A high-adhesive photovoltaic encapsulation film and its preparation method and application

Abstract

The present invention relates to the technical field of photovoltaic films, and discloses a photovoltaic encapsulation film with high adhesion, a preparation method thereof, and an application thereof. The raw materials of one side of the photovoltaic encapsulation film that is bonded to the glass in a photovoltaic module include a matrix resin, an organic peroxide initiator, and a liquid polyepoxy small molecule; the temperature at which the organic peroxide initiator is pyrolyzed to generate free radicals and carbon dioxide is not higher than the lamination temperature of the photovoltaic module, and is not lower than the preparation temperature of the photovoltaic encapsulation film. The photovoltaic encapsulation film of the present invention has good adhesion performance, can achieve a high bonding strength with the glass, and can still maintain good adhesion after aging.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic adhesive films, and in particular to a photovoltaic encapsulation adhesive film with high adhesion, a preparation method thereof and applications thereof. Background Art

[0002] As a key auxiliary material for protecting photovoltaic cells, the encapsulation film has an especially important bonding performance to avoid delamination of photovoltaic modules during long-term outdoor operation. At present, the main matrix resins of the film are ethylene-vinyl acetate copolymer (EVA) and ethylene-α-olefin copolymer (POE). These two resins are polymer materials with low polarity and poor cohesive strength. POE is a non-polar material in particular, and has poor bonding performance with glass. Especially after wet heat aging, water vapor will enter along the interface between the film and the glass, and the film will absorb water and swell, resulting in weakened peel strength between the film and the glass at the interface or even delamination. In order to ensure that the film continues to protect photovoltaic cells, it is necessary to improve its bonding performance, especially the bonding performance after PCT aging.

[0003] In the prior art, silane coupling agents or silane grafting materials are usually added to the adhesive film to improve the bonding performance between the adhesive film and the glass. However, in these existing solutions, the peel strength between the adhesive film and the glass after aging is low, and the peel strength after PCT 48 hours is no more than 60 N / cm. Summary of the invention

[0004] In order to solve the technical problem of poor bonding performance between existing photovoltaic encapsulation adhesive films and glass, the present invention provides a photovoltaic encapsulation adhesive film with high bonding performance and a preparation method and application thereof. The photovoltaic encapsulation adhesive film of the present invention has good bonding performance, can achieve high bonding strength with glass, and can still maintain good bonding after aging.

[0005] The specific technical scheme of the present invention is:

[0006] In a first aspect, the present invention provides a highly adhesive photovoltaic encapsulation film, wherein the raw materials of one side of the photovoltaic encapsulation film that is bonded to the glass in a photovoltaic module include a matrix resin, an organic peroxide initiator, and a liquid polyepoxy small molecule; the temperature at which the organic peroxide initiator pyrolyzes to produce free radicals and carbon dioxide is no higher than the lamination temperature of the photovoltaic module and no lower than the preparation temperature of the photovoltaic encapsulation film.

[0007] The present invention uses an organic peroxide initiator and a liquid polyepoxy small molecule in the raw materials, which can produce the following effects: in the lamination process of assembling the adhesive film into a photovoltaic module, the organic peroxide initiator is pyrolyzed to produce free radicals and carbon dioxide, wherein the free radicals initiate the matrix resin in the adhesive film to produce free radicals for bonding, and the carbon dioxide is combined to open the epoxy groups in the liquid polyepoxy small molecule, and some of the epoxy groups are bonded to the matrix resin after the ring opening, and some of the epoxy groups react with the silanol groups on the glass surface after the ring opening to form a strong chemical bond. In the above manner, under the action of the organic peroxide initiator, the liquid polyepoxy small molecule can form a covalent connection between the matrix resin in the adhesive film and the glass, thereby improving the bonding performance between the photovoltaic encapsulation adhesive film and the glass, and enabling it to maintain a high bonding strength after aging.

[0008] In addition, the polyepoxy material used in the present invention is a liquid small molecule with low viscosity, easy to disperse into the matrix resin, and high reaction activity. Therefore, compared with solid or paste epoxy resin polymers, it can play a better role in improving the bonding performance between photovoltaic encapsulation film and glass.

[0009] Preferably, the organic peroxide initiator includes at least one of tert-butyl peroxide-2-ethylhexanoate, 1,1-di-tert-butyl peroxide-3,3,5-trimethylcyclohexane, 1,1-di-tert-butyl peroxide cyclohexane, tert-amyl peroxide-2-ethylhexanoate, tert-butyl peroxide-3,5,5-trimethylhexanoate, tert-butyl peroxide-2-ethylhexanoate, tert-butyl peroxide-isopropyl carbonate, tert-butyl peroxide benzoate, butyl 4,4-bis(tert-butylperoxy)valerate, di-tert-amyl peroxide, and 2,5-di-tert-butylperoxide-2,5-dimethylhexane.

[0010] Preferably, the organic peroxide initiator comprises component a and component b in a mass ratio of 1:1-3; the temperatures at which component a and component b are pyrolyzed to generate free radicals and carbon dioxide are 120-135° C. and 137-150° C., respectively.

