Impact-resistant and breakage-resistant composite drag reduction film for aviation and preparation process thereof

Abstract

The invention discloses an impact-resistant and breakage-resistant composite drag reduction film for aviation and a preparation process thereof, and relates to the technical field of drag reduction films. The impact-resistant and breakage-resistant composite resistance-reducing film for aviation comprises a release protective layer, an adhesive anti-falling layer, a substrate weather-resistant layer, a resistance-reducing functional layer and a self-cleaning coating which are sequentially stacked from bottom to top, the adhesive anti-stripping layer is obtained by coating one surface of the substrate weather-proof layer with an acrylic resin adhesive and carrying out thermocuring; the resistance reducing functional layer is obtained by coating the other surface of the substrate weather-proof layer with UV curing resin and forming a small rib microstructure through thermal-optical dual curing; the self-cleaning coating is obtained by spraying a self-cleaning coating on the surface of the drag reduction functional layer and drying the self-cleaning coating.

Description

Technical Field

[0001] This invention relates to the field of drag-reducing membrane technology, specifically to an impact-resistant and burst-resistant composite drag-reducing membrane for aerospace applications and its preparation process. Background Technology

[0002] During flight, aerodynamic drag on the aircraft surface directly affects fuel efficiency and range. Composite drag-reducing membranes have become key materials for reducing drag, but the harsh environment at high altitudes poses multiple challenges to their performance. Existing drag-reducing membranes generally suffer from an imbalance in overall performance: while membranes based on thermoplastic polyurethane possess basic toughness, they are prone to embrittlement and cracking after long-term service due to insufficient resistance to ultraviolet radiation and thermo-oxidative aging, resulting in significant degradation of mechanical properties.

[0003] Drag-reducing functional layers often rely on a single curing method for molding, resulting in poor microstructural stability and weak bonding with the substrate interface, making them prone to peeling under airflow impact. Meanwhile, traditional reinforcing fillers have poor compatibility with the matrix; while they can improve strength, they sacrifice elongation at break, making it difficult to balance impact resistance and burst strength.

[0004] Based on this, the present invention provides an impact-resistant and burst-resistant composite drag-reducing membrane for aviation and its preparation process, which is of great significance. Summary of the Invention

[0005] The purpose of this invention is to provide an impact-resistant and burst-resistant composite drag-reducing membrane for aviation and its preparation process, so as to solve the problems mentioned in the background art.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: An aerospace impact-resistant and burst-resistant composite drag-reducing membrane, which is stacked from bottom to top as follows: a release protective layer, an adhesive anti-detachment layer, a base weather-resistant layer, a drag-reducing functional layer, and a self-cleaning coating; The adhesive anti-detachment layer is obtained by coating one side of the base weather-resistant layer with a thermosetting acrylic resin adhesive and then heat-curing it. The drag-reducing functional layer is obtained by coating a polyurethane acrylate UV-curable resin onto the other side of the substrate weather-resistant layer and then curing it with heat and light to form a small rib microstructure. The weather-resistant base layer is prepared from the following raw material components in parts by weight: 50 parts thermoplastic polyurethane elastomer, 3-6 parts vinyl MQ resin, 5-10 parts modified lignin-zinc oxide composite, 4-8 parts modified cerium dioxide, 2-4 parts color masterbatch, 0.5-1 part antioxidant, and 0.1-0.15 parts dicumyl peroxide. The self-cleaning coating is obtained by spraying self-cleaning paint onto the surface of the drag-reducing functional layer and then drying it.

[0007] Furthermore, the thickness of the weather-resistant layer of the substrate is 50~100μm.

[0008] Furthermore, the thickness of the adhesive anti-detachment layer is 30~50μm; Furthermore, the height of the rib microstructure is 20~50μm.

[0009] Furthermore, the thickness of the self-cleaning coating is 10~20μm.

[0010] Furthermore, the preparation process of the aerospace-grade impact-resistant and burst-resistant composite drag-reducing membrane includes the following steps: Step 1: Add thermoplastic polyurethane elastomer, vinyl MQ resin, modified lignin-zinc oxide composite, modified cerium dioxide, color masterbatch, antioxidant, and dicumyl peroxide into a mixer, stir and mix evenly, and then extrude through a twin-screw extruder to obtain the base weather-resistant layer. Step 2: Apply thermosetting acrylic resin adhesive to one side of the weather-resistant base layer, and heat-cure to obtain an adhesive anti-detachment layer; then attach a release protective film to the adhesive anti-detachment layer to obtain a release protective layer. Step 3: Apply polyurethane acrylate UV-curable resin to the other side of the substrate weather-resistant layer, and then heat-cur it and light-cur it with a mold roller to form a small rib microstructure, thus obtaining a drag-reducing functional layer. Step 4: Spray the self-cleaning coating onto the surface of the drag-reducing functional layer, and after drying, obtain the self-cleaning coating; then perform laser perforation and laser cutting to obtain the aerospace-grade impact-resistant and burst-resistant composite drag-reducing film.

[0011] Furthermore, the preparation method of the modified lignin-zinc oxide complex is as follows: (1) Under nitrogen protection, demethylated lignin and maleic anhydride were added to acetic acid and stirred at 30-40°C for 2-6 hours. After the reaction was stopped, maleic anhydride-modified lignin was obtained by vacuum distillation. (2) Under nitrogen protection, maleic anhydride modified lignin, 2,3-epoxypropyltrimethylammonium chloride and 3,5-diisopropylsalicylic acid chromium were added to deionized water, stirred and heated to 70~80℃, and stirred for 2~6h; then 2-hydroxy-4-propenoxybenzophenone and azobisisobutyronitrile were added, and the mixture was kept warm and stirred for 1~3h. The reaction was then stopped, purified by dialysis, and freeze-dried to obtain modified lignin. (3) Under nitrogen protection, zinc acetate dihydrate was added to deionized water and stirred to obtain zinc acetate aqueous solution; modified lignin was added to 5wt% sodium hydroxide aqueous solution and stirred to obtain modified lignin solution; zinc acetate aqueous solution was added to modified lignin solution, stirred and heated to 80~90℃, kept warm for 2~6h, the reaction was stopped, the pH of the system was adjusted to 7.8~8.5, aged, centrifuged, washed and dried to obtain modified lignin-zinc oxide complex.

[0012] Furthermore, the demethylated lignin is prepared according to the method disclosed in CN107177026A.

[0013] Furthermore, the preparation of maleic anhydride-modified lignin includes the following raw material components in parts by weight: 5 parts of demethylated lignin, 1-2 parts of maleic anhydride, and 30 parts of acetic acid.

[0014] Further, the modified lignin preparation comprises the following raw material components in parts by weight: 5 parts maleic anhydride modified lignin, 1-2 parts 2,3-epoxypropyltrimethylammonium chloride, 0.05-0.15 parts chromium 3,5-diisopropylsalicylate, 0.5-1.5 parts 2-hydroxy-4-propenoxybenzophenone, 0.05-0.15 parts azobisisobutyronitrile, and 30 parts deionized water.

