Environmentally friendly recycled material twin-screw extruder and method

Abstract

The application relates to the technical field of environment-friendly regenerated material production equipment, in particular to an environment-friendly regenerated material double-screw extruder and method, which comprises a feeding driving mechanism, a feeding extruding mechanism, a mixing driving mechanism and a mixing extruding mechanism. The feeding driving mechanism is used for driving the feeding extruding mechanism, the mixing driving mechanism is used for driving the mixing extruding mechanism, the feeding extruding mechanism is used for feeding materials, the feeding extruding mechanism comprises a feeding tank body, a feeding fixing support, a feeding main screw, a feeding driven screw and a feeding connecting seat, both ends of the feeding tank body are respectively provided with a feeding port and a discharging port, and the discharging port is used for connecting the mixing extruding mechanism. The feeding main screw in the grinding channel and the feeding driven screw work cooperatively, not only realizing the stable conveying of the materials from the feeding port to the discharging port, but also efficiently grinding the materials in the conveying process, which is helpful to improving the dispersivity and uniformity of the materials.

Description

Technical Field

[0001] This invention relates to the field of environmentally friendly recycled material production equipment technology, and in particular to an environmentally friendly recycled material twin-screw extruder and method. Background Technology

[0002] With the increasing prominence of global resource and environmental issues, sustainable development has become an important direction for all industries. The recycling and utilization of recycled materials, as a key link in resource recycling, has received widespread attention. Traditional recycled material production processes have many problems and cannot meet the demands of modern industry for efficient, precise, and environmentally friendly production. Against this backdrop, intelligent production lines for recycled materials have emerged.

[0003] In the extrusion process, recycled materials need to be produced using a screw extruder. However, existing extruders have relatively simple structures and do not pre-treat some recycled materials, leading to instability and insufficient material dispersion in the subsequent extrusion process. Therefore, new improvements are needed to the existing extrusion mechanism. Summary of the Invention

[0004] To address the aforementioned issues, this invention provides an environmentally friendly twin-screw extruder and method for producing recycled materials. The main feed screw and the driven feed screw in the grinding channel work together to not only achieve stable material transport from the feed port to the discharge port, but also efficiently grind the material during transport, thereby improving the dispersion and uniformity of the material.

[0005] The technical solution adopted in this invention is: an environmentally friendly recycled material twin-screw extruder, comprising a feeding drive mechanism, a feeding extrusion mechanism, a mixing drive mechanism, and a mixing extrusion mechanism. The feeding drive mechanism drives the feeding extrusion mechanism, and the mixing drive mechanism drives the mixing extrusion mechanism. The feeding extrusion mechanism is used for material input. The feeding extrusion mechanism includes a feeding tank, a feeding fixed bracket, a feeding main screw, a feeding driven screw, and a feeding connecting seat. The feeding tank has an inlet port and an outlet port at both ends. The outlet port is used to connect to the mixing extrusion mechanism, and the inlet port is used for... The feeding mechanism is designed for feeding materials. The feeding fixing bracket is located inside the feeding tank and is equipped with a partition plate to separate the feeding port and the discharging port. The feeding fixing bracket also has a grinding channel. Both the main feeding screw and the driven feeding screw are located within the grinding channel, used to convey the material from the feeding port towards the discharging port for grinding as it passes through. A feeding connecting seat is located at one end of the feeding tank and is used to fix one end of the main feeding screw. The feeding drive mechanism is connected to the main feeding screw via a coupling. The mixing extrusion mechanism is used to mix and extrude the ground material.

[0006] A further improvement to the above scheme is that the feeding drive mechanism is a drive motor, and the feeding connection seat includes a sealing connection end plate, a tail end plate, and a connecting bearing. The sealing connection end plate is disposed at one end of the feeding tank and connected to the feeding fixed bracket. The tail end plate is disposed on one side of the sealing connection end plate and forms a connecting cavity. The connecting bearing is disposed in the connecting cavity and is used to connect one end of the feeding main screw. A spring is disposed in the connecting cavity, and the spring is sleeved on the feeding main screw, with one end abutting against the end of the connecting cavity. One end of the feeding main screw passes through the sealing connection end plate and is connected to the feeding drive mechanism through a coupling.

[0007] A further improvement to the above scheme is that two feed driven screws are provided, and the two feed driven screws are respectively engaged on both sides of the feed main screw to grind and convey the material from the feed port to the discharge port during the transmission process; a grinding gap is formed between the feed driven screw and the feed main screw for material grinding, and the opposite surfaces of the feed driven screw and the feed main screw corresponding to the grinding gap are coated with an alloy coating.

