High-toughness regenerated plastic dropper material based on waste mulching film and preparation method of high-toughness regenerated plastic dropper material

Abstract

The invention discloses a high-toughness regenerated plastic dropper material based on a waste mulching film and a preparation method of the high-toughness regenerated plastic dropper material, belongs to the technical field of material regeneration, and is used for solving the technical problem that the tensile property and the impact resistance of a regenerated plastic dropper material in the prior art need to be further improved. According to the invention, a silica ion reinforcing component, boric acid ester modified regenerated polyethylene and hydroxyl carbamate flexible polyurethane are synergistically compounded, and a multi-scale structure system in which an inorganic-organic hybrid constraint structure, a dynamic reversible connection unit and a flexible dissipation channel are combined is constructed in the material; the material forms a stable interface coupling and continuous stress transfer path in the melting processing and service stress process, so that the material gives consideration to structural bearing, morphology stability and energy distribution capability, and is suitable for plastic dropper products with comprehensive requirements on mechanical properties and heat resistance.

Description

Technical Field

[0001] This invention relates to the field of material recycling technology, specifically to a high-toughness recycled plastic drip tube material based on waste mulch film and its preparation method. Background Technology

[0002] Waste mulch film is mainly composed of polyethylene materials. After recycling, sorting, cleaning, and reprocessing, it can form recycled polyolefin raw materials, which are used in packaging products and extruded parts. Plastic drip tubes are commonly used flexible extruded products in the pharmaceutical and daily chemical industries, and have comprehensive requirements for the toughness, molding consistency, and heat distortion stability of the materials. However, the molecular structure and performance of recycled waste mulch film are usually affected by differences in source, residual impurities, and multiple heat processing history. This leads to material adaptation requirements for drip tube products in terms of load-bearing capacity, heat resistance, and reliability. Therefore, the industry is generally concerned with the development and standardized application of high-toughness recycled drip tube materials based on waste mulch film.

[0003] Currently, the preparation process of recycled plastic drip irrigation materials based on waste mulch film usually involves simple cleaning, recycling and granulation followed by direct extrusion molding or conventional blending modification to obtain the product. Due to the complex sources of waste mulch film and the large differences in the usage environment, problems such as molecular chain breakage, structural inhomogeneity and residual impurities are inevitable during the recycling process, which makes the recycled materials exhibit large dispersion in terms of mechanical properties and processing stability.

[0004] Furthermore, traditional processes often focus on adjusting a single property in material system design, making it difficult to achieve a synergistic balance between toughness, load-bearing capacity, and heat deformation resistance. As a result, products are prone to insufficient morphological stability, localized stress concentration, or performance degradation during extrusion molding and subsequent use. Therefore, there is still room for further optimization and improvement in the industry regarding the shortcomings of recycled waste plastic film in terms of multi-scale structural synergy, interface stability, and comprehensive performance matching. Summary of the Invention

[0005] The purpose of this invention is to provide a high-toughness recycled plastic dripper material based on waste plastic film and its preparation method, in order to solve the technical problem that the tensile and impact resistance properties of recycled plastic dripper materials in the prior art need to be further improved.

[0006] The objective of this invention can be achieved through the following technical solution: a method for preparing a high-toughness recycled plastic drip irrigation material based on waste plastic film, comprising the following steps:

[0007] S1. After rubbing and cleaning the waste plastic film, clean plastic film is obtained;

[0008] S2. After the clean mulch film is crushed, it is washed with water and gravity separation is performed. After drying, it is further separated by cyclone separation to obtain clean mulch film particles.

[0009] S3. Weigh out 84-88 parts of borate-modified recycled polyethylene, 24-27 parts of silica-oxygen ion reinforcing component, 10-12 parts of hydroxyl urethane flexible polyurethane and 2-3 parts of auxiliary materials by weight, add them to a mixing tank and mix evenly, then add them to a twin-screw extruder and melt extrude to obtain recycled plastic dropper material.

[0010] Furthermore, in step S1, the friction cleaning operation is as follows: the waste plastic film is transferred to the friction washing machine, the machine speed is 400-600 rpm, the material filling rate is 30-50%, first using 1wt% sodium hydroxide aqueous solution as the cleaning medium, cleaning for 15 minutes, and then using 0.5-0.8wt% citric acid as the cleaning medium, cleaning for 15-20 minutes.

[0011] Furthermore, in step S2, the water flow velocity for gravity separation is 0.3-0.5 m / s, the wind speed for cyclone separation is 8-12 m / s, and the wind pressure is 1000-1500 Pa.

[0012] Furthermore, in step S3, the auxiliary material is obtained by mixing antioxidant 1010, antioxidant 168, calcium stearate, ethylene bis-stearamide and talc in a mass ratio of 4:4:6:6:20. The temperature of the feeding zone in the twin-screw extruder is 160-170℃, the temperature of the melting zone is 170-180℃, the temperature of the die zone is 180-190℃, and the screw speed is 100-120 rpm.

[0013] Furthermore, the borate-modified recycled polyethylene is prepared by the following method:

[0014] A1. Clean mulch film granules and o-xylene are added to a reaction vessel and stirred. After nitrogen protection, the temperature is raised to 105-115℃ and stirred for 40 min. Then glycidyl methacrylate is added. After stirring evenly, benzoyl peroxide is added. The temperature of the reaction vessel is maintained at 105-115℃ and stirred for 4-6 h. After the reaction is completed, the reaction solution is cooled to 50-60℃ and poured into 3 times the volume of 95wt% ethanol aqueous solution. After precipitation is complete, the filter cake is collected and dried to obtain epoxy-grafted recycled polyethylene.

