WO2023284350A1 - 一种具有表面周期性微纳结构的辐射制冷薄膜及制备方法 - Google Patents

一种具有表面周期性微纳结构的辐射制冷薄膜及制备方法 Download PDF

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WO2023284350A1
WO2023284350A1 PCT/CN2022/087864 CN2022087864W WO2023284350A1 WO 2023284350 A1 WO2023284350 A1 WO 2023284350A1 CN 2022087864 W CN2022087864 W CN 2022087864W WO 2023284350 A1 WO2023284350 A1 WO 2023284350A1
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nano structure
periodic micro
film
layer
coating
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PCT/CN2022/087864
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French (fr)
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贾宝华
林瀚
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伊诺福科光学技术有限公司
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
    • C08J7/04—Coating
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
    • C08J7/04—Coating
    • C08J7/06—Coating with compositions not containing macromolecular substances
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B23/00—Machines, plants or systems, with a single mode of operation not covered by groups F25B1/00 - F25B21/00, e.g. using selective radiation effect
    • F25B23/003—Machines, plants or systems, with a single mode of operation not covered by groups F25B1/00 - F25B21/00, e.g. using selective radiation effect using selective radiation effect
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2323/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
    • C08J2323/02—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
    • C08J2323/10—Homopolymers or copolymers of propene
    • C08J2323/12—Polypropene
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2327/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers
    • C08J2327/02—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment
    • C08J2327/04—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment containing chlorine atoms
    • C08J2327/06—Homopolymers or copolymers of vinyl chloride
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2327/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers
    • C08J2327/02—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment
    • C08J2327/12—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms
    • C08J2327/16—Homopolymers or copolymers of vinylidene fluoride
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2333/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Derivatives of such polymers
    • C08J2333/04—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Derivatives of such polymers esters
    • C08J2333/06—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Derivatives of such polymers esters of esters containing only carbon, hydrogen, and oxygen, the oxygen atom being present only as part of the carboxyl radical
    • C08J2333/10—Homopolymers or copolymers of methacrylic acid esters
    • C08J2333/12—Homopolymers or copolymers of methyl methacrylate
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2367/00—Characterised by the use of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Derivatives of such polymers
    • C08J2367/02—Polyesters derived from dicarboxylic acids and dihydroxy compounds
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2369/00—Characterised by the use of polycarbonates; Derivatives of polycarbonates

Definitions

  • the invention relates to the technical field of radiation refrigeration, in particular to a radiation refrigeration film with a surface periodic micro-nano structure and a preparation method thereof.
  • radiative cooling technology is widely used in building energy saving, automobile, solar battery cooling, outdoor equipment heat dissipation, outdoor equipment cooling, agricultural greenhouses, tents, umbrellas, textiles and other fields.
  • the radiation cooling film has a relatively high market share.
  • people usually attach the radiative cooling film to the outer surface of the object to be cooled, such as the outer wall or roof of the building, and then the radiative cooling film will transfer the heat in the form of infrared radiation in the atmospheric window band when reflecting sunlight sent to outer space.
  • the cooling effect of the existing radiative cooling films needs to be further improved.
  • the invention provides a radiation cooling thin film with a surface periodic micro-nano structure and a preparation method to solve the deficiencies of the prior art.
  • the present invention provides the following technical solutions:
  • an embodiment of the present invention provides a radiation cooling film with a periodic micro-nano structure on the surface, the radiation cooling film includes a periodic micro-nano structure layer, a polymer film layer and a reflective coating; wherein,
  • the periodic micro-nano structure layer, polymer film layer and reflective coating are arranged sequentially from top to bottom;
  • the polymer film layer, the periodic micro-nano structure layer and the reflective coating are arranged sequentially from top to bottom.
  • the periodic micro-nano structure layer is composed of a periodic micro-nano structure
  • the periodic micro-nano structure is periodically arranged air holes or periodically arranged dielectric pillars.
  • the periodic micro-nano structure has a width of 3-8 ⁇ m, a period of 6-12 ⁇ m, and a depth of 0.5-5 ⁇ m.
  • the polymer film layer is polyethylene terephthalate, polyvinyl chloride, polycarbonate, polymethyl methacrylate, poly Either of vinylidene fluoride and polypropylene.
  • the reflective coating is a metal coating or a dielectric coating.
  • the metal coating is an aluminum coating or a silver coating.
  • the radiative cooling film further includes a protective layer
  • the protective layer is located on the surface of the reflective coating away from the polymer film layer or the periodic micro-nano structure layer.
  • the protective layer is an anti-fingerprint coating or a hard coating layer.
  • an embodiment of the present invention provides a method for preparing a radiative cooling film, which is used to prepare the radiative cooling film with a surface periodic micro-nano structure as described in the first aspect, the method comprising:
  • a protective layer is plated on the surface of the reflective coating.
  • an embodiment of the present invention provides a method for preparing a radiative cooling film, which is used to prepare the radiative cooling film with a surface periodic micro-nano structure as described in the first aspect, the method comprising:
  • Patterns are made on the polymer substrate by laser processing to obtain a polymer film with a periodic micro-nano structure layer;
  • a protective layer is plated on the surface of the reflective coating.
  • the embodiments of the present invention provide a radiation cooling film with a surface periodic micro-nano structure and a preparation method thereof.
  • the absorption of the radiation cooling film in the visible and infrared bands is controlled by adding a periodic micro-nano structure on the surface of the polymer film layer.
  • radiation characteristics can increase the infrared radiation rate, in order to effectively improve the performance of radiation refrigeration, has a high market promotion value.
  • Fig. 1 is a schematic side view of the structure of a radiative cooling film with a surface periodic micro-nano structure provided by Embodiment 1 of the present invention
  • Fig. 2 is a schematic top view of the structure of a radiative cooling film with a surface periodic micro-nano structure provided by Embodiment 1 of the present invention
  • Fig. 3 is a schematic side view of the structure of a radiative cooling film with a surface periodic micro-nano structure provided by Embodiment 1 of the present invention
  • Figure 4 is a schematic diagram of the simulated spectral absorptivity/emissivity of the H6.5P8D2.5 microstructure PET film in the wavelength range of 8-13 ⁇ m;
  • Fig. 5 is the schematic diagram of the solar absorptivity (Asun) of H6.5P8D2.5 microstructure PET film;
  • Fig. 6 is a schematic diagram of the average emissivity of film thickness between 10 and 100 ⁇ m on Ag film;
  • Figure 7 is a schematic diagram of the calculated value of the cooling power of the H6.5P8D2.5 microstructure PET film with different thicknesses of silver-plated backside at night (a) and during the day (b);
  • Figure 8 is a schematic diagram of the transmission spectrum of the atmosphere at different locations when the amount of water vapor is different, the water 3mm is shown in black, and the water 0R-50 is shown in red;
  • Figure 9 is calculated based on the atmospheric transmittance spectrum of 0R-50 (Hawthorn) water, with silver-coated H6.5P8D2.5 microstructure PET films of different thicknesses and flat PET films with different thicknesses of back-coated films
  • Figure 10 is a schematic diagram of the simulated absorptivity in the solar spectral range (a) and emissivity in the wavelength range of 8–13 ⁇ m (b) for different structural depths (between 0.5 and 5 ⁇ m) on PET.
  • Figure 11 is a schematic diagram of the calculated cooling power of H6.5P8 microstructured PET films with different structural depths coated with silver at night (a) and day (b);
  • Figure 12 is a schematic representation of measured absorption/emission spectra of a commercial refrigeration film (a) and a silver-backed microstructured PET film (b);
  • Figure 13 is a schematic diagram of the calculated cooling power of commercial refrigeration films at night (a) and during the day (b) and silver-coated microstructured PET films;
  • Figure 14 is a photo of the microstructured PET film before (a) and after (b) the silver coating film and the photo of the experimental setup (c) used for the measurement;
  • Figure 15 is a schematic diagram of the measured temperature and ambient temperature of the microstructure PET film plated with silver on the back of the night (a) and daytime (b), where Ta is the ambient temperature, and Tfilm is the cooling film temperature;
  • Fig. 16 is the schematic diagram of temperature test box
  • 17 is a schematic diagram of a temperature measurement system
  • Fig. 18 is cloudy day measurement result
  • Figure 19 is the cloudy measurement result
  • Fig. 20 is the sunny day measurement result
  • Fig. 21 is the schematic diagram of measuring box
  • Figure 22 is a photo of the refrigeration power measurement system
  • Figure 23 is the power measurement result (cloudy).
