Composition, packaging adhesive film and photovoltaic module

Abstract

The invention relates to the technical field of solar cells, in particular to a composition, a packaging adhesive film and a photovoltaic module. The composition disclosed by the invention is prepared from the following components in parts by mass: 100 to 150 parts of ethylene-vinyl acetate copolymer, 70 to 100 parts of composite filler and 1 to 10 parts of cross-linking agent, the composite filler comprises a matrix and a coating layer coating at least part of the surface of the matrix; the matrix comprises first particles; the coating layer includes second particles. The composite filler of the composition is composed of the base body and the coating layer coating the outer side of the base body, the composite filler in the composition can avoid the agglomeration phenomenon generated when the first particles and the second particles are independently used, and then the peel strength of a subsequent packaging adhesive film is improved; and the Mohs hardness of the second particles is controlled to be larger than that of the first particles, so that more stable coating is formed, and the long-term stability of the subsequent packaging adhesive film is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cells, and in particular to a composition, an encapsulation film and a photovoltaic module. Background Art

[0002] Solar cell encapsulant is an indispensable material in the production of solar photovoltaic modules. It is mainly used for the encapsulation of solar cells to protect them from the external environment and improve the reliability and service life of the modules. The main types of encapsulant include ethylene-vinyl acetate copolymer (EVA) film, ethylene-octene copolymer (POE) film, and expanded polyethylene (EPE) film. EVA film is the most commonly used solar cell encapsulation material, with high light transmittance, good adhesion, weather resistance, and resistance to UV yellowing. After long-term use, existing EVA films are affected by environmental factors (such as ultraviolet rays, humidity, heat, oxygen, etc.), and will experience various aging problems, which in turn affect the performance and life of the modules.

[0003] Therefore, it is urgent to develop a composition with good long-term stability. Summary of the Invention

[0004] The present invention aims to solve one of the technical problems in the related art at least to a certain extent. To this end, the present invention provides a composition with good long-term stability.

[0005] The first aspect of the present invention provides a composition comprising, by weight, 100-150 parts of ethylene-vinyl acetate copolymer (EVA), 70-100 parts of a composite filler, and 1-10 parts of a cross-linking agent;

[0006] The composite filler comprises a matrix and a coating layer coated on at least a portion of the surface of the matrix;

[0007] The matrix includes first particles, and the Mohs hardness of the first particles is 3-4;

[0008] The coating layer includes second particles, and the Mohs hardness of the second particles is 5-7;

[0009] The ratio of the D50 particle sizes of the first particles, the second particles, and the composite filler is 1:(0.001-0.03):(1-4).

[0010] The composition includes a certain ratio of ethylene-vinyl acetate copolymer, a composite filler, and a crosslinking agent. The composite filler consists of a matrix and a coating layer coated on the outside of the matrix. The composite filler in the composition can avoid the agglomeration phenomenon that occurs when the first particles and the second particles are used alone, thereby improving the peel strength of the subsequent encapsulation film. The Mohs hardness of the second particles is controlled to be greater than that of the first particles to form a more stable coating, thereby improving the long-term stability of the subsequent encapsulation film.

[0011] In some embodiments of the present invention, the first particles include one or more of calcium carbonate particles, barium sulfate particles, calcium sulfate particles, strontium sulfate particles, zinc sulfide particles, and magnesium carbonate particles.

[0012] In some embodiments of the present invention, the first particles have a particle size distribution of 40-100 μm and a D50 particle size of 70-80 μm. The first particles of the present invention have a narrow particle size distribution and are substantially uniform in size, resulting in a composite filler with a relatively uniform overall particle size distribution. This facilitates the subsequent formation of an encapsulating film with a relatively uniform thickness. Furthermore, during the coating process, the distribution of the composite filler throughout the thickness of the encapsulating film is also relatively uniform.

[0013] In some embodiments of the present invention, the first particles are spherical in shape. The properties of the spherical first particles are relatively uniform at different positions in 360 degrees. Thus, from a three-dimensional perspective, the coating layer on the substrate surface is uniformly distributed. When added to the composition, the coating layer can be evenly distributed in three dimensions.

[0014] In some embodiments of the present invention, the sphericity of the first particles is 8.5-9.5.

[0015] In some embodiments of the present invention, the second particles include one or more of titanium dioxide particles, silicon dioxide particles, and orthoclase particles.

[0016] In some embodiments of the present invention, the second particles have a particle size distribution of 0.1-1 μm and a D50 particle size of 0.2-0.5 μm. The narrow particle size distribution and substantially uniform particle size of the second particles of the present invention allow for more uniform coating of the substrate, resulting in a composite filler with a relatively uniform overall particle size distribution, which facilitates the subsequent formation of an encapsulating film with a relatively uniform thickness.

