Environment-friendly recycled material double-screw extruder and method

Abstract

The invention relates to the technical field of environment-friendly recycled material production equipment, in particular to an environment-friendly recycled material double-screw extruder and a method. The environment-friendly recycled material double-screw extruder comprises a feeding driving mechanism, a feeding extruding mechanism, a mixing driving mechanism and a mixing extruding mechanism; the mixing driving mechanism is used for driving the mixing extrusion mechanism, the feeding extrusion mechanism is used for feeding materials, the feeding extrusion mechanism comprises a feeding tank body, a feeding fixing support, a feeding main screw rod, a feeding driven screw rod and a feeding connecting base, and a feeding port and a discharging port are formed in the two ends of the feeding tank body respectively. And the discharging port is used for being connected with a mixing and extruding mechanism. The feeding main screw and the feeding driven screw in the grinding channel cooperatively operate, so that materials are stably conveyed from the feeding port to the discharging port, the materials are efficiently ground in the conveying process, and the dispersity and uniformity of the materials are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of environmental protection and recycled material production equipment, and particularly to a twin-screw extruder and method for environmental protection and recycled materials. Background Art

[0002] With the increasingly prominent global resource and environmental problems, sustainable development has become an important development direction for all industries. The recycling and utilization of recycled materials, as a key link in resource recycling, have received extensive attention. There are many problems in the traditional production process of recycled materials, which are difficult to meet the requirements of modern industry for efficient, precise, and environmentally friendly production. In this context, the intelligent production line for recycled materials has emerged.

[0003] During the extrusion process of recycled materials, a screw extruder is required for extrusion production. However, the existing extruder structure is relatively simple, and no pretreatment is carried out on some recycled materials, resulting in problems such as insufficient stability and material dispersion in the subsequent extrusion process. Therefore, new improvements need to be made to the existing extrusion mechanism. Summary of the Invention

[0004] To solve the above problems, the main feeding screw and the driven feeding screw in the grinding channel of the present invention cooperate to not only achieve the stable transportation of materials from the feeding port to the discharging port, but also efficiently grind the materials during the transportation process, which helps to improve the dispersion and uniformity of the materials. The present invention provides a twin-screw extruder and method for environmental protection and recycled materials.

[0005] The technical solution adopted by the present invention is as follows: A twin-screw extruder for environmental protection and recycled materials includes a feeding drive mechanism, a feeding extrusion mechanism, a mixing drive mechanism, and a mixing extrusion mechanism. The feeding drive mechanism is used to drive the feeding extrusion mechanism, and the mixing drive mechanism is used to drive the mixing extrusion mechanism. The feeding extrusion mechanism is used for material input. The feeding extrusion mechanism includes a feeding tank body, a feeding fixed bracket, a main feeding screw, a driven feeding screw, and a feeding connection seat. The two ends of the feeding tank body are respectively provided with a feeding port and a discharging port. The discharging port is used to connect the mixing extrusion mechanism, and the feeding port is used to input materials. The feeding fixed bracket is arranged inside the feeding tank body. The feeding fixed bracket is provided with a partition plate for separating the feeding port and the discharging port. The feeding fixed bracket is provided with a grinding channel. The main feeding screw and the driven feeding screw are both arranged in the grinding channel for transporting materials from the feeding port towards the discharging port to grind the materials when they pass through. The feeding connection seat is arranged at one end of the feeding tank body for fixing one end of the main feeding screw. The feeding drive mechanism is connected to the main feeding screw through a coupling. The mixing extrusion mechanism is used to mix and extrude the ground materials.

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

[0007] A further improvement to the above solution is that there are two feeding driven screws. The two feeding driven screws are respectively meshed on both sides of the main feeding screw to grind and convey the material from the feeding port towards the discharging port during the transmission process. A grinding gap is formed between the feeding driven screw and the main feeding screw for material grinding. The opposite surfaces of the feeding driven screw and the main feeding screw corresponding to the grinding gap are alloy spraying coatings.

[0008] A further improvement to the above solution is that partition ribs are arranged inside the feeding tank body. The partition ribs are used to connect partition plates. The partition plates are provided with sealed grooves, and sealing rings are arranged in the sealed grooves to be used for sealing and partitioning the feeding port and the discharging port.

[0009] A further improvement to the above solution is that a safety valve is arranged on one side of the feeding tank body. The feeding tank body is provided with a first valve hole and a second valve hole. The safety valve includes a valve body, a valve core, and a pressure regulating element. A cavity is arranged inside the valve body. The valve core is arranged in the cavity. The first valve hole is used to connect the feeding port with the cavity. The second valve hole is used to connect the discharging port with the cavity. The valve core is located between the first valve hole and the second valve hole. The pressure regulating element includes an adjusting bolt and an elastic element. Two ends of the elastic element respectively abut against the adjusting bolt and the valve core to regulate the pressure borne by the valve core.

