Explosion-proof membrane capable of being quickly shaped and preparation method thereof

Abstract

The invention discloses an explosion-proof membrane capable of being quickly shaped and a preparation method of the explosion-proof membrane. The explosion-proof membrane comprises a base material layer, an energy dissipation layer, a self-healing layer and a self-adhesive layer which are sequentially compounded, the base material layer is a high-transmittance polyester base material with shape memory performance; the energy dissipation layer is located on the outer side of the base material layer and is of a gradient modulus structure. The self-healing layer is located on the outer side of the energy dissipation layer, and the self-healing layer is a low-modulus acrylate polymer matrix; the self-adhesive layer is located on the inner side of the base material layer. According to the method, the site construction period is shortened from the hour level to the minute level, the adaptability to the hyperboloid car window or dome daylighting roof complex special-shaped base is improved, and rapid shaping is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of explosion-proof membranes, and in particular to a rapidly reshapeable explosion-proof membrane and a preparation method thereof. Background Art

[0002] Explosion-proof film is a type of functional safety film primarily used on building doors and windows, vehicles, and precision equipment. Its core function is to enhance the impact resistance of glass and other substrates, prevent shattering and splashing, and slow the energy transfer of explosion shock waves. Existing explosion-proof films are mostly based on polyester and polycarbonate polymer materials, bonded to the substrate through adhesive or thermal bonding. With the growing demand for complex curved glass, heterogeneous material structures, and high-end emergency protection, users are not only concerned with the explosion-proof rating of the film itself, but also have higher requirements for its ease of construction, long-term service stability, and environmental adaptability.

[0003] Currently, commercially available explosion-proof films generally utilize a flat roll structure. On-site construction requires manual scraping and hot air guns, and multiple cuts and splices are required to achieve curved surface adhesion. This presents significant compatibility challenges when working with complex, three-dimensional, and irregularly shaped substrates. Construction efficiency is low, and bubbles, wrinkles, and stress concentration defects are easily generated. Furthermore, existing explosion-proof films primarily rely on a single polymer substrate for fragment retention. While this meets explosion-proof requirements under initial impact, they are susceptible to microcrack propagation, interfacial aging and delamination, and increased optical haze in multiple impact cycles or extreme environments such as high temperature and humidity, leading to a rapid decline in protective performance. Furthermore, traditional self-adhesive layers are often based on a single acrylic or PVB system, which cures slowly and easily leaves residual adhesive residue, making it difficult to achieve both rapid prototyping and subsequent high-strength adhesion. Therefore, existing explosion-proof films face numerous deficiencies in adaptability, reliability, and construction techniques, as they address complex curves, pursue efficient and rapid shaping, and withstand long-term service under multiple impacts. Summary of the Invention

[0004] One purpose of the present invention is to propose a rapidly reshaping explosion-proof film and a preparation method thereof. The on-site construction period of the present invention is shortened from hours to minutes, thereby improving the adaptability to complex and irregular-shaped substrates of hyperbolic windows or dome skylights and achieving rapid shaping.

[0005] A rapidly reshapeable explosion-proof membrane according to an embodiment of the present invention comprises a substrate layer, an energy dissipation layer, a self-healing layer and a self-adhesive layer that are laminated in sequence;

[0006] The substrate layer is a highly transparent polyester substrate with shape memory properties, wherein the highly transparent polyester substrate is doped with a blend of shape memory polyurethane and polyethylene terephthalate, and is reinforced by introducing 1-3% by mass of nano-silica treated with an aminosilane coupling agent and 0.5-2% by mass of carboxyl-functionalized carbon nanotubes;

[0007] The energy dissipation layer is located outside the substrate layer and has a gradient modulus structure. The energy dissipation layer is prepared by ultrasonic-high-speed shear compounding of 5-15% nanocellulose and 85-95% thermoplastic polyurethane.

[0008] The self-healing layer is located outside the energy dissipation layer. The self-healing layer is a low-modulus acrylic polymer matrix. Polyurea formaldehyde shell microcapsules with a mass fraction of 2-8% are uniformly dispersed in the polymer matrix. The core of the microcapsule is an isocyanate-hydroxyl self-crosslinking repair agent. After the film layer is subjected to multiple impacts and microcracks are generated, the microcapsules rupture and release the repair agent to perform low-temperature self-healing.

[0009] The self-adhesive layer is located on the inner side of the substrate layer.

[0010] Optionally, the self-adhesive layer adopts an isocyanate-hydroxyl thermosensitive cross-linking system, specifically including the following raw materials in parts by weight: 80-100 parts of terminal hydroxyl polybutadiene, 20-30 parts of polyether polyol 330N, 25-30 parts of isophorone diisocyanate, 0.01-0.2 parts of dibutyltin dilaurate, 0.1-0.3 parts of dimethylethanolamine, 2-5 parts of silica aerogel, 0.5-2 parts of nano-titanium dioxide, 0.5-1 parts of γ-aminopropyltriethoxysilane coupling agent, and 3-6 parts of microcapsule-type isocyanate-hydroxyl cross-linking accelerator.

[0011] A method for preparing a rapidly reshapeable explosion-proof membrane, wherein the substrate layer is prepared, comprising:

[0012] A polyethylene terephthalate (PET) and shape memory polyurethane (SMPU) blend is provided, wherein the PET mass fraction is 70-85% and the SMPU mass fraction is 15-30%. The PET and SMPU are dried and sequentially fed into a twin-screw extruder, melt-blended at a first stage temperature of 230-240°C and a second stage temperature of 240-250°C to obtain a blended melt.

[0013] The blended melt is extruded through a T-die to form a primary sheet with a thickness of 80–120 μm, and then subjected to biaxial stretching with a longitudinal stretching ratio of 3–3.5 times and a transverse stretching ratio of 3.5–4 times;

[0014] Before stretching, 1-3% by mass of nano-SiO2 with its surface modified by γ-aminopropyltriethoxysilane and 0.5-2% by mass of carboxyl functionalized carbon nanotubes are introduced into the blended melt, wherein the nano-SiO2 particle size is 15-30nm, the carboxyl functionalized carbon nanotube diameter is 5-10nm, and the aspect ratio is ≥100. Before addition, the fillers are pre-emulsified and dispersed in the polyester by a high-speed disperser for 15-20 minutes;

[0015] The composite blend melt containing reinforcing fillers is extruded and cast into a film at 250-260°C. After stretching and shaping, an oriented film material is formed. The oriented film material has a thickness of 75-90 μm. During the stretching process, the temperature of the cooling roller is maintained at 30-40°C to lock the shape memory structure.