[0015] Furthermore, the preparation of the modified lignin-zinc oxide composite includes the following raw material components in parts by weight: 4-6 parts of zinc acetate dihydrate, 5 parts of modified lignin, 50 parts of deionized water, and 50 parts of sodium hydroxide aqueous solution.

[0016] In this invention, demethylated lignin undergoes an esterification reaction with maleic anhydride to obtain maleic anhydride-modified lignin containing carboxyl groups and double bonds. This reaction is carried out at a relatively low temperature, which reduces the solubility of the demethylated lignin, thereby allowing grafting to occur on the lignin surface. Acetic acid is used as the reaction solvent and also acts as a catalyst. Next, using chromium 3,5-diisopropylsalicylate as a catalyst, the carboxyl groups of the maleic anhydride-modified lignin undergo a ring-opening reaction with the epoxy groups of 2,3-epoxypropyltrimethylammonium chloride, introducing a quaternary ammonium salt structure onto the lignin. Then, using azobisisobutyronitrile as a catalyst, the double bonds of 2-hydroxy-4-propenoxybenzophenone undergo free radical copolymerization with the double bonds on the maleic anhydride-modified lignin, introducing a benzophenone structure onto the lignin, thereby obtaining the modified lignin. Finally, because Zn2+ combines with OH- at a high concentration to form Zn(OH)42- growth units, and the modified lignin contains a positively charged quaternary ammonium salt structure, it electrostatically adsorbs Zn(OH)42-, causing precipitation and accumulation to form zinc oxide particles. Adjusting the pH to 7.8-8.5 further stabilizes the zinc oxide particles, resulting in a modified lignin-zinc oxide complex. The reason for using demethylated lignin in this invention is that it contains more phenolic hydroxyl groups. After graft modification, residual phenolic hydroxyl groups can form hydrogen bonds with polyurethane, which helps improve the mechanical properties of polyurethane, especially significantly enhancing its toughness.

[0017] Furthermore, the method for preparing the modified cerium dioxide is as follows: (1) Add vinyltriethoxysilane to a 75wt% aqueous ethanol solution and add acetic acid to adjust the pH to 4.5-6. Continue stirring and mixing for 10-30 min to obtain a silane hydrolysate; disperse cerium dioxide in anhydrous ethanol to obtain a 50wt% cerium dioxide dispersion. (2) Heat the cerium dioxide dispersion to 50~60℃ and slowly add silane hydrolysate. After the addition is complete, continue stirring for 2~6 hours. After filtration, washing and drying, the modified cerium dioxide is obtained.

[0018] Furthermore, the mass ratio of the vinyltriethoxysilane and the aqueous ethanol solution is (0.05~0.1):2.

[0019] Furthermore, the mass ratio of cerium dioxide to vinyltriethoxysilane is 1:(0.05~0.1).

[0020] In this invention, cerium dioxide is modified with vinyltriethoxysilane to obtain modified cerium dioxide containing double bonds.

[0021] Furthermore, in step one, the process parameters of the twin-screw extruder are as follows: the twin-screw extruder has six sections, the temperature of each section is 180~210℃, and the screw speed is 250~350r / min.

[0022] Furthermore, in steps two and three, the parameters for thermosetting are: thermosetting temperature of 70~80℃ and thermosetting time of 5~10min.

[0023] Furthermore, in step three, the parameters for photocuring are: photocuring with 365nm ultraviolet light, ultraviolet light intensity of 40~50mW / cm2, and photocuring time of 30~40s.

[0024] Furthermore, the spraying parameters of the self-cleaning coating are as follows: spraying with an air spray gun, spraying air pressure of 0.4~0.7MPa, spraying angle perpendicular to the surface to be sprayed, spraying distance of 15~20cm, and spray width of 10~15cm.

[0025] Furthermore, the relevant parameters for the laser perforation are: aperture diameter of 0.5mm ± 0.01mm and aperture spacing of 7mm.

[0026] Compared with the prior art, the beneficial effects achieved by the present invention are: (1) In this invention, thermoplastic polyurethane elastomer is used as the main raw material for the base weather-resistant layer. The drag-reducing film processed with it has good strength, wear resistance and toughness; however, its weather resistance is poor and it is prone to ultraviolet degradation and thermo-oxidative degradation, which leads to a rapid decline in its performance. Based on this, this invention is designed to improve its UV resistance. Considering that lignin has excellent natural UV resistance and also contains a large number of phenolic hydroxyl groups that can form hydrogen bonds with thermoplastic polyurethane elastomer, it also has a beneficial effect on the mechanical properties of polyurethane. In this invention, a modified lignin-zinc oxide composite is prepared by modifying lignin. The modified lignin-zinc oxide composite contains benzophenone structure and zinc oxide particles. The benzophenone structure and zinc oxide particles can further enhance the UV resistance of lignin, thereby making the prepared base weather-resistant layer have better UV resistance. In this invention, cerium dioxide is further modified to obtain modified cerium dioxide containing double bonds, which can synergistically improve the UV resistance of thermoplastic polyurethane elastomers by modifying the lignin-zinc oxide composite.

[0027] (2) A large number of phenolic hydroxyl groups and flexible side chains obtained by copolymerization remain on the modified lignin-zinc oxide particles. The phenolic hydroxyl groups help to form hydrogen bonds with the thermoplastic polyurethane elasticity, thereby improving the mechanical properties of the substrate weather-resistant layer; the flexible side chains can also improve the toughness of the substrate weather-resistant layer.

[0028] (3) In addition, modified lignin-zinc oxide particles and modified cerium dioxide can also be used as reinforcing fillers to synergistically enhance the mechanical properties of thermoplastic polyurethane elasticity through particle toughening.

[0029] (4) In this invention, vinyl MQ resin is further added. Under the action of dicumyl peroxide, vinyl MQ resin, modified lignin-zinc oxide composite and modified cerium dioxide can cross-link, so that the prepared substrate weather-resistant layer has a denser network structure, which can further enhance the mechanical properties of polyurethane and achieve the thermo-oxidative resistance of thermoplastic polyurethane elastomer.

[0030] (5) In this invention, polyurethane acrylate UV-curable resin is selected as the drag-reducing functional layer material. The polyurethane acrylate UV-curable resin and the substrate weather-resistant layer have good compatibility, which can ensure the bonding force between the substrate weather-resistant layer and the drag-reducing functional layer. The solution adopts a heat-light dual curing method to ensure that the formed small rib microstructure is more stable.

[0031] (6) The self-cleaning coating can reduce the frequency of subsequent manual maintenance and reduce aviation operating costs.

