Packaging adhesive film and preparation method and application thereof

Abstract

The invention provides a packaging adhesive film and a preparation method and application thereof, the packaging adhesive film comprises a first EVA layer, a middle POE layer and a second EVA layer, the first EVA layer and the second EVA layer are prepared from the following raw materials: 80-99 parts of EVA resin, 0.01-0.1 part of a charge dissipation agent, 0.1-2 parts of a first cross-linking agent, 0.1-2 parts of a modified assistant cross-linking agent, 0.1-1 part of a silane coupling agent and 0.01-0.2 part of a first light stabilizer; the second EVA layer further comprises 0.01 to 0.2 part of an ultraviolet light absorber; the middle POE layer is prepared from the following raw materials: 60 to 80 parts of POE resin, 10 to 20 parts of modified POE resin, 10 to 20 parts of APAO resin, 0.1 to 2 parts of a second cross-linking agent, 0.1 to 2 parts of an assistant cross-linking agent and 0.01 to 0.2 part of a second light stabilizer. The packaging adhesive film has the advantages of excellent anti-PID performance, low haze and low auxiliary agent migration.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of photovoltaic adhesive film packaging, and particularly relates to a packaging adhesive film and a preparation method and application thereof. BACKGROUND

[0002] In the face of the urgent demand for global energy transformation, the photovoltaic industry is undergoing profound technological changes, and TOPCon cells are gradually becoming the core of this change due to their outstanding performance and potential. In the key stage of the photovoltaic industry's transition from P-type to N-type technology, TOPCon tunnel oxide passivation contact cells, as representatives of N-type cell technology, have rapidly grown into market-leading technologies due to their high conversion efficiency, low decay rate, and unique cost advantages. Currently, TOPcon cells have proposed a new structure, Polyfinger structure. Polyfinger technology refers to replacing the traditional full-area polysilicon layer with a local polysilicon finger structure, retaining high-doped polysilicon only in the metal grid line contact area, and processing other areas through etching or thinning. The core of the Polyfinger structure is a 1.5-2nm ultra-thin silicon oxide layer. The thickness of the ultra-thin silicon oxide layer must be thin enough to allow quantum tunneling to occur. However, such a thin ultra-thin silicon oxide layer faces significant challenges in terms of insulation performance and reliability when subjected to high electric fields. The electric field can accelerate the penetration of hydrogen ions and may directly damage the silicon oxide layer, compromising its passivation performance and tunneling characteristics.

[0003] With the continuous updating of cell technology, the packaging adhesive film, which is the core material for protecting the cell sheet, also needs further updating and upgrading. The types of photovoltaic packaging adhesive films mainly include EVA, POE, and EPE. Conventional EVA adhesive films have high adhesion and low cost, but their water vapor barrier ability is weak, their anti-potential-induced decay (PID) ability is weak, and their adhesive film haze is high. POE adhesive film has good weather resistance, low water vapor transmission rate, and good anti-PID performance, but POE is a non-polar material, which leads to slow absorption of additives and easy precipitation of additives, making it easy to slip during lamination of the assembly, affecting the assembly yield. EPE adhesive film combines the advantages of high adhesion, low cost, easy processing of EVA adhesive film and low water transmission, excellent anti-PID performance of POE adhesive film, but since POE is a non-polar material and EVA is a polar material, the additives in the adhesive film are mostly polar additives, therefore, the additives in the P layer of the EPE structure easily migrate to the E layer, reducing the crosslinking degree of the P layer and affecting the reliability of the assembly.

[0004] CN117987030A discloses an irradiation pre-cured intermediate layer composite photovoltaic packaging adhesive film, comprising a first EVA adhesive layer, a POE adhesive layer and a second EVA adhesive layer, a first anti-permeation barrier layer is provided between the first EVA adhesive layer and the POE adhesive layer, a second anti-permeation barrier layer is provided between the POE adhesive layer and the second EVA adhesive layer, the first anti-permeation barrier layer and the second anti-permeation barrier layer are both poly-4-methyl-1-pentene layers, and the poly-4-methyl-1-pentene layer is a transparent material with a crystallinity of 55-75%. The adhesive film can prevent the migration of polar additives in the POE adhesive layer to the first EVA adhesive layer and the second EVA adhesive layer, slow down the migration speed of the polar additives, and avoid the high rate of defective products such as cell piece string sliding produced during the production of pure POE adhesive layer; on the other hand, the irradiation pre-curing of the POE adhesive layer can also ensure the uniformity of the three-layer thickness during the assembly lamination process. However, the crystallinity of poly-4-methyl-1-pentene is 55-75%, which affects the light transmittance and mechanical properties of the packaging adhesive film.

