the polymerization apparatus 1500 may have the characteristics of various polymerization apparatuses according to other embodiments, as long as there is no technical contradiction.

[0213] 16 shows an example of a main part of a polymerization apparatus 1600. The polymerization apparatus 1600 differs from the polymerization apparatus 100 in that the polymerization apparatus 1600 does not include the serpentine cooling pipe 244 and the serpentine cooling pipe 248. Regarding characteristics other than the above differences, the polymerization apparatus 1600 may have the same configuration as the polymerization apparatus 100. Furthermore, within a technically compatible range, the polymerization apparatus 1600 may have the characteristics of various polymerization apparatuses according to other embodiments.

[0214] For example, when the viscosity of the slurry flowing inside the reaction vessel 110 is relatively high, if the serpentine cooling pipes 140 and 150 are arranged in multiple stages in the radial direction of the straight body portion 312, the slurry may remain in the region between the serpentine cooling pipes 140 and 150. An example of a case where the viscosity of the slurry is relatively high is suspension polymerization of vinyl chloride. Even in such a case, the number of stages in the radial direction of the serpentine cooling pipes 140 and 150 changes along the circumferential direction of the straight body portion 312, thereby suppressing the retention of the slurry. As a result, mixing of the slurry is promoted.

[0215] FIG. 17 shows an example of a main part of a polymerization system 1700. In this embodiment, the polymerization system 1700 includes a polymerization device 100 and a controller 1710. In this embodiment, the polymerization system 1700 includes a stirring system 1702. The stirring system 1702 includes a stirring shaft 122, a stirring blade 1722, a stirring blade 1724, a stirring blade 1726, and a power mechanism 126. The polymerization device 100 described in relation to FIG. 17 may have a similar configuration to the polymerization device 100 described in relation to FIG. 1, except that the polymerization device 100 includes a stirring blade 1722, a stirring blade 1724, and a stirring blade 1726 instead of the multiple stirring blades 124.

[0216] In this embodiment, for the purpose of simplifying the explanation, an example of the polymerization system 1700 and the stirring system 1702 will be explained using as an example a case where three stirring blades, namely, the stirring blade 1722, the stirring blade 1724, and the stirring blade 1726, are attached to the stirring shaft 122. However, the polymerization system 1700 and the stirring system 1702 are not limited to this embodiment. In another embodiment, two stirring blades are attached to the stirring shaft 122 of the polymerization system 1700 and the stirring system 1702. In still another embodiment, four or more stirring blades are attached to the stirring shaft 122 of the polymerization system 1700 and the stirring system 1702.

[0217] As described above, the stirring shaft 122 is rotatably disposed inside the reaction vessel 110. In particular, a portion of the stirring shaft 122 is disposed inside the straight body portion 312 of the reaction vessel 110 and configured to be rotatable. The stirring shaft 122 is attached to the reaction vessel 110 such that the extension direction of the stirring shaft 122 and the extension direction of the straight body portion 312 approximately coincide with each other.

[0218] In this embodiment, the three agitating blades, agitating blade 1722, agitating blade 1724, and agitating blade 1726, are attached at different positions in the extension direction of agitating shaft 122. Agitating blade 1722 is attached at the uppermost position of the multiple agitating blades. Agitating blade 1724 is disposed between agitating blade 1722 and agitating blade 1726. Agitating blade 1726 is attached at the lowermost position of the multiple agitating blades.

[0219] In this embodiment, the stirring system 1702 stirs the liquid contained inside the reaction vessel 110 of the polymerization apparatus 100. Specifically, as the stirring shaft 122 rotates, the stirring blade 1722, the stirring blade 1724, and the stirring blade 1726 (which may be simply referred to as multiple stirring blades) attached to the stirring shaft 122 rotate, and as a result, the liquid contained inside the reaction vessel 110 is stirred.

[0220] In this embodiment, the controller 1710 controls the rotation speed of the agitation shaft 122. The controller 1710 controls the rotation speed of the agitation shaft 122, for example, by controlling the output of the power mechanism 126. In this embodiment, the controller 1710 controls the rotation speed of the agitation shaft 122 so that the rotation speed of the agitation shaft 122 satisfies the relationship shown in the following mathematical formula 1. (Formula 1) N(b / d)(L / D) / n≦6.0

[0221] In formula 1, N indicates the number of the multiple impellers attached to the agitation shaft 122. As described above, in this embodiment, N is 3. b indicates the maximum blade width [m] of the multiple impellers. In other words, b indicates the blade width of the impeller with the largest blade width among impeller 1722, impeller 1724, and impeller 1726. d indicates the maximum blade diameter [m] of the multiple impellers. In other words, d indicates the blade diameter of the impeller with the largest blade diameter among impeller 1722, impeller 1724, and impeller 1726.

[0222] L indicates the length [m] in the extension direction of the straight body portion 312 of the reaction vessel 110. D indicates the maximum diameter [m] of multiple inscribed circles that are approximately inscribed in the straight body portion 312 in each of the cross sections formed by multiple planes when the straight body portion 312 is cut along multiple planes that are approximately perpendicular to the extension direction of the straight body portion 312 (the up-down direction in the figure) and pass through the respective mounting positions of the multiple stirring blades. When the reaction vessel 110 has a cylindrical straight body portion 312, D is the inside diameter [m] of the straight body portion 312. n indicates the set value of the rotation speed [rps] of the stirring shaft 122.

[0223] This can suppress the generation of coarse particles, narrow the particle size distribution of the polymer, suppress the occurrence of fish eyes, and suppress the adhesion of scale.

[0224] The parameter expressed by N(b / d)(L / D) / n represents the degree of stirring of the liquid when the liquid is contained in the reaction vessel 110 at approximately the rated capacity of the reaction vessel 110. Therefore, the parameter is sometimes called a stirring parameter.

[0225] In this embodiment, the internal volume of the reaction vessel 110 is 40 to 300 m 3 The ratio (L / D) of the length L of the straight body portion 312 in the extension direction to the diameter D of the inscribed circle of the straight body portion 312 of the reaction vessel 110 may be 1.0 to 3.0. This makes it possible to more reliably obtain the effect of determining the dimensions of the straight body portion 312 of the reaction vessel 110, the dimensions of at least one of the plurality of stirring blades 124, and the set value of the rotation speed of the stirring shaft 122 so as to satisfy the relationship shown in Formula 1.

[0226] It is preferable that the controller 1710 controls the rotation speed of the agitation shaft 122 so that the rotation speed of the agitation shaft 122 satisfies the relationship shown in the following mathematical expression 2. (Formula 2) 0.05≦N(b / d)(L / D) / n≦6.0

[0227] In the formula 2, the definitions of N, b, d, L, D, and n are the same as those in the formula 1. This further suppresses the generation of coarse particles. The particle size distribution of the polymer is further narrowed. The occurrence of fish eyes is further suppressed. In addition, the adhesion of scale is further suppressed.

[0228] When the polymerization apparatus 100 is equipped with one or more serpentine cooling pipes 140 or one or more serpentine cooling pipes 150 (i.e., when the number of series of serpentine cooling pipes in the radial direction of the straight body portion 312 is one or more), it is preferable that the controller 1710 controls the rotation speed of the agitator shaft 122 so that the rotation speed of the agitator shaft 122 satisfies the relationship shown in the following mathematical formula 3. (Formula 3) 0.15≦N(b / d)(L / D) / n≦5.5

[0229] In the formula 3, the definitions of N, b, d, L, D, and n are the same as those in the formula 1. This further suppresses the generation of coarse particles. The particle size distribution of the polymer is further narrowed. The occurrence of fish eyes is further suppressed. In addition, the adhesion of scale is further suppressed.

[0230] When a structure such as a cooling pipe is disposed inside the reaction vessel 110, it becomes more difficult to control the flow state of the liquid contained inside the reaction vessel 110 compared to when no structure is disposed inside the reaction vessel 110. In particular, the serpentine cooling pipe 140 and the serpentine cooling pipe 150 have a complex structure and may hinder the agitation of the liquid in the extension direction of the straight body portion 312. Therefore, when the serpentine cooling pipe 140 or the serpentine cooling pipe 150 is disposed inside the reaction vessel 110, it becomes more difficult to control the agitation state of the liquid.

[0231] Therefore, when a structure such as a cooling pipe is disposed inside the reaction vessel 110, it is preferable to maintain the value of the stirring parameter within a narrower numerical range (i.e., 0.15 to 5.5) compared to when no structure is disposed inside the reaction vessel 110. Furthermore, even when a structure such as a cooling pipe is disposed inside the reaction vessel 110, when the relationship shown in Equation 3 is established, a polymer of the same quality as when no structure such as a cooling pipe is disposed inside the reaction vessel 110 can be produced.