[0032] In summary, the present invention, through the synergistic effect of modified lignin-zinc oxide, modified cerium dioxide, and vinyl MQ resin, comprehensively enhances the weather resistance of thermoplastic polyurethane elasticity and improves its mechanical properties, resulting in a drag-reducing membrane with superior overall performance. Detailed Implementation

[0033] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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] It should be noted that the following quantities are by weight, and there are no special restrictions on the suppliers of all raw materials involved in this invention. Exemplary examples include: In the following examples, the thermoplastic polyurethane elastomer, product number TPU1460A, was purchased from Dongguan Zhangmutou Hengrun Plastic Raw Materials Co., Ltd. Thermosetting acrylic resin adhesive, model FX-9238, with a viscosity of 4000~7000 mPa·s / 25℃, was purchased from Nantong Fangxin Resin Co., Ltd. The polyurethane acrylate UV-curable resin, model U-CURE 9501, with a viscosity of 10000~20000mPa·s / 60℃, was purchased from Kunshan Castel Polymer Materials Co., Ltd. Self-cleaning paint, model Ultradry SC500, purchased from Baylor Chemical Company; Vinyl MQ silicone resin, model CX-355-2, with a viscosity of 850 mm² / s and a vinyl content of 1.36~1.38%, was purchased from Guangdong Chenxi New Material Technology Co., Ltd. 2-Hydroxy-4-propenoxybenzophenone, 99% purity, Shanghai Dingmiao Chemical Technology Co., Ltd. Chromium 3,5-diisopropylsalicylate, purity ≥98%, purchased from Xi'an Lanhao Additives Factory; Antioxidant, model number Antioxidant 1076; 2,3-epoxypropyltrimethylammonium chloride, purity 99%; zinc acetate dihydrate, purity 99%; alkali lignin, product number: 370959; vinyltriethoxysilane, purity 98%; n-dodecyl mercaptan, purity ≥98%; purchased from Merck Reagent Co., Ltd.; each part by weight is 100g.

[0035] Preparatory steps: Demethylated lignin was prepared by the method disclosed in CN107177026A. The preparation method is as follows: alkali lignin was added to an aqueous solution of sodium sulfide and stirred to fully dissolve the lignin. Then, the temperature was raised to the reaction temperature of 100℃, sulfur, n-dodecyl mercaptan and sodium borohydride were added, and the reaction was kept at the temperature for 3 hours. After the reaction was completed, water was added to dilute the solution and the pH value was adjusted to 2. The solution was centrifuged and separated to obtain demethylated lignin. The mass ratio of lignin, sodium sulfide, sulfur, n-dodecyl mercaptan, and sodium borohydride is 50:9:5:40:2.

[0036] Example 1: Preparation process of an impact-resistant and burst-resistant composite drag-reducing membrane for aerospace applications: Step 1: Preparing the weather-resistant layer of the substrate: 1. Preparation of modified lignin-zinc oxide complex: (1) Under nitrogen protection, 10 parts of demethylated lignin and 3 parts of maleic anhydride were added to 60 parts of acetic acid, and the mixture was stirred at 35°C for 4 hours. After the reaction was completed, maleic anhydride-modified lignin was obtained by vacuum distillation; (2) Under nitrogen protection, 10 parts of maleic anhydride-modified lignin, 3 parts of 2,3-epoxypropyltrimethylammonium chloride, and 0.2 parts of 3,5-diisopropylsalicylic acid chromium were added to 30 parts of deionized water, and the mixture was stirred and heated to 75°C for 4 hours. Then, 2 parts of 2-hydroxy-4-propenoxybenzophenone and 0.2 parts of azobis(2-hydroxy-4-propenoxybenzophenone) were added to the mixture. Isobutyronitrile was kept warm and stirred for 2 hours to stop the reaction. After purification by dialysis and freeze-drying, modified lignin was obtained. (3) Under nitrogen protection, 10 parts of zinc acetate dihydrate were added to 50 parts of deionized water and stirred to obtain zinc acetate aqueous solution. 10 parts of modified lignin were added to 50 parts of 5wt% sodium hydroxide aqueous solution and stirred to obtain modified lignin solution. Zinc acetate aqueous solution was added to modified lignin solution, stirred and heated to 85℃, kept warm for 4 hours to stop the reaction. The pH of the system was adjusted to 8. After aging, centrifugation, washing and drying, modified lignin-zinc oxide complex was obtained. 2. Preparation of modified cerium dioxide: (1) Add 0.6 parts of vinyltriethoxysilane to 16 parts of 75wt% aqueous ethanol solution, and add acetic acid to adjust the pH to 5. Continue stirring and mixing for 20 min to obtain silane hydrolysate; disperse 8 parts of cerium dioxide in anhydrous ethanol to obtain 50wt% cerium dioxide dispersion; (2) Heat the cerium dioxide dispersion to 55℃ and slowly add silane hydrolysate dropwise. After the addition is complete, continue stirring for 4 h. After filtration, washing, and drying, obtain modified cerium dioxide; 3. Add 50 parts of thermoplastic polyurethane elastomer, 4.5 parts of vinyl MQ resin, 7.5 parts of modified lignin-zinc oxide composite, 6 parts of modified cerium dioxide, 3 parts of color masterbatch, 0.75 parts of antioxidant, and 0.12 parts of dicumyl peroxide into a mixer, stir and mix evenly, and then extrude the mixture through a twin-screw extruder. The twin-screw extruder is divided into 6 sections, and the temperature of each section is controlled at 200±5℃. The screw speed is 300r / min to obtain a 100μm thick weather-resistant base layer. Step 2: Apply thermosetting acrylic resin adhesive to one side of the weather-resistant base layer and heat-cur it at 75°C for 8 minutes to obtain a 50μm thick adhesive anti-detachment layer; then attach a PET release protective film to the adhesive anti-detachment layer to obtain a release protective layer. Step 3: Apply polyurethane acrylate UV-curable resin to the other side of the substrate weather-resistant layer, heat cure at 75°C for 8 minutes, and then perform UV curing treatment with 365nm UV light for 35 seconds using a mold roller with a UV light intensity of 45mW / cm2 to form a small rib microstructure with a height of 50μm, thus obtaining a drag-reducing functional layer. Step 4: Using an air spray gun, spray the self-cleaning coating onto the surface of the drag-reducing functional layer at a spray pressure of 0.6MPa, a spray distance of 20cm, and a spray width of 15cm, perpendicular to the surface of the drag-reducing functional layer. Dry the coating at 50℃ for 30 minutes to obtain a 20μm thick self-cleaning coating. Then, perform laser perforation with a hole diameter of 0.5mm±0.01mm and a hole spacing of 7mm. Laser cut the coating into the required shape and size to obtain an aerospace-grade impact-resistant and burst-resistant composite drag-reducing membrane.

