Heat-insulating super-hydrophobic composite coating with high light transmittance as well as preparation method and application thereof

Abstract

The invention discloses a high-light-transmittance heat-insulation super-hydrophobic composite coating as well as a preparation method and application thereof, and relates to the technical field of coating preparation. The composite coating provided by the invention comprises a heat-insulating coating positioned on a bottom layer and a super-hydrophobic coating positioned on a top layer, wherein the heat-insulating coating comprises a binder and heat-insulating material particles dispersed in the binder; the super-hydrophobic coating comprises a micro-nano composite structure composed of modified silicon dioxide nanoparticles and fumed silica nanoparticles, the modified silicon dioxide nanoparticles are silicon dioxide nanoparticles which are prepared through hydrophobic treatment and have the particle size of 80-150 nm, and the mass ratio of the modified silicon dioxide nanoparticles to the fumed silica nanoparticles with the particle size of 15-30 nm is (0.2-0.4) g: (0.1-0.2) g; according to the composite coating provided by the invention, the light transmittance and the hydrophobicity of the composite coating are synergistically improved by regulating and controlling the proportion of silicon dioxide with different scales while the light transmittance, heat insulation and surface super-hydrophobicity are realized.

Description

Technical Field

[0001] The present invention relates to the technical field of coating preparation, and particularly relates to a heat-insulating superhydrophobic composite coating with high light transmittance, a preparation method thereof, and an application thereof. Background Art

[0002] With the continuous development of modern science and technology and industry, higher requirements are put forward for the multifunctionality of the material surface in the fields of architecture, automobiles, aerospace, etc. Especially in terms of energy conservation and environmental protection, optical performance and durability, etc., multifunctional coatings with heat insulation, superhydrophobicity, high light transmittance and long-term durability are becoming the focus of research and application; traditional single-function coatings often have difficulty meeting the multiple performance requirements in complex application environments, especially there are great technical bottlenecks in balancing heat insulation performance, light transmittance performance and maintaining long-term self-cleaning ability.

[0003] At present, heat-insulating coatings and superhydrophobic coatings have been widely used in their respective fields; however, most heat-insulating coatings lack self-cleaning function and are prone to dirt accumulation or water penetration in humid or dusty environments, thus reducing light transmittance, affecting heat dissipation performance and shortening service life; superhydrophobic coatings have been widely used in the fields of waterproofing, anti-fouling and anti-icing due to their excellent self-cleaning ability. Superhydrophobic coatings form a multi-scale rough structure with nano or micro-nano levels (such as the lotus leaf effect) on the surface and reduce the surface energy, so that water droplets form a large contact angle (≥150°) on the surface and have a small rolling angle, thus quickly sliding off and taking away the surface dirt. However, most superhydrophobic coatings have almost no reflection effect on near-infrared and mid-infrared light and are difficult to meet the energy-saving requirements; therefore, a composite coating can be constructed by combining a heat-insulating coating and a superhydrophobic coating to make up for the deficiencies of single coatings in performance; however, due to the special surface structure of superhydrophobic coatings, light scattering and reflection phenomena are likely to occur, resulting in a decrease in the transparency of the composite coating. Summary of the Invention

[0004] Embodiments of the present invention provide a heat-insulating superhydrophobic composite coating with high light transmittance and a preparation method thereof.

[0005] The preparation method includes the following steps:

[0006] S1, dispersing heat-insulating material particles in a binder to obtain a sol, and coating and forming the sol on a substrate to obtain a transparent heat-insulating coating;

[0007] S2, preparing silica gel with tetraethyl orthosilicate as a precursor, immersing the silica gel in a n-hexane solution containing trimethylchlorosilane for modification treatment, cleaning and drying to obtain modified silica nanoparticles; the particle size of the modified silica nanoparticles is 80-150 nm;

[0008] S3. Mix the modified silica nanoparticles prepared in step S2 with fumed silica nanoparticles at a mass ratio of (0.2~0.4) g:(0.1~0.2) g and disperse them in an ethanol solution of 1H,1H,2H,2H-perfluorodecyltrimethoxysilane to obtain a superhydrophobic coating precursor solution; the particle size of the fumed silica nanoparticles is 15~30 nm;

[0009] S4. Spray the superhydrophobic coating precursor solution on the thermal insulation coating by electrospray deposition method, dry it, then immerse it in an ethanol solution containing perfluorooctyltriethoxysilane, and take it out and heat-treat it at 120~150 °C to obtain a superhydrophobic coating.

