Single-screw extruder for extruding wide-width TPO geomembrane and extrusion screw
By improving the structure and parameters of the single-screw extruder, the problems of uneven material mixing and poor plasticization in the production of wide-width TPO geomembranes were solved, and the efficient production of high-quality wide-width TPO geomembranes was achieved.
Patent Information
- Application Number
- CN202422790856.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-15
- Publication Date
- 2025-11-04
- Estimated Expiration
- 2034-11-15
AI Technical Summary
Existing single-screw extruders have difficulty mixing materials evenly and achieving poor plasticization when extruding wide-width TPO geomembranes, and there are residual air bubbles, which cannot meet the production requirements of wide-width TPO geomembranes.
A single-screw extruder for wide-width TPO geomembrane extrusion was designed, including a feeding section, a first compression section, a barrier section, an exhaust section, a second compression section, and a homogenization section. It is equipped with pins and two exhaust ports, and adopts a water ring vacuum pump. The screw diameter and length-to-diameter ratio are improved, and heating and heat dissipation measures are combined to ensure material uniformity and plasticizing effect.
It achieves uniform mixing and plasticization of materials, reduces extrusion temperature, avoids residual air bubbles, meets the production requirements of TPO geomembranes with a width of 6m and above, and improves product quality.
Smart Images
Figure CN223507653U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of screw extruders, specifically relating to a single screw extruder and extrusion screw for wide-width TPO geomembrane extrusion. Background Technology
[0002] Tests have shown that in order to reduce the difference in transverse and longitudinal elongation at break during the production of wide-width TPO geomembranes, the extruded wide-width TPO geomembranes need to complete most of the crystallization process before entering the three-roll calender. This requires ensuring that the material temperature during extrusion by the screw extruder is low enough to allow for crystallization.
[0003] Currently, screw extruders are generally divided into single-screw extruders and twin-screw extruders. Twin-screw extruders are typically used for extruding products with a width of 6m or more due to their advantages of large barrel capacity, thorough material mixing, good plasticizing effect, and high production efficiency. However, for TPO geomembranes, when using a twin-screw extruder, the shear heat generated during extrusion is significantly greater than that of a single-screw extruder after the material melts. This results in a significantly higher extrusion temperature (approximately 30 degrees Celsius higher) than that of a single-screw extruder. This increased extrusion temperature not only alters the material composition but also fails to meet the low-temperature requirements for extruding wide-width TPO geomembranes using a screw extruder. While scaling up a traditional single-screw extruder can meet the capacity requirements for producing wide-width TPO products, its slow speed makes it difficult to achieve uniform mixing and poor plasticizing when extruding wide-width products. It may even retain residual air bubbles, making it unsuitable for extruding wide-width TPO geomembranes. Utility Model Content
[0004] The purpose of this invention is to overcome the shortcomings of existing single-screw extruders, which, when used to extrude wide-width TPO geomembranes, result in uneven material mixing, poor plasticization, and residual air bubbles. This invention provides a single-screw extruder and extrusion screw for wide-width TPO geomembranes.
[0005] To achieve the above objectives, the technical solution adopted by this utility model is as follows:
[0006] An extrusion screw includes a feeding section, a first compression section, a barrier section, a venting section, a second compression section, and a homogenization section arranged sequentially in the direction of material travel.
[0007] As a further technical solution, the extrusion screw is provided with several rings of pins in the middle and rear part of the first compression section and the homogenization section.
[0008] As a further technical solution, in the homogenization section, adjacent ring pins are staggered; in the middle and rear part of the first compression section, several ring pins are positioned correspondingly in the radial direction and are distributed in a row.
[0009] As a further technical solution, the diameter of the extrusion screw is ≥180mm and the length-to-diameter ratio is ≥38.
[0010] As a further technical solution, the length of the extrusion screw is 6930mm.
[0011] A single-screw extruder for wide-width TPO geomembrane extrusion includes a barrel mechanism, a feed inlet and a discharge outlet disposed on the barrel mechanism, an extrusion screw rotatably disposed within the barrel mechanism, and a motor for driving the extrusion screw to rotate.
[0012] As a further technical solution, the barrel mechanism includes a protective shell, a barrel disposed inside the protective shell, a heating module sleeved on the barrel, and a cooling fan disposed outside the protective shell for cooling the heating module.
