Aluminum oxide film for high barrier packaging and preparation method thereof

Abstract

The present application discloses an aluminum oxide-coated film for high-barrier packaging and a preparation method thereof, belonging to the field of thin films. An aluminum oxide-coated film for high-barrier packaging comprises a substrate, one side of which is alternately provided with multiple polyurethane coatings and multiple aluminum oxide coatings, wherein the layer structure closest to the substrate and the layer structure farthest from the substrate are both polyurethane coatings; the polyurethane coating is formed by curing a polyurethane coating, and the polyurethane coating contains a hydroxy acrylate emulsion, an isocyanate curing agent, an auxiliary agent and water; the hydroxy acrylate emulsion is reacted with cinnamyl alcohol and a long-chain isocyanate, and the resulting amino ester product is then polymerized with a hydroxy acrylate monomer and an acrylic acid monomer to obtain the result. The present application has the advantages of reducing the difficulty of producing solar backsheets and maintaining high barrier properties.

Description

Technical Field

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

[0002] Globally, the photovoltaic power generation market continues to expand, and the demand for the production and quality of photovoltaic modules continues to increase. Solar panels, one of the core components of photovoltaic power generation, typically consist of photovoltaic glass, EVA, solar cells, EVA, and a solar backsheet. The solar backsheet is the encapsulation material located on the back of the solar panel, providing protection and support for the cells.

[0003] Solar backsheet materials are generally composed of three layers of co-extruded composite film. Taking BBF solar backsheet 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 solar cells.

[0004] Due to the complexity of the three-layer co-extrusion composite film technology and the high requirements for extrusion equipment and control technology, production is difficult. Currently, only a few manufacturers have mastered the solar backsheet production technology, affecting the wider application of solar backsheets. Summary of the Invention

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

[0006] In a 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 multiple polyurethane coatings and multiple aluminum oxide coatings, wherein the layer structure closest to the substrate and the layer structure farthest from the substrate are both the polyurethane coatings;

[0007] 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;

[0008] The hydroxy acrylate emulsion is obtained by reacting cinnamyl alcohol with long-chain isocyanate, and then polymerizing the generated amino ester product with hydroxy acrylate monomer and acrylic acid monomer.

[0009] By employing this technical solution, the substrate surface is modified with multiple aluminum oxide layers and a polyurethane coating. The resulting aluminum oxide layers have a dense structure and excellent moisture and gas barrier properties. This aluminum oxide film, used as a solar backsheet, improves resistance to environmental interference, effectively protecting the cells from moisture corrosion and extending the lifespan of photovoltaic modules. Compared to three-layer co-extruded films, films modified with multiple aluminum oxide layers and a polyurethane coating offer the same protection for photovoltaic modules and are simpler to manufacture. Conventional equipment and processes can meet these requirements, reducing equipment investment costs and simplifying production.

[0010] The polyurethane coating is formed by curing a polyurethane coating. The polyurethane coating utilizes a two-component film-forming process and boasts a high degree of crosslinking. The amino ester product formed by the reaction of cinnamyl alcohol with a long-chain isocyanate has a carbon-carbon double bond. This product is then polymerized with a hydroxyacrylate monomer and an acrylic acid monomer to form a polyol. The two-component mixing of the hydroxyacrylate emulsion and the isocyanate curing agent allows for crosslinking and curing, significantly improving adhesion between the aluminum oxide coating and the substrate, and between the aluminum oxide coatings. Furthermore, the introduction of benzene rings by the cinnamyl alcohol further stabilizes the crosslinked molecular segments, reducing gaps caused by the mobility of the crosslinked molecular segments and enhancing gas barrier properties. Furthermore, the long-chain isocyanate introduces a long-chain hydrophobic structure, imparting excellent hydrophobic and water-blocking properties to each layer of the polyurethane coating. These two factors work synergistically to provide the polyurethane coating with excellent moisture and gas barrier properties. Furthermore, since the amino ester forms a bond between the benzene ring and the long-chain alkyl group after the reaction of cinnamyl alcohol with the long-chain isocyanate, and the site of polymerization with the acrylate is also located between the benzene ring and the long-chain alkyl group, the amino ester and the polyurethane share similar segments, enhancing the thermal stability of the crosslinked structure.

[0011] Optionally, the hydroxyacrylate emulsion is prepared from the following raw materials in parts by weight:

[0012] 50-60 parts of hydroxy acrylate monomer;

[0013] 4-8 parts of acrylic acid monomer;

[0014] 12-18 parts of long-chain isocyanate;

[0015] 9-14 parts of cinnamyl alcohol;

[0016] 2.5-4 parts of emulsifier;

[0017] 0.3-0.8 parts of initiator;

[0018] 70-80 parts of water.

