Photovoltaic packaging adhesive film and preparation method and application thereof

Abstract

The invention provides a photovoltaic packaging adhesive film as well as a preparation method and application thereof. The photovoltaic packaging adhesive film is prepared from the following raw materials in parts by mass: 100 parts of a resin matrix, 0.01 to 0.5 part of lignin, 0.05 to 2 parts of a cross-linking agent, 0.05 to 5 parts of an assistant cross-linking agent, 0.01 to 1 part of a tackifier and 0.01 to 0.2 part of a light stabilizer. Lignin is used as an auxiliary agent, and the ultraviolet shielding effect can be remarkably improved. The photovoltaic adhesive film prepared by the invention has high stability and is not easy to migrate; a large number of functional groups in the lignin can chemically react with the resin to improve the crosslinking density, so that the tensile strength, resistivity and other properties of the adhesive film are improved. Lignin is used, and the method has the advantages of being environmentally friendly, non-toxic, harmless, renewable and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of photovoltaic modules, and relates to a photovoltaic encapsulation film and its preparation method and application, and particularly to a photovoltaic encapsulation film with high-efficiency ultraviolet shielding and its preparation method and application. Background Art

[0002] As a key material of photovoltaic modules, the photovoltaic encapsulation film affects the quality and lifespan of the modules. It is an organic polymer material that will age under long-term sunlight irradiation, reducing the adhesiveness, light transmittance, mechanical strength, etc. of the film, and affecting the service life and power generation efficiency of the modules. In addition, during the long-term use of the modules, the backsheet will show aging and cracking phenomena, and one of the main reasons is ultraviolet radiation. Therefore, developing a photovoltaic film with high stability and high ultraviolet shielding effect to reduce the ultraviolet radiation received by the backsheet is an effective means to delay the aging of the backsheet and improve the service life of the modules.

[0003] To improve the ultraviolet shielding ability of photovoltaic films, UV-shielding additives are usually added to the films. Commonly used UV-shielding agents include inorganic and organic types. Organic types such as benzophenones and benzotriazoles have obvious absorption of ultraviolet rays in the range of 290-380 nm, which are the most commonly used UV absorbers in current photovoltaic films. For example, commonly used UV absorbers in the prior art include 2-hydroxy-4-n-octyloxybenzophenone, 2,2-tetramethylenebis(3,1-benzoxazin-4-one), 2-(2'-hydroxy-5-methylphenyl)benzotriazole, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-tert-amylphenyl)benzotriazole, 2'-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2H-benzotriazol-2)-4,6-bis(1-methyl-1-phenylethyl)phenol, etc. However, the disadvantage that these UV absorbers are easily degraded under light makes the stability of the modules insufficient; inorganic types such as titanium dioxide and zinc oxide have excellent scattering characteristics for ultraviolet rays, but they are likely to cause photo-degradation of polymers and are generally not used in photovoltaic films.

[0004] Therefore, in this field, it is desired to further improve the anti-ultraviolet aging performance of photovoltaic encapsulation films, improve the migration property, and enhance properties such as the tensile strength and resistivity of the films. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a photovoltaic encapsulation film and its preparation method and application.

[0006] To achieve this purpose, the present invention adopts the following technical solutions:

[0007] On the one hand, the present invention provides a photovoltaic encapsulation film. The preparation raw materials of the photovoltaic encapsulation film include the following components by mass: 100 parts by mass of a resin matrix, 0.01 to 0.5 parts by mass of lignin, 0.05 to 2 parts by mass of a crosslinking agent, 0.05 to 5 parts by mass of a co-crosslinking agent, 0.01 to 1 part by mass of a tackifier, and 0.01 to 0.2 parts by mass of a light stabilizer.

[0008] The present invention uses the biomass material lignin as a special additive to improve the anti-ultraviolet aging performance of the photovoltaic encapsulation film. First, the abundant benzene rings and their derivatives in the lignin structure endow it with excellent ultraviolet absorption ability. Second, compared with common ultraviolet absorbers, the lignin structure has abundant functional groups that can chemically combine with the resin matrix, enabling it to stably exist in the film and not easily migrate. Third, the high chemical activity of lignin can increase the resin crosslinking density, improving the properties such as the tensile strength and resistivity of the film.

