Low-corrosion white EVA (Ethylene Vinyl Acetate) packaging adhesive film as well as preparation method and application thereof

Abstract

The invention provides a low-corrosion type white EVA packaging adhesive film as well as a preparation method and application thereof. The low-corrosion type white EVA packaging adhesive film comprises a first low-acid layer, a main body EVA layer and a second low-acid layer which are sequentially stacked, the preparation raw materials of the first low-acid layer comprise conventional EVA particles, low-acid EVA particles and an auxiliary agent; the main body EVA layer is prepared from the following raw materials: conventional EVA particles, titanium dioxide and auxiliaries; and the second low-acid layer is prepared from the following raw materials: conventional EVA particles, low-acid EVA particles, an acid acceptor and an auxiliary agent. According to the white EVA packaging adhesive film provided by the invention, the first low-acid layer and the second low-acid layer are arranged on the two sides of the main body EVA layer, and the acid acceptor is introduced into the second low-acid layer, so that the packaging adhesive film has relatively low corrosivity.

Description

Technical Field

[0001] This invention belongs to the field of solar cell technology, and relates to a low-corrosion white EVA (ethylene-vinyl acetate copolymer) encapsulating film, its preparation method, and its application. Background Technology

[0002] As an important part of new energy, photovoltaic power generation has matured in recent years. Photovoltaic modules consist of eight auxiliary materials. Since the solar cells can generate photovoltaic power, they are the core component, and the other seven auxiliary materials need to be updated around the technological iteration of the solar cells. Currently, the market is dominated by TOPCon solar cell technology for technological iteration and updates. Initially, its solar cell paste used Ag / Al composite paste, which was corroded by conventional EVA encapsulation film, so POE was used for encapsulation. However, based on the LECO technology update, the paste was changed to Ag, which is an inert metal. Therefore, EVA can be used for encapsulation, which reduces the corrosivity and also reduces the cost of encapsulation materials.

[0003] Currently, TOPCon cells generally use white EVA encapsulation technology on the back, which can reflect a certain amount of sunlight, thereby increasing the module's power generation efficiency. However, as the photovoltaic module's service life increases, the VA groups in EVA decompose into acetic acid, which corrodes the cells. In addition, the presence of titanium dioxide filler in the white EVA accelerates the corrosion of the cells, leading to module power decay and reducing the module's lifespan. Furthermore, due to the presence of titanium dioxide, the encapsulation film has a low specific surface energy, and with the increase in service life, there is a risk of delamination failure, which reduces the adhesion to the backsheet or glass. Therefore, it is very meaningful to develop a high-performance white EVA encapsulation film suitable for TOPCon single / double glass modules. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a low-corrosion white EVA encapsulation film, its preparation method, and its applications. The low-corrosion white EVA encapsulation film provided by the present invention is a three-layer co-extruded EVA film, suitable for encapsulating LECO technology TOPCon single / double glass modules. Compared with conventional white EVA encapsulation films, it exhibits a relatively lower acetic acid content after aging, and significantly improved low-corrosion and DH (damp-heat) aging resistance.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides a low-corrosion white EVA encapsulation film, the low-corrosion white EVA encapsulation film comprising a first low-acid layer, a main EVA layer, and a second low-acid layer stacked sequentially;

[0007] The raw materials for preparing the first low-acid layer include conventional EVA particles, low-acid EVA particles, and additives;

[0008] The raw materials for preparing the main EVA layer include conventional EVA particles, titanium dioxide, and additives;

[0009] The raw materials for preparing the second low-acid layer include conventional EVA particles, low-acid EVA particles, acid absorbent, and additives.

[0010] In practical use, the first low-acid layer is adjacent to the glass or backsheet side, and the second low-acid layer is adjacent to the battery cell side.

[0011] The white EVA encapsulation film provided by this invention has a first low-acid layer made of low-acid EVA particles (low VA content EVA particles) and conventional EVA particles, which can reduce VA decomposition after damp heat aging of the film and reduce the proportion of acetic acid penetrating into the main EVA layer and the second low-acid layer. Since the main EVA layer contains color masterbatch powder, which has a low specific surface energy, there is a risk of delamination failure as the service life increases. Therefore, the first low-acid layer also has the effect of improving its adhesion to the backing / glass.