[0010] Optionally, the thermal insulation material particles include at least one of indium tin oxide nanoparticles, indium antimonate tin oxide nanoparticles, fluorine-doped tin oxide nanoparticles, cerium oxide nanoparticles, titanium dioxide nanoparticles, and hollow silica microspheres.

[0011] Optionally, step S1 specifically includes:

[0012] S11. Disperse hollow silica microspheres in ethyl acetate to obtain a first thermal insulation material solution; disperse indium tin oxide nanoparticles in acetone to obtain a second thermal insulation material solution;

[0013] S12. Mix the first thermal insulation material solution and the second thermal insulation material solution and add 1,3-bis(hexafluoroisopropyl)benzene diglycidyl ether to obtain a third thermal insulation material solution;

[0014] S13. Add polydimethylsiloxane (PDMS) to the third thermal insulation material solution to form a sol, coat the sol on a substrate by spin coating, and adopt stepwise curing, and sequentially carry out low-temperature pre-curing, high-temperature curing and ultraviolet curing to obtain a thermal insulation coating.

[0015] Optionally, in step S11, the dosage ratio of hollow silica microspheres to ethyl acetate is (0.28~0.33) g:(18~22) mL, and the stirring time for obtaining the first thermal insulation material solution is 1~2 h; the dosage ratio of ITO nanoparticles to acetone is (0.1~0.2) g:(18~22) mL, and the stirring time for obtaining the second thermal insulation material solution is 0.5~1 h.

[0016] Optionally, in step S12, the dosage ratio of 1,3-bis(hexafluoroisopropyl)benzene diglycidyl ether to the mixed solution of the first thermal insulation material solution and the second thermal insulation material is (3~4) g:(45~60) mL.

[0017] Optionally, in step S13, the dosage ratio of PDMS to the third thermal insulation material solution is (0.1~0.15) g:(45~60) mL.

[0018] Optionally, in step S13, (0.02 - 0.1) g of dodecyltrimethylammonium bromide (DTAB) is added to the sol.

[0019] DTAB is a cationic surfactant that can adsorb on the surface of the heat-insulating material particles, thus preventing the agglomeration between the heat-insulating material particles and enabling the heat-insulating material particles to be more evenly dispersed in PDMS.

[0020] Optionally, in step S13, the spin-coating speed is 2000 - 3000 rpm / min, and the spin-coating time is controlled within 30 - 40 s.

[0021] Optionally, in step S13, the stepped curing treatment is as follows: first, pre-cure at 60 - 80 °C for 1 - 2 h; then raise the temperature to 120 - 160 °C for high-temperature curing for 2 - 3 h; finally, cure under ultraviolet light irradiation with a wavelength of 365 nm and a light intensity of 15 mW / cm 2 for 30 - 50 min to complete the preparation of the heat-insulating coating.

[0022] Optionally, in step S2, the method for preparing the silica gel using tetraethyl orthosilicate as the precursor is specifically as follows: using tetraethyl orthosilicate as the precursor, mixing it with absolute ethanol and deionized water to obtain a solution, adding hydrochloric acid to adjust the pH to initiate hydrolysis and condensation reactions, and obtaining the SiO2 gel after aging;

[0023] wherein, the dosage ratio of tetraethyl orthosilicate, absolute ethanol, deionized water, and hydrochloric acid is (4 - 6) mL : (45 - 65) mL : (3 - 5) mL : (0.4 - 0.5) g; the pH is maintained at 3 - 4 during the preparation of the silica gel; the aging time is between 36 - 72 h.