  • Figure 24 is the power measurement result (sunny day).
  • Figure 25 is the measurement result of cooling power at night
  • Figure 26 is the refrigeration power at a fixed working temperature
  • Fig. 27 is a radiation cooling film with a surface periodic micro-nano structure and its preparation method provided by Embodiment 2 of the present invention.
  • Fig. 28 is a radiative cooling film with surface periodic micro-nano structure and its preparation method provided by Embodiment 3 of the present invention.
  • the embodiment of the present invention provides a radiation cooling film with a periodic micro-nano structure on the surface, and the radiation cooling film includes a periodic micro-nano structure layer, a polymer film layer and a reflective coating; wherein,
  • the periodic micro-nano structure layer, polymer film layer and reflective coating are arranged sequentially from top to bottom, as shown in Figures 1-2;
  • the polymer film layer, the periodic micro-nano structure layer and the reflective coating are arranged sequentially from top to bottom, as shown in FIG. 3 .
  • the refrigerating power of the radiative cooling film can reach 122W/m 2 on a sunny day, which can improve the power density of the current radiative cooling film. Due to its flexibility and easy application, it can be widely used in wearable cooling devices, foldable cooling devices, retractable cooling curtains, car coverings, and building surface cooling applications.
  • the periodic micro-nano structure layer is composed of periodic micro-nano structures
  • the periodic micro-nano structure can be periodically arranged air holes, or periodically arranged dielectric pillars, and can also be any periodically distributed pattern, including patterns with mutually nested patterns with different periods.
  • the periodic micro-nano structure can be processed using photoresist (mainly ultraviolet photoresist, or UV glue) and photolithography, or directly processed on the polymer substrate by laser ablation technology, and controlled Structural parameters to control the visible light transmittance and infrared emission spectrum of the material.
  • the periodic micro-nano structure has a width of 3-8 ⁇ m, preferably 6.5 ⁇ m, a period of 6-12 ⁇ m, preferably 8 ⁇ m, and a depth of 0.5-5 ⁇ m, preferably 2.5 ⁇ m.
  • the polymer film layer is an ordinary polymer, and its optional range includes polyethylene terephthalate, polyvinyl chloride, polycarbonate, polymethyl methacrylate, polydidene Vinyl fluoride, polypropylene, etc.
  • the reflective coating is a metal coating or a dielectric coating, wherein the metal coating may be an aluminum coating or a silver coating for reflecting visible light.
  • the metal coating may be an aluminum coating or a silver coating for reflecting visible light.
  • any other highly reflective metals can also be selected, which are not limited in this embodiment.
  • the radiation cooling film further includes a protective layer for protecting the surface of the radiation cooling film
  • the protective layer is located on the surface of the reflective coating away from the polymer film layer or the periodic micro-nano structure layer, but whatever it is, it is attached to the reflective coating.
  • the protective layer is an anti-fingerprint coating (AF layer) or a hard coating layer (HC layer).
  • AF layer anti-fingerprint coating
  • HC layer hard coating layer
  • the microstructure PET film is marked according to its different structural dimensions; H6.5P8D2.5".
  • Figure 4 shows the simulated absorption spectra of H6.5P8D2.5 microstructured PET films with different thicknesses on a 200 nm Ag film. Then, the solar absorptivity (Asun) (Fig. 5) and average emissivity (Fig. 6) of H6.5P8D2.5 were calculated in the 8 to 13 ⁇ m (E@8–13 ⁇ m) wavelength range. Based on the simulation, the absorption spectra of the microstructured PET film with different thicknesses on the silver film are shown in Fig. 4.
  • FIG. 7 shows the calculated cooling power of different thicknesses of H6.5P8D2.5 microstructured PET films coated with silver on the backside at an ambient temperature of 300 K at night and day, respectively.
  • the conduction and convection coefficients are set to 6.9W/m 2 K.
  • the sunlight power density during the daytime is 1000 Wm -2 .
  • the thickness of the silver plating on the back of H6.5P8D2.5 is calculated at 10
  • the diurnal cooling power of the microstructured PET film in the range of 100 ⁇ m and 100 ⁇ m ranged from 65.7 Wm ⁇ 2 to 120 Wm ⁇ 2 and 29.5 Wm ⁇ 2 to 55.4 Wm ⁇ 2 , respectively ((a) in Fig. 7).
  • the cooling power of the H6.5P8D2.5 microstructure PET film coated with silver on the back with a thickness of 50 ⁇ m is 163.1Wm -2 and 114.5Wm -2 at night and day, respectively.
  • the cooling power of the H6.5P8D2.5 microstructured PET film with a thickness of 50 ⁇ m coated with silver at night and day is 103.1 Wm -2 and 56.6 Wm - 2, respectively. 2 .
  • the PET film with microstructure is higher than the PET film without microstructure ((a) and (b) in Fig. 9).
  • the nighttime and daytime cooling of H6 based on the atmospheric transmission spectrum of water 0R-50 (Hawthorn) (red line in Fig. 8), the nighttime and daytime cooling of H6.
  • the power is about 2.3Wm -2 to 7Wm -2 higher ((a) and (b) in Fig. 9).
  • the nighttime and daytime cooling power of the H6.5P8D2.5 microstructured PET film coated with silver on the back is about 3.5 Wm higher than that of the flat PET film of the same thickness -2 to 9.1Wm -2 ((c) and (d) in Fig. 9). Therefore, by fabricating microstructures on the PET film, the cooling power of the back-coated PET film can be effectively improved.
  • the pore width (H), period (P), thickness of the PET film and thickness of the Ag film were fixed as 6.5 ⁇ m, 8 ⁇ m, 50 ⁇ m and 200 nm, respectively, and only the depth of the microstructure was changed.
  • (a) and (b) in Fig. 10 show the simulated absorptivity in the solar spectral range and the simulated emissivity spectra in the wavelength range of 8–13 ⁇ m for H6.5P8 microstructured PET films with different structure depths coated with silver on the back .
  • the absorption/emission spectra of the microstructured PET film coated with silver on the back slightly changed with the increase of the microstructure depth in two wavelength ranges.
  • the solar absorptance (Asun) ((c) in Fig. 10) and the average emissivity in the wavelength range of 8 and 13 ⁇ m (E@8–13 ⁇ m) (Fig. (d) in 10).
  • the 50 ⁇ m thick H6.5P8D microstructured PET film coated with silver on the back has the highest average emissivity of 94.7% in the wavelength range of 8–13 ⁇ m at a depth of 2.5 ⁇ m.
  • the structure depth of silver-plated backside is 0.5-5 ⁇ m
  • the diurnal cooling power of the structured PET films ranged from 109.2 Wm ⁇ 2 to 115.5 Wm ⁇ 2 and 51.2 Wm ⁇ 2 to 55.3 Wm ⁇ 2 , respectively ((b) in Figure 11 ). Based on these results, the difference in diurnal cooling power of silver-backed microstructured PET films with a microstructure depth in the range of 2.5 ⁇ m to 3.5 ⁇ m is less than 0.7 Wm ⁇ 2 . Therefore, there is a large margin of error in the depth of the proposed microstructure during fabrication.
  • FIG. 12 show the absorption/emission spectra of the commercial refrigeration film and the microstructured PET film (experimentally fabricated) coated with silver on the back, respectively.
  • the average emissivity of the commercial refrigeration film in the solar absorptivity (Asun) and 8 and 13 ⁇ m (E@8–13 ⁇ m) wavelength ranges is 5.1% and 94%, respectively.
