Carrier membrane composition, carrier membrane as well as preparation method and application of carrier membrane

Abstract

The invention provides a carrier membrane composition, a carrier membrane as well as a preparation method and application of the carrier membrane. The carrier membrane composition comprises first polyolefin resin and modified polyolefin resin, wherein the modified polyolefin resin contains carbon-carbon double bonds, and the average functionality of the carbon-carbon double bonds in the modified polyolefin resin is 5-100; the modified polyolefin resin is obtained by carrying out graft copolymerization reaction on second polyolefin resin and an active monomer containing a carbon-carbon double bond. In the carrier film composition, the first polyolefin resin provides basic physical properties for the formation of the carrier film, and the modified polyolefin resin improves the reactivity and functional characteristics among the components by introducing a carbon-carbon double bond functional group. The cross-linking efficiency, the mechanical property, the thermal stability and the durability of the carrier membrane are optimized under a complex synergistic effect mechanism between the two components, so that the carrier membrane becomes an ideal photovoltaic module carrier membrane material suitable for a main-grid-free technology, and the photoelectric conversion efficiency and the reliability of a module can be further improved.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic adhesive technology, and more specifically, to a carrier film composition, a carrier film, a method for preparing the same, and its applications. Background Art

[0002] In recent years, with the increasing global demand for clean energy, photovoltaic (PV) technology, as an important component of sustainable energy, has received unprecedented attention. Enhancing the market competitiveness of PV cells, improving their photoelectric conversion efficiency, and reducing manufacturing costs have become the driving force and goal of the PV industry's continuous exploration. The emergence of busbar-less (OBB) technology marks a significant advancement in PV cell technology. Compared to traditional busbar technology, OBB technology eliminates the severely light-blocking busbars. This innovation not only improves the photoelectric conversion efficiency of PV cells and reduces power loss due to busbar shading, but also effectively reduces the amount of silver paste used, which has significant economic benefits given the current high silver prices. More importantly, OBB technology demonstrates advantages in improving the microcracks and grid breakage problems that may occur after silicon wafer thinning, improving the aging reliability and durability of modules.

[0003] In the implementation of OBB technology, the cells become relatively fragile during processing due to the removal of traditional main grid lines. In order to better protect the cells from mechanical damage during subsequent processes such as ribbon welding and stacking, and to ensure that the integrity and performance of the cells are not affected, a carrier film is often formed by coating, thereby realizing the connection between the ribbon and the gridless cells.

[0004] To ensure effective coating and enhance the performance of the carrier film, the coating process typically involves an electron beam irradiation pre-crosslinking step. This step improves the creep characteristics of the carrier film, ensuring its dimensional stability at high temperatures and its shape retention during welding. However, the current electron beam irradiation method for pre-crosslinking existing carrier film components suffers from inefficiency. At the same production speed, a higher electron beam current is required to achieve the desired crosslinking level, which not only prolongs the production cycle and increases energy consumption but also directly drives up the production cost of OBB carrier films, further limiting the application of OBB technology in the photovoltaic cell field.

[0005] Therefore, how to reduce the electron beam current required for pre-crosslinking of carrier membrane components while ensuring the basic properties of the carrier membrane, such as temporary adhesion, thermal stability and mechanical properties, has become one of the key issues for promoting the further popularization of OBB technology. Summary of the Invention

[0006] The main objective of this invention is to provide a carrier membrane composition, a carrier membrane, a method for preparing the same, and its applications. The aim is to provide a carrier membrane composition formulation that, while ensuring the basic properties of the carrier membrane such as temporary adhesion, thermal stability, and mechanical properties, reduces the electron beam current required for pre-crosslinking of the carrier membrane components, significantly improves production efficiency, and effectively controls production costs.

[0007] This application provides a carrier membrane composition comprising: a first polyolefin resin and a modified polyolefin resin; wherein the modified polyolefin resin contains carbon-carbon double bonds, and the average functionality of the carbon-carbon double bonds in the modified polyolefin resin is 5 to 100; the modified polyolefin resin is obtained by graft copolymerization of a second polyolefin resin and an active monomer containing carbon-carbon double bonds.

[0008] Further, the grafting rate of the modified polyolefin resin is 0.5-10%; preferably, the grafting rate of the modified polyolefin resin is 1-5%; preferably, the active monomer is a first active monomer and / or a second active monomer; wherein, the first active monomer contains at least two carbon-carbon double bonds and a carbonyl group, and the second active monomer contains a carbon-carbon double bond and at least one of the following groups: epoxy group, carbonyl group, carboxyl group, hydroxyl group, amide group or amino group; preferably, the active monomer is a combination of the first active monomer and the second active monomer; preferably, the weight ratio of the first active monomer and the second active monomer is (50-100):(1-50); preferably, the first active monomer is selected from tripropylene isocyanate. The graft copolymerization reaction comprises one or more of urate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, tripropylene glycol diacrylate, and triallyl cyanurate; preferably, the second active monomer is selected from one or more of glycidyl methacrylate, dimethyl maleate, methacrylic acid, hydroxyethyl methacrylate, and acrylamide; preferably, the graft copolymerization reaction is carried out by at least one of melt extrusion, solution copolymerization, suspension copolymerization, and emulsion copolymerization; preferably, the graft copolymerization reaction is carried out by melt extrusion; preferably, the temperature of the graft copolymerization reaction is 90-180°C; preferably, the speed of melt extrusion is 100-400 rpm.

[0009] Further, the first polyolefin resin and the second polyolefin resin are each independently selected from one or more of polyethylene, polypropylene, ethylene-octene copolymer, ethylene-butene copolymer and ethylene-hexene copolymer; preferably, the weight-average molecular weight of the first polyolefin resin is 25,000 to 500,000 g / mol; preferably, the weight-average molecular weight of the second polyolefin resin is 50,000 to 500,000 g / mol.

[0010] Further, by weight, the carrier membrane composition comprises 1-90 parts of the first polyolefin resin and 10-100 parts of the modified polyolefin resin; preferably, the carrier membrane composition further comprises an electron irradiation crosslinking agent and / or a stabilizer; preferably, by weight, the carrier membrane composition comprises 50-90 parts of the first polyolefin resin, 10-50 parts of the modified polyolefin resin, 0-5.0 parts of the electron irradiation crosslinking aid, and 0-2.0 parts of the stabilizer, and the content of the electron irradiation crosslinking aid and the stabilizer is not simultaneously 0; preferably, the weight ratio of the first polyolefin resin to the modified polyolefin resin in the carrier membrane composition is (1-9):1; preferably, the electron irradiation crosslinking aid is selected from tripropylene isocyanurate, trimethylolpropane triacrylate, tripropylene isocyanurate ... The stabilizer is selected from one or more of hydroxymethylpropane trimethacrylate, triallyl cyanurate, tripropylene glycol diacrylate, pentaerythritol triallyl ether, and pentaerythritol allyl ether; preferably, the stabilizer is selected from one or more of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, bis(1-octoxy-2,2,6,6-tetramethyl-4-piperidinyl) sebacate, poly(4-hydroxy-2,2,6,6-tetramethyl-1-piperidinol) ester, 2-hydroxy-4-n-octoxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-2'-carboxybenzophenone, and 2,4-dihydroxybenzophenone.

[0011] Further, the raw materials for the graft copolymerization reaction include a second polyolefin resin, an active monomer, an initiator, and an antioxidant; preferably, by weight, the raw materials for the graft copolymerization reaction comprise 100 parts of the second polyolefin resin, 1.0 to 15 parts of the active monomer, 0.05 to 2 parts of the initiator, and 0.05 to 0.5 parts of the antioxidant; preferably, the initiator is selected from 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, 1,1-(bis(tert-butylperoxy)3,3,5-trimethylcyclohexane), tert-butyl peroxide, triphenylmethane-4,4',4”-triisocyanate, dicumyl peroxide, bis(2-tert-butylperoxyisopropyl)benzene, tert-butylisocumyl peroxide, tert-amyl peroxide, ditert-amyl peroxide, tert-butyl peroxide benzoate, and tert-butylperoxy-2-ethylhexanoic acid. The antioxidant is selected from one or more of the following: ester, tert-butylperoxide-3,5,5-trimethylhexanoate, di(4-chlorobenzyl)peroxide, di(2,4-dichlorobenzyl)peroxide, di(4-methylphenyl)peroxide, n-butyl-4,4-di(tert-butylperoxide)valerate, ethyl-3,3-di(tert-butylperoxide)butyrate, and tert-butylperoxide-2-ethylhexyl carbonate; preferably, the antioxidant is selected from one or more of the following: pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate, and tris(2,4-di-tert-butylphenyl)phosphite.

[0012] According to a second aspect of the present invention, a carrier membrane is also provided, which is prepared from the above-described carrier membrane composition.

