Encapsulation adhesive film, method for preparing the same, and photovoltaic module

Abstract

The application relates to the field of photovoltaic technology, in particular to a packaging adhesive film, a preparation method thereof and a photovoltaic module. The packaging adhesive film comprises 60-80 parts of ethylene-octene polymer, 5-20 parts of star-shaped styrene-butadiene block copolymer masterbatch, 1-10 parts of a compatilizer, 5-20 parts of a polar masterbatch, 0.1-1.0 parts of a crosslinking agent, 0.1-1 part of an auxiliary crosslinking agent, 0.1-1 part of a first anti-separation agent, 0.1-1 part of a second anti-separation agent and 0.05-0.5 part of an antioxidant; the first anti-separation agent comprises hydroxyl-terminated polybutadiene and long-chain alkyl silane at a mass ratio of (1.5-4):1; and the second anti-separation agent comprises hydroxyl-terminated polydimethylsiloxane and long-chain alkyl silane at a mass ratio of (1.5-4):1. The packaging adhesive film has excellent anti-slip performance and low auxiliary agent migration performance.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic technology, and in particular to an encapsulating film, its preparation method, and a photovoltaic module. Background Technology

[0002] POE photovoltaic encapsulant films have gained widespread attention in recent years due to their outstanding barrier properties and excellent weather resistance. Made primarily of POE (ethylene-octene polymer), POE's structure is dominated by carbon-carbon and carbon-hydrogen bonds, resulting in non-polar molecules and low water vapor permeability, making it more suitable for humid environments. Furthermore, POE photovoltaic encapsulant films are relatively stable and have good weather resistance. Their unique molecular structure also prevents charge polarization and migration, making them a growing alternative to EVA films and leading to their widespread use in double-glass photovoltaic modules. However, as an elastomer, the encapsulant film exhibits thermal expansion and contraction due to storage and transportation conditions. Before lamination, POE in the encapsulant film is in a single-component form. The various formulation raw materials and additives are adsorbed onto the surface of EVA / POE particles through mixing and stirring. However, due to storage or transportation conditions, especially high temperatures, some highly active additives can easily migrate and precipitate onto the film surface, causing adhesion. On the other hand, polar additives precipitate from the interior of the encapsulant film to its surface, reducing the surface friction coefficient. This can easily cause cell slippage during module manufacturing, leading to module degradation. Although this can be mitigated by adding positioning tapes and spot welding to the cells, it still impacts module production efficiency to some extent. In particular, some crosslinking agents and silane coupling agents change from liquid to solid at lower temperatures. Since they are only physically melted and blended within the encapsulant film without undergoing a chemical reaction, the additive morphology changes within the film, resulting in insufficient crosslinking.

[0003] In view of this, the present invention is hereby proposed. Summary of the Invention

[0004] One object of the present invention is to provide an encapsulating film with excellent anti-slip properties and anti-additive exudation properties.

[0005] Another object of the present invention is to provide a method for preparing an encapsulating film.

[0006] Another object of the present invention is to provide a photovoltaic module.

[0007] To achieve the above-mentioned objectives of the present invention, one aspect of the present invention provides an encapsulating film, which is mainly prepared from the following components in parts by weight:

[0008] The mixture contains 60-80 parts of ethylene-octene polymer, 5-20 parts of star-shaped styrene-butadiene block copolymer masterbatch, 1-10 parts of compatibilizer, 5-20 parts of polar masterbatch, 0.1-1.0 parts of crosslinking agent, 0.1-1 parts of co-crosslinking agent, 0.1-1 parts of first anti-exudation agent, 0.1-1 parts of second anti-exudation agent, and 0.05-0.5 parts of antioxidant.

[0009] The first anti-precipitation agent comprises hydroxyl-terminated polybutadiene and long-chain alkylsilane in a mass ratio of (1.5–4):1; the second anti-precipitation agent comprises hydroxyl-terminated polydimethylsiloxane and long-chain alkylsilane in a mass ratio of (1.5–4):1.

[0010] In a specific embodiment of the present invention, the hydroxyl value of the hydroxyl-terminated polybutadiene is 0.47 to 0.80 mmol / g.

[0011] In a specific embodiment of the present invention, the molecular weight of the hydroxyl-terminated polydimethylsiloxane is 1000-4000 g / mol.

[0012] In a specific embodiment of the present invention, the long-chain alkylsilane includes at least one of vinyltris(β-methoxyethoxy)silane, 3-methacryloyloxypropyltrimethoxysilane, octyltrimethoxysilane, n-decyltrimethoxysilane, dodecyltrimethoxysilane, and hexadecyltrimethoxysilane.

[0013] In a specific embodiment of the present invention, the preparation of the first anti-precipitation agent includes: mixing the terminal hydroxyl polybutadiene and the long-chain alkylsilane at 50-70°C in proportion.

[0014] In a specific embodiment of the present invention, the preparation of the second anti-precipitation agent includes: mixing the terminal hydroxyl polydimethylsiloxane and the long-chain alkylsilane at 50-70°C in proportion.

[0015] In a specific embodiment of the present invention, the star-shaped styrene-butadiene block copolymer masterbatch comprises ethylene-octene polymer and star-shaped styrene-butadiene block copolymer in a mass ratio of (3-5):1.

[0016] In a specific embodiment of the present invention, the mass ratio of styrene to butadiene in the star-shaped styrene-butadiene block copolymer is (2-6):(8-4).

[0017] In a specific embodiment of the present invention, the polar masterbatch is a silane coupling agent modified POE masterbatch. Further, the silane coupling agent includes at least one selected from 3-methacryloyloxypropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, and vinyltris(β-methoxyethoxy)silane.

[0018] In a specific embodiment of the present invention, the polar masterbatch is mainly prepared from POE resin, silane coupling agent and initiator. Further, the polar masterbatch is mainly prepared from 100 parts of POE resin, 1 to 5 parts of silane coupling agent and 0.01 to 0.1 parts of initiator by weight.

