A fireproof and aging-resistant high-reflection aluminum-plastic composite film, its preparation method, and its application in improving the power generation efficiency of the back side of a photovoltaic cell

Abstract

The present invention relates to a fireproof and aging-resistant highly reflective aluminum-plastic composite film, a preparation method thereof, and an application in improving the power generation efficiency of the back side of a photovoltaic cell, belonging to the technical field of photovoltaic materials. The fireproof and aging-resistant highly reflective aluminum-plastic composite film of the present invention comprises a transparent protective layer, a vacuum aluminized polypropylene film, and a polyethylene substrate that are sequentially laminated. It has fireproof and aging-resistant properties, and at the same time has good tensile strength, elongation rate, and light reflection performance. When the highly reflective aluminum-plastic composite film of the present invention is laid on the ground of a photovoltaic power plant, it can reflect the sunlight irradiated on the ground to the back side of the photovoltaic module through the gaps between the modules, enabling the back side of the double-sided double-glass photovoltaic module to generate electricity, with the power generation efficiency increased by 20% - 30%. Moreover, the composite film simultaneously plays the roles of weed prevention, dust prevention, and erosion prevention, solving the problems of weeds, dust, and soil erosion on the ground of the photovoltaic power plant.

Description

Technical Field

[0001] The present invention relates to a fireproof and aging-resistant highly reflective aluminum-plastic composite film, a preparation method thereof, and an application in improving the power generation efficiency of the back side of a photovoltaic cell, belonging to the technical field of photovoltaic materials. Background Art

[0002] Solar power generation is mainly divided into two categories: photovoltaic power generation and solar thermal power generation. Photovoltaic power generation utilizes the photovoltaic effect of semiconductor materials to directly convert sunlight into electrical energy. Photovoltaic power generation technology is applicable to distributed power generation, such as a home rooftop photovoltaic system, and also applicable to large-scale centralized power generation, such as a large-scale ground photovoltaic power station. A photovoltaic power station is a photovoltaic power generation system connected to the power grid and transmitting power to the power grid. Photovoltaic power stations can be divided into grid-connected power generation systems with and without batteries. Solar power generation is divided into solar thermal power generation and photovoltaic power generation. Generally, solar power generation refers to solar photovoltaic power generation. The most basic component of solar photovoltaic power generation is a solar cell (chip), including monocrystalline silicon, polycrystalline silicon, amorphous silicon, and thin-film batteries, etc.

[0003] At present, most photovoltaic power stations adopt double-sided double-glass photovoltaic modules, but they can only generate electricity on the sunny side. The power generation efficiency of the back side is the same as that of the front side. Since there is no reflected light, the power generation efficiency of the back side approaches 0. Therefore, in order to improve the power generation efficiency of the back side of the double-sided double-glass photovoltaic module, there is an urgent need to provide a highly reflective aluminum-plastic composite film suitable for power generation on the back side of a photovoltaic cell. Summary of the Invention

[0004] The purpose of the present invention is to provide a fireproof and aging-resistant highly reflective aluminum-plastic composite film, a preparation method thereof, and an application in improving the power generation efficiency of the back side of a photovoltaic cell, so as to solve the problem of low power generation efficiency of the back side of the current double-sided double-glass photovoltaic module.

[0005] The technical solution of the fireproof and aging-resistant highly reflective aluminum-plastic composite film of the present invention is as follows:

[0006] A fireproof and aging-resistant high-reflection aluminum-plastic composite film, comprising a transparent protective layer, a vacuum aluminized polypropylene film, and a polyethylene substrate that are sequentially laminated. The vacuum aluminized polypropylene film is laminated with the transparent protective layer through a vacuum aluminized layer; the transparent protective layer is formed by curing an aqueous polyurethane coating; the aqueous polyurethane coating is composed of an aqueous acrylate emulsion and an aqueous isocyanate curing agent. The preparation method of the aqueous acrylate emulsion is as follows: A functional polyol, water, and a first monomer mixture are mixed and reacted, and then mixed and reacted with a second monomer mixture to obtain the aqueous acrylate emulsion; the first monomer mixture is composed of a first mixed monomer and an initiator, and the first mixed monomer is composed of methyl methacrylate, butyl acrylate, isooctyl acrylate, acrylic acid, and hydroxypropyl acrylate with a mass ratio of 25-30:8-10:5-7:4-6:5-8; the second monomer mixture is composed of a second mixed monomer and an initiator, and the second mixed monomer is composed of methyl acrylate, butyl acrylate, hexyl acrylate, acrylic acid, and hydroxyethyl acrylate with a mass ratio of 23-25:5-7:8-10:4-8:5-7; the mass ratio of the functional polyol, the first monomer mixture, and the second monomer mixture is 8:10-12:75-85; the structure of the functional polyol is as follows:

[0007] 。

[0008] Preferably, the thickness of the polyethylene substrate is 0.3-0.4 mm, the thickness of the vacuum aluminized polypropylene film is 0.03-0.05 mm, and the thickness of the transparent protective layer is 20-35 μm.

[0009] Preferably, the first monomer mixture is composed of methyl methacrylate, butyl acrylate, isooctyl acrylate, acrylic acid, hydroxypropyl acrylate, and potassium persulfate with a mass ratio of 25-30:8-10:5-7:4-6:5-8:0.1-0.15.

[0010] Preferably, the second monomer mixture is composed of methyl acrylate, butyl acrylate, hexyl acrylate, acrylic acid, hydroxyethyl acrylate, and potassium persulfate with a mass ratio of 23-25:5-7:8-10:4-8:5-7:0.1-0.15.

[0011] Preferably, the preparation method of the functional polyol is as follows:

[0012] (1) 1,4-Cyclohexanediamine and 1,1,1-trifluoro-2,3-epoxypropane are mixed and reacted at a temperature of 40-50 °C for 18-24 h to obtain a fluorinated diol; the molar ratio of 1,4-cyclohexanediamine to 1,1,1-trifluoro-2,3-epoxypropane is 1:2;

[0013] (2) Mix the fluorinated diol and 4-bromo-1,2-epoxybutane at a temperature of 45 - 50 °C and react for 24 - 30 h to obtain brominated fluorinated polyol; the molar ratio of the fluorinated diol to 4-bromo-1,2-epoxybutane is 1:2;

[0014] (3) Mix the brominated fluorinated polyol and 2,6-dimethylpiperidine at a temperature of 60 - 65 °C and react for 24 - 30 h to obtain piperidine-modified fluorinated polyol; the molar ratio of the brominated fluorinated polyol to 2,6-dimethylpiperidine is 1:2;

[0015] (4) Mix the piperidine-modified fluorinated polyol and (3-bromopropyl)phosphoric acid at a temperature of 75 - 80 °C and react for 24 - 30 h to obtain functional polyol; the molar ratio of the piperidine-modified fluorinated polyol to (3-bromopropyl)phosphoric acid is 1:4.5 - 5.

