Adhesion promoter and preparation method thereof, packaging adhesive film composition and preparation method thereof, packaging adhesive film and HJT battery assembly

Abstract

The invention belongs to the field of solar cells, and particularly relates to an adhesion promoter and a preparation method thereof, a packaging adhesive film composition and a preparation method thereof, a packaging adhesive film and an HJT cell module. The method for preparing the adhesion promoter comprises the step of carrying out polymerization reaction on the silane coupling agent and titanate. According to the packaging adhesive film, the long-acting reliability of an HJT battery assembly is greatly enhanced, the problem that the adhesive force is poor due to the fact that an existing packaging adhesive film of an adhesion promoter system mainly using a silane coupling agent lacks effective chemical bonding force with an ITO film on the surface of an HJT battery is solved, and aging delamination and high-temperature hot spots of the packaging adhesive film and the battery are avoided; the long-term aging reliability of the HJT battery assembly is ensured, and the outdoor service life of the HJT battery assembly is prolonged.

Description

Technical Field

[0001] The present invention belongs to the field of solar cells, and specifically relates to an adhesion promoter and a preparation method thereof, a packaging film composition and a preparation method thereof, a packaging film and an HJT battery assembly. Background Art

[0002] In recent years, with the gradual development of solar cell technology, P-type cells have undergone rapid technological iterations to N-type cells. As one of the N-type cell technologies, intrinsic thin-film heterojunction cells (HJT) will inevitably become the mainstream direction of future solar panels due to their advantages such as fewer production processes, high conversion efficiency, low process temperature, high degree of thinning and high bifaciality.

[0003] Different from the silicon nitride structure on the surface of conventional crystalline silicon cells, the surface of HJT cells is an oxide-doped ITO film layer, namely In2O3:Sn. Due to the insufficient coordination between the surface oxygen ions and the lattice metal ions, this type of crystal structure has more acid hydroxyl groups generated by the oxygen ions absorbing protons in the air moisture, and only a small amount of metal ions will become basic hydroxyl groups. This makes it difficult to achieve good adhesion between the ITO film and the organic silane coupling agent in the conventional film because there is no effective chemical bonding site. This leads to hidden dangers in the reliability of HJT battery components. After long-term use, HJT components will have abnormal risks such as delamination from the battery and high-temperature hot spots. The above technical problems do not exist in other batteries and semiconductor devices with different structures and compositions from HJT batteries. Therefore, with the continuous development of HJT cells, especially the increasing demand for cost reduction and efficiency improvement, the high bonding performance of the encapsulation film and the stringent requirements for ensuring the high reliability of HJT components make the development of HJT battery-specific encapsulation film increasingly important.

[0004] The existing research and development of adhesion-enhancing films for heterojunction batteries have not analyzed the reasons why ITO films and conventional films cannot be effectively bonded by silane coupling agents, and have not screened or synthesized adhesion promoters that can achieve chemical bonding with the ITO film on the surface of heterojunction batteries. Instead, they have improved the wettability by changing the substrate or added some adhesion promoters that can improve the bonding with the metal interface. When used for ITO films with different surface hydroxylation conditions from the metal's crystal structure, the adhesion-enhancing effect may be more through physical bonding rather than chemical bonding, and its long-term reliability remains to be verified.

[0005] Patent applications CN115521717A and CN116640536A improve the adhesion of the battery by changing the substrate in contact with the HJT battery. The former uses polyurethane synthesized from isocyanate and polyol as an adhesive layer, and forms a double-layer co-extrusion structure with polyolefin to improve the adhesion and aging and corrosion resistance of the film. The improvement of its adhesion may benefit more from the large number of hydrogen bonds inside the polyurethane, but the hydrogen bonds with small bond energy cannot withstand the test of photovoltaic modules in harsh outdoor environments for a long time, and the reliability of the interface of thermoplastic and thermosetting materials is not considered; the latter adds cyclic ether-based compounds and cyclic olefin copolymers or homopolymers with a specific range of cyclic ether equivalents to polyolefins to improve the wettability and adhesion of the substrate to the surface of the HJT battery, improve the adhesion of the battery and improve the water resistance of the substrate, but it does not consider that the silane coupling agent cannot produce effective chemical bonding with the ITO film at the interface, and the adhesion of the HJT battery is limited and difficult to maintain after aging, which cannot meet the current high adhesion requirements.