[0016] The oriented film material is preheated and subjected to a heat cycle treatment at 65–70°C for 60–120 seconds to activate the soft segment chains in the shape memory polyurethane to form reversible microstructure memory nodes. The segments are then frozen by cooling to 23±2°C to complete the locking of the substrate memory state.

[0017] Optionally, the detection of the substrate layer includes the stretching rate ε m and rebound rate R m :

[0018] ε m =(L1-L0) / L0×100%;

[0019] Wherein, L0 is the initial length, L1 is the length under heating and stretching state;

[0020] R m =(L2-L0) / (L1-L0)×100%;

[0021] Wherein, L2 is the final length after recovery deformation after cooling;

[0022] The substrate layer should satisfy ε m ≥200%, R m ≥85%.

[0023] Optionally, the energy dissipation layer is prepared, including:

[0024] Providing nanocellulose and thermoplastic polyurethane raw materials, wherein the mass fraction of the nanocellulose is 5-15%, and the mass fraction of the thermoplastic polyurethane is 85-95%. The nanocellulose is in the form of a fiber bundle structure with a length of 500-1000 nm and a diameter of 20-50 nm. The nanocellulose is dispersed into a suspension with a concentration of 2-4 wt% by using deionized water.

[0025] The nanocellulose suspension was treated with a high-speed shear emulsification device at room temperature for 10-15 minutes at a shear rate of 8000-12000 rpm to form a nanocellulose dispersion;

[0026] The treated nanocellulose dispersion is added to the molten thermoplastic polyurethane and subjected to ultrasonic-assisted mixing at a temperature of 90-110°C, with an ultrasonic power of 300-500W and an action time of 15-25 minutes to form a nano-reinforced composite slurry;

[0027] The nano-reinforced composite slurry was preformed on a two-roll mill at a roller temperature of 100–120°C and a roller distance of 0.5–1.0 mm to form a primary sheet with a thickness of 80–150 μm.

[0028] The primary sheet is placed in a temperature-controlled hot pressing mold for lamination treatment. The hot pressing temperature is 110-130°C, the hot pressing pressure is 5-8 MPa, and the hot pressing time is 60-120 seconds to form a dense composite film layer with a modulus gradient distribution. The thickness of the dense composite film layer is controlled in the range of 60-80 μm.

[0029] Optionally, the detection of the energy dissipation layer includes the impact energy absorption coefficient η e , defined as the impact energy absorbed per unit area E a The impact energy input per unit area E t The ratio of:

[0030] η e =E a / E t ×100%;

[0031] Among them, E a Indicates the impact energy absorbed by the material sample, E t It represents the total energy transferred to the film layer by external impact;

[0032] The energy dissipation layer should satisfy η e ≥60%, and after repeated impact times n=3, the fragment retention rate P s Should satisfy P s ≥80%.

[0033] Optionally, the self-healing layer is prepared, comprising:

[0034] Providing acrylic acid ester polymer matrix monomers and polyurea formaldehyde shell microcapsule materials, wherein the acrylic acid ester polymer matrix monomers include methyl methacrylate, butyl acrylate and hydroxyethyl acrylate in a mass ratio of 50:30:20;

[0035] The acrylate polymer matrix monomers are mixed and introduced into an initiator system, wherein the initiator system includes 0.5-1.0 wt% of azobisisobutyronitrile, 0.1-0.2 wt% of p-toluenesulfonic acid, and 0.2-0.3 wt% of a stabilizer 2,6-di-tert-butyl-p-cresol, and prepolymerized at 70-75° C. for 60-90 minutes to obtain a low modulus acrylate prepolymer solution;

[0036] Provide polyurea formaldehyde shell microcapsules, the content of which is an isocyanate-hydroxyl self-crosslinking repair agent, the particle size range of the polyurea formaldehyde shell microcapsules is 1-5 μm, the encapsulation efficiency is ≥80%, and the mass fraction of the polyurea formaldehyde shell microcapsules is 2-8%;

[0037] The polyurea formaldehyde shell microcapsules are slowly dispersed in the low modulus acrylate prepolymer solution by mechanical stirring at a speed of 200–400 rpm for 20–30 minutes to form a uniformly dispersed composite coating solution;

[0038] The composite coating liquid is applied to the outer surface of the energy dissipation layer by wire rod coating. The coating thickness is controlled within the range of 10-20 μm. The self-healing layer is formed by hot air drying at a temperature of 60-65°C for 30-60 minutes.

[0039] The self-repair rate R of the self-healing layer was detected. h , defined as the strength of recovery after repair σ r The ratio of the initial strength σ0 before damage:

[0040] R h =σ r / σ0×100%;

[0041] Among them, σ0 is the tensile strength of the film in the undamaged state, σ r It is the tensile strength recovered after being left at room temperature for 48 hours after being damaged;

[0042] The self-healing layer should meet R h ≥70%, and under impact stress σ i =15–25MPa, no through cracks are visible to the naked eye after n=3 cycles.

[0043] Optionally, the self-adhesive layer is prepared, comprising:

[0044] 80–100 parts by weight of hydroxyl-terminated polybutadiene, 20–30 parts by weight of polyether polyol 330N, and 25–30 parts by weight of isophorone diisocyanate are prepolymerized at 80–90° C. for 30–60 minutes to form an NCO-terminated prepolymer. During the reaction, the stirring speed is maintained at 300–500 rpm, and the content of the NCO-terminated prepolymer is controlled within the range of 2.5–3.5 wt %.

[0045] Auxiliary components are introduced into the NCO-terminated prepolymer. The auxiliary components include: 0.01-0.2 parts of dibutyltin dilaurate catalyst, 0.1-0.3 parts of dimethylethanolamine, 2-5 parts of silica aerogel, 0.5-2 parts of nano-titanium dioxide, and 0.5-1 parts of γ-aminopropyltriethoxysilane coupling agent. After adding them in sequence, they are mixed at 50-60°C for 20-30 minutes to form a homogeneous adhesive liquid.

[0046] Add the microcapsule isocyanate-hydroxy crosslinking accelerator to the homogeneous adhesive solution, control the stirring speed at 200-300 rpm, and stir for 15-25 minutes to form a self-adhesive adhesive solution;

[0047] The self-adhesive liquid is evenly applied to the back of the substrate layer using a scraping process. The scraping film thickness is controlled at 15-30 μm. After standing and degassing at room temperature for 30 minutes, it is dried under hot air conditions at 60-65°C for 10-20 minutes. The self-adhesive layer structure is completed by covering it with a peelable polyolefin release film.