[0019] By adopting the above technical solution, 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 bonding strength to the aluminum oxide coating and enhance the water dispersibility. The excessive amount of cinnamyl alcohol ensures the complete reaction of the long-chain isocyanate, and the resulting 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.

[0020] Optionally, the hydroxyacrylate is selected from one or more of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate and hydroxypropyl methacrylate.

[0021] Optionally, the acrylic acid monomer is one or both of acrylic acid and methacrylic acid.

[0022] Optionally, the long-chain isocyanate is selected from one or more of dodecyl isocyanate, tetradecyl isocyanate, hexadecyl isocyanate and octadecyl isocyanate.

[0023] By adopting the above technical solution, the above-mentioned long-chain isocyanate can bring terminal hydrophobic properties and improve the moisture barrier ability. Among them, the chain segment length of dodecyl isocyanate is moderate, which not only provides hydrophobic barrier but also avoids the influence of excessively long chain segments on the stability of the cross-linking structure, and performs better in terms of thermal shrinkage.

[0024] Optionally, the polyurethane coating comprises the following raw materials in parts by weight:

[0025] 60-70 parts of hydroxy acrylate emulsion;

[0026] 5.5-7 parts of isocyanate curing agent;

[0027] 1 to 2.5 parts of additives;

[0028] 20-30 parts water;

[0029] The auxiliary agent is selected from one or both of a leveling agent and a thickener.

[0030] 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.

[0031] Optionally, the isocyanate curing agent is a water-dispersible polyisocyanate based on hexamethylene diisocyanate.

[0032] By adopting the above technical solution, 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.

[0033] Optionally, the substrate is a PET film or a BOPET film.

[0034] Optionally, the thickness of the aluminum oxide coating is 100 to 150 angstroms.

[0035] Optionally, the polyurethane coating is provided with three layers, and the aluminum oxide coating is provided with two layers.

[0036] Optionally, the polyurethane coating has a thickness of 0.1 to 0.3 μm.

[0037] In a second aspect, the present application provides a method for preparing an aluminum oxide film for high-barrier packaging using the following technical solutions:

[0038] A method for preparing an aluminum oxide film for high-barrier packaging, comprising the following steps:

[0039] Mixing cinnamyl alcohol and long-chain isocyanate, heating the mixture to react at 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;

[0040] Dispersing part of the emulsifier evenly in water, then adding the amino ester product, hydroxy acrylate monomer and acrylic acid monomer, mixing, 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;

[0041] The hydroxy acrylate emulsion is mixed with an isocyanate curing agent, an additive and water, and stirred evenly to obtain a polyurethane coating;

[0042] Applying polyurethane coating on one side of the substrate, drying and curing to form a polyurethane coating;

[0043] 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;

[0044] Applying polyurethane coating on the surface of the aluminum oxide coating, drying and curing it to form a polyurethane coating;

[0045] According to 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.

[0046] 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 surface structure of the film and high barrier properties.

[0047] Optionally, the temperature of the curing process after applying the polyurethane coating is 70-120°C.

[0048] 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.

[0049] 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 oxygen gas is 8700-10000 sccm.

[0050] 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.

[0051] In summary, this application has the following beneficial effects:

[0052] 1. The aluminum oxide film of this application modifies the surface of a substrate with multiple aluminum oxide layers and a polyurethane coating. The aluminum oxide layers have a dense structure and excellent moisture and gas barrier capabilities. As a solar backsheet, the aluminum oxide film can improve resistance to environmental interference, protect solar cells from moisture corrosion, and extend the service life of photovoltaic modules. Compared with three-layer co-extruded films, films modified with multiple aluminum oxide layers and polyurethane coatings can also protect photovoltaic modules and are simpler in preparation. Traditional equipment and processes can meet preparation requirements, reducing equipment investment costs and production difficulty.

