Preparation method and application of super-hydrophobic structure for preventing pesticide residues in pesticide spraying box of unmanned aerial vehicle

Abstract

The invention relates to the technical field of agricultural engineering, in particular to a preparation method and application of a super-hydrophobic structure for preventing pesticide residues in a pesticide spraying box of an unmanned aerial vehicle. Processing a cylindrical structure array on the surface of the plastic, and removing areas outside the cylindrical structure to obtain cylindrical structure plastic; the diameter of the cylindrical structure is 200-1000 [mu] m, and the spacing is 200-1000 [mu] m; dropwise adding a silicon dioxide solution on the surface of the plastic with the cylindrical structure to obtain the super-hydrophobic plastic; the mass percentage of the silicon dioxide solution is 4%. Plastic is manufactured into a micro-nano structure surface through a laser processing technology, and then the surface is treated through nano silicon dioxide, so that excellent super-hydrophobic performance and enhanced durability are achieved. Through the method, the pesticide spraying box is prepared from the super-hydrophobic plastic, so that residues of pesticide liquid on the side wall of the box body can be effectively reduced, the utilization rate of the pesticide liquid is increased, and stable performance is kept in long-term use.

Description

Technical Field

[0001] The present invention relates to the technical field of agricultural engineering, and particularly to a preparation method and application of a superhydrophobic structure for preventing pesticide residues in a pesticide spraying tank of an unmanned aerial vehicle (UAV). Background Art

[0002] With the rapid development of the technology of pesticide spraying by UAVs, as an important component thereof, the design and performance of the pesticide spraying tank directly affect the utilization efficiency of pesticides and environmental protection. At present, most pesticide spraying tanks of UAVs are made of common materials such as PP (polypropylene). The surfaces of these materials are easy to adsorb pesticide droplets, resulting in the attachment of droplets to the side walls of the tank, thus causing insufficient utilization of pesticides. The phenomenon of droplet adhesion not only causes pesticide residues in the spraying tank, reduces the spraying efficiency, but also requires additional treatment measures to clean the residual droplets, increasing the operation complexity and resource waste.

[0003] Therefore, solving the problem of droplet residues in the spraying tank has become an important research direction for improving the efficiency and sustainability of the technology of pesticide spraying by UAVs. Summary of the Invention

[0004] To solve the above problems, the present invention provides a preparation method and application of a superhydrophobic structure for preventing pesticide residues in a pesticide spraying tank of an UAV. The plastic is processed to form a micro-nano structure surface by laser processing technology, and then the surface is treated with nano-silica to achieve excellent superhydrophobic performance and enhanced durability. By this method, the superhydrophobic plastic is prepared into a spraying tank, which can effectively reduce the residues of the liquid medicine on the side walls of the tank, improve the utilization rate of the liquid medicine, and maintain stable performance during long-term use.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] The present invention provides a preparation method of a superhydrophobic structure for preventing pesticide residues in a pesticide spraying tank of an UAV, comprising the following steps:

[0007] 1) Processing an array of cylindrical structures on the surface of the plastic, and removing the areas other than the cylindrical structures to obtain cylindrical structure plastic;

[0008] The diameter of the cylindrical structure is 200-1000 μm, the spacing is 200-1000 μm, and the height is 270-310 μm;

[0009] 2) Dropping a silica solution on the surface of the cylindrical structure plastic obtained in the step 1) to obtain a superhydrophobic structure;

[0010] The mass percentage content of the silica solution is 4%.

[0011] Preferably, the diameter of the cylindrical structure in the step 1) is 400-800 μm.

[0012] Preferably, the diameter of the cylindrical structure is 600 μm.

[0013] Preferably, the spacing between the cylindrical structures in step 1) is 400 - 800 μm.

[0014] Preferably, the spacing between the cylindrical structures is 400 μm.

[0015] Preferably, in step 1), a nanosecond laser processing system is used for processing, and the processing parameters are: wavelength 355 nm, pulse width 10 ns, scanning speed 400 mm / s, processing current 4 A, focal position 40 cm, line spacing 10 μm, frequency 40 kHz, scanning area 25×25 mm 2 .