[0010] A further improvement to the above solution is that the mixing and extrusion mechanism includes a transmission box, an extrusion box, a transmission connecting shaft, a mixing and extrusion screw, and a mixing and feeding device. The transmission connecting shaft is arranged inside the transmission box. One end of the transmission connecting shaft is connected to the mixing drive mechanism and the other end is connected to the mixing and extrusion screw. Two mixing and extrusion screws are arranged in parallel and their outer diameters are meshed with each other. The mixing and extrusion screws are arranged inside the extrusion box. The extrusion box is provided with an extrusion connection port for connecting an extrusion die.

[0011] An extrusion method for an environmentally friendly recycled material, including the environmentally friendly recycled material twin-screw extruder as described above. Step S1, Material Components: The environmentally friendly recycled materials are weighed by weight percentage as follows: 50 - 70% of recycled polyolefin particles, selected from rPP, rPE or a mixture of both; 25 - 40% of biomass filler, modified wood powder or straw powder, with a particle size of 80 - 120 mesh; 3 - 8% of reactive compatibilizer, PP - g - MAH or POE - g - MAH; 0.5 - 1% of antioxidant, a compound of hindered phenol and phosphite ester; Step S2, Feeding in Stages: The recycled polyolefin particles and 50% of the compatibilizer are premixed in a kneader at 90°C for 5 minutes; The biomass filler and the remaining compatibilizer are processed in a high - speed mixer at 60°C for 10 minutes; Low - temperature Grinding: The premixed material is fed into the feeding port of a twin - screw extruder; It is ground by a co - rotating twin - screw at 40 ± 5°C; The grinding gap is controlled at 0.2 - 0.4 mm, and the output particle size D50 ≤ 100 μm; Vacuum Extrusion: The ground material enters the mixing and extrusion mechanism, with an extrusion linear speed of 4 - 6 m / min and a melt pressure of 10 ± 1 MPa.

[0012] A further improvement to the above - mentioned solution is that the method for modifying the biomass filler is as follows: The wood powder / straw powder is treated with a 5wt% NaOH solution for 1 hour, washed to neutral, and then dried and mixed with a 2wt% silane coupling agent at 80°C; 0.3% liquid paraffin is added as a dispersion medium during the premixing of the recycled polyolefin particles.

[0013] A further improvement to the above - mentioned solution is that during the grinding stage, liquid nitrogen is used to assist in cooling, with a spraying amount of 0.5 L / min to maintain the material temperature ≤ 40°C; a pressure feedback system is set at the discharge port to automatically relieve pressure when the pressure > 0.4 MPa; The grinding material enters the mixing and extrusion mechanism and is extruded under the following sectional parameters: Feeding section: The temperature is 155 - 165°C, the vacuum degree is atmospheric pressure, and the screw speed is 100 rpm; Melting section: The temperature is 175 - 185°C, the vacuum degree is - 0.09 MPa, and the screw speed is 180 rpm; Die head section: The temperature is 170 - 180°C.

[0014] A further improvement to the above - mentioned solution is that 1 - 3% of supercritical CO2 is injected into the melting section at a pressure of 7.39 MPa and a temperature of 31°C, reducing the foaming density of the material by 15 - 30%; an on - line infrared thickness gauge is set at the die head outlet to close - loop control the extrusion speed fluctuation ≤ ± 2%.

[0015] The beneficial effects of the present invention are as follows: Compared with the existing screw extruders, the present invention is used for extruding environmentally friendly recycled materials. In the material input link, the feeding tank body of the feeding and extruding mechanism is respectively provided with a feeding port and a discharging port at both ends, and cooperating with the partition plate on the feeding fixing bracket, it can effectively prevent the unground materials from directly flowing to the discharging end, ensuring that the materials are fully ground. The main feeding screw and the driven feeding screw in the grinding channel cooperate with each other, not only realizing the stable transportation of the materials from the feeding port to the discharging port, but also efficiently grinding the materials during the transportation process, which helps to improve the dispersibility and uniformity of the materials, providing a good foundation for subsequent mixing and extrusion. The feeding connecting seat firmly fixes one end of the main feeding screw, ensuring the stability of the screw during operation, reducing vibration and wear, and extending the service life of the equipment. By connecting the feeding driving mechanism and the main feeding screw through a coupling, efficient power transmission can be achieved, accurately controlling the screw speed to meet the grinding requirements of different materials. The mixing and extruding mechanism mixes and extrudes the ground materials, further improving the mixing uniformity of the materials and enabling the components of the environmentally friendly recycled materials to be fully integrated. In this embodiment, the processing quality and production efficiency of the environmentally friendly recycled materials are effectively improved, the energy consumption is reduced, and the generation of waste materials is reduced.

