An adhesive film, its preparation method and application

Abstract

The present invention discloses a glue film, a preparation method thereof and an application, relating to the photovoltaic field. The raw materials of the glue film comprise the following components in parts by weight: 100 parts of POE, 0.2 - 5 parts of liquid nitrile rubber, 0.1 - 2 parts of crosslinking agent, 0.01 - 5 parts of co-crosslinking agent, 0.1 - 5 parts of coupling agent, 0 - 4 parts of antioxidant, and 0 - 3 parts of ultraviolet absorber. By using POE as the matrix, adding liquid nitrile rubber and the above-mentioned auxiliaries, and limiting the dosage of each component, the present invention can significantly improve the crosslinking degree of POE, reduce the exudation rate of auxiliaries, and improve the anti-PID performance. The preparation method is simple and suitable for industrial production.

Description

Technical Field

[0001] The present invention relates to the field of photovoltaics, and more particularly, to an adhesive film and a preparation method and application thereof. Background Art

[0002] Photovoltaic encapsulation adhesive films play an important role in improving the service life of photovoltaic modules. Currently, ethylene-vinyl acetate copolymer (EVA) or polyolefin elastomer (POE) is generally used as the matrix, and various additives are added for preparation. Compared with EVA, POE materials have advantages such as good weather resistance, low water vapor transmission rate, and good anti-potential-induced degradation (PID) performance, and are one of the key focuses in the industry in recent years.

[0003] However, since POE has a fully saturated carbon chain structure, the reaction activity of the molecular chain is low, and problems such as slow crosslinking speed and low crosslinking degree are likely to occur during lamination. Therefore, the lamination temperature and time of POE are often higher than those of EVA, and more crosslinking agents and co-crosslinking agents need to be added, which reduces the lamination efficiency and increases energy consumption to a certain extent; even so, the crosslinking degree of POE after lamination is still lower than that of EVA; in addition, POE has very low polarity, and adding more additives will cause problems such as additive precipitation during lamination, and the adhesive film is prone to slipping. In addition, even if the battery module is encapsulated with a common POE adhesive film, cations such as + Na 2+ Ca + K

[0004] CN 117467378 A discloses a rapidly crosslinkable POE encapsulation adhesive film and a preparation method and a photovoltaic module thereof, which improve the crosslinking ability of POE by introducing highly active groups such as aromatic olefins and cycloolefins into the POE molecular chain. CN110713798A discloses a rapidly crosslinkable encapsulation adhesive film for photovoltaic modules and a preparation method thereof, which makes the adhesive film have a certain crosslinking degree before use through radiation treatment, and then introduces a modified resin with active groups to make the adhesive film crosslink again during lamination. CN 111518487A discloses a special anti-PID POE adhesive film for photovoltaic double-glass module encapsulation and a preparation method thereof, which grafts maleic anhydride onto the POE resin to enhance polarity and improve its compatibility with additives; in addition, by adding a PID regulator prepared from nano rare earth oxides, its anti-PID performance can be improved. CN 109810639 A discloses an anti-potential-induced degradation photovoltaic encapsulation material POE adhesive film, which improves the performance of the POE adhesive film by adding a small molecule internal crosslinking agent containing double bonds and amide groups.

[0005] Although the above method can improve some properties of the POE encapsulation film, its preparation raw materials are relatively complex and the cost is high. It is difficult to balance the crosslinking performance, anti-PID performance, and the performance of reducing the precipitation of additives of the POE film, and it is not suitable for industrial production. Summary of the Invention

[0006] The main object of the present invention is to provide a film and its preparation method and application, so as to solve the problems of poor crosslinking property, serious precipitation of additives, and easy occurrence of PID phenomenon in the existing POE film.