[0006] Patent application CN115044322A improves the adhesion with HJT batteries by adjusting the film formula structure, especially by adding adhesive to the first adhesive layer in contact with the HJT battery. However, its formula is complex, and the actual ingredients or mechanism of action for improving the adhesion effect are unclear, and it cannot be guaranteed that the adhesion or UV resistance of the film will not be affected after aging.

[0007] In view of the above problems, it is necessary to develop a packaging film composition that has good adhesion to HJT batteries to improve the reliability of HJT battery components. Summary of the invention

[0008] The object of the present invention is to provide a packaging adhesive film for a heterojunction battery, which has good adhesion to a HJT battery and stable adhesion after heating, and a preparation method thereof.

[0009] A first aspect of the present invention provides a method for preparing an adhesion promoter, the method comprising polymerizing a silane coupling agent and a titanate to obtain the adhesion promoter.

[0010] In one or more embodiments, the method has one or more of the following features:

[0011] The silane coupling agent is selected from one or more of 3-(methacryloyloxy)propyltrimethoxysilane, 3-glycidyloxypropyltrimethoxysilane, vinyltrimethoxysilane, 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane;

[0012] The titanate is selected from one or more of methyl titanate, tetrakis(2-ethyl-1,3-hexanediol)titanium, titanium isobutoxide, tetraisopropyl titanate, tetraethyl titanate, n-propyl titanate, monoalkoxy titanate and titanate chelate;

[0013] The molar ratio of the silane coupling agent to the titanate is (0.5-5):1;

[0014] The polymerization temperature is 40-60°C;

[0015] The polymerization reaction is carried out for 1-8 hours.

[0016] The second aspect of the present invention provides an adhesion promoter prepared by the method described in the first aspect of the present invention.

[0017] In one or more embodiments, the number average molecular weight of the adhesion promoter is 400-2400; and / or, in the adhesion promoter, the molar ratio of Si atoms to Ti atoms is (1-3):1.

[0018] The third aspect of the present invention provides an encapsulation film composition, which includes a base resin, a main cross-linking agent, an auxiliary cross-linking agent, a silane coupling agent, an antioxidant, a light stabilizer, and the adhesion promoter described in the second aspect of the present invention.

[0019] In one or more embodiments, in the encapsulating film composition, the mass ratio of the adhesion promoter to the base resin is (0.1-0.6):100; and / or, in parts by weight, the encapsulating film composition comprises:

[0020] Base resin: 100 parts;

[0021] Main cross-linking agent: 0.4-0.8 parts;

[0022] Cross-linking agent: 0.4-1.5 parts;

[0023] Silane coupling agent: 0.1-0.8 parts;

[0024] Adhesion promoter: 0.1-0.6 parts;

[0025] Antioxidant: 0.01-0.1 parts;

[0026] Light stabilizer: 0.05-0.2 parts.

[0027] In one or more embodiments, the encapsulating film composition has one or more of the following features:

[0028] The matrix resin is selected from one or more of ethylene-vinyl acetate copolymer, elastomer obtained by random copolymerization of ethylene and α-olefin, ethylene-vinyl acetate copolymer, polyethylene, ethylene propylene copolymer, ethylene butene copolymer, ethylene pentene copolymer, ethylene octene copolymer, ethylene methyl acrylate copolymer and ethylene methyl methacrylate copolymer;

[0029] The main cross-linking agent is selected from one or both of tert-butyl peroxycarbonate-2-ethylhexyl ester and tert-amyl peroxy (2-ethylhexyl) carbonate;

[0030] The auxiliary crosslinking agent is selected from one or both of triallyl isocyanurate and trimethylolpropane triacrylate;

[0031] The silane coupling agent is selected from one or more of 3-(methacryloyloxy)propyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, vinyltrimethoxysilane, 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane;

[0032] The antioxidant is β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate octadecyl alcohol ester;

[0033] The light stabilizer is bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate.

[0034] A fourth aspect of the present invention provides a packaging adhesive film, wherein the packaging adhesive film comprises a film layer made of the packaging adhesive film composition according to the third aspect of the present invention.

[0035] In one or more embodiments, the encapsulation film has one or more of the following features:

[0036] The thickness of the packaging film is 100-800 μm;

[0037] The packaging film has a single-layer structure or a double-layer structure. One layer of the single-layer structure and the double-layer structure is prepared from the packaging film composition, and the other layer of the double-layer structure is prepared from another film composition.

[0038] According to a fifth aspect of the present invention, a HJT battery assembly is provided, wherein the HJT battery assembly comprises the packaging film according to the fourth aspect of the present invention.