[0005] CN113801584A discloses a photovoltaic packaging adhesive film for bonding a photovoltaic substrate and a cell together, comprising a POE layer made of polyolefin resin and additives, an EVA layer made of EVA resin and additives provided on one side of the POE layer, and a barrier layer provided between the POE layer and the EVA layer for bonding the POE layer and the EVA layer together and blocking the migration of substances between the POE layer and the EVA layer. The interlayer bonding force of the photovoltaic packaging adhesive film is not less than 50 N / cm. The photovoltaic packaging adhesive film has a simple structure, low cost, excellent interlayer bonding force, and additives will not precipitate from the surface of the film and between the layers to affect the assembly packaging, but its water vapor barrier ability needs to be improved.

[0006] CN116968356A discloses a preparation method of a composite EPE adhesive film, which is a laminated structure formed by melt co-extrusion; the preparation method comprises: mixing POE resin and additives to obtain POE mixture, mixing EVA resin and additives to obtain EVA mixture, mixing POE resin, EVA resin, coupling agent, crosslinking agent, aluminum oxide and silicon dioxide to obtain barrier layer mixture; preparing barrier film liquid; heating and plasticizing the POE mixture, the EVA mixture and the barrier layer mixture respectively; calendering the plasticized POE, the plasticized EVA and the plasticized barrier layer mixture into an EPE film according to the laminated structure; coating the barrier film liquid on the EPE film to obtain a composite EPE film. The packaging adhesive film has excellent PID resistance, high temperature and humidity resistance and high crosslinking degree, but its mechanical properties and light transmittance are not mentioned at all.

[0007] Therefore, it is a technical problem to be solved in the field to develop a packaging adhesive film with low haze, high bonding force, low additive migration and excellent potential-induced degradation resistance. Summary of the Invention

[0008] To address the shortcomings of existing technologies, the present invention aims to provide an encapsulating film, its preparation method, and its application. The present invention selects and blends the raw materials for preparing the EVA layer and POE layer, and the resulting encapsulating film is used in TOPcon batteries, exhibiting excellent anti-PID performance, low haze, high adhesion, excellent aging resistance, and low additive migration.

[0009] To achieve this objective, the present invention adopts the following technical solution:

[0010] In a first aspect, the present invention provides an encapsulating film, the encapsulating film comprising a first EVA layer, an intermediate POE layer and a second EVA layer, wherein the first EVA layer is bonded to glass and the second EVA layer is bonded to a battery cell.

[0011] The raw materials for preparing the first and second EVA layers both include, by weight:

[0012] 80-99 parts of EVA resin, 0.01-0.1 parts of charge dissipation agent, 0.1-2 parts of first crosslinking agent, 0.1-2 parts of modified co-crosslinking agent, 0.1-1 parts of silane coupling agent, and 0.01-0.2 parts of first light stabilizer;

[0013] The second EVA layer also includes 0.01-0.2 parts of ultraviolet light absorber;

[0014] The raw materials for preparing the intermediate POE layer include, by weight:

[0015] 60-80 parts of POE resin, 10-20 parts of modified POE resin, 10-20 parts of APAO resin, 0.1-2 parts of second crosslinking agent, 0.1-2 parts of co-crosslinking agent, and 0.01-0.2 parts of second light stabilizer.

[0016] In this invention, EVA resin reduces the haze of the encapsulating film and increases light transmittance, effectively increasing the light capture of the solar cell, thereby improving the photoelectric conversion efficiency and power of the module. Charge dissipation agents and light stabilizers effectively improve the anti-PID performance of the module after adopting a multi-busbar design for TOPcon cells. Modified crosslinking agents promote the formation of crosslinking networks, directly increasing the crosslinking degree of the encapsulating film, strengthening the adhesion between the encapsulating film and the glass and solar cell, and significantly improving peel strength. The second EVA layer also incorporates an ultraviolet absorber, which reduces the impact of ultraviolet light on the solar cell, protecting the solar cell and encapsulating material from ultraviolet damage. Simultaneously, it ensures high transmittance in the visible light band, maximizing the utilization of effective incident light by the cell. The intermediate POE layer uses modified POE resin and APAO resin, which improves the adhesion between the intermediate POE layer and the EVA layer, effectively reducing delamination after EPE film aging, and reducing the migration rate of additives. The second crosslinking agent and co-crosslinking agent further increase the crosslinking degree, thereby improving the mechanical properties of the encapsulating film. This invention selects and blends the raw materials for preparing EVA and POE layers to prepare an encapsulating film for TOPcon batteries. The film exhibits excellent anti-PID properties, low haze, high adhesion, excellent aging resistance, and low additive migration.

