A closed-loop cleaning and enhanced granulation integrated method for waste polyethylene plastic

Abstract

The application provides a closed-loop cleaning and enhanced granulation integrated method for waste polyethylene plastic, and belongs to the technical field of waste PE plastic recycling, which comprises pretreatment of waste PE, chemical cleaning and anchoring of the pretreated waste PE fragments, and extrusion granulation of the chemically modified waste PE fragments mixed with auxiliary materials. The application realizes in-situ grafting enhancement of the PE surface by introducing modified nano-SiO2 anchoring during cleaning, reduces the usage amount of the filler in the extrusion granulation stage, solves the problems of poor compatibility of non-polar PE with polar additives and easy agglomeration, adds a thioctic amide and a hydroxyl-terminated branched polymer compound modifier in the extrusion granulation stage, repairs the molecular chain rupture and mechanical property reduction of the waste PE caused by aging and processing, and improves the tensile, bending and other mechanical properties of the regenerated PE particles.

Description

Technical Field

[0001] This invention relates to the field of waste PE plastic recycling technology, specifically to a closed-loop integrated method for cleaning and reinforcing granulation of waste polyethylene plastic. Background Technology

[0002] Polyethylene (PE) is a saturated alkane polymer formed by the polymerization of ethylene monomers. Its molecular chains possess high symmetry and chemical stability. With its excellent corrosion resistance, good processability, and low production cost, it has become one of the world's most produced and widely used general-purpose plastics. According to a 2023 report by the United Nations Environment Programme, the total amount of waste plastics generated globally each year has exceeded 400 million tons, of which polyethylene and polypropylene account for 60%, making them the main components of waste plastics. PE plastics have a natural degradation cycle of hundreds of years. Open-air stockpiling releases VOCs; discarding them in soil hinders aeration and water permeability and disrupts microbial community structure; entering water bodies decomposes into microplastics, which accumulate through the food chain; while incineration can achieve energy recovery, it may produce toxic and harmful gases and has low energy efficiency.

[0003] Currently, the recycling of waste PE plastics is still mainly based on physical recycling, with the core process being physical crushing, simple washing, and then melt granulation. This method is simple to operate and low in cost, making it the most widely used recycling route. However, due to technological bottlenecks, the following problems still exist: 1) During use, waste PE plastics are exposed to light, temperature changes, mechanical stress, and other environments for a long time, causing oxidative degradation of the molecular chains. The physical operations such as crushing and melting during recycling further exacerbate the breakage and entanglement of the molecular chains, leading to a decline in its mechanical properties. This means that recycled PE materials can only be used for low-value-added products, restricting the economic benefits of recycling; 2) To improve the mechanical properties of recycled PE materials, existing technologies often add fillers or modifiers during the melt granulation stage for reinforcement and modification. However, since PE molecular chains are non-polar, while most modifiers are polar, the interfacial bonding between the two is weak, resulting in poor compatibility and uneven dispersion. Especially during high-temperature melt granulation, modifiers are prone to agglomeration due to intermolecular forces, resulting in limited improvement in the mechanical properties of recycled PE materials, which cannot meet the needs of mid-to-high-end products. Summary of the Invention

[0004] The purpose of this invention is to provide a closed-loop integrated method for cleaning and reinforcing granulation of waste polyethylene plastics, so as to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A closed-loop integrated method for cleaning and reinforcing granulation of waste polyethylene plastic includes the following steps: (1) The waste PE is sorted, crushed and dried, and then activated by low temperature plasma to obtain activated PE fragments; (2) Mix the activated PE fragments with the modified cleaning solution at a solid-liquid ratio of 1: (8~10), clean with ultrasonication, rinse, and then centrifuge to dehydrate to obtain the modified PE fragments; (3) By weight, 100 parts of modified PE scrap, 0.8-1.5 parts of modifier, 3-6 parts of filler, 2-4 parts of compatibilizer, 0.5-1 parts of antioxidant and 0.3-0.6 parts of light stabilizer are mixed evenly and then extruded and granulated to obtain recycled PE granules.

[0006] Preferably, in step (2), the modified cleaning solution comprises, by weight, the following: 100 parts water; 0.5-1.5 parts of nonionic surfactant; Alkaline additives: 0.3-0.8 parts; Chelating agent 0.1~0.3 parts; 0.1-0.2 parts of silane hydrolysis inhibitor; Modified nano-SiO2 0.4~0.8 parts.