[0008] A further improvement to the above scheme is that the inside of the feed tank is provided with a partition rib, the partition rib is used to connect the partition plate, the partition plate is provided with a sealing groove, and a sealing ring is provided in the sealing groove to seal and separate the feed port and the discharge port.

[0009] A further improvement to the above scheme is that a safety valve is provided on one side of the feed tank, the feed tank is provided with a first valve port and a second valve port, the safety valve includes a valve body, a valve core and a pressure regulating element, the valve body is provided with a cavity, the valve core is disposed in the cavity, the first valve port is used to connect the feed port to the cavity, the second valve port is used to connect the discharge port to the cavity, the valve core is located between the first valve port and the second valve port, and the pressure regulating element includes an adjusting bolt and an elastic element, the two ends of the elastic element respectively abut against the adjusting bolt and the valve core to adjust the pressure borne by the valve core.

[0010] A further improvement to the above scheme is that the mixing extrusion mechanism includes a transmission box, an extrusion box, a transmission connecting shaft, a mixing extrusion screw, and a mixing conveyor. The transmission connecting shaft is disposed inside the transmission box, with one end connected to the mixing drive mechanism and the other end connected to the mixing extrusion screw. Two mixing extrusion screws are arranged side by side with their outer diameters meshing with each other. The mixing extrusion screw is disposed inside the extrusion box, which is provided with an extrusion connection port for connecting to the extrusion die.

[0011] An extrusion method for environmentally friendly recycled materials, comprising the aforementioned environmentally friendly recycled material twin-screw extruder.

[0012] Step S1, Material Components: Weigh the environmentally friendly recycled materials by weight percentage:

[0013] 50-70% recycled polyolefin particles, selected from rPP, rPE or a mixture of both;

[0014] Biomass filler 25-40%, modified wood flour or straw powder, particle size 80-120 mesh;

[0015] 3-8% reactive compatibilizer, PP-g-MAH or POE-g-MAH;

[0016] Antioxidant 0.5-1%, hindered phenols + phosphites compound;

[0017] Step S2, segmented feeding:

[0018] Recycled polyolefin granules and 50% compatibilizer were premixed in a 90°C internal mixer for 5 minutes.

[0019] The biomass filler and remaining compatibilizer were treated in a high-speed mixer at 60°C for 10 minutes.

[0020] Cryogenic grinding:

[0021] The premixed material is fed into the feed port of the twin-screw extruder;

[0022] Grinding was performed at 40±5℃ using a twin-screw rotor rotating in the same direction.

[0023] Control the grinding gap to 0.2-0.4mm, and output particle size D50≤100μm;

[0024] Vacuum extrusion:

[0025] The abrasive material enters the mixing and extrusion mechanism, with an extrusion line speed of 4-6 m / min and a melt pressure of 10±1 MPa.

[0026] A further improvement to the above scheme is that the biomass filler modification method is as follows: wood flour / straw powder is treated with 5wt% NaOH solution for 1 hour, washed with water until neutral, and then dried and mixed with 2wt% silane coupling agent at 80℃; 0.3% liquid paraffin is added as a dispersion medium when premixing recycled polyolefin particles.

[0027] A further improvement to the above scheme is that liquid nitrogen is used for cooling during the grinding stage, with a spray rate of 0.5 L / min to maintain the material temperature ≤40℃; a pressure feedback system is installed at the discharge port to automatically release pressure when the pressure is >0.4 MPa.

[0028] The ground material enters the mixing and extrusion mechanism and is extruded under the following segmented parameters:

[0029] Feeding section: temperature 155-165℃, vacuum level at atmospheric pressure, screw speed 100rpm;

[0030] Melting section: temperature 175-185℃, vacuum degree -0.09MPa, screw speed 180rpm;

[0031] Die head section: temperature is 170-180℃.

[0032] A further improvement to the above scheme is to inject 1-3% supercritical CO2 into the melting section at a pressure of 7.39 MPa and a temperature of 31°C, thereby reducing the foaming density of the material by 15-30%; and to install an online infrared thickness gauge at the die outlet to control the extrusion speed fluctuation to ≤±2% in a closed loop.

