Preparation method of super-hydrophobic coating and shape memory composite base cloth and umbrella

Abstract

The application relates to a preparation method of a super-hydrophobic coating and a shape memory composite base cloth and an umbrella, and belongs to the technical field of coatings, and comprises the following steps: step S1, base cloth pretreatment; step S2, surface activation of the base cloth by using an atmospheric pressure plasma jet device; and step S3, evaporation at normal temperature and pressure: the base cloth is placed in a closed container and is fixed in suspension; fluorine-containing silane surface modifier FAS-17 is injected into the closed container; the closed container is isolated from the outside air at room temperature, saturated vapor pressure is achieved, a colorless, low-surface-energy super-hydrophobic coating is obtained on the surface of the base cloth, and a composite base cloth is formed. According to the scheme, a micro-nano rough groove structure is constructed through plasma deposition based on a physical-chemical synergistic mechanism, chemical hydrophobic modification is realized in combination with a fluorine-containing silane coating, the contact angle of the composite base cloth reaches 152 DEG + 2 DEG, the rolling angle is less than or equal to 2 DEG, and stable super-hydrophobicity is presented.

Description

Technical Field

[0001] This invention belongs to the field of coating technology, and specifically relates to a method for preparing a superhydrophobic coating and a shape memory composite substrate, and an umbrella made therefrom. Background Technology

[0002] Applying a superhydrophobic surface to the umbrella surface prevents water adhesion and provides excellent self-cleaning capabilities, keeping the surface clean. Traditional superhydrophobic surface fabrication techniques include wet chemical etching, electrochemical coating, sol-gel methods, photolithography, sputtering, and phase separation. Wet chemical etching or electrochemical coating requires strong acid / base reagents, generating chemical waste that pollutes the environment. Furthermore, the high process temperatures can damage the fiber structure of substrates such as polyester and nylon. The sol-gel method requires high-temperature heat treatment to form anatase-type hydrophobic structures. Sputtering or photolithography relies on vacuum equipment, making it too costly.

[0003] Atmospheric pressure plasma jet (APPJ) is a non-equilibrium low-temperature (50–90°C) plasma jet generated in an open environment at normal pressure. It forms a highly active particle stream through gas discharge (such as dielectric barrier discharge, nanosecond pulse discharge) to avoid thermal damage and vacuum limitation.

[0004] Chinese patent CN113231273A discloses a method for atmospheric pressure low-temperature plasma deposition of functional coatings, which deposits and sprays functional coatings on the surface of rubber materials, introduces polar groups, and enhances the surface hydrophilicity.

[0005] When applying atmospheric pressure plasma jet technology to base fabrics, it is necessary to consider how to increase the hydrophobicity of the base fabric surface, rather than improving its hydrophilicity, and how to increase the adhesion between the coating and the base fabric. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the purpose of this invention is to provide a method for preparing a superhydrophobic coating.

[0007] Another objective of this invention is to provide a method for preparing shape memory composite substrate.

[0008] Another object of the present invention is to provide umbrellas using the above-described composite base fabric.

[0009] To achieve the above objectives, the present invention adopts the following technical solution.

[0010] A method for preparing a superhydrophobic coating includes the following steps:

[0011] Step S1, base fabric pretreatment:

[0012] The base fabric is cleaned and dried to remove surface contaminants;

[0013] Step S2: Surface activation of the base fabric is performed using an atmospheric pressure plasma jet device.

[0014] An atmospheric pressure plasma jet device includes a cathode, a nozzle, a substrate, a gas system, and a DC power supply. The cathode is made of tungsten metal. The gas system consists of a working gas and a reactant gas, wherein the working gas is argon and the reactant gas is oxygen. A base fabric is placed on the substrate, and the working gas and reactant gas are mixed and injected into the nozzle. A DC power supply is applied to ignite the plasma, and a blue glow discharge appears at the tip of the nozzle. The generated plasma jet scans the entire substrate area at a constant scanning rate to complete the surface activation of the base fabric and deposit a nano-metal oxide layer on the upper surface of the base fabric.