[0039] The present invention has the following beneficial effects:

[0040] 1. The present invention analyzes for the first time the possible reasons for the poor adhesion between conventional adhesive films and the ITO film on the surface of HJT batteries, and proposes the use of an adhesion promoter containing an organic titanate that is easily coupled with acid hydroxyl groups, thereby achieving effective chemical bonding between the encapsulation adhesive film and the ITO film.

[0041] 2. The encapsulating film composition of the present invention only changes the adhesion promoter system, and has little effect on other properties of the encapsulating film composition. That is, the organic titanate used for viscosity enhancement only needs to be simply modified, and there is no adverse conflict reaction with the auxiliary agent system of the polyolefin film, and the original extrusion process of the film will not be changed, and the manufacturing difficulty will not be increased.

[0042] 3. The encapsulation film of the present invention greatly enhances the long-term reliability of HJT battery components, solves the problem of poor adhesion between the photovoltaic encapsulation film using an adhesion promoter system mainly composed of silane coupling agents and the ITO film on the surface of the heterojunction battery due to lack of effective chemical bonding force, avoids aging delamination of the encapsulation film and the battery and the generation of high-temperature hot spots, ensures the long-term aging reliability of the HJT battery component, and enhances its outdoor service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is a schematic diagram of the hydroxylation of ITO surface, where 1-indium atom, 2-oxygen atom.

[0044] Figure 2 Schematic diagram of the structure of an adhesion promoter with a Si / Ti atomic molar ratio of 1:1.

[0045] Figure 3 Schematic diagram of the structure of an adhesion promoter with a Si / Ti atomic molar ratio of 2:1.

[0046] Figure 4 Schematic diagram of the structure of an adhesion promoter with a Si / Ti atomic molar ratio of 3:1. DETAILED DESCRIPTION

[0047] In order to enable those skilled in the art to understand the characteristics and effects of the present invention, the following is a general description and definition of the terms and expressions mentioned in the specification. Unless otherwise specified, all technical and scientific terms used in the text are the common meanings understood by those skilled in the art for the present invention. In the event of a conflict, the definition in this specification shall prevail.

[0048] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.

[0049] Herein, “comprising”, “including”, “containing” and similar terms encompass the meanings of “consisting essentially of” and “consisting of”. For example, when “A comprises B and C” is disclosed herein, “A consists essentially of B and C” and “A consists of B and C” should be deemed to be disclosed herein.

[0050] In this article, all features such as values, quantities, contents and concentrations defined in the form of numerical ranges or percentage ranges are only for brevity and convenience. Accordingly, the description of numerical ranges or percentage ranges should be considered to have included and specifically disclosed all possible secondary ranges and individual values ​​within the range (including integers and fractions).

[0051] In this document, unless otherwise specified, percentage refers to mass percentage and ratio refers to mass ratio.

[0052] Herein, when describing embodiments or examples, it should be understood that they are not used to limit the present invention to these embodiments or examples. On the contrary, all substitutes, improvements and equivalents of the methods and materials described in the present invention can be included in the scope defined by the present invention.

[0053] In this document, in order to make the description concise, not all possible combinations of various technical features in various embodiments or examples are described. Therefore, as long as there is no contradiction in the combination of these technical features, the various technical features in various embodiments or examples can be combined arbitrarily, and all possible combinations should be considered to be within the scope of this specification.

[0054] The present invention introduces the adhesion promoter of the present invention into the packaging film system by analyzing that the surface hydroxylation of the ITO film of the HJT battery is mainly the acid hydroxyl group of the oxygen ion adsorbing protons. The organic titanate and the silane coupling agent are mixed and pre-treated with polycondensation to obtain the adhesion promoter of the present invention. The adhesion promoter of the present invention is effectively chemically bonded with ITO through the titanate part, and cross-linked with the base material polyolefin elastomer by means of the carbon-carbon double bond, epoxy group, amino group, thiol group and other active groups on the polycondensation silane coupling agent part, so as to achieve effective chemical bonding between the HJT battery and the packaging film, improve the bonding force between the packaging film and the HJT battery, avoid the risk of aging debonding and high-temperature hot spots in the components, and ensure the long-term reliability of the HJT battery components.

[0055] Adhesion promoter and preparation method thereof

[0056] The invention provides an adhesion promoter, which is a polymer obtained by polymerization of a silane coupling agent and a titanate through a polymerization reaction.

