A polymer melt homogenization treatment device with a reflux channel

Abstract

This invention relates to a polymer melt homogenization treatment device with a reflux channel. The device includes an extrusion barrel and a screw disposed within the extrusion barrel. The extrusion barrel includes a feeding section, a melting section, and a metering and conveying section according to the polymer movement direction. The extrusion barrel is provided with a pipe for refluxing a portion of the polymer melt, which refluxes the polymer from the end of the melting section to the beginning of the melting section. An outer ring is fixedly fitted inside the extrusion barrel, and an inner ring is fixedly fitted on the screw. The inner and outer rings are concentric, and a gap is provided between the outer ring of the inner ring and the inner ring of the outer ring for the polymer melt to pass through. This invention, by setting a bypass reflux channel, forces a portion of the insufficiently homogenized melt back to the upstream high-shear zone for secondary mixing, extending the average residence time of some materials and giving poorly mixed melts a chance to be homogenized again, significantly improving the temperature and compositional uniformity of the final melt.

Description

Technical Field

[0001] This invention belongs to the technical field of polymer material processing equipment, specifically relating to a polymer melt homogenization treatment device with a reflux channel. Background Technology

[0002] In the field of polymer processing, extruders are key equipment for achieving polymer melting, mixing, and homogenization. Traditional single-screw or twin-screw extruders commonly suffer from problems such as uneven mixing, localized overheating, and wide residence time distribution when processing high-viscosity polymer melts. Especially in systems with added modifiers or fillers, the melt cannot achieve sufficient circulation and mixing during screw conveying, resulting in defects such as uneven component distribution and large melt temperature differences in the final product, which seriously affects the stability of product quality.

[0003] In existing technologies, some devices improve mixing by increasing the screw's length-to-diameter ratio or using special threaded elements. However, this often leads to increased equipment costs and energy consumption, and it cannot remedy existing mixing inhomogeneities. Therefore, developing a homogenization device capable of forced recirculation of the melt has significant practical value. Summary of the Invention

[0004] The purpose of this invention is to provide a polymer melt homogenization treatment device with a reflux channel in order to solve the problems mentioned in the background art.

[0005] The present invention achieves the above objectives through the following technical solutions: A polymer melt homogenization treatment device with a reflux channel includes an extrusion cylinder and a screw disposed within the extrusion cylinder. The extrusion cylinder includes a feeding section, a melting section, and a metering and conveying section according to the polymer movement direction. The device is characterized in that the extrusion cylinder is provided with a pipe for refluxing a portion of the polymer melt, the pipe refluxing the polymer from the end of the melting section to the beginning of the melting section. An outer ring is fixedly sleeved inside the extrusion cylinder, and an inner ring is fixedly sleeved on the screw. The inner ring and the outer ring are concentric. A gap is provided between the outer ring of the inner ring and the inner ring of the outer ring to allow the polymer melt to pass through. The gap traps unmelted material in the polymer melt and allows it to flow back to the beginning of the melting section through the pipeline.

[0006] Preferably, a scraper is fixedly mounted on the screw, the scraper being used to push the unmelted polymer toward the inlet of the pipe; The scraper is located on the rear side of the polymer flow direction and is in contact with the surfaces of both the outer ring and the inner ring.

[0007] Preferably, the scraper is provided with protrusions for cleaning the gaps.

[0008] Preferably, a telescopic component is fixedly provided at the inlet of the pipe, and a cleaning component for scraping off the unmelted polymer accumulated on the scraper is fixedly provided at the telescopic end of the telescopic component.

[0009] Preferably, the cleaning component includes a substrate and a limiting member fixed on the substrate, the limiting member being used to carry the unmelted polymer toward the pipe inlet.

[0010] Preferably, the cleaning component is made of an elastic material.

[0011] Preferably, the inlet of the pipe is provided with a cleaning component for cleaning up unmelted polymer at the limiting component.

[0012] Preferably, the cross-section of the cleaning component is polygonal.

[0013] Preferably, the cleaning component is rotatably mounted on the pipe via a rotating shaft, and the rotating shaft is fixedly connected to a drive motor for rotating the cleaning component.

[0014] The beneficial effects of this invention are as follows: 1. By setting up a bypass reflux channel, the present invention forces some of the insufficiently homogenized melt back to the upstream high-shear zone for secondary mixing, which prolongs the average residence time of some materials, giving the poorly mixed melt a chance to be homogenized again, and significantly improving the temperature and composition uniformity of the final melt.