[0033] The beneficial effects of this invention are:

[0034] Compared to existing screw extruders, this invention is used for extruding environmentally friendly recycled materials. In the material input stage, the feeding extrusion mechanism has inlet and outlet ports at both ends of the feed tank. Combined with the partition plate on the feed fixing bracket, this effectively prevents unground material from flowing directly to the outlet, ensuring thorough grinding. The main feed screw and driven feed screw in the grinding channel work together to not only stably transport material from the inlet to the outlet port but also efficiently grind the material during transport, improving its dispersion and uniformity, providing a good foundation for subsequent mixing and extrusion. The feed connecting seat securely fixes one end of the main feed screw, ensuring its stability during operation, reducing vibration and wear, and extending the equipment's service life. A coupling connects the feed drive mechanism and the main feed screw, enabling efficient power transmission and precise control of the screw speed to meet the grinding requirements of different materials. The mixing extrusion mechanism mixes and extrudes the ground material, further improving the mixing uniformity and ensuring the full integration of the various components of the environmentally friendly recycled material. In this embodiment, the processing quality and production efficiency of environmentally friendly recycled materials are effectively improved, energy consumption is reduced, and waste generation is reduced.

[0035] An extrusion method for environmentally friendly recycled materials involves the rational proportioning of recycled polyolefin particles, biomass fillers, reactive compatibilizers, and antioxidants to achieve excellent overall performance. Recycled polyolefin particles provide basic mechanical and processing properties. The addition of biomass fillers not only reduces costs but also enhances the material's environmental friendliness and certain special properties, such as rigidity. Reactive compatibilizers improve the interfacial compatibility between components, resulting in a more uniform internal structure and effectively improving overall material performance. The addition of antioxidants ensures the material's stability during processing and use, extending its service life. Segmented feeding and low-temperature grinding processes significantly improve the material's dispersibility and fineness. Pre-mixing in a Banbury mixer and high-speed mixer ensures initial uniform distribution of the components, followed by grinding in a twin-screw extruder at specific temperatures and grinding intervals, outputting fine materials with a particle size D50 ≤ 100 μm, providing a good foundation for subsequent processing. The vacuum extrusion stage ensures the stability and efficiency of the extrusion process. An extrusion line speed of 4-6 m / min and a melt pressure of 10±1 MPa enable the material to be extruded smoothly, producing environmentally friendly recycled material products with stable quality and excellent performance, thus meeting the high-quality production needs of the environmentally friendly recycled material extrusion field. Attached Figure Description

[0036] Figure 1 This is a three-dimensional schematic diagram of the environmentally friendly recycled material twin-screw extruder of the present invention;

[0037] Figure 2 for Figure 1 A three-dimensional schematic diagram of the China Environmental Protection Recycling Twin-Screw Extruder from another perspective;

[0038] Figure 3 for Figure 1 A side view of the China Environmental Protection Recycled Materials Twin-Screw Extruder;

[0039] Figure 4 for Figure 1 A side view of the China Environmental Protection Recycled Materials Twin-Screw Extruder;

[0040] Figure 5 for Figure 4 Sectional view of AA;

[0041] Figure 6 for Figure 4 Sectional view of BB;

[0042] Figure 7 for Figure 1 A schematic diagram of the mixing extrusion mechanism of the China Environmental Protection Recycled Materials Twin Screw Extruder;

[0043] Figure 8 This is a schematic flowchart of the extrusion method for environmentally friendly recycled materials according to the present invention.

[0044] Explanation of reference numerals in the attached drawings: 1. Feeding drive mechanism; 2. Feeding extrusion mechanism; 21. Feed tank; 21. Feeding port; 211. Discharge port; 212. Separating rib; 213. First valve hole; 214. Second valve hole; 215. Feeding fixing bracket; 22. Separating plate; 221. Sealing groove; 2211. Grinding channel; 222. Feeding main screw; 23. Feeding driven screw; 24. Feeding connecting seat; 25. Sealing connecting end plate; 251. Tail end plate; 252. Connecting bearing; 253. Connecting cavity; 254. Safety valve; 26. Valve body; 261. Valve core; 262. Pressure regulating element; 263. Adjusting bolt; 2631. Elastic element; 2632. Mixing drive mechanism; 3. Mixing extrusion mechanism; 4. Transmission box; 41. Extrusion box; 42. Extrusion connecting port; 421. Transmission connecting shaft; 43. Mixing extrusion screw; 44. Mixing conveyor device; 45. Detailed Implementation

[0045] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0046] It should be noted that when a component is said to be "fixed to" another component, it can be directly attached to the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component.