[0016] An extrusion method for environmentally friendly recycled materials. In terms of material component selection, the recycled polyolefin particles, biomass filler, reactive compatibilizer, and antioxidant are rationally proportioned to enable the material to have good comprehensive performance. The recycled polyolefin particles provide basic mechanical properties and processing properties. The addition of the biomass filler not only reduces costs but also improves the environmental friendliness and certain special properties of the material, such as rigidity. The reactive compatibilizer enhances the interfacial compatibility between the components, making the internal structure of the material more uniform, thereby effectively improving the overall performance of the material. The addition of the antioxidant ensures the stability of the material during processing and use, extending its service life. The segmented feeding and low-temperature grinding processes greatly improve the dispersibility and refinement degree of the material. The premixing treatment by a mixer and a high-speed mixer enables the components to be initially evenly distributed, and then ground by a twin-screw extruder at a specific temperature and grinding gap to output fine materials with a particle size D50≤100μm, providing a good foundation for subsequent processing. The vacuum extrusion link ensures the stability and efficiency of the extrusion process. The extrusion line speed of 4 - 6m / min and the melt pressure of 10±1MPa enable the materials to be smoothly extruded and formed, producing environmentally friendly recycled material products with stable quality and excellent performance, meeting the high-quality production requirements in the field of environmentally friendly recycled material extrusion. Brief Description of the Drawings

[0017] Figure 1 is a three-dimensional schematic diagram of the twin-screw extruder for environmentally friendly recycled materials of the present invention; Figure 2 is Figure 1Stereoscopic schematic diagram of the dual-screw extruder for environmentally friendly recycled materials from another perspective; Figure 3 is Figure 1 Side view schematic diagram of the dual-screw extruder for environmentally friendly recycled materials; Figure 4 is Figure 1 Side view schematic diagram of the dual-screw extruder for environmentally friendly recycled materials; Figure 5 is Figure 4 Cross-sectional view of A-A in the middle; Figure 6 is Figure 4 Cross-sectional view of B-B in the middle; Figure 7 is Figure 1 Structural schematic diagram of the mixing and extrusion mechanism of the dual-screw extruder for environmentally friendly recycled materials; Figure 8 Flow schematic diagram of the extrusion method of the environmentally friendly recycled materials of the present invention.

[0018] Explanation of reference numerals: feeding drive mechanism 1, feeding extrusion mechanism 2, feeding tank body 21, feeding port 211, discharging port 212, dividing rib 213, first valve hole 214, second valve hole 215, feeding fixing bracket 22, dividing plate 221, sealing groove 2211, grinding channel 222, feeding main screw 23, feeding driven screw 24, feeding connecting seat 25, sealing connection 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 connection port 421, transmission connection shaft 43, mixing extrusion screw 44, mixing material feeding device 45. Detailed implementation manners