[0016] Preferably, the temperature for the mixing reaction of the functional polyol, water and the first monomer mixture is 65 - 75 °C, and the time is 30 - 50 min.

[0017] Preferably, the time for the mixing reaction with the second monomer mixture is 5 - 6 h.

[0018] The technical solution of the preparation method of the fireproof and aging-resistant highly reflective aluminum-plastic composite film of the present invention is as follows:

[0019] A preparation method of a fireproof and aging-resistant highly reflective aluminum-plastic composite film as described above, comprising the following steps: Composite a vacuum aluminized polypropylene film and a polyethylene film to obtain a composite layer; then coat a waterborne polyurethane coating on the aluminized layer surface of the composite layer, and cure to obtain a fireproof and aging-resistant highly reflective aluminum-plastic composite film.

[0020] Preferably, the curing temperature is 60 - 70 °C and the time is 24 - 48 h.

[0021] The technical solution of the application of the fireproof and aging-resistant highly reflective aluminum-plastic composite film of the present invention in improving the backside power generation efficiency of a photovoltaic is as follows:

[0022] An application of a fireproof and aging-resistant highly reflective aluminum-plastic composite film as described above in improving the backside power generation efficiency of a photovoltaic.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows: By synthesizing a polyol with hydrophobic fluorine atoms, bulky piperidine groups, phosphoric acid branches, hydrophilic quaternary ammonium salts, and polyhydroxy structures, and using the synthesized polyol to prepare an aqueous acrylate emulsion, not only can the surfactant function be exerted, but also the various functional structural groups in the polyol cooperate with each other and jointly play a role, effectively improving the adhesion to the aluminum layer, as well as the weather resistance, self-cleaning performance, and transparency of the coating. Among them, the hydrophobic fluorine atoms can improve the wetting performance of the aqueous acrylate emulsion on the substrate and the water-proof and oil-loving properties of the coating; the bulky piperidine groups have anti-radiation and ultraviolet light resistance properties; the acidic phosphoric acid branches can slightly corrode the metal aluminum and improve the adhesion and bonding strength; the hydrophilic quaternary ammonium salts and polyhydroxy structures can improve the affinity and compatibility of the polyol with the aqueous acrylate emulsion, and can also improve the wetting and dispersibility of the polyurethane coating, thereby improving the adhesion strength to the substrate.

[0024] The high-reflection aluminum-plastic composite film of the present invention simultaneously has good adhesion performance, heat and weather resistance, self-cleaning performance, and a relatively high reflectivity, and has the functions of preventing weeds, dust, and erosion. It can be applied not only to photovoltaic power stations but also to engineering fields that require reflecting sunlight and heat radiation, such as landfills, reservoir liners, roof insulation, etc. All materials in the high-reflection aluminum-plastic composite film of the present invention can be recycled, and the production process is environmentally friendly, which can effectively reduce the emission of waste materials and harmful substances. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is the nuclear magnetic hydrogen spectrum diagram of the functional polyol prepared in Example 1 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0026] The following examples are intended to further illustrate the content of the present invention rather than limit the protection scope of the present invention.

[0027] Specific examples of the fireproof and aging-resistant high-reflection aluminum-plastic composite film of the present invention and its preparation method are as follows:

[0028] Example 1. The fireproof and aging-resistant highly reflective aluminum-plastic composite film in this example includes a transparent protective layer, a vacuum aluminized polypropylene film (the vacuum aluminized polypropylene film includes a vacuum aluminized layer and a polypropylene substrate), and a polyethylene substrate, which are laminated in sequence from top to bottom; the thickness of the polyethylene substrate is 0.3 mm, and the polyethylene substrate is high-density polyethylene (HDPE), which has good mechanical properties, chemical corrosion resistance, and durability; the thickness of the vacuum aluminized polypropylene film is 0.03 mm, and the aluminum layer in the vacuum aluminized polypropylene film has a high reflectivity, which can effectively reflect sunlight and heat radiation; the thickness of the transparent protective layer is 20 μm, and the transparent protective layer is a polyurethane coating, which is formed by curing an aqueous polyurethane coating, and can better protect the aluminum layer and improve the durability and anti-pollution ability of the aluminum reflective layer. The vacuum aluminized polypropylene film is laminated with the transparent protective layer through the vacuum aluminized layer.

[0029] Among them, the preparation method of the aqueous polyurethane coating is as follows:

[0030] (1) Add 1,4-cyclohexanediamine, 1,1,1-trifluoro-2,3-epoxypropane, and acetone into a reaction kettle, stir evenly, heat to 40 °C, stir and react for 18 h, carry out vacuum distillation to remove the solvent, obtain a concentrate, and subject the concentrate to column chromatography purification to obtain a fluorinated diol; among them, the molar ratio of 1,4-cyclohexanediamine to 1,1,1-trifluoro-2,3-epoxypropane is 1:2, the mass ratio of 1,1,1-trifluoro-2,3-epoxypropane to acetone is 1:1.2, and the eluent used for column chromatography purification is composed of petroleum ether, ethyl acetate, and dichloromethane with a volume ratio of 15:1:1. The structure of the fluorinated diol is as follows:

[0031] .

[0032] (2) Add the fluorinated diol, 4-bromo-1,2-epoxybutane, and acetone into a reaction kettle, stir evenly, heat to 45 °C, stir and reflux for 24 h, carry out vacuum distillation to remove the solvent, obtain a concentrate, and subject the concentrate to column chromatography purification to obtain a brominated fluorinated polyol; among them, the molar ratio of the fluorinated diol to 4-bromo-1,2-epoxybutane is 1:2, the mass ratio of 4-bromo-1,2-epoxybutane to acetone is 1:1, and the eluent used for column chromatography purification is composed of petroleum ether, ethyl acetate, and methanol with a volume ratio of 15:1:1. The structure of the brominated fluorinated polyol is as follows:

[0033] .