[0011] The present invention uses two organic peroxide initiators (component a and component b) with different pyrolysis temperatures to be compounded in a specific ratio, which can further improve the post-aging bonding strength between the adhesive film and the glass. This is because: when only component a with a lower pyrolysis temperature is used, or the proportion of the former in components a and b is too large, the matrix resin inside the adhesive film will cross-link too quickly during the hot pressing process, resulting in the adhesive film being unable to fully wet and spread on the glass, thereby adversely affecting the post-aging bonding strength between the two; when only component b with a higher pyrolysis temperature is used, or the proportion of the latter in components a and b is too large, the cross-linking speed of the adhesive film is slow. At the same time, because the liquid polyepoxy small molecules also consume free radicals, the cross-linking speed will be slower and the cross-linking degree will be smaller, which will also have an adverse effect on the aging bonding performance of the adhesive film.

[0012] Further, the component a includes at least one of tert-butyl peroxy-2-ethylhexanoate, 1,1-di-tert-butyl peroxy-3,3,5-trimethylcyclohexane, tert-butyl peroxy-3,5,5-trimethylhexanoate, 1,1-di-tert-butyl peroxycyclohexane and tert-amyl peroxycarbonate-2-ethylhexanoate, and the component b includes at least one of tert-butyl peroxycarbonate-2-ethylhexanoate, tert-butyl peroxyisopropyl carbonate, tert-butyl peroxybenzoate, 4,4-bis(tert-butylperoxy)butyl valerate, di-tert-amyl peroxide and 2,5-di-tert-butylperoxy-2,5-dimethylhexane.

[0013] Preferably, the liquid polyepoxy small molecule includes at least one of 3,4-epoxycyclohexylcarboxylic acid-3',4'-epoxycyclohexylmethyl ester, bis((3,4-epoxycyclohexyl)methyl)adipate, vinylcyclohexene dioxide, dipentene dioxide, tetrahydroindene diepoxide and di-4-epoxycyclohexane.

[0014] Preferably, the mass ratio of the liquid polyepoxy small molecule to the organic peroxide initiator is 1:1-9; the total mass of the liquid polyepoxy small molecule and the organic peroxide initiator is 0.6-1.8% of the mass of the base resin.

[0015] Preferably, the base resin contains vinyl groups.

[0016] Further, the base resin includes at least one of ethylene-vinyl acetate copolymer, ethylene-propylene acetate copolymer, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer and ethylene-α-olefin copolymer.

[0017] Preferably, the raw material of the side of the photovoltaic encapsulation film that is bonded to the glass in the photovoltaic module also includes at least one of a cross-linking agent, a silane coupling agent, an anti-PID agent and an anti-aging agent.

[0018] In a second aspect, the present invention provides a method for preparing the photovoltaic encapsulation film, comprising the following steps:

[0019] S1: Mix the organic peroxide initiator and the liquid polyepoxy small molecule, mix with the base resin, and fully absorb;

[0020] S2: Add other raw materials of photovoltaic encapsulation film to the product obtained in step S1, and extrude and form a film after it is fully absorbed.

[0021] In the above preparation process, after the organic peroxide initiator and the liquid polyepoxy small molecule are mixed and absorbed by the matrix resin, they are then mixed with other raw materials, which can make the distribution positions of the organic peroxide initiator and the liquid polyepoxy small molecule in the film closer, which helps the liquid polyepoxy small molecule to form covalent bonds with the matrix resin and glass under the action of the organic peroxide initiator during lamination. Therefore, the above preparation method can further improve the bonding strength between the photovoltaic encapsulation film and the glass.

[0022] Preferably, in step S1, the method for sufficient absorption is stirring at 45-50°C and 60-70 rpm for 2-2.5 h; in step S2, the method for sufficient absorption is stirring at 45-50°C and 60-70 rpm for 10-12 h.

[0023] Preferably, in step S2, the temperature of the extrusion film forming is 80-100°C.

[0024] In a third aspect, the present invention provides an application of the photovoltaic encapsulation film in a photovoltaic module, and the preparation process of the photovoltaic module includes: stacking the backboard, photovoltaic encapsulation film, battery cell, photovoltaic encapsulation film and glass in order from bottom to top, and laminating at 140~150°C.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] (1) The present invention uses an organic peroxide initiator and a liquid polyepoxy small molecule in the adhesive film raw material. During the lamination process of preparing photovoltaic modules, the liquid polyepoxy small molecule can form a covalent connection between the adhesive film matrix resin and the glass under the action of free radicals and carbon dioxide generated by the pyrolysis of the organic peroxide initiator, thereby improving the bonding performance between the photovoltaic encapsulation adhesive film and the glass, and enabling it to maintain a high bonding strength after aging.

[0027] (2) The present invention can further improve the post-aging bonding strength between the adhesive film and the glass by using two organic peroxide initiators (component a and component b) with different pyrolysis temperatures and compounding them in a specific ratio.