[0015] A2. Add epoxy-grafted recycled polyethylene, dopamine hydrochloride, phenylboronic acid and anhydrous ethanol to a reaction vessel and stir. After mixing evenly, heat the reaction vessel to 80-95℃ and keep it at that temperature for 4-6 hours. After the reaction is completed, reduce the pressure and distill until no liquid is collected to obtain borate ester modified recycled polyethylene.

[0016] The mechanism for preparing borate ester modified recycled polyethylene is as follows:

[0017]

[0018] In the formula: ; ; .

[0019] Furthermore, in step A1, the ratio of the amount of the clean mulch film particles, o-xylene, glycidyl methacrylate and benzoyl peroxide is 10g:80mL:1-2mL:0.1g.

[0020] Furthermore, in step A2, the ratio of epoxy-grafted recycled polyethylene, dopamine hydrochloride, phenylboronic acid, and anhydrous ethanol is 10g:0.2-0.3g:0.3-0.5g:1-2mL.

[0021] Furthermore, the preparation method of the silicon-oxygen ion-enhancing component is as follows: vinyltrimethoxysilane, 3-(methacryloyloxy)propyltrimethoxysilane, dopamine hydrochloride, deionized water and anhydrous ethanol are added to a reaction vessel, stirred evenly, and then heated to 40-60℃ and kept at the temperature for 6-8 hours. After the reaction is completed, the pressure is reduced and distilled until no liquid is collected to obtain the silicon-oxygen ion-enhancing component.

[0022] Furthermore, in the process of preparing the silicon-oxygen ion-enhancing component, the ratio of vinyltrimethoxysilane, 3-(methacryloyloxy)propyltrimethoxysilane, dopamine hydrochloride, deionized water and anhydrous ethanol is 3-5 mL: 2-3 mL: 0.8-1.0 g: 3-5 mL: 10-15 mL.

[0023] Furthermore, the hydroxycarbamate flexible polyurethane is prepared by the following method:

[0024] B1. Add bisphenol A diglycidyl ether to a high-pressure reactor, heat the high-pressure reactor to 110-130℃, introduce a calculated amount of carbon dioxide, keep the reaction at the temperature for 8-10 hours, and after the reaction is completed, cool to room temperature to obtain a bifunctional cyclic carbonate intermediate.

[0025] B2. Add the bifunctional cyclic carbonate intermediate and 1,6-hexanediamine to the reaction vessel and stir. After the mixture is homogeneous, heat the reaction vessel to 70-90℃ and keep it at that temperature for 8-12 hours. After the reaction is complete, cool to room temperature to obtain hydroxyl urethane flexible polyurethane.

[0026] Furthermore, in step B1, the amount of carbon dioxide used is 5-8 times the molar amount of epoxy groups in the reaction system;

[0027] Furthermore, in step B2, the ratio of the bifunctional cyclic carbonate intermediate to 1,6-hexanediamine is 10-12 g: 2-3 g.

[0028] The present invention also discloses a high-toughness recycled plastic drip pipe material based on waste mulch film, which is prepared by the above-mentioned preparation method of the high-toughness recycled plastic drip pipe material based on waste mulch film.

[0029] The present invention has the following beneficial effects:

[0030] 1. In the material system of this invention, boron ester modified recycled polyethylene constitutes a continuous phase skeleton. The boron-containing dynamic bond structure introduced on its main chain can participate in the rearrangement process of molecular chain segments under external force, so that the tensile load is transmitted in a relatively uniform manner in the polymer system. At the same time, the silicon-oxygen bond network formed in the silicon-oxygen ion reinforcing component is embedded in the polyethylene matrix in a dispersed state, and forms a certain constraint and support for the continuous phase chain segments through its relatively rigid structural characteristics. In addition, the hydroxyl urethane flexible polyurethane physically entangles with the polyethylene chain segments during melt blending and participates in the construction of the intermolecular interaction network through hydrogen bonding. The above-mentioned multiple structural units do not respond independently under tensile load, but form a synergistic load-bearing system through interfacial interaction and dynamic bonding, so that the material exhibits stable structural response characteristics during the stress process.

[0031] 2. Under instantaneous impact or stress concentration conditions, the response modes of different components in the material system of this invention exhibit obvious division of labor characteristics. Specifically, the flexible polyurethane segments of hydroxyl urethane preferentially undergo deformation and participate in the absorption and dissipation of impact energy; the dynamic borate bonds in the borate-modified recycled polyethylene can undergo reversible breakage and recombination under external force, forming a buffer for the crack initiation process at the molecular scale; at the same time, the inorganic-organic hybrid structure composed of silicon-oxygen ion reinforcing components changes the stress transmission path in local areas, causing the crack propagation direction to deflect. Ultimately, multiple mechanisms occur in parallel during the impact process, dispersing the impact energy among different scales and structural units, thereby forming an ordered energy dissipation process.

[0032] 3. Under operating conditions of heat and external load, the silicon-oxygen ion reinforcing component, mainly composed of Si-O-Si bonds, forms a hybrid structure with a certain rigidity in the polyethylene matrix, which constrains the thermal motion of polymer chain segments. The borate-modified recycled polyethylene maintains a certain degree of intermolecular connection during the heating process, making the continuous phase structure less prone to rapid relaxation in the thermal field. At the same time, the hydroxyl urethane flexible polyurethane participates in the maintenance of the overall structure through hydrogen bonding and chain entanglement, providing flexibility while avoiding local instability of the system under thermo-mechanical coupling conditions. Under the combined action of thermal field and load, the components form a mutually balancing structural configuration, making the material as a whole exhibit a tendency to maintain a stable shape. Detailed Implementation

[0033] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] In this application, antioxidant 1010 was purchased from Shanghai Maclean Biochemical Technology Co., Ltd., with product number P750268; antioxidant 168 was purchased from Shanghai Maclean Biochemical Technology Co., Ltd., with product number T822863; calcium stearate was purchased from Shanghai Maclean Biochemical Technology Co., Ltd., with product number C805417; and talc was purchased from Shanghai Maclean Biochemical Technology Co., Ltd., with product number T675625.