[0013] According to a third aspect of the present invention, a method for preparing the above-mentioned carrier film is also provided, the method comprising the following steps: mixing raw materials including a second polyolefin resin and an active monomer, and then subjecting them to a graft copolymerization reaction to obtain a modified polyolefin resin; mixing raw materials including a first polyolefin resin and a modified polyolefin resin, and then subjecting them to extrusion casting at a first temperature to obtain a cast film; and subjecting the cast film to electron irradiation curing to obtain a carrier film.

[0014] Further, the preparation method includes the following steps: mixing a second polyolefin resin, an active monomer, an initiator, and an antioxidant, and then subjecting the mixture to a graft copolymerization reaction to obtain a modified polyolefin resin; mixing a first polyolefin resin, a modified polyolefin resin, an electron irradiation crosslinking aid, and a stabilizer, and then extruding and casting the mixture at a first temperature to obtain a cast film; and then curing the cast film by electron irradiation to obtain a carrier film.

[0015] Further, the first temperature is 75–200°C; preferably, the thickness of the carrier film is 0.01–0.5 mm; preferably, the temperature of the graft copolymerization reaction is 90–180°C; preferably, the electron irradiation dose is <200 KGy; preferably, the extrusion method is single-screw extrusion or twin-screw extrusion.

[0016] According to a fourth aspect of the present invention, a gridless photovoltaic cell is also provided, the gridless photovoltaic cell comprising the above-described carrier film; or, the gridless photovoltaic cell comprising the carrier film prepared by the above-described preparation method.

[0017] This invention provides a carrier film composition comprising: a first polyolefin resin and a modified polyolefin resin; wherein the modified polyolefin resin contains carbon-carbon double bonds, and the average functionality of the carbon-carbon double bonds in the modified polyolefin resin is 5-100; the modified polyolefin resin is obtained by graft copolymerization of a second polyolefin resin and an active monomer containing carbon-carbon double bonds. In the carrier film composition, the first polyolefin resin provides the basic physical properties for the formation of the carrier film, while the modified polyolefin resin improves the reactivity and functional properties between the components by introducing carbon-carbon double bond functional groups. Under the complex synergistic mechanism between the two components, the crosslinking efficiency, mechanical properties, thermal stability, and durability of the carrier film are optimized, making it an ideal carrier film material for photovoltaic modules, especially suitable for the requirements of busbarless (OBB) technology, which improves the photoelectric conversion efficiency of photovoltaic modules, reduces their production costs, and improves the reliability of the modules. Detailed Implementation

[0018] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the embodiments.

[0019] Terminology Explanation:

[0020] Melt flow index (MFI): This indicates the amount of material that melts per unit time under certain temperature and pressure, usually expressed in g / 10min or g / min. It describes the melting performance of a material during heating. A higher MFI indicates that the material melts faster under the same conditions, and thus has better melting performance.

[0021] Grafting rate: The ratio of the mass of the monomer grafted onto the polymer molecular chain to the mass of the polymer;

[0022] Electron radiation dose: refers to the radiation energy absorbed by a unit mass of material.

[0023] Degree of crosslinking: the gel content of the polymer;

[0024] Peel strength: used to indicate the strength of the bond between two materials; in this application, peel strength refers to the peel strength between the carrier film and the battery cell;

[0025] As described in the background section, in the implementation of OBB technology, a coating process is often used to form a carrier film to connect the solder ribbon to the gridless solar cell. To ensure the coating effect and better enhance the performance of the carrier film, the coating process usually involves an electron beam irradiation pre-crosslinking step. This step can improve the creep characteristics of the carrier film, ensure its dimensional stability at high temperatures, and its shape retention during the welding process. However, the existing carrier film composition faces the problem of low efficiency in the pre-crosslinking process using electron beam irradiation. That is, at the same production speed, a higher irradiation dose is required to achieve the ideal crosslinking level of the carrier film. This not only prolongs the production cycle and increases energy consumption, but also directly drives up the production cost of OBB carrier films.

[0026] To address the aforementioned problems, this invention provides a carrier membrane composition comprising: a first polyolefin resin and a modified polyolefin resin; wherein the modified polyolefin resin contains carbon-carbon double bonds, and the average functionality of the carbon-carbon double bonds in the modified polyolefin resin is 5–100; the modified polyolefin resin is obtained by graft copolymerization of a second polyolefin resin and an active monomer containing carbon-carbon double bonds. This carrier membrane composition mainly consists of the two key components mentioned above, which play unique roles in the performance and function of the carrier membrane, and their interaction significantly affects the overall performance of the carrier membrane.

[0027] Specifically, the first polyolefin resin, as one of the basic materials of the carrier film, provides the basic physical and mechanical properties for the formation of the carrier film, such as tensile strength, flexibility, and heat resistance. The modified polyolefin resin is obtained by graft copolymerization of the second polyolefin resin with an active monomer containing carbon-carbon double bonds. This graft copolymerization process introduces carbon-carbon double bond functional groups into the molecular chain of the second polyolefin resin, significantly increasing the content of chemically reactive sites and enhancing the resin's reactivity. This allows the carrier film composition to achieve sufficient cross-linking between resins at a lower irradiation dose, reducing the requirements for electron beam current intensity and electron radiation, lowering production costs, and improving production efficiency. Through the synergistic effect of the first and modified polyolefin resins, the formed carrier film not only possesses better temporary adhesion, thermal stability, and mechanical properties—the fundamental properties of a carrier film—but also achieves sufficient cross-linking at a lower irradiation dose. The above operations effectively reduce the requirements for electron beam current intensity during the carrier film irradiation process, lower production costs, shorten the production cycle, and improve production efficiency. The reasons for these superior effects may include the following: First, both are polyolefin resins, and their similar chemical structures contribute to their good compatibility, allowing them to better leverage their respective advantages and further improve the stability of the prepared carrier membrane. Second, the first polyolefin resin provides the carrier membrane with a certain degree of rigidity and stability, while the modified polyolefin resin enhances the crosslinking and adhesion of the carrier membrane through its special activity. This synergistic effect allows the membrane to maintain good physical properties while achieving higher chemical reactivity and functionality, thereby optimizing the overall performance of the formed carrier membrane, such as higher weather resistance, better adhesion, and better dimensional stability, further improving the overall performance of the carrier membrane.

[0028] Furthermore, the modified polyolefin resin contains carbon-carbon double bonds, and the average functionality of these carbon-carbon double bonds in the modified polyolefin resin is 5–100. Average functionality refers to the average number of functional groups in a substance; for modified polyolefin resins, the average functionality reflects the average number of carbon-carbon double bonds in the resin. In this application, controlling the average functionality of the carbon-carbon double bonds in the modified polyolefin resin within the above-mentioned range further ensures that the resin has sufficient reactivity to improve the electron beam irradiation crosslinking efficiency, while maintaining the material's mechanical strength, dimensional stability, adhesion, and weather resistance. Firstly, carbon-carbon double bonds, as reaction sites, can rapidly crosslink under electron beam irradiation to form a three-dimensional network structure. Controlling the average functionality of the modified polyolefin resin within the above-mentioned range means controlling the number of crosslinkable double bonds in the resin, thereby enabling the carrier film composition to achieve sufficient crosslinking with lower beam current intensity and irradiation dose, significantly improving production efficiency and reducing production costs. Secondly, modified polyolefin resins with a certain double bond content can form a denser cross-linking network. This not only improves the mechanical strength and dimensional stability of the material but also enhances its heat resistance and weather resistance, allowing it to maintain good performance under complex and changing environmental conditions. Thirdly, the presence of carbon-carbon double bonds provides additional reactivity to the material, helping to further improve the adhesion performance of the carrier film, resulting in a tighter interfacial contact between the carrier film and the battery cell, improving peel strength, and ensuring the long-term reliability of the module. Furthermore, the above limitations help avoid excessive cross-linking of the carrier film composition, thereby preventing the material from becoming brittle due to excessive cross-linking, which could reduce its flexibility and processing performance. In summary, by controlling the average functionality of carbon-carbon double bonds in the modified polyolefin resin within the above-mentioned range, this application further ensures that the resin has sufficient reactivity to improve the electron beam irradiation cross-linking efficiency, while maintaining the mechanical strength, dimensional stability, adhesion, and weather resistance of the carrier film.

[0029] In summary, in the carrier film composition, the first polyolefin resin provides the basic physical properties for the formation of the carrier film, while the modified polyolefin resin enhances the reactivity and functional properties between the components by introducing carbon-carbon double bond functional groups. Through the complex synergistic mechanism between these two components, the crosslinking efficiency, mechanical properties, thermal stability, and durability of the carrier film are optimized, making it an ideal carrier film material for photovoltaic modules, especially suitable for the requirements of busbar-less (OBB) technology. This improves photoelectric conversion efficiency, reduces production costs, and enhances module reliability.

