Alumina-plated thin film for high-barrier packaging and preparation method thereof

Abstract

The invention discloses an aluminum oxide plated film for high-barrier packaging and a preparation method of the aluminum oxide plated film, and belongs to the field of films. An aluminum oxide plated film for high-barrier packaging comprises a base material, a plurality of polyurethane coatings and a plurality of aluminum oxide plating layers are alternately arranged on one face of the base material, and the layer structure closest to the base material and the layer structure farthest from the base material are the polyurethane coatings; the polyurethane coating is formed by curing a polyurethane coating, and the polyurethane coating comprises a hydroxyl acrylate emulsion, an isocyanate curing agent, an auxiliary agent and water; the hydroxy acrylate emulsion is obtained by reacting cinnamyl alcohol with long-chain isocyanate and then carrying out polymerization reaction on the generated amino ester product, a hydroxy acrylate monomer and an acrylic monomer. The solar backboard has the advantages that the difficulty of producing the solar backboard is reduced, and the high barrier performance is kept.

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 high-barrier packaging and a preparation method thereof. Background Art

[0002] Globally, the scale of the photovoltaic power generation market continues to expand, and the demand for the output and quality of photovoltaic modules continues to increase. Solar panels, one of the core components of photovoltaic power generation, generally include photovoltaic glass, EVA, solar cells, EVA and solar backplanes, among which the solar backplane is the packaging material located on the back of the solar panel, which protects and supports the cells.

[0003] Solar back panel materials are generally composed of three layers of co-extruded composite film. Taking BBF solar back panel as an example, it uses a three-layer co-extruded film of EVA resin + PET resin + THV resin, which has good barrier properties and toughness, thereby protecting the battery cells.

[0004] Due to the complexity of the three-layer co-extrusion composite film technology and the high requirements for extrusion equipment and control process, production is difficult. Currently, only a few manufacturers have mastered the solar backplane production technology, which affects the wider application of solar backplanes. Summary of the invention

[0005] In order to reduce the difficulty of producing solar back panels and maintain high barrier properties, the present application provides an aluminum oxide-plated film for high-barrier packaging and a preparation method thereof.

[0006] In the first aspect, the present application provides an aluminum oxide-coated film for high-barrier packaging, which adopts the following technical solution: an aluminum oxide-coated film for high-barrier packaging, comprising a substrate, one side of which is alternately provided with a plurality of polyurethane coatings and a plurality of aluminum oxide coatings, wherein the layer structure closest to the substrate and the layer structure farthest from the substrate are both the polyurethane coatings; The polyurethane coating is formed by curing a polyurethane coating, wherein the polyurethane coating comprises a hydroxy acrylate emulsion, an isocyanate curing agent, an auxiliary agent and water; The hydroxy acrylate emulsion is obtained by reacting cinnamyl alcohol with long-chain isocyanate, and then the generated amino ester product is polymerized with hydroxy acrylate monomer and acrylic acid monomer.

[0007] By adopting the above technical solution, the surface of the substrate is modified with multiple aluminum oxide coatings and polyurethane coatings. The aluminum oxide coatings have a dense structure and good moisture barrier and gas barrier capabilities. The aluminum oxide film used as a solar backplane can improve the ability to resist environmental interference, effectively prevent the battery from being corroded by moisture, and extend the service life of the photovoltaic module. Compared with the three-layer co-extruded film, the film modified by multiple aluminum oxide coatings and polyurethane coatings can also protect the photovoltaic module, and is simpler in terms of preparation process. The traditional equipment process can meet the preparation requirements, which reduces the equipment investment cost and the production difficulty.