[0035] Example 1

[0036] This embodiment provides a method for preparing borate ester modified recycled polyethylene, including the following steps:

[0037] Step ①: Prepare clean mulch film

[0038] Weigh 20.0g of waste plastic film and transfer it to a friction washing machine. The machine speed is 400rpm and the material filling rate is 30%. First, use 1wt% sodium hydroxide aqueous solution as the cleaning medium and clean for 15min. Then, use 0.5wt% citric acid as the cleaning medium and clean for 15min to obtain clean plastic film.

[0039] Step 2: Prepare clean mulch film granules

[0040] Weigh out 15.0g of clean mulch film, crush it, and then perform water washing and gravity separation at a water flow rate of 0.3m / s. After drying, continue to perform cyclone separation at a wind speed of 8m / s and 1000Pa to obtain clean mulch film particles.

[0041] Step ③: Preparation of epoxy-grafted recycled polyethylene

[0042] Weigh 10.0g of clean plastic film granules and 80.0mL of o-xylene and add them to the reaction vessel. Stir and purge with nitrogen to raise the temperature to 105℃ and keep stirring for 40min. Then add 1.0mL of glycidyl methacrylate and stir until homogeneous. Add 0.1g of benzoyl peroxide and maintain the temperature of the reaction vessel at 105℃ for 4h. After the reaction is complete, cool the reaction solution to 50℃ and pour it into 3 times the volume of 95wt% ethanol aqueous solution. After precipitation is complete, filter, collect the filter cake and dry it to obtain epoxy-grafted recycled polyethylene.

[0043] Step 4: Preparation of borate ester modified recycled polyethylene

[0044] Weigh out 10.0g of epoxy-grafted recycled polyethylene, 0.2g of dopamine hydrochloride, 0.3g of phenylboronic acid and 1.0mL of anhydrous ethanol and add them to the reaction vessel. Stir until the mixture is homogeneous, then heat the reaction vessel to 80℃ and keep it at that temperature for 4 hours. After the reaction is complete, reduce the pressure and distill until no liquid is collected to obtain borate ester modified recycled polyethylene.

[0045] Waste plastic film first undergoes saponification, hydrolysis, and desorption of surface contaminants in an alkaline hydrothermal system, and physically removes attached particles and organic residues through frictional shearing. Subsequently, inorganic salt deposits and alkaline treatment residues are further removed in a weakly acidic citric acid medium through complexation and acidification, achieving a chemical-mechanical synergistic removal of surface impurities. After crushing, water washing and gravity separation and cyclone separation are used to separate and enrich heterogeneous impurities based on differences in liquid phase density and gas-solid kinetic behavior of different components, respectively. Clean particles are dispersed under o-xylene swelling conditions and generate macromolecular free radicals under the initiation of benzoyl peroxide, which then undergo a free radical grafting reaction with glycidyl methacrylate, introducing epoxy functional groups into the polyethylene chain segment. Subsequently, epoxy-grafted polyethylene, dopamine hydrochloride, and phenylboronic acid undergo ring-opening addition and boronic acid esterification reactions in an ethanol system to form a dynamic boronic acid ester bond structure, achieving the chemical bonding introduction of boron-containing functional groups.

[0046] The various intermediates and additives formed in the above steps synergistically influence the macroscopic properties of the final recycled plastic dropper material by progressively regulating the structural integrity, chemical activity, and intermolecular interactions of the recycled polyethylene. The pretreatment and sorting processes reduce the probability of introducing inorganic impurities, low-molecular-weight contaminants, and heterogeneous particles, thus mitigating the interference of stress concentration and interface defects on the overall continuity of the material. The epoxy grafting reaction introduces polar functional groups into the polyethylene backbone, altering the interfacial chemical characteristics of the original non-polar segments and transforming the intermolecular interactions from primarily van der Waals forces to multiple interactions involving a certain degree of chemical reactivity. Based on this, the borate ester bond structure participates in polymer network construction through reversible covalent linkages, dynamically participating in molecular rearrangement under processing thermal and operational stress conditions. This allows for the adjustment of chain segment freedom of movement, energy dissipation paths, and stress transfer modes without significantly disrupting the continuous phase of the polyethylene backbone, ultimately affecting the overall mechanical response, thermal stability, and rheological characteristics of the recycled plastic dropper material at the structural level.

[0047] Example 2

[0048] This embodiment provides a method for preparing borate ester modified recycled polyethylene, including the following steps:

[0049] Step ①: Prepare clean mulch film

[0050] Weigh 20.0g of waste plastic film and transfer it to a friction washing machine. The machine speed is 600rpm and the material filling rate is 50%. First, use 1wt% sodium hydroxide aqueous solution as the cleaning medium and clean for 15min. Then, use 0.8wt% citric acid as the cleaning medium and clean for 20min to obtain clean plastic film.

[0051] Step 2: Prepare clean mulch film granules

[0052] Weigh out 15.0g of clean mulch film, crush it, and then perform water washing and gravity separation at a water flow rate of 0.5m / s. After drying, continue to perform cyclone separation at a wind speed of 12m / s and a pressure of 1500Pa to obtain clean mulch film particles.

