Aluminum oxide film for aging-resistant packaging and preparation method thereof

Abstract

The present application discloses an aluminum oxide-coated film for aging-resistant packaging and a preparation method thereof, belonging to the field of thin films. An aluminum oxide-coated film for aging-resistant packaging comprises a substrate, one side of which is sequentially provided with a first polyurethane coating, a first aluminum oxide coating, a second polyurethane coating, a second aluminum oxide coating, and a third polyurethane coating; the first polyurethane coating, the second polyurethane coating, and the third polyurethane coating can all be cured by polyurethane coating, and the polyurethane coating contains a main agent, an isocyanate curing agent, an auxiliary agent, and water; the main agent contains a hydroxyl-terminated polyurethane emulsion, silica sol, and a modified aluminum sol, and the modified aluminum sol is obtained by reacting the aluminum sol with a vinyl silane coupling agent, and the resulting grafted mixture is then polymerized with a fluorine-containing acrylate monomer and styrene. The present application has the advantages of reducing the difficulty of producing solar photovoltaic backsheets and maintaining aging resistance.

Description

Technical Field

[0001] The present application relates to the field of thin films, and in particular to an aluminum oxide-plated thin film for aging-resistant packaging and a preparation method thereof. Background Art

[0002] With people's increasing attention to renewable energy and reducing carbon emissions, as well as the continuous innovation and cost reduction of photovoltaic technology, the market prospects of solar photovoltaic modules are increasingly being developed. Among them, solar photovoltaic backsheets, which are the key packaging materials of solar photovoltaic modules, have also become a hot spot for research and development and application.

[0003] Since solar photovoltaic modules are generally installed outdoors and need to withstand various harsh environmental conditions, such as high temperature and humidity, the solar photovoltaic backsheet not only needs to have good barrier properties, but also needs to have good aging resistance to improve the durability of the solar photovoltaic modules.

[0004] At present, solar photovoltaic backsheets are generally composed of three-layer co-extruded composite films. Taking BBF solar backsheets as an example, they use a three-layer co-extruded film of EVA resin + PET resin + THV resin. However, the three-layer co-extruded film is difficult to process and has high requirements for extrusion equipment and control process. The production conditions of most manufacturers cannot meet them, which is not conducive to the development of the solar backsheet market. Summary of the Invention

[0005] In order to reduce the difficulty of producing solar photovoltaic backsheets and maintain aging resistance, the present application provides an aluminum oxide-plated film for aging-resistant packaging and a preparation method thereof.

[0006] In the first aspect, the present application provides an aluminum oxide film for aging-resistant packaging using the following technical solutions:

[0007] An aluminum oxide film for aging-resistant packaging comprises a substrate, one side of which is sequentially provided with a first polyurethane coating, a first aluminum oxide coating, a second polyurethane coating, a second aluminum oxide coating and a third polyurethane coating;

[0008] The first polyurethane coating, the second polyurethane coating and the third polyurethane coating can all be formed by curing a polyurethane coating, wherein the polyurethane coating comprises a main agent, an isocyanate curing agent, an auxiliary agent and water;

[0009] The main agent comprises hydroxyl-terminated polyurethane emulsion, silica sol and modified aluminum sol. The modified aluminum sol is obtained by reacting aluminum sol with a vinyl silane coupling agent, and then polymerizing the generated grafted mixture with a fluorine-containing acrylate monomer and styrene.

[0010] By adopting the above technical solution, two layers of aluminum oxide coating are evaporated on the surface of the substrate, and three layers of polyurethane coating are added to improve the density of the substrate surface, thereby obtaining good moisture barrier and gas barrier capabilities. It can replace multi-layer resin co-extruded films and be applied to solar backsheets to protect photovoltaic modules. Traditional equipment and technology can realize the molding of polyurethane coating and aluminum oxide coating, so the production process is simpler, which reduces equipment investment costs and production difficulty.

[0011] All three layers of polyurethane coating are formed by curing polyurethane coatings. Specifically, the hydroxyl-terminated polyurethane emulsion in the main agent reacts and cures with an isocyanate curing agent. The addition of silica sol and modified alumina sol utilizes the hydroxyl groups in the silica and alumina sols to react and bond with the isocyanate, forming a stable bond. The alumina in the alumina sol also creates a good interfacial compatibility with the alumina coating, enhancing the adhesion between the polyurethane coating and the alumina coating. Fluorinated acrylate monomers are polymerized in the modified alumina sol, enhancing the weather resistance of the polyurethane coating through the fluorosilicone groups. Further polymerization of styrene increases the rigidity of the polyurethane coating. Because a vinyl silane coupling agent is grafted prior to polymerization, the polyurethane coating maintains its density, achieving a balance between high barrier properties and aging resistance, making it suitable for photovoltaic module backsheets.