[0007] To achieve the above object, according to the first aspect of the present invention, a film is provided, and its raw materials include the following components in parts by weight: 100 parts of POE, 0.2 - 5 parts of liquid nitrile rubber, 0.1 - 2 parts of crosslinking agent, 0.01 - 5 parts of co-crosslinking agent, 0.1 - 5 parts of coupling agent, 0 - 4 parts of antioxidant, and 0 - 3 parts of ultraviolet absorber. There are a large number of carbon-carbon double bonds in nitrile rubber, which can provide more crosslinking sites, participate in the formation of the crosslinking network of the film, and improve the crosslinking degree; in addition, liquid nitrile rubber has good fluidity and is easy to be uniformly mixed with POE. Compared with solid nitrile rubber, the obtained film has better uniformity.

[0008] Further, in the liquid nitrile rubber, the mass fraction of acrylonitrile units is 20% - 70%, and the mass fraction of butadiene units is 30% - 80%.

[0009] More preferably, in the liquid nitrile rubber, the mass fraction of acrylonitrile units is 50% - 70%, and the mass fraction of butadiene units is 30% - 50%. The cyano group in acrylonitrile has strong polarity, which can improve the compatibility between the POE matrix and additives, reduce the additive precipitation rate, and the strong coordination property of the cyano group can also capture cations, improving the anti-PID performance of the film; the butadiene chain segment has good compatibility with the POE matrix. By limiting the mass fractions of acrylonitrile units and butadiene units, the problem of additive precipitation can be effectively alleviated and the anti-PID performance can be improved.

[0010] Further, the number-average molecular weight of the liquid nitrile rubber is 500 - 10000, the viscosity is 500 - 10000 cP, and the polydispersity index (PDI) is 1.01 - 5.

[0011] Further, the viscosity of the liquid nitrile rubber is 1000 - 5000 cP.

[0012] Further, the PDI of the liquid nitrile rubber is 1.5 - 2.5.

[0013] Furthermore, the melt index of the POE measured under the conditions of 190 °C and 2.16 kg is 5 - 30 g / 10 min; the number average molecular weight of the POE is 50,000 - 300,000, and the PDI is 1.1 - 3; the mass fraction of ethylene in the POE is 50% - 90%.

[0014] Furthermore, the crosslinking agent is at least one of azobisisobutyronitrile, benzoyl peroxide, tert-amyl peroxybenzoate, tert-butyl peroxybenzoate, di-tert-butyl peroxide, 1,1-di-tert-butylperoxy-3,3,5-trimethylcyclohexane, tert-butyl peroxyisopropyl carbonate, tert-amyl peroxyacetate, tert-amyl peroxy(2-ethylhexyl) carbonate, tert-butyl peroxy-3,5,5-trimethylhexanoate, 1,1-di-tert-butylperoxycyclohexane, 2,2-bis(tert-butylperoxy)butane, tert-butyl peroxy-tert-amyl carbonate, 1,1-bis(tert-amylperoxy)cyclohexane, 2,5-dimethyl-2,5-bis(benzoylperoxy)hexane.

[0015] Furthermore, the co-crosslinking agent is at least one of triallyl cyanurate, trimethylolpropane trimethacrylate, triallyl isocyanurate, ethoxylated pentaerythritol tetraacrylate, ethoxylated trimethylolpropane triacrylate, pentaerythritol tetraacrylate, pentaerythritol triacrylate.

[0016] Furthermore, the coupling agent is at least one of γ-glycidoxypropyltrimethoxysilane, vinyltrichlorosilane, vinyltriethoxysilane, vinyltrimethoxysilane, vinyltris(2-methoxyethoxy)silane, γ-methacryloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltriethoxysilane.

[0017] Furthermore, the antioxidant is at least one of didodecenyl p-cresol, isooctyl 3,5-di-tert-butyl-4-hydroxybenzenepropionate, bis(2,4-dicumylphenyl)pentaerythritol diphosphite, distearyl pentaerythritol diphosphite, N,N'-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine, 2,6-di-tert-butyl-p-cresol, tris(2,4-di-tert-butylphenyl)phosphite, octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanuric acid.