[0015] Step S3, vapor deposition at room temperature and pressure:

[0016] The base fabric is placed in a sealed container and suspended in the air; a fluorinated silane surface modifier FAS-17 is injected into the sealed container; it is left to stand at room temperature to isolate the sealed container from the outside air and reach saturated vapor pressure, thereby obtaining a colorless, low surface energy superhydrophobic coating on the surface of the base fabric, forming a composite base fabric.

[0017] Further, in step S1, the base fabric is ultrasonically cleaned with acetone, isopropanol and deionized water for 4-6 minutes each; then dried in an oven at 80°C for 30 minutes.

[0018] Furthermore, in step S2, the nozzle is made of stainless steel, and a metal rod with a diameter of 1 mm and a length of 175 mm is placed in the center of the stainless steel nozzle with a diameter of 2 mm; the inner diameter of the nozzle is 2 mm, the gap between the cathode and the nozzle is 0.5 mm; the distance between the nozzle and the substrate is fixed at 2 mm; the parameters of the DC power supply are 150 V and 1 A.

[0019] Furthermore, in step S3, the volume ratio of the fluorinated silane surface modifier to the sealed container is 0.012%.

[0020] A method for preparing a shape memory composite substrate includes the following steps:

[0021] Step S1, base fabric weaving:

[0022] The warp yarn is made of polyamide 6 filament; the weft yarn is made of polypropylene monofilament and polyamide 6 low elastic yarn mixed in a ratio of 1:(2-4).

[0023] The base fabric is double-layered jacquard woven, consisting of an outer layer and an inner layer; the outer layer has a plain weave structure with a warp density of 380 to 450 threads per inch and a weft density of 300 to 380 threads per inch; the inner layer has a honeycomb mesh structure with a mesh size of 0.5 to 1.0 mm.

[0024] Step S2, Calendering treatment: The hydrostatic pressure resistance of the base fabric after calendering is ≥350mm water column;

[0025] Step S3, the composite of the hydrophobic coating, includes:

[0026] Step S301, base fabric pretreatment:

[0027] The base fabric is cleaned and dried to remove surface contaminants;

[0028] Step S302: Surface activation of the base fabric is performed using an atmospheric pressure plasma jet device.

[0029] An atmospheric pressure plasma jet device includes a cathode, a nozzle, a substrate, a gas system, and a DC power supply. The cathode is made of tungsten metal. The gas system consists of a working gas and a reactant gas, wherein the working gas is argon and the reactant gas is oxygen. A base fabric is placed on the substrate, and the working gas and reactant gas are mixed and injected into the nozzle. A DC power supply is applied to ignite the plasma, and a blue glow discharge appears at the tip of the nozzle. The generated plasma jet scans the entire substrate area at a constant scanning rate to complete the surface activation of the base fabric and deposit a nano-metal oxide layer on the upper surface of the base fabric.

[0030] Step S303, vapor deposition at room temperature and pressure:

[0031] The base fabric is placed in a sealed container and suspended in the air; a fluorinated silane surface modifier FAS-17 is injected into the sealed container; it is left to stand at room temperature to isolate the sealed container from the outside air and reach saturated vapor pressure, so that a colorless, low surface energy superhydrophobic coating is obtained on the surface of the base fabric, forming a composite base fabric.

[0032] Step S4, hot pressing and shaping:

[0033] After the composite base fabric is preheated to 100~120℃ by infrared, fold lines are pre-pressed out by a CNC folding pressing device with a pressure of 0.5~1.2MPa. Then it is set by high-temperature hot air at a temperature range of 160~180℃ for 30~60s to form permanent fold memory.

[0034] Further, in step S1, polyamide 6 filaments are produced with a specification range of 40 to 80 denier and a single filament count of 48 to 144.

