Encapsulation adhesive film and preparation method thereof, laminated member and recycling process thereof, photovoltaic module

Abstract

This invention relates to the field of solar cell technology, specifically to an encapsulating film and its preparation method, a laminate and its recycling process, and a photovoltaic module. The encapsulating film comprises, by weight, the following raw materials: 100 parts matrix resin, 2-6 parts dynamic crosslinking site donors, 1-2 parts dynamic crosslinking agent, 0.3-0.6 parts catalyst, 0.05-1 part covalent crosslinking agent, and 0.05-2 parts co-crosslinking agent. Using the above raw materials, an encapsulating film with a dual-network structure based on the coexistence of covalent and dynamic crosslinking can be prepared. The resulting encapsulating film can maintain high stability in bonding with glass during the service life of the photovoltaic module, and can also achieve dynamic bond breaking and recombination and network topology rearrangement through transesterification during the recycling of the photovoltaic module. This provides stress relaxation channels and controllable debonding capability for the encapsulating film, enabling gentle and rapid delamination between the encapsulating film and glass, and achieving low-loss recycling of both the glass and the encapsulating film.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, specifically to an encapsulating film and its preparation method, a laminate and its recycling process, and a photovoltaic module. Background Technology

[0002] With the large-scale development of renewable energy, photovoltaic (PV) power generation, as a core component, has been widely promoted and applied. In recent years, global PV installed capacity has continued to expand, especially with the support of national policies, leading to the sustained growth of the PV industry. PV modules typically have a lifespan of 20-30 years. As early-stage modules gradually reach the end of their service life, a large-scale decommissioning of PV modules is predicted in the coming years. Against this backdrop, how to efficiently and environmentally recycle the valuable materials within these modules has become a critical issue that urgently needs to be addressed.

[0003] Currently, most photovoltaic modules commonly use EVA / POE encapsulant film as the encapsulation material, which not only provides protection but also ensures the long-term stability of the module. Traditional EVA / POE encapsulant film undergoes cross-linking and curing via peroxides during hot pressing, forming a stable but irreversible three-dimensional network structure. This structure endows the film with excellent physical and chemical properties, but existing EVA / POE encapsulant films make interlayer separation difficult during the recycling process after photovoltaic modules are decommissioned. Existing recycling processes typically rely on high-temperature pyrolysis or strong solvent treatment, which is not only energy-intensive and time-consuming but also prone to damaging the glass and solar cells, and causing secondary pollution. Summary of the Invention

[0004] To address the technical problem of difficulty in separating the layers of the encapsulating film in photovoltaic modules during the recycling process after the photovoltaic modules are decommissioned, this invention provides an encapsulating film and its preparation method, a laminate and its recycling process, and a photovoltaic module.

[0005] This invention is achieved using the following technical solution: an encapsulating film, comprising, by weight, the following raw materials: 100 parts of base resin, 2-6 parts of dynamic crosslinking site donors, 1-2 parts of dynamic crosslinking agent, 0.3-0.6 parts of catalyst, 0.05-1 parts of covalent crosslinking agent, and 0.05-2 parts of co-crosslinking agent; the dynamic crosslinking site donors contain at least one functional group, either carboxyl or anhydride groups; the catalyst is a catalyst containing zinc ions. The covalent crosslinking agent provides free radicals upon heating, and through these free radicals, promotes the formation of irreversible C-C bonds on the base resin; the dynamic crosslinking site donors, initiated by free radicals, attach to the molecular chain of the base resin, and the anhydride groups attached to the molecular chain of the base resin undergo ring-opening and esterification under the action of the dynamic crosslinking agent to form thermally reversible ester bonds. The irreversible C-C bonds and the thermally reversible ester bonds together constitute an encapsulating film with a dual-network structure based on the coexistence of covalent and dynamic crosslinking.

[0006] As a further improvement of the present invention, the dynamic crosslinking site donor includes one or more of maleic anhydride, itaconic anhydride, acrylic acid, methacrylic acid, itaconic acid, fumaric acid, maleic acid, and glycidyl methacrylate. The dynamic crosslinking site donor is used to provide reaction sites capable of dynamic exchange to the matrix resin.

[0007] As a further improvement of the present invention, the dynamic crosslinking agent is a polyol and / or a polyester. The polyol includes one or more of trimethylolpropane, pentaerythritol, glycerol, sorbitol, and polyether polyols. The polyester is a polyfunctional ester compound containing two or more ester groups in its molecule and capable of participating in transesterification reactions under the action of a zinc-containing catalyst; the polyester includes one or more of triethyl citrate, tributyl citrate, triglyceride triacetate, diallyl maleate, diallyl fumarate, polycaprolactone polyol, and polyester polyol.

[0008] As a further improvement of the present invention, the catalyst includes one or more of zinc acetate, zinc oxide, zinc chloride, zinc lactate, and zinc acetylacetonate.

[0009] As a further improvement of the present invention, the covalent crosslinking agent is an organic peroxide crosslinking agent that can provide free radicals.

[0010] As a further improvement of the present invention, the co-crosslinking agent includes one or more of triallyl isocyanurate, triallyl cyanurate, trimethylolpropane, trimethacrylate and diallyl phthalate.

[0011] As a further improvement of the present invention, the matrix resin includes one or both of ethylene vinyl acetate and polyolefin elastomer.

[0012] As a further improvement of the present invention, the encapsulating film also includes additives, including one or more of silane coupling agents, antioxidants, light stabilizers, and ultraviolet light absorbers.

[0013] The present invention also includes a method for preparing the encapsulating film as described above, comprising: weighing each raw material according to the formula amount, and sequentially premixing, melting, extruding into a film, cooling, slitting and winding the weighed raw materials, and then passing them through the heating and laminating process in the photovoltaic module manufacturing process to obtain the encapsulating film.

[0014] As a further improvement of the present invention, the lamination temperature in the heating lamination process is 140℃~160℃, the lamination time is 8-20min, and the vacuum degree is ≤-0.08MPa.

[0015] The present invention also includes a laminate comprising a cover glass, a back glass, and an encapsulating film as described above disposed between the cover glass and the back glass. The encapsulating film is used to bond the cover glass and the back glass respectively, thereby forming a three-layer laminate. The thickness of the encapsulating film is 0.5mm to 0.8mm.

