Biological clogging-resistant nano modified drip irrigation tape for underground drip irrigation system and application of drip irrigation tape

Abstract

The invention discloses an anti-biological clogging nano-modified drip irrigation tape for an underground drip irrigation system. The anti-biological clogging nano-modified drip irrigation tape comprises a drip irrigation tape nano-particle modified pipe wall and a drip irrigation tape nano-particle modified irrigation emitter. Nano copper oxide particles and nano zinc oxide particles are added into the drip irrigation emitter material of the drip irrigation tape, so that the antibacterial ability of the surface of the emitter and the ability of inhibiting root invasion are improved; a processing aid I consisting of maleic anhydride grafted polyethylene, sodium dodecyl benzene sulfonate and vinyl trimethoxy silane is added, so that the compatibility of the modified material for the drip irrigation emitter of the drip irrigation tape is improved. Nano magnesium hydroxide or nano titanium dioxide is added into the drip irrigation tape pipe wall material, so that the mechanical property of the drip irrigation tape pipe wall is improved; and a processing aid II consisting of polyethylene wax, a titanate coupling agent and maleic anhydride grafted polyethylene is added, so that the compatibility of the drip irrigation tape pipe wall modified material is improved. The invention further provides a drip irrigation tape modification effect evaluation method and an adaptive production process mode, and the problem of biological blockage of an underground drip irrigation system is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of water-saving irrigation, in particular to a nano-modified drip irrigation belt for underground drip irrigation system with anti-biological clogging properties and application thereof. Background Art

[0002] Due to years of underground operation, subsurface drip irrigation systems face a serious problem of bioclogging of emitters. This bioclogging can be categorized into two main types: one caused by microorganisms in the irrigation water that accumulate on the emitter surface, forming a biofilm; the other caused by underground crop roots invading the emitter flow path. Typically, when emitter blockage reaches a certain level, the drip tape must be replaced to ensure uniform irrigation. However, due to the high cost of replacing underground drip tapes due to their thick walls, this can lead to more severe blockages after years of operation. Emitter blockage can, at best, alter the emitter's hydraulic performance, reduce the system's irrigation uniformity, and affect crop growth and yield. It can also severely impact the system's operational effectiveness and safety, potentially leading to system failure.

[0003] Regarding blockage caused by underground crop roots invading the emitter flow path, two methods have been proposed to prevent root invasion in emitters using herbicides. First, adding herbicides to the emitter's masterbatch has a good root-repelling effect, but the release rate of the drug is uncontrollable. To achieve this, excessive amounts of herbicide must be added directly to the emitter's masterbatch, which can be harmful to users. Second, patent application number CN201710840324.X discloses an underground drip irrigation tape that resists root invasion and rodent and insect bites. This method uses microencapsulated herbicides into masterbatch and mixes them with the raw materials of the drip irrigation tape to achieve root-invasion resistance. However, this method is costly and unsuitable for large-scale application.

[0004] In addition, the walls of the drip irrigation tapes used in underground drip irrigation are generally thick, which significantly increases the replacement cost of underground drip irrigation. At present, although some products have attempted to modify the drip irrigation tapes with so-called nanomaterials, there is a lack of effective description of the most critical parameter involved in nanomaterial modification - nanoparticle size. Products related to nanomaterial modification do not mention the nanoparticle size, which is a factor that is crucial to the modification effect. The selection of the nanoparticle size range that is most effective in modifying the performance of the drip irrigation tape remains unresolved. In addition, how to comprehensively evaluate the performance of the modified drip irrigation tape based on performance, cost and other indicators is also a problem that needs to be solved.

[0005] In summary, there is currently a lack of a dedicated, bioclogging-resistant drip tape for underground drip irrigation, particularly one with a bioclogging-resistant material formula. Research on emitter anti-clogging capabilities has primarily focused on optimizing emitter design to improve emitter anti-clogging capabilities, without comprehensive consideration of multiple aspects, particularly antimicrobial formulations, material hydrophobicity and hydrophilicity, and root invasion resistance. There is currently a lack of stable, cost-effective modification methods for root invasion resistance. Due to the high wall thickness of underground drip tapes, research is urgently needed to explore methods for modifying underground drip tape materials and develop economical, specialized drip tape material formulas. Summary of the Invention

[0006] In response to the deficiencies in the prior art, the present invention aims to provide a nano-modified drip tape for an underground drip irrigation system that resists bioclogging and its application, which integrates the functions of inhibiting biofilm growth and preventing root invasion. By determining the appropriate particle size range of the nanoparticle-modified material for the drip tape wall, the compatibility of the nanoparticles with the PE material of the emitter is improved, and the performance degradation and uneven distribution of the emitter caused by the direct addition of nanoparticles into the PE material of the emitter is avoided. The wall thickness of the drip tape is reduced, its economic efficiency is improved, and a processing technology adaptation mode is proposed to solve the technical problem of biological clogging in the underground drip irrigation system.

[0007] In order to solve the above technical problems, the technical solution provided by the present invention is:

[0008] A nano-modified drip irrigation tape for underground drip irrigation system that resists biological clogging, the nano-modified drip irrigation tape comprising:

[0009] Drip irrigation tape nanoparticle modified emitter and drip irrigation tape nanoparticle modified pipe wall;

[0010] The drip irrigation tape nanoparticle modified emitter includes a drip irrigation tape emitter modified material and a processing aid;

[0011] The modified material for the drip irrigation tape emitter includes 80%-92% by weight of the emitter PE raw material, 0.5%-2% by weight of the masterbatch, 1%-5% by weight of the nano-metal oxide first particle, and 1%-5% by weight of the nano-metal oxide second particle. The nano-metal oxide first particle serves as a nano-particle modifier for inhibiting the attachment of biofilm to the emitter, and the nano-metal oxide second particle serves as a nano-particle modifier for inhibiting the invasion of roots from the surrounding environment into the emitter flow channel.