[0018] Further, the ultraviolet absorber is at least one of ethylhexyl methoxycinnamate, 2,4-di-tert-butylphenyl 3,5-di-tert-butyl-4-hydroxybenzoate, n-hexadecyl 3,5-di-tert-butyl-4-hydroxybenzoate, ethylhexyl triazone, N-(2-ethoxyphenyl)-N'-(2-ethylphenyl)oxamide, ethyl 2-cyano-3,3-diphenylacrylate, 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-[4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl]-5-(octyloxy)phenol, 2-hydroxy-4-n-octyloxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2,4-dihydroxybenzophenone, and N-(ethoxycarbonylphenyl)-N'-methyl-N'-phenylformamidine.

[0019] According to the second aspect of the present invention, a method for preparing the above-mentioned adhesive film is further provided. The preparation method is as follows: Mix each component according to the ratio, and perform casting extrusion and cooling at 85-100 °C to obtain the adhesive film. This preparation method is simple and does not require the use of complex equipment and processes, making it suitable for industrial production.

[0020] According to the third aspect of the present invention, an application of the above-mentioned adhesive film in the photovoltaic field is provided, and it can be used to prepare photovoltaic encapsulation materials.

[0021] Applying the technical solution of the present invention, adding liquid nitrile rubber to the POE matrix can provide more crosslinking sites, improve the crosslinking degree of the POE adhesive film, and can also capture cations to improve the anti-PID performance; adding a crosslinking agent and a co-crosslinking agent can further improve the crosslinking performance of the POE adhesive film and enhance its mechanical properties; the liquid nitrile rubber contains a butadiene segment with good affinity for POE and a strongly polar cyano group, which can improve the compatibility between the additive and the POE matrix and reduce the additive precipitation rate; adding an antioxidant and an ultraviolet absorber can improve the anti-aging performance of the adhesive film and give it a longer service life. Detailed Embodiments

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Those not specified in the embodiments are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or instruments not specified by the manufacturer are all conventional products that can be obtained through commercial purchase.

[0023] As described in the background art of the present invention, there are problems in the prior art such as poor crosslinking performance of POE films, insufficient anti-PID performance, and easy precipitation of additives. To solve the above problems, in a typical embodiment of the present invention, a film is provided, and its raw materials include the following components in parts by weight: 100 parts of POE, 0.2 - 5 parts of liquid nitrile rubber, 0.1 - 2 parts of crosslinking agent, 0.01 - 5 parts of co-crosslinking agent, 0.1 - 5 parts of coupling agent, 0 - 4 parts of antioxidant, and 0 - 3 parts of ultraviolet absorber.

[0024] There are a large number of carbon-carbon double bonds in liquid nitrile rubber, which can provide more crosslinking sites, participate in the formation of the crosslinked network of the film, and improve the crosslinking degree. In addition, the cyano group has a strong coordination ability and can coordinate with metal ions such as Na + , Ca 2+ , K + etc., to achieve the purpose of capturing cations, prevent Na + , Ca 2+ , K + and other ions in the glass from reaching the battery surface, and improve the anti-PID performance. In addition, nitrile rubber is a copolymer of butadiene and acrylonitrile. The butadiene segment has good compatibility with the POE resin. The cyano group has strong polar characteristics, which can increase the polarity of the main resin, improve the compatibility with additives, and play a role in anti-slip and preventing the precipitation of additives. Common nitrile rubbers are solids and it is difficult to achieve uniform mixing with POE. Therefore, liquid nitrile rubber needs to be used, which has better processing performance and is easier to mix evenly. In addition, the addition of a crosslinking agent and a co-crosslinking agent in the present invention can crosslink the molecular chains with each other, thereby having thermosetting properties. A three-dimensional network structure can be formed during the encapsulation process, effectively improving the mechanical properties of the film. By adding an antioxidant and an ultraviolet absorber, the anti-aging performance of the film can be improved and its service life can be increased. Limiting the dosage of each component in the film as above can make the film have good crosslinking performance, low additive precipitation rate, and high anti-PID performance. The formula of the above film is simple, the components are easy to obtain, and it is suitable for large-scale application.