[0012] The white EVA encapsulation film provided by this invention has a second low-acid layer made of EVA particles with lower VA content mixed with conventional EVA particles, which can reduce VA decomposition after wet heat aging of the film, thereby reducing the risk of corrosion of the battery cell. Since the battery cell is more sensitive to acid, an acid absorber is added to this layer, which can further absorb or degrade the acid decomposed by EVA, thus providing a dual protection effect for the battery cell.

[0013] Another function of the second low-acid layer is to reduce the fluidity of the upper and lower films by adding a certain proportion of low melt index resin particles. The overall fluidity of the film is reduced during the lamination process, which can reduce the risk of whitening after lamination, thus not affecting the power generation efficiency of the solar cell. This addition method does not require pre-crosslinking treatment such as irradiation or corona treatment, which can improve the sample preparation efficiency of the production line, thereby reducing the energy consumption of the production line and reducing costs.

[0014] In this invention, "low corrosion" in the low-corrosion white EVA encapsulation film refers to the acetic acid content of the EVA encapsulation film being less than 110 ppm after PCT aging (temperature 121°C, humidity 100% RH) for 96 hours. The acetic acid content is tested in accordance with ISO 15106-1:2003(E) determination of water vapor transmission rate of plastic films and sheets.

[0015] Preferably, the additives in the first low-acid layer, the main EVA layer, and the second low-acid layer each independently include any one or a combination of at least two of the following: crosslinking agent, co-crosslinking agent, acrylate, tackifier, and light stabilizer.

[0016] Preferably, the raw materials for preparing the first low-acid layer include the following components by weight:

[0017]

[0018] Preferably, the raw materials for preparing the first low-acid layer, by weight, may include 70, 71, 72, 73, 74, or 75 parts of conventional EVA particles.

[0019] Preferably, the amount of low-acid EVA particles used in the preparation of the first low-acid layer can be 20 parts, 21 parts, 22 parts, 23 parts, 24 parts, 25 parts, etc., by weight.

[0020] Preferably, the amount of crosslinking agent used in the preparation of the first low-acid layer can be 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, 1 part, etc., by weight.

[0021] Preferably, the amount of crosslinking agent used in the preparation of the first low-acid layer can be 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, 1 part, etc., by weight.

[0022] Preferably, the amount of acrylate used in the preparation of the first low-acid layer can be 0.7 parts, 0.8 parts, 0.9 parts, 1 part, 1.1 parts, 1.2 parts, 1.3 parts, 1.4 parts, 1.5 parts, etc., by weight.

[0023] Preferably, the amount of tackifier used in the preparation of the first low-acid layer can be 0.1 parts, 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, etc., by weight.

[0024] Preferably, the amount of light stabilizer used in the preparation of the first low-acid layer can be 0.05 parts, 0.08 parts, 0.1 parts, 0.13 parts, 0.15 parts, 0.18 parts, 0.2 parts, 0.23 parts, 0.25 parts, 0.28 parts, 0.3 parts, etc., by weight.

[0025] Preferably, the raw materials for preparing the main EVA layer include the following components by weight:

[0026]

[0027] Preferably, the raw materials for preparing the main EVA layer, by weight, can be 80, 81, 82, 83, 84, or 85 parts of conventional EVA particles.

[0028] Preferably, the raw materials for preparing the main EVA layer, by weight, include 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, etc. of titanium dioxide.

[0029] Preferably, the amount of crosslinking agent used in the preparation of the main EVA layer can be 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, 1 part, etc., by weight.

[0030] Preferably, the amount of crosslinking agent used in the preparation of the main EVA layer can be 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, 1 part, etc., by weight.

[0031] Preferably, the amount of acrylate used in the preparation of the main EVA layer can be 0.7 parts, 0.8 parts, 0.9 parts, 1 part, 1.1 parts, 1.2 parts, 1.3 parts, 1.4 parts, 1.5 parts, etc., by weight.

[0032] Preferably, the amount of tackifier used in the preparation of the main EVA layer can be 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, etc., by weight.

[0033] Preferably, the amount of light stabilizer used in the preparation of the main EVA layer can be 0.05 parts, 0.08 parts, 0.1 parts, 0.13 parts, 0.15 parts, 0.18 parts, 0.2 parts, 0.23 parts, 0.25 parts, 0.28 parts, 0.3 parts, etc., by weight.

