A high-power radiative cooling film and a method of making the same

Abstract

The application discloses a high-power radiation refrigeration film and a preparation method thereof, relates to the technical field of refrigeration film materials, and particularly relates to the patent classification F25B23 / 00. The preparation method comprises the following steps: providing a base film, performing pretreatment, alternately depositing TiO2 and SiO2 layers on the pretreated base film by magnetron sputtering to form a reflection layer, combining an emission layer on the reflection layer through an adhesive, and performing hot-press bonding on the above film layers, so that the refrigeration film is obtained. The reflection layer material is mixed with polyvinylidene fluoride and boron nitride composite particles, and the prepared refrigeration film has high-power infrared radiation performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of refrigeration film materials, belongs to the patent classification F25B23 / 00, and specifically relates to a high-power radiative refrigeration film and a preparation method thereof. BACKGROUND

[0002] Under the background of global energy crisis and increasingly serious environmental problems, as a passive cooling technology that does not consume traditional energy and only relies on the thermal radiation of an object itself to achieve cooling, the radiative refrigeration technology has great application potential in the fields of building energy saving, aerospace, electronic device heat dissipation and the like due to its green environmental protection and energy saving and high efficiency. As the core material of the radiative refrigeration technology, the radiative refrigeration film can realize the cooling of an object surface by efficiently emitting infrared radiation in the atmospheric window band and dissipating heat in the form of electromagnetic waves to the low-temperature universe space.

[0003] However, the existing radiative refrigeration films on the market still have significant deficiencies in the infrared radiation effect. Most radiative refrigeration film materials have weak selective emission capacity for infrared radiation. In actual application, the radiative refrigeration film cannot accurately and efficiently radiate heat in the atmospheric window band, and part of the heat is dissipated in a non-effective band, or there is excessive absorption in other bands, resulting in low overall radiative refrigeration efficiency and difficulty in achieving ideal cooling effect. From the material point of view, the infrared radiation characteristics of the materials used in the traditional radiative refrigeration film are not good. The infrared emissivity of part of the materials is low, which cannot meet the demand of high-power radiative refrigeration. SUMMARY

[0004] The present application aims to provide a high-power radiative refrigeration film and a preparation method thereof. The technical problem of poor infrared radiation performance of the radiative refrigeration film proposed in the background technology is solved. The high-power radiative refrigeration film prepared by the present application has good infrared radiation performance.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical scheme:

[0006] A preparation method of a high-power radiative refrigeration film, comprising the following steps:

[0007] S1, providing a base film and performing pretreatment;

[0008] S2, alternately depositing TiO2 and SiO2 layers on the pretreated base film by magnetron sputtering to form a reflection layer;

[0009] S3, combining an emission layer on the infrared reflection layer through an adhesive;

[0010] S4, hot pressing and bonding the above-mentioned film layers, and the high-power radiative refrigeration film is obtained.

[0011] As preferred, the base film material in step S1 is polyethylene terephthalate.

[0012] As preferred, the PTE base film thickness is 100-125 μm, and the light transmittance is ≥ 90%.

[0013] As preferred, in step S1, the pretreatment process is to first ultrasonically clean the base film, and then perform corona treatment.

[0014] As preferred, in step S2, the thickness of the TiO2 layer in the reflective layer is 100 nm, and the number of deposited layers is 5-9 layers.

[0015] As preferred, in step S2, the thickness of the SiO2 layer in the reflective layer is 150 nm, and the number of deposited layers is 5-9 layers.

[0016] As preferred, in step S3, the adhesive used is an acrylic adhesive.

[0017] As preferred, in step S3, the emissive layer material is composed of polyvinylidene fluoride and nano boron nitride composite particles.