[0053] 2. The polyurethane coating is formed by curing a polyurethane coating. This coating utilizes a two-component film-forming process and boasts a high degree of crosslinking. The amino ester product formed by the reaction of cinnamyl alcohol with a long-chain isocyanate has a carbon-carbon double bond. This product is then polymerized with a hydroxy acrylate monomer and an acrylic acid monomer to form a polyol. The two-component mixture of the hydroxy acrylate emulsion and the isocyanate curing agent allows for crosslinking and curing, significantly improving adhesion between the aluminum oxide coating and the substrate, and between the aluminum oxide coatings. Furthermore, the introduction of benzene rings by the cinnamyl alcohol further stabilizes the crosslinked molecular segments, reducing gaps caused by crosslinking and improving gas barrier properties. Furthermore, the long-chain isocyanate introduces a long-chain hydrophobic structure, imparting excellent hydrophobic and water-blocking properties to each layer of the polyurethane coating. These two factors work synergistically to provide the polyurethane coating with excellent moisture and gas barrier properties. In addition, since the benzene ring and the long-chain alkyl group 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 group, amino ester and polyurethane have similar chain segments, which improves the thermal stability of the cross-linked structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 This is a planar structural diagram of the aluminum oxide film for high-barrier packaging in Example 1 of the present application.

[0055] Description of reference numerals:

[0056] 1. Substrate; 2. Polyurethane coating; 3. Aluminum oxide coating. DETAILED DESCRIPTION

[0057] The following is combined with Figure 1 This application is described in further detail.

[0058] Example 1

[0059] A high barrier encapsulation aluminum oxide film, such as Figure 1 As shown, the present invention comprises a substrate 1, with a plurality of polyurethane coatings 2 and a plurality of aluminum oxide coatings 3 alternately disposed 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 disposed and two aluminum oxide coatings 3 are disposed.

[0060] A method for preparing an aluminum oxide film for high-barrier packaging, comprising the following steps:

[0061] Weigh 0.9 kg of cinnamyl alcohol and 1.2 kg of long-chain isocyanate, wherein the long-chain isocyanate is dodecyl isocyanate.

[0062] Cinnamyl alcohol and long-chain isocyanate are added to a reaction vessel 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.

[0063] Weigh 5 kg of hydroxyacrylate monomer, 0.4 kg of acrylic acid monomer, 0.25 kg of emulsifier, and 30 g of initiator. The hydroxyacrylate monomer is hydroxyethyl acrylate, the acrylic acid monomer is methacrylic acid, the emulsifier is sodium lauryl sulfate, and the initiator is ammonium persulfate. Pre-dissolve the initiator in 0.5 L of water to obtain an initiator solution for later use.

[0064] 50 wt% of the emulsifier was evenly dispersed in 6.5 L of water, and then the amino ester product, hydroxy acrylate monomer and acrylic acid monomer were added and mixed. The temperature was raised to 75°C, and the initiator solution was gradually added dropwise to react. The initiator was added dropwise within 2 hours. The remaining emulsifier was added 1 hour after the initiator was added dropwise. After the initiator was added dropwise, the reaction was continued for 3 hours. After the reaction was completed, the temperature was cooled and the pH of the reaction system was adjusted to 7 with ammonia water to obtain a hydroxy acrylate emulsion.

[0065] Weigh 6 kg of hydroxyacrylate 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.

[0066] The hydroxy acrylate emulsion, isocyanate curing agent, leveling agent, thickener and water are mixed and stirred evenly to obtain a polyurethane coating.

[0067] A substrate is taken, specifically a PET film with a thickness of 25 μm.

[0068] 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.

[0069] 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℃, the wire feeding speed of the aluminum wire is 150mm / min, and the flow rate of the oxygen is 8700sccm to form an aluminum oxide coating with a thickness of 100 angstroms. It is then dried and cured in a 60℃ oven for 72 hours.

[0070] Polyurethane coating is applied 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.

[0071] Aluminum oxide was vacuum evaporated on the surface of the polyurethane coating prepared in the previous step, and the above steps of forming the aluminum oxide coating were repeated to form an aluminum oxide coating having a thickness of 100 angstroms.

[0072] Polyurethane coating is applied 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 preparing an aluminum oxide film for high barrier packaging.

[0073] Example 2

[0074] The difference between this embodiment and embodiment 1 lies in the different preparation methods.

[0075] A method for preparing an aluminum oxide film for high-barrier packaging, comprising the following steps:

[0076] Weigh 1.4 kg of cinnamyl alcohol and 1.8 kg of long-chain isocyanate, wherein the long-chain isocyanate is dodecyl isocyanate.

[0077] Cinnamyl alcohol and long-chain isocyanate are added to a reaction vessel 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.