[0015] 2. This invention achieves forced separation of unmelted material through the gap between the inner and outer rings. With the cooperation of the reflux pipe, this part of the material is actively extracted and sent back to the high shear zone, realizing the recycling of unmelted material and fundamentally avoiding the problems of accumulation and degradation.

[0016] 3. This invention improves the return efficiency of unmelted materials and reduces the accumulation of dead corners within the equipment through structures such as scrapers and cleaning components. The cleaning components are responsible for picking up material from the scrapers and vice versa, forming a two-stage relay-style material transfer. This design ensures that both the scrapers and cleaning components remain clean for extended periods, avoiding the problem of clogging leading to system failure. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram showing the positional relationship between the outer ring, inner ring, and screw in this invention; Figure 3 yes Figure 2 Enlarged view of point A in the middle; Figure 4 This is a schematic diagram showing the positional relationship between the inner and outer rings when there are multiple inner rings in this invention.

[0018] In the diagram: 1. Extrusion cylinder; 2. Screw; 3. Pipe; 4. Outer ring; 5. Inner ring; 6. Gap; 7. Scraper; 8. Telescopic component; 9. Base plate; 10. Limiting component; 11. Cleaning component; 12. Drive motor. Detailed Implementation

[0019] The present application will now be described in further detail. It should be noted that the following specific embodiments are only used to further illustrate the present application and should not be construed as limiting the scope of protection of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application based on the above application content.

[0020] Example 1

[0021] like Figure 1-4 As shown, a polymer melt homogenization treatment device with a reflux channel includes an extrusion barrel 1 and a single screw 2 inside the extrusion barrel 1. The extrusion barrel 1 includes a feeding section, a melting section, and a metering and conveying section according to the polymer movement direction. Multiple heating and cooling units are provided on the outside of the extrusion barrel 1. A pipe 3 is provided on the extrusion barrel 1 for refluxing a portion of the polymer melt. The inlet of the pipe 3 is located at the end of the melting section, and the outlet is connected back to the beginning of the melting section of the screw 2. Preferably, a melt pump is provided inside the pipe 3 for forcibly sending a portion of the insufficiently homogenized melt back to the high-shear zone (the beginning of the melting section of the screw 2) for secondary mixing. The melt pump is an adjustable-speed gear pump.

[0022] An outer ring 4 is fixedly fitted inside the extrusion barrel 1, and an inner ring 5 is fixedly fitted on the screw 2. The inner ring 5 and the outer ring 4 are concentric, and a gap 6 is provided between the outer ring of the inner ring 5 and the inner ring of the outer ring 4 to allow polymer to pass through. The outer ring 4 is fixed to the inner wall of the extrusion barrel 1 by a key, pin, or interference fit and does not rotate with the screw 2; the inner ring 5 is fixed to the screw 2 by a key or thread and rotates synchronously with the screw 2. Both the inner ring 5 and the outer ring 4 are made of wear-resistant alloy materials (such as nitrided steel or duplex stainless steel) with a surface hardness ≥60HRC.

[0023] It should be noted that only melted material with sufficiently low viscosity can be forced through the gap 6 between the outer ring 4 and the inner ring 5 into the front of the extrusion barrel 1 under the pressure generated by the rotation of screw 2. Unmelted solid particles or high-viscosity gels, due to their large size or inability to deform, are forcibly retained in the middle or front of the melt conveying section (the direction of the outer ring 4 near the beginning of the melt melting section). The retained unmelted material continues to be heated by the barrel and subjected to strong shearing action by the kneading blocks on screw 2 in the extrusion barrel 1. After the unmelted material gradually melts, it enters the front of the extrusion barrel 1 through the gap 6. Finally, almost all of the output from the barrier section is pure, fully molten melt.

[0024] Preferably, the gap 6 is 0.3-1.0 mm (depending on the material particle size and melt viscosity). If the gap 6 is too small, the pressure drop will increase dramatically and it will easily become clogged; if the gap 6 is too large, unmelted material will pass through directly, resulting in a loss of separation effect. The axial length of the gap 6 is 3-5D (D is the diameter of screw 2). If it is too short, the melting will be incomplete; if it is too long, it will increase energy consumption and the risk of degradation. Under the action of the gap 6, the pressure drop is usually 30-50% higher than that of a conventional screw 2, requiring a more powerful motor to drive the screw 2 to rotate.