[0019] In a specific embodiment of the present invention, the compatibilizer includes at least one of maleic anhydride-grafted ethylene-octene copolymer, maleic anhydride-grafted ethylene-butene copolymer, and maleic anhydride-grafted SEBS copolymer.

[0020] In a specific embodiment of the present invention, the crosslinking agent includes at least one of tert-butyl peroxycarbonate-2-ethylhexyl ester, cumene peroxide, tert-amyl peroxycarbonate-2-ethylhexyl ester, and tert-butyl peroxycarbonate-2-ethylhexyl ester; the co-crosslinking agent includes at least one of triallyl isocyanurate, triallyl cyanurate, and trimethylolpropane trimethacrylate.

[0021] Another aspect of the present invention provides a method for preparing an encapsulating film, comprising the following steps:

[0022] (a) After uniformly mixing polar masterbatch, crosslinking agent, co-crosslinking agent, first anti-precipitation agent, second anti-precipitation agent and antioxidant, the mixture is melt-granulated to obtain mixed masterbatch;

[0023] (b) The mixed masterbatch is mixed evenly with ethylene-octene polymer, star-shaped styrene-butadiene block copolymer masterbatch and compatibilizer, then melt-extruded, drawn and cooled to form a film, and then subjected to irradiation pre-crosslinking treatment.

[0024] In a specific embodiment of the present invention, in step (b), the temperature of the melt extrusion is 70–95°C.

[0025] In a specific embodiment of the present invention, in step (a), the temperature of the melt granulation is 70 to 120°C.

[0026] The present invention also provides a photovoltaic module comprising any of the encapsulating films described above.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] (1) By introducing star-shaped styrene-butadiene block copolymer masterbatch, the present invention enables its multiple molecular chain tentacles to entangle with POE molecular chains, adsorb and fix additives, prevent additive migration, and improve the crosslinking degree of the film. On the other hand, the molecular chain tentacles can increase the adsorption capacity of the film to the battery cell and glass on the film surface, and improve the anti-slip performance of the film.

[0029] (2) This invention introduces a specific anti-exudation agent. The anti-exudation agent has a polar molecular cage structure with interlocking molecular chains. A portion of the polar small molecule liquid additive is adsorbed on the cage surface and a portion is bound inside the cage structure, forming a cage effect to prevent the additive from migrating. Furthermore, the alkylsilane coupling agent and the long-chain terminal hydroxyl polybutadiene molecular chain in the first anti-exudation agent have good compatibility with the non-polar POE molecular chain, which can better keep the additive inside the POE resin. The terminal hydroxyl polydimethylsiloxane molecular chain in the second anti-exudation agent has hydroxyl groups at both ends. Under the same addition amount, the lower the molecular weight, the higher the molar amount of hydroxyl groups, and the higher the polarity, the more polar additives can be adsorbed. On the other hand, the hydroxyl groups of the molecular chain segments can form strong hydrogen bonds with the first exudation agent, which can be indirectly locked inside the POE resin. Moreover, the polar cage structure on the surface of the film can adsorb the battery cell and glass through van der Waals forces, which can play an anti-slip role.

[0030] (3) The photovoltaic module made by the present invention using encapsulation film can avoid the phenomenon of slippage between glass and cell, avoid module degradation, and improve module production efficiency. Detailed Implementation

[0031] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0032] The encapsulating film is mainly composed of the following components in parts by weight:

[0033] The mixture contains 60-80 parts of ethylene-octene polymer, 5-20 parts of star-shaped styrene-butadiene block copolymer masterbatch, 1-10 parts of compatibilizer, 5-20 parts of polar masterbatch, 0.1-1 parts of crosslinking agent, 0.1-1 parts of co-crosslinking agent, 0.1-1 parts of first anti-exudation agent, 0.1-1 parts of second anti-exudation agent, and 0.05-0.5 parts of antioxidant.

[0034] The first anti-precipitation agent comprises hydroxyl-terminated polybutadiene and long-chain alkylsilane in a mass ratio of (1.5–4):1; the second anti-precipitation agent comprises hydroxyl-terminated polydimethylsiloxane and long-chain alkylsilane in a mass ratio of (1.5–4):1.

[0035] This invention incorporates star-shaped styrene-butadiene block copolymer masterbatch, compatibilizer, polar masterbatch, and anti-exudation agent into the matrix. These components work synergistically in the encapsulating film, resulting in excellent anti-slip properties and low additive migration. When the encapsulating film of this invention is laminated with an EVA film, additive migration from the POE film to the EVA film is significantly reduced during testing. This demonstrates that the POE film exhibits excellent storage stability, anti-slip properties, and anti-additive exudation properties, making it widely applicable in the TOPCon photovoltaic module field.

[0036] In the encapsulation film of the present invention, the styrene-butadiene block copolymer used is a high molecular weight thermoplastic elastomer with a star structure. The star structure is formed by using a coupling agent to "grab" the four polymerized molecular chains, turning the linear unit into a star structure. This allows the four molecular tentacles to entangle with the POE molecular chains, adsorb and fix the additives, prevent the additives from migrating, and improve the cross-linking degree of the film. On the other hand, the high molecular chain tentacles can increase the adsorption capacity of the film to the battery cell and glass on the film surface, thereby improving the anti-slip performance of the film.

[0037] This invention introduces a specific anti-exudation agent with a polar molecular cage structure in which molecular chains interweave. A portion of the polar small-molecule liquid additive is adsorbed onto the cage surface, while another portion is bound inside the cage structure, forming a cage effect to prevent additive migration. Furthermore, the alkylsilane coupling agent and the long-chain terminal hydroxyl polybutadiene molecular chains in the first anti-exudation agent have good compatibility with the non-polar POE molecular chains, allowing for better containment of the additive within the POE resin. The terminal hydroxyl polydimethylsiloxane molecular chains in the second anti-exudation agent have hydroxyl groups at both ends. Under the same addition amount, the lower the molecular weight, the higher the molar amount of the hydroxyl groups, resulting in higher polarity and the ability to adsorb more polar additives. On the other hand, the hydroxyl groups in the molecular chain segments can form strong hydrogen bonds with the first anti-exudation agent, indirectly locking them inside the POE resin. Moreover, the polar cage structure on the surface of the film can adsorb the battery cells and glass through van der Waals forces, providing an anti-slip effect.