[0016] Preferably, in step 2), the area ratio of the plastic of the cylindrical structure to the volume of the silica solution is 625 mm 2 : 10 μL.

[0017] Preferably, after dropping the silica solution in step 2), it is left to dry naturally for 15 min to obtain the superhydrophobic plastic.

[0018] Preferably, the plastic in step 1) includes polypropylene plastic with a thickness of 3 mm.

[0019] The present invention also provides an application of the preparation method described in the above technical solution in improving the hydrophobicity of plastics.

[0020] The present invention also provides an application of the preparation method described in the above technical solution in increasing the contact angle of plastics.

[0021] Advantages of the present invention:

[0022] By combining nanosecond laser processing and chemical processes, microscale structures are prepared on the smooth surface of polypropylene plastic (PP), enabling nanostructures to adhere more firmly to the surface and embed inside the microscale structures, thereby effectively protecting the microscale structures and improving the superhydrophobic durability of the material. This processing method is simple and effective, significantly improving the performance of the spraying tank.

[0023] The present invention improves the surface cleaning problem of the spraying tank: The structured superhydrophobic surface significantly reduces the complexity of surface cleaning of the traditional spraying tank, avoids the problems of droplet wall hanging and residue, thereby reducing the time and labor costs required for cleaning and improving the operation efficiency.

[0024] The present invention simplifies the preparation process: The preparation method of the present invention is simple, completed by combining laser processing and chemical treatment, without the need for additional complex processing steps or expensive equipment, reducing the production cost, while improving the operability and practicability.

[0025] The present invention improves the durability of the material: By using laser processing technology on the surface of polypropylene to construct a micron-scale cylindrical array structure, the present invention significantly enhances the adhesion and structural stability of the material surface. The nanostructures can be more firmly embedded and protected within the micron structures, thereby greatly improving the durability and abrasion resistance of the material and extending the service life of the spraying tank.

[0026] The present invention enhances the superhydrophobic performance: By combining laser and nano-coating, the present invention constructs a multi-level micro-nano structure, improving the superhydrophobic performance of the material. This structure can not only effectively repel liquids but also prevent the attachment of pollutants, further enhancing the performance and maintenance convenience of the spraying tank.

[0027] In summary, the present invention provides an efficient, simple, and durable surface treatment method for the spraying tank, solves the problems of traditional spraying tanks in cleaning and maintenance, and significantly improves the service life and overall performance of the material. Brief Description of the Drawings

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments.

[0029] Figure 1 It is a schematic flowchart of the implementation steps of the present invention;

[0030] Figure 2 It is a schematic diagram of the laser cylindrical array processing path of the present invention, showing the processing path. By processing the black part, the remaining cylindrical array shape is obtained;

[0031] Figure 3 It is the initial static contact angle on the surface of the PP polypropylene sample, the unprocessed polypropylene material, and the contact angle is 88°;

[0032] Figure 4 It is the static contact angle on the surface of the PP polypropylene sample after only laser processing, and the contact angle is 127°. It can be seen that after laser processing, there is a significant impact on the surface wettability of the material;

[0033] Figure 5 It is the static contact angle on the surface of the PP polypropylene sample prepared by Example 10 of the present invention, and the contact angle is 157°. A superhydrophobic polypropylene surface with a cylindrical structure on the surface is obtained;

[0034] Figure 6 It is the test result of the static contact angle after only laser processing in Examples 1-5 and Comparative Example 1 with the cylindrical diameter changed;

[0035] Figure 7 It is the test result of the static contact angle after only laser processing in Example 1 and Examples 6-9 and Comparative Example 1 with the cylindrical column spacing changed;

[0036] Figure 8 Schematic diagram of the durability friction test in Example 10 and Comparative Example 2;

[0037] Figure 9 Change in static contact angle after friction test in Example 10;

[0038] Figure 10 Change in static contact angle after friction test in Comparative Example 2;

[0039] Figure 11 Test result diagram of Example 13;

[0040] Figure 12 EDS energy spectrum analysis diagram of Example 14;