[0019] For the convenience of understanding the present invention, the present invention will be described more comprehensively below with reference to the relevant drawings. Preferred embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0020] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly on the other element or there may also be an intermediate element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intermediate element at the same time.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this invention belongs. The terms used in the description of this invention herein are for the purpose of describing specific embodiments only and are not intended to limit the invention. As Figures 1 to 8 As shown, in an embodiment of the present invention, an environmentally friendly recycled material twin-screw extruder is involved, which includes 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 is used to drive the feeding extrusion mechanism 2, and the mixing drive mechanism 3 is used to drive the mixing extrusion mechanism 4. The feeding extrusion mechanism 2 is used for material input. The feeding extrusion mechanism 2 includes a feeding tank body 21, a feeding fixed bracket 22, a feeding main screw 23, a feeding driven screw 24, and a feeding connection seat 25. The two ends of the feeding tank body 21 are respectively provided with a feeding port 211 and a discharge port 212. The discharge port 212 is used to connect the mixing extrusion mechanism 4, and the feeding port 211 is used to input materials. The feeding fixed bracket 22 is arranged inside the feeding tank body 21. The feeding fixed bracket 22 is provided with a partition plate 221 for separating the feeding port 211 and the discharge port 212. The feeding fixed bracket 22 is provided with a grinding channel 222. The feeding main screw 23 and the feeding driven screw 24 are both arranged in the grinding channel 222 for conveying materials from the feeding port 211 towards the discharge port 212 to grind the materials when they pass through. The feeding connection seat 25 is arranged at one end of the feeding tank body 21 for fixing one end of the feeding main screw 23. The feeding drive mechanism 1 and the feeding main screw 23 are connected by a coupling. The mixing extrusion mechanism 4 is used to mix and extrude the ground materials. This invention is used for extruding environmentally friendly recycled materials. In the material input link, the feeding port 211 and the discharge port 212 are respectively arranged at both ends of the feeding tank body 21 of the feeding extrusion mechanism 2. Cooperating with the partition plate 221 on the feeding fixed bracket 22, it can effectively prevent unground materials from directly flowing to the discharge end and ensure that the materials are fully ground. The feeding main screw 23 and the feeding driven screw 24 in the grinding channel 222 cooperate to not only realize the stable conveying of materials from the feeding port 211 to the discharge port 212, but also efficiently grind the materials during the conveying process, which helps to improve the dispersibility and uniformity of the materials and provides a good foundation for subsequent mixing and extrusion. The feeding connection seat 25 firmly fixes one end of the feeding main screw 23, ensuring the stability of the screw during operation, reducing vibration and wear, and extending the service life of the equipment. By connecting the feeding drive mechanism 1 and the feeding main screw 23 through a coupling, efficient power transmission can be achieved, and the screw speed can be accurately controlled to meet the grinding requirements of different materials. The mixing extrusion mechanism 4 mixes and extrudes the ground materials to further improve the mixing uniformity of the materials and make the components of the environmentally friendly recycled materials fully blend. In this embodiment, the processing quality and production efficiency of the environmentally friendly recycled materials are effectively improved, energy consumption is reduced, and waste generation is reduced.

[0022] The feed drive mechanism 1 is a drive motor, and the feed 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 arranged at one end of the feed tank body 21 and is connected to the feed fixed bracket 22. The tail end plate 252 is arranged on one side of the sealing connection end plate 251 and forms a connecting cavity 254. The connecting bearing 253 is arranged in the connecting cavity 254 and is used to connect one end of the feed main screw 23. A spring is arranged in the connecting cavity 254. The spring is sleeved on the feed main screw 23, and one end abuts against the end of the connecting cavity 254; one end of the feed main screw 23 passes through the sealing connection end plate 251 and is connected to the feed drive mechanism 1 through a coupling. In this embodiment, the driving motor serves as the feeding drive mechanism 1, which provides stable and accurate power output for the feeding process. It can accurately control the feeding speed and torque according to the extrusion process requirements, ensure that the recycled materials enter the extruder evenly and continuously, and greatly improve the stability and controllability of the extrusion process. The sealing connection end plate 251 of the feeding connection seat 25 is firmly connected to the feeding tank body 21 and the fixed bracket, which not only ensures the structural stability of the feeding system, but also effectively prevents material leakage and meets environmental protection requirements. The connecting bearing 253 in the connecting cavity 254 accurately supports the feeding main screw 23, reduces radial and axial runout during operation, improves the stability of the screw rotation, and extends the service life of the screw and related components. The spring sleeve is arranged on the feeding main screw 23 and abuts against the end of the connecting cavity 254, which can buffer the vibration and impact generated by the screw during operation and avoid the problem of uneven material transportation caused by excessive vibration. At the same time, the feed drive mechanism 1 and the feed main screw 23 are connected through a coupling, which can efficiently transmit power and compensate for the relative displacement between the two shafts, further ensuring the efficient operation of the entire feed system.

[0023] There are two feeding driven screws 24, and the two feeding driven screws 24 are respectively meshed on both sides of the feeding main screw 23 to grind and convey the material from the feeding port 211 towards the discharging port 212 during the transmission process; a grinding gap is formed between the feeding driven screw 24 and the feeding main screw 23 for material grinding, and the opposite surfaces of the feeding driven screw 24 and the feeding main screw 23 corresponding to the grinding gap are alloy spraying coatings. In this embodiment, the two feeding driven screws 24 are respectively meshed on both sides of the feeding main screw 23, which can ensure that the material obtains uniform and stable conveying power during the transmission process. The grinding and conveying process from the feeding port 211 to the discharging port 212 is smoother, effectively avoiding the phenomenon of material accumulation and blockage, and greatly improving the working efficiency and continuity of the extruder. The grinding gap formed between the feeding driven screw 24 and the feeding main screw 23 can fully grind the environmentally friendly recycled material, making the material particles finer and evenly distributed, and improving the mixing quality and plasticization degree of the material. It is crucial for the extrusion processing of environmentally friendly recycled materials and helps to improve the physical properties and appearance quality of the final product. The alloy spraying coating is adopted on the opposite surfaces corresponding to the grinding gap, improving the wear resistance and corrosion resistance of the screw surface. Since the environmentally friendly recycled material has a complex composition and may contain various impurities and corrosive substances, the alloy spraying coating can effectively resist the erosion of these factors, extend the service life of the screw, and reduce the equipment maintenance cost.