[0017] In some embodiments of the present invention, the mass content of the second particles is 15%-30% based on the mass of the composite filler. Controlling the mass content of the second particles can enable the second particles to form an island-like coating on the surface of the substrate, reducing the interaction force between the coating layers of adjacent composite fillers, avoiding agglomeration between multiple composite fillers caused by the mutual bonding of adjacent coating layers, improving the uniformity of the particle size distribution of the composite filler, and obtaining a more stable encapsulation film with better peel strength performance in the subsequent preparation process. In addition, controlling the mass content of the second particles can improve the reflection and refraction effects of light in the film, thereby further improving the reflectivity of the encapsulation film.

[0018] In some embodiments of the present invention, the D50 particle size of the composite filler is 60-350 μm.

[0019] In some embodiments of the present invention, the coating layer includes a first coating layer and a second coating layer; the first coating layer coats at least a portion of the surface of the substrate; the second coating layer coats at least a portion of the surface of the first coating layer; the first coating layer includes a coupling agent; and the second coating layer includes the second particles.

[0020] In some embodiments of the present invention, the coupling agent includes one or more of phthalate compounds, silane compounds, aluminate compounds, phosphate compounds, and borate compounds.

[0021] In some embodiments of the present invention, the mass content of the coupling agent is 4%-5% based on the mass of the composite filler.

[0022] In some embodiments of the present invention, the phthalate compound includes tetrabutyl titanate and / or tetraisopropyl titanate.

[0023] In some embodiments of the present invention, the silane compound includes one or more of aminosilane, mercaptosilane, epoxysilane, vinylsilane, and methacryloxysilane.

[0024] In some embodiments of the present invention, the aluminate compound includes one or more of isopropyl tris(dioctylpyrophosphate acyloxy)aluminate and isopropyl tris(dodecylbenzenesulfonyloxy)aluminate.

[0025] In some embodiments of the present invention, the phosphate compound includes one or more of vinyl dimethyl phosphate and methacryloxypropyl phosphate.

[0026] In some embodiments of the present invention, the borate ester compound includes one or more of tributyl borate and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane borate.

[0027] In some embodiments of the present invention, the mass content of vinyl acetate is 25% to 45% based on the mass of the ethylene-vinyl acetate copolymer. Optimizing the mass content of vinyl acetate in the ethylene-vinyl acetate copolymer improves reactivity and the peel strength of the subsequently prepared encapsulation film, reducing the risk of film peel strength loss and photovoltaic module breakage caused by film hardening after aging.

[0028] In some embodiments of the present invention, the crosslinking agent includes one or more of peroxyester compounds, peroxycarbonate compounds, dialkyl peroxide compounds, and diacyl peroxide compounds. The crosslinking agent can generate free radicals, initiating the formation of covalent bonds between the vinyl acetate segments in the EVA, thereby constructing a three-dimensional crosslinked network. When combined with the EVA and composite fillers in the composition, the crosslinking agent can enhance the mechanical properties and long-term stability of the encapsulating film.

[0029] In some embodiments of the present invention, the peroxyester compound includes one or more of tert-butyl peroxy-2-ethylhexanoate (TBPEH), tert-butyl peroxybenzoate (TBPB), tert-amyl peroxy-2-ethylhexanoate (TAEC), and tert-butyl peroxyacetate (TBPA).

[0030] In some embodiments of the present invention, the peroxycarbonate compound includes one or more of tert-butyl peroxy-2-ethylhexyl carbonate (TBEC), bis(4-tert-butylcyclohexyl) peroxydicarbonate (TBCP), di(2-ethylhexyl) peroxydicarbonate (EHP), di(hexadecyl) peroxydicarbonate (DCPD), and di(3-methoxybutyl) peroxydicarbonate (DMBP).

[0031] In some embodiments of the present invention, the dialkyl peroxide compound includes one or more of dicumyl peroxide (DCP), di-tert-butyl peroxide (DTBP), and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane (DBPH).

[0032] In some embodiments of the present invention, the diacyl peroxide compound includes one or more of dibenzoyl peroxide (BPO), dilauroyl peroxide (DLP), diacetyl peroxide (DAP), di(3,5,5-trimethylhexanoyl) peroxide (TMHP), and di(4-chlorobenzoyl) peroxide (DCBP).

[0033] In some embodiments of the present invention, the composition further includes a tackifier. The tackifier can reduce the surface energy of the adhesive film, allowing it to better wet the surface of the glass, backplane, or battery module, reducing interfacial defects. The tackifier, when combined with other components of the composition, such as EVA, a crosslinking agent, and composite fillers, can significantly improve the adhesive film and bonding properties, thereby enhancing the packaging quality and long-term reliability of the battery module.

[0034] In some embodiments of the present invention, the composition further includes a plasticizer. The plasticizer can be embedded in the vinyl acetate (VA) segments of the EVA, weakening the interchain forces of the polymer chains, increasing segment fluidity, and improving segment flexibility and processing properties. The plasticizer, when combined with other components of the composition, such as the EVA, crosslinking agent, and composite filler, can comprehensively enhance the mechanical properties and long-term stability of the encapsulating film.