[0017] The amount of EVA resin used can be 80 parts, 81 parts, 82 parts, 83 parts, 84 parts, 85 parts, 86 parts, 87 parts, 88 parts, or 89 parts, etc.

[0018] The amount of the charge dissipating agent can be 0.01 parts, 0.03 parts, 0.05 parts, 0.07 parts, 0.09 parts, or 0.1 parts, etc.

[0019] The amounts of the first crosslinking agent and the second crosslinking agent can be 0.1 parts, 0.3 parts, 0.5 parts, 0.7 parts, 0.9 parts, 1.1 parts, 1.3 parts, 1.5 parts, 1.7 parts, 1.9 parts, or 2 parts, etc.

[0020] The amount of the modified crosslinking agent can be 0.1 parts, 0.3 parts, 0.5 parts, 0.7 parts, 0.9 parts, 1.1 parts, 1.3 parts, 1.5 parts, 1.7 parts, 1.9 parts, or 2 parts, etc.

[0021] The amount of the silane coupling agent can be 0.1 parts, 0.3 parts, 0.5 parts, 0.7 parts, 0.9 parts, or 1 part, etc.

[0022] The amounts of the first and second light stabilizers can be 0.01 parts, 0.03 parts, 0.05 parts, 0.07 parts, 0.09 parts, 0.1 parts, 0.3 parts, 0.5 parts, 0.7 parts, 0.9 parts, 1.1 parts, 1.3 parts, 1.5 parts, 1.7 parts, 1.9 parts, or 2 parts, etc.

[0023] The amount of the ultraviolet absorber can be 0.01 parts, 0.03 parts, 0.05 parts, 0.07 parts, 0.09 parts, 0.1 parts, 0.3 parts, 0.5 parts, 0.7 parts, 0.9 parts, 1.1 parts, 1.3 parts, 1.5 parts, 1.7 parts, 1.9 parts, or 2 parts, etc.

[0024] The amount of POE resin used can be 60 parts, 62 parts, 64 parts, 66 parts, 68 parts, 70 parts, 72 parts, 74 parts, 76 parts, 78 parts, or 80 parts, etc.

[0025] The amount of the modified POE resin can be 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, or 20 parts, etc.

[0026] The amount of APAO resin used can be 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, or 20 parts, etc.

[0027] The amount of the crosslinking agent can be 0.1 parts, 0.3 parts, 0.5 parts, 0.7 parts, 0.9 parts, 1.1 parts, 1.3 parts, 1.5 parts, 1.7 parts, 1.9 parts, or 2 parts, etc.

[0028] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The purpose and beneficial effects of the present invention can be better achieved and realized through the following preferred technical solutions.

[0029] Preferably, the modified co-crosslinking agent is obtained by reacting triallyl isocyanurate and silane.

[0030] Preferably, the modified crosslinking agent is selected from at least one of the following structures:

[0031] , .

[0032] Preferably, the thickness of the first EVA layer and the second EVA layer are each independently 100-200μm, such as 100μm, 110μm, 120μm, 130μm, 140μm, 150μm, 160μm, 170μm, 180μm, 190μm or 200μm.

[0033] Preferably, the thickness of the intermediate POE layer is 100-250μm, such as 110μm, 130μm, 150μm, 170μm, 190μm, 210μm, 230μm or 250μm.

[0034] Preferably, the mass percentage of VA in the EVA resin is 30%-35%, such as 30%, 31%, 32%, 33%, 34% or 35%.

[0035] In this invention, the mass percentage of VA in the EVA resin is 30%-35%, which ensures that the encapsulation film has high light transmittance, low haze, reliable adhesion, and excellent aging resistance. If the VA content is too low, the adhesion and light transmittance of the encapsulation film will decrease, and the haze will increase, which will not only affect the effective optical utilization of the solar cell, but also pose a risk of delamination. If the VA content is too high, the anti-PID performance will decrease significantly, and at the same time, the mechanical properties and stability of the encapsulation film will be reduced.

[0036] Preferably, the melt index of the EVA resin is 15-45 g / 10 min, such as 15 g / 10 min, 17 g / 10 min, 19 g / 10 min, 21 g / 10 min, 23 g / 10 min, 25 g / 10 min, 27 g / 10 min, 29 g / 10 min, 31 g / 10 min, 33 g / 10 min, 35 g / 10 min, 37 g / 10 min, 39 g / 10 min, 41 g / 10 min, 43 g / 10 min, or 45 g / 10 min.