  • the Asun and E@8-13 ⁇ m of the silver-coated microstructured PET were 7.6% and 91.5%, respectively.
  • the Asun and E@8–13 ⁇ m of the silver-coated microstructured PET obtained from the measured absorption/emissivity are higher or lower than the simulation results, respectively. This result was attributed to the insufficient quality of the silver film deposited on the backside of the microstructured PET film.
  • the maximum temperature difference of the backside silver-coated microstructured PET was slightly larger than that of the commercial refrigeration film.
  • the calculated cooling power of the backside silver-coated microstructured PET film during the day is lower than the cooling capacity of the commercial refrigeration film, because the backside silver-coated microstructure PET film has a higher absorption rate in the solar spectrum range.
  • FIG. 14 show the photographs of the microstructured PET film before and after silver plating and the experimental setup used for the measurement, respectively.
  • large-area microstructured PET films have been fabricated.
  • the backside of the microstructured PET film was plated with silver ((b) in Figure 14) and put into the device ((c) in Figure 14) to test its refrigeration performance.
  • (a) and (b) in FIG. 15 show the temperature (Tfilm) and ambient temperature (Ta) of the backside silver-coated microstructured PET film measured at night and day, respectively.
  • the temperature of the microstructured PET film coated with silver on the back is about 6 °C lower than the ambient temperature at night.
  • the temperature of the microstructured PET film coated with silver on the backside was 2.2 to 5.1 °C lower than the ambient temperature under sunlight irradiation with a power density of 634.4 Wm -2 and 1078.2 Wm -2 . Therefore, the microstructured PET film coated with silver on the back exhibits good cooling performance both at night and during the day.
  • the radiation film temperature test box is mainly composed of film test area unit, lifting table, shell and other parts.
  • the schematic diagram of the overall structure is shown in Figure 16.
  • the shell material is 316L stainless steel, which is divided into two parts, and the upper and lower parts are connected by flanges.
  • a window of 100mm ⁇ 100mm is opened on the top of the upper cover part for placing Zn-Se glass, and the size of the glass is 100mm ⁇ 100mm ⁇ 5mm.
  • the infrared transmittance of ZnSe is 75%-80%, and it can withstand pressure.
  • the lower part is designed as a double-layer structure, which can measure both vacuum and non-vacuum conditions inside.
  • the entire outer surface is wrapped in aluminum foil.
  • the cooling radiant film is fixed by a polytetrafluoroethylene (PTFE) fixture with a large thermal resistance.
  • PTFE polytetrafluoroethylene
  • the upper and lower surfaces of the film are not in contact with other structures to ensure that the real temperature of the upper and lower surfaces of the film is measured and avoid temperature due to heat conduction. loss.
  • the fixture is placed on the lifting platform, which is a three-axis manual moving platform, which can realize that when the Z-axis is adjusted to the highest position, the radiation cooling film should be as close as possible to the Zn-Se glass window, which is used to control the alignment between the film and the glass on the top of the shell. , and the distance between the film and the glass.
  • the red dots in Figure 16 are the layout of thermocouples.
  • thermocouples Clamp the radiation film to be measured with a size of 120mm ⁇ 120mm on the fixture, arrange K-type thermocouples according to the layout shown in Figure 16, and measure the ambient temperature of the upper surface, the lower surface, and the position under the film that is not exposed to sunlight and the temperature on the film.
  • the ambient temperature of the location exposed to sunlight was recorded in real time with a temperature collector (Fluke SERIES III).
  • the solar irradiance data is collected through the light collector (Jianda PeopleSoft), and the data is recorded with the supporting software on the notebook, and the real-time humidity is measured and recorded through the hygrometer (Jianda PeopleSoft).
  • the overall measurement system is shown in Figure 17.
  • the diurnal and nighttime temperature changes of the radiant film were measured under different weather conditions.
  • the temperature on the side irradiated by the sun is higher.
  • the ambient temperature on the film is the heat source, so the ambient temperature above the radiant film (Tambient-u) and the temperature on the lower surface of the radiative film (Tfilm-b) are selected as Observe the object, observe the cooling effect during the period of 12:00-14:00 when the sun is the strongest; while measuring at night, the external ambient temperature is low, and the inside of the box is the heat source to be cooled.
  • the ambient temperature under the radiation film is selected (Tambient-b) and the upper surface temperature of the radiation film (Tfilm-u) are the observation objects.
  • the measured cooling radiant film can achieve a temperature difference of 3-8°C no matter day or night.
  • the maximum temperature difference during the day is 8°C
  • the maximum temperature difference at night is 5.5°C.
  • the refrigeration power measurement box is composed of a heat preservation fixture, a heating sheet and a shell.
  • the schematic diagram of the overall structure is shown in Figure 21.
  • the main part of the cabinet is designed and manufactured with 18mm thick acrylic transparent board, and there is a 100 ⁇ 100mm square working area in the center of the upper cover.
  • the 12mm thick acrylic board is used, and the infrared transmittance can reach 90%.
  • the cooling radiant film is pasted on the ceramic heating sheet that can be heated evenly through thermal conductive silicone grease.
  • the heating sheet is placed on the polytetrafluoroethylene (PTFE) fixture, and it is tightly connected by tightening to reduce the heat loss of the heating sheet.
  • the red dots in Figure 21 are the arrangement points of the thermocouples, respectively measuring the surface temperature (T-film) and the ambient temperature (T-ambient) of the film.
  • the all-in-one machine controls the intermediate components (for example: DC voltage relay switch) to realize the control of the start and stop of the heating plate.
  • the PLC all-in-one machine automatically collects the proportion of the start-stop time of the heating element and the heating power of the heating element, and calculates the actual heating power of the heating element during this period, which is the cooling power of the radiant cooling film. To reduce the influence of heat conduction, the measurement will be carried out in a vacuum environment.
  • the overall measurement system is shown in Figure 22, including (from left to right in the figure) a control box, a DC adjustable voltage source, a withstand voltage test box and a vacuum pump.
  • the cooling power of the nanostructure designed cooling radiant film was measured under different weather conditions (sunny, cloudy). Assemble each part of the device and check whether the connection is tight, power on to check whether the PLC all-in-one machine can operate normally, whether the temperature reading of the thermocouple is correct, the reading of the thermocouple is related to the ambient temperature and the connection circuit, so the thermocouple should be calibrated, Place the whole set of equipment in an open and unsheltered outdoor place, cover the window first, and start to calibrate the thermocouple through the control panel when the temperature reading is stable. After calibration, the temperature difference between the cooling radiation film and the environment should be zero degrees, and remove the cover at this time The experiment started.
  • the power data extraction should be at least half an hour after the start, and the longer the experiment is carried out, the more accurate the result will be.
  • the power measurement is performed simultaneously with the temperature measurement. Get the power corresponding to the temperature difference reached.
  • the experiment was divided into four groups according to the preset specific temperature, namely 30°C group, 35°C group, 40°C group, and 45°C group.
  • the initial experimental procedure is basically the same as the previous experiment.
  • the thermocouple After the thermocouple is calibrated, use the vacuum pump to evacuate the pressure-resistant housing, and wait for the temperature of the PLC integrated machine to stabilize; manually input a fixed temperature value, turn on the control switch, and perform a test on the device. Preheat, when the temperature reaches the preset value, restart the device to start the experiment. Do each group for at least half an hour, the longer the time, the more accurate the result. .
  • turn off the control switch export the experimental data, and the end of a group of experiments; respectively input different preset experimental environment temperatures, repeat the above steps until the four groups have completed the measurement to complete the experiment.
  • the cooling power of the radiant film is measured in cloudy and sunny days, and the results are shown in Figure 25.
  • the power is 47.7W/m 2
  • the average power is 83.9W/m 2 .
  • the cooling power of the cooling radiant film at different working temperatures is shown in Figure 26.