[0008] The polyurethane coating is cured by polyurethane coating. The polyurethane coating adopts a two-component film-forming method with a high degree of crosslinking. The amino ester product generated by the reaction of cinnamyl alcohol and long-chain isocyanate has a carbon-carbon double bond, and then polymerizes with hydroxy acrylate monomer and acrylic acid monomer to generate polyol, so that the hydroxy acrylate emulsion and isocyanate curing agent can be cross-linked and cured after two-component mixing, so that the adhesion between the aluminum oxide coating and the substrate, and between the aluminum oxide coating and the aluminum oxide coating is greatly improved. On the one hand, the benzene ring is introduced by cinnamyl alcohol to further fix the cross-linked molecular chain segment, reduce the gap generated by the activity of the cross-linked molecular chain segment, and improve the gas barrier ability. On the other hand, the long-chain isocyanate introduces a long-chain hydrophobic structure, so that each layer of polyurethane coating has good hydrophobic and water-blocking ability. The two cooperate to make the polyurethane coating have good moisture barrier and gas barrier ability. In addition, since the benzene ring and the long-chain alkyl are connected by amino ester after the reaction of cinnamyl alcohol and long-chain isocyanate, and the site of polymerization with acrylate is also located between the benzene ring and the long-chain alkyl, the amino ester and the polyurethane have similar segments, which promotes the improvement of the thermal stability of the cross-linked structure.

[0009] Optionally, the hydroxyacrylate emulsion is prepared from the following raw materials in parts by weight: 50-60 parts of hydroxy acrylate monomer; 4-8 parts of acrylic acid monomer; 12-18 parts of long-chain isocyanate; 9-14 parts of cinnamyl alcohol; Emulsifier 2.5-4 parts; Initiator 0.3-0.8 parts; 70-80 parts of water.

[0010] By adopting the above technical scheme, the hydroxy acrylate emulsion is polymerized with hydroxy acrylate monomer as the main body and copolymerized with a small amount of acrylic acid monomer to enhance the binding force to the aluminum oxide coating and enhance the water dispersibility. The excess cinnamyl alcohol ensures the complete reaction of the long-chain isocyanate, and the generated amino ester product is fully copolymerized with the hydroxy acrylate monomer, thereby forming a polyurethane coating with a stable structure and strong barrier ability after cross-linking with the curing agent, while ensuring the strength of the aluminum oxide film.

[0011] Optionally, the hydroxyacrylate is selected from one or more of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate and hydroxypropyl methacrylate.

[0012] Optionally, the acrylic acid monomer is one or both of acrylic acid and methacrylic acid.

[0013] Optionally, the long-chain isocyanate is selected from one or more of dodecyl isocyanate, tetradecyl isocyanate, hexadecyl isocyanate and octadecyl isocyanate.

[0014] By adopting the above technical solution, the above long-chain isocyanate can bring terminal hydrophobic properties and improve the barrier ability to moisture. Among them, the chain segment length of dodecyl isocyanate is moderate, which can avoid the influence of excessively long chain segments on the stability of the cross-linking structure while providing hydrophobic barrier, and performs better in terms of thermal shrinkage.

[0015] Optionally, the polyurethane coating comprises the following raw materials in parts by weight: 60-70 parts of hydroxy acrylate emulsion; 5.5-7 parts of isocyanate curing agent; 1 to 2.5 parts of additives; 20-30 parts water; The auxiliary agent is selected from one or both of a leveling agent and a thickener.

[0016] By adopting the above technical solution, adding a leveling agent and a thickener can improve the flatness of the coating, thereby improving the uniformity of the aluminum oxide film.

[0017] Optionally, the isocyanate curing agent is a water-dispersible polyisocyanate based on hexamethylene diisocyanate.

[0018] By adopting the above technical scheme, the water-dispersible polyisocyanate based on hexamethylene diisocyanate is suitable for forming a stable cross-linking structure with the hydroxy acrylate emulsion, and the cross-linking structure is dense.

[0019] Optionally, the substrate is a PET film or a BOPET film.

[0020] Optionally, the thickness of the aluminum oxide coating is 100 to 150 angstroms.

[0021] Optionally, the polyurethane coating is provided with three layers, and the aluminum oxide coating is provided with two layers.

[0022] Optionally, the thickness of the polyurethane coating is 0.1-0.3 μm.

