Infrared stealth type porous silicon heat insulation car cover material and preparation method thereof

Abstract

The invention discloses an infrared stealth type porous silicon heat insulation car cover material and a preparation method thereof. The material is prepared from functional components such as modified porous silicon powder, high-elasticity aliphatic waterborne polyurethane, organic silicon modified acrylic emulsion, nano cellulose, a liquid polybutadiene toughening agent, a silane coupling agent, flaky aluminum powder, infrared absorption pigment and graphene microchips according to a specific proportion. Through a special charging sequence and a dispersing process, a double-layer composite structure with integrated functions is formed in situ in a primary coating and curing process, the bottom layer is a porous silicon heat insulation layer, and the surface layer is an infrared stealth regulation and control layer; according to the structure, the material has extremely low heat conductivity coefficient and infrared emissivity while maintaining excellent flexibility, bending resistance and adhesive force, the dual functions of efficient heat insulation and infrared detection resistance are achieved, and the material is environmentally friendly, simple in process and suitable for large-scale production.

Description

Technical Field

[0001] This invention relates to the field of functional car cover materials technology, specifically to an infrared stealth porous silicon heat insulation car cover material and its preparation method. Background Technology

[0002] With the increasing number of cars on the road, car covers, as an important tool for protecting vehicle paint and providing heat insulation and sun protection, are facing increasingly diverse functional requirements. Traditional car covers mainly provide physical protection, and their materials (such as ordinary PVC and PE) have poor heat insulation properties, leading to a sharp increase in interior temperature in summer. This not only affects driving and riding comfort but also increases air conditioning energy consumption.

[0003] To improve thermal insulation performance, some heat-insulating car covers have appeared on the market, mainly blocking solar heat radiation by adding reflective pigments or using multi-layer composite structures. However, these car covers generally have the following shortcomings: First, they mainly reflect visible light and near-infrared wavelengths, and have limited ability to suppress long-wave infrared radiation (i.e., the thermal radiation of the object itself) in the 8-14μm range. In military or specific security scenarios, detection equipment equipped with long-wave infrared thermal imagers can clearly identify the outline and thermal characteristics of vehicles covered by such car covers, resulting in significant risks to vehicle privacy and security. Second, in order to achieve extremely low thermal conductivity, existing technologies often attempt to introduce high-performance heat-insulating fillers such as porous silicon and aerogel. However, these materials themselves have problems such as high brittleness, easy powdering and cracking, poor adhesion to polymer matrices, and poor weather resistance, making it difficult to use stably in car cover products that require frequent rolling, bending, and exposure to various climatic conditions, and they cannot meet the low emissivity surface characteristics required for infrared stealth.

[0004] Especially for new energy vehicles, their power batteries are prone to thermal runaway due to heat accumulation under high temperatures and direct sunlight, which can lead to vehicle fires. While existing car cover materials can partially block direct sunlight, they lack effective suppression of overall heat diffusion in the battery compartment, making it difficult to provide sufficient safety protection under extreme high-temperature conditions. Therefore, developing a car cover material that combines high-efficiency heat insulation with wide-temperature-range stability is of significant practical importance for improving the safety of new energy vehicles during summer use.

[0005] Therefore, the market urgently needs a car cover material that can comprehensively solve the above problems. An ideal car cover material should simultaneously meet the following requirements: (1) It has excellent heat insulation performance, which can effectively reduce the temperature inside the car; (2) It has infrared stealth function, which can significantly reduce the infrared emissivity in the 8~14μm band and resist thermal imaging detection; (3) It has good flexibility, resistance to repeated bending and adhesion, so as to adapt to the daily use of car covers; (4) It has wide temperature range adaptability and weather resistance, which can ensure stable performance under all climate conditions; (5) The process is compatible with existing production lines and can realize large-scale industrial production.

[0006] There is currently no car cover material solution that can simultaneously achieve high-efficiency heat insulation, infrared stealth, excellent mechanical properties, and good processability. Summary of the Invention

[0007] To address the shortcomings of the existing technology, the present invention aims to provide an infrared stealth porous silicon heat insulation car cover material and its preparation method, thereby solving the problems mentioned in the background art.