[0232] In this case, the ratio of the maximum value of the distance Pp between two adjacent extension portions 612 to the length L of the body portion 312 in the extension direction may be 0.5 to 15%. C1 The ratio of the distance between the one or more serpentine cooling pipes 140 or the one or more serpentine cooling pipes 150 and the inner wall surface of the straight body portion 312 to the inner diameter D of the straight body portion 312 may be 0.5 to 10%. C2 The proportion may be 1 to 30%.

[0233] When the polymerization apparatus 100 is equipped with one or more serpentine cooling pipes 140 and one or more serpentine cooling pipes 150 (i.e., when the number of series of serpentine cooling pipes in the radial direction of the straight body portion 312 is two or more), it is preferable that the controller 1710 controls the rotation speed of the agitator shaft 122 so that the rotation speed of the agitator shaft 122 satisfies the relationship shown in the following mathematical formula 4. (Formula 4) 0.3≦N(b / d)(L / D) / n≦5.5

[0234] In the formula 4, the definitions of N, b, d, L, D, and n are the same as those in the formula 1. This further suppresses the generation of coarse particles. The particle size distribution of the polymer becomes narrower. Furthermore, the occurrence of fisheyes is further suppressed. In addition, the adhesion of scale is further suppressed. When the relationship shown in the formula 4 is established, the effect of suppressing the occurrence of fisheyes is particularly remarkable.

[0235] As described above, the serpentine cooling pipes 140 and 150 have a complex structure and may hinder the agitation of the liquid in the extension direction of the body portion 312. In particular, when the number of series of serpentine cooling pipes in the radial direction of the body portion 312 is two or more, the degree of the above-mentioned interference becomes significant.

[0236] Therefore, when the number of series of serpentine cooling pipes in the radial direction of the body portion 312 is 2 or more, it is preferable to maintain the value of the stirring parameter within a narrower numerical range (i.e., 0.3 to 5.5) compared to when no structure is disposed inside the reaction vessel 110. Even when the number of series of serpentine cooling pipes in the radial direction of the body portion 312 is 2 or more, when the relationship shown in Equation 4 is established, a polymer of the same quality as when no structure such as cooling pipes is disposed inside the reaction vessel 110 can be produced.

[0237] In this case, the ratio of the maximum value of the distance Pp between two adjacent extension portions 612 to the length L in the extension direction of the body portion 312 may be 0.5 to 15%. The ratio of the minimum value L1 of the distance between the one or more serpentine cooling pipes 140 or the one or more serpentine cooling pipes 150 and the inner wall surface of the body portion 312 to the inner diameter D of the body portion 312 may be 0.5 to 10%. The ratio of the maximum value L2 of the distance between the one or more serpentine cooling pipes 140 or the one or more serpentine cooling pipes 150 and the inner wall surface of the body portion 312 to the inner diameter D of the body portion 312 may be 1 to 30%.

[0238] The polymerization system 1700 may be an example of a reactor. The polymerization system 1700 may be an example of a batch reactor. The stirring system 1702 may be an example of a stirring device. The controller 1710 may be an example of a control unit or a control unit. The stirring blade 1722 may be an example of a first stirring blade. The stirring blade 1724 may be an example of a third stirring blade. The stirring blade 1726 may be an example of a second stirring blade. The power mechanism 126 may be an example of a drive unit.

[0239] 18 shows an example of the mounting position of the impeller on the agitator shaft 122. In this embodiment, an example of the mounting position of the impeller on the agitator shaft 122 is described using as an example a case in which the impeller diameters of the impeller 1722, the impeller 1724, and the impeller 1726 are all di, and the impeller widths of the impeller 1722, the impeller 1724, and the impeller 1726 are all bi. Note that in other embodiments, the impeller diameters of at least two of the impeller 1722, the impeller 1724, and the impeller 1726 may be different. Also, the impeller widths of at least two of the impeller 1722, the impeller 1724, and the impeller 1726 may be different.

[0240] 18, dashed line 1820 indicates the rotation axis of agitator shaft 122. Dashed line 1822 indicates the attachment position of agitator blade 1722 on agitator shaft 122. Dashed line 1824 indicates the attachment position of agitator blade 1724 on agitator shaft 122. Dashed line 1826 indicates the attachment position of agitator blade 1726 on agitator shaft 122.

[0241] In this embodiment, the minimum value of the distance between the attachment positions of the multiple impellers on the agitating shaft 122 and a position on the agitating shaft 122 corresponding to one end of the straight body portion 312 may be 0.1 to 0.45 times the length L in the extension direction of the straight body portion 312. For example, the distance Z between the attachment position of the impeller 1722 on the agitating shaft 122 and a position 1842 corresponding to the upper end 1832 of the straight body portion 312 on the agitating shaft 122 is set to 0.1 to 0.45 times the length L of the straight body portion 312 in the extension direction.

[0242] In this embodiment, the agitator blade 1726 on the agitator shaft 122 is disposed between a first position 1852 of the agitator shaft 122 and a second position 1854 of the agitator shaft 122. The attachment position of the agitator blade 1726 on the agitator shaft 122 may be the midpoint of the blade width of the agitator blade 1726 on the agitator shaft 122. In FIG. 18, the attachment position of the agitator blade 1726 is represented as the intersection of the dashed dotted line 1820 and the dashed dotted line 1826.

[0243] The first position 1852 is located above the second position 1854 when the agitator shaft 122 is attached to the straight body portion 312. The first position 1852 is located above a position 1844 that corresponds to the lower end 1834 of the straight body portion 312 of the agitator shaft 122. The distance between the first position 1852 and a position 1844 that corresponds to the lower end 1834 of the straight body portion 312 of the agitator shaft 122 may be 0.25 times or less the inner diameter D of the straight body portion 312.

[0244] Furthermore, when the agitator shaft 122 is attached to the straight body portion 312, the second position 1854 is located below a position 1844 that corresponds to the lower end 1834 of the straight body portion 312 of the agitator shaft 122. The distance between the second position 1854 and a position 1844 that corresponds to the lower end 1834 of the straight body portion 312 of the agitator shaft 122 may be 0.1 times or less the inner diameter D of the straight body portion 312.

[0245] In this embodiment, the agitating blade 1724 is attached near (N-1) third positions obtained by equally dividing the distance between the attachment position of the agitating blade 1722 and the attachment position of the agitating blade 1726 into (N-1) positions. In this embodiment, since N=3, the agitating blade 1724 is attached at a position which equally divides the distance between the attachment position of the agitating blade 1722 and the attachment position of the agitating blade 1726. In this case, the distance C between the attachment position of the agitating blade 1722 and the attachment position of the agitating blade 1724 is ia is the distance C between the mounting position of the stirring blade 1724 and the mounting position of the stirring blade 1726 ib Approximately equal to.

[0246] The distance between the impeller 1724 and the third position may be 0.5 times or less the ratio (D / N) of the inner diameter D of the body portion 312 to the number N of the impellers. When (N-2) impellers 1724 are arranged between the impeller 1722 and the impeller 1726, the maximum value of the distance between the (N-2) impellers 1724 and the corresponding third position may be 0.5 times or less the ratio (D / N) of the inner diameter D of the body portion 312 to the number N of the impellers.

[0247] The one agitating blade 1724 may be an example of (N-2) third agitating blades. The attachment position of the agitating blade 1722 may be an example of a first attachment position. The attachment position of the agitating blade 1726 may be an example of a second attachment position.

[0248] 19 illustrates an example of a system configuration of a polymerization system 1900. In this embodiment, the polymerization system 1900 includes a polymerization apparatus 100 and a controller 1910. In this embodiment, the controller 1910 has an agitation control unit 1912 and an input control unit 1914. The polymerization apparatus 100 may have a configuration similar to that of the polymerization apparatus 100 described in relation to FIG. 1 or FIG. 17.

[0249] In this embodiment, the polymerization system 1900 may include one or more monomer storage tanks 1922, one or more pumps 1932, and one or more flow meters 1942. The polymerization system 1900 may include one or more aqueous medium storage tanks 1924, one or more pumps 1934, and one or more flow meters 1944. The polymerization system 1900 may include one or more dispersion aid storage tanks 1926, one or more pumps 1936, and one or more flow meters 1946. The polymerization system 1900 may include one or more polymerization initiator storage tanks 1928, one or more pumps 1938, and one or more flow meters 1948. Various storage tanks, pumps, and / or flow meters may be provided for each type of raw material and / or aid.