[0034] (3) Add brominated fluorinated polyol, 2,6-dimethylpiperidine and acetone into a reaction kettle. After stirring evenly, heat to 60 °C and stir and reflux for 24 h. Distill off the solvent under reduced pressure to obtain a concentrate. Subject the concentrate to column chromatography purification to obtain piperidine-modified fluorinated polyol. Among them, the molar ratio of brominated fluorinated polyol to 2,6-dimethylpiperidine is 1:2, the mass ratio of 2,6-dimethylpiperidine to acetone is 1:1.5, and the eluent used for column chromatography purification is composed of petroleum ether, ethyl acetate and methanol with a volume ratio of 15:1:1. The structure of the piperidine-modified fluorinated polyol is as follows:

[0035] 。

[0036] (4) Add piperidine-modified fluorinated polyol, (3-bromopropyl)phosphoric acid and acetone into a reaction kettle. After stirring evenly, heat to 75 °C and stir and reflux for 24 h. Distill off the solvent under reduced pressure to obtain a concentrate. Subject the concentrate to column chromatography purification to obtain functional polyol. Among them, the molar ratio of piperidine-modified fluorinated polyol to (3-bromopropyl)phosphoric acid is 1:4.5, the mass ratio of (3-bromopropyl)phosphoric acid to acetone is 1:1.5, and the eluent used for column chromatography purification is composed of petroleum ether, ethyl acetate and methanol with a volume ratio of 15:1:1.5. The 1H NMR spectrum of the functional polyol is as Figure 1 shown, and the chemical structure is as follows:

[0037] 。

[0038] (5) Add functional polyol and water with a mass ratio of 1:8 into a reaction kettle, stir evenly to obtain a mixture. Then control the temperature of the materials in the reaction kettle at 65 °C, and dropwise add the first monomer mixture into the reaction kettle under stirring conditions. After the dropping is completed, continue to stir and react for 30 min, then dropwise add the second monomer mixture into the reaction kettle, continue to stir and react for 5 h, cool down to 35 °C, and add ammonia water into the reaction kettle to adjust the pH of the materials in the reaction kettle to 7 to obtain an aqueous acrylate emulsion. Among them, the first monomer mixture is composed of methyl methacrylate, butyl acrylate, isooctyl acrylate, acrylic acid, hydroxypropyl acrylate and potassium persulfate with a mass ratio of 25:8:5:4:5:0.1; the second monomer mixture is composed of methyl acrylate, butyl acrylate, hexyl acrylate, acrylic acid, hydroxyethyl acrylate and potassium persulfate with a mass ratio of 23:5:8:4:5:0.1; the mass ratio of functional polyol, the first monomer mixture and the second monomer mixture is 8:10:75.

[0039] (6) Stir the aqueous acrylate emulsion and the aqueous isocyanate curing agent (Covestro Bayhydur XP2487) evenly to obtain an aqueous polyurethane coating; the molar ratio of the isocyanate group in the aqueous isocyanate curing agent to the hydroxyl group in the aqueous acrylate emulsion is 1.1:1.

[0040] The preparation method of the fireproof and aging-resistant highly reflective aluminum-plastic composite film in this embodiment is as follows: Coat glue between the vacuum aluminized polypropylene film and the polyethylene film, and then use a dry laminator for lamination to obtain a composite layer; then spin-coat a waterborne polyurethane coating on the aluminized layer surface of the composite layer, and cure it at 60°C for 48 hours to form a transparent protective layer, thus obtaining the fireproof and aging-resistant highly reflective aluminum-plastic composite film.

[0041] Example 2, the fireproof and aging-resistant highly reflective aluminum-plastic composite film in this embodiment includes a transparent protective layer, a vacuum aluminized polypropylene film (the vacuum aluminized polypropylene film includes a vacuum aluminized layer and a polypropylene substrate), and a polyethylene substrate that are laminated in sequence from top to bottom. The thickness of the polyethylene substrate is 0.3 mm, the thickness of the vacuum aluminized polypropylene film is 0.04 mm, and the thickness of the transparent protective layer is 30 μm; the transparent protective layer is a polyurethane coating formed by curing the waterborne polyurethane coating. The vacuum aluminized polypropylene film is laminated with the transparent protective layer through the vacuum aluminized layer.

[0042] Among them, the preparation method of the waterborne polyurethane coating is as follows:

[0043] (1) Add 1,4-cyclohexanediamine, 1,1,1-trifluoro-2,3-epoxypropane, and acetone to a reaction kettle, stir evenly, heat to 45°C, stir and react for 20 hours, perform vacuum distillation to remove the solvent, obtain a concentrate, and subject the concentrate to column chromatography purification to obtain a fluorinated diol; among them, the molar ratio of 1,4-cyclohexanediamine to 1,1,1-trifluoro-2,3-epoxypropane is 1:2, the mass ratio of 1,1,1-trifluoro-2,3-epoxypropane to acetone is 1:1.3, and the eluent used for column chromatography purification is composed of petroleum ether, ethyl acetate, and dichloromethane with a volume ratio of 15:1:1. The structure of the fluorinated diol is as follows:

[0044] .

[0045] (2) Add the fluorinated diol, 4-bromo-1,2-epoxybutane, and acetone to a reaction kettle, stir evenly, heat to 48°C, stir and reflux for 26 hours, perform vacuum distillation to remove the solvent, obtain a concentrate, and subject the concentrate to column chromatography purification to obtain a brominated fluorinated polyol; among them, the molar ratio of the fluorinated diol to 4-bromo-1,2-epoxybutane is 1:2, the mass ratio of 4-bromo-1,2-epoxybutane to acetone is 1:1.2, and the eluent used for column chromatography purification is composed of petroleum ether, ethyl acetate, and methanol with a volume ratio of 15:1:1. The structure of the brominated fluorinated polyol is as follows:

[0046] .

[0047] (3) Add brominated fluorinated polyol, 2,6-dimethylpiperidine, and acetone into a reaction kettle. After stirring evenly, heat to 63 °C and stir under reflux for 27 h. Remove the solvent by vacuum distillation to obtain a concentrate. Purify the concentrate by column chromatography to obtain piperidine-modified fluorinated polyol. Among them, the molar ratio of brominated fluorinated polyol to 2,6-dimethylpiperidine is 1:2, the mass ratio of 2,6-dimethylpiperidine to acetone is 1:1.8, and the eluent used for column chromatography purification is composed of petroleum ether, ethyl acetate, and methanol with a volume ratio of 15:1:1. The structure of piperidine-modified fluorinated polyol is as follows:

[0048] .

[0049] (4) Add piperidine-modified fluorinated polyol, (3-bromopropyl)phosphoric acid, and acetone into a reaction kettle. After stirring evenly, heat to 78 °C and stir under reflux for 27 h. Remove the solvent by vacuum distillation to obtain a concentrate. Purify the concentrate by column chromatography to obtain functional polyol. Among them, the molar ratio of piperidine-modified fluorinated polyol to (3-bromopropyl)phosphoric acid is 1:4.7, the mass ratio of (3-bromopropyl)phosphoric acid to acetone is 1:1.8, and the eluent used for column chromatography purification is composed of petroleum ether, ethyl acetate, and methanol with a volume ratio of 15:1:1.5. The structure of functional polyol is as follows:

[0050] .