[0018] In the technical solution of the present application, the base film uses polyethylene terephthalate, which serves as the supporting framework of the entire film structure, providing mechanical strength and stability, ensuring the adhesion of subsequent film layers and overall use performance. After pretreatment, TiO2 and SiO2 are alternately deposited on the base film to form an infrared reflective layer, which uses the refractive index difference between the two to construct a multi-layer interference structure, producing high reflection in the solar spectrum range and effectively blocking the absorption of solar radiation heat. The vibration characteristics of the C-F bond in the molecular structure of polyvinylidene fluoride (PVDF) naturally match the atmospheric window band (8-13 μm), enabling it to efficiently emit infrared radiation, transferring heat in the form of radiation to outer space. At the same time, PVDF itself has a certain reflection ability to solar light, which can reduce heat input. The addition of boron nitride nanosheets further synergistically improves the infrared radiation performance: it has high thermal conductivity and unique phonon plasmon effect, which can enhance the heat transfer within the material and optimize the distribution of infrared emission band. The composite structure of the two forms a high-efficiency heat management network, with PVDF providing a high-emissivity substrate and boron nitride nanosheets expanding the infrared radiation interface and improving the heat diffusion efficiency, thereby achieving a stronger passive cooling effect without the need for external energy.

[0019] As preferred, the preparation method of the boron nitride composite particles includes the following steps:

[0020] A1, drying and pretreating the boron nitride nanosheets;

[0021] A2, preparing a mixed solution of zinc salt and 2-methylimidazole;

[0022] A3, the pretreated boron nitride nanosheet is added into the mixed solution, heated for reaction, and after treatment, the product is obtained.

[0023] In the technical scheme of the present application, in order to further improve the infrared radiation performance, the boron nitride nanosheet is compounded with metal organic framework (MOF) to realize high-power radiation refrigeration. The specific preparation method of the boron nitride composite particle is: growing a metal organic framework (MOF) layer on the surface of the boron nitride nanosheet in situ by a solvothermal method, using the interface reaction of the active sites on the surface of the boron nitride with zinc salt and 2-methyl imidazole coordination precursor to promote the ZIF-8 type MOF to be coated on the surface of the boron nitride in a core-shell structure. The three-dimensional pore network of the ZIF-8 type MOF can regulate the dielectric environment, and the periodic pore structure can enhance the photon scattering and interface reflection in the mid-infrared wave band, and improve the electromagnetic response efficiency of the material to the infrared wave. At the same time, the MOF confinement effect can change the local electron distribution and affect the molecular vibration mode, and optimize the infrared absorption and re-emission process. In addition, the active sites on the surface of the boron nitride nanosheet and the Zn 2+ The coordination reaction occurs to form a B-N-Zn chemical bond, which restructures the interface electron cloud density, enhances the interface polarization effect, thereby improving the photon capture efficiency and the energy conversion ability in the mid-infrared wave band, improving the infrared emissivity, and further improving the infrared radiation power of the refrigeration film.

[0024] As a preferred, the boron nitride composite particle is subjected to surface modification treatment:

[0025] The boron nitride composite particle and zinc nitrate are used as raw materials, and a ZnO nanoneedle is combined on the surface of the boron nitride composite particle by a hydrothermal method to obtain a composite particle intermediate;

[0026] The surface of the composite particle intermediate is grafted with an amino silane coupling agent, and the product is obtained.

[0027] In the technical scheme of the present application, as described above, the boron nitride composite particle is doped into the polyvinylidene fluoride material to improve the infrared emissivity. However, the present application team found through research that directly doping the boron nitride composite particle into the polyvinylidene fluoride will cause the boron nitride composite particle to be unevenly dispersed in the polyvinylidene fluoride material and interface defects exist between the two, which will affect the improvement of the infrared radiation performance of the refrigeration film. In order to further solve this problem, the boron nitride composite particle is further modified in the present application, and the ZnO nanoneedle and the amino silane coupling agent are combined on the surface of the boron nitride composite particle, respectively. After modification, the anchoring effect of the ZnO nanoneedle and the hydrogen bonding force formed between the amino group and the polyvinylidene fluoride improve the bonding effect between the two, improve the dispersion effect and interface bonding force of the boron nitride composite particle in the polyvinylidene fluoride, and thus solve the above technical problems. Figure 1The surface scanning electron microscope (SEM) image of the high-power radiation refrigeration film can be observed, so that the boron nitride composite particles are embedded in the polyvinylidene fluoride surface and interior, and the overall distribution is relatively uniform and dispersed, and there is no obvious regional concentration phenomenon.

[0028] A high-power radiation refrigeration film is prepared by the above method.

