Green radiation refrigeration film based on near-infrared light conversion material and preparation method and application thereof

Abstract

The invention belongs to the technical field of radiation refrigeration, and particularly relates to a green radiation refrigeration film based on a near-infrared light conversion material and a preparation method and application of the green radiation refrigeration film. The green radiation refrigeration film based on the near-infrared light conversion material is prepared by compounding the high-molecular polymer, the green pigment and the inorganic microspheres; the film is selectively absorbed in a visible light band and then is efficiently emitted in a near-infrared light mode, the film has excellent reflectivity in a near-infrared band, and the film and the near-infrared light cooperate to achieve an excellent radiation refrigeration effect; wherein the porous structure of the high-molecular polymer enhances diffuse reflection of light; the green pigment endows the film with a green appearance, the film is selectively absorbed in a visible region and then is efficiently emitted in the form of near-infrared light, and the film has excellent near-infrared band reflectivity; the phonon polarization-phonon resonance characteristic of the inorganic microspheres is beneficial to radiation emission of heat and reduction of absorption of sunlight; the preparation method is simple, low in cost, safe and environmentally friendly, and the prepared film can be widely applied to preparation of cooling materials.

Description

Technical Field

[0001] The present invention belongs to the field of radiation cooling technology, and more specifically, relates to a green radiation cooling film based on near-infrared light conversion material, and a preparation method and application thereof. Background Art

[0002] As the global climate warms, the rapid growth of cooling demand has become a significant problem. Refrigeration electricity accounts for about 10% of the world's total electricity consumption. Traditional refrigeration technologies (such as liquid vaporization, gas expansion, thermoelectric, etc.) not only consume a lot of energy, but also aggravate the greenhouse effect and have a serious impact on the ecological environment. In this context, passive cooling strategies, with their environmental friendliness and significant carbon reduction effects, are gradually becoming one of the key technologies to promote energy reform and industrial upgrading.

[0003] As a rising star in the field of passive cooling, radiative cooling is mainly achieved in the form of coatings or thin films (films), using the atmospheric window (8-14 μm) to radiate heat into the cold outer space in the form of blackbody radiation. However, existing radiative cooling films are mostly white or silver, which is to maximize the reflection of sunlight and reduce heat absorption. Although this design effectively reduces the thermal effect, its monotonous color limits its aesthetic application. For example, Chinese patent application CN116515219A discloses a porous radiative cooling film, which has no metal reflective layer. The film can achieve a radiative cooling of up to 6.7°C, which brings a significant cooling effect to the surface of an object or a building, but its reflectivity in the near-infrared band (800nm-1600nm) is only about 56%, which greatly limits the improvement of its cooling effect. In practical applications, the aesthetic value of color is often as important as the thermal effect of the material. However, traditional color coatings usually absorb energy in the visible light band (380-760nm) and convert it into heat, thereby weakening the performance of radiative cooling. This problem creates an irreconcilable contradiction between the performance requirements and color requirements of color radiative cooling coatings.

[0004] Therefore, there is an urgent need to develop a color radiation cooling film that utilizes photoluminescent materials to combine rich colors, high reflectivity in the near-infrared band, and excellent cooling effect. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the conflict between the color and thermal effect of the radiation cooling film and the defects and shortcomings of the reflectivity and cooling effect in the near-infrared band that need to be improved, and to provide a green radiation cooling film based on near-infrared light conversion material.

[0006] Another object of the present invention is to provide a method for preparing the green radiation refrigeration film based on the near-infrared light conversion material.

[0007] Another object of the present invention is to provide an application of the green radiation refrigeration film based on near-infrared light conversion material in the preparation of cooling materials.

[0008] The above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0009] The present invention protects a green radiation cooling film based on near-infrared light conversion material, wherein the composition of the green radiation cooling film includes a high molecular polymer, a green pigment and inorganic microspheres;

[0010] Wherein, the green pigment comprises one or more of chromium-nickel co-doped magnesium oxide, chromium-nickel co-doped lithium gallate, and chromium-nickel co-doped magnesium gallate;

[0011] In the chromium-nickel co-doped magnesium oxide, the chromium doping amount is 10% to 20%, and the nickel doping amount is 0.1% to 1%, calculated as a percentage of the total molar amount of magnesium, chromium and nickel elements;

[0012] In the chromium-nickel co-doped lithium gallate or chromium-nickel co-doped magnesium gallate, the chromium doping amount is 10% to 20%, and the nickel doping amount is 0.1% to 1%, calculated as a percentage of the total molar amount of gallium, chromium and nickel elements.

[0013] The present invention uses high molecular polymer, green pigment and inorganic microspheres to prepare a green radiation cooling film based on near-infrared light conversion material. The porous structure constructed by the high molecular polymer can increase diffuse reflection; the green pigment includes one or more of chromium-nickel co-doped magnesium oxide, chromium-nickel co-doped lithium gallate, and chromium-nickel co-doped magnesium gallate, wherein Cr 3+ The dd transition of Ni leads to specific absorption and emission characteristics, namely, absorption of red light and reflection of green light. 2+ The doping of chromium and nickel will also cause the optical absorption and color change of the material, resulting in the green color of chromium and nickel co-doped magnesium oxide, chromium and nickel co-doped lithium gallate, and chromium and nickel co-doped magnesium gallate, and the green pigment can convert strong visible light absorption into near-infrared light energy, and at the same time can emit the absorbed energy in the form of fluorescence; the inorganic microspheres have significant phonon polarization-phonon resonance characteristics near the 9.6μm band, which can significantly improve the reflectivity of the solar radiation area, that is, it helps to radiate heat and reduce the absorption of sunlight, and the inorganic microspheres have low thermal conductivity and are not easy to exchange heat with objects. Therefore, the obtained green radiation cooling film shows good absorption performance in the visible light band (380-760nm), can use pigments to achieve color development while emitting the absorbed visible light band energy in the near-infrared band, and has excellent reflectivity in the near-infrared band (800-1600nm), thereby achieving excellent radiation cooling effect.