[0024] Partition ribs 213 are arranged inside the feeding tank body 21, and the partition ribs 213 are used to connect the partition plate 221. The partition plate 221 is provided with a sealing groove 2211, and a sealing ring is arranged in the sealing groove 2211 for sealing and partitioning the feeding port 211 and the discharging port 212. In this embodiment, the partition ribs 213 connect the partition plate 221, which can effectively enhance the structural stability of the partition plate 221 and ensure its reliable partitioning function when bearing the feeding pressure and the impact of material flow. The design of the sealing groove 2211 and the sealing ring realizes precise and efficient sealing of the feeding port 211 and the discharging port 212. The sealing structure can prevent the phenomenon of material mixing during the feeding stage, ensure that various environmentally friendly recycled materials entering the twin-screw extruder are conveyed according to the predetermined ratio and path, greatly improving the accuracy and stability of material mixing, and further enhancing the uniformity of the quality of the extruded product. Sealing can avoid material leakage, reduce the pollution and erosion of other components inside the equipment, and extend the service life of the equipment.

[0025] A safety valve 26 is provided on one side of the feeding tank body 21. The feeding tank body 21 is provided with a first valve hole 214 and a second valve hole 215. The safety valve 26 includes a valve body 261, a valve core 262 and a pressure regulating element 263. A cavity is provided inside the valve body 261, and the valve core 262 is arranged inside the cavity. The first valve hole 214 is used to connect the feeding port 211 with the cavity, and the second valve hole 215 is used to connect the discharging port 212 with the cavity. The valve core 262 is located between the first valve hole 214 and the second valve hole 215. The pressure regulating element 263 includes an adjusting bolt 2631 and an elastic element 2632. Two ends of the elastic element 2632 respectively abut against the adjusting bolt 2631 and the valve core 262 to regulate 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 operation of environmentally friendly recycled materials, factors such as the characteristics of the materials and the production environment may cause the pressure inside the feeding tank body 21 to rise abnormally. At this time, the safety valve 26 can respond in time. When the pressure in the tank reaches the set value, the valve core 262 generates displacement under the action of the pressure, overcoming the resistance of the elastic element 2632, so that the first valve hole 214 is communicated with the second valve hole 215, releasing part of the pressure, and avoiding dangerous situations such as the rupture of the tank due to overpressure, ensuring the safety of the equipment and operators. It helps to stabilize the extrusion process. A stable feeding pressure is the key to ensuring the uniform and stable extrusion of environmentally friendly recycled materials by the twin-screw extruder. Through the pressure regulating element 263, the operator can accurately regulate the pressure borne by the valve core 262 according to the extrusion requirements of different materials, and then maintain the feeding tank body 21 within a suitable pressure range, so that the materials can enter the extruder at a stable flow rate, improving the quality and consistency of the extruded products.

[0026] Refer to Figure 7As shown in the figure, the hybrid extrusion mechanism 4 includes a transmission box 41, an extrusion box 42, a transmission connecting shaft 43, a hybrid extrusion screw 44 and a hybrid feeding device 45. The transmission connecting shaft 43 is arranged in the transmission box 41. One end of the transmission connecting shaft 43 is connected to the hybrid driving mechanism 3, and the other end is connected to the hybrid extrusion screw 44. Two hybrid extrusion screws 44 are arranged in parallel and their outer diameters are meshed with each other. The hybrid extrusion screw 44 is arranged in the extrusion box 42, and the extrusion box 42 is provided with an extrusion connection port 421 for connecting an extrusion die. In this embodiment, the design of two hybrid extrusion screws 44 with meshed outer diameters greatly improves the mixing uniformity of the environmentally friendly recycled materials. During the rotation of the screws, recycled materials with different properties and different particle sizes are fully stirred and kneaded, ensuring that the performance indexes of the materials reach a high degree of consistency before extrusion, effectively avoiding quality defects of the extruded products caused by uneven material distribution. Secondly, through the reasonable setting of the transmission connecting shaft 43 between the transmission box 41 and the extrusion box 42, the efficient and stable transmission of power is realized. The power of the hybrid driving mechanism 3 is accurately transmitted to the hybrid extrusion screw 44 through the transmission connecting shaft 43, ensuring the stability and controllability of the screw rotation speed, and then providing stable pressure and flow rate for the extrusion process, which helps to produce environmentally friendly recycled material products with high dimensional accuracy and stable quality.