  • This experiment was carried out at night. Although the experiment was carried out under vacuum, the ambient temperature at night was relatively low, and the temperature difference from the preset temperature was large, so the heat from the heating plate would also radiate to the surrounding environment through the window. Therefore, the measured results are the result of the combined effect of the cooling radiant film and the surrounding environment. It cannot represent the cooling power of the cooling radiant film at this temperature, but it shows the use effect that the radiant film can achieve in application scenarios similar to the experimental conditions.
  • the embodiments of the present invention provide a radiation cooling film with a periodic micro-nano structure on the surface.
  • the absorption and radiation characteristics of the radiation cooling film in the visible and infrared bands are controlled by adding a periodic micro-nano structure on the surface of the polymer film layer. , can increase the infrared radiation rate to effectively improve the performance of radiative refrigeration, and has a high market promotion value.
  • an embodiment of the present invention provides a method for preparing a radiation cooling film, which is used to prepare a radiation cooling film with a surface periodic micro-nano structure as described in the first embodiment above.
  • the method includes:
  • the embodiment of the present invention provides a method for preparing a radiation cooling film, which uses ultraviolet lithography to add periodic micro-nano structures on the surface of the polymer film layer to control the absorption and radiation characteristics of the radiation cooling film in the visible and infrared bands,
  • the infrared radiation rate can be increased to realize the effective improvement of radiation refrigeration performance, and has high market promotion value.
  • an embodiment of the present invention provides a method for preparing a radiation cooling film, which is used to prepare a radiation cooling film with a surface periodic micro-nano structure as described in the first embodiment above.
  • the method includes:
  • the embodiment of the present invention provides a method for preparing a radiation cooling film, which uses laser processing technology to add periodic micro-nano structures on the surface of the polymer film layer to control the absorption and radiation characteristics of the radiation cooling film in the visible and infrared bands. Improve the infrared radiation rate to realize the effective improvement of radiation refrigeration performance, which has high market promotion value.

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Abstract

一种具有表面周期性微纳结构的辐射制冷薄膜及制备方法，其中辐射制冷薄膜包括周期性微纳结构层、聚合物膜层和反射涂层；所述周期性微纳结构层、聚合物膜层和反射涂层按照自上而下的顺序依次设置；或者，所述聚合物膜层、周期性微纳结构层和反射涂层按照自上而下的顺序依次设置。本发明提供的一种具有表面周期性微纳结构的辐射制冷薄膜及制备方法，通过在聚合物膜层的表面增设周期性微纳结构来控制辐射制冷薄膜在可见光和红外光波段的吸收和辐射特性，可提高红外辐射率，以实现辐射制冷性能的有效提升，具有较高的市场推广价值。

Description

一种具有表面周期性微纳结构的辐射制冷薄膜及制备方法
本申请要求于2021年07月15日提交中国专利局、申请号为202110800547.X、发明名称为“一种具有表面周期性微纳结构的辐射制冷薄膜及制备方法”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本发明涉及辐射制冷技术领域，尤其涉及一种具有表面周期性微纳结构的辐射制冷薄膜及制备方法。
背景技术
随着人们生活水平的提高，建筑能耗在总能耗中所占的比例越来越大。传统的主动式制冷技术(比如，空调技术)需要消耗能源来带走热量，不仅高耗能，而且采用的氟氯烃工质会对臭氧层造成破坏，从而造成温室效应、空气污染等环境污染问题。辐射制冷技术作为一种不耗能、无污染的新型被动制冷方法，对降温节能和环境保护具有积极意义，其利用的是特定波长(8-13μm)的载热红外辐射可以不受阻碍地穿过地球大气散逸到外太空的特性，通过将热源热量转化为特定波长的红外线，从而可以把它们辐射到温度极低的外太空，实现物体与外太空的热交换，达到对物体降温的目的。
目前，辐射制冷技术被广泛应用于建筑节能、汽车、太阳能电池冷却、户外设备散热、户外设备降温、农业大棚、帐篷、伞、纺织物等领域。在已经市场化的辐射制冷产品中，辐射制冷薄膜是其中市场占有率较高的一款。使用时，人们通常将辐射制冷薄膜贴附在待降温物体的外表面，比如建筑物的外墙或屋顶上，然后辐射制冷薄膜在反射太阳光时会将热量以大气窗口波段的红外辐射的方式传递至外太空。然而，现有的辐射制冷薄膜的制冷效果还有待进一步提升。