[0023] In the second aspect, the present application provides a method for preparing an aluminum oxide film for high barrier packaging using the following technical solution: A method for preparing an aluminum oxide film for high barrier packaging comprises the following steps: Mixing cinnamyl alcohol and long-chain isocyanate, heating to react, the heating temperature is 70-75° C., and stopping the reaction when the -NCO content in the reaction system is less than 0.1%, to obtain an amino ester product; Dispersing part of the emulsifier in water uniformly, then adding the amino ester product, hydroxy acrylate monomer and acrylic acid monomer to mix, heating to 75-85° C., gradually adding the initiator to react, adding the remaining emulsifier, and adjusting the pH to neutral after the reaction to obtain a hydroxy acrylate emulsion; The hydroxy acrylate emulsion is mixed with an isocyanate curing agent, an auxiliary agent and water, and stirred evenly to obtain a polyurethane coating; Applying polyurethane coating on one side of the substrate, drying and curing to form a polyurethane coating; Vacuum evaporation of aluminum oxide is performed on the surface of the polyurethane coating to form an aluminum oxide coating, which is then dried and solidified; Applying polyurethane coating on the surface of the aluminum oxide coating, drying and curing, and forming a polyurethane coating; According to the needs, a required number of polyurethane coatings and aluminum oxide coatings are formed on one side of the substrate to obtain an aluminum oxide coating film for high barrier packaging.

[0024] By adopting the above technical solution, the polyurethane coating improves the bonding strength between the aluminum oxide coating and the substrate, and between the aluminum oxide coatings, and after the aluminum oxide coating is formed, it is dried and solidified to further stabilize the aluminum oxide coating, thereby achieving a dense film surface structure and high barrier properties.

[0025] Optionally, the temperature of the curing process after applying the polyurethane coating is 70-120°C.

[0026] By adopting the above technical solution, the curing temperature of the polyurethane coating is controlled to obtain a polyurethane coating with good bonding ability and barrier properties.

[0027] Optionally, during the vacuum evaporation process, the aluminum plating speed is 8-11 m / s, the temperature of the heated aluminum wire is 1350-1400° C., the wire feeding speed of the aluminum wire is 150-180 mm / min, and the flow rate of the introduced oxygen is 8700-10000 sccm.

[0028] By adopting the above technical solution, the parameters of vacuum evaporation are adjusted, and the forming state of aluminum oxide is improved, which is suitable for forming a dense aluminum oxide coating on the surface of the polyurethane coating.

[0029] In summary, this application has the following beneficial effects: 1. The aluminum oxide film of the present application modifies the surface of the substrate with multiple aluminum oxide coatings and polyurethane coatings. The aluminum oxide coating has a dense structure and good moisture barrier and gas barrier capabilities. As a solar backplane, the aluminum oxide film can improve the ability to resist environmental interference, prevent the battery from being corroded by moisture, and extend the service life of the photovoltaic module. Compared with the three-layer co-extruded film, the film modified by multiple aluminum oxide coatings and polyurethane coatings can also protect the photovoltaic module, and is simpler in terms of preparation process. The traditional equipment process can meet the preparation requirements, which reduces the equipment investment cost and the production difficulty.

[0030] 2. The polyurethane coating is cured by polyurethane coating. The polyurethane coating adopts a two-component film-forming method with a high degree of crosslinking. The amino ester product generated by the reaction of cinnamyl alcohol and long-chain isocyanate has a carbon-carbon double bond, which is then polymerized with hydroxy acrylate monomer and acrylic monomer to form a polyol. The hydroxy acrylate emulsion and isocyanate curing agent are mixed in two components to crosslink and cure, which greatly improves the adhesion between the aluminum oxide coating and the substrate, and between the aluminum oxide coatings. On the one hand, the benzene ring is introduced by cinnamyl alcohol to further fix the crosslinked molecular chain segment, reduce the gap generated by the activity of the crosslinked molecular chain segment, and improve the gas barrier ability. On the other hand, the long-chain isocyanate introduces a long-chain hydrophobic structure, so that each layer of polyurethane coating has good hydrophobic and water-blocking ability. The two work together to make the polyurethane coating have good moisture barrier and gas barrier capabilities. In addition, after the reaction of cinnamyl alcohol and long-chain isocyanate, the benzene ring and the long-chain alkyl are connected by amino ester, and the site of polymerization with acrylate is also located between the benzene ring and the long-chain alkyl. The amino ester and polyurethane have similar chain segments, which improves the thermal stability of the cross-linked structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a planar structural diagram of the aluminum oxide-plated film for high-barrier packaging in Example 1 of the present application.