[0028] (3) In the process of preparing the photovoltaic encapsulation film of the present invention, after the organic peroxide initiator and the liquid polyepoxy small molecules are mixed and absorbed by the matrix resin, they are mixed with other raw materials. This can promote the organic peroxide initiator and the liquid polyepoxy small molecules to play their roles, thereby improving the bonding performance between the photovoltaic encapsulation film and the glass to a greater extent. DETAILED DESCRIPTION

[0029] The present invention will be further described below in conjunction with the embodiments.

[0030] A photovoltaic encapsulation film with high adhesion, wherein the raw materials of one side of the photovoltaic encapsulation film that is bonded to the glass in a photovoltaic module include a matrix resin, an organic peroxide initiator and liquid polyepoxy small molecules; the temperature at which the organic peroxide initiator is pyrolyzed to generate free radicals and carbon dioxide is not higher than the lamination temperature of the photovoltaic module and is not lower than the preparation temperature of the photovoltaic encapsulation film.

[0031] As a specific embodiment, the organic peroxide initiator includes at least one of tert-butyl peroxy-2-ethylhexyl carbonate, tert-amyl peroxy-2-ethylhexyl carbonate, bis(3,5,5-trimethylhexanoyl) peroxide, tert-butyl peroxy isononanoate, tert-butyl peroxy-2-ethylhexanoate and tert-butyl peroxy isopropyl carbonate.

[0032] As a specific embodiment, the organic peroxide initiator includes component a and component b in a mass ratio of 1:1-3. The temperatures at which component a and component b are pyrolyzed to generate free radicals and carbon dioxide are 120-135°C and 137-150°C, respectively. Component a includes at least one of tert-butyl peroxy-2-ethylhexanoate, 1,1-di-tert-butyl peroxy-3,3,5-trimethylcyclohexane, tert-butyl peroxy-3,5,5-trimethylhexanoate, 1,1-di-tert-butyl peroxycyclohexane and tert-amyl peroxycarbonate-2-ethylhexanoate, and component b includes at least one of tert-butyl peroxycarbonate-2-ethylhexanoate, tert-butyl peroxyisopropylcarbonate, tert-butyl peroxybenzoate, butyl 4,4-bis(tert-butylperoxy)valerate, di-tert-amyl peroxide and 2,5-di-tert-butylperoxy-2,5-dimethylhexane.

[0033] As a specific embodiment, the liquid polyepoxy small molecule includes at least one of 3,4-epoxycyclohexylcarboxylic acid-3',4'-epoxycyclohexyl methyl ester, bis((3,4-epoxycyclohexyl)methyl)adipate, vinylcyclohexene dioxide, dipentene dioxide, tetrahydroindene diepoxide and di-4-epoxycyclohexane.

[0034] As a specific implementation manner, the mass ratio of the liquid polyepoxy small molecule to the organic peroxide initiator is 1:1-10; the total mass of the liquid polyepoxy small molecule and the organic peroxide initiator is 0.1-1% of the mass of the base resin.

[0035] As a specific implementation, the base resin contains vinyl groups.

[0036] As a specific implementation, the raw material of the side of the photovoltaic encapsulation film that is bonded to the glass in the photovoltaic module also includes at least one of a cross-linking agent, a silane coupling agent, an anti-PID agent, and an anti-aging agent.

[0037] A method for preparing the photovoltaic encapsulation film comprises the following steps:

[0038] S1: Mix the organic peroxide initiator and the liquid polyepoxy small molecule, mix with the base resin, and fully absorb;

[0039] S2: Add other raw materials of photovoltaic encapsulation film to the product obtained in step S1, and extrude and form a film after it is fully absorbed.

[0040] As a specific implementation, in step S1, the method of sufficient absorption is to stir at 45-50° C. and 60-70 rpm for 2-2.5 h.

[0041] As a specific implementation, in step S2, the method of sufficient absorption is to stir at 45-50° C. and 60-70 rpm for 10-12 h.

[0042] As a specific implementation, in step S2, the temperature of the extrusion film forming is 80-100°C.

[0043] In a third aspect, the present invention provides an application of the photovoltaic encapsulation film in a photovoltaic module, and the preparation process of the photovoltaic module includes: stacking the backboard, photovoltaic encapsulation film, battery cell, photovoltaic encapsulation film and glass in order from bottom to top, and laminating at 140~150°C.

[0044] The present invention is described below by specific examples. It should be understood that these examples are only used to illustrate the present invention and are not used to limit the scope of the present invention. Without departing from the spirit and scope of the inventive concept, changes and advantages that can be thought of by those skilled in the art are included in the present invention, and the attached claims and any equivalents thereof are the protection scope of the present invention.