以上信息作为背景信息给出只是为了辅助理解本公开，并没有确定或者承认任意上述内容是否可用作相对于本公开的现有技术。
发明内容
本发明提供一种具有表面周期性微纳结构的辐射制冷薄膜及制备方法，以解决现有技术的不足。
为实现上述目的，本发明提供以下的技术方案：
第一方面，本发明实施例提供一种具有表面周期性微纳结构的辐射制冷薄膜，所述辐射制冷薄膜包括周期性微纳结构层、聚合物膜层和反射涂层；其中，
所述周期性微纳结构层、聚合物膜层和反射涂层按照自上而下的顺序依次设置；
或者，所述聚合物膜层、周期性微纳结构层和反射涂层按照自上而下的顺序依次设置。
进一步地，所述具有表面周期性微纳结构的辐射制冷薄膜中，所述周期性微纳结构层由周期性微纳结构构成；
所述周期性微纳结构为周期性设置的空气孔洞或者周期性设置的电介质立柱。
进一步地，所述具有表面周期性微纳结构的辐射制冷薄膜中，所述周期性微纳结构的宽度为3～8μm，周期为6～12μm，深度为0.5～5μm。
进一步地，所述具有表面周期性微纳结构的辐射制冷薄膜中，所述聚合物膜层为聚对苯二甲酸乙二酯、聚氯乙烯、聚碳酸酯、聚甲基丙烯酸甲酯、聚偏二氟乙烯、聚丙烯中的任意一种。
进一步地，所述具有表面周期性微纳结构的辐射制冷薄膜中，所述反射涂层为金属涂层或者电介质涂层。
进一步地，所述具有表面周期性微纳结构的辐射制冷薄膜中，所述金属涂层为铝涂层或者银涂层。
进一步地，所述具有表面周期性微纳结构的辐射制冷薄膜中，所述辐射制冷薄膜还包括保护层；
所述保护层位于所述反射涂层远离所述聚合物膜层或者周期性微纳结构层一侧的表面。
进一步地，所述具有表面周期性微纳结构的辐射制冷薄膜中，所述保护层为防指纹涂层或者硬镀膜层。
第二方面，本发明实施例提供一种辐射制冷薄膜的制备方法，用于制备如上述第一方面所述的具有表面周期性微纳结构的辐射制冷薄膜，所述方法包括：
制作光刻掩模板；
在聚合物膜层的表面涂覆UV胶；
通过所述光刻掩模板对所述UV胶进行紫外光曝光；
采用显影液对所述UV胶进行显影；
对所述聚合物膜层上的所述显影液进行清洗，得到周期性微纳结构层；
在所述周期性微纳结构层的表面或者所述聚合物膜层的表面镀反射涂层；
在所述反射涂层的表面镀保护层。
第三方面，本发明实施例提供一种辐射制冷薄膜的制备方法，用于制备如上述第一方面所述的具有表面周期性微纳结构的辐射制冷薄膜，所述方法包括：
采用激光加工的方式在聚合物衬底上制作图形，得到具有周期性微纳结构层的聚合物膜；
在所述周期性微纳结构层的表面或者所述聚合物膜的表面镀反射涂层；
在所述反射涂层的表面镀保护层。
与现有技术相比，本发明实施例具有以下有益效果：
本发明实施例提供的一种具有表面周期性微纳结构的辐射制冷薄膜及制备方法，通过在聚合物膜层的表面增设周期性微纳结构来控制辐射制冷薄膜在可见光和红外光波段的吸收和辐射特性，可提高红外辐射率，以实现辐射制冷性能的有效提升，具有较高的市场推广价值。
附图说明
为了更清楚地说明本发明实施例或现有技术中的技术方案，下面将对 实施例或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动性的前提下，还可以根据这些附图获得其它的附图。
图1是本发明实施例一提供的一种具有表面周期性微纳结构的辐射制冷薄膜的结构侧视示意图；
图2是本发明实施例一提供的一种具有表面周期性微纳结构的辐射制冷薄膜的结构俯视示意图；
图3是本发明实施例一提供的一种具有表面周期性微纳结构的辐射制冷薄膜的结构侧视示意图；
图4是H6.5P8D2.5微结构PET膜在8-13μm波长范围内的模拟光谱吸收率/发射率示意图；
图5是H6.5P8D2.5微结构PET膜的太阳吸收率(Asun)的示意图；
图6是在Ag膜上的膜厚度在10到100μm之间的平均发射率的示意图；
图7是在夜间(a)和在白天(b)，背面镀银的不同厚度的H6.5P8D2.5微结构PET膜的制冷功率的计算值的示意图；
图8是水汽量不同时不同位置大气的透射光谱的示意图，水3mm以黑色显示，而水0R-50以红色显示；
图9是基于0R-50(Hawthorn)水的大气透过率谱计算得出的背面镀银的具有不同厚度的H6.5P8D2.5微结构PET膜和背面镀膜的具有不同厚度的平坦的PET膜的在夜间(a)和白天(b)的制冷功率值的示意图，以及基于3mm的水的大气透射光谱计算的在夜间(c)和白天(d)的制冷功率值的示意图；
图10是模拟的不同结构深度的太阳光谱范围内的吸收率(a)和8-13μm的波长范围内的发射率(b)的示意图，在PET上结构深度在(0.5和5μm之间)太阳光谱的平均吸收率(Asun)曲线(c)，以及8和13μm波长范围内的平均发射率(E@8-13μm)曲线(d)的示意图；
图11是在夜间(a)和白天(b)，背面镀银的具有不同结构深度的H6.5P8微结构PET膜的制冷功率计算值的示意图；
图12是商业制冷膜(a)和背面镀银的微结构PET膜(b)的测量吸收/发射光谱的示意图；
图13是计算的夜间(a)和白天(b)商业制冷膜和背面镀银的微结构PET膜的制冷功率的示意图；
图14是微结构化PET膜在镀银膜之前(a)和之后(b)的照片以及用于测量的实验装置(c)的照片；
图15是夜间(a)和白天(b)背面镀银的微结构PET膜的测量温度和环境温度的示意图，Ta为环境温度，Tfilm为制冷膜温度；
图16是温度测试箱的示意图；
图17是温度测量系统的示意图；
图18是阴天测量结果；
图19是多云测量结果；
图20是晴天测量结果；
图21是测量箱的示意图；
图22是制冷功率测量系统的照片
图23是功率测量结果(多云)；
图24是功率测量结果(晴天)；
图25是夜间制冷功率测量结果；
图26是固定工作温度下的制冷功率；
图27是本发明实施例二提供的一种具有表面周期性微纳结构的辐射制冷薄膜及制备方法；
图28是本发明实施例三提供的一种具有表面周期性微纳结构的辐射制冷薄膜及制备方法。
具体实施方式
下面结合附图并通过具体实施方式来进一步说明本发明的技术方案。
实施例一
有鉴于上述现有的辐射制冷薄膜存在的缺陷，本申请人基于从事该行 业多年丰富的实务经验及专业知识，并配合学理的运用，积极加以研究创新，以希望创设能够解决现有技术中缺陷的技术，使得辐射制冷薄膜更具有实用性。经过不断的研究、设计，并经过反复试作样品及改进后，终于创设出确具实用价值的本发明。
请参考图1～3，本发明实施例提供具有表面周期性微纳结构的辐射制冷薄膜，所述辐射制冷薄膜包括周期性微纳结构层、聚合物膜层和反射涂层；其中，
所述周期性微纳结构层、聚合物膜层和反射涂层按照自上而下的顺序依次设置，如图1～2所示；
或者，所述聚合物膜层、周期性微纳结构层和反射涂层按照自上而下的顺序依次设置，如图3所示。
需要说明的是，所述辐射制冷薄膜在天气晴朗的日间的制冷功率可达122W/m 2，可改善目前辐射制冷薄膜的功率密度。由于其柔性，容易贴覆的优势可以广泛应用于可穿戴制冷器件，可折叠制冷器件，可收放制冷窗帘，汽车车衣，以及建筑物表面制冷的应用。
在本实施例中，所述周期性微纳结构层由周期性微纳结构构成；
所述周期性微纳结构可以为周期性设置的空气孔洞，或者是周期性设置的电介质立柱，还可以是任意周期性分布的图形，包括具有不同周期的图形相互嵌套的图形。所述周期性微纳结构可以使用光刻胶(主要为紫外光刻胶，或称UV胶)并使用光刻方法加工，或者采用激光烧蚀技术直接在聚合物衬底上加工，并通过控制结构参数来控制材料的可见光透射率和红外发射光谱。
优选的，所述周期性微纳结构的宽度为3～8μm，优选为6.5μm，周期为6～12μm，优选为8μm，深度为0.5～5μm，优选为2.5μm。
在本实施例中，所述聚合物膜层为普通聚合物，其可选的范围包括聚对苯二甲酸乙二酯、聚氯乙烯、聚碳酸酯、聚甲基丙烯酸甲酯、聚偏二氟乙烯、聚丙烯等等。
在本实施例中，所述反射涂层为金属涂层或者电介质涂层，其中，所述金属涂层可以为铝涂层或者银涂层，用于反射可见光。当然，也还可以 选择其他任意具有高反射性的金属，本实施例不作一一限定。
在本实施例中，所述辐射制冷薄膜还包括保护层，用于保护辐射制冷薄膜的表面；
所述保护层位于所述反射涂层远离所述聚合物膜层或者周期性微纳结构层一侧的表面，但不管是哪种，其都是与所述反射涂层贴合的。
优选的，所述保护层为防指纹涂层(AF层)或者硬镀膜层(HC层)。
需要说明的是，本实施例根据微结构PET膜的不同的结构尺寸对其进行了标记；例如，以具有6.5μm的孔宽度、8μm的周期和2.5μm的深度的微结构的膜命名为“H6.5P8D2.5”。图4显示了在200nm的Ag膜上具有不同厚度的H6.5P8D2.5微结构PET膜的模拟吸收光谱。然后，计算了H6.5P8D2.5的8至13μm(E@8-13μm)波长范围内的太阳吸收率(Asun)(图5)和平均发射率(图6)。基于模拟，在银膜上不同厚度的微结构PET膜的吸收光谱如图4所示。如图5和6所示，当H6.5P8D2.5的PET膜的厚度从10微米增加到100微米时，Asun和E@8-13μm将分别从3.7％逐渐增加到5.6％和从62.4％增加到99.2％。背面镀银的厚度为50μm的H6.5P8D2.5微结构PET膜的Asun和E@8-13μm分别为4.85％和94.7％。