[0025] In a preferred embodiment of the present invention, the raw materials include the following components in parts by weight: 100 parts of POE, 0.2 - 5 parts of liquid nitrile rubber, 0.1 - 2 parts of crosslinking agent, 0.1 - 3 parts of co-crosslinking agent, 0.1 - 3 parts of coupling agent, 0.05 - 2 parts of antioxidant, and 0.1 - 3 parts of ultraviolet absorber.

[0026] By limiting the dosage of each component as above, the mechanical properties and anti-aging performance of the film are relatively good, and the applicable range is wider.

[0027] In a preferred embodiment of the present invention, in the liquid nitrile rubber, the mass fraction of acrylonitrile units is 20% - 70%, and the mass fraction of butadiene units is 30% - 80%.

[0028] In a preferred embodiment of the present invention, in the liquid nitrile rubber, the mass fraction of acrylonitrile units is 50%-70%, and the mass fraction of butadiene units is 30%-50%. By further optimizing the mass fractions of acrylonitrile units and butadiene units in the liquid nitrile rubber, the rubber film still has a high crosslinking degree and good anti-PID performance in the case of extremely low or no precipitation of the additives.

[0029] In a preferred embodiment of the present invention, the number-average molecular weight of the liquid nitrile rubber is 500-10,000, the viscosity is 500-10,000 cP, and the polydispersity index (PDI) is 1.01-5. By the above optimization of the performance parameters of the liquid nitrile rubber, it can be well mixed with POE, effectively improving the crosslinking performance of the rubber film.

[0030] In the present invention, the viscosities are all measured by a rotational rheometer at 25°C; the PDI is all measured by an American Waters 1525 / 2414 gel permeation chromatograph at 25°C, the sample concentration is 3 mg / mL, polystyrene is used as the standard sample, the mobile phase is tetrahydrofuran, and the flow rate is 1 mL / min.

[0031] In a preferred embodiment of the present invention, the viscosity of the liquid nitrile rubber at 25°C is 1000-5000 cP. By optimizing its viscosity, its processing performance can be further improved.

[0032] In a preferred embodiment of the present invention, the PDI of the liquid nitrile rubber is 1.5-2.5. By optimizing the PDI of the liquid nitrile rubber, the molecular weight distribution of the polymer is narrower, that is, the composition is more uniform, and the consistency of the rubber film is higher, which helps to improve its stability during use.

[0033] Typical but not limiting, according to the ASTM D1238 standard, the melt index of POE measured at 190°C and 2.16 kg is 5-30 g / 10 min; the number-average molecular weight of POE is 50,000-300,000, the PDI is 1.1-3; the mass fraction of ethylene in POE is 50%-90%.

[0034] In a preferred embodiment of the present invention, the crosslinking agent is at least one of azobisisobutyronitrile, benzoyl peroxide, tert-amyl peroxybenzoate, tert-butyl peroxybenzoate, di-tert-butyl peroxide, 1,1-di-tert-butylperoxy-3,3,5-trimethylcyclohexane, tert-butyl peroxyisopropyl carbonate, tert-amyl peroxyacetate, tert-amyl peroxy(2-ethylhexyl) carbonate, tert-butyl peroxy-3,5,5-trimethylhexanoate, 1,1-di-tert-butylperoxycyclohexane, 2,2-bis(tert-butylperoxy)butane, tert-butyl peroxy-tert-amyl carbonate, 1,1-di(tert-amylperoxy)cyclohexane, 2,5-dimethyl-2,5-bis(benzoylperoxy)hexane. The co-crosslinking agent is at least one of triallyl cyanurate, trimethylolpropane trimethacrylate, triallyl isocyanurate, ethoxylated pentaerythritol tetraacrylate, ethoxylated trimethylolpropane triacrylate, pentaerythritol tetraacrylate, pentaerythritol triacrylate. The coupling agent is at least one of γ-glycidoxypropyltrimethoxysilane, vinyltrichlorosilane, vinyltriethoxysilane, vinyltrimethoxysilane, vinyltris(2-methoxyethoxy)silane, γ-methacryloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltriethoxysilane. By making the above-mentioned preferences for the types of the crosslinking agent, the co-crosslinking agent and the coupling agent, they can synergistically improve the crosslinking performance of POE and the compatibility of the POE matrix, liquid nitrile rubber and additives, and reduce the precipitation rate of additives.