[0057] In the adhesion promoter, the molar ratio of Si atoms to Ti atoms may be (1-3):1, such as 1:1, 2:1, or 3:1, or in a range between any two values, preferably (2-3):1. In one or more embodiments, the structure of the adhesion promoter is as follows Figure 2-4 As shown, R is a substituent of a silane coupling agent commonly used in the art, which contains active groups such as carbon-carbon double bonds, epoxy groups, amino groups, and mercapto groups.

[0058] In some embodiments, the number average molecular weight of the adhesion promoter is 400-2400, such as 600, 800, 1000, 1500, 1800, 2100, 2400, or a range between any two values, preferably 500-1000, 600-1500, 700-1200 or 750-1000.

[0059] The invention also provides a method for preparing the adhesion promoter, which comprises polymerizing a silane coupling agent and a titanate to obtain the adhesion promoter of the invention.

[0060] In some embodiments, the silane coupling agent is selected from one or more of 3-methacryloxypropylmethyldimethoxysilane, 3-(methacryloxy)propyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, vinyltrimethoxysilane, 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane; preferably one or two of 3-(methacryloxy)propyltrimethoxysilane and 3-methacryloxypropylmethyldimethoxysilane.

[0061] In some embodiments, the titanate is a coupling agent commonly used in the art that is easy to couple with an acid hydroxyl group, and can effectively chemically bond with indium tin oxide. The titanate is selected from one or more of methyl titanate, tetra(2-ethyl-1,3-hexanediol)titanium, isobutoxide titanium, tetraisopropyl titanate, tetraethyl titanate, n-propyl titanate, monoalkoxy titanate, and titanate chelate. In some embodiments, the titanate is tetraisopropyl titanate.

[0062] In some embodiments, the molar ratio of the silane coupling agent to the titanate is (0.5-5):1, for example, 0.5:1, 1:1, 2:1, 3:1, 5:1, or between any two numerical ranges, preferably (1-3):1. In some embodiments, in the method for preparing the adhesion promoter, the amount of the silane coupling agent and the titanate is, by weight, 45-75 parts of silane coupling agent; 25-55 parts of titanate. In some embodiments, in the method for preparing the adhesion promoter, the amount of the silane coupling agent is 45-71 parts by weight. In some embodiments, in the method for preparing the adhesion promoter, the amount of the titanate is 29-55 parts by weight.

[0063] In some embodiments, the polymerization temperature is 40-60°C.

[0064] In some embodiments, the polymerization reaction is carried out for 1-8 hours, preferably 2-6 hours.

[0065] In some embodiments, the preparation method of the adhesion promoter is as follows: a silane coupling agent and a titanate are mixed according to a ratio, heated to 40-60° C., and stirred for 1-8 hours to obtain the adhesion promoter.

[0066] Encapsulation film composition

[0067] The invention provides a packaging film composition, which comprises a base resin, a main cross-linking agent, an auxiliary cross-linking agent, a silane coupling agent, an antioxidant, a light stabilizer, and the adhesion promoter of the invention.

[0068] In some embodiments, the base resin is selected from one or more of ethylene-vinyl acetate copolymer (EVA), elastomer obtained by random copolymerization of ethylene and α-olefin (POE), ethylene-vinyl acetate copolymer, polyethylene, ethylene propylene copolymer, ethylene butene copolymer, ethylene pentene copolymer, ethylene octene copolymer, ethylene methyl acrylate copolymer and ethylene methyl methacrylate copolymer; preferably one or two of EVA and POE.

[0069] In some embodiments, the primary cross-linking agent is selected from one or both of tert-butyl peroxycarbonate-2-ethylhexyl ester and tert-amyl peroxy(2-ethylhexyl)carbonate.

[0070] In some embodiments, the auxiliary cross-linking agent is selected from one or both of triallyl isocyanurate and trimethylolpropane triacrylate.

[0071] In some embodiments, the silane coupling agent is selected from one or more of 3-methacryloxypropylmethyldimethoxysilane, 3-(methacryloxy)propyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, vinyltrimethoxysilane, 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane; preferably 3-(methacryloxy)propyltrimethoxysilane.

[0072] In some embodiments, the antioxidant is octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate.

[0073] In some embodiments, the photostabilizer is bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate.

[0074] In some embodiments, in the encapsulating film composition, the mass ratio of the adhesion promoter to the base resin is (0.1-0.6):100, preferably (0.2-0.4):100.

[0075] In some embodiments, the encapsulation film composition comprises, by weight:

[0076] Base resin: 100 parts;

[0077] Main cross-linking agent: 0.4-0.8 parts;

[0078] Cross-linking agent: 0.4-1.5 parts;

[0079] Silane coupling agent: 0.1-0.8 parts;

[0080] Adhesion promoter: 0.1-0.6 parts;

[0081] Antioxidant: 0.01-0.1 parts;

[0082] Light stabilizer: 0.05-0.2 parts.