[0008] To achieve the above objectives, a specific embodiment of the present invention provides an infrared stealth porous silicon heat insulation car cover material, which, by weight percentage, comprises the following components: 25-35% modified porous silicon powder, 20-28% high-elastic aliphatic waterborne polyurethane, 8-12% organosilicon-modified acrylic emulsion, 1-3% nanocellulose, 2-4% liquid polybutadiene toughening agent, 1-2% silane coupling agent KH560, 2.5-4.0% flake aluminum powder, 1-2% infrared absorbing pigment, 0.2-0.5% graphene microflakes, 0.3-0.8% UV stabilizer, and the balance being defoamer, film-forming aid, and deionized water.

[0009] This application discloses an infrared stealth porous silicon heat insulation car cover material and its preparation method. The material not only has an extremely low thermal conductivity and excellent heat insulation and cooling effect, but also has an extremely low infrared emissivity, which can effectively resist infrared thermal imaging detection. In addition, it has the characteristics of high and low temperature resistance, repeated bending resistance, strong adhesion, and good weather resistance. The process is simple and suitable for large-scale production.

[0010] In addition, the infrared stealth porous silicon heat insulation car cover material and its preparation method proposed in this application may also have the following additional technical features: In one embodiment of this application, the particle size of the flake aluminum powder is 6-12 μm.

[0011] In one embodiment of this application, the infrared absorbing pigment is at least one of copper manganese oxide or iron manganese oxide.

[0012] In one embodiment of this application, the car cover material is a functionally integrated two-layer composite structure, which includes a porous silicon heat insulation layer as the bottom layer and an infrared stealth control layer as the top layer; the porous silicon heat insulation layer and the infrared stealth control layer are integrated and work together, wherein the porous silicon heat insulation layer is used to block heat conduction to reduce the surface temperature; the infrared stealth control layer is used to reduce infrared emissivity and absorb infrared radiation to achieve thermal imaging detection resistance.

[0013] In one embodiment of this application, the dry film thickness of the car cover material is 50-80 μm.

[0014] In one embodiment of this application, the thermal conductivity of the car cover material is ≤0.028 W / (m·K).

[0015] In one embodiment of this application, the infrared emissivity of the car cover material is ≤0.30 in the 8-14μm infrared band.

[0016] In one embodiment of this application, the car cover material has a bending resistance of ≥10,000 cycles and does not crack, peel off, or delaminate after bending.

[0017] In one embodiment of this application, the applicable temperature range of the car cover material is -33℃ to 33℃.

[0018] A method for preparing infrared stealth porous silicon heat-insulating car cover material includes the following steps: (1) The high-elastic aliphatic waterborne polyurethane, the organosilicon-modified acrylic emulsion and a portion of deionized water are mixed and stirred at low speed to form a basic emulsion. (2) Add the modified porous silica powder, the nanocellulose and the silane coupling agent KH560 to the base emulsion obtained in step (1) and disperse at high speed for 30-45 minutes; (3) Add the flake aluminum powder, the infrared absorbing pigment and the graphene microplate to the mixture obtained in step (2) and disperse at a medium speed for 20 minutes; (4) Add the liquid polybutadiene toughening agent, the UV stabilizer, the defoamer, the film-forming aid and the remaining deionized water to the mixture obtained in step (3), and stir for 15 minutes until the mixture is uniform; (5) After filtering the mixed slurry obtained in step (4), it is coated onto the car cover base film, and the dry film thickness is controlled to be 50-80μm. It is then dried and cured at 60-90℃ to obtain the infrared stealth porous silicon heat insulation car cover material.

[0019] (6) The material can significantly reduce the surface and internal temperature of the vehicle body in high temperature environment, reduce the heat accumulation in the battery compartment, thereby effectively suppressing the risk of battery thermal runaway caused by high temperature, and providing additional active safety protection for new energy vehicles.

[0020] The advantages of this invention compared to existing technologies are: (1) Through the design of a double-layer composite structure of “porous silicon heat insulation layer + infrared stealth control layer”, the bottom layer of porous silicon powder and aerogel structure effectively blocks heat conduction, while the surface layer of sheet aluminum powder, infrared absorbing pigment and graphene micro-flakes work together to form a low emissivity surface and absorb residual infrared radiation, so that the infrared emissivity of the material in the 8-14μm band is reduced to below 0.30, which significantly reduces the probability of being detected by infrared thermal imagers.

[0021] (2) A flexible polymer matrix is ​​formed by high-elastic aliphatic waterborne polyurethane and silicone-modified acrylic emulsion, and liquid polybutadiene toughening agent and nanocellulose are added, which greatly improves the brittleness problem caused by the addition of porous silica powder, making the material resistant to more than 10,000 cycles of repeated bending without cracking or falling off, thus meeting the needs of frequent roll-up use of car covers.