[0025] In this embodiment, the inner ring 5 is not limited to a single ring and can be configured as a ring-within-a-ring structure. That is, the inner ring 5 consists of several interlocking rings, with gaps 6 between each ring, and the rings can rotate freely. The gaps 6 are increased from one to several, increasing the area through which the polymer flows, thus preventing a sudden increase in pressure inside the extrusion cylinder 1 and allowing the polymer to pass through normally.

[0026] Furthermore, the screw 2 is provided with a scraper 7 for pushing the unmelted polymer toward the inlet of the return pipe 3. The scraper 7 is fixedly installed on the screw 2, and the scraper 7 is in surface contact with the outer ring 4 and the inner ring 5 and is located on the rear side of the polymer flow direction.

[0027] It should be noted that the end faces of the outer ring 4 and the inner ring 5 are flush. When the scraper 7 rotates with the screw 2, it can move the unmelted material in the gap 6, allowing unmelted material far from the inlet of the pipe 3 to move to the inlet of the pipe 3 and be sucked in by the pipe 3. The scraper 7 not only promotes the backflow of unmelted material, but also agitates the molten polymer, thus helping to achieve uniform dispersion of the polymer.

[0028] Preferably, the scraper 7 is provided with protrusions for cleaning the gap 6. These protrusions clean the gap 6 and any unmelted material trapped within it, ensuring the gap remains unobstructed and allowing the polymer to move normally and continuously. The protrusions should be slightly smaller than the width of the gap 6 (e.g., 0.7-0.9 mm for a gap of 1.0 mm) to prevent them from getting stuck and causing wear or jamming. The cross-sectional shape of the protrusions should preferably be semi-circular or trapezoidal to reduce stress concentration.

[0029] Example 2

[0030] Based on Example 1, in this example, a telescopic component 8 is fixedly provided at the inlet of the pipe 3, and a cleaning component 11 for scraping off the unmelted polymer accumulated on the scraper 7 is fixedly provided at the telescopic end of the telescopic component 8. Preferably, the telescopic component 8 is an electric push rod, which is fireproofed and heat-insulated, and can be cooled by water cooling.

[0031] It should be noted that, due to the high viscosity of the molten material, the scraper 7 may cause the molten material to rotate along the screw 2 inside the extrusion cylinder 1 during rotation, which may prevent the scraper 7 from collecting the unmelted material and thus affect the performance of the scraper 7.

[0032] With the cleaning component 11 installed, the telescopic component 8 drives the cleaning component 11 to move during the rotation of the scraper 7, so that the cleaning component 11 extends into the extrusion cylinder 1 and is located on the moving trajectory of the scraper 7. The cleaning component 11 blocks the tendency of the molten material to rotate along the screw 2, and the scraper 7 can collect the unmelted material near the end face of the outer ring 4 during rotation and gradually move it to the inlet of the pipe 3.

[0033] When the scraper 7 contacts the cleaning component 11, the telescopic component 8 drives the cleaning component 11 out of the extrusion cylinder 1. During its movement, the cleaning component 11 carries away a large amount of unmelted material from the scraper 7, improving the return efficiency of the unmelted material. The timing of the cleaning component 11 entering the extrusion cylinder 1 should be synchronized with the rotation phase of the scraper 7 to avoid collision. A position sensor (such as a Hall sensor or rotary encoder) can be installed on the screw 2 shaft, and the timing of the telescopic component 8 can be controlled by a controller (PLC).

[0034] The number of scrapers 7 can be set at equal intervals along the axial direction of the screw 2 to improve the reflow efficiency of unmelted materials.

[0035] Preferably, the cleaning component 11 includes a substrate 9 and a limiting component 10 fixedly disposed on the substrate 9. The limiting component 10 is used to carry the unmelted polymer towards the inlet of the pipe 3. The limiting component 10 is L-shaped and includes a hooking section and a storage section. When the limiting component 10 moves, it can carry out the unmelted material at the scraper 7. The storage section can provide a certain degree of protection for the unmelted material and prevent it from being carried away again as the molten material moves.

[0036] In this embodiment, the cleaning component 11 is made of an elastic material. The cleaning component 11 retracts synchronously after contacting the scraper 7. In order to avoid damaging the scraper 7, the cleaning component 11 has a certain degree of elasticity.