[0029] Compared with the prior art, the beneficial effects of the present application are:

[0030] 1. The polyethylene terephthalate is used as the base film, and after pretreatment, TiO2 and SiO2 layers with specific thickness and number of layers are alternately deposited by magnetron sputtering, and a multilayer interference structure is constructed by using the difference in refractive index of the two, so that the high-efficiency reflection of the solar spectrum is realized, and the absorption of solar radiation heat is effectively blocked.

[0031] 2. The emission layer uses polyvinylidene fluoride and nano boron nitride composite particles, the C-F bond of the former is adapted to the atmospheric window band and has infrared emission capability, the latter grows MOF layer through solvothermal method, and is modified by combining ZnO nanoneedle and amino silane coupling agent through hydrothermal method, the pore network of MOF enhances infrared response, the modification improves the combination of particles and polyvinylidene fluoride, and the infrared emissivity is collectively improved, so that the high-power infrared radiation of the refrigeration film is realized. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 The SEM image of the surface of the high-power radiation refrigeration film of the present application. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application. In the specific embodiments, the thickness of the polyethylene terephthalate base film is 100-125 mu m, the light transmittance is greater than or equal to 90%, the purity of the boron nitride nanosheet is greater than or equal to 99%, and the sheet diameter is 50-200 nm.

[0034] Embodiment 1

[0035] Preparation of boron nitride composite particles:

[0036] Step 1: weigh 50 mg of boron nitride nanosheet, place it in a vacuum drying oven at 120 DEG C for 6 hours, and remove the surface adsorbed water and impurities.

[0037] Step 2: In a beaker, 0.58 g of zinc nitrate hexahydrate and 0.66 g of 2-methylimidazole were dissolved in 30 mL of N,N-dimethylformamide (DMF), respectively, and stirred magnetically for 30 minutes until completely dissolved. Then the two solutions were mixed and stirred for another 1 hour to form a uniform precursor solution.

[0038] Step 3: After drying, the boron nitride nanosheets were added to the precursor solution and ultrasonically dispersed for 30 minutes. Then the solution was transferred to a polytetrafluoroethylene-lined reaction kettle, which was sealed and placed in an oven at 100°C for 12 hours. After the reaction was completed, the product was cooled to room temperature and centrifuged at 8000 rpm for 10 minutes. The precipitate was collected and washed with DMF and methanol three times each, and finally dried in a vacuum drying oven at 80°C for 24 hours to obtain boron nitride composite particles.

[0039] Surface modification of boron nitride composite particles:

[0040] Step 1: 0.5 g of the above boron nitride composite particles and 50 mL of zinc nitrate solution (0.01 mol / L) were weighed into a reaction kettle and hydrothermally reacted at 100°C for 3 hours. After the reaction, the product was centrifuged (10000 rpm, 15 minutes), washed with deionized water three times, and dried at 60°C for 8 hours to obtain an intermediate with ZnO nanoneedles loaded on the surface.

[0041] Step 2: The intermediate was added to a 100 mL ethanol solution containing 0.5 mL of aminosilane coupling agent APTES, and stirred at 80°C for 2 hours. After the reaction was completed, the product was centrifuged (8000 rpm, 10 minutes), washed with ethanol twice, and dried in a vacuum drying oven at 80°C for 6 hours to obtain modified boron nitride composite particles.

[0042] Preparation of high-power radiation refrigeration film:

[0043] Step 1: Take a polyethylene terephthalate-based film and cut it to a size of 10 cm x 10 cm. First, place the base film in a beaker and add anhydrous ethanol and deionized water (volume ratio 1:1) to clean it in an ultrasonic cleaner with a power of 300 W and a frequency of 40 kHz for 15 minutes to remove surface dust and oil. After taking it out, rinse it with deionized water three times and place it in a vacuum drying oven at 50°C for 10 minutes. Then, place the dried base film in a corona treatment machine and perform surface activation at a voltage of 15 kV for 30 seconds to obtain a pretreated base film.