[0024] Optionally, in step S2, the solution containing trimethylchlorosilane is a n-hexane solution of trimethylchlorosilane, and the dosage ratio of silica gel, trimethylchlorosilane, and n-hexane is (0.2 - 0.4) g : (0.4 - 0.8) g : (30 - 50) mL.

[0025] Optionally, step S3 further includes:

[0026] Adding nanocellulose to the ethanol solution of 1,1,2,2,3,3,4,4,5,5,6,6,7,7,7 - heptadecafluorodecyltrimethoxysilane; the nanocellulose is at least one of wood pulp nanocellulose, cotton linter nanocellulose, bacterial cellulose, and calcium alginate nanocellulose.

[0027] Optionally, in step S3, the nanocellulose added to the ethanol solution of heptadecafluorodecyltrimethoxysilane is wood pulp nanocellulose, and the addition amount is 0.03 to 0.1 g.

[0028] Optionally, in step S4, the mass ratio of perfluorooctyltriethoxysilane to ethanol is (0.6 to 1) g : (120 to 150) g.

[0029] Optionally, during the process of electrospray depositing the superhydrophobic coating, the substrate temperature is maintained at 60°C, and at the same time, the environmental relative humidity is controlled within the range of 30% to 50%.

[0030] A highly light-transmissive heat-insulating superhydrophobic composite coating proposed by the present invention includes:

[0031] A transparent heat-insulating coating, comprising a binder and heat-insulating material particles dispersed in the binder;

[0032] A superhydrophobic coating covering the surface of the heat-insulating coating; the superhydrophobic coating includes a micro-nano composite structure composed of modified silica nanoparticles and fumed silica nanoparticles;

[0033] Among them, the modified silica nanoparticles are silica nanoparticles prepared by hydrophobic treatment, and their particle size is 80 to 150 nm; the particle size of the fumed silica nanoparticles is 15 to 30 nm;

[0034] The mass ratio of the modified silica nanoparticles to the fumed silica nanoparticles is (0.2 to 0.4) g : (0.1 to 0.2) g.

[0035] Optionally, the mass ratio of the modified silica nanoparticles to the fumed silica nanoparticles is 4:1; at this ratio, the fumed silica effectively fills the pores between the modified particles, forming a dense micro-nano composite structure, reducing light scattering and optimizing the hydrophobicity.

[0036] Optionally, the heat-insulating material particles include hollow silica microspheres; the hollow silica microspheres are used to reduce heat conduction.

[0037] Optionally, the heat-insulating material particles include one or more of indium tin oxide (ITO) nanoparticles, indium antimonate tin oxide (ATO) nanoparticles, fluorine-doped tin oxide (FTO) nanoparticles, cerium oxide (CeO2) nanoparticles, and titanium dioxide (TiO2) nanoparticles; these nanoparticles reduce the surface temperature by reflecting the near-infrared (NIR) part of sunlight or reducing heat conduction.

[0038] Optionally, the heat-insulating material particles include hollow silica microspheres and ITO nanoparticles.

[0039] Optionally, the binder is PDMS.

[0040] Optionally, the superhydrophobic coating further comprises nanocellulose; the nanocellulose is one or more of wood pulp nanocellulose, cotton linter nanocellulose, bacterial cellulose, and calcium alginate nanocellulose.

[0041] Optionally, the nanocellulose in the superhydrophobic coating is wood pulp nanocellulose, and the addition amount of wood pulp nanocellulose is 0.03 - 0.1 g; due to its aspect ratio and surface hydroxyl density, wood pulp nanocellulose can guide the directional arrangement of silica particles through a hydrogen bond network to form a dense micro-nano composite structure.

[0042] Optionally, the addition amount of wood pulp nanocellulose is 0.05 g.