[0032] Description of reference numerals: 1. Substrate; 2. Polyurethane coating; 3. Aluminum oxide coating. DETAILED DESCRIPTION

[0033] The following is combined with Figure 1 This application is described in further detail.

[0034] Example 1 A high barrier encapsulation aluminum oxide film, such as Figure 1 As shown, it includes a substrate 1, and a plurality of polyurethane coatings 2 and a plurality of aluminum oxide coatings 3 are alternately arranged on one side of the substrate 1, wherein the layer structure closest to the substrate 1 and the layer structure farthest from the substrate 1 are both polyurethane coatings 2. In this embodiment, three polyurethane coatings 2 are arranged, and two aluminum oxide coatings 3 are arranged.

[0035] A method for preparing an aluminum oxide film for high barrier packaging comprises the following steps: Weigh 0.9 kg of cinnamyl alcohol and 1.2 kg of long-chain isocyanate, wherein the long-chain isocyanate is dodecyl isocyanate.

[0036] Cinnamyl alcohol and long-chain isocyanate are added into a reaction container and mixed, and heated to 70° C. for reaction. The reaction is stopped when the -NCO content in the reaction system is less than 0.1%, thereby obtaining an amino ester product.

[0037] Weigh 5 kg of hydroxy acrylate monomer, 0.4 kg of acrylic acid monomer, 0.25 kg of emulsifier, and 30 g of initiator. The hydroxy acrylate monomer is hydroxyethyl acrylate, the acrylic acid monomer is methacrylic acid, the emulsifier is sodium dodecyl sulfate, and the initiator is ammonium persulfate. The initiator is pre-dissolved in 0.5 L of water to obtain an initiator solution for use.

[0038] Disperse 50 wt% of the emulsifier evenly in 6.5 L of water, then add the amino ester product, hydroxy acrylate monomer and acrylic acid monomer to mix, heat to 75°C, gradually add the initiator solution to react, the initiator is added within 2 hours, the remaining emulsifier is added 1 hour after the initiator is added, and the reaction is continued for 3 hours after the initiator is added. After the reaction is completed, cool and cool, and adjust the pH of the reaction system to 7 with ammonia water to obtain a hydroxy acrylate emulsion.

[0039] Weigh 6 kg of hydroxy acrylate emulsion, 0.55 kg of isocyanate curing agent, 30 g of leveling agent, 70 g of thickener, and 2 L of water. The isocyanate curing agent is a water-dispersible polyisocyanate based on hexamethylene diisocyanate, specifically Desmodur DA, the leveling agent is BYK-333, and the thickener is RM-825.

[0040] The hydroxy acrylate emulsion, isocyanate curing agent, leveling agent, thickener and water are mixed and stirred evenly to obtain a polyurethane coating.

[0041] A substrate is taken, specifically a PET film with a thickness of 25 μm.

[0042] Forming polyurethane coating: Apply polyurethane coating on one side of the substrate with a coating amount of 1g / m 2 The substrate 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 70°C, 80°C, 115°C, 120°C, 115°C, 110°C, and 105°C, forming a polyurethane coating with a thickness of 0.1μm.

[0043] Forming aluminum oxide coating: The substrate is sent into the vacuum evaporation equipment, and aluminum oxide is vacuum evaporated on the surface of the polyurethane coating. During the vacuum evaporation process, the aluminum plating speed is 8m / s, the temperature of the heated aluminum wire is 1350°C, the wire feeding speed of the aluminum wire is 150mm / min, and the flow rate of oxygen is 8700sccm to form an aluminum oxide coating with a thickness of 100 angstroms. It is then dried and cured in a 60°C oven for 72 hours.