[0035] In some embodiments of the present invention, the composition further comprises an antioxidant, which can be used in combination with the EVA, crosslinking agent, composite filler and other components in the composition to improve the aging resistance of the solar cell encapsulation film.

[0036] In some embodiments of the present invention, the viscosity of the tackifier is greater than 6 Pa·s. This viscosity is well-matched with EVA, reducing phase separation or interfacial defects and improving the uniformity of the composition. This viscosity also provides sufficient cohesion and adhesion, making it suitable for photovoltaic module encapsulation.

[0037] In some embodiments of the present invention, the tackifier includes one or more of hydrogenated petroleum resin, terpene resin, and rosin resin.

[0038] In some embodiments of the present invention, the plasticizer includes one or more of tributyl citrate, acetyl tributyl citrate, epoxidized soybean oil, dicyclohexyl phthalate, glycerol tribenzoate, or trimethylolpropane tribenzoate.

[0039] In some embodiments of the present invention, the antioxidant includes one or more of hindered phenol compounds, phosphite compounds, and thioester compounds.

[0040] In some embodiments of the present invention, the hydrogenated petroleum resin includes one or more of hydrogenated C5 petroleum resin, hydrogenated C9 petroleum resin, and dicyclopentadiene hydrogenated petroleum resin.

[0041] In some embodiments of the present invention, the hindered phenol compound includes one or more of 2,6-di-tert-butyl-p-cresol, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-s-triazine-2,4,6-(1H,3H,5H)-trione, and thiobis(3-methyl-6-tert-butyl)phenol.

[0042] In some embodiments of the present invention, the phosphite compound includes one or more of tris(2,4-di-tert-butylphenyl)phosphite, bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, tetrakis(2,4-di-tert-butylphenyl)-4,4'-biphenyl diphosphite, and diphenylisodecylphosphite.

[0043] In some embodiments of the present invention, the thioester compound includes one or more of dilauryl thiodipropionate, distearyl thiodipropionate, dimyristyl thiodipropionate, and 4,4'-thiobis(6-tert-butyl-3-methylphenol).

[0044] In some embodiments of the present invention, the composition further comprises 20-25 parts by mass of a tackifier.

[0045] In some embodiments of the present invention, the composition further comprises 6-8 parts by mass of a plasticizer.

[0046] In some embodiments of the present invention, the composition further comprises 4-6 parts by mass of an antioxidant.

[0047] The second aspect of the present invention provides a packaging film obtained by cross-linking the composition.

[0048] A third aspect of the present invention provides a photovoltaic module comprising solar cells, glass and a back sheet, wherein the solar cells and the glass, and the solar cells and the back sheet are connected via a cross-linked composition.

[0049] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. DETAILED DESCRIPTION

[0050] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be understood as limiting the present invention.

[0051] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, features defined as "first" or "second" may explicitly or implicitly include one or more of such features. Furthermore, in the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0052] For commonly used white EVA film systems, calcium carbonate and titanium dioxide are typically added as two different fillers. Calcium carbonate and titanium dioxide can be added directly to the EVA film system, or premixed and then added to the system. However, regardless of the addition method, calcium carbonate and calcium carbonate will agglomerate, or titanium dioxide and titanium dioxide will agglomerate, resulting in calcium carbonate and titanium dioxide being unable to be evenly distributed in the system. Calcium carbonate and titanium dioxide have different physical and chemical properties. As pigments and fillers in films used for solar cell encapsulation, they not only have different light reflection and refractive indices, but also have significant differences in their resistance to environmental erosion, such as acidic media. After long-term use, the film can fail due to localized erosion.

[0053] To this end, the first aspect of the present invention provides a composition comprising, by weight, 100-150 parts of ethylene-vinyl acetate copolymer (EVA), 70-100 parts of a composite filler, and 1-10 parts of a cross-linking agent;

[0054] The composite filler comprises a matrix and a coating layer coated on at least a portion of the surface of the matrix;

[0055] The matrix includes first particles, and the Mohs hardness of the first particles is 3-4;

[0056] The coating layer includes second particles, and the Mohs hardness of the second particles is 5-7;

[0057] The ratio of the D50 particle sizes of the first particles, the second particles, and the composite filler is 1:(0.001-0.03):(1-4).

[0058] The composition includes a certain ratio of ethylene-vinyl acetate copolymer, a composite filler, and a crosslinking agent. The composite filler consists of a matrix and a coating layer coated on the outside of the matrix. The composite filler in the composition can avoid the agglomeration phenomenon that occurs when the first particles and the second particles are used alone, thereby improving the peel strength of the subsequent encapsulation film. The Mohs hardness of the second particles is controlled to be greater than that of the first particles to form a more stable coating, thereby improving the long-term stability of the subsequent encapsulation film.

[0059] In some preferred embodiments of the present invention, as an example, the ratio of the D50 particle sizes of the first particles, the second particles, and the composite filler is 1:(0.003-0.005):(1-4).