[0051] (5) Add functional polyol and water with a mass ratio of 1:9 into a reaction kettle and stir evenly to obtain a mixed solution. Then control the temperature of the materials in the reaction kettle at 70 °C. Under stirring conditions, dropwise add the first monomer mixture into the reaction kettle. After the dropping is completed, continue to stir and react for 40 min. Then dropwise add the second monomer mixture into the reaction kettle and continue to stir and react for 6 h. Cool down to 37 °C, add ammonia water into the reaction kettle, and adjust the pH of the materials in the reaction kettle to 7 to obtain an aqueous acrylate emulsion. Among them, the first monomer mixture is composed of methyl methacrylate, butyl acrylate, isooctyl acrylate, acrylic acid, hydroxypropyl acrylate, and potassium persulfate with a mass ratio of 27:9:6:5:7:0.12; the second monomer mixture is composed of methyl acrylate, butyl acrylate, hexyl acrylate, acrylic acid, hydroxyethyl acrylate, and potassium persulfate with a mass ratio of 24:6:9:6:6:0.13; the mass ratio of functional polyol, the first monomer mixture, and the second monomer mixture is 8:10:80.

[0052] (6) Stir the aqueous acrylate emulsion and the aqueous isocyanate curing agent (Covestro Bayhydur XP2487) evenly to obtain an aqueous polyurethane coating; the molar ratio of the isocyanate group in the aqueous isocyanate curing agent to the hydroxyl group in the aqueous acrylate emulsion is 1.2:1.

[0053] The preparation method of the fireproof and aging-resistant high-reflection aluminum-plastic composite film in this embodiment is as follows: Apply glue between the vacuum aluminized polypropylene film and the polyethylene film, and then use a dry laminator for lamination to obtain a composite layer; then spin-coat a waterborne polyurethane coating on the aluminized layer surface of the composite layer, and cure it at 65 °C for 48 h to form a transparent protective layer, thus obtaining the fireproof and aging-resistant high-reflection aluminum-plastic composite film.

[0054] Example 3. The fireproof and aging-resistant high-reflection aluminum-plastic composite film in this embodiment includes a transparent protective layer, a vacuum aluminized polypropylene film (the vacuum aluminized polypropylene film includes a vacuum aluminized layer and a polypropylene substrate), and a polyethylene substrate that are laminated in sequence from top to bottom. The thickness of the polyethylene substrate is 0.4 mm, the thickness of the vacuum aluminized polypropylene film is 0.05 mm, and the thickness of the transparent protective layer is 35 μm; the transparent protective layer is a polyurethane coating formed by curing a waterborne polyurethane coating. The vacuum aluminized polypropylene film is laminated with the transparent protective layer through the vacuum aluminized layer.

[0055] Among them, the preparation method of the waterborne polyurethane coating is as follows:

[0056] (1) Add 1,4-cyclohexanediamine, 1,1,1-trifluoro-2,3-epoxypropane, and acetone to a reaction kettle, stir evenly, heat to 50 °C, stir and react for 24 h, perform vacuum distillation to remove the solvent, obtain a concentrate, and subject the concentrate to column chromatography purification to obtain a fluorinated diol; among them, the molar ratio of 1,4-cyclohexanediamine to 1,1,1-trifluoro-2,3-epoxypropane is 1:2, the mass ratio of 1,1,1-trifluoro-2,3-epoxypropane to acetone is 1:1.5, and the eluent used for column chromatography purification is composed of petroleum ether, ethyl acetate, and dichloromethane with a volume ratio of 15:1:1. The structure of the fluorinated diol is as follows:

[0057] .

[0058] (2) Add the fluorinated diol, 4-bromo-1,2-epoxybutane, and acetone to a reaction kettle, stir evenly, heat to 50 °C, stir and reflux for 30 h, perform vacuum distillation to remove the solvent, obtain a concentrate, and subject the concentrate to column chromatography purification to obtain a brominated fluorinated polyol; among them, the molar ratio of the fluorinated diol to 4-bromo-1,2-epoxybutane is 1:2, the mass ratio of 4-bromo-1,2-epoxybutane to acetone is 1:1.3, and the eluent used for column chromatography purification is composed of petroleum ether, ethyl acetate, and methanol with a volume ratio of 15:1:1. The structure of the brominated fluorinated polyol is as follows:

[0059] .

[0060] (3) Add brominated fluorinated polyol, 2,6-dimethylpiperidine and acetone into the reaction kettle. After stirring evenly, heat to 65 °C and stir under reflux for 30 h. Distill off the solvent under reduced pressure to obtain a concentrate. Purify the concentrate by column chromatography to obtain piperidine-modified fluorinated polyol. Among them, the molar ratio of brominated fluorinated polyol to 2,6-dimethylpiperidine is 1:2, the mass ratio of 2,6-dimethylpiperidine to acetone is 1:2, and the eluent used for column chromatography purification is composed of petroleum ether, ethyl acetate and methanol with a volume ratio of 15:1:1. The structure of piperidine-modified fluorinated polyol is as follows:

[0061] .

[0062] (4) Add piperidine-modified fluorinated polyol, (3-bromopropyl)phosphoric acid and acetone into the reaction kettle. After stirring evenly, heat to 80 °C and stir under reflux for 30 h. Distill off the solvent under reduced pressure to obtain a concentrate. Purify the concentrate by column chromatography to obtain functional polyol. Among them, the molar ratio of piperidine-modified fluorinated polyol to (3-bromopropyl)phosphoric acid is 1:5, the mass ratio of (3-bromopropyl)phosphoric acid to acetone is 1:2, and the eluent used for column chromatography purification is composed of petroleum ether, ethyl acetate and methanol with a volume ratio of 15:1:1.5. The structure of functional polyol is as follows:

[0063] .

[0064] (5) Add functional polyol and water with a mass ratio of 1:10 into the reaction kettle and stir evenly to obtain a mixed solution. Then control the temperature of the materials in the reaction kettle at 75 °C. Under stirring conditions, dropwise add the first monomer mixture into the reaction kettle. After the dropping is completed, continue to stir and react for 50 min. Then dropwise add the second monomer mixture into the reaction kettle and continue to stir and react for 6 h. Cool down to 40 °C and add ammonia water into the reaction kettle to adjust the pH of the materials in the reaction kettle to 7.5 to obtain an aqueous acrylate emulsion. Among them, the first monomer mixture is composed of methyl methacrylate, butyl acrylate, isooctyl acrylate, acrylic acid, hydroxypropyl acrylate and potassium persulfate with a mass ratio of 30:10:7:6:8:0.15; the second monomer mixture is composed of methyl acrylate, butyl acrylate, hexyl acrylate, acrylic acid, hydroxyethyl acrylate and potassium persulfate with a mass ratio of 25:7:10:8:7:0.15; the mass ratio of functional polyol, the first monomer mixture and the second monomer mixture is 8:10:85.