[0007] Preferably, the nonionic surfactant is composed of fatty alcohol polyoxyethylene ether and glucoside in a mass ratio of 1:2, the alkaline additive is composed of sodium bicarbonate and sodium carbonate in a mass ratio of 3:1, and the pH of the modified cleaning solution is 8-9.

[0008] Sodium bicarbonate and sodium carbonate are mixed in a 3:1 ratio, utilizing CO32-. 2- and HCO3 2- The conjugate acid-base pair forms a wide-range, strongly buffered, weakly alkaline system, possessing both moderate neutralizing ability and mild emulsifying ability. On the one hand, it avoids the damage to the PE surface caused by using sodium carbonate alone, and on the other hand, it avoids the poor cleaning effect caused by the weak saponification ability of sodium bicarbonate.

[0009] Preferably, the chelating agent is disodium ethylenediaminetetraacetate (EDTA-2Na), the silane hydrolysis inhibitor is methyltrimethoxysilane, and the modified nano-SiO2 is KH-550 modified nano-SiO2 (KH-550@nano-SiO2).

[0010] Preferably, in step (1), the crushed particle size is 3~10mm, the drying temperature is 60℃~100℃, the low-temperature plasma activation uses air medium, the power is 150~200W, the time is 3~5min, and the vacuum degree (gauge pressure) is -0.05~-0.06MPa; in step (2), the ultrasonic cleaning conditions are 45~55℃ and 40~60kHz, and the rinsing is to rinse once with diluted cleaning solution and then rinse twice with water.

[0011] Preferably, the diluted cleaning solution is prepared by diluting the modified cleaning solution by 3 to 5 times.

[0012] Preferably, in step (3), the modifier is a compound of thioctinamide and terminal hydroxyl branched polymer in a mass ratio of 2:1.

[0013] Preferably, the hydroxyl-terminated branched polymer includes at least one of hydroxyl-terminated hyperbranched polyester and hyperbranched polyglycerol.

[0014] Preferably, in step (3), the filler is vinyltriethoxysilane (VTES) modified nano-talc powder, the compatibilizer is maleic anhydride grafted polyethylene (MAH-g-PE), the antioxidant is hindered phenolic antioxidant, and the light stabilizer is benzotriazole derivative.

[0015] Preferably, in step (3), a twin-screw extruder is used for granulation, and the extrusion temperature of each zone is 120~130℃ in zone 1, 140~150℃ in zone 2, 160~170℃ in zone 3, and 175~185℃ in zone 4, with a screw speed of 180~220r / min.

[0016] The beneficial effects of the above-described technical solution of the present invention are as follows: (1) Waste PE has strong chemical inertness and extremely low polarity. This solution introduces polar groups such as hydroxyl and carbonyl groups on its surface through low-temperature air plasma to achieve surface activation. This not only improves the wetting and removal effect of the subsequent modified cleaning solution on oil stains and impurities, but also provides chemical binding sites for modified nano-SiO2, compatibilizers, etc., thereby solving the problem of poor compatibility and easy agglomeration of non-polar PE and polar additives.

[0017] (2) The modified cleaning solution of this scheme has the dual functions of efficient decontamination and in-situ modification. The nonionic compound surfactant, alkaline additive and chelating agent work together to deeply remove oil stains, inorganic salts and other impurities. KH-550@nano-SiO2 in the cleaning system is uniformly dispersed by ultrasonic field under the stabilization of silane hydrolysis inhibitor and bonds with PE activation sites to achieve in-situ surface grafting enhancement. At the same time, it reduces the amount of filler used in the melt granulation stage and avoids the problems of low efficiency and uneven modification caused by the traditional first cleaning and then modification segmented process.

[0018] (3) In the melt granulation process of this scheme, thioctin and terminal hydroxyl branched polymer compound modifiers are used. The active groups can be used to extend and re-crosslink the degraded and broken PE molecular chains, repairing the molecular chain breakage and mechanical property decline caused by aging and processing of waste PE. With the addition of modified nano talc powder and maleic anhydride grafted PE compatibilizer, the reinforcing phase is uniformly dispersed in the matrix and the interface is strongly bonded, which significantly improves the tensile, bending and other mechanical properties of recycled PE, so as to meet the requirements of mid-to-high-end applications.