[0027] Referring to Figures 1 to 8 As shown in the figure, an extrusion method for environmentally friendly recycled materials includes the above-mentioned twin-screw extruder for environmentally friendly recycled materials. Step S1, material components: The environmentally friendly recycled materials are weighed by weight percentage: 50-70% of recycled polyolefin particles, selected from rPP, rPE or a mixture of both; 25-40% of biomass filler, modified wood powder or straw powder, with a particle size of 80-120 mesh; 3-8% of reactive compatibilizer, PP-g-MAH or POE-g-MAH; 0.5-1% of antioxidant, a compound of hindered phenols and phosphite. Step S2, segmented feeding: The recycled polyolefin particles and 50% of the compatibilizer are premixed in a 90°C internal mixer for 5 minutes; the biomass filler and the remaining compatibilizer are processed in a 60°C high-speed mixer for 10 minutes. Low-temperature grinding: The premixed material is put into the feeding port 211 of the twin-screw extruder; ground by the co-rotating twin-screws at 40±5°C; controlling the grinding gap at 0.2-0.4 mm, and the output particle size D50≤100 μm. Vacuum extrusion: The ground material enters the hybrid extrusion mechanism 4, with an extrusion linear speed of 4-6 m / min and a melt pressure of 10±1 MPa.

[0028] In this embodiment, in terms of material component selection, the recycled polyolefin particles, biomass filler, reactive compatibilizer, and antioxidant are rationally proportioned, enabling the material to possess good comprehensive properties. The recycled polyolefin particles provide the basic mechanical properties and processing properties. The addition of the biomass filler not only reduces costs but also enhances the environmental friendliness and certain special properties of the material, such as rigidity. The reactive compatibilizer enhances the interfacial compatibility between the components, making the internal structure of the material more uniform, thereby effectively improving the overall properties of the material. The addition of the antioxidant ensures the stability of the material during processing and use, extending its service life. The segmented feeding and low-temperature grinding processes greatly improve the dispersibility and refinement degree of the material. The premixing treatment by the internal mixer and high-speed mixer allows the components to be initially evenly distributed, and then ground by the twin-screw extruder at a specific temperature and grinding gap to output fine materials with a particle size D50≤100μm, providing a good foundation for subsequent processing. The vacuum extrusion link ensures the stability and efficiency of the extrusion process. The extrusion line speed of 4 - 6m / min and the melt pressure of 10±1MPa enable the material to be smoothly extruded and formed, producing environmentally friendly recycled material products with stable quality and excellent performance, meeting the high-quality production requirements in the field of environmentally friendly recycled material extrusion.

[0029] The method for modifying the biomass filler is as follows: Wood flour / straw powder is treated with a 5wt% NaOH solution for 1 hour, washed with water until neutral, and then dried and mixed with a 2wt% silane coupling agent at 80°C. When premixing the recycled polyolefin particles, 0.3% liquid paraffin is added as a dispersion medium. In this embodiment, for the biomass filler, after treating the wood flour / straw powder with a 5wt% NaOH solution for 1 hour and washing it with water until neutral, impurities, hemicellulose, and part of the lignin are effectively removed, increasing the active sites on the surface of the filler and enhancing its interfacial bonding ability with the polymer matrix. Subsequently, it is dried and mixed with a 2wt% silane coupling agent at 80°C. The silane coupling agent can form chemical bonding between the filler and the polymer, further improving their compatibility, enabling the biomass filler to be better dispersed in the recycled polyolefin matrix during the twin-screw extrusion process, and enhancing the mechanical properties of the composite material. When premixing the recycled polyolefin particles, 0.3% liquid paraffin is added as a dispersion medium. Liquid paraffin has good lubricity and dispersibility. In the twin-screw extruder, it can reduce the friction between the materials, reduce the agglomeration phenomenon of the materials, make the recycled polyolefin particles and the modified biomass filler more evenly distributed, contribute to improving the fluidity of the materials, and ensure the stability and continuity of the extrusion process.