[0030] In a preferred embodiment, the grafting rate of the modified polyolefin resin is 0.5% to 10%. The grafting rate reflects the proportion of active monomers grafted onto the second polyolefin resin. Controlling the grafting rate of the modified polyolefin resin within the above range is beneficial for improving the efficiency of the modified polyolefin resin in the crosslinking reaction and also allows the formed carrier film to have superior appearance properties, thereby further improving the various properties of the carrier film formed from the carrier film composition. Preferably, the grafting rate of the modified polyolefin resin is 1% to 5%; controlling the grafting rate of the modified polyolefin resin within the above preferred range yields even better results.

[0031] Preferably, the active monomer is a first active monomer and / or a second active monomer; wherein the first active monomer contains at least two carbon-carbon double bonds and a carbonyl group, and the second active monomer contains a carbon-carbon double bond and at least one of the following groups: epoxy group, carbonyl group, carboxyl group, hydroxyl group, amide group, or amino group. Introducing the first active monomer containing carbon-carbon double bonds and a carbonyl group during the formation of the modified polyolefin resin is beneficial for further improving the crosslinking reactivity of the carrier film composition and accelerating the crosslinking process. This allows for the rapid formation of a stable crosslinked network at a lower irradiation dose, which is beneficial for further reducing the curing time and production cost of the carrier film. By controlling the number of carbon-carbon double bonds in the first active monomer within the above-mentioned range, during the modification of the second polyolefin resin, a portion of the carbon-carbon double bonds are consumed during the modification process, while the remaining unreacted carbon-carbon double bonds in the first active monomer will still exist on the modified resin molecular chain, thereby further improving the effect of the modified polyolefin resin in the carrier film composition on the efficiency of irradiation crosslinking. In addition to carbon-carbon double bonds, the second active monomer also contains functional groups such as epoxy, carbonyl, carboxyl, hydroxyl, amide, or amino groups. These functional groups enhance the resin's adhesion and compatibility with other materials. Particularly during surface bonding with HJT solar cells (heterojunction solar cells), they further improve the adhesion and peel strength of the carrier film, ensuring good contact between the HJT solar cell and the carrier film, thereby further optimizing the photoelectric conversion efficiency of the gridless solar cell. Both monomers mentioned above can improve the crosslinking reactivity of the carrier film composition, accelerate the crosslinking process, and achieve the formation of a stable crosslinked network at a lower irradiation dose, reducing the curing time and production cost of the carrier film composition.

[0032] Preferably, the active monomer is a blend of a first active monomer and a second active monomer; preferably, the weight ratio of the first active monomer to the second active monomer is (50-100):(1-50). The blending of the first and second active monomers not only accelerates the cross-linking reaction between the carrier film compositions, but the functional groups (such as amino and hydroxyl groups) of the second active monomer can further enhance the adhesion to the HJT solar cell. Under the dual synergistic effect of promoting cross-linking and adhesion, the excellent performance of the carrier film in photovoltaic modules is further ensured, while also further optimizing material performance and cost-effectiveness. In particular, controlling the weight ratio between the two within the above range can better exert the above-mentioned effects, which is beneficial to further improving the efficiency of carrier film formation and further improving the overall performance of the carrier film. Preferably, the first active monomer is selected from one or more of tripropylene isocyanurate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, tripropylene glycol diacrylate, and triallyl cyanurate; preferably, the second active monomer is selected from one or more of glycidyl methacrylate, dimethyl maleate, methacrylic acid, hydroxyethyl methacrylate, and acrylamide. Selecting the first and second active monomers mentioned above can better improve the efficiency of forming the carrier membrane and further improve the overall performance of the carrier membrane.

[0033] Preferably, the graft copolymerization reaction employs at least one of melt extrusion, solution copolymerization, suspension copolymerization, and emulsion copolymerization; preferably, the graft copolymerization reaction employs melt extrusion; preferably, the melt extrusion rotation speed is 100–400 rpm. Melt extrusion, solution copolymerization, suspension copolymerization, and emulsion copolymerization can all achieve graft modification of the second polyolefin resin and the active monomer. In particular, melt extrusion, due to its advantages of continuity, high efficiency, and ease of large-scale production, has become the preferred graft copolymerization reaction method. Controlling the melt extrusion rotation speed within the above-mentioned range can further ensure thorough mixing of the reactants, promote the uniformity of the graft reaction, and improve the quality and stability of the modified resin. Preferably, the graft copolymerization reaction temperature is 90–180°C. Controlling the temperature of the graft copolymerization reaction within the above range allows the second polyolefin resin and the active monomer containing carbon-carbon double bonds to undergo a better graft copolymerization reaction, ensuring that the grafted active monomer is evenly distributed in the second polyolefin resin. This improves the uniformity and grafting rate of the modified polyolefin resin, while also further enhancing the efficiency and stability of the formed carrier film.

[0034] In a preferred embodiment, the first polyolefin resin and the second polyolefin resin are each independently selected from one or more of polyethylene, polypropylene, ethylene-octene copolymer, ethylene-butene copolymer, and ethylene-hexene copolymer; preferably, the weight-average molecular weight of the first polyolefin resin is 25,000 to 500,000 g / mol; preferably, the weight-average molecular weight of the second polyolefin resin is 50,000 to 500,000 g / mol. Selecting the above-mentioned first and second polyolefin resins, and controlling their weight-average molecular weights within the aforementioned ranges, allows for better utilization of both resins, resulting in a more efficient and lower-cost carrier film. This enables the carrier film to achieve optimal performance in gridless photovoltaic modules, further optimizing the production cost and efficiency of gridless photovoltaic cells.

[0035] In a preferred embodiment, the carrier film composition comprises, by weight, 1-90 parts of the first polyolefin resin and 10-100 parts of the modified polyolefin resin. Controlling the addition ratio of the first polyolefin resin and the modified polyolefin resin in the carrier film composition within the above range allows for better crosslinking of the carrier film composition. Preferably, the carrier film composition further includes an electron irradiation crosslinking agent and / or a stabilizer. The electron irradiation crosslinking agent acts as a catalyst during electron beam irradiation, promoting the crosslinking reaction between the molecules of the first polyolefin resin and the modified polyolefin resin. The synergistic effect of the electron irradiation crosslinking agent and the active functional groups in the modified polyolefin resin accelerates the crosslinking process between components, achieving sufficient crosslinking at a lower irradiation dose, reducing dependence on high irradiation doses, saving energy, and lowering production costs. Simultaneously, the use of the electron irradiation crosslinking agent also increases the weather resistance and chemical corrosion resistance of the film, playing an important role in extending the lifespan of photovoltaic modules. Stabilizers can further protect the primary polyolefin resin and the modified polyolefin resin from thermal degradation and oxidation, especially under high-temperature processing conditions, and help to further improve the structural integrity and reactivity of the resulting modified polyolefin resin. Using electron irradiation crosslinking agents and / or stabilizers as components of the carrier membrane composition can further improve the formation efficiency of the carrier membrane and also further enhance its performance.

[0036] Preferably, by weight, the carrier film composition comprises 50-90 parts of a first polyolefin resin, 10-50 parts of a modified polyolefin resin, 0-5.0 parts of an electron irradiation crosslinking aid, and 0-2.0 parts of an antioxidant, wherein the contents of the electron irradiation crosslinking aid and the stabilizer are not simultaneously zero. In the carrier film composition, the first polyolefin resin lays the foundation for the basic physical properties of the carrier film, the modified polyolefin resin optimizes the crosslinking process by introducing active groups, the electron irradiation crosslinking aid catalyzes the crosslinking reaction, and the stabilizer protects the carrier film from environmental damage. The synergistic effect among these components not only ensures the basic properties of the carrier film, such as temporary adhesion, thermal stability, and mechanical properties, but also further reduces the electron beam current required for pre-crosslinking of the carrier film components, significantly improving production efficiency and effectively controlling production costs. Controlling the proportions of each component in the carrier film composition within the above-mentioned range yields even better results, better balancing the physical properties, chemical reactivity, and long-term stability of the carrier film, providing strong support for the high efficiency, reliability, and economy of photovoltaic modules. Preferably, in the carrier membrane composition, the weight ratio of the first polyolefin resin to the modified polyolefin resin is (1-9):1. Controlling the weight ratio of the first polyolefin resin to the modified polyolefin resin in the carrier membrane composition within the above range can better leverage the synergistic effect of the first polyolefin resin and the modified polyolefin resin, which is beneficial for further reducing the electron beam current required during the pre-crosslinking of the carrier membrane components, significantly improving production efficiency, effectively controlling production costs, and further improving the basic properties of the carrier membrane, such as temporary adhesion, thermal stability, and mechanical properties.

