EVA packaging adhesive film and preparation method thereof

Abstract

The invention relates to the technical field of solar cells, in particular to an EVA packaging adhesive film and a preparation method thereof. The EVA packaging adhesive film comprises a core layer adhesive film and a shell layer adhesive film, and the shell layer adhesive film comprises the following raw materials: EVA resin, a water blocking agent and a cross-linking agent; the core layer adhesive film is prepared from the following raw materials: EVA resin, a cross-linking agent, an antioxidant and a light stabilizer; and the core layer adhesive film is positioned in the shell layer adhesive film. The EVA packaging adhesive film can be formed by compounding the shell layer adhesive film and the core layer adhesive film, and the additive in the core layer adhesive film is less, so that the condition that the performance of the EVA packaging adhesive film is reduced due to excessive additive is reduced; the shell layer adhesive film and the core layer adhesive film are made of the same EVA resin, so that the shell layer adhesive film and the core layer adhesive film have good compatible adhesion and strong adhesion stability; the water blocking agent in the shell layer adhesive film can improve the water vapor blocking capability of the EVA packaging adhesive film on one hand, and can improve the bonding strength of the EVA packaging adhesive film on the other hand.

Description

Technical Field

[0001] The present application relates to the technical field of solar cells, and in particular to an EVA encapsulation film and a preparation method thereof. Background Art

[0002] With the development of science and technology and the increase in population, the demand for energy and electricity has also increased significantly. Traditional petroleum fossil resources are non-renewable on the one hand, and the use of traditional petroleum and electricity resources will cause environmental pollution and other problems on the other hand. Therefore, renewable clean energy is supported by more and more countries. Among the many renewable energy technologies, photovoltaic modules can directly convert solar radiation into electrical energy, which is one of the most effective, environmentally friendly and mature technology products.

[0003] As an important component of the component, the encapsulation film plays a bonding and protective role in the component. The most commonly used encapsulation film material is ethylene-vinyl acetate (EVA), but EVA has poor water vapor barrier performance. When water vapor enters the EVA layer, EVA will degrade under sunlight to produce acetic acid and other products, which will further diffuse to the battery layer, causing electrochemical degradation reactions on the battery surface.

[0004] In the related art, waterproofing and water blocking agents are generally mixed with cross-linking agents, antioxidants, light stabilizers, silane coupling agents, etc. and then added to the EVA matrix to improve the water vapor barrier ability of the EVA film. However, the EVA matrix can only accommodate a limited amount of additives. If too much is added, it will cause uneven dispersion in the matrix, affecting the effect of the additives.

[0005] It should be noted that the above content is not necessarily prior art, nor is it intended to limit the scope of patent protection of this application. Summary of the invention

[0006] The embodiments of the present application provide an EVA encapsulation film and a preparation method thereof to solve or alleviate one or more of the technical problems mentioned above.

[0007] In a first aspect, an embodiment of the present application provides an EVA encapsulation film, comprising a core layer film and a shell layer film, wherein the shell layer film comprises the following raw materials in parts by weight: 80 to 100 parts of EVA resin, 5 to 10 parts of a water barrier agent, and 0.2 to 2 parts of a cross-linking agent; The core layer film comprises the following raw materials in parts by weight: 70-100 parts of EVA resin, 0.5-2 parts of cross-linking agent, 0.1-1 parts of antioxidant and 0.1-0.5 parts of light stabilizer; Wherein, the core layer film is located inside the shell layer film.

[0008] Optionally, the water-blocking agent includes silane-modified silica, which is silica modified by a silane coupling agent.

[0009] Optionally, the silane coupling agent includes one or more of ethyltriethoxysilane, phenyltriethoxysilane and perfluorotrimethoxysilane.

[0010] Optionally, the mass ratio of the silane coupling agent to the silicon dioxide is 2:1 to 1:2.

[0011] Optionally, the cross-linking agent includes one or more of di-tert-butyl diisopropyl peroxide, diisopropyl peroxide, tert-butyl peroxycarbonate-2-ethylhexyl ester and di-tert-butyl peroxide.

[0012] Optionally, when the cross-linking agent includes di-tert-butyl diisopropylbenzene peroxide and diisopropylbenzene peroxide, the mass ratio of the di-tert-butyl diisopropylbenzene peroxide to the diisopropylbenzene peroxide is 7:3-5:5.

[0013] Optionally, the antioxidant includes one or more of antioxidant 1076, antioxidant 1010, tris(2,4-di-tert-butylphenyl) phosphite, and ß-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate.