[0037] Preferably, the charge dissipating agent comprises any one or a combination of at least two of sodium dodecylbenzenesulfonate, ammoniacal ethylene oxide, sodium dodecyl sulfate, sodium dodecyl sulfonate, or alkyl phosphate.

[0038] Preferably, the first crosslinking agent comprises any one or a combination of at least two of the following: tert-amyl peroxy(2-ethylhexyl)carbonate, tert-butyl peroxycarbonate-2-ethylhexyl, trimethyltrivinylcyclotrisiloxane, or tetramethyltetravinylcyclotetrasiloxane.

[0039] Preferably, the silane coupling agent comprises any one or a combination of at least two of vinyltrimethoxysilane, vinyltriethoxysilane, or vinyltritert-butylperoxysilane.

[0040] Preferably, the first light stabilizer and the second light stabilizer each independently comprise any one or a combination of at least two of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, bis(1-octoxy-2,2,6,6-tetramethyl-4-piperidinyl) sebacate, hexadecyl 3,5-di-tert-butyl-4-hydroxybenzoate, or bis-2,2,6,6-tetramethylpiperidinol sebacate.

[0041] Preferably, the melt index of the POE resin is 5-14 g / 10 min, such as 5 g / 10 min, 6 g / 10 min, 7 g / 10 min, 8 g / 10 min, 9 g / 10 min, 10 g / 10 min, 11 g / 10 min, 12 g / 10 min, 13 g / 10 min, or 14 g / 10 min.

[0042] Preferably, the modified POE resin is formed by grafting and modifying triallyl isocyanurate, fumed silica, and POE resin.

[0043] Preferably, the APAO resin is obtained by polymerizing ethylene and propylene.

[0044] Preferably, the softening point of the APAO resin is 90-100℃, such as 90℃, 91℃, 92℃, 93℃, 94℃, 95℃, 96℃, 97℃, 98℃, 99℃ or 100℃.

[0045] Preferably, the viscosity of the APAO resin at 25°C is 40,000-80,000 mPa·s, such as 40,000 mPa·s, 45,000 mPa·s, 50,000 mPa·s, 55,000 mPa·s, 60,000 mPa·s, 65,000 mPa·s, 70,000 mPa·s, 75,000 mPa·s, or 80,000 mPa·s.

[0046] Preferably, the second crosslinking agent comprises any one or a combination of at least two of the following: tert-amyl peroxy(2-ethylhexyl)carbonate, tert-butyl peroxycarbonate-2-ethylhexyl, azobisisobutyronitrile, or benzoyl peroxide.

[0047] Preferably, the co-crosslinking agent comprises any one or a combination of at least two of triallyl isocyanurate, trimethylolpropane triacrylate, glyceryl ethoxylate triacrylate, pentaerythritol tetraacrylate, pentaerythritol triacrylate, or tetramethyltetravinylcyclotetrasiloxane.

[0048] Preferably, the ultraviolet absorber comprises any one or a combination of at least two of 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-cresol, 2,4-dihydroxybenzophenone, or phenyl salicylate.

[0049] In a second aspect, the present invention provides a method for preparing an encapsulating film as described in the first aspect, the method comprising the following steps:

[0050] The raw materials for preparing the first EVA layer, the raw materials for preparing the intermediate POE layer, and the raw materials for preparing the second EVA layer are mixed evenly and then cast to obtain the encapsulating film.

[0051] Preferably, the casting temperature is 90-100℃, such as 90℃, 91℃, 92℃, 93℃, 94℃, 95℃, 96℃, 97℃, 98℃, 99℃ or 100℃.

[0052] In a second aspect, the present invention provides an application of the encapsulating film as described in the first aspect in a TOPcon battery.

[0053] Compared with the prior art, the present invention has the following beneficial effects:

[0054] This invention selects and blends the raw materials for preparing the EVA and POE layers, achieving a high degree of crosslinking. The resulting encapsulating film, used in TOPcon batteries, exhibits excellent anti-PID properties, low haze, high adhesion, excellent aging resistance, high temperature and humidity resistance, and low additive migration. Specifically, it boasts a crosslinking degree ≥85%, anti-PID performance ≤2.1%, haze ≤2.8%, initial peel strength ≥125 N / cm, and no delamination after 48 h of PCT aging, UV aging, and 2000 h of damp heat resistance testing. After aging tests, the peel strength is consistently ≥50 N / cm. Detailed Implementation

[0055] 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.