[0060] In some embodiments of the present invention, the first particles include one or more of calcium carbonate particles, barium sulfate particles, calcium sulfate particles, strontium sulfate particles, zinc sulfide particles, and magnesium carbonate particles.

[0061] In some embodiments of the present invention, the first particles can have a Mohs hardness of 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, or 4, as examples.

[0062] In some embodiments of the present invention, the particle size distribution of the first particles is 40-100 μm, and the D50 particle size is 70-80 μm. As an example, the particle size distribution of the first particles can be 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100 μm, and the D50 particle size can be 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80 μm. The particle size distribution of the first particles of the present invention is relatively narrow and the particle size is basically consistent. A composite filler with a relatively uniform overall particle size distribution can be obtained, which is conducive to the subsequent formation of a relatively uniform thickness packaging film. At the same time, during the coating process, the distribution of the composite filler in the thickness direction of the packaging film will also be relatively uniform.

[0063] In some embodiments of the present invention, the first particles are spherical; further, the first particles have a sphericity of 8.5-9.5. For example, the sphericity of the spherical first particles can be 8.5, 8.6, 8.7, 8.8, 8.9, 9, 9.1, 9.2, 9.3, 9.4, or 9.5. The spherical first particles have relatively uniform properties at all positions throughout 360°. Thus, from a three-dimensional perspective, the coating layer on the substrate surface is uniformly distributed, and when added to the composition, a uniform distribution in three dimensions can be achieved.

[0064] In some embodiments of the present invention, the second particles include one or more of titanium dioxide particles, silicon dioxide particles, and orthoclase particles.

[0065] In some embodiments of the present invention, as an example, the Mohs hardness of the first particles can be 5, 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9, 6, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7.

[0066] In some embodiments of the present invention, the second particles have a particle size distribution of 0.1-1 μm, and a D50 particle size of 0.2-0.5 μm. As an example, the second particles may have a particle size distribution of 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1 μm, and a D50 particle size of 0.2, 0.3, 0.4, or 0.5 μm. The second particles of the present invention have a narrow particle size distribution and are substantially uniform in size, allowing for a more uniform coating of the substrate, resulting in a composite filler having a relatively uniform overall particle size distribution, which facilitates the subsequent formation of an encapsulation film with a relatively uniform thickness.

[0067] In some embodiments of the present invention, based on the mass of the composite filler, the mass content of the second particles is 15%-30%. As an example, based on the mass of the composite filler, the mass content of the second particles is 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%. Controlling the mass content of the second particles can enable the second particles to form an island-like coating on the surface of the substrate, reduce the interaction force between the coating layers of adjacent composite fillers, avoid agglomeration between multiple composite fillers caused by the mutual bonding of adjacent coating layers, improve the uniformity of the particle size distribution of the composite filler, and obtain a packaging film with better peel strength performance and more stability in the subsequent preparation process. In addition, controlling the mass content of the second particles can improve the reflection and refraction effects of light in the film, thereby further improving the reflectivity of the packaging film.

[0068] In some embodiments of the present invention, the composite filler has a D50 particle size of 60-350 μm. For example, the composite filler can have a D50 particle size of 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, or 350 μm.

[0069] In some embodiments of the present invention, the coating layer includes a first coating layer and a second coating layer; the first coating layer coats at least a portion of the surface of the substrate; the second coating layer coats at least a portion of the surface of the first coating layer; the first coating layer includes a coupling agent; and the second coating layer includes the second particles.

[0070] In some embodiments of the present invention, the coupling agent includes one or more of phthalate compounds, silane compounds, aluminate compounds, phosphate compounds, and borate compounds.

[0071] In some embodiments of the present invention, the phthalate compound includes tetrabutyl titanate and / or tetraisopropyl titanate.

[0072] In some embodiments of the present invention, the silane compound includes one or more of aminosilane, mercaptosilane, epoxysilane, vinylsilane, and methacryloxysilane.

[0073] In some embodiments of the present invention, the aluminate compound includes one or more of isopropyl tris(dioctylpyrophosphate acyloxy)aluminate and isopropyl tris(dodecylbenzenesulfonyloxy)aluminate.

[0074] In some embodiments of the present invention, the phosphate compound includes one or more of vinyl dimethyl phosphate and methacryloxypropyl phosphate.

[0075] In some embodiments of the present invention, the borate ester compound includes one or more of tributyl borate and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane borate.

[0076] In some embodiments of the present invention, the mass content of the coupling agent is 4%-5% based on the mass of the composite filler.

[0077] In some embodiments of the present invention, the present invention has no special requirements for the preparation method of the composite filler, and it can be prepared by conventional methods in the art, for example, a sol-gel method, a liquid phase precipitation method or a mechanochemical method.

[0078] In some embodiments of the present invention, the method for preparing the composite filler comprises the following steps:

[0079] S1. Mix the first particles with water, adjust the pH to 7.5-7.8, and then mix with a coupling agent. Stir and react at 50-80° C. for 1-10 hours. Then add the first coupling agent. The mass ratio of the first coupling agent to the first particles is (20-30):100.