[0044] Step 2: Fix the pretreated base film on the sample holder of the magnetron sputtering equipment, and vacuumize to a base vacuum degree of 1 x 10 -4Pa. Argon gas (purity 99.99%) was introduced as sputtering gas, the flow rate was controlled at 30 sccm, and the working pressure was maintained at 0.5 Pa. The radio frequency power supply of the TiO2 target (purity 99.99%) was turned on, the power was set to 150 W, the deposition time was 10 minutes, and a TiO2 layer with a thickness of 100 nm was formed; after the TiO2 target power was turned off, the SiO2 target (purity 99.99%) was switched to, the radio frequency power was adjusted to 200 W, and a SiO2 layer with a thickness of 150 nm was formed after deposition for 15 minutes. TiO2 and SiO2 layers were alternately deposited according to the above parameters, 8 layers of TiO2 were deposited in total, 8 layers of SiO2 were deposited in total, and a reflective layer was formed on the pretreated base film.

[0045] Step 3: The reflective layer was uniformly coated with an acrylic adhesive (coating amount 50 g / m2). Polyvinylidene fluoride and surface-modified boron nitride composite particles were mixed at a mass ratio of 1:0.4, DMF solvent was added to prepare a composite solution, and ultrasonic dispersion was performed for 80 minutes until uniform. The composite solution was uniformly coated on the reflective layer coated with the acrylic adhesive, the wet film thickness was controlled to be 50 μm, and the coated film was placed in an oven at 80°C for drying for 30 minutes to obtain a composite film layer.

[0046] Step 4: The composite film layer was placed in a hot-pressing device and hot-pressed at a temperature of 130°C and a pressure of 2 MPa for 10 minutes, and then naturally cooled to room temperature and taken out to obtain a high-power radiation refrigeration film.

[0047] Example 2

[0048] The preparation method of the boron nitride composite particles was the same as that in Example 1.

[0049] The surface modification method of the boron nitride composite particles was the same as that in Example 1.

[0050] Preparation of the high-power radiation refrigeration film:

[0051] Step 1: A polyethylene terephthalate base film was cut into a size of 10 cm x 10 cm. First, the base film was placed in a beaker, anhydrous ethanol and deionized water (volume ratio 1:1) were added, and the surface dust and oil stains were removed by ultrasonic cleaning in an ultrasonic cleaner with a power of 300 W and a frequency of 40 kHz for 15 minutes; after taking out, the base film was washed with deionized water for 3 times, and then placed in a vacuum drying box for drying at 50°C for 10 minutes. Then, the dried base film was placed in a corona treatment machine for surface activation under the conditions of a voltage of 15 kV and a treatment time of 30 seconds to obtain a pretreated base film.

[0052] Step 2: The pretreated base film was fixed on the sample holder of the magnetron sputtering device, and the vacuum degree was pumped to 1 x 10 -4Pa. Argon gas (purity 99.99%) was introduced as sputtering gas, the flow rate was controlled at 30 sccm, and the working pressure was maintained at 0.5 Pa. The radio frequency power supply of the TiO2 target (purity 99.99%) was turned on, the power was set to 150 W, the deposition time was 10 minutes, and a TiO2 layer with a thickness of 100 nm was formed; after the TiO2 target power was turned off, the SiO2 target (purity 99.99%) was switched to, the radio frequency power was adjusted to 200 W, and a SiO2 layer with a thickness of 150 nm was formed after 15 minutes of deposition. TiO2 and SiO2 layers were alternately deposited according to the above parameters, 6 layers of TiO2 were deposited in total, and 6 layers of SiO2 were deposited in total, thereby forming a reflective layer on the pretreated base film.

[0053] Step 3: The reflective layer was uniformly coated with an acrylic adhesive (coating amount 50 g / m2). Polyvinylidene fluoride and surface-modified boron nitride composite particles were mixed at a mass ratio of 1:0.3, DMF solvent was added to prepare a composite solution, and ultrasonic dispersion was performed for 80 minutes until uniform. The composite solution was uniformly coated on the reflective layer coated with the acrylic adhesive, the wet film thickness was controlled to be 50 μm, and the coated film was placed in an oven at 80°C for drying for 30 minutes, thereby obtaining a composite film layer.

[0054] Step 4: The composite film layer was placed in a hot-pressing device, and hot-pressing was performed at a temperature of 130°C and a pressure of 2 MPa for 10 minutes. After natural cooling to room temperature, the high-power radiation refrigeration film was taken out.

[0055] Example 3

[0056] The boron nitride composite particles were prepared according to the method of Example 1.

[0057] The surface modification method of the boron nitride composite particles was the same as that of Example 1.