[0056] The source information of some raw materials in this embodiment of the invention is as follows:

[0057] EVA resin (VA content 33%): Lianhong New Technology, UL01833;

[0058] EVA resin (VA content 20%): Sinopec, 20F20;

[0059] EVA resin (VA content 40%): Mitsui, 40W;

[0060] POE resin: Jingbo Petrochemical, PV7200;

[0061] APAO resin: Evonik Chemicals, 751;

[0062] Modified POE resin: 10 parts triallyl cyanurate, 2 parts fumed silica, 87.8 parts POE resin and 0.2 parts 2,2'-azobis(2-methylpropanediamine) dihydrochloride (DBPH) were uniformly mixed and added to a twin-screw extruder at a temperature of 160℃ for graft modification to obtain modified POE resin.

[0063] Example 1

[0064] This embodiment provides an encapsulation film comprising a three-layer structure, consisting of a first EVA layer bonded to glass, an intermediate POE layer, and a second EVA layer bonded to a battery cell. The thickness of the first EVA layer is 150 μm, the thickness of the intermediate POE layer is 200 μm, and the thickness of the second EVA layer is 150 μm.

[0065] The raw materials for preparing the first EVA layer include the following components by weight: 98.05 parts of EVA resin (VA content 33%), 0.05 parts of sodium dodecylbenzenesulfonate, 0.6 parts of tert-butylperoxycarbonate-2-ethylhexyl, 0.3 parts of tetramethyltetravinylcyclotetrasiloxane, 0.5 parts of 1,3-bis(allyl)-5-(3-trimethoxysilylpropyl)triisocyanate, 0.4 parts of vinyltrimethoxysilane, and 0.1 parts of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate.

[0066] The raw materials for preparing the intermediate POE layer include the following components by weight: 73.6 parts of POE resin, 15 parts of modified POE resin, 10 parts of APAO resin, 0.8 parts of tert-butyl peroxycarbonate-2-ethylhexyl, 0.5 parts of triallyl isocyanurate, and 0.1 parts of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate.

[0067] The raw materials for preparing the second EVA layer include the following components by weight: 97.85 parts of EVA resin (VA content 33%), 0.05 parts of sodium dodecylbenzenesulfonate, 0.6 parts of tert-butylperoxycarbonate-2-ethylhexyl, 0.3 parts of tetramethyltetravinylcyclotetrasiloxane, 0.5 parts of 1,3-bis(allyl)-5-(3-trimethoxysilylpropyl)triisocyanate, 0.4 parts of vinyltrimethoxysilane, 0.2 parts of 2,4-dihydroxybenzophenone, and 0.1 parts of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate.

[0068] After the raw materials for each layer are mixed evenly according to the above ratio, the mixture is cast at 95°C using a three-layer casting equipment to obtain the encapsulating film.

[0069] Example 2

[0070] This embodiment provides an encapsulation film comprising a three-layer structure, consisting of a first EVA layer bonded to glass, an intermediate POE layer, and a second EVA layer bonded to a battery cell. The thickness of the first EVA layer is 110 μm, the thickness of the intermediate POE layer is 240 μm, and the thickness of the second EVA layer is 110 μm.

[0071] The raw materials for preparing the first EVA layer include the following components by weight: 85 parts of EVA resin (VA content 33%), 0.01 parts of sodium dodecyl sulfonate, 1.8 parts of trimethyltrivinylcyclotrisiloxane, 0.5 parts of vinyltritert-butylperoxysilane, 1.5 parts of 1,3-bis(allyl)-5-(3-trimethoxysilylpropyl)triisocyanate, 0.2 parts of vinyltriethoxysilane, and 0.05 parts of bis(1-octoxy-2,2,6,6-tetramethyl-4-piperidinyl) sebacate.

[0072] The raw materials for preparing the intermediate POE layer include the following components by weight: 63 parts POE resin, 15 parts modified POE resin, 10 parts APAO resin, 2 parts tert-butylperoxycarbonate-2-ethylhexyl, 1 part trimethylolpropane triacrylate, and 0.2 parts bis(1-octoxy-2,2,6,6-tetramethyl-4-piperidinyl) sebacate.