[0037] Preferably, the electron irradiation crosslinking aid is selected from one or more of the following: tripropylene isocyanurate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, triallyl cyanurate, tripropylene glycol diacrylate, pentaerythritol triallyl ether, and pentaerythritol allyl ether; preferably, the stabilizer is selected from one or more of the following: bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, bis(1-octoxy-2,2,6,6-tetramethyl-4-piperidinyl) sebacate, poly(4-hydroxy-2,2,6,6-tetramethyl-1-piperidinol) ester, 2-hydroxy-4-n-octoxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-2'-carboxybenzophenone, and 2,4-dihydroxybenzophenone. Using the aforementioned specific electron irradiation crosslinking aids and stabilizers as components of the carrier membrane composition can improve the crosslinking efficiency and crosslinking effect of the carrier membrane.

[0038] In a preferred embodiment, the raw materials for the graft copolymerization reaction include a second polyolefin resin, an active monomer, an initiator, and an antioxidant. The second polyolefin resin serves as the basis for grafting the active monomer, providing the main polymer backbone for the modified polyolefin resin. The addition of the active monomer involves a graft reaction between its carbon-carbon double bond functional groups and the resin, introducing unsaturated bonds or functional groups, thereby improving the crosslinking ability and adhesion to HJT solar cells of the modified resin. The initiator decomposes during the graft copolymerization reaction to generate free radicals, which rearrange to create active sites on the polymer molecular chain, thus stimulating the active monomer reaction for better crosslinking. The antioxidant inhibits the oxidative degradation of the second polyolefin resin caused by oxygen during processing and use, especially under high-temperature processing conditions, contributing to further improving the structural integrity and reactivity of the resulting modified polyolefin resin. The synergistic effect of these components allows the graft copolymerization reaction to proceed more effectively, resulting in a modified polyolefin resin with greater crosslinking activity.

[0039] Preferably, by weight, the raw materials for the graft copolymerization reaction include 100 parts of the second polyolefin resin, 1.0 to 15 parts of the active monomer, 0.05 to 2 parts of the initiator, and 0.05 to 0.5 parts of the antioxidant. Controlling the proportions of each component in the raw materials for the graft copolymerization reaction within the above range can improve the graft copolymerization reaction, further enhance the reactivity of the modified polyolefin resin, and thus better improve the performance of the prepared carrier membrane and reduce the preparation cost of the carrier membrane. Preferably, the electron irradiation crosslinking aid is selected from one or more of tripropylene isocyanurate, trimethylolpropane triacrylate, and trimethylolpropane trimethacrylate; preferably, the initiator is selected from 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, 1,1-(bis(tert-butylperoxy)3,3,5-trimethylcyclohexane), tert-butyl peroxide, triphenylmethane-4,4',4”-triisocyanate, dicumyl peroxide, bis(2-tert-butylperoxyisopropyl)benzene, tert-butyl isopropyl peroxide, tert-amyl peroxide, di-tert-amyl peroxide, tert-butyl peroxide-2-ethylhexanoate, tert-butyl peroxide-3,5,5-trimethylhexanoate, di(4-chlorobenzoyl)peroxide, di(2,4-dichloro) The antioxidant is selected from one or more of the following: benzyl peroxide, di(4-methylphenyl) peroxide, n-butyl-4,4-di(tert-butylperoxy)valerate, ethyl-3,3-di(tert-butylperoxy)butyrate, and tert-butylperoxy-2-ethylhexyl carbonate; preferably, the antioxidant is selected from one or more of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate, and tris(2,4-di-tert-butylphenyl)phosphite. The above-mentioned specific electron irradiation crosslinking aid, antioxidant, initiator, and stabilizer provide even better results.

[0040] According to a second aspect of the present invention, a carrier membrane is also provided, which is prepared from the above-described carrier membrane composition.

[0041] According to a third aspect of the present invention, a method for preparing the above-mentioned carrier film is also provided. This method includes the following steps: mixing raw materials comprising a second polyolefin resin and an active monomer, followed by a graft copolymerization reaction to obtain a modified polyolefin resin; mixing raw materials comprising a first polyolefin resin and the modified polyolefin resin, followed by extrusion casting at a first temperature to obtain a cast film; and curing the cast film by electron irradiation to obtain the carrier film. The above-mentioned preparation method has advantages such as fewer process steps, simpler operation, and lower cost, thereby facilitating a better improvement in the crosslinking rate of the carrier film formation and the performance of the formed carrier film, and further reducing preparation costs.

[0042] In a preferred embodiment, the method for preparing the carrier film includes the following steps: mixing a second polyolefin resin, an active monomer, an initiator, and an antioxidant, followed by a graft copolymerization reaction to obtain a modified polyolefin resin; mixing a first polyolefin resin, a modified polyolefin resin, an electron irradiation crosslinking aid, and a stabilizer, followed by extrusion casting at a first temperature to obtain a cast film; and curing the cast film by electron irradiation to obtain the carrier film. Adding an initiator and a stabilizer during the preparation of the modified polyolefin resin improves the crosslinking rate and performance of the formed carrier film.

[0043] In a preferred embodiment, the first temperature is 75–200°C; preferably, the thickness of the carrier membrane is 0.01–0.5 mm; preferably, the graft copolymerization reaction temperature is 90–180°C; preferably, the electron irradiation dose is <200 KGy; preferably, the extrusion method is single-screw extrusion or twin-screw extrusion. Controlling the parameters in the carrier membrane preparation process within the above ranges is beneficial to further improve the preparation efficiency.

[0044] According to a fourth aspect of the present invention, a gridless photovoltaic cell is also provided, comprising the above-described carrier film; or the gridless photovoltaic cell comprising the carrier film prepared by the above-described preparation method. The carrier film prepared using the above formulation or the above-described preparation method exhibits better application performance in practical applications.

[0045] The present application will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.

[0046] The grade information of the polyolefin resins used in the examples and comparative examples is as follows:

[0047] Polyethylene resin with a weight average molecular weight of 100,000 g / mol: 2426H (Sinopec Corporation); Ethylene-octene copolymer resin with a weight average molecular weight of 150,000 g / mol: 8480 (Dow Chemical Company); Polyethylene resin with a weight average molecular weight of 200,000 g / mol: 2426K (Sinopec Corporation); Polyethylene resin with a weight average molecular weight of 500,000 g / mol: HD6070EA (Sinopec Yangzi Petrochemical Co., Ltd.); Polyethylene resin with a weight average molecular weight of 50,000 g / mol... Polyethylene resin: 951-025 (China Petroleum & Chemical Corporation); Ethylene-octene copolymer resin with a weight average molecular weight of 500,000 g / mol: HM7387 (Dow Chemical Company); Ethylene-octene copolymer resin with a weight average molecular weight of 50,000 g / mol: 11527 (Dow Chemical Company); Polyethylene resin with a weight average molecular weight of 25,000 g / mol: 8730L (SK Chemicals, Korea); Polyethylene resin with a weight average molecular weight of 150,000 g / mol: 2426K (China Petroleum & Chemical Corporation).

[0048] Example 1

[0049] 100 parts of a second polyolefin resin (polyethylene) with a weight-average molecular weight of 100,000 g / mol, 4 parts of a first active monomer (trimethylolpropane triacrylate), 0.2 parts of an initiator (2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane), and 0.05 parts of an antioxidant (pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]) were mixed and subjected to graft copolymerization at a reaction temperature of 180°C and a rotation speed of 100 rpm. The mixture was then melt-extruded by a twin-screw extruder to obtain a modified polyolefin resin. The grafting rate of the obtained modified polyolefin resin was 2.5%, and the average functionality of the carbon-carbon double bonds in the modified polyolefin resin was 15.

[0050] Eighty parts of a first polyolefin resin (ethylene-octene copolymer) with a weight-average molecular weight of 150,000 g / mol, 20 parts of the modified polyolefin resin obtained above, 1 part of an electron irradiation crosslinking aid (tripropylene isocyanurate), and 0.1 part of a stabilizer (bis(1-octoxy-2,2,6,6-tetramethyl-4-piperidinyl) sebacate) were mixed and extruded at 150°C to obtain a cast film with a thickness of 0.01 mm. The cast film was then cured by electron irradiation to obtain a carrier film. When the irradiation dose was set to 100 kGy, the degree of crosslinking of the prepared carrier film was 22.3%.