[0019] (4) The antioxidant and light stabilizer in this scheme are evenly dispersed during the extrusion granulation process, which can inhibit the thermo-oxidative aging and photo-aging during high-temperature processing and subsequent use, and delay the degradation of molecular chains again; combined with the aforementioned chain repair and interface enhancement effects, the recycled PE particles not only have improved mechanical properties, but also have excellent long-term use stability. Detailed Implementation

[0020] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0021] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products. Example

[0022] A closed-loop integrated method for cleaning and reinforcing granulation of waste polyethylene plastic includes the following steps: (1) Pretreatment Waste PE is sorted to remove impurities, then fed into a crusher to crush it, obtaining PE fragments with a particle size of 3~10mm. The fragments are dried at 60~100℃ to remove surface free water, and then activated by low-temperature plasma for 3~5 minutes using air medium, power 150~200W, vacuum degree -0.05~-0.06MPa, to obtain activated PE fragments.

[0023] (2) Chemical cleaning S1. Preparation of modified cleaning solution: Based on 100 parts by mass, use water as the base liquid, add 0.5-1.5 parts of nonionic surfactant, 0.1-0.3 parts of chelating agent, 0.1-0.2 parts of silane hydrolysis inhibitor and 0.3-0.8 parts of alkaline additive to adjust the pH to 8-9, then add 0.4-0.8 parts of KH-550@nano-SiO2, and ultrasonically disperse for 10-15 min to obtain the modified cleaning solution.

[0024] The nonionic surfactant is composed of fatty alcohol polyoxyethylene ether and glucoside in a mass ratio of 1:2. The fatty alcohol polyoxyethylene ether is preferably lauryl alcohol polyoxyethylene ether-9, and the glucoside is preferably octyl / decyl glucoside APG0810. The chelating agent is EDTA-2Na, the silane hydrolysis inhibitor is methyltrimethoxysilane, and the alkaline auxiliary agent is composed of sodium bicarbonate and sodium carbonate in a mass ratio of 3:1.

[0025] KH-550@nano-SiO2 is prepared using conventional methods, such as dispersing nano-SiO2 in an ethanol-water mixed solvent, adjusting it to a weakly acidic state, adding KH-550, and heating at 50-70℃ to hydrolyze silane and react it with the hydroxyl and carboxyl groups on the surface of SiO2. Finally, it is obtained by washing and drying.

[0026] S2, Cleaning and Anchoring: The PE activated fragments from step (1) are mixed with the modified cleaning solution at a solid-liquid ratio of 1: (8~10). The temperature is controlled at 45~55℃, and ultrasonic cleaning is performed at 40~60kHz for 20-30 minutes to remove oil and impurities from the PE surface. At the same time, KH-550@nano-SiO2 is hydrolyzed to generate silanols. The amino group of KH-550 itself is used as a nucleophile to reduce the dehydration condensation activation energy of silanol and hydroxyl groups on the PE surface. Combined with the instantaneous energy of ultrasonic cavitation, KH-550@nano-SiO2 is anchored on the PE fragments to form a modified layer.

[0027] S3, rinsing and dehydration: After step S2, rinse once with a modified cleaning solution of 1 / 3 to 1 / 5 concentration, then rinse twice with pure water, and then centrifuge at 1000 to 2000 r / min to dehydrate so that the water content is not higher than 0.5%, and obtain modified PE fragments.

[0028] (3) Enhanced granulation: By weight, 100 parts of modified PE scrap, 0.8~1.5 parts of modifier, 3~6 parts of filler, 2~4 parts of compatibilizer, 0.5~1 parts of antioxidant and 0.3~0.6 parts of light stabilizer are mixed evenly and then put into a twin-screw extruder for extrusion granulation. The extrusion temperature of each zone is controlled as follows: Zone 1 120~130℃, Zone 2 140~150℃, Zone 3 160~170℃, Zone 4 175~185℃, and the screw speed is 180~220r / min to obtain recycled granules.

[0029] The modifier is composed of thioctinamide and hydroxyl-terminated branched polymers in a mass ratio of 2:1. The hydroxyl-terminated branched polymers include hydroxyl-terminated hyperbranched polyesters (such as the H10, H20, or H30 series) and hyperbranched polyglycerols (number average molecular weight). M nAt least one of the following: (1500~2000 g / mol); the filler is VTES modified nano talc powder; the compatibilizer is MAH-g-PE (grafting rate 0.8~1.2%); the antioxidant is a hindered phenolic antioxidant; and the light stabilizer is a benzotriazole derivative.