[0012] Optionally, the modified aluminum sol is prepared from the following raw materials in parts by weight:

[0013] 20-30 parts of aluminum sol;

[0014] 1.8-5 parts of vinyl silane coupling agent;

[0015] 1.6-2.85 parts of fluorinated acrylate monomer;

[0016] 0.2-0.4 parts of styrene;

[0017] 0.1-0.2 parts of initiator;

[0018] 0.2-0.4 parts of emulsifier;

[0019] 4-6 parts of alcohol solvent;

[0020] 10-15 parts water.

[0021] By adopting the above technical solution, the modified aluminum sol can not only improve the adhesion between the polyurethane coating and the alumina coating, but also improve the aging resistance of the polyurethane coating by introducing fluorine functional groups. In addition, it was found that the modified aluminum sol can reduce the agglomeration of colloid particles and make the sol components stably dispersed in the main agent.

[0022] Optionally, the aluminum sol is aluminum oxide sol.

[0023] Optionally, the silica sol is silica sol.

[0024] By adopting the above technical solution, the silica sol can form silicon-hydrogen bonds to enhance the density of the polyurethane coating. At the same time, as the main body of the sol system, it reduces the amount of aluminum sol and improves stability.

[0025] Optionally, the vinyl silane coupling agent is selected from one or more of γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, vinyltrimethoxysilane and vinyltriethoxysilane.

[0026] By adopting the above technical solution, the vinyl silane coupling agent can provide carbon-carbon double bonds for polymerization of fluorinated acrylate monomer and styrene after being grafted onto the aluminum sol, thereby introducing fluorinated acrylate monomer and styrene into the aluminum sol.

[0027] Optionally, the fluorine-containing acrylate monomer is selected from one or more of trifluoroethyl methacrylate, hexafluorobutyl methacrylate and octafluoropentyl methacrylate.

[0028] By adopting the above technical solution, the above-mentioned fluorine-containing acrylate monomers can all be polymerized in the aluminum sol, providing fluorine functional groups and thereby improving the weather resistance of the polyurethane coating. When the vinyl silane coupling agent specifically selects γ-methacryloxypropyltrimethoxysilane or γ-methacryloxypropyltriethoxysilane, and the fluorine-containing acrylate monomer specifically selects trifluoroethyl methacrylate, the longer chain segment of γ-methacryloxypropyltrimethoxysilane can extend the connection position of trifluoroethyl methacrylate, making room for the benzene ring structure of the embedded styrene, further improving the density, and even with the introduction of only a small amount of fluorine, good water barrier and weather resistance can be obtained, thereby improving the gas barrier properties. The aluminum oxide film coating can be suitable for more complex packaging scenarios.

[0029] Optionally, the weight ratio of γ-methacryloxypropyltrimethoxysilane to trifluoroethyl methacrylate is (3-5):(1.6-2.6).

[0030] Optionally, the polyurethane coating used for the first polyurethane coating and the second polyurethane coating comprises the following raw materials in parts by weight:

[0031] 60-70 parts of main agent;

[0032] 5-7 parts of isocyanate curing agent;

[0033] 1-2 parts of additives;

[0034] 10-20 parts water;

[0035] The mass ratio of the hydroxyl-terminated polyurethane emulsion, silica sol and modified aluminum sol in the raw materials of the above-mentioned main agent is 10:(2-2.5):(1.2-1.5);

[0036] The polyurethane coating used in the third polyurethane coating comprises the following raw materials in parts by weight:

[0037] 50-55 parts of main agent;

[0038] 5-6 parts of isocyanate curing agent;

[0039] 2 to 2.5 parts of additives;

[0040] 10-20 parts water;

[0041] The mass ratio of the hydroxyl-terminated polyurethane emulsion, silica sol and modified aluminum sol in the raw materials of the main agent is 10:(2.2-2.7):(0.4-0.6).

[0042] By adopting the above technical solution, only the third polyurethane coating layer among the three polyurethane coating layers is in contact with the outside world. Therefore, the composition ratio of the third polyurethane coating layer is adjusted, especially the content of aluminum sol, to ensure the stability of the outermost polyurethane coating layer.

[0043] Optionally, the auxiliary agent is one or both of a leveling agent and a thickener.