[0048] Detect the peel strength σ of the self-adhesive layer p and cross-linking rate α p , where the peel strength σ p Defined as the peel force F p Ratio to the glue line width w:

[0049] σ p =F p / w;

[0050] Cross-linking rate α p The NCO functional group consumption rate was calculated by Fourier transform infrared spectroscopy:

[0051] α p =(A0-A t ) / A0×100%;

[0052] Among them, A0 is the initial NCO characteristic peak area, A t is the residual NCO peak area after curing;

[0053] The self-adhesive layer should meet σ p ≥2.0N / cm, α p ≥90%, and the adhesion decreases by no more than 10% after being kept at an ambient temperature of 23±2℃ for 48 hours.

[0054] Optionally, the preparation of the microcapsule-type isocyanate-hydroxy crosslinking accelerator comprises:

[0055] Toluene-2,4-diisocyanate and 1,4-butanediol were mixed in a molar ratio of 1:1 and reacted at 65-68°C for 2.5 hours under nitrogen protection to form an NCO-terminated isocyanate-hydroxyl prepolymer. The reaction chemical equation is:

[0056] OCN–C6H3(CH3)–NCO+HO–(CH2)4–OH→OCN–C6H3(CH3)–NH–COO–(CH2)4

[0057] –O–CO–NH–C6H3(CH3)–NCO;

[0058] The isocyanate-hydroxy prepolymer is added to the oil phase consisting of paraffin oil and Span-80, with the paraffin oil weight ratio being 70-80 parts and the Span-80 weight ratio being 5-8 parts. The mixture is added to a high-speed emulsifier and sheared and emulsified at 9000 rpm for 15 minutes to form a water-in-oil emulsion.

[0059] An aqueous phase is prepared as a shell-forming component. The aqueous phase includes 2-4 parts of urea, 5-8 parts of a 37 wt% formaldehyde aqueous solution, and 0.05-0.1 parts of sodium tripolyphosphate. The aqueous phase is dissolved in deionized water, the pH is adjusted to 3.0-3.5, and the aqueous phase is added dropwise to the water-in-oil emulsion.

[0060] The reaction is maintained at 60-63°C for 3 hours to generate urea-formaldehyde polymer, which is coated on the surface of the isocyanate-hydroxy prepolymer droplets to form a stable capsule wall. The chemical equation of the urea-formaldehyde polymer reaction is:

[0061] H2N–CO–NH2+HCHO→[–NH–CH2–NH–CO–] n +H2O;

[0062] After the reaction, the emulsion system was cooled to room temperature, and the resulting microcapsules were collected by centrifugation and washed three times with deionized water. The microcapsules were then dried at 45°C for 12–24 hours to obtain a microcapsule-type isocyanate-hydroxy crosslinking accelerator with a particle size of 1–3 μm and an encapsulation efficiency of ≥75%.

[0063] Detection of the encapsulation efficiency η of microcapsule-type isocyanate-hydroxy crosslinking accelerator c and release rate R c , where the encapsulation efficiency η c Defined as the effective core mass m in the microcapsule e and the total microcapsule mass m t Ratio: η c =m e / m t ×100; release rate R c It is defined as the mass of cross-linker released per unit time at a specific temperature m r With the initial kernel mass m e Ratio: R c =m r / m e ×100; microcapsules should meet η c ≥75, R c ≥85, and reacts with the –OH groups in the hydroxy-terminated polybutadiene in the self-adhesive layer environment to form a polyurethane cross-linked network. The reaction chemical equation is: R–NCO+R′–OH→R–NH–COO–R′.

[0064] Optionally, the preparation of the silica aerogel includes:

[0065] Tetraethoxysilane was used as the silicon source, and a precursor solution was prepared by mixing TEOS:H2O:EtOH:HCl in a molar ratio of 1:4:6:0.01. Ethanol was used as the solvent and hydrochloric acid was used as the catalyst. The mixture was stirred magnetically at 23±2°C for 30 minutes to produce an acid-catalyzed hydrolysis reaction. The chemical reaction equation is as follows:

[0066] Si(OC2H5)4+4H2O→Si(OH)4+4C2H5OH;

[0067] Under normal temperature conditions, the polycondensation reaction occurs, and the Si(OH)4 molecules undergo a hydroxyl condensation reaction to form Si–O–Si bonds and release water. The polycondensation reaction equation is as follows:

[0068] Si(OH)4+Si(OH)4→(HO)3Si–O–Si(OH)3+H2O;

[0069] The obtained sol was placed in a sealed container for 24-25 hours to form a wet gel structure. The wet gel was subjected to multiple steps of ethanol solvent exchange, using fresh ethanol solution with a volume ratio of 1-1.1:1.5-1.7 to replace the water in the pores. Each exchange lasted 6-6.5 hours and was repeated 3-5 times.

[0070] After the ethanol solvent exchange, the surface modifier trimethylsilyl chloride is introduced into the wet gel. The surface modifier trimethylsilyl chloride reacts with the hydroxyl groups on the silica surface to form a hydrophobic methylsiloxane surface. The reaction equation is as follows:

[0071] Si–OH+(CH3)3SiCl→≡Si–O–Si(CH3)3+HCl;

[0072] The surface-modified wet gel is placed in a supercritical drying device and subjected to CO2 supercritical drying at a temperature of 260–280°C and a pressure of 8–10 MPa for 6–8 hours to remove the solvent in the pores and retain the network structure to obtain a silica aerogel block with a volume shrinkage of <10%.

[0073] The obtained block aerogel was mechanically crushed and sieved to obtain silica aerogel particles with a particle size distribution in the range of 50–200 nm. The specific surface area S of the obtained silica aerogel was measured. a , pore size distribution d p and hydrophobicity θ s ,in:

[0074] The specific surface area of ​​silica aerogel should meet S a ≥500;

[0075] The pore size distribution of silica aerogel should satisfy 5, nm≤dp ≤25, nm;

[0076] The hydrophobicity of silica aerogel should satisfy θ s ≥130°.

[0077] The beneficial effects of the present invention are:

[0078] The present invention forms a shape memory-gradient sandwich structure with excellent reversible deformation ability and high modulus recovery characteristics by doping shape memory polyurethane and carboxyl functionalized carbon nanotubes into a high-transmittance polyester substrate, and combining it with nano-silica modified by surface aminosilane coupling. Combined with the low-temperature heat-vacuum shaping process, the explosion-proof film can achieve rapid three-dimensional bonding and shaping in a single process in the range of 65-75°C, effectively dispersing the initial stress, shortening the on-site construction cycle from hours to minutes, improving the adaptability to complex and irregular substrates of hyperbolic windows or dome skylights, and realizing rapid shaping.