[0038] In different implementation methods, the amounts of each component in the encapsulating film, by weight, can be as follows:

[0039] The amount of ethylene-octene polymer can be 60 parts, 62 parts, 65 parts, 68 parts, 70 parts, 72 parts, 75 parts, 78 parts, 80 parts, or any combination thereof.

[0040] The amount of star-shaped styrene-butadiene block copolymer masterbatch can be 5 parts, 8 parts, 10 parts, 12 parts, 15 parts, 18 parts, 20 parts, or any combination thereof.

[0041] The amount of compatibilizer can be 1 part, 2 parts, 5 parts, 8 parts, 10 parts, or any combination thereof;

[0042] The amount of polar masterbatch can be 5 parts, 8 parts, 10 parts, 12 parts, 15 parts, 18 parts, 20 parts, or any combination thereof.

[0043] The amount of crosslinking agent can be 0.1 parts, 0.2 parts, 0.5 parts, 0.8 parts, 1 part, or any combination thereof;

[0044] The amount of the crosslinking agent can be 0.1 parts, 0.2 parts, 0.5 parts, 0.8 parts, 1 part, or any combination thereof;

[0045] The amount of the first anti-precipitation agent can be 0.1 parts, 0.2 parts, 0.5 parts, 0.8 parts, 1 part, or any combination thereof;

[0046] The amount of the second anti-precipitation agent can be 0.1 parts, 0.2 parts, 0.5 parts, 0.8 parts, 1 part, or any combination thereof;

[0047] The amount of antioxidant can be 0.05 parts, 0.08 parts, 0.1 parts, 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, or any combination thereof.

[0048] In different embodiments, the mass ratio of hydroxyl-terminated polybutadiene to long-chain alkylsilane in the first anti-precipitation agent can be 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, or any combination thereof; the mass ratio of hydroxyl-terminated polydimethylsiloxane to long-chain alkylsilane in the second anti-precipitation agent can be 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, or any combination thereof.

[0049] In a specific embodiment of the present invention, the hydroxyl value of the hydroxyl-terminated polybutadiene is 0.47 to 0.80 mmol / g.

[0050] In different embodiments, the hydroxyl value of the hydroxyl-terminated polybutadiene can be a range of 0.47 mmol / g, 0.5 mmol / g, 0.6 mmol / g, 0.7 mmol / g, 0.80 mmol / g, or any combination thereof.

[0051] In a specific embodiment of the present invention, the molecular weight of the hydroxyl-terminated polydimethylsiloxane is 1000-4000 g / mol.

[0052] In different embodiments, the molecular weight of the hydroxyl-terminated polydimethylsiloxane can be a range of 1000 g / mol, 2000 g / mol, 3000 g / mol, 4000 g / mol, or any combination thereof.

[0053] In specific embodiments of the present invention, the long-chain alkylsilane includes at least one of vinyltris(β-methoxyethoxy)silane, 3-methacryloyloxypropyltrimethoxysilane, octyltrimethoxysilane, n-decyltrimethoxysilane, dodecyltrimethoxysilane, and hexadecyltrimethoxysilane.

[0054] In a specific embodiment of the present invention, the preparation of the first anti-precipitation agent includes: mixing terminal hydroxyl polybutadiene and long-chain alkylsilane at 50–70°C in a specified ratio. Further, the mixing time is 10–20 minutes.

[0055] In different embodiments, the mixing temperature in the preparation of the first anti-precipitation agent can be 50°C, 55°C, 60°C, 65°C, 70°C or any combination thereof; the mixing time can be 10 min, 12 min, 15 min, 18 min, 20 min or any combination thereof.

[0056] In a specific embodiment of the present invention, the preparation of the second anti-precipitation agent includes: mixing terminal hydroxyl polydimethylsiloxane and long-chain alkylsilane at 50–70°C in a certain proportion. Further, the mixing time is 10–20 min.

[0057] In different embodiments, the mixing temperature in the preparation of the second anti-precipitation agent can be 50°C, 55°C, 60°C, 65°C, 70°C or any combination thereof; the mixing time can be 10 min, 12 min, 15 min, 18 min, 20 min or any combination thereof.

[0058] In the preparation of the first or second anti-precipitation agent, after the hydroxyl-terminated polybutadiene or hydroxyl-terminated polydimethylsiloxane and long-chain alkylsilane are mixed and reacted, physical entanglement and hydrogen bonding occur, forming a polar molecular cage structure in which the molecular chains interweave. This structure can adsorb the additives on the surface and bind and fix the additives inside, thus preventing the additives from migrating.

[0059] Furthermore, the alkylsilane coupling agent and long-chain polybutadiene molecular chain in the first anti-precipitation agent have good compatibility with the non-polar POE molecular chain, which can better retain the additives inside the POE resin. The hydroxyl-terminated polydimethylsiloxane molecular chain in the second anti-precipitation agent has hydroxyl groups at both ends. Under the same addition amount, the lower the molecular weight, the higher the molar amount of hydroxyl groups, the higher the polarity, and the more polar additives can be adsorbed. In addition, the hydroxyl groups in the hydroxyl-terminated polydimethylsiloxane segments can form strong hydrogen bonds with the second anti-precipitation agent, indirectly locking them inside the POE resin and reducing additive migration.

[0060] In a specific embodiment of the present invention, the star-shaped styrene-butadiene block copolymer masterbatch comprises ethylene-octene polymer and star-shaped styrene-butadiene block copolymer in a mass ratio of (3-5):1.

[0061] In different embodiments, the mass ratio of ethylene-octene polymer to star-shaped styrene-butadiene block copolymer in the star-shaped styrene-butadiene block copolymer masterbatch can be 3:1, 3.5:1, 4:1, 4.5:1, 5:1, or any combination thereof.