[0080] S2. Mix the product obtained in step S1 with a second coupling agent, wherein the mass ratio of the second coupling agent to the first particles is (20-30):100, and stir the mixture at 50-80° C. for 1-10 hours.

[0081] In some specific embodiments of the present invention, the mass fraction of the composite filler in the composition can be 70 parts, 80 parts, 90 parts, 100 parts, or a range consisting of any two of these values.

[0082] In some embodiments of the present invention, the mass content of vinyl acetate is 25%-45% based on the mass of the ethylene-vinyl acetate copolymer. As an example, the mass content of vinyl acetate is 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, and 45% based on the mass of the ethylene-vinyl acetate copolymer. By optimizing the mass content of vinyl acetate in the ethylene-vinyl acetate copolymer, the reaction activity is improved, and the peel strength of the subsequently prepared encapsulation film is improved, thereby reducing the risk of film peel strength loss and photovoltaic module fragmentation caused by the film becoming hard after aging.

[0083] In some specific embodiments of the present invention, in the composition, the mass fraction of ethylene-vinyl acetate copolymer can be 100 parts, 110 parts, 120 parts, 130 parts, 140 parts, 150 parts or a range consisting of any two of these values.

[0084] In some embodiments of the present invention, the crosslinking agent includes one or more of peroxyester compounds, peroxycarbonate compounds, dialkyl peroxide compounds, and diacyl peroxide compounds. The crosslinking agent can generate free radicals, initiating the formation of covalent bonds between the vinyl acetate segments in the EVA, thereby constructing a three-dimensional crosslinked network. When combined with the EVA and composite fillers in the composition, the crosslinking agent can enhance the mechanical properties and long-term stability of the encapsulating film.

[0085] In some embodiments of the present invention, the peroxyester compound includes one or more of tert-butyl peroxy-2-ethylhexanoate (TBPEH), tert-butyl peroxybenzoate (TBPB), tert-amyl peroxy-2-ethylhexanoate (TAEC), and tert-butyl peroxyacetate (TBPA).

[0086] In some embodiments of the present invention, the peroxycarbonate compound includes one or more of tert-butyl peroxy-2-ethylhexyl carbonate (TBEC), bis(4-tert-butylcyclohexyl) peroxydicarbonate (TBCP), di(2-ethylhexyl) peroxydicarbonate (EHP), di(hexadecyl) peroxydicarbonate (DCPD), and di(3-methoxybutyl) peroxydicarbonate (DMBP).

[0087] In some embodiments of the present invention, the dialkyl peroxide compound includes one or more of dicumyl peroxide (DCP), di-tert-butyl peroxide (DTBP), and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane (DBPH).

[0088] In some embodiments of the present invention, the diacyl peroxide compound includes one or more of dibenzoyl peroxide (BPO), dilauroyl peroxide (DLP), diacetyl peroxide (DAP), di(3,5,5-trimethylhexanoyl) peroxide (TMHP), and di(4-chlorobenzoyl) peroxide (DCBP).

[0089] In some specific embodiments of the present invention, in the composition, the mass fraction of the crosslinking agent can be 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts or a range consisting of any two of these values.

[0090] In some embodiments of the present invention, the composition further includes a tackifier. The tackifier can reduce the surface energy of the adhesive film, allowing it to better wet the surface of the glass, backplane, or battery module, reducing interfacial defects. The tackifier, when combined with other components of the composition, such as EVA, a crosslinking agent, and composite fillers, can significantly improve the adhesive film and bonding properties, thereby enhancing the packaging quality and long-term reliability of the battery module.

[0091] In some embodiments of the present invention, the viscosity of the tackifier is greater than 6 Pa·s. For example, the viscosity of the tackifier is 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or 16 Pa·s. Tackifiers with these viscosities are well-matched with EVA, reducing phase separation or interfacial defects and improving the uniformity of the composition. Tackifiers with these viscosities exhibit a certain degree of cohesion and adhesion, making them suitable for photovoltaic module encapsulation.

[0092] In some embodiments of the present invention, the tackifier includes one or more of hydrogenated petroleum resin, terpene resin, and rosin resin; further, the hydrogenated petroleum resin includes one or more of hydrogenated C5 petroleum resin, hydrogenated C9 petroleum resin, and dicyclopentadiene hydrogenated petroleum resin.

[0093] In some embodiments of the present invention, the composition further comprises 20-25 parts by weight of a tackifier. For example, the tackifier may be present in an amount of 20, 21, 22, 23, 24, 25, or a range consisting of any two of these values.

[0094] In some embodiments of the present invention, the composition further includes a plasticizer. The plasticizer can be embedded in the VA segments of the EVA, weakening the interchain forces of the polymer chains, increasing segment fluidity, and improving segment flexibility and processing properties. The plasticizer, when combined with the EVA, crosslinking agent, and composite filler components of the composition, can comprehensively enhance the mechanical properties and long-term stability of the encapsulating film.