基于大气透射光谱和模拟吸收光谱，计算出背面镀银的不同厚度的H6.5P8D2.5微结构PET膜的制冷功率。图7分别显示了在夜间和白天在300K的环境温度下，背面镀银的不同厚度的H6.5P8D2.5微结构PET薄膜的计算出的制冷功率。这里将传导和对流系数设置为6.9W/m 2K。另外，假设白天的太阳光功率密度为1000Wm -2。根据3mm水(图8中的黑线)和0R-50(Hawthorn)水(图8中的红线)的大气透射光谱计算的，当H6.5P8D2.5微结构PET膜的厚度从10微米增加到100微米时，夜间的制冷功率将分别从102.4Wm -2逐渐增加到176.3Wm -2，和66.1Wm -2增加至108.7Wm -2(图7中的(a))。此外，根据3mm的水(图8中的黑线)和0R-50(Hawthorn)的水(图8中的红线)的大气透射光谱，计算出H6.5P8D2.5的背面镀银的厚度在10和100μm范围内的微结构PET膜日间制冷功率分别在65.7Wm -2至120Wm -2和29.5Wm -2至55.4Wm-2的范围内(图7中的(a))。根据3mm水的大气透射光谱计算，背面镀银的厚度为50μm的H6.5P8D2.5微结构PET 膜在夜间和白天的制冷功率分别为163.1Wm -2和114.5Wm -2。另一方面，根据0R-50(Hawthorn)大气透射光谱计算，背面镀银的厚度为50μm的H6.5P8D2.5微结构PET膜在夜间和白天的制冷功率分别为103.1Wm -2和56.6Wm -2。这里以没有结构的平膜作为参考，可以看出有微结构的PET膜高于没有微结构的PET薄膜(图9中的(a)和(b))。因此，基于水0R-50(Hawthorn)的大气透射光谱(图8中的红线)，背面镀银的H6.5P8D2.5微结构PET膜相比于同样厚度的平坦的PET膜的夜间和白天制冷功率约高2.3Wm -2至7Wm -2(图9中的(a)和(b))。基于3mm水的大气透射光谱(图7中的(a))，背面镀银的H6.5P8D2.5微结构PET膜相比于同样厚度的平坦的PET膜的夜间和白天制冷功率约高3.5Wm -2至9.1Wm -2(图9中的(c)和(d))。因此，通过在PET膜上制造微结构，可以有效地提高背面镀膜的PET膜的制冷功率。
背面镀银的微结构PET膜结构参数的优化：
在模拟中，将孔宽度(H)，周期(P)，PET膜的厚度和Ag膜的厚度分别固定为6.5μm，8μm，50μm和200nm，只改变微结构的深度。图10中的(a)和(b)显示了背面镀银的具有不同结构深度的H6.5P8微结构PET膜在太阳光谱范围的模拟吸收率以及8-13μm的波长范围内的模拟发射率光谱。如图10中的(a)和(b)所示，在两个波长范围内，背面镀银的微结构PET膜的吸收/发射光谱随微结构深度的增加而略有变化。然后，计算了具有不同深度的H6.5P8微结构的太阳吸收率(Asun)(图10中的(c))和在8和13μm(E@8-13μm)波长范围内的平均发射率(图10中的(d))。如图10中的(c)和(d)所示，当H6.5P8的深度从0.5微米增加到5微米时，Asun和E@8-13μm的变化范围分别为4.6％至4.9％和89.6％至94.7％。背面镀银的厚度为50μm的H6.5P8D微结构PET膜在深度为2.5μm时在8-13μm的波长范围内具有94.7％的最高平均发射率。
接下来，基于大气透射光谱和模拟吸收光谱，计算出具有不同深度的背面镀银的H6.5P8微结构PET膜的制冷功率。图11中的(a)和(b)分别显示了在夜间和白天在300K的环境温度下，背面镀银的具有不同结构深度的H6.5P8微结构PET膜的计算出的制冷功率。这里将传导和对流系数设置 为6.9W/m 2K。另外，假设白天的太阳光功率密度为1000Wm -2。当H6.5P8微结构的深度在0.5至5μm的范围内时，根据3mm水(图8中的黑线)和0R-50(Hawthorn)水(图8中的红线)的大气透射光谱计算的日间制冷功率将从155.5Wm -2逐渐增加至163.1Wm -2。夜间制冷功率为97.6Wm -2逐渐增加至103.1Wm -2(图11中的(a))。此外，根据水3mm(图8中的红线)和水0R-50(Hawthorn)(图8中的红线)的大气透射光谱，可以估算出背面镀银的结构深度在0.5-5μm的H6.5P8微结构PET膜在日间的制冷功率分别在109.2Wm -2至115.5Wm -2和51.2Wm -2至55.3Wm -2的范围内(图11中的(b))。基于这些结果，背面镀银的具有微结构深度在2.5μm至3.5μm的范围内的微结构PET膜的日间制冷功率的差异小于0.7Wm -2。因此，在制造过程中所提出的微结构的深度有很大的误差宽容度。
本发明与商业辐射制冷膜的比较：
图12中的(a)和(b)分别显示了商用制冷膜和背面镀银的微结构PET膜(实验制作的)的吸收/发射光谱。商业制冷膜在太阳吸收率(Asun)和8和13μm(E@8-13μm)波长范围内的平均发射率分别为5.1％和94％。另外，背面镀银的微结构PET的Asun和E@8-13μm分别为7.6％和91.5％。由测得的吸收/发射率得到的背面镀银的微结构PET的Asun和E@8-13μm分别高于或低于模拟结果。将此结果归因于沉积在微结构PET膜背面的银膜质量不够高。
接下来，基于水0R-50(Hawthorn)的大气透射光谱和测得的吸收/发射光谱，计算出商用制冷膜和背面镀银微结构PET膜的制冷功率。图13中的(a)和(b)分别显示了在夜间和白天在300K的环境温度下，商用制冷膜和背面镀银微结构PET膜的制冷功率。这里将传导和对流系数设置为6.9W/m 2K。另外，假设白天的太阳光功率密度为1000Wm -2。在夜间，背面镀银微结构PET的计算出的制冷功率与商用制冷膜非常接近。此外，在夜间，背面镀银微结构PET的最大温度差比商业制冷膜的最大温度差稍大。然而白天背面镀银微结构PET膜的计算出的制冷功率低于商业制冷膜的制冷能力，因为背面镀银微结构PET膜在太阳光谱范围内具有更高的吸收率。
图14中的(a)～(c)分别显示了微结构PET膜在镀银之前和之后的照 片和用于测量的实验装置。如图14中的(a)所示，已经可以制造大面积的微结构PET膜。将微结构化的PET膜的背面镀银(图14中的(b))并放入装置(图14中的(c))中，以测试其制冷性能。图15中的(a)和(b)分别示出了在夜间和白天测量的背面镀银的微结构PET膜的温度(Tfilm)和环境温度(Ta)。如图15中的(a)所示，背面镀银的微结构PET膜的温度比夜间的环境温度低约6℃。此外，在功率密度为634.4Wm -2和1078.2Wm -2的阳光照射下，背面镀银的微结构PET膜的温度比环境温度低2.2至5.1℃。因此，背面镀银的微结构PET膜在夜间和白天均表现出良好的制冷性能。
真空条件下制冷效果的测量：
一、温度测量实验
1、装置简介
辐射膜温度测试箱主要由薄膜试验区单元、升降台、壳体等部分组成。整体结构示意图如图16所示。
壳体材料为316L不锈钢，分为两部分，上下部分由法兰联接。上盖部分的顶部开有100mm×100mm的窗口，用于放置Zn-Se玻璃，玻璃尺寸为100mm×100mm×5mm。ZnSe的红外透过率为75％-80％，且可以承压。下半部分设计为双层结构，可测量内部为真空和非真空两种情况。整个外表面用铝箔包裹。制冷辐射膜通过热阻很大的聚四氟乙烯(PTFE)夹具固定，除却边缘夹持部分，膜上下表面均不与其它结构接触以确保测得膜上下表面的真实温度，避免因导热产生温度损失。夹具放置在升降台上，升降台为三轴式手动移动台，可实现在Z轴调整到最高位置时，辐射制冷膜要尽量贴近Zn-Se玻璃窗口，用于控制膜与外壳顶部玻璃的对中，以及膜与玻璃的距离。图16中红点为热电偶的布点。
2、实验方法
将120mm×120mm尺寸的待测辐射膜夹紧在夹具上，按照图16所示布点布置K型热电偶，分别测量辐射膜上表面、下表面、膜下不受阳光照射位置环境温度和膜上受阳光照射位置环境温度，并用温度采集器(Fluke SERIES III)实时记录温度。测温的同时，通过光线采集器(建大仁科)收集太阳辐照度数据，并用笔记本上配套软件记录数据，通过湿度计(建 大仁科)测量并记录实时湿度。测量系统整体如图17所示。