[0034] Preferably, the raw materials for preparing the second low-acid layer include the following components by weight:

[0035]

[0036] Preferably, the amount of conventional EVA particles used in the preparation of the second low-acid layer can be 70 parts, 71 parts, 72 parts, 73 parts, 74 parts, 75 parts, etc., by weight.

[0037] Preferably, the amount of low-acid EVA particles used in the preparation of the second low-acid layer can be 20 parts, 21 parts, 22 parts, 23 parts, 24 parts, 25 parts, etc., by weight.

[0038] Preferably, the amount of crosslinking agent used in the preparation of the second low-acid layer can be 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, 1 part, 1.1 parts, 1.2 parts, etc., by weight.

[0039] Preferably, the amount of crosslinking agent used in the preparation of the second low-acid layer can be 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, 1 part, etc., by weight.

[0040] Preferably, the amount of acrylate used in the preparation of the second low-acid layer can be 0.7 parts, 0.8 parts, 0.9 parts, 1 part, 1.1 parts, 1.2 parts, 1.3 parts, 1.4 parts, 1.5 parts, etc., by weight.

[0041] Preferably, the amount of tackifier used in the preparation of the second low-acid layer can be 0.1 parts, 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, etc., by weight.

[0042] Preferably, the amount of acid absorbent used in the preparation of the second low-acid layer can be 0.1 parts, 0.12 parts, 0.14 parts, 0.16 parts, 0.18 parts, 0.2 parts, etc., by weight.

[0043] Preferably, the amount of light stabilizer used in the preparation of the second low-acid layer can be 0.05 parts, 0.08 parts, 0.1 parts, 0.13 parts, 0.15 parts, 0.18 parts, 0.2 parts, 0.23 parts, 0.25 parts, 0.28 parts, 0.3 parts, etc., by weight.

[0044] Preferably, the crosslinking agent comprises any one or a combination of at least two of the following: 2-ethylhexyl carbonate tert-butyl peroxide, 2-ethylhexyl carbonate tert-amyl peroxide, methyl ethyl ketone peroxide, benzoyl peroxide, di-tert-butyl peroxide, and dicumyl hydroperoxide.

[0045] Preferably, the crosslinking agent comprises any one or a combination of at least two of the following: triallyl isocyanurate, triallyl cyanurate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, tripropylene glycol diacrylate, dipropylene glycol diacrylate, and triethylene glycol methyl diacrylate.

[0046] Preferably, the acrylate includes any one or a combination of at least two of propoxytrimethylolpropane triacrylate, trimethylolpropane triacrylate, polyethylene glycol diacrylate, and tricyclodecanedimethylol diacrylate.

[0047] Preferably, the tackifier comprises any one or a combination of at least two of γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, 3-(methacryloxy)propyltriethoxysilane, 3-(methacryloxy)propyltrimethoxysilane, vinyltrimethoxysilane, and vinyltriethoxysilane.

[0048] Preferably, the light stabilizer comprises any one or a combination of at least two of the following: bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, poly(4-hydroxy-2,2,6,6-tetramethyl-1-piperidinol) succinate, bis-2,2,6,6-tetramethylpiperidinol sebacate or hindered amine light stabilizers, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, tris(2,4-di-tert-butylphenyl) phosphite, and 2,2,6,6-tetramethyl-4-piperidinyl esters.

[0049] It should be noted that the specific selections of crosslinking agent, co-crosslinking agent, acrylate, tackifier, and light stabilizer in the first low-acid layer, the main EVA layer, and the second low-acid layer can be the same or different.

[0050] Preferably, the titanium dioxide comprises commercially available rutile titanium dioxide produced by conventional sulfuric acid or chloride processes, including any one or a combination of at least two of the commercially available conventional DR-2588, CR-210, CR-220, and 886.

[0051] Preferably, the acid absorbent comprises hydrotalcite Mg 4.5 Al2(OH) 13 CO3·mH2O, where m is an integer from 3 to 5 (e.g., 3, 4 or 5), can be used with only one of them or with two or more at the same time.

[0052] Preferably, the VA content of conventional EVA particles in the first low-acid layer, the main EVA layer, and the second low-acid layer is independently 25%-30% (e.g., 25%, 26%, 27%, 28%, 29%, 30%, etc.), and the melt index is independently 20-30g / 10min (e.g., 20g / 10min, 22g / 10min, 24g / 10min, 26g / 10min, 28g / 10min, 30g / 10min, etc.), and the model is any one or a combination of at least two of the commercially available conventional Hanwha E282PV, Sirbon UE2825, and V2825.