[0053] Step ③: Preparation of epoxy-grafted recycled polyethylene

[0054] Weigh 10.0g of clean plastic film granules and 80.0mL of o-xylene and add them to the reactor. Stir and purge with nitrogen to raise the temperature to 115℃ and keep stirring for 40min. Then add 2.0mL of glycidyl methacrylate and stir until homogeneous. Add 0.1g of benzoyl peroxide and maintain the reactor temperature at 115℃ for 6h. After the reaction is complete, cool the reaction solution to 60℃ and pour it into 3 times the volume of 95wt% ethanol aqueous solution. After precipitation is complete, filter, collect the filter cake and dry it to obtain epoxy-grafted recycled polyethylene.

[0055] Step 4: Preparation of borate ester modified recycled polyethylene

[0056] Weigh out 10.0g of epoxy-grafted recycled polyethylene, 0.3g of dopamine hydrochloride, 0.5g of phenylboronic acid and 2.0mL of anhydrous ethanol and add them to the reaction vessel. Stir until the mixture is homogeneous, then heat the reaction vessel to 95℃ and keep it at that temperature for 6 hours. After the reaction is complete, reduce the pressure and distill until no liquid is collected to obtain borate-modified recycled polyethylene.

[0057] Example 3

[0058] This embodiment provides a method for preparing borate ester modified recycled polyethylene, including the following steps:

[0059] Step ①: Prepare clean mulch film

[0060] Weigh 20.0g of waste plastic film and transfer it to a friction washing machine. The machine speed is 500rpm and the material filling rate is 40%. First, use 1wt% sodium hydroxide aqueous solution as the cleaning medium and clean for 15min. Then, use 0.6wt% citric acid as the cleaning medium and clean for 18min to obtain clean plastic film.

[0061] Step 2: Prepare clean mulch film granules

[0062] Weigh out 15.0g of clean mulch film, crush it, and then perform water washing and gravity separation at a water flow rate of 0.4m / s. After drying, continue to perform cyclone separation at a wind speed of 10m / s and 1200Pa to obtain clean mulch film particles.

[0063] Step ③: Preparation of epoxy-grafted recycled polyethylene

[0064] Weigh 10.0g of clean plastic film granules and 80.0mL of o-xylene and add them to the reaction vessel. Stir and purge with nitrogen to raise the temperature to 110℃ and keep stirring for 40min. Then add 1.5mL of glycidyl methacrylate and stir until homogeneous. Add 0.1g of benzoyl peroxide and maintain the temperature of the reaction vessel at 110℃ for 5h. After the reaction is complete, cool the reaction solution to 55℃ and pour it into 3 times the volume of 95wt% ethanol aqueous solution. After precipitation is complete, filter, collect the filter cake and dry it to obtain epoxy-grafted recycled polyethylene.

[0065] Step 4: Preparation of borate ester modified recycled polyethylene

[0066] Weigh out 10.0g of epoxy-grafted recycled polyethylene, 0.3g of dopamine hydrochloride, 0.4g of phenylboronic acid and 1.5mL of anhydrous ethanol and add them to the reaction vessel. Stir until the mixture is homogeneous, then heat the reaction vessel to 90℃ and keep it at that temperature for 5h. After the reaction is complete, reduce the pressure and distill until no liquid is collected to obtain borate ester modified recycled polyethylene.

[0067] Example 4

[0068] This embodiment provides a method for preparing hydroxycarbamate flexible polyurethane, including the following steps:

[0069] Step I: Preparation of bifunctional cyclic carbonate intermediates

[0070] Weigh 10.0g of bisphenol A diglycidyl ether and add it to a high-pressure reactor. After heating the high-pressure reactor to 110℃, introduce carbon dioxide at a molar amount 5 times that of the epoxy groups in the reaction system. Keep the reaction at this temperature for 8 hours. After the reaction is complete, cool to room temperature to obtain a bifunctional cyclic carbonate intermediate.

[0071] Step II: Preparation of hydroxycarbamate flexible polyurethane

[0072] Weigh 10.0g of the bifunctional cyclic carbonate intermediate and 2.0g of 1,6-hexanediamine and add them to the reaction vessel. Stir until the mixture is homogeneous, then heat the reaction vessel to 70℃ and keep it at that temperature for 8 hours. After the reaction is complete, cool it to room temperature to obtain hydroxyl urethane flexible polyurethane.

[0073] The epoxy group in the bisphenol A diglycidyl ether molecule undergoes a nucleophilic ring-opening insertion reaction under pressurized carbon dioxide. Carbon dioxide acts as a carbon source, intercalating into the epoxy structure and undergoing intramolecular cyclization to form a five-membered cyclic carbonate structure, thereby achieving the construction of a bifunctional cyclic carbonate intermediate. Under heating conditions in the presence of 1,6-hexanediamine, the carbonate ring undergoes selective ring-opening due to nucleophilic attack by the amine group, generating a polymeric structural unit containing both hydroxyl and urethane bonds. The molecular chain extends along the bifunctional reaction site, forming a polyurethane-type main chain structure linked by hydroxyl urethane bonds.