[0044] Optionally, the substrate is a PET film or a BOPET film.

[0045] Optionally, the thickness of the aluminum oxide coating is 100 to 150 angstroms.

[0046] In a second aspect, the present application provides a method for preparing an aluminum oxide film for aging-resistant packaging using the following technical solution:

[0047] A method for preparing an aluminum oxide film for aging-resistant packaging, comprising the following steps:

[0048] The vinyl silane coupling agent is added to an alcohol solvent and dispersed uniformly, and then added to the aluminum sol, and heated to react to obtain a grafted mixture;

[0049] The emulsifier is evenly dispersed in water, and then the grafting mixture, fluorinated acrylate monomer and styrene are added and mixed, and the temperature is raised to 60-70°C, and the initiator is gradually added to react to obtain a modified aluminum sol;

[0050] The hydroxyl-terminated polyurethane emulsion, silica sol and modified aluminum sol are mixed and stirred uniformly to obtain a main agent, and the main agent is then mixed with an isocyanate curing agent, an auxiliary agent and water, and stirred uniformly to obtain a polyurethane coating;

[0051] Applying a polyurethane coating on one side of the substrate, drying and curing the coating to form a first polyurethane coating;

[0052] Vacuum evaporating aluminum oxide on the surface of the first polyurethane coating to form a first aluminum oxide coating layer, and drying and solidifying the layer;

[0053] Applying polyurethane coating on the surface of the first alumina coating, drying and curing it to form a second polyurethane coating;

[0054] vacuum evaporating aluminum oxide on the surface of the second polyurethane coating to form a second aluminum oxide coating, and drying and solidifying the coating;

[0055] A polyurethane coating is coated on the surface of the second aluminum oxide coating, dried and solidified to form a third polyurethane coating, thereby obtaining an aluminum oxide film for aging-resistant packaging.

[0056] By adopting the above technical solution, the weather resistance of the aluminum sol is improved after modification, thereby improving the aging resistance of the polyurethane coating. In addition, the polyurethane coating is applied before each vapor deposition, thereby improving the bonding strength between the aluminum oxide coating and the substrate, and between the aluminum oxide coatings, thereby maintaining good aging resistance and barrier capabilities.

[0057] Optionally, the temperature of the curing process after applying the polyurethane coating is 80-125°C.

[0058] By adopting the above technical solution, the curing temperature of the polyurethane coating is controlled to obtain a polyurethane coating with good aging resistance and barrier properties.

[0059] Optionally, during the vacuum evaporation process, the aluminum plating speed is 8 to 11 m / s, the temperature of the heated aluminum wire is 1350 to 1400° C., the wire feeding speed of the aluminum wire is 135 to 160 mm / min, and the flow rate of the introduced oxygen is 9500 to 10500 sccm.

[0060] By adopting the above technical solution, the parameters of vacuum evaporation are adjusted and the forming state of aluminum oxide is improved to adapt to the surface shape of the modified and adjusted polyurethane coating, thereby forming a dense aluminum oxide coating.

[0061] In summary, this application has the following beneficial effects:

[0062] 1. This application utilizes two vapor-deposited aluminum oxide layers on the substrate surface, followed by a three-layer polyurethane coating to enhance the substrate's surface density, resulting in excellent moisture and gas barrier properties. This film can replace multi-layer resin composite films and be applied to solar backsheets to protect photovoltaic modules. Compared to three-layer co-extruded films, conventional equipment and processes can achieve the formation of the polyurethane coating and aluminum oxide coating, resulting in a simpler production process, lower equipment investment costs, and reduced production difficulty.

[0063] 2. All three layers of polyurethane coating are formed by curing polyurethane coatings. Specifically, the hydroxyl-terminated polyurethane emulsion in the main agent reacts and cures with an isocyanate curing agent. Silica sol and modified aluminum sol are added to form a stable bond by reacting the hydroxyl groups in the silica and aluminum sols with the isocyanate. The aluminum oxide in the aluminum sol forms a good interfacial compatibility with the aluminum oxide coating, improving the adhesion between the polyurethane coating and the aluminum oxide coating. Fluorinated acrylate monomers are polymerized in the modified aluminum sol to enhance the weather resistance of the polyurethane coating through the fluorosilicone groups. Further polymerization of styrene increases the rigidity of the polyurethane coating. Because a vinyl silane coupling agent is grafted before polymerization, the density of the polyurethane coating is ensured, balancing high barrier properties and aging resistance, making it suitable for photovoltaic module backsheets. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Figure 1 This is a planar structural diagram of the aluminum oxide film used for aging-resistant packaging in Example 1 of the present application.