[0035] Polypropylene monofilament specifications: 20 to 60 denier, with 1 monofilament; Polyamide 6 low-elasticity yarn specifications: 30 to 70 denier, with 36 to 96 monofilaments.

[0036] Further, in step S2, during the calendering process, the temperature is 150~170℃; the pressure is 13~17MPa; the speed is 16~20 m / min; and the cooling method is air cooling.

[0037] Further, in step S301, the base fabric is ultrasonically cleaned sequentially with acetone, isopropanol, and deionized water for 4-6 minutes each; then dried in an oven at 80°C for 30 minutes.

[0038] In step S302, the nozzle is made of stainless steel, and a metal rod with a diameter of 1 mm and a length of 175 mm is placed in the center of the stainless steel nozzle with a diameter of 2 mm; the inner diameter of the nozzle is 2 mm, the gap between the cathode and the nozzle is 0.5 mm; the distance between the nozzle and the substrate is fixed at 2 mm; the parameters of the DC power supply are 150 V and 1 A.

[0039] In step S303, the volume ratio of the fluorinated silane surface modifier to the sealed container is 0.012%.

[0040] An umbrella, wherein the base fabric is coated with the superhydrophobic coating described above, or the base fabric is prepared by the preparation method described above.

[0041] This solution has the following beneficial effects:

[0042] Significantly enhanced superhydrophobicity: Based on a physical-chemical synergistic mechanism, micro-nano rough groove structures are constructed through plasma deposition, and chemical hydrophobic modification is achieved by combining a fluorosilane coating, resulting in a composite substrate with a contact angle of 152°±2° and a roll-off angle ≤2°, exhibiting stable superhydrophobicity.

[0043] Shape memory and optimized storage efficiency: The double-layer heterogeneous weaving design of polyamide 6 (PA6) and polypropylene (PP) is adopted. The tension difference between warp and weft yarns is used to form directional crease lines, reducing folding resistance by 35%. At the same time, thermoplastic directional shaping promotes the orderly arrangement of PA6 molecular chains along the crease direction, constructing a permanent cross-linked network, completely eliminating the mechanical dependence of umbrella storage on metal frames. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of an atmospheric pressure plasma jet device;

[0045] Figure 2 This is a SEM image of the base fabric surface;

[0046] Figure 3 It is a dynamic image of water droplets on the surface of the treated base fabric. Detailed Implementation

[0047] The present invention will now be described in further detail with reference to the accompanying drawings.

[0048] A method for preparing a superhydrophobic coating includes the following steps:

[0049] Step S1, base fabric pretreatment.

[0050] The base fabric is ultrasonically cleaned sequentially with acetone, isopropanol, and deionized water for 4-6 minutes each to remove surface oil. The base fabric is then dried to ensure no moisture remains on the surface. The drying method is to dry in an 80℃ oven for 30 minutes.

[0051] Acetone is sonicated for 5 minutes to remove lipophilic oil stains. Isopropanol is sonicated for 5 minutes to dissolve polar residues. Deionized water is sonicated for 5 minutes to rinse away ionic impurities.

[0052] Step S2: The base fabric is surface activated using an atmospheric pressure plasma jet device.

[0053] Figure 1 This is a schematic diagram of an atmospheric pressure plasma jet device; such as Figure 1 As shown, the atmospheric pressure plasma jet device includes a cathode, nozzle, substrate, gas system, and DC power supply. For the structure of the atmospheric pressure plasma jet device, please refer to Li Wenhao et al., “Design, Experiment and Simulation Study of Atmospheric Pressure Wide Radial Air Plasma Jet Device”, Journal of Vacuum Science and Technology, 2019, 39(5): 420-427.

[0054] The cathode is made of tungsten metal doped with 2% thorium (WT20).