[0083] Preferably, the encapsulation film composition comprises, by weight:

[0084] Base resin: 100 parts;

[0085] Main cross-linking agent: 0.6-0.8 parts;

[0086] Cross-linking agent: 1.0-1.4 parts;

[0087] Silane coupling agent: 0.1-0.4 parts;

[0088] Adhesion promoter: 0.2-0.4 parts;

[0089] Antioxidant: 0.01-0.05 parts;

[0090] Light stabilizer: 0.1-0.2 parts.

[0091] Packaging film and HJT battery components

[0092] The invention provides a packaging adhesive film, which comprises a film layer made of the packaging adhesive film composition of the invention.

[0093] In some embodiments, the thickness of the packaging film is 100-800 μm, preferably 300-600 μm, for example 500 μm.

[0094] The encapsulation film of the present invention has a single-layer structure or a double-layer structure. One layer of the single-layer structure and the double-layer structure is prepared from the encapsulation film composition of the present invention, and the other layer of the double-layer structure is prepared from other film compositions. Other film compositions are common compositions in the field of films and may include a base resin, a primary cross-linking agent, an auxiliary cross-linking agent, a silane coupling agent, an antioxidant, and a light stabilizer. In some embodiments, the base resin, the primary cross-linking agent, the auxiliary cross-linking agent, the silane coupling agent, the antioxidant, and the light stabilizer are as described in any embodiment of the present invention. The encapsulation film composition and the optional other film compositions can be prepared into an encapsulation film by conventional methods in the art, for example, using a single / twin screw extruder to cast a film under heating conditions. In some embodiments, the preparation is carried out at 80-110°C, for example, 90°C.

[0095] It is necessary to control the amount of adhesion promoter added within the range defined in the present invention. If the amount of adhesion promoter added is too little, the effect of improving the bonding force between the encapsulation film and the HJT cell is not obvious. For an encapsulation film with a single-layer structure, all of its raw materials are the encapsulation film composition of the present invention. If the amount of adhesion promoter added is too much, it is not conducive to the bonding between the encapsulation film and the glass because it cannot effectively bond with the silanol group of the glass. An encapsulation film with a double-layer structure does not have the above problems, but the cost of the double-layer structure will increase compared to the single-layer structure.

[0096] The present invention also provides a HJT battery assembly, which includes the packaging adhesive film of the present invention.

[0097] application

[0098] The invention provides application of an adhesion promoter and a packaging adhesive film composition in preparing the packaging adhesive film of the invention.

[0099] The present invention provides application of an adhesion promoter and a packaging adhesive film composition in improving the bonding force between the packaging adhesive film of the present invention and an HJT battery sheet.

[0100] The present invention provides an application of an adhesion promoter and an encapsulation film composition in improving the peeling strength between an encapsulation film and a HJT cell sheet. In some embodiments, the peeling strength is greater than 30 N / cm, preferably 35-90 N / cm or 39-86 N / cm.

[0101] The present invention provides an application of an adhesion promoter and an encapsulation film composition in improving the peel strength between an encapsulation film and an HJT cell after aging. In some embodiments, the peel strength is >31 N / cm, preferably 35-80 N / cm or 43-69 N / cm. In some embodiments, the aging temperature is 100-250°C, preferably 150-200°C, for example 180°C. In some embodiments, the aging time is 1-24h, preferably 2-10h, for example 2h.

[0102] The present invention also provides application of the packaging adhesive film of the present invention in improving the reliability of HJT battery components.

[0103] In the national standard, the peel strength between the encapsulation film and the glass is above 60N / cm. Generally, those skilled in the art believe that the peel strength between the encapsulation film and the HJT cell is above 30N / cm and can be used in actual production.

[0104] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. The experimental methods in the following examples without specifying specific conditions are usually based on conventional conditions or the conditions recommended by the manufacturer. Unless otherwise stated, percentages and parts are calculated by weight.

[0105] In the present invention, the number average molecular weight is measured by gel permeation chromatography.

[0106] Preparation Example 1

[0107] The adhesion promoter was prepared according to the following ratio and method: 71 parts of 3-(methacryloyloxy)propyltrimethoxysilane and 29 parts of tetraisopropyl titanate were mixed (molar ratio 3:1), heated to 60°C, and rotated and stirred for 4 hours to obtain the adhesion promoter. The molar ratio of Si atoms to Ti atoms in the adhesion promoter was 3:1, and the number average molecular weight of the adhesion promoter was about 1000.