[0012] The processing aid 1 includes maleic anhydride grafted polyethylene at a mass ratio of 1%-5%, sodium dodecylbenzenesulfonate at a mass ratio of 0.5%-2%, and vinyltrimethoxysilane at a mass ratio of 0.2%-0.6%. The processing aid 1 is used to improve the compatibility of the modified material of the drip irrigation tape emitter;

[0013] The nanoparticle modified pipe wall of the drip irrigation tape comprises a drip irrigation tape pipe wall modification material and a processing aid;

[0014] The modified material for the drip irrigation tape wall includes 50%-60% by weight of recycled drip irrigation tape, 5%-15% by weight of high-density polyethylene, 10%-30% by weight of recycled greenhouse film, and 0.1%-2% by weight of metal oxide III; the metal oxide III is used to improve the mechanical properties of the drip irrigation tape wall;

[0015] The second processing aid includes polyethylene wax accounting for 0.1%-0.5% by mass, titanate coupling agent accounting for 0.1%-0.5% by mass, and maleic anhydride grafted polyethylene accounting for 1%-5% by mass; the second processing aid is used to improve the compatibility of the drip irrigation belt pipe wall modification material.

[0016] Preferably, the metal oxide has a particle size of 20-100 nm.

[0017] Preferably, the metal oxide is nano-magnesium hydroxide or nano-titanium dioxide.

[0018] Preferably, the nanoparticle metal oxide is nano zinc oxide.

[0019] Preferably, the nanoparticle metal oxide is nano-copper oxide.

[0020] Preferably, the evaluation method of the modified effect of the nano drip irrigation tape is: assigning different weights to the tensile strength, elastic modulus, elongation at break, Shore hardness, bursting pressure and economic cost indicators in an expert scoring manner, obtaining a comprehensive evaluation index score of the modified drip irrigation tape performance, and determining the modified effect of the drip irrigation tape;

[0021] The calculation formula of the comprehensive evaluation index score is shown in formula (1):

[0022] W=0.2×W DF +0.1×W ET +0.05×W EB +0.05×W SH +0.1×W BP +0.5×W EC (1)

[0023] Where: W is the comprehensive performance score; W DF W is the tensile strength index score; ET is the elastic modulus index score; W EB W is the elongation at break score; SH Shore hardness score; W BP W is the burst pressure index score; EC Score the economic cost indicator.

[0024] Preferably, the scores of the tensile strength, elastic modulus, elongation at break, Shore hardness, burst pressure and economic cost indicators are 1 to 5;

[0025] The tensile strength score is: ≤110, score 1; 111-132, score 2; 133-154, score 3; 155-176, score 4; >176, score 5;

[0026] The elastic modulus score is: ≤255, score 1; 256-285, score 2; 286-315, score 3; 316-345, score 4; >345, score 5;

[0027] The elongation at break is scored as follows: ≤200, score 1; 201-240, score 2; 241-280, score 3; 281-320, score 4; >320, score 5;

[0028] The elastic modulus score is: ≤255, score 1; 256-285, score 2; 286-315, score 3; 316-345, score 4; >345, score 5;

[0029] The Shore hardness rating is: ≤200, score 1; 201-240, score 2; 241-280, score 3; 281-320, score 4; >320, score 5;

[0030] The burst pressure score is: ≤52, score 1; 53-58, score 2; 59-65, score 3; 66-71, score 4; >71, score 5;

[0031] The economic cost scores are: ≥35%, score 1; 25-34%, score 2; 15-24%, score 3; 5-14%, score 4; <5, score 5.

[0032] Preferably, the production process mode of the nano-modified drip irrigation tape is adapted as follows:

[0033] The components of the modified material for the drip irrigation tape emitter are mixed in proportion, and a processing aid is added during the mixing process to form a modified drip irrigation tape emitter raw material; the modified emitter raw material is melt-granulated at a temperature gradient of 180-230° C. to form a masterbatch, and after the masterbatch is dried, it is injection-molded at an injection molding temperature of 220° C. and a pressure of 80 MPa to form a modified emitter;

[0034] The components of the drip irrigation tape wall modification material are mixed in proportion, and a second processing aid is added during the mixing process to form a modified drip irrigation tape wall raw material; the modified drip irrigation tape emitter raw material is processed into a modified drip irrigation tape wall by a screw extruder; the feed port temperature of the screw extruder is 180°C-190°C, the barrel section temperature is 220°C-240°C, and the flange, machine diameter, screen changer and die head temperature are 230°C-240°C;

[0035] After the modified water emitters are arranged on a vibrating screen plate, they are heated at 75°C to soften the surface through a conveyor line, and then bonded to the modified pipe wall at 90°C after extrusion; the bonded modified drip irrigation tape is water-cooled at 15°C to set the shape;

[0036] The production speed of the modified drip irrigation tape is 200-250m / min.

[0037] Application of any of the above-mentioned nano-modified drip irrigation tapes in preventing biological clogging in underground drip irrigation systems.

[0038] The beneficial effects of the present invention are:

[0039] (1) The present invention adds nano-zinc oxide particles and nano-copper oxide particles to the emitter material, inhibiting the growth of biofilm on the emitter surface, improving the antibacterial ability of the emitter surface and the ability to inhibit root invasion, and solving the problem of biological clogging in the emitter. The present invention also adds a processing aid composed of nano-maleic anhydride grafted polyethylene, sodium dodecylbenzenesulfonate, and vinyltrimethoxysilane to improve the compatibility between emitter materials.