[0022] (3) The introduction of organosilicon modified components and UV stabilizers gives the material good high and low temperature resistance (-33℃~33℃) and UV aging resistance, making it suitable for all-weather outdoor use.

[0023] (4) It adopts an aqueous system with low VOC content, making it environmentally friendly. All raw materials used are industrial-grade products, the preparation process is simple, and it is highly compatible with existing car cover coating production lines, making it suitable for large-scale industrial production.

[0024] (5) The material also has the advantages of strong adhesion, stable dry film state and long service life. The heat insulation and cooling range can reach more than 18℃, and the heat insulation performance retention rate after bending is more than 92%.

[0025] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the structure of an infrared stealth porous silicon heat insulation car cover material according to an embodiment of the present invention; Figure 2 This is a process flow diagram of a method for preparing an infrared stealth porous silicon heat insulation car cover material according to an embodiment of the present invention.

[0028] Explanation of reference numerals in the attached figures: 1. Porous silicon heat insulation layer; 2. Infrared stealth control layer. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] like Figures 1 to 2 As shown in the figure, an infrared stealth porous silicon heat-insulating car cover material and its preparation method according to an embodiment of the present invention spontaneously construct a functionally layered composite structure in a single coating system through a specific raw material formulation and matching preparation process. The bottom layer is a heat-insulating layer with modified porous silicon powder as its framework, and the top layer is an infrared stealth control layer with the synergistic effect of sheet-like aluminum powder, infrared-absorbing pigments, and graphene microflakes. This structure is not achieved by physically combining two different materials, but rather by the gradient distribution of functional fillers during the coating and curing process due to differences in the density, surface energy, and interaction forces with the substrate of different components, as well as specific feeding sequences and dispersion processes. This integrated structure avoids interlayer adhesion problems and ensures the integrity and durability of the material.

[0031] The performance of the material of this invention depends on the specific functions and synergistic effects of each component within its proportion range.

[0032] Modified porous silica powder (25-35%): used as a core thermal insulation filler. Porous silica powder possesses a rich nanoscale pore structure, effectively blocking the thermal motion of gas molecules and gas-phase heat conduction, thus imparting an extremely low thermal conductivity to the material. If its dosage is below 25%, the thermal insulation effect is not significant; if it is above 35%, the slurry viscosity becomes too high, making coating difficult, and the flexibility and adhesion of the coating will decrease sharply. "Modification" refers to surface treatment of commercially available porous silica powder (e.g., pretreatment with silane coupling agents) to improve its compatibility and dispersibility with the polymer matrix and prevent agglomeration. This is a crucial prerequisite for ensuring the final mechanical properties of the coating.

[0033] High-elastic aliphatic waterborne polyurethane (20-28%) and silicone-modified acrylic emulsion (8-12%): These two components together form the polymer film-forming matrix of the system. High-elastic aliphatic waterborne polyurethane provides excellent elasticity, low-temperature resistance, and scratch resistance, serving as the primary source of the organic material's flexibility. The silicone-modified acrylic emulsion contributes excellent adhesion, water resistance, and weather resistance, and its silicone segments enhance the surface hydrophobicity of the coating. The combination of these two components, after curing, forms an interpenetrating network structure, achieving a balance between high elasticity, high strength, and high adhesion, providing a robust yet flexible supporting framework for the functional filler.

[0034] Nanocellulose (1-3%): As a bio-based nano-reinforcing material, it has three main functions: First, as a thickener and rheology modifier, it prevents the sedimentation of heavy fillers such as porous silica powder during slurry storage and construction, maintaining the uniformity and stability of the system; second, its nanofiber network can penetrate into the polymer matrix, playing a reinforcing role similar to "steel bars," improving the tensile strength and modulus of the coating; third, in synergy with porous silica powder, it further increases the tortuosity of the heat transfer path, enhancing the thermal insulation effect.

[0035] Liquid polybutadiene toughening agent (2-4%): As a reactive toughening agent, it can physically entangle or slightly crosslink with the polymer matrix, effectively absorbing and dissipating external stress (such as energy generated by bending and impact) without significantly reducing the glass transition temperature. It is a key component in solving the problem of easy cracking of coatings with high filler content, and directly contributes to the material's resistance to more than 10,000 cycles of cyclic bending.