[0108] Preparation Example 2

[0109] The adhesion promoter was prepared according to the following ratio and method: 45 parts of 3-(methacryloyloxy)propyltrimethoxysilane and 55 parts of tetraisopropyl titanate were mixed (molar ratio of 1:1), heated to 60°C, and stirred for 2 hours to obtain the adhesion promoter. The molar ratio of Si atoms to Ti atoms in the adhesion promoter was 1:1, and the number average molecular weight of the adhesion promoter was about 500.

[0110] Preparation Example 3

[0111] The adhesion promoter was prepared according to the following ratio and method: 62 parts of 3-methacryloxypropylmethyldimethoxysilane and 38 parts of tetraisopropyl titanate were mixed (molar ratio 2:1), heated to 40°C, and stirred for 6 hours to obtain the adhesion promoter. The molar ratio of Si atoms to Ti atoms in the adhesion promoter was 2:1, and the number average molecular weight of the adhesion promoter was about 750.

[0112] Example 1

[0113] The encapsulation film of this embodiment is a single-layer structure. The specific composition of the encapsulation film composition is shown in Table 1, and the adhesion promoter is the adhesion promoter prepared in Preparation Example 1.

[0114] The encapsulation film composition of this embodiment is obtained by the following preparation method: all the additives (main cross-linking agent, auxiliary cross-linking agent, silane coupling agent, adhesion promoter, antioxidant, light stabilizer, types and proportions as shown in Table 1) except the base resin are mixed uniformly in proportion, and at the same time, a specific number of EVA or POE particles are placed in a stirring tank, and stirring is continued. The mixed additives are uniformly sprayed on the base resin particles within 1 hour. After the additives are completely sprayed, stirring is continued for 6 hours. The material needs to be returned 3 times in the middle to prevent the additives from being at the bottom of the stirring tank.

[0115] The encapsulation film of this embodiment is obtained by the following preparation method: depositing the encapsulation film composition prepared according to the above method, standing at room temperature for 12 hours to allow the additive to be completely absorbed, and directly casting into a film at 90° C. using a single / twin screw extruder.

[0116] Example 2

[0117] The packaging film of this embodiment has a single-layer structure.

[0118] The method of Example 1 was repeated to prepare a packaging film, except that: the specific composition of the packaging film composition is shown in Table 1, and the adhesion promoter is the adhesion promoter prepared in Preparation Example 1.

[0119] Example 3

[0120] The packaging film of this embodiment has a single-layer structure.

[0121] The method of Example 1 was repeated to prepare a packaging film, except that: the specific composition of the packaging film composition is shown in Table 1, and the adhesion promoter is the adhesion promoter prepared in Preparation Example 1.

[0122] Example 4

[0123] The packaging film of this embodiment has a single-layer structure.

[0124] The method of Example 1 was repeated to prepare a packaging film, except that: the specific composition of the packaging film composition is shown in Table 1, and the adhesion promoter is the adhesion promoter prepared in Preparation Example 2.

[0125] Example 5

[0126] The packaging film of this embodiment has a single-layer structure.

[0127] The method of Example 1 was repeated to prepare a packaging film, except that: the specific composition of the packaging film composition is shown in Table 1, and the adhesion promoter is the adhesion promoter prepared in Preparation Example 2.

[0128] Example 6

[0129] The packaging film of this embodiment has a single-layer structure.

[0130] The method of Example 1 was repeated to prepare a packaging film, except that: the specific composition of the packaging film composition is shown in Table 1, and the adhesion promoter is the adhesion promoter prepared in Preparation Example 3.

[0131] Example 7

[0132] The packaging film of this embodiment has a single-layer structure.

[0133] The method of Example 1 was repeated to prepare a packaging film, except that: the specific composition of the packaging film composition is shown in Table 1, and the adhesion promoter is the adhesion promoter prepared in Preparation Example 3.

[0134] Example 8

[0135] The packaging film of this embodiment has a double-layer structure.

[0136] The method of Example 1 was repeated to prepare a packaging film, except that: the specific compositions of the two packaging film compositions are shown in Table 1, and the adhesion promoter is the adhesion promoter prepared in Preparation Example 1.

[0137] Example 9

[0138] The packaging film of this embodiment has a double-layer structure.

[0139] The method of Example 1 was repeated to prepare a packaging film, except that: the specific compositions of the two packaging film compositions are shown in Table 1, and the adhesion promoter is the adhesion promoter prepared in Preparation Example 1.