[0016] This invention also provides a recycling process for the laminated component as described above, comprising: cutting or cleaning the excess adhesive area at the edge of the laminated component to expose the edges of the adhesive layer between the encapsulating film and the cover glass, and the edges of the adhesive layer between the encapsulating film and the back glass. The treated laminated component is then immersed in a mixed solvent containing ethanol and NaOH and heated until the cover glass, encapsulating film, and back glass separate, after which heating is stopped. The cover glass, back glass, and encapsulating film are then recycled separately, thus completing the recycling of the laminated component.

[0017] As a further improvement of the present invention, the heating temperature is 60-80℃ and the heating time is 0.5h~6h.

[0018] The present invention also provides a photovoltaic module comprising the encapsulating film as described above.

[0019] The technical solution provided by this invention has the following beneficial effects: (1) The encapsulating film provided in this solution introduces carboxyl / anhydride groups into the molecular chain of the matrix resin. The introduced carboxyl / anhydride groups can provide dynamic crosslinking sites, and polyols are used as dynamic crosslinking agents. This enables the construction of a dynamic ester bond network on the matrix resin. This design is an improvement on the current photovoltaic encapsulating film. This allows the improved encapsulating film to form a dual network structure of "covalent crosslinking and dynamic crosslinking". This allows the encapsulating film to adhere to the glass with high stability during the service of the photovoltaic module. It can also achieve the breaking and recombination of dynamic bonds and the rearrangement of network topology based on ester exchange during the recycling of the photovoltaic module. This provides stress relaxation channels and controllable debonding ability for the encapsulating film, enabling the encapsulating film and glass to be gently and quickly delaminated, and achieving the purpose of low-loss recycling of glass and encapsulating film.

[0020] (2) The encapsulating film provided in this scheme is constructed into a complete dynamic cross-linking system using maleic anhydride, trimethylolpropane, and zinc acetate. Maleic anhydride can be grafted onto the molecular chain of the matrix resin through melt grafting or solution grafting, thereby enabling the molecular chain of the matrix resin to carry dynamic sites that can be used for exchange. Trimethylolpropane is a small molecule structure, which is uniformly dispersed in the system and can quickly bind to the dynamic sites of maleic anhydride, avoiding local aggregation of the constructed dynamic ester bonds, thus achieving a more uniform dynamic cross-linking network. Furthermore, the anhydride group of maleic anhydride has a much higher reactivity than ordinary carboxyl groups. Without the need for high-temperature dehydration, it can quickly undergo ring-opening esterification with the primary hydroxyl group in trimethylolpropane under the mild catalysis of zinc acetate. After ring opening, carboxyl groups will be produced in situ, thereby continuously providing sites for subsequent dynamic exchange and coordination, achieving a continuous supply of dynamic exchange and coordination sites in a single reaction. Furthermore, the dynamic ester bonds formed by the reaction of maleic anhydride and trimethylolpropane undergo reversible transesterification under the catalytic heating conditions of zinc acetate, realizing the dissociation and recombination of the network. At the same time, the zinc ions dissociated from zinc acetate can also form carboxylic acid zinc coordination bonds with the carboxyl groups generated by the ring opening of maleic anhydride and the ester groups in the system. This dual dynamic mechanism based on "dynamic ester bonds" and "dynamic coordination bonds" can improve the dynamic performance of the constructed dynamic crosslinked network, thereby improving its recycling performance. Attached Figure Description

[0021] Figure 1 This is a chemical reaction diagram of a method for preparing an encapsulating film provided in Embodiment 1 of the present invention.

[0022] Figure 2 This is a schematic diagram illustrating the principle of covalent crosslinking and dynamic crosslinking in the encapsulation film preparation method provided in Embodiment 1 of the present invention; wherein Figure 2 (a) is a schematic diagram illustrating the principle of covalent crosslinking in the encapsulating film; Figure 2 (b) is a schematic diagram of the principle of dynamic cross-linking in the encapsulation film. Detailed Implementation

[0023] The present invention will now be further described in conjunction with specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0024] In the description of this invention, it should be noted that directional terms such as "center," "lateral," "longitudinal," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation and positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These are used only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. They should not be construed as limiting the specific scope of protection of this invention. The terms "first," "second," etc., in the specification and claims of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. The terms "comprising" and "having," and any variations thereof, in the specification and claims of this invention, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products, or devices.

[0025] This embodiment provides an encapsulating film comprising, by weight, the following raw materials: 100 parts matrix resin, 2-6 parts dynamic crosslinking site donors, 1-2 parts dynamic crosslinking agent, 0.3-0.6 parts catalyst, 0.05-1 part covalent crosslinking agent, and 0.05-2 parts co-crosslinking agent. The covalent crosslinking agent provides free radicals upon heating, which induce irreversible C-C bonds to form on the matrix resin. The dynamic crosslinking site donors, initiated by free radicals, attach to the molecular chain of the matrix resin. The anhydride groups attached to the matrix resin molecular chain undergo ring-opening and esterification under the action of the dynamic crosslinking agent, forming thermally reversible ester bonds. The irreversible C-C bonds and the thermally reversible ester bonds together constitute an encapsulating film with a dual-network structure based on the coexistence of covalent and dynamic crosslinking. Please refer to... Figure 1 This solution introduces carboxyl / anhydride groups into the molecular chain of the matrix resin. These carboxyl / anhydride groups provide dynamic crosslinking sites, and polyols are used as dynamic crosslinking agents. This allows for the construction of a dynamic ester bond network on the matrix resin. This design is an improvement on current photovoltaic encapsulation films. The improved encapsulation film can form a dual-network structure with both covalent and dynamic crosslinking. This enables the encapsulation film to adhere to the glass stably during the service life of the photovoltaic module, and also allows for dynamic bond breaking and recombination and network topology rearrangement based on ester exchange during the recycling of the photovoltaic module. This provides stress relaxation channels and controllable debonding capability for the encapsulation film, enabling gentle and rapid delamination between the encapsulation film and the glass, and achieving low-loss recycling of both the glass and the encapsulation film.

[0026] Among them, such as Figure 2 (b) As shown in the figure, dynamic crosslinking is constructed based on reversible covalent bonds. In this scheme, it is obtained using an ester exchange reaction, the specific process of which is as follows: by introducing anhydride groups into the long chain of the original matrix resin, and then performing ring-opening and esterification under the action of polyol, reversible ester bonds are formed. The reversible ester bonds can maintain structural stability during the service of the photovoltaic module (operating temperature below 80℃). In a specific alcohol / alkali thermal recovery environment, an ester exchange reaction and network rearrangement are excited, which in turn induces stress relaxation of the encapsulating film and reduces its adhesion to the glass interface, thereby achieving controllable separation between the encapsulating film and the glass. Based on this, this scheme achieves dynamic crosslinking between the encapsulating film and the glass through reversible ester bonds formed by anhydride / carboxyl sites and polyols or polyesters, that is, the formed reversible ester bonds can provide the encapsulating film with reversible dissociation ability during the recycling stage.