[0014] Furthermore, the high molecular polymer includes one or more of polylactic acid fiber, polydimethylsiloxane, polystyrene, polyvinyl chloride, polyethylene, and polyvinylidene fluoride.

[0015] Furthermore, the lithium gallate is LiGa5O8, which is prepared by fully sintering a Li source and a Ga source at 1300-1800°C to obtain LiGa5O8 crystals.

[0016] Furthermore, as a preferred method, LiGa5O8 is prepared by fully sintering Li2O and Ga2O3 at 1600°C to obtain LiGa5O8 crystals.

[0017] Furthermore, the magnesium gallate is MgGa2O4, which is prepared by fully sintering a Mg source and a Ga source at 1300-1800°C to obtain MgGa2O4 crystals.

[0018] Furthermore, as a preferred method, MgGa2O4 is prepared by fully sintering MgO and Ga2O3 at 1600°C to obtain MgGa2O4 crystals.

[0019] Preferably, the green pigment comprises Mg (1-x-y) Cr x Ni y O、Li(Ga (1-x-y) Cr x Ni y )5O8、Mg(Ga (1-x-y) Cr x Ni y )2O4; wherein, 0.1≤x≤0.2, 0.001≤y≤0.01.

[0020] More preferably, the green pigment comprises Mg 0.79 Cr 0.2 Ni 0.01 O、Mg 0.84 Cr 0.15 Ni 0.01 O、Mg 0.89 Cr 0.1 Ni 0.01 O. LiGa 3.95 CrNi 0.05 O8、LiGa 4.495 Cr 0.5 Ni 0.005 O8、LiGa 3.995 CrNi 0.005 O8、MgGa 1.598 Cr 0.4 Ni 0.002 O4、MgGa 1.798 Cr0.2 Ni 0.002 One or more of O4.

[0021] Furthermore, the Cr source in the green pigment includes one or more of chromium oxide, chromium carbonate, and chromium sulfate, preferably chromium oxide.

[0022] Furthermore, the Ni source in the green pigment includes one or more of nickel oxide, nickel carbonate, and nickel sulfate, preferably nickel oxide.

[0023] Furthermore, the Mg source in the green pigment includes one or more of magnesium oxide, magnesium carbonate, and magnesium sulfate, preferably magnesium oxide.

[0024] Furthermore, the Ga source in the green pigment includes one or more of gallium oxide, gallium carbonate, and gallium sulfate, preferably gallium oxide.

[0025] Furthermore, the Li source in the green pigment includes one or more of lithium carbonate, lithium oxide, and lithium sulfate, preferably lithium carbonate.

[0026] Furthermore, the preparation method of the green pigment comprises the following steps:

[0027] According to the stoichiometric ratio of each component element, the raw material is accurately weighed, and the solvent is added at a material-liquid ratio of 1: (1-5) g / mL and fully ground, and the mixture is fully calcined at 1300-1800° C. and ground after cooling to obtain a green pigment.

[0028] Furthermore, the solvent includes one or more of ethanol, methanol and water.

[0029] Furthermore, the sufficient burning time is 1 to 6 hours.

[0030] Furthermore, the sufficient grinding time is 1 to 3 hours.

[0031] Furthermore, the grinding time after cooling is 10 to 60 minutes.

[0032] Preferably, the inorganic microspheres include one or more of titanium dioxide, magnesium oxide, silicon dioxide, aluminum oxide, zirconium dioxide, and barium sulfate.

[0033] Preferably, the particle size of the inorganic microspheres is 100 nm to 10 μm.

[0034] Preferably, the mass ratio of the high molecular polymer, the green pigment and the inorganic microspheres is 1:(0.02-0.5):(0.02-0.5).

[0035] The present invention protects a method for preparing the green radiation refrigeration film based on near-infrared light conversion material, comprising the following steps:

[0036] S1. Mixing a polymer, a green pigment and inorganic microspheres in an organic solvent to obtain a suspension;

[0037] S2. The suspension obtained in step S1 is coated on a substrate, and a thin film is formed on the substrate after drying, and the thin film is peeled off to obtain a green radiation cooling film based on near-infrared light conversion material.

[0038] The green radiation refrigeration film prepared by the present invention has a simple preparation process and a fast film forming speed. The film prepared by the method can achieve the functions of lowering indoor temperature, refrigeration, freezing, temperature difference power generation, etc., thereby achieving the purpose of energy saving and emission reduction.

[0039] Preferably, in step S1, the organic solvent includes one or more of formic acid, tetrahydrofuran, carbon disulfide, dichloromethane, chloroform, and toluene.

[0040] Preferably, in step S1, the mass volume ratio of the high molecular weight polymer to the organic solvent is 1g:

[0041] (0.01~0.05)L.

[0042] Furthermore, in step S1, the mixing is mixing after ultrasonic stirring.

[0043] Preferably, in step S2, the drying condition is to dry in a constant temperature and humidity chamber at 10-40°C and a relative humidity (RH) of 40%-95% for 0.1-10 hours.

[0044] More preferably, the drying condition is drying in a constant temperature and humidity chamber at 20-40° C. and RH of 40%-90% for 0.5-5 h.

[0045] Furthermore, the constant humidity solvent in the constant temperature and humidity chamber includes one or more of deionized water, ethanol, and methanol.

[0046] Preferably, in step S2, the green radiative cooling film has a film thickness of 50 to 1000 μm. The film within this thickness range has a better solar transmittance, so that it can fully exert its cooling performance with the help of the green pigment in the film.

[0047] The present invention protects the use of the green radiation refrigeration film based on near-infrared light conversion material in the preparation of cooling materials.