[0074] The bifunctional cyclic carbonate intermediate generated by the CO2 ring-opening carboxylation of bisphenol A diglycidyl ether, and the hydroxyl urethane flexible polyurethane obtained by its ring-opening polymerization with 1,6-hexanediamine, essentially introduce highly polar, strongly interacting, and relatively flexible polymeric segments into the recycled polyethylene system. The urethane bonds and hydroxyl groups can form a dense hydrogen-bonded network in both the solid and melt phases, significantly enhancing intermolecular forces and altering stress transmission, making it easier for external forces to be continuously transmitted between phase interfaces and chain segments rather than concentrated at defects. Simultaneously, the flexibility... The aliphatic segments increase the degree of freedom of movement of local segments, making the material exhibit more obvious viscoelastic dissipation characteristics and regulating melt flow behavior during stress and molding shearing. In addition, the bisphenol A backbone provides relatively rigid aromatic structural units, enabling the polyurethane segments to form a "soft-hard" structural difference in the system. This introduces more complex physical crosslinking and phase distribution at the microscopic level. Ultimately, through the combined mechanism of hydrogen bond network + polar interaction + segment compliance regulation + microphase structure difference, it affects the overall mechanical response, thermal behavior and processing rheological characteristics of recycled plastic dropper materials.

[0075] Example 5

[0076] This embodiment provides a method for preparing hydroxycarbamate flexible polyurethane, including the following steps:

[0077] Step I: Preparation of bifunctional cyclic carbonate intermediates

[0078] Weigh 12.0g of bisphenol A diglycidyl ether and add it to a high-pressure reactor. After heating the high-pressure reactor to 130℃, introduce carbon dioxide at a molar amount 8 times that of the epoxy groups in the reaction system. Keep the reaction at this temperature for 10 hours. After the reaction is complete, cool to room temperature to obtain a bifunctional cyclic carbonate intermediate.

[0079] Step II: Preparation of hydroxycarbamate flexible polyurethane

[0080] Weigh 12.0g of the bifunctional cyclic carbonate intermediate and 3.0g of 1,6-hexanediamine and add them to the reaction vessel. Stir until the mixture is homogeneous, then heat the reaction vessel to 90℃ and keep it at that temperature for 12h. After the reaction is complete, cool it to room temperature to obtain hydroxyl urethane flexible polyurethane.

[0081] Example 6

[0082] This embodiment provides a method for preparing hydroxycarbamate flexible polyurethane, including the following steps:

[0083] Step I: Preparation of bifunctional cyclic carbonate intermediates

[0084] Weigh 11.0g of bisphenol A diglycidyl ether and add it to a high-pressure reactor. After heating the high-pressure reactor to 120°C, introduce carbon dioxide at a molar amount 6 times that of the epoxy groups in the reaction system. Keep the reaction at this temperature for 9 hours. After the reaction is complete, cool to room temperature to obtain a bifunctional cyclic carbonate intermediate.

[0085] Step II: Preparation of hydroxycarbamate flexible polyurethane

[0086] Weigh 11.0g of the bifunctional cyclic carbonate intermediate and 2.5g of 1,6-hexanediamine and add them to the reaction vessel. Stir until the mixture is homogeneous, then heat the reaction vessel to 80℃ and keep it at that temperature for 10h. After the reaction is complete, cool it to room temperature to obtain hydroxycarbamate flexible polyurethane.

[0087] Example 7

[0088] This embodiment provides a method for preparing a high-toughness recycled plastic drip irrigation material based on waste plastic film, including the following steps:

[0089] Step 1: Preparation of silicon-oxygen ion-enhancing components

[0090] Weigh out 3.0 mL of vinyltrimethoxysilane, 2.0 mL of 3-(methacryloyloxy)propyltrimethoxysilane, 0.8 g of dopamine hydrochloride, 3.0 mL of deionized water and 10.0 mL of anhydrous ethanol and add them to the reaction vessel. After stirring evenly, heat to 40 °C and keep the temperature for 6 h. After the reaction is completed, reduce the pressure and distill until no liquid is collected to obtain the silicon-oxygen ion-enhanced component.

[0091] Vinyltrimethoxysilane and 3-(methacryloyloxy)propyltrimethoxysilane undergo alkoxysilane hydrolysis in a water-ethanol system. The -Si-OCH3 group is converted into silanol (-Si-OH) under the action of water molecules. Subsequently, the silanols form a silicon-oxygen network structure dominated by Si-O-Si bonds through condensation reactions. The catechol structure in the dopamine hydrochloride molecule interacts with the generated silanol or silicon-oxygen bond through hydrogen bonding and coordination in this reaction environment. This achieves a synergistic combination of organic aromatic structure and inorganic silicon-oxygen skeleton at the molecular scale, ultimately forming a composite silicon-oxygen ion-reinforced component containing silicon-oxygen bonds, aromatic structural units, and polymerizable unsaturated groups.

[0092] After the silicon-oxygen ion-reinforcing component formed in this step is incorporated into the recycled plastic dropper material system, the silicon-oxygen network units with Si-O-Si bonds as the core in its molecular structure exhibit highly polar inorganic-organic hybrid characteristics in the polymer matrix. On the one hand, the silicon-oxygen bonds and the silanol structures remaining after hydrolysis have high bond energy and polarity, and can participate in intermolecular interactions as rigid or semi-rigid nodes in the system, changing the arrangement and motion state of polymer chain segments through physical embedding, interface constraints, and polar interactions. On the other hand, the dopamine-derived aromatic catechol structure introduces multi-point formation into the system. The polar groups with hydrogen bonding and coordination enable the reinforcing component to act as an interfacial coupling and stress transfer bridge between the continuous polyethylene phase and the polar modified phase. In addition, the residual unsaturated organosilicon side groups enhance the physical entanglement between the reinforcing component and the polymer chain segments at the microscale, making the silicon-oxygen structure more stably dispersed in the matrix. The hybrid characteristics of the coexistence of rigid silicon-oxygen structure, polar interaction and flexible organic chain segments jointly regulate the microphase distribution, interfacial bonding mode and load transfer path in the recycled plastic dropper material, affecting its overall mechanical response, thermal behavior and processing rheological properties at the mechanistic level.