[0079] The present invention introduces a microcapsule-type isocyanate-hydroxyl crosslinking accelerator, and coats the NCO-terminated prepolymer through urea-formaldehyde condensation, thereby endowing the self-healing layer and the self-adhesive layer of the explosion-proof membrane with secondary dynamic crosslinking and micro-damage self-repair functions. Under the action of multiple impacts or cyclic stresses, the microcapsules are ruptured by the force, and the isocyanate is released to cross-link with the matrix hydroxyl group to form a polyurethane network structure, which significantly delays the penetration of microcracks and interface peeling. After 5 equivalent impact cycles, the fragment retention rate can reach more than 80%. At the same time, the adhesion force drops by less than 10% in harsh environments such as high temperature, high humidity, and salt spray, ensuring long-term safety.

[0080] The present invention prepares a gradient energy dissipation layer by compounding nanocellulose and thermoplastic polyurethane, and uniformly embeds silica aerogel particles to construct a graded energy absorption skeleton and a soft-hard phase coupling channel. Under the action of explosion impact, the outer low-modulus self-healing layer of the membrane dissipates the initial strain energy, the middle gradient layer and nano-aerogel effectively absorb high strain rate energy and achieve rapid dispersion, and the inner high-strength substrate cooperates to retain fragments. The overall impact energy absorption coefficient is increased to more than 60%, and the peel strength is increased by more than 15%, effectively preventing the protection level from attenuating after multiple impacts. BRIEF DESCRIPTION OF THE DRAWINGS

[0081] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0082] Figure 1 This is the infrared spectrum of the explosion-proof film sample in Example 3. DETAILED DESCRIPTION

[0083] The present invention will now be described in further detail with reference to the accompanying drawings, which are simplified schematic diagrams that illustrate the basic structure of the present invention in a schematic manner.

[0084] Example 1: A rapidly reshapeable explosion-proof membrane comprising the following layer structure: a substrate layer, an energy dissipation layer, a self-healing layer, and a self-adhesive layer. The substrate is a 50 μm thick PET (polyethylene terephthalate) film that has been corona treated to improve surface adhesion; the energy dissipation layer is approximately 100 μm thick and is primarily composed of a polymer material containing silica aerogel; the self-healing layer is approximately 10 μm thick and contains a microcapsule-type isocyanate-hydroxy crosslinking accelerator; and the self-adhesive layer is approximately 25 μm thick and is used to adhere to the substrate surface. The method for preparing the explosion-proof membrane is as follows:

[0085] Preparation of the microcapsule crosslinking accelerator: 10g of isophorone diisocyanate (IPDI) as the capsule core material was added to 30mL of liquid paraffin as the oil phase. 2.5g of polyvinyl alcohol was dissolved in 500mL of deionized water with stirring as the aqueous emulsifier. The oil phase was slowly added dropwise to the aqueous phase and pre-stirred at room temperature for 10 minutes to form a colostrum. The pH of the system was then adjusted to 3.5. 5g of urea and 15g of a 37% formaldehyde solution were added and emulsified at 55°C with high-speed stirring (600 rpm) for 30 minutes. The mixture was then kept at this temperature for 2 hours to form the urea-formaldehyde resin capsule wall by in-situ polycondensation. After the reaction, the microcapsules were cooled to room temperature, washed repeatedly with ethanol and water, and vacuum-dried to obtain an isocyanate microcapsule crosslinking accelerator with an average particle size of approximately 60μm and a dense capsule wall. When the microcapsule is ruptured by external force, the core isocyanate is released, which can undergo a cross-linking reaction with the hydroxyl-containing polymer to form a polyurethane bond. The chemical reaction equation is: R–NCO+R′–OH→R–NH–CO–O–R′.

[0086] Preparation of the energy dissipation layer: Add 100 parts of polyvinyl butyral resin (PVB) to 500 parts of anhydrous ethanol and heat and stir at 60°C until completely dissolved to obtain a PVB adhesive. Add 20 parts of dried silica aerogel powder (SiO2, nanoporous structure, porosity approximately 90%) to the adhesive and use ultrasonic dispersion for 30 minutes to evenly disperse the aerogel in the adhesive. Then, add an appropriate amount of defoamer to the adhesive and stir evenly. Then, use a doctor blade to coat the aerogel-containing PVB adhesive on one side of the corona-treated PET substrate described above, controlling the wet film thickness to approximately 120 μm. The coated PET film is placed in an 80°C oven and dried for 30 minutes. After the solvent evaporates, a cured film of the energy dissipation layer approximately 100 μm thick is formed on the PET.

[0087] Preparation of the self-healing layer: 100 parts of a commercially available acrylic polyol resin (solid content 60%, hydroxyl value of approximately 120 mgKOH / g) was selected as the film-forming base material, diluted with 100 parts of ethyl acetate, and 20 parts of the IPDI microcapsule crosslinking accelerator prepared in step (1) of Example 1 were added. Mechanical stirring was used to mix at a low speed (100-200 rpm) for 15 minutes to uniformly disperse the microcapsules in the resin solution. During the operation, the temperature was controlled at room temperature (≈25°C) and vigorous stirring was avoided to prevent the microcapsules from rupturing. The self-healing resin containing microcapsules was then coated on the surface of the cured energy dissipation layer to form a wet film layer of approximately 15 μm thick. After natural leveling for 5 minutes, it was dried at 50°C for 60 minutes to obtain a self-healing layer with a thickness of approximately 10 μm. The microcapsule isocyanate dispersed in the self-healing layer ruptured when scratched or squeezed, and quickly reacted with the hydroxyl groups in the resin to crosslink, thereby quickly repairing microcracks and improving the interlayer bonding strength.

[0088] Preparation of self-adhesive layer: A layer of self-adhesive adhesive is applied to the other side of the PET substrate. The adhesive used is an acrylic pressure-sensitive adhesive (water-white and transparent), the main components of which include 2-ethylhexyl acrylate, methyl methacrylate and acrylic acid (mass ratio of about 80:18:2), which is prepared by solution polymerization and has a solid content of 50%. The pressure-sensitive adhesive liquid is evenly applied to the back of the PET film with a thickness of about 30 μm, and then dried at 60 ° C for 10 minutes to form a self-adhesive layer of about 25 μm thick. Finally, a release protective film is applied to the surface of the self-adhesive layer to facilitate storage and removal during use. At this point, the explosion-proof membrane of Example 1 is prepared.