[0062] In a specific embodiment of the present invention, the mass ratio of styrene to butadiene in the star-shaped styrene-butadiene block copolymer is (2-6):(8-4).

[0063] In different embodiments, the mass ratio of styrene to butadiene in the star-shaped styrene-butadiene block copolymer can be 2:8, 3.3:6.7, 4:6, 5:5, 6:4, or any combination thereof.

[0064] In practice, the star-shaped styrene-butadiene block copolymer masterbatch is prepared by mixing ethylene-octene polymer and star-shaped styrene-butadiene block copolymer in a certain proportion, followed by melt extrusion granulation using a twin-screw extruder. The melt extrusion granulation temperature can be 70–120°C. For example, in different embodiments, the melt extrusion granulation temperature can be 70°C, 75°C, 80°C, 100°C, 120°C, etc.

[0065] In a specific embodiment of the present invention, the polar masterbatch is a silane coupling agent modified POE masterbatch. Further, the silane coupling agent includes at least one of 3-methacryloxypropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, and vinyltris(β-methoxyethoxy)silane, preferably at least one of 3-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, and vinyltris(β-methoxyethoxy)silane.

[0066] In a specific embodiment of the present invention, the polar masterbatch is mainly prepared from POE resin, silane coupling agent and initiator. Further, the polar masterbatch is mainly prepared from 100 parts of POE resin, 1 to 5 parts of silane coupling agent and 0.01 to 0.1 parts of initiator by weight.

[0067] In practice, the polar masterbatch is prepared by mixing ethylene-octene polymer, initiator, and silane coupling agent in proportion, followed by melt extrusion granulation using a twin-screw extruder. The melt extrusion granulation temperature can be between 70 and 190°C. For example, in different embodiments, the melt extrusion granulation temperature can be 70°C, 100°C, 120°C, 150°C, 180°C, 190°C, etc.

[0068] The polar masterbatch of this invention grafts a polar silane coupling agent onto a non-polar POE molecular chain under high temperature conditions using a silane coupling agent and an initiator. This increases the polarity of the POE resin, improves the adsorption effect and compatibility of additives, and reduces the migration of polar additives. The initiator may include, but is not limited to, dicumyl peroxide.

[0069] Furthermore, the introduction of polar masterbatch in this invention reduces the amount of liquid polar additives required, avoiding incomplete absorption or uneven distribution of additives due to the direct addition of silane coupling agents; on the other hand, polar masterbatch can better adsorb additional polar additives, preventing additive migration; and the polar POE molecular chains increase the van der Waals forces between the film and the glass and the battery cell, preventing slippage between the glass and the battery cell.

[0070] In a specific embodiment of the present invention, the compatibilizer includes at least one of maleic anhydride-grafted ethylene-octene copolymer, maleic anhydride-grafted ethylene-butene copolymer, and maleic anhydride-grafted SEBS copolymer, preferably maleic anhydride-grafted SEBS copolymer.

[0071] Using the above compatibilizer can further improve the compatibility between star-shaped styrene-butadiene block copolymer masterbatch and polar masterbatch, and avoid unevenness and phase separation in the film.

[0072] In a specific embodiment of the present invention, the crosslinking agent includes at least one of tert-butyl peroxycarbonate-2-ethylhexyl ester, dicumyl peroxide, tert-amyl peroxycarbonate-2-ethylhexyl ester, and tert-butyl peroxycarbonate-2-ethylhexyl ester; the co-crosslinking agent includes at least one of triallyl isocyanurate, triallyl cyanurate, and trimethylolpropane trimethacrylate.

[0073] Another aspect of the present invention provides a method for preparing an encapsulating film, comprising the following steps:

[0074] (a) After uniformly mixing polar masterbatch, crosslinking agent, co-crosslinking agent, first anti-precipitation agent, second anti-precipitation agent and antioxidant, the mixture is melt-granulated to obtain mixed masterbatch;

[0075] (b) The mixed masterbatch is mixed evenly with ethylene-octene polymer, star-shaped styrene-butadiene block copolymer masterbatch and compatibilizer, then melt-extruded, drawn and cooled to form a film, and then subjected to irradiation pre-crosslinking treatment.

[0076] In a specific embodiment of the present invention, in step (b), the temperature of melt extrusion is 70–95°C.

[0077] In different embodiments, in step (b), the temperature of melt extrusion can be a range of 70°C, 80°C, 90°C, 95°C, or any combination thereof.

[0078] In a specific embodiment of the present invention, in step (a), the temperature of melt granulation is 70–120°C.

[0079] In different embodiments, in step (a), the temperature for melt granulation can be 70°C, 80°C, 90°C, 100°C, 120°C, or any combination thereof.

[0080] The present invention also provides a photovoltaic module comprising any of the above-mentioned encapsulating films.

[0081] Information regarding some of the materials used in the following embodiments is as follows:

[0082] Ethylene-octene polymer: Dow Chemical Company, XUS 38688;

[0083] Star-shaped styrene-butadiene block copolymer: Baling Petrochemical, YH-806;

[0084] Linear styrene-butadiene block copolymer: Baling Petrochemical, YH-788;

[0085] Maleic anhydride-grafted SEBS copolymer: Kraton Corporation, FG1901;

[0086] Crosslinking agent: tert-butyl percarbonate-2-ethylhexyl ester;

[0087] Co-crosslinking agent: triallyl isocyanurate;

[0088] Hydroxyl-terminated polybutadiene: Hongyuan New Materials, HTPB, Type I (hydroxyl value 0.47~0.53mmol / g);

[0089] Hydroxyl-terminated polybutadiene: Hongyuan New Materials, HTPB, Type II (hydroxyl value 0.54~0.64mmol / g);

[0090] Hydroxyl-terminated polybutadiene: Hongyuan New Materials, HTPB, Type IV (hydroxyl value 0.71~0.80mmol / g);

[0091] Hydroxyl-terminated polydimethylsiloxane: Anhui Aiyota Silicon Oil Co., Ltd., IOTA 2110 (molecular weight 1000g / mol), IOTA 2120 (molecular weight 2000g / mol), IOTA 2140 (molecular weight 4000g / mol), etc.;

[0092] Long-chain alkylsilanes: Shandong Silicon Science New Materials Co., Ltd., hexadecyltrimethoxysilane SICO-N1613;

[0093] Antioxidant: Pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate].