[0009] In the present invention, the renewable raw material lignin added to the photovoltaic film has a large number of benzene ring structures. The π electron cloud in the benzene ring can absorb ultraviolet light and generate electronic transitions. Because the lignin structure contains a large number of different types of benzene ring derivatives and its π electron cloud has a variety of energy level distributions, lignin can absorb ultraviolet light of multiple wavelengths. Therefore, this photovoltaic film can absorb all ultraviolet light in the wavelength range of 290 nm to 380 nm.

[0010] In the present invention, the amount of lignin in the preparation raw materials of the photovoltaic encapsulation film can be 0.01 part by mass, 0.05 part by mass, 0.1 part by mass, 0.2 part by mass, 0.3 part by mass, 0.4 part by mass, or 0.5 part by mass; the amount of the crosslinking agent can be 0.05 part by mass, 0.08 part by mass, 0.1 part by mass, 0.5 part by mass, 0.8 part by mass, 1 part by mass, 1.3 part by mass, 1.5 part by mass, 1.8 part by mass, or 2 parts by mass; the amount of the co-crosslinking agent can be 0.05 part by mass, 0.08 part by mass, 0.1 part by mass, 0.5 part by mass, 0.8 part by mass, 1 part by mass, 2 parts by mass, 3 parts by mass, 4 parts by mass, or 5 parts by mass; the amount of the tackifier can be 0.01 part by mass, 0.03 part by mass, 0.05 part by mass, 0.08 part by mass, 0.1 part by mass, 0.3 part by mass, 0.5 part by mass, 0.8 part by mass, or 1 part by mass, and the amount of the light stabilizer can be 0.01 part by mass, 0.05 part by mass, 0.1 part by mass, 0.15 part by mass, 0.18 part by mass, or 0.2 part by mass.

[0011] Preferably, the resin matrix is one or a combination of at least two of ethylene-vinyl acetate copolymer, ethylene copolymer, propylene copolymer, ethylene-butene copolymer, or ethylene-octene copolymer, preferably ethylene-vinyl acetate copolymer or ethylene-octene copolymer.

[0012] Preferably, the vinyl acetate content in the ethylene-vinyl acetate copolymer is 10-33%, such as 10%, 13%, 15%, 20%, 23%, 25%, 28%, 30% or 33%, preferably 28-33%; the melt index is 10-43 g / 10 min, such as 10 g / 10 min, 15 g / 10 min, 18 g / 10 min, 20 g / 10 min, 25 g / 10 min, 28 g / 10 min, 30 g / 10 min, 33 g / 10 min, 38 g / 10 min, 40 g / 10 min or 43 g / 10 min, preferably 15-25 g / 10 min.

[0013] Preferably, the melt index of the ethylene-octene copolymer is 3-30 g / 10 min, such as 3 g / 10 min, 5 g / 10 min, 8 g / 10 min, 10 g / 10 min, 15 g / 10 min, 20 g / 10 min, 25 g / 10 min or 30 g / 10 min, preferably 5-15 g / 10 min.

[0014] In the present invention, the lignin is alkaline lignin or neutral lignin.

[0015] Preferably, the alkaline lignin is selected from at least one of sulfate lignin, alkali lignin, oxygen-alkali lignin, ammonia lignin or lime lignin.

[0016] Preferably, the neutral lignin is selected from at least one of Brauns native lignin, Norland lignin, Beckman lignin or cellulase lignin.

[0017] More preferably, the lignin is Brauns native lignin or alkali lignin.

[0018] In the present invention, acidic lignin is not used because adding acidic lignin can achieve an ultraviolet shielding effect, but the light transmittance of the photovoltaic encapsulation film will be significantly reduced, making it not meet the application requirements of the photovoltaic film, and its acidity will exacerbate the acid corrosion of the backplane and cause the backplane to turn yellow.

[0019] Preferably, the lignin is powdery lignin obtained by drying.

[0020] More preferably, the drying method is spray drying.