[0045] Example 1

[0046] A photovoltaic encapsulation film is prepared by the following steps:

[0047] S1: Weigh the following raw materials in parts by weight: 100 parts of POE resin, 0.3 parts of tert-amyl peroxycarbonate-2-ethylhexanoate (pyrolysis temperature is 134°C), 0.6 parts of tert-butyl peroxycarbonate-2-ethylhexanoate (pyrolysis temperature is 137°C), 0.9 parts of 3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexylcarboxylate, 0.9 parts of co-crosslinking agent TAIC, 0.3 parts of silane coupling agent KH570, 0.1 parts of anti-PID additive montmorillonite, and 0.2 parts of anti-aging additive UV770.

[0048] S2: tert-amyl peroxycarbonate-2-ethylhexanoate, tert-butyl peroxycarbonate-2-ethylhexanoate and 3,4-epoxycyclohexylcarboxylic acid-3',4'-epoxycyclohexylmethyl ester were added to a mixer, stirred evenly, and then POE resin was added, and stirred at 50°C and 60 rpm for 2 h. The remaining other raw materials were added to the mixer, and stirred at 50°C and 60 rpm for 10 h to obtain a mixture.

[0049] S3: Extruding and casting the mixture into a film at 90° C. to obtain a photovoltaic encapsulation film.

[0050] The photovoltaic encapsulation film prepared in this embodiment is used to prepare a photovoltaic module through the following steps: the backplane, photovoltaic encapsulation film, solar cell, photovoltaic encapsulation film and glass are stacked in order from bottom to top, and then laminated at a temperature of 145°C and a pressure of -30 kPa for 8 minutes to obtain a photovoltaic module.

[0051] Example 2

[0052] A photovoltaic encapsulation film is prepared by the following steps:

[0053] S1: Weigh the following raw materials in parts by weight: 100 parts of POE resin, 0.225 parts of 1,1-di-tert-butylperoxy-3,3,5-trimethylcyclohexane (pyrolysis temperature is 128°C), 0.225 parts of tert-butyl peroxybenzoate (pyrolysis temperature is 142°C), 0.15 parts of bis((3,4-epoxycyclohexyl)methyl)adipate, 0.9 parts of co-crosslinking agent TAIC, 0.3 parts of silane coupling agent KH570, 0.1 parts of anti-PID additive montmorillonite, and 0.2 parts of anti-aging additive UV770.

[0054] S2: Add 1,1-di-tert-butylperoxy-3,3,5-trimethylcyclohexane, tert-butyl peroxybenzoate and bis((3,4-epoxycyclohexyl)methyl)adipate into a blender, stir evenly, add POE resin, and stir at 45°C at 60 rpm for 2.5 h. Add the remaining other raw materials into the blender, stir at 45°C at 60 rpm for 12 h to obtain a mixture.

[0055] S3: Extruding and casting the mixture into a film at 80° C. to obtain a photovoltaic encapsulation film.

[0056] The photovoltaic encapsulation film prepared in this embodiment is used to prepare a photovoltaic module through the following steps: the backplane, photovoltaic encapsulation film, solar cell, photovoltaic encapsulation film and glass are stacked in order from bottom to top, and then laminated at a temperature of 140°C and a pressure of -30 kPa for 15 min to obtain a photovoltaic module.

[0057] Example 3

[0058] A photovoltaic encapsulation film is prepared by the following steps:

[0059] S1: Weigh the following raw materials in parts by weight: 100 parts of POE resin, 0.15 parts of tert-butyl peroxy-3,5,5-trimethylhexanoate (pyrolysis temperature is 135°C), 0.45 parts of tert-butyl peroxycarbonate-2-ethylhexanoate (pyrolysis temperature is 137°C), 0.4 parts of vinyl cyclohexene dioxide, 0.9 parts of co-crosslinking agent TAIC, 0.3 parts of silane coupling agent KH570, 0.1 parts of anti-PID additive montmorillonite, and 0.2 parts of anti-aging additive UV770.

[0060] S2: Add tert-butyl peroxy-3,5,5-trimethylhexanoate, tert-butyl peroxycarbonate-2-ethylhexanoate and vinylcyclohexene dioxide into a mixer, stir evenly, add POE resin, and stir at 50°C at 70 rpm for 2 hours. Add the remaining other raw materials into the mixer, stir at 50°C at 70 rpm for 10 hours to obtain a mixture.

[0061] S3: Extruding and casting the mixture into a film at 100° C. to obtain a photovoltaic encapsulation film.

[0062] The photovoltaic encapsulation film prepared in this embodiment is used to prepare a photovoltaic module through the following steps: the backplane, photovoltaic encapsulation film, solar cell, photovoltaic encapsulation film and glass are stacked in order from bottom to top, and then laminated at a temperature of 150°C and a pressure of -30 kPa for 7 minutes to obtain a photovoltaic module.