[0037] Example 2: Preparation process of an aerospace impact-resistant and burst-resistant composite drag-reducing membrane: Step 1: Preparing the weather-resistant layer of the substrate: 1. Preparation of modified lignin-zinc oxide complex: (1) Under nitrogen protection, 10 parts of demethylated lignin and 3 parts of maleic anhydride were added to 60 parts of acetic acid, and the mixture was stirred at 35°C for 4 hours. After the reaction was completed, maleic anhydride-modified lignin was obtained by vacuum distillation; (2) Under nitrogen protection, 10 parts of maleic anhydride-modified lignin, 3 parts of 2,3-epoxypropyltrimethylammonium chloride, and 0.2 parts of 3,5-diisopropylsalicylic acid chromium were added to 30 parts of deionized water, and the mixture was stirred and heated to 75°C for 4 hours. Then, 2 parts of 2-hydroxy-4-propenoxybenzophenone and 0.2 parts of azobis(2-hydroxy-4-propenoxybenzophenone) were added to the mixture. Isobutyronitrile was kept warm and stirred for 2 hours to stop the reaction. After purification by dialysis and freeze-drying, modified lignin was obtained. (3) Under nitrogen protection, 10 parts of zinc acetate dihydrate were added to 50 parts of deionized water and stirred to obtain zinc acetate aqueous solution. 10 parts of modified lignin were added to 50 parts of 5wt% sodium hydroxide aqueous solution and stirred to obtain modified lignin solution. Zinc acetate aqueous solution was added to modified lignin solution, stirred and heated to 85℃, kept warm for 4 hours to stop the reaction. The pH of the system was adjusted to 8. After aging, centrifugation, washing and drying, modified lignin-zinc oxide complex was obtained. 2. Preparation of modified cerium dioxide: (1) Add 0.6 parts of vinyltriethoxysilane to 16 parts of 75wt% aqueous ethanol solution, and add acetic acid to adjust the pH to 5. Continue stirring and mixing for 20 min to obtain silane hydrolysate; disperse 8 parts of cerium dioxide in anhydrous ethanol to obtain 50wt% cerium dioxide dispersion; (2) Heat the cerium dioxide dispersion to 55℃ and slowly add silane hydrolysate dropwise. After the addition is complete, continue stirring for 4 h. After filtration, washing, and drying, obtain modified cerium dioxide; 3. Add 50 parts of thermoplastic polyurethane elastomer, 3 parts of vinyl MQ resin, 5 parts of modified lignin-zinc oxide composite, 4 parts of modified cerium dioxide, 3 parts of color masterbatch, 0.75 parts of antioxidant, and 0.12 parts of dicumyl peroxide into a mixer, stir and mix evenly, and then extrude the mixture through a twin-screw extruder. The twin-screw extruder is divided into 6 sections, and the temperature of each section is controlled at 200±5℃. The screw speed is 300r / min to obtain a 100μm thick weather-resistant base layer. Step 2: Apply thermosetting acrylic resin adhesive to one side of the weather-resistant base layer and heat-cur it at 75°C for 8 minutes to obtain a 50μm thick adhesive anti-detachment layer; then attach a PET release protective film to the adhesive anti-detachment layer to obtain a release protective layer. Step 3: Apply polyurethane acrylate UV-curable resin to the other side of the substrate weather-resistant layer, heat cure at 75°C for 8 minutes, and then perform UV curing treatment with 365nm UV light for 35 seconds using a mold roller with a UV light intensity of 45mW / cm2 to form a small rib microstructure with a height of 50μm, thus obtaining a drag-reducing functional layer. Step 4: Using an air spray gun, spray the self-cleaning coating onto the surface of the drag-reducing functional layer at a spray pressure of 0.6MPa, a spray distance of 20cm, and a spray width of 15cm, perpendicular to the surface of the drag-reducing functional layer. Dry the coating at 50℃ for 30 minutes to obtain a 20μm thick self-cleaning coating. Then, perform laser perforation with a hole diameter of 0.5mm±0.01mm and a hole spacing of 7mm. Laser cut the coating into the required shape and size to obtain an aerospace-grade impact-resistant and burst-resistant composite drag-reducing membrane.

[0038] Example 3: Preparation process of an impact-resistant and burst-resistant composite drag-reducing membrane for aerospace applications: Step 1: Preparing the weather-resistant layer of the substrate: 1. Preparation of modified lignin-zinc oxide complex: (1) Under nitrogen protection, 10 parts of demethylated lignin and 3 parts of maleic anhydride were added to 60 parts of acetic acid, and the mixture was stirred at 35°C for 4 hours. After the reaction was completed, maleic anhydride-modified lignin was obtained by vacuum distillation; (2) Under nitrogen protection, 10 parts of maleic anhydride-modified lignin, 3 parts of 2,3-epoxypropyltrimethylammonium chloride, and 0.2 parts of 3,5-diisopropylsalicylic acid chromium were added to 30 parts of deionized water, and the mixture was stirred and heated to 75°C for 4 hours. Then, 2 parts of 2-hydroxy-4-propenoxybenzophenone and 0.2 parts of azobis(2-hydroxy-4-propenoxybenzophenone) were added to the mixture. Isobutyronitrile was kept warm and stirred for 2 hours to stop the reaction. After purification by dialysis and freeze-drying, modified lignin was obtained. (3) Under nitrogen protection, 10 parts of zinc acetate dihydrate were added to 50 parts of deionized water and stirred to obtain zinc acetate aqueous solution. 10 parts of modified lignin were added to 50 parts of 5wt% sodium hydroxide aqueous solution and stirred to obtain modified lignin solution. Zinc acetate aqueous solution was added to modified lignin solution, stirred and heated to 85℃, kept warm for 4 hours to stop the reaction. The pH of the system was adjusted to 8. After aging, centrifugation, washing and drying, modified lignin-zinc oxide complex was obtained. 2. Preparation of modified cerium dioxide: (1) Add 0.6 parts of vinyltriethoxysilane to 16 parts of 75wt% aqueous ethanol solution, and add acetic acid to adjust the pH to 5. Continue stirring and mixing for 20 min to obtain silane hydrolysate; disperse 8 parts of cerium dioxide in anhydrous ethanol to obtain 50wt% cerium dioxide dispersion; (2) Heat the cerium dioxide dispersion to 55℃ and slowly add silane hydrolysate dropwise. After the addition is complete, continue stirring for 4 h. After filtration, washing, and drying, obtain modified cerium dioxide; 3. Add 50 parts of thermoplastic polyurethane elastomer, 6 parts of vinyl MQ resin, 10 parts of modified lignin-zinc oxide composite, 8 parts of modified cerium dioxide, 3 parts of color masterbatch, 0.75 parts of antioxidant, and 0.12 parts of dicumyl peroxide into a mixer, stir and mix evenly, and then extrude the mixture through a twin-screw extruder. The twin-screw extruder is divided into 6 sections, and the temperature of each section is controlled at 200±5℃. The screw speed is 300r / min to obtain a 100μm thick weather-resistant base layer. Step 2: Apply thermosetting acrylic resin adhesive to one side of the weather-resistant base layer and heat-cur it at 75°C for 8 minutes to obtain a 50μm thick adhesive anti-detachment layer; then attach a PET release protective film to the adhesive anti-detachment layer to obtain a release protective layer. Step 3: Apply polyurethane acrylate UV-curable resin to the other side of the substrate weather-resistant layer, heat cure at 75°C for 8 minutes, and then perform UV curing treatment with 365nm UV light for 35 seconds using a mold roller with a UV light intensity of 45mW / cm2 to form a small rib microstructure with a height of 50μm, thus obtaining a drag-reducing functional layer. Step 4: Using an air spray gun, spray the self-cleaning coating onto the surface of the drag-reducing functional layer at a spray pressure of 0.6MPa, a spray distance of 20cm, and a spray width of 15cm, perpendicular to the surface of the drag-reducing functional layer. Dry the coating at 50℃ for 30 minutes to obtain a 20μm thick self-cleaning coating. Then, perform laser perforation with a hole diameter of 0.5mm±0.01mm and a hole spacing of 7mm. Laser cut the coating into the required shape and size to obtain an aerospace-grade impact-resistant and burst-resistant composite drag-reducing membrane.