[0021] Preferably, the crosslinking agent is composed of one or more of isopropyl percarbonate tert-butyl, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 2-ethylhexyl percarbonate tert-butyl, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(tert-amylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(tert-amylperoxy)cyclohexane, 1,1-bis(tert-butylperoxy)cyclohexane, 2,2-bis(tert-butylperoxy)butane, tert-amyl peroxy-2-ethylhexyl carbonate, 2,5-dimethyl-2,5-bis(benzoylperoxy)hexane, tert-amyl percarbonate, tert-butyl peroxy-3,3,5-trimethylhexanoate, preferably any one or a combination of at least two of 2-ethylhexyl percarbonate tert-butyl, tert-amyl peroxy-2-ethylhexyl carbonate or 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane.

[0022] Preferably, the co-crosslinking agent is composed of one or more of triallyl isocyanurate, triallyl cyanurate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, tris(2-hydroxyethyl)isocyanurate triacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated trimethylolpropane triacrylate, ethoxylated glycerol triacrylate, propoxylated glycerol triacrylate, pentaerythritol tetraacrylate, ethoxylated pentaerythritol tetraacrylate, trimethylolpropane tetraacrylate, bis-trimethylolpropane tetraacrylate, bis-trimethylolpropane tetramethacrylate, propoxylated pentaerythritol tetraacrylate, 2,4,6-tris(2-propenyloxy)-1,3,5-triazine, tricyclodecane dimethanol diacrylate, propoxylated neopentyl glycol diacrylate, ethoxylated bisphenol A diacrylate, ethoxylated bisphenol A dimethacrylate, 2-butyl-2-ethyl-1,3-propanediol diacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate and polyethylene glycol dimethacrylate, preferably any one or a combination of at least two of triallyl isocyanurate, ethoxylated trimethylolpropane triacrylate or propoxylated trimethylolpropane triacrylate.

[0023] Preferably, the tackifier is a silane coupling agent, specifically composed of one or more of vinyltriethoxysilane, vinyltrimethoxysilane, vinyltris(β-methoxyethoxy)silane, 3-methacryloxypropyltrimethoxysilane, aminopropyltrimethoxysilane, aminopropyltriethoxysilane, aminopropyltriisopropoxysilane, preferably any one or a combination of at least two of 3-methacryloxypropyltrimethoxysilane or vinyltrimethoxysilane.

[0024] Preferably, the light stabilizer is one or a combination of at least two of cetyl 3,5 - di - tert - butyl - 4 - hydroxybenzoate, tris(1,2,2,6,6 - pentamethyl - 4 - piperidyl) phosphite, bis(2,2,6,6 - tetramethylpiperidyl) sebacate, bis - 1 - decyloxy - 2,2,6,6 - tetramethylpiperidin - 4 - yl sebacate, the polymer of succinic acid and 4 - hydroxy - 2,2,6,6 - tetramethyl - 1 - piperidinol, the polymer of N,N’ - bis(2,2,6,6 - tetramethyl - 4 - piperidyl) - 1,6 - hexanediamine and 2,4,6 - trichloro - 1,3,5 - triazine, 1,5,8,12 - tetra[4,6 - bis(N - butyl - N - 1,2,2,6,6 - pentamethyl - 4 - piperidylamino) - 1,3,5 - triazin - 2 - yl] - 1,5,8,12 - tetraazadodecane, poly - {[6 - [(1,1,3,3 - tetramethylbutyl) - imino] - 1,3,5 - triazine - 2,4 - diyl][2 - (2,2,6,6 - tetramethylpiperidyl) - amino] - hexyl - [4 - (2,2,6,6 - tetramethylpiperidyl) - amino]}. Preferably, it is one or a combination of at least two of 1,5,8,12 - tetra[4,6 - bis(N - butyl - N - 1,2,2,6,6 - pentamethyl - 4 - piperidylamino) - 1,3,5 - triazin - 2 - yl] - 1,5,8,12 - tetraazadodecane, poly - {[6 - [(1,1,3,3 - tetramethylbutyl) - imino] - 1,3,5 - triazine - 2,4 - diyl][2 - (2,2,6,6 - tetramethylpiperidyl) - amino] - hexyl - [4 - (2,2,6,6 - tetramethylpiperidyl) - amino]} or bis(2,2,6,6 - tetramethylpiperidyl) sebacate.

[0025] On the other hand, the present invention provides a method for preparing the photovoltaic encapsulation film as described above, and the preparation method includes the following steps:

[0026] Mix the resin matrix, lignin, cross - linker, co - cross - linker, tackifier and light stabilizer, melt - extrude, and cast into a film to obtain the photovoltaic encapsulation film.