[0051] Example 2

[0052] 100 parts of a second polyolefin resin (polyethylene) with a weight-average molecular weight of 200,000 g / mol, 1 part of a first active monomer (trimethylolpropane triacrylate), 0.05 parts of an initiator (2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane), and 0.05 parts of an antioxidant (pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]) were mixed and subjected to graft copolymerization at a reaction temperature of 160℃ and a rotation speed of 100 rpm. The mixture was then melt-extruded by a twin-screw extruder to obtain a modified polyolefin resin. The grafting rate of the obtained modified polyolefin resin was 0.5%, and the average functionality of the carbon-carbon double bonds in the modified polyolefin resin was 5.

[0053] Eighty parts of a first polyolefin resin (ethylene-octene copolymer) with a weight-average molecular weight of 150,000 g / mol, 20 parts of the modified polyolefin resin obtained above, 1 part of an electron irradiation crosslinking aid (tripropylene isocyanurate), and 0.1 part of a stabilizer (bis(1-octoxy-2,2,6,6-tetramethyl-4-piperidinyl) sebacate) were mixed and extruded at 150°C to obtain a cast film with a thickness of 0.01 mm. The cast film was then cured by electron irradiation to obtain a carrier film. When the irradiation dose was set to 100 kGy, the degree of crosslinking of the prepared carrier film was 17.7%.

[0054] Example 3

[0055] 100 parts of a second polyolefin resin (polyethylene) with a weight-average molecular weight of 500,000 g / mol, 7 parts of a first active monomer (trimethylolpropane triacrylate), 1.0 part of an initiator (2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane), and 0.1 part of an antioxidant (pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]) were mixed and subjected to graft copolymerization at a reaction temperature of 190℃ and a rotation speed of 100 rpm. The mixture was then melt-extruded by a twin-screw extruder to obtain a modified polyolefin resin. The grafting rate of the obtained modified polyolefin resin was 5%, and the average functionality of the carbon-carbon double bonds in the modified polyolefin resin was 100.

[0056] Eighty parts of a first polyolefin resin (ethylene-octene copolymer) with a weight-average molecular weight of 150,000 g / mol, 20 parts of the modified polyolefin resin obtained above, 1 part of an electron irradiation crosslinking aid (tripropylene isocyanurate), and 0.1 part of a stabilizer (bis(1-octoxy-2,2,6,6-tetramethyl-4-piperidinyl) sebacate) were mixed and extruded at 180°C to obtain a cast film with a thickness of 0.01 mm. The cast film was then cured by electron irradiation to obtain a carrier film. When the irradiation dose was set to 100 kGy, the degree of crosslinking of the prepared carrier film was 47.7%.

[0057] Example 4

[0058] 100 parts of a second polyolefin resin (polyethylene) with a weight-average molecular weight of 50,000 g / mol, 12.0 parts of a first active monomer (trimethylolpropane triacrylate), 1 part of an initiator (2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane), and 0.1 parts of an antioxidant (pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]) were mixed and subjected to graft copolymerization at a reaction temperature of 180℃ and a rotation speed of 100 rpm. The mixture was then melt-extruded by a twin-screw extruder to obtain a modified polyolefin resin. The grafting rate of the obtained modified polyolefin resin was 10%, and the average functionality of the carbon-carbon double bonds in the modified polyolefin resin was 30.

[0059] Eighty parts of a first polyolefin resin (ethylene-octene copolymer) with a weight-average molecular weight of 150,000 g / mol, 20 parts of the modified polyolefin resin obtained above, 1 part of an electron irradiation crosslinking aid (tripropylene isocyanurate), and 0.1 part of a stabilizer (bis(1-octoxy-2,2,6,6-tetramethyl-4-piperidinyl) sebacate) were mixed and extruded at 150 °C to obtain a cast film with a thickness of 0.01 mm. The cast film was then cured by electron irradiation to obtain a carrier film. When the irradiation dose was set to 100 kGy, the degree of crosslinking of the prepared carrier film was 54.8%.

[0060] Example 5

[0061] 100 parts of a second polyolefin resin (polyethylene) with a weight-average molecular weight of 200,000 g / mol, 2 parts of a first active monomer (trimethylolpropane triacrylate), 0.1 parts of an initiator (2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane), and 0.05 parts of an antioxidant (pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]) were mixed and subjected to graft copolymerization at a reaction temperature of 150°C and a rotation speed of 100 rpm. The mixture was then melt-extruded by a twin-screw extruder to obtain a modified polyolefin resin. The grafting rate of the obtained modified polyolefin resin was 1%, and the average functionality of the carbon-carbon double bonds in the modified polyolefin resin was 10.

[0062] Eighty parts of a first polyolefin resin (ethylene-octene copolymer) with a weight-average molecular weight of 150,000 g / mol, 20 parts of the modified polyolefin resin obtained above, 1 part of an electron irradiation crosslinking aid (tripropylene isocyanurate), and 0.1 part of a stabilizer (bis(1-octoxy-2,2,6,6-tetramethyl-4-piperidinyl) sebacate) were mixed and extruded at 150°C to obtain a cast film with a thickness of 0.01 mm. The cast film was then cured by electron irradiation to obtain a carrier film. When the irradiation dose was set to 100 kGy, the degree of crosslinking of the prepared carrier film was 20.0%.

[0063] Example 6

[0064] 100 parts of a second polyolefin resin (ethylene-octene copolymer) with a weight average molecular weight of 500,000 g / mol, 3 parts of a first active monomer (trimethylolpropane triacrylate), 0.2 parts of an initiator (2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane), and 0.05 parts of an antioxidant (pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]) were mixed and subjected to graft copolymerization at a reaction temperature of 180℃ and a rotation speed of 100 rpm. The mixture was then melt-extruded by a twin-screw extruder to obtain a modified polyolefin resin. The grafting rate of the obtained modified polyolefin resin was 1.8%, and the average functionality of the carbon-carbon double bonds in the modified polyolefin resin was 50.

[0065] Eighty parts of a first polyolefin resin (polyethylene) with a weight-average molecular weight of 500,000 g / mol, 20 parts of the modified polyolefin resin obtained above, 1 part of an electron irradiation crosslinking aid (tripropylene isocyanurate), and 0.1 part of a stabilizer (bis(1-octyloxy-2,2,6,6-tetramethyl-4-piperidinyl) sebacate) were mixed and extruded at 150°C to obtain a cast film with a thickness of 0.01 mm. The cast film was then cured by electron irradiation to obtain a carrier film. When the irradiation dose was set to 100 kGy, the degree of crosslinking of the prepared carrier film was 31.9%.

[0066] Example 7

[0067] 100 parts of a second polyolefin resin (ethylene-octene copolymer) with a weight-average molecular weight of 50,000 g / mol, 6 parts of a first active monomer (trimethylolpropane triacrylate), 0.8 parts of an initiator (2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane), and 0.1 parts of an antioxidant (pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]) were mixed and subjected to graft copolymerization at a reaction temperature of 180℃ and a rotation speed of 100 rpm. The mixture was then melt-extruded by a twin-screw extruder to obtain a modified polyolefin resin. The grafting rate of the obtained modified polyolefin resin was 3.5%, and the average functionality of the carbon-carbon double bonds in the modified polyolefin resin was 10.

[0068] Eighty parts of a first polyolefin resin (polyethylene) with a weight-average molecular weight of 25,000 g / mol, 20 parts of the modified polyolefin resin obtained above, 1 part of an electron irradiation crosslinking aid (tripropylene isocyanurate), and 0.1 part of a stabilizer (bis(1-octyloxy-2,2,6,6-tetramethyl-4-piperidinyl) sebacate) were mixed and extruded at 150 °C to obtain a cast film with a thickness of 0.01 mm. The cast film was then cured by electron irradiation to obtain a carrier film. When the irradiation dose was set to 100 kGy, the degree of crosslinking of the prepared carrier film was 24.7%.

[0069] Example 8

[0070] 100 parts of a second polyolefin resin (polyethylene) with a weight-average molecular weight of 150,000 g / mol, 1.0 part of a first active monomer (trimethylolpropane triacrylate), 0.05 parts of an initiator (tert-butyl peroxide), and 0.05 parts of an antioxidant (pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate)) were mixed and subjected to graft copolymerization at a reaction temperature of 180°C and a rotation speed of 100 rpm. The mixture was then melt-extruded by a twin-screw extruder to obtain a modified polyolefin resin. The grafting rate of the obtained modified polyolefin resin was 0.5%, and the average functionality of the carbon-carbon double bonds in the modified polyolefin resin was 5.

[0071] Eighty parts of a first polyolefin resin (ethylene-octene copolymer) with a weight-average molecular weight of 150,000 g / mol, 20 parts of the modified polyolefin resin obtained above, 1 part of an electron irradiation crosslinking aid (tripropylene isocyanurate), and 0.1 part of a stabilizer (bis(1-octoxy-2,2,6,6-tetramethyl-4-piperidinyl) sebacate) were mixed and extruded at 150°C to obtain a cast film with a thickness of 0.01 mm. The cast film was then cured by electron irradiation to obtain a carrier film. When the irradiation dose was set to 100 kGy, the degree of crosslinking of the prepared carrier film was 19.3%.

[0072] Example 9

[0073] A graft copolymerization reaction was carried out at a reaction temperature of 180°C and a rotation speed of 100 rpm. The mixture was then subjected to a graft copolymerization reaction and subjected to a twin-screw melt extrusion to obtain a modified polyolefin resin. The grafting rate of the obtained modified polyolefin resin was 10%, and the average functionality of the carbon-carbon double bonds in the modified polyolefin resin was 50.

[0074] Eighty parts of a first polyolefin resin (ethylene-octene copolymer) with a weight-average molecular weight of 150,000 g / mol, 20 parts of the modified polyolefin resin obtained above, 1 part of an electron irradiation crosslinking aid (tripropylene isocyanurate), and 0.1 part of a stabilizer (bis(1-octoxy-2,2,6,6-tetramethyl-4-piperidinyl) sebacate) were mixed and extruded at 150 °C to obtain a cast film with a thickness of 0.01 mm. The cast film was then cured by electron irradiation to obtain a carrier film. When the irradiation dose was set to 100 kGy, the degree of crosslinking of the prepared carrier film was 48.5%.

[0075] Example 10

[0076] 100 parts of a second polyolefin resin (polyethylene) with a weight-average molecular weight of 100,000 g / mol, 4 parts of a first active monomer (trimethylolpropane triacrylate), 0.2 parts of an initiator (2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane), and 0.05 parts of an antioxidant (pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]) were mixed and subjected to graft copolymerization at a reaction temperature of 180°C and a rotation speed of 100 rpm. The mixture was then melt-extruded by a twin-screw extruder to obtain a modified polyolefin resin. The grafting rate of the obtained modified polyolefin resin was 2.5%, and the average functionality of the carbon-carbon double bonds in the modified polyolefin resin was 15.

[0077] One part of a first polyolefin resin (ethylene-octene copolymer) with a weight-average molecular weight of 150,000 g / mol, 100 parts of the modified polyolefin resin obtained above, 5 parts of an electron irradiation crosslinking aid (tripropylene glycol diacrylate), and 2 parts of a stabilizer (bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate) were mixed and extruded at 175°C to obtain a cast film with a thickness of 0.01 mm. The cast film was then cured by electron irradiation to obtain a carrier film. When the irradiation dose was set to 100 kGy, the crosslinking degree of the prepared carrier film was 85.3%.

[0078] Example 11

[0079] 100 parts of a second polyolefin resin (polyethylene) with a weight-average molecular weight of 100,000 g / mol, 4 parts of a first active monomer (trimethylolpropane triacrylate), 0.2 parts of an initiator (2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane), and 0.05 parts of an antioxidant (pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]) were mixed and subjected to graft copolymerization at a reaction temperature of 180°C and a rotation speed of 100 rpm. The mixture was then melt-extruded by a twin-screw extruder to obtain a modified polyolefin resin. The grafting rate of the obtained modified polyolefin resin was 2.5%, and the average functionality of the carbon-carbon double bonds in the modified polyolefin resin was 15.

[0080] Ninety parts of a first polyolefin resin (ethylene-octene copolymer) with a weight-average molecular weight of 150,000 g / mol, ten parts of the modified polyolefin resin obtained above, three parts of an electron irradiation crosslinking aid (trimethylolpropane trimethacrylate), and two parts of a stabilizer (2-hydroxy-4-n-octyloxybenzophenone) were mixed and extruded at 200°C to obtain a cast film with a thickness of 0.01 mm. The cast film was then cured by electron irradiation to obtain a carrier film. When the irradiation dose was set to 100 kGy, the degree of crosslinking of the prepared carrier film was 16.5%.

[0081] Example 12

[0082] 100 parts of a second polyolefin resin (polyethylene) with a weight-average molecular weight of 100,000 g / mol, 4 parts of a first active monomer (trimethylolpropane triacrylate), 0.2 parts of an initiator (2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane), and 0.05 parts of an antioxidant (pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]) were mixed and subjected to graft copolymerization at a reaction temperature of 180°C and a rotation speed of 100 rpm. The mixture was then melt-extruded by a twin-screw extruder to obtain a modified polyolefin resin. The grafting rate of the obtained modified polyolefin resin was 2.5%, and the average functionality of the carbon-carbon double bonds in the modified polyolefin resin was 15.

[0083] 50 parts of a first polyolefin resin (ethylene-octene copolymer) with a weight-average molecular weight of 150,000 g / mol, 10 parts of the modified polyolefin resin obtained above, 3 parts of an electron irradiation crosslinking aid (trimethylolpropane trimethacrylate), and 2 parts of a stabilizer (2-hydroxy-4-n-octyloxybenzophenone) were mixed and extruded at 200°C to obtain a cast film with a thickness of 0.01 mm. The cast film was then cured by electron irradiation to obtain a carrier film. When the irradiation dose was set to 100 kGy, the degree of crosslinking of the prepared carrier film was 31.4%.

[0084] Example 13

[0085] 100 parts of a second polyolefin resin (polyethylene) with a weight-average molecular weight of 100,000 g / mol, 4 parts of a first active monomer (trimethylolpropane triacrylate), 0.2 parts of an initiator (2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane), and 0.05 parts of an antioxidant (pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]) were mixed and subjected to graft copolymerization at a reaction temperature of 180°C and a rotation speed of 100 rpm. The mixture was then melt-extruded by a twin-screw extruder to obtain a modified polyolefin resin. The grafting rate of the obtained modified polyolefin resin was 2.5%, and the average functionality of the carbon-carbon double bonds in the modified polyolefin resin was 15.

[0086] Ninety parts of a first polyolefin resin (ethylene-octene copolymer) with a weight-average molecular weight of 150,000 g / mol, 50 parts of the modified polyolefin resin obtained above, 3 parts of an electron irradiation crosslinking aid (trimethylolpropane trimethacrylate), and 2 parts of a stabilizer (2-hydroxy-4-n-octyloxybenzophenone) were mixed and extruded at 200°C to obtain a cast film with a thickness of 0.01 mm. The cast film was then cured by electron irradiation to obtain a carrier film. When the irradiation dose was set to 100 kGy, the degree of crosslinking of the prepared carrier film was 45.7%.

[0087] Example 14

[0088] 100 parts of a second polyolefin resin (polyethylene) with a weight-average molecular weight of 100,000 g / mol, 4 parts of a first active monomer (trimethylolpropane triacrylate), 0.2 parts of an initiator (2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane), and 0.05 parts of an antioxidant (pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]) were mixed and subjected to graft copolymerization at a reaction temperature of 90°C and a rotation speed of 400 rpm. The mixture was then melt-extruded by a twin-screw extruder to obtain a modified polyolefin resin. The grafting rate of the obtained modified polyolefin resin was 2.5%, and the average functionality of the carbon-carbon double bonds in the modified polyolefin resin was 15.

[0089] 90 parts of a first polyolefin resin (ethylene-octene copolymer) with a weight-average molecular weight of 150,000 g / mol, 10 parts of the modified polyolefin resin obtained above, and 0.1 parts of a stabilizer (bis(1-octoxy-2,2,6,6-tetramethyl-4-piperidinyl) sebacate) were mixed and extruded at 150°C to obtain a cast film with a thickness of 0.01 mm. The cast film was then cured by electron irradiation to obtain a carrier film. When the irradiation dose was set to 100 kGy, the crosslinking degree of the prepared carrier film was 18.5%.

[0090] Example 15

[0091] 100 parts of a second polyolefin resin (polyethylene) with a weight-average molecular weight of 100,000 g / mol, 4 parts of a first active monomer (trimethylolpropane triacrylate), 0.2 parts of an initiator (2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane), and 0.05 parts of an antioxidant (pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]) were mixed and subjected to graft copolymerization at a reaction temperature of 180°C and a rotation speed of 100 rpm. The mixture was then melt-extruded by a twin-screw extruder to obtain a modified polyolefin resin. The grafting rate of the obtained modified polyolefin resin was 2.5%, and the average functionality of the carbon-carbon double bonds in the modified polyolefin resin was 15.

[0092] Ninety parts of a first polyolefin resin (ethylene-octene copolymer) with a weight-average molecular weight of 150,000 g / mol, ten parts of the modified polyolefin resin obtained above, and one part of an electron irradiation crosslinking aid (tripropylene isocyanurate) were mixed and extruded at 150°C to obtain a cast film with a thickness of 0.01 mm. The cast film was then cured by electron irradiation to obtain a carrier film. When the irradiation dose was set to 100 kGy, the degree of crosslinking of the prepared carrier film was 22.6%.