[0013] As a further technical solution, the heating module includes a heating coil wound around the outer wall of the barrel;
[0014] The air outlet of the cooling fan is aligned with the heating coil of the corresponding heating module.
[0015] As a further technical solution, two exhaust ports are provided on the barrel at positions corresponding to the exhaust section of the extrusion screw, and the exhaust ports are connected to a water ring vacuum pump.
[0016] As a further technical solution, a cooling coil is provided on the outside of the barrel at a position corresponding to the feeding section.
[0017] As a further technical solution, according to the material travel direction, the discharge port is also sequentially equipped with an automatic screen changer, a metering pump, a static mixer, a distributor, and a wide-width mold.
[0018] Compared with the prior art, the beneficial effects of this utility model are as follows:
[0019] 1. This utility model uses a single-screw extruder to produce wide-width TPO geomembranes. The shear heat generated during the material movement process is much less than that of a twin-screw extruder, thus reducing the temperature during the extrusion of wide-width TPO geomembranes compared to a twin-screw extruder.
[0020] 2. This utility model sets the diameter of the extrusion screw to ≥180mm and the length-to-diameter ratio to ≥38, so that it can meet the extrusion volume requirements of TOP geomembrane with a width of 6m and above.
[0021] 3. This utility model improves the structure of the extrusion screw, setting it as follows: feeding section, first compression section, barrier section, venting section, second compression section, and homogenization section arranged sequentially in the material travel direction. In this utility model, after the material melts in the first compression section, it enters the venting section through the barrier section to expel the gas from the melt. Then, it is repressurized in the second compression section and homogenized in the homogenization section before being discharged. The functions of each section of the extrusion screw in this utility model are as follows: 1) This utility model includes a first compression section for melting the material; 2) In traditional technology, the barrier section is usually located between the compression section and the homogenization section. This invention uses a barrier section to block unmelted materials. The barrier section is positioned between the first compression section and the venting section. While blocking unmelted materials, it also promotes the expulsion of air bubbles, improving the venting effect and preventing backflow of material from the venting section. 3) The venting section is used to expel air bubbles from the melt. 4) A second compression section is placed after the venting section to apply secondary pressure to the material, improving the plasticizing effect and enhancing the uniformity and plasticizing effect of the melt. 5) A homogenization section is included to homogenize the melt before extrusion, providing uniformity. Furthermore, several pins are placed in the middle and rear of the first compression section to mix and homogenize the melt during compression and plasticizing, promoting uniform melting and allowing the melt to undergo preliminary homogenization before venting, thus improving the uniformity and plasticizing effect. In summary, the sequence of the sections in this invention greatly improves the uniformity and plasticizing effect of the melt, enabling it to meet the production needs of large-volume materials.
[0022] 4. Traditional screw extruders, even with a venting section, only have one vent. This invention, however, has two vents on the barrel of the venting section, and a water ring vacuum pump is installed at each vent. This design provides a larger venting volume, accelerating the removal of gas from the melt and preventing defects such as pits caused by residual air bubbles. On the other hand, it promotes melt cooling, solving the problem of melt heating caused by shear force, thereby reducing the temperature during wide-width TPO geomembrane extrusion. The combined effect of these two factors significantly reduces melt defects in the TPO filler system compared to traditional single-screw extruders that are simply scaled up proportionally.
[0023] In summary, this invention, by adjusting the diameter and length-to-diameter ratio of the extrusion screw, the function and sequence of each section of the screw, and by setting two exhaust ports and a water ring vacuum pump, ensures the mixing and plasticizing effect of the melt while greatly increasing the capacity of the single-screw extruder. It also reduces the temperature of the melt during extrusion, making it suitable for extruding TPO geomembranes with a width of 6m or more. In addition, it facilitates the removal of air bubbles in the melt, avoiding product defects caused by residual air bubbles in the melt. Attached Figure Description
[0024] Figure 1 This is a schematic diagram of a single-screw extruder for wide-width TPO geomembrane extrusion in one embodiment of the present invention;
[0025] Figure 2 This is a schematic diagram of the structure of the barrel mechanism in one embodiment of the present invention;
[0026] Figure 3 This is a schematic diagram of the structure of the barrel in one embodiment of the present invention;
[0027] Figure 4 This is a schematic diagram of the extrusion screw in one embodiment of the present invention;
[0028] Figure 5 for Figure 4 Enlarged view of point A;
[0029] Figure 6 This is a schematic diagram of the extrusion screw in the homogenization section of one embodiment of the present invention.