[0035] Typical but not limiting, the antioxidants are at least one of ditetradecenyl p - cresol, isooctyl 3,5 - di - tert - butyl - 4 - hydroxyhydrocinnamate, bis(2,4 - di - cumylphenyl)pentaerythritol diphosphite, distearyl pentaerythritol diphosphite, N,N'-bis[3-(3,5 - di - tert - butyl - 4 - hydroxyphenyl)propionyl]hydrazine, 2,6 - di - tert - butyl - p - cresol, tris(2,4 - di - tert - butylphenyl)phosphite, octadecyl 3,5 - di - tert - butyl - 4 - hydroxyphenylpropionate, pentaerythritol tetra[3-(3,5 - di - tert - butyl - 4 - hydroxyphenyl)propionate], bis(2,4 - di - tert - butylphenyl)pentaerythritol diphosphite, 2,2'-methylenebis(4 - methyl - 6 - tert - butylphenol), 1,3,5 - tris(3,5 - di - tert - butyl - 4 - hydroxybenzyl)isocyanuric acid. The ultraviolet absorbers are at least one of ethylhexyl methoxycinnamate, 2,4 - di - tert - butylphenyl 3,5 - di - tert - butyl - 4 - hydroxybenzoate, n - hexadecyl 3,5 - di - tert - butyl - 4 - hydroxybenzoate, ethylhexyl triazone, N-(2 - ethoxyphenyl)-N'-(2 - ethylphenyl)oxalamide, ethyl 2 - cyano - 3,3 - diphenylacrylate, 2-(2'-hydroxy - 5'-tert - octylphenyl)benzotriazole, 2-(2'-hydroxy - 5'-methylphenyl)benzotriazole, 2 - [4,6 - bis(2,4 - dimethylphenyl)-1,3,5 - triazin - 2 - yl]-5-(octyloxy)phenol, 2 - hydroxy - 4 - n - octyloxybenzophenone, 2 - hydroxy - 4 - methoxybenzophenone, 2,2'-dihydroxy - 4,4'-dimethoxybenzophenone, 2,4 - dihydroxybenzophenone, N-(ethoxycarbonylphenyl)-N'-methyl - N'-phenylformamidine. The above - mentioned antioxidants and ultraviolet absorbers are common anti - aging additives, which can effectively improve the service life of the film.

[0036] In another typical embodiment of the present invention, a method for preparing the above - mentioned film is further provided. The preparation method is as follows: mix each component according to the ratio, and then perform casting extrusion and cooling at 85 - 100 °C to obtain the film; in addition, embossing can be carried out before cooling, and slitting and winding can be carried out after cooling to obtain the film product. The above - mentioned preparation method is simple and has few processes, which is suitable for industrial production.

[0037] In a typical embodiment of the present invention, the application of the film in the above - mentioned embodiment in the photovoltaic field is provided, and it can be used to prepare photovoltaic encapsulation materials.

[0038] The following further describes the present application in detail with specific embodiments, and these embodiments should not be construed as limiting the scope claimed by the present application.

[0039] The information of some components in the examples and comparative examples is as follows:

[0040] POE: The melt index measured at 190 °C and 2.16 kg is 10 g / 10 min, the number average molecular weight is 150,000, the PDI is 2.0, and the mass fraction of ethylene is 75%.