[0044] A polyurethane coating is coated on the surface of the aluminum oxide coating obtained in the previous step, and the above steps of forming the polyurethane coating are repeated to form a polyurethane coating with a thickness of 0.1 μm.

[0045] Aluminum oxide is vacuum evaporated on the surface of the polyurethane coating prepared in the previous step, and the above steps of forming the aluminum oxide coating are repeated to form an aluminum oxide coating having a thickness of 100 angstroms.

[0046] Polyurethane coating is coated on the surface of the aluminum oxide coating obtained in the previous step, and the above steps of forming the polyurethane coating are repeated to form a polyurethane coating with a thickness of 0.1 μm, thereby obtaining three polyurethane coatings and two aluminum oxide coatings arranged alternately, thereby obtaining an aluminum oxide film for high barrier packaging.

[0047] Example 2 The difference between this embodiment and embodiment 1 is the different preparation methods.

[0048] A method for preparing an aluminum oxide film for high barrier packaging comprises the following steps: Weigh 1.4 kg of cinnamyl alcohol and 1.8 kg of long-chain isocyanate, wherein the long-chain isocyanate is dodecyl isocyanate.

[0049] Cinnamyl alcohol and long-chain isocyanate are added into a reaction container and mixed, and heated to 75° C. for reaction. The reaction is stopped when the -NCO content in the reaction system is less than 0.1%, thereby obtaining an amino ester product.

[0050] Weigh 6 kg of hydroxy acrylate monomer, 0.8 kg of acrylic acid monomer, 0.4 kg of emulsifier, and 80 g of initiator. The hydroxy acrylate monomer is hydroxyethyl acrylate, the acrylic acid monomer is methacrylic acid, the emulsifier is sodium dodecyl sulfate, and the initiator is ammonium persulfate. The initiator is pre-dissolved in 0.5 L of water to obtain an initiator solution for use.

[0051] Disperse 50 wt% of the emulsifier evenly in 7.5 L of water, then add the amino ester product, hydroxy acrylate monomer and acrylic acid monomer to mix, heat to 85°C, gradually add the initiator solution to react, the initiator is added within 2 hours, the remaining emulsifier is added 1 hour after the initiator is added, and the reaction is continued for 3 hours after the initiator is added. After the reaction is completed, cool and cool, and adjust the pH of the reaction system to 7 with ammonia water to obtain a hydroxy acrylate emulsion.

[0052] Weigh 7 kg of hydroxy acrylate emulsion, 0.7 kg of isocyanate curing agent, 70 g of leveling agent, 180 g of thickener, and 3 L of water. The isocyanate curing agent is a water-dispersible polyisocyanate based on hexamethylene diisocyanate, specifically Desmodur DA, the leveling agent is BYK-333, and the thickener is RM-825.

[0053] The hydroxy acrylate emulsion, isocyanate curing agent, leveling agent, thickener and water are mixed and stirred evenly to obtain a polyurethane coating.

[0054] A substrate is taken, specifically a PET film with a thickness of 25 μm.

[0055] Forming polyurethane coating: Apply polyurethane coating on one side of the substrate with a coating amount of 1g / m 2 The substrate 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 70°C, 80°C, 115°C, 120°C, 115°C, 110°C, and 105°C, forming a polyurethane coating with a thickness of 0.1μm.

[0056] Forming aluminum oxide coating: The substrate is sent into the vacuum evaporation equipment, and aluminum oxide is vacuum evaporated on the surface of the polyurethane coating. During the vacuum evaporation process, the aluminum plating speed is 11m / s, the temperature of the heated aluminum wire is 1400℃, the wire feeding speed of the aluminum wire is 180mm / min, and the flow rate of oxygen is 10000sccm to form an aluminum oxide coating with a thickness of 100 angstroms. It is then dried and cured in a 60℃ oven for 72h.

[0057] A polyurethane coating is coated on the surface of the aluminum oxide coating obtained in the previous step, and the above steps of forming the polyurethane coating are repeated to form a polyurethane coating with a thickness of 0.1 μm.