[0093] Example 16

[0094] 100 parts of a second polyolefin resin (polyethylene) with a weight-average molecular weight of 100,000 g / mol, 4 parts of a first active monomer (trimethylolpropane triacrylate), 0.2 parts of an initiator (2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane), and 0.05 parts of an antioxidant (pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]) were mixed and subjected to graft copolymerization at a reaction temperature of 180°C and a rotation speed of 100 rpm. The mixture was then melt-extruded by a twin-screw extruder to obtain a modified polyolefin resin. The grafting rate of the obtained modified polyolefin resin was 2.5%, and the average functionality of the carbon-carbon double bonds in the modified polyolefin resin was 15.

[0095] 50 parts of a first polyolefin resin (ethylene-octene copolymer) with a weight-average molecular weight of 150,000 g / mol, 50 parts of the modified polyolefin resin obtained above, 1 part of an electron irradiation crosslinking aid (tripropylene isocyanurate), and 0.1 part of a stabilizer (bis(1-octoxy-2,2,6,6-tetramethyl-4-piperidinyl) sebacate) were mixed and extruded at 150°C to obtain a cast film with a thickness of 0.01 mm. The cast film was then cured by electron irradiation to obtain a carrier film. When the irradiation dose was set to 100 kGy, the degree of crosslinking of the prepared carrier film was 53.7%.

[0096] Example 17

[0097] 100 parts of a second polyolefin resin (polyethylene) with a weight-average molecular weight of 100,000 g / mol, 4 parts of a first active monomer (trimethylolpropane triacrylate), 0.2 parts of an initiator (2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane), and 0.05 parts of an antioxidant (pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]) were mixed and subjected to graft copolymerization at a reaction temperature of 180°C and a rotation speed of 100 rpm. The mixture was then melt-extruded by a twin-screw extruder to obtain a modified polyolefin resin. The grafting rate of the obtained modified polyolefin resin was 2.5%, and the average functionality of the carbon-carbon double bonds in the modified polyolefin resin was 15.

[0098] Thirty parts of a first polyolefin resin (ethylene-octene copolymer) with a weight-average molecular weight of 150,000 g / mol, 50 parts of the modified polyolefin resin obtained above, 1 part of an electron irradiation crosslinking aid (tripropylene isocyanurate), and 0.1 part of a stabilizer (bis(1-octoxy-2,2,6,6-tetramethyl-4-piperidinyl) sebacate) were mixed and extruded at 150°C to obtain a cast film with a thickness of 0.01 mm. The cast film was then cured by electron irradiation to obtain a carrier film. When the irradiation dose was set to 100 kGy, the crosslinking degree of the prepared carrier film was 63.1%.

[0099] Comparative Example 1

[0100] 100 parts of a second polyolefin resin (polyethylene) with a weight-average molecular weight of 200,000 g / mol, 18 parts of a first active monomer (trimethylolpropane triacrylate), 3 parts of an initiator (2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane), and 1 part of an antioxidant (pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]) were mixed and subjected to graft copolymerization at a reaction temperature of 160℃ and a rotation speed of 100 rpm. The mixture was then melt-extruded by a twin-screw extruder to obtain a modified polyolefin resin. The grafting rate of the obtained modified polyolefin resin was 12%, and the average functionality of the carbon-carbon double bonds in the modified polyolefin resin was 120.

[0101] Eighty parts of a first polyolefin resin (ethylene-octene copolymer) with a weight average molecular weight of 150,000, 20 parts of the modified polyolefin resin obtained above, 1 part of an electron irradiation crosslinking aid (tripropylene isocyanurate), and 0.1 part of a stabilizer (bis(1-octoxy-2,2,6,6-tetramethyl-4-piperidinyl) sebacate) were mixed and extruded at 180°C to obtain a cast film with a thickness of 0.01 mm. The cast film was then cured by electron irradiation to obtain a carrier film. When the irradiation dose was set to 100 kGy, the degree of crosslinking of the prepared carrier film was 47.2%.

[0102] Comparative Example 2

[0103] The difference between Comparative Example 2 and Example 1 is that no modified polyolefin resin was added. In Comparative Example 2, the degree of crosslinking of the carrier film obtained by electron irradiation curing of the cast film at an irradiation dose of 100 kGy was 10.5%.

[0104] Comparative Example 3

[0105] 100 parts of a second polyolefin resin (polyethylene) with a weight-average molecular weight of 50,000 g / mol, 0.5 parts of a first active monomer (trimethylolpropane triacrylate), 0.1 parts of an initiator (2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane), and 0.05 parts of an antioxidant (pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]) were mixed and subjected to graft copolymerization at a reaction temperature of 180℃ and a rotation speed of 100 rpm. The mixture was then melt-extruded by a twin-screw extruder to obtain a modified polyolefin resin. The grafting rate of the obtained modified polyolefin resin was 0.2%, and the average functionality of the carbon-carbon double bonds in the modified polyolefin resin was 1.

[0106] Eighty parts of a first polyolefin resin (ethylene-octene copolymer) with a weight average molecular weight of 150,000, 20 parts of the modified polyolefin resin obtained above, 1 part of an electron irradiation crosslinking aid (tripropylene isocyanurate), and 0.1 part of a stabilizer (bis(1-octoxy-2,2,6,6-tetramethyl-4-piperidinyl) sebacate) were mixed and extruded at 150°C to obtain a cast film with a thickness of 0.01 mm. The cast film was then cured by electron irradiation to obtain a carrier film. When the irradiation dose was set to 100 kGy, the degree of crosslinking of the prepared carrier film was 12.9%.

[0107] The parameters in the preparation process of the carrier membrane in the above examples and comparative examples were statistically analyzed, and the results are shown in Table 1. Among them, the grafting rate of the modified polyolefin resin is the ratio of the mass of the monomer grafted onto the polymer molecular chain to the mass of the polymer. Specifically, the test method is as follows: referring to the method in patent CN110441253A, the grafting rate is tested using FTIR. The specific test method is as follows: ① A series of grafted samples with different grafting rates are prepared. The total mass of the samples is W, and the mass of the monomer is m0. ② The samples are purified by dissolving, filtering, extracting, and drying to obtain purified samples, with a sample mass of M1. ③ The grafting rate (G) of samples with different grafting rates is calculated. r And the modification rate (C), calculated as: C=(M1-W) / m0×100%; G r = (M1-W) / W×100%. ④ The infrared spectra of the above samples were determined by infrared spectroscopy, and the range of the samples within ~1720 cm⁻¹ was recorded using infrared analysis software. -1 and ~1378cm -1 The peak areas are denoted as A. 1720 and A 1378 , then A=A 1720 / A 1378 Note: The characteristic peak positions of different monomers vary, and the calculation needs to be adjusted accordingly based on the peak positions of the monomers. ⑤ Plot the grafting rate against the ratio of A measured by infrared spectroscopy, and obtain the standard curve equation through linear fitting. ⑥ Measure and calculate the A of the sample to be tested, substitute it into the fitted curve equation, and obtain the grafting rate of the sample to be tested.

[0108] Regarding the determination of irradiation dose: The irradiation dose can be calculated using the formula D = K * I / V / SW. In this formula, D is the absorbed dose (kGy); K is a coefficient, a constant; I is the electron beam current (mA); V is the under-beam delivery speed (m / min); and SW is the scanning width (m). During the electron irradiation curing process of the cast film, the corresponding electron beam current, under-beam delivery speed, electron beam current, and scanning width are recorded. The irradiation dose can then be calculated using the above formula.

[0109] Table 1

[0110]

[0111] To further understand the performance of the prepared support membrane, its performance was further tested. Among these tests,

[0112] Test method for degree of crosslinking: Refer to the method in standard GB / T29848 "Ethylene-vinyl acetate copolymer film for photovoltaic encapsulation";

[0113] Peel strength test method: This refers to the peel strength between the carrier film and the solar cell. The test method refers to the method in standard GB / T29848 "Ethylene-vinyl acetate copolymer adhesive film for photovoltaic encapsulation". The peel strength test between the adhesive film and the solar cell is conducted in the following stacking order: glass, conventional adhesive film, solar cell, test adhesive film, and conventional backsheet. HJT structure solar cells are selected.

[0114] Test method for elongation at break: Refer to standard GB / T29848 "Ethylene-vinyl acetate copolymer film for photovoltaic encapsulation".

[0115] Creep performance test method: Performed according to ASTM D2990 standard. Test temperature 90℃, test time 24 hours, applied force constant 10N.