[0039] Comparative Example 1: Comparative Example 1 is based on Example 1, with the following adjustment: alkali lignin was used for modification treatment, while other processes remained unchanged. Specifically: A process for preparing an impact-resistant and burst-resistant composite drag-reducing membrane for aerospace applications: Step 1: Preparing the weather-resistant layer of the substrate: 1. Preparation of modified lignin-zinc oxide complex: (1) Under nitrogen protection, 10 parts of alkali lignin and 3 parts of maleic anhydride were added to 60 parts of acetic acid, and the mixture was stirred at 35°C for 4 hours. After the reaction was completed, maleic anhydride-modified lignin was obtained by vacuum distillation; (2) Under nitrogen protection, 10 parts of maleic anhydride-modified lignin, 3 parts of 2,3-epoxypropyltrimethylammonium chloride, and 0.2 parts of 3,5-diisopropylchromium salicylate were added to 30 parts of deionized water, and the mixture was stirred and heated to 75°C for 4 hours. Then, 2 parts of 2-hydroxy-4-propenoxybenzophenone and 0.2 parts of azobisisobutyric acid were added to the mixture. Nitrile, continue to keep warm and stir for 2 hours, stop the reaction, dialysis and purify, freeze dry to obtain modified lignin; (3) Under nitrogen protection, add 10 parts of zinc acetate dihydrate to 50 parts of deionized water, stir and mix to obtain zinc acetate aqueous solution; add 10 parts of modified lignin to 50 parts of 5wt% sodium hydroxide aqueous solution, stir and mix to obtain modified lignin solution; add zinc acetate aqueous solution to modified lignin solution, stir and heat to 85℃, keep warm for 4 hours, stop the reaction, adjust the pH of the system to 8, age, centrifuge, wash and dry to obtain modified lignin-zinc oxide complex; 2. Preparation of modified cerium dioxide: (1) Add 0.6 parts of vinyltriethoxysilane to 16 parts of 75wt% aqueous ethanol solution, and add acetic acid to adjust the pH to 5. Continue stirring and mixing for 20 min to obtain silane hydrolysate; disperse 8 parts of cerium dioxide in anhydrous ethanol to obtain 50wt% cerium dioxide dispersion; (2) Heat the cerium dioxide dispersion to 55℃ and slowly add silane hydrolysate dropwise. After the addition is complete, continue stirring for 4 h. After filtration, washing, and drying, obtain modified cerium dioxide; 3. Add 50 parts of thermoplastic polyurethane elastomer, 4.5 parts of vinyl MQ resin, 7.5 parts of modified lignin-zinc oxide composite, 6 parts of modified cerium dioxide, 3 parts of color masterbatch, 0.75 parts of antioxidant, and 0.12 parts of dicumyl peroxide into a mixer, stir and mix evenly, and then extrude the mixture through a twin-screw extruder. The twin-screw extruder is divided into 6 sections, and the temperature of each section is controlled at 200±5℃. The screw speed is 300r / min to obtain a 100μm thick weather-resistant base layer. Step 2: Apply thermosetting acrylic resin adhesive to one side of the weather-resistant base layer and heat-cur it at 75°C for 8 minutes to obtain a 50μm thick adhesive anti-detachment layer; then attach a PET release protective film to the adhesive anti-detachment layer to obtain a release protective layer. Step 3: Apply polyurethane acrylate UV-curable resin to the other side of the substrate weather-resistant layer, heat cure at 75°C for 8 minutes, and then perform UV curing treatment with 365nm UV light for 35 seconds using a mold roller with a UV light intensity of 45mW / cm2 to form a small rib microstructure with a height of 50μm, thus obtaining a drag-reducing functional layer. Step 4: Using an air spray gun, spray the self-cleaning coating onto the surface of the drag-reducing functional layer at a spray pressure of 0.6MPa, a spray distance of 20cm, and a spray width of 15cm, perpendicular to the surface of the drag-reducing functional layer. Dry the coating at 50℃ for 30 minutes to obtain a 20μm thick self-cleaning coating. Then, perform laser perforation with a hole diameter of 0.5mm±0.01mm and a hole spacing of 7mm. Laser cut the coating into the required shape and size to obtain an aerospace-grade impact-resistant and burst-resistant composite drag-reducing membrane.