[0040] (2) The present invention adds nanoparticle metal oxide to the drip irrigation tape wall material to improve the mechanical properties of the drip irrigation tape wall; and also adds a processing aid composed of polyethylene wax, titanate coupling agent, and maleic anhydride grafted polyethylene to improve the compatibility of the drip irrigation tape wall modified material;

[0041] (3) The present invention proposes a method for evaluating the modification effect of drip irrigation tapes, and screens out the optimal particle size range of nanoparticle modification to be between 20 nm and 100 nm, thereby reducing the cost of the nanoparticle tube wall;

[0042] (4) The present invention proposes that the temperature of the emitter conveyor line in the drip irrigation tape production line is controlled between 60°C and 80°C, the temperature of the screw extruder discharge port is between 180°C and 190°C, the temperature of the barrel section is between 220°C and 240°C, the temperature of the flange, machine diameter, screen changer and machine head is between 230°C and 240°C, the production speed of the drip irrigation tape should be controlled at 200-250m / min, and an improved production process model of the drip irrigation tape adapted to the nanoparticle material formula is adopted, so that the nanoparticle-modified emitter and the nanoparticle-modified drip irrigation tape can be produced normally. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0044] Figure 1 This is a technical roadmap for the preparation of the nano-modified drip irrigation tape for underground drip irrigation system to prevent biological clogging.

[0045] Figure 2 Element distribution map on the surface of nanoparticle-modified emitters

[0046] Figure 3 This is a graph showing the change in the degree of blockage of the antibacterial modified emitter and the dry weight of the blockage material.

[0047] Figure 4 The modification effect of nanoparticles of different particle sizes on drip irrigation tape

[0048] Figure 5 This is a characterization diagram of the anti-clogging effect and performance modification of underground drip irrigation emitters. a is the flow blockage degree of the drip irrigation system over time, b is the irrigation uniformity of the drip irrigation system, and c is the dry weight of the clogging material in the drip irrigation system. DETAILED DESCRIPTION

[0049] The following describes preferred embodiments of the present invention in conjunction with the accompanying drawings. It should be understood that the following embodiments are provided for illustrative purposes only and are not intended to limit the scope of the present invention. Those skilled in the art may make various modifications and substitutions to the present invention without departing from the purpose and spirit of the present invention.

[0050] Bioclogging of emitters in drip irrigation systems is primarily caused by biofilm adhesion and root invasion from the surrounding environment. To inhibit biofilm growth and root invasion on the emitter surface, the present invention proposes a nano-modified drip tape for underground drip irrigation systems and its application. The drip tape comprises a nanoparticle-modified emitter and a nanoparticle-modified pipe wall. Nanoparticles of metal oxide are added to the emitter to inhibit biofilm growth and root invasion on the emitter surface, while nanoparticles of metal oxide are added to the pipe wall to improve the mechanical properties of the pipe wall. Processing aids are also added to the modified materials for the pipe wall and emitter, respectively, to improve their compatibility. This solves the technical problem of bioclogging prevention and reduces the cost of the drip tape. The present invention also proposes a method for evaluating the modified drip tape effect and an adapted production process improvement model for the drip tape, enabling the normal production of the nanoparticle-modified emitter and the nanoparticle-modified drip tape.

[0051] The technical roadmap for preparing the nano-modified drip irrigation tape of the present invention is as follows: Figure 1As shown, the details are as follows:

[0052] 1. Preparation of Nanoparticle-modified Irrigators

[0053] Nano zinc oxide particles and nano copper oxide particles are mixed and added to the PE material of the drip irrigation tape emitter to enhance the antibacterial ability of the emitter surface and the ability to inhibit root invasion.

[0054] 1.1 Determine the method of adding nanoparticles

[0055] Physically blending nano-zinc oxide and nano-copper oxide particles into the PE material of the emitter can not only prevent bioclogging of the emitter, but also avoid any impact on the surrounding environment. This is because if the nanoparticles are directly released into the water source, they will diffuse into the surrounding environment with the water flow, significantly affecting not only microorganisms and plants and animals in the soil, but also continuing to spread to further areas, where the nanoparticles can penetrate into the internal organs of plants and animals, and the active substances they produce and their own nano-size can significantly affect their normal activities.

[0056] 1.2 Determine the concentration of nanoparticles

[0057] The appropriate nanoparticle concentration is crucial for improving the emitter's ability to inhibit bioclogging. Excessive nanoparticle content will not only form a large number of particle clusters in the emitter, affecting the emitter's production accuracy and quality, but also significantly reduce the adhesion between the emitter and the drip irrigation tape, causing it to leak. Excessively low nanoparticle content will result in the emitter's antibacterial properties being very low or even non-existent.

[0058] Nano-zinc oxide particles are used as a nanoparticle modifier to inhibit biofilm adhesion in emitters, while nano-copper oxide particles are used as a nanoparticle modifier to inhibit root invasion from the surrounding environment into the emitter flow channel. The mass blend ratio of nano-zinc oxide and nano-copper oxide particles ranges from 1% to 10%. Experimental verification shows that at a concentration below 1%, the dry weight of the biofilm remains virtually unchanged during long-term clogging tests, and the ability to inhibit root invasion is almost zero. However, at a concentration above 10%, not only is the economic cost higher, but the number of leaks caused by the reduced adhesion between the emitter and the drip irrigation pipe wall increases by 5-10 times.

[0059] A preliminary proposed nanoparticle modified formula for inhibiting biological clogging of emitters is as follows: the mass fraction of PE raw material of the emitter is 88%-95%, the mass fraction of masterbatch is 0.5%-2%, the mass fraction of nano zinc oxide particles is 1%-5%, and the mass fraction of nano copper oxide particles is 1%-5%.

[0060] 1.3 Preparation of processing aids to improve the compatibility of modified nanoparticle emitter materials

[0061] Directly adding nanoparticles to the PE material of the emitter will not only affect the performance of the emitter due to the low compatibility between the two, but also affect the performance of the modified material due to uneven distribution.