[0078] Weigh 6 kg of hydroxyacrylate monomer, 0.8 kg of acrylic acid monomer, 0.4 kg of emulsifier, and 80 g of initiator. The hydroxyacrylate monomer is hydroxyethyl acrylate, the acrylic acid monomer is methacrylic acid, the emulsifier is sodium lauryl sulfate, and the initiator is ammonium persulfate. Pre-dissolve the initiator in 0.5 L of water to obtain an initiator solution for later use.

[0079] 50 wt% of the emulsifier was evenly dispersed in 7.5 L of water, and then the amino ester product, hydroxy acrylate monomer and acrylic acid monomer were added and mixed. The temperature was raised to 85° C., and the initiator solution was gradually added dropwise to react. The initiator was added dropwise within 2 hours. The remaining emulsifier was added 1 hour after the initiator was added dropwise. After the initiator was added dropwise, the reaction was continued for 3 hours. After the reaction was completed, the temperature was cooled and the pH of the reaction system was adjusted to 7 with ammonia water to obtain a hydroxy acrylate emulsion.

[0080] Weigh 7 kg of hydroxyacrylate 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.

[0081] The hydroxy acrylate emulsion, isocyanate curing agent, leveling agent, thickener and water are mixed and stirred evenly to obtain a polyurethane coating.

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

[0083] 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.

[0084] 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 the 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 72 hours.

[0085] Polyurethane coating is applied 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.

[0086] Aluminum oxide was vacuum evaporated on the surface of the polyurethane coating prepared in the previous step, and the above steps of forming the aluminum oxide coating were repeated to form an aluminum oxide coating having a thickness of 100 angstroms.

[0087] Polyurethane coating is applied 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 preparing an aluminum oxide film for high barrier packaging.

[0088] Example 3

[0089] The difference between this embodiment and embodiment 1 lies in the difference in the hydroxy acrylate emulsion.

[0090] In the step of preparing the hydroxy acrylate emulsion, hexadecyl isocyanate is selected as the long-chain isocyanate, and the amount of hexadecyl isocyanate added is 1.52 kg.

[0091] Comparative Example 1

[0092] The difference between this comparative example and Example 1 lies in the difference in the hydroxyacrylate emulsion.

[0093] The hydroxy acrylate emulsion used in this comparative example is a commercially available hydroxy acrylate emulsion with a hydroxyl value of 3%.

[0094] Comparative Example 2

[0095] The difference between this comparative example and Example 1 lies in the difference in the hydroxy acrylate emulsion. Specifically:

[0096] Weigh 0.78 kg of hydroxyethyl acrylate and 1.2 kg of long-chain isocyanate, wherein the long-chain isocyanate is dodecyl isocyanate.

[0097] Hydroxyethyl acrylate and long-chain isocyanate were added to a reaction vessel 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.

[0098] Weigh 5 kg of hydroxyacrylate monomer, 0.4 kg of acrylic acid monomer, 0.25 kg of emulsifier, and 30 g of initiator. The hydroxyacrylate monomer is hydroxyethyl acrylate, the acrylic acid monomer is methacrylic acid, the emulsifier is sodium lauryl sulfate, and the initiator is ammonium persulfate. Pre-dissolve the initiator in 0.5 L of water to obtain an initiator solution for later use.

[0099] 50 wt% of the emulsifier was evenly dispersed in 6.5 L of water, and then the amino ester product, hydroxy acrylate monomer and acrylic acid monomer were added and mixed. The temperature was raised to 75°C, and the initiator solution was gradually added dropwise to react. The initiator was added dropwise within 2 hours. The remaining emulsifier was added 1 hour after the initiator was added dropwise. After the initiator was added dropwise, the reaction was continued for 3 hours. After the reaction was completed, the temperature was cooled and the pH of the reaction system was adjusted to 7 with ammonia water to obtain a hydroxy acrylate emulsion.

[0100] Comparative Example 3

[0101] The difference between this comparative example and Example 1 lies in the difference in the hydroxy acrylate emulsion. Specifically:

[0102] 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.

[0103] Cinnamyl alcohol and short-chain isocyanate are added to a reaction vessel 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% to obtain an amino ester product.

[0104] Weigh 5 kg of hydroxyacrylate monomer, 0.4 kg of acrylic acid monomer, 0.25 kg of emulsifier, and 30 g of initiator. The hydroxyacrylate monomer is hydroxyethyl acrylate, the acrylic acid monomer is methacrylic acid, the emulsifier is sodium lauryl sulfate, and the initiator is ammonium persulfate. Pre-dissolve the initiator in 0.5 L of water to obtain an initiator solution for later use.