[0040] Comparative Example 2: Comparative Example 2 is based on Example 1, with the following adjustment: no modification treatment is performed on the demethylated lignin, while other processes remain unchanged. Specifically: A process for preparing an impact-resistant and burst-resistant composite drag-reducing membrane for aerospace applications: Step 1: Preparing the weather-resistant layer of the substrate: 1. Preparation of modified cerium dioxide: (1) 0.6 parts of vinyltriethoxysilane were added to 16 parts of 75wt% aqueous ethanol solution, and acetic acid was added to adjust the pH to 5. The mixture was stirred for 20 min to obtain silane hydrolysate. 8 parts of cerium dioxide were dispersed in anhydrous ethanol to obtain 50wt% cerium dioxide dispersion. (2) The cerium dioxide dispersion was heated to 55℃ and silane hydrolysate was slowly added dropwise. After the addition was completed, the mixture was stirred for 4 h. After filtration, washing and drying, modified cerium dioxide was obtained. 2. Add 50 parts of thermoplastic polyurethane elastomer, 4.5 parts of vinyl MQ resin, 7.5 parts of demethylated lignin, 6 parts of modified cerium dioxide, 3 parts of color masterbatch, 0.75 parts of antioxidant, and 0.12 parts of dicumyl peroxide into a mixer and stir until uniform. Then, extrude the mixture through a twin-screw extruder. The twin-screw extruder is divided into 6 sections, with the temperature of each section controlled at 200±5℃ and the screw speed at 300r / min, to obtain a 100μm thick weather-resistant base layer. Step 2: Apply thermosetting acrylic resin adhesive to one side of the weather-resistant base layer and heat-cur it at 75°C for 8 minutes to obtain a 50μm thick adhesive anti-detachment layer; then attach a PET release protective film to the adhesive anti-detachment layer to obtain a release protective layer. Step 3: Apply polyurethane acrylate UV-curable resin to the other side of the substrate weather-resistant layer, heat cure at 75°C for 8 minutes, and then perform UV curing treatment with 365nm UV light for 35 seconds using a mold roller with a UV light intensity of 45mW / cm2 to form a small rib microstructure with a height of 50μm, thus obtaining a drag-reducing functional layer. Step 4: Using an air spray gun, spray the self-cleaning coating onto the surface of the drag-reducing functional layer at a spray pressure of 0.6MPa, a spray distance of 20cm, and a spray width of 15cm, perpendicular to the surface of the drag-reducing functional layer. Dry the coating at 50℃ for 30 minutes to obtain a 20μm thick self-cleaning coating. Then, perform laser perforation with a hole diameter of 0.5mm±0.01mm and a hole spacing of 7mm. Laser cut the coating into the required shape and size to obtain an aerospace-grade impact-resistant and burst-resistant composite drag-reducing membrane.

[0041] Comparative Example 3: Comparative Example 3 is based on Example 1, with the following adjustment: vinyl MQ resin is not added, while other processes remain unchanged. Specifically: A process for preparing an impact-resistant and burst-resistant composite drag-reducing membrane for aerospace applications: Step 1: Preparing the weather-resistant layer of the substrate: 1. Preparation of modified lignin-zinc oxide complex: (1) Under nitrogen protection, 10 parts of demethylated lignin and 3 parts of maleic anhydride were added to 60 parts of acetic acid, and the mixture was stirred at 35°C for 4 hours. After the reaction was completed, maleic anhydride-modified lignin was obtained by vacuum distillation; (2) Under nitrogen protection, 10 parts of maleic anhydride-modified lignin, 3 parts of 2,3-epoxypropyltrimethylammonium chloride, and 0.2 parts of 3,5-diisopropylsalicylic acid chromium were added to 30 parts of deionized water, and the mixture was stirred and heated to 75°C for 4 hours. Then, 2 parts of 2-hydroxy-4-propenoxybenzophenone and 0.2 parts of azobis(2-hydroxy-4-propenoxybenzophenone) were added to the mixture. Isobutyronitrile was kept warm and stirred for 2 hours to stop the reaction. After purification by dialysis and freeze-drying, modified lignin was obtained. (3) Under nitrogen protection, 10 parts of zinc acetate dihydrate were added to 50 parts of deionized water and stirred to obtain zinc acetate aqueous solution. 10 parts of modified lignin were added to 50 parts of 5wt% sodium hydroxide aqueous solution and stirred to obtain modified lignin solution. Zinc acetate aqueous solution was added to modified lignin solution, stirred and heated to 85℃, kept warm for 4 hours to stop the reaction. The pH of the system was adjusted to 8. After aging, centrifugation, washing and drying, modified lignin-zinc oxide complex was obtained. 2. Preparation of modified cerium dioxide: (1) Add 0.6 parts of vinyltriethoxysilane to 16 parts of 75wt% aqueous ethanol solution, and add acetic acid to adjust the pH to 5. Continue stirring and mixing for 20 min to obtain silane hydrolysate; disperse 8 parts of cerium dioxide in anhydrous ethanol to obtain 50wt% cerium dioxide dispersion; (2) Heat the cerium dioxide dispersion to 55℃ and slowly add silane hydrolysate dropwise. After the addition is complete, continue stirring for 4 h. After filtration, washing, and drying, obtain modified cerium dioxide; 3. Add 50 parts of thermoplastic polyurethane elastomer, 7.5 parts of modified lignin-zinc oxide composite, 6 parts of modified cerium dioxide, 3 parts of color masterbatch, 0.75 parts of antioxidant, and 0.12 parts of dicumyl peroxide into a mixer, stir and mix evenly, and then extrude the mixture through a twin-screw extruder. The twin-screw extruder is divided into 6 sections, and the temperature of each section is controlled at 200±5℃. The screw speed is 300r / min to obtain a 100μm thick weather-resistant base layer. Step 2: Apply thermosetting acrylic resin adhesive to one side of the weather-resistant base layer and heat-cur it at 75°C for 8 minutes to obtain a 50μm thick adhesive anti-detachment layer; then attach a PET release protective film to the adhesive anti-detachment layer to obtain a release protective layer. Step 3: Apply polyurethane acrylate UV-curable resin to the other side of the substrate weather-resistant layer, heat cure at 75°C for 8 minutes, and then perform UV curing treatment with 365nm UV light for 35 seconds using a mold roller with a UV light intensity of 45mW / cm2 to form a small rib microstructure with a height of 50μm, thus obtaining a drag-reducing functional layer. Step 4: Using an air spray gun, spray the self-cleaning coating onto the surface of the drag-reducing functional layer at a spray pressure of 0.6MPa, a spray distance of 20cm, and a spray width of 15cm, perpendicular to the surface of the drag-reducing functional layer. Dry the coating at 50℃ for 30 minutes to obtain a 20μm thick self-cleaning coating. Then, perform laser perforation with a hole diameter of 0.5mm±0.01mm and a hole spacing of 7mm. Laser cut the coating into the required shape and size to obtain an aerospace-grade impact-resistant and burst-resistant composite drag-reducing membrane.