[0037] Example 3

[0038] Based on Example 2, in this example, the inlet of the pipe 3 is provided with a cleaning component 11 for cleaning the unmelted polymer at the limiting component 10.

[0039] The cross-section of the cleaning component 11 is polygonal.

[0040] The cleaning component 11 is rotatably mounted on the pipe 3 via a rotating shaft, and the rotating shaft is fixedly connected to a drive motor 12 for driving the cleaning component 11 to rotate.

[0041] The cleaning component 11 is installed on the inner wall of the inlet of pipe 3, and its rotation axis is aligned with the axis of the extrusion cylinder 1. The drive motor 12 is a low-speed, high-torque motor (10-60 rpm) and is equipped with a magnetic coupler to prevent melt leakage into the motor cavity.

[0042] It should be noted that, due to the high viscosity of unmelted and molten materials, the cleaning component 11 may accumulate unmelted materials inside the scraper 7 when scraping off the unmelted materials. This not only affects the continuous cleaning of the scraper 7, but also the long-term presence of unmelted materials inside the cleaning component 11 can easily cause the unmelted materials to degenerate, resulting in unqualified products.

[0043] By providing a drive motor 12, the cleaning component 11 is rotated by the drive motor 12. During the movement of the cleaning component 11, the interior of the cleaning component 11 is cleaned, so that the unmelted material attached to the cleaning component 11 enters the pipe 3 along with the molten material for backflow.

[0044] The cleaning component 11 has a polygonal cross-section with a large length-to-width ratio and an elliptical structure, which can continuously remove unmelted materials and has a smooth surface that does not allow unmelted materials to adhere.

[0045] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A polymer melt homogenization treatment device with a reflux channel, comprising an extrusion barrel (1) and a screw (2) disposed within the extrusion barrel (1), wherein the extrusion barrel (1) includes a feeding section, a melting section, and a metering and conveying section according to the polymer movement direction, characterized in that, The extrusion cylinder (1) is provided with a pipe (3) for recirculating part of the polymer melt, the pipe (3) recirculating the polymer from the end of the molten section to the beginning of the molten section; An outer ring (4) is fixedly sleeved inside the extrusion cylinder (1), and an inner ring (5) is fixedly sleeved on the screw (2). The inner ring (5) and the outer ring (4) are concentric. A gap (6) is provided between the outer ring of the inner ring (5) and the inner ring of the outer ring (4) for the polymer melt to pass through. The gap (6) traps the unmelted material in the polymer melt and it is returned to the beginning of the melting section along with the pipe (3).

2. The polymer melt homogenization equipment with a reflux channel according to claim 1, characterized in that, A scraper (7) is fixedly installed on the screw (2), and the scraper (7) is used to push the unmelted polymer toward the inlet of the pipe (3); The scraper (7) is located on the rear side of the polymer flow direction and is in contact with the surfaces of the outer ring (4) and the inner ring (5).

3. The polymer melt homogenization equipment with a reflux channel according to claim 2, characterized in that, The scraper (7) is provided with protrusions for cleaning the gap (6).

4. The polymer melt homogenization equipment with a reflux channel according to claim 3, characterized in that, The inlet of the pipe (3) is fixedly provided with a telescopic component (8), and the telescopic end of the telescopic component (8) is fixedly provided with a cleaning component (11) for scraping off the unmelted polymer accumulated on the scraper (7).

5. The polymer melt homogenization equipment with a reflux channel according to claim 4, characterized in that, The cleaning component (11) includes a substrate (9) and a limiting component (10) fixed on the substrate (9). The limiting component (10) is used to carry the unmelted polymer toward the inlet of the pipe (3).

6. The polymer melt homogenization equipment with a reflux channel according to claim 5, characterized in that, The cleaning component (11) is made of an elastic material.

7. The polymer melt homogenization equipment with a reflux channel according to claim 6, characterized in that, The inlet of the pipe (3) is provided with a cleaning component (11) for cleaning the unmelted polymer at the limiting component (10).

8. The polymer melt homogenization equipment with a reflux channel according to claim 7, characterized in that, The cross-section of the cleaning component (11) is polygonal.

9. A polymer melt homogenization treatment device with a reflux channel according to claim 8, characterized in that, The cleaning component (11) is rotatably mounted on the pipe (3) via a rotating shaft, and the rotating shaft is fixedly connected to a drive motor (12) for driving the cleaning component (11) to rotate.

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