[0041] Liquid nitrile rubber:

[0042] LNBR1, the mass fraction of acrylonitrile units is 50%, the mass fraction of butadiene units is 50%, the number average molecular weight is 5,000, the viscosity is 2,000 cP, and the PDI is 1.5;

[0043] LNBR2, the mass fraction of acrylonitrile units is 60%, the mass fraction of butadiene units is 40%, the number average molecular weight is 5,000, the viscosity is 2,000 cP, and the PDI is 1.5;

[0044] LNBR3, the mass fraction of acrylonitrile units is 70%, the mass fraction of butadiene units is 30%, the number average molecular weight is 5,000, the viscosity is 2,000 cP, and the PDI is 1.5;

[0045] LNBR4, the mass fraction of acrylonitrile units is 40%, the mass fraction of butadiene units is 60%, the number average molecular weight is 5,000, the viscosity is 2,000 cP, and the PDI is 1.5;

[0046] LNBR5, the mass fraction of acrylonitrile units is 20%, the mass fraction of butadiene units is 80%, the number average molecular weight is 5,000, the viscosity is 2,000 cP, and the PDI is 1.5;

[0047] LNBR6, the mass fraction of acrylonitrile units is 50%, the mass fraction of butadiene units is 50%, the number average molecular weight is 10,000, the viscosity is 9,000 cP, and the PDI is 1.5.

[0048] LNBR7, the mass fraction of acrylonitrile units is 50%, the mass fraction of butadiene units is 50%, the number average molecular weight is 600, the viscosity is 500 cP, and the PDI is 1.5.

[0049] LNBR8, the mass fraction of acrylonitrile units is 50%, the mass fraction of butadiene units is 50%, the number average molecular weight is 7,600, the viscosity is 5,000 cP, and the PDI is 1.5.

[0050] LNBR9, the mass fraction of acrylonitrile units is 50%, the mass fraction of butadiene units is 50%, the number average molecular weight is 3,000, the viscosity is 1,000 cP, and the PDI is 1.5.

[0051] LNBR10, with a mass fraction of acrylonitrile units of 50%, a mass fraction of butadiene units of 50%, a number-average molecular weight of 5000, a viscosity of 2000 cP, and a PDI of 2.

[0052] LNBR11, with a mass fraction of acrylonitrile units of 50%, a mass fraction of butadiene units of 50%, a number-average molecular weight of 5000, a viscosity of 2000 cP, and a PDI of 2.5.

[0053] Example 1

[0054] An example of the adhesive film of the present invention. The specific formulation of Example 1 is shown in Table 1. The preparation method is as follows: Mix each component according to the ratio, perform casting extrusion, embossing, cooling, slitting, and winding at 90 °C to obtain the adhesive film.

[0055] Example 2

[0056] An example of the adhesive film of the present invention. The difference between Example 2 and Example 1 is only that the type of liquid nitrile rubber is different, which is LNBR2.

[0057] Example 3

[0058] An example of the adhesive film of the present invention. The difference between Example 3 and Example 1 is only that the type of liquid nitrile rubber is different, which is LNBR3.

[0059] Example 4

[0060] An example of the adhesive film of the present invention. The difference between Example 4 and Example 1 is only that the type of liquid nitrile rubber is different, which is LNBR4.

[0061] Example 5

[0062] An example of the adhesive film of the present invention. The difference between Example 5 and Example 1 is only that the type of liquid nitrile rubber is different, which is LNBR5.

[0063] Example 6

[0064] An example of the adhesive film of the present invention. The difference between Example 6 and Example 1 is only that the type of liquid nitrile rubber is different, which is LNBR6.

[0065] Example 7

[0066] An example of the adhesive film of the present invention. The difference between Example 7 and Example 1 is only that the type of liquid nitrile rubber is different, which is LNBR7.

[0067] Example 8

[0068] An embodiment of the adhesive film of the present invention. The difference between Example 8 and Example 1 is only that the type of liquid nitrile rubber is different, which is LNBR8.

[0069] Example 9

[0070] An embodiment of the adhesive film of the present invention. The difference between Example 9 and Example 1 is only that the type of liquid nitrile rubber is different, which is LNBR9.

[0071] Example 10

[0072] An embodiment of the adhesive film of the present invention. The difference between Example 10 and Example 1 is only that the type of liquid nitrile rubber is different, which is LNBR10.

[0073] Example 11

[0074] An embodiment of the adhesive film of the present invention. The difference between Example 11 and Example 1 is only that the type of liquid nitrile rubber is different, which is LNBR11.

[0075] Examples 12 - 13

[0076] Examples 12 - 13 are embodiments of the adhesive film of the present invention. The difference between Examples 12 - 13 and Example 1 is only that the weight parts of each component are different, as specifically shown in Table 1.

[0077] Comparative Examples 1 - 2

[0078] Comparative Examples 1 - 2 are adhesive films. The difference between them and Example 1 is only that the weight parts of each component are different, as specifically shown in Table 1.

[0079] Table 1 (weight parts)

[0080]

[0081] Performance test

[0082] The adhesive films prepared in the examples and comparative examples were subjected to performance tests. The test methods are as follows, and the test results are shown in Table 2.

[0083] 1) Crosslinking degree: Tested in accordance with the national standard GB / T 29848 - 2018. Laminating conditions: In a vacuum laminator, pressurize at 150 °C for 13 min, and use the xylene extraction method to test the crosslinking degree.

[0084] 2) Exudation performance of additives: All additives in the film need to be first configured at different concentration gradients in ethanol, and then analyzed by Agilent 7890A gas chromatography. According to the signal response intensity of the GC detector and the concentration of the additives, a standard curve is made. Then, the freshly prepared film (500 g, with the total content of all additives being a%) is sealed in an aluminum-plastic bag and placed at 30 °C for 24 h. Then, a sample of 5 cm × 6 cm is cut, weighed, with the mass being M (about 1.5 g), soaked in 50 mL of ethanol, ultrasonically treated for 5 minutes, the ethanol soaking solution is collected, and then analyzed by the above-mentioned gas chromatography. According to the standard curve, the concentration of each additive is obtained, and the total mass of all additives in the ethanol soaking solution is calculated as m. The exudation rate A of the additives is calculated as A = m / (M × a%), and the smaller the exudation rate A of the additives, the weaker the ability of the additives to exude to the film surface.

[0085] 3) PID: Test is carried out according to IEC TS 62804-1:2015, and the test conditions are 85 °C / 85% RH, with an additional constant DC voltage of -1500 V. After 192 h, the power attenuation of the module before and after the PID test is measured.

[0086] Table 2

[0087]

[0088] From the above test results, it can be seen that the crosslinking degrees of Examples 1-13 are all higher than 80%, the exudation rates of the additives are lower than 3%, and the PID is within 3%. Their comprehensive performance is significantly better than that of Comparative Examples 1-2 and is suitable for application in the photovoltaic field. In addition, the tensile strength of the film in Examples 1-13 is all higher than 15 MPa, and the elongation at break is all above 900%, with good mechanical properties and a wide range of applications.

[0089] In addition, by comparing the test results of Examples 1-5, it can be found that when the mass fraction of acrylonitrile units in liquid nitrile rubber is 50% - 70% and the mass fraction of butadiene units is 30% - 50%, the prepared film has better comprehensive performance.

[0090] By comparing the test results of Example 1 and Examples 6-9, it can be found that the viscosity of liquid nitrile rubber also affects the performance of the film. When the viscosity is 1000 - 5000 cP, the PID is smaller.

[0091] From the test results of Example 1 and Examples 10-11, it can be seen that when the PDI of liquid nitrile rubber is 1.5 - 2.5, the film has a high crosslinking degree, a low exudation rate of additives, and the PID is within 1.5%, with good comprehensive performance.