[0093] Step 2: Preparation of recycled plastic dropper material

[0094] The excipients are prepared by mixing antioxidant 1010, antioxidant 168, calcium stearate, ethylene bis-stearamide and talc in a mass ratio of 4:4:6:6:20.

[0095] By weight, 84 parts of the borate-modified recycled polyethylene prepared in Example 1, 24 parts of the silicon oxide ion-reinforced component prepared in Example 4, 10 parts of hydroxyl urethane flexible polyurethane, and 2 parts of auxiliary materials were weighed and added to a mixing tank and mixed evenly. The mixture was then added to a twin-screw extruder. The temperature of the feeding zone in the twin-screw extruder was 160°C, the temperature of the melting zone was 170°C, the temperature of the die zone was 180°C, and the screw speed was 100 rpm. The mixture was melt-extruded to obtain recycled plastic dropper material.

[0096] Under the combined action of melt shear and thermal field, borate-modified recycled polyethylene, as a continuous phase, fully melts and forms a flowable polymer matrix. The borate bonds exhibit certain dynamic reversibility characteristics within the processing temperature range, causing the polymer chain segments to rearrange under external forces. The inorganic-organic hybrid structure, mainly Si-O-Si, in the silicon-oxygen ion reinforcing component is embedded in the polyethylene system in the melt through physical dispersion and interfacial interaction. Its polar silicon-oxygen structure forms multiple non-covalent interactions with the modified polyethylene and other polar components. The hydroxyl urethane flexible polyurethane segments physically entangle with the polyethylene segments in the molten state and participate in the construction of intermolecular networks through hydrogen bonding. At the same time, antioxidants, lubricants, and inorganic fillers are uniformly dispersed in the high-shear environment. The components in the molten state form a structurally coupled multiphase polymer system through the synergistic effects of physical mixing, interfacial interaction, and dynamic bonding.

[0097] Example 8

[0098] This embodiment provides a method for preparing a high-toughness recycled plastic drip irrigation material based on waste plastic film, including the following steps:

[0099] Step 1: Preparation of silicon-oxygen ion-enhancing components

[0100] Weigh out 5.0 mL of vinyltrimethoxysilane, 3.0 mL of 3-(methacryloyloxy)propyltrimethoxysilane, 1.0 g of dopamine hydrochloride, 5.0 mL of deionized water and 15.0 mL of anhydrous ethanol and add them to the reaction vessel. After stirring evenly, heat to 60 °C and keep the temperature for 8 h. After the reaction is completed, reduce the pressure and distill until no liquid is collected to obtain the silicon-oxygen ion-enhanced component.

[0101] Step 2: Preparation of recycled plastic dropper material

[0102] The excipients are prepared by mixing antioxidant 1010, antioxidant 168, calcium stearate, ethylene bis-stearamide and talc in a mass ratio of 4:4:6:6:20.

[0103] By weight, 88 parts of the borate-modified recycled polyethylene prepared in Example 2, 27 parts of the silicon oxide ion-reinforced component prepared in Example 5, 12 parts of hydroxyl urethane flexible polyurethane, and 3 parts of auxiliary materials were weighed and added to a mixing tank and mixed evenly. The mixture was then added to a twin-screw extruder. The temperature of the feeding zone in the twin-screw extruder was 170°C, the temperature of the melting zone was 180°C, the temperature of the die zone was 190°C, and the screw speed was 120 rpm. The mixture was melt-extruded to obtain recycled plastic dropper material.

[0104] Example 9

[0105] This embodiment provides a method for preparing a high-toughness recycled plastic drip irrigation material based on waste plastic film, including the following steps:

[0106] Step 1: Preparation of silicon-oxygen ion-enhancing components

[0107] Weigh out 4.0 mL of vinyltrimethoxysilane, 2.5 mL of 3-(methacryloyloxy)propyltrimethoxysilane, 0.9 g of dopamine hydrochloride, 4.0 mL of deionized water and 12.0 mL of anhydrous ethanol and add them to the reaction vessel. After stirring evenly, heat to 50 °C and keep the temperature for 7 h. After the reaction is completed, reduce the pressure and distill until no liquid is collected to obtain the silicon-oxygen ion-enhanced component.

[0108] Step 2: Preparation of recycled plastic dropper material

[0109] The excipients are prepared by mixing antioxidant 1010, antioxidant 168, calcium stearate, ethylene bis-stearamide and talc in a mass ratio of 4:4:6:6:20.

[0110] By weight, 86 parts of the borate ester modified recycled polyethylene prepared in Example 3, 25 parts of the silicon oxide ion reinforced component prepared in Example 6, 12 parts of hydroxyl urethane flexible polyurethane, and 3 parts of auxiliary materials were weighed and added to a mixing tank and mixed evenly. The mixture was then added to a twin-screw extruder. The temperature of the feeding zone of the twin-screw extruder was 165°C, the temperature of the melting zone was 175°C, the temperature of the die zone was 185°C, and the screw speed was 110 rpm. The material was melt-extruded to obtain recycled plastic dropper material.

[0111] Comparative Example 1

[0112] The difference between this comparative example and Example 9 is that step ④ is omitted in the preparation process of the borate ester modified recycled polyethylene used in step two.

[0113] Comparative Example 2

[0114] The difference between this comparative example and Example 9 is that the use of the silicon oxide ion-enhancing component is omitted in step two.