[0027] like Figure 2 As shown in Figure (a), covalent crosslinking utilizes the free radicals provided by organic peroxide crosslinking agents upon heating. These free radicals supply the molecular chains of the matrix resin, abstracting hydrogen atoms and creating free radical active sites in the macromolecular chains. Subsequently, different macromolecular chain free radicals connect occasionally or through co-crosslinking agents to form irreversible C-C bonds, thereby ensuring the structural stability and strength of the prepared encapsulating film during long-term service.

[0028] When the encapsulating film is heated during the lamination process, the peroxide crosslinking agent initiates a free radical reaction to build a "covalent framework," while the anhydride groups and polyols undergo esterification under the action of a catalyst to build a "dynamic crosslinking network," ultimately forming a dual-network structure of "covalent crosslinking and dynamic crosslinking." This dual-network structure enables the encapsulating film to achieve high-stability adhesion during the service life of photovoltaic modules, and also achieves mild and controllable debonding performance during the recycling stage of photovoltaic modules, thereby improving the overall practicality of the encapsulating film.

[0029] The matrix resin may include any one or a mixture of two of ethylene vinyl acetate (EVA) and polyolefin elastomer (POE). The VA content in the EVA may be 28wt%~33wt%, preferably 28wt%. The dynamic crosslinking site donor contains at least one functional group, either a carboxyl group or an anhydride group, to provide reaction sites where dynamic exchange can occur. The dynamic crosslinking site donor includes one or more of maleic anhydride, itaconic anhydride, acrylic acid, methacrylic acid, itaconic acid, fumaric acid, maleic acid, and glycidyl methacrylate. The selection of the dynamic crosslinking site donor containing at least one functional group, either a carboxyl group or an anhydride group, allows for direct compounding with the existing matrix resin on the encapsulation film. This eliminates the need to modify the matrix resin; the dynamic crosslinking site donor is simply compounded onto the matrix resin to introduce dynamic crosslinking sites. Furthermore, the dynamic crosslinking site donor, combined with a mild zinc-based catalyst, ensures that the constructed dynamic crosslinking network undergoes dynamic exchange only upon catalyst activation. At room temperature or normal service temperature, the migration, rotation, and relaxation capabilities of EVA matrix molecular chains and adjacent polymer segments in the dynamic cross-linked network are low, and the transesterification rate is slow, thus the dynamic cross-linked network is relatively stable. However, during the recycling stage, under the combined effects of heating, solvent swelling, and an alkaline environment, the transesterification and network rearrangement rates are significantly increased, thereby enabling the prepared encapsulating film to balance stability and dynamic performance.

[0030] Dynamic crosslinking agents include one or more of polyols and polyesters. The polyols can be selected from one or more of trimethylolpropane, pentaerythritol, glycerol, sorbitol, and polyether polyols. Trimethylolpropane has three active primary hydroxyl groups, with a fixed functionality of 3. The primary hydroxyl groups have high reactivity, reacting quickly and stably with isocyanates, anhydrides, and epoxy groups, making them suitable for the curing and reversible reactions of dynamic crosslinking systems, ensuring a uniform distribution of dynamic bonds in the network. Furthermore, the small molecular size of trimethylolpropane, with its central carbon atom connected to three hydroxymethyl chains, provides moderate steric hindrance, ensuring smooth crosslinking reactions without hindering the breaking and recombination of dynamic bonds due to excessive steric hindrance. Compared to other more rigid aromatic polyols and polyfunctional alcohols with higher crosslinking densities, dynamic materials crosslinked with trimethylolpropane have a milder decrosslinking temperature and are easier to melt and reshape, making them suitable for the recycling and reprocessing of thermosetting materials. Pentaerythritol contains four active primary hydroxyl groups, which are symmetrically distributed. At the same molar addition, pentaerythritol can form more crosslinking points, rapidly increasing the crosslinking density of the system and significantly improving the tensile strength and hardness of the material. Furthermore, all four hydroxyl groups are highly active primary hydroxyl groups, reacting rapidly and to a high degree with isocyanates, carboxyl groups, acid anhydrides, and epoxy groups. This satisfies the processing requirements for rapid curing and ensures the uniform distribution of dynamic covalent bonds (such as reversible urethane bonds and ester bonds) in the network, providing a structural basis for dynamic repair, decrosslinking, and remodeling. Polyether polyols are a class of polyol polymers with ether bonds (COC) as the backbone and hydroxyl groups at the ends. Due to the low rotational barrier within the ether bonds, their molecular chains exhibit extremely high flexibility. Long, flexible ether bond backbones can be introduced into the dynamic crosslinking network. Based on the high flexibility of the ether bond backbone, the collision probability of dynamic bonds can be significantly increased, accelerating the dissociation and recombination rate of dynamic covalent bonds (such as reversible urethane bonds and ester bonds) in the dynamic crosslinking network. Furthermore, polyether polyols can generally be used in combination with small molecule polyols (such as trimethylolpropane, pentaerythritol, etc.), allowing the dynamic crosslinking agent to balance the strength and dynamic properties of the crosslinked network. Polyesters are multifunctional ester compounds containing two or more ester groups in their molecules and capable of participating in transesterification reactions under the action of zinc-containing catalysts. Polyesters include one or more of triethyl citrate, tributyl citrate, glyceryl triacetate, diallyl maleate, diallyl fumarate, polycaprolactone polyol, and polyester polyol. Multiple ester groups in polyesters can act as dynamic transesterification sites, undergoing transesterification reactions with hydroxyl, carboxyl, or alcohol molecules in the encapsulation film system in the presence of zinc-based catalysts (i.e., catalysts containing zinc ions), thereby participating in the construction and rearrangement of the dynamic crosslinked network.

[0031] The catalyst can be selected from one or more of zinc acetate, zinc oxide, zinc chloride, zinc lactate, and zinc acetylacetonate. The advantages of using zinc ion-type catalysts are as follows: (1) It can itself serve as a dynamic cross-linking point for metals, constructing a dual dynamic network of "covalent dynamic bond + coordination dynamic bond". (2) Carboxyl groups, hydroxyl groups, amide bonds, etc. on the polymer chain can all form coordination bonds with zinc ions. Through the coordination cross-linking of zinc ions, the deficiency of covalent cross-linking can be supplemented, and the cross-linking density, modulus, tensile strength, etc. of the system can be improved. In addition, the bond energy of the coordination bond is moderate, which can effectively transfer stress and dissipate impact energy through bond dissociation-reconstruction when the material is subjected to impact, thus enabling it to exist flexibly in the dynamic network. (3) As a catalyst, zinc ions can promote ester exchange reaction and dynamic network rearrangement. The principle is that the metal cation lowers the activation energy of the reaction, so that the breaking and recombination of ester bonds can occur rapidly under mild conditions.