[0065] Description of reference numerals:

[0066] 1. Substrate; 2. First polyurethane coating; 3. First aluminum oxide coating; 4. Second polyurethane coating; 5. Second aluminum oxide coating; 6. Third polyurethane coating. DETAILED DESCRIPTION

[0067] The following is combined with Figure 1 This application is described in further detail.

[0068] Example 1

[0069] An aluminum oxide film for aging-resistant packaging, such as Figure 1 As shown, it includes a substrate 1, and one side of the substrate 1 is sequentially provided with a first polyurethane coating 2, a first aluminum oxide coating 3, a second polyurethane coating 4, a second aluminum oxide coating 5 and a third polyurethane coating 6.

[0070] A method for preparing an aluminum oxide film for aging-resistant packaging, comprising the following steps:

[0071] Weigh 2000g of aluminum sol, 300g of a vinyl silane coupling agent, 160g of a fluorinated acrylate monomer, 20g of styrene, 10g of an initiator, 20g of an emulsifier, and 400g of an alcohol solvent. The aluminum sol is alumina sol with a solid content of 20%, a particle size of 10-20nm, and a pH of 6; the vinyl silane coupling agent is γ-methacryloxypropyltrimethoxysilane; the fluorinated acrylate monomer is trifluoroethyl methacrylate; the emulsifier is DNS-501; the alcohol solvent is a 95wt% ethanol solution; and the initiator is ammonium persulfate, which is pre-dissolved in 0.2L of water to obtain an initiator solution for later use.

[0072] The vinyl silane coupling agent was added to an alcohol solvent and dispersed uniformly, and then added to the aluminum sol, heated to 60° C. and reacted for 2 hours to obtain a grafted mixture.

[0073] The emulsifier was evenly dispersed in 0.8 L of water, and then the grafted mixture, fluorinated acrylate monomer and styrene were added and mixed. The temperature was raised to 70° C., and the initiator solution was gradually added dropwise to react. The initiator was added dropwise within 1.5 h. After the initiator was added dropwise, the reaction was continued for 3 h. After the reaction was completed, the temperature was cooled to obtain a modified aluminum sol.

[0074] Weigh 10 kg of hydroxyl-terminated polyurethane emulsion, 2 kg of silica sol, and 1.2 kg of modified aluminum sol. The hydroxyl-terminated polyurethane emulsion has a solids content of 36%, a fineness of 25 μm, a hydroxyl content of 3%, and a pH of 7. The silica sol is silica sol with a solids content of 25%, a particle size of 10-20 nm, and a pH of 7.

[0075] The hydroxyl-terminated polyurethane emulsion, silica sol and modified aluminum sol are mixed and stirred evenly to obtain a main agent.

[0076] Weigh 6kg of the base agent, 0.5kg of the isocyanate curing agent, 40g of the leveling agent, 60g of the thickener, and 1kg of water. The isocyanate curing agent is a water-dispersible polyisocyanate based on hexamethylene diisocyanate, specifically Desmodur DA; the leveling agent is TEGO Glide 450; and the thickener is RM-825.

[0077] The main agent is mixed with an isocyanate curing agent, a leveling agent, a thickener and water, and stirred evenly to obtain a polyurethane coating for forming a first polyurethane coating and a second polyurethane coating.

[0078] Separately, 10 kg of hydroxyl-terminated polyurethane emulsion, 2.2 kg of silica sol, and 0.4 kg of modified alumina sol were weighed.

[0079] The hydroxyl-terminated polyurethane emulsion, silica sol and modified aluminum sol are mixed and stirred evenly to obtain a main agent.

[0080] Weigh 5kg of main agent, 0.5kg of isocyanate curing agent, 80g of leveling agent, 120g of thickener and 1kg of water.

[0081] The main agent is mixed with the isocyanate curing agent, the leveling agent, the thickener and water, and stirred evenly to obtain a polyurethane coating for forming the third polyurethane coating.

[0082] A substrate is taken, specifically a PET film with a thickness of 25 μm.

[0083] Forming the first polyurethane coating: Apply polyurethane coating on one side of the substrate with a coating amount of 1g / m 2The base film is then passed into a drying tunnel for drying and curing. The drying tunnel is divided into seven sections, and the temperatures of each section are 80°C, 90°C, 110°C, 125°C, 115°C, 105°C, and 100°C, forming a first polyurethane coating with a thickness of 0.1μm.