[0065] (6) Stir the aqueous acrylate emulsion and the aqueous isocyanate curing agent (Covestro Bayhydur XP2487) evenly to obtain an aqueous polyurethane coating; the molar ratio of the isocyanate group in the aqueous isocyanate curing agent to the hydroxyl group in the aqueous acrylate emulsion is 1.3:1.

[0066] The preparation method of the fireproof and aging-resistant high-reflection aluminum-plastic composite film in this embodiment is as follows: Apply glue between the vacuum aluminized polypropylene film and the polyethylene film, and then use a dry laminator for lamination to obtain a composite layer; then spin-coat a waterborne polyurethane coating on the aluminized layer surface of the composite layer, and cure it at 70 °C for 48 h to form a transparent protective layer, thus obtaining the fireproof and aging-resistant high-reflection aluminum-plastic composite film.

[0067] Comparative Example 1

[0068] The difference between the fireproof and aging-resistant high-reflection aluminum-plastic composite film in this comparative example and the fireproof and aging-resistant high-reflection aluminum-plastic composite film in Example 1 is only that the preparation method of the waterborne polyurethane coating used to prepare the transparent protective layer in the fireproof and aging-resistant high-reflection aluminum-plastic composite film of this comparative example is as follows:

[0069] (1) Add 1,4-cyclohexanediamine, 1,1,1-trifluoro-2,3-epoxypropane and acetone into a reaction kettle, stir evenly, heat to 40 °C, stir and react for 18 h, carry out vacuum distillation to remove the solvent, obtain a concentrate, and carry out column chromatography purification on the concentrate to obtain fluorinated diol; among them, the molar ratio of 1,4-cyclohexanediamine to 1,1,1-trifluoro-2,3-epoxypropane is 1:2, the mass ratio of 1,1,1-trifluoro-2,3-epoxypropane to acetone is 1:1.2, and the eluent used for column chromatography purification is composed of petroleum ether, ethyl acetate and dichloromethane with a volume ratio of 15:1:1. The structure of the fluorinated diol is as follows:

[0070] 。

[0071] (2) Add the fluorinated diol, 4-bromo-1,2-epoxybutane and acetone into a reaction kettle, stir evenly, heat to 45 °C, stir and reflux for 24 h, carry out vacuum distillation to remove the solvent, obtain a concentrate, and carry out column chromatography purification on the concentrate to obtain brominated fluorinated polyol; among them, the molar ratio of the fluorinated diol to 4-bromo-1,2-epoxybutane is 1:2, the mass ratio of 4-bromo-1,2-epoxybutane to acetone is 1:1, and the eluent used for column chromatography purification is composed of petroleum ether, ethyl acetate and methanol with a volume ratio of 15:1:1. The structure of the brominated fluorinated polyol is as follows:

[0072] 。

[0073] (3) Add brominated fluorinated polyol, 2,6-dimethylpiperidine and acetone into a reaction kettle. After stirring evenly, heat to 60 °C and stir and reflux for 24 h. Remove the solvent by distillation under reduced pressure to obtain a concentrate. Purify the concentrate by column chromatography to obtain piperidine-modified fluorinated polyol. Among them, the molar ratio of brominated fluorinated polyol to 2,6-dimethylpiperidine is 1:2, the mass ratio of 2,6-dimethylpiperidine to acetone is 1:1.5, and the eluent used for column chromatography purification is composed of petroleum ether, ethyl acetate and methanol with a volume ratio of 15:1:1. The structure of piperidine-modified fluorinated polyol is as follows:

[0074] .

[0075] (4) Add piperidine-modified fluorinated polyol and water with a mass ratio of 1:8 into a reaction kettle, stir evenly to obtain a mixed solution, then control the temperature of the materials in the reaction kettle at 65 °C, and dropwise add the first monomer mixture into the reaction kettle under stirring conditions. After the dropping is completed, continue to stir and react for 30 min, then dropwise add the second monomer mixture into the reaction kettle, continue to stir and react for 5 h, cool down to 35 °C, add ammonia water into the reaction kettle, and adjust the pH of the materials in the reaction kettle to 7 to obtain an aqueous acrylate emulsion. Among them, the first monomer mixture is composed of methyl methacrylate, butyl acrylate, isooctyl acrylate, acrylic acid, hydroxypropyl acrylate and potassium persulfate with a mass ratio of 25:8:5:4:5:0.1; the second monomer mixture is composed of methyl acrylate, butyl acrylate, hexyl acrylate, acrylic acid, hydroxyethyl acrylate and potassium persulfate with a mass ratio of 2:3:5:8:4:5:0.1; the mass ratio of piperidine-modified fluorinated polyol, the first monomer mixture and the second monomer mixture is 8:10:75.

[0076] (5) Stir the aqueous acrylate emulsion and the aqueous isocyanate curing agent (Covestro Bayhydur XP2487) evenly to obtain an aqueous polyurethane coating; the molar ratio of the isocyanate group in the aqueous isocyanate curing agent to the hydroxyl group in the aqueous acrylate emulsion is 1.1:1.

[0077] Comparative Example 2

[0078] The difference between the fireproof and aging-resistant highly reflective aluminum-plastic composite film of this comparative example and the fireproof and aging-resistant highly reflective aluminum-plastic composite film of Example 1 is only that the preparation method of the aqueous polyurethane coating used to prepare the transparent protective layer in the fireproof and aging-resistant highly reflective aluminum-plastic composite film of this comparative example is as follows:

[0079] (1) Add 1,4 - cyclohexanediamine, 1,1,1 - trifluoro - 2,3 - epoxypropane and acetone into a reaction kettle. After stirring evenly, heat to 40 °C and stir - react for 18 h. Then perform vacuum distillation to remove the solvent to obtain a concentrate. Purify the concentrate by column chromatography to obtain a fluorinated diol. Among them, the molar ratio of 1,4 - cyclohexanediamine to 1,1,1 - trifluoro - 2,3 - epoxypropane is 1:2, and the mass ratio of 1,1,1 - trifluoro - 2,3 - epoxypropane to acetone is 1:1.2. The eluent used for column chromatography purification is composed of petroleum ether, ethyl acetate and dichloromethane with a volume ratio of 15:1:1. The structure of the fluorinated diol is as follows:

[0080] .

[0081] (2) Add the fluorinated diol, 4 - bromo - 1,2 - epoxybutane and acetone into a reaction kettle. After stirring evenly, heat to 45 °C and stir - reflux react for 24 h. Then perform vacuum distillation to remove the solvent to obtain a concentrate. Purify the concentrate by column chromatography to obtain a brominated fluorinated polyol. Among them, the molar ratio of the fluorinated diol to 4 - bromo - 1,2 - epoxybutane is 1:2, and the mass ratio of 4 - bromo - 1,2 - epoxybutane to acetone is 1:1. The eluent used for column chromatography purification is composed of petroleum ether, ethyl acetate and methanol with a volume ratio of 15:1:1. The structure of the brominated fluorinated polyol is as follows:

[0082] .