[0030] In the diagram: 1. Barrel mechanism, 2. Cooling coil, 3. Feed inlet, 4. Discharge outlet, 5. Extrusion screw, 6. Motor, 7. Feeding section, 8. First compression section, 9. Barrier section, 10. Exhaust section, 11. Second compression section, 12. Homogenization section, 13. Exhaust port, 14. Water ring vacuum pump, 15. Pin, 16. Protective housing, 17. Barrel, 18. Heating coil, 19. Heating module, 20. Cooling fan, 21. Automatic screen changer, 22. Metering pump, 23. Static mixer, 24. Distributor, 25. Wide die, 26. Spiral groove, 27. Temperature sensor. Detailed Implementation
[0031] The technical solution of this utility model will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.
[0032] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.
[0033] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.
[0034] The present invention will now be described in further detail with reference to the accompanying drawings.
[0035] Example 1
[0036] Figure 1-6 This invention illustrates an embodiment of a single-screw extruder for wide-width TPO geomembrane extrusion, comprising a barrel mechanism 1, a feed inlet 3 and a discharge outlet 4 disposed on the barrel mechanism 1, an extrusion screw 5 rotatably disposed within the barrel mechanism 1, and a motor 6 for driving the extrusion screw 5 to rotate; the extrusion screw 5 includes a feeding section 7, a first compression section 8, a barrier section 9, an exhaust section 10, a second compression section 11, and a homogenization section 12 arranged sequentially in the material's travel direction. In this invention, after the material melts in the first compression section 8, it enters the venting section 10 through the barrier section 9 to expel the gas from the melt. Then, it is repressurized in the second compression section 11 and homogenized in the homogenization section 12 before being discharged. The functions of each section of the extrusion screw in this invention are as follows: 1. The first compression section 8 is used to melt the material. 2. In traditional technology, the barrier section is usually set between the compression section and the homogenization section to block unmelted material. In this invention, the barrier section 9 is set between the first compression section 8 and the venting section 10. The barrier section 9 can not only block unmelted material, but also promote the discharge of air bubbles, improve the venting effect, and prevent the backflow of material in the venting section. 3. The venting section 10 is used to discharge air bubbles in the melt. 4. The second compression section 11 is set after the venting section to repressurize the material, which improves the plasticizing effect of the material and the uniformity and plasticizing effect of the melt. 5. The homogenization section is set to homogenize the melt before extrusion, providing uniformity of the melt.
[0037] As an embodiment of the single-screw extruder for wide-width TPO geomembrane extrusion according to this utility model, the diameter is ≥180mm and the length-to-diameter ratio is ≥38.
[0038] As an embodiment of the single-screw extruder for wide TPO geomembrane extrusion according to this utility model, the diameter of the extrusion screw 5 is 180mm and the length-to-diameter ratio is 38:1; this parameter setting enables it to meet the extrusion volume requirements of TOP geomembrane with a width of 6m and above.
[0039] As an embodiment of the single-screw extruder for wide-width TPO geomembrane extrusion according to this utility model, the extrusion screw 5 is provided with several rings of pins 15 in the middle and rear part of the first compression section 8 and the homogenization section 12. The present utility model provides pins 15 in the middle and rear part of the first compression section, which can mix and homogenize at the same time as compression and plasticization, thereby further improving the mixing and plasticization effect of the melt.
[0040] As an embodiment of the single-screw extruder for wide-width TPO geomembrane extrusion according to this utility model, in the homogenization section, adjacent ring pins 15 are staggered.
[0041] As an embodiment of the single-screw extruder for wide-width TPO geomembrane extrusion according to this utility model, in the middle and rear part of the first compression section 8, several rings of pins 15 are positioned correspondingly in the radial direction and are distributed in a row, and the interval between adjacent rings is equal to the thread pitch of the extrusion screw of the first compression section.