[0062] The present invention provides a processing aid for improving the fluidity of nanoparticles in an emitter, comprising maleic anhydride grafted polyethylene, sodium dodecylbenzenesulfonate and vinyltrimethoxysilane.

[0063] 1.3.1 Determine the proportion of each part of the processing aid in the emitter material

[0064] The right ratio is crucial for improving the compatibility between nanoparticles and the emitter material. Excessive amounts of maleic anhydride-grafted polyethylene, sodium dodecylbenzenesulfonate, and vinyltrimethoxysilane can not only destabilize the material's melt viscosity, thus affecting the injection molding of the emitter, but also affect the emitter's overall mechanical properties. Excessively low amounts of maleic anhydride-grafted polyethylene, sodium dodecylbenzenesulfonate, and vinyltrimethoxysilane can poorly disperse the nanoparticles and create insufficient interfacial bonding between the nanoparticles and polyethylene, limiting their ability to improve compatibility.

[0065] The present invention proposes a processing aid for improving the compatibility between nanoparticles and the PE material of the sprinkler, which comprises: maleic anhydride grafted polyethylene in a mass fraction ratio of 1%-5%; sodium dodecylbenzenesulfonate in a mass fraction ratio of 0.5%-2%; and vinyltrimethoxysilane in a mass fraction ratio of 0.2%-0.6%.

[0066] 1.4 Comprehensively determine the formulation of nanoparticle modified emitter materials and processing aids for drip irrigation tapes

[0067] The material formula for the emitter to prevent biological clogging is as follows: the mass fraction of PE emitter raw material is 80%-92%; the mass fraction of masterbatch is 0.5%-2%; the mass fraction of nano zinc oxide particles is 1%-10%; the mass fraction of nano copper oxide particles is 1%-10%; the mass fraction of maleic anhydride grafted polyethylene is 1%-5%; the mass fraction of sodium dodecylbenzene sulfonate is 0.5%-2%; and the mass fraction of vinyltrimethoxysilane is 0.2%-0.6%.

[0068] Maleic anhydride grafted polyethylene is used as a compatibilizer to enhance the interfacial polymerization of nanoparticles and polyethylene by providing polar groups. When the proportion of maleic anhydride grafted polyethylene is less than 1%, the fusion of nanoparticles cannot be effectively improved. At this time, the antibacterial effect of the nano-modified sprinkler is close to that without addition, and the dry weight of the clogging material is 8.2 mg / cm- 2 When the ratio is greater than 5%, the toughness of the modified emitter decreases significantly, and the drop hammer impact strength decreases from 48kJ / m- 2 Reduced to 41kJ / m- 2 Sodium dodecylbenzenesulfonate is a surfactant used to disperse nanoparticles and prevent them from agglomerating in PE. When the addition ratio is less than 0.5%, the dispersion effect of the nanoparticles is not obvious. At this time, the antibacterial effect of the nano-modified sprinkler is close to that without addition, and the dry weight of the clogging material remains at 8.2 mg / cm- 2 When the proportion is greater than 2%, the excess residue will cause bubbles and significantly weaken the strength of the emitter, and the tensile strength of the emitter will drop from 28MPa to about 26MPa. Vinyltrimethoxysilane is used as a coupling agent to strengthen the bond stability between nanoparticles and PE materials. When the proportion is less than 0.2%, the antibacterial effect of the nano-modified emitter is close to that without addition, and the dry weight of the clogging substance remains at 8.2mg / cm- 2 When its proportion is greater than 0.6%,

[0069] Depend on Figure 2 It can be seen that under the action of processing aid 1, nano copper oxide and nano zinc oxide particles are evenly and densely distributed on the surface of the emitter.

[0070] 1.5 Use the nano-antibacterial sprinkler to conduct a long-term accelerated clogging test on recycled water to verify the nano-antibacterial sprinkler's anti-biological clogging ability.

[0071] like Figure 3 The figure shows the blockage degree of the drip irrigation tape emitter and the distribution of the dry weight of the blockage material. Figure 3 It can be seen that the blue is the control group and the green is the experimental group. The nano antibacterial emitter significantly reduced the blockage degree of the drip irrigation system. The outflow rate of the drip irrigation system increased from about 72.5% of the CK group to about 89.3%, and significantly reduced the dry weight of the clogging material in the drip irrigation system. The dry weight was 13.8mg / cm- 2 Around reduced to 6.1mg / cm- 2 about.

[0072] 2. Preparation of Nanoparticle-Modified Tube Walls

[0073] In addition to the failure of underground drip irrigation systems caused by biological clogging, the high cost caused by the thick wall of the drip irrigation tape is also an important factor restricting the promotion of underground drip irrigation.

[0074] Nanoparticles are used as modifiers to modify the wall of the drip irrigation tape, thereby improving the mechanical properties of the drip irrigation tape wall, reducing the wall thickness of the drip irrigation tape and thus reducing the cost of using the drip irrigation tape.

[0075] 2.1 Determine the concentration of nanoparticle modifier

[0076] Appropriate nanoparticle concentration is crucial to the performance modification of drip irrigation tapes. Too high a nanoparticle blending amount will cause uneven dispersion of the nanoparticles in the drip irrigation tape, forming agglomeration, which will not only affect the surface properties of the drip irrigation tape, but also reduce the adhesion between the drip irrigation tape wall and the emitter, and also reduce the mechanical properties of the drip irrigation tape; too low a nanoparticle blending amount will reduce the modification effect on the drip irrigation tape wall, or even have no obvious modification effect.

[0077] When the added concentration of nanoparticles is 0.1%-2%, the tensile force range is 162N-175N. When the mass fraction is greater than 2%, the tensile force of the drip irrigation tape is between 151-164; when the mass fraction is less than 0.1%, the tensile force of the modified drip irrigation tape is about 161N. Therefore, the added concentration is determined to be between 0.1% and 2%.