[0084] Forming the first aluminum oxide coating: The substrate is fed into a vacuum evaporation device, and aluminum oxide is vacuum evaporated on the surface of the first polyurethane coating. During the vacuum evaporation process, the aluminum plating speed is 8 m / s, the temperature of the heated aluminum wire is 1350°C, the wire feeding speed of the aluminum wire is 135 mm / min, and the flow rate of the oxygen introduced is 9500 sccm to form the first aluminum oxide coating. The thickness of the aluminum oxide coating is 100 angstroms, and then it is dried and cured in a 60°C oven for 72 hours.

[0085] Forming the second polyurethane coating: Apply polyurethane coating on the first aluminum oxide coating with a coating amount of 1g / m 2 The base film is then passed into a drying tunnel for drying and curing. The drying tunnel is divided into seven sections, and the temperatures of each section are 80°C, 90°C, 110°C, 125°C, 115°C, 105°C, and 100°C, forming a second polyurethane coating with a thickness of 0.1μm.

[0086] Forming a second aluminum oxide coating: The substrate is fed into a vacuum evaporation device, and aluminum oxide is vacuum evaporated on the surface of the second polyurethane coating. During the vacuum evaporation process, the aluminum plating speed is 8 m / s, the temperature of the heated aluminum wire is 1350°C, the wire feeding speed of the aluminum wire is 135 mm / min, and the flow rate of the oxygen introduced is 9500 sccm to form a second aluminum oxide coating with a thickness of 100 angstroms. The aluminum oxide coating is then dried and cured in a 60°C oven for 72 hours.

[0087] Forming the third polyurethane coating: Apply polyurethane coating on the second alumina coating with a coating amount of 1g / m 2 The base film is then passed into a drying tunnel for drying and curing. The drying tunnel is divided into seven sections, and the temperatures of each section are 80°C, 90°C, 110°C, 125°C, 115°C, 105°C, and 100°C, forming a third polyurethane coating with a thickness of 0.1μm to obtain an aluminum oxide-plated film for aging-resistant packaging.

[0088] Example 2

[0089] The difference between this embodiment and embodiment 1 lies in the different preparation methods.

[0090] A method for preparing an aluminum oxide film for aging-resistant packaging, comprising the following steps:

[0091] Weigh 3000g of aluminum sol, 500g of a vinyl silane coupling agent, 260g of a fluorinated acrylate monomer, 40g of styrene, 20g of an initiator, 40g of an emulsifier, and 600g of an alcohol solvent. The aluminum sol is alumina sol with a solid content of 20%, a particle size of 10-20nm, and a pH of 6; the vinyl silane coupling agent is γ-methacryloxypropyltrimethoxysilane; the fluorinated acrylate monomer is trifluoroethyl methacrylate; the emulsifier is DNS-501; the alcohol solvent is a 95wt% ethanol solution; and the initiator is ammonium persulfate, which is pre-dissolved in 0.2L of water to obtain an initiator solution for later use.

[0092] The vinyl silane coupling agent was added to an alcohol solvent and dispersed uniformly, and then added to the aluminum sol, heated to 70° C. and reacted for 2 hours to obtain a grafted mixture.

[0093] The emulsifier was evenly dispersed in 1.3 L of water, and then the grafted mixture, fluorinated acrylate monomer and styrene were added and mixed. The temperature was raised to 70° C., and the initiator solution was gradually added dropwise to react. The initiator was added dropwise within 1.5 h. After the initiator was added dropwise, the reaction was continued for 3 h. After the reaction was completed, the temperature was cooled to obtain a modified aluminum sol.

[0094] Weigh 10 kg of hydroxyl-terminated polyurethane emulsion, 2.5 kg of silica sol, and 1.5 kg of modified aluminum sol. The hydroxyl-terminated polyurethane emulsion has a solids content of 36%, a fineness of 25 μm, a hydroxyl content of 3%, and a pH of 7. The silica sol is silica sol with a solids content of 25%, a particle size of 10-20 nm, and a pH of 7.

[0095] The hydroxyl-terminated polyurethane emulsion, silica sol and modified aluminum sol are mixed and stirred evenly to obtain a main agent.

[0096] Weigh 7kg of the base agent, 0.7kg of the isocyanate curing agent, 80g of the leveling agent, 120g of the thickener, and 2kg of water. The isocyanate curing agent is a water-dispersible polyisocyanate based on hexamethylene diisocyanate, specifically Desmodur DA; the leveling agent is TEGO Glide 450; and the thickener is RM-825.