[0055] The nozzle is made of stainless steel, and a metal rod with a diameter of 1 mm and a length of 175 mm is placed in the center of the 2 mm diameter stainless steel nozzle to improve electron emission stability and extend electrode life. To avoid uneven discharge, the cathode does not contact the nozzle wall (for example, the gap between the cathode and the inner wall of the nozzle is fixed at 0.5 mm), and the diameter of the metal rod is slightly smaller than the inner diameter of the nozzle. The inner diameter of the nozzle is 2 mm, and the gap between the cathode and the nozzle is 0.5 mm to avoid uneven discharge and ensure the laminar flow characteristics of the jet. The distance between the nozzle and the substrate is fixed at 2 mm, which is the optimal activation distance.

[0056] The gas system consists of a working gas and a reactant gas. The working gas is argon at a flow rate of 15 SLM (standard liters per minute); the reactant gas is oxygen at a flow rate of 40 SCCM (standard cubic centimeters per minute). Oxygen excites and generates reactive oxygen atoms, enhancing surface hydroxylation.

[0057] The parameters of the DC power supply are 150V and 1A;

[0058] The base fabric is placed on the substrate, and the working gas and the reactive gas are mixed and injected into the nozzle. A DC power supply of 150V and 1A is applied to ignite the plasma. A blue glow discharge appears at the tip of the nozzle. The generated plasma jet scans the entire substrate area at a constant scanning rate of 4s / cm², completing the surface activation of the base fabric and depositing a nano-metal oxide layer on the upper surface of the base fabric.

[0059] Step S3: Evaporation deposition at room temperature and pressure.

[0060] For superhydrophobic surfaces, the surface energy should be as low as possible. Reagents with perfluoroalkyl chains can reduce surface energy.

[0061] The base fabric is placed in a sealed container and suspended to avoid contact with the container wall. A fluorosilane surface modifier, FAS-17 (chemical name: 1H,1H,2H,2H-perfluorodecyltriethoxysilane), is injected into the sealed container; the volume ratio of the fluorosilane surface modifier to the sealed container is 0.012% (i.e., 120µL of fluorosilane surface modifier is used for every 1L of sealed container); the concentration of the fluorosilane surfactant is 97%, and it does not directly contact the base fabric; the container is allowed to stand at room temperature for 1 hour to isolate it from the outside air and reach saturated vapor pressure, resulting in a colorless, low surface energy superhydrophobic coating on the base fabric surface, forming a composite base fabric.

[0062] The roll angle test is as follows:

[0063] The roll-off angle is a key parameter characterizing the dynamic hydrophobic properties of a superhydrophobic surface. The roll-off angle test results of the base fabric before and after surface modification are as follows:

[0064] Before modification: The roll angle of the base fabric is about 35°, indicating that it only has basic waterproof performance and droplets are easy to remain on the surface;

[0065] After modification: After atmospheric pressure plasma jet (APPJ) assisted nanofabrication and silanization treatment, the roll-off angle is significantly reduced to about 2°.

[0066] Traditional coatings may exhibit good hydrophobicity (e.g., at 130°), but a roll-off angle exceeding 30° indicates considerable adhesion to water droplets. In this solution, the base fabric undergoes atmospheric pressure plasma jet (APPJ)-assisted nanofabrication and silanization treatment, resulting in a sharp decrease in the roll-off angle. This signifies enhanced hydrophobicity of the base fabric surface. The nanoparticles deposited on the base fabric surface provide a larger surface area, further enhancing surface hydrophobicity and water repellency. The base fabric surface becomes non-wetting, making it virtually impossible for water droplets to adhere to it; instead, water droplets spontaneously roll off, achieving "zero adhesion" anti-wetting properties.

[0067] The atmospheric pressure plasma jet was tested using different gases as follows:

[0068] 1. Using pure argon as the gas system, the treated base fabric exhibits superhydrophilicity, with the lowest surface static contact angle decreasing to 1.5°±0.5°; it reverts to hydrophobicity after 48 hours. Therefore, a reactive gas needs to be added to the working gas.

[0069] 2. Nanoparticles appeared on the surface of the base fabric under conditions of using argon gas containing 0.2% oxygen as the gas system and scanning for more than 30 cycles. Figure 2 This is a SEM image of the base fabric surface; such as Figure 2 As shown, the base fabric has a rough surface with a thin layer of nanoparticles deposited on it.