[0053] Preferably, the low-acid EVA particles in the first low-acid layer have a VA content of 16%-18% (e.g., 16%, 17%, 18%, etc.) and a melt index of 10-15g / 10min (e.g., 10g / 10min, 11g / 10min, 12g / 10min, 13g / 10min, 14g / 10min, 15g / 10min, etc.), and the commercially available model is Hanwha E182L (1815).

[0054] Preferably, the VA content of the low-acid EVA particles in the second low-acid layer is 3%-15% (e.g., 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, etc.), and the melt index is 2-5 g / 10 min (e.g., 2 g / 10 min, 3 g / 10 min, 4 g / 10 min, 5 g / 10 min, etc.). The commercially available models are any one or at least a combination of two of the following: Formosa Plastics Taiwan 7340M (14 03), 7320M (09 04), and 7240M (15 02).

[0055] Preferably, the thickness of the first low-acid layer is 0.1-0.15 mm, such as 0.1 mm, 0.11 mm, 0.12 mm, 0.13 mm, 0.14 mm, 0.15 mm, etc.

[0056] Preferably, the thickness of the main EVA layer is 0.4-0.5 mm, such as 0.4 mm, 0.42 mm, 0.44 mm, 0.46 mm, 0.48 mm, 0.5 mm, etc.

[0057] Preferably, the thickness of the second low-acid layer is 0.1-0.15 mm, such as 0.1 mm, 0.11 mm, 0.12 mm, 0.13 mm, 0.14 mm, 0.15 mm, etc.

[0058] The white EVA encapsulation film provided by this invention has a main EVA layer that reflects sunlight, improves the utilization efficiency of the module's cells, and increases the module's power generation efficiency. The reason why this layer has the highest thickness is because conventional EVA particles and titanium dioxide are low in cost, so the proportion of the main EVA layer is increased as much as possible.

[0059] In a second aspect, the present invention provides a method for preparing a low-corrosion white EVA encapsulating film as described in the first aspect, the method comprising the following steps:

[0060] The raw materials for preparing the first low-acid layer, the main EVA layer, and the second low-acid layer are mixed separately, then cast and co-extruded, and post-treated to obtain the low-corrosion white EVA encapsulation film.

[0061] Preferably, the post-processing includes cooling, edge trimming, and winding.

[0062] Thirdly, the present invention provides an application of a low-corrosion white EVA encapsulating film as described in the first aspect in photovoltaic modules.

[0063] Compared with the prior art, the present invention has the following beneficial effects:

[0064] The white EVA encapsulation film provided by this invention has low corrosivity by setting a first low-acid layer and a second low-acid layer on both sides of the main EVA layer and introducing an acid absorber in the second low-acid layer. The first low-acid layer uses low-acid EVA particles mixed with conventional EVA particles, which can reduce VA decomposition after damp heat aging of the film and reduce the proportion of acetic acid penetrating into the main EVA layer and the second low-acid layer. The second low-acid layer uses EVA particles with even lower VA content mixed with conventional EVA particles, which can also reduce VA decomposition after damp heat aging of the film. At the same time, the addition of an acid absorber can further absorb or degrade the acid decomposed from EVA. Attached Figure Description

[0065] Figure 1 This is a schematic diagram of the structure of the low-corrosion white EVA encapsulation film provided in Example 1;

[0066] Among them, 1-first low-acid layer, 2-main EVA layer, 3-second low-acid layer. Detailed Implementation

[0067] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0068] Example 1

[0069] This embodiment provides a low-corrosion white EVA encapsulation film, the structural schematic of which is shown below. Figure 1 As shown, the low-corrosion white EVA encapsulation film includes a first low-acid layer 1, a main EVA layer 2, and a second low-acid layer 3 stacked sequentially, with thicknesses of 0.15mm, 0.4mm, and 0.15mm respectively.

[0070] The raw materials for preparing the first low-acid layer include the following components by weight:

[0071]

[0072]

[0073] The raw materials for preparing the main EVA layer include the following components by weight:

[0074]

[0075] The raw materials for preparing the second low-acid layer include the following components by weight:

[0076]

[0077] The preparation method includes the following steps:

[0078] The raw materials for preparing the first low-acid layer, the main EVA layer, and the second low-acid layer are stirred evenly in a mixer, and then left to stand in a sealed container for a period of time. After that, the mixture is extracted and cast onto the film production line to form a molten film. After being cooled by multiple cooling rollers, the film is trimmed and rolled into a finished product to obtain the low-corrosion white EVA encapsulation film.

[0079] Example 2

[0080] The difference between this embodiment and Embodiment 1 is that the amount of raw materials used in the preparation of each layer is different, as detailed below:

[0081] The raw materials for preparing the first low-acid layer include the following components by weight:

[0082]

[0083] The raw materials for preparing the main EVA layer include the following components by weight:

[0084]

[0085] The raw materials for preparing the second low-acid layer include the following components by weight:

[0086]

[0087] Example 3

[0088] The difference between this embodiment and Embodiment 1 is that the amount of raw materials used in the preparation of each layer is different, as follows: The raw materials for the preparation of the first low-acid layer, by weight, include the following components:

[0089]

[0090] The raw materials for preparing the main EVA layer include the following components by weight:

[0091] Hanwha E282 PV 82 copies;

[0092]

[0093] The raw materials for preparing the second low-acid layer include the following components by weight:

[0094]

[0095] Example 4

[0096] The difference between this embodiment and Embodiment 1 is that the amount of raw materials used in the preparation of each layer is different, as follows: The raw materials for the preparation of the first low-acid layer, by weight, include the following components:

[0097]

[0098]

[0099] The raw materials for preparing the main EVA layer include the following components by weight:

[0100] The raw materials for preparing the second low-acid layer include the following components by weight:

[0101] Example 5

[0102] The difference between this embodiment and Embodiment 1 is that, in the raw materials for preparing the first low-acid layer, the amount of Hanwha E282PV is 65 parts and the amount of Hanwha E182L is 30 parts; in the raw materials for preparing the second low-acid layer, the amount of Hanwha E282PV is 65 parts and the amount of Formosa Plastics 7340M from Taiwan is 30 parts.

[0103] Example 6

[0104] The difference between this embodiment and Embodiment 1 is that the amount of hydrotalcite, an acid absorber, in the raw materials for preparing the second low-acid layer is 0.30 parts.

[0105] Example 7

[0106] The difference between this embodiment and Embodiment 1 is that the acid absorbent (hydrotalcite), the raw material for preparing the second low-acid layer, is replaced with an equal amount of magnesium hydroxide.

[0107] Comparative Example 1

[0108] The difference between this comparative example and Example 1 is that the white EVA encapsulating film consists only of the main EVA layer, and the raw materials for preparing the main EVA layer include the following components by weight:

[0109]

[0110] Comparative Example 2

[0111] The difference between this comparative example and Example 1 is that the white EVA encapsulation film only has a first low-acid layer and a main EVA layer.

[0112] The raw materials for preparing the first low-acid layer include the following components by weight:

[0113]

[0114] The raw materials for preparing the main EVA layer include the following components by weight:

[0115]

[0116] Comparative Example 3

[0117] The difference between this comparative example and Example 1 is that the white EVA encapsulation film only has a main EVA layer and a second low-acid layer.

[0118] The raw materials for preparing the main EVA layer include the following components by weight:

[0119]

[0120]

[0121] The raw materials for preparing the second low-acid layer include the following components by weight:

[0122]

[0123] Comparative Example 4

[0124] The difference between this comparative example and Example 1 is that no acid absorber is added to the second low-acid layer. The specific raw materials for each layer are as follows:

[0125] The raw materials for preparing the first low-acid layer include the following components by weight:

[0126]

[0127]

[0128] The raw materials for preparing the main EVA layer include the following components by weight:

[0129]

[0130] The raw materials for preparing the second low-acid layer include the following components by weight:

[0131]

[0132] The performance of the white EVA encapsulating film provided in the examples and comparative examples was tested using the following methods:

[0133] (1) Reflectivity: Measured in accordance with IEC 61215:2021;

[0134] (2) Fluidity of vulcanized ML: The fluidity was determined in accordance with GB / T 16584-1996;

[0135] (3) Acetic acid content: The test was conducted in accordance with ISO 15106-1:2003(E) Determination of water vapor transmission rate of plastic films and sheets; the aging conditions for PCT were 121°C and 100%RH.