[0063] Example 4

[0064] The difference between this embodiment and embodiment 1 is that in the preparation process of the photovoltaic encapsulation film, only tert-amyl peroxycarbonate-2-ethylhexanoate is added to the two organic peroxide initiators, and the amount used is the same as the total amount of tert-amyl peroxycarbonate-2-ethylhexanoate and tert-butyl peroxycarbonate-2-ethylhexanoate in embodiment 1; the rest of the raw materials and steps are the same as those in embodiment 1. Specifically, the steps of preparing the photovoltaic encapsulation film in this embodiment are as follows:

[0065] S1: Weigh the following raw materials in parts by weight: 100 parts of POE resin, 0.9 parts of tert-amyl peroxycarbonate-2-ethylhexanoate (pyrolysis temperature is 134°C), 0.9 parts of 3,4-epoxycyclohexylcarboxylic acid-3',4'-epoxycyclohexylmethyl ester, 0.9 parts of co-crosslinking agent TAIC, 0.3 parts of silane coupling agent KH570, 0.1 parts of anti-PID additive montmorillonite, and 0.2 parts of anti-aging additive UV770.

[0066] S2: tert-amyl peroxycarbonate-2-ethylhexanoate and 3,4-epoxycyclohexylcarboxylic acid-3',4'-epoxycyclohexylmethyl ester were added to a mixer, stirred evenly, and then POE resin was added, and stirred at 50°C and 60 rpm for 2 h. The remaining other raw materials were added to the mixer, and stirred at 50°C and 60 rpm for 10 h to obtain a mixture.

[0067] S3: Extruding and casting the mixture into a film at 90° C. to obtain a photovoltaic encapsulation film.

[0068] The photovoltaic encapsulation film prepared in this embodiment is used to prepare a photovoltaic module through the following steps: the backplane, photovoltaic encapsulation film, solar cell, photovoltaic encapsulation film and glass are stacked in order from bottom to top, and then laminated at a temperature of 145°C and a pressure of -30 kPa for 8 minutes to obtain a photovoltaic module.

[0069] Example 5

[0070] The difference between this embodiment and embodiment 1 is that in the process of preparing the photovoltaic encapsulation film, only tert-butyl peroxycarbonate-2-ethylhexanoate is added to the two organic peroxide initiators, and the amount used is the same as the total amount of tert-amyl peroxycarbonate-2-ethylhexanoate and tert-butyl peroxycarbonate-2-ethylhexanoate in embodiment 1; the rest of the raw materials and steps are the same as those in embodiment 1. Specifically, the steps of preparing the photovoltaic encapsulation film in this embodiment are as follows:

[0071] S1: Weigh the following raw materials in parts by weight: 100 parts of POE resin, 0.9 parts of tert-butyl peroxycarbonate-2-ethylhexanoate (thermal decomposition temperature is 137°C), 0.9 parts of 3,4-epoxycyclohexylcarboxylic acid-3',4'-epoxycyclohexylmethyl ester, 0.9 parts of co-crosslinking agent TAIC, 0.3 parts of silane coupling agent KH570, 0.1 parts of anti-PID additive montmorillonite, and 0.2 parts of anti-aging additive UV770.

[0072] S2: tert-butyl peroxycarbonate-2-ethylhexanoate and 3,4-epoxycyclohexylcarboxylic acid-3',4'-epoxycyclohexylmethyl ester were added to a mixer, stirred evenly, and then POE resin was added, and stirred at 50°C and 60 rpm for 2 h. The remaining other raw materials were added to the mixer, and stirred at 50°C and 60 rpm for 10 h to obtain a mixture.

[0073] S3: Extruding and casting the mixture into a film at 90° C. to obtain a photovoltaic encapsulation film.

[0074] The photovoltaic encapsulation film prepared in this embodiment is used to prepare a photovoltaic module through the following steps: the backplane, photovoltaic encapsulation film, solar cell, photovoltaic encapsulation film and glass are stacked in order from bottom to top, and then laminated at a temperature of 145°C and a pressure of -30 kPa for 8 minutes to obtain a photovoltaic module.

[0075] Example 6

[0076] The difference between this embodiment and embodiment 1 is that: the total amount of tert-amyl peroxycarbonate-2-ethylhexanoate and tert-butyl peroxycarbonate-2-ethylhexanoate is unchanged, the amount of the former is increased, and the amount of the latter is reduced; the rest of the raw materials and steps are the same as those in embodiment 1. Specifically, the steps of preparing the photovoltaic encapsulation film in this embodiment are as follows:

[0077] S1: Weigh the following raw materials in parts by weight: 100 parts of POE resin, 0.8 parts of tert-amyl peroxycarbonate-2-ethylhexanoate (pyrolysis temperature is 134°C), 0.1 parts of tert-butyl peroxycarbonate-2-ethylhexanoate (pyrolysis temperature is 137°C), 0.9 parts of 3,4-epoxycyclohexylcarboxylic acid-3',4'-epoxycyclohexylmethyl ester, 0.9 parts of co-crosslinking agent TAIC, 0.3 parts of silane coupling agent KH570, 0.1 parts of anti-PID additive montmorillonite, and 0.2 parts of anti-aging additive UV770.