[0036] Silane coupling agent KH560 (1-2%): Its core function is to act as a "molecular bridge" between inorganic fillers (porous silica powder, flake aluminum powder, etc.) and the organic polymer matrix. After hydrolysis, the alkoxy group at one end of its molecule condenses with the hydroxyl group on the filler surface, while the epoxy or amino group at the other end interacts with the polymer chain segment. This significantly improves the interfacial bonding force between the filler and the matrix, prevents cracking at the interface due to stress concentration, and enhances the water resistance and durability of the coating.

[0037] Flake aluminum powder (2.5-4.0%, particle size 6-12 μm): is the preferred functional pigment for achieving low infrared emissivity. Flake aluminum powder possesses extremely high metallic luster and reflectivity. In the coating of this invention, the flake aluminum powder is enriched on the surface and oriented parallel to the coating surface, forming a dense, mirror-like reflective layer. This reflective layer can efficiently reflect infrared radiation in the 8-14 μm band, thereby significantly reducing the infrared emissivity of the coating. The particle size is controlled within this range to ensure sufficient hiding power and reflectivity without affecting the smoothness and flexibility of the coating.

[0038] Infrared absorbing pigments (1-2%, copper manganese oxide or iron manganese oxide): These work synergistically with flake aluminum powder to construct an infrared stealth control layer. While the flake aluminum powder primarily acts as a reflector, it may not completely reflect infrared radiation at certain angles or wavelengths. Infrared absorbing pigments (such as copper manganese black or iron manganese black) themselves have high absorptivity in these wavelengths. They can absorb residual infrared radiation that has passed through the aluminum powder reflective layer or failed to be reflected, converting it into minute amounts of heat energy. This heat energy is then slowly dissipated through a porous silicon insulating layer with extremely low thermal conductivity, further "masking" the thermal signal and reducing the emissivity to below 0.30.

[0039] Graphene microflakes (0.2-0.5%): as a multifunctional additive. First, graphene has extremely high thermal conductivity. In this system, its small, uniform dispersion is not used to enhance overall thermal conductivity, but rather to "homogenize heat flow," that is, to help rapidly diffuse local hot spots (such as heat converted from infrared-absorbing pigments) laterally, avoiding the formation of high-temperature points and thus reducing local infrared radiation intensity. Second, graphene microflakes can also enhance the mechanical strength and airtightness of the coating.

[0040] UV stabilizer (0.3-0.8%): Used to absorb or shield ultraviolet rays, preventing the polymer matrix from undergoing photo-oxidative degradation under long-term outdoor sunlight, thereby maintaining the long-term stability of the coating's mechanical properties, color, and infrared stealth function.

[0041] Balance components (defoamer, film-forming aid, deionized water): Defoamer is used to eliminate bubbles generated during preparation and coating, ensuring a dense and defect-free coating. Film-forming aid (such as dodecyl alcohol ester) is used to lower the minimum film-forming temperature of the polymer, promoting the fusion of emulsion particles at low temperatures to form a continuous and dense film. Deionized water, as an environmentally friendly solvent, constitutes the continuous phase.

[0042] As mentioned above, the double-layer composite structure of this invention is not pre-prepared as two layers and then bonded together, but rather formed in situ during a single coating-curing process. Its formation mechanism is as follows: After high-speed dispersion, modified porous silica powder and nanocellulose, under the action of silane coupling agents, exhibit strong interactions with the polymer emulsion particle surfaces, tending to be uniformly dispersed throughout the slurry system. The flake aluminum powder, infrared absorbing pigments, and graphene microflakes added in subsequent steps, due to differences in density, particle size, and surface properties compared to the porous silica powder, and dispersed at a lower (medium) speed, exhibit different bonding states with the polymer matrix. During leveling and early curing after coating, under the combined effects of gravity, solvent evaporation convection, and the interfacial energy between the coating and air, the relatively dense and smaller-sized flake aluminum powder and infrared absorbing pigments gradually migrate and accumulate towards the coating surface (air interface) as moisture evaporates and the coating shrinks. Meanwhile, the modified porous silica powder, due to its porous structure, lower density (after surface treatment), and stronger bonding with the matrix, remains more largely in the coating region near the substrate.