[0136] The performance test results are shown in Table 1.

[0137] Table 1

[0138]

[0139] As can be seen from Table 1, the white EVA encapsulation films provided in Examples 1-4 of the present invention all have low corrosivity (acetic acid content after PCT aging for 48 hours: 72.8-76.3 ppm; acetic acid content after PCT aging for 96 hours: 108.5-109.7 ppm), and their reflectivity can meet the usage requirements. The film has appropriate fluidity, does not become too hard overall after lamination, and is not prone to overflow risk. The white EVA encapsulation films provided in Examples 5 and 6 all exhibited low reflectivity, indicating that excessive addition of low-acid EVA and acid absorbers would affect light transmittance, thereby affecting reflectivity. In addition, due to the low melt index of low-acid EVA, excessive addition would reduce the fluidity of the encapsulation film, making the film too hard overall, and posing a risk of microcracks in the battery cells after lamination. The white EVA encapsulation film provided in Example 7 also exhibited low reflectivity, indicating that replacing an equal amount of hydrotalcite with magnesium hydroxide would affect light transmittance, thereby affecting reflectivity. At the same time, the addition of an equal amount of magnesium hydroxide resulted in an increase in acetic acid content after 96 hours of PCT aging, indicating that an equal amount of magnesium hydroxide was not as effective as hydrotalcite in absorbing acid. If it were added further, the reflectivity would be even lower.

[0140] Compared with Example 1, the white EVA encapsulating film PCT provided in Comparative Example 1 showed a significant increase in acetic acid content after aging, and a lower ML content. The film had high fluidity, and there was a risk of adhesive overflow after lamination, which would affect the power generation efficiency of the solar cell. The white EVA encapsulating films PCT provided in Comparative Examples 2-4 all showed a significant increase in acetic acid content after aging.

[0141] The white EVA encapsulating films provided in the examples and comparative examples are assembled into photovoltaic modules. The method includes the following steps: photovoltaic glass, transparent EVA, photovoltaic cells, white EVA, and photovoltaic glass are stacked in sequence with thicknesses of 2mm, 0.7mm, 0.13mm, 0.7mm, and 2mm, respectively, and the photovoltaic module is obtained after lamination.

[0142] The photovoltaic modules were subjected to a DH aging test, and the test method is as follows:

[0143] (1) Initial peel strength and peel strength after DH 2000h: measured according to GB / T 2790-1995;

[0144] (2) Power attenuation rate after DH 1000h and DH 2000h: measured in accordance with IEC 61215:2021.

[0145] Specifically, DH 1000h means placing the photovoltaic module at 85℃ and 85%RH for 1000 hours, and DH 2000h means placing the photovoltaic module at 85℃ and 85%RH for 2000 hours.

[0146] Table 2

[0147]

[0148]

[0149] As can be seen from Table 2, the photovoltaic modules prepared by the white EVA encapsulating film provided in the embodiments of the present invention all have high peel strength (peel strength after DH 2000h: 72.7-73.1N / cm), low power attenuation rate (power attenuation rate after DH 1000h: 2.12%-2.18%; power attenuation rate after DH 2000h: 3.24%-3.29%) and excellent resistance to damp heat after aging tests.

[0150] The photovoltaic modules prepared with the white EVA encapsulating film provided in Examples 5-6 all showed a decrease in peel strength after DH2000h, indicating that excessive addition of low-acid EVA particles and acid absorbents would affect the peel strength after damp heat aging. The photovoltaic modules prepared with the white EVA encapsulating film provided in Example 7 showed higher power attenuation after DH1000h and DH2000h, indicating that the effect of adding an equal amount of magnesium hydroxide was not as good as that of hydrotalcite.

[0151] Compared with Example 1, the photovoltaic modules prepared from the white EVA encapsulating films provided in Comparative Examples 1-4 all showed a significant decrease in resistance to damp heat.

[0152] The applicant declares that this invention illustrates the low-corrosion white EVA encapsulating film, its preparation method, and its application through the above embodiments. However, this invention is not limited to the above embodiments, meaning that this invention does not necessarily rely on the above embodiments for implementation. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of the raw materials used, additions of auxiliary components, and selection of specific methods all fall within the protection and disclosure scope of this invention.