[0073] The raw materials for preparing the second EVA layer include the following components by weight: 80 parts of EVA resin (VA content 33%), 0.02 parts of sodium dodecyl sulfonate, 0.1 parts of tert-butyl peroxycarbonate-2-ethylhexyl, 1.9 parts of tetramethyltetravinylcyclotetrasiloxane, 2 parts of 1,3-bis(allyl)-5-(3-trimethoxysilylpropyl)triisocyanate, 1 part of vinyltritert-butylperoxysilane, 0.2 parts of 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-cresol, and 0.2 parts of sebacic acid bis-2,2,6,6-tetramethylpiperidinol.

[0074] After the raw materials for each layer are mixed evenly according to the above ratio, they are cast at 90°C using a three-layer casting equipment to obtain the encapsulating film.

[0075] Example 3

[0076] This embodiment provides an encapsulation film comprising a three-layer structure, consisting of a first EVA layer bonded to glass, an intermediate POE layer, and a second EVA layer bonded to a battery cell. The thickness of the first EVA layer is 195 μm, the thickness of the intermediate POE layer is 100 μm, and the thickness of the second EVA layer is 195 μm.

[0077] The raw materials for preparing the first EVA layer include the following components by weight: 81 parts of EVA resin (VA content 33%), 0.01 parts of sodium dodecyl sulfate, 0.2 parts of tert-amyl (2-ethylhexyl) carbonate, 2 parts of tetramethyltetravinylcyclotetrasiloxane, 2 parts of 1,3-bis(allyl)-5-(3-trimethoxysilylpropyl)triisocyanate, 1 part of vinyltrimethoxysilane, and 0.2 parts of hexadecyl 3,5-di-tert-butyl-4-hydroxybenzoate.

[0078] The raw materials for preparing the intermediate POE layer include the following components by weight: 76 parts of POE resin, 15 parts of modified POE resin, 10 parts of APAO resin, 0.2 parts of tert-butylperoxycarbonate-2-ethylhexyl, pentaerythritol triacrylate and 0.01 parts of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate.

[0079] The raw materials for preparing the second EVA layer include the following components by weight: 85 parts of EVA resin (VA content 33%), 0.1 parts of sodium dodecyl sulfate, 2 parts of tert-butyl peroxycarbonate-2-ethylhexyl, 0.5 parts of tetramethyltetravinylcyclotetrasiloxane, 0.2 parts of 1,3-bis(allyl)-5-(3-trimethoxysilylpropyl)triisocyanate, 0.2 parts of vinyltrimethoxysilane, 0.08 parts of phenyl salicylate, and 0.04 parts of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate.

[0080] After the raw materials for each layer are mixed evenly according to the above ratio, they are cast at 100°C using a three-layer casting equipment to obtain the encapsulating film.

[0081] Example 4

[0082] The difference from Example 1 is that in the middle POE layer, the amount of APAO resin is 15 parts, the amount of modified POE resin is 15 parts, and the amount of POE resin is 68.6 parts. The amount of other components and the preparation method are the same as in Example 1.

[0083] Example 5

[0084] The difference from Example 1 is that in the middle POE layer, the amount of APAO resin is 20 parts, the amount of modified POE resin is 15 parts, and the amount of POE resin is 63.6 parts. The amount of other components and the preparation method are the same as in Example 1.

[0085] Example 6

[0086] The difference from Example 1 is that in the middle POE layer, the amount of APAO resin is 10 parts, the amount of modified POE resin is 10 parts, and the amount of POE resin is 78.6 parts. The amount of other components and the preparation method are the same as in Example 1.

[0087] Example 7

[0088] The difference from Example 1 is that in the middle POE layer, the amount of APAO resin is 10 parts, the amount of modified POE resin is 20 parts, and the amount of POE resin is 68.6 parts. The amount of other components and the preparation method are the same as in Example 1.

[0089] Comparative Example 1

[0090] The difference from Example 1 is that the VA content in the EVA resin in the first EVA layer and the second EVA layer is 20%, while the amount of other components and the preparation method are the same as in Example 1.

[0091] Comparative Example 2

[0092] The difference from Example 1 is that the VA content in the EVA resin in the first EVA layer and the second EVA layer is 40%, while the amount of other components and the preparation method are the same as in Example 1.

[0093] Comparative Example 3

[0094] The difference from Example 1 is that in the first and second EVA layers, 1,3-bis(allyl)-5-(3-trimethoxysilylpropyl)triisocyanate is replaced with an equal amount of triallyl isocyanurate, while the amounts of the remaining components and the preparation methods are the same as in Example 1.