将整个系统放置在空旷的场地上，每次实验开始前，先打开测量箱的上盖放置半个小时，使箱体内部温度接近环境温度，打开所有数据采集设备而后合上盖子，挡住上方窗口，此时有一个升温过程，待箱体内部温度稳定后撤去窗口上遮挡物，记录时间，开始实验。
3、结果分析
在不同天气情况下测量辐射膜日间和夜间的温度变化。在日间测量时，受阳光照射的一侧温度较高，此时，膜上环境温度为热源，因此选取辐射膜上方环境温度(Tambient-u)和辐射膜下表面温度(Tfilm-b)为观测对象，观测太阳光照最强烈的12:00-14:00时段的降温效果；而在夜间测量时，外部环境温度较低，箱体内部为待制冷的热源，此时选取辐射膜下方环境温度(Tambient-b)和辐射膜上表面温度(Tfilm-u)为观测对象。整理分析数据后结果如下：
(1)阴天
由图18可以得出在阴天时，当太阳辐照度为366.6W/m 2，湿度为28.3％时，制冷辐射膜与环境温度仍有3℃的温差。
(2)多云
由图19可知，多云时，当太阳辐照度为636W/m 2，湿度为17.2％时辐射膜与环境温度温差可达5℃。
(3)晴
由图20可得，当天气晴朗时，在太阳辐射度为898W/m 2，相对湿度为26.38％时，制冷辐射膜与环境温度温差可达8℃。而在夜间湿度相对较大，当平均湿度为44.4％时温差为5.5℃，当湿度达到74.4％时，温差降为4.5℃。
由图18至图20可以看出在无雨的天气，所测量的制冷辐射膜无论日间还是夜间可以能够实现3-8℃的温差。目前测得日间最高温差8℃，夜间最大温差5.5℃。
小结：此部分夜间温差的测量大多在晴朗情况下进行，最小的温差应出现在天气不好的白天，如有需要可以补实验数据。受ZnSe红外透过率限制，所得温差应小于能达到的最优值。
二、制冷功率测量实验
1、装置介绍
制冷功率测量箱由保温夹具、加热片、壳体组成。整体结构示意图如图21所示。箱体主体部分采用18mm厚度亚克力透明板设计制造，上盖中心留有100×100mm的正方形工作区域，采用12mm厚度亚克力板，红外透过率可达90％。将制冷辐射膜通过导热硅脂粘贴在能够均匀加热的陶瓷加热片上，加热片放置在聚四氟乙烯(PTFE)夹具上，通过加紧使其紧密连接，减少加热片的热损失。图21中红点为热电偶的布置点，分别测量膜上表面温度(T-film)和环境温度(T-ambient)。
2、实验方法
将30mm×30mm尺寸的待测辐射膜用导热硅脂贴在相同尺寸的加热片上，按照图21所示布点布置K型热电偶。利用可编程逻辑控制器(PLC)一体机作为逻辑运算与控制系统，一体机控制中间元件(例：直流电压继电器开关)实现对加热片启停的控制。开始工作后，PLC一体机把K型热电偶测得的环境温度(ambient temperature,Ta)与薄膜温度(film temperature,Tf)进行对比，若环境温度>薄膜温度，PLC一体机控制加热片对薄膜进行恒功率加热直至环境温度＝薄膜温度。PLC一体机自动采集加热片启停时间占比以及加热片加热功率，计算得出该段时间内加热片的实际加热功率，此即辐射制冷膜的制冷功率。为减少导热的影响，测量将在真空环境下进行。测量系统整体如图22所示，包括(图中从左至右依次为)控制箱、直流可调电压源、耐压实验箱和真空泵。
(1)不同天气情况
利用设计的制冷辐射膜制冷功率测量装置对纳米结构设计制冷辐射膜在不同天气(晴天、多云)情况下的制冷功率进行测量实验。将装置各部分组装并检查连接是否紧固，通电检查PLC一体机能否正常运行，热电偶温度读数是否正确，热电偶的读数与环境温度和连接电路均有关系，因此要对热电偶进行校正，将整套装置放置在空旷的无遮挡的户外场所，先遮挡住窗口，当温度读数平稳后开始通过控制面板对热电偶进行校正，校正后制冷辐射膜与环境温差应为零度，此时移开遮挡物开始实验。应注意的 是，移开遮挡物后，膜上温度有一个迅速的下降，因此开始时加热片会迅速弥补这一段温差，会导致结果偏大，所以前半个小时的结果偏大不够准确，计算功率的数据提取时至少要在开始后半个小时，且实验进行的时间越长结果越准确。功率测量与温度测量同时进行。得到与到达温差相对应的功率。
(2)固定温度
实验按照预设特定温度不同分为四个组，分别为30℃组、35℃组、40℃组、45℃组。开始的实验步骤与上一项实验基本相同，在校正完热电偶之后使用真空泵对耐压壳体抽真空，等待PLC一体机温度度数稳定；手动输入固定的温度值，打开控制开关，对装置进行预热，当温度到达预设值之后重新启动装置开始实验。每组至少做半个小时，时间越长结果越准确。.到达预计测量时长后，将控制开关置关闭，导出实验数据，为一组实验结束；分别输入不同的预设实验环境温度，重复上述步骤直至四个组均完成测量为一次实验结束。
3、结果分析
(1)不同天气情况
①白天测量
由图23可以看出当多云天气，环境温度为25℃，平均太阳辐照度473W/m 2，湿度为23.1％时，制冷辐射膜的制冷功率为67.9W/m 2。
由图24可以看出，当天气晴朗，平均太阳辐照度为898W/m 2，相对湿度为26.4％，平均环境温度为34.9℃时，制冷辐射膜的制冷功率可达122W/m 2，预期功率相对应的温差也增加到8℃。天气情况良好和环境温度增加都是增大制冷功率的原因。
②夜间测量
当夜间环境温度为12℃时，在多云和晴朗天气分别测量辐射膜的制冷功率，结果如图25所示。多云时功率为47.7W/m 2，天气晴朗时，平均功率为83.9W/m 2。远低于白天多云和晴朗时的功率67.9W/m 2和122W/m 2。可见环境温度对该辐射膜的功率有较大影响，高的工作温度更有利于制冷辐射膜发挥功效。
(2)固定工作温度功率测量
制冷辐射膜在不同工作温度下的制冷功率如图26所示。此实验在夜间进行，虽然实验是在抽真空的情况下进行的，但夜间环境温度较低，与预设温度的温差很大，所以加热片的热量也会透过窗口向周围环境辐射。因此所测量到的结果是制冷辐射膜与周围环境综合作用的结果。不能代表制冷辐射膜在此温度下的制冷功率，但展示了辐射膜在与实验工况类似的应用场景中能够达到的使用效果。
本发明实施例提供的一种具有表面周期性微纳结构的辐射制冷薄膜，通过在聚合物膜层的表面增设周期性微纳结构来控制辐射制冷薄膜在可见光和红外光波段的吸收和辐射特性，可提高红外辐射率，以实现辐射制冷性能的有效提升，具有较高的市场推广价值。
实施例二
请参考图27，本发明实施例提供一种辐射制冷薄膜的制备方法，用于制备如上述实施例一所述的具有表面周期性微纳结构的辐射制冷薄膜，所述方法包括：
S201、制作光刻掩模板。
S202、在聚合物膜层的表面涂覆UV胶。
S203、通过所述光刻掩模板对所述UV胶进行紫外光曝光。
S204、采用显影液对所述UV胶进行显影。
S205、对所述聚合物膜层上的所述显影液进行清洗，得到周期性微纳结构层。
S206、在所述周期性微纳结构层的表面或者所述聚合物膜层的表面镀反射涂层。
S207、在所述反射涂层的表面镀保护层。
本发明实施例提供的一种辐射制冷薄膜的制备方法，通过紫外光刻技术在聚合物膜层的表面增设周期性微纳结构来控制辐射制冷薄膜在可见光和红外光波段的吸收和辐射特性，可提高红外辐射率，以实现辐射制冷性能的有效提升，具有较高的市场推广价值。
实施例三
请参考图28，本发明实施例提供一种辐射制冷薄膜的制备方法，用于制备如上述实施例一所述的具有表面周期性微纳结构的辐射制冷薄膜，所述方法包括：
S301、采用激光加工的方式在聚合物衬底上制作图形，得到具有周期性微纳结构层的聚合物膜。
S302、在所述周期性微纳结构层的表面或者所述聚合物膜的表面镀反射涂层。
S303、在所述反射涂层的表面镀保护层。
本发明实施例提供的一种辐射制冷薄膜的制备方法，通过激光加工技术在聚合物膜层的表面增设周期性微纳结构来控制辐射制冷薄膜在可见光和红外光波段的吸收和辐射特性，可提高红外辐射率，以实现辐射制冷性能的有效提升，具有较高的市场推广价值。

Claims (10)

  1. 一种具有表面周期性微纳结构的辐射制冷薄膜，其特征在于，所述辐射制冷薄膜包括周期性微纳结构层、聚合物膜层和反射涂层；其中，
    所述周期性微纳结构层、聚合物膜层和反射涂层按照自上而下的顺序依次设置；
    或者，所述聚合物膜层、周期性微纳结构层和反射涂层按照自上而下的顺序依次设置。
  2. 根据权利要求1所述的具有表面周期性微纳结构的辐射制冷薄膜，其特征在于，所述周期性微纳结构层由周期性微纳结构构成；
    所述周期性微纳结构为周期性设置的空气孔洞或者周期性设置的电介质立柱。
  3. 根据权利要求2所述的具有表面周期性微纳结构的辐射制冷薄膜，其特征在于，所述周期性微纳结构的宽度为3～8μm，周期为6～12μm，深度为0.5～5μm。