[0089] The explosion-proof film obtained has good flexibility and transparency and can be applied to the surface of substrates such as glass. In actual application, the microcapsules are ruptured by applying pressure through rolling and triggering the rapid cross-linking and curing of isocyanate and resin hydroxyl groups, thereby achieving rapid shaping and performance enhancement. The explosion-proof film obtained in Example 1 was subjected to performance tests, and the results are listed in Table 1. The tensile strength was measured in accordance with the GB / T1040.3-2006 standard (tensile speed 50 mm / min, gauge length 50 mm); the peel strength was tested using the 180° peeling method (the adhesive layer was adhered to the glass and peeled off at a speed of 300 mm / min); the cross-linking rate was measured using the solvent extraction method (the insoluble content was measured after the film was soaked in toluene for 24 hours).

[0090] Table 1 Performance test results of the explosion-proof membrane of Example 1

[0091] Performance indicators Example 1 numerical value Tensile strength (MPa) 80.5 Peel strength (N / cm) 12.1 Cross-linking rate (%) 92.7

[0092] As can be seen from Table 1, the explosion-proof film prepared in this embodiment has a tensile strength of over 80 MPa, a peel strength of 12 N / cm, and a crosslinking rate of over 90%, indicating that the introduction of the microcapsule crosslinking accelerator enables the film to be rapidly crosslinked and strengthened when subjected to stress, and has excellent overall mechanical properties.

[0093] Example 2: A rapidly reshapeable explosion-proof membrane, similar in structure to Example 1, comprises a PET substrate layer, an energy dissipation layer, a self-healing layer, and a self-adhesive layer. The difference lies in the use of different material ratios and process conditions, as described below:

[0094] Preparation of the microcapsule crosslinking accelerator: 8g of hexamethylene diisocyanate (HDI) was dissolved in 20mL of toluene to form an oil phase. 3g of gelatin and 1g of gum arabic were added to 300mL of deionized water as the aqueous phase, and stirred at 40°C until a stable emulsifier solution was formed. The oil phase was slowly dripped into the aqueous phase under high-speed stirring (800 rpm) to emulsify the mixture. The mixture was emulsified at room temperature for 15 minutes to obtain a uniform emulsion. The pH was then adjusted to 5.5, the temperature was raised to 70°C, and 5g of melamine and 15g of a 37% formaldehyde solution were added. The mixture was maintained at 70°C for 1.5 hours, forming a strong melamine-formaldehyde resin capsule wall through in-situ polycondensation. After the reaction was completed, the microcapsules were cooled, recovered by centrifugation, washed three times with distilled water, and dried under vacuum at 50°C for 12 hours to obtain HDI microcapsule powder. The resulting microcapsules had a particle size of approximately 50μm, a thick capsule wall, and a high encapsulation rate. Upon impact, the HDI was released to crosslink and solidify with the matrix.

[0095] Preparation of the energy dissipation layer: 100 parts of thermoplastic polyurethane elastomer (TPU, Shore A hardness 85) were chopped and added to 100 parts of a dimethylformamide / toluene mixed solvent. The mixture was stirred and dissolved in a 70°C water bath for 2 hours to form a TPU sol (solids content approximately 30%). To this sol, 15 parts of surface-modified silica aerogel were added and homogenized at room temperature at high speed for 20 minutes to uniformly disperse the aerogel particles in the TPU sol. The resulting mixed sol was coated onto one side of a 50μm-thick PET substrate (previously corona-treated) using a doctor blade, controlling the wet film thickness to approximately 100μm. The mixture was then dried at 90°C for 20 minutes. After the solvent evaporated, a TPU / aerogel composite layer approximately 80μm thick was formed on the PET substrate, i.e., the energy dissipation layer.

[0096] Preparation of self-healing layer: Take 100 parts of modified polyurethane acrylate resin (with terminal hydroxyl group, Mn≈5000), add 50 parts of propylene glycol methyl ether acetate to dilute, add 15 parts of HDI microcapsules obtained in step (1) of Example 2, and stir evenly at low speed. After that, 0.5 parts of leveling agent are added to eliminate brush marks, and the coating is evenly applied to the surface of the energy dissipation layer obtained in step (2) to form a wet film of about 20 μm thick. After natural leveling, it is dried at 60 ° C for 40 minutes to obtain a self-healing layer of about 12 μm thick. The HDI microcapsules distributed in this layer release HDI when the film is scratched, and react rapidly with the hydroxyl groups in the polyurethane acrylate resin to form a cross-linked polyurethane network, thereby achieving self-repair of cracks.

[0097] Preparation of self-adhesive layer: This step is the same as Example 1. Acrylate pressure-sensitive adhesive with the same formulation is applied to the other surface of the PET substrate to a thickness of about 25 μm. After drying, a self-adhesive layer is formed, which is then covered with a release film for later use.

[0098] The explosion-proof membrane of Example 2 was produced using the above method. Similar to Example 1, after being installed on a glass surface, rolling pressure triggered the rupture of the microcapsules. HDI isocyanate reacted with the hydroxyl groups in the resin to form -NH-CO-O- crosslinks, rapidly curing the membrane. The resulting membrane was tested for performance, and the results are shown in Table 2.

[0099] Table 2 Performance test results of the explosion-proof membrane of Example 2

[0100] Performance indicators Example 2 numerical value Tensile strength (MPa) 75.4 Peel strength (N / cm) 13.0 Cross-linking rate (%) 95.1

[0101] As shown in Table 2, the tensile strength and peel strength of the explosion-proof film of Example 2 both reached high levels, and the crosslinking rate was close to 95%, indicating that microcapsules prepared with different isocyanate core materials can also effectively improve the crosslinking density and mechanical properties of the film.

[0102] Example 3: This example provides another rapidly reshapeable explosion-proof membrane. Its layer structure is basically the same as the above example. The difference is that this example introduces microcapsule crosslinking agents into both the energy dissipation layer and the self-healing layer to further improve the interlayer bonding strength. The specific process is as follows:

[0103] Preparation of the microcapsule crosslinking accelerator: 12g of toluene diisocyanate (TDI) was used as the core material. After preheating to 50°C to completely liquefy it, 1g of Span-80 emulsifier was added and mixed to form an oil phase. The oil phase was slowly dripped into 400mL of aqueous solution containing 2g of polyoxyethylene nonylphenol ether (OP-10) and 0.5g of triethanolamine. Emulsification was carried out at 1000 rpm for 10 minutes to obtain a stable emulsion with an average droplet diameter of approximately 40μm. The pH of the system was adjusted to 4.0, and 6g of urea and 18g of formaldehyde solution were added. The reaction was carried out at 60°C for 2 hours, followed by the addition of 18g of formaldehyde and continued for 1 hour to form a "double-layer" urea-formaldehyde resin capsule wall. The reaction solution was cooled to room temperature, filtered, washed with water, and vacuum-dried to obtain TDI microcapsule powder. The resulting microcapsules had a particle size distribution of 20-80μm and a TDI content of approximately 45%. The capsule wall had a double-layer structure and released TDI monomer upon rupture under pressure or impact.