[0048] Compared with the prior art, the present invention has the following beneficial effects: the present invention prepares a green radiation cooling film based on near-infrared light conversion material by compounding a high molecular polymer, a green pigment and an inorganic microsphere; the film selectively absorbs in the visible light band and then efficiently emits near-infrared light, and has excellent reflectivity in the near-infrared band, and the two synergistically achieve an excellent radiation cooling effect; wherein, the porous structure of the high molecular polymer enhances the diffuse reflection of light; the green pigment gives the film a green appearance, selectively absorbs in the visible light region and then efficiently emits near-infrared light, and has excellent reflectivity in the near-infrared band; the phonon polarization-phonon resonance characteristics of the inorganic microspheres contribute to the radiation dissipation of heat and reduce the absorption of sunlight; the preparation method of the present invention is simple, low-cost, safe and environmentally friendly, and the prepared film can be widely used in the preparation of cooling materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 This is a physical picture of the green film in Example 1.

[0050] Figure 2 These are microscope images of the green films in Examples 1 and 3.

[0051] Figure 3 This is the X-ray diffraction pattern of the green film in Example 4.

[0052] Figure 4 This is the Raman spectrum of the green film obtained by changing the chromium doping ratio in Example 4.

[0053] Figure 5 This is the absorption spectrum of the green film in Example 1 in the ultraviolet-visible-near infrared band.

[0054] Figure 6 The excitation spectra of the green films in Examples 1 and 3 under 420 nm excitation and the emission spectra at 1240 nm.

[0055] Figure 7 The excitation spectrum of the green film in Example 4 at 460 nm excitation and the emission spectrum at 1335 nm.

[0056] Figure 8 The temperature curves of the green film and the ambient air in Example 1 and Comparative Example 1 are shown.

[0057] Fig. 9 The temperature curves of the green film and the ambient air in Example 1 and Comparative Example 2 are shown.

[0058] Fig.10 The temperature curves of the green film and the ambient air in Example 1 and Comparative Example 3 are shown.

[0059] Fig.11The temperature curves of the green film and the ambient air in Example 1 and Comparative Example 4 are shown. DETAILED DESCRIPTION

[0060] The present invention is further described below in conjunction with the accompanying drawings and specific examples, but the examples do not limit the present invention in any form. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0061] Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0062] Example 1 Preparation of a green radiation cooling film based on near-infrared light conversion material

[0063] 1. Green pigment Mg 0.79 Cr 0.2 Ni 0.01 Preparation of O

[0064] Preparation of Mg 0.79 Cr 0.2 Ni 0.01 O, the matrix is ​​MgO, and the percentage of the total molar amount of Mg, Cr and Ni, in which the doping ion Cr 3+ and Ni 2+ The doping amount is 20% and 1% respectively. According to the stoichiometric ratio of each component element, accurately weigh 1g of the mixed raw material with a molar ratio of MgO:Cr2O3:NiO=0.79:0.1:0.01. Place the above 1g of mixed raw material in an agate mortar and then add 3mL of ethanol and grind for 1h. After the raw materials are fully mixed, move them to a corundum crucible, cover them, place them in a high-temperature reactor and burn them at 1600℃ for 2h, then cool them naturally to room temperature, take out the sample and grind it for 15min to obtain the green pigment Mg 0.79 Cr 0.2 Ni 0.01 O.

[0065] 2. Preparation of green radiative cooling films based on near-infrared light conversion materials

[0066] First, 0.45 g of polyvinyl chloride powder was added to 5 mL of carbon disulfide and stirred magnetically at room temperature to form a 90 mg / mL solution. 0.05 g of Mg was added to the solution. 0.79 Cr 0.2 Ni 0.01O and 0.05 g SiO2 nanoparticles (particle size 100 nm) were ultrasonically dispersed at room temperature using a magnetic stirrer to form a uniformly dispersed suspension, the suspension was poured into a square glass mold (depth of 500 μm), the mold was transferred to a constant temperature and humidity chamber at 20°C and 90% RH, dried for 0.5 h, and finally peeled off from the mold to obtain a porous green radiant cooling film.

[0067] Example 2 Preparation of a green radiation cooling film based on near-infrared light conversion material

[0068] 1. Green pigment Mg 0.84 Cr 0.15 Ni 0.01 Preparation of O

[0069] Preparation of Mg 0.84 Cr 0.15 Ni 0.01 O, the matrix is ​​MgO, and the percentage of the total molar amount of Mg, Cr, and Ni, among which the doping ion Cr 3+ and Ni 2+ The doping amounts are 15% and 1% respectively. According to the stoichiometric ratio of each component element, accurately weigh 1g of the mixed raw material with a molar ratio of MgO:Cr2O3:NiO=0.84:0.075:0.01. Place the above 1g of mixed raw material in an agate mortar and then add 3mL of ethanol and grind for 1h. After the raw materials are fully mixed, move them to a corundum crucible, cover them, place them in a high-temperature reactor and burn them at 1600℃ for 2h, then cool them naturally to room temperature, take out the sample and grind it for 15min to obtain the green pigment Mg 0.84 Cr 0.15 Ni 0.01 O.

[0070] 2. Preparation of green radiative cooling films based on near-infrared light conversion materials

[0071] First, 0.3 g of polyethylene powder was added to 5 mL of tetrahydrofuran and stirred magnetically at room temperature to form a 60 mg / mL solution. 0.02 g of Mg was added to the solution. 0.84 Cr 0.15 Ni 0.01 O and 0.02g TiO2 nanoparticles (particle size 300nm) were ultrasonically dispersed at room temperature using a magnetic stirrer to form a uniformly dispersed suspension, the suspension was poured into a square glass mold (depth of 200μm), the mold was transferred to a constant temperature and humidity chamber at 30℃ and 60% RH, dried for 1h, and finally peeled off from the mold to obtain a porous green radiative cooling film.