[0097] The main agent is mixed with an isocyanate curing agent, a leveling agent, a thickener and water, and stirred evenly to obtain a polyurethane coating for forming a first polyurethane coating and a second polyurethane coating.

[0098] Separately, 10 kg of hydroxyl-terminated polyurethane emulsion, 2.7 kg of silica sol, and 0.6 kg of modified alumina sol were weighed.

[0099] The hydroxyl-terminated polyurethane emulsion, silica sol and modified aluminum sol are mixed and stirred evenly to obtain a main agent.

[0100] Weigh 5.5 kg of main agent, 0.6 kg of isocyanate curing agent, 100 g of leveling agent, 150 g of thickener, and 2 kg of water.

[0101] The main agent is mixed with the isocyanate curing agent, the leveling agent, the thickener and water, and stirred evenly to obtain a polyurethane coating for forming the third polyurethane coating.

[0102] A substrate is taken, specifically a PET film with a thickness of 25 μm.

[0103] Forming the first polyurethane coating: Apply polyurethane coating on one side of the substrate with a coating amount of 1g / m 2 The base film is then passed into a drying tunnel for drying and curing. The drying tunnel is divided into seven sections, and the temperatures of each section are 80°C, 90°C, 110°C, 125°C, 115°C, 105°C, and 100°C, forming a first polyurethane coating with a thickness of 0.1μm.

[0104] Forming the first aluminum oxide coating: The substrate is fed into a vacuum evaporation device, and aluminum oxide is vacuum evaporated on the surface of the first polyurethane coating. During the vacuum evaporation process, the aluminum plating speed is 11 m / s, the temperature of the heated aluminum wire is 1400°C, the wire feeding speed of the aluminum wire is 160 mm / min, and the flow rate of the oxygen introduced is 10500 sccm to form the first aluminum oxide coating. The thickness of the aluminum oxide coating is 100 angstroms, and then it is dried and cured in a 60°C oven for 72 hours.

[0105] Forming the second polyurethane coating: Apply polyurethane coating on the first aluminum oxide coating with a coating amount of 1g / m 2 The base film is then passed into a drying tunnel for drying and curing. The drying tunnel is divided into seven sections, and the temperatures of each section are 80°C, 90°C, 110°C, 125°C, 115°C, 105°C, and 100°C, forming a second polyurethane coating with a thickness of 0.1μm.

[0106] Forming a second aluminum oxide coating: The substrate is fed into a vacuum evaporation device, and aluminum oxide is vacuum evaporated on the surface of the polyurethane coating. During the vacuum evaporation process, the aluminum plating speed is 11 m / s, the temperature of the heated aluminum wire is 1400°C, the wire feeding speed of the aluminum wire is 160 mm / min, and the flow rate of the oxygen introduced is 10500 sccm to form a second aluminum oxide coating. The thickness of the aluminum oxide coating is 100 angstroms, and then it is dried and cured in a 60°C oven for 72 hours.

[0107] Forming the third polyurethane coating: Apply polyurethane coating on the second alumina coating with a coating amount of 1g / m 2 The base film is then passed into a drying tunnel for drying and curing. The drying tunnel is divided into seven sections, and the temperatures of each section are 80°C, 90°C, 110°C, 125°C, 115°C, 105°C, and 100°C, forming a third polyurethane coating with a thickness of 0.1μm to obtain an aluminum oxide-plated film for aging-resistant packaging.

[0108] Example 3

[0109] The difference between this embodiment and embodiment 1 lies in the difference in the modified aluminum sol.

[0110] In the step of preparing the modified aluminum sol, the vinyl silane coupling agent is vinyl trimethoxy silane, and the amount of vinyl trimethoxy silane added is 180 g.

[0111] Example 4

[0112] The difference between this embodiment and embodiment 1 lies in the difference in the modified aluminum sol.

[0113] In the step of preparing the modified aluminum sol, the fluorine-containing acrylate monomer is octafluoropentyl methacrylate, and the amount of octafluoropentyl methacrylate added is 285 g.

[0114] Comparative Example 1

[0115] The difference between this comparative example and Example 1 lies in the difference in the main agent.

[0116] The main agent is composed only of hydroxyl-terminated polyurethane emulsion.

[0117] Comparative Example 2

[0118] The difference between this comparative example and Example 1 lies in the difference in the main agent.

[0119] In the step of preparing the main agent, the modified aluminum sol is not added, and the modified aluminum sol is replaced by an equal amount of unmodified aluminum sol.