[0043] The present invention also proposes an application of the above heat-insulating superhydrophobic composite coating in the fields of architectural glass, automotive glass, special protection equipment, etc.

[0044] The present invention has the following beneficial effects:

[0045] The heat-insulating superhydrophobic composite coating with high light transmittance proposed by the present invention includes a heat-insulating coating at the bottom layer and a superhydrophobic coating at the top layer; the bottom-layer heat-insulating coating undertakes the heat-insulating function through heat-insulating particles dispersed in the binder and allows visible light to pass through; the top-layer superhydrophobic coating constructs a hydrophobic rough structure with nano- and micro-nano multi-scales through larger-sized modified silica particles and smaller-sized fumed silica particles to reduce the surface energy, enabling water droplets to form a large contact angle and have a small rolling angle on the surface, so as to quickly slide off and carry away surface dirt, realizing the superhydrophobic function and self-cleaning function, and further through precise regulation of the ratio of modified silica particles and fumed silica particles in the superhydrophobic coating, balancing void filling and particle dispersion, reducing the light scattering and reflection of the superhydrophobic coating, and realizing the synergistic improvement of the light transmittance and hydrophobicity of the composite coating. Description of the Drawings

[0046] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention, and those of ordinary skill in the art can obtain other drawings without creative efforts based on these drawings.

[0047] Figure 1 It is a test diagram of the surface water contact angle of the composite coating prepared in Example 3 of the present invention;

[0048] Figure 2It is the optical transmittance diagram of Embodiments 1-5 of the present invention and glass;

[0049] Figure 3 It is the heating curve diagram of Embodiments 3-5 of the present invention under 10-minute light illumination. Detailed implementation manners

[0050] To make the invention objectives, features, and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the embodiments described below are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0051] The explanations of relevant English professional terms involved in the embodiments of the present invention are as follows:

[0052] ITO: Indium tin oxide; PDMS: Polydimethylsiloxane; TEOS: Tetraethyl orthosilicate; TMCS: Trimethylchlorosilane; FAS-17: Heptadecafluorodecyltrimethoxysilane.

[0053] The first aspect of the embodiments of the present invention proposes a heat-insulating superhydrophobic composite coating with high light transmittance, including a heat-insulating coating at the bottom layer and a superhydrophobic coating at the top layer; wherein, the bottom heat-insulating coating mainly undertakes the heat-insulating function and allows visible light to pass through, so as to achieve the effect of "transmitting light but not heat"; the top superhydrophobic functional coating reduces the surface energy by constructing a hydrophobic rough structure with nano- and micro-nano multi-scales, making water droplets form a large contact angle and have a small rolling angle on the surface, so as to quickly slide off and take away the surface dirt, realizing the superhydrophobic function and self-cleaning function.

[0054] The second aspect of the embodiments of the present invention explores the influence of ITO nanoparticles in the heat-insulating coating on the light transmittance and heat-insulating efficiency of the composite coating, and prepares a composite coating adaptable to different actual application scenarios by regulating the dosage of ITO nanoparticles.

[0055] The third aspect of the embodiments of the present invention explores the influence of different ratios of modified silica and fumed silica in the superhydrophobic coating on the hydrophobicity and light transmittance of the composite coating, and prepares a composite coating with excellent hydrophobicity and high light transmittance by precisely regulating the ratio of modified silica and fumed silica.

[0056] The fourth aspect of the embodiments of the present invention explores the influence of adding nanocellulose in the superhydrophobic coating on the hydrophobicity and light transmittance of the composite coating, and optimizes the nanocellulose addition scheme that can improve the hydrophobicity and light transmittance of the composite coating.

[0057] The technical solution of the present invention will be further described in detail below in conjunction with specific embodiments and the accompanying drawings:

[0058] Example 1

[0059] Step 1: Take 0.3 g of hollow silica microspheres and disperse them in 20 mL of ethyl acetate, and stir for 1.5 hours to obtain solution A; disperse 0.1 g of ITO nanoparticles in 20 mL of acetone and stir for 0.5 hours to obtain solution B.