[0078] 2.2 Preparation of modified materials for drip irrigation pipe wall

[0079] The nanoparticle-modified pipe wall material includes 50%-60% by weight of recycled drip irrigation tape, 5%-15% by weight of high-density polyethylene, 10%-30% by weight of recycled greenhouse film, and 0.1%-2% by weight of nano-magnesium hydroxide. Nano-magnesium hydroxide can also be replaced by nano-titanium dioxide.

[0080] 2.3 Preparation of processing aids to improve the compatibility of modified nanoparticle drip irrigation tape wall materials

[0081] Nanoparticles directly incorporated into the drip irrigation tape wall material have incompatible surface properties, causing the nanoparticles to easily form clusters within the material, thereby affecting the performance of the drip irrigation tape. The appropriate dosage of additives is crucial for improving the performance of both. Excessive dosage can cause the additives themselves to become foreign matter in the material, affecting its overall performance. Excessive dosage can have a minimal effect on improving the compatibility between the two materials.

[0082] The second processing aid for improving the compatibility between nanoparticle drip irrigation tape pipe wall materials of the present invention comprises: 0.1%-0.5% by mass of polyethylene wax, 0.1%-0.5% by mass of titanate coupling agent, and 1%-5% by mass of maleic anhydride grafted polyethylene.

[0083] Among them, polyethylene wax is used to improve the processing fluidity of PE and increase the dispersion of nanoparticles in PE. When its added mass fraction is greater than 0.5%, it will reduce the adhesion between the drip irrigation belt pipe wall and the sprinkler, causing the drip irrigation belt leakage phenomenon to increase from the original 0.1% to about 5%, which greatly affects the use experience of the drip irrigation belt. When its added mass fraction is less than 0.1%, the tensile performance of the drip irrigation belt is about 161N, which is no significant difference compared with the CK treatment without addition; titanate coupling agent is used to improve the binding force between nanoparticles and PE and improve the dispersion effect of nanoparticles in PE. When its added mass fraction is greater than 0.5%, it will also reduce the adhesion between the drip irrigation belt pipe wall and the sprinkler, and the drip irrigation belt leakage phenomenon will increase from the original 0.1% to about 3%, affecting the use of the drip irrigation belt. When the added mass fraction is less than 0.1%, the tensile performance of the drip irrigation belt At around 161N, there is no significant difference compared with the CK treatment without addition; maleic anhydride grafted polyethylene forms a bonding force with the surface of nanoparticles through polar groups, while maintaining compatibility with PE, thereby enhancing the interfacial bonding force. When the added mass fraction is greater than 5%, the rigidity of the material becomes stronger and it is easier to break during processing. The melt strength is around 14cN, which is a significant decrease from the 18cN of the CK treatment. When the added mass fraction is less than 1%, the tensile performance of the drip irrigation tape is around 161N, which is no significant difference compared with the CK treatment without addition.

[0084] 3. Propose a method to evaluate the modification effect of drip irrigation tape and evaluate the modification effect of nanoparticles with different particle sizes

[0085] The evaluation method for the modified effect of drip irrigation tape is to comprehensively consider the performance indicators and economic costs of the modified drip irrigation tape. By comparing the national standard (GB / T 19812.1-2017) and the performance and economic standards of the current drip irrigation tape, the performance indicators and economic costs of the modified drip irrigation tape are scored. The scoring range is shown in Table 1. Then, different weights are assigned to each indicator and economic cost through expert scoring, so as to obtain the score of the comprehensive evaluation index of the modified drip irrigation tape performance, and then determine the modified effect of the drip irrigation tape. During the use of drip irrigation tape, due to its large-scale use requirements, its economic cost is the core, and its weight is 0.5 by experts. Tensile strength is an important reference indicator for field laying and recycling. Its weight is 0.2 by experts. Elastic modulus and bursting pressure are used to ensure the basic performance of the drip irrigation tape. They are scored by experts at 0.1. The remaining indicators focus on auxiliary functions and have lower weights. They are scored by experts at 0.05. The calculation formula is shown in Formula 1:

[0086] W=0.2×W DF +0.1×W ET +0.05×W EB +0.05×W SH +0.1×W BP +0.5×W EC (1)

[0087] Where: W is the comprehensive performance score; W DF W is the tensile strength index score; ET is the elastic modulus index score; W EB W is the elongation at break score; SH Shore hardness score; W BP W is the burst pressure index score; EC Score the economic cost indicator.

[0088] Table 1 Comprehensive performance rating table of drip irrigation belt

[0089]

[0090] According to the comprehensive evaluation method of drip irrigation tape, the modification effect of nanoparticles with different particle sizes was evaluated, and the modification effect and comprehensive score of different nanoparticle sizes were obtained as follows: Figure 4 As shown in Table 2:

[0091] Table 2 Comprehensive scores of drip irrigation tapes modified with nanoparticles of different particle sizes

[0092]

[0093] According to the comprehensive evaluation results of nanoparticle modification, the present invention proposes that the most suitable nano magnesium hydroxide modified particle size range is 20nm-100nm. Different nanoparticle sizes have a greater impact on the modification effect of the drip irrigation tape material. Because the nanoparticle size is too small (<20nm), not only the small particle nanoparticle size processing difficulty and production cost are greatly increased, but also the specific surface area of ​​the small particle size nanoparticles is too large, the surface energy of each nanoparticle is very high, and the adsorption effect between particles becomes stronger, resulting in a stronger clustering effect of the nanoparticles in the PE material, thereby affecting the overall performance of the drip irrigation tape; when the nanoparticle size is too large (>100m), not only will the nanoparticle size be too large and result in poor dispersibility in the PE material, thereby making the clustering effect obvious, but also because the particle size is too large, the effect as a heterogeneous nucleating agent will be greatly reduced, which reduces the crystallization effect of the polymer chain and affects the overall mechanical properties of the drip irrigation tape. Finally, nanoparticles with a particle size of 20-100nm are selected.