[0032] The covalent crosslinking agent can be an organic peroxide crosslinking agent capable of providing free radicals. The covalent crosslinking agent can be selected from one or more of the following: tert-butyl peroxycarbonate-2-ethylhexyl ester, dicumyl peroxide, bis-tert-butyl peroxycarbonate-2-ethylhexyl ester, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, tert-butyl peroxycarbonate, and tert-amyl peroxycarbonate. Tert-butyl peroxycarbonate-2-ethylhexyl ester is a monoperoxycarbonate that decomposes at 50-70℃ to generate active free radicals, which is lower than the decomposition temperature of dicumyl peroxide. Furthermore, its decomposition products are tert-butoxy radicals and 2-ethylhexoxy radicals, which do not contain benzene carcinogens; thus improving the decomposition effect and safety of the prepared encapsulating film. Dicumyl peroxide is a highly efficient free radical initiator that can rapidly initiate the glass formation of hydrogen atoms on polymer molecular chains, forming chain free radicals that couple and generate stable CC permanent crosslinking bonds. It can also synergistically work with co-crosslinking agents to inhibit vertical main chain breakage, thereby improving crosslinking efficiency. For bis(tert-butylperoxide)diisopropylbenzene and 1,1-bis(tert-butylperoxide)-3,3,5-trimethylcyclohexane, both molecules contain two peroxide bonds. Therefore, when either of these substances is used as a covalent crosslinking agent, it can achieve stable decomposition and continuous free radical generation, ensuring sufficient crosslinking reaction without localized over-crosslinking or scorching, thus improving the stability of the covalent crosslinking process.

[0033] The co-crosslinking agent can be selected from one or more of triallyl isocyanurate (TAIC), triallyl cyanurate, trimethylolpropane, trimethacrylate, and diallyl phthalate. The co-crosslinking agent can be a small or large molecule compound containing two or more unsaturated groups capable of participating in free radical polymerization / addition reactions. The unsaturated double bonds of the co-crosslinking agent can rapidly capture free radicals generated by peroxides, preferentially undergoing copolymerization and crosslinking, reducing the attack of free radicals on the polymer backbone, and inhibiting degradation at its source. When used in conjunction with peroxides, it can achieve efficient crosslinking of the matrix resin. Furthermore, the co-crosslinking agent can indirectly regulate the exchange rate of dynamic bonds by adjusting the chain segment mobility of the network, thereby enabling the co-crosslinking agent to balance the dynamic properties and structural stability of the encapsulating film.

[0034] Encapsulating films may also include additives, such as one or more of silane coupling agents, antioxidants, light stabilizers, and ultraviolet absorbers. These are common additives in existing encapsulating films, and can be selectively added as needed during actual use to improve the adhesion, weather resistance, processing stability, and appearance quality of the resulting encapsulating film.

[0035] In this scheme, the dynamic crosslinking site donor is preferably maleic anhydride, the dynamic crosslinking agent is preferably trimethylolpropane (TMP), and the catalyst is preferably zinc acetate. The hydroxyl group in TMP and the carboxyl / anhydride group form a classic reaction pair, and zinc acetate has a specific catalytic effect on the transesterification and esterification reactions of this system. A complete dynamic crosslinking system is constructed using maleic anhydride, TMP, and zinc acetate. Maleic anhydride can be grafted onto the molecular chain of the matrix resin through melt grafting or solution grafting, thereby enabling the matrix resin molecular chain to carry dynamic sites suitable for exchange. TMP, being a small molecule, is uniformly dispersed in the system and can quickly bind to the dynamic ester bonds of maleic anhydride, avoiding local aggregation of the constructed dynamic sites and thus achieving a more uniform dynamic crosslinking network. Furthermore, the anhydride group of maleic anhydride is far more reactive than that of ordinary carboxyl groups. Without the need for high-temperature dehydration, it can rapidly undergo ring-opening esterification with the primary hydroxyl group in trimethylolpropane under the mild catalysis of zinc acetate. After ring-opening, carboxyl groups are produced in situ, thus continuously providing sites for subsequent dynamic exchange and coordination. This allows for a continuous supply of dynamic exchange and coordination sites in a single reaction. In addition, the dynamic ester bond formed by the reaction of maleic anhydride and trimethylolpropane undergoes reversible ester exchange under zinc acetate catalytic heating, achieving network dissociation and recombination. Simultaneously, the zinc ions dissociated from zinc acetate can form carboxylic acid zinc coordination bonds with the carboxyl groups generated from the ring-opening of maleic anhydride and the ester groups in the system. This dual dynamic mechanism based on "dynamic ester bonds" and "dynamic coordination bonds" can improve the dynamic performance of the constructed dynamic cross-linked network, thereby enhancing its recovery performance.

[0036] Based on the encapsulating film described above, this solution also provides a laminate, which includes a cover glass, the encapsulating film as described above, and a back glass. The encapsulating film is bonded to the cover glass and the back glass respectively based on the lamination process, thereby forming a three-layer laminate.

[0037] The lamination process may include vacuuming, heating, and heat curing. Lamination conditions may include: temperature 140℃~160℃, time 8-20 min, and vacuum degree ≤-0.08MPa. Preferably, the lamination temperature is 146℃~148℃, and the lamination time is 10-15 min. During lamination curing, the peroxide crosslinking agent initiates the formation of a covalent crosslinked network; simultaneously, under the catalysis of the zinc catalyst, dynamic ester exchange and network rearrangement occur based on the ester bond structure formed by the dynamic crosslinking site donors and the dynamic crosslinking agent, ultimately obtaining a dual crosslinked network structure with both covalent and dynamic crosslinking, thus enabling the encapsulating film to balance service stability and recyclability.

[0038] Based on this, this solution also provides a method for preparing an encapsulating film, which can be prepared using a melt-based process. The method for preparing the encapsulating film includes the following steps: (a) Premix: Weigh 100 parts by weight of the matrix resin, 4 parts by weight of the dynamic crosslinking site donor, 1.5 parts by weight of the dynamic crosslinking agent, 0.45 parts by weight of the catalyst, 0.5 parts by weight of the covalent crosslinking agent, 1 part by weight of the co-crosslinking agent, and 0.05 parts by weight of the additives according to the formula. Dry mix the weighed raw materials using a high-speed mixer to obtain the premix.