[0078] S2: tert-amyl peroxycarbonate-2-ethylhexanoate, tert-butyl peroxycarbonate-2-ethylhexanoate and 3,4-epoxycyclohexylcarboxylic acid-3',4'-epoxycyclohexylmethyl ester were added to a mixer, stirred evenly, and then POE resin was added, and stirred at 50°C and 60 rpm for 2 hours. The remaining other raw materials were added to the mixer, and stirred at 50°C and 60 rpm for 10 hours to obtain a mixture.

[0079] S3: Extruding and casting the mixture into a film at 90° C. to obtain a photovoltaic encapsulation film.

[0080] The photovoltaic encapsulation film prepared in this embodiment is used to prepare a photovoltaic module through the following steps: the backplane, photovoltaic encapsulation film, solar cell, photovoltaic encapsulation film and glass are stacked in order from bottom to top, and then laminated at a temperature of 145°C and a pressure of -30 kPa for 8 minutes to obtain a photovoltaic module.

[0081] Example 7

[0082] The difference between this embodiment and embodiment 1 is that: the total amount of tert-amyl peroxycarbonate-2-ethylhexanoate and tert-butyl peroxycarbonate-2-ethylhexanoate is unchanged, the amount of the former is reduced, and the amount of the latter is increased; the rest of the raw materials and steps are the same as those in embodiment 1. Specifically, the steps of preparing the photovoltaic encapsulation film in this embodiment are as follows:

[0083] S1: Weigh the following raw materials in parts by weight: 100 parts of POE resin, 0.1 parts of tert-amyl peroxycarbonate-2-ethylhexanoate (pyrolysis temperature is 134°C), 0.8 parts of tert-butyl peroxycarbonate-2-ethylhexanoate (pyrolysis temperature is 137°C), 0.9 parts of 3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexylcarboxylate, 0.9 parts of co-crosslinking agent TAIC, 0.3 parts of silane coupling agent KH570, 0.1 parts of anti-PID additive montmorillonite, and 0.2 parts of anti-aging additive UV770.

[0084] S2: tert-amyl peroxycarbonate-2-ethylhexanoate, tert-butyl peroxycarbonate-2-ethylhexanoate and 3,4-epoxycyclohexylcarboxylic acid-3',4'-epoxycyclohexylmethyl ester were added to a mixer, stirred evenly, and then POE resin was added, and stirred at 50°C and 60 rpm for 2 h. The remaining other raw materials were added to the mixer, and stirred at 50°C and 60 rpm for 10 h to obtain a mixture.

[0085] S3: Extruding and casting the mixture into a film at 90° C. to obtain a photovoltaic encapsulation film.

[0086] The photovoltaic encapsulation film prepared in this embodiment is used to prepare a photovoltaic module through the following steps: the backplane, photovoltaic encapsulation film, solar cell, photovoltaic encapsulation film and glass are stacked in order from bottom to top, and then laminated at a temperature of 145°C and a pressure of -30 kPa for 8 minutes to obtain a photovoltaic module.

[0087] Example 8

[0088] The difference between this embodiment and embodiment 1 is that: in the mixing process, all raw materials are mixed in one step, not in two steps; the remaining raw materials and steps are the same as those in embodiment 1. Specifically, the steps of preparing the photovoltaic encapsulation film in this embodiment are as follows:

[0089] S1: Weigh the following raw materials in parts by weight: 100 parts of POE resin, 0.3 parts of tert-amyl peroxycarbonate-2-ethylhexanoate (pyrolysis temperature is 134°C), 0.6 parts of tert-butyl peroxycarbonate-2-ethylhexanoate (pyrolysis temperature is 137°C), 0.9 parts of 3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexylcarboxylate, 0.9 parts of co-crosslinking agent TAIC, 0.3 parts of silane coupling agent KH570, 0.1 parts of anti-PID additive montmorillonite, and 0.2 parts of anti-aging additive UV770.

[0090] S2: Add all the raw materials into a blender and stir at 50 °C and 60 rpm for 12 h to obtain a mixture.

[0091] S3: Extruding and casting the mixture into a film at 90° C. to obtain a photovoltaic encapsulation film.

[0092] The photovoltaic encapsulation film prepared in this embodiment is used to prepare a photovoltaic module through the following steps: the backplane, photovoltaic encapsulation film, solar cell, photovoltaic encapsulation film and glass are stacked in order from bottom to top, and then laminated at a temperature of 145°C and a pressure of -30 kPa for 8 minutes to obtain a photovoltaic module.

[0093] Comparative Example 1

[0094] The difference between this comparative example and Example 1 is that: in the process of preparing the photovoltaic encapsulation film, no organic peroxide initiator and liquid polyepoxy small molecule are added; the rest of the raw materials and steps are the same as those in Example 1. Specifically, the steps of preparing the photovoltaic encapsulation film in this comparative example are as follows:

[0095] S1: Weigh the following raw materials in parts by weight: 100 parts of POE resin, 0.9 parts of co-crosslinking agent TAIC, 0.3 parts of silane coupling agent KH570, 0.1 parts of anti-PID additive montmorillonite, and 0.2 parts of anti-aging additive UV770.