[0072] Example 3 A green radiation cooling film based on near-infrared light conversion material

[0073] 1. Green pigment Mg 0.89 Cr 0.1 Ni 0.01 Preparation of O

[0074] Preparation of Mg 0.89 Cr 0.1 Ni 0.01 O, the matrix is ​​MgO, and the percentage of the total molar amount of Mg, Cr, and Ni, among which the doping ion Cr 3+ and Ni 2+ The doping amount is 10% and 1% respectively. According to the stoichiometric ratio of each component element, accurately weigh 1g of the mixed raw material with a molar ratio of MgO:Cr2O3:NiO=0.89:0.05:0.01. Place the above 1g of mixed raw material in an agate mortar and then add 3mL of ethanol and grind for 1h. After the raw materials are fully mixed, move them to a corundum crucible, cover them, place them in a high-temperature reactor and burn them at 1600℃ for 2h, then cool them naturally to room temperature, take out the sample and grind it for 15min to obtain the green pigment Mg 0.89 Cr 0.1 Ni 0.01 O.

[0075] 2. Preparation of green radiative cooling films based on near-infrared light conversion materials

[0076] First, 0.45 g of polystyrene powder was added to 5 mL of formic acid and stirred magnetically at room temperature to form a 90 mg / mL solution. 0.03 g of Mg was added to the solution. 0.89 Cr 0.1 Ni 0.01 O and 0.03g TiO2 nanoparticles (particle size 500nm) were ultrasonically dispersed at room temperature using a magnetic stirrer to form a uniformly dispersed suspension, the suspension was poured into a square glass mold (depth of 300μm), the mold was transferred to a constant temperature and humidity chamber at 40℃ and 80%RH, dried for 2h, and finally peeled off from the mold to obtain a porous green radiant cooling film.

[0077] Example 4 Preparation of a green radiation cooling film based on near-infrared light conversion material

[0078] 1. Green Pigment LiGa 3.95 CrNi 0.05 Preparation of O8

[0079] Preparation of LiGa 3.95 CrNi 0.05 O8, the matrix is ​​LiGa5O8, and the percentage of the total molar amount of Ga, Cr, and Ni is calculated, among which the doping ion Cr 3+and Ni 2+ The doping amount is 20% and 1% respectively. According to the stoichiometric ratio of each component element, accurately weigh 1g of the mixed raw material with a molar ratio of Li2CO3:Ga2O3:Cr2O3:NiO=0.55:1.975:0.5:0.05. Place the above 1g of mixed raw material in an agate mortar and then add 3mL of ethanol and grind for 1h. After the raw materials are fully mixed, move them to a corundum crucible, cover them, place them in a high-temperature reactor and burn them at 1600℃ for 2h, then cool them naturally to room temperature, take out the sample and grind it for 15min to obtain the green pigment LiGa 3.95 CrNi 0.05 O8.

[0080] 2. Preparation of green radiative cooling films based on near-infrared light conversion materials

[0081] First, 0.15 g of polydimethylsiloxane powder was added to 5 mL of dichloromethane and stirred magnetically at room temperature to form a 30 mg / mL solution. 0.01 g of LiGa 3.95 CrNi 0.05 O8 and 0.01g ZnS nanoparticles (particle size 200nm) were ultrasonically dispersed at room temperature using a magnetic stirrer to form a uniformly dispersed suspension, the suspension was poured into a square glass mold (depth of 400μm), the mold was transferred to a constant temperature and humidity chamber at 30℃ and 70% RH, dried for 5h, and finally peeled off from the mold to obtain a porous green radiant cooling film.

[0082] Example 5 Preparation of a green radiation cooling film based on near-infrared light conversion material

[0083] 1. Green Pigment LiGa 4.495 Cr 0.5 Ni 0.005 Preparation of O8

[0084] Preparation of LiGa 4.495 Cr 0.5 Ni 0.005 O8, the matrix is ​​LiGa5O8, and the percentage of the total molar amount of Ga, Cr, and Ni is calculated, among which the doping ion Cr 3+ and Ni 2+The doping amount is 10% and 0.1% respectively. According to the stoichiometric ratio of each component element, accurately weigh 1g of the mixed raw material with a molar ratio of Li2CO3:Ga2O3:Cr2O3:NiO=0.55:2.2475:0.25:0.005. Place the above 1g of mixed raw material in an agate mortar and then add 3mL of ethanol and grind for 1h. After the raw materials are fully mixed, move them to a corundum crucible, cover them, place them in a high-temperature reactor and burn them at 1600℃ for 2h, then cool them naturally to room temperature, take out the sample and grind it for 15min to obtain the green pigment LiGa 4.495 Cr 0.5 Ni 0.005 O8.

[0085] 2. Preparation of green radiative cooling films based on near-infrared light conversion materials

[0086] First, 0.45 g of polystyrene powder was added to 5 mL of toluene and stirred magnetically at room temperature to form a 90 mg / mL solution. 0.03 g of LiGa 4.495 Cr 0.5 Ni 0.005 O8 and 0.03g Al2O3 nanoparticles (particle size 10μm) were ultrasonically dispersed at room temperature using a magnetic stirrer to form a uniformly dispersed suspension, the suspension was poured into a square glass mold (depth of 300μm), the mold was transferred to a constant temperature and humidity chamber at 20℃ and 50% RH, dried for 4h, and finally peeled off from the mold to obtain a porous green radiant cooling film.

[0087] Example 6 Preparation of a green radiation cooling film based on near-infrared light conversion material

[0088] 1. Green Pigment LiGa 3.995 CrNi 0.005 Preparation of O8

[0089] Preparation of LiGa 3.995 CrNi 0.005 O8, the matrix is ​​LiGa5O8, and the percentage of the total molar amount of Ga, Cr, and Ni is calculated, among which the doping ion Cr 3+ and Ni 2+The doping amount is 20% and 0.1% respectively. According to the stoichiometric ratio of each component element, accurately weigh 1g of the mixed raw material with a molar ratio of Li2CO3:Ga2O3:Cr2O3:NiO=0.55:1.9975:0.5:0.005. Place the above 1g of mixed raw material in an agate mortar and then add 3mL of ethanol and grind for 1h. After the raw materials are fully mixed, move them to a corundum crucible, cover them, place them in a high-temperature reactor and burn them at 1600℃ for 2h, then cool them naturally to room temperature, take out the sample and grind it for 15min to obtain the green pigment LiGa 3.995 CrNi 0.005 O8.