[0115] Comparative Example 3

[0116] The difference between this comparative example and Example 9 is that step II of the preparation process of the hydroxycarbamate flexible polyurethane used in step II is omitted.

[0117] Performance testing:

[0118] The tensile strength, tensile yield stress, and tensile fracture stress of the recycled plastic dropper materials prepared in Examples 7-9 and Comparative Examples 1-3 were tested in accordance with the standard GB / T 1040.1-2025 "Determination of tensile properties of plastics - Part 1: General".

[0119] The notched cantilever impact strength of the recycled plastic dropper materials prepared in Examples 7-9 and Comparative Examples 1-3 was tested in accordance with the standard GB / T 1843-2008 "Determination of impact strength of plastic cantilever beam".

[0120] The load deformation temperature of the recycled plastic dropper materials prepared in Examples 7-9 and Comparative Examples 1-3 was tested according to the standard GB / T 1634.1-2025 "Determination of load deformation temperature of plastics - Part 1: General test method". The specific data are shown in Table 1.

[0121] Table 1 - Performance Test Data for Each Sample

[0122]

[0123] Data Analysis:

[0124] A comparative analysis of the data in Table 1 reveals that the plastic dropper material prepared in this invention has a tensile strength of 24.9 MPa, a tensile yield stress of 23.0 MPa, a tensile fracture stress of 23.8 MPa, and a cantilever beam notched impact strength of 7.4 kJ·m. -2 Simultaneously, the load deformation temperature was 91℃, and all data were superior to the comparative example. This indicates that:

[0125] In Comparative Example 1, after step ④ was removed, the material obtained in step ③ only achieved the grafting and introduction of epoxy functional groups, but did not further construct a boron-containing dynamic bonding structure. As a result, the continuous phase lacked reversible rearrangement molecular-level connecting units during melt shearing and service stress. During the blending process, the epoxy grafting sites tended to exhibit local polar point effects, and their interfacial coupling ability with the silicon oxide ion reinforcing component and polyurethane chain segments was discretized, making it difficult to form a continuous interfacial transition layer. Moreover, under stress, chain segment slippage and micro-debonding of the phase interface were more likely to occur first, the stress transmission path tended to be uneven, and local stress concentration was difficult to be dispersed to a larger scale structure in time. This caused the system to change from the "dynamic connection-interfacial synergy" operation mode to a loosely coupled structure mainly based on physical embedding.

[0126] In Comparative Example 2, after removing the silicon-oxygen ion reinforcing component, the system lacks an inorganic-organic hybrid constraint structure dominated by Si-O-Si bonds. This causes the structural support of the multiphase system to mainly rely on polyethylene chain segment entanglement, borate ester dynamic connection, and polyurethane hydrogen bonding. During melt blending, due to the lack of a hybrid skeleton to restrict and shape morphology evolution, the dispersion scale of the polyurethane phase in the matrix is ​​more likely to coarsen, the thickness and continuity of the interface layer are reduced, resulting in steeper structural boundaries between phase regions. Furthermore, under heated or continuous load conditions, the degree of freedom of chain segment thermal motion increases, and structural relaxation and phase interface migration are more likely to accumulate. This causes the system to change from a "skeleton constraint-interface coupling" structural configuration to a response mode that relies more on the short-range effects of organic chains.

[0127] In Comparative Example 3, after step II is removed, the system lacks flexible segmental units that can preferentially deform and participate in energy distribution under high strain or sudden load conditions. This causes the structural response of the material to be shared by the modified polyethylene continuous phase and the silicon-oxygen hybrid phase. During the melt blending stage, the original wetting, bridging, and interfacial gradient effects of the flexible polyurethane on the dispersed phase disappear, resulting in a decrease in the continuity of the interfacial transition layer. Clear boundaries and local weak bonding regions are more likely to form between phase regions. During service, when local stress concentration occurs, the structural channels that can delay the establishment of stress peak and disperse strain energy are reduced. Stress tends to accumulate in the rigid constraint region, and the passivation process of crack tips is restricted. This causes the system to shift from a "multi-scale dissipation-flexible buffer" mechanism to a more singular load-bearing and constraint-type response mode.

[0128] Ultimately, this solution demonstrates that performance is not achieved by simply stacking multiple material components, but rather through a systematic configuration of different structural units and their respective functional responses during processing and service. Specifically, the borate ester modified continuous phase participates in molecular-level bonding and rearrangement under stress and thermal fields, influencing stress transmission paths and interface evolution. The silicon-oxygen ion reinforcing component forms a relatively rigid inorganic-organic hybrid constraint structure within the system, restricting morphological stability and the range of chain segment movement. The hydroxyl urethane flexible polyurethane participates in wetting, bridging, and energy distribution processes in the interface region and under high strain conditions. In the comparative example, the absence of any structural unit leads to a shift in the system's operational mode, with stress transmission, morphological evolution, and energy dissipation processes becoming increasingly singular, making it difficult to maintain synergistic responses across multiple scales. Therefore, this solution, through the orderly introduction and synergistic configuration of multiple functional structural units, forms a composite material system with a clear operational logic.

[0129] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing high-toughness recycled plastic drip irrigation material based on waste plastic film, characterized in that, Includes the following steps: S1. After rubbing and cleaning the waste plastic film, clean plastic film is obtained; S2. After the clean mulch film is crushed, it is washed with water and gravity sorted. After drying, it is further sorted by cyclone to obtain clean mulch film particles. S3. Weigh out 84-88 parts of borate-modified recycled polyethylene, 24-27 parts of silica-oxygen ion reinforcing component, 10-12 parts of hydroxyl urethane flexible polyurethane and 2-3 parts of auxiliary materials by weight, add them to a mixing tank and mix evenly, then add them to a twin-screw extruder and melt extrude to obtain recycled plastic dropper material.