[0094] By using the modified formula of the nanoparticle tube wall material proposed in the present invention, the wall thickness can be reduced by 0.015mm while still providing the same drip irrigation tape performance. The cost of the commonly used drip irrigation tape with a wall thickness of 0.2mm and a diameter of 16 can be reduced by about 3.56%.

[0095] 4. Improve the production process of drip irrigation tape and adapt the formula of nanoparticle materials

[0096] Nanoparticle modification changes the processing properties of the drip irrigation tape emitter and pipe wall materials. To ensure the proper production of the nanoparticle-modified emitters and drip irrigation tape proposed in this invention, the drip irrigation tape production process has been modified accordingly. The drip irrigation tape production line progresses from the emitter selection tray to the emitter conveyor line, then to the screw extruder, and then to the barrel, flange, machine diameter, screen changer, and die. At the die, the emitter sheet is bonded to the drip irrigation tape wall, followed by cooling, perforation, and winding.

[0097] 4.1 Temperature control of emitter conveyor line in drip irrigation tape production line

[0098] The temperature of the emitter conveyor line in the drip irrigation tape production line is controlled at 60℃-80℃. In the drip irrigation tape production line, the emitter sieve plate arranges the scattered emitters into a row of emitters that move in an orderly manner. The emitters are then transported along the emitter conveyor line to the drip irrigation tape pipe wall and bonded to the drip irrigation tape to form a drip irrigation tape.

[0099] At this time, the emitter conveyor line heats the emitter throughout its entire journey, allowing the emitter to reach a temperature state where it can bond with the drip irrigation tape wall when it reaches the bonding point with the drip irrigation tape wall. Nano-zinc oxide particles and nano-copper oxide particles are added to the emitter to enhance the emitter's antibacterial and root invasion resistance, thereby increasing the emitter's specific heat capacity. The heating temperature of the emitter conveyor line is adjusted so that the emitter can still maintain an appropriate temperature when it reaches the bonding point with the drip irrigation tape wall.

[0100] If the temperature of the emitter conveyor line is too high, the emitter will heat up too high, causing the shape of the emitter to change due to overheating, affecting the normal functioning of the emitter. If the temperature is too low, the emitter will be too low when it reaches the bonding point with the pipe wall, and the drip irrigation tape will not be able to bond well, which is prone to leakage.

[0101] 4.2 Temperature range control at each stage of screw extruder

[0102] Adjust the temperatures at the screw extruder's feed port, barrel section, flange, machine diameter, screen changer, and die head. The screw extruder is the machine that processes nano-modified pipe wall materials into drip irrigation tape. The incorporation of nanoparticles into the drip irrigation tape wall material significantly affects the properties of the original drip irrigation tape material. The appropriate temperature range is crucial for the processing of nanoparticle-modified drip irrigation tape, and targeted adjustments to the feed port, barrel section, flange, machine diameter, screen changer, and die head are necessary. If the temperature is too high, the nanoparticle-modified material will soften, adhere, or even decompose before the molten material reaches the extrusion port, hindering subsequent production and significantly impacting material properties. If the temperature is too low, the melt at the extrusion port will have poor fluidity, making it difficult to process and shape.

[0103] The present invention determines that the temperature range of each part of the screw extruder is that the temperature of the screw extruder feed port is between 180°C and 190°C, the temperature of the barrel section is between 220°C and 240°C, and the temperature of the flange, machine diameter, screen changer and die head is between 230°C and 240°C.

[0104] 4.3 Drip irrigation tape production speed control

[0105] The production speed of the drip irrigation tape should be controlled between 200-250m / min. The production speed of the drip irrigation tape production line is the rolling speed of the drip irrigation tape. When the nanoparticles modify the drip irrigation tape, they are almost evenly distributed in the drip irrigation tape material system under the action of the additive, which will improve the fluidity of the admixture in the molten state, thereby increasing the production speed of the drip irrigation tape. Accordingly, the production speed range of the nanoparticle-modified drip irrigation tape proposed in the present invention should be controlled between 200-250m / min.

[0106] Example

[0107] 5.1 According to the formula of nano-modified materials for anti-biological clogging sprinklers, high-density polyethylene (mass fraction 91.9%), nano-zinc oxide particles (2%), nano-copper oxide particles (2%), maleic anhydride grafted polyethylene (2%), sodium dodecylbenzenesulfonate (0.6%), vinyltrimethoxysilane (0.5%) and masterbatch (1%) were uniformly mixed in a high-speed mixer to form the modified sprinkler raw material.

[0108] During the mixing process, maleic anhydride grafted polyethylene acts as a compatibilizer, binding to the surface of nanoparticles through the polar groups of the molecular chain. At the same time, the non-polar segments are entangled with the PE matrix, significantly improving the dispersion of nanoparticles in the matrix; sodium dodecylbenzene sulfonate further prevents the agglomeration of nano-zinc oxide and copper oxide, ensuring their uniform distribution on the surface of the emitter.

[0109] The mixed raw materials are melted and granulated at a temperature gradient of 180-230°C through a twin-screw extruder. The granulated masterbatch is dried and then fed into an injection molding machine to be molded into a labyrinth flow channel water emitter at an injection molding temperature of 220°C and a pressure of 80MPa.

[0110] 5.2 According to the pipe wall material modification formula, the recycled material of drip irrigation tape (70%), recycled material of greenhouse film (10%), high-density polyethylene (13.7%), nano-magnesium hydroxide with a particle size range of 30nm-60nm (0.8%), polyethylene wax (0.3%), titanate coupling agent (0.2%) and maleic anhydride grafted polyethylene (5%) are mixed evenly.