[0027] In the present invention, after casting into a film, it is prepared into a photovoltaic encapsulation film through processes such as cooling, slitting, and winding.

[0028] On the other hand, the present invention provides the application of the photovoltaic encapsulation film as described above in a photovoltaic module.

[0029] The high - efficiency ultraviolet - shielding photovoltaic film prepared by the present invention has high stability and high ultraviolet - shielding effect, can greatly reduce the ultraviolet radiation received by the backsheet, and is an effective means to delay the aging of the backsheet and improve the service life of the module.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The present invention uses lignin as an auxiliary agent. The lignin structure contains rich benzene rings and their derivatives, which have excellent absorption effects on ultraviolet light and can significantly improve the ultraviolet shielding effect. The photovoltaic film prepared by the present invention has high stability. On the one hand, compared with common ultraviolet absorbers, the lignin structure has rich functional groups that can chemically combine with the resin matrix, making it not easy to migrate; on the other hand, its large number of functional groups can chemically react with the resin to increase the crosslinking density, improving the properties such as the tensile strength and resistivity of the film. The lignin used in the present invention is the second largest biomass resource in plants, with the advantages of being green, environmentally friendly, non-toxic, harmless, and renewable. Detailed implementation manners

[0032] The technical solutions of the present invention will be further described below through specific implementation manners. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0033] Example 1

[0034] A photovoltaic encapsulation film with high-efficiency ultraviolet shielding, the preparation raw materials of which include: 100 parts by mass of EVA with a VA content of 28% (Hanwha Total Petrochemical), 0.05 part by mass of Brouss lignin, 0.5 part by mass of tert-butyl peroxycarbonate-2-ethylhexyl ester (Younaide Initiator (Shanghai) Co., Ltd., TBEC), 3.0 parts by mass of trimethylolpropane triacrylate (Tianjin Tianjiao Chemical Co., Ltd., TMPTA), 0.1 part by mass of bis(2,2,6,6-tetramethylpiperidin-4-yl) sebacate (BASF, Tinuvin770), 0.2 part by mass of 3-(trimethoxysilyl)propyl methacrylate (Evonik Degussa, KH-570).

[0035] Mix the above raw materials evenly using a stirring kettle, and co-extrude them through an extruder. After the extruded material is melted and plasticized, it is injected into a die head, and a photovoltaic encapsulation film with high-efficiency ultraviolet shielding is prepared through processes such as casting film, cooling, slitting, and winding.

[0036] Example 2

[0037] A highly efficient ultraviolet-shielding photovoltaic encapsulation film, the raw materials for its preparation include: 100 parts by mass of EVA with a VA content of 28% (Hanwha Total Petrochemical), 0.1 part by mass of Brouss lignin, 0.5 part by mass of tert-butyl peroxycarbonate-2-ethylhexyl ester (Peroxychem (Shanghai) Co., Ltd., TBEC), 3.0 parts by mass of trimethylolpropane triacrylate (Tianjin Tianjiao Chemical Co., Ltd., TMPTA), 0.1 part by mass of bis(2,2,6,6-tetramethylpiperidin-4-yl) sebacate (BASF, Tinuvin770), 0.2 part by mass of methacryloxypropyltrimethoxysilane (Evonik Degussa, KH-570).

[0038] Mix the above raw materials evenly using a stirring kettle, and then co-extrude them through an extruder. After the extruded material is melted and plasticized, it is injected into a die head, and then processed through processes such as casting into a film, cooling, slitting, and winding to prepare a highly efficient ultraviolet-shielding photovoltaic encapsulation film.

[0039] Example 3

[0040] A highly efficient ultraviolet-shielding photovoltaic encapsulation film, the raw materials for its preparation include: 100 parts by mass of EVA with a VA content of 28% (Hanwha Total Petrochemical), 0.2 part by mass of Brouss lignin, 0.5 part by mass of tert-butyl peroxycarbonate-2-ethylhexyl ester (Peroxychem (Shanghai) Co., Ltd., TBEC), 3.0 parts by mass of trimethylolpropane triacrylate (Tianjin Tianjiao Chemical Co., Ltd., TMPTA), 0.1 part by mass of bis(2,2,6,6-tetramethylpiperidin-4-yl) sebacate (BASF, Tinuvin770), 0.2 part by mass of methacryloxypropyltrimethoxysilane (Evonik Degussa, KH-570).