[0030] VTES-modified nano-talc powder is prepared using conventional methods, such as dissolving VTES in an ethanol-water mixed solvent, adjusting it to a weakly acidic state, then adding nano-talc powder for dispersion, reacting under heating conditions of 50-70℃, and finally washing and drying after the reaction is complete. Example 1

[0031] A closed-loop integrated method for cleaning and reinforcing granulation of waste polyethylene plastic, employing the steps of the above embodiments, includes: (1) The waste PE is sorted to remove impurities and then sent to a crusher to crush it to obtain PE fragments with a particle size of 3~5mm. The surface free water is removed by drying at 80℃. Then, the PE is activated by low-temperature plasma for 4min using air medium, power 180W, vacuum degree -0.05~-0.06MPa, to obtain activated PE fragments.

[0032] (2) The modified cleaning solution, by mass, includes 100 parts water, 1 part nonionic surfactant (lauryl alcohol polyoxyethylene ether-9 and APG0810), 0.2 parts EDTA-2Na, 0.1 parts methyltrimethoxysilane, 0.8 parts alkaline additives and 0.6 parts KH-550@nano-SiO2.

[0033] The PE activated fragments from step (1) were mixed with the modified cleaning solution at a solid-liquid ratio of 1:10. The temperature was controlled at 47℃, and the mixture was ultrasonically cleaned at 60kHz for 20 minutes. Then, it was rinsed once with a 1 / 3 concentration of modified cleaning solution, and then rinsed twice with pure water. The mixture was centrifuged at 1000r / min to obtain the modified PE fragments.

[0034] (3) By weight, 100 parts of modified PE scrap, 1 part of modifier (the hydroxyl-terminated branched polymer is hydroxyl-terminated hyperbranched polyester H202), 4 parts of filler, 4 parts of MAH-g-PE, 0.7 parts of antioxidant 1010 and 0.5 parts of UV-327 are mixed evenly and then put into a twin-screw extruder for extrusion granulation. The extrusion temperature of each zone is controlled as follows: zone 1 130℃, zone 2 150℃, zone 3 170℃ and zone 4 180℃. The screw speed is 200r / min to obtain recycled granules. Example 2

[0035] A closed-loop integrated method for cleaning and reinforcing granulation of waste polyethylene plastic, employing the steps of the above embodiments, includes: (1) The waste PE is sorted to remove impurities and then sent to a crusher to crush it to obtain PE fragments with a particle size of 4~8mm. The surface free water is removed by drying at 90℃. Then, the PE is activated by low-temperature plasma for 3min using air medium, power 200W, vacuum degree -0.05~-0.06MPa, to obtain activated PE fragments.

[0036] (2) The modified cleaning solution, by mass, includes 100 parts water, 1.3 parts nonionic surfactant (lauryl polyoxyethylene ether-9 and octyl / decyl glucoside APG0810), 0.3 parts EDTA-2Na, 0.2 parts methyltrimethoxysilane, 0.8 parts alkaline additives and 0.8 parts KH-550@nano-SiO2.

[0037] The PE activated fragments from step (1) were mixed with the modified cleaning solution at a solid-liquid ratio of 1:9. The temperature was controlled at 52℃, and the mixture was ultrasonically cleaned at 50kHz for 30 minutes. Then, it was rinsed once with a 1 / 4 concentration of modified cleaning solution, and then rinsed twice with pure water. The mixture was centrifuged at 1500r / min to obtain the modified PE fragments.

[0038] (3) By weight, mix 100 parts of modified PE scrap and 0.9 parts of modifier (the terminal hydroxyl branched polymer is hyperbranched polyglycerol). M n =2000g / mol), 6 parts filler, 4 parts MAH-g-PE, 0.9 parts antioxidant 1010 and 0.5 parts UV-327 are mixed evenly, and then put into a twin-screw extruder for extrusion granulation. The extrusion temperature of each zone is controlled as follows: zone 1 130℃, zone 2 150℃, zone 3 170℃ and zone 4 180℃, and the screw speed is 200r / min to obtain recycled granules. Example 3

[0039] A closed-loop integrated method for cleaning and reinforcing granulation of waste polyethylene plastic, employing the steps of the above embodiments, includes: (1) The waste PE is sorted to remove impurities and then sent to a crusher to crush it to obtain PE fragments with a particle size of 5~8mm. The surface free water is removed by drying at 80℃. Then, the PE is activated by low-temperature plasma for 5min using air medium, power 160W, vacuum degree -0.05~-0.06MPa, to obtain activated PE fragments.