[0111] Among them, nano-magnesium hydroxide, after being surface-modified with a titanate coupling agent, works together with polyethylene wax to form a uniformly dispersed reinforced network structure in the recycled PE matrix, thereby improving the tensile strength and impact resistance of the pipe wall.

[0112] The mixed material is processed into the drip irrigation tape wall through a single-screw extruder. During the extrusion process, the feed inlet temperature is set at 180°C to prevent premature melting of the raw material and blockage. The barrel temperature is maintained at 220°C to ensure full plasticization of the melt. The flange, die diameter, and die head temperatures are controlled at 235°C to ensure a smooth, defect-free surface. The final extruded tube has a wall thickness of 0.4mm, which is 33% thinner than traditional underground drip irrigation tape. The tube diameter is 16mm and the burst pressure reaches 350kPa, meeting the requirements of the national standard GB / T 19812.1-2017.

[0113] 5.3 The modified emitters are bonded to the nano-modified pipe wall on a drip irrigation tape production line. After being arranged on a vibrating screen, the emitters are heated at 75°C to soften the surface on a conveyor line. After extrusion, they are bonded to the pipe wall at 90°C. The bonded drip irrigation tape is then water-cooled at 15°C to prevent deformation due to thermal stress.

[0114] During the production process, the temperature of the sprinkler conveyor line is strictly controlled within the range of 60-80°C. When the temperature is lower than 60°C, the bonding strength is insufficient, and when the temperature is higher than 80°C, the sprinkler flow channel structure will be deformed. The adaptation of the screw extruder temperature gradient and the production speed (250m / min) not only ensures the uniform dispersion of nanoparticles in the tube wall, but also avoids tube wall defects caused by melt fracture or uneven cooling.

[0115] 5.4 To verify the performance of the drip irrigation tape, accelerated clogging tests and field trials were conducted. In the accelerated test, after 900 hours of operation in recycled water, the modified emitter's flow rate decreased to approximately 82.1% of its initial flow rate, while that of the conventional emitter decreased to approximately 72.2% of its initial flow rate. Scanning electron microscopy revealed that the emitter surface was densely populated with nano-zinc oxide and copper oxide particles, significantly enhancing the emitter's antibacterial and root invasion-inhibiting properties.

[0116] In addition, due to the reinforcing effect of nanoparticles on the modified pipe wall, the tensile force and elastic modulus of the modified drip irrigation tape with a wall thickness of 0.185 mm are 160 N and 330 MPa respectively, and the tensile force and elastic modulus of the unmodified drip irrigation tape with a wall thickness of 0.2 mm are 161 N and 321 MPa respectively. The performance of the two is very close, but the cost of the modified drip irrigation tape is reduced by about 7.3%.

[0117] According to the comprehensive evaluation method proposed in the present invention, the modification effects of nano magnesium hydroxide with different particle sizes were scored. The results showed that the nanoparticle modified drip irrigation tape with a particle size of 20-100nm had a comprehensive score of 3.75 points (Table 2), and its dispersibility, enhancement effect and economy were the best; while the particles with a particle size of less than 20nm had a score of 3.57 points due to severe agglomeration, and the particles with a particle size greater than 100nm had a score of only 3.46 points due to uneven dispersion and weak enhancement effect. The above results confirm that 20-100nm is the optimal particle size range for nanoparticle modification.

[0118] The actual flow rate of the drip irrigation system emitter is affected by the ambient temperature, working pressure, and the degree of emitter blockage. In this experiment, the drip irrigation system was always operated under 0.1MPa conditions. Therefore, the emitter flow rate deviation is mainly caused by the ambient temperature. This experiment uses the flow rate water temperature correction formula proposed by Pei et al., which is shown in formula (2):

[0119]

[0120] Where: is the flow rate after temperature correction (L / h); T i is the water temperature during flow test (℃); q 20 is the rated flow rate at 20℃; x is the emitter flow index; q 20 and x are obtained by testing before the experiment begins.

[0121] The actual outflow rate of the emitter can be used to calculate the relative average flow rate (Dra) of the emitter after being corrected by the temperature-flow correction formula to determine the blockage degree of the emitter. The calculation formula is shown in formula (3):

[0122]

[0123] Where: qit m is the correction flow rate of the i-th emitter (L / h); qi0 m is the rated flow rate (L / h) of the emitter after calibration when the drip irrigation system is first operated; n is the number of emitters on the capillary tube, which is 59 in this test.

[0124] Figure 5a and b compare the blockage of the ordinary emitter and the emitter of the present invention. It can be seen that the blockage accumulation of the flow channel of the modified emitter is significantly lower than that of the ordinary emitter. The outflow rate of the drip irrigation system is increased from 72% to 81.6% ( Figure 5 a), the water uniformity of the drip irrigation system increased from 68.5% to 79.1% ( Figure 5 b); Figure 5 c shows that the dry weight of the clogging material is 14.3 mg / cm 2 Reduced to 8.7 mg / cm 2 , further proving its anti-biofilm ability.

[0125] The present invention achieves the goals of long-term anti-clogging, thin-wall and low-cost underground drip irrigation belts through the integration of material formulation, production process and performance evaluation system, providing reliable technical support for the sustainable development of water-saving agriculture.

[0126] The contents not described in detail in this specification belong to the prior art known to those skilled in the art.