[0058] Preparation of the high-power radiation refrigeration film:

[0059] Step 1: A polyethylene terephthalate base film was cut into a size of 10 cm x 10 cm. The base film was first placed in a beaker, deionized water and anhydrous ethanol (volume ratio 1:1) were added, and the surface dust and oil stains were removed by ultrasonic cleaning in an ultrasonic cleaner at a power of 300 W and a frequency of 40 kHz for 15 minutes. After being taken out, the base film was washed with deionized water for 3 times, and then was placed in a vacuum drying box for drying at 50°C for 10 minutes. Subsequently, the dried base film was placed in a corona treatment machine, and surface activation was performed at a voltage of 15 kV and a treatment time of 30 seconds, thereby obtaining a pretreated base film.

[0060] Step 2: The pretreated base film was fixed on the sample holder of a magnetron sputtering device, and the vacuum degree was reduced to 1 x 10 -4Pa. Argon gas (purity 99.99%) was introduced as sputtering gas, the flow rate was controlled at 30 sccm, and the working pressure was maintained at 0.5 Pa. The radio frequency power supply of the TiO2 target (purity 99.99%) was turned on, the power was set to 150 W, the deposition time was 10 minutes, and a TiO2 layer with a thickness of 100 nm was formed; after the TiO2 target power was turned off, the SiO2 target (purity 99.99%) was switched to, the radio frequency power was adjusted to 200 W, and a SiO2 layer with a thickness of 150 nm was formed after 15 minutes of deposition. TiO2 and SiO2 layers were alternately deposited according to the above parameters, 7 layers of TiO2 were deposited in total, and 7 layers of SiO2 were deposited in total, thereby forming a reflective layer on the pretreated base film.

[0061] Step 3: The reflective layer was uniformly coated with an acrylic adhesive (coating amount 50 g / m2). Polyvinylidene fluoride and surface-modified boron nitride composite particles were mixed at a mass ratio of 1:0.35, DMF solvent was added to prepare a composite solution, and ultrasonic dispersion was performed for 80 minutes until uniform. The composite solution was uniformly coated on the reflective layer coated with the acrylic adhesive, the wet film thickness was controlled to be 50 μm, and the coated film was placed in an oven at 80°C for drying for 30 minutes, thereby obtaining a composite film layer.

[0062] Step 4: The composite film layer was placed in a hot-pressing device, and hot-pressing was performed at a temperature of 130°C and a pressure of 2 MPa for 10 minutes. After natural cooling to room temperature, the high-power radiation refrigeration film was taken out.

[0063] Example 4

[0064] The boron nitride composite particles were prepared according to the method of Example 1.

[0065] The surface modification method of the boron nitride composite particles was the same as that of Example 1.

[0066] Preparation of the high-power radiation refrigeration film:

[0067] Step 1: A polyethylene terephthalate base film was cut into a size of 10 cm x 10 cm. First, the base film was placed in a beaker, anhydrous ethanol and deionized water (volume ratio 1:1) were added, and the base film was cleaned in an ultrasonic cleaner at a power of 300 W and a frequency of 40 kHz for 15 minutes to remove surface dust and oil stains. After being taken out, the base film was washed with deionized water for 3 times and was placed in a vacuum drying box for drying at 50°C for 10 minutes. Subsequently, the dried base film was placed in a corona treatment machine for surface activation at a voltage of 15 kV and a treatment time of 30 seconds, thereby obtaining a pretreated base film.

[0068] Step 2: The pretreated base film was fixed on the sample holder of a magnetron sputtering device, and the vacuum was pumped to a base vacuum degree of 1 x 10 -4Pa. Argon gas (purity 99.99%) was introduced as sputtering gas, the flow rate was controlled at 30 sccm, and the working pressure was maintained at 0.5 Pa. The radio frequency power supply of the TiO2 target (purity 99.99%) was turned on, the power was set to 150 W, the deposition time was 10 minutes, and a TiO2 layer with a thickness of 100 nm was formed. After turning off the TiO2 target power, the SiO2 target (purity 99.99%) was switched to, the radio frequency power was adjusted to 200 W, and a SiO2 layer with a thickness of 150 nm was formed after 15 minutes of deposition. TiO2 and SiO2 layers were alternately deposited according to the above parameters, 9 layers of TiO2 were deposited in total, and 9 layers of SiO2 were deposited in total, thereby forming a reflective layer on the pretreated base film.