[0090] 2. Preparation of green radiative cooling films based on near-infrared light conversion materials

[0091] First, 0.3 g of polylactic acid fiber powder was added to 5 mL of chloroform and magnetically stirred at room temperature to form a 60 mg / mL solution. 0.05 g of LiGa 3.995 CrNi 0.005 O8 and 0.05g ZrO2 nanoparticles (particle size 200nm) were ultrasonically dispersed at room temperature using a magnetic stirrer to form a uniformly dispersed suspension, the suspension was poured into a square glass mold (depth of 100μm), the mold was transferred to a constant temperature and humidity chamber at 20℃ and 40% RH, dried for 4.5h, and finally peeled off from the mold to obtain a porous green radiant cooling film.

[0092] Example 7 Preparation of a green radiation cooling film based on near-infrared light conversion material

[0093] 1. Green pigment MgGa 1.598 Cr 0.4 Ni 0.002 Preparation of O4

[0094] Preparation of MgGa 1.598 Cr 0.4 Ni 0.002 O4, the matrix is ​​MgGa2O4, and the percentage of the total molar amount of Ga, Cr, and Ni is calculated, among which the doping ion Cr 3+ and Ni 2+The doping amount is 20% and 0.1% respectively. According to the stoichiometric ratio of each component element, accurately weigh 1g of the mixed raw material with a molar ratio of MgO: Ga2O3: Cr2O3: NiO = 1: 0.799: 0.2: 0.002. Place the above 1g of mixed raw material in an agate mortar and then add 3mL of ethanol and grind for 1h. After the raw materials are fully mixed, move them to a corundum crucible, cover them, place them in a high-temperature reactor and burn them at 1600℃ for 2h, then cool them naturally to room temperature, take out the sample and grind it for 15min to obtain the green pigment MgGa 1.598 Cr 0.4 Ni 0.002 O4.

[0095] 2. Preparation of green radiative cooling films based on near-infrared light conversion materials

[0096] First, 0.15 g of polyethylene powder was added to 5 mL of chlorobenzene and stirred magnetically at room temperature to form a 30 mg / mL solution. 0.03 g of MgGa 1.598 Cr 0.4 Ni 0.002 O4 and 0.03g ZrO2 nanoparticles (particle size 5μm) were ultrasonically dispersed at room temperature using a magnetic stirrer to form a uniformly dispersed suspension, the suspension was poured into a square glass mold (depth of 500μm), the mold was transferred to a constant temperature and humidity chamber at 30℃ and 80% RH, dried for 2h, and finally peeled off from the mold to obtain a porous green radiant cooling film.

[0097] Example 8 Preparation of a green radiation cooling film based on near-infrared light conversion material

[0098] 1. Green pigment MgGa 1.798 Cr 0.2 Ni 0.002 Preparation of O4

[0099] Preparation of MgGa 1.798 Cr 0.2 Ni 0.002 O4, the matrix is ​​MgGa2O4, and the percentage of the total molar amount of Ga, Cr, and Ni is calculated, among which the doping ion Cr 3+ and Ni 2+The doping amounts are 10% and 0.1% respectively. According to the stoichiometric ratio of each component element, accurately weigh 1g of the mixed raw material with a molar ratio of MgO: Ga2O3: Cr2O3: NiO = 1: 0.899: 0.1: 0.002. Place the above 1g of mixed raw material in an agate mortar and then add 3mL of ethanol and grind for 1h. After the raw materials are fully mixed, move them to a corundum crucible, cover them, place them in a high-temperature reactor and burn them at 1600℃ for 2h, then cool them naturally to room temperature, take out the sample and grind it for 15min to obtain the green pigment MgGa 1.798 Cr 0.2 Ni 0.002 O4.

[0100] 2. Preparation of green radiative cooling films based on near-infrared light conversion materials

[0101] First, 0.45 g of polyvinylidene fluoride powder was added to 5 mL of xylene and magnetically stirred at room temperature to form a 90 mg / mL solution; 0.01 g of MgGa 1.798 Cr 0.2 Ni 0.002 O4 and 0.01g ZrO2 nanoparticles (particle size 500nm) were ultrasonically dispersed at room temperature using a magnetic stirrer to form a uniformly dispersed suspension, the suspension was poured into a square glass mold (depth of 300μm), the mold was transferred to a constant temperature and humidity chamber at 40℃ and 90% RH, dried for 3.5h, and finally peeled off from the mold to obtain a porous green radiant cooling film.

[0102] Comparative Example 1 Preparation of a porous microsphere white radiation cooling film

[0103] This comparative example is based on Example 1, and the difference between it and Example 1 is that no green pigment Mg is added. 0.79 Cr 0.2 Ni 0.01 O.

[0104] 0.45 g of polyvinyl chloride powder was added to 5 mL of carbon disulfide and magnetically stirred at room temperature to form a 90 mg / mL solution. 0.05 g of SiO2 nanoparticles (particle size 100 nm) was added to the above solution and ultrasonically dispersed with a magnetic stirrer at room temperature to form a uniformly dispersed suspension. The suspension was poured into a square glass mold (depth of 500 μm), and the mold was transferred to a constant temperature and humidity chamber at 20°C and 90% RH, dried for 0.5 h, and finally peeled off from the mold to obtain a porous white radiant cooling film.