[0127] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A nano-modified drip irrigation tape for underground drip irrigation system that resists biological clogging, characterized in that: The nano-modified drip irrigation tape comprises: Drip irrigation tape nanoparticle modified emitter and drip irrigation tape nanoparticle modified pipe wall; The drip irrigation tape nanoparticle modified emitter includes a drip irrigation tape emitter modified material and a processing aid; The modified material for the drip irrigation tape emitter includes 80%-92% by weight of the emitter PE raw material, 0.5%-2% by weight of the masterbatch, 1%-5% by weight of the nano-metal oxide first particle, and 1%-5% by weight of the nano-metal oxide second particle. The nano-metal oxide first particle serves as a nano-particle modifier for inhibiting the attachment of biofilm to the emitter, and the nano-metal oxide second particle serves as a nano-particle modifier for inhibiting the invasion of roots from the surrounding environment into the emitter flow channel. The processing aid 1 includes maleic anhydride grafted polyethylene at a mass ratio of 1%-5%, sodium dodecylbenzenesulfonate at a mass ratio of 0.5%-2%, and vinyltrimethoxysilane at a mass ratio of 0.2%-0.6%. The processing aid 1 is used to improve the compatibility of the modified material of the drip irrigation tape emitter; The nanoparticle modified pipe wall of the drip irrigation tape comprises a drip irrigation tape pipe wall modification material and a processing aid; The modified material for the drip irrigation tape wall includes 50%-60% by weight of recycled drip irrigation tape, 5%-15% by weight of high-density polyethylene, 10%-30% by weight of recycled greenhouse film, and 0.1%-2% by weight of nano-metal oxide III; the nano-metal oxide III is used to improve the mechanical properties of the drip irrigation tape wall; The second processing aid includes polyethylene wax accounting for 0.1%-0.5% by mass, titanate coupling agent accounting for 0.1%-0.5% by mass, and maleic anhydride grafted polyethylene accounting for 1%-5% by mass; the second processing aid is used to improve the compatibility of the drip irrigation belt pipe wall modification material.

2. The anti-biological clogging nano-modified drip irrigation tape for underground drip irrigation system according to claim 1, characterized in that: The nano metal oxide three is nano magnesium hydroxide or nano titanium dioxide.

3. The anti-biological clogging nano-modified drip irrigation tape for underground drip irrigation system according to claim 1, characterized in that: The particle size of the nano metal oxide is 20-100 nm.

4. The anti-biological clogging nano-modified drip irrigation tape for underground drip irrigation system according to claim 1, characterized in that: The nanoparticle metal oxide is nano zinc oxide.

5. The anti-biological clogging nano-modified drip irrigation tape for underground drip irrigation system according to claim 1, characterized in that: The second nanoparticle metal oxide is nano copper oxide.

6. The anti-biological clogging nano-modified drip irrigation tape for underground drip irrigation system according to claim 1, characterized in that: The evaluation method for the modified effect of the nano drip irrigation tape is as follows: different weights are assigned to the tensile strength, elastic modulus, elongation at break, Shore hardness, bursting pressure, and economic cost indicators in an expert scoring manner to obtain a comprehensive evaluation index score of the modified drip irrigation tape performance and determine the modified effect of the drip irrigation tape; The calculation formula of the comprehensive evaluation index score is shown in formula (1): W=0.2×W DF +0.1×W ET +0.05×W EB +0.05×W SH +0.1×W BP +0.5×W EC (1) Where: W is the comprehensive performance score; W DF W is the tensile strength index score; ET is the elastic modulus index score; W EB W is the elongation at break score; SH Shore hardness score; W BP W is the burst pressure index score; EC Score the economic cost indicator.

7. The anti-biological clogging nano-modified drip irrigation tape for underground drip irrigation system according to claim 6, characterized in that: The tensile strength, elastic modulus, elongation at break, Shore hardness, burst pressure and economic cost indicators are scored on a scale of 1 to 5; The tensile strength score is: ≤110, score 1; 111-132, score 2; 133-154, score 3; 155-176, score 4; >176, score 5; The elastic modulus score is: ≤255, score 1; 256-285, score 2; 286-315, score 3; 316-345, score 4; >345, score 5; The elongation at break is scored as follows: ≤200, score 1; 201-240, score 2; 241-280, score 3; 281-320, score 4; >320, score 5; The elastic modulus score is: ≤255, score 1; 256-285, score 2; 286-315, score 3; 316-345, score 4; >345, score 5; The Shore hardness rating is: ≤200, score 1; 201-240, score 2; 241-280, score 3; 281-320, score 4; >320, score 5; The burst pressure score is: ≤52, score 1; 53-58, score 2; 59-65, score 3; 66-71, score 4; >71, score 5; The economic cost scores are: ≥35%, score 1; 25-34%, score 2; 15-24%, score 3; 5-14%, score 4; <5, score 5.

8. The anti-biological clogging nano-modified drip irrigation tape for underground drip irrigation system according to claim 1, characterized in that: The production process mode of the nano-modified drip irrigation tape is adapted as follows: The components of the modified material for the drip irrigation tape emitter are mixed in proportion, and a processing aid is added during the mixing process to form a modified drip irrigation tape emitter raw material; the modified emitter raw material is melt-granulated at a temperature gradient of 180-230° C. to form a masterbatch, and after the masterbatch is dried, it is injection-molded at an injection molding temperature of 220° C. and a pressure of 80 MPa to form a modified emitter; The components of the drip irrigation tape wall modification material are mixed in proportion, and a second processing aid is added during the mixing process to form a modified drip irrigation tape wall raw material; the modified drip irrigation tape emitter raw material is processed into a modified drip irrigation tape wall by a screw extruder; the feed port temperature of the screw extruder is 180°C-190°C, the barrel section temperature is 220°C-240°C, and the flange, machine diameter, screen changer and die head temperature are 230°C-240°C; After the modified water emitters are arranged on a vibrating screen plate, they are heated at 75°C to soften the surface through a conveyor line, and then bonded to the modified pipe wall at 90°C after extrusion; the bonded modified drip irrigation tape is water-cooled at 15°C to set the shape; The production speed of the modified drip irrigation tape is 200-250m / min.

9. Use of the nano-modified drip irrigation tape according to any one of claims 1 to 8 in preventing biological clogging in underground drip irrigation systems.

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