[0120] Comparative Example 3

[0121] The difference between this comparative example and Example 1 lies in the difference in the modified aluminum sol.

[0122] The steps for preparing modified aluminum sol are specifically as follows:

[0123] Weigh 2000 g of aluminum sol, 263 g of (3,3,3-trifluoropropyl)trimethoxysilane, and 400 g of 95 wt% ethanol solution.

[0124] (3,3,3-Trifluoropropyl)trimethoxysilane was added to a 95 wt% ethanol solution and dispersed uniformly, and then aluminum sol was added, and the solution was heated to 60° C. and reacted for 2 h to obtain a modified aluminum sol.

[0125] Comparative Example 4

[0126] The difference between this comparative example and Example 1 lies in the difference in the modified aluminum sol.

[0127] In the step of preparing the modified aluminum sol, styrene is not added, and styrene is replaced by an equal amount of fluorine-containing acrylate monomer.

[0128] Performance Testing Barrier Property: Referring to the test methods ASTM D-3985 and ASTM F-1249, the oxygen transmission rate and water vapor transmission rate of the aluminum oxide film were tested. The results are shown in Table 1.

[0129] Tensile strength: Referring to the test method ASTM D-882, the tensile strength of the aluminum oxide film was tested, including the longitudinal tensile strength and the transverse tensile strength. The results are shown in Table 1.

[0130] Heat and moisture resistance: The aluminum oxide film was folded in half with the third aluminum oxide layer facing outward, and the folded edge was sealed with waterproof tape. The film was then placed in a constant temperature and humidity aging chamber set at 85°C and 95% relative humidity for 500 hours. Two hours after the aging process, the aluminum oxide film was cut into the test size and the tensile strength was tested. The results are shown in Table 2.

[0131] Moisture and frost resistance: The aluminum oxide film was folded in half and overlapped, with the third aluminum oxide layer facing outward. The folded edge was sealed with waterproof tape and then placed in a high and low temperature alternating test chamber. The high and low temperature alternating test chamber was set to a temperature cycle of -40°C to 85°C and a relative humidity of 85%. A total of 10 cycles were performed. In each cycle, the temperature was maintained at -40°C for 1 hour and at 85°C for 20 hours. The temperature change rate between -40°C and 0°C was 150°C / h, and the temperature change rate between 0°C and 85°C was 100°C / h. 2 hours after the aging was completed, the aluminum oxide film was cut into the test size and the tensile strength was tested. The results are shown in Table 2.

[0132] Table 1

[0133]

[0134]

[0135] Table 2

[0136]

[0137] Combined analysis of Table 1 and Table 2 shows that the oxygen permeability and water vapor permeability of the aluminum oxide-coated films prepared in Example 1 and Example 2 are low, and the retention rate of tensile strength after wet heat aging and wet freeze aging is high, indicating that the aluminum oxide-coated film is suitable for the backplane of photovoltaic modules, protecting photovoltaic modules from environmental erosion, and has excellent aging resistance and can cope with harsh environments of high temperature and humidity.

[0138] Compared with Comparative Examples 1-4, the aluminum oxide-coated film prepared in Example 1 performs better in oxygen barrier and moisture barrier, and has a high retention rate of tensile strength after aging, indicating that the polyurethane coating using hydroxyl-terminated polyurethane emulsion, silica sol and modified aluminum sol as the main agents can greatly improve the barrier property and stability of the polyurethane coating, and the grafting method of vinyl silane coupling agent and fluorine-containing acrylate monomer can further improve the density of the polyurethane coating, and the benzene ring structure of styrene also promotes the stability of the polyurethane coating.

[0139] Compared with Examples 3-4, the aluminum oxide-coated film prepared in Example 1 performed better in terms of oxygen barrier performance, indicating that the segment structure of γ-methacryloxypropyltrimethoxysilane combined with trifluoroethyl methacrylate can further improve the density of the polyurethane coating, thereby blocking oxygen.

[0140] This specific implementation manner is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the specific implementation manner as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. An aluminum oxide film for aging-resistant packaging, characterized in that: The invention comprises a substrate, wherein one side of the substrate is sequentially provided with a first polyurethane coating, a first aluminum oxide coating, a second polyurethane coating, a second aluminum oxide coating and a third polyurethane coating; The first polyurethane coating, the second polyurethane coating and the third polyurethane coating can all be formed by curing a polyurethane coating, wherein the polyurethane coating comprises a main agent, an isocyanate curing agent, an auxiliary agent and water; The main agent comprises hydroxyl-terminated polyurethane emulsion, silica sol and modified aluminum sol. The modified aluminum sol is obtained by reacting aluminum sol with a vinyl silane coupling agent, and then polymerizing the generated grafted mixture with a fluorine-containing acrylate monomer and styrene.