[0105] 50 wt% of the emulsifier was evenly dispersed in 6.5 L of water, and then the amino ester product, hydroxy acrylate monomer and acrylic acid monomer were added and mixed. The temperature was raised to 75°C, and the initiator solution was gradually added dropwise to react. The initiator was added dropwise within 2 hours. The remaining emulsifier was added 1 hour after the initiator was added dropwise. After the initiator was added dropwise, the reaction was continued for 3 hours. After the reaction was completed, the temperature was cooled and the pH of the reaction system was adjusted to 7 with ammonia water to obtain a hydroxy acrylate emulsion.

[0106] Comparative Example 4

[0107] The difference between this comparative example and Example 1 lies in the difference in the hydroxy acrylate emulsion. Specifically:

[0108] Weigh 0.78 kg of hydroxyethyl acrylate and 0.75 kg of benzyl isocyanate.

[0109] Hydroxyethyl acrylate and benzyl isocyanate were added to a reaction vessel 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.

[0110] Weigh 5 kg of hydroxyacrylate monomer, 0.4 kg of acrylic acid monomer, 0.25 kg of emulsifier, and 30 g of initiator. The hydroxyacrylate monomer is hydroxyethyl acrylate, the acrylic acid monomer is methacrylic acid, the emulsifier is sodium lauryl sulfate, and the initiator is ammonium persulfate. Pre-dissolve the initiator in 0.5 L of water to obtain an initiator solution for later use.

[0111] 50 wt% of the emulsifier was evenly dispersed in 6.5 L of water, and then the amino ester product, hydroxy acrylate monomer and acrylic acid monomer were added and mixed. The temperature was raised to 75°C, and the initiator solution was gradually added dropwise to react. The initiator was added dropwise within 2 hours. The remaining emulsifier was added 1 hour after the initiator was added dropwise. After the initiator was added dropwise, the reaction was continued for 3 hours. After the reaction was completed, the temperature was cooled and the pH of the reaction system was adjusted to 7 with ammonia water to obtain a hydroxy acrylate emulsion.

[0112] 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.

[0113] 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.

[0114] 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.

[0115] Table 1

[0116] <![CDATA[Oxygen Transmission Rate (cc / m 3 ·24h)]]> <![CDATA[Water vapor transmission rate (g / m 3 ·24 h)]]> 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

[0117] Table 2

[0118]

[0119] Combined analysis of Table 1 and Table 2 shows that the aluminum oxide-coated films prepared in Example 1 and Example 2 have low oxygen permeability and water vapor permeability, and have excellent oxygen barrier and moisture barrier properties, meeting the packaging requirements of photovoltaic modules and providing good protection for solar cells. At the same time, the thermal shrinkage is low and the tensile strength is high, making the aluminum oxide-coated films suitable for a wider range of application scenarios.

[0120] 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 form 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. Compared with the use of commercially available hydroxy acrylate emulsion to prepare polyurethane coatings, it is more in line with the requirements for photovoltaic module packaging.

[0121] 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 it is suitable for more complex and demanding application functional scenarios.

[0122] 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.

[0123] 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. A high-barrier aluminum oxide film for packaging, characterized by: The invention comprises a substrate, wherein one side of the substrate 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; The long-chain isocyanate is selected from one or more of dodecyl isocyanate, tetradecyl isocyanate, hexadecyl isocyanate and octadecyl isocyanate.

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; 2.5~4 parts of emulsifier; 0.3~0.8 parts of initiator; 70~80 parts of water.

3. 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.

4. 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.

5. The aluminum oxide film for high barrier packaging according to any one of claims 1 to 4, characterized in that: The substrate is selected from PET film or BOPET film.

6. The aluminum oxide film for high barrier packaging according to any one of claims 1 to 4, characterized in that: The thickness of the aluminum oxide coating is 100-150 angstroms.

7. A method for preparing a high-barrier aluminum oxide film for packaging according to any one of claims 1 to 6, characterized in that: The following steps are involved: Mixing cinnamyl alcohol and long-chain isocyanate, heating and reacting, 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 evenly in water, then adding the amino ester product, hydroxy acrylate monomer and acrylic acid monomer, mixing, 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 additive 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-deposit aluminum oxide 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 it to form a polyurethane coating; According to 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.

8. The method for preparing a high-barrier aluminum oxide film for packaging according to claim 7, characterized in that: The temperature of the curing process after applying the polyurethane coating is 70~120℃.

9. The method for preparing a high-barrier aluminum oxide film for packaging according to claim 7, wherein: 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 the oxygen is 8700~10000sccm.

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