[0095] In some embodiments of the present invention, the plasticizer includes one or more of tributyl citrate, acetyl tributyl citrate, epoxidized soybean oil, dicyclohexyl phthalate, glycerol tribenzoate, or trimethylolpropane tribenzoate.

[0096] In some embodiments of the present invention, the composition further comprises 6-8 parts by weight of a plasticizer. For example, the plasticizer may be present in an amount of 6 parts, 6.5 parts, 7 parts, 7.5 parts, 8 parts, or a range consisting of any two of these values.

[0097] In some embodiments of the present invention, the composition further comprises an antioxidant, which can be used in combination with the EVA, crosslinking agent, composite filler and other components in the composition to improve the aging resistance of the solar cell encapsulation film.

[0098] In some embodiments of the present invention, the antioxidant includes one or more of hindered phenol compounds, phosphite compounds, and thioester compounds.

[0099] In some embodiments of the present invention, the hindered phenol compound includes one or more of 2,6-di-tert-butyl-p-cresol, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-s-triazine-2,4,6-(1H,3H,5H)-trione, and thiobis(3-methyl-6-tert-butyl)phenol.

[0100] In some embodiments of the present invention, the phosphite compound includes one or more of tris(2,4-di-tert-butylphenyl)phosphite, bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, tetrakis(2,4-di-tert-butylphenyl)-4,4'-biphenyl diphosphite, and diphenylisodecylphosphite.

[0101] In some embodiments of the present invention, the thioester compound includes one or more of dilauryl thiodipropionate, distearyl thiodipropionate, dimyristyl thiodipropionate, and 4,4'-thiobis(6-tert-butyl-3-methylphenol).

[0102] In some embodiments of the present invention, the composition further comprises 4-6 parts by weight of an antioxidant. For example, the amount of antioxidant by weight can be 4 parts, 4.5 parts, 5 parts, 5.5 parts, 6 parts, or a range consisting of any two of these values.

[0103] The second aspect of the present invention provides a packaging film obtained by cross-linking the composition.

[0104] A third aspect of the present invention provides a photovoltaic module comprising solar cells, glass and a back sheet, wherein the solar cells and the glass, and the solar cells and the back sheet are connected via a cross-linked composition.

[0105] The present invention has no special requirements for the preparation method of the photovoltaic module, and conventional methods in the art can be used. In some embodiments of the present invention, the preparation method of the photovoltaic module includes the following steps: laminating the composition with glass, solar cell sheets, and backsheet to obtain a laminate; and heating the laminate to crosslink the crosslinking agent in the composition with the ethylene-vinyl acetate copolymer to obtain the photovoltaic module.

[0106] The scheme of the present disclosure will be explained below with reference to the examples. Those skilled in the art will understand that the following examples are only used to illustrate the present disclosure and should not be regarded as limiting the scope of the present disclosure. Where specific techniques or conditions are not specified in the examples, the techniques or conditions described in the literature in this field or in accordance with the product instructions are used. Reagents or instruments used without specifying the manufacturer are conventional products that can be obtained commercially. The Mohs hardness of the calcium carbonate particles used in the examples of the present invention and the comparative examples is 3, and the Mohs hardness of the titanium dioxide particles is 6.

[0107] Example 1

[0108] The encapsulation film of this embodiment is prepared by the method comprising the following steps:

[0109] 120 g of ethylene-vinyl acetate copolymer (EVA), 80 g of composite filler, 20 g of tackifier, 6 g of plasticizer, 4 g of antioxidant and 2 g of crosslinking agent were mixed evenly, placed in a flat plate mold with a thickness of 1 mm, and hot-pressed in a flat plate vulcanizer for curing at a hot pressing temperature of 150° C., a hot pressing pressure of 10 MPa, and a hot pressing time of 500 s to obtain a packaging film with a thickness of 1 mm. The formula of the composition is shown in Table 1. The ethylene-vinyl acetate copolymer (EVA) has a vinyl acetate (VA) content of 33 wt %; the tackifier is rosin resin (viscosity of 10 Pa·s); the plasticizer is acetyl tributyl citrate; the antioxidant is 2,6-di-tert-butyl-p-cresol; and the crosslinking agent is tert-butyl peroxy-2-ethylhexyl carbonate. The preparation method of the composite filler comprises the following steps:

[0110] Monodisperse calcium carbonate particles and water were mixed in a mass ratio of 1:8.5, and ultrasonically dispersed uniformly. The pH was adjusted to weak alkalinity (7.6). Tetrabutyl titanate, a coupling agent, was added dropwise in an amount of 20% by mass of the monodisperse calcium carbonate particles under stirring. After the addition was completed, the reaction was continued at 60-70°C with stirring for 4 hours. After the reaction was completed, tetrabutyl titanate, a coupling agent, was added dropwise in an amount of 20% by mass of the monodisperse calcium carbonate particles under stirring. The reaction was continued at 60-70°C with stirring for 4 hours, so that the tetrabutyl titanate was partially hydrolyzed and adsorbed and fixed on the surface of the monodisperse calcium titanate particles to obtain calcium carbonate particles. A composite filler having a three-layer structure of tetrabutyl titanate and titanium dioxide particles, wherein tetrabutyl titanate is coated on the surface of calcium carbonate particles, and titanium dioxide is coated on the surface of tetrabutyl titanate to form an island-like coating. The composite filler has a D50 particle size of 70-200 μm, and the calcium carbonate particles in the composite filler have a particle size distribution of 60-90 μm, a D50 particle size of 70 μm, and a sphericity of 8.9. The mass content of tetrabutyl titanate is 5 wt%; the coating amount of titanium dioxide is 20 wt%, the titanium dioxide particle size distribution is 0.2-0.3 μm, and the D50 particle size is 0.25-0.35 μm.

[0111] Example 2

[0112] The encapsulation film of this embodiment is prepared by referring to the steps in Example 1, and the only difference from Example 1 is that:

[0113] The raw materials of Example 2 are: 125g ethylene-vinyl acetate copolymer (EVA), 83g composite filler, 22g tackifier, 7g plasticizer, 5g antioxidant and 3g crosslinking agent. The specific formula is shown in Table 1.

[0114] Example 3

[0115] The encapsulation film of this embodiment is prepared by referring to the steps in Example 1, and the only difference from Example 1 is that:

[0116] The raw materials of Example 3 are: 130g ethylene-vinyl acetate copolymer (EVA), 85g composite filler, 25g tackifier, 8g plasticizer, 6g antioxidant and 4g crosslinking agent. The specific formula is shown in Table 1.

[0117] Example 4

[0118] The encapsulating film of this embodiment is prepared by referring to the steps in Example 1, with the only difference from Example 1 being that the sphericity of the calcium carbonate particles in the composite filler of this embodiment is 8.5. The specific formula is shown in Table 1.

[0119] Example 5

[0120] The encapsulating film of this embodiment is prepared by referring to the steps in Example 1, with the only difference from Example 1 being that the titanium dioxide coating amount in the composite filler of this embodiment is 18 wt %. The specific formula is shown in Table 1.

[0121] Example 6

[0122] The encapsulating film of this embodiment is prepared by referring to the steps in Example 1, with the only difference from Example 1 being that the titanium dioxide coating amount in the composite filler of this embodiment is 27 wt %. The specific formula is shown in Table 1.

[0123] Example 7

[0124] The encapsulation film of this embodiment is prepared by referring to the steps in Example 1. The only difference from Example 1 is that the particle size distribution of the calcium carbonate in the composite filler of this embodiment is 40-100 μm. The specific formula is shown in Table 1.

[0125] Table 1

[0126]

[0127]

[0128] Comparative Example 1

[0129] The encapsulation film of this comparative example differs from that of Example 1 only in that 64 g of calcium carbonate and 16 g of titanium dioxide powder are used in place of 80 g of the composite filler in Example 1; the remaining steps are carried out with reference to the method in Example 1.

[0130] Test Case

[0131] The encapsulating films of Examples 1-7 and Comparative Example 1 were tested for their adhesive properties before and after aging. Specifically, the peel strength before and after aging was measured according to GB / T 2791-1995. A polyvinyl fluoride composite film (TPT) backsheet was used as the substrate. The aging environment was: 75°C, 85% relative humidity, 20 mL of 5% acetic acid was placed in the aging chamber, and aging was continued for 28 days. The test results are shown in Table 2.

[0132] Table 2

[0133]

[0134] As shown in Table 2, compared with Comparative Example 1, the packaging films prepared in Examples 1-7 of the present invention have higher peel strength, and after aging, the attenuation of the packaging films prepared in Examples 1-7 is lower than that of the packaging film in Comparative Example 1.

[0135] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", "some implementation plans" or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0136] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A composition, characterized in that Calculated by mass, it comprises: 100-150 parts of ethylene-vinyl acetate copolymer, 70-100 parts of composite filler and 1-10 parts of cross-linking agent; The composite filler comprises a matrix and a coating layer coated on at least a portion of the surface of the matrix; The matrix includes first particles, and the Mohs hardness of the first particles is 3-4; The coating layer includes second particles, and the Mohs hardness of the second particles is 5-7; The ratio of the D50 particle sizes of the first particles, the second particles, and the composite filler is 1:(0.001-0.03):(1-4).

2. The composition according to claim 1, characterized in that The first particles include one or more of calcium carbonate particles, barium sulfate particles, calcium sulfate particles, strontium sulfate particles, zinc sulfide particles, and magnesium carbonate particles; and / or, the first particles have a particle size distribution of 40-100 μm and a D50 particle size of 70-80 μm; And / or, the shape of the first particles is spherical; the sphericity of the first particles is 8.5-9.

5.