[0047] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Figures 1-8As shown, in one embodiment of the present invention, an environmentally friendly recycled material twin-screw extruder is disclosed, comprising a feeding drive mechanism 1, a feeding extrusion mechanism 2, a mixing drive mechanism 3, and a mixing extrusion mechanism 4. The feeding drive mechanism 1 drives the feeding extrusion mechanism 2, and the mixing drive mechanism 3 drives the mixing extrusion mechanism 4. The feeding extrusion mechanism 2 is used for material input. The feeding extrusion mechanism 2 includes a feeding tank 21, a feeding fixed bracket 22, a feeding main screw 23, a feeding driven screw 24, and a feeding connecting seat 25. The feeding tank 21 has a feeding port 211 and a discharging port 212 at its two ends. The discharging port 212 is used to connect to the mixing extrusion mechanism 4, and the feeding port 211 is used for material input. Material is fed in; the feeding fixing bracket 22 is set inside the feeding tank 21, and the feeding fixing bracket 22 is provided with a partition plate 221 to separate the feeding port 211 and the discharging port 212. The feeding fixing bracket 22 is provided with a grinding channel 222, and the feeding main screw 23 and the feeding driven screw 24 are both set in the grinding channel 222 to convey the material from the feeding port 211 toward the discharging port 212 for grinding as the material passes through; the feeding connecting seat 25 is set at one end of the feeding tank 21 to fix one end of the feeding main screw 23, and the feeding drive mechanism 1 is connected to the feeding main screw 23 through a coupling; the mixing extrusion mechanism 4 is used to mix and extrude the ground material. This invention is used for the extrusion of environmentally friendly recycled materials. In the material input stage, the feed tank 21 of the feeding extrusion mechanism 2 has a feed port 211 and a discharge port 212 at both ends. Together with the partition plate 221 on the feed fixing bracket 22, this effectively prevents unground material from flowing directly to the discharge end, ensuring thorough grinding. The feed main screw 23 and the feed driven screw 24 in the grinding channel 222 work together to not only achieve stable material transport from the feed port 211 to the discharge port 212, but also efficiently grind the material during transport, improving its dispersion and uniformity, and providing a good foundation for subsequent mixed extrusion. The feed connecting seat 25 securely fixes one end of the feed main screw 23, ensuring the screw's stability during operation, reducing vibration and wear, and extending the equipment's service life. Connecting the feed drive mechanism 1 and the feed main screw 23 via a coupling enables efficient power transmission, precise control of the screw speed, and meets the grinding requirements of different materials. The mixing extrusion mechanism 4 mixes and extrudes the ground materials, further improving the mixing uniformity and ensuring full integration of the components of the environmentally friendly recycled material. In this embodiment, the processing quality and production efficiency of the environmentally friendly recycled material are effectively improved, energy consumption is reduced, and waste generation is decreased.

[0048] The feeding drive mechanism 1 is a drive motor. The feeding connection seat 25 includes a sealing connection end plate 251, a tail end plate 252, and a connecting bearing 253. The sealing connection end plate 251 is disposed at one end of the feeding tank 21 and connected to the feeding fixed bracket 22. The tail end plate 252 is disposed on one side of the sealing connection end plate 251 and forms a connecting cavity 254. The connecting bearing 253 is disposed in the connecting cavity 254 and is used to connect one end of the feeding main screw 23. A spring is disposed in the connecting cavity 254. The spring is sleeved on the feeding main screw 23 and one end abuts against the end of the connecting cavity 254. One end of the feeding main screw 23 passes through the sealing connection end plate 251 and is connected to the feeding drive mechanism 1 through a coupling. In this embodiment, the drive motor serves as the feeding drive mechanism 1, providing stable and precise power output for the feeding process. It can precisely control the feeding speed and torque according to extrusion process requirements, ensuring that recycled materials enter the extruder uniformly and continuously, greatly improving the stability and controllability of the extrusion process. The sealing connection end plate 251 of the feeding connector 25 is securely connected to the feeding tank 21 and the fixed bracket, ensuring not only the structural stability of the feeding system but also effectively preventing material leakage and meeting environmental protection requirements. The connecting bearing 253 within the connecting cavity 254 precisely supports the feeding main screw 23, reducing radial and axial runout during operation, improving the smoothness of screw rotation, and extending the service life of the screw and related components. A spring is sleeved on the feeding main screw 23 and abuts against the end of the connecting cavity 254, buffering the vibration and impact generated by the screw during operation and preventing uneven material conveying due to excessive vibration. Meanwhile, the feeding drive mechanism 1 and the main feeding screw 23 are connected by a coupling, which can efficiently transmit power, compensate for the relative displacement between the two shafts, and further ensure the efficient operation of the entire feeding system.