[0030] During the grinding stage, liquid nitrogen is used to assist in cooling, with a spraying volume of 0.5 L / min to maintain the material temperature ≤ 40°C; a pressure feedback system is set at the discharge port 212, and automatic pressure relief occurs when the pressure > 0.4 MPa; the grinding enters the mixing and extrusion mechanism 4 and is extruded under the following segmented parameters: feeding section: temperature is 155 - 165°C, vacuum degree is atmospheric pressure, and screw speed is 100 rpm; melting section: temperature is 175 - 185°C, vacuum degree is -0.09 MPa, and screw speed is 180 rpm; die head section: temperature is 170 - 180°C. In this embodiment, liquid nitrogen is used to assist in cooling during the grinding stage and the spraying volume is precisely controlled at 0.5 L / min, which can effectively maintain the material temperature ≤ 40°C. This measure prevents problems such as degradation and performance deterioration of the material due to heat generated during grinding, maximally retains the original characteristics of the environmentally friendly recycled material, and ensures the stability of its physical and chemical properties. The pressure feedback system set at the discharge port 212 automatically relieves pressure when the pressure > 0.4 MPa, providing reliable safety protection for the entire extrusion process. It avoids equipment damage caused by excessive pressure, reduces the risk of production accidents, and improves the stability and continuity of equipment operation. After entering the mixing and extrusion mechanism 4, the precise setting of each segmented parameter plays an important role. The temperature of the feeding section is 155 - 165°C, the vacuum degree is atmospheric pressure, and the screw speed is 100 rpm, which is conducive to the uniform feeding of the material and lays a good foundation for subsequent processing. The temperature of the melting section is increased to 175 - 185°C, the vacuum degree reaches -0.09 MPa, and the screw speed is 180 rpm, which can fully melt and plasticize the material, remove volatiles, and improve the homogeneity and fluidity of the material. The temperature of the die head section is controlled at 170 - 180°C, ensuring the forming quality of the extruded product and making the final environmentally friendly recycled material product have high dimensional accuracy and good appearance quality.

[0031] 1 - 3% supercritical CO2 is injected into the melting section, with a pressure of 7.39 MPa and a temperature of 31°C, reducing the foaming density of the material by 15 - 30%; an online infrared thickness gauge is set at the die head outlet to close-loop control the extrusion speed fluctuation ≤ ±2%. In this embodiment, the injection of supercritical CO2 reduces the foaming density of the material by 15 - 30%, optimizing the physical properties of the product. While maintaining a certain strength, the weight of the foamed material is significantly reduced, which not only reduces the usage amount of raw materials but also improves the thermal insulation, sound insulation and other properties of the product, broadening the application fields of the environmentally friendly recycled material. An online infrared thickness gauge is set at the die head outlet and closed-loop controlled to control the extrusion speed fluctuation within ≤ ±2%. The precise speed control ensures the thickness uniformity of the extruded product, greatly improving the stability of product quality. The reduction of thickness deviation makes the product more reliable during subsequent processing and use, reduces the defective rate caused by uneven thickness, and improves production efficiency and economic benefits. The precise control also meets the requirements of high-quality manufacturing for environmentally friendly recycled materials, helping to promote the wide application of environmentally friendly recycled materials in more fields.

[0032] The above embodiments only represent several implementation manners of the present invention. The description thereof is relatively specific and detailed, but it should not be construed as a limitation to the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several variations and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the appended claims.

Claims

1. An environmentally friendly recycled material twin-screw extruder, characterized in that: It includes a feeding driving mechanism, a feeding extrusion mechanism, a mixing driving mechanism and a mixing extrusion mechanism. The feeding driving mechanism is used to drive the feeding extrusion mechanism, and the mixing driving mechanism is used to drive the mixing extrusion mechanism. The feeding extrusion mechanism is used for material input. The feeding extrusion mechanism includes a feeding tank body, a feeding fixed bracket, a feeding main screw, a feeding driven screw and a feeding connection seat. The two ends of the feeding tank body are respectively provided with a feeding port and a discharging port. The discharging port is used to connect the mixing extrusion mechanism, and the feeding port is used to input materials. The feeding fixed bracket is arranged inside the feeding tank body. The feeding fixed bracket is provided with a partition plate for separating the feeding port and the discharging port. The feeding fixed bracket is provided with a grinding channel. The feeding main screw and the feeding driven screw are both arranged in the grinding channel for conveying materials from the feeding port towards the discharging port to grind the materials when they pass through. The feeding connection seat is arranged at one end of the feeding tank body for fixing one end of the feeding main screw. The feeding driving mechanism is connected to the feeding main screw through a coupling. The mixing extrusion mechanism is used to mix and extrude the ground materials.

2. The twin-screw extruder for environmentally friendly recycled materials according to claim 1, wherein: The feeding driving mechanism is a driving 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 arranged at one end of the feeding tank body and is connected to the feeding fixed bracket. The tail end plate is arranged on one side of the sealing connection end plate and forms a connecting cavity. The connecting bearing is arranged in the connecting cavity and is used to connect one end of the feeding main screw. A spring is arranged in the connecting cavity. The spring is sleeved on the feeding main screw and one end thereof 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 driving mechanism through a coupling.