[0140] Comparative Example 1

[0141] The packaging film of this comparative example has a single-layer structure.

[0142] The method of Example 1 was repeated to prepare an encapsulating film, except that no adhesion promoter was added. The specific composition of the encapsulating film composition is shown in Table 1.

[0143] Comparative Example 2

[0144] The packaging film of this comparative example has a single-layer structure.

[0145] The method of Example 1 was repeated to prepare an encapsulating film, except that the adhesion promoter in the film composition of this comparative example was tetraisopropyl titanate that had not been polycondensed with a silane coupling agent. The specific composition of the encapsulating film composition is shown in Table 1.

[0146] Comparative Example 3

[0147] The packaging film of this comparative example has a single-layer structure.

[0148] The method of Example 1 was repeated to prepare a packaging film, except that: the specific composition of the packaging film composition is shown in Table 1, and the adhesion promoter is the adhesion promoter prepared in Preparation Example 1.

[0149] Comparative Example 4

[0150] The packaging film of this comparative example has a single-layer structure.

[0151] The method of Example 1 was repeated to prepare an encapsulating film, except that no adhesion promoter was added. The specific composition of the encapsulating film composition is shown in Table 1.

[0152] Table 1: Specific components of the encapsulation films in Examples 1-9 and Comparative Examples 1-4

[0153]

[0154]

[0155] The specific model of EVA in the table is Taiju UE2828, POE is Dow 8130, main cross-linking agent-1 is tert-butyl peroxycarbonate-2-ethylhexyl ester (TBEC), main cross-linking agent-2 is tert-amyl peroxy (2-ethylhexyl) carbonate (TAEC), auxiliary cross-linking agent-1 is triallyl isocyanurate (TAIC), auxiliary cross-linking agent-2 is trimethylolpropane triacrylate (TMPTA), silane coupling agent is 3-(methacryloyloxy)propyltrimethoxysilane (KH570), antioxidant is β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate (1076), and light stabilizer is bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate (UV770).

[0156] Performance testing and methods

[0157] 1. Peel strength between encapsulation film and glass: According to the national standard GB / T29848-2018 for photovoltaic encapsulation film and the 180° peel strength test method of adhesive in GB / T2790-1995, the encapsulation film was made into a laminate (200mm*100mm), masking paper was placed between EVA and embossed glass, and laminated and cured at 148°C for 18 minutes. After cooling, the grid mold was placed on the backplane surface, and a small strip (15mm wide) was cut with a utility knife to separate EVA from the embossed glass. The laminate was clamped in the lower fixture to test the peel strength between EVA and the embossed glass (180° peeling, speed 100mm / min).

[0158] 2. Peel strength between encapsulation film and cell: Take 3mm thick glass, heterojunction cell, encapsulation film, backplane, stack them in the order of glass / film / cell / isolation strip / encapsulation film / backplane to form laminated parts, put them into vacuum laminator, and laminate and cure at 148℃ for 18min. Test on tensile machine with peel speed of 100mm / min, record peel strength value, and use it to characterize the interfacial adhesion between encapsulation film and cell.

[0159] 3. The packaging films obtained in the above Examples 1-9 and Comparative Examples 1-4 were made into the above-mentioned battery adhesion test laminates, and subjected to aging tests in a high-temperature oven (temperature 180° C.) for 2 hours, and the adhesion data after aging were measured on a tensile testing machine.

[0160] The performance test results are shown in Table 2 below.

[0161] Table 2: Performance test results of the encapsulation films in Examples 1-9 and Comparative Examples 1-4

[0162]

[0163]

[0164] Comparing Examples 1-9 with Comparative Examples 1-4, it can be seen that the encapsulation film composition of the present invention, in which the adhesion promoter is obtained by prepolymerization of a silane coupling agent and an organic titanate, can be used to prepare an encapsulation film with improved adhesion to a heterojunction battery.

[0165] By comparing Examples 1, 4, and 6 with Examples 2, 5, and 7, it can be seen that when the amount of the prepared adhesion promoter added is increased or the proportion of tetraisopropyl titanate therein is increased, the adhesion between the encapsulation film and the heterojunction battery is improved, but the adhesion with the glass is reduced.