[0070] The test results for water droplets bouncing on the modified surface are as follows:

[0071] Figure 3 It is a dynamic image of water droplets on the surface of the treated base fabric; Figure 3 The experiment showcased the dynamic behavior of a water droplet on a treated surface, as recorded by a high-speed camera. The droplet was completely repelled by the treated surface within an extremely short time, averaging 13.8–14.6 milliseconds. Furthermore, the test revealed that even after the droplet bounced back and forth between its starting point and the surface more than ten times, the height at the end of the fifth bounce was still 44.4%–51.8% of the height of the first bounce.

[0072] This method combines atmospheric pressure plasma jet deposition and vapor deposition to create a superhydrophobic surface with a rough, bilayer topography. During atmospheric pressure plasma jet deposition, plasma-active tungsten ions first react with free radicals or oxygen in the turbulent air, then deposit on the substrate surface as tungsten metal and incompletely oxidized tungsten oxide. The deposited nanoparticles on the surface are mainly composed of tungsten trioxide, with an inner film containing incompletely oxidized tungsten oxide and metallic tungsten. The nanoparticles are initially deposited in metallic form and then gradually oxidized. Simultaneously, tungsten trioxide prevents further internal oxidation. The deposited nanoparticles form a rough surface and an inner layer with a dual morphology, trapping air to form an air cushion that enhances superhydrophobicity. Vapor deposition self-assembles the hydroxyl bonds on the substrate surface into fluoroalkyl silanes, thus forming metal-siloxane bonds. The coating is functionalized with terminal trifluoromethyl (-CF3) and long-chain -CF2- groups, reducing its surface energy to 15–23 mN / m.

[0073] A method for preparing a shape memory composite substrate includes the following steps:

[0074] Step S1, base fabric weaving:

[0075] The warp yarns are made of polyamide 6 filament (PA6) with a specification range of 40 to 80 denier and 48 to 144 filaments per strand.

[0076] The weft yarn is composed of polypropylene monofilament (PP) and polyamide 6 low-elasticity yarn (PA6) in a ratio of 1:(2-4). Polypropylene monofilament specifications: 20 to 60 denier, with 1 monofilament; polyamide 6 low-elasticity yarn specifications: 30 to 70 denier, with 36 to 96 monofilaments.

[0077] The base fabric is double-layered jacquard woven, consisting of an outer layer and an inner layer;

[0078] The surface layer has a plain weave structure with a warp density of 380 to 450 yarns per inch and a weft density of 300 to 380 yarns per inch. The warp and weft yarns are tightly interwoven to form a high-density waterproof structure.

[0079] The bottom layer has a honeycomb grid structure with a grid aperture of 0.5 to 1.0 mm, which provides deformation space, enhances the flexibility of the base fabric, and guides the folding direction.

[0080] Double-layer jacquard weaving is a textile process that uses two sets of warp and two sets of weft yarns to form a double-layered outer and inner fabric. It is described in Chinese patents with publication numbers CN101046025A, CN110144663A, CN207659593U, and CN106884247A. Chinese patent with publication number CN117005096A discloses a double-layer jacquard weaving process in which the front side of the fabric is the lower structure and the reverse side is the upper structure (flat plain weave). This solution can adopt this solution.

[0081] Step S2, calendering. A high-temperature and high-pressure calendering process is used to obtain a smooth and flat base fabric. The hydrostatic pressure resistance of the calendered base fabric is ≥ 350 mm water column.

[0082] At a temperature of 150~170℃, close to the melting point of polypropylene (165℃) but lower than the softening point of polyamide 6 (180℃), selective melting of polypropylene fibers is achieved while protecting the polyamide 6 fiber skeleton structure from heat damage.

[0083] With a pressure of 13~17MPa, the high pressure drives the molten polypropylene to flow and fill the pores of the fabric, while simultaneously compacting the polyamide 6 fiber layer, significantly improving the density and mechanical strength of the base fabric.