[0041] Mix the above raw materials evenly using a stirring kettle, and then co-extrude them through an extruder. After the extruded material is melted and plasticized, it is injected into a die head, and then processed through processes such as casting into a film, cooling, slitting, and winding to prepare a highly efficient ultraviolet-shielding photovoltaic encapsulation film.

[0042] Example 4

[0043] A highly efficient ultraviolet-shielding photovoltaic encapsulation film, the raw materials for its preparation include: 100 parts by mass of ethylene-octene copolymer (Dow Chemical), 0.05 part by mass of Brouss lignin, 0.5 part by mass of tert-amyl peroxy-2-ethylhexyl carbonate (Peroxychem (Shanghai) Co., Ltd., TAEC), 3.0 parts by mass of trimethylolpropane triacrylate (Tianjin Tianjiao Chemical Co., Ltd., TMPTA), 0.1 part by mass of bis(2,2,6,6-tetramethylpiperidin-4-yl) sebacate (BASF, Tinuvin770), 0.2 part by mass of methacryloxypropyltrimethoxysilane (Evonik Degussa, KH-570).

[0044] Mix the above raw materials evenly in a stirring kettle, and then co-extrude them through an extruder. After the extruded material is melted and plasticized, it is injected into a die head, and then a high-efficiency ultraviolet-shielding photovoltaic encapsulation film is prepared through processes such as casting into a film, cooling, slitting, and winding.

[0045] Example 5

[0046] A high-efficiency ultraviolet-shielding photovoltaic encapsulation film, the raw materials for its preparation include: 100 parts by mass of ethylene-octene copolymer (Dow Chemical), 0.1 part by mass of Brouss lignin, 0.5 part by mass of tert-amyl peroxy-2-ethylhexyl carbonate (Younited Initiators (Shanghai) Co., Ltd., TAEC), 3.0 parts by mass of trimethylolpropane triacrylate (Tianjin Tianjiao Chemical Co., Ltd., TMPTA), 0.1 part by mass of bis(2,2,6,6-tetramethylpiperidinyl) sebacate (BASF, Germany, Tinuvin770), 0.2 part by mass of methacryloxypropyltrimethoxysilane (Evonik Degussa, KH-570).

[0047] Mix the above raw materials evenly in a stirring kettle, and then co-extrude them through an extruder. After the extruded material is melted and plasticized, it is injected into a die head, and then a high-efficiency ultraviolet-shielding photovoltaic encapsulation film is prepared through processes such as casting into a film, cooling, slitting, and winding.

[0048] Example 6

[0049] A high-efficiency ultraviolet-shielding photovoltaic encapsulation film, the raw materials for its preparation include: 100 parts by mass of ethylene-octene copolymer (Dow Chemical), 0.2 part by mass of Brouss lignin, 0.5 part by mass of tert-amyl peroxy-2-ethylhexyl carbonate (Younited Initiators (Shanghai) Co., Ltd., TAEC), 3.0 parts by mass of trimethylolpropane triacrylate (Tianjin Tianjiao Chemical Co., Ltd., TMPTA), 0.1 part by mass of bis(2,2,6,6-tetramethylpiperidinyl) sebacate (BASF, Germany, Tinuvin770), 0.2 part by mass of methacryloxypropyltrimethoxysilane (Evonik Degussa, KH-570).

[0050] Mix the above raw materials evenly in a stirring kettle, and then co-extrude them through an extruder. After the extruded material is melted and plasticized, it is injected into a die head, and then a high-efficiency ultraviolet-shielding photovoltaic encapsulation film is prepared through processes such as casting into a film, cooling, slitting, and winding.

[0051] Comparative Example 1

[0052] A kind of photovoltaic encapsulation film, the preparation raw materials include: 100 parts by mass of EVA with 28% VA content (Hanwha Total Petrochemical), 0.5 part by mass of tert-butyl peroxy-2-ethylhexyl carbonate (PeroxyChem (Shanghai) Co., Ltd., TBEC), 3.0 parts by mass of trimethylolpropane triacrylate (Tianjin Tianjiao Chemical Co., Ltd., TMPTA), 0.2 part by mass of 2-hydroxy-4-n-octyloxybenzophenone (BASF, Germany), 0.1 part by mass of bis(2,2,6,6-tetramethylpiperidin-4-yl) sebacate (BASF, Germany, Tinuvin770), 0.2 part by mass of methacryloxypropyltrimethoxysilane (Evonik Degussa, KH-570).