[0058] Aluminum oxide is vacuum evaporated on the surface of the polyurethane coating prepared in the previous step, and the above steps of forming the aluminum oxide coating are repeated to form an aluminum oxide coating having a thickness of 100 angstroms.

[0059] Polyurethane coating is coated on the surface of the aluminum oxide coating obtained in the previous step, and the above steps of forming the polyurethane coating are repeated to form a polyurethane coating with a thickness of 0.1 μm, thereby obtaining three polyurethane coatings and two aluminum oxide coatings arranged alternately, thereby obtaining an aluminum oxide film for high barrier packaging.

[0060] Example 3 The difference between this embodiment and embodiment 1 lies in the difference in hydroxy acrylate emulsion.

[0061] In the step of preparing the hydroxy acrylate emulsion, the long-chain isocyanate is hexadecyl isocyanate, and the amount of hexadecyl isocyanate added is 1.52 kg.

[0062] Comparative Example 1 The difference between this comparative example and Example 1 lies in the difference in the hydroxyacrylate emulsion.

[0063] The hydroxyl acrylate emulsion used in this comparative example is a commercially available hydroxyl acrylate emulsion with a hydroxyl value of 3%.

[0064] Comparative Example 2 The difference between this comparative example and Example 1 lies in the difference in hydroxy acrylate emulsion. Specifically: Weigh 0.78 kg of hydroxyethyl acrylate and 1.2 kg of long-chain isocyanate, wherein the long-chain isocyanate is dodecyl isocyanate.

[0065] Hydroxyethyl acrylate and long-chain isocyanate are added into a reaction container and mixed, and heated to 70° C. for reaction. The reaction is stopped when the -NCO content in the reaction system is less than 0.1%, thereby obtaining an amino ester product.

[0066] Weigh 5 kg of hydroxy acrylate monomer, 0.4 kg of acrylic acid monomer, 0.25 kg of emulsifier, and 30 g of initiator. The hydroxy acrylate monomer is hydroxyethyl acrylate, the acrylic acid monomer is methacrylic acid, the emulsifier is sodium dodecyl sulfate, and the initiator is ammonium persulfate. The initiator is pre-dissolved in 0.5 L of water to obtain an initiator solution for use.

[0067] Disperse 50 wt% of the emulsifier evenly in 6.5 L of water, then add the amino ester product, hydroxy acrylate monomer and acrylic acid monomer to mix, heat to 75°C, gradually add the initiator solution to react, the initiator is added within 2 hours, the remaining emulsifier is added 1 hour after the initiator is added, and the reaction is continued for 3 hours after the initiator is added. After the reaction is completed, cool and cool, and adjust the pH of the reaction system to 7 with ammonia water to obtain a hydroxy acrylate emulsion.

[0068] Comparative Example 3 The difference between this comparative example and Example 1 lies in the difference in hydroxy acrylate emulsion. Specifically: Weigh 0.9 kg of cinnamyl alcohol and 0.4 kg of short-chain isocyanate, wherein ethyl isocyanate is selected as the short-chain isocyanate.

[0069] Cinnamyl alcohol and short-chain isocyanate are added into a reaction container and mixed, and heated to 70° C. for reaction. The reaction is stopped when the -NCO content in the reaction system is less than 0.1%, thereby obtaining an amino ester product.

[0070] Weigh 5 kg of hydroxy acrylate monomer, 0.4 kg of acrylic acid monomer, 0.25 kg of emulsifier, and 30 g of initiator. The hydroxy acrylate monomer is hydroxyethyl acrylate, the acrylic acid monomer is methacrylic acid, the emulsifier is sodium dodecyl sulfate, and the initiator is ammonium persulfate. The initiator is pre-dissolved in 0.5 L of water to obtain an initiator solution for use.