[0039] (ii) Melt blending: The premixed material is added to a twin-screw extruder for melt blending. The blending temperature can be controlled within the range of 80℃~130℃, and the die head temperature can be controlled within the range of 100℃~140℃. After cooling, the mixture is pelletized to obtain mixed pellets.

[0040] (iii) Extrusion film formation: The mixed granules are extruded into a film by extrusion casting or extrusion blow molding, and then cooled and shaped before being slit and rolled up to obtain the encapsulation film.

[0041] The thickness of the resulting encapsulating film can be 0.3mm to 1mm, preferably 0.5mm to 0.8mm.

[0042] In other embodiments of this solution, steps (i) and (ii) may also be performed in the following manner: (a) Premix: Weigh 100 parts by weight of matrix resin, 4 parts by weight of dynamic crosslinking site donor, 1.5 parts by weight of dynamic crosslinking agent, 0.45 parts by weight of catalyst, 0.5 parts by weight of covalent crosslinking agent, 1 part by weight of co-crosslinking agent, and 0.05 parts by weight of additives according to the formula. Dry mix the matrix resin, dynamic crosslinking site donor, dynamic crosslinking agent, catalyst, and additives using a high-speed mixer to obtain the premix.

[0043] (ii) Melt blending: The premix from step (i) is added to a twin-screw extruder for melt blending. The covalent crosslinking agent and co-crosslinking agent are added in the middle or later stages by means of post-addition or side feeding. The blending temperature can be controlled at 80-130℃, and the die head temperature can be controlled at 100-140℃. After extrusion, the mixture is cooled and pelletized to obtain mixed pellets.

[0044] In this improvement process, the covalent crosslinking agent and the co-crosslinking agent are added in the middle or later stages using a post-addition or side-feeding method. This is to avoid premature decomposition of organic peroxides, which could lead to discoloration or uncontrolled crosslinking.

[0045] It is understood that in some other embodiments, the high-speed mixer in step (a) may be replaced by a drum mixer.

[0046] Based on the technique of preparing the encapsulating film using the above-described preparation method, a laminated component is obtained through a lamination process. The resulting laminated component simultaneously meets the requirements of stability during its service life and recyclability during the recycling phase. Therefore, this solution also provides a recycling process for the laminated component, which includes the following steps: S1: Cut off or clean the excess adhesive area at the edge of the laminate to expose the adhesive layer between the encapsulating film and the cover glass, as well as the adhesive layer between the encapsulating film and the back glass.

[0047] S2: The treated laminate is completely immersed in a mixed solvent containing ethanol and NaOH and heated for 0.5h to 6h, which causes the encapsulating film to swell and undergo dynamic bond exchange and rearrangement, thereby reducing interfacial adhesion and achieving delamination of the cover glass, encapsulating film and back glass.

[0048] S3: After layering, the cover glass, back glass, and encapsulating film can be recycled separately, thus completing the recycling of the laminate.

[0049] In step S2, the volume fraction of ethanol in the mixed solvent system is 20-90 vol%, the concentration of NaOH is 0.01-1 mol / L, the recovery temperature is 60-80℃, and the treatment time is 0.5-6 h. In step S3, after the encapsulating film is recovered, the separated encapsulating film can be further cleaned, dried, and reprocessed for reuse, thereby improving the utilization efficiency of the encapsulating film.

[0050] In this solution, the encapsulating film is based on a dual-network structure where "dynamic cross-linking" and "covalent cross-linking" coexist. This allows for the recycling of laminated components obtained through lamination using the encapsulating film. During recycling, the encapsulating film swells under alkaline conditions at 70°C, causing dynamic exchange and rearrangement of the internal dynamic network. This reduces interfacial adhesion, enabling gentle debonding and low-damage delamination between the encapsulating layer and the glass. The swelling essentially involves water vapor and small-molecule solvents penetrating the cross-linked network of the encapsulating film, widening the spacing between cross-linking points. This transforms the polymer chains from "tightly restricted" to "relaxed and mobile," significantly reducing the resistance to migration, rotation, and diffusion. Previously unbreakable dynamic bonds (ester bonds, coordination bonds) can now approach each other and exchange. Furthermore, the mild temperature increase or environmental stimulation accompanying swelling activates the zinc catalyst. Under the catalysis of the zinc catalyst, the activation energy of ester exchange and coordination bond dissociation is significantly reduced, allowing dynamic exchange to proceed rapidly. This results in dynamic exchange and rearrangement of the dynamic network within the encapsulating film. These two aspects effectively reduce the interfacial adhesion between the encapsulating film and the glass, thereby achieving the goal of delaminating the encapsulating film, cover glass, and back glass, and enabling the recycling of the cover glass, back glass, and encapsulating layer.

[0051] Furthermore, this solution utilizes maleic anhydride, which, under the mild catalysis of zinc acetate, rapidly undergoes ring-opening with the primary hydroxyl group in trimethylolpropane to generate a carboxyl group. This carboxyl group is a highly reactive group that readily adsorbs moisture, causing the encapsulating film to swell more quickly in the humid and hot environment of immersion, thus triggering dynamic exchange earlier and improving the recycling efficiency of subsequent laminates. Moreover, the zinc ion coordination bonds formed by maleic anhydride, zinc acetate, and trimethylolpropane are more prone to dissociation-solventization-reorganization in the presence of polar small molecules (such as water and alcohols), preferentially disrupting the zinc coordination bonds at the interface and accelerating the debonding between the encapsulating film and the glass interface.

[0052] Based on this, the present solution also provides a photovoltaic module, which includes an encapsulating film as described above. The photovoltaic module can be assembled using the encapsulating film described above based on a lamination process, so that the assembled photovoltaic module can operate stably during its service life. After the photovoltaic module has reached the end of its service life, the photovoltaic module can be disassembled and the cover glass, back glass, encapsulating film and other parts can be recycled and reused based on a lamination recycling process.

[0053] To verify the performance of the encapsulating film provided in this embodiment, the technicians also conducted the following experiments.