Claims

1. A low-corrosion white EVA encapsulating film, characterized in that, The low-corrosion white EVA encapsulation film comprises a first low-acid layer, a main EVA layer, and a second low-acid layer stacked sequentially. The raw materials for preparing the first low-acid layer include conventional EVA particles, low-acid EVA particles, and additives; The raw materials for preparing the main EVA layer include conventional EVA particles, titanium dioxide, and additives; The raw materials for preparing the second low-acid layer include conventional EVA particles, low-acid EVA particles, acid absorbent, and additives.

2. The low-corrosion white EVA encapsulating film according to claim 1, characterized in that, The additives in the first low-acid layer, the main EVA layer, and the second low-acid layer each independently include any one or a combination of at least two of the following: crosslinking agent, co-crosslinking agent, acrylate, tackifier, and light stabilizer.

3. The low-corrosion white EVA encapsulating film according to claim 1 or 2, characterized in that, The raw materials for preparing the first low-acid layer include the following components by weight: Preferably, the raw materials for preparing the main EVA layer include the following components by weight: Preferably, the raw materials for preparing the second low-acid layer include the following components by weight:

4. The low-corrosion white EVA encapsulating film according to claim 2 or 3, characterized in that, The crosslinking agent includes any one or a combination of at least two of the following: 2-ethylhexyl tert-butyl peroxide, 2-ethylhexyl tert-amyl peroxide, methyl ethyl ketone peroxide, benzoyl peroxide, di-tert-butyl peroxide, and dicumyl hydroperoxide. Preferably, the crosslinking agent comprises any one or a combination of at least two of the following: triallyl isocyanurate, triallyl cyanurate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, tripropylene glycol diacrylate, dipropylene glycol diacrylate, and triethylene glycol methyl diacrylate. Preferably, the acrylate includes any one or a combination of at least two of propoxytrimethylolpropane triacrylate, trimethylolpropane triacrylate, polyethylene glycol diacrylate, and tricyclodecanedimethylol diacrylate. Preferably, the tackifier comprises any one or a combination of at least two of γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, 3-(methacryloxy)propyltriethoxysilane, 3-(methacryloxy)propyltrimethoxysilane, vinyltrimethoxysilane, and vinyltriethoxysilane. Preferably, the light stabilizer comprises any one or a combination of at least two of the following: bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, poly(4-hydroxy-2,2,6,6-tetramethyl-1-piperidinol) succinate, bis-2,2,6,6-tetramethylpiperidinol sebacate or hindered amine light stabilizers, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, tris(2,4-di-tert-butylphenyl) phosphite, and 2,2,6,6-tetramethyl-4-piperidinyl esters.

5. The low-corrosion white EVA encapsulating film according to any one of claims 1-4, characterized in that, The titanium dioxide includes rutile titanium dioxide produced by conventional sulfuric acid or chloride processes.

6. The low-corrosion white EVA encapsulating film according to any one of claims 1-5, characterized in that, The acid absorbent includes hydrotalcite; Preferably, the VA content of conventional EVA particles in the first low-acid layer, the main EVA layer, and the second low-acid layer is each independently 25%-30%, and the melt index is each independently 20-30 g / 10 min. Preferably, the VA content of the low-acid EVA particles in the first low-acid layer is 16%-18%, and the melt index is 10-15 g / 10 min; Preferably, the low-acid EVA particles in the second low-acid layer have a VA content of 3%-15% and a melt index of 2-5 g / 10 min.

7. The low-corrosion white EVA encapsulating film according to any one of claims 1-6, characterized in that, The thickness of the first low-acid layer is 0.1-0.15 mm; Preferably, the thickness of the main EVA layer is 0.4-0.5 mm; Preferably, the thickness of the second low-acid layer is 0.1-0.15 mm.

8. A method for preparing a low-corrosion white EVA encapsulating film as described in any one of claims 1-7, characterized in that, The preparation method includes the following steps: The raw materials for preparing the first low-acid layer, the main EVA layer, and the second low-acid layer are mixed separately, then cast and co-extruded, and post-treated to obtain the low-corrosion white EVA encapsulation film.

9. The preparation method according to claim 8, characterized in that, The post-processing includes cooling, edge trimming, and winding.

10. The application of a low-corrosion white EVA encapsulating film as described in any one of claims 1-7 in photovoltaic modules.

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