2. The method for preparing high-toughness recycled plastic drip irrigation material based on waste mulch film according to claim 1, characterized in that, In step S1, the friction cleaning operation is as follows: the waste plastic film is transferred to the friction washing machine, the machine speed is 400-600 rpm, the material filling rate is 30-50%, first use 1wt% sodium hydroxide aqueous solution as cleaning medium, clean for 15 minutes, and then use 0.5-0.8wt% citric acid as cleaning medium, clean for 15-20 minutes. In step S2, the water flow velocity for gravity separation is 0.3-0.5 m / s, the wind velocity for cyclone separation is 8-12 m / s, and the wind pressure is 1000-1500 Pa.

3. The method for preparing high-toughness recycled plastic drip irrigation material based on waste mulch film according to claim 1, characterized in that, In step S3, the auxiliary material is obtained by mixing antioxidant 1010, antioxidant 168, calcium stearate, ethylene bis-stearamide and talc in a mass ratio of 4:4:6:6:

20. The temperature of the feeding zone in the twin-screw extruder is 160-170℃, the temperature of the melting zone is 170-180℃, the temperature of the die zone is 180-190℃, and the screw speed is 100-120 rpm.

4. The method for preparing high-toughness recycled plastic drip irrigation material based on waste mulch film according to claim 1, characterized in that, The borate-modified recycled polyethylene is prepared by the following method: A1. Clean mulch film granules and o-xylene are added to a reaction vessel and stirred. After nitrogen protection, the temperature is raised to 105-115℃ and stirred for 40 min. Then glycidyl methacrylate is added. After stirring evenly, benzoyl peroxide is added. The temperature of the reaction vessel is maintained at 105-115℃ and stirred for 4-6 h. After the reaction is completed, the reaction solution is cooled to 50-60℃ and poured into 3 times the volume of 95wt% ethanol aqueous solution. After precipitation is complete, the filter cake is collected and dried to obtain epoxy-grafted recycled polyethylene. A2. Add epoxy-grafted recycled polyethylene, dopamine hydrochloride, phenylboronic acid and anhydrous ethanol to a reaction vessel and stir. After mixing evenly, heat the reaction vessel to 80-95℃ and keep it at that temperature for 4-6 hours. After the reaction is completed, reduce the pressure and distill until no liquid is collected to obtain borate ester modified recycled polyethylene.

5. The method for preparing high-toughness recycled plastic drip irrigation material based on waste mulch film according to claim 4, characterized in that, In step A1, the ratio of the clean mulch film particles, o-xylene, glycidyl methacrylate, and benzoyl peroxide is 10g:80mL:1-2mL:0.1g; in step A2, the ratio of the epoxy-grafted recycled polyethylene, dopamine hydrochloride, phenylboronic acid, and anhydrous ethanol is 10g:0.2-0.3g:0.3-0.5g:1-2mL.

6. The method for preparing high-toughness recycled plastic drip irrigation material based on waste mulch film according to claim 1, characterized in that, The preparation method of the silicon-oxygen ion-enhancing component is as follows: vinyltrimethoxysilane, 3-(methacryloyloxy)propyltrimethoxysilane, dopamine hydrochloride, deionized water and anhydrous ethanol are added to a reaction vessel, stirred evenly, and then heated to 40-60℃ and kept at the temperature for 6-8 hours. After the reaction is completed, the pressure is reduced and distilled until no liquid is collected to obtain the silicon-oxygen ion-enhancing component.

7. The method for preparing high-toughness recycled plastic drip irrigation material based on waste mulch film according to claim 6, characterized in that, In the preparation of the silicon-oxygen ion-enhancing component, the ratio of vinyltrimethoxysilane, 3-(methacryloyloxy)propyltrimethoxysilane, dopamine hydrochloride, deionized water and anhydrous ethanol is 3-5 mL: 2-3 mL: 0.8-1.0 g: 3-5 mL: 10-15 mL.

8. The method for preparing high-toughness recycled plastic drip irrigation material based on waste mulch film according to claim 1, characterized in that, The hydroxycarbamate flexible polyurethane is prepared by the following method: B1. Add bisphenol A diglycidyl ether to a high-pressure reactor, heat the high-pressure reactor to 110-130℃, introduce a calculated amount of carbon dioxide, keep the reaction at the temperature for 8-10 hours, and after the reaction is completed, cool to room temperature to obtain a bifunctional cyclic carbonate intermediate. B2. Add the bifunctional cyclic carbonate intermediate and 1,6-hexanediamine to the reaction vessel and stir. After the mixture is homogeneous, heat the reaction vessel to 70-90℃ and keep it at that temperature for 8-12 hours. After the reaction is complete, cool to room temperature to obtain hydroxyl urethane flexible polyurethane.

9. The method for preparing high-toughness recycled plastic drip irrigation material based on waste mulch film according to claim 8, characterized in that, In step B1, the amount of carbon dioxide used is 5-8 times the molar amount of epoxy groups in the reaction system; in step B2, the ratio of the amount of bifunctional cyclic carbonate intermediate to 1,6-hexanediamine is 10-12g:2-3g.

10. A high-toughness recycled plastic drip irrigation material based on waste plastic film, characterized in that, The high-toughness recycled plastic drip irrigation material based on waste mulch film is prepared by the preparation method of high-toughness recycled plastic drip irrigation material based on waste mulch film as described in any one of claims 1-9.

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