[0104] Preparation of the energy dissipation layer: A 50μm-thick polycarbonate (PC) film was used as the substrate, and a layer of energy dissipation coating containing microcapsules was uniformly applied to the surface. The preparation method was as follows: 100 parts of polyvinyl butyral resin (PVB) was dissolved in a mixed solvent (ethanol / water = 8:2) by heating to obtain a 30% mass fraction of PVB solution. 10 parts of silica aerogel powder with a particle size of approximately 20nm was added, and ultrasonic stirring was performed for 20 minutes until uniform. Then, 10 parts of the aforementioned TDI microcapsules were added and slowly stirred for 5 minutes before dispersing to prevent excessive breakage of the microcapsules. The resulting coating was applied to the PC substrate with a doctor blade to a thickness of approximately 120μm. The coating was allowed to stand at room temperature for 10 minutes and then dried at 50°C for 1 hour, resulting in an energy dissipation layer approximately 100μm thick. Because this layer contains both PVB hydroxyl groups and microcapsule TDI, when subjected to strong external impact, the TDI released by the microcapsules ruptures and immediately cross-links with surrounding PVB molecules, forming chemical bonds, thereby enhancing the overall strength and toughness of the energy dissipation layer.

[0105] Preparation of the self-healing layer: 100 parts of the same acrylic polyol resin as in Example 1 were used as the base material, 10 parts of the TDI microcapsules obtained in step (1) of Example 3 were added, and after adding an appropriate amount of xylene to dilute to a suitable viscosity, the mixture was stirred and evenly coated on top of the energy dissipation layer obtained in step (2) to a thickness of approximately 15 μm. After standing at room temperature for 10 minutes, it was dried at 50°C for 40 minutes to obtain a self-healing layer of approximately 8 μm thickness. The remaining TDI microcapsules in this layer will release TDI when scratched, cross-linking with the hydroxyl groups of the acrylic resin to form polyurethane, which quickly repairs the scratches. At the same time, some of the TDI microcapsules from the energy dissipation layer rupture under pressure and penetrate into this layer, further promoting the fusion between the layers.

[0106] Preparation of self-adhesive layer: Silicone pressure-sensitive adhesive is used as the self-adhesive material to improve the adhesion performance on the surfaces of different materials. The silicone pressure-sensitive adhesive obtained by copolymerization of n-butyl methacrylate and dimethylsiloxane is coated on the back of the PC substrate with a thickness of about 20 μm. It is placed at room temperature for 2 hours to allow the solvent to evaporate naturally to form a transparent self-adhesive layer, and then covered with release paper for protection.

[0107] The explosion-proof membrane of Example 3 was obtained according to the following steps. Because both the energy dissipation layer and the self-healing layer of this example contain a microcapsule crosslinking agent, the TDI released from the microcapsules can simultaneously trigger a rapid crosslinking reaction in both functional layers when subjected to severe impact or deformation, forming a dense three-dimensional crosslinked network (with the silica aerogel acting as a skeletal reinforcement), significantly improving the membrane's impact resistance and self-healing efficiency. Performance test results for the membrane obtained in Example 3 are shown in Table 3.

[0108] Table 3 Performance test results of the explosion-proof membrane of Example 3

[0109] Performance indicators Example 3 numerical value Tensile strength (MPa) 82.3 Peel strength (N / cm) 11.4 Cross-linking rate (%) 90.5

[0110] As can be seen from Table 3, the explosion-proof membrane of Example 3 maintains a high level in terms of tensile strength and peel strength, and the cross-linking rate is about 90%, indicating that the design of adding microcapsule cross-linking agent in the double layer makes the bond between the membrane layers stronger and can form an effective overall support structure when subjected to stress.

[0111] Comparative Example 1: This comparative example uses a process that is basically the same as that of Example 1 to prepare an explosion-proof membrane, but does not add a microcapsule-type isocyanate-hydroxy crosslinking accelerator to investigate the effect of omitting the key crosslinking step on the performance. The specific steps are: prepare the energy dissipation layer (PVB+aerogel) and the self-healing layer according to the method of Example 1, but do not add any isocyanate microcapsule crosslinking agent to the self-healing layer formula, and only use the same resin base material to directly coat to form an 8-10 μm thick resin layer; the self-adhesive layer is prepared in the same way as in Example 1. Due to the lack of a microcapsule crosslinking agent, the energy dissipation layer and the self-healing layer of the obtained comparative example explosion-proof membrane cannot undergo active crosslinking and curing during use. The performance test results of the comparative example 1 sample are listed in Table 4.

[0112] Table 4 Performance test results of explosion-proof membrane of comparative example 1

[0113] Performance indicators Comparative Example 1 Numerical Value Tensile strength (MPa) Fifty / 50.0 Peel strength (N / cm) 8.3 Cross-linking rate (%) 10.4

[0114] The tensile strength and peel strength test methods in the above table are the same as those in Example 1; the crosslinking rate is measured using the same method.

[0115] As can be seen from Table 4, since no microcapsule cross-linking accelerator was added to Comparative Example 1, the cross-linking rate of the film was only about 10%, which was much lower than the level of more than 90% in Examples 1-3, indicating that the film layer was basically not cross-linked and cured. Its tensile strength dropped to about 50 MPa, and its peel strength dropped to about 8 N / cm, which was significantly lower than the corresponding performance of Example 1. This proves that omitting the isocyanate microcapsule cross-linking agent will lead to a significant decrease in the mechanical properties and self-healing properties of the explosion-proof membrane, making it difficult to meet the requirements of high-performance explosion-proof membranes.

[0116] Combined with the above-mentioned embodiment 3 and the explosion-proof membrane prepared in Example 1, reference Figure 1 , the vertical axis is absorbance, the horizontal axis is wave number (cm -1 ). Curves a (upper curve) and b (lower curve) represent:

[0117] Curve a: a self-adhesive layer sample without adding microcapsule type isocyanate-hydroxy crosslinking accelerator and silica aerogel; Curve b: a sample of the explosion-proof film of the present invention.

[0118] Graphic features: at 1700cm -1 The stretching vibration of amide I (C=O) appears near the 1100cm -1 The Si–O–Si stretching vibration is enhanced near 3400 cm, indicating that the silica aerogel is effectively embedded; -1 The intensity of the nearby –OH vibration decreases, indicating that –OH and –NCO react fully; the absorption peak of curve b is stronger and sharper, indicating that the structure is denser and the cross-linking is more complete.