[0069] Step 3: The reflective layer was uniformly coated with an acrylic adhesive (coating amount 50 g / m2). Polyvinylidene fluoride and surface-modified boron nitride composite particles were mixed at a mass ratio of 1:0.5, DMF solvent was added to prepare a composite solution, and ultrasonic dispersion was performed for 80 minutes until uniform. The composite solution was uniformly coated on the reflective layer coated with the acrylic adhesive, the wet film thickness was controlled at 50 μm, and the coated film was placed in an oven at 80°C for drying for 30 minutes, thereby obtaining a composite film layer.

[0070] Step 4: The composite film layer was placed in a hot-pressing device, hot-pressed at a temperature of 130°C and a pressure of 2 MPa for 10 minutes, and then naturally cooled to room temperature before being taken out, thereby obtaining a high-power radiation refrigeration film.

[0071] Example 5

[0072] The boron nitride composite particles were prepared according to the method of Example 1.

[0073] The surface modification method of the boron nitride composite particles was the same as that of Example 1.

[0074] Preparation of a high-power radiation refrigeration film:

[0075] Step 1: A polyethylene terephthalate base film was cut into a size of 10 cm x 10 cm. The base film was first placed in a beaker, deionized water and anhydrous ethanol (volume ratio 1:1) were added, and the surface dust and oil stains were removed by ultrasonic cleaning in an ultrasonic cleaner with a power of 300 W and a frequency of 40 kHz for 15 minutes. After being taken out, the base film was washed with deionized water for 3 times, and then dried in a vacuum drying oven at 50°C for 10 minutes. Subsequently, the dried base film was placed in a corona treatment machine, and the surface was activated under the conditions of a voltage of 15 kV and a treatment time of 30 seconds, thereby obtaining a pretreated base film.

[0076] Step 2: The pretreated base film was fixed on the sample holder of a magnetron sputtering device, and the vacuum degree was reduced to 1 x 10 -4Pa. Argon gas (purity 99.99%) was introduced as sputtering gas, the flow rate was controlled at 30 sccm, and the working pressure was maintained at 0.5 Pa. The radio frequency power supply of the TiO2 target (purity 99.99%) was turned on, the power was set to 150 W, the deposition time was 10 minutes, and a TiO2 layer with a thickness of 100 nm was formed; after the TiO2 target power was turned off, the SiO2 target (purity 99.99%) was switched to, the radio frequency power was adjusted to 200 W, and a SiO2 layer with a thickness of 150 nm was formed after deposition for 15 minutes. TiO2 and SiO2 layers were alternately deposited according to the above parameters, 5 layers of TiO2 were deposited in total, and 5 layers of SiO2 were deposited in total, thereby forming a reflective layer on the pretreated base film.

[0077] Step 3: The reflective layer was uniformly coated with an acrylic adhesive (coating amount 50 g / m2). Polyvinylidene fluoride and surface-modified boron nitride composite particles were mixed at a mass ratio of 1:0.2, DMF solvent was added to prepare a composite solution, and ultrasonic dispersion was performed for 80 minutes until uniform. The composite solution was uniformly coated on the reflective layer coated with the acrylic adhesive, the wet film thickness was controlled to be 50 μm, and the coated sample was placed in an oven at 80°C for drying for 30 minutes, thereby obtaining a composite film layer.

[0078] Step 4: The composite film layer was placed in a hot-pressing device, hot-pressed at a temperature of 130°C and a pressure of 2 MPa for 10 minutes, and then taken out after natural cooling to room temperature, thereby obtaining a high-power radiation refrigeration film.

[0079] Comparative Example 1:

[0080] The difference between Comparative Example 1 and Example 1 lies in that no surface-modified boron nitride composite particles were added in Step 3 of the preparation process of the refrigeration film.

[0081] Comparative Example 2

[0082] The difference between Comparative Example 2 and Example 1 lies in that the surface-modified boron nitride composite particles were replaced by boron nitride nanosheets in Step 3 of the preparation process of the refrigeration film.