[0094] Example 1

[0095] This embodiment provides an encapsulating film comprising the following components in parts by weight:

[0096] The composition includes 65 parts of ethylene-octene polymer, 10 parts of star-shaped styrene-butadiene block copolymer masterbatch, 5 parts of maleic anhydride-grafted SEBS copolymer, 20 parts of 3-methacryloyloxypropyltrimethoxysilane-grafted POE polar masterbatch, 0.9 parts of tert-butylperoxycarbonate-2-ethylhexyl ester, 0.6 parts of triallyl isocyanurate, 0.3 parts of primary anti-precipitation agent, 0.2 parts of secondary anti-precipitation agent, and 0.1 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate].

[0097] The preparation of the star-shaped styrene-butadiene block copolymer masterbatch includes: weighing ethylene-octene polymer and star-shaped styrene-butadiene block copolymer at a mass ratio of 4:1, mixing them evenly, and then granulating them by twin-screw melt extrusion. The melt extrusion temperatures are: Zone I 75-85℃, Zone II 85-95℃, Zone III 100-120℃, Zone IV 100-120℃, Zone V 100-120℃, Zone VI 100-120℃, and die head 110℃.

[0098] The preparation of 3-methacryloxypropyltrimethoxysilane-grafted POE polar masterbatch includes: selecting 100 parts by weight of ethylene-octene polymer, 0.05 parts by weight of dicumyl peroxide and 3-methacryloxypropyltrimethoxysilane, mixing them evenly, and then granulating them by twin-screw melt extrusion at the following temperatures: Zone I 75-85℃, Zone II 85-95℃, Zone III 100-120℃, Zone IV 170-180℃, Zone V 170-180℃, Zone VI 170-180℃, and die head 150℃.

[0099] The preparation of the first anti-precipitation agent includes: weighing hydroxyl-terminated polybutadiene (type II) and hexadecyltrimethoxysilane in a mass ratio of 1.5:1, mixing them at 60°C for 20 min to obtain the first anti-precipitation agent.

[0100] The preparation of the second anti-precipitation agent includes: weighing hydroxyl-terminated polydimethylsiloxane (molecular weight 4000 g / mol) and hexadecyltrimethoxysilane in a mass ratio of 1.5:1, mixing them at 60°C for 20 min to obtain the second anti-precipitation agent.

[0101] The method for preparing the encapsulating film in this embodiment includes the following steps:

[0102] (1) 3-methacryloxypropyltrimethoxysilane-grafted POE polar masterbatch, tert-butylperoxycarbonate-2-ethylhexyl ester, triallyl isocyanurate, first anti-precipitation agent, second anti-precipitation agent and pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] are mixed evenly and then melt-granulated to obtain mixed masterbatch; wherein, the melt granulation temperature is: Zone I 75-85℃, Zone II 85-95℃, Zone III 100-120℃, Zone IV 100-120℃, Zone V 100-120℃, Zone VI 100-120℃, and die head 110℃.

[0103] (2) The mixed masterbatch is mixed evenly with ethylene-octene polymer, star-shaped styrene-butadiene block copolymer masterbatch and maleic anhydride-grafted SEBS copolymer and then melt-extruded. The film is formed by traction with embossing roller and cooling with cooling roller. Finally, it is slit and wound to obtain the encapsulating film. The melting is carried out in a single screw extruder of a casting machine. The melt extrusion temperature is 55-65℃ in zone I, 65-75℃ in zone II, 70-80℃ in zone III, 75-85℃ in zone IV, 80-90℃ in zone V, 90-95℃ in zone VI, and 95℃ at the die head.

[0104] Example 2

[0105] This embodiment refers to the encapsulating film and its preparation method in Embodiment 1, the only difference being that the amount of each component used in preparing the encapsulating film is different.

[0106] The encapsulating film of this embodiment includes the following components in parts by weight:

[0107] 70 parts of ethylene-octene polymer, 7 parts of star-shaped styrene-butadiene block copolymer masterbatch, 3 parts of maleic anhydride-grafted SEBS copolymer, 20 parts of 3-methacryloyloxypropyltrimethoxysilane-grafted POE polar masterbatch, 0.9 parts of tert-butylperoxycarbonate-2-ethylhexyl ester, 0.6 parts of triallyl isocyanurate, 0.3 parts of primary anti-precipitation agent, 0.2 parts of secondary anti-precipitation agent, and 0.1 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate].

[0108] Example 3

[0109] This embodiment refers to the encapsulating film and its preparation method in Embodiment 1, the only difference being that the amount of each component used in preparing the encapsulating film is different.

[0110] The encapsulating film of this embodiment includes the following components in parts by weight:

[0111] 75 parts of ethylene-octene polymer, 5 parts of star-shaped styrene-butadiene block copolymer masterbatch, 5 parts of maleic anhydride-grafted SEBS copolymer, 15 parts of 3-methacryloyloxypropyltrimethoxysilane-grafted POE polar masterbatch, 0.9 parts of tert-butylperoxycarbonate-2-ethylhexyl ester, 0.6 parts of triallyl isocyanurate, 0.3 parts of primary anti-precipitation agent, 0.2 parts of secondary anti-precipitation agent, and 0.1 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate].

[0112] Example 4

[0113] This embodiment refers to the encapsulating film and its preparation method in Embodiment 1, the only difference being that the amount of each component used in preparing the encapsulating film is different.