[0040] (2) The modified cleaning solution, by mass, includes 100 parts water, 0.7 parts nonionic surfactant (lauryl polyoxyethylene ether-9 and octyl / decyl glucoside APG0810), 0.2 parts EDTA-2Na, 0.15 parts methyltrimethoxysilane, 0.6 parts alkaline additives and 0.4 parts KH-550@nano-SiO2.

[0041] The PE activated fragments from step (1) were mixed with the modified cleaning solution at a solid-liquid ratio of 1:8. The temperature was controlled at 55℃, and the mixture was ultrasonically cleaned at 60kHz for 25 minutes. Then, it was rinsed once with a 1 / 5 concentration of modified cleaning solution, and then rinsed twice with pure water. The mixture was centrifuged at 1000r / min to obtain the modified PE fragments.

[0042] (3) By weight, 100 parts of modified PE scrap, 1.3 parts of modifier (the hydroxyl-terminated branched polymer is hydroxyl-terminated hyperbranched polyester H102), 3 parts of filler, 3 parts of MAH-g-PE, 0.8 parts of antioxidant 1010 and 0.6 parts of UV-329 are mixed evenly and then put into a twin-screw extruder for extrusion granulation. The extrusion temperature of each zone is controlled as follows: zone 1 130℃, zone 2 150℃, zone 3 170℃ and zone 4 180℃. The screw speed is 200r / min to obtain recycled granules. Comparative Example 1

[0043] The difference between this and Example 1 is that in step (2), the anchor is not cleaned with modified cleaning solution, but is cleaned by soaking in 2wt% alkaline solution. Comparative Example 2

[0044] The difference between this and Example 1 is that, in step (2), no silane hydrolysis inhibitor is added to the modified cleaning solution. Comparative Example 3

[0045] The difference between this and Example 1 is that in step (3), the amount of VTES modified nano talc filler is increased to 10 parts. Comparative Example 4

[0046] The difference between this and Example 1 is that it uses a conventional method for recycling, including the following steps: (1) Sort the waste PE, soak and clean it with 2wt% alkaline solution, then rinse and dry it; (2) Crush the dried waste PE, add 0.2wt% antioxidant 1010, 10wt% MAH-g-PE toughening agent, 0.3wt% stearic acid lubricant and 0.5wt% UV-531 anti-ultraviolet agent, mix evenly, transfer to a twin-screw extruder for extrusion granulation, and obtain recycled granules. Comparative Example 5

[0047] A method for preparing polyethylene plastic, using conventional methods in the industry: by weight, 90 parts of PE matrix, 6 parts of montmorillonite, 0.3 parts of antioxidant 1010, 0.2 parts of stearic acid and 3.7 parts of MAH-g-PE are mixed evenly and extruded and granulated in a twin-screw extruder to obtain polyethylene plastic.

[0048] The main physical properties of the recycled granules obtained in Examples 1-3 and Comparative Examples 1-5 were tested according to the standards "Determination of Tensile Properties of Plastics" (GB / T1040) and "Determination of Flexural Properties of Plastics" (GB / T9341). The tensile strength test used a specimen size of 172*10*4 mm and a tensile rate of 50 mm / min; the flexural strength / modulus test used a specimen size of 80*10*4 mm and a bending rate of 2 mm / min. The test results are shown in the table below.

[0049] Test results show that the physical properties of Examples 1-3 of this invention are significantly better than those of Comparative Examples 1-4, but slightly lower than those of Comparative Example 5. This indicates that the present invention improves the overall mechanical properties of recycled waste polyethylene (PE), while being only slightly inferior to the properties of virgin PE plastic. Compared to Comparative Example 4 (traditional recycling method), the tensile strength of this invention is increased by more than 60%, and the elongation at break is increased by about 2 times. All key indicators are close to or even reach the level of virgin PE, successfully solving the problem of performance degradation caused by aging and degradation of waste plastics.

[0050] This invention introduces polar groups such as hydroxyl and carbonyl groups into the surface of waste PE through surface activation, providing chemical sites for the bonding of non-polar PE with polar additives. Subsequently, KH-550@nano-SiO2 is grafted onto the PE surface in a modified cleaning solution containing a silane hydrolysis inhibitor to form an interface reinforcement layer. Comparative experiments show that the absence of the silane hydrolysis inhibitor (Comparative Example 2) or the use of only ordinary alkaline solution for cleaning (Comparative Example 1) leads to a decrease in tensile and flexural strength. While increasing the amount of filler used in melt granulation can improve the performance of regenerated granulation, the improvement is limited and far from meeting the performance standards of Examples 1-3.