[0041] Figure 13 EDS energy spectrum analysis diagram of Comparative Example 4. Detailed implementation method

[0042] The present invention provides a method for preparing a superhydrophobic structure for preventing pesticide residue in a pesticide spraying tank of an unmanned aerial vehicle, comprising the following steps:

[0043] 1) Process an array of cylindrical structures on the surface of the plastic, and remove the areas outside the cylindrical structures to obtain plastic with cylindrical structures;

[0044] The diameter of the cylindrical structure is 200 - 1000 μm, the spacing is 200 - 1000 μm, and the height is 270 - 310 μm;

[0045] 2) Drop a silica solution on the surface of the plastic with cylindrical structures obtained in step 1) to obtain a superhydrophobic structure;

[0046] The mass percentage content of the silica solution is 4%.

[0047] The present invention processes an array of cylindrical structures on the surface of the plastic, removes the areas outside the cylindrical structures to obtain plastic with cylindrical structures; the diameter of the cylindrical structure is 200 - 1000 μm, the spacing is 200 - 1000 μm, and the height is 270 - 310 μm. In the present invention, the diameter of the cylindrical structure is preferably 400 - 800 μm, more preferably 600 μm. In the present invention, the spacing of the cylindrical structures is preferably 400 - 800 μm, more preferably 400 μm. In the present invention, the processing preferably uses a nanosecond laser processing system, and the processing parameters are preferably: wavelength 355 nm, pulse width 10 ns, scanning speed 400 mm / s, processing current 4 A, focal position 40 cm, line spacing 10 μm, frequency 40 kHz, scanning area 25×25 mm 2。The present invention preferably uses a nanosecond laser to scan and process the plastic surface in the X and Y directions, removing the areas outside the cylindrical structure to form a smooth cylindrical array. In the present invention, the plastic preferably includes polypropylene plastic, and the thickness is preferably 3 mm.

[0048] Silica solution is dropped onto the surface of the obtained plastic with a cylindrical structure to obtain a superhydrophobic structure; the mass percentage content of the silica solution is 4%. In the present invention, the area of the plastic with a cylindrical structure to the volume of the silica solution is 625 mm 2 : 10 μL. The present invention ensures uniform coverage and an appropriate amount of solution, neither too much nor too little. If the amount of solution is too much, it may cause coating accumulation, forming a non-uniform coating with a large coating roughness, which is not conducive to obtaining stable superhydrophobicity, and the coating strength decreases, thereby affecting the nanostructure and superhydrophobic performance. If the amount of solution is too little, the surface of the PP polypropylene cannot be uniformly covered, resulting in incomplete formation of the nanostructure and affecting the hydrophobicity. Then, it is naturally dried for 15 min until the ethanol completely volatilizes, leaving a uniform nano-silica coating, thus forming the surface of the medicine spraying box with a micro-nano structure.

[0049] The present invention also provides the application of the preparation method described in the above technical solution in improving the hydrophobicity of plastics.

[0050] The present invention also provides the application of the preparation method described in the above technical solution in improving the contact angle of plastics.

[0051] To further illustrate the present invention, the present invention will be described in detail below in conjunction with embodiments, but they cannot be understood as limiting the protection scope of the present invention.

[0052] Example 1

[0053] First, a PP polypropylene sample (with a thickness of 3 mm) is ultrasonically cleaned for 10 minutes to remove surface contaminants, and then dried with nitrogen for standby. The pretreated PP polypropylene is fixed on the processing plane. The focal position of the laser is adjusted to ensure that the laser can be effectively focused on the sample surface. A cylindrical structure array with a diameter of 600 microns, a spacing of 400 microns, and a height range of 280 - 300 microns is processed on the sample surface. The surface of the medicine spraying box with a raised cylindrical structure is obtained.

[0054] Example 2

[0055] The difference between Example 2 and Example 1 is that: a cylindrical structure array with a diameter of 200 μm and a spacing of 400 microns is processed on the sample surface, and the others are the same.

[0056] Example 3

[0057] The difference between Example 3 and Example 1 is that: a cylindrical structure array with a diameter of 400 μm and a pitch of 400 μm is processed on the surface of the sample, and the others are the same.