[0114] The encapsulating film of this embodiment includes the following components in parts by weight:

[0115] The composition includes 75 parts of ethylene-octene polymer, 7 parts of star-shaped styrene-butadiene block copolymer masterbatch, 3 parts of maleic anhydride-grafted SEBS copolymer, 15 parts of 3-methacryloyloxypropyltrimethoxysilane-grafted POE polar masterbatch, 0.9 parts of tert-butylperoxycarbonate-2-ethylhexyl ester, 0.6 parts of triallyl isocyanurate, 0.3 parts of primary anti-precipitation agent, 0.2 parts of secondary anti-precipitation agent, and 0.1 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate].

[0116] Example 5

[0117] This embodiment refers to the encapsulating film and its preparation method in Embodiment 1, the only difference being that the amount of each component used in preparing the encapsulating film is different.

[0118] The encapsulating film of this embodiment includes the following components in parts by weight:

[0119] The composition includes 80 parts of ethylene-octene polymer, 5 parts of star-shaped styrene-butadiene block copolymer masterbatch, 2 parts of maleic anhydride-grafted SEBS copolymer, 13 parts of 3-methacryloyloxypropyltrimethoxysilane-grafted POE polar masterbatch, 0.9 parts of tert-butylperoxycarbonate-2-ethylhexyl ester, 0.6 parts of triallyl isocyanurate, 0.3 parts of primary anti-precipitation agent, 0.2 parts of secondary anti-precipitation agent, and 0.1 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate].

[0120] Example 6

[0121] This embodiment refers to the encapsulating film and its preparation method in Embodiment 1, the only difference being that the amount of each component used in preparing the encapsulating film is different.

[0122] The encapsulating film of this embodiment includes the following components in parts by weight:

[0123] The composition includes 80 parts of ethylene-octene polymer, 7 parts of star-shaped styrene-butadiene block copolymer masterbatch, 3 parts of maleic anhydride-grafted SEBS copolymer, 10 parts of 3-methacryloyloxypropyltrimethoxysilane-grafted POE polar masterbatch, 0.9 parts of tert-butylperoxycarbonate-2-ethylhexyl ester, 0.6 parts of triallyl isocyanurate, 0.3 parts of primary anti-precipitation agent, 0.2 parts of secondary anti-precipitation agent, and 0.1 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate].

[0124] Example 7

[0125] This embodiment refers to the encapsulating film and its preparation method in Embodiment 2, with the only difference being the preparation of the first anti-exudate agent.

[0126] The preparation of the first anti-precipitation agent in this embodiment includes: weighing hydroxyl-terminated polybutadiene (type IV) and hexadecyltrimethoxysilane in a mass ratio of 1.5:1, mixing them at 60°C for 20 min to obtain the first anti-precipitation agent.

[0127] Example 8

[0128] This embodiment refers to the encapsulating film and its preparation method in Embodiment 2, with the only difference being the preparation of the first anti-exudate agent.

[0129] The preparation of the first anti-precipitation agent in this embodiment includes: weighing hydroxyl-terminated polybutadiene (type I) and hexadecyltrimethoxysilane in a mass ratio of 1.5:1, mixing them at 60°C for 20 min to obtain the first anti-precipitation agent.

[0130] Example 9

[0131] This embodiment refers to the encapsulating film and its preparation method in Example 2, the only difference being that the preparation of the second anti-exudate agent is different.

[0132] The preparation of the second anti-precipitation agent in this embodiment includes: weighing hydroxyl-terminated polydimethylsiloxane (molecular weight 2000 g / mol) and hexadecyltrimethoxysilane in a mass ratio of 1.5:1, mixing them at 60°C for 20 min to obtain the second anti-precipitation agent.

[0133] Example 10

[0134] This embodiment refers to the encapsulating film and its preparation method in Example 2, the only difference being that the preparation of the second anti-exudate agent is different.

[0135] The preparation of the second anti-precipitation agent in this embodiment includes: weighing hydroxyl-terminated polydimethylsiloxane (molecular weight 1000 g / mol) and hexadecyltrimethoxysilane in a mass ratio of 1.5:1, mixing them at 60°C for 20 min to obtain the second anti-precipitation agent.

[0136] Example 11

[0137] This embodiment refers to the encapsulating film and its preparation method in Embodiment 2, with the only difference being the preparation of the first anti-exudate agent.

[0138] The preparation of the first anti-precipitation agent in this embodiment includes: weighing hydroxyl-terminated polybutadiene (type II) and hexadecyltrimethoxysilane in a mass ratio of 3:1, mixing them at 60°C for 20 min to obtain the first anti-precipitation agent.

[0139] Example 12

[0140] This embodiment refers to the encapsulating film and its preparation method in Example 2, the only difference being that the preparation of the second anti-exudate agent is different.

[0141] The preparation of the second anti-precipitation agent in this embodiment includes: weighing hydroxyl-terminated polydimethylsiloxane (molecular weight 4000 g / mol) and hexadecyltrimethoxysilane in a mass ratio of 3:1, mixing them at 60°C for 20 min to obtain the second anti-precipitation agent.

[0142] Comparative Example 1

[0143] Comparative Example 1 uses the same encapsulating film preparation method as Example 1, except that the raw material composition of the encapsulating film is different.

[0144] The encapsulating film of Comparative Example 1 comprises the following components by weight: 100 parts of ethylene-octene polymer, 0.9 parts of tert-butyl peroxycarbonate-2-ethylhexyl ester, 0.6 parts of triallyl isocyanurate, 0.5 parts of 3-methacryloyloxypropyltrimethoxysilane, and 0.1 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate].

[0145] The preparation method of the encapsulating film in Comparative Example 1 includes: mixing the components evenly in proportion, then melting and extruding the mixture, using an embossing roller to pull the film and a cooling roller to cool it into a film, and finally slitting and winding it to obtain the encapsulating film. The temperature of the melt extrusion is the same as in step (2) of Example 1.

[0146] Comparative Example 2

[0147] Comparative Example 2 uses the same encapsulating film preparation method as Example 6, except that the raw material composition of the encapsulating film is different.