[0084] The vehicle speed is 16~20 meters / minute to ensure uniform heat transfer (dwell time ≈30s) and avoid local overmelting or insufficient curing.

[0085] The cooling method is air cooling, which rapidly solidifies the molten structure, inhibits the growth of polypropylene crystallinity, and preserves the shape memory response potential of the base fabric.

[0086] Calendering process employs a three-step locking mechanism of PP melting-penetration-rapid cooling and setting. Melting: Polypropylene melts at a critical temperature; Penetration: Molten polypropylene penetrates into the fiber gaps under pressure; Rapid cooling and setting: Air cooling rapidly solidifies to form physical cross-linking points, locking the pre-set structure.

[0087] Step S3, composite of hydrophobic coating.

[0088] Step S301, base fabric pretreatment.

[0089] The base fabric is ultrasonically cleaned sequentially with acetone, isopropanol, and deionized water for 4-6 minutes each to remove surface oil. The base fabric is then dried to ensure no moisture remains on the surface. The drying method is to dry in an 80℃ oven for 30 minutes.

[0090] Step S302: The base fabric is surface activated using an atmospheric pressure plasma jet device.

[0091] The cathode is made of tungsten metal doped with 2% thorium (WT20).

[0092] The nozzle is made of stainless steel, and a metal rod with a diameter of 1 mm and a length of 175 mm is placed in the center of a 2 mm diameter stainless steel nozzle to improve electron emission stability and extend electrode life. To avoid uneven discharge, the cathode does not contact the nozzle wall (for example, the gap between the cathode and the inner wall of the nozzle is fixed at 0.5 mm), and the diameter of the metal rod is slightly smaller than that of the nozzle. The inner diameter of the nozzle is 2 mm, and the gap between the cathode and the nozzle is 0.5 mm to avoid uneven discharge and ensure the laminar flow characteristics of the jet. The distance between the nozzle and the substrate is fixed at 2 mm, which is the optimal activation distance.

[0093] The gas system consists of a working gas and a reactant gas. The working gas is argon at a flow rate of 15 SLM (standard liters per minute); the reactant gas is oxygen at a flow rate of 40 SCCM (standard cubic centimeters per minute). Oxygen excites and generates reactive oxygen atoms, enhancing surface hydroxylation.

[0094] The parameters of the DC power supply are 150V and 1A;

[0095] The base fabric is placed on the substrate, and the working gas and the reactive gas are mixed and injected into the nozzle. A DC power supply of 150V and 1A is applied to ignite the plasma. A blue glow discharge appears at the tip of the nozzle. The generated plasma jet scans the entire substrate area at a constant scanning rate of 4s / cm², completing the surface activation of the base fabric and depositing a nano-metal oxide layer on the upper surface of the base fabric.

[0096] Step S303: Evaporation deposition at room temperature and pressure.

[0097] For superhydrophobic surfaces, the surface energy should be as low as possible. Reagents with perfluoroalkyl chains can reduce surface energy.

[0098] The base fabric is placed in a sealed container and suspended to avoid contact with the container wall. A fluorosilane surface modifier, FAS-17 (chemical name: 1H,1H,2H,2H-perfluorodecyltriethoxysilane), is injected into the sealed container; the volume ratio of the fluorosilane surface modifier to the sealed container is 0.012% (i.e., 120µL of fluorosilane surface modifier is used for every 1L of sealed container); the concentration of the fluorosilane surfactant is 97%, and it does not directly contact the base fabric; the container is allowed to stand at room temperature for 1 hour to isolate it from the outside air and reach saturated vapor pressure, resulting in a colorless, low surface energy superhydrophobic coating on the base fabric surface, forming a composite base fabric.