[0042] Comparative Example 4: Comparative Example 4 is based on Example 1, with the following adjustment: no cerium dioxide modification, and other processes remaining unchanged. Specifically: A process for preparing an impact-resistant and burst-resistant composite drag-reducing membrane for aerospace applications: Step 1: Preparing the weather-resistant layer of the substrate: 1. Preparation of modified lignin-zinc oxide complex: (1) Under nitrogen protection, 10 parts of demethylated lignin and 3 parts of maleic anhydride were added to 60 parts of acetic acid, and the mixture was stirred at 35°C for 4 hours. After the reaction was completed, maleic anhydride-modified lignin was obtained by vacuum distillation; (2) Under nitrogen protection, 10 parts of maleic anhydride-modified lignin, 3 parts of 2,3-epoxypropyltrimethylammonium chloride, and 0.2 parts of 3,5-diisopropylsalicylic acid chromium were added to 30 parts of deionized water, and the mixture was stirred and heated to 75°C for 4 hours. Then, 2 parts of 2-hydroxy-4-propenoxybenzophenone and 0.2 parts of azobis(2-hydroxy-4-propenoxybenzophenone) were added to the mixture. Isobutyronitrile was kept warm and stirred for 2 hours to stop the reaction. After purification by dialysis and freeze-drying, modified lignin was obtained. (3) Under nitrogen protection, 10 parts of zinc acetate dihydrate were added to 50 parts of deionized water and stirred to obtain zinc acetate aqueous solution. 10 parts of modified lignin were added to 50 parts of 5wt% sodium hydroxide aqueous solution and stirred to obtain modified lignin solution. Zinc acetate aqueous solution was added to modified lignin solution, stirred and heated to 85℃, kept warm for 4 hours to stop the reaction. The pH of the system was adjusted to 8. After aging, centrifugation, washing and drying, modified lignin-zinc oxide complex was obtained. 2. Add 50 parts of thermoplastic polyurethane elastomer, 4.5 parts of vinyl MQ resin, 7.5 parts of modified lignin-zinc oxide composite, 6 parts of cerium dioxide, 3 parts of color masterbatch, 0.75 parts of antioxidant, and 0.12 parts of dicumyl peroxide into a mixer and stir until uniform. Then, extrude the mixture through a twin-screw extruder. The twin-screw extruder is divided into 6 sections, and the temperature of each section is controlled at 200±5℃. The screw speed is 300r / min to obtain a 100μm thick weather-resistant base layer. Step 2: Apply thermosetting acrylic resin adhesive to one side of the weather-resistant base layer and heat-cur it at 75°C for 8 minutes to obtain a 50μm thick adhesive anti-detachment layer; then attach a PET release protective film to the adhesive anti-detachment layer to obtain a release protective layer. Step 3: Apply polyurethane acrylate UV-curable resin to the other side of the substrate weather-resistant layer, heat cure at 75°C for 8 minutes, and then perform UV curing treatment with 365nm UV light for 35 seconds using a mold roller with a UV light intensity of 45mW / cm2 to form a small rib microstructure with a height of 50μm, thus obtaining a drag-reducing functional layer. Step 4: Using an air spray gun, spray the self-cleaning coating onto the surface of the drag-reducing functional layer at a spray pressure of 0.6MPa, a spray distance of 20cm, and a spray width of 15cm, perpendicular to the surface of the drag-reducing functional layer. Dry the coating at 50℃ for 30 minutes to obtain a 20μm thick self-cleaning coating. Then, perform laser perforation with a hole diameter of 0.5mm±0.01mm and a hole spacing of 7mm. Laser cut the coating into the required shape and size to obtain an aerospace-grade impact-resistant and burst-resistant composite drag-reducing membrane.

[0043] Comparative Example 5: Comparative Example 5 is based on Example 1, with the following adjustment: only thermoplastic polyurethane elastomer is used as the raw material for the base weather-resistant layer, while other processes remain unchanged. Specifically: A process for preparing an impact-resistant and burst-resistant composite drag-reducing membrane for aerospace applications: Step 1: Preparation of the base weather-resistant layer: Add 50 parts of thermoplastic polyurethane elastomer, 3 parts of color masterbatch, and 0.75 parts of antioxidant into a mixer, stir and mix evenly, and then extrude the mixture through a twin-screw extruder. The twin-screw extruder is divided into 6 sections, and the temperature of each section is controlled at 200±5℃. The screw speed is 300r / min to obtain a 100μm thick base weather-resistant layer. Step 2: Apply thermosetting acrylic resin adhesive to one side of the weather-resistant base layer and heat-cur it at 75°C for 8 minutes to obtain a 50μm thick adhesive anti-detachment layer; then attach a PET release protective film to the adhesive anti-detachment layer to obtain a release protective layer. Step 3: Apply polyurethane acrylate UV-curable resin to the other side of the substrate weather-resistant layer, heat cure at 75°C for 8 minutes, and then perform UV curing treatment with 365nm UV light for 35 seconds using a mold roller with a UV light intensity of 45mW / cm2 to form a small rib microstructure with a height of 50μm, thus obtaining a drag-reducing functional layer. Step 4: Using an air spray gun, spray the self-cleaning coating onto the surface of the drag-reducing functional layer at a spray pressure of 0.6MPa, a spray distance of 20cm, and a spray width of 15cm, perpendicular to the surface of the drag-reducing functional layer. Dry the coating at 50℃ for 30 minutes to obtain a 20μm thick self-cleaning coating. Then, perform laser perforation with a hole diameter of 0.5mm±0.01mm and a hole spacing of 7mm. Laser cut the coating into the required shape and size to obtain an aerospace-grade impact-resistant and burst-resistant composite drag-reducing membrane.

[0044] Performance testing: The tensile strength, puncture resistance, and UV aging resistance of the aerospace-grade impact-resistant and burst-resistant composite drag-reducing films prepared in Examples 1-3 and Comparative Examples 1-5 were tested, as follows: (1) Tensile performance test: Under the conditions of 23℃ and 50% relative humidity, the tensile performance of the impact-resistant and burst-resistant composite drag-reducing membrane for aviation was tested according to the standard GB / T 1040.1-2018. The tensile rate was 10mm / min and the sample size was 20cm (length) × 2cm (width). (2) Puncture resistance test: Under the conditions of 23℃ and 50% relative humidity, the puncture resistance test of the impact-resistant and burst-resistant composite drag-reducing membrane for aviation was carried out according to the standard GB / T 37841-2019. The puncture needle was made of stainless steel with a diameter of 1mm, a hemispherical tip with a radius of 0.5mm, and a puncture speed of 50mm / min. (3) UV aging performance test: Under the conditions of 23℃ and 50% relative humidity, the aerospace impact-resistant and tear-resistant composite drag-reducing membrane was aged for 360h by irradiation accelerated aging chamber with 200W mercury light source, and then its tensile performance was tested.

[0045] The test results for the above test items are shown in Table 1 below: Table 1

[0046] Results Analysis: As can be seen from the data in Table 1 above, the tensile strength, puncture resistance and UV aging resistance of Examples 1-3 are all better than those of the comparative examples. This indicates that the present invention has prepared an aerospace impact-resistant and tear-resistant composite drag-reducing membrane with excellent mechanical properties and UV aging resistance by synergistic preparation of modified lignin-zinc oxide composite, modified cerium dioxide and vinyl MQ resin.