[0148] The raw materials of the encapsulating film in Comparative Example 2 do not include a second anti-exudant.

[0149] Comparative Example 3

[0150] Comparative Example 3 uses the same encapsulating film preparation method as Example 6, except that the raw material composition of the encapsulating film is different.

[0151] The raw materials of the encapsulating film in Comparative Example 3 do not include the first anti-exudant.

[0152] Comparative Example 4

[0153] Comparative Example 4 uses the same encapsulating film preparation method as Example 1, except that the raw material composition of the encapsulating film is different.

[0154] The encapsulating film of Comparative Example 4 comprises the following components by weight: 65 parts of ethylene-octene polymer, 10 parts of star-shaped styrene-butadiene block copolymer masterbatch, 5 parts of maleic anhydride-grafted SEBS copolymer, 20 parts of 3-methacryloyloxypropyltrimethoxysilane-grafted POE polar masterbatch, 0.9 parts of tert-butylperoxycarbonate-2-ethylhexyl ester, 0.6 parts of triallyl isocyanurate, and 0.1 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate].

[0155] Comparative Example 5

[0156] Comparative Example 5 uses the same encapsulating film preparation method as Example 2, except that the preparation of the first anti-exudant is different.

[0157] The preparation of the first anti-exudate agent in Comparative Example 5 included: weighing hydroxyl-terminated polybutadiene (type II) and hexadecyltrimethoxysilane in a mass ratio of 5:1, mixing them at 60°C for 20 minutes to obtain the first anti-exudate agent. The raw material composition of the encapsulating film is different.

[0158] Comparative Example 6

[0159] Comparative Example 6 uses the same encapsulating film preparation method as Example 2, except that the preparation of the second anti-exudate agent is different.

[0160] The preparation of the second anti-precipitation agent in Comparative Example 6 included: weighing hydroxyl-terminated polydimethylsiloxane (molecular weight 4000 g / mol) and hexadecyltrimethoxysilane in a mass ratio of 5:1, mixing them at 60°C for 20 min to obtain the second anti-precipitation agent.

[0161] Comparative Example 7

[0162] Comparative Example 7 uses the same encapsulating film preparation method as Example 2, except that: an equal weight of linear styrene-butadiene block copolymer masterbatch is used to replace the star-shaped styrene-butadiene block copolymer masterbatch in Example 2.

[0163] The preparation of linear styrene-butadiene block copolymer masterbatch includes: weighing ethylene-octene polymer and linear styrene-butadiene block copolymer at a mass ratio of 4:1, mixing them evenly, and then granulating them by twin-screw melt extrusion. The melt extrusion conditions are the same as those for the preparation of star-shaped styrene-butadiene block copolymer masterbatch.

[0164] Experimental Example

[0165] To compare and illustrate the performance of different encapsulating films, the following performance tests were conducted, and the test methods for each test item are as follows:

[0166] Peel strength:

[0167] Sample preparation: Take the encapsulation film samples prepared in the examples and comparative examples, and place them in the vacuum laminator in the order of "tempered glass / encapsulation film of the present invention / backplate" and laminate at 145°C for 10 minutes.

[0168] Test method: A CMT2203 universal electronic tensile tester was used, and the test procedure specified in GB / T 2790-1995 was followed. The tensile speed was 100 mm / min. The arithmetic mean of three samples was taken to obtain the peel strength between the encapsulation film sample and the glass.

[0169] HAST Aging Test: Take the encapsulating film samples from the examples and comparative examples, and place the "test laminate for peel strength with glass" into the PCT aging test chamber according to the test method of GB / T 29848-2018. Set the test conditions as follows: temperature 121℃, relative humidity 99%~100%, test for 48h. After aging, restore in an open environment at 23℃±5℃ and relative humidity<70% for 2~4h, and then conduct peel strength tests with glass.

[0170] Film-glass slip test: Take an encapsulation film with an area of ​​10cm×10cm and a film weight between 4.3 and 4.5g, prepared according to different examples and comparative examples, place it on patterned glass with an inclination angle of 30°, with the patterned side of the glass facing the film, and record the slip distance of the film in 1 minute.

[0171] Film-cell slippage test: Take a commercially available TOPCon cell and place it on a film with a 30° tilt angle (supported by glass on the back), with the front of the cell facing the film. Record the slippage distance of the cell in 1 minute.

[0172] Exudation test: Different POE encapsulation films and conventional EVA films, each with an area of ​​10cm × 10cm and a mass between 4.3 and 4.5g, were stacked to form an EP structure. Every 24 hours, a set of films was taken out and weighed using an electronic analytical balance. The weight change of the films was recorded, and the additive migration rate was calculated. Among them, the POE encapsulation film additive exudation rate = additive exudation mass / (POE encapsulation film mass × additive addition ratio); additive exudation mass = initial POE film mass - mass of the POE film at the time of removal.

[0173] The results of the peel strength test and slip test are shown in Table 1:

[0174] Table 1 Test results of different encapsulating films

[0175]

[0176]

[0177] The precipitation test results are shown in Table 2:

[0178] Table 2 Results of precipitation of different encapsulating films

[0179]

[0180] Comparing Examples 1 and 5, it is evident that adding excessive amounts of non-POE matrix masterbatch leads to phase separation during the curing process of the adhesive film, resulting in a decrease in the peel strength of the film, especially the aging peel strength. Comparing Examples 2 and 3-6, it is evident that adding more POE polar masterbatch can enhance the adhesion between the adhesive film and the battery cell and glass, reducing slippage. Comparing Examples 2 and 7-10, it is evident that adding high-hydroxyl-value terminal hydroxyl polybutadiene or low-molecular-weight terminal hydroxyl polydimethylsiloxane can significantly improve the anti-slip performance of the adhesive film and reduce the risk of additive precipitation. Comparing Examples 2 and 11-12, it is evident that when the amount of long-chain alkylsilane in the first or second anti-precipitation agent is reduced, the precipitation rate of additives in the adhesive film significantly increases. Comparing Example 2 and Comparative Examples 6-8, it can be seen that when the ratio of long-chain alkylsilane to hydroxyl-terminated polybutadiene or hydroxyl-terminated polydimethylsiloxane in the first and second anti-exudants exceeds the specified range, the film can maintain good peel strength, but its performance in preventing additive exudation and anti-slip properties is poor. Furthermore, the overall performance of the film is significantly reduced when the masterbatch is prepared using linear styrene-butadiene block copolymer.