[0095] Comparative Example 4

[0096] The difference from Example 1 is that modified POE resin and APAO resin are not used in the intermediate POE layer, the amount of POE resin is 98.6 parts, and the amount of other components and the preparation method are the same as in Example 1.

[0097] Comparative Example 5

[0098] The difference from Example 1 is that sodium dodecylbenzenesulfonate is not added to the first and second EVA layers, while the amounts and preparation methods of the remaining components are the same as in Example 1.

[0099] Comparative Example 6

[0100] The difference from Example 1 is that in the middle POE layer, the amount of POE resin is 94.6 parts, the amount of modified POE resin is 2 parts, and the amount of APAO resin is 2 parts. The amount of other components and the preparation method are the same as in Example 1.

[0101] Comparative Example 7

[0102] The difference from Example 1 is that in the middle POE layer, the amount of POE resin is 38.6 parts, the amount of modified POE resin is 30 parts, and the amount of APAO resin is 30 parts. The amount of other components and the preparation method are the same as in Example 1.

[0103] Performance testing

[0104] (1) Crosslinking degree: Tested according to GB / T 29848-2018. Lamination conditions: In a vacuum laminator, pressurized at 145℃ for 15 min, and the crosslinking degree was tested by xylene extraction method.

[0105] (2) Haze: Tested according to GB / T 2410-2008. Lamination conditions: In a vacuum laminator, pressurized at 145℃ for 15 minutes.

[0106] (3) PID: The test was conducted in accordance with IEC TS 62804-1:2015. The test conditions were 85℃, 85%RH, and an external constant DC voltage of -1500V. After 192 hours, the power attenuation of the component before and after the PID test was measured.

[0107] (4) Peel strength: The encapsulating films (EPE encapsulating films) prepared in the examples and comparative examples were cut into A4 size. According to the test method of GB / T 29848-2018, the films were placed in a vacuum laminator in the order of "glass / encapsulating film / backsheet" and laminated at 145°C for 15 min to prepare samples. Then, the samples were subjected to PCT aging test, UV aging test and high temperature and humidity aging test, and the adhesion data were recorded to observe whether there was delamination of the components.

[0108] (5) Power of photovoltaic modules: tested in accordance with GB / T 45021-2024.

[0109] (6) PCT aging test: The test shall be conducted in accordance with GB / T 41203-2021.

[0110] (7) UV aging resistance test: The test shall be conducted in accordance with GB / T 16422.3-2019.

[0111] (8) High temperature and high humidity aging resistance test: The test shall be conducted in accordance with GB / T 2423.3-2006.

[0112] The encapsulating films provided in the examples and comparative examples were tested according to the above performance testing methods, and the results are shown in Table 1-2:

[0113] Table 1

[0114]

[0115] Table 2

[0116]

[0117] As shown in Table 1-2, the encapsulating films prepared in Examples 1-7 of this invention, when used in TOPcon batteries, exhibit excellent anti-PID performance, low haze, high adhesion, excellent aging resistance, high temperature and humidity resistance, and low additive migration. Specifically, the degree of crosslinking is ≥85%, anti-PID performance is ≤2.1%, haze is ≤2.8%, initial peel strength is ≥125 N / cm, and no delamination occurs after 48 h of PCT aging, UV aging, and 2000 h of damp heat resistance testing. The peel strength after aging tests is ≥50 N / cm.

[0118] As can be seen from the comparison between Example 1 and Comparative Examples 1-2, if the VA content in the EVA resin is too low, the degree of crosslinking of the encapsulation film will decrease, the haze will increase, and the anti-PID performance, peel strength, resistance to PCT aging, UV aging and damp heat aging performance will all decrease. If the VA content in the EVA resin is too high, it will also lead to an increase in film haze, a decrease in peel strength, a decrease in crosslinking, and delamination of the encapsulation film.

[0119] As can be seen from the comparison between Example 1 and Comparative Example 3, the modified crosslinking aid helps to improve the degree of crosslinking and the peel force of the encapsulating film, thereby improving the resistance to PCT aging, UV aging and damp heat aging.

[0120] As can be seen from the comparison of Example 1 and Comparative Examples 4, 6, and 7, the addition of modified POE resin and APAO resin can improve the crosslinking degree of the encapsulating film, forming a denser three-dimensional network, thereby improving the peel strength of the encapsulating film and enhancing its resistance to PCT aging, UV aging, and damp heat aging. If the amount of modified POE resin and APAO resin added to the encapsulating film is too high or too low, the overall performance of the encapsulating film will deteriorate.