[0058] Example 4

[0059] The difference between Example 4 and Example 1 is that: a cylindrical structure array with a diameter of 800 μm and a pitch of 400 μm is processed on the surface of the sample, and the others are the same.

[0060] Example 5

[0061] The difference between Example 5 and Example 1 is that: a cylindrical structure array with a diameter of 1000 μm and a pitch of 400 μm is processed on the surface of the sample, and the others are the same.

[0062] Comparative Example 1

[0063] The difference between Comparative Example 1 and Example 1 is that: no laser processing is performed on the surface of the sample.

[0064] The static contact angle test was carried out on the surface of the spraying tank with convex cylindrical structures prepared in Examples 1-5 and Comparative Example 1, and the results Figure 6 are shown. It can be seen from Figure 6 that different contact angles are obtained for different diameters of the cylindrical array, which are: 87.85°, 111.146°, 115.40°, 126.55°, 122.67°, 112.20°.

[0065] The surface of the convex cylindrical structure prepared in Example 1 has the largest contact angle, which is 126.55°.

[0066] It should be noted that Figure 6 the test results of the contact angle are the average values after 3 measurements on the surface.

[0067] Example 6

[0068] The difference between Example 6 and Example 1 is that: a cylindrical structure array with a diameter of 600 μm and a pitch of 200 μm is processed on the surface of the sample. The others are the same

[0069] Example 7

[0070] The difference between Example 7 and Example 1 is that: a cylindrical structure array with a diameter of 600 μm and a pitch of 600 μm is processed on the surface of the sample. The others are the same

[0071] Example 8

[0072] The difference between Example 8 and Example 1 is that: a cylindrical structure array with a diameter of 600 μm and a pitch of 800 μm is processed on the surface of the sample. The others are the same

[0073] Example 9

[0074] The difference between Example 9 and Example 1 is that: a cylindrical structure array with a diameter of 600 μm and a pitch of 1000 μm is machined on the surface of the sample. Others are the same.

[0075] The static contact angle results in Example 1, Examples 6 - 9 and Comparative Example 1 are as Figure 7 shown. When the column pitch is 400, the static contact angle is the largest. Different column pitches of the cylindrical array have different contact angles, which are: 87.85°, 118.96°, 126.55°, 118.36°, 114.04°, 99.00° respectively.

[0076] It should be noted that Figure 7 the test results of the contact angle are all the averages after 3 measurements on the surface.

[0077] Example 10

[0078] A preparation method of a superhydrophobic plastic for a spraying medicine box, the steps are as follows:

[0079] 1. Ultrasonically clean a PP polypropylene plastic sample (with a thickness of 3 mm) for 10 min to remove surface contaminants, and then dry it with nitrogen for standby.

[0080] 2. Fix the pretreated PP polypropylene plastic on the processing plane. Adjust the focal position of the laser to ensure that the laser can be effectively focused on the surface of the sample. Set up a nanosecond laser processing system, and fix the pretreated PP polypropylene on the processing plane. Adjust the focal position of the laser to ensure that the laser can be effectively focused on the surface of the sample. Set the processing area and laser parameters through the control system. The processing parameters are: wavelength 355 nm, pulse width 10 ns, scanning speed 400 mm / s, processing current 4 A, focal position 40 cm, line pitch 10 μm, frequency 40 kHz, scanning area 25×25 mm 2 , the same as Table 1. Select a cylindrical structure array with a diameter of 600 μm and a pitch of 400 μm on the surface of the sample. After processing, a cylindrical array with a height of 280 - 300 μm is obtained. At the four corners of the cylinder, the laser heat converges and the depth is slightly deeper; around the cylinder, the depth is shallower. Use a nanosecond laser to perform scanning processing on the PP polypropylene surface in the X and Y directions, and remove the area outside the cylindrical structure to form a smooth cylindrical array.