[0105] Comparative Example 2 Preparation of a green radiation cooling film based on near-infrared light conversion material

[0106] This comparative example is set up based on Example 1, and the difference between it and Example 1 is that SiO2 inorganic microspheres are not added.

[0107] 1. Green pigment Mg 0.79 Cr 0.2 Ni 0.01 Preparation of O

[0108] Preparation of Mg 0.79 Cr 0.2 Ni 0.01 O, the matrix is ​​MgO, and the percentage of the total molar amount of Mg, Cr, and Ni, among which the doping ion Cr 3+ and Ni 2+ The doping amount is 20% and 1% respectively. According to the stoichiometric ratio of each component element, accurately weigh 1g of the mixed raw material with a molar ratio of MgO:Cr2O3:NiO=0.79:0.1:0.01. Place the above 1g of mixed raw material in an agate mortar and then add 3mL of ethanol and grind for 1h. After the raw materials are fully mixed, move them to a corundum crucible, cover them, place them in a high-temperature reactor and burn them at 1600℃ for 2h, then cool them naturally to room temperature, take out the sample and grind it for 15min to obtain the green pigment Mg 0.79 Cr 0.2 Ni 0.01 O.

[0109] 2. Preparation of green radiative cooling films based on near-infrared light conversion materials

[0110] First, 0.45 g of polyvinyl chloride powder was added to 5 mL of carbon disulfide and stirred magnetically at room temperature to form a 90 mg / mL solution. 0.05 g of Mg was added to the solution. 0.79 Cr 0.2 Ni 0.01 O, ultrasonically dispersed with a magnetic stirrer at room temperature to form a uniformly dispersed suspension, poured into a square glass mold (depth of 100 μm), transferred the mold to a constant temperature and humidity chamber at 20°C and 40% RH, dried for 4.5 h, and finally peeled off from the mold to obtain a porous green radiative cooling film.

[0111] Comparative Example 3 Preparation of a green radiation cooling film based on near-infrared light conversion material

[0112] This comparative example is based on Example 1. The difference between this comparative example and Example 1 is that Cr 3+ The molar doping amount was changed from 20% to 30%.

[0113] 1. Green pigment Mg 0.69 Cr 0.3 Ni0.01 Preparation of O

[0114] Preparation of Mg 0.69 Cr 0.3 Ni 0.01 O, the matrix is ​​MgO, and the percentage of the total molar amount of Mg, Cr, and Ni, among which the doping ion Cr 3+ and Ni 2+ The doping amount is 30% and 1% respectively. According to the stoichiometric ratio of each component element, accurately weigh 1g of the mixed raw material with a molar ratio of MgO:Cr2O3:NiO=0.69:0.15:0.01. Place the above 1g of mixed raw material in an agate mortar and then add 3mL of ethanol and grind for 1h. After the raw materials are fully mixed, move them to a corundum crucible, cover them, place them in a high-temperature reactor and burn them at 1600℃ for 2h, then cool them naturally to room temperature, take out the sample and grind it for 15min to obtain the green pigment Mg 0.69 Cr 0.3 Ni 0.01 O.

[0115] 2. Preparation of green radiative cooling films based on near-infrared light conversion materials

[0116] First, 0.45 g of polyvinyl chloride powder was added to 5 mL of carbon disulfide and stirred magnetically at room temperature to form a 90 mg / mL solution. 0.05 g of Mg was added to the solution. 0.69 Cr 0.3 Ni 0.01 O and 0.05 g SiO2 nanoparticles (particle size 100 nm) were ultrasonically dispersed at room temperature using a magnetic stirrer to form a uniformly dispersed suspension, the suspension was poured into a square glass mold (depth of 500 μm), the mold was transferred to a constant temperature and humidity chamber at 20°C and 90% RH, dried for 0.5 h, and finally peeled off from the mold to obtain a porous green radiative cooling film.

[0117] Comparative Example 4 Preparation of a green radiation cooling film based on near-infrared light conversion material

[0118] This comparative example is based on Example 1, and the difference between it and Example 1 is that Ni 2+ The molar doping amount was changed from 1% to 2%.

[0119] 1. Green pigment Mg 0.78 Cr 0.2 Ni 0.02 Preparation of O

[0120] Preparation of Mg 0.78 Cr 0.2 Ni 0.02O, the matrix is ​​MgO, and the percentage of the total molar amount of Mg, Cr, and Ni, among which the doping ion Cr 3+ and Ni 2+ The doping amount is 20% and 2% respectively. According to the stoichiometric ratio of each component element, accurately weigh 1g of the mixed raw material with a molar ratio of MgO:Cr2O3:NiO=0.78:0.1:0.02. Place the above 1g of mixed raw material in an agate mortar and then add 3mL of ethanol and grind for 1h. After the raw materials are fully mixed, move them to a corundum crucible, cover them, place them in a high-temperature reactor and burn them at 1600℃ for 2h, then cool them naturally to room temperature, take out the sample and grind it for 15min to obtain the green pigment Mg 0.78 Cr 0.2 Ni 0.02 O.

[0121] 2. Preparation of green radiative cooling films based on near-infrared light conversion materials

[0122] First, 0.45 g of polyvinyl chloride powder was added to 5 mL of carbon disulfide and stirred magnetically at room temperature to form a 90 mg / mL solution. 0.05 g of Mg was added to the solution. 0.78 Cr 0.2 Ni 0.02 O and 0.05 g SiO2 nanoparticles (particle size 100 nm) were ultrasonically dispersed at room temperature using a magnetic stirrer to form a uniformly dispersed suspension, the suspension was poured into a square glass mold (depth of 500 μm), the mold was transferred to a constant temperature and humidity chamber at 20°C and 90% RH, dried for 0.5 h, and finally peeled off from the mold to obtain a porous green radiative cooling film.

[0123] Experimental Example: Performance Measurement of Radiative Cooling Film

[0124] The cooling performance of the radiative cooling films provided in the embodiments and comparative examples was measured.