[0054] Experimental group 1 The raw materials for Experimental Group 1 included: 100 parts by weight of ethylene vinyl acetate, 4 parts by weight of maleic anhydride, 1.5 parts by weight of trimethylolpropane, 0.4 parts by weight of zinc acetate, 0.7 parts by weight of tert-butyl percarbonate-2-ethylhexyl ester, 0.5 parts by weight of triallyl isocyanurate (TAIC), 0.2 parts by weight of silane coupling agent, 0.2 parts by weight of antioxidant, and 0.3 parts by weight of ultraviolet light absorber.

[0055] The method for preparing the encapsulating film using the raw materials of Experimental Group 1 is as follows: (I) Weigh 100 parts by weight of ethylene vinyl acetate, 4 parts by weight of maleic anhydride, 1.5 parts by weight of trimethylolpropane, 0.4 parts by weight of zinc acetate, 0.2 parts by weight of silane coupling agent, 0.2 parts by weight of antioxidant, and 0.3 parts by weight of ultraviolet light absorber according to the formula. Dry mix the above raw materials using a high-speed mixer to obtain a premix.

[0056] (ii) The premix from step (i) is added to a twin-screw extruder for melt blending. 0.7 parts by weight of tert-butyl percarbonate-2-ethylhexyl ester and 0.5 parts by weight of triallyl isocyanurate (TAIC) are added later in the middle to later stages. The blending temperature can be controlled at 80-130℃, and the die head temperature can be controlled at 100-140℃. After extrusion, the mixture is cooled and pelletized to obtain mixed granules.

[0057] (iii) The mixed granules are extruded and cast or extruded and blown into a film, then cooled and shaped, and then slit and rolled up to obtain the encapsulation film.

[0058] Experimental group 2 The raw materials for Experimental Group 2 included: 100 parts by weight of ethylene vinyl acetate, 2 parts by weight of maleic anhydride, 1 part by weight of trimethylolpropane, 0.3 parts by weight of zinc acetate, 0.1 parts by weight of zinc stearate, 0.7 parts by weight of tert-butyl percarbonate-2-ethylhexyl ester, 0.5 parts by weight of triallyl isocyanurate (TAIC), 0.2 parts by weight of silane coupling agent, 0.2 parts by weight of antioxidant, and 0.3 parts by weight of ultraviolet light absorber.

[0059] The method for preparing the encapsulating film using the raw materials of Experimental Group 2 is as follows: (I) Weigh 100 parts by weight of ethylene vinyl acetate, 2 parts by weight of maleic anhydride, 1 part by weight of trimethylolpropane, 0.3 parts by weight of zinc acetate, 0.1 parts by weight of zinc stearate, 0.2 parts by weight of silane coupling agent, 0.2 parts by weight of antioxidant, and 0.3 parts by weight of ultraviolet light absorber according to the formula. Dry mix the above raw materials using a high-speed mixer to obtain a premix.

[0060] (ii) The premix from step (i) is added to a twin-screw extruder for melt blending. 0.7 parts by weight of tert-butyl percarbonate-2-ethylhexyl ester and 0.5 parts by weight of triallyl isocyanurate (TAIC) are added later in the middle to later stages. The blending temperature can be controlled at 80-130℃, and the die head temperature can be controlled at 100-140℃. After extrusion, the mixture is cooled and pelletized to obtain mixed granules.

[0061] (iii) The mixed granules are extruded and cast or extruded and blown into a film, then cooled and shaped, and then slit and rolled up to obtain the encapsulation film.

[0062] Experimental group 3 The raw materials for experimental group 3 included: 100 parts by weight of ethylene vinyl acetate, 4 parts by weight of itaconic anhydride, 1.5 parts by weight of trimethylolpropane, 0.4 parts by weight of zinc acetate, 0.7 parts by weight of tert-butyl percarbonate-2-ethylhexyl ester, 0.5 parts by weight of triallyl isocyanurate (TAIC), 0.2 parts by weight of silane coupling agent, 0.2 parts by weight of antioxidant, and 0.3 parts by weight of ultraviolet light absorber.

[0063] The method for preparing the encapsulating film using the raw materials of Experimental Group 3 is as follows: (I) Weigh 100 parts by weight of ethylene vinyl acetate, 4 parts by weight of itaconic anhydride, 1.5 parts by weight of trimethylolpropane, 0.4 parts by weight of zinc acetate, 0.2 parts by weight of silane coupling agent, 0.2 parts by weight of antioxidant, and 0.3 parts by weight of ultraviolet light absorber according to the formula. Dry mix the above raw materials using a high-speed mixer to obtain a premix.

[0064] (ii) The premix from step (i) is added to a twin-screw extruder for melt blending. 0.7 parts by weight of tert-butyl percarbonate-2-ethylhexyl ester and 0.5 parts by weight of triallyl isocyanurate (TAIC) are added later in the middle to later stages. The blending temperature can be controlled at 80-130℃, and the die head temperature can be controlled at 100-140℃. After extrusion, the mixture is cooled and pelletized to obtain mixed granules.

[0065] (iii) The mixed granules are extruded and cast or extruded and blown into a film, then cooled and shaped, and then slit and rolled up to obtain the encapsulation film.

[0066] Experimental group 4 The raw materials for experimental group 4 included: 100 parts by weight of ethylene vinyl acetate, 2 parts by weight of itaconic anhydride, 1 part by weight of trimethylolpropane, 0.3 parts by weight of zinc acetate, 0.1 parts by weight of zinc stearate, 0.7 parts by weight of tert-butyl percarbonate-2-ethylhexyl ester, 0.5 parts by weight of triallyl isocyanurate (TAIC), 0.2 parts by weight of silane coupling agent, 0.2 parts by weight of antioxidant, and 0.3 parts by weight of ultraviolet light absorber.

[0067] The method for preparing the encapsulating film using the raw materials of Experiment Group 4 is as follows: (I) Weigh 100 parts by weight of ethylene vinyl acetate, 2 parts by weight of itaconic anhydride, 1 part by weight of trimethylolpropane, 0.3 parts by weight of zinc acetate, 0.1 parts by weight of zinc stearate, 0.2 parts by weight of silane coupling agent, 0.2 parts by weight of antioxidant, and 0.3 parts by weight of ultraviolet light absorber according to the formula. Dry mix the above raw materials using a high-speed mixer to obtain a premix.

[0068] (ii) The premix from step (i) is added to a twin-screw extruder for melt blending. 0.7 parts by weight of tert-butyl percarbonate-2-ethylhexyl ester and 0.5 parts by weight of triallyl isocyanurate (TAIC) are added later in the middle to later stages. The blending temperature can be controlled at 80-130℃, and the die head temperature can be controlled at 100-140℃. After extrusion, the mixture is cooled and pelletized to obtain mixed granules.