[0099] Step S4, hot pressing and shaping:

[0100] After the composite base fabric is preheated to 100~120℃ by infrared, fold lines are pre-pressed out by a CNC folding pressing device with a pressure of 0.5~1.2MPa. Then it is shaped by high-temperature hot air at a temperature range of 160~180℃ for 30~60s, so that the PA6 molecular chains are oriented and form permanent fold memory.

[0101] The CNC crease pressing device can be the load crease device disclosed in Chinese Patent No. CN113737358A.

[0102] This solution employs a three-step shaping process: infrared preheating softening ensures uniform heating of the composite base fabric, eliminating internal fiber stress and enhancing subsequent plastic deformation capabilities. Pressure mechanical shaping pre-presses precise fold lines onto the base fabric surface, providing a physical guiding path for molecular chain rearrangement. Hot air molecular chain orientation causes the polyamide 6 molecular chains to align orderly along the fold direction, forming a stable orientation structure and achieving irreversible fixation of the fold shape.

[0103] An umbrella, wherein the base fabric is coated with the superhydrophobic coating described above, or the base fabric is prepared by the preparation method described above.

[0104] This composite base fabric combines superhydrophobicity, self-cleaning, and automatic folding storage functions, making it suitable for high-end rain gear.

[0105] It is understood that those skilled in the art can make equivalent substitutions or modifications to the technical solution and inventive concept of the present invention, and all such substitutions or modifications should fall within the protection scope of the appended claims.

Claims

1. A method for preparing a superhydrophobic coating, characterized in that, Includes the following steps: Step S1, base fabric pretreatment: The base fabric is cleaned and dried to remove surface contaminants; Step S2: Surface activation of the base fabric is performed using an atmospheric pressure plasma jet device. An atmospheric pressure plasma jet device includes a cathode, a nozzle, a substrate, a gas system, and a DC power supply; the cathode is made of tungsten metal; the gas system consists of a working gas and a reactant gas, wherein the working gas is argon and the reactant gas is oxygen; a base cloth is placed on the substrate, and the working gas and reactant gas are mixed and injected into the nozzle; A DC power supply is applied to ignite the plasma, and a blue glow discharge appears at the tip of the nozzle. The generated plasma jet scans the entire substrate area at a constant scanning rate, completing the surface activation of the substrate and depositing a nano-metal oxide layer on the upper surface of the substrate. In step S2, the nozzle is made of stainless steel, and a metal rod with a diameter of 1 mm and a length of 175 mm is placed in the center of the stainless steel nozzle with a diameter of 2 mm; the inner diameter of the nozzle is 2 mm, and the gap between the cathode and the nozzle is 0.5 mm; the distance between the nozzle and the substrate is fixed at 2 mm; the parameters of the DC power supply are 150 V and 1 A; the working gas is argon with a flow rate of 15 slm; and the reaction gas is oxygen with a flow rate of 40 slm. Step S3, vapor deposition at room temperature and pressure: The base fabric is placed in a sealed container and suspended in the air; a fluorinated silane surface modifier FAS-17 is injected into the sealed container; it is left to stand at room temperature to isolate the sealed container from the outside air and reach saturated vapor pressure, so that a colorless, low surface energy superhydrophobic coating is obtained on the surface of the base fabric, forming a composite base fabric. In step S3, the volume ratio of the fluorinated silane surface modifier to the sealed container is 0.012%; Based on the physicochemical synergistic mechanism, a micro-nano rough groove structure is constructed by plasma deposition, and chemical hydrophobic modification is achieved by combining it with a fluorosilane coating, so that the contact angle of the composite substrate reaches 152°±2° and the roll-off angle is ≤2°.

2. The method for preparing a superhydrophobic coating according to claim 1, characterized in that, In step S1, the base fabric is ultrasonically cleaned with acetone, isopropanol and deionized water for 4-6 minutes each; then dried in an oven at 80°C for 30 minutes.