[0125] 1. Morphology

[0126] The green radiative cooling film obtained in Example 1 was photographed with a camera, and the results are as follows: Figure 1 As shown, the green near-infrared light conversion material Mg 0.79 Cr 0.2 Ni 0.01 O is evenly distributed in the polyvinyl chloride powder to obtain a homogeneous green radiative cooling film.

[0127] The green radiative cooling films obtained in Example 1 (left) and Example 3 (right) were photographed under a microscope. Figure 2As shown, it can be observed that interconnected pores are formed inside the film, and the porous structure of different sizes can capture a portion of the air. By utilizing the difference in refractive index between air and powder, the reflection and scattering of sunlight can be enhanced.

[0128] The morphology of the green films obtained in the other embodiments is basically the same as that in Embodiment 1, and will not be described again here.

[0129] 2. X-ray diffraction patterns and Raman spectra

[0130] The green radiative cooling film obtained in Example 4 was measured using a Bruker D8ADVANCE X-ray powder diffractometer. The results are as follows: Figure 3 As shown in the figure, the measured spectrum is consistent with the LiGa5O8 standard card (JCPDS 38-1371), proving that no other phases or impurities are introduced into the surface of the film sample prepared by the present application, and verifying that the present application has successfully prepared a green radiation cooling film based on near-infrared light conversion materials; in order to further verify the Cr 3+ / Ni 2+ The successful doping of Cr in Example 4 was determined by using an Agilent Cary 5000 UV-visible near-infrared spectrophotometer. 3+ The Raman spectrum of the green radiative cooling film prepared with the doping ratio of Figure 4 As shown, with Cr 3+ As the amount of Ga increases, the amount of Ga replaced in the matrix LiGa5O8 increases, which makes the relative intensity of Ga gradually decrease ( Figure 3 The dashed box part) confirms that Cr 3+ / Ni 2+ Successful doping of matrix LiGa5O8.

[0131] 3. Absorption / emission spectra

[0132] The absorbance / emissivity of Example 1 in the UV-visible-near infrared band was tested using an Agilent Cary 5000 UV-visible-near infrared spectrophotometer. The results are as follows: Figure 5 As shown, in the visible light region (380-800nm), the absorption rate of the green radiation cooling film can reach 40%-50%, which means that the film can effectively absorb this part of visible light energy; in the near-infrared region (800-1600nm), the reflectivity is as high as 95%-99%, which can reflect most of the energy of solar radiation, reduce heat absorption, and thus significantly reduce the temperature of the film.

[0133] Figure 6 Cr prepared in Example 1 and Example 3 3+ / Ni 2+ Doped green pigment Mg 0.79 Cr0.2 Ni 0.01 O and Mg 0.89 Cr 0.1 Ni 0.01 O fluorescence spectrum characteristics, as shown in the figure, under 420nm excitation, Cr 3+ / Ni 2+ The doped sample emits near-infrared light with a center at 1240nm, that is, it emits the absorbed energy at 1240nm; similarly, Figure 7 The Cr prepared in Example 4 3+ / Ni 2+ Doped green pigment LiGa 4.79 Cr 0.2 Ni 0.01 Fluorescence emission spectrum of O8, under 460nm excitation, Cr 3+ / Ni 2+ The doped sample can emit the absorbed energy at 1335nm, which shows that the film can absorb energy in the visible light region and efficiently emit the absorbed energy in the near-infrared region.

[0134] 4. Daytime temperature tracking curve

[0135] Under the condition of sunny outdoor natural light, the radiative cooling performance of the film was tested using a homemade device, which consisted of a polystyrene foam box covered with aluminum foil and a K-type thermocouple (a temperature sensor). The film was placed on top of the foam box to fully receive natural light, and the K-type thermocouple was firmly attached to the bottom of the film sample through polyimide glue. Among them, the polystyrene foam box covered with aluminum foil was used to reduce the influence of ambient heat. During the test, the specific time period of the test was recorded and the temperature change of the film was continuously monitored. After the test, the collected temperature data was processed and analyzed to evaluate the radiative cooling performance of the film. Figure 8 The following are the daytime temperature tracking curves of the green radiation cooling films prepared in Example 1 and Comparative Example 1 at 10:00-13:00. It can be seen from the figure that the maximum temperature difference between Comparative Example 1 and the environment is 6.3°C, and the average temperature difference is 2.6°C. The maximum temperature difference between Example 1 and the environment is 10.8°C, and the average temperature difference is 5.8°C. With the addition of green pigment, the maximum temperature difference between Example 1 and Comparative Example 1 can reach 6.6°C, and the average temperature difference is 4°C, indicating that after adding green pigment, the film can reflect the energy absorbed in the visible light region in the near-infrared region, achieving a passive cooling effect, and further significantly reducing the temperature of the film; Fig. 9The daytime temperature tracking curves of the films prepared in Example 1 and Comparative Example 2 from 9:30 to 15:00 show that the maximum temperature difference between Comparative Example 2 and the environment is 3.4°C, and the average temperature difference is 2.0°C. The maximum temperature difference between Example 1 and the environment is 8.1°C, and the average temperature difference is 5.1°C. With the addition of nanoparticles, the maximum temperature difference between Example 1 and Comparative Example 2 is 5.1°C, and the average temperature difference is 3.3°C; this shows that only the green radiation cooling film based on near-infrared light conversion materials prepared by combining high molecular polymers, green pigments and inorganic microspheres at the same time in the film preparation process has an excellent cooling effect. Compared with the film prepared without inorganic microspheres or green pigments, its cooling effect is inferior to the film with the synergistic effect of the three.