[0060] Mix solution A and solution B and stir for 10 minutes, add 3.5 g of 1,3-bis(hexafluoroisopropyl)benzene diglycidyl ether, and ultrasonically treat for 30 minutes to obtain solution C; add 0.1 g of PDMS and stir with a magnetic stirrer for 4 hours to form a stable sol D.

[0061] Step 2: Use the spin coating method to uniformly coat solution D on the surface of the substrate at a spin coating rate of 2500 rpm / min for 30 seconds; then perform stepwise curing: pre-cure at 60 °C for 1 hour, high-temperature cure at 120 °C for 2 hours, and finally cure under ultraviolet light irradiation for 30 minutes to complete the preparation of the bottom thermal insulation coating.

[0062] Step 3: Mix 4 mL of TEOS, 55 mL of absolute ethanol, 4 mL of deionized water, and 0.5 g of hydrochloric acid, adjust the pH to 3.5, carry out hydrolysis and condensation reactions, and age for 48 hours to obtain SiO2 gel; immerse the SiO2 gel in a mixed solution of 0.4 g of TMCS and 40 mL of n-hexane, and perform fractional drying after washing to obtain modified silica nanoparticles.

[0063] Mix 0.3 g of modified silica (particle size 80 - 150 nm) and 0.15 g of fumed silica (particle size 15 - 30 nm), disperse them in a mixed solution of FAS-17 and ethanol, and perform ultrasonic treatment for 1 hour.

[0064] Step 4: Deposit the mixed solution on a substrate at 60 °C by electrospray deposition technology; subsequently, immerse the sample in a perfluorooctyltriethoxysilane / ethanol solution and perform heat treatment at 120 °C to complete the preparation of the composite coating.

[0065] Example 2

[0066] The difference between this example and Example 1 lies in Step 3.

[0067] Step 3: Mix 0.4 g of modified silica nanoparticles (particle size 80 - 150 nm) and 0.1 g of fumed silica nanoparticles (particle size 15 - 30 nm) according to a mass ratio of 4:1.

[0068] As shown in Table 1, this proportion design significantly optimizes the coating performance. The contact angle increases from 156° to 162°, and the light transmittance increases from 78.9% to 81.2%.

[0069] Specifically, at this proportion, fumed silica can effectively fill the pores between modified particles, forming a dense micro-nano composite structure, reducing light scattering and optimizing hydrophobicity.

[0070] Example 3

[0071] The difference between this example and Example 2 is that in Step 3, 0.05 g of nanocellulose is added to the FAS-17 ethanol solution.

[0072] As shown in Table 3, the addition of 0.05 g of wood pulp nanocellulose further increases the light transmittance of the composite coating to 82.3%, and the contact angle reaches 160°.

[0073] Specifically, the high aspect ratio of wood pulp cellulose enables it to guide silica particles to form a uniform micro-nano structure, reduce the voids between particles, and inhibit light scattering; the abundant hydroxyl groups on its surface form a stable interface with the Si-O groups of FAS-17, enhancing the hydrophobic durability.

[0074] Example 4

[0075] The difference between this example and Example 3 is that in Step 1, the ITO nanoparticles are 0.15 g, and the rest are exactly the same as in Example 1.

[0076] Example 5

[0077] The difference between this example and Example 3 is that in Step 1, the ITO nanoparticles are 0.2 g, and the rest are exactly the same as in Example 1.

[0078] The relevant test items for the examples of the present invention are transmittance and contact angle, and the test results are as follows in the table:

[0079]

[0080] Table 1 Test Results of Examples 1-5 and Glass

[0081] As can be seen from Table 1, compared with other examples, the composite coating prepared in Example 3 of the present invention has the highest average light transmittance, with an average light transmittance as high as 82.3%, close to that of ordinary glass (about 90%), and the surface contact angle is as high as 160° (see Figure 2 )

[0082] From the test results of Examples 3 - 5, it can be seen that when more ITO nanoparticles are added, such as in Example 4 (0.15 g of ITO nanoparticles), the light transmittance drops to 75.1%, indicating that the increase in ITO content significantly reduces the light transmittance; in Example 5 with 0.2 g of ITO nanoparticles added, the light transmittance drops sharply to 43.8%, suggesting that excessive ITO leads to severe light scattering and absorption.