[0053] Mix the above raw materials evenly using a stirring kettle, and then co-extrude them through an extruder. After the extruded material is melted and plasticized, it is injected into a die head, and then prepared into a nanocellulose-reinforced photovoltaic encapsulation film through processes such as melt extrusion, casting into a film, cooling, slitting, and winding.

[0054] Comparative Example 2

[0055] A kind of photovoltaic encapsulation film, the preparation raw materials include: 100 parts by mass of ethylene-octene copolymer (Dow Chemical, USA), 0.5 part by mass of tert-amyl peroxy-2-ethylhexyl carbonate (PeroxyChem (Shanghai) Co., Ltd., TAEC), 3.0 parts by mass of trimethylolpropane triacrylate (Tianjin Tianjiao Chemical Co., Ltd., TMPTA), 0.2 part by mass of 2-hydroxy-4-n-octyloxybenzophenone (BASF, Germany), 0.1 part by mass of bis(2,2,6,6-tetramethylpiperidin-4-yl) sebacate (BASF, Germany, Tinuvin770), 0.2 part by mass of methacryloxypropyltrimethoxysilane (Evonik Degussa, KH-570).

[0056] Mix the above raw materials evenly using a stirring kettle, and then co-extrude them through an extruder. After the extruded material is melted and plasticized, it is injected into a die head, and then prepared into a nanocellulose-reinforced photovoltaic encapsulation film through processes such as melt extrusion, casting into a film, cooling, slitting, and winding.

[0057] Comparative Example 3

[0058] A kind of photovoltaic encapsulation film, the preparation raw materials include: 100 parts by mass of EVA with 28% VA content (Hanwha Total Petrochemical), 0.2 parts by mass of sulfuric acid lignin, 0.5 parts by mass of tert-butyl peroxycarbonate-2-ethylhexyl ester (PeroxyChem (Shanghai) Co., Ltd., TBEC), 3.0 parts by mass of trimethylolpropane triacrylate (Tianjin Tianjiao Chemical Co., Ltd., TMPTA), 0.1 parts by mass of bis(2,2,6,6-tetramethylpiperidin-4-yl) sebacate (BASF, Tinuvin770), 0.2 parts by mass of methacryloxypropyltrimethoxysilane (Evonik Degussa, KH-570).

[0059] Mix the above raw materials evenly using a stirring kettle, and then co-extrude them through an extruder. After the extruded material is melted and plasticized, it is injected into the die head, and then prepared into a nanocellulose-reinforced photovoltaic encapsulation film through processes such as melting extrusion, casting into a film, cooling, slitting, and winding.

[0060] Performance test method:

[0061] 1. Transmittance test:

[0062] The thickness of the test sample is 0.6 mm. According to the spectrophotometer method of GB / T 2410-2008, take the average value of the transmittance in the range of 380 - 1100 nm and 290 - 380 nm.

[0063] 2. Crosslinking degree test:

[0064] The sample preparation method is as follows: Take a piece of film with a size of 50 mm * 50 mm, stack it from bottom to top in the order of glass, non-stick film, film, non-stick film, and glass, then put it into a vacuum laminator for curing and crosslinking, and then take it out and put it into a dryer to cool to room temperature for standby. It is required that the cured film is flat on both the upper and lower sides, with uniform thickness, and the crosslinking degree reaches more than 75%. Weigh 0.50 g ± 0.01 g, cut it into small particles with a size less than 3 mm * 3 mm, and each group of samples has no less than 3.