[0181] Comparing Examples 1-12 and Comparative Example 1, it is evident that the addition of star-shaped styrene-butadiene block copolymer masterbatch, maleic anhydride-grafted SEBS copolymer, first anti-exudation agent, and second anti-exudation agent, with the synergistic effect of various components, significantly improves the adhesive properties, anti-slip properties, and anti-additive exudation properties of the film. Comparing Examples 1 and Comparative Example 4, it is evident that while adding a large amount of star-shaped styrene-butadiene block copolymer masterbatch and polar masterbatch to the film can improve slippage and additive exudation, the lack of an appropriate amount of compatibilizer reduces the compatibility between the star-shaped styrene-butadiene block copolymer masterbatch and the POE matrix, leading to phase separation during vulcanization and a significant decrease in the peel strength and aging peel strength of the film. Comparing Examples 6 and Comparative Examples 2 and 3, it is evident that adding only a single anti-exudation agent, or not adding any anti-exudation agent at all, does not significantly improve the improvement of additive exudation in the film.

[0182] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An encapsulating film, characterized in that, It is mainly prepared from the following components in parts by weight: The mixture contains 60-80 parts of ethylene-octene polymer, 5-20 parts of star-shaped styrene-butadiene block copolymer masterbatch, 1-10 parts of compatibilizer, 5-20 parts of polar masterbatch, 0.1-1.0 parts of crosslinking agent, 0.1-1 parts of co-crosslinking agent, 0.1-1 parts of first anti-exudation agent, 0.1-1 parts of second anti-exudation agent, and 0.05-0.5 parts of antioxidant. The first anti-precipitation agent comprises hydroxyl-terminated polybutadiene and long-chain alkylsilane in a mass ratio of (1.5–4):1; the second anti-precipitation agent comprises hydroxyl-terminated polydimethylsiloxane and long-chain alkylsilane in a mass ratio of (1.5–4):

1.

2. The encapsulating film according to claim 1, characterized in that, The hydroxyl-terminated polybutadiene has a hydroxyl value of 0.47–0.80 mmol / g; And / or, the molecular weight of the hydroxyl-terminated polydimethylsiloxane is 1000 to 4000.

3. The encapsulating film according to claim 1, characterized in that, The long-chain alkylsilanes include at least one of octyltrimethoxysilane, n-decyltrimethoxysilane, dodecyltrimethoxysilane, and hexadecyltrimethoxysilane.

4. The encapsulating film according to claim 3, characterized in that, The preparation of the first anti-precipitation agent includes: mixing the terminal hydroxyl polybutadiene and the long-chain alkylsilane at 50-70°C in proportion.

5. The encapsulating film according to claim 3, characterized in that, The preparation of the second anti-precipitation agent includes: mixing the terminal hydroxyl polydimethylsiloxane and the long-chain alkylsilane at 50-70°C in proportion.

6. The encapsulating film according to claim 1, characterized in that, The star-shaped styrene-butadiene block copolymer masterbatch comprises ethylene-octene polymer and star-shaped styrene-butadiene block copolymer in a mass ratio of (3-5):

1.

7. The encapsulating film according to claim 6, characterized in that, In the star-shaped styrene-butadiene block copolymer, the mass ratio of styrene to butadiene is (2-6):(8-4).

8. The encapsulating film according to claim 1, characterized in that, The polar masterbatch is a silane coupling agent modified POE masterbatch.

9. The encapsulating film according to claim 8, characterized in that, The silane coupling agent includes at least one of 3-methacryloxypropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, and vinyltri(β-methoxyethoxy)silane.

10. The encapsulating film according to claim 1, characterized in that, The polar masterbatch is mainly made of POE resin, silane coupling agent and initiator.

11. The encapsulating film according to claim 10, characterized in that, The polar masterbatch is mainly prepared by weight of 100 parts of POE resin, 1-5 parts of silane coupling agent and 0.01-0.1 parts of initiator.

12. The encapsulating film according to claim 1, characterized in that, The compatibilizer includes at least one of maleic anhydride-grafted ethylene-octene copolymer, maleic anhydride-grafted ethylene-butene copolymer, and maleic anhydride-grafted SEBS copolymer. And / or, the crosslinking agent includes at least one of tert-butyl peroxycarbonate-2-ethylhexyl, dicumyl peroxide and tert-amyl peroxycarbonate; the co-crosslinking agent includes at least one of triallyl isocyanurate, triallyl cyanurate and trimethylolpropane trimethacrylate.

13. The method for preparing the encapsulating film according to any one of claims 1 to 12, characterized in that, Includes the following steps: (a) The polar masterbatch, crosslinking agent, co-crosslinking agent, first anti-precipitation agent, second anti-precipitation agent and antioxidant are mixed evenly and then melt-granulated to obtain mixed masterbatch; (b) The mixed masterbatch is mixed evenly with ethylene-octene polymer, star-shaped styrene-butadiene block copolymer masterbatch and compatibilizer, then melt-extruded, drawn and cooled to form a film, and then subjected to irradiation pre-crosslinking treatment.

14. The method for preparing the encapsulating film according to claim 13, characterized in that, In step (b), the temperature of the melt extrusion is 70–95°C.

15. The method for preparing the encapsulating film according to claim 14, characterized in that, In step (a), the temperature of the melt granulation is 70–120°C.

16. A photovoltaic module, characterized in that, This includes the encapsulating film according to any one of claims 1 to 12 or the encapsulating film prepared by the preparation method according to any one of claims 13 to 15.

Images