[0043] At a curing temperature of 60-90℃, the polymer particles fully fuse to form a film, "freezing" and fixing this filler distribution state. This naturally forms a porous silicon heat insulation layer 1, with modified porous silica powder and nanocellulose as the main components, which performs the main heat insulation function, and an infrared stealth control layer 2, with flake aluminum powder and infrared absorbing pigments as the main components, which performs the infrared stealth function. The two layers are tightly bonded by a continuous polymer matrix and an inorganic-organic interface (treated with a silane coupling agent), without a clear physical boundary, hence the name "functionally integrated bilayer composite structure". Example 1

[0044] This embodiment provides an infrared stealth porous silicon heat insulation car cover material and its preparation method.

[0045] Raw material preparation: Prepare the following raw materials by weight percentage: 30% modified porous silica powder, 25% high-elastic aliphatic waterborne polyurethane, 10% silicone-modified acrylic emulsion, 2% nanocellulose, 3% liquid polybutadiene toughening agent, 1.5% silane coupling agent KH560, 3.0% flake aluminum powder (particle size D50 approximately 8μm), 1.5% copper manganese oxide infrared absorbing pigment, 0.3% graphene microflakes, 0.5% UV stabilizer, 0.2% defoamer, 1.0% film-forming aid, and deionized water to bring the total to 100%. All raw materials are commercially available industrial-grade products. The modified porous silica powder is a hydrophobic porous silica micropowder pretreated with aminosilane.

[0046] Preparation steps: (1) Preparation of basic emulsion: In a clean dispersion vessel equipped with stirring and speed control, first add metered deionized water (approximately 40% of the total water volume), then sequentially add the high-elasticity aliphatic waterborne polyurethane and the silicone-modified acrylic emulsion. Start the stirring process, maintaining a low speed of 200-300 rpm for approximately 10-15 minutes. The purpose of this stage is to ensure the two polymer emulsions are initially and uniformly mixed, and to prevent emulsion breakage due to high-speed shear. Continue stirring until the system presents a homogeneous, slightly bluish, milky-white liquid; this forms the base emulsion.

[0047] (2) Main construction and initial dispersion of the insulation layer: While maintaining stirring, add the full metered amounts of modified porous silica powder, nanocellulose, and silane coupling agent KH560 sequentially to the base emulsion obtained in step (1). After the addition is complete, rapidly increase the stirring speed to 1000-1200 rpm for high-speed dispersion. The high-speed dispersion process lasts for 40 minutes. This stage is one of the key aspects of the process. High-speed shearing force breaks down the soft agglomerates of modified porous silica powder, causing it to be uniformly dispersed in the form of primary particles or small aggregates.

[0048] Nanocellulose is fully defibrinated under high shear to form a nanofiber network that interweaves with porous silica particles.

[0049] Under high-speed dispersion and the presence of moisture in the system, the alkoxy groups of silane coupling agent KH560 partially hydrolyze to generate silanols. These silanols undergo condensation reactions with the silanols on the surface of porous silica powder and interact with the hydroxyl groups on the surface of nanocellulose and the active groups on polymer segments. This process significantly improves the interfacial compatibility between the inorganic filler and the organic polymer, laying the foundation for the excellent mechanical properties of the final coating.

[0050] After this step, a uniform slurry A with high viscosity but good flowability is obtained, in which modified porous silica powder and nanocellulose have been initially compounded with the polymer matrix.

[0051] (3) Introduction and dispersion of filler for infrared stealth functional layer: Reduce the stirring speed to a medium speed of 500-600 rpm. While stirring, slowly add the flake aluminum powder, copper manganese oxide infrared absorbing pigment, and graphene microflakes to slurry A in sequence. The addition process should be slow and carried out in batches to prevent the lightweight powders from flying away and agglomerating. After all the powders have been added, continue dispersing at this medium speed for 20 minutes.

[0052] This stage employs medium-speed dispersion to ensure that fillers such as flake aluminum powder are fully wetted and dispersed, while minimizing mechanical damage to the flake structure of the aluminum powder (high-speed shearing may cause the flake aluminum powder to curl or break), thus protecting its high reflectivity mirror properties.

[0053] The addition of graphene microflakes at this stage helps to disperse them more evenly in the system. Medium-speed stirring initially disperses these functional fillers in slurry A, but due to differences in physicochemical properties, their bonding state with the matrix differs from that of the fillers added in step (2), laying the groundwork for gradient distribution in the subsequent curing process.

[0054] After this step, composite slurry B containing all solid fillers is obtained.