[0065] The test method is as follows: a. Wash and dry the stainless steel wire mesh bag, and weigh it as W1 (accurate to 0.001 g); b. Put the prepared sample into the stainless steel wire mesh bag and weigh it as W2 (accurate to 0.001 g); c. Seal the mesh bag with iron wire, put it into a three-necked flask containing 1 / 2 volume of xylene solution, immerse the sample in the solvent, heat to about 140 °C, and carry out condensation reflux for 5 h; d. After the reflux is over, take out the stainless steel wire mesh bag, hang it to remove the liquid drops, and then put it into a vacuum oven at a temperature of 140 °C and dry to constant weight; e. Take out the stainless steel wire mesh bag, remove the iron wire, put it into a dryer and cool to room temperature, and weigh it as W3 (accurate to 0.001 g).

[0066] The calculation method is as follows: Calculate the crosslinking degree according to the following formula, and take the average value of the test results.

[0067] D = (W3 - W1) / (W2 - W1) * 100%

[0068] In the formula, D is the crosslinking degree; W1 is the mass of the empty stainless steel wire mesh bag / g; W2 is the mass of the steel wire mesh with the sample / g; W3 is the mass of the sample and the steel wire mesh after extraction and drying / g.

[0069] 3. Backsheet protection effect test:

[0070] Use the adhesive film to encapsulate the standard single-glass photovoltaic module. After the UV 80 kWh test, observe the cracking and powdering of the backsheet, and use a colorimeter to measure the Δb value. If the backsheet does not crack, does not powder, and Δb < 2, it is judged that the backsheet protection effect is OK; otherwise, the protection effect is NG.

[0071] The test results of all samples are shown in Table 1.

[0072] Table 1 Performance test results of the examples and comparative examples

[0073]

[0074]

[0075] The applicant declares that the present invention uses the above embodiments to illustrate the photovoltaic encapsulation adhesive film, its preparation method and application of the present invention. However, the present invention is not limited to the above embodiments, that is, it does not mean that the present invention must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvement of the present invention, the equivalent substitution of each raw material of the product of the present invention, the addition of auxiliary components, the selection of specific methods, etc. all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A photovoltaic encapsulation film, characterized in that: The raw materials for preparing the photovoltaic encapsulation film include the following components in parts by mass: 100 parts by mass of a resin matrix, 0.01 to 0.5 parts by mass of lignin, 0.05 to 2 parts by mass of a cross-linking agent, 0.05 to 5 parts by mass of a co-cross-linking agent, 0.01 to 1 parts by mass of a tackifier, and 0.01 to 0.2 parts by mass of a light stabilizer.

2. The photovoltaic encapsulation film according to claim 1, characterized in that: The resin matrix is ​​one or a combination of at least two of ethylene-vinyl acetate copolymer, ethylene copolymer, propylene copolymer, ethylene-butene copolymer or ethylene-octene copolymer, preferably ethylene-vinyl acetate copolymer or ethylene-octene copolymer; Preferably, the vinyl acetate content in the ethylene-vinyl acetate copolymer is 10 to 33%, preferably 28 to 33%, and the melt index is 10 to 43 g / 10 min, preferably 15 to 25 g / 10 min; Preferably, the melt index of the ethylene-octene copolymer is 3 to 30 g / 10 min, preferably 5 to 15 g / 10 min.

3. The photovoltaic encapsulation film according to claim 1 or 2, characterized in that: The lignin is alkaline lignin or neutral lignin. Preferably, the alkaline lignin is selected from at least one of kraft lignin, alkali lignin, oxygen alkali lignin, ammonia lignin or lime lignin; Preferably, the neutral lignin is selected from at least one of Brous native lignin, Nord lignin, Beckmann lignin or cellulolytic enzyme lignin; Preferably, the lignin is Brown's natural lignin or alkali lignin.

4. The photovoltaic encapsulation film according to any one of claims 1 to 3, characterized in that: The lignin is powdered lignin obtained by drying; More preferably, the drying method is spray drying.

5. The photovoltaic encapsulation film according to any one of claims 1 to 4, characterized in that: The crosslinking agent is tert-butyl peroxy isopropyl carbonate, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, tert-butyl peroxy carbonate-2-ethylhexyl ester, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(tert-amylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(tert-amylperoxy)cyclohexane, 1,1- The invention is a mixture of one or more of bis(tert-butylperoxy)cyclohexane, 2,2-bis(tert-butylperoxy)butane, tert-amyl peroxy-2-ethylhexyl carbonate, 2,5-dimethyl 2,5-bis(benzoylperoxy)-hexane, tert-amyl peroxycarbonate, and tert-butyl peroxy-3,3,5-trimethylhexanoate, and is preferably any one of tert-butylperoxycarbonate-2-ethylhexyl carbonate, tert-amyl peroxy-2-ethylhexyl carbonate, or 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, or a combination of at least two thereof.