[0121] As can be seen from the comparison between Example 1 and Comparative Example 5, the charge dissipation agent can significantly improve the anti-PID performance of the TOPcon battery module after adopting Polyfinger.

[0122] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. An encapsulating film, characterized in that, The encapsulating film includes a first EVA layer, an intermediate POE layer, and a second EVA layer. The first EVA layer is bonded to the glass, and the second EVA layer is bonded to the battery cell. The raw materials for preparing the first and second EVA layers both include, by weight: 80-99 parts of EVA resin, 0.01-0.1 parts of charge dissipation agent, 0.1-2 parts of first crosslinking agent, 0.1-2 parts of modified co-crosslinking agent, 0.1-1 parts of silane coupling agent, and 0.01-0.2 parts of first light stabilizer; The second EVA layer also includes 0.01-0.2 parts of ultraviolet light absorber; The raw materials for preparing the intermediate POE layer include, by weight: 60-80 parts of POE resin, 10-20 parts of modified POE resin, 10-20 parts of APAO resin, 0.1-2 parts of second crosslinking agent, 0.1-2 parts of co-crosslinking agent, and 0.01-0.2 parts of second light stabilizer.

2. The encapsulating film according to claim 1, characterized in that, The modified co-crosslinking agent is obtained by reacting triallyl isocyanurate and silane; Preferably, the modified crosslinking agent is selected from at least one of the following structures: 、 。 3. The encapsulating film according to claim 1 or 2, characterized in that, The thickness of the first EVA layer and the second EVA layer are each independently 100-200 μm; Preferably, the thickness of the intermediate POE layer is 100-250 μm.

4. The encapsulating film according to any one of claims 1-3, characterized in that, The mass percentage of VA in the EVA resin is 30%-35%; Preferably, the melt index of the EVA resin is 15-45 g / 10 min; Preferably, the charge dissipating agent comprises any one or a combination of at least two of sodium dodecylbenzenesulfonate, ammoniacal ethylene oxide, sodium dodecyl sulfate, sodium dodecyl sulfonate, or alkyl phosphate.

5. The encapsulating film according to any one of claims 1-4, characterized in that, The first crosslinking agent includes any one or a combination of at least two of the following: tert-amyl peroxy(2-ethylhexyl)carbonate, tert-butyl peroxycarbonate-2-ethylhexyl, trimethyltrivinylcyclotrisiloxane, or tetramethyltetravinylcyclotetrasiloxane; Preferably, the silane coupling agent comprises any one or a combination of at least two of vinyltrimethoxysilane, vinyltriethoxysilane, or vinyltritert-butylperoxysilane; Preferably, the first light stabilizer and the second light stabilizer each independently comprise any one or a combination of at least two of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, bis(1-octoxy-2,2,6,6-tetramethyl-4-piperidinyl) sebacate, hexadecyl 3,5-di-tert-butyl-4-hydroxybenzoate, or bis-2,2,6,6-tetramethylpiperidinol sebacate.

6. The encapsulating film according to any one of claims 1-5, characterized in that, The melt index of the POE resin is 5-14 g / 10 min; Preferably, the modified POE resin is formed by grafting and modifying triallyl isocyanurate, fumed silica, and POE resin. Preferably, the APAO resin is obtained by polymerization of ethylene and propylene; Preferably, the softening point of the APAO resin is 90-100℃; Preferably, the viscosity of the APAO resin at 25°C is 40,000-80,000 mPa·s.

7. The encapsulating film according to any one of claims 1-6, characterized in that, The second crosslinking agent includes any one or a combination of at least two of the following: tert-amyl peroxy(2-ethylhexyl)carbonate, tert-butyl peroxycarbonate-2-ethylhexyl, azobisisobutyronitrile, or benzoyl peroxide; Preferably, the co-crosslinking agent comprises any one or a combination of at least two of triallyl isocyanurate, trimethylolpropane triacrylate, glyceryl ethoxylate triacrylate, pentaerythritol tetraacrylate, pentaerythritol triacrylate, or tetramethyltetravinylcyclotetrasiloxane. Preferably, the ultraviolet absorber comprises any one or a combination of at least two of 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-cresol, 2,4-dihydroxybenzophenone, or phenyl salicylate.

8. A method for preparing an 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 EVA layer, the raw materials for preparing the intermediate POE layer, and the raw materials for preparing the second EVA layer are mixed evenly and then cast to obtain the encapsulating film.

9. The preparation method according to claim 8, characterized in that, The casting temperature is 90-100℃.

10. The application of an encapsulating film as described in any one of claims 1-7 in a TOPcon battery.

Images