[0096] S2: Add all the raw materials into a mixer and stir at 50°C and 60 rpm for 12 h to obtain a mixture.

[0097] S3: Extruding and casting the mixture into a film at 90° C. to obtain a photovoltaic encapsulation film.

[0098] The photovoltaic encapsulation film prepared in this embodiment is used to prepare a photovoltaic module through the following steps: the backplane, photovoltaic encapsulation film, solar cell, photovoltaic encapsulation film and glass are stacked in order from bottom to top, and then laminated at a temperature of 145°C and a pressure of -30 kPa for 8 minutes to obtain a photovoltaic module.

[0099] Comparative Example 2

[0100] The difference between this comparative example and Example 1 is that the liquid polyepoxy small molecule is replaced with an equal mass of bisphenol A epoxy resin; the rest of the raw materials and steps are the same as Example 1. Specifically, the steps for preparing the photovoltaic encapsulation film in this comparative example are as follows:

[0101] S1: Weigh the following raw materials in parts by weight: 100 parts of POE resin, 0.3 parts of tert-amyl peroxycarbonate-2-ethylhexanoate (pyrolysis temperature is 134°C), 0.6 parts of tert-butyl peroxycarbonate-2-ethylhexanoate (pyrolysis temperature is 137°C), 0.9 parts of bisphenol A epoxy resin, 0.9 parts of co-crosslinking agent TAIC, 0.3 parts of silane coupling agent KH570, 0.1 parts of anti-PID additive montmorillonite, and 0.2 parts of anti-aging additive UV770.

[0102] S2: tert-amyl peroxycarbonate-2-ethylhexanoate, tert-butyl peroxycarbonate-2-ethylhexanoate and bisphenol A epoxy resin were added to a blender, stirred evenly, and then POE resin was added, and stirred at 50°C and 60 rpm for 2 h. The remaining other raw materials were added to the blender, and stirred at 50°C and 60 rpm for 10 h to obtain a mixture.

[0103] S3: Extruding and casting the mixture into a film at 90° C. to obtain a photovoltaic encapsulation film.

[0104] The photovoltaic encapsulation film prepared in this embodiment is used to prepare a photovoltaic module through the following steps: the backplane, photovoltaic encapsulation film, solar cell, photovoltaic encapsulation film and glass are stacked in order from bottom to top, and then laminated at a temperature of 145°C and a pressure of -30 kPa for 8 minutes to obtain a photovoltaic module.

[0105] Test example: Bonding performance test between photovoltaic encapsulation film and glass

[0106] Photovoltaic encapsulation films and photovoltaic modules were prepared according to the methods in the embodiments and comparative examples, and the peel strength between the photovoltaic encapsulation films and the glass was tested before aging and after PCT 48 h. The results are shown in Table 1. The conditions for PCT 48 h were set as follows: temperature 121°C, pressure 0.2 MPa, and humidity 100%.

[0107] Table 1 Peel strength test results between photovoltaic encapsulation film and glass

[0108]

[0109] Test results analysis and conclusion:

[0110] (1) By comparing Example 1 with Comparative Example 1, it can be seen that by adding an organic peroxide initiator and a liquid polyepoxy small molecule during the preparation of the encapsulation film, the bonding strength between the film and the glass can be improved. This is because: during the lamination process of assembling the film into a photovoltaic module, the organic peroxide initiator pyrolyzes to produce free radicals and carbon dioxide, wherein the free radicals initiate the matrix resin in the film to produce free radicals available for bonding, and the acidic environment provided by the carbon dioxide causes the epoxy groups in the liquid polyepoxy small molecule to open the ring, and some of the epoxy groups are bonded to the matrix resin after the ring opening, and some of the epoxy groups react with the silanol groups on the glass surface after the ring opening to form a strong chemical bond. In the above manner, the liquid polyepoxy small molecule can form a covalent connection between the matrix resin in the film and the glass, thereby improving the bonding performance between the photovoltaic encapsulation film and the glass.

[0111] (2) By comparing Example 1 and Comparative Example 2, it can be seen that the liquid polyepoxy small molecules of the present invention have a better effect on improving the adhesive performance of the film than the epoxy resin polymer. This is because the liquid small molecules have low viscosity, are easy to disperse into the matrix resin, and have high reactivity. Therefore, compared with the solid or paste epoxy resin polymer, they can play a better role in improving the adhesive performance between the photovoltaic encapsulation film and the glass.

[0112] (3) By comparing Example 1 with Example 8, it can be seen that in the process of mixing, the organic peroxide initiator and the liquid polyepoxy small molecule are mixed and absorbed by the matrix resin before being mixed with other raw materials, which can further improve the bonding strength between the photovoltaic encapsulation film and the glass. This is because: the above two-step mixing method can make the distribution positions of the organic peroxide initiator and the liquid polyepoxy small molecule in the film closer, which helps the liquid polyepoxy small molecule to form covalent bonds with the matrix resin and glass under the action of the organic peroxide initiator during lamination.