3. The twin-screw extruder for environmentally friendly recycled materials according to claim 1, characterized in that: There are two feeding driven screws. The two feeding driven screws are respectively meshed on both sides of the feeding main screw to grind and convey the materials from the feeding port towards the discharging port during transmission. A grinding gap is formed between the feeding driven screw and the feeding main screw for material grinding. The opposite surfaces of the feeding driven screw and the feeding main screw corresponding to the grinding gap are alloy spraying coatings.

4. The twin-screw extruder for environmentally friendly recycled materials according to claim 1, characterized in that: Partition ribs are arranged inside the feeding tank body. The partition ribs are used to connect the partition plate. The partition plate is provided with a sealing groove, and a sealing ring is arranged in the sealing groove for sealing and separating the feeding port and the discharging port.

5. The twin-screw extruder for environmentally friendly recycled materials according to claim 1, wherein: A safety valve is arranged on one side of the feeding tank body. The feeding tank body is provided with a first valve hole and a second valve hole. The safety valve includes a valve body, a valve core and a pressure regulating element. A cavity is arranged inside the valve body. The valve core is arranged in the cavity. The first valve hole is used to connect the feeding port with the cavity, and the second valve hole is used to connect the discharging port with the cavity. The valve core is located between the first valve hole and the second valve hole. 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 regulate the pressure borne by the valve core.

6. The twin-screw extruder for environmentally friendly recycled materials according to claim 1, wherein: The mixing and extrusion mechanism includes a transmission box, an extrusion box, a transmission connecting shaft, a mixing and extrusion screw, and a mixing and feeding device. The transmission connecting shaft is arranged in the transmission box. One end of the transmission connecting shaft is connected to the mixing drive mechanism, and the other end is connected to the mixing and extrusion screw. Two mixing and extrusion screws are arranged in parallel and their outer diameters mesh with each other. The mixing and extrusion screw is arranged in the extrusion box, and the extrusion box is provided with an extrusion connection port for connecting an extrusion die.

7. An extrusion method for an environmentally friendly recycled material, characterized in that: including the twin-screw extruder for environmentally friendly recycled materials according to any one of claims 1 to 6, Step S1, material components: The environmentally friendly recycled materials are weighed by weight percentage: 50-70% of recycled polyolefin particles, selected from rPP, rPE or a mixture of both; 25-40% of biomass filler, modified wood powder or straw powder, with a particle size of 80-120 mesh; 3-8% of reactive compatibilizer, PP-g-MAH or POE-g-MAH; 0.5-1% of antioxidant, a compound of hindered phenols + phosphite; Step S2, segmented feeding: The recycled polyolefin particles and 50% of the compatibilizer are premixed in a kneader at 90°C for 5 minutes; The biomass filler and the remaining compatibilizer are processed in a high-speed mixer at 60°C for 10 minutes; Low-temperature grinding: The premixed material is put into the feeding port of the twin-screw extruder; It is ground by a co-rotating twin-screw at 40±5°C; The grinding gap is controlled at 0.2-0.4 mm, and the output particle size D50≤100 μm; Vacuum extrusion: The ground material enters the mixing and extrusion mechanism, the extrusion linear speed is 4-6 m / min, and the melt pressure is 10±1 MPa.

8. The extrusion method of the environmentally friendly recycled material according to claim 7, characterized in that: The method for modifying the biomass filler is: The wood powder / straw powder is treated with a 5wt% NaOH solution for 1 hour, washed to neutral, and then dried and mixed with a 2wt% silane coupling agent at 80°C; 0.3% liquid paraffin is added as a dispersion medium during the premixing of the recycled polyolefin particles.

9. The extrusion method of the environmentally friendly recycled material according to claim 7, characterized in that: During the grinding stage, liquid nitrogen is used to assist in cooling, the injection volume is 0.5 L / min, and the material temperature is maintained at ≤40°C; a pressure feedback system is set at the discharge port, and when the pressure > 0.4 MPa, it automatically relieves pressure; The grinding enters the mixing and extrusion mechanism and is extruded under the following segmented parameters: Feeding section: The temperature is 155-165°C, the vacuum degree is normal pressure, and the screw speed is 100 rpm; Melting section: The temperature is 175-185°C, the vacuum degree is -0.09 MPa, and the screw speed is 180 rpm; Die head section: The temperature is 170-180°C.

10. The extrusion method of the environmentally friendly recycled material according to claim 7, characterized in that: 1-3% of supercritical CO2 is injected into the melting section, the pressure is 7.39 MPa, and the temperature is 31°C, so that the foaming density of the material is reduced by 15-30%; an on-line infrared thickness gauge is set at the die head outlet, and the closed-loop control of the extrusion speed fluctuation is ≤±2%.

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