6. The photovoltaic encapsulation film according to any one of claims 1 to 5, characterized in that: The auxiliary crosslinking agent is triallyl isocyanurate, triallyl cyanurate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, tris(2-hydroxyethyl)isocyanuric acid triacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated trimethylolpropane triacrylate, ethoxylated glycerol triacrylate, propoxylated glycerol triacrylate, pentaerythritol tetraacrylate, ethoxylated pentaerythritol tetraacrylate, trimethylolpropane tetraacrylate, ditrimethylolpropane tetraacrylate, ditrimethylolpropane tetramethacrylate, propoxylated pentaerythritol tetraacrylate The invention relates to a mixture of one or more of ester, 2,4,6-tris(2-propenyloxy)-1,3,5-triazine, tricyclodecane dimethanol diacrylate, propoxylated neopentyl glycol diacrylate, ethoxylated bisphenol A diacrylate, ethoxylated bisphenol A dimethacrylate, 2-butyl-2-ethyl-1,3-propanediol diacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate and polyethylene glycol dimethacrylate, preferably any one of triallyl isocyanurate, ethoxylated trimethylolpropane triacrylate or propoxylated trimethylolpropane triacrylate or a combination of at least two thereof.

7. The photovoltaic encapsulation film according to any one of claims 1 to 6, characterized in that: The tackifier is a silane coupling agent, specifically a mixture of one or more of vinyl triethoxysilane, vinyl trimethoxysilane, vinyl tri(β-methoxyethoxy)silane, methacryloxypropyl trimethoxysilane, aminopropyl trimethoxysilane, aminopropyl triethoxysilane, and aminopropyl triisopropoxysilane, preferably any one of methacryloxypropyl trimethoxysilane or vinyl trimethoxysilane or a combination of at least two thereof.

8. The photovoltaic encapsulation film according to any one of claims 1 to 7, characterized in that: The light stabilizer is 3,5-di-tert-butyl-4-hydroxy-benzoic acid hexadecyl ester, tris(1,2,2,6,6-pentamethyl-4-piperidinyl)phosphite, sebacate bis-2,2,6,6-tetramethylpiperidinol ester, bis-1-decyloxy-2,2,6,6-tetramethylpiperidin-4-ol sebacate, a polymer of succinic acid and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidinol, N,N'-bis(2, Polymers of 1,6-hexanediamine and morpholine-2,4,6-trichloro-1,3,5-triazine, 1,5,8,12-tetrakis[4,6-bis(N-butyl-N-1,2,2,6,6-pentamethyl-4-piperidinylamino)-1,3,5-triazine-2-yl]-1,5,8,12-tetraazadodecane, poly-{[6-[(1,1,3,3-tetramethylbutyl) -imino]-1,3,5-triazine-2,4-diyl][2-(2,2,6,6-tetramethylpiperidinyl)-nitro]-hexylene-[4-(2,2,6,6-tetramethylpiperidinyl)-amino]} or a combination of at least two thereof, preferably 1,5,8,12-tetrakis[4,6-bis(N-butyl-N-1,2,2,6,6-pentamethyl-4-piperidinylamino)-1,3,5-triazine-2- [(1,1,3,3-tetramethylbutyl)-imino]-1,3,5-triazine-2,4-diyl][2-(2,2,6,6-tetramethylpiperidinyl)-nitro]-hexylidene-[4-(2,2,6,6-tetramethylpiperidinyl)-amino]} or bis-2,2,6,6-tetramethylpiperidinol sebacate or a combination of at least two thereof.

9. A method for preparing a photovoltaic encapsulation film according to any one of claims 1 to 8, characterized in that: The preparation method comprises the following steps: The resin matrix, lignin, a cross-linking agent, a co-cross-linking agent, a tackifier and a light stabilizer are mixed, melt-extruded and cast into a film to obtain the photovoltaic encapsulation adhesive film.

10. Use of the photovoltaic encapsulation film according to any one of claims 1 to 8 in photovoltaic modules.

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