[0042] As an embodiment of the single-screw extruder for wide-width TPO geomembrane extrusion according to this utility model, the barrel mechanism 1 includes a protective shell 16, a barrel 17 disposed within the protective shell 16, a heating module 19 sleeved on the barrel 17, and a cooling fan 20 disposed outside the protective shell 16 for cooling the heating module 19. The heating module 19 is used to heat the material, and the cooling fan 20 can cool the heating module 19 when the temperature of the barrel 17 exceeds a set temperature, thereby achieving temperature control of the material.
[0043] As an embodiment of the single-screw extruder for wide-width TPO geomembrane extrusion according to the present invention, the heating module 19 includes a heating coil 18 wound on the outer wall of the barrel 17.
[0044] As an embodiment of the single-screw extruder for wide-width TPO geomembrane extrusion of this utility model, the outer wall of the barrel 17 is provided with a plurality of spiral grooves 26, and the heating coil 18 is wound around the outer wall of the barrel 17 along the spiral grooves 26.
[0045] As an embodiment of the single-screw extruder for wide-width TPO geomembrane extrusion according to this utility model, the air outlet of the cooling fan 20 is aligned with the heating coil 18 of the corresponding heating module 19.
[0046] As an embodiment of the single-screw extruder for wide-width TPO geomembrane extrusion according to this utility model, two exhaust ports 13 are provided on the barrel 17 at positions corresponding to the exhaust section 10 of the extrusion screw 5. The exhaust ports 13 are connected to a water ring vacuum pump 14. This design can provide a larger exhaust volume, accelerate the discharge of gas in the melt, and avoid defects such as pits in the product caused by residual air bubbles. On the other hand, it can further reduce the temperature of the melt and reduce the temperature during wide-width TPO geomembrane extrusion. The combined effect of these two factors greatly reduces melt defects in the TPO filler system compared to a traditional single-screw extruder that is simply scaled up proportionally.
[0047] As an embodiment of the single-screw extruder for wide-width TPO geomembrane extrusion according to this utility model, several temperature sensors 27 are also provided on the barrel mechanism for detecting the temperature of the material.
[0048] As an embodiment of the single-screw extruder for wide-width TPO geomembrane extrusion according to this utility model, a cooling coil 2 is provided on the outside of the barrel 17 at a position corresponding to the feeding section 7. Since the material is usually conveyed by a conveyor during feeding, and the material temperature entering the extruder is too high due to shear heat generated during the conveying process, the cooling coil 2 is provided at the feeding section 7 of the extruder to cool down the material entering the extruder, so as to avoid the material temperature entering the extruder being too high and affecting the temperature control of the barrel 17, thereby causing product defects.
[0049] As an embodiment of the single-screw extruder for wide-width TPO geomembrane extrusion of this utility model, the discharge port 4 is also provided with an automatic screen changer 21, a metering pump 22, a static mixer 23, a distributor 24 and a wide-width die 25 in sequence according to the material travel direction.
[0050] As an embodiment of the single-screw extruder for wide-width TPO geomembrane extrusion according to this utility model, the width of the wide-width die is greater than or equal to 6m.
[0051] Effect comparison:
[0052] 1. Experimental materials, see Table 1;
[0053] Table 1
[0054] Raw material type Specific raw materials weight ratio thermoplastic polyolefin resin <![CDATA[C3 / C2 / C4 terpolymerized polypropylene (reactive grade TPO)]]> 40 copies thermoplastic polyolefin resin <![CDATA[C3 / C2 binary copolymer polypropylene]]> 15 copies Toughened resin Ethylene / α-butene random copolymer 10 copies Toughened resin Ethylene / α-octene block copolymer 10 copies Inorganic packing Calcium carbonate 20 copies antioxidants Irganox B225 0.5 copies Light stabilizers Chimassorb 2020 0.5 copies nucleating agent Zinc stearate 0.3 copies nucleating agent Calcium 1,2-cyclohexanedicarboxylate 0.7 copies pigment Titanium dioxide 3 copies
[0055] 2. Extrusion methods for geomembranes
[0056] A process for preparing a wide-width TPO geomembrane includes the following steps:
[0057] Step 1: Mix inorganic filler, antioxidant, light stabilizer, nucleating agent and pigment, and then extrude and granulate with thermoplastic polyolefin resin using a twin-screw extruder to obtain high-concentration filler thermoplastic polyolefin masterbatch.