[0081] 3. Preparation of nanostructures: The coating of nano-silica should not be too thick, and the solubility of nano-silica in absolute ethanol is relatively low. Therefore, a 4% mass fraction solution is selected. Use an electronic balance to weigh 1.0 g of nano-silica and 24.0 g of absolute ethanol, and use a magnetic stirrer to stir at a speed of 750 r / min at 25 °C for 300 min to fully dissolve it by stirring. Mix the absolute ethanol and stir it until fully dissolved. Use a pipette to take 10 μL of the mixed solution and evenly drop it on the processed PP polypropylene surface, and let it dry for 15 min until the ethanol completely evaporates, leaving a uniform nano-silica coating. On a 25 mm × 25 mm pp sample piece, use a pipette to take 10 μL of the mixed solution and evenly drop it on the processed PP polypropylene surface to ensure uniform coverage and an appropriate amount of solution, neither too much nor too little. If the amount of solution is too much, it may cause coating accumulation, forming a non-uniform coating with a large coating roughness, which is not conducive to obtaining stable superhydrophobicity, and the coating strength decreases, thus affecting the nanostructure and superhydrophobic performance. If the amount of solution is too little, the PP polypropylene surface cannot be uniformly covered, resulting in incomplete formation of the nanostructure and affecting the hydrophobicity. Then let it dry for 15 minutes until the ethanol completely evaporates, leaving a uniform nano-silica coating, thereby forming the surface of the medicine spraying box with micro-nano structures, and the contact angle is 157°.

[0082] Table 1 Specific parameters of laser processing

[0083] Parameter Value Wavelength / nm 355 Pulse width / ns 10 Scanning speed mm / s 400 Processing current / A 4 Focus position / mm 40 Line spacing / μm 10 Frequency / kHz 40 Scanning area mm×mm 25×25

[0084] Example 11

[0085] The schematic diagram of the durability friction test is as Figure 8 shown. Use a superhydrophobic plastic with a cylindrical structure (prepared in Example 10) with a cylindrical parameter diameter of 600 μm and a column spacing of 400 μm and place it on 800-mesh sandpaper. Place a 500 g load on the sample surface, conduct cyclic friction, and record the change in the contact angle after different friction cycle times. Each cycle is 20 cm apart, and the contact angle data is measured once per cycle.

[0086] Comparative Example 2

[0087] The difference between Comparative Example 2 and Example 11 is that a superhydrophobic sample piece with a smooth and structureless surface is used, and the others are the same.

[0088] After the durability friction test on Example 10 and Comparative Example 2, the static contact angles are respectively as Figure 9 and Figure 10 shown.

[0089] When the friction cycle reaches 4 times, the superhydrophobic property of the superhydrophobic PP (polypropylene) with a smooth and structureless surface drops rapidly, and the contact angle decreases to 142.7±0.3°. However, for the superhydrophobic surface processed by laser, when the cycle number reaches 7 times, the surface can still maintain a superhydrophobic state with a contact angle of 151.3±0.5°. As the friction cycle number further increases to more than 8 times, the contact angle then decreases to 149.5±0.6°. Although it loses the superhydrophobic state, it still has good hydrophobic ability. The sandpaper wear experiment shows that the superhydrophobic PP (polypropylene) has excellent anti-friction and wear resistance. It should be noted that Figure 9 and Figure 10 the test results of the contact angle in

[0090] Example 12

[0091] The superhydrophobic plastic prepared in Example 10 of the present invention is applied to the surface of the spraying tank. The contact angle of a 2 μl droplet on the processed surface is less than 3°. After dropping onto the surface, it quickly rolls off.

[0092] Comparative Example 3

[0093] On the unprocessed (prepared in Comparative Example 1) sample piece, after a 2 μl liquid droplet drops, it shows strong adhesion. Even when the sample piece is inverted, the liquid droplet cannot drip off.

[0094] Example 13

[0095] The superhydrophobic plastic prepared in Example 10 of the present invention is applied to the surface of the spraying tank to verify the effect of the polypropylene sample piece with superhydrophobic surface technology in reducing pesticide residues. Selection and preparation of pesticides: Five common pesticides, namely monosultap, abamectin + spirotetramat, imidacloprid, deltamethrin, and pyraclostrobin + tebuconazole, are selected and configured into solutions according to the specified ratio to simulate the pesticide use situation in actual operation in the spraying tank. The above pesticide solutions are dropped onto the surface of the polypropylene sample piece processed by laser and coated with a superhydrophobic coating. The contact angle and rolling angle of the sample piece surface are measured every two minutes, and the total test time is set to 10 minutes. The test results in Example 13 are as Figure 11 shown.