[0083] (3) Add the brominated fluorinated polyol, 2,6 - dimethylpiperidine and acetone into a reaction kettle. After stirring evenly, heat to 60 °C and stir - reflux react for 24 h. Remove the solvent by vacuum distillation to obtain a concentrate. Purify the concentrate by column chromatography to obtain a piperidine - modified fluorinated polyol. Among them, the molar ratio of the brominated fluorinated polyol to 2,6 - dimethylpiperidine is 1:2, and the mass ratio of 2,6 - dimethylpiperidine to acetone is 1:1.5. The eluent used for column chromatography purification is composed of petroleum ether, ethyl acetate and methanol with a volume ratio of 15:1:1. The structure of the piperidine - modified fluorinated polyol is as follows:

[0084] .

[0085] (4) Add piperidine-modified fluorinated polyol, water, and hydroxyethylidene diphosphonic acid with a mass ratio of 1:8 into a reaction kettle, stir evenly to obtain a mixed solution, then control the temperature of the materials in the reaction kettle at 65 °C, and dropwise add the first monomer mixture into the reaction kettle under stirring conditions. After the dropping is completed, continue stirring and reacting for 30 min, then dropwise add the second monomer mixture into the reaction kettle, and continue stirring and reacting for 5 h. Cool down to 35 °C, add ammonia water into the reaction kettle, and adjust the pH of the materials in the reaction kettle to 7 to obtain an aqueous acrylate emulsion; wherein, the first monomer mixture is composed of methyl methacrylate, butyl acrylate, isooctyl acrylate, acrylic acid, hydroxypropyl acrylate, and potassium persulfate with a mass ratio of 25:8:5:4:5:0.1; the second monomer mixture is composed of methyl acrylate, butyl acrylate, hexyl acrylate, acrylic acid, hydroxyethyl acrylate, and potassium persulfate with a mass ratio of 23:5:8:4:5:0.1; the mass ratio of the piperidine-modified fluorinated polyol, the first monomer mixture, and the second monomer mixture is 8:10:75, and the molar ratio of hydroxyethylidene diphosphonic acid to the piperidine-modified fluorinated polyol is 2:1.

[0086] (5) Stir the aqueous acrylate emulsion and the aqueous isocyanate curing agent (Covestro Bayhydur XP2487) evenly to obtain an aqueous polyurethane coating; the molar ratio of the isocyanate group in the aqueous isocyanate curing agent to the hydroxyl group in the aqueous acrylate emulsion is 1.1:1.

[0087] Comparative Example 3

[0088] The difference between the fireproof and aging-resistant highly reflective aluminum-plastic composite film of this comparative example and the fireproof and aging-resistant highly reflective aluminum-plastic composite film of Example 1 is only that in step (1) of the preparation method of the aqueous polyurethane coating used to prepare the transparent protective layer in the fireproof and aging-resistant highly reflective aluminum-plastic composite film of this comparative example, 1,1,1-trifluoro-2,3-epoxypropane is replaced by 3-(perfluorobutane)-1,2-epoxypropane.

[0089] Comparative Example 4

[0090] The difference between the fireproof and aging-resistant highly reflective aluminum-plastic composite film of this comparative example and the fireproof and aging-resistant highly reflective aluminum-plastic composite film of Example 1 is only that the preparation method of the aqueous polyurethane coating used to prepare the transparent protective layer in the fireproof and aging-resistant highly reflective aluminum-plastic composite film of this comparative example is as follows:

[0091] (1) Add 1,4 - cyclohexanediamine, propylene oxide, and acetone into a reaction kettle. After stirring evenly, heat to 40 °C and stir - react for 18 h. Then perform vacuum distillation to remove the solvent, obtaining a concentrate. Subject the concentrate to column chromatography purification to obtain a diol. Among them, the molar ratio of 1,4 - cyclohexanediamine to propylene oxide is 1:2, the mass ratio of propylene oxide to acetone is 1:1.2, and the eluent used for column chromatography purification is composed of petroleum ether, ethyl acetate, and dichloromethane with a volume ratio of 15:1:1.

[0092] (2) Add the diol, 4 - bromo - 1,2 - epoxybutane, and acetone into a reaction kettle. After stirring evenly, heat to 45 °C and stir - reflux react for 24 h. Then perform vacuum distillation to remove the solvent, obtaining a concentrate. Subject the concentrate to column chromatography purification to obtain a brominated polyol. Among them, the molar ratio of the diol to 4 - bromo - 1,2 - epoxybutane is 1:2, the mass ratio of 4 - bromo - 1,2 - epoxybutane to acetone is 1:1, and the eluent used for column chromatography purification is composed of petroleum ether, ethyl acetate, and methanol with a volume ratio of 15:1:1.

[0093] (3) Add the brominated polyol, 2,6 - dimethylpiperidine, and acetone into a reaction kettle. After stirring evenly, heat to 60 °C and stir - reflux react for 24 h. Then perform vacuum distillation to remove the solvent, obtaining a concentrate. Subject the concentrate to column chromatography purification to obtain a piperidine - modified polyol. Among them, the molar ratio of the brominated polyol to 2,6 - dimethylpiperidine is 1:2, the mass ratio of 2,6 - dimethylpiperidine to acetone is 1:1.5, and the eluent used for column chromatography purification is composed of petroleum ether, ethyl acetate, and methanol with a volume ratio of 15:1:1.

[0094] (4) Add the piperidine - modified polyol, (3 - bromopropyl)phosphoric acid, and acetone into a reaction kettle. After stirring evenly, heat to 75 °C and stir - reflux react for 24 h. Then perform vacuum distillation to remove the solvent, obtaining a concentrate. Subject the concentrate to column chromatography purification to obtain a functional polyol. Among them, the molar ratio of the piperidine - modified polyol to (3 - bromopropyl)phosphoric acid is 1:4.5, the mass ratio of (3 - bromopropyl)phosphoric acid to acetone is 1:1.5, and the eluent used for column chromatography purification is composed of petroleum ether, ethyl acetate, and methanol with a volume ratio of 15:1:1.5. The structure of the functional polyol is as follows:

[0095] .

[0096] (5) Add functional polyol and water with a mass ratio of 1:8 into the reaction kettle, stir evenly to obtain a mixed solution, then control the temperature of the materials in the reaction kettle at 65 °C, and dropwise add the first monomer mixture into the reaction kettle under stirring conditions. After the dropping is completed, continue to stir and react for 30 min, then dropwise add the second monomer mixture into the reaction kettle, continue to stir and react for 5 h, cool down to 35 °C, add ammonia water into the reaction kettle, and adjust the pH of the materials in the reaction kettle to 7 to obtain an aqueous acrylate emulsion; wherein, the first monomer mixture is composed of methyl methacrylate, butyl acrylate, isooctyl acrylate, acrylic acid, hydroxypropyl acrylate and potassium persulfate with a mass ratio of 25:8:5:4:5:0. I; the second monomer mixture is composed of methyl acrylate, butyl acrylate, hexyl acrylate, acrylic acid, hydroxyethyl acrylate and potassium persulfate with a mass ratio of 23:5:8:4:5:0.1; the mass ratio of the functional polyol, the first monomer mixture and the second monomer mixture is 8:10:75.