[0058] Step 2: The high-concentration filler thermoplastic polyolefin masterbatch, the remaining thermoplastic polyolefin resin and toughening resin are extruded into shape using the wide-width TPO geomembrane extrusion single-screw extruder, commercially available twin-screw extruder and commercially available split-type single-screw extruder of Example 2 of this utility model, respectively. Then, the thickness is fixed by a three-roll calender, the edges are trimmed, the length is cut, the roll is wound and packaged to obtain a 6m wide TPO geomembrane.
[0059] 3. Appearance and performance testing
[0060] 1. The appearance of the TPO geomembrane produced by the wide-width TPO geomembrane extrusion single-screw extruder of Example 2 of this utility model was compared with that of the TPO geomembrane produced by a commercially available separate single-screw extruder; the results are as follows:
[0061] The TPO geomembrane produced by the wide-width TPO geomembrane extrusion using a single-screw extruder in Example 2 has a smooth and clean surface and a dense cross-section without air holes; while the TPO geomembrane produced by a commercially available split single-screw extruder has defects such as air holes and cavities inside the product due to poor mixing and plasticizing effects and difficulty in expelling air bubbles.
[0062] 2. The performance of the TPO geomembrane prepared by the single-screw extruder for wide-width TPO geomembrane extrusion according to Example 2 of this utility model and the TPO geomembrane prepared by the commercially available twin-screw extruder were tested. The results are shown in Table 2.
[0063] Table 2
[0064]
[0065] Wide-width TPO geomembranes produced by commercially available twin-screw extruders exhibit significant differences in longitudinal / transverse elongation at break, far inferior to those of this invention.
[0066] The above-described embodiments are merely preferred embodiments of this utility model, and not an exhaustive list of all feasible implementations of this utility model. Any obvious modifications made by those skilled in the art without departing from the principles and spirit of this utility model should be considered to be included within the scope of protection of the claims of this utility model.
Claims
1. An extrusion screw, characterized in that, It includes a feeding section (7), a first compression section (8), a barrier section (9), an exhaust section (10), a second compression section (11), and a homogenization section (12) arranged sequentially according to the material's direction of travel. Several rings of pins (15) are provided in the middle and rear part of the first compression section (8) and the homogenization section (12). In the homogenization section (12), adjacent ring pins (15) are staggered; in the middle and rear part of the first compression section (8), several ring pins (15) are positioned in the radial direction and are distributed in a row.
2. An extrusion screw according to claim 1, characterized in that, The diameter of the extrusion screw (5) is ≥180mm and the length-to-diameter ratio is ≥38.
3. A single-screw extruder for wide-width TPO geomembrane extrusion, characterized in that, It includes a barrel mechanism (1), a feed port (3) and a discharge port (4) disposed on the barrel mechanism (1), an extrusion screw (5) rotatably disposed in the barrel mechanism (1) and as described in any one of claims 1-2, and a motor (6) for driving the extrusion screw (5) to rotate.
4. A single-screw extruder for wide-width TPO geomembrane extrusion according to claim 3, characterized in that, The barrel mechanism (1) includes a protective shell (16), a barrel (17) disposed inside the protective shell (16), a heating module (19) sleeved on the barrel (17), and a cooling fan (20) disposed outside the protective shell (16) for cooling the heating module (19).
5. A single-screw extruder for wide-width TPO geomembrane extrusion according to claim 4, characterized in that, The heating module (19) includes a heating coil (18) wound on the outer wall of the barrel (17); The air outlet of the cooling fan (20) is aligned with the heating coil (18) of the corresponding heating module (19).
6. A single-screw extruder for wide-width TPO geomembrane extrusion according to claim 4, characterized in that, Two exhaust ports (13) are provided on the barrel (17) at positions corresponding to the exhaust section (10) of the extrusion screw (5), and the exhaust ports (13) are connected to a water ring vacuum pump (14).
7. A single-screw extruder for wide-width TPO geomembrane extrusion according to claim 4, characterized in that, A cooling coil (2) is provided on the outside of the barrel (17) at a position corresponding to the feeding section (7).
8. A single-screw extruder for wide-width TPO geomembrane extrusion according to claim 3, characterized in that, According to the material travel direction, the discharge port (4) is also provided with an automatic screen changer (21), a metering pump (22), a static mixer (23), a distributor (24) and a wide mold (25) in sequence.