[0049] Two driven screws 24 are provided, each meshing with one side of the main feed screw 23 to grind and convey material from the feed port 211 towards the discharge port 212 during transmission. A grinding gap is formed between the driven screws 24 and the main feed screw 23 for material grinding. The surfaces of the driven screws 24 and the main feed screw 23 corresponding to the grinding gap are coated with an alloy coating. In this embodiment, the two driven screws 24 meshing with one side of the main feed screw 23 ensure that the material receives uniform and stable conveying power during transmission. The grinding and conveying process from the feed port 211 to the discharge port 212 is smoother, effectively avoiding material accumulation and blockage, and greatly improving the working efficiency and continuity of the extruder. The grinding gap formed between the driven screws 24 and the main feed screw 23 can fully grind the environmentally friendly recycled material, making the material particles finer and more evenly distributed, improving the mixing quality and plasticization degree of the material. This is crucial for the extrusion processing of environmentally friendly recycled materials, helping to improve the physical properties and appearance quality of the final product. Applying an alloy coating to the opposing surfaces of the corresponding grinding gap enhances the wear resistance and corrosion resistance of the screw surface. Because environmentally friendly recycled materials have complex compositions and may contain various impurities and corrosive substances, the alloy coating effectively resists these factors, extending the screw's service life and reducing equipment maintenance costs.

[0050] The feed tank 21 has internal partition ribs 213, which connect to a partition plate 221. The partition plate 221 has a sealing groove 2211 containing a sealing ring to seal the feed port 211 and discharge port 212. In this embodiment, the partition ribs 213 connect to the partition plate 221, effectively enhancing the structural stability of the partition plate 221 and ensuring reliable separation even under feed pressure and material flow impact. The design of the sealing groove 2211 and the sealing ring achieves precise and efficient sealing of the feed port 211 and discharge port 212. The sealing structure prevents cross-contamination of different materials during the feeding stage, ensuring that various environmentally friendly recycled materials entering the twin-screw extruder are transported according to a predetermined ratio and path, greatly improving the accuracy and stability of material mixing, and thus enhancing the uniformity of extruded product quality. The seal also prevents material leakage, reduces contamination and corrosion to other internal components, and extends the equipment's service life.

[0051] A safety valve 26 is provided on one side of the feed tank 21. The feed tank 21 has a first valve port 214 and a second valve port 215. The safety valve 26 includes a valve body 261, a valve core 262, and a pressure regulating element 263. The valve body 261 has a cavity, and the valve core 262 is disposed within the cavity. The first valve port 214 connects the feed port 211 to the cavity, and the second valve port 215 connects the discharge port 212 to the cavity. The valve core 262 is located between the first valve port 214 and the second valve port 215. The pressure regulating element 263 includes an adjusting bolt 2631 and an elastic element 2632. The two ends of the elastic element 2632 abut against the adjusting bolt 2631 and the valve core 262, respectively, to adjust the pressure borne by the valve core 262. In this embodiment, the safety valve 26 ensures the safety of the feeding process. During the extrusion of environmentally friendly recycled materials, the characteristics of the material and factors such as the production environment may cause an abnormal increase in pressure within the feed tank 21. At this time, the safety valve 26 can respond promptly. When the pressure inside the tank reaches the set value, the valve core 262, under pressure, overcomes the resistance of the elastic element 2632 and displaces, connecting the first valve port 214 and the second valve port 215, releasing some pressure and preventing dangerous situations such as tank rupture due to overpressure, thus ensuring the safety of equipment and operators. This also helps stabilize the extrusion process. Stable feed pressure is key to ensuring uniform and stable extrusion of environmentally friendly recycled materials by the twin-screw extruder. Through the pressure regulating element 263, operators can precisely adjust the pressure borne by the valve core 262 according to the extrusion requirements of different materials, thereby maintaining the feed tank 21 within a suitable pressure range, allowing the material to enter the extruder at a stable flow rate, improving the quality and consistency of the extruded product.

[0052] See Figure 7As shown, the mixing extrusion mechanism 4 includes a transmission box 41, an extrusion box 42, a transmission connecting shaft 43, a mixing extrusion screw 44, and a mixing conveyor device 45. The transmission connecting shaft 43 is located inside the transmission box 41. One end of the transmission connecting shaft 43 is connected to the mixing drive mechanism 3, and the other end is connected to the mixing extrusion screw 44. Two mixing extrusion screws 44 are arranged side by side with their outer diameters meshing with each other. The mixing extrusion screws 44 are located inside the extrusion box 42, which is provided with an extrusion connection port 421 for connecting to the extrusion die. In this embodiment, the design of two mixing extrusion screws 44 with their outer diameters meshing with each other greatly improves the mixing uniformity of environmentally friendly recycled materials. During the rotation of the screws, recycled materials with different properties and particle sizes are fully stirred and kneaded, ensuring that the various performance indicators of the materials reach a high degree of consistency before extrusion, effectively avoiding quality defects in extruded products caused by uneven material distribution. Secondly, the transmission box 41 and the extrusion box 42 achieve efficient and stable power transmission through the reasonable arrangement of the transmission connecting shaft 43. The power of the hybrid drive mechanism 3 is accurately transmitted to the hybrid extrusion screw 44 via the transmission connection shaft 43, ensuring the stability and controllability of the screw speed, thereby providing stable pressure and flow for the extrusion process, which helps to produce environmentally friendly recycled material products with high dimensional accuracy and stable quality.