[0047] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An impact-resistant and burst-resistant composite drag-reducing membrane for aviation, characterized in that: The layers stacked from bottom to top include: release protective layer, adhesive anti-detachment layer, base weather-resistant layer, drag-reducing functional layer, and self-cleaning coating; The adhesive anti-detachment layer is obtained by coating one side of the base weather-resistant layer with a thermosetting acrylic resin adhesive and then heat-curing it. The drag-reducing functional layer is obtained by coating a polyurethane acrylate UV-curable resin onto the other side of the substrate weather-resistant layer and then curing it with heat and light to form a small rib microstructure. The weather-resistant base layer is prepared from the following raw material components in parts by weight: 50 parts thermoplastic polyurethane elastomer, 3-6 parts vinyl MQ resin, 5-10 parts modified lignin-zinc oxide composite, 4-8 parts modified cerium dioxide, 2-4 parts color masterbatch, 0.5-1 part antioxidant, and 0.1-0.15 parts dicumyl peroxide. The self-cleaning coating is obtained by spraying self-cleaning paint onto the surface of the drag-reducing functional layer and then drying it.

2. The aerospace impact-resistant and burst-resistant composite drag-reducing membrane according to claim 1, characterized in that: The preparation method of the modified lignin-zinc oxide complex is as follows: (1) Under nitrogen protection, demethylated lignin and maleic anhydride were added to acetic acid and stirred at 30-40°C for 2-6 hours. After the reaction was stopped, maleic anhydride-modified lignin was obtained by vacuum distillation. (2) Under nitrogen protection, maleic anhydride modified lignin, 2,3-epoxypropyltrimethylammonium chloride and 3,5-diisopropylsalicylic acid chromium were added to deionized water, stirred and heated to 70~80℃, and stirred for 2~6h; then 2-hydroxy-4-propenoxybenzophenone and azobisisobutyronitrile were added, and the mixture was kept warm and stirred for 1~3h. The reaction was then stopped, purified by dialysis, and freeze-dried to obtain modified lignin. (3) Under nitrogen protection, zinc acetate dihydrate was added to deionized water and stirred to obtain zinc acetate aqueous solution; modified lignin was added to 5wt% sodium hydroxide aqueous solution and stirred to obtain modified lignin solution; zinc acetate aqueous solution was added to modified lignin solution, stirred and heated to 80~90℃, kept warm for 2~6h, the reaction was stopped, the pH of the system was adjusted to 7.8~8.5, aged, centrifuged, washed and dried to obtain modified lignin-zinc oxide complex; The preparation of maleic anhydride-modified lignin includes the following raw material components in parts by weight: 5 parts of demethylated lignin, 1-2 parts of maleic anhydride, and 30 parts of acetic acid; The modified lignin preparation comprises the following raw material components in parts by weight: 5 parts maleic anhydride modified lignin, 1-2 parts 2,3-epoxypropyltrimethylammonium chloride, 0.05-0.15 parts chromium 3,5-diisopropylsalicylate, 0.5-1.5 parts 2-hydroxy-4-propenoxybenzophenone, 0.05-0.15 parts azobisisobutyronitrile, and 30 parts deionized water; The modified lignin-zinc oxide composite is prepared by the following raw material components in parts by weight: 4-6 parts of zinc acetate dihydrate, 5 parts of modified lignin, 50 parts of deionized water, and 50 parts of sodium hydroxide aqueous solution.

3. The aerospace impact-resistant and burst-resistant composite drag-reducing membrane according to claim 1, characterized in that: The method for preparing the modified cerium dioxide is as follows: (1) Add vinyltriethoxysilane to a 75wt% aqueous ethanol solution and add acetic acid to adjust the pH to 4.5-6. Continue stirring and mixing for 10-30 min to obtain a silane hydrolysate; disperse cerium dioxide in anhydrous ethanol to obtain a 50wt% cerium dioxide dispersion. (2) Heat the cerium dioxide dispersion to 50~60℃ and slowly add silane hydrolysate. After the addition is complete, continue stirring for 2~6 hours. After filtration, washing and drying, the modified cerium dioxide is obtained. The mass ratio of the vinyltriethoxysilane and the aqueous ethanol solution is (0.05~0.1):2; The mass ratio of cerium dioxide to vinyltriethoxysilane is 1:(0.05~0.1).

4. The preparation process of an aerospace impact-resistant and burst-resistant composite drag-reducing membrane according to any one of claims 1 to 3, characterized in that: Includes the following steps: Step 1: Add thermoplastic polyurethane elastomer, vinyl MQ resin, modified lignin-zinc oxide composite, modified cerium dioxide, color masterbatch, antioxidant, and dicumyl peroxide into a mixer, stir and mix evenly, and then extrude through a twin-screw extruder to obtain the base weather-resistant layer. Step 2: Apply thermosetting acrylic resin adhesive to one side of the weather-resistant base layer, and heat-cure to obtain an adhesive anti-detachment layer; then attach a release protective film to the adhesive anti-detachment layer to obtain a release protective layer. Step 3: Apply polyurethane acrylate UV-curable resin to the other side of the substrate weather-resistant layer, and then heat-cur and mold roller light-cured to form a small rib microstructure to obtain a drag-reducing functional layer. Step 4: Spray the self-cleaning coating onto the surface of the drag-reducing functional layer, and after drying, obtain the self-cleaning coating; then perform laser perforation and laser cutting to obtain the aerospace-grade impact-resistant and burst-resistant composite drag-reducing film.

5. The preparation process of an aerospace impact-resistant and burst-resistant composite drag-reducing membrane according to claim 4, characterized in that: In step one, the process parameters of the twin-screw extruder are as follows: the twin-screw extruder has six sections, the temperature of each section is 180~210℃, and the screw speed is 250~350r / min.

6. The preparation process of an aerospace impact-resistant and burst-resistant composite drag-reducing membrane according to claim 4, characterized in that: In steps two and three, the parameters for heat curing are: heat curing temperature of 70~80℃ and heat curing time of 5~10min.

7. The preparation process of an aerospace impact-resistant and burst-resistant composite drag-reducing membrane according to claim 4, characterized in that: In step three, the parameters for photocuring are: photocuring with 365nm ultraviolet light, and the ultraviolet light intensity is 40~50mW / cm². 2 The photocuring time is 30~40s.

8. The preparation process of an aerospace impact-resistant and burst-resistant composite drag-reducing membrane according to claim 4, characterized in that: The spraying parameters for the self-cleaning coating are as follows: spraying with an air spray gun, spraying air pressure of 0.4~0.7MPa, spraying angle perpendicular to the surface to be sprayed, spraying distance of 15~20cm, and spray width of 10~15cm.

9. The preparation process of an aerospace impact-resistant and burst-resistant composite drag-reducing membrane according to claim 4, characterized in that: The thickness of the weather-resistant base layer is 50~100μm; the thickness of the adhesive anti-detachment layer is 30~50μm; the height of the rib microstructure is 20~50μm; and the thickness of the self-cleaning coating is 10~20μm.

10. The preparation process of an aerospace impact-resistant and burst-resistant composite drag-reducing membrane according to claim 4, characterized in that: The relevant parameters for laser perforation are: aperture diameter of 0.5mm ± 0.01mm and aperture spacing of 7mm.

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