[0014] Optionally, the light stabilizer includes one or more of 2,2-dihydroxy-4-methoxybenzophenone, bis(2,2,6,6-tetramethyl-4-piperidinyl)sebacate, and bis(1-octyloxy-2,2,6,6-tetramethyl-4-piperidinyl)sebacate.

[0015] Optionally, the mass ratio of the core layer film to the shell layer film is (4~5):1.

[0016] In a second aspect, an embodiment of the present application provides a method for preparing an EVA encapsulation film, comprising the following steps: Put 80-100 parts of EVA resin, 5-10 parts of water-blocking agent and 0.2-2 parts of cross-linking agent into a first mixing kettle to obtain a shell film raw material; Put 70-100 parts of EVA resin, 0.5-2 parts of cross-linking agent, 0.1-1 parts of antioxidant and 0.1-0.5 parts of light stabilizer into a second mixing kettle to obtain a core layer film raw material; The shell layer film raw material is put into the first mixing kettle for melting, and then extruded through the first extruder to obtain a pre-shell layer film; the core layer film raw material is put into the second mixing kettle for melting, and then extruded through the second extruder to obtain a pre-core layer film; the pre-shell layer film and the pre-core layer film are then extruded through a coaxial co-extrusion device to obtain an extrudate, and the extrudate is sequentially cast, cooled, pulled, and curled to obtain an EVA packaging film.

[0017] Optionally, the water blocking agent is silane-modified silica; The preparation method of the silane-modified silicon dioxide comprises: The silicon dioxide is placed in a vacuum oven and baked; Adding a silane coupling agent into an acetone solution and stirring to obtain a mixed solution; After the pH of the mixed solution is adjusted, the silicon dioxide particles are added to the pH-adjusted mixed solution and ultrasonically dispersed; The mixed solution after ultrasonic dispersion is subjected to centrifugal filtration and drying treatment in sequence to obtain silane-modified silicon dioxide.

[0018] Optionally, the mass ratio of the silane coupling agent to the acetone solution is 1:(3-5).

[0019] The above technical solution adopted in the embodiment of the present application may have the following advantages: The shell layer film and the core layer film are compounded to form an EVA encapsulation film. The core layer film contains fewer additives, which reduces the performance degradation of the EVA encapsulation film caused by excessive additives. Since the shell layer film and the core layer film use the same EVA resin, they have good compatible adhesion and strong bonding stability. The water barrier in the shell layer film can improve the water vapor barrier ability of the EVA encapsulation film on the one hand, and improve the bonding strength of the EVA encapsulation film on the other hand. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In the accompanying drawings, unless otherwise specified, the same reference numerals throughout the multiple drawings represent the same or similar parts or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings only depict some embodiments disclosed in the present application and should not be regarded as limiting the scope of the present application.

[0021] Figure 1 It is a schematic diagram of the structure of the EVA encapsulation film provided in the embodiment of the present application.

[0022] Description of reference numerals: 1. Core layer film; 2. Shell layer film. DETAILED DESCRIPTION

[0023] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings. In the accompanying drawings, for clarity, the sizes of layers, regions, elements and their relative sizes may be exaggerated. Wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limitations on the present application. It should be noted that, in the absence of conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

[0024] It should be understood that when an element or layer is referred to as "on ...", "adjacent to ...", "connected to" or "coupled to" other elements or layers, it can be directly on, adjacent to, connected to or coupled to other elements or layers, or there can be intervening elements or layers. On the contrary, when an element is referred to as "directly on ...", "directly adjacent to ...", "directly connected to" or "directly coupled to" other elements or layers, there is no intervening element or layer. It should be understood that although the terms first, second, third, etc. can be used to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings of the present disclosure, the first element, component, region, layer or part discussed below can be represented as the second element, component, region, layer or part. And when the second element, component, region, layer or part is discussed, it does not indicate that the present application discloses the existence of the first element, component, region, layer or part.

[0025] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0026] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein, for example. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0027] In the present application, when it comes to a numerical interval (i.e., a numerical range), unless otherwise specified, the distribution of the optional numerical values ​​in the numerical interval is considered to be continuous, and includes the two numerical endpoints (i.e., the minimum and maximum values) of the numerical interval, and each numerical value between the two numerical endpoints. Unless otherwise specified, when the numerical interval only refers to an integer in the numerical interval, it includes the two endpoint integers of the numerical range, and each integer between the two endpoints, which is equivalent to directly listing each integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be merged. In other words, unless otherwise specified, the numerical range disclosed in the present application should be understood to include any and all sub-ranges included therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, a percentage, a ratio, etc. "Numerical interval" allows for broadly including quantitative intervals such as percentage intervals, ratio intervals, and ratio intervals.

[0028] Hereinafter, exemplary embodiments according to the present application will be described in more detail with reference to the accompanying drawings. It should be noted that these exemplary embodiments can be implemented in many different forms and should not be construed as being limited to the embodiments described herein.

[0029] In the first aspect, an embodiment of the present application provides an EVA encapsulation film, comprising a core layer film and a shell layer film, wherein the shell layer film comprises the following raw materials in parts by weight: 80 to 100 parts of EVA resin, 5 to 10 parts of a water barrier and 0.2 to 2 parts of a cross-linking agent; the core layer film comprises the following raw materials in parts by weight: 70 to 100 parts of EVA resin, 0.5 to 2 parts of a cross-linking agent, 0.1 to 1 parts of an antioxidant and 0.1 to 0.5 parts of a light stabilizer; wherein the core layer film is located inside the shell layer film.

[0030] In this embodiment, the shell film and the core film are compounded to form an EVA encapsulation film, and the core film contains fewer additives, which reduces the performance degradation of the EVA encapsulation film due to excessive additives; since the shell film and the core film use the same EVA resin, they have good compatibility and adhesion, and the bonding stability of the two is strong; the water-blocking agent in the shell film can improve the ability of the EVA encapsulation film to block water vapor on the one hand, and on the other hand, it can improve the bonding strength of the EVA encapsulation film. In addition, the water-blocking agent is added to the shell film to improve the overall water vapor barrier and bonding strength of the EVA encapsulation film. The core film does not contain a water-blocking agent, which can reduce the types and contents of additives in the core film, reduce the performance degradation of the EVA encapsulation film due to excessive additives, and can also enable other additives in the core film to play a better role, thereby improving the overall performance of the EVA encapsulation film.

[0031] In an optional embodiment, the water-blocking agent includes silane-modified silica, and the silane-modified silica is silica modified by a silane coupling agent.

[0032] In this embodiment, the water-blocking agent is silane-modified silica, which is added to the shell layer film, and the shell layer film wraps the core layer film. The silane-modified silica makes the shell layer film have excellent water vapor barrier effect on the one hand, and effectively improves the bonding strength between the EVA encapsulation film and the glass and the back panel on the other hand.

[0033] In an optional embodiment, the silane coupling agent includes one or more of ethyltriethoxysilane, phenyltriethoxysilane and perfluorotrimethoxysilane.

[0034] In this embodiment, the above-mentioned silane coupling agent is used to modify silica, which can effectively improve the dispersibility of silica and reduce the agglomeration of silica in the shell film; and ethyltriethoxysilane can effectively improve the interfacial compatibility of silica; phenyltriethoxysilane has an aromatic ring structure, which can improve the compatibility of silica with organic materials while also improving the mechanical and thermal stability of silica; perfluorotrimethoxysilane has a perfluoro group, which can provide silica with good hydrophobicity and oil resistance, and can improve its surface waterproof and oil-proof properties, thereby improving the water vapor barrier effect of the EVA encapsulation film.

[0035] In an optional embodiment, the mass ratio of the silane coupling agent to the silicon dioxide is 2:1 to 1:2.

[0036] In this embodiment, the mass ratio of the silane coupling agent to the silica is 2:1 to 1:2, and the mass ratio range of the two is relatively wide, and the degree of modification can be flexibly adjusted according to demand. When the mass ratio of the silane coupling agent to the silica is 2:1, the surface modification of the silica will be more complete, providing stronger hydrophobicity, chemical stability and other properties, and reducing the phenomenon of silica agglomeration; and when the mass ratio of the silane coupling agent to the silica is 1:2, while providing partial hydrophobicity of the silica, more original silica properties can be maintained, ensuring that the modified silica still has a certain hydrophilicity or surface activity.

[0037] In an optional embodiment, the cross-linking agent includes one or more of di-tert-butyl diisopropyl peroxide, diisopropyl peroxide, tert-butyl peroxycarbonate-2-ethylhexyl ester and di-tert-butyl peroxide.

[0038] In this embodiment, the cross-linking agent will decompose and produce free radicals during the processing, which will trigger a cross-linking reaction of the EVA resin molecules to form a three-dimensional network structure, thereby enhancing the mechanical properties, thermal stability and aging resistance of the EVA resin; at the same time, under the action of the cross-linking agent, the silica modified by the silane coupling agent is easier to combine with the EVA resin, thereby playing a coupling role.

[0039] In an optional embodiment, when the cross-linking agent includes di-tert-butyl diisopropylbenzene peroxide and diisopropylbenzene peroxide, the mass ratio of the di-tert-butyl diisopropylbenzene peroxide to the diisopropylbenzene peroxide is 7:3-5:5.

[0040] In the present embodiment, the above two crosslinking agents both play a crosslinking effect on the EVA resin, but there are differences in the crosslinking process. Di-tert-butyl diisopropylbenzene peroxide has a higher crosslinking efficiency, but its thermal stability is poor and the price is relatively high. Diisopropylbenzene peroxide has a low price and high thermal stability, but the crosslinking effect is poor. It requires a higher temperature and a longer time to achieve the expected crosslinking effect when used alone. Therefore, by regulating the ratio of the two crosslinking agents, the best crosslinking effect is achieved and the production cost is reduced.

[0041] In an optional embodiment, the antioxidant includes one or more of antioxidant 1076, antioxidant 1010, tris(2,4-di-tert-butylphenyl)phosphite, and ß-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate. Antioxidants can improve the stability of the EVA packaging film under long-term high temperature and outdoor environments, prevent the film from deteriorating under long-term ultraviolet irradiation and thermal cycles, and effectively extend the service life of the EVA packaging film.

[0042] In an optional embodiment, the light stabilizer includes one or more of 2,2-dihydroxy-4-methoxybenzophenone, bis(2,2,6,6,-tetramethyl-4-piperidinyl) sebacate, and bis(1-octyloxy-2,2,6,6-tetramethyl-4-piperidinyl) sebacate. The function of the light stabilizer is to improve the tolerance of the EVA encapsulation film to ultraviolet (UV) and visible light, prevent the EVA encapsulation film from photodegradation caused by long-term exposure to sunlight, and ensure that the EVA encapsulation film can maintain good physical properties and long-term stability during use.

[0043] In an optional embodiment, the mass ratio of the core layer film to the shell layer film is (4~5):1.

[0044] In this embodiment, a water-blocking agent is added to the shell layer film, mainly to provide moisture-proof and waterproof properties, while a light stabilizer and an antioxidant are added to the core layer film, providing weather resistance and stability. When the mass ratio of the core layer film to the shell layer film is (4~5):1, and the shell layer film wraps the core layer film, it ensures that the shell layer film plays a protective and waterproof role while not significantly affecting the overall performance of the EVA encapsulation film, and can also protect the core layer film from the influence of the external environment.

[0045] In a second aspect, an embodiment of the present application provides a method for preparing an EVA encapsulation film, comprising the following steps: Put 80-100 parts of EVA resin, 5-10 parts of water-blocking agent and 0.2-2 parts of cross-linking agent into a first mixing kettle to obtain a shell film raw material; Put 70-100 parts of EVA resin, 0.5-2 parts of cross-linking agent, 0.1-1 parts of antioxidant and 0.1-0.5 parts of light stabilizer into a second mixing kettle to obtain a core layer film raw material; The shell layer film raw material is put into the first mixing kettle for melting, and then extruded through the first extruder to obtain a pre-shell layer film; the core layer film raw material is put into the second mixing kettle for melting, and then extruded through the second extruder to obtain a pre-core layer film; the pre-shell layer film and the pre-core layer film are then extruded through a coaxial co-extrusion device to obtain an extrudate, and the extrudate is sequentially cast, cooled, pulled, and curled to obtain an EVA packaging film.

[0046] In this embodiment, the EVA encapsulation film includes a core layer film and a shell layer film. The preparation method of the present application can ensure that the core layer film is located inside the shell layer film, which can effectively improve the problem of too many additives being added to an EVA film, resulting in the performance of the EVA film being degraded due to excessive additive dosage and agglomeration. The preparation method can also achieve mass production and ensure production quality.

[0047] In an optional embodiment, the water blocking agent is silane-modified silica; The preparation method of the silane-modified silicon dioxide comprises: Adding a silane coupling agent into an acetone solution and stirring to obtain a mixed solution; After the pH of the mixed solution is adjusted, silicon dioxide is added to the pH-adjusted mixed solution and ultrasonically dispersed; The mixed solution after ultrasonic dispersion is subjected to centrifugal filtration and drying treatment in sequence to obtain silane-modified silicon dioxide.

[0048] In this embodiment, the preparation method of the present application is adopted to modify silicon dioxide using a silane coupling agent, which effectively improves the water vapor barrier effect of silicon dioxide while also improving the connection strength between the EVA film and the glass and back panel.

[0049] In an optional embodiment, the mass ratio of the silane coupling agent to the acetone solution is 1:(3-5).

[0050] In this embodiment, when the mass ratio of the silane coupling agent to the acetone solution is lower than 1:5, the modification of the silicon dioxide is insufficient, resulting in a poor modification effect; when the mass ratio of the silane coupling agent to the acetone solution is higher than 1:3, the silicon dioxide is excessively modified, reducing the interaction force between silicon dioxide and other materials, and when there is too much silane coupling agent, the silane coupling agents self-polymerize or undergo excessive cross-linking reactions with silicon dioxide, causing the coupling agents in the solution to polymerize into a colloid, affecting the modification effect on silicon dioxide.

[0051] In an optional embodiment, the shell layer film raw material and the core layer film raw material are separately and independently dried at 30° C. to 50° C. for 4 to 5 hours.

[0052] In this embodiment, the cross-linking of EVA resin is relatively sensitive to water vapor. If the shell layer film raw material and the core layer film raw material have a high water content, the cross-linking effect of EVA may deteriorate, and the insufficient cross-linking degree may not achieve the bonding and packaging effect.

[0053] In an optional embodiment, the extrusion temperature of the first extruder is 80-100°C (such as 80°C, 90°C, 100°C), and the screw speed is 400-600rpm (such as 400rpm, 500rpm, 600rpm); the extrusion temperature of the second extruder is 80-100°C (such as 80°C, 90°C, 100°C), and the screw speed is 400-600rpm (such as 400rpm, 500rpm, 600rpm).

[0054] like Figure 1 As shown, the specific structure of an EVA encapsulation film is as follows: The EVA encapsulation film comprises a core film 1 and a shell film 2. A receiving cavity for receiving the core film 1 is formed in the shell film 2. The core film 1 is located in the receiving cavity, so that the shell film 2 wraps the entire core film 1. The distance between the upper surface of the shell film 2 and the upper surface of the core film 1 and the distance between the lower surface of the shell film 2 and the lower surface of the core film 1 are both H. The thickness of the core film 1 is L. The ratio of L to H is 5:1 to 6:1, so that the shell film 2 wraps the entire core film 1, ensuring that the shell film 2 plays a protective and waterproof role, while not significantly affecting the overall performance of the EVA encapsulation film, and can also protect the core film 1 from the influence of the external environment.

[0055] The following specific examples further illustrate the present application, but should not be construed as limiting the present application. Without departing from the spirit and substance of the present application, modifications or replacements made to the methods, steps or conditions of the present application are within the scope of the present application.

[0056] [Preparation Example 1] A specific preparation method of silane-modified silicon dioxide is as follows: The silica was placed in a vacuum oven and baked to remove the surface hydroxyl groups. The oven temperature was 120°C and the baking time was 4 hours. A silane coupling agent is added to the acetone solution, and the mixture is stirred for 20 minutes to obtain a mixed solution, wherein the mass ratio of the silane coupling agent to the acetone solution is 1:5, and the silane coupling agent includes ethyltriethoxysilane and phenyltriethoxysilane, and the mass ratio of the ethyltriethoxysilane to the phenyltriethoxysilane is 1:1; The pH of the mixed solution was adjusted by acetic acid to 6.0, and then the baked silicon dioxide was added to the pH-adjusted mixed solution and ultrasonically dispersed for 30 minutes, wherein the mass ratio of the silane coupling agent to the silicon dioxide was 1:2; The mixed solution after ultrasonic dispersion is subjected to centrifugal filtration and drying treatment in sequence to obtain a pre-product, which is then placed in an oven at 200° C. and baked for 4 hours to obtain silane-modified silica, wherein the silica particle size is 50-300 nm.

[0057] [Preparation Example 2] A specific preparation method of silane-modified silicon dioxide is as follows: The silica was placed in a vacuum oven and baked to remove the surface hydroxyl groups. The oven temperature was 120°C and the baking time was 4 hours. A silane coupling agent is added to the acetone solution, and the mixture is stirred for 20 minutes to obtain a mixed solution, wherein the mass ratio of the silane coupling agent to the acetone solution is 1:4, and the silane coupling agent includes ethyltriethoxysilane and phenyltriethoxysilane, and the mass ratio of the ethyltriethoxysilane to the phenyltriethoxysilane is 1:1; The pH of the mixed solution was adjusted by acetic acid to 5.5, and then the baked silicon dioxide was added to the pH-adjusted mixed solution, and ultrasonic dispersion was performed for 30 minutes, wherein the mass ratio of the silane coupling agent to the silicon dioxide was 1:1; The mixed solution after ultrasonic dispersion is subjected to centrifugal filtration and drying treatment in sequence to obtain a pre-product, which is then placed in an oven at 200° C. and baked for 4 hours to obtain silane-modified silica, wherein the silica particle size is 50-300 nm.

[0058] [Preparation Example 3] A specific preparation method of silane-modified silicon dioxide is as follows: The silica was placed in a vacuum oven and baked to remove the surface hydroxyl groups. The oven temperature was 120°C and the baking time was 4 hours. A silane coupling agent is added to the acetone solution, and the mixture is stirred for 20 minutes to obtain a mixed solution, wherein the mass ratio of the silane coupling agent to the acetone solution is 1:3, and the silane coupling agent includes ethyltriethoxysilane and phenyltriethoxysilane, and the mass ratio of the ethyltriethoxysilane to the phenyltriethoxysilane is 1:1; The pH of the mixed solution was adjusted by acetic acid to 6.5, and then the baked silicon dioxide was added to the pH-adjusted mixed solution, and ultrasonic dispersion was performed for 30 minutes, wherein the mass ratio of the silane coupling agent to the silicon dioxide was 2:1; The mixed solution after ultrasonic dispersion is subjected to centrifugal filtration and drying treatment in sequence to obtain a pre-product, which is then placed in an oven at 200° C. and baked for 4 hours to obtain silane-modified silica, wherein the silica particle size is 50-300 nm.

[0059] [Preparation Example 4] A specific preparation method of silane-modified silicon dioxide is as follows: The silica was placed in a vacuum oven and baked to remove the surface hydroxyl groups. The oven temperature was 120°C and the baking time was 4 hours. The silane coupling agent was added into the acetone solution, and the mixture was stirred for 20 minutes to obtain a mixed solution, wherein the mass ratio of the silane coupling agent to the acetone solution was 1:4, and the silane coupling agent was perfluorotrimethylsiloxane; The pH of the mixed solution was adjusted by acetic acid to 6.0, and then the baked silicon dioxide was added to the pH-adjusted mixed solution and ultrasonically dispersed for 30 minutes, wherein the mass ratio of the silane coupling agent to the silicon dioxide was 1:2; The mixed solution after ultrasonic dispersion is subjected to centrifugal filtration and drying treatment in sequence to obtain a pre-product, which is then placed in an oven at 200° C. and baked for 4 hours to obtain silane-modified silica, wherein the silica particle size is 50-300 nm.

[0060] [Example 1] like Figure 1 As shown, the specific structure of an EVA encapsulation film is as follows: The EVA packaging film comprises a core layer film 1 and a shell layer film 2. A receiving cavity for receiving the core layer film 1 is formed in the shell layer film 2, and the core layer film 1 is located in the receiving cavity.

[0061] The specific preparation method of a preparation method of an EVA encapsulation film is as follows: 100 parts of EVA resin, 10 parts of water-blocking agent and 0.5 parts of cross-linking agent are put into a first mixing kettle to obtain a shell film raw material, and the shell film raw material is dried at a temperature of 50° C. for 4 hours; 100 parts of EVA resin, 1.5 parts of cross-linking agent, 0.5 parts of antioxidant and 0.2 parts of light stabilizer are put into the second mixing kettle to obtain a core layer film raw material, and the core layer film raw material is dried at a temperature of 50° C. for 4 hours; The dried shell layer film raw material is put into the first mixing kettle for melting, and then extruded through the first extruder to obtain a pre-shell layer film; the dried core layer film raw material is put into the second mixing kettle for melting, and then extruded through the second extruder to obtain a pre-core layer film; the pre-shell layer film and the pre-core layer film are then extruded through a coaxial co-extrusion device to obtain an extrudate, and the extrudate is sequentially cast, cooled, pulled, and curled to obtain an EVA encapsulation film (that is, the core layer film is located in the shell layer film); wherein, the temperature of the first extruder and the second extruder are both 90°C, and the screw speed is both 500rpm.

[0062] Among them, the water-blocking agent is the water-blocking agent prepared in Preparation Example 1, the cross-linking agent is diisopropylbenzene peroxide, the antioxidant is antioxidant 1010, the light stabilizer is bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, and the mass ratio of the core layer film to the shell layer film is 4.5:1.

[0063] [Example 2] The difference from Example 1 is that the shell layer film uses 80 parts of EVA resin, 5 parts of water barrier agent and 0.2 parts of cross-linking agent; the core layer film uses 80 parts of EVA resin, 2 parts of cross-linking agent, 1 part of antioxidant and 0.1 part of light stabilizer, and the mass ratio of the core layer film to the shell layer film is 5:1.

[0064] [Example 3] The difference from Example 1 is that the shell layer film uses 90 parts of EVA resin, 8 parts of water barrier agent and 2 parts of cross-linking agent; the core layer film uses 90 parts of EVA resin, 0.5 parts of cross-linking agent, 0.1 parts of antioxidant and 0.5 parts of light stabilizer, and the mass ratio of the core layer film to the shell layer film is 4:1.

[0065] [Example 4] The difference from Example 1 is that the crosslinking agents used in the shell film are di-tert-butyl diisopropylbenzene peroxide and diisopropylbenzene peroxide, and the mass ratio of di-tert-butyl diisopropylbenzene peroxide to diisopropylbenzene peroxide is 7:3.

[0066] [Example 5] - [Example 7] The difference from Example 1 is that the water-blocking agent used in Example 5 is the water-blocking agent prepared in Preparation Example 2; The difference from Example 1 is that the water-blocking agent used in Example 6 is the water-blocking agent prepared in Preparation Example 3; The difference from Example 1 is that the water-blocking agent used in Example 7 is the water-blocking agent prepared in Preparation Example 4; [Comparative Example 1] The difference from Example 1 is that the water-blocking agent used in the shell layer film of Comparative Example 1 is polytetrafluoroethylene micropowder and nano-titanium dioxide, and the mass ratio of polytetrafluoroethylene micropowder to nano-titanium dioxide is 4:1-5:1.

[0067] [Comparative Example 2] The difference from Example 1 is that the water-blocking agent used in the shell layer film of Comparative Example 1 is silicon dioxide that has not been modified by a silane coupling agent.

[0068] [Comparative Example 3] The specific preparation method of a preparation method of an EVA encapsulation film is as follows: Put EVA resin (100 parts), cross-linking agent DCP (1 part), water-blocking agent (5 parts), antioxidant 1010 (1 part) and light stabilizer (0.5 parts) into a mixing kettle at the same time; the water-blocking agent is the water-blocking agent prepared in Preparation 1; After the raw materials in the mixing kettle are mixed evenly, they are extruded through an extruder, and then cast, cooled, pulled, and curled to obtain an EVA packaging film. The extruder temperature is 90° C. and the screw speed is 500 rpm.

[0069] The following is a performance test of the EVA encapsulation films provided in Examples 1 to 7 of the present application and Comparative Examples 1 to 3, and the test results are shown in Table 1.

[0070] Table 1: Test data of EVA packaging films prepared in Examples 1-7 and Comparative Examples 1-3

[0071] It can be seen from Table 1 that, compared with Comparative Examples 1 to 3, the EVA encapsulation films of Examples 1 to 7 are formed by combining a shell layer film and a core layer film, which reduces the performance degradation of the EVA encapsulation film due to excessive additives. In addition, a water-blocking agent is added to the shell layer film, which can improve the water-blocking strength and bonding strength of the EVA encapsulation film.

[0072] Combining Examples 1 to 7, Comparative Examples 1 to 2 and Table 1, it can be seen that the common water-blocking agent is used in Comparative Example 1, and the unmodified silica is used in Comparative Example 2. Therefore, the water-blocking effect of the EVA encapsulation film obtained in Comparative Examples 1 and 2 is poor. In Examples 1 to 7, by adding silica modified by a silane coupling agent, the water vapor permeability of the EVA encapsulation film is significantly reduced, and the peel strength is enhanced. This shows that the modified silica water-blocking agent has stronger water-blocking and adhesion properties for the EVA encapsulation film.

[0073] Combining Examples 1 to 7, Comparative Example 3 and Table 1, it can be seen that Comparative Example 3 is a single-layer EVA encapsulation film, and its water barrier and adhesion effects are poor, which shows that the core-shell film used in this application can better play a role in water barrier and adhesion. At the same time, it can be seen that the modified silica and the core-shell film will not affect the relatively good light transmittance and elastic modulus of the overall EVA encapsulation film.

[0074] It should be noted that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. The orientation words "inside" and "outside" refer to the inside and outside relative to the outline of each component itself. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Therefore, the exemplary term "above..." can include both "above..." and "below..." orientations. The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used here are interpreted accordingly.

[0075] It should also be noted that "one embodiment", "another embodiment", "embodiment", etc. mentioned in this application refer to the specific features, structures or characteristics described in conjunction with the embodiment included in at least one embodiment generally described in this application. The same expression appearing in multiple places in the specification does not necessarily refer to the same embodiment. Further, when describing a specific feature, structure or characteristic in conjunction with any embodiment, it is claimed that the realization of such feature, structure or characteristic in conjunction with other embodiments also falls within the scope of this application.

[0076] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0077] It should also be noted that the above are only preferred embodiments of the present application, and the patent protection scope of the present application is not limited thereto. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. An EVA encapsulation film, characterized in that: It comprises a core layer film and a shell layer film, wherein the shell layer film comprises the following raw materials in parts by weight: 80-100 parts of EVA resin, 5-10 parts of water blocking agent and 0.2-2 parts of cross-linking agent; The core layer film comprises the following raw materials in parts by weight: 70-100 parts of EVA resin, 0.5-2 parts of cross-linking agent, 0.1-1 parts of antioxidant and 0.1-0.5 parts of light stabilizer; Wherein, the core layer film is located inside the shell layer film.

2. The EVA encapsulation film according to claim 1, characterized in that: The water-blocking agent includes silane-modified silica, which is silica modified by a silane coupling agent.

3. The EVA encapsulation film according to claim 2, characterized in that: The silane coupling agent includes one or more of ethyltriethoxysilane, phenyltriethoxysilane and perfluorotrimethoxysilane.

4. The EVA encapsulation film according to claim 2, characterized in that: The mass ratio of the silane coupling agent to the silicon dioxide is 2:1 to 1:

2.

5. The EVA encapsulation film according to claim 1, characterized in that: The crosslinking agent includes one or more of di-tert-butyl diisopropyl peroxide, diisopropyl peroxide, tert-butyl peroxycarbonate-2-ethylhexyl ester and di-tert-butyl peroxide.

6. The EVA encapsulation film according to claim 5, characterized in that: When the cross-linking agent includes di-tert-butyl diisopropylbenzene peroxide and diisopropylbenzene peroxide, the mass ratio of the di-tert-butyl diisopropylbenzene peroxide to the diisopropylbenzene peroxide is 7:3-5:

5.

7. The EVA encapsulation film according to claim 1, characterized in that: The antioxidant includes one or more of antioxidant 1076, antioxidant 1010, tris(2,4-di-tert-butylphenyl) phosphite, and ß-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate.

8. The EVA encapsulation film according to claim 1, characterized in that: The light stabilizer includes one or more of 2,2-dihydroxy-4-methoxybenzophenone, bis(2,2,6,6-tetramethyl-4-piperidinyl)sebacate, and bis(1-octyloxy-2,2,6,6-tetramethyl-4-piperidinyl)sebacate.

9. The EVA encapsulation film according to claim 1, characterized in that: The mass ratio of the core layer film to the shell layer film is (4~5):

1.

10. A method for preparing an EVA encapsulation film, characterized in that: The steps include: Put 80-100 parts of EVA resin, 5-10 parts of water-blocking agent and 0.2-2 parts of cross-linking agent into a first mixing kettle to obtain a shell film raw material; Put 70-100 parts of EVA resin, 0.5-2 parts of cross-linking agent, 0.1-1 parts of antioxidant and 0.1-0.5 parts of light stabilizer into a second mixing kettle to obtain a core layer film raw material; The shell layer film raw material is put into the first mixing kettle for melting, and then extruded through the first extruder to obtain a pre-shell layer film; the core layer film raw material is put into the second mixing kettle for melting, and then extruded through the second extruder to obtain a pre-core layer film; the pre-shell layer film and the pre-core layer film are then extruded through a coaxial co-extrusion device to obtain an extrudate, and the extrudate is sequentially subjected to casting, cooling, pulling, and curling to obtain an EVA packaging film.

11. The method for preparing the EVA encapsulation film according to claim 10, characterized in that: The water blocking agent is silane-modified silica; The preparation method of the silane-modified silicon dioxide comprises: Adding a silane coupling agent into an acetone solution and stirring to obtain a mixed solution; After the pH of the mixed solution is adjusted, silicon dioxide is added to the pH-adjusted mixed solution and ultrasonically dispersed; The mixed solution after ultrasonic dispersion is subjected to centrifugal filtration and drying treatments in sequence to obtain silane-modified silicon dioxide.

12. The method for preparing the EVA encapsulation film according to claim 11, characterized in that: The mass ratio of the silane coupling agent to the acetone solution is 1:(3-5).

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