[0053] See Figures 1-8 As shown, an extrusion method for environmentally friendly recycled materials includes the aforementioned environmentally friendly recycled material twin-screw extruder.

[0054] Step S1, Material Components: Environmentally friendly recycled materials are weighed by weight percentage as follows: 50-70% recycled polyolefin particles, selected from rPP, rPE or a mixture of both; 25-40% biomass filler, modified wood flour or straw powder, particle size 80-120 mesh; 3-8% reactive compatibilizer, PP-g-MAH or POE-g-MAH; 0.5-1% antioxidant, hindered phenols + phosphite compound;

[0055] Step S2, segmented feeding: Recycled polyolefin particles and 50% compatibilizer are premixed in a 90°C internal mixer for 5 minutes; biomass filler and the remaining compatibilizer are treated in a 60°C high-speed mixer for 10 minutes.

[0056] Low-temperature grinding: The premixed material is fed into the feed port 211 of the twin-screw extruder; it is ground at 40±5℃ by the co-rotating twin screws; the grinding gap is controlled at 0.2-0.4mm, and the output particle size D50≤100μm;

[0057] Vacuum extrusion: The abrasive material enters the mixing and extrusion mechanism 4, the extrusion line speed is 4-6 m / min, and the melt pressure is 10±1 MPa.

[0058] In this embodiment, the selection of material components involves a rational ratio of recycled polyolefin particles, biomass fillers, reactive compatibilizers, and antioxidants, resulting in a material with excellent overall performance. Recycled polyolefin particles provide basic mechanical and processing properties. The addition of biomass fillers not only reduces costs but also improves the material's environmental friendliness and certain special properties, such as rigidity. Reactive compatibilizers enhance the interfacial compatibility between components, making the internal structure of the material more uniform, thereby effectively improving the overall performance of the material. The addition of antioxidants ensures the stability of the material during processing and use, extending its service life. Segmented feeding and low-temperature grinding processes greatly improve the dispersibility and fineness of the material. Premixing in an internal mixer and high-speed mixer allows for initial uniform distribution of the components, followed by grinding in a twin-screw extruder at specific temperatures and grinding gaps, outputting fine materials with a particle size D50 ≤ 100 μm, providing a good foundation for subsequent processing. The vacuum extrusion process ensures the stability and efficiency of the extrusion process. An extrusion line speed of 4-6 m / min and a melt pressure of 10±1 MPa enable the material to be extruded smoothly, producing environmentally friendly recycled material products with stable quality and excellent performance, thus meeting the high-quality production needs of the environmentally friendly recycled material extrusion field.

[0059] The biomass filler modification method is as follows: wood flour / straw powder is treated with 5wt% NaOH solution for 1 hour, washed with water until neutral, and then dried and mixed with 2wt% silane coupling agent at 80℃; 0.3% liquid paraffin is added as a dispersion medium during the premixing of recycled polyolefin particles. In this embodiment, for the biomass filler, treating wood flour / straw powder with 5wt% NaOH solution for 1 hour and then washing with water until neutral effectively removes impurities, hemicellulose, and some lignin, increases the active sites on the filler surface, and improves its interfacial bonding ability with the polymer matrix. Subsequently, it is dried and mixed with 2wt% silane coupling agent at 80℃. The silane coupling agent can form chemical bonds between the filler and the polymer, further improving their compatibility, so that the biomass filler can be better dispersed in the recycled polyolefin matrix during twin-screw extrusion, enhancing the mechanical properties of the composite material. Adding 0.3% liquid paraffin as a dispersion medium during the premixing of recycled polyolefin particles provides good lubricity and dispersibility. In a twin-screw extruder, it can reduce the friction between materials, reduce material agglomeration, and make the recycled polyolefin particles and modified biomass fillers more evenly distributed, which helps to improve the flowability of materials and ensure the stability and continuity of the extrusion process.