[0055] (4) Additives and final adjustment of slurry: While maintaining a slow stirring speed of 400-500 rpm, add the liquid polybutadiene toughening agent, UV stabilizer, defoamer, and film-forming aid to the composite slurry B in sequence. Finally, add the remaining deionized water to adjust the slurry to a suitable viscosity for coating. Continue stirring for 15 minutes until all additives are uniformly dispersed, there are no visible particles or agglomerates in the system, and the slurry is a uniform grayish-black color with good flowability and appropriate viscosity, thus obtaining the final coating slurry C. The slow stirring at this stage aims to achieve uniform mixing and facilitate defoaming.

[0056] (5) Coating, film formation and structural curing: The final coating slurry C is filtered through a 200-mesh sieve to remove any trace amounts of large particles or impurities introduced during production. The filtered slurry is then evenly coated onto a pre-prepared TPU (thermoplastic polyurethane) car cover base film using a doctor blade or roller coating method. The wet film thickness is precisely controlled by adjusting the doctor blade gap or roller speed, resulting in a dry film thickness of approximately 65 μm after drying and curing.

[0057] The coated wet film is sent into a temperature-zoned drying tunnel for programmed curing. Specifically, it is first dried at 60°C for 2-3 minutes to allow most of the moisture to evaporate slowly and the slurry to initially level. Then, it is heated to 80-85°C and dried for 5-8 minutes. This stage is the key period for film formation and structural stabilization. The polymer particles fuse to form a continuous film under the action of the film-forming aid. At the same time, due to the continuous evaporation of the solvent (water) and the shrinkage of the film, the flake aluminum powder and infrared absorbing pigments added in step (3) migrate and accumulate to the air interface, while the modified porous silica powder added in step (2) is more fixed in the area close to the base film, and finally a double-layer composite structure is formed: the side close to the TPU base film is a porous silica heat insulation layer 1 rich in modified porous silica powder and nanocellulose. Its main function is to use the nanopores of porous silica to efficiently block heat conduction; the side close to the air is an infrared stealth control layer 2 rich in flake aluminum powder and copper manganese oxide infrared absorbing pigments. Its function is to form a highly reflective and highly absorbent surface to reduce infrared emissivity. The two layers are firmly bonded together through a polymer matrix (a blend of high-elastic aliphatic waterborne polyurethane and silicone-modified acrylic emulsion) and an interface reinforced with a silane coupling agent. Finally, the material is cooled and wound up to obtain an infrared stealth porous silicone heat-insulating car cover material. Example 2

[0058] The main difference between this embodiment and Embodiment 1 is that the proportions of some raw materials have been adjusted.

[0059] The raw materials by weight percentage are as follows: modified porous silica powder 28%, high-elastic aliphatic waterborne polyurethane 22%, organosilicon modified acrylic emulsion 9%, nanocellulose 2.5%, liquid polybutadiene toughening agent 3.5%, silane coupling agent KH560 1.8%, flake aluminum powder (particle size D50 approximately 10μm) 3.5%, iron manganese oxide infrared absorbing pigment 1.8%, graphene microflakes 0.4%, UV stabilizer 0.6%, defoamer 0.15%, film-forming aid 1.2%, and deionized water to make up the balance.

[0060] The preparation method is the same as in Example 1. The resulting material has a dry film thickness of approximately 70 μm, a thermal conductivity of 0.027 W / (m·K), an infrared emissivity of 0.29, a resistance to repeated bending cycles greater than 10,000 times, and a thermal insulation temperature difference of 18℃. Example 3

[0061] The difference between this embodiment and Embodiment 1 is that it uses boundary values ​​for some parameters.

[0062] The raw materials by weight percentage are as follows: 35% modified porous silica powder, 20% high-elastic aliphatic waterborne polyurethane, 12% organosilicon modified acrylic emulsion, 3% nanocellulose, 4% liquid polybutadiene toughening agent, 2% silane coupling agent KH560, 4.0% flake aluminum powder (6μm particle size), 2% copper manganese oxide infrared absorbing pigment, 0.5% graphene microflakes, 0.8% UV stabilizer, 0.25% defoamer, 1.5% film-forming aid, and deionized water to make up the balance.

[0063] The preparation method is the same as in Example 1, but due to the higher solid content, the amount of deionized water was appropriately increased in step (4) to adjust the viscosity. The resulting material has a dry film thickness of approximately 80 μm. Its thermal conductivity is 0.025 W / (m·K), exhibiting the best thermal insulation performance; its infrared emissivity is 0.26; its resistance to repeated bending is approximately 10,500 times (meeting the requirements, but slightly inferior to Examples 1 and 2, reflecting the slight effect of high filler content on flexibility); and its thermal insulation temperature difference reaches 20°C.