[0097] (6) Stir the aqueous acrylate emulsion and the aqueous isocyanate curing agent (Covestro Bayhydur XP2487) evenly to obtain an aqueous polyurethane coating; the molar ratio of the isocyanate group in the aqueous isocyanate curing agent to the hydroxyl group in the aqueous acrylate emulsion is 1.1:1.

[0098] Experimental examples

[0099] In order to investigate the basic properties of the highly reflective aluminum-plastic composite films of each example and comparative example, the peel strength between the transparent protective layer and the vacuum aluminized polypropylene film, the self-cleaning performance, weather resistance and fire and heat resistance of the transparent protective layer, and the reflectivity of the aluminum-plastic composite film of each example and comparative example were respectively tested.

[0100] Among them, the test method for weather resistance is as follows: Place the highly reflective aluminum-plastic composite film with the transparent protective layer facing up in an artificial aging test chamber for weather resistance testing, calculate the absolute value of the color difference between before aging of the protective layer and when the aging time is 6000 h, and use the absolute value of the color difference as a quantitative evaluation index for weather resistance.

[0101] The test method for self-cleaning performance is as follows: Place the highly reflective aluminum-plastic composite film with the transparent protective layer facing up, divide the transparent protective layer into two parts with the same area, namely part A and part B, and cover a layer with a density of 0.1 g / cm 2For the chalk dust, then tilt the glass plate at an angle of 10 degrees, and then spray vertically downward at a position 20 cm above the top. The A part and the B part of the protective layer are both sprayed in the same way to simulate the rain erosion in nature. Then place the glass plate horizontally in a drying oven for drying. After drying, measure the reflectivity coefficients of the A part and the B part of the protective layer, which are Fa and Fb respectively. Calculate the change rate of the reflectivity coefficient, and the calculation formula is (Fb - Fa) / Fb. Use the change rate of the reflectivity coefficient to evaluate the self-cleaning performance of the protective layer.

[0102] The test method for the fire resistance and heat resistance is as follows: Spin-coat the waterborne polyurethane coatings used in each example and comparative example on the aluminum foil, cure at 70 °C for 48 h, and then place them in an oven at 350 °C to observe the blistering, wrinkling, peeling, and cracking of the coating, and record the time when the coating first shows blistering, peeling, wrinkling, or cracking.

[0103] The test method for the reflectivity is as follows: Place the transparent protective layer of the high-reflection aluminum-plastic composite film facing upward, and use a reflectivity measuring instrument to measure the reflectivity of the ultraviolet-visible spectroscopy with a wavelength range of 200 - 1400 nm according to the method specified in ASTM-17 "Test Method for Solar Transmission and Reflection of Sheet Materials".

[0104] The test results of the peel strength between the transparent protective layer and the vacuum aluminized polypropylene film in the high-reflection aluminum-plastic composite films of each example and comparative example, the weather resistance and self-cleaning performance of the transparent protective layer, and the reflectivity of the aluminum-plastic composite film are shown in Table 1.

[0105] Table 1 Peel strength between the transparent protective layer and the vacuum aluminized polypropylene film in the high-reflection aluminum-plastic composite film

[0106] Weather resistance and self-cleaning performance of the transparent protective layer, reflectivity of the aluminum-plastic composite film

[0107] Aluminum-plastic composite film Peeling strength (N / 15mm) Self-cleaning performance - Rate of change of reflectivity (%) Weather resistance - Absolute value of color difference Fire and heat resistance Reflectivity (%) Example 1 6.1 1.5 2.1 15d 93.4 Example 2 6.5 1.2 1.8 17d 93.6 Example 3 6.2 1.4 1.9 14d 92.5 Comparative example 1 0.8 9.2 9.1 3d 57.1 Comparative example 2 1.3 10.4 9.7 1d 62.7 Comparative example 3 0.7 8.9 7.8 3d 42.3 Comparative example 4 1.7 7.1 8.6 2d 53.8

[0108] As can be seen from Table 1, the high-reflection aluminum-plastic composite film of the present invention simultaneously has good adhesion performance, heat and weather resistance, self-cleaning performance, and a relatively high reflectivity. By synthesizing a polyol having hydrophobic fluorine atoms, large steric hindrance piperidine groups, phosphate branches, hydrophilic quaternary ammonium salts, and a polyhydroxy structure, and using the synthesized polyol to prepare an aqueous acrylate emulsion, not only can the role of a surfactant be exerted, but also the various functional structural groups in the polyol cooperate with each other and jointly play a role, effectively improving the adhesion to the aluminum layer, as well as the weather resistance, self-cleaning performance, and transparency of the coating. Among them, the hydrophobic fluorine atoms can improve the wetting performance of the aqueous acrylate emulsion on the substrate and the water-repellent and oil-affinity of the coating; the large steric hindrance piperidine groups have anti-radiation and UV resistance properties; the acidic phosphate branches can slightly corrode metallic aluminum to improve the adhesion bonding strength; the hydrophilic quaternary ammonium salts and polyhydroxy structures can improve the affinity and compatibility of the polyol with the aqueous acrylate emulsion, and can also improve the wetting and dispersibility of the polyurethane coating, thereby improving the adhesion strength to the substrate.

[0109] As can be seen from Example 1 and Comparative Example 1, when using piperidine-modified fluorinated polyol, due to the lack of branched phosphate groups, the bonding strength and heat and weather resistance of the polyurethane coating both show an obvious downward trend. As can be seen from Example 1 and Comparative Example 2, when using a mixture of piperidine-modified fluorinated polyol and hydroxyethyl phosphoric acid, although the emulsion contains both piperidine-modified fluorinated polyol and a phosphate structure, since the piperidine-modified fluorinated polyol and the phosphate structure are not in a chemical bonding relationship, their cooperation relationship is poor, and they are arranged in a disordered structure in the emulsion, which is not conducive to improving the comprehensive performance of the protective layer.

[0110] As can be seen from Example 1 and Comparative Examples 3-4, when replacing 1,1,1-trifluoro-2,3-epoxypropane with 3-(perfluorobutane)-1,2-epoxypropane or epoxypropane, due to too much or too little fluorine atom content in the system, the hydrophilic-lipophilic balance of the emulsion is disrupted, resulting in uneven distribution of the active groups in the latex particles and segregation, which not only affects the adhesion of the coating, but also affects the heat resistance, weather resistance, and light reflectivity of the coating.