[0096] The contact angle of the sample piece surface decreases slightly with time, but the overall change range is extremely small, and the rolling angle always remains below 3.5°. This shows that the superhydrophobic surface has excellent hydrophobic properties and effectively reduces the adhesion of pesticides on the surface. It should be noted that Figure 11 the test results of the contact angle in

[0097] Example 14

[0098] The superhydrophobic plastic prepared in Example 10 was applied to the surface of the spraying tank, taken out after being immersed in the imidacloprid pesticide solution for 10 minutes, and the energy dispersive spectrometer (EDS) was used to analyze the composition of the residues on the surface of the sample sheet.

[0099] Comparative Example 4

[0100] The untreated sample sheet was immersed in the imidacloprid pesticide solution for 10 minutes and then taken out, and the energy dispersive spectrometer (EDS) was used to analyze the composition of the residues on the surface of the sample sheet.

[0101] After the pesticide immersion of Example 14 and Comparative Example 4, the EDS energy spectrum analysis diagrams are respectively as Figure 12 、 Figure 13 shown.

[0102] There were obvious residues of Cl and K elements on the surface of the untreated sample sheet; while no residues were detected on the surface of the sample sheet treated by laser processing combined with the superhydrophobic coating, and the contents of Cl and K elements were 0. The treated sample sheet showed a good anti-pesticide residue effect.

[0103] Although the above embodiments have described the present invention in detail, they are only a part of the embodiments of the present invention, not all of them. People can also obtain other embodiments according to these embodiments without creative work, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A preparation method of a superhydrophobic structure for preventing pesticide residues in a pesticide spraying tank of a drone, characterized in that Comprising the following steps: 1) Processing an array of cylindrical structures on the surface of the plastic, removing the areas other than the cylindrical structures, to obtain cylindrical structure plastic; The diameter of the cylindrical structures is 200 - 1000 μm, the spacing is 200 - 1000 μm, and the height is 270 - 310 μm; 2) Dropping a silica solution on the surface of the cylindrical structure plastic obtained in step 1) to obtain a superhydrophobic structure; The mass percentage content of the silica solution is 4%.

2. The preparation method of the superhydrophobic structure according to claim 1, characterized in that In step 1), the diameter of the cylindrical structures is 400 - 800 μm.

3. The preparation method of the superhydrophobic structure according to claim 1 or 2, characterized in that, The diameter of the cylindrical structures is 600 μm.

4. The method for preparing the superhydrophobic structure according to claim 1, wherein In step 1), the spacing of the cylindrical structures is 400 - 800 μm.

5. The preparation method of the superhydrophobic structure according to claim 1, characterized in that, The processing in step 1) uses a nanosecond laser processing system, and the processing parameters are: wavelength 355 nm, pulse width 10 ns, scanning speed 400 mm / s, processing current 4 A, focal position 40 cm, line spacing 10 μm, frequency 40 kHz, scanning area 25×25 mm 2 .

6. The preparation method of the superhydrophobic structure according to claim 1, characterized in that, The area of the cylindrical structure plastic in step 2) is in a ratio of 625 mm 2 : 10 μL.

7. The preparation method of the superhydrophobic structure according to claim 1, characterized in that, After dropping the silica solution in step 2), air-dry naturally for 15 min to obtain superhydrophobic plastic.

8. The preparation method of the superhydrophobic structure according to claim 1, characterized in that, In step 1), the plastic includes polypropylene plastic with a thickness of 3 mm.

9. Application of the preparation method of the superhydrophobic structure according to any one of claims 1 - 8 in improving the hydrophobicity of plastics.

10. Application of the preparation method of the superhydrophobic structure according to any one of claims 1 - 8 in increasing the contact angle of plastics.

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