[0083] Comparative Example 3

[0084] The difference between Comparative Example 3 and Example 1 lies in that the surface-modified boron nitride composite particles were replaced by boron nitride composite particles in Step 3 of the preparation process of the refrigeration film, i.e., no surface modification was performed on the boron nitride composite particles.

[0085] Performance test:

[0086] 1. Infrared emissivity test: Fourier transform infrared spectrometer (FTIR) was used to test the emissivity in the 8-13 μm atmospheric window band. The sample was cut into a size of 2 cm x 2 cm, fixed on a sample holder, and tested in a dry nitrogen atmosphere using a MIR-100 infrared spectrometer. The scanning range was 400-4000 cm -1, resolution 4 cm -1 The average emissivity of the sample in the 8-13 μm wavelength range was calculated by comparison with the standard blackbody radiation curve. The test results are shown in Table 1.

[0087] 2. Solar reflectance test: The reflectance in the wavelength range of 200-2500 nm was determined using a UV-Vis-NIR spectrophotometer (with an integrating sphere accessory). The sample size was 3 cm x 3 cm, and the Lambda 950 spectrometer was used for testing with a scanning interval of 5 nm and an incident light angle of 8°. The reference standard white plate (reflectivity 99%) was used to calculate the average reflectivity in the full wavelength range. The test results are shown in Table 1.

[0088] 3. Infrared radiation power test: The infrared radiation meter with an 8-13 μm bandpass filter was used in a constant temperature test chamber (temperature control 25 ± 0.5°C, dry nitrogen atmosphere): first, the instrument was calibrated using a 30°C temperature-controlled blackbody source (emissivity ≥ 0.99), and then a 5 cm x 5 cm sample was fixed on an adiabatic support. The probe was vertically aligned with the sample surface at a distance of 10 cm to collect the average value of the 30-second radiation power. By subtracting the environmental reflected radiation and dividing by the test chamber window transmittance, the actual infrared radiation power of the sample in the atmospheric window wavelength range was obtained. The test results are shown in Table 1.

[0089] Table 1:

[0090]

[0091]

[0092] Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent replacements to some technical features, and any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing a high-power radiation-cooling film, characterized in that, Includes the following steps: S1. Provide a base film and perform pretreatment; S2. A reflective layer is formed by alternately depositing TiO2 and SiO2 layers on the pretreated base film using magnetron sputtering. S3. The reflective layer is bonded to the reflective layer with an adhesive. S4. The above film layers are then hot-pressed together to obtain the final product. The emission layer material is composed of polyvinylidene fluoride and modified nano boron nitride composite particles; The preparation method of boron nitride nanocomposite particles includes the following steps: A1. Drying pretreatment of boron nitride nanosheets; A2. Prepare a mixed solution of zinc salt and 2-methylimidazole; A3. Add the pretreated boron nitride nanosheets to the above mixed solution, heat to react, and after post-treatment, obtain the product; Preparation of modified boron nitride nanocomposite particles: Using boron nitride nanocomposite particles and zinc nitrate as raw materials, ZnO nanoneedles were bonded to the surface of boron nitride composite particles by hydrothermal method to obtain composite particle intermediates; Then, an aminosilane coupling agent is grafted onto the surface of the composite particle intermediate to obtain the final product.

2. The method for preparing a high-power radiation cooling film according to claim 1, characterized in that, In step S1, the base film material is polyethylene terephthalate; The PET base film has a thickness of 100–125 μm and a light transmittance of ≥90%.

3. The method for preparing a high-power radiation-cooling film according to claim 1, characterized in that, In step S1, the pretreatment process involves first ultrasonically cleaning the base film, and then performing corona treatment.

4. The method for preparing a high-power radiation-cooling film according to claim 1, characterized in that, In step S2, the thickness of the TiO2 layer in the reflective layer is 100 nm, and the number of deposition layers is 5 to 9.

5. The method for preparing a high-power radiation-cooling film according to claim 1, characterized in that, In step S2, the thickness of the SiO2 layer in the reflective layer is 150 nm, and the number of deposition layers is 5 to 9.

6. The method for preparing a high-power radiation-cooling film according to claim 1, characterized in that, In step S3, the adhesive used is an acrylic adhesive.

7. A high-power radiation cooling film, characterized in that, It is prepared by the method described in any one of claims 1-6 above.

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