  4. 根据权利要求1所述的具有表面周期性微纳结构的辐射制冷薄膜，其特征在于，所述聚合物膜层为聚对苯二甲酸乙二酯、聚氯乙烯、聚碳酸酯、聚甲基丙烯酸甲酯、聚偏二氟乙烯、聚丙烯中的任意一种。
  5. 根据权利要求1所述的具有表面周期性微纳结构的辐射制冷薄膜，其特征在于，所述反射涂层为金属涂层或者电介质涂层。
  6. 根据权利要求5所述的具有表面周期性微纳结构的辐射制冷薄膜，其特征在于，所述金属涂层为铝涂层或者银涂层。
  7. 根据权利要求1所述的具有表面周期性微纳结构的辐射制冷薄膜，其特征在于，所述辐射制冷薄膜还包括保护层；
    所述保护层位于所述反射涂层远离所述聚合物膜层或者周期性微纳结构层一侧的表面。
  8. 根据权利要求7所述的具有表面周期性微纳结构的辐射制冷薄膜，其特征在于，所述保护层为防指纹涂层或者硬镀膜层。
  9. 一种辐射制冷薄膜的制备方法，用于制备如权利要求1～8中任一项所述的具有表面周期性微纳结构的辐射制冷薄膜，其特征在于，所述方法包括：
    制作光刻掩模板；
    在聚合物膜层的表面涂覆UV胶；
    通过所述光刻掩模板对所述UV胶进行紫外光曝光；
    采用显影液对所述UV胶进行显影；
    对所述聚合物膜层上的所述显影液进行清洗，得到周期性微纳结构层；
    在所述周期性微纳结构层的表面或者所述聚合物膜层的表面镀反射涂层；
    在所述反射涂层的表面镀保护层。
  10. 一种辐射制冷薄膜的制备方法，用于制备如权利要求1～8中任一项所述的具有表面周期性微纳结构的辐射制冷薄膜，其特征在于，所述方法包括：
    采用激光加工的方式在聚合物衬底上制作图形，得到具有周期性微纳结构层的聚合物膜；
    在所述周期性微纳结构层的表面或者所述聚合物膜的表面镀反射涂层；
    在所述反射涂层的表面镀保护层。
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Publication number Priority date Publication date Assignee Title
CN113527740A (zh) * 2021-07-15 2021-10-22 伊诺福科光学技术有限公司 一种具有表面周期性微纳结构的辐射制冷薄膜及制备方法
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Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4190321A (en) * 1977-02-18 1980-02-26 Minnesota Mining And Manufacturing Company Microstructured transmission and reflectance modifying coating
US4396643A (en) * 1981-06-29 1983-08-02 Minnesota Mining And Manufacturing Company Radiation absorbing surfaces
US20130196083A1 (en) * 2012-01-27 2013-08-01 Jawaharlal Nehru Centre For Advanced Scientific Research Micropattern generation with pulsed laser diffraction
US20140085725A1 (en) * 2011-05-16 2014-03-27 Giesecke & Devrient Gmbh Two-Dimensionally Periodic, Color-Filtering Grating
US20180307138A1 (en) * 2015-10-13 2018-10-25 Microtau Ip Pty Ltd Microstructure patterns
CN110320745A (zh) * 2019-06-26 2019-10-11 复旦大学 具有理想发射谱的柔性被动冷却薄膜及其制备方法
CN111334012A (zh) * 2020-03-12 2020-06-26 厦门理工学院 一种耐热、可降解的辐射制冷薄膜及其制备方法和用途
WO2020237813A1 (zh) * 2019-05-31 2020-12-03 宁波瑞凌新能源科技有限公司 复合辐射制冷膜、复合辐射制冷膜材料及其应用
CN213291633U (zh) * 2020-06-09 2021-05-28 苏州苏大维格科技集团股份有限公司 辐射制冷薄膜
CN213291604U (zh) * 2020-06-09 2021-05-28 苏州苏大维格科技集团股份有限公司 辐射制冷薄膜
CN113527740A (zh) * 2021-07-15 2021-10-22 伊诺福科光学技术有限公司 一种具有表面周期性微纳结构的辐射制冷薄膜及制备方法

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3311094A4 (en) * 2015-06-18 2019-04-10 The Trustees of Columbia University in the City of New York SYSTEMS AND METHOD FOR RADIATION COOLING AND HEATING
CN107976731A (zh) * 2017-12-27 2018-05-01 成都菲斯特科技有限公司 一种四层结构的逆向反辐射热降温材料
CN109210653A (zh) * 2018-10-11 2019-01-15 宁波瑞凌节能环保创新与产业研究院 一种具有辐射制冷功能的阴凉库屋顶
CN112460836A (zh) * 2020-11-17 2021-03-09 淮阴工学院 被动式辐射冷却复合材料薄膜

Patent Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4190321A (en) * 1977-02-18 1980-02-26 Minnesota Mining And Manufacturing Company Microstructured transmission and reflectance modifying coating
US4396643A (en) * 1981-06-29 1983-08-02 Minnesota Mining And Manufacturing Company Radiation absorbing surfaces
US20140085725A1 (en) * 2011-05-16 2014-03-27 Giesecke & Devrient Gmbh Two-Dimensionally Periodic, Color-Filtering Grating
US20130196083A1 (en) * 2012-01-27 2013-08-01 Jawaharlal Nehru Centre For Advanced Scientific Research Micropattern generation with pulsed laser diffraction
US20180307138A1 (en) * 2015-10-13 2018-10-25 Microtau Ip Pty Ltd Microstructure patterns
WO2020237813A1 (zh) * 2019-05-31 2020-12-03 宁波瑞凌新能源科技有限公司 复合辐射制冷膜、复合辐射制冷膜材料及其应用
CN110320745A (zh) * 2019-06-26 2019-10-11 复旦大学 具有理想发射谱的柔性被动冷却薄膜及其制备方法
CN111334012A (zh) * 2020-03-12 2020-06-26 厦门理工学院 一种耐热、可降解的辐射制冷薄膜及其制备方法和用途
CN213291633U (zh) * 2020-06-09 2021-05-28 苏州苏大维格科技集团股份有限公司 辐射制冷薄膜
CN213291604U (zh) * 2020-06-09 2021-05-28 苏州苏大维格科技集团股份有限公司 辐射制冷薄膜
CN113527740A (zh) * 2021-07-15 2021-10-22 伊诺福科光学技术有限公司 一种具有表面周期性微纳结构的辐射制冷薄膜及制备方法

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