2. The aluminum oxide film for aging-resistant packaging according to claim 1, characterized in that: The modified aluminum sol is prepared from the following raw materials in parts by weight: 20-30 parts of aluminum sol; 1.8-5 parts of vinyl silane coupling agent; 1.6-2.85 parts of fluorinated acrylate monomer; 0.2-0.4 parts of styrene; 0.1~0.2 parts of initiator; Emulsifier 0.2~0.4 parts; 4-6 parts of alcohol solvent; 10-15 parts water.

3. The aluminum oxide film for aging-resistant packaging according to claim 1, characterized in that: The vinyl silane coupling agent is selected from one or more of γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, vinyltrimethoxysilane and vinyltriethoxysilane.

4. The aluminum oxide film for aging-resistant packaging according to claim 1, characterized in that: The fluorine-containing acrylate monomer is selected from one or more of trifluoroethyl methacrylate, hexafluorobutyl methacrylate and octafluoropentyl methacrylate.

5. The aluminum oxide film for aging-resistant packaging according to claim 1, characterized in that: The polyurethane coating used for the first polyurethane coating and the second polyurethane coating comprises the following raw materials in parts by weight: 60~70 parts of main agent; 5-7 parts of isocyanate curing agent; 1~2 parts of additives; 10-20 parts water; The mass ratio of the hydroxyl-terminated polyurethane emulsion, silica sol and modified aluminum sol in the raw materials of the above-mentioned main agent is 10:(2-2.5):(1.2-1.5); The polyurethane coating used in the third polyurethane coating comprises the following raw materials in parts by weight: 50~55 parts of main agent; 5-6 parts of isocyanate curing agent; 2~2.5 parts of additives; 10-20 parts water; The mass ratio of the hydroxyl-terminated polyurethane emulsion, silica sol and modified aluminum sol in the raw materials of the above-mentioned main agent is 10:(2.2~2.7):(0.4~0.6).

6. The aluminum oxide film for aging-resistant packaging according to any one of claims 1 to 5, characterized in that: The substrate is selected from PET film or BOPET film.

7. The aluminum oxide film for aging-resistant packaging according to any one of claims 1 to 5, characterized in that: The thickness of the aluminum oxide coating is 100-150 angstroms.

8. A method for preparing an aging-resistant aluminum oxide film for packaging according to any one of claims 1 to 7, characterized in that: The following steps are involved: The vinyl silane coupling agent is added to an alcohol solvent and dispersed uniformly, and then added to the aluminum sol, and heated to react to obtain a grafted mixture; The emulsifier is evenly dispersed in water, and then the grafting mixture, fluorinated acrylate monomer and styrene are added and mixed, the temperature is increased, and the initiator is gradually added to react to obtain a modified aluminum sol; The hydroxyl-terminated polyurethane emulsion, silica sol and modified aluminum sol are mixed and stirred uniformly to obtain a main agent, and the main agent is then mixed with an isocyanate curing agent, an auxiliary agent and water, and stirred uniformly to obtain a polyurethane coating; Applying a polyurethane coating on one side of the substrate, drying and curing the coating to form a first polyurethane coating; Vacuum evaporating aluminum oxide on the surface of the first polyurethane coating to form a first aluminum oxide coating layer, and drying and solidifying the layer; Applying polyurethane coating on the surface of the first alumina coating, drying and curing it to form a second polyurethane coating; vacuum evaporating aluminum oxide on the surface of the second polyurethane coating to form a second aluminum oxide coating, and drying and solidifying the coating; A polyurethane coating is coated on the surface of the second aluminum oxide coating, dried and solidified to form a third polyurethane coating, thereby obtaining an aluminum oxide film for aging-resistant packaging.

9. The method for preparing an aging-resistant aluminum oxide film for packaging according to claim 8, characterized in that: The temperature of the curing process after applying the polyurethane coating is 80~125℃.

10. The method for preparing an aging-resistant aluminum oxide film for packaging according to claim 8, characterized in that: During the vacuum evaporation process, the aluminum plating speed is 8~11m / s, the temperature of the heated aluminum wire is 1350~1400℃, the wire feeding speed of the aluminum wire is 135~160mm / min, and the flow rate of the oxygen is 9500~10500sccm.

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