[0069] (iii) The mixed granules are extruded and cast or extruded and blown into a film, then cooled and shaped, and then slit and rolled up to obtain the encapsulation film.

[0070] control group The raw materials for the control group included: 100 parts by weight of ethylene vinyl acetate, 0.7 parts by weight of tert-butyl peroxycarbonate-2-ethylhexyl ester, 0.5 parts by weight of triallyl isocyanurate (TAIC), 0.2 parts by weight of silane coupling agent, 0.2 parts by weight of antioxidant, and 0.3 parts by weight of ultraviolet light absorber.

[0071] The method for preparing the encapsulating film using the raw materials from the control group is as follows: (I) Weigh 100 parts by weight of ethylene vinyl acetate, 0.2 parts by weight of silane coupling agent, 0.2 parts by weight of antioxidant, and 0.3 parts by weight of ultraviolet light absorber according to the formula. Dry mix the above raw materials using a high-speed mixer to obtain a premix.

[0072] (ii) The premix from step (i) is added to a twin-screw extruder for melt blending. 0.7 parts by weight of tert-butyl percarbonate-2-ethylhexyl ester and 0.5 parts by weight of triallyl isocyanurate (TAIC) are added later in the middle to later stages. The blending temperature can be controlled at 80-130℃, and the die head temperature can be controlled at 100-140℃. After extrusion, the mixture is cooled and pelletized to obtain mixed granules.

[0073] (iii) The mixed granules are extruded and cast or extruded and blown into a film, then cooled and shaped, and then slit and rolled up to obtain the encapsulation film.

[0074] The encapsulation films prepared in experimental groups 1, 2, 3, 4 and the control group were subjected to the following performance tests.

[0075] (I) Degree of crosslinking determination The degree of crosslinking of the encapsulating films prepared in experimental groups 1, 2, 3, 4, and the control group was determined by differential scanning calorimetry (DSC) according to GB / T 36965-2018. The results are shown in Table 1. Since determining the degree of crosslinking of the encapsulating films using DSC is a common performance testing procedure in this field, it will not be described in detail.

[0076] (II) Transmittance Measurement Referring to GB / T 29848-2018, the average transmittance of the encapsulating films prepared in experimental groups 1, 2, 3, 4, and the control group at wavelengths of 290-1100 nm was determined using a spectrophotometer. The results are shown in Table 1. Since measuring the average transmittance of the encapsulating films using a spectrophotometer is a common performance testing procedure in this field, this procedure will not be described in detail.

[0077] (III) Determination of tensile strength and elongation at break The light transmittance of the encapsulating films prepared in experimental groups 1, 2, 3, 4, and the control group was measured using an electronic universal tensile testing machine. The results are shown in Table 1. Since measuring the tensile strength and elongation at break of the encapsulating films using an electronic universal tensile testing machine is a common performance testing procedure in this field, this procedure will not be described in detail.

[0078] (IV) Peel strength test The interfacial peel strength between the encapsulating film and the glass plate prepared in experimental groups 1, 2, 3, 4, and the control group was measured using the commonly used 180° peel method. The results are shown in Table 1. Since the 180° peel method is a commonly used performance testing procedure in this field, it will not be described in detail.

[0079] (V) Is it recyclable? The encapsulating films prepared in experimental groups 1, 2, 3, and 4, as well as the control group, were used to obtain corresponding laminates according to the above-described scheme. The obtained laminates were then subjected to the following procedure to determine their recyclability: the excess adhesive at the edges of the laminates was removed or cleaned to expose the edges of the adhesive layers between the encapsulating film and the cover glass, as well as between the encapsulating film and the back glass. The treated laminates were then placed in a mixed solvent containing ethanol and NaOH and heated to 70°C for 2 hours. After 2 hours of heating, the separation of the cover glass, encapsulating film, and back glass was observed. The results are shown in Table 1.

[0080] Table 1 compares the performance of the encapsulating films prepared in experimental groups 1, 2, 3, 4, and the control group. Analysis of Table 1 shows that the control group, consisting of a conventional EVA encapsulation film system, exhibits a relatively dense structure and strong interfacial adhesion due to the absence of additional dynamic crosslinking components in its encapsulation film. This results in higher crosslinking degree, tensile strength, and peel strength. However, the irreversible crosslinking network in the control group's encapsulation film makes effective network topology rearrangement and stress relaxation difficult even after immersion in a 70°C ethanol / NaOH solution for 2 hours. Therefore, effective separation between the glass and the encapsulation film cannot be achieved.

[0081] For Experimental Group 1, 4 parts by weight of maleic anhydride, 1.5 parts by weight of trimethylolpropane, and 0.4 parts by weight of zinc acetate were used. Maleic anhydride has high reactivity and can effectively introduce anhydride reaction sites into the ethylene vinyl acetate (EVA) molecular chain, forming a dynamic ester bond structure with trimethylolpropane. Therefore, the degree of crosslinking of the encapsulating film prepared in Experimental Group 1 can be maintained at 85.16%, and the peel strength can reach 86.34 N / cm. The above experimental data show that the encapsulating film prepared in Experimental Group 1 still has good interfacial adhesion performance after the introduction of a dynamic crosslinking network. At the same time, because dynamic ester bonds are formed in the encapsulating film of Experimental Group 1, transesterification and network rearrangement can occur during the recycling stage. Therefore, the laminate formed based on the encapsulating film of Experimental Group 1 can be separated and recycled after heating at 70°C for 2 hours.

[0082] For experimental group 2, the amounts of maleic anhydride and trimethylolpropane were lower than those in experimental group 1, and a mixture of 0.3 parts by weight of zinc acetate and 0.1 parts by weight of zinc stearate was used. Due to the reduced amount of dynamic crosslinking site donors in experimental group 2, the density of dynamic ester bond crosslinking points was relatively lower, resulting in slightly lower tensile and peel strengths compared to experimental group 1. Furthermore, the zinc stearate in experimental group 2 has a better hydrophobic constant structure, which is beneficial for improving the dispersibility of zinc-based components in ethylene vinyl acetate (EVA). However, its lubricating effect may reduce interfacial adhesion strength to some extent, thus resulting in a peel strength of 82.57 N / cm for experimental group 2, slightly lower than that of experimental group 1.