[0064] The technical solutions described in the embodiments of this application successfully construct a functionally integrated bilayer composite structure through specific component synergy and gradient film formation processes. This structure comprises a porous silicon thermal insulation layer 1 rich in modified porous silicon powder and an infrared stealth control layer 2 enriched with flake aluminum powder and infrared absorbing pigments. This structure enables the material to maintain excellent flexibility and wide temperature range adaptability while possessing extremely low thermal conductivity and infrared emissivity, achieving a balance between high-efficiency thermal insulation and infrared stealth.

[0065] Obviously, the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention also intends to include these modifications and variations.

Claims

1. An infrared stealth porous silicon heat-insulating car cover material, characterized in that, By weight percentage, it includes the following components: Modified porous silica powder 25-35%, high-elastic aliphatic waterborne polyurethane 20-28%, organosilicon modified acrylic emulsion 8-12%, nanocellulose 1-3%, liquid polybutadiene toughening agent 2-4%, silane coupling agent KH560 1-2%, flake aluminum powder 2.5-4.0%, infrared absorbing pigment 1-2%, graphene microflakes 0.2-0.5%, UV stabilizer 0.3-0.8%, with the balance being defoamer, film-forming aid and deionized water.

2. The infrared stealth porous silicon heat-insulating car cover material according to claim 1, characterized in that, The particle size of the flake aluminum powder is .

3. The infrared stealth porous silicon heat-insulating car cover material according to claim 1, characterized in that, The infrared absorbing pigment is at least one of copper manganese oxide or iron manganese oxide.

4. The infrared stealth porous silicon heat-insulating car cover material according to any one of claims 1 to 3, characterized in that, The car cover material is a functionally integrated double-layer composite structure, which includes a porous silicon heat insulation layer (1) as the bottom layer and an infrared stealth control layer (2) as the surface layer. The porous silicon heat insulation layer (1) and the infrared stealth control layer (2) are integrated and work together, wherein the porous silicon heat insulation layer (1) is used to block heat conduction to reduce the surface temperature. The infrared stealth control layer (2) is used to reduce infrared emissivity and absorb infrared radiation in order to achieve thermal imaging detection.

5. The infrared stealth porous silicon heat-insulating car cover material according to claim 4, characterized in that, The dry film thickness of the car cover material is 50-80 μm.

6. The infrared stealth porous silicon heat-insulating car cover material according to claim 4, characterized in that, The thermal conductivity of the car cover material is ≤0.028W / (m·K).

7. The infrared stealth porous silicon heat-insulating car cover material according to claim 4, characterized in that, The infrared emissivity of the car cover material is ≤0.30 in the 8-14μm infrared band.

8. The infrared stealth porous silicon heat-insulating car cover material according to claim 4, characterized in that, The car cover material is resistant to ≥10,000 cycles of repeated bending and does not crack, peel off, or delaminate after bending.

9. The infrared stealth porous silicon heat-insulating car cover material according to claim 4, characterized in that, The applicable temperature range of the car cover material is -33℃ to 33℃.

10. A method for preparing an infrared stealth porous silicon heat-insulating car cover material as described in any one of claims 1 to 9, characterized in that, Includes the following steps: (1) The high-elastic aliphatic waterborne polyurethane, the organosilicon-modified acrylic emulsion and a portion of deionized water are mixed and stirred at low speed to form a basic emulsion. (2) Add the modified porous silica powder, the nanocellulose and the silane coupling agent KH560 to the base emulsion obtained in step (1) and disperse at high speed for 30-45 minutes; (3) Add the flake aluminum powder, the infrared absorbing pigment and the graphene microplate to the mixture obtained in step (2) and disperse at a medium speed for 20 minutes; (4) Add the liquid polybutadiene toughening agent, the UV stabilizer, the defoamer, the film-forming aid and the remaining deionized water to the mixture obtained in step (3), and stir for 15 minutes until the mixture is uniform; (5) After filtering the mixed slurry obtained in step (4), it is coated onto the car cover base film, and the dry film thickness is controlled to be 50-80μm. It is then dried and cured at 60-90℃ to obtain the infrared stealth porous silicon heat insulation car cover material.

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