[0083] Specifically, ITO nanoparticles have the property of selectively reflecting infrared rays (the core heat - insulating function), but their refractive index (~2.0) is quite different from that of the resin matrix (~1.5); as the ITO content increases, the distance between particles decreases, and the Mie scattering effect is enhanced, resulting in a decrease in the light transmittance in the visible light band.

[0084] Refer to Figure 3 , after 10 minutes of illumination, the temperature of the glass surface rises from 24.4 °C to 36.7 °C. In Example 3, after 10 minutes of illumination, the temperature rises from 24.4 °C to 34.9 °C. In Example 4, after 10 minutes of illumination, the temperature rises from 24.4 °C to 32.1 °C. In Example 5, after 10 minutes of illumination, the temperature rises from 24.4 °C to 30.6 °C; it shows that ITO reflects near - infrared light (accounting for ~50% of the solar radiation energy) through the surface plasmon resonance effect. The higher its content, the higher the infrared reflectivity and the stronger the heat - insulation performance.

[0085] By regulating different dosages of ITO nanoparticles, the composite coatings prepared by the present invention can exhibit excellent performance in different actual application scenarios.

[0086] Specifically, in Example 3, the prepared composite coating is suitable for scenarios with extremely high requirements for light transmittance, such as building daylighting glass. The light transmittance of this coating is greater than 80%. While ensuring good daylighting effects, the heat - insulation efficiency is significantly improved by 14.6%, effectively reducing the heat accumulation in the room caused by solar radiation; the coating corresponding to Example 4 is suitable for scenarios with medium light - transmittance requirements, such as automotive glass. Its light transmittance is about 75%. It can not only meet the vision requirements of drivers but also show excellent heat - insulation performance, with the heat - insulation efficiency increased by up to 37.4%; for scenarios with low light - transmittance and high heat - insulation requirements, such as the special equipment protection field, the coating of Example 5 performs well. The light transmittance of this coating is less than 50%, but the heat - insulation efficiency is close to 50%. It can provide reliable protection for special equipment, effectively blocking the external heat transfer and ensuring the normal operation and stable performance of the equipment.

[0087] Furthermore, the present invention also proposes the following comparative examples to explore the effects of different ratios of modified silica and fumed silica in the super - hydrophobic functional coating on the hydrophobicity and light transmittance of the composite coating, as well as the effects of adding nanocellulose in the super - hydrophobic functional coating on the hydrophobicity and light transmittance of the composite coating.

[0088] Comparative Example 1

[0089] The difference between this comparative example and Example 2 is that in Step 3, 0.1 g of silica nanoparticles were fixed, and the ratio of modified silica to fumed silica was adjusted; the test results of transmittance and contact angle are shown in Table 2.

[0090]

[0091] Table 2 Test Results of Composite Coatings of Modified Silica and Fumed Silica with Different Ratios

[0092] As can be seen from Table 2, when the modified silica and fumed silica are mixed at a mass ratio of 4:1 (0.4 g of modified particles + 0.1 g of fumed particles), the contact angle of the composite coating is 162°, and the transmittance is 81.2%. At this ratio, the fumed silica can effectively fill the pores between the modified particles, forming a dense micro-nano composite structure, reducing light scattering and optimizing hydrophobicity.

[0093] If the ratio is adjusted to 3:1 (0.3 g of modified particles + 0.1 g of fumed particles), the contact angle of the composite coating drops to 158°, and the transmittance is 78.2%; when the ratio is 2:1 (0.2 g of modified particles + 0.1 g of fumed particles), the contact angle of the composite coating is only 154°, and the transmittance is 74.6%, indicating that the excessive accumulation of fumed particles leads to an increase in surface energy and an aggravation of reflection loss.