[0113] (4) Comparing Examples 1 to 3 with Examples 4 to 7, it can be seen that the use of a compound of component a with a lower decomposition temperature and component b with a higher decomposition temperature as an organic peroxide initiator can improve the post-aging bonding strength between the film and the glass, and when the mass ratio of component a to component b is controlled within the range of 1:1 to 3, the post-aging bonding strength is higher. This is because: when only component a with a lower pyrolysis temperature is used, or the proportion of the former in components a and b is too large, the matrix resin inside the film will cross-link too quickly during the hot pressing process, resulting in the film being unable to fully wet and spread on the glass, thereby adversely affecting the post-aging bonding strength between the two; when only component b with a higher pyrolysis temperature is used, or the proportion of the latter in components a and b is too large, the cross-linking speed of the film is slow. At the same time, because the liquid polyepoxy small molecules also consume free radicals, the cross-linking speed will be slower and the cross-linking degree will be smaller, which will also have an adverse effect on the aging bonding performance of the film.

[0114] Unless otherwise defined, all technical terms and scientific terms used in the present invention have the same meanings as those commonly understood by ordinary technicians in the field to which the present disclosure belongs. Unless otherwise specified, the raw materials and equipment used in the present invention are conventional raw materials and equipment in the field and can be obtained from conventional commercial channels; unless otherwise specified, the methods used in the present invention are conventional methods in the field.

[0115] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent transformation made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A photovoltaic encapsulation film with high adhesion, characterized in that: The raw materials of one side of the photovoltaic encapsulation film that is bonded to the glass in the photovoltaic module include a matrix resin, an organic peroxide initiator and a liquid polyepoxy small molecule; the temperature at which the organic peroxide initiator pyrolyzes to generate free radicals and carbon dioxide is not higher than the lamination temperature of the photovoltaic module and is not lower than the preparation temperature of the photovoltaic encapsulation film; the organic peroxide initiator includes component a and component b in a mass ratio of 1:1-3; the temperatures at which component a and component b pyrolyze to generate free radicals and carbon dioxide are 120-135°C and 137-150°C, respectively.

2. The photovoltaic encapsulation film according to claim 1, characterized in that: The component a comprises at least one of tert-butyl peroxy-2-ethylhexanoate, 1,1-di-tert-butyl peroxy-3,3,5-trimethylcyclohexane, tert-butyl peroxy-3,5,5-trimethylhexanoate, 1,1-di-tert-butyl peroxycyclohexane and tert-amyl peroxycarbonate-2-ethylhexanoate.

3. The photovoltaic encapsulation film according to claim 1, characterized in that: The component b comprises at least one of tert-butyl peroxycarbonate-2-ethylhexanoate, tert-butyl peroxyisopropylcarbonate, tert-butyl peroxybenzoate, butyl 4,4-bis(tert-butylperoxy)valerate, di-tert-amyl peroxide and 2,5-di-tert-butylperoxy-2,5-dimethylhexane.

4. The photovoltaic encapsulation film according to claim 1, characterized in that: The liquid polyepoxy small molecule includes at least one of 3,4-epoxycyclohexylcarboxylic acid-3',4'-epoxycyclohexyl methyl ester, bis((3,4-epoxycyclohexyl)methyl)adipate, vinylcyclohexene dioxide, dipentylene dioxide, tetrahydroindene diepoxide and di-4-epoxycyclohexane.

5. The photovoltaic encapsulation film according to claim 1, characterized in that: The mass ratio of the liquid polyepoxy small molecule to the organic peroxide initiator is 1:1-9; the total mass of the liquid polyepoxy small molecule and the organic peroxide initiator is 0.6-1.8% of the mass of the base resin.

6. The photovoltaic encapsulation film according to claim 1, characterized in that: The raw material of the side of the photovoltaic encapsulation film that is bonded to the glass in the photovoltaic module also includes at least one of a cross-linking agent, a silane coupling agent, an anti-PID additive and an anti-aging additive.

7. A method for preparing the photovoltaic encapsulation film according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1: Mix the organic peroxide initiator and the liquid polyepoxy small molecule, mix with the base resin, and fully absorb; S2: Add other raw materials of photovoltaic encapsulation film to the product obtained in step S1, and extrude and form a film after it is fully absorbed.

8. The preparation method according to claim 7, characterized in that In step S1, the method for sufficient absorption is stirring at a speed of 60-70 rpm for 2-2.5 h at 45-50° C.; in step S2, the method for sufficient absorption is stirring at a speed of 60-70 rpm for 10-12 h at 45-50° C.

9. The preparation method according to claim 7, characterized in that: In step S2, the temperature of the extrusion film forming is 80-100°C.

10. Use of the photovoltaic encapsulation film according to any one of claims 1 to 6 in photovoltaic modules, characterized in that: The preparation process of the photovoltaic module includes: stacking the backboard, photovoltaic encapsulation film, battery cell, photovoltaic encapsulation film and glass in order from bottom to top, and laminating at 140-150°C.

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