[0071] Disperse 50 wt% of the emulsifier evenly in 6.5 L of water, then add the amino ester product, hydroxy acrylate monomer and acrylic acid monomer to mix, heat to 75°C, gradually add the initiator solution to react, the initiator is added within 2 hours, the remaining emulsifier is added 1 hour after the initiator is added, and the reaction is continued for 3 hours after the initiator is added. After the reaction is completed, cool and cool, and adjust the pH of the reaction system to 7 with ammonia water to obtain a hydroxy acrylate emulsion.

[0072] Comparative Example 4 The difference between this comparative example and Example 1 lies in the difference in hydroxy acrylate emulsion. Specifically: Weigh 0.78 kg of hydroxyethyl acrylate and 0.75 kg of benzyl isocyanate.

[0073] Hydroxyethyl acrylate and benzyl isocyanate were added into a reaction container and mixed, and heated to 70° C. for reaction. The reaction was stopped when the -NCO content in the reaction system was less than 0.1%, thereby obtaining an amino ester product.

[0074] Weigh 5 kg of hydroxy acrylate monomer, 0.4 kg of acrylic acid monomer, 0.25 kg of emulsifier, and 30 g of initiator. The hydroxy acrylate monomer is hydroxyethyl acrylate, the acrylic acid monomer is methacrylic acid, the emulsifier is sodium dodecyl sulfate, and the initiator is ammonium persulfate. The initiator is pre-dissolved in 0.5 L of water to obtain an initiator solution for use.

[0075] Disperse 50 wt% of the emulsifier evenly in 6.5 L of water, then add the amino ester product, hydroxy acrylate monomer and acrylic acid monomer to mix, heat to 75°C, gradually add the initiator solution to react, the initiator is added within 2 hours, the remaining emulsifier is added 1 hour after the initiator is added, and the reaction is continued for 3 hours after the initiator is added. After the reaction is completed, cool and cool, and adjust the pH of the reaction system to 7 with ammonia water to obtain a hydroxy acrylate emulsion.

[0076] Performance test barrier property: refer to the test methods ASTM D-3985 and ASTM F-1249 to test the oxygen permeability and water vapor permeability of the aluminum oxide film. The results are shown in Table 1.

[0077] Thermal stability: Referring to the test method ASTM D-1204, the thermal shrinkage of the aluminum oxide film was tested, including the longitudinal thermal shrinkage and the transverse thermal shrinkage. The test conditions were 150°C and 30 minutes. The results are shown in Table 2.

[0078] 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 2.

[0079] Table 1 <![CDATA[Oxygen transmission rate (cc / m 3 ·24h)]]> <![CDATA[Water vapor transmission rate (g / m 3 ·24h)]]> Example 1 0.11 0.09 Example 2 0.15 0.11 Example 3 0.14 0.11 Comparative Example 1 0.96 0.72 Comparative Example 2 0.80 0.39 Comparative Example 3 0.64 0.52 Comparative Example 4 0.43 0.31 Table 2 Combining the analysis of Table 1 and Table 2, the aluminum oxide-coated film prepared in Example 1 and Example 2 has low oxygen permeability and water vapor permeability, has excellent oxygen barrier and moisture barrier properties, meets the packaging requirements of photovoltaic modules, and plays a good protective role for solar cells. At the same time, it has low thermal shrinkage and high tensile strength, making the aluminum oxide-coated film suitable for a wider range of application scenarios.

[0080] Compared with Comparative Examples 1-3, the oxygen permeability and water vapor permeability of the aluminum oxide-coated film prepared in Example 1 are significantly reduced, and the advantages of oxygen barrier and moisture barrier properties are obvious, indicating that the present application first uses cinnamyl alcohol and long-chain isocyanate to react to generate an amino ester product, and then polymerizes hydroxy acrylate to obtain a hydroxy acrylate emulsion, and then prepares a polyurethane coating that can form a dense and stable coating, which is more in line with the requirements for photovoltaic module packaging than using commercially available hydroxy acrylate emulsions to prepare polyurethane coatings.

[0081] Compared with Comparative Example 4, the oxygen permeability and water vapor permeability of the aluminum oxide-coated film prepared in Example 1 are reduced, the oxygen barrier and moisture barrier properties are better, and the thermal shrinkage rate is significantly reduced, indicating that the thermal stability of the aluminum oxide-coated film is improved and is suitable for more complex and demanding application functional scenarios.

[0082] Compared with Example 3, the overall performance of the aluminum oxide film prepared in Example 1 is better, indicating that when the long-chain isocyanate is preferably dodecyl isocyanate, the coating structure is denser and more stable.

[0083] 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 such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A high barrier encapsulation aluminum oxide film, characterized in that: It comprises a substrate, one side of which is alternately provided with a plurality of polyurethane coatings and a plurality of aluminum oxide coatings, wherein the layer structure closest to the substrate and the layer structure farthest from the substrate are both the polyurethane coatings; The polyurethane coating is formed by curing a polyurethane coating, wherein the polyurethane coating comprises a hydroxy acrylate emulsion, an isocyanate curing agent, an auxiliary agent and water; The hydroxy acrylate emulsion is obtained by reacting cinnamyl alcohol with long-chain isocyanate, and then the generated amino ester product is polymerized with hydroxy acrylate monomer and acrylic acid monomer.

2. The aluminum oxide film for high barrier packaging according to claim 1, characterized in that: The hydroxy acrylate emulsion is prepared from the following raw materials in parts by weight: 50-60 parts of hydroxy acrylate monomer; 4-8 parts of acrylic acid monomer; 12-18 parts of long-chain isocyanate; 9-14 parts of cinnamyl alcohol; Emulsifier 2.5~4 parts; Initiator 0.3~0.8 parts; 70~80 parts of water.

3. The aluminum oxide film for high barrier packaging according to claim 1, characterized in that: The long-chain isocyanate is selected from one or more of dodecyl isocyanate, tetradecyl isocyanate, hexadecyl isocyanate and octadecyl isocyanate.

4. The aluminum oxide film for high barrier packaging according to claim 1, characterized in that: The polyurethane coating comprises the following raw materials in parts by weight: 60-70 parts of hydroxy acrylate emulsion; 5.5~7 parts of isocyanate curing agent; 1~2.5 parts of additives; 20-30 parts water; The auxiliary agent is selected from one or both of a leveling agent and a thickener.

5. The aluminum oxide film for high barrier packaging according to claim 1, characterized in that: The isocyanate curing agent is a water-dispersible polyisocyanate based on hexamethylene diisocyanate.

6. The high barrier encapsulation aluminum oxide film 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 high barrier 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 a high barrier encapsulation aluminum oxide film according to any one of claims 1 to 7, characterized in that: The following steps are involved: The cinnamyl alcohol and the long-chain isocyanate are mixed, heated to react, and the reaction is stopped when the -NCO content in the reaction system is less than 0.1%, thereby obtaining an amino ester product; Dispersing part of the emulsifier in water uniformly, then adding the amino ester product, hydroxy acrylate monomer and acrylic acid monomer to mix, heating, gradually adding the initiator to react, adding the remaining emulsifier, and adjusting the pH to neutral after the reaction to obtain a hydroxy acrylate emulsion; The hydroxy acrylate emulsion is mixed with an isocyanate curing agent, an auxiliary agent and water, and stirred evenly to obtain a polyurethane coating; Applying polyurethane coating on one side of the substrate, drying and curing to form a polyurethane coating; Vacuum evaporation of aluminum oxide is performed on the surface of the polyurethane coating to form an aluminum oxide coating, which is then dried and solidified; Applying polyurethane coating on the surface of the aluminum oxide coating, drying and curing, and forming a polyurethane coating; According to the needs, a required number of polyurethane coatings and aluminum oxide coatings are formed on one side of the substrate to obtain an aluminum oxide coating film for high barrier packaging.

9. The method for preparing a high-barrier encapsulation aluminum oxide film according to claim 8, characterized in that: The temperature of the curing process after applying the polyurethane coating is 70~120℃.

10. The method for preparing a high-barrier encapsulation aluminum oxide film 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 150~180mm / min, and the flow rate of oxygen is 8700~10000sccm.

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