[0051] The above-described preferred embodiments of the present invention are provided as examples, but it will be apparent to those skilled in the art that such embodiments are provided merely by way of example. Many modifications, alterations, and alternatives will occur to those skilled in the art without departing from the spirit and intent of the invention. It should be understood that various alternatives to the embodiments of the invention described herein may be employed in the practice of the invention. The appended claims are intended to define the scope of protection of the invention and therefore cover the modular compositions, equivalents, or alternatives within the scope of these claims.

Claims

1. A closed-loop integrated method for cleaning and reinforcing granulation of waste polyethylene plastic, characterized in that, Includes the following steps: (1) The waste PE is sorted, crushed and dried, and then activated by low temperature plasma to obtain activated PE fragments; (2) Mix the activated PE fragments with the modified cleaning solution at a solid-liquid ratio of 1: (8~10), ultrasonically clean and rinse, then centrifuge and dehydrate to obtain the modified PE fragments; (3) By weight, 100 parts of modified PE scrap, 0.8-1.5 parts of modifier, 3-6 parts of filler, 2-4 parts of compatibilizer, 0.5-1 parts of antioxidant and 0.3-0.6 parts of light stabilizer are mixed evenly and then extruded and granulated to obtain recycled PE granules.

2. The closed-loop integrated cleaning and reinforcing granulation method for waste polyethylene plastic according to claim 1, characterized in that, In step (2), the modified cleaning solution, by weight, comprises: 100 parts water; 0.5-1.5 parts of nonionic surfactant; Alkaline additives: 0.3-0.8 parts; Chelating agent 0.1~0.3 parts; 0.1-0.2 parts of silane hydrolysis inhibitor; Modified nano-SiO2 0.4~0.8 parts.

3. The closed-loop integrated cleaning and reinforcing granulation method for waste polyethylene plastic according to claim 2, characterized in that, The nonionic surfactant is composed of fatty alcohol polyoxyethylene ether and glucoside in a mass ratio of 1:2, the alkaline additive is composed of sodium bicarbonate and sodium carbonate in a mass ratio of 3:1, and the pH of the modified cleaning solution is 8-9.

4. The closed-loop integrated cleaning and reinforcing granulation method for waste polyethylene plastic according to claim 2, characterized in that, The chelating agent is disodium ethylenediaminetetraacetate, the silane hydrolysis inhibitor is methyltrimethoxysilane, and the modified nano-SiO2 is modified using KH-550.

5. The closed-loop integrated cleaning and reinforcing granulation method for waste polyethylene plastic according to claim 1, characterized in that, In step (1), the crushed particle size is 3~10mm, the drying temperature is 60℃~100℃, the low-temperature plasma activation uses air medium, the power is 150~200W, the time is 3~5min, and the vacuum degree is -0.05~-0.06MPa; in step (2), the ultrasonic cleaning conditions are 45~55℃ and 40~60kHz, and the rinsing is to rinse once with diluted cleaning solution and then rinse twice with water.

6. The closed-loop integrated cleaning and reinforcing granulation method for waste polyethylene plastic according to claim 5, characterized in that, The diluted cleaning solution is prepared by diluting the modified cleaning solution by 3 to 5 times.

7. The closed-loop integrated cleaning and reinforcing granulation method for waste polyethylene plastic according to claim 1, characterized in that, In step (3), the modifier is composed of thioctinamide and terminal hydroxyl branched polymer in a mass ratio of 2:

1.

8. The closed-loop integrated cleaning and reinforcing granulation method for waste polyethylene plastic according to claim 7, characterized in that, The hydroxyl-terminated branched polymer includes at least one of hydroxyl-terminated hyperbranched polyester and hyperbranched polyglycerol.

9. The closed-loop integrated cleaning and reinforcing granulation method for waste polyethylene plastic according to claim 1, characterized in that, In step (3), the filler is vinyltriethoxysilane modified nano-talc powder, the compatibilizer is maleic anhydride grafted polyethylene, the antioxidant is hindered phenolic antioxidant, and the light stabilizer is benzotriazole derivative.

10. The closed-loop integrated cleaning and reinforcing granulation method for waste polyethylene plastic according to claim 1, characterized in that, In step (3), a twin-screw extruder is used for extrusion granulation. The extrusion temperatures in each zone are 120~130℃ in zone 1, 140~150℃ in zone 2, 160~170℃ in zone 3, and 175~185℃ in zone 4. The screw speed is 180~220r / min.

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