[0136] Fig.10 The daytime temperature tracking curves of the films prepared in Example 1 and Comparative Example 3 from 11:30 to 13:00 show that the maximum temperature difference between Comparative Example 3 and the environment is 4.0°C, and the average temperature difference is 2.1°C. The maximum temperature difference between Example 1 and the environment is 7.9°C, and the average temperature difference is 4.9°C. 3+ The maximum temperature difference between Example 1 and Comparative Example 3 is 3.9°C, and the average temperature difference is 2.2°C, indicating that the film is doped with 20% Cr. 3+ The cooling effect is better than 30% Cr 3+ ; Fig.11 The daytime temperature tracking curves of the films prepared in Example 1 and Comparative Example 4 from 10:00 to 15:30 show that the maximum temperature difference between Comparative Example 4 and the environment is 3.3°C, and the average temperature difference is 1.9°C. The maximum temperature difference between Example 1 and the environment is 7.7°C, and the average temperature difference is 5.0°C. 2+ The maximum temperature difference between Example 1 and Comparative Example 2 is 4.1°C, and the average temperature difference is 2.8°C, indicating that the film is doped with 1% Ni 2+ The cooling effect is better than 2% Ni 2+ . Comparative Examples 3 and 4 illustrate that only when the chromium-nickel doping amount of the green pigment in the green radiant cooling film satisfies the molar doping ratio of chromium of 10% to 20% and the molar doping ratio of nickel of 0.1% to 1% at the same time can a better cooling effect be achieved. Among them, the film obtained in Example 1 was subjected to a comparative experiment of daytime temperature tracking curves by the present invention with the films prepared in Comparative Examples 1, 2, 3, and 4. It is worth noting that since the experiments of these comparative examples were conducted on different dates, and the intensity of sunlight naturally varies from day to day, therefore, Figures 8 to 11 The daytime temperature tracking curves of the film of Example 1 shown in the figure show certain differences. Such differences are the natural result of the experimental conditions (i.e., different solar illumination intensities on different days), which are reasonable phenomena in the experimental process and do not affect the validity of the experimental conclusions.

[0137] In summary, Examples 1 to 8 combine high molecular weight polymer, green pigment and inorganic microspheres at the same time, and the Cr 3+ The molar doping ratio is 10% to 20% and Ni 2+ A green radiative cooling film based on near-infrared light conversion materials was successfully prepared with a molar doping ratio of 0.1% to 1%. The film exhibits excellent absorption performance in the visible light band and efficient emission in the near-infrared band, while also having excellent reflectivity in the near-infrared band. This feature significantly reduces the temperature of the surface of the object or the surrounding environment, thereby achieving efficient radiative cooling effects.

[0138] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A green radiation cooling film based on near-infrared light conversion material, characterized in that: The green radiation cooling film is mainly prepared from high molecular polymer, green pigment and inorganic microspheres; Wherein, the green pigment comprises one or more of chromium-nickel co-doped magnesium oxide, chromium-nickel co-doped lithium gallate, and chromium-nickel co-doped magnesium gallate; In the chromium-nickel co-doped magnesium oxide, the chromium doping amount is 10% to 20%, and the nickel doping amount is 0.1% to 1%, calculated as a percentage of the total molar amount of magnesium, chromium and nickel elements; In the chromium-nickel co-doped lithium gallate or chromium-nickel co-doped magnesium gallate, the chromium doping amount is 10% to 20%, and the nickel doping amount is 0.1% to 1%, calculated as a percentage of the total molar amount of gallium, chromium and nickel elements.

2. The green radiation cooling film based on near-infrared light conversion material according to claim 1, characterized in that: The green pigment includes Mg (1-x-y) Cr x Ni y O、Li(Ga (1-x-y) Cr x Ni y )5O8、Mg(Ga (1-x-y) Cr x Ni y )2O4; wherein, 0.1≤x≤0.2, 0.001≤y≤0.

01.

3. The green radiation cooling film based on near-infrared light conversion material according to claim 2, characterized in that: The green pigment includes Mg 0.79 Cr 0.2 Ni 0.01 O、Mg 0.84 Cr 0.15 Ni 0.01 O、Mg 0.89 Cr 0.1 Ni 0.01 O. LiGa 3.95 CrNi 0.05 O8、LiGa 4.495 Cr 0.5 Ni 0.005 O8、LiGa 3.995 CrNi 0.005 O8、MgGa 1.598 Cr 0.4 Ni 0.002 O4、MgGa 1.798 Cr 0.2 Ni 0.002 One or more of O4.

4. The green radiation cooling film based on near-infrared light conversion material according to claim 1, characterized in that: The high molecular polymer includes one or more of polylactic acid fiber, polydimethylsiloxane, polystyrene, polyvinyl chloride, polyethylene, and polyvinylidene fluoride.

5. The green radiation cooling film based on near-infrared light conversion material according to claim 1, characterized in that: The inorganic microspheres include one or more of titanium dioxide, magnesium oxide, silicon dioxide, aluminum oxide, zirconium dioxide, and barium sulfate.

6. The green radiation cooling film based on near-infrared light conversion material according to claim 1, characterized in that: The mass ratio of the high molecular polymer, the green pigment and the inorganic microspheres is 1:(0.02-0.5):(0.02-0.5).

7. The method for preparing a green radiation cooling film based on near-infrared light conversion material according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1. Mixing a polymer, a green pigment and inorganic microspheres in an organic solvent to obtain a suspension; S2. The suspension obtained in step S1 is coated on a substrate, and a thin film is formed on the substrate after drying, and the thin film is peeled off to obtain a green radiation cooling film based on near-infrared light conversion material.

8. The preparation method according to claim 7, characterized in that: In step S1, the organic solvent includes one or more of formic acid, tetrahydrofuran, carbon disulfide, dichloromethane, chloroform, and toluene.

9. The preparation method according to claim 7, characterized in that: In step S1, the mass volume ratio of the high molecular polymer to the organic solvent is 1g:(0.01-0.05)L.

10. Use of the green radiation cooling film based on near-infrared light conversion material according to any one of claims 1 to 6 in the preparation of cooling materials.

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