[0111] Application Example

[0112] From the test results of the above experimental examples, it can be seen that the high-reflection aluminum-plastic composite film of the present invention simultaneously has good adhesion performance, heat and weather resistance, self-cleaning performance, and a relatively high reflectivity, and can be applied to the field of double-sided double-glass photovoltaic modules. The high-reflection aluminum-plastic composite films of Examples 1-3 were laid on the ground of a photovoltaic power plant, and the sunlight irradiated on the ground was reflected to the back of the modules through the gaps between the modules, enabling the front and back sides of the modules to generate electricity simultaneously. The experimental results show that after laying the high-reflection aluminum-plastic composite film of the present invention, the power generation efficiency of the double-sided double-glass photovoltaic modules can be increased by 20% to 30%. In addition, after laying the high-reflection aluminum-plastic composite film of the present invention, the weeds on the ground of the power plant are reduced, and the problems of dust and soil erosion are alleviated.

[0113] In summary, the high-reflection aluminum-plastic composite film of the present invention simultaneously has good adhesion performance, heat and weather resistance, self-cleaning performance, and a relatively high reflectivity, and has the functions of preventing weeds, dust, and erosion. It can be applied not only to photovoltaic power stations but also to engineering fields that require reflection of sunlight and heat radiation, such as landfills, reservoir liners, roof insulation, etc. Each material in the high-reflection aluminum-plastic composite film of the present invention can be recycled, and the production process is environmentally friendly, which can effectively reduce the emission of waste materials and harmful substances.

Claims

1. A highly reflective aluminum-plastic composite film with fire resistance and aging resistance, characterized in that, The invention comprises a transparent protective layer, a vacuum aluminum-plated polypropylene film and a polyethylene substrate, which are laminated in sequence. The vacuum aluminum-plated polypropylene film is laminated with the transparent protective layer through the vacuum aluminum-plated layer. The transparent protective layer is formed by curing a water-based polyurethane coating. The water-based polyurethane coating is composed of a water-based acrylic ester emulsion and a water-based isocyanate curing agent. The preparation method of the water-based acrylic ester emulsion is as follows: a functional polyol, water and a first monomer mixture are mixed and reacted, and then mixed and reacted with a second monomer mixture to obtain a water-based acrylic ester emulsion. The first monomer mixture is composed of a first mixed monomer and an initiator. The first mixed monomer is composed of a mass The first monomer mixture is composed of methyl methacrylate, butyl acrylate, isooctyl acrylate, acrylic acid and hydroxypropyl acrylate in a mass ratio of 25-30:8-10:5-7:4-6:5-8; the second monomer mixture is composed of a second mixed monomer and an initiator, and the second mixed monomer is composed of methyl acrylate, butyl acrylate, hexyl acrylate, acrylic acid and hydroxyethyl acrylate in a mass ratio of 23-25:5-7:8-10:4-8:5-7; the mass ratio of the functional polyol, the first monomer mixture and the second monomer mixture is 8:10-12:75-85; the structure of the functional polyol is as follows: 。 2. The fireproof and aging-resistant highly reflective aluminum-plastic composite film according to claim 1, characterized in that, The thickness of the polyethylene substrate is 0.3-0.4 mm, the thickness of the vacuum aluminum-plated polypropylene film is 0.03-0.05 mm, and the thickness of the transparent protective layer is 20-35 μm.

3. The fireproof and aging-resistant highly reflective aluminum-plastic composite film according to claim 1, wherein The first monomer mixture consists of methyl methacrylate, butyl acrylate, isooctyl acrylate, acrylic acid, hydroxypropyl acrylate and potassium persulfate in a mass ratio of 25-30:8-10:5-7:4-6:5-8:0.1-0.

15.

4. The fireproof and aging-resistant highly reflective aluminum-plastic composite film according to claim 1, characterized in that, The second monomer mixture consists of methyl acrylate, butyl acrylate, hexyl acrylate, acrylic acid, hydroxyethyl acrylate and potassium persulfate in a mass ratio of 23-25:5-7:8-10:4-8:5-7:0.1-0.

15.

5. The fireproof and aging-resistant highly reflective aluminum-plastic composite film according to any one of claims 1-4, characterized in that, The preparation method of the functional polyol is as follows: (1) mixing 1,4-cyclohexanediamine and 1,1,1-trifluoro-2,3-propylene oxide at a temperature of 40-50° C. for 18-24 hours to obtain a fluorinated diol; the molar ratio of the 1,4-cyclohexanediamine to the 1,1,1-trifluoro-2,3-propylene oxide is 1:2; (2) mixing a fluorinated diol and 4-bromo-1,2-butylene oxide at a temperature of 45-50° C. for 24-30 hours to obtain a brominated fluorinated polyol; the molar ratio of the fluorinated diol to 4-bromo-1,2-butylene oxide is 1:2; (3) mixing a brominated fluorinated polyol and 2,6-dimethylpiperidine at a temperature of 60-65° C. for 24-30 hours to obtain a piperidine-modified fluorinated polyol; the molar ratio of the brominated fluorinated polyol to the 2,6-dimethylpiperidine is 1:2; (4) Mixing the piperidine-modified fluorinated polyol and (3-bromopropyl)phosphoric acid at a temperature of 75-80° C. for 24-30 hours to obtain a functional polyol; the molar ratio of the piperidine-modified fluorinated polyol to (3-bromopropyl)phosphoric acid is 1:4.5-5.

6. The fireproof and aging-resistant highly reflective aluminum-plastic composite film according to any one of claims 1-4, characterized in that The temperature for the mixing reaction of the functional polyol, water and the first monomer mixture is 65 - 75 °C, and the time is 30 - 50 min.

7. The fireproof and aging-resistant highly reflective aluminum-plastic composite film according to any one of claims 1-4, characterized in that, The time for the mixing reaction with the second monomer mixture is 5 - 6 h.

8. A method for preparing a fireproof and aging-resistant highly reflective aluminum-plastic composite film according to any one of claims 1-7, characterized in that, It includes the following steps: laminating a vacuum aluminized polypropylene film and a polyethylene film to obtain a composite layer; then coating an aqueous polyurethane coating on the aluminized layer surface of the composite layer, and curing to obtain a fireproof and aging-resistant highly reflective aluminum-plastic composite film.

9. The preparation method of the fireproof and aging-resistant highly reflective aluminum-plastic composite film according to claim 8, characterized in that, The temperature for the curing is 60 - 70 °C, and the time is 24 - 48 h.

10. Application of a fireproof and aging-resistant highly reflective aluminum-plastic composite film as described in any one of claims 1 - 7 in improving the power generation efficiency of the back side of a photovoltaic cell.

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