[0116] Table 2

[0117]

[0118]

[0119] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects:

[0120] In Examples 1 to 17, carrier membranes were prepared using the carrier membrane composition formulation provided in this application. According to the data in the table, in the above examples, under the same irradiation dose of 100 kGy, the prepared carrier membranes all exhibited good crosslinking degree; simultaneously, the obtained carrier membranes showed better overall performance, including peel strength, elongation at break, and creep properties. In particular, controlling the proportions of each component in the carrier membrane composition within a preferred range resulted in even better crosslinking degree and overall performance of the prepared carrier membrane.

[0121] In Comparative Example 1, the modified polyolefin resin used in the carrier membrane composition had a high grafting rate and average functionality. Although the crosslinking degree of the carrier membrane after irradiation was acceptable, the peel strength of the carrier membrane was significantly lower than that of the embodiments of this application. In Comparative Example 2, no modified polyolefin resin was added to the carrier membrane composition. Under the same irradiation dose of 100 KGy as the embodiments, the crosslinking degree of the carrier membrane after irradiation was poor, the irradiation efficiency was low, and the peel strength of the corresponding carrier membrane was also significantly lower than that of the embodiments of this application. In Comparative Example 3, although modified polyolefin resin was added during the preparation of the carrier membrane, the average functionality of the carbon-carbon double bonds in the modified polyolefin resin was low. The crosslinking efficiency of the resulting carrier membrane under an irradiation dose of 100 KGy was significantly lower than that of the embodiments of this application, and the performance of the resulting carrier membrane was also significantly lower than that of the embodiments of this application.

[0122] In summary, in the carrier film composition provided in this application, the first polyolefin resin provides the basic physical properties for the formation of the carrier film, while the modified polyolefin resin improves the reactivity and functional properties between the components by introducing carbon-carbon double bond functional groups. Through the complex synergistic mechanism between the two components, the crosslinking efficiency, mechanical properties, thermal stability, and durability of the carrier film are optimized, making it an ideal carrier film material for photovoltaic modules, especially suitable for the requirements of busbar-less (OBB) technology. This improves photoelectric conversion efficiency, reduces production costs, and enhances module reliability.

[0123] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A carrier membrane composition, characterized in that, The carrier membrane composition comprises: a first polyolefin resin and a modified polyolefin resin; The modified polyolefin resin contains carbon-carbon double bonds, and the average functionality of the carbon-carbon double bonds in the modified polyolefin resin is 5 to 100. The modified polyolefin resin is obtained by graft copolymerization of a second polyolefin resin and an active monomer containing the carbon-carbon double bond.

2. The carrier membrane composition according to claim 1, characterized in that, The grafting rate of the modified polyolefin resin is 0.5-10%; preferably, the grafting rate of the modified polyolefin resin is 1-5%. Preferably, the active monomer is a first active monomer and / or a second active monomer; wherein the first active monomer contains at least two carbon-carbon double bonds and a carbonyl group, and the second active monomer contains the carbon-carbon double bonds and at least one of the following groups: epoxy group, carbonyl group, carboxyl group, hydroxyl group, amide group or amino group; Preferably, the active monomer is a combination of the first active monomer and the second active monomer; Preferably, the weight ratio of the first active monomer to the second active monomer is (50-100):(1-50); Preferably, the first active monomer is selected from one or more of the following: tripropylene isocyanurate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, tripropylene glycol diacrylate, and triallyl cyanurate. Preferably, the second active monomer is selected from one or more of glycidyl methacrylate, dimethyl maleate, methacrylic acid, hydroxyethyl methacrylate, and acrylamide; Preferably, the graft copolymerization reaction is carried out using at least one of melt extrusion, solution copolymerization, suspension copolymerization, and emulsion copolymerization. Preferably, the graft copolymerization reaction is carried out using the melt extrusion method; preferably, the temperature of the graft copolymerization reaction is 90–180°C. Preferably, the rotation speed of the melt extrusion is 100 to 400 rpm.

3. The carrier membrane composition according to claim 1, characterized in that, The first polyolefin resin and the second polyolefin resin are each independently selected from one or more of polyethylene, polypropylene, ethylene-octene copolymer, ethylene-butene copolymer and ethylene-hexene copolymer; Preferably, the weight-average molecular weight of the first polyolefin resin is 25,000 to 500,000 g / mol; Preferably, the weight-average molecular weight of the second polyolefin resin is 50,000 to 500,000 g / mol.

4. The carrier membrane composition according to any one of claims 1 to 3, characterized in that, By weight, the first polyolefin resin in the carrier membrane composition is 1 to 90 parts, and the modified polyolefin resin is 10 to 100 parts; Preferably, the carrier membrane composition further includes an electron irradiation crosslinking agent and / or a stabilizer; Preferably, by weight, the carrier membrane composition comprises 50-90 parts of the first polyolefin resin, 10-50 parts of the modified polyolefin resin, 0-5.0 parts of the electron irradiation crosslinking aid, and 0-2.0 parts of the stabilizer, wherein the contents of the electron irradiation crosslinking aid and the stabilizer are both 0. Preferably, in the carrier membrane composition, the weight ratio of the first polyolefin resin to the modified polyolefin resin is (1-9):1; Preferably, the electron irradiation crosslinking aid is selected from one or more of the following: tripropylene isocyanurate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, triallyl cyanurate, tripropylene glycol diacrylate, pentaerythritol triallyl ether, and pentaerythritol allyl ether. Preferably, the stabilizer is selected from one or more of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, bis(1-octoxy-2,2,6,6-tetramethyl-4-piperidinyl) sebacate, polysuccinate (4-hydroxy-2,2,6,6-tetramethyl-1-piperidinol), 2-hydroxy-4-n-octoxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-2'-carboxybenzophenone, and 2,4-dihydroxybenzophenone.

5. The carrier membrane composition according to any one of claims 1 to 3, characterized in that, The raw materials for the graft copolymerization reaction include the second polyolefin resin, the active monomer, the initiator, and the antioxidant; Preferably, by weight, the raw materials for the graft copolymerization reaction include 100 parts of the second polyolefin resin, 1.0 to 15 parts of the active monomer, 0.05 to 2 parts of the initiator, and 0.05 to 0.5 parts of the antioxidant. Preferably, the initiator is selected from 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, 1,1-(bis(tert-butylperoxy)3,3,5-trimethylcyclohexane), tert-butyl peroxide, triphenylmethane-4,4',4”-triisocyanate, dicumyl peroxide, bis(2-tert-butylperoxyisopropyl)benzene, tert-butylisopropyl peroxide, tert-amyl peroxide, di-tert-amyl peroxide, and tert-butylperoxide. Formate, tert-butyl peroxide-2-ethylhexanoate, tert-butyl peroxide-3,5,5-trimethylhexanoate, di(4-chlorobenzoyl)peroxide, di(2,4-dichlorobenzyl)peroxide, di(4-methylphenyl)peroxide, n-butyl-4,4-di(tert-butyl peroxide)valerate, ethyl-3,3-di(tert-butyl peroxide)butyrate and tert-butyl peroxide-2-ethylhexyl carbonate; Preferably, the antioxidant is selected from one or more of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate, and tris(2,4-di-tert-butylphenyl)phosphite.

6. A carrier membrane, characterized in that, The carrier membrane is prepared from the carrier membrane composition according to any one of claims 1 to 5.

7. The method for preparing the carrier membrane according to claim 6, characterized in that, The preparation method includes the following steps: After mixing raw materials including a second polyolefin resin and an active monomer, a graft copolymerization reaction is carried out to obtain a modified polyolefin resin. After mixing raw materials including the first polyolefin resin and the modified polyolefin resin, the mixture is extruded and cast at a first temperature to obtain a cast film. The cast film is cured by electron irradiation to obtain the carrier film.

8. The method for preparing the carrier membrane according to claim 7, characterized in that, The preparation method includes the following steps: The modified polyolefin resin is obtained by mixing the second polyolefin resin, the active monomer, the initiator and the antioxidant, and then subjecting the mixture to the graft copolymerization reaction. The first polyolefin resin, the modified polyolefin resin, the electron irradiation crosslinking aid, and the stabilizer are mixed and then extruded at the first temperature to obtain the cast film. The cast film is cured by electron irradiation to obtain the carrier film.

9. The method for preparing the carrier membrane according to claim 7 or 8, characterized in that, The first temperature is 75–200°C; Preferably, the thickness of the carrier membrane is 0.01–0.5 mm; Preferably, the temperature of the graft copolymerization reaction is 90–180°C; Preferably, the electron irradiation dose is <200 KGy; Preferably, the extrusion method is single-screw extrusion or twin-screw extrusion.

10. A gridless photovoltaic cell module, characterized in that, The gridless photovoltaic cell module includes the carrier film as described in claim 6; or the gridless photovoltaic cell module includes the carrier film prepared by any one of the preparation methods described in claims 7 to 9.

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