[0094] Further adjusting the ratio to 5:1 (0.5 g of modified + 0.1 g of fumed), the contact angle slightly rises to 160°, but the transmittance drops to 78.8%, indicating that excessive modified particles cause local agglomeration and enhanced scattering.

[0095] The ratio of 4:1 of modified silica to fumed silica balances pore filling and particle dispersion, achieving a synergistic improvement in transmittance (reaching 81.2%) and hydrophobicity (contact angle reaching 162°).

[0096] Comparative Example 2

[0097] The difference between this comparative example and Example 3 is that first, in Step 3, the effects of adding nano-cellulose from different sources on the hydrophobicity and transmittance of the composite coating were explored, and the test results are shown in Table 3.

[0098] As can be seen from Table 3, the addition of wood pulp nano-cellulose further increases the transmittance to 82.3%, and the contact angle reaches 160°; while the transmittance of cotton linter, bacterial cellulose, and calcium alginate nano-cellulose is only 76 - 79%, and the contact angle ≤ 155°; due to its aspect ratio and surface hydroxyl density, wood pulp nano-cellulose can guide the directional arrangement of silica particles through a hydrogen bond network to form a dense micro-nano composite structure.

[0099]

[0100] Table 3 Comparison test results of nanocellulose from different sources

[0101] Secondly, in step 3, the effects of different addition amounts (0.03, 0.05, 0.07, 0.1 g) of wood pulp nanocellulose were explored, and the test results are shown in Table 4.

[0102]

[0103] Table 4 Test results of different addition amounts of wood pulp nanocellulose

[0104] As can be seen from Table 4, when the addition amount of wood pulp nanocellulose is 0.05 g, the light transmittance reaches the peak value of 82.3%, and the contact angle is 160°.

[0105] When the addition amount of wood pulp nanocellulose increases to 0.1 g, the light transmittance drops to 75.1%, and the contact angle drops to 155°; The experiment shows that an addition amount of 0.05 g can maximize the structure optimization effect without causing agglomeration, while excessive addition will damage the continuity of the micro-nano structure, resulting in enhanced light scattering and decreased hydrophobicity; This result verifies that the optimal addition range is 0.03 - 0.1 g, and 0.05 g is the critical optimal value of performance.

[0106] The above-described embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it; Although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: They can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; And these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A preparation method of a heat-insulating and superhydrophobic composite coating with high light transmittance, characterized in that, It includes the following steps: S1. Dispersing heat-insulating material particles in a binder to obtain a sol, and coating the sol on a substrate to form a film to obtain a transparent heat-insulating coating; S2. Preparing silica gel using tetraethyl orthosilicate as a precursor, immersing the silica gel in a n-hexane solution containing trimethylchlorosilane for modification treatment, and obtaining modified silica nanoparticles after washing and drying; the particle size of the modified silica nanoparticles is 80 - 150 nm; S3. Mixing the modified silica nanoparticles prepared in step S2 and fumed silica nanoparticles according to a mass ratio of (0.2 - 0.4) g : (0.1 - 0.2) g and dispersing them in an ethanol solution of 1,1,2,2,3,3,4,4,5,5,6,6,7,7,7 - heptadecafluorodecyltrimethoxysilane to obtain a superhydrophobic coating precursor solution; the particle size of the fumed silica nanoparticles is 15 - 30 nm; S4. Spraying the superhydrophobic coating precursor solution on the heat-insulating coating by electrospray deposition method, drying, impregnating it in an ethanol solution containing perfluorooctyltriethoxysilane, and heat-treating it at 120 - 150 °C after taking it out to obtain a superhydrophobic coating.