[0119] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A rapidly reshaping explosion-proof membrane, characterized in that: It includes a base material layer, an energy dissipation layer, a self-healing layer and a self-adhesive layer that are compounded in sequence; The substrate layer is a highly transparent polyester substrate with shape memory properties, wherein the highly transparent polyester substrate is doped with a blend of shape memory polyurethane and polyethylene terephthalate, and is reinforced by introducing 1-3% by mass of nano-silica treated with an aminosilane coupling agent and 0.5-2% by mass of carboxyl-functionalized carbon nanotubes; The energy dissipation layer is located outside the substrate layer and has a gradient modulus structure. The energy dissipation layer is prepared by ultrasonic-high-speed shear compounding of 5-15% nanocellulose and 85-95% thermoplastic polyurethane. The self-healing layer is located outside the energy dissipation layer. The self-healing layer is a low-modulus acrylic polymer matrix. Polyurea formaldehyde shell microcapsules with a mass fraction of 2-8% are uniformly dispersed in the polymer matrix. The core of the microcapsule is an isocyanate-hydroxyl self-crosslinking repair agent. After the film layer is subjected to multiple impacts and microcracks are generated, the microcapsules rupture and release the repair agent to perform low-temperature self-healing. The self-adhesive layer is located on the inner side of the substrate layer.

2. The rapidly reshapeable explosion-proof membrane according to claim 1, characterized in that: The self-adhesive layer adopts an isocyanate-hydroxyl thermosensitive crosslinking system, which specifically includes the following raw materials in parts by weight: 80-100 parts of terminal hydroxyl polybutadiene, 20-30 parts of polyether polyol 330N, 25-30 parts of isophorone diisocyanate, 0.01-0.2 parts of dibutyltin dilaurate, 0.1-0.3 parts of dimethylethanolamine, 2-5 parts of silica aerogel, 0.5-2 parts of nano-titanium dioxide, 0.5-1 parts of γ-aminopropyltriethoxysilane coupling agent, and 3-6 parts of microcapsule-type isocyanate-hydroxyl crosslinking accelerator.

3. A method for preparing a rapidly reshapeable explosion-proof membrane, characterized in that: The substrate layer preparation comprises: A polyethylene terephthalate (PET) and shape memory polyurethane (SMPU) blend is provided, wherein the PET mass fraction is 70-85% and the SMPU mass fraction is 15-30%. The PET and SMPU are dried and sequentially fed into a twin-screw extruder, melt-blended at a first stage temperature of 230-240°C and a second stage temperature of 240-250°C to obtain a blended melt. The blended melt is extruded through a T-die to form a primary sheet with a thickness of 80–120 μm, and then subjected to biaxial stretching with a longitudinal stretching ratio of 3–3.5 times and a transverse stretching ratio of 3.5–4 times; Before stretching, 1-3% by mass of nano-SiO2 with its surface modified by γ-aminopropyltriethoxysilane and 0.5-2% by mass of carboxyl functionalized carbon nanotubes are introduced into the blended melt, wherein the nano-SiO2 particle size is 15-30nm, the carboxyl functionalized carbon nanotube diameter is 5-10nm, and the aspect ratio is ≥100. Before addition, the fillers are pre-emulsified and dispersed in the polyester by a high-speed disperser for 15-20 minutes; The composite blend melt containing reinforcing fillers is extruded and cast into a film at 250-260°C. After stretching and shaping, an oriented film material is formed. The oriented film material has a thickness of 75-90 μm. During the stretching process, the temperature of the cooling roller is maintained at 30-40°C to lock the shape memory structure. The oriented film material is preheated and subjected to a heat cycle treatment at 65–70°C for 60–120 seconds to activate the soft segment chains in the shape memory polyurethane to form reversible microstructure memory nodes. The segments are then frozen by cooling to 23±2°C to complete the locking of the substrate memory state.

4. The method for preparing a rapidly reshapeable explosion-proof membrane according to claim 3, characterized in that: The energy dissipation layer is prepared, comprising: Providing nanocellulose and thermoplastic polyurethane raw materials, wherein the mass fraction of the nanocellulose is 5-15%, and the mass fraction of the thermoplastic polyurethane is 85-95%. The nanocellulose is in the form of a fiber bundle structure with a length of 500-1000 nm and a diameter of 20-50 nm. The nanocellulose is dispersed into a suspension with a concentration of 2-4 wt% by using deionized water. The nanocellulose suspension was treated with a high-speed shear emulsification device at room temperature for 10-15 minutes at a shear rate of 8000-12000 rpm to form a nanocellulose dispersion; The treated nanocellulose dispersion is added to the molten thermoplastic polyurethane and subjected to ultrasonic-assisted mixing at a temperature of 90-110°C, with an ultrasonic power of 300-500W and an action time of 15-25 minutes to form a nano-reinforced composite slurry; The nano-reinforced composite slurry was preformed on a two-roll mill at a roller temperature of 100–120°C and a roller distance of 0.5–1.0 mm to form a primary sheet with a thickness of 80–150 μm. The primary sheet is placed in a temperature-controlled hot pressing mold for lamination treatment. The hot pressing temperature is 110-130°C, the hot pressing pressure is 5-8 MPa, and the hot pressing time is 60-120 seconds to form a dense composite film layer with a modulus gradient distribution. The thickness of the dense composite film layer is controlled in the range of 60-80 μm.

5. The method for preparing a rapidly reshapeable explosion-proof membrane according to claim 3, characterized in that: The self-healing layer preparation comprises: Providing acrylic acid ester polymer matrix monomers and polyurea formaldehyde shell microcapsule materials, wherein the acrylic acid ester polymer matrix monomers include methyl methacrylate, butyl acrylate and hydroxyethyl acrylate in a mass ratio of 50:30:20; The acrylate polymer matrix monomers are mixed and introduced into an initiator system, wherein the initiator system includes 0.5-1.0 wt% of azobisisobutyronitrile, 0.1-0.2 wt% of p-toluenesulfonic acid, and 0.2-0.3 wt% of a stabilizer 2,6-di-tert-butyl-p-cresol, and prepolymerized at 70-75° C. for 60-90 minutes to obtain a low modulus acrylate prepolymer solution; Provide polyurea formaldehyde shell microcapsules, the content of which is an isocyanate-hydroxyl self-crosslinking repair agent, the particle size range of the polyurea formaldehyde shell microcapsules is 1-5 μm, the encapsulation efficiency is ≥80%, and the mass fraction of the polyurea formaldehyde shell microcapsules is 2-8%; The polyurea formaldehyde shell microcapsules are slowly dispersed in the low modulus acrylate prepolymer solution by mechanical stirring at a speed of 200–400 rpm for 20–30 minutes to form a uniformly dispersed composite coating solution; The composite coating liquid is applied to the outer surface of the energy dissipation layer by wire rod coating. The coating thickness is controlled within the range of 10–20 μm. Hot air drying is performed at a temperature of 60–65°C for 30–60 minutes to complete the formation of the self-healing layer.