[0166] Comparing Examples 1, 4 and 6, and comparing Examples 2, 5 and 7, the adhesion promoter prepared in Preparation Example 1 has the best improvement effect on the encapsulation film, followed by the encapsulation film prepared in Preparation Example 3, and finally the encapsulation film prepared in Preparation Example 2. The laminates prepared using the encapsulation films prepared in Preparation Examples 1 and 3 meet the requirements of the peeling strength between the existing encapsulation film and glass, and also meet the requirements of the peeling strength between the existing encapsulation film and the HJT cell.

[0167] It can be seen from Examples 8 and 9 that when the encapsulation film is made into a double-layer structure and an adhesion promoter is added only to the layer in contact with the battery, the adhesion with the heterojunction battery can be improved without affecting the adhesion with the glass.

[0168] Comparing Comparative Example 1 and Comparative Example 3, it can be seen that when the content of the adhesion promoter of the present invention is very small, the peel strength between the encapsulation film and the HJT battery cell and the peel strength between the encapsulation film and the HJT battery cell after baking at 180°C*2h are not effectively improved.

Claims

1. A method for preparing an adhesion promoter, characterized in that: The method comprises polymerizing a silane coupling agent and a titanate to obtain the adhesion promoter.

2. The method according to claim 1, characterized in that The method has one or more of the following features: The silane coupling agent is selected from one or more of 3-(methacryloyloxy)propyltrimethoxysilane, 3-glycidyloxypropyltrimethoxysilane, vinyltrimethoxysilane, 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane; The titanate is selected from one or more of methyl titanate, tetrakis(2-ethyl-1,3-hexanediol)titanium, titanium isobutoxide, tetraisopropyl titanate, tetraethyl titanate, n-propyl titanate, monoalkoxy titanate and titanate chelate; The molar ratio of the silane coupling agent to the titanate is (0.5-5):1, preferably (1-3):1; The polymerization temperature is 40-60°C; The polymerization reaction is carried out for 1-8 hours, preferably 2-6 hours.

3. An adhesion promoter prepared by the method according to claim 1 or 2; preferably, the number average molecular weight of the adhesion promoter is 500-1000.

4. The adhesion promoter according to claim 3, characterized in that The number average molecular weight of the adhesion promoter is 400-2400; and / or, in the adhesion promoter, the molar ratio of Si atoms to Ti atoms is (1-3):

1.

5. A packaging film composition, characterized in that: The encapsulating film composition comprises a base resin, a main cross-linking agent, an auxiliary cross-linking agent, a silane coupling agent, an antioxidant, a light stabilizer, and the adhesion promoter according to claim 3 or 4.

6. The encapsulating film composition according to claim 5, characterized in that: In the encapsulating film composition, the mass ratio of the adhesion promoter to the base resin is (0.1-0.6):100; and / or, in parts by weight, the encapsulating film composition comprises: Base resin: 100 parts; Main cross-linking agent: 0.4-0.8 parts; Cross-linking agent: 0.4-1.5 parts; Silane coupling agent: 0.1-0.8 parts; Adhesion promoter: 0.1-0.6 parts; Antioxidant: 0.01-0.1 parts; Light stabilizer: 0.05-0.2 parts.

7. The encapsulating film composition according to claim 5, characterized in that: The encapsulating film composition has one or more of the following characteristics: The matrix resin is selected from one or more of ethylene-vinyl acetate copolymer, elastomer obtained by random copolymerization of ethylene and α-olefin, ethylene-vinyl acetate copolymer, polyethylene, ethylene propylene copolymer, ethylene butene copolymer, ethylene pentene copolymer, ethylene octene copolymer, ethylene methyl acrylate copolymer and ethylene methyl methacrylate copolymer; The main cross-linking agent is selected from one or both of tert-butyl peroxycarbonate-2-ethylhexyl ester and tert-amyl peroxy (2-ethylhexyl) carbonate; The auxiliary crosslinking agent is selected from one or both of triallyl isocyanurate and trimethylolpropane triacrylate; The silane coupling agent is selected from one or more of 3-(methacryloyloxy)propyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, vinyltrimethoxysilane, 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane; The antioxidant is β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate octadecyl alcohol ester; The light stabilizer is bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate.

8. A packaging film, characterized in that: The encapsulation film comprises a film layer made from the encapsulation film composition according to any one of claims 5 to 7.

9. The packaging film according to claim 8, characterized in that: The thickness of the packaging film is 100-800 μm; and / or the packaging film has a single-layer structure or a double-layer structure, one layer of the single-layer structure and the double-layer structure is prepared from the packaging film composition, and the other layer of the double-layer structure is prepared from other film compositions.

10. A HJT battery assembly, characterized in that: The HJT battery assembly includes the packaging film according to claim 8 or 9.

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