[0083] For experimental group 3, 4 parts by weight of itaconic anhydride, 1.5 parts by weight of trimethylolpropane, and 0.4 parts by weight of zinc acetate were used. Itaconic anhydride contains both anhydride and unsaturated structures, providing numerous reaction sites and facilitating the formation of a relatively high-density dynamic ester bond network. Therefore, the encapsulating film prepared in experimental group 3 exhibits high crosslinking degree and tensile strength, at 85.82% and 12.64 MPa, respectively. However, due to the strong polarity of itaconic anhydride, higher addition amounts may lead to localized polar enrichment or interfacial structural differences, affecting the uniformity of adhesion between the encapsulating film and the glass interface. Consequently, the peel strength of the encapsulating film in experimental group 3 is lower than that in experimental groups 1 and 2.

[0084] For experimental group 4, the amounts of itaconic anhydride and trimethylolpropane were lower than those in experimental group 3, and the catalyst used in experimental group 4 was a combination of zinc acetate and zinc stearate. First, the lower amount of itaconic anhydride reduced the influence of polar components on the interface of the prepared encapsulating film. At the same time, zinc stearate improved the dispersibility of zinc-based components in EVA, thereby improving the chain segment mobility and flexibility of the prepared encapsulating film. As a result, the encapsulating film prepared in experimental group 4 had the highest elongation at break, reaching 765%, and a peel strength of 84.76 N / cm. This proves that by reducing the amount of dynamic crosslinking site donors, the interfacial adhesion performance of the encapsulating film prepared in experimental group 4 was restored to a certain extent. At the same time, the encapsulating film prepared in experimental group 4 could still undergo dynamic network rearrangement and achieve controllable separation under the recycling condition of heating at 70°C for 2 hours.

[0085] In summary, compared with the control group, experimental groups 1 to 4 further introduced dynamic crosslinking into the conventional crosslinking system. During dynamic crosslinking, the anhydride groups can undergo ring-opening esterification with trimethylolpropane during lamination to form an ester crosslinking network; simultaneously, TBEC and TAIC can still induce the formation of an irreversible covalent crosslinking network in the film. Therefore, experimental groups 1 and 4 all formed a dual-network structure with coexisting covalent crosslinking and dynamic ester crosslinking networks, thus enabling the encapsulation film to balance service stability and recyclability.

[0086] The basic principles, main features, and advantages of this invention have been described above. Those skilled in the art should understand that this invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made without departing from the spirit and scope of the invention, and all such changes and modifications fall within the scope of the invention as claimed. The scope of protection claimed by this invention is defined by the appended claims and their equivalents.

Claims

1. An encapsulating film, characterized in that, It comprises, by weight, the following raw materials: 100 parts matrix resin, 2-6 parts dynamic crosslinking site donor, 1-2 parts dynamic crosslinking agent, 0.3-0.6 parts catalyst, 0.05-1 part covalent crosslinking agent, and 0.05-2 parts co-crosslinking agent; the dynamic crosslinking site donor contains at least one functional group, either a carboxyl group or an anhydride group; the catalyst is a catalyst containing zinc ions; Covalent crosslinking agents provide free radicals during heating, and these free radicals promote the formation of irreversible C-C bonds on the matrix resin. Dynamic crosslinking site donors are incorporated into the molecular chain of the matrix resin under the initiation of free radicals, and the anhydride groups attached to the molecular chain of the matrix resin undergo ring-opening and esterification under the action of dynamic crosslinking agents to form thermally reversible ester bonds. The irreversible C-C bonds and the thermally reversible ester bonds together constitute a dual-network structure of encapsulation film based on the coexistence of covalent and dynamic crosslinking.

2. The encapsulating film as described in claim 1, characterized in that, The dynamic crosslinking site donor includes one or more of maleic anhydride, itaconic anhydride, acrylic acid, methacrylic acid, itaconic acid, fumaric acid, maleic acid, and glycidyl methacrylate; the dynamic crosslinking site donor is used to provide the matrix resin with reaction sites that can undergo dynamic exchange.

3. The encapsulating film as described in claim 1, characterized in that, The dynamic crosslinking agent is a polyol and / or a polyester; the polyol includes one or more of trimethylolpropane, pentaerythritol, glycerol, sorbitol, and polyether polyol; the polyester includes one or more of triethyl citrate, tributyl citrate, glyceryl triacetate, diallyl maleate, diallyl fumarate, polycaprolactone polyol, and polyester polyol.

4. The encapsulating film as described in claim 1, characterized in that, The catalyst includes one or more of zinc acetate, zinc oxide, zinc chloride, zinc lactate, zinc stearate, and zinc acetylacetonate. And / or, the covalent crosslinking agent is an organic peroxide crosslinking agent that can provide free radicals; And / or, the co-crosslinking agent includes one or more of triallyl isocyanurate, triallyl cyanurate, trimethylolpropane, trimethacrylate and diallyl phthalate; And / or, the matrix resin includes one or both of ethylene vinyl acetate and polyolefin elastomer; And / or, the encapsulating film further includes additives, which include one or more of silane coupling agents, antioxidants, light stabilizers, and ultraviolet light absorbers.

5. A method for preparing an encapsulating film as described in any one of claims 1-4, characterized in that, It includes: Weigh each raw material according to the formula, and then premix, melt, extrude into film, cool, slit and roll up the weighed raw materials in sequence. After passing through the heating and lamination process in the photovoltaic module manufacturing process, the encapsulation film is obtained.

6. The method for preparing the encapsulating film as described in claim 5, characterized in that, The lamination temperature in the heating lamination process is 140℃~160℃, the lamination time is 8-20min, and the vacuum degree is ≤-0.08MPa.

7. A laminate, characterized in that, It includes a cover glass, a back glass, and an encapsulating film as described in any one of claims 1-4 disposed between the cover glass and the back glass, wherein the encapsulating film is used to bond the cover glass and the back glass respectively, thereby forming the laminate with a three-layer structure; the thickness of the encapsulating film is 0.5mm to 0.8mm.

8. A recycling process for laminates as described in claim 7, characterized in that, It includes: The excess adhesive area at the edge of the laminate is cut off or cleaned, so that the edge of the adhesive layer between the encapsulating film and the cover glass, as well as the edge of the adhesive layer between the encapsulating film and the back glass, are exposed. The processed laminate was placed in a mixed solvent containing ethanol and NaOH and heated until the cover glass, encapsulating film and back glass separated into layers, then heating was stopped. The cover glass, back glass, and encapsulating film are recycled separately, thus completing the recycling of the laminate.

9. The recycling process for laminates as described in claim 8, characterized in that, The heating temperature is 60-80℃, and the heating time is 0.5h-6h.

10. A photovoltaic module, characterized in that, It includes the encapsulating film as described in any one of claims 1-4.

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