[0060] During the grinding stage, liquid nitrogen is used for assisted cooling at a spray rate of 0.5 L / min to maintain the material temperature ≤40℃. A pressure feedback system is installed at the discharge port 212, automatically releasing pressure when it exceeds 0.4 MPa. The ground material then enters the mixing and extrusion mechanism 4, where it is extruded under the following segmented parameters: Feeding section: temperature 155-165℃, vacuum at atmospheric pressure, screw speed 100 rpm; Melting section: temperature 175-185℃, vacuum -0.09 MPa, screw speed 180 rpm; Die section: temperature 170-180℃. In this embodiment, the use of liquid nitrogen for assisted cooling and precise control of the spray rate at 0.5 L / min during the grinding stage effectively maintains the material temperature ≤40℃. This measure prevents degradation and performance deterioration caused by heat generated during grinding, preserving the original characteristics of the environmentally friendly recycled material to the greatest extent and ensuring its stable physical and chemical properties. The pressure feedback system at the discharge port 212 automatically releases pressure when it exceeds 0.4 MPa, providing reliable safety assurance for the entire extrusion process. This prevents equipment damage due to excessive pressure, reduces the risk of production accidents, and improves the stability and continuity of equipment operation. After entering the mixing extrusion mechanism 4, the precise setting of parameters for each section plays a crucial role. The feeding section temperature is maintained at 155-165℃, the vacuum degree is at atmospheric pressure, and the screw speed is 100 rpm, which facilitates uniform material feeding and lays a good foundation for subsequent processing. The melting section temperature is increased to 175-185℃, the vacuum degree reaches -0.09 MPa, and the screw speed is 180 rpm, enabling the material to fully melt and plasticize, remove volatiles, and improve the homogeneity and flowability of the material. The die head temperature is controlled at 170-180℃ to ensure the forming quality of the extruded material, resulting in high dimensional accuracy and good appearance quality in the final environmentally friendly recycled material products.

[0061] In this embodiment, the injection of supercritical CO2 reduces the foam density of the material by 15-30% at a pressure of 7.39 MPa and a temperature of 31°C. An online infrared thickness gauge is installed at the die outlet, and the extrusion speed fluctuation is controlled within ≤±2% in a closed loop. In this embodiment, the injection of supercritical CO2 reduces the foam density of the material by 15-30%, optimizing the physical properties of the product. The foamed material maintains a certain strength while significantly reducing its weight, thus reducing the amount of raw materials used and improving the product's heat insulation, sound insulation, and other properties, broadening the application areas of environmentally friendly recycled materials. The online infrared thickness gauge at the die outlet, with closed-loop control, keeps the extrusion speed fluctuation within ≤±2%. Precise speed control ensures the uniformity of the extruded product thickness, greatly improving the stability of product quality. The reduction in thickness deviation makes the product more reliable in subsequent processing and use, reducing the defect rate caused by uneven thickness, and improving production efficiency and economic benefits. Precise control also meets the high-quality manufacturing requirements of environmentally friendly recycled materials, helping to promote the widespread application of environmentally friendly recycled materials in more fields.

[0062] The above embodiments merely illustrate several implementation methods of the present invention, and their descriptions are relatively specific and detailed, but 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 all fall within the protection scope of the present invention. Therefore, the protection scope of this patent should be determined by the appended claims.

Claims

1. An environmentally friendly twin-screw extruder for recycled materials, characterized in that: The system includes a feeding drive mechanism, a feeding extrusion mechanism, a mixing drive mechanism, and a mixing extrusion mechanism. The feeding drive mechanism drives the feeding extrusion mechanism, and the mixing drive mechanism drives the mixing extrusion mechanism. The feeding extrusion mechanism is used for material input. The feeding extrusion mechanism includes a feeding tank, a feeding fixed bracket, a feeding main screw, a feeding driven screw, and a feeding connecting seat. The feeding tank has an inlet port and an outlet port at both ends. The outlet port is used to connect to the mixing extrusion mechanism, and the inlet port is used to input material. The feeding fixed bracket... The feeding device is housed within the feeding tank. A partition plate separates the feeding port and the discharge port. A grinding channel is provided within the feeding channel, and both the main feeding screw and the driven feeding screw are located within it. This channel transports the material from the feeding port towards the discharge port for grinding as it passes through. A feeding connector is located at one end of the feeding tank to fix one end of the main feeding screw. The feeding drive mechanism is connected to the main feeding screw via a coupling. The mixing and extrusion mechanism is used to mix and extrude the ground material. The feeding drive mechanism is a drive motor. The feeding connection seat includes a sealing connection end plate, a tail end plate, and a connecting bearing. The sealing connection end plate is located at one end of the feeding tank and connected to the feeding fixed bracket. The tail end plate is located on one side of the sealing connection end plate and forms a connecting cavity. The connecting bearing is located in the connecting cavity and is used to connect one end of the feeding main screw. A spring is installed in the connecting cavity. The spring is sleeved on the feeding main screw, and one end of the spring abuts against the end of the connecting cavity. One end of the feeding main screw passes through the sealing connection end plate and is connected to the feeding drive mechanism through a coupling. There are two feed driven screws, which are respectively engaged with the two sides of the feed main screw to grind and convey the material from the feed port to the discharge port during the transmission process; a grinding gap is formed between the feed driven screw and the feed main screw for material grinding, and the opposite surfaces of the feed driven screw and the feed main screw corresponding to the grinding gap are coated with an alloy coating. The feed tank is provided with a partition rib inside, which is used to connect the partition plate. The partition plate is provided with a sealing groove, and a sealing ring is provided in the sealing groove to seal and separate the feed port and the discharge port. A safety valve is provided on one side of the feed tank. The feed tank has a first valve port and a second valve port. The safety valve includes a valve body, a valve core, and a pressure regulating element. A cavity is provided inside the valve body, and the valve core is disposed in the cavity. The first valve port is used to connect the feed port to the cavity, and the second valve port is used to connect the discharge port to the cavity. The valve core is located between the first valve port and the second valve port. The pressure regulating element includes an adjusting bolt and an elastic element. The two ends of the elastic element abut against the adjusting bolt and the valve core, respectively, to adjust the pressure borne by the valve core.