3. The composition according to claim 1, characterized in that The second particles include one or more of titanium dioxide particles, silicon dioxide particles, and orthoclase particles; and / or, the particle size distribution of the second particles is 0.1-1 μm, and the D50 particle size is 0.2-0.5 μm; and / or, based on the mass of the composite filler, the mass content of the second particles is 15%-30%; And / or, the D50 particle size of the composite filler is 60-350 μm.

4. The composition according to claim 1, characterized in that The coating layer includes a first coating layer and a second coating layer; the first coating layer coats at least a portion of the surface of the substrate; the second coating layer coats at least a portion of the surface of the first coating layer; the first coating layer includes a coupling agent; and the second coating layer includes the second particles; And / or, the coupling agent includes one or more of phthalate compounds, silane compounds, aluminate compounds, phosphate compounds, and borate compounds; And / or, based on the mass of the composite filler, the mass content of the coupling agent is 4%-5%.

5. The composition according to claim 4, characterized in that The phthalate compound includes tetrabutyl titanate and / or tetraisopropyl titanate; And / or, the silane compound includes one or more of aminosilane, mercaptosilane, epoxysilane, vinylsilane, and methacryloxysilane; And / or, the aluminate compound includes one or more of isopropyl tris(dioctyl pyrophosphate acyloxy)aluminate and isopropyl tris(dodecylbenzenesulfonyloxy)aluminate; And / or, the phosphate compound includes one or more of vinyl dimethyl phosphate and methacryloxypropyl phosphate; And / or, the borate ester compound includes one or more of tributyl borate and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane borate.

6. The composition according to claim 1, characterized in that Based on the mass of the ethylene-vinyl acetate copolymer, the mass content of vinyl acetate is 25%-45%.

7. The composition according to claim 1, characterized in that The cross-linking agent includes one or more of peroxyester compounds, peroxycarbonate compounds, dialkyl peroxide compounds, and diacyl peroxide compounds.

8. The composition according to claim 7, characterized in that The peroxyester compound includes one or more of tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxybenzoate, tert-amyl peroxy-2-ethylhexanoate, and tert-butyl peroxyacetate; And / or, the peroxycarbonate compound includes one or more of tert-butyl peroxy-2-ethylhexyl carbonate, bis(4-tert-butylcyclohexyl) peroxydicarbonate, di(2-ethylhexyl) peroxydicarbonate, di(hexadecyl) peroxydicarbonate, and di(3-methoxybutyl) peroxydicarbonate; And / or, the dialkyl peroxide compound includes one or more of dicumyl peroxide, di-tert-butyl peroxide, and 2,5-dimethyl-2,5-bis(tert-butylperoxide)hexane; And / or, the diacyl peroxide compound includes one or more of dibenzoyl peroxide, dilauroyl peroxide, diacetyl peroxide, di(3,5,5-trimethylhexanoyl) peroxide, and di(4-chlorobenzoyl) peroxide.

9. The composition according to claim 1, characterized in that The composition further includes a viscosity increasing agent; and / or, the composition further comprises a plasticizer; And / or, the composition further comprises an antioxidant.

10. The composition according to claim 9, characterized in that The viscosity of the tackifier is greater than 6 Pa·s; and / or, the tackifier comprises one or more of hydrogenated petroleum resin, terpene resin, and rosin resin; And / or, the plasticizer includes one or more of tributyl citrate, acetyl tributyl citrate, epoxy soybean oil, dicyclohexyl phthalate, glycerol tribenzoate or trimethylolpropane tribenzoate; And / or, the antioxidant includes one or more of hindered phenol compounds, phosphite compounds, and thioester compounds.

11. The composition according to claim 10, characterized in that The hydrogenated petroleum resin includes one or more of hydrogenated C5 petroleum resin, hydrogenated C9 petroleum resin, and dicyclopentadiene hydrogenated petroleum resin; And / or, the hindered phenol compound includes one or more of 2,6-di-tert-butyl-p-cresol, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-s-triazine-2,4,6-(1H,3H,5H)-trione, and thiobis(3-methyl-6-tert-butyl)phenol; And / or, the phosphite compound includes one or more of tris(2,4-di-tert-butylphenyl)phosphite, bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, tetrakis(2,4-di-tert-butylphenyl)-4,4'-biphenyl diphosphite, and diphenylisodecylphosphite; And / or, the thioester compound includes one or more of dilauryl thiodipropionate, distearyl thiodipropionate, dimyristyl thiodipropionate, and 4,4'-thiobis(6-tert-butyl-3-methylphenol).

12. The composition according to claim 1, characterized in that The composition further comprises 20-25 parts by weight of a tackifier; And / or, the composition further comprises 6-8 parts by mass of a plasticizer; And / or, the composition further comprises 4-6 parts by mass of an antioxidant.

13. A packaging film, characterized in that: The composition according to any one of claims 1 to 12 is obtained by cross-linking.

14. A photovoltaic module, characterized in that: The invention comprises a solar cell, glass and a back plate, wherein the solar cell and the glass, and the solar cell and the back plate are connected through the cross-linked composition according to any one of claims 1 to 12.

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