3. A method for preparing a shape memory composite substrate, characterized in that, Including the following methods: Step S1, base fabric weaving: The warp yarn is made of polyamide 6 filament; the weft yarn is made of polypropylene monofilament and polyamide 6 low elastic yarn mixed in a ratio of 1:(2-4). The base fabric is double-layered jacquard woven, consisting of an outer layer and an inner layer; the outer layer has a plain weave structure with a warp density of 380 to 450 threads per inch and a weft density of 300 to 380 threads per inch; the inner layer has a honeycomb mesh structure with a mesh size of 0.5 to 1.0 mm. Step S2, Calendering treatment: The hydrostatic pressure resistance of the base fabric after calendering is ≥350mm water column; Step S3, the composite of the hydrophobic coating, includes: Step S301, base fabric pretreatment: The base fabric is cleaned and dried to remove surface contaminants; In step S301, the base fabric is ultrasonically cleaned with acetone, isopropanol, and deionized water for 4-6 minutes each; then dried in an oven at 80°C for 30 minutes. Step S302: Surface activation of the base fabric is performed using an atmospheric pressure plasma jet device. An atmospheric pressure plasma jet device includes a cathode, a nozzle, a substrate, a gas system, and a DC power supply. The cathode is made of tungsten metal. The gas system consists of a working gas and a reactant gas, wherein the working gas is argon and the reactant gas is oxygen. A base fabric is placed on the substrate, and the working gas and reactant gas are mixed and injected into the nozzle. A DC power supply is applied to ignite the plasma, and a blue glow discharge appears at the tip of the nozzle. The generated plasma jet scans the entire substrate area at a constant scanning rate to complete the surface activation of the base fabric and deposit a nano-metal oxide layer on the upper surface of the base fabric. In step S302, the nozzle is made of stainless steel, and a metal rod with a diameter of 1 mm and a length of 175 mm is placed in the center of the stainless steel nozzle with a diameter of 2 mm; the inner diameter of the nozzle is 2 mm, and the gap between the cathode and the nozzle is 0.5 mm; the distance between the nozzle and the substrate is fixed at 2 mm; the parameters of the DC power supply are 150 V and 1 A; the working gas is argon with a flow rate of 15 slm; and the reaction gas is oxygen with a flow rate of 40 slm. Step S303, vapor deposition at room temperature and pressure: The base fabric is placed in a sealed container and suspended in the air; a fluorinated silane surface modifier FAS-17 is injected into the sealed container; it is left to stand at room temperature to isolate the sealed container from the outside air and reach saturated vapor pressure, so that a colorless, low surface energy superhydrophobic coating is obtained on the surface of the base fabric, forming a composite base fabric. In step S303, the volume ratio of the fluorinated silane surface modifier to the sealed container is 0.012%; Based on the physical-chemical synergistic mechanism, micro-nano rough groove structures are constructed by plasma deposition, and chemical hydrophobic modification is achieved by combining fluorosilane coating, so that the contact angle of the composite substrate reaches 152°±2° and the roll-off angle is ≤2°. Step S4, hot pressing and shaping: After the composite base fabric is preheated to 100~120℃ by infrared, fold lines are pre-pressed out by a CNC folding pressing device with a pressure of 0.5~1.2MPa. Then it is set by high-temperature hot air at a temperature range of 160~180℃ for 30~60s to form permanent fold memory.

4. The method for preparing a shape memory composite substrate according to claim 3, characterized in that, Step S1: Polyamide 6 filament, with a specification range of 40 to 80 denier and 48 to 144 filaments; Polypropylene monofilament specifications: 20 to 60 denier, with 1 monofilament; Polyamide 6 low-elasticity yarn specifications: 30 to 70 denier, with 36 to 96 monofilaments.

5. The method for preparing a shape memory composite substrate according to claim 3, characterized in that, Step S2, during calendering, the temperature is 150~170℃; the pressure is 13~17MPa; the speed is 16~20 m / min; and the cooling method is air cooling.

6. An umbrella, characterized in that, The base fabric is coated with the superhydrophobic coating as described in any one of claims 1-2, or the base fabric is prepared by any one of claims 3-5.

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