2. The environmentally friendly twin-screw extruder for recycled materials according to claim 1, characterized in that: The hybrid extrusion mechanism includes a transmission box, an extrusion box, a transmission connecting shaft, a hybrid extrusion screw, and a hybrid conveyor. The transmission connecting shaft is located inside the transmission box. One end of the transmission connecting shaft is connected to the hybrid drive mechanism, and the other end is connected to the hybrid extrusion screw. Two hybrid extrusion screws are arranged in parallel with their outer diameters meshing with each other. The hybrid extrusion screw is located inside the extrusion box, and the extrusion box is provided with an extrusion connection port for connecting to the extrusion die.

3. A method for extruding environmentally friendly recycled materials, characterized in that: Including the environmentally friendly recycled material twin-screw extruder as described in any one of claims 1 to 2, Step S1, Material Components: Weigh the environmentally friendly recycled materials by weight percentage: 50-70% recycled polyolefin particles, selected from rPP, rPE or a mixture of both; Biomass filler 25-40%, modified wood flour or straw powder, particle size 80-120 mesh; 3-8% reactive compatibilizer, PP-g-MAH or POE-g-MAH; Antioxidant 0.5-1%, hindered phenols + phosphites compound; Step S2, segmented feeding: Recycled polyolefin granules and 50% compatibilizer were premixed in a 90°C internal mixer for 5 minutes. The biomass filler and remaining compatibilizer were treated in a high-speed mixer at 60°C for 10 minutes. Cryogenic grinding: The premixed material is fed into the feed port of the twin-screw extruder; Grinding was performed at 40±5℃ using a twin-screw rotor rotating in the same direction. Control the grinding gap to 0.2-0.4mm, and output particle size D50≤100μm; Vacuum extrusion: The abrasive material enters the mixing and extrusion mechanism, with an extrusion line speed of 4-6 m / min and a melt pressure of 10±1 MPa.

4. The extrusion method for environmentally friendly recycled materials according to claim 3, characterized in that: The biomass filler modification method is as follows: wood flour / straw powder is treated with 5wt% NaOH solution for 1 hour, washed with water until neutral, and then dried and mixed with 2wt% silane coupling agent at 80℃; 0.3% liquid paraffin is added as a dispersion medium when premixing recycled polyolefin particles.

5. The extrusion method for environmentally friendly recycled materials according to claim 3, characterized in that: Liquid nitrogen is used for cooling during the grinding stage, with a spray rate of 0.5 L / min, to maintain the material temperature at ≤40℃; a pressure feedback system is installed at the discharge port to automatically release pressure when the pressure is >0.4 MPa. The ground material enters the mixing and extrusion mechanism and is extruded under the following segmented parameters: Feeding section: temperature 155-165℃, vacuum level at atmospheric pressure, screw speed 100rpm; Melting section: temperature 175-185℃, vacuum degree -0.09MPa, screw speed 180rpm; Die head section: temperature is 170-180℃.

6. The extrusion method for environmentally friendly recycled materials according to claim 3, characterized in that: The melting section is injected with 1-3% supercritical CO2 at a pressure of 7.39 MPa and a temperature of 31°C, which reduces the foaming density of the material by 15-30%. An online infrared thickness gauge is installed at the die outlet to control the extrusion speed fluctuation to ≤±2% in a closed loop.

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