[0250] In this embodiment, the controller 1910 controls the polymerization system 1900. For example, the controller 1910 controls the input amounts of various raw materials and auxiliary agents. The controller 1910 may control the timing at which various raw materials and / or auxiliary agents are input to the reaction vessel 110. The controller 1910 may control the temperature of the polymerization system. The controller 1910 may control the stirring state of the polymerization system.

[0251] In this embodiment, the stirring control unit 1912 controls the stirring state of the polymerization system. For example, the stirring control unit 1912 controls the rotation speed of the stirring shaft 122. The stirring control unit 1912 may have a configuration similar to that of the controller 1710 described in relation to Fig. 17. For example, the stirring control unit 1912 controls the rotation speed of the stirring shaft 122 so that the rotation speed of the stirring shaft 122 satisfies the relationship shown in the above-mentioned mathematical formula 1.

[0252] In this embodiment, the input control unit 1914 controls the amount (sometimes referred to as the input amount) of various raw materials and auxiliary agents input into the reaction vessel 110, and the timing at which the various raw materials and / or auxiliary agents are input into the reaction vessel 110. For the purpose of simplifying the explanation, in this embodiment, an example of the input control unit 1914 will be explained using as an example a case where the input control unit 1914 controls the mass of the various raw materials and auxiliary agents input into the reaction vessel 110.

[0253] The input control unit 1914 controls, for example, the mass of the monomer input into the reaction vessel 110. The input control unit 1914 may control starting and stopping of the pump 1932 based on the amount of monomer transferred measured by the flow meter 1942 and a preset input amount of monomer.

[0254] The input control unit 1914 controls, for example, the mass of the aqueous solvent input into the reaction vessel 110. The input control unit 1914 may control starting and stopping of the pump 1934 based on the amount of the aqueous medium transferred measured by the flowmeter 1944 and a preset input amount of the aqueous medium.

[0255] The input control unit 1914 controls, for example, the mass of the dispersion aid input into the reaction vessel 110. The input control unit 1914 may control starting and stopping of the pump 1936 based on the amount of the dispersion aid transferred measured by the flowmeter 1946 and a preset input amount of the dispersion aid.

[0256] The input control unit 1914 determines the input amount of the dispersion aid depending on, for example, the state of the cooling tube disposed inside the reaction vessel 110. According to one embodiment, when the number Nc [pieces] of the virtual circles in the reaction vessel 110 is 1, 2, or 3, the input control unit 1914 determines the input amount of the dispersion aid so that the number Nc [pieces] of the virtual circles and the ratio CZ [mg / kg] satisfy the relationship shown in the above formula A1, B1, C1, or D1. According to another embodiment, when the number Nc [pieces] of the virtual circles in the reaction vessel 110 is 4 or more, the input control unit 1914 determines the input amount of the dispersion aid so that the ratio CZ [mg / kg] satisfies the relationship shown in the above formula A2, B2, C2, or D2.

[0257] The input control unit 1914 controls, for example, the mass of the polymerization initiator input into the reaction vessel 110. The input control unit 1914 may control starting and stopping of the pump 1938 based on the amount of the polymerization initiator transferred measured by the flowmeter 1948 and a preset input amount of the polymerization initiator.

[0258] In this embodiment, the monomer storage tank 1922 stores the monomer. The pump 1932 transfers the monomer from the monomer storage tank 1922 to the reaction vessel 110. This causes the monomer to be introduced into the reaction vessel 110. The pump 1932 may be operated in response to an instruction from the introduction control unit 1914. The flow meter 1942 measures the amount of the monomer transferred. The flow meter 1942 may output information indicating the amount of the monomer transferred to the introduction control unit 1914. The monomer may be stored and transferred as a powder, or the monomer may be stored and transferred as a liquid.

[0259] In this embodiment, the aqueous medium storage tank 1924 stores the aqueous medium. The pump 1934 transfers the aqueous medium from the aqueous medium storage tank 1924 to the reaction vessel 110. This causes the aqueous medium to be fed into the reaction vessel 110. The pump 1934 may operate in response to an instruction from the input control unit 1914. The flow meter 1944 measures the amount of the aqueous medium transferred. The flow meter 1944 may output information indicating the amount of the aqueous medium transferred to the input control unit 1914.

[0260] In this embodiment, the dispersion aid tank 1926 stores the dispersion aid. The pump 1936 transfers the dispersion aid from the dispersion aid tank 1926 to the reaction vessel 110. This causes the dispersion aid to be introduced into the reaction vessel 110. The pump 1936 may be operated in response to an instruction from the introduction control unit 1914. The flow meter 1946 measures the amount of the dispersion aid transferred. The flow meter 1946 may output information indicating the amount of the dispersion aid transferred to the introduction control unit 1914. The dispersion aid may be stored and transferred as a powder, or the dispersion aid may be stored and transferred as a liquid.

[0261] In this embodiment, the polymerization initiator storage tank 1928 stores the polymerization initiator. The pump 1938 transfers the polymerization initiator from the polymerization initiator storage tank 1928 to the reaction vessel 110. This causes the polymerization initiator to be introduced into the reaction vessel 110. The pump 1938 may be operated in response to an instruction from the introduction control unit 1914. The flow meter 1948 measures the amount of the polymerization initiator transferred. The flow meter 1948 may output information indicating the amount of the polymerization initiator transferred to the introduction control unit 1914. The polymerization initiator may be stored and transferred as a powder, or the polymerization initiator may be stored and transferred as a liquid.

[0262] The polymerization system 1900 may be an example of a reactor. The polymerization system 1900 may be an example of a batch reactor. The input control unit 1914 may be an example of a dispersion aid input unit. The pump 1936 may be an example of a dispersion aid input unit.

[0263] (An example of another embodiment) In this embodiment, an example of the polymerization system 1900 has been described by taking as an example a case where the input control unit 1914 controls the masses of various raw materials and auxiliary agents input into the reaction vessel 110. However, the polymerization system 1900 is not limited to this embodiment. In other embodiments, the input amounts of various raw materials and auxiliary agents may be in moles or volumes.

[0264] In this embodiment, an example of a method for producing a polymer by a suspension polymerization method using the polymerization system 1900 has been described, taking as an example a case where the raw material and / or auxiliary are transferred by a pump and the amount of the transferred raw material and / or auxiliary is measured by a flow meter. In this case, the above production method includes a raw material input stage of inputting a vinyl monomer, an aqueous medium, a dispersion aid, and a polymerization initiator into the inside of a reactor, and a polymerization stage of polymerizing the vinyl monomer to produce a vinyl polymer. In addition, when the number Nc [pieces] of the multiple imaginary circles is 1, 2, or 3, the raw material input stage includes a stage of inputting a dispersion aid so that the number Nc [pieces] of the multiple imaginary circles and the ratio CZ [mg-dispersion aid / kg-monomer] of the mass of the dispersion aid to the mass of the vinyl monomer satisfy the relationship shown in the above-mentioned formula A1, B1, C1, or D1, or formula A2, B2, C2, or D2. However, the polymerization system 1900 is not limited to this embodiment.

[0265] In another embodiment, first, the raw material and / or auxiliary are weighed so that the relationship shown in the above-mentioned formula A1, B1, C1 or D1, or the formula A2, B2, C2 or D2 is established. At this time, the above-mentioned weighing operation is controlled by, for example, the input control unit 1914. Next, the weighed raw material and / or auxiliary are input into the reaction vessel 110. As a result, the number Nc [pieces] of the above-mentioned imaginary circles and the above-mentioned ratio CZ [mg-dispersion auxiliary / kg-monomer] satisfy the relationship shown in the above-mentioned formula A1, B1, C1 or D1, or the formula A2, B2, C2 or D2. EXAMPLES

[0266] The present invention will be specifically described below with reference to Reference Examples and Examples, but the present invention is not limited to the following Examples.

[0267] (Reference Examples and Comparative Examples) As a reference example, a polymerization example is shown in which the rotation speed of the stirring shaft 122 in the polymerization apparatus 100, the dimension of the straight body part of the reaction vessel 110, the dimension of at least one of the multiple stirring blades 124, and the set value of the rotation speed of the stirring shaft 122 satisfy the relationship shown in the above-mentioned mathematical formula 1. Also, as a reference comparative example, a polymerization example is shown in which the rotation speed of the stirring shaft 122 in the polymerization apparatus 100, the dimension of the straight body part of the reaction vessel 110, the dimension of at least one of the multiple stirring blades 124, and the set value of the rotation speed of the stirring shaft 122 do not satisfy the relationship shown in the above-mentioned mathematical formula 1.

[0268] (Polymerization conditions) In Reference Examples 1 to 13 and Reference Comparative Examples 1 to 5, vinyl chloride polymers were produced using deionized water, vinyl chloride monomer, and commercially available reagents, while varying the presence or absence of a serpentine cooling tube inside the reaction vessel, the arrangement of the serpentine cooling tube, the dimensions of the reaction vessel, and the rotation speed of the stirring shaft. In Reference Examples 1 to 13 and Reference Comparative Examples 1 to 5, the polymerization temperature and the supply temperature of the coolant were the same. The polymerization temperature was set based on the target K value of the polymer.

[0269] (evaluation) (Evaluation of resin particles) The particle size distribution and the number of fish eyes of the produced polymer (sometimes referred to as resin particles) were measured in each of Reference Examples 1 to 10 and Reference Comparative Example 1. As the particle size distribution of the polymer, the mass % of the resin particles passing through a 60 mesh sieve, the mass % of the resin particles passing through a 100 mesh sieve, and the mass % of the resin particles passing through a 200 mesh sieve were measured.

[0270] The number of fish eyes was measured according to the following procedure. First, 100 parts by mass of a sample polymer, 50 parts by mass of bis(2-ethylhexyl) phthalate (DOP), 2.0 parts by mass of a Ba / Zn-based stabilizer, 5.0 parts by mass of epoxidized soybean oil, 0.1 parts by mass of carbon black, and 0.5 parts by mass of titanium dioxide were mixed to obtain a compound. Next, 50 g of the above compound was kneaded in a roll mill at 145° C. for 6 minutes and separated into a sheet having a thickness of 0.3 mm. Thereafter, 100 cm of the above sheet was cut into pieces and kneaded. 2The number of transparent particles in the solution was visually counted to determine the number of fisheyes.

[0271] (Scale rating) In addition, the polymerization test was repeated in each of Reference Examples 1 to 10 and Reference Comparative Example 1. After the polymerization test was completed a predetermined number of times, the surface of the inner wall surface of the reaction vessel was visually observed to confirm the presence or absence of adhesion of scale. In addition, when the serpentine cooling pipe 140 and / or the serpentine cooling pipe 150 were arranged inside the reaction vessel, the surface of the serpentine cooling pipe 140 and / or the serpentine cooling pipe 150 was visually observed to confirm the presence or absence of adhesion of scale.

[0272] (Reference example 1) (Specifications of Polymerization Apparatus 100) In Reference Example 1, vinyl chloride polymer was produced using a polymerization apparatus 100 shown in FIG. 3 The reaction vessel 110 used was as follows. The diameter of the straight body portion 312 of the reaction vessel 110 was 3600 mm, and the length of the straight body portion 312 was 6800 mm. The ratio of the length L of the straight body portion 312 to the diameter D of the straight body portion 312 was 1.9.

[0273] Four serpentine cooling pipes 140, each made of an austenitic stainless steel cylindrical pipe with an outer diameter of 90 mm, were arranged inside the reaction vessel 110. The distance between the center of each of the four serpentine cooling pipes 140 and the central axis of the reaction vessel 110 was 1360 mm. The four serpentine cooling pipes 140 were arranged symmetrically with respect to the central axis of the reaction vessel 110. The number of stages of each of the four serpentine cooling pipes 140 was 12. That is, each of the four serpentine cooling pipes 140 had 12 extensions 612. In each of the four serpentine cooling pipes 140, the distance between adjacent extensions 612 (sometimes referred to as pitch Pp) was 400 mm.

[0274] The distance P between the inner wall surface of the straight body portion 312 and the serpentine cooling pipe 140 with respect to the diameter D of the straight body portion 312 C2The ratio of the pitch Pp to the length L of the body portion 312 was 5.9%.

[0275] Similarly, four serpentine cooling pipes 150, each made of an austenitic stainless steel cylindrical pipe with an outer diameter of 90 mm, were installed inside the reaction vessel 110. The distance between the center of each of the four serpentine cooling pipes 150 and the central axis of the reaction vessel 110 was 1610 mm. The four serpentine cooling pipes 150 were disposed symmetrically with respect to the central axis of the reaction vessel 110. Each of the four serpentine cooling pipes 150 had 12 stages. The pitch Pp of each of the four serpentine cooling pipes 150 was 400 mm.

[0276] The ratio of the distance L1 between the inner wall surface of the body portion 312 and the serpentine cooling pipe 150 to the diameter D of the body portion 312 was 5.3%. The ratio of the pitch Pp to the length L of the body portion 312 was 5.9%.

[0277] Next, the stirring shaft 122 with three paddle blades attached was installed in the reaction vessel 110. The rotation speed of the stirring shaft 122 was determined so as to satisfy the relationship of the above-mentioned mathematical formula 1. In Reference Example 1, the value of the stirring parameter expressed by N(b / d)(L / D) / n was 0.22. The stirring energy applied to the content of the reaction vessel 110 was 80 to 200 kgf m / s m 3 was within the range.

[0278] (Polymerization method) A vinyl chloride polymer was synthesized according to the following procedure. First, 32,900 kg of deionized water, 10.5 kg of partially saponified polyvinyl alcohol with a saponification degree of 80.0 mol%, and 4.5 kg of hydroxypropyl methylcellulose with a methoxy substitution degree of 28.5 mass% and a hydroxypropyl substitution degree of 8.9% were made into an aqueous solution and charged into the reaction vessel 110. Next, 30,100 kg of vinyl chloride monomer was charged into the reaction vessel 110. Thereafter, while stirring the mixed solution with the stirrer 120, polymerization initiator A, polymerization initiator B, and polymerization initiator C were pumped into the reaction vessel 110.

[0279] As polymerization initiator A, an isoparaffin solution containing di-2-ethylhexyl peroxydicarbonate was used. The amount of di-2-ethylhexyl peroxydicarbonate added was 22.1 kg. As polymerization initiator B, an isoparaffin solution containing t-butyl peroxyneodecanate was used. The amount of t-butyl peroxyneodecanate added was 3.2 kg. As polymerization initiator C, an isoparaffin solution containing cumyl peroxyneodecanate was used. The amount of cumyl peroxyneodecanate added was 5.0 kg.

[0280] Next, hot water was passed through the jacket 170 to raise the temperature of the mixed solution inside the reaction vessel 110 to 57° C., thereby initiating polymerization. When the temperature of the mixed solution inside the reaction vessel 110 reached 57° C., the passage of cooling water through the baffle 130, the serpentine cooling tube 140, the serpentine cooling tube 150, and the jacket 170 was started. After that, when the polymerization conversion rate reached 20%, the reflux condenser 180 was operated.

[0281] Under the condition that the temperature of the mixed solution inside the reaction vessel 110 was maintained at 57°C, all cooling was stopped when the pressure inside the reaction vessel 110 dropped by 0.09 MPa compared to the average pressure after the start of polymerization. 18 minutes after all cooling was stopped, an aqueous dispersion of triethylene glycol bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate] (concentration: 40% by mass) sufficient to stop the polymerization reaction was poured into the reaction vessel 110. This terminated the polymerization reaction, and a vinyl chloride polymer was obtained.

[0282] After the polymerization reaction was completed, the particle size distribution of the synthesized polyvinyl chloride resin and the number of fish eyes were measured. In addition, in order to check the adhesion state of scale, the above polymerization test was repeated as one batch. After a predetermined number of polymerization tests were completed, the adhesion state of scale inside the reaction vessel 110 was visually checked. The measurement results of the particle size distribution of the polyvinyl chloride resin, the measurement results of the number of fish eyes, and the confirmation results of the adhesion state of scale are shown in Table 1.

[0283] (Reference examples 2~8) A vinyl chloride polymer was synthesized using a polymerization apparatus similar to the polymerization apparatus 100 shown in FIG. 2. In Reference Examples 2 to 8, a vinyl chloride polymer was synthesized by the same procedure as Reference Example 1, except that the dimensions of the reaction vessel 110, the rotation speed of the stirring shaft 122, and the amount of raw materials charged were different. In Reference Examples 2 to 8, the stoichiometric ratio of each raw material and the reaction temperature were adjusted in the same manner as Reference Example 1. Thereby, based on the experimental results of Reference Examples 1 to 8, the relationship between the dimensions of the reaction vessel, the dimensions of the stirring blade, and the set value of the rotation speed of the stirring shaft, and the relationship between the quality of the produced polymer can be considered.

[0284] The specifications of the polymerization apparatuses in Reference Examples 2 to 8 are summarized in Table 1. Table 1 also shows the results of measuring the particle size distribution of the vinyl chloride resin in Reference Examples 2 to 8, the results of measuring the number of fish eyes, and the results of checking the state of scale adhesion.

[0285] (Reference example 9) A vinyl chloride polymer was synthesized using a polymerization apparatus similar to the polymerization apparatus 100 shown in FIG. 2 except that it does not include the serpentine cooling tube 140 and the serpentine cooling tube 150. In Reference Example 9, a vinyl chloride polymer was synthesized by the same procedure as in Reference Example 1 except that the dimensions of the reaction vessel 110, the presence or absence of the serpentine cooling tube 140 and the serpentine cooling tube 150, the rotation speed of the stirring shaft 122, and the amount of raw materials charged were different. In Reference Example 9, the stoichiometric ratio of each raw material and the reaction temperature were adjusted in the same manner as in Reference Example 1. This allows the influence of structures arranged inside the reaction vessel to be considered.

[0286] The specifications of the polymerization apparatus of Reference Example 9 are summarized in Table 2. Table 2 also shows the results of measuring the particle size distribution of the vinyl chloride resin in Reference Example 9, the results of measuring the number of fish eyes, and the results of checking the state of scale adhesion.

[0287] (Reference examples 10~11) A vinyl chloride polymer was synthesized using a polymerization apparatus similar to the polymerization apparatus 100 shown in FIG. 2 except that it did not include a serpentine cooling pipe 140. In Reference Examples 10 to 11, a vinyl chloride polymer was synthesized by the same procedure as in Reference Example 1 except that the dimensions of the reaction vessel 110, the presence or absence of the serpentine cooling pipe 140, the rotation speed of the stirring shaft 122, and the amount of raw materials charged were different. In Reference Examples 10 to 11, the stoichiometric ratio of each raw material and the reaction temperature were adjusted in the same manner as in Reference Example 1. This allows the influence of structures arranged inside the reaction vessel to be considered.

[0288] The specifications of the polymerization apparatus in Reference Examples 10 to 11 are summarized in Table 2. Table 2 also shows the results of measuring the particle size distribution of the vinyl chloride resin in Reference Examples 10 to 11, the results of measuring the number of fish eyes, and the results of checking the state of scale adhesion.

[0289] (Reference example 12) A vinyl chloride polymer was synthesized using a polymerization apparatus similar to the polymerization apparatus 100 shown in FIG. 2, except that the number of series of serpentine cooling pipes in the radial direction of the reaction vessel 110 was three. In Reference Examples 10 and 11, a vinyl chloride polymer was synthesized by the same procedure as in Reference Example 1, except that the dimensions of the reaction vessel 110, the number of series of serpentine cooling pipes, the rotation speed of the stirring shaft 122, and the amount of raw materials charged were different. In Reference Example 12, the stoichiometric ratio of each raw material and the reaction temperature were adjusted in the same manner as in Reference Example 1. This allows the influence of structures arranged inside the reaction vessel to be considered.

[0290] The specifications of the polymerization apparatus of Reference Example 12 are summarized in Table 2. The measurement results of the particle size distribution of the vinyl chloride resin in Reference Example 12, the measurement results of the number of fish eyes, and the confirmation results of the adhesion state of scale are also shown in Table 2.

[0291] (Reference example 13) A vinyl chloride polymer was synthesized using a polymerization apparatus similar to the polymerization apparatus 100 shown in FIG. 2 except that the number of series of serpentine cooling tubes in the radial direction of the reaction vessel 110 was five. In Reference Example 13, a vinyl chloride polymer was synthesized by the same procedure as in Reference Example 1 except that the dimensions of the reaction vessel 110, the number of series of serpentine cooling tubes, the rotation speed of the stirring shaft 122, and the charged amount of raw materials were different. In Reference Example 13, the stoichiometric ratio of each raw material and the reaction temperature were adjusted in the same manner as in Reference Example 1. This allows the influence of structures arranged inside the reaction vessel to be considered.

[0292] The specifications of the polymerization apparatus of Reference Example 13 are summarized in Table 2. In addition, Table 2 also shows the measurement results of the particle size distribution of the vinyl chloride resin in Reference Example 13, the measurement results of the number of fish eyes, and the confirmation results of the adhesion state of scale.

[0293] (Reference Comparative Example 1) A vinyl chloride polymer was synthesized using a polymerization apparatus similar to the polymerization apparatus 100 used in Reference Example 1, except that the dimensions of the reaction vessel 110 were different. In Reference Comparative Example 1, a vinyl chloride polymer was synthesized by the same procedure as in Reference Example 1, except that the dimensions of the reaction vessel 110, the dimensions of the stirring blade 124, and the rotation speed of the stirring shaft 122 were different. In Reference Comparative Example 1, the stoichiometric ratio of each raw material and the reaction temperature were adjusted in the same manner as in Reference Example 1.

[0294] In Reference Comparative Example 1 and Reference Example 1, the L / D of the reaction vessel 110 is different. Therefore, the flow state inside the reaction vessel 110 is different in Reference Comparative Example 1 and Reference Example 1. As a result, the stirring conditions under which polymerization can be continued are also different in Reference Comparative Example 1 and Reference Example 1. Therefore, the stirring conditions in Reference Comparative Example 1 were determined by adjusting the value of b / d in Formula 1 and the set value of the rotation speed of the stirring shaft. As a result, the value of b / d in Reference Comparative Example 1 was larger than the value of b / d in Reference Example 1. In addition, the value of the stirring parameter in Reference Comparative Example 1 was 6.44.

[0295] The specifications of the polymerization apparatus of Reference Comparative Example 1 are outlined in Table 3. Table 3 also shows the measurement results of the particle size distribution of the polyvinyl chloride resin in Reference Comparative Example 1, the measurement results of the number of fish eyes, and the confirmation results of the state of scale adhesion.

[0296] (Reference Comparative Examples 2 to 5) A vinyl chloride polymer was synthesized using a polymerization apparatus similar to the polymerization apparatus 100 used in Reference Example 1, except that the dimensions of the reaction vessel 110, and the arrangement and pitch width of the serpentine cooling pipe were different. In Reference Comparative Examples 2 to 5, a vinyl chloride polymer was synthesized by the same procedure as Reference Example 1, except that the dimensions of the reaction vessel 110, the arrangement and pitch width of the serpentine cooling pipe, the dimensions of the stirring blade 124, the rotation speed of the stirring shaft 122, and the amount of raw materials charged were different. In Reference Comparative Examples 2 to 5, the stoichiometric ratio of each raw material and the reaction temperature were adjusted in the same manner as in Reference Example 1. In Reference Comparative Examples 2 to 5, the rotation speed of the stirring shaft 122 was determined so that the value of the stirring parameter exceeded 6.

[0297] The specifications of the polymerization apparatuses of Reference Comparative Examples 2 to 5 are summarized in Table 3. Table 3 also shows the results of measuring the particle size distribution of the vinyl chloride resins in Reference Comparative Examples 2 to 5, the results of measuring the number of fish eyes, and the results of checking the state of scale adhesion.

[0298] As shown by the results of Reference Examples 1 to 13, by determining the dimensions of the straight body of the reaction vessel 110, the dimensions of at least one of the plurality of stirring blades 124, and the set value of the rotation speed of the stirring shaft 122 so that the value of the stirring parameter is 6.0 or less, it is possible to suppress the generation of coarse particles and synthesize a vinyl chloride resin having a good particle size distribution. It is also found that the generation of fish eyes is greatly suppressed. Furthermore, the generation of scale is hardly visible to the naked eye.

[0299] On the other hand, as shown by Comparative Examples 1 to 5, when the value of the stirring parameter exceeds 6.0, coarse particles are generated, and a vinyl chloride resin having a relatively wide particle size distribution is synthesized. In addition, many fish eyes are generated, and scales that can be easily confirmed by the naked eye are generated.

[0300] The cause of the above phenomenon is unclear, but the following causes are presumed, for example. In other words, the flow state inside the reaction vessel 110 is affected by the L / D of the reaction vessel 110, the structure and arrangement of the internal structure placed inside the reaction vessel 110, and the like. For example, when the L / D of the reaction vessel 110 is large, it is necessary to increase b in order to ensure the flowability of the fluid inside the reaction vessel 110. On the other hand, when b is large, the magnitude of the stirring energy applied to the raw materials needs to be increased to 80 to 200 kgf m / s m 3 In order to maintain the rotation speed at about the same level, it may become necessary to reduce the set value n of the rotation speed. At this time, if the relationship expressed by the mathematical formula 1 or the like is no longer established, the fluidity of the fluid inside the reaction vessel 110 becomes insufficient, and it is considered that a problem occurs in the polymerization.

[0301] For the same reason, when the influence of the internal structure arranged inside the reaction vessel 110 on the flow state becomes large, it becomes difficult to control the stirring state. For example, when the number of series of the serpentine cooling pipe is two or more, it becomes difficult to control the stirring state. Even in such a case, as shown in Reference Examples 3 to 7, by determining the dimensions of the straight body part of the reaction vessel 110, the dimensions of at least one of the multiple stirring blades 124, and the set value of the rotation speed of the stirring shaft 122 so that the value of the stirring parameter is 0.3 to 5.5, it is found that a high-quality polyvinyl chloride resin can be synthesized even when the number of series of the serpentine cooling pipe is two or more. In particular, it is found that a significant effect can be obtained in suppressing the occurrence of fisheyes.

[0302] [Table 1]

[0303] [Table 2]

[0304] [Table 3]

[0305] Examples and Comparative Examples As an embodiment, a polymerization example is shown in which the number Nc of the virtual circles is 1, 2, or 3, and the number Nc of the virtual circles and the ratio CZ of the mass of the dispersion aid to the mass of the raw material solution [mg-dispersion aid / kg-monomer] satisfy the relationship shown in the above-mentioned formula A1. Also, as a comparative example, a polymerization example is shown in which the number Nc of the virtual circles is 1, 2, or 3, and the number Nc of the virtual circles and the ratio CZ do not satisfy the relationship shown in the above-mentioned formula A1.

[0306] In the examples and comparative examples, the ratio of the mass of the dispersing aid to the mass of the monomer is used as an index to evaluate the physical properties of the resin particles and the amount of scale adhering to the inside of the reactor. Therefore, in the explanation of the examples and comparative examples, specific numerical values ​​of the mass of the monomer and the mass of the dispersing aid are omitted. However, a person skilled in the art who has read the description of this specification can manufacture and use the polymerization apparatus according to this embodiment based on the description of the examples and comparative examples without excessive trial and error. The dispersing aid and the buffering agent may be simply referred to as the aid.

[0307] (Examples 1 to 3) A vinyl chloride polymer was synthesized using a polymerization apparatus configured similarly to the polymerization apparatus used in Reference Example 6, except that the "cooling pipe arrangement" was a "single-layer arrangement." In the above polymerization apparatus, four serpentine cooling pipes arranged in a single layer in the radial direction were disposed inside the reaction vessel 110.

[0308] In Examples 1 to 3, vinyl chloride polymers were produced by varying the amount of dispersion aid added. In Example 1, vinyl chloride polymers were synthesized by the same procedure as in Reference Example 6, except that the composition and amount of the dispersion aid were different, and that commercially available citric acid was added as a buffer. In Examples 2 and 3, vinyl chloride polymers were synthesized by the same procedure as in Reference Example 6, except that the composition and amount of the dispersion aid were different.

[0309] In Examples 1 to 3, the polymerization temperature and the coolant supply temperature were the same. The polymerization temperature was set based on the target K value of the polymer. The target K value of the polymer was determined based on the average degree of polymerization of the target polymer. As a dispersion aid, a mixture of partially saponified polyvinyl alcohol (PVA) and hydroxypropyl methylcellulose (HPMC) was used. The composition and amount of the dispersion aid and the amount of the buffer added in Examples 1 to 3 are shown in Table 4.

[0310] (Comparative Examples 1 to 2) A vinyl chloride polymer was synthesized using the same polymerization apparatus as that used in Example 1. In Comparative Example 1, a vinyl chloride polymer was synthesized in the same procedure as in Example 1, except that the amount of each dispersing agent added was different, and that no buffer agent was added. In Comparative Example 2, a vinyl chloride polymer was synthesized in the same procedure as in Example 3, except that the amount of each dispersing agent added was different, and that commercially available citric acid was added as a buffer agent. The compositions and amounts of dispersing agents added and the amount of buffer agent added in Comparative Examples 1 and 2 are shown in Table 4.

[0311] [Table 4]

[0312] In Table 4, "◯" indicates that the auxiliary was added, and "-" indicates that the auxiliary was not added. The compositions of the partially saponified PVAs were the same in Example 1, Example 2, and Comparative Example 1. The compositions of the partially saponified PVAs were the same in Example 3 and Comparative Example 2.

[0313] (Examples 4 to 6) A vinyl chloride polymer was synthesized using a polymerization apparatus configured similarly to the polymerization apparatus used in Reference Example 6. In the above polymerization apparatus, eight serpentine cooling tubes arranged in two layers in the radial direction were disposed inside reaction vessel 110 as shown in FIG.

[0314] In Examples 4 to 6, vinyl chloride polymers were produced by varying the amount of dispersion aid added. In Examples 4 and 6, vinyl chloride polymers were synthesized by the same procedure as in Reference Example 6, except that the composition and amount of the dispersion aid were different, and that commercially available citric acid was added as a buffer. In Example 5, vinyl chloride polymers were synthesized by the same procedure as in Reference Example 6, except that the composition and amount of the dispersion aid were different.

[0315] In Examples 4 to 6, the polymerization temperature and the coolant supply temperature were the same as in Example 1. As described above, the polymerization temperature was set based on the target K value of the polymer. The composition and amount of the dispersion aid and the amount of the buffer agent in Examples 4 to 6 are shown in Table 5.

[0316] (Comparative Examples 3 to 4) A vinyl chloride polymer was synthesized using the same polymerization apparatus as that used in Example 4. In Comparative Example 3, a vinyl chloride polymer was synthesized in the same procedure as in Example 4, except that the amount of each auxiliary added was different. In Comparative Example 4, a vinyl chloride polymer was synthesized in the same procedure as in Example 6, except that the amount of each dispersion auxiliary added was different and no buffer agent was added. The compositions and amounts of the dispersion auxiliary and the amount of the buffer agent added in Comparative Examples 3 and 4 are shown in Table 5.

[0317] [Table 5]

[0318] In Table 5, "◯" indicates that the auxiliary was added, and "-" indicates that the auxiliary was not added. The compositions of the partially saponified PVAs were the same in Example 4, Example 5, and Comparative Example 3. The compositions of the partially saponified PVAs were the same in Example 6 and Comparative Example 4.

[0319] (Examples 7 to 9) A vinyl chloride polymer was synthesized using a polymerization apparatus configured similarly to the polymerization apparatus used in Reference Example 6, except that the "arrangement of cooling pipes" was a "triple arrangement." In the above polymerization apparatus, 12 serpentine cooling pipes arranged in triple radial layers were disposed inside the reaction vessel 110.

[0320] In Examples 7 to 9, vinyl chloride polymers were produced by varying the amount of dispersion aid added. In Example 7, vinyl chloride polymers were synthesized by the same procedure as in Reference Example 6, except that the composition and amount of dispersion aid added were different. In Examples 8 to 9, vinyl chloride polymers were synthesized by the same procedure as in Reference Example 6, except that the composition and amount of dispersion aid added were different, and commercially available citric acid was added as a buffer.

[0321] In Examples 7 to 9, the polymerization temperature and the coolant supply temperature were the same as in Example 1. As described above, the polymerization temperature was set based on the target K value of the polymer. The composition and amount of the dispersion aid and the amount of the buffer agent in Examples 7 to 9 are shown in Table 6.

[0322] (Comparative Examples 5 to 6) A vinyl chloride polymer was synthesized using the same polymerization apparatus as that used in Example 7. In Comparative Example 5, a vinyl chloride polymer was synthesized by the same procedure as in Example 7, except that the amount of partially saponified PVA added was different. In Comparative Example 6, a vinyl chloride polymer was synthesized by the same procedure as in Example 9, except that the amount of each auxiliary added was different. The compositions and amounts of the dispersion auxiliary and the buffering agent added in Comparative Examples 5 and 6 are shown in Table 6.

[0323] [Table 6]

[0324] In Table 6, "◯" indicates that the auxiliary was added, and "-" indicates that the auxiliary was not added. The compositions of the partially saponified PVAs were the same in Example 7, Example 8, and Comparative Example 5. The compositions of the partially saponified PVAs were the same in Example 9 and Comparative Example 6.

[0325] (evaluation) (Evaluation of resin particles) In each of Examples 1 to 9 and Comparative Examples 1 to 6, the apparent density, particle size distribution, number of fish eyes, and loss on drying of the produced polymer (sometimes referred to as resin particles) were measured. The apparent density of the resin particles was measured in accordance with JIS K7365. As the particle size distribution of the polymer, the mass % of the resin particles passing through a 60 mesh sieve, the mass % of the resin particles passing through a 100 mesh sieve, and the mass % of the resin particles passing through a 200 mesh sieve were measured.

[0326] The number of fish eyes was measured according to the following procedure. First, 100 parts by mass of a sample polymer, 50 parts by mass of bis(2-ethylhexyl) phthalate (DOP), 2.0 parts by mass of a Ba / Zn-based stabilizer, 5.0 parts by mass of epoxidized soybean oil, 0.1 parts by mass of carbon black, and 0.5 parts by mass of titanium dioxide were mixed to obtain a compound. Next, 50 g of the above compound was kneaded in a roll mill at 145° C. for 6 minutes and separated into a sheet having a thickness of 0.3 mm. Thereafter, 100 cm of the above sheet was cut into pieces and kneaded. 2 The number of transparent particles in the solution was visually counted to determine the number of fisheyes.

[0327] The loss on drying was measured in accordance with the test method specified in the 18th Revised Japanese Pharmacopoeia (Ministry of Health, Labour and Welfare Notification No. 220, June 7, 2021). Specifically, 1 g of resin particles was weighed and dried at 105°C for 4 hours. The dried resin particles were placed in a desiccator using silica gel and allowed to cool to room temperature. The mass of the resin particles after cooling was measured, and the ratio of the loss due to drying to the mass of the resin particles before drying was calculated.

[0328] (Scale rating) In each of Examples 1 to 9 and Comparative Examples 1 to 6, after the polymerization test was completed, the surface of the inner wall of the reaction vessel was visually observed to check for the presence or absence of adhesion of scale.

[0329] The evaluation results for Examples 1 to 3 and Comparative Examples 1 and 2 are shown in Table 7. The evaluation results for Examples 4 to 6 and Comparative Examples 3 and 4 are shown in Table 8. The evaluation results for Examples 7 to 9 and Comparative Examples 5 and 6 are shown in Table 9.

[0330] [Table 7]

[0331] [Table 8]

[0332] [Table 9]

[0333] In Tables 7 to 9, "A" for the scale adhesion status indicates that almost no scale was visible to the naked eye. "B" indicates that a small amount of scale (more than in the case of "A") was visible to the naked eye. "C" indicates that a large amount of scale was visible to the naked eye.

[0334] In Examples 1 to 9, the ratio CZ is within the range of values ​​shown by the formula A1, and in Comparative Examples 1 to 6, the ratio CZ is outside the range of values ​​shown by the formula A1. As shown in Tables 7 to 9, in Examples 1 to 9, resin particles having a narrower particle size distribution and fewer fish eyes were produced compared to Comparative Examples 1 to 6. It can be seen that in Examples 1 to 9, the loss on drying of the resin particles is smaller compared to Comparative Examples 1 to 6, and there is less mixing of the raw material solution. In particular, in Examples 1 to 9, resin particles having a loss on drying of 1% or less were obtained. Furthermore, in Examples 1 to 9, adhesion of scale was suppressed compared to Comparative Examples 1 to 6.

[0335] In Examples 1 and 2, the above ratio CZ is within the numerical range indicated by Formula B1, and in Example 3, the above ratio CZ is outside the numerical range indicated by Formula B1. As shown in Table 7, scale adhesion was significantly suppressed in Examples 1 and 2. Scale adhesion was suppressed in Examples 1 and 2 even compared to Example 3. Similarly, as shown in Table 8, scale adhesion was suppressed in Examples 4 and 5 even compared to Example 6. Moreover, as shown in Table 9, scale adhesion was suppressed in Examples 7 and 8 even compared to Example 9.

[0336] In Examples 2 and 3, the ratio CZ is within the numerical range represented by Formula C1, and in Example 1, the ratio CZ is outside the numerical range represented by Formula C1. As shown in Table 7, resin particles with very few fisheyes were produced in Examples 2 and 3. Resin particles with fewer fisheyes were produced in Examples 2 and 3, even compared to Example 1. Similarly, as shown in Table 8, resin particles with fewer fisheyes were produced in Examples 5 and 6, even compared to Example 4. Furthermore, as shown in Table 9, resin particles with fewer fisheyes were produced in Examples 8 and 9, even compared to Example 7.

[0337] In Example 2, the above ratio CZ is within the numerical range indicated by Formula D1, and in Examples 1 and 3, the above ratio CZ is outside the numerical range indicated by Formula D1. As shown in Table 7, in Example 2, resin particles with very few fisheyes were produced, and scale adhesion was significantly suppressed. Similarly, as shown in Table 8, in Example 5, resin particles with very few fisheyes were produced, and scale adhesion was significantly suppressed. Furthermore, as shown in Table 9, in Example 8, resin particles with very few fisheyes were produced, and scale adhesion was significantly suppressed.

[0338] Although the present invention has been described above using the embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It is clear to those skilled in the art that various modifications and improvements can be made to the above embodiments. It is clear from the claims that such modifications and improvements can also be included in the technical scope of the present invention.

[0339] It should be noted that the order of execution of each process, such as operations, procedures, steps, and stages, in the devices, systems, programs, and methods shown in the claims, specifications, and drawings is not specifically stated as "before" or "prior to," and that the process may be performed in any order unless the output of a previous process is used in a subsequent process. Even if the operational flow in the claims, specifications, and drawings is described using "first," "next," and the like for convenience, it does not mean that the process must be performed in this order. [Explanation of symbols]

[0340] 100 Polymerization apparatus, 110 Reaction vessel, 120 Agitator, 122 Agitation shaft, 124 Agitation blade, 126 Power mechanism, 130 Baffle, 132 Body, 134 Support, 140 Serpentine cooling tube, 150 Serpentine cooling tube, 170 Jacket, 172 Flow path, 180 Reflux condenser, 182 Flow path, 232 Baffle, 234 Baffle, 236 Baffle, 238 Baffle, 242 Serpentine cooling tube, 244 Serpentine cooling tube, 246 Serpentine cooling tube, 248 Serpentine cooling tube, 252 Serpentine cooling tube, 254 Serpentine cooling tube, 256 Serpentine cooling tube, 258 Serpentine cooling tube, 312 Straight body portion, 314 First head plate, 316 Second head plate, 318 Base, 332 Refrigerant supply pipe, 334 Refrigerant return pipe, 342 Connection part, 344 Connection part, 346 Connection part, 510 Inner pipe, 512 Inlet, 520 Outer pipe, 522 Outlet, 532 Pipe, 534 Pipe, 542 Flow rate control valve, 544 Flow rate control valve, 552 Pipe, 554 Flow rate control valve, 556 Pipe, 558 Flow rate control valve, 610 Serpentine part, 612 Extension part, 614 Bend part, 702 Supply pipe, 704 Outlet pipe, 710 Serpentine part, 712 Extension part, 714 Bend part, 810 Serpentine part, 812 Serpentine part, 814 Serpentine part, 816 Serpentine part, 822 Connection part, 824 Connection part, 900 Polymerization device, 1000 Polymerization device, 1100 Polymerization apparatus, 1160, serpentine cooling tube, 1200, polymerization apparatus, 1252, serpentine cooling tube, 1300, polymerization apparatus, 1331, baffle, 1332, baffle, 1333, baffle, 1334, baffle, 1335, baffle, 1336, baffle, 1351, serpentine cooling tube, 1352, serpentine cooling tube, 1353, serpentine cooling tube, 1354, serpentine cooling tube, 1355, serpentine cooling tube, 1356, serpentine cooling tube, 1400, polymerization apparatus, 1403, virtual circle, 1404, virtual circle, 1405, virtual circle, 1500, polymerization apparatus, 1600, polymerization apparatus, 1700, polymerization system, 1702, stirring system, 1710, controller, 1722, stirring blade, 1724, stirring blade, 1726 Agitator blade, 1820 dashed line, 1822 dashed line, 1824 dashed line, 1826 dashed line, 1832 upper end, 1834 lower end, 1842 position, 1844 position, 1852 first position, 1854 second position, 1900 polymerization system, 1910 controller, 1912 agitation control section, 1914 input control section, 1922Monomer storage tank, 1924 Aqueous medium storage tank, 1926 Dispersing agent storage tank, 1928 Polymerization initiator storage tank, 1932 Pump, 1934 Pump, 1936 Pump, 1938 Pump, 1942 Flowmeter, 1944 Flowmeter, 1946 Flowmeter, 1948 Flowmeter

Claims

1. A batch-type reactor used for producing a polymer by suspension polymerization using a dispersing aid, comprising: A reactor having a cylindrical straight body portion; A plurality of first cooling pipes arranged inside the reactor for circulating a coolant; a stirring shaft disposed inside the reactor, having a stirring blade attached thereto and configured to be rotatable; Equipped with the plurality of first cooling pipes in a plane substantially perpendicular to the extension direction of the straight body portion are arranged on one or more concentric arcs having a center on a central axis of the stirring shaft, When the number Nc of the concentric circles is 1, 2 or 3, the number Nc of the concentric circles and the ratio CZ [mg-dispersing agent / kg-monomer] of the mass of the dispersing agent to the mass of one or more types of monomers that are raw materials for the polymer satisfy the relationship shown in the following formula A1, (Formula A1) 15Nc+300<CZ<175Nc+2000 The stirring shaft is configured so that a plurality of the stirring blades can be attached at different positions in the extension direction of the stirring shaft, The dimension of the straight body portion, the dimension of at least one of the plurality of stirring blades, and the set value of the rotation speed of the stirring shaft satisfy the relationship shown in the following formula 1. (Formula 1) N(b / d)(L / D) / n≦6.0 (In Formula 1, N indicates the number of the plurality of stirring blades, b represents the maximum value [m] of the blade width of the plurality of stirring blades, d represents the maximum value [m] of the blade diameter of the plurality of stirring blades, L indicates the length [m] of the straight body portion in the extension direction. D is a plane that is approximately perpendicular to the extension direction of the straight body portion, and when the straight body portion is cut along a plurality of planes that pass through the mounting positions of each of the plurality of stirring blades, the maximum value of the diameters of a plurality of inscribed circles that are approximately inscribed in the straight body portion in each of the cross sections along the plurality of planes [m], n indicates the set value of the rotation speed [rps] of the stirring shaft. Reactor.

2. When the number Nc of the concentric circles is 4 or more, the ratio CZ [mg-dispersing agent / kg-monomer] satisfies the relationship shown in the following formula A2: (Formula A2) 15×3+300<CZ<175×3+2000 2. The reactor of claim 1.

3. When the number Nc of concentric circles is 1, 2, or 3, The number Nc [pieces] and the ratio CZ [mg-dispersing aid / kg-monomer] satisfy the relationship shown in the following formula B1. (Formula B1) 15Nc+310<CZ<175Nc+1550 2. The reactor of claim 1.

4. When the number Nc of concentric circles is 1, 2, or 3, The number Nc [pieces] and the ratio CZ [mg-dispersing aid / kg-monomer] satisfy the relationship shown in the following formula C1. (Formula C1) 15Nc+400<CZ<175Nc+1850 2. The reactor of claim 1.

5. When the number Nc of concentric circles is 1, 2, or 3, The number Nc [pieces] and the ratio CZ [mg-dispersing aid / kg-monomer] satisfy the relationship shown in the following formula D1. (Formula D1) 15Nc+400<CZ<175Nc+1550 2. The reactor of claim 1.

6. The reactor further includes a dispersion aid input section for inputting the dispersion aid into the reactor, When the number Nc [pieces] of the concentric circles is 1, 2 or 3, the dispersion aid is added so that the number Nc [pieces] and the ratio CZ [mg-dispersion aid / kg-monomer] satisfy the relationship shown in the above formula A1.

2. The reactor of claim 1.

7. A batch-type reactor used for producing a polymer by suspension polymerization using a dispersing aid, comprising: A reactor having a cylindrical straight body portion; A plurality of first cooling pipes arranged inside the reactor for circulating a coolant; a stirring shaft disposed inside the reactor, having one or more stirring blades attached thereto and configured to be rotatable; A dispersion aid input section for inputting the dispersion aid into the reactor; Equipped with the plurality of first cooling pipes in a plane substantially perpendicular to the extension direction of the straight body portion are arranged on one or more concentric arcs having a center on a central axis of the stirring shaft, When the number Nc [pieces] of the concentric circles is 1, 2 or 3, the dispersion aid is added so that the number Nc [pieces] of the concentric circles and the ratio CZ [mg-dispersion aid / kg-monomer] of the mass of the dispersion aid to the mass of one or more types of monomers that are raw materials for the polymer satisfy the relationship shown in the following mathematical formula A1. (Formula A1) 15Nc+300<CZ<175Nc+2000 The stirring shaft is configured so that a plurality of the stirring blades can be attached at different positions in the extension direction of the stirring shaft, The dimension of the straight body portion, the dimension of at least one of the plurality of stirring blades, and the set value of the rotation speed of the stirring shaft satisfy the relationship shown in the following formula 1. (Formula 1) N(b / d)(L / D) / n≦6.0 (In Formula 1, N indicates the number of the plurality of stirring blades, b represents the maximum value [m] of the blade width of the plurality of stirring blades, d represents the maximum value [m] of the blade diameter of the plurality of stirring blades, L indicates the length [m] of the straight body portion in the extension direction. D is a plane that is approximately perpendicular to the extension direction of the straight body portion, and when the straight body portion is cut along a plurality of planes that pass through the mounting positions of each of the plurality of stirring blades, the maximum value of the diameters of a plurality of inscribed circles that are approximately inscribed in the straight body portion in each of the cross sections along the plurality of planes [m], n indicates the set value of the rotation speed [rps] of the stirring shaft. Reactor.

8. Each of the plurality of first cooling pipes has a meandering portion that extends while repeatedly bending, The meandering portion is A plurality of extension portions extending linearly or curvedly; a plurality of bent portions connecting end portions of two adjacent extension portions among the plurality of extension portions; Including, The reactor of claim 1 or claim 7.

9. Each of the plurality of first cooling pipes is A plurality of ring portions each having a ring shape; One or more connecting portions connecting the plurality of ring portions; Including, The reactor of claim 1 or claim 7.

10. A plurality of baffles extending generally parallel to the extension direction of the straight body portion; a second cooling pipe disposed inside at least one of the plurality of baffles for circulating a coolant; Further comprising: The reactor of claim 1 or claim 7.

11. A step of polymerizing a vinyl monomer using the reaction apparatus according to claim 1 or claim 7 to produce a vinyl polymer. A method for producing a vinyl polymer.

12. A method for producing a vinyl polymer by suspension polymerization using a batch reactor, comprising the steps of: The reaction apparatus comprises: A reactor having a cylindrical straight body portion; A plurality of first cooling pipes arranged inside the reactor for circulating a coolant; a stirring shaft disposed inside the reactor, having a stirring blade attached thereto and configured to be rotatable; Equipped with the plurality of first cooling pipes in a plane substantially perpendicular to the extension direction of the straight body portion are arranged on one or more concentric arcs having a center on a central axis of the stirring shaft, The method comprises: A step of introducing a vinyl monomer, an aqueous medium, and a dispersing agent into the reactor; a polymerization step of polymerizing a vinyl monomer to produce a vinyl polymer; having The raw material input step includes: When the number of concentric circles Nc [pieces] is 1, 2 or 3, adding the dispersion aid so that the number of concentric circles Nc [pieces] and the ratio CZ [mg-dispersion aid / kg-monomer] of the mass of the dispersion aid to the mass of the vinyl monomer satisfy the relationship shown in the following mathematical formula A1: Including, (Formula A1) 15Nc+300<CZ<175Nc+2000 The stirring shaft is configured so that a plurality of the stirring blades can be attached at different positions in the extension direction of the stirring shaft, The dimension of the straight body portion, the dimension of at least one of the plurality of stirring blades, and the set value of the rotation speed of the stirring shaft satisfy the relationship shown in the following formula 1. (Formula 1) N(b / d)(L / D) / n≦6.0 (In Formula 1, N indicates the number of the plurality of stirring blades, b represents the maximum value [m] of the blade width of the plurality of stirring blades, d represents the maximum value [m] of the blade diameter of the plurality of stirring blades, L indicates the length [m] of the straight body portion in the extension direction. D is a plane that is approximately perpendicular to the extension direction of the straight body portion, and when the straight body portion is cut along a plurality of planes that pass through the mounting positions of each of the plurality of stirring blades, the maximum value of the diameters of a plurality of inscribed circles that are approximately inscribed in the straight body portion in each of the cross sections along the plurality of planes [m], n indicates the set value of the rotation speed [rps] of the stirring shaft. method.

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