6. The method for preparing a rapidly reshapeable explosion-proof membrane according to claim 3, characterized in that: The self-adhesive layer is prepared, comprising: 80–100 parts by weight of hydroxyl-terminated polybutadiene, 20–30 parts by weight of polyether polyol 330N, and 25–30 parts by weight of isophorone diisocyanate are prepolymerized at 80–90° C. for 30–60 minutes to form an NCO-terminated prepolymer. During the reaction, the stirring speed is maintained at 300–500 rpm, and the content of the NCO-terminated prepolymer is controlled within the range of 2.5–3.5 wt %. Auxiliary components are introduced into the NCO-terminated prepolymer. The auxiliary components include: 0.01-0.2 parts of dibutyltin dilaurate catalyst, 0.1-0.3 parts of dimethylethanolamine, 2-5 parts of silica aerogel, 0.5-2 parts of nano-titanium dioxide, and 0.5-1 parts of γ-aminopropyltriethoxysilane coupling agent. After adding them in sequence, they are mixed at 50-60°C for 20-30 minutes to form a homogeneous adhesive liquid. Add the microcapsule isocyanate-hydroxy crosslinking accelerator to the homogeneous adhesive solution, control the stirring speed at 200-300 rpm, and stir for 15-25 minutes to form a self-adhesive adhesive solution; The self-adhesive liquid is evenly applied to the back of the substrate layer using a scraping film process. The scraping film thickness is controlled at 15-30 μm. After standing and degassing at room temperature for 30 minutes, it is dried under hot air conditions at 60-65°C for 10-20 minutes and covered with a peelable polyolefin release film to complete the self-adhesive layer structure.

7. The method for preparing a rapidly reshapeable explosion-proof membrane according to claim 3, characterized in that: The preparation of the microcapsule-type isocyanate-hydroxy crosslinking accelerator comprises: Toluene-2,4-diisocyanate and 1,4-butanediol were mixed in a molar ratio of 1:1 and reacted at 65-68°C for 2.5 hours under nitrogen protection to form an NCO-terminated isocyanate-hydroxyl prepolymer. The reaction chemical equation is: OCN–C6H3(CH3)–NCO+HO–(CH2)4–OH→OCN–C6H3(CH3)–NH–COO–(CH2)4–O–CO–NH–C6H2(CH3)–NCO; The isocyanate-hydroxy prepolymer is added to the oil phase consisting of paraffin oil and Span-80, with the paraffin oil weight ratio being 70-80 parts and the Span-80 weight ratio being 5-8 parts. The mixture is added to a high-speed emulsifier and sheared and emulsified at 9000 rpm for 15 minutes to form a water-in-oil emulsion. An aqueous phase is prepared as a shell-forming component. The aqueous phase includes 2-4 parts of urea, 5-8 parts of a 37 wt% formaldehyde aqueous solution, and 0.05-0.1 parts of sodium tripolyphosphate. The aqueous phase is dissolved in deionized water, the pH is adjusted to 3.0-3.5, and the aqueous phase is added dropwise to the water-in-oil emulsion. The reaction is maintained at 60-63°C for 3 hours to generate urea-formaldehyde polymer, which is coated on the surface of the isocyanate-hydroxy prepolymer droplets to form a stable capsule wall. The chemical equation of the urea-formaldehyde polymer reaction is: H2N–CO–NH2+HCHO→[–NH–CH2–NH–CO–] n +H2O; After the reaction, the emulsion system was cooled to room temperature, the obtained microcapsules were collected by centrifugation and washed three times with deionized water, and then dried at 45°C for 12-24 hours to obtain a microcapsule-type isocyanate-hydroxyl crosslinking accelerator with a particle size of 1-3 μm and an encapsulation efficiency of ≥75%.

8. The method for preparing a rapidly reshapeable explosion-proof membrane according to claim 3, characterized in that: The preparation of the silica aerogel comprises: Tetraethoxysilane was used as the silicon source, and a precursor solution was prepared by mixing TEOS:H2O:EtOH:HCl in a molar ratio of 1:4:6:0.

01. Ethanol was used as the solvent and hydrochloric acid was used as the catalyst. The mixture was stirred magnetically at 23±2°C for 30 minutes to produce an acid-catalyzed hydrolysis reaction. The chemical reaction equation is as follows: Si(OC2H5)4+4H2O→Si(OH)4+4C2H5OH; Under normal temperature conditions, the polycondensation reaction occurs, and the Si(OH)4 molecules undergo a hydroxyl condensation reaction to form Si–O–Si bonds and release water. The polycondensation reaction equation is as follows: Si(OH)4+Si(OH)4→(HO)3Si–O–Si(OH)3+H2O; The obtained sol was placed in a sealed container for 24-25 hours to form a wet gel structure. The wet gel was subjected to multiple steps of ethanol solvent exchange, using fresh ethanol solution with a volume ratio of 1-1.1:1.5-1.7 to replace the water in the pores. Each exchange lasted 6-6.5 hours and was repeated 3-5 times. After the ethanol solvent exchange, the surface modifier trimethylsilyl chloride is introduced into the wet gel. The surface modifier trimethylsilyl chloride reacts with the hydroxyl groups on the silica surface to form a hydrophobic methylsiloxane surface. The reaction equation is as follows: Si–OH+(CH3)3SiCl→≡Si–O–Si(CH3)3+HCl; The surface-modified wet gel is placed in a supercritical drying device and subjected to CO2 supercritical drying at a temperature of 260–280°C and a pressure of 8–10 MPa for 6–8 hours to remove the solvent in the pores and retain the network structure to obtain a silica aerogel block with a volume shrinkage of <10%. The obtained block aerogel was mechanically crushed and sieved to obtain silica aerogel particles with a particle size distribution in the range of 50–200 nm. The specific surface area S of the obtained silica aerogel was measured. a , pore size distribution d p and hydrophobicity θ s ,in: The specific surface area of ​​silica aerogel should meet S a ≥500; The pore size distribution of silica aerogel should satisfy 5, nm≤d p ≤25, nm; The hydrophobicity of silica aerogel should satisfy θ s ≥130°.

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