Packaging adhesive film, preparation method thereof and photovoltaic module

Abstract

The invention relates to the technical field of photovoltaic products, in particular to a packaging adhesive film and a preparation method thereof and a photovoltaic module, the packaging adhesive film comprises at least one layer of A-layer adhesive film, and the A-layer adhesive film comprises a pre-crosslinking area pre-crosslinked by laser; based on 100 parts by weight of matrix resin, the A-layer adhesive film comprises 100 parts of matrix resin, 0.01-5 parts of a cross-linking agent, 0.01-3 parts of an assistant cross-linking agent and 0.01-3 parts of a laser initiator. The pre-crosslinking area in the packaging adhesive film is formed by laser pre-crosslinking, so that the crosslinking depth can be ensured, uniform crosslinking of a thick film in the thickness direction can be realized, the pre-crosslinking time can be shortened, the production efficiency can be improved, and the production cost can be reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic products, and in particular to an encapsulation adhesive film, a preparation method thereof, and a photovoltaic module. Background Art

[0002] Generally, in the preparation process of photovoltaic encapsulation adhesive films, in order to improve the heat resistance and dimensional stability of the adhesive films, reduce the fluidity of the adhesive films during lamination, reduce the migration of pigment fillers and additives, shorten the lamination time, etc., the adhesive films are subjected to pre-crosslinking treatment to make them have a crosslinking degree within a certain range. However, the existing pre-crosslinking treatment methods all have deficiencies.

[0003] The existing pre-crosslinking treatment processes include thermal pre-crosslinking, radiation pre-crosslinking, and ultraviolet / infrared pre-crosslinking, etc. Among them, thermal pre-crosslinking generally refers to processing the adhesive film at a specific pressure using high temperature and a heat-initiating crosslinking agent. However, thermal pre-crosslinking requires a long reaction time and has a high requirement for the heat resistance of the adhesive film, thus having low production efficiency and high production cost. In addition, thermal pre-crosslinking cannot achieve pre-crosslinking in specific areas; radiation pre-crosslinking generally refers to using high-energy ionizing rays to initiate crosslinking reactions between polymer chains, and crosslinking aids can also be added to promote the efficiency of radiation pre-crosslinking. On the one hand, due to the limitation of radiation energy, too thick adhesive films cannot be pre-crosslinked by irradiation, and in relatively thick adhesive films, the crosslinking degree may be different in the thickness direction. On the other hand, although radiation pre-crosslinking can achieve pre-crosslinking in some areas, its collimation is poor, and it is difficult to accurately distinguish the pre-crosslinked area and the non-pre-crosslinked area; ultraviolet / infrared pre-crosslinking generally refers to initiating crosslinking reactions under ultraviolet light or infrared light irradiation. When light propagates in the adhesive film, affected by scattering and absorption, the amount of light reaching the deep part of the adhesive film decreases, resulting in different crosslinking degrees in the thickness direction of the adhesive film. Although ultraviolet / infrared combined with a photomask can achieve pre-crosslinking in specific areas, due to reasons such as light scattering, it is still difficult to accurately control the area where pre-crosslinking occurs.

[0004] In view of the problems existing in the above related technologies, it is very necessary to develop a pre-crosslinked adhesive film with a reliable pre-crosslinking method and uniform pre-crosslinking in the thickness direction and its photovoltaic module. Summary of the Invention

[0005] The present invention provides an encapsulation adhesive film, a preparation method thereof, and a photovoltaic module, so as to solve the problems in the prior art that the pre-crosslinking treatment method of photovoltaic encapsulation adhesive films has a long pre-crosslinking time, a high requirement for the heat resistance of the adhesive film, low production efficiency, high production cost, uneven pre-crosslinking degree in the thickness direction, etc.

[0006] According to the first aspect of the present invention, the present invention provides a packaging adhesive film, which includes at least one layer of A-layer adhesive film, and the A-layer adhesive film includes a pre-crosslinked region that has been laser pre-crosslinked; based on 100 parts by weight of the matrix resin, the A-layer adhesive film includes 100 parts of matrix resin, 0.01 to 5 parts of crosslinking agent, 0.01 to 3 parts of co-crosslinking agent, and 0.01 to 3 parts of laser initiator.

[0007] Further, the laser initiator is selected from one or more of bis(2,6-difluoro-3-pyrrolylphenyl)titanocene, N-phenylglycine, disodium tetