Extruder and continuous high-shear processing device

Abstract

An extruder 2 comprises a barrel 4 and a screw 5. The barrel 4 includes a supply port 6, a first connection port 8, a second connection port 9, and a discharge port 7. The screw 5 includes, in a flow direction (X direction) along the screw axis, an upstream-side screw part 11 provided on the upstream (X1) side of the first connection port 8, a downstream-side screw part 13 provided on the downstream (X2) side of the second connection port 9, and a dam part 12 provided between the first connection port 8 and the second connection port 9. Thus, melting and kneading before high-shear processing and cooling of resin after the high-shear processing can be performed by the single extruder instead of two extruders provided in a continuous high-shear processing device.

Description

Extruder and Continuous High-Shear Processing Device 【0001】 The present invention relates to an extruder suitable for use in combination with a high-shear processing machine and a continuous high-shear processing device provided with the extruder. 【0002】 A continuous high-shear processing device equipped with a high-shear processing machine used for low-molecular-weighting of resins, etc. has extruders provided on the upstream side and the downstream side of the high-shear processing machine, respectively. After melting and kneading the resin raw material in the extruder provided on the upstream side, a high-shear force is applied to the resin by the high-shear processing machine to generate shear heat, and the resin after high-shear processing at a high temperature is defoamed and cooled in the extruder provided on the downstream side (for example, Patent Document 1). 【0003】 Japanese Patent No. 6949342 【0004】 In the continuous high-shear processing device described in Patent Document 1, if the two extruders can be replaced with one extruder, it becomes possible to reduce the costs required for manufacturing and maintenance management. Also, the continuous high-shear processing device can be made compact and the installation area can be reduced. The present invention aims to provide an extruder capable of performing melting and kneading before high-shear processing and defoaming and cooling of the resin after high-shear processing, in place of the two extruders provided in the continuous high-shear processing device, and a continuous high-shear processing device (resin processing system) provided with the extruder and the high-shear processing machine. 【0005】 The present invention has the following configuration as means for solving the above problems. An extruder comprising a barrel and a screw, wherein the barrel has a supply port, a first connection port, a second connection port, and a discharge port, and the screw has an upstream screw portion provided upstream of the first connection port, a downstream screw portion provided downstream of the second connection port, and a blocking portion provided between the first connection port and the second connection port, in the flow direction along the screw axis. 【0006】By connecting the first and second connection ports, located on both sides of the damming section in the flow direction along the screw axis, to the high-shear processing machine, the resin kneaded in the upstream screw section located upstream of the first connection port can be supplied to the high-shear processing machine from the first connection port, and the resin after high-shear processing can be returned to the downstream screw section from the second connection port for cooling. Therefore, the two extruders that were conventionally provided before and after processing by the high-shear processing machine can be replaced with a single extruder. 【0007】 This is a schematic perspective view showing an extruder and a continuous high-shear processing apparatus according to an embodiment of the present invention. This is a schematic plan view showing the extruder and continuous high-shear processing apparatus of Figure 1. This is a partial cross-sectional view of the high-shear processing apparatus. This is a cross-sectional view of the high-shear processing apparatus showing both the barrel and the screw in cross-section. This is a cross-sectional view along the line F15-F15 in Figure 4. This is a perspective view of the cylindrical body. This is a side view showing the direction of resin flow relative to the screw. This is a partial cross-sectional view of the high-shear processing apparatus showing the direction of resin flow when the screw rotates. This is a cross-sectional view of the part corresponding to Figure 5, showing an example in which multiple passages are arranged in parallel. This is a schematic plan view showing a modified example (part 1) of the extruder and continuous high-shear processing apparatus of Figure 1. This is a schematic plan view showing a modified example (part 2) of the extruder and continuous high-shear processing apparatus of Figure 1. This is a perspective view showing the configuration of the connecting screw section in Figure 11. This is a perspective view (photograph in place of a drawing) showing the state of the narrow-pitch section in the reverse screw section, connecting screw section and upstream screw section after use of the extruder of Example 2. This is a schematic perspective view of a continuous high-shear processing apparatus. This is a cross-sectional view of the first extruder in the continuous high-shear processing apparatus. This is a diagram showing the two screw sections of the first extruder in Figure 15 in a state where they are meshed together. This is a partial cross-sectional view of the second extruder in the continuous high-shear processing apparatus in Figure 14. 【0008】 Embodiments of the present invention will be described below with reference to the drawings as appropriate. The same components will be given the same number, and their descriptions will be omitted as appropriate. Furthermore, XYZ coordinates will be shown in each drawing to indicate direction as appropriate. 【0009】(Continuous High Shear Processing Equipment) Figure 14 is a perspective view showing an overview of a typical continuous high shear processing equipment 100. The continuous high shear processing equipment 100 includes a first extruder 102 for kneading the resin before high shear processing, a high shear processing machine 103 for applying high shear force to the resin, and a second extruder 104 for degassing and cooling the resin after high shear processing, and these are connected in series in this order. 【0010】 The first extruder 102 is used to melt and knead the raw material resin 10. The resin 10 is supplied to the first extruder 102 from the supply port 109, for example, as pellets. The first extruder 102 comprises a barrel 106 and two screw sections 107a and 107b housed inside the barrel 106. The barrel 106 includes a cylinder section 108 having a shape formed by combining two cylinders and a heater (not shown) for melting the resin 10. The resin 10 is continuously supplied to the cylinder section 108 from the supply port 109 near the upstream end of the barrel 106. 【0011】 Figure 15 is a cross-sectional view of the first extruder 102 in the continuous high-shear processing apparatus 100. The screw sections 107a and 107b are housed in the cylinder section 108 in a meshed state and rotate in the same direction by receiving torque transmitted from a motor (not shown). By rotating in the same direction, the resin 10 can be strongly kneaded and melted. 【0012】 Figure 16 shows the state in which the two screw sections 107a and 107b of the first extruder 102 are meshed together. As shown in the figure, the screw sections 107a and 107b are each equipped with a feed section 111, a kneading section 112, and a pumping section 113, which are arranged in a line along the axial direction of the screw sections 107a and 107b. A second supply port for adding fillers such as fibers may be provided between the feed section 111 and the kneading section 112. 【0013】 The feed section 111 has spirally twisted flights 114. The flights 114 of the screw sections 107a and 107b rotate while interlocking with each other, and convey the resin 10 supplied from the supply port 109 toward the kneading section 112. 【0014】 The kneading section 112 has a plurality of discs 115 arranged in the axial direction of the screw sections 107a and 107b. The discs 115 of the screw sections 107a and 107b rotate facing each other and knead the resin 10 sent from the feed section 111. The kneaded resin 10 is fed to the pumping section 113 by the rotation of the screw sections 107a and 107b. 【0015】 The pumping section 113 has spirally twisted flights 116. The flights 116 of the screw sections 107a and 107b rotate while interlocking with each other, pushing the resin 10 out from the discharge port 117 near the downstream end of the barrel 106. 【0016】 The resin 10 supplied to the supply port 109 of the first extruder 102 is melted by the heat of the heater and kneaded. As shown by arrow A in Figure 14, it is continuously supplied from the discharge port 117 of the barrel 106 to the high shear processing machine 103. 【0017】 The resin 10 is supplied stably from the first extruder 102 to the high shear processing machine 103 in a predetermined amount with an appropriate viscosity. This reduces the burden on the high shear processing machine 103, which performs processes such as reducing the molecular weight of the resin 10 following the kneading process in the first extruder 102. 【0018】 Figure 17 is a partial cross-sectional view of the second extruder 104 in the continuous high-shear processing apparatus 100. In the second extruder 104 shown in the figure, gas components contained in the processed resin 10 discharged from the high-shear processing machine 103 are sucked and removed, and the resin 10 is cooled. The second extruder 104 comprises a barrel 122 and a single vent screw section 123 housed in the barrel 122. The barrel 122 includes a straight cylindrical cylinder section 124. The processed resin 10 extruded from the high-shear processing machine 103 is continuously supplied from one end to the cylinder section 124 of the barrel 122. 【0019】The barrel 122 has a vent port 125. The vent port 125 is located in the middle of the barrel 122 and is connected to the vacuum pump 126. Furthermore, the other end of the cylinder portion 124 of the barrel 122 is closed by a head portion 127 equipped with a discharge port 128. 【0020】 The vent screw section 123 has spirally twisted flights 129, which are housed in the cylinder section 124 and rotate in one direction by receiving torque transmitted from a motor (not shown). The flights 129 rotate integrally with the vent screw section 123 and continuously transport the kneaded material supplied to the cylinder section 124 toward the head section 127. When the processed resin 10 is transported to a position corresponding to the vent port 125, it is subjected to vacuum pressure from the vacuum pump 126. That is, by creating negative pressure inside the cylinder section 124 with the vacuum pump 126, gaseous substances and other volatile components contained in the resin 10 are continuously sucked and removed from the kneaded material. After the gaseous substances and other volatile components have been removed, the resin 10 is discharged from the discharge port 128 of the head section 127. As described above, the continuous high-shear processing apparatus 100 includes a first extruder 102 used in a pre-processing step before processing by the high-shear processing machine 103, and a second extruder 104 used in a post-processing step after processing by the high-shear processing machine 103. 【0021】 (Extruder) Figure 1 is a schematic perspective view showing the extruder 2 and continuous high shear processing apparatus 1 according to this embodiment. Figure 2 is a schematic plan view showing the extruder 2 and continuous high shear processing apparatus 1. 【0022】 The continuous high-shear processing apparatus 1 comprises an extruder 2 and a high-shear processing machine 3. The extruder 2 comprises a barrel 4 and a screw 5. 【0023】 Barrel 4, like barrel 106 in the continuous high-shear processing device 100, is equipped with a cylinder section having a shape combining two cylinders and a heater for melting the resin 10 (see Figures 14 and 15). The resin 10 is continuously supplied to the cylinder section inside the barrel from a supply port 6 near the upstream end of barrel 4. 【0024】The barrel 4 is equipped with a supply port 6, a discharge port 7, a first connection port 8, and a second connection port 9. The supply port 6 is located near the upstream end (X1 side end) in the flow direction of the resin 10 along the axial direction (X direction) of the screw 5, and the resin 10 is supplied into the barrel 4 from here. The discharge port 7 is located in the head section that closes the downstream end (X2 side end) in the flow direction of the barrel 4. The discharge port 7 located in the head section can have a structure similar to, for example, the discharge port 128 located in the head section 127 of a continuous high shear processing device 100 (see Figure 17). 【0025】 The first connection port 8 and the second connection port 9 are provided between the supply port 6 and the discharge port 7 of the barrel 4, and connect the inside and outside of the barrel 4. The first connection port 8 is provided on the upstream side and the second connection port 9 is provided on the downstream side in the flow direction of the resin 10 (from X1 to X2, as appropriate, referred to as "flow direction") along the axis (X direction) of the screw 5. 【0026】 The barrel 4 is configured such that the first barrel section 4A upstream of the first connection port 8 and the second barrel section 4B downstream of the second connection port 9 can be set to different temperatures in the flow direction. For example, the temperature of the upstream first barrel section 4A can be set to be above the melting point of the resin 10, and the temperature of the downstream second barrel section 4B can be set to be below the melting point of the resin 10. By controlling the temperature of the barrel 4 in this way, the kneading of the resin 10 in the first barrel section 4A before high shear processing and the cooling of the resin 10 in the second barrel section 4B after high shear processing can be performed efficiently. 【0027】 Since the resin 10 has reached a high temperature after high shear processing, it can be efficiently cooled by setting the temperature of the second barrel section 4B lower than its melting point. If the resin 10 is polypropylene with a melting point of approximately 160°C, for example, it is preferable to set the temperature of the first barrel section 4A for kneading the resin 10 to 180°C or more and 210°C or less, and the temperature of the second barrel section 4B for cooling the resin 10 to 120°C or more and less than 160°C. 【0028】The temperature of the second barrel section 4B is preferably about 40 to 70°C lower than the temperature of the first barrel section 4A. As the amount of resin 10 extruded increases, the cooling efficiency of the second barrel section 4B decreases, so the temperature of the second barrel section 4B should be set according to the amount of extrusion. 【0029】 The screw 5 is equipped with two screws 5a and 5b, and like the screw sections 107a and 107b, they are housed in the cylinder section 108 in a state where they are meshed with each other, and are rotated in the same direction by receiving torque transmitted from a motor (not shown) (see Figures 15 and 16). 【0030】 The screw 5 has an upstream screw section 11, a blocking section 12, and a downstream screw section 13, which differs from the screw section 107 of the continuous high shear processing device 100 (see Figure 14). 【0031】 The upstream screw section 11 is provided upstream of the first connection port 8, and the downstream screw section 13 is provided downstream of the second connection port 9. Here, "provided upstream" means that the center of the flow direction of the upstream screw section 11 is located upstream of the first connection port 8. Also, "provided downstream" means that the center of the flow direction of the downstream screw section 13 is located downstream of the second connection port 9. The damming section 12 is provided between the first connection port 8 and the second connection port 9 in the flow direction. 【0032】 With the above configuration, the resin 10 melted and kneaded in the upstream screw section 11 can be blocked by the blocking section 12 and supplied to the high shear processing machine 3 connected to the first connection port 8 located upstream of the blocking section 12. Furthermore, the processed resin 10 can be supplied into the barrel 4 from the high shear processing machine 3 connected to the second connection port 9 located downstream of the blocking section 12. In other words, by providing the blocking section 12 between the first connection port 8 and the second connection port 9, it becomes possible to transfer the resin 10 before and after processing between the barrel 4 and the high shear processing machine 3 connected to it. 【0033】The upstream screw section 11, like the screw section 107 of the continuous high-shear processing device 100, melts and kneads the resin 10 before processing by the high-shear processing machine 3. For this reason, it can be configured in the same way as the screw section 107 (see Figure 16). 【0034】 The configuration of the downstream screw section 13 is not particularly limited, but when cooling and degassing the resin 10 after processing by the high-shear processing machine 3, for example, the screw section 107 can be configured with a feed section 111 or a pumping section 113. Also, when adding additives such as fillers to the resin 10 after processing by the high-shear processing machine 3, the screw section 107 can be configured to include a feed section 111, a kneading section 112, and / or a pumping section 113 (see Figure 16). In this case, a supply port for additives (not shown) is provided in the part of the barrel 4 that has the downstream screw section 13. 【0035】 The upstream screw section 11 and the downstream screw section 13 have the same screw direction. Therefore, by rotating in the same direction, the resin 10 before and after processing by the high shear processing machine 3 is conveyed from the X1 direction to the X2 direction. In the present invention, when the screws rotate in the same direction, the conveying direction in the screw axis direction is the same, which is referred to as having the same screw direction. Conversely, when the screws rotate in the same direction, the conveying direction in the screw axis direction is opposite, which is referred to as having the opposite screw direction. 【0036】 The blocking portion 12 only needs to be able to block the flow of resin 10 between the upstream screw portion 11 and the downstream screw portion 13. For example, the blocking portion 12 can be configured as a convex portion protruding from the shaft of a screw 5 that is formed to seal the upstream and downstream sides, with a small clearance that allows it to slide between it and the cylinder portion inside the barrel 4. 【0037】 The extruder 2 is equipped with a vent port 14 downstream of the damming section 12. The vent port 14 can be configured, for example, in the same way as the vent port 125 in the second extruder 104 (see Figure 17). 【0038】By connecting the first connection port 8 and the second connection port 9, which are provided on both sides of the damming portion 12 in the axial direction (flow direction) of the screw 5, to the high shear processing machine 3, the extruder 2 can perform both the melting and kneading of the resin 10 before processing and the cooling of the resin 10 after processing, which are performed by the high shear processing machine 3. 【0039】 (High Shear Processing Machine) Figure 3 is a partial cross-sectional view of the high shear processing machine 3. Figure 4 is a cross-sectional view of the high shear processing machine 3 showing both the barrel 20 and the screw 21 in cross-section. As shown in these figures, the high shear processing machine 3 is a single-screw extruder and comprises a barrel 20 and a single screw 21. The screw 21 can reduce the molecular weight by applying a shearing action to the resin supplied from the extruder 2. The barrel 20 is a straight cylindrical shape and is arranged horizontally. The barrel 20 is divided into a plurality of barrel elements 31. 【0040】 Each barrel element 31 has a cylindrical through hole 32. The barrel elements 31 are integrally joined by bolts so that their respective through holes 32 are coaxially continuous. The through holes 32 of the barrel elements 31 cooperate with each other to define a cylindrical cylinder portion 33 inside the barrel 20. The cylinder portion 33 extends in the axial direction of the barrel 20. 【0041】 A supply port 34 is formed at one end of the barrel 20 along its axial direction. The supply port 34 is in communication with the cylinder section 33, and the resin molten by the extruder 2 is continuously supplied to the supply port 34 from the first connection port 8. 【0042】 The barrel 20 is equipped with a heater (not shown). The heater adjusts the temperature of the barrel 20 as needed. The barrel 20 is equipped with a refrigerant passage 35 arranged to surround the cylinder section 33. When the temperature of the barrel 20 exceeds a predetermined upper limit, the refrigerant flows along the refrigerant passage 35, forcibly cooling the barrel 20. For example, water or oil can be used as the refrigerant. 【0043】The other end along the axial direction of the barrel 20 is closed by the head portion 36. The head portion 36 has a discharge port 36a. The discharge port 36a is located on the opposite side along the axial direction of the barrel 20 with respect to the supply port 34 and is connected to the second connection port 9 of the extruder 2. 【0044】 The screw 21 has a linear axis along the resin conveyance direction and includes a screw body 37. The screw body 37 is composed of a single rotary shaft 38 and a plurality of cylindrical barrels 39. 【0045】 The rotary shaft 38 includes a first shaft portion 40 and a second shaft portion 41. The first shaft portion 40 is located at the proximal end of the rotary shaft 38 on the side of one end of the barrel 20. The first shaft portion 40 includes a joint portion 42 and a stopper portion 43. The joint portion 42 is connected to a drive source such as a motor via a coupling (not shown). The stopper portion 43 is provided coaxially with the joint portion 42. The stopper portion 43 has a larger diameter than the joint portion 42. 【0046】 The second shaft portion 41 extends coaxially from the end face of the stopper portion 43 of the first shaft portion 40. The second shaft portion 41 has a length extending over substantially the entire length of the barrel 20 and has a tip facing the head portion 36. A straight axis O1 passing through the first shaft portion 40 and the second shaft portion 41 coaxially extends horizontally in the axial direction of the rotary shaft 38. 【0047】 The conveying portion 81 and the barrier portion 82 may be configured such that only one set is arranged or a plurality of sets are arranged. In either case, by passing the resin through the passage 88 immediately after reducing the molecular weight of the resin, it is possible to suppress excessive progress of thermal deterioration of the resin. The supply port 34 of the barrel 20 is open toward the conveying portion 81 arranged on the proximal end side of the screw body 37. 【0048】Each conveying section 81 has a spiral flight 84. The flight 84 projects from the outer peripheral surface along the circumferential direction of the cylindrical body 39 toward the conveying path 53. When the screw 21 rotates counterclockwise (leftward) as viewed from the proximal end of the screw body 37, the flight 84 is twisted so as to convey the raw material from the proximal end to the distal end of the screw body 37. That is, the flight 84 is twisted to the right in the same manner as a right-handed screw. 【0049】 Each barrier section 82 has a spiral flight 86. The flight 86 projects from the outer peripheral surface along the circumferential direction of the cylindrical body 39 toward the conveying path 53. When the screw 21 rotates counterclockwise (leftward) as viewed from the proximal end of the screw body 37, the flight 86 is twisted so as to convey the resin from the distal end to the proximal end of the screw body 37. That is, the flight 86 is twisted to the left in the same manner as a left-handed screw and forms a reverse screw in the opposite direction to the flight 84. 【0050】 The twist pitch of the flight 86 of each barrier section 82 is set to be the same as or smaller than the twist pitch of the flight 84 of the conveying section 81. Further, a slight clearance is ensured between the tops of the flights 84 and 86 and the inner peripheral surface of the cylinder section 33 of the barrel 20. 【0051】 The clearance between the outer diameter portion of the barrier section 82 (the tops of the flights 84 and 86) and the inner peripheral surface of the cylinder section 33 is preferably set in the range of 0.1 mm or more and 2 mm or less. More preferably, the clearance is set in the range of 0.1 mm or more and 0.7 mm or less. Thereby, it is possible to restrict the resin from passing through and being conveyed through the clearance. 【0052】The screw body 37 has a plurality of passages 88 that extend in the axial direction of the screw body 37 as screw elements. The passages 88 are formed in the cylindrical bodies 39 of both conveying sections 81, straddling the barrier section 82 of each unit, where one barrier section 82 and two conveying sections 81 flanking the barrier section 82 are considered as one unit. In this case, the passages 88 are aligned in a line at predetermined intervals (for example, equal intervals) along the same straight line in the axial direction of the screw body 37. The passages 88 are provided in the barrier section 82 flanked by the conveying sections 81. 【0053】 Each cylindrical body 39 is configured such that a second shaft portion 41 passes through it coaxially. The second shaft portion 41 is a solid cylindrical shape with a smaller diameter than the stopper portion 43. 【0054】 Figure 5 is a cross-sectional view taken along the line F15-F15 in Figure 4. As shown in the figure, a pair of keys 45a and 45b are attached to the outer circumferential surface of the second shaft portion 41. The keys 45a and 45b extend in the axial direction of the second shaft portion 41 at a position offset by 180° in the circumferential direction of the second shaft portion 41. 【0055】 Figure 6 is a perspective view of the cylindrical body 39. As shown in the figure, a pair of key grooves 49a and 49b are formed on the inner circumferential surface of the cylindrical body 39. The key grooves 49a and 49b extend in the axial direction of the cylindrical body 39 at positions offset by 180° in the circumferential direction of the cylindrical body 39. 【0056】 The cylindrical body 39 is inserted onto the second shaft portion 41 from the direction of the tip of the second shaft portion 41, with the keyways 49a and 49b aligned with the keys 45a and 45b of the second shaft portion 41. The first collar 44 is interposed between the cylindrical body 39 that was initially inserted onto the second shaft portion 41 and the end face of the stopper portion 43 of the first shaft portion 40. Furthermore, after all the cylindrical bodies 39 have been inserted onto the second shaft portion 41, a fixing screw 52 is screwed into the tip surface of the second shaft portion 41 via the second collar 51 (see Figures 3 and 4). This screwing tightens all the cylindrical bodies 39 in the axial direction of the second shaft portion 41 between the first collar 44 and the second collar 51, causing the end faces of adjacent cylindrical bodies 39 to be in close contact without any gaps. 【0057】The passage 88 is located inside the cylindrical body 39 at an eccentric position from the axis O1 of the rotating shaft 38. In other words, the passage 88 is off-axis from the axis O1 and revolves around the axis O1 when the screw body 37 rotates. 【0058】 The passage 88 is, for example, a hole with a circular cross-sectional shape. The passage 88 is configured as a hollow space that allows only the flow of resin. The wall surface 89 of the passage 88 revolves around the axis O1 without rotating on its own axis when the screw body 37 rotates. 【0059】 When the passage 88 is a hole with a circular cross-sectional shape, the diameter of the circle may be, for example, about 1 to 5 mm. The length of the passage 88 (length L2, see Figure 7) may be, for example, about 15 to 90 mm. From the viewpoint of allowing the resin to pass through smoothly and increasing the filling rate in these conveying sections 81, the diameter of the circle in the cross-section of the passage 88 is preferably 1 to 3 mm, and the length of the passage 88 is preferably 40 to 60 mm. 【0060】 Figure 7 is a side view showing the direction of resin flow relative to the screw. As shown in the figure, the screw 21 has, as a screw element, a plurality of transport sections 81 for transporting resin and a plurality of barrier sections 82 for restricting the flow of resin. Specifically, a plurality of transport sections 81 are arranged at the base end of the screw body 37 corresponding to one end of the barrel 20, and a plurality of transport sections 81 are arranged at the tip of the screw body 37 corresponding to the other end of the barrel 20. Furthermore, between these transport sections 81, the transport sections 81 and barrier sections 82 are arranged alternately in the axial direction from the base end to the tip of the screw body 37. The number of times processes such as molecular weight reduction by the high shear processing machine 3 are performed is determined by the number of sets of transport sections 81 and barrier sections 82 arranged as one unit. 【0061】 As shown by arrow C in Figure 7, the resin supplied to the high-shear processing machine 3 is fed into the outer surface of the conveying unit 81 located on the base end side of the screw body 37. At this time, when the screw 21 rotates counterclockwise to the left as viewed from the base end of the screw body 37, the flights 84 of the conveying unit 81 continuously convey the resin toward the tip of the screw body 37, as shown by the solid arrows in the figure. 【0062】 The conveying section 81 and the barrier section 82 are arranged alternately in the axial direction of the screw body 37, and the passage 88 is provided at intervals in the axial direction of the screw body 37. As a result, the resin introduced into the screw body 37 from the supply port 34 is subjected to intermittent and repeated shearing action as it is conveyed from the base end to the tip of the screw body 37, and its molecular weight is reduced. 【0063】 Figure 8 is a partial cross-sectional view of a high-shear processing machine 3 showing the flow direction of resin when the screw 21 rotates. As shown in the figure, each passage 88 has an inlet 91, an outlet 92, and a passage body 93. The inlet 91 and the outlet 92 are connected by the passage body 93 and are located close to both sides of a single barrier section 82. Alternatively, in a transport section 81 adjacent to two adjacent barrier sections 82, the inlet 91 opens on the outer circumferential surface near the downstream end of the transport section 81, and the outlet 92 opens on the outer circumferential surface near the upstream end of the transport section 81. The inlet 91 and the outlet 92, which are open on the outer circumferential surface of the same transport section 81, are not connected by the passage body 93. The inlet 91 is connected to the outlet 92 of the adjacent downstream transport section 81 via the barrier section 82, and the outlet 92 is connected to the inlet 91 of the adjacent upstream transport section 81 via the barrier section 82. 【0064】 When passing through passage 88, no shear force is applied to the resin by the screw 21. To enhance the cooling effect when passing through passage 88, a refrigerant passage (not shown) extending coaxially along the axis O1 of the rotating shaft 38 may be formed inside the rotating shaft 38. When a refrigerant passage is formed, one end may be connected to an outlet pipe, and the other end may be sealed liquid-tightly at the tip of the rotating shaft 38. A refrigerant introduction pipe may be inserted coaxially inside the refrigerant passage. This allows the refrigerant to circulate along the axial direction of the rotating shaft 38, thereby improving the cooling efficiency when passing through passage 88 using the refrigerant. 【0065】Figure 8 shows the resin occupancy rate in the portion of the screw body 37 corresponding to the conveying section 81 as a gradient (shade). That is, in the conveying section 81, the darker the color, the higher the occupancy rate. In the conveying section 81, the occupancy rate increases as it approaches the barrier section 82, reaching 100% just before the barrier section 82. In this way, a high shear force is applied to the resin, which has an occupancy rate of approximately 100% near the resin reservoir R, by the rotation of the screw 21. This makes it possible to reduce the molecular weight of the resin. 【0066】 In the resin reservoir R, the pressure increases due to the damming of the flow. The resin, now under increased pressure, flows continuously into the passage 88 from the inlet 91 opened on the outer surface of the conveying section 81, as shown by the dashed arrows in Figure 8, and flows continuously within the passage 88. The filling length, which is the length over which the resin fills the passage along the conveying direction, is determined by the positional relationship between the passage 88 and the barrier section 82. 【0067】 The length L2 of the passage 88 shown in Figure 8 (see Figure 7) needs to be greater than the length L1 of the barrier portion 82 that the passage 88 straddles. However, from the viewpoint of reducing the flow resistance when the resin passes through the passage 88, it is preferable that the length L2 is twice or less the length L1 of the barrier portion 82 that the passage 88 straddles, more preferably 1.5 times or less, and even more preferably 1.3 times or less. 【0068】 Conditions for reducing molecular weight include the rotational speed of the screw body 37, the inner diameter and distance of the passage 88, and the number of times shear action is applied. The number of times the conveyance is limited (number of resin reservoirs R) is determined by the number of barrier sections 82 in the high-shear processing machine 3 where the passage 88 between the screw bodies 37 is provided. 【0069】The screw 21 rotates in response to torque from the drive source. The optimal rotational speed of the screw 21 for low molecular weight production varies depending on the outer diameter of the screw 21. Generally, the optimal rotational speed tends to increase as the outer diameter of the screw 21 decreases. When using a screw 21 with an outer diameter of 30 mm to 50 mm and a flight height 84, i.e., groove depth of 2 mm to 4 mm, a low viscosity resin that produces a high-strength molded product can be obtained by rotating the screw 21 at a speed of 1000 rpm to 3600 rpm. From the viewpoint of increasing the strength of the molded product, the rotational speed of the screw 21 is preferably 1000 rpm to 3000 rpm, and more preferably 1500 rpm to 3000 rpm. 【0070】 Furthermore, by setting the shear rate to 850 ( / sec) or more and 3000 ( / sec) or less, a low-viscosity resin that produces a molded product with high strength can be obtained. From the viewpoint of increasing the strength of the molded product, the shear rate of the screw 21 is preferably 850 ( / sec) or more and 2500 ( / sec) or less, and more preferably 1250 ( / sec) or more and 2500 ( / sec) or less. 【0071】 Figure 9 is a cross-sectional view of the portion corresponding to Figure 5, showing an example in which multiple passages are arranged in parallel. As shown in the figure, a configuration in which multiple passages 88 are arranged parallel and evenly inside the screw body 37 is preferred. In this case, the inlets 91 and outlets 92 (see Figure 8) of the passages 88 are also evenly provided on the outer circumferential surface of the screw body 37. 【0072】 Figure 9 shows an example in which four passages 88a, 88b, 88c, and 88d are provided in parallel inside the screw body 37. As shown in the figure, the even arrangement of multiple passages 88 means that the angle between the axis (center point) O1 of the cross-section of the screw body 37 and the line connecting adjacent passages 88 is equal. The angle between O1 and the line connecting adjacent passages 88 is 90° when there are four passages 88, and 180° when there are two passages 88. Note that D1 indicates the outer diameter of the screw body 37. 【0073】(Modified Version) Figure 10 is a schematic plan view showing a modified version (version 1) of the extruder 2 and the continuous high shear processing apparatus 1. The extruder 2 shown in the figure is equipped with an upstream screw section 11 and a downstream screw section 13 and a reverse screw section 15 with the screw direction opposite as a damming section 12. The flight pitch of the reverse screw section 15 is preferably set to be smaller than the pitch of the upstream screw section 11 and the downstream screw section 13, but it may be about the same. 【0074】 The reverse screw section 15 can have a configuration similar to, for example, the barrier section 82 in the high shear processing machine 3 (see Figure 8). However, the flight pitch of the reverse screw section 15 may be similar to that of the upstream screw section 11 and the downstream screw section 13, and the flights do not have to be in a continuous, dense configuration as shown in Figure 8 (see Figure 13). By using the reverse screw section 15, the resin on its upstream side can be effectively blocked, thereby facilitating the supply of resin to the high shear processing machine 3 via the first connection port 8 and the supply of processed resin to the extruder 2 via the second connection port 9. 【0075】 The third barrel section 4C, which is provided with the reverse screw section 15, can be set to a different temperature from the first barrel section 4A upstream of the first connection port 8 and the second barrel section 4B downstream of the second connection port 9. From the viewpoint of ensuring sufficient blocking ability of the reverse screw section 15, it is preferable to set the temperature of the third barrel section 4C to approximately the melting point of the resin, for example, to set the temperature of the third barrel section 4C in a range from a temperature 5°C lower than the melting point of the resin to a temperature 5°C higher than the melting point of the resin. 【0076】Figure 11 is a schematic plan view showing a modified example (part 2) of the extruder 2 and the continuous high-shear processing apparatus 1. Figure 12 is a perspective view showing the configuration of the connecting screw section 16 in Figure 11. The extruder 2 shown in Figure 11 is equipped with a connecting screw section 16 between the upstream screw section 11 and the reverse screw section 15. The connecting screw section 16 has a forward screw section (first screw section) 16A on the upstream side that has the same screw direction as the upstream screw section 11, and a reverse screw section (second screw section) 16B on the downstream side that has the opposite screw direction to the upstream screw section 11, i.e., the same screw direction as the reverse screw section 15. 【0077】 The pitch of the positive screw section 16A is the same as that of the reverse screw section 16B, and is wider than the pitch of the upstream screw section 11. Furthermore, the boundary section 16C between the positive screw section 16A and the reverse screw section 16B is located near the center of the first connection port 8 in the flow direction and overlaps with the first connection port 8 in the flow direction. 【0078】 The pitch of the forward screw section 16A and the reverse screw section 16B is preferably, for example, about 1.5 to 3 times the pitch of the upstream screw section 11 and about 1.5 to 3 times the pitch of the reverse screw section 15. 【0079】 With the above configuration, the connecting screw portion 16 forms a flow of the resin, which has been melted and kneaded by the upstream screw portion 11, to the first connection port 8 in the Y2 direction, while also weakening the flow of resin towards the X2 side. Therefore, the resin can be supplied smoothly to the high shear processing machine 3, and the blocking of the resin by the reverse screw portion 15 can be made more reliable. 【0080】 Furthermore, the modified configuration shown in Figure 11 includes a narrow-pitch section 17 on the connecting screw section 16 side of the upstream screw section 11, where the flight pitch is narrower than that of the other parts of the upstream screw section 11. By providing the narrow-pitch section 17 in this way, the effect of filling the region between the narrow-pitch section 17 and the reverse screw section 15 with resin is improved. Therefore, the supply of resin to the high-shear processing machine 3 by the connecting screw section 16 via the first connection port 8 can be made smoother. 【0081】(Example 1) A single pipe was attached to the first connection port 8 of the extruder 2 shown in Figure 10, and the barrel temperature of the first barrel section 4A and the second barrel section 4B was set to 195°C. Polypropylene (F704NP, manufactured by Prime Polymer) was melted and kneaded under the following conditions, and it was checked whether polypropylene came out of the single pipe attached to the first connection port 8 and the discharge port 7 of the barrel 4. 【0082】 (Operating conditions) Extrusion rate 5 kg / hour, rotation speed 200 rpm Extrusion rate 10 kg / hour, rotation speed 200 rpm Extrusion rate 20 kg / hour, rotation speed 300 rpm 【0083】 Under all operating conditions, it was confirmed that resin was discharged from the single pipe attached to the first connection port 8. No resin leakage was observed from the discharge port 7 at an extrusion rate of 5 kg / hour, but it occurred at an extrusion rate of 20 kg / hour. From these results, it was found that by configuring the damming section 12 with the reverse screw section 15, resin can be dammed within the barrel 4 when the extrusion rate is small. 【0084】 (Example 2) With the extruder 2 shown in Figure 11, the barrel temperature of the first barrel section 4A and the second barrel section 4B was set to 195°C, and polypropylene (F704NP, manufactured by Prime Polymer) was melt-kneaded under the following conditions, and it was checked whether polypropylene came out of the first connection port 8 and the discharge port 7 of the barrel 4. 【0085】 (Operating conditions) Extrusion rate 5 kg / hour, rotation speed 100 rpm, 200 rpm Extrusion rate 10 kg / hour, rotation speed 100 rpm, 200 rpm Extrusion rate 20 kg / hour, rotation speed 200 rpm, 300 rpm 【0086】 Under all operating conditions, it was confirmed that resin was discharged from the first connection port 8. No resin leakage occurred from the discharge port 7, regardless of the extrusion rate conditions of 5, 10, or 20 kg / hour. Figure 13 is a photographic representation of the state of the reverse screw section 15, the connecting screw section 16, and the narrow-pitch section 17 of the upstream screw section 11 of the extruder 2 used in this embodiment. As shown in the figure, almost no resin reached the reverse screw section 15. 【0087】From these results, it was found that by configuring the damming section 12 with an inverted screw section 15, providing a connecting screw section 16 between it and the upstream screw section 11, and providing a narrow-pitch section 17 on the connecting screw section 16 side of the upstream screw section 11, the resin can be dammed within the barrel 4 even when the extrusion amount is increased. 【0088】 (Example 3) The configuration of the continuous high-shear processing apparatus 1, which is equipped with an extruder 2 and a high-shear processing machine 3 as shown in Figure 11, was changed so that the vent port 14 was placed directly above the reverse screw section 15. Polypropylene (F704NP, manufactured by Prime Polymer, melt flow rate (MFR) = 7, zero shear viscosity: 5182 Pa.S) was melted and kneaded under the following conditions, and after being reduced in molecular weight by the high-shear processing machine 3, the resin after being reduced in molecular weight was returned to the extruder 2. 【0089】 (Operating conditions) Extrusion rate: 10 kg / hour, 20 kg / hour, 30 kg / hour (Extruder 2) Rotation speed: Adjusted according to the extrusion rate Barrel temperature: 1st barrel section 4A and 2nd barrel section 4B 195°C, 3rd barrel section 4C 160°C (High shear processing machine 3) Rotation speed: 1500 rpm Barrel temperature: 195°C 【0090】 When a transparent window was provided in the reverse screw section 15 for inspection, it was found that no resin reached the reverse screw section 15 in either the case of an extrusion rate of 10 kg / hour or 20 kg / hour, indicating that the resin was sufficiently blocked. However, when the extrusion rate was 30 kg / hour, resin did reach the reverse screw section 15. 【0091】Furthermore, the resin processed by the high-shear processing machine 3 could be returned to the barrel 4 of the extruder 2 through the second connection port 9 and removed from the discharge port 7. The zero-shear viscosity of the resin processed by the high-shear processing machine 3 removed from the discharge port 7 was measured and found to be 637 Pa.s at an extrusion rate of 10 kg / hour and 511 Pa.s at an extrusion rate of 20 kg / hour. As described above, the resin could be continuously reduced in molecular weight using the continuous high-shear processing apparatus 1, which consists of the extruder 2 and the high-shear processing machine 3. The fact that the resin reached the reverse screw section 15 at an extrusion rate of 30 kg / hour is thought to be due to a decrease in the blocking capacity of the reverse screw section 15 caused by the vent port 14 located directly above the reverse screw section 15. 【0092】 (Example 4) Using a continuous high-shear processing apparatus 1 equipped with an extruder 2 and a high-shear processing machine 3 as shown in Figure 11, polypropylene (F704NP, manufactured by Prime Polymer) was melted and kneaded under the following conditions, and after being reduced in molecular weight by the high-shear processing machine 3, the resin after the reduction in molecular weight was returned to the extruder 2, and the difference in cooling effect due to the barrel temperature of the second barrel section 4B was evaluated. Specifically, the temperature of the resin coming out of the high-shear processing machine 3 and the discharge port 7 was measured to evaluate the difference in cooling effect. The continuous high-shear processing apparatus 1 used in this example differs from the one used in Example 3 in that a vent port 14 is provided in the second barrel section 4B. 【0093】 (Operating conditions) Extrusion rate: 10 kg / hour, 20 kg / hour, 30 kg / hour, 40 kg / hour (Extruder 2) Rotation speed: Adjusted according to the extrusion rate Barrel temperature: First barrel section 4A 195°C, Second barrel section 4B 130°C, 150°C, 195°C, Third barrel section 4C 160°C (High shear processing machine 3) Rotation speed: 3600 rpm Barrel temperature: 195°C 【0094】When a transparent window was provided in the third barrel section 4C of the reverse screw section 15 for inspection, it was found that no resin reached the reverse screw section 15 in any of the extrusion rates of 10, 20, 30, and 40 kg / hour, indicating that the resin was being blocked by the reverse screw section 15. It is believed that the blocking ability of the reverse screw section 15 was improved by providing a vent opening 14 in the second barrel section 4B and configuring the third barrel section 4C of the reverse screw section 15 as a closed barrel, i.e., without a vent opening 14. 【0095】 Table 1 below shows the difference in cooling effect depending on the set temperature of the second barrel section 4B. From the results shown in Table 1, it was found that the temperature of the resin after processing by the high shear processing machine 3 can be reduced by lowering the set temperature of the second barrel section 4B. In this embodiment, the second barrel section 4B was set to a temperature lower than the melting point of the resin (polypropylene) (approximately 160°C) in order to cool the resin after processing, but no problems arose as a result. 【0096】 The extruder of the present invention can be combined with a high-shear processing machine that reduces the molecular weight of resin by applying a high shear force to constitute a continuous high-shear processing apparatus. 【0097】1: Continuous high shear processing device 2: Extruder 3: High shear processing machine 4: Barrel 4A: First barrel section 4B: Second barrel section 4C: Third barrel section 5, 5a, 5b: Screw 6: Supply port 7: Discharge port 8: First connection port 9: Second connection port 10: Resin 11, 11a, 11b: Upstream screw section 12, 12a, 12b: Blocking section 13, 13a, 13b: Downstream screw section 14: Vent port 15: Reverse screw section 16: Connecting screw section 16A: Forward screw section 16B: Reverse screw section 16C: Boundary section 17: Narrow pitch section 20: Barrel 21: Screw 31: Barrel element 32: Through hole 33: Cylinder section 34: Supply port 35: Coolant passage 36: Head section 36a: Discharge port 37: Screw body 38: Rotating shaft 39: Cylindrical body 40: First shaft section 41: Second shaft section 42: Joint section 43: Stopper section 44: First collar 45a, 45b: Key 49a, 49b: Keyway 51: Second collar 52: Fixing screw 53: Conveyor path 81: Conveyor section 82: Barrier section 84, 86: Flight 88, 88a, 88b, 88c, 88d: Passage 89: Wall surface 91: Inlet 92: Outlet 93: Passage body 100, 101: Continuous high shear processing device 102: First extruder 103: High shear processing machine 104: Second extruder 106: Barrel 107, 107a, 107b: Screw section 108: Cylinder section 109: Supply port 111: Feed section 112: Mixing section 113: Pumping section 114: Flight 115: Disc 116: Flight 117: Discharge port 122: Barrel 123: Vent screw section 124: Cylinder section 125: Vent port 126: Vacuum pump 127: Head section 128: Discharge port 129: Flight O1: Axis R: Resin reservoir L1, L2: Length

Claims

1. An extruder comprising a barrel and a screw, wherein the barrel has a supply port, a first connection port, a second connection port and a discharge port, and the screw has, in the flow direction along the screw axis, an upstream screw portion provided upstream of the first connection port, a downstream screw portion provided downstream of the second connection port, and a damming portion provided between the first connection port and the second connection port.

2. The extruder according to claim 1, wherein the upstream screw portion has the same screw direction as the downstream screw portion, and the damming portion is a reverse screw portion whose screw direction is opposite to that of the upstream screw portion and the downstream screw portion.

3. The extruder according to claim 2, wherein a connecting screw portion is provided between the reverse screw portion and the upstream screw portion, and the connecting screw portion has a first screw portion on the upstream side having the same screw direction as the upstream screw portion, and a second screw portion on the downstream side having the same screw direction as the reverse screw portion.

4. The extruder according to claim 3, wherein the pitch of the first screw section and the second screw section is wider than the pitch of the upstream screw section.

5. The extruder according to claim 4, wherein the pitch of the first screw section and the pitch of the second screw section are the same.

6. The extruder according to claim 5, wherein the upstream screw portion has a narrow-pitch portion on the downstream side having a narrower pitch than the other portions.

7. The extruder according to claim 6, wherein the boundary between the first screw portion and the second screw portion faces the first connection port.

8. The extruder according to claim 1, wherein the barrel can have a first barrel section upstream of the first connection port and a second barrel section downstream of the second connection port set to different temperatures.

9. A continuous high-shear processing apparatus comprising an extruder and a high-shear processing machine as described in claim 1, wherein the first connection port and the second connection port of the extruder are connected to the high-shear processing machine.

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