2. The preparation method of the heat-insulating superhydrophobic composite coating with high light transmittance according to claim 1, characterized in that, Step S3 further includes: Adding nanocellulose to the ethanol solution of 1,1,2,2,3,3,4,4,5,5,6,6,7,7,7 - heptadecafluorodecyltrimethoxysilane; The nanocellulose is at least one of wood pulp nanocellulose, cotton linter nanocellulose, bacterial cellulose, and calcium alginate nanocellulose.

3. The preparation method of the heat-insulating superhydrophobic composite coating with high light transmittance according to claim 2, characterized in that, The nanocellulose is wood pulp nanocellulose, and the addition amount is 0.03 - 0.1 g.

4. The preparation method of the heat-insulating superhydrophobic composite coating with high light transmittance according to claim 1, characterized in that, The heat-insulating material particles include at least one of indium tin oxide nanoparticles, indium antimonate tin oxide nanoparticles, fluorine-doped tin oxide nanoparticles, cerium oxide nanoparticles, titanium dioxide nanoparticles, and hollow silica microspheres.

5. The preparation method of the heat-insulating superhydrophobic composite coating with high light transmittance according to claim 1, characterized in that, Step S1 specifically includes: S11. Dispersing hollow silica microspheres in ethyl acetate to obtain a first heat-insulating material solution; dispersing indium tin oxide nanoparticles in acetone to obtain a second heat-insulating material solution; S12. Mixing the first heat-insulating material solution and the second heat-insulating material solution and adding 1,3 - bis(hexafluoroisopropyl)benzene diglycidyl ether to obtain a third heat-insulating material solution; S13. Adding polydimethylsiloxane to the third heat-insulating material solution to form a sol, coating the sol on a substrate by spin coating, and sequentially performing low-temperature pre-curing, high-temperature curing, and ultraviolet curing to obtain a heat-insulating coating.

6. The preparation method of the heat-insulating superhydrophobic composite coating with high light transmittance according to claim 5, characterized in that, In step S11, the dosage ratio of hollow silica microspheres to ethyl acetate is (0.28 - 0.33) g : (18 - 22) mL, and the dosage ratio of indium tin oxide nanoparticles to acetone is (0.1 - 0.2) g : (18 - 22) mL; In step S12, the dosage ratio of 1,3 - bis(hexafluoroisopropyl)benzene diglycidyl ether to the mixed solution of the first heat-insulating material solution and the second heat-insulating material solution is (3 - 4) g : (45 - 60) mL.

7. A heat-insulating superhydrophobic composite coating with high light transmittance, characterized in that, It includes: A transparent heat-insulating coating, comprising a binder and heat-insulating material particles dispersed in the binder; A superhydrophobic coating covering the surface of the heat-insulating coating; The superhydrophobic coating comprises a micro-nano composite structure composed of modified silica nanoparticles and fumed silica nanoparticles; The modified silica nanoparticles are silica nanoparticles prepared by hydrophobic treatment, with a particle size of 80-150 nm; the particle size of the fumed silica nanoparticles is 15-30 nm; The mass ratio of the modified silica nanoparticles to the fumed silica nanoparticles is (0.2-0.4) g:(0.1-0.2) g.

8. The heat-insulating and super-hydrophobic composite coating with high light transmittance according to claim 7, characterized in that, The superhydrophobic coating further comprises nanocellulose; the nanocellulose is at least one of wood pulp nanocellulose, cotton linter nanocellulose, bacterial cellulose, and calcium alginate nanocellulose.

9. The heat-insulating superhydrophobic composite coating with high light transmittance according to claim 7, characterized in that, The heat insulation material particles include at least one of indium tin oxide nanoparticles, indium tin antimony oxide nanoparticles, fluorine-doped tin oxide nanoparticles, cerium oxide nanoparticles, titanium dioxide nanoparticles, and hollow silica microspheres.

10. Application of the high light transmittance heat insulation superhydrophobic composite coating prepared by the preparation method according to any one of claims 1-6, or application of the high light transmittance heat insulation superhydrophobic composite coating according to any one of claims 7-9.

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