[0092] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, various modifications and variations can be made to the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A film, characterized in that: The raw materials include the following components in parts by weight: 100 parts of POE, 0.2-5 parts of liquid nitrile rubber, 0.1-2 parts of a crosslinking agent, 0.01-5 parts of a co-crosslinking agent, 0.1-5 parts of a coupling agent, 0-4 parts of an antioxidant, and 0-3 parts of an ultraviolet absorber; in the liquid nitrile rubber, the mass fraction of an acrylonitrile unit is 50%-70%, and the mass fraction of a butadiene unit is 30%-50%; The number average molecular weight of the liquid nitrile rubber is 3000-7600, the viscosity of the liquid nitrile rubber is 1000-5000 cP, and the PDI of the liquid nitrile rubber is 1.5-2.5; The coupling agent is at least one of γ-glycidyloxypropyltrimethoxysilane, vinyltrichlorosilane, vinyltriethoxysilane, vinyltrimethoxysilane, vinyltri(2-methoxyethoxy)silane, γ-methacryloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane and N-(β-aminoethyl)-γ-aminopropyltriethoxysilane.

2. The adhesive film according to claim 1, characterized in that: The melt index of the POE measured at 190° C. and 2.16 kg is 5-30 g / 10 min; the number average molecular weight of the POE is 50,000-300,000, and the PDI is 1.1-3; the mass fraction of ethylene in the POE is 50%-90%.

3. The adhesive film according to claim 1, characterized in that: The crosslinking agent is at least one of azobisisobutyronitrile, benzoyl peroxide, tert-amyl perbenzoate, tert-butyl perbenzoate, di-tert-butyl peroxide, 1,1-di-tert-butylperoxy-3,3,5-trimethylcyclohexane, tert-butyl peroxyisopropyl carbonate, tert-amyl peroxyacetate, tert-amyl peroxy (2-ethylhexyl) carbonate, tert-butyl peroxy-3,5,5-trimethylhexanoate, 1,1-di-tert-butylperoxycyclohexane, 2,2-bis (tert-butylperoxy)butane, tert-butyl peroxypentylate, 1,1-di (tert-amylperoxy)cyclohexane, and 2,5-dimethyl-2,5-bis (benzoylperoxy)hexane; and / or The auxiliary cross-linking agent is at least one of triallyl cyanurate, trimethylolpropane trimethacrylate, triallyl isocyanurate, ethoxylated pentaerythritol tetraacrylate, ethoxylated trimethylolpropane triacrylate, pentaerythritol tetraacrylate and pentaerythritol triacrylate; and / or The antioxidants are didodecenyl p-cresol, 3,5-di-tert-butyl-4-hydroxyphenylpropionate isooctyl, bis(2,4-dicumylphenyl)pentaerythritol diphosphite, distearyl pentaerythritol diphosphite, N,N'-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine, 2,6-di-tert-butyl-p-cresol, tris(2,4-di-tert-butylphenyl)phosphite, β-(3 At least one of 1,3,5-di-tert-butyl-4-hydroxyphenyl) propionate, octadecyl tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, 2,2'-methylenebis(4-methyl-6-tert-butylphenol), and 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanuric acid; and / or The ultraviolet absorber is ethylhexyl methoxycinnamate, 2,4-di-tert-butylphenyl 3,5-di-tert-butyl-4-hydroxybenzoate, hexadecyl 3,5-di-tert-butyl-4-hydroxybenzoate, ethylhexyl triazone, N-(2-ethoxyphenyl)-N'-(2-ethylphenyl)-oxalamide, 2-cyano-3,3-diphenyl acrylate, 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole, 2-(2'-hydroxy At least one of 2-(4-(2-(6-nitro-5-nitrophenyl)benzotriazole, 2-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine-2-yl-5-(octyloxy)-phenol, 2-hydroxy-4-n-octyloxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2,4-dihydroxybenzophenone and N-(ethoxycarbonylphenyl)-N'-methyl-N'-phenylformamidine.

4. A method for preparing an adhesive film according to any one of claims 1 to 3, characterized in that: The preparation method comprises the following steps: mixing the components according to a proportion, performing cast extrusion at 85-100° C., and cooling to obtain the adhesive film.

5. Use of the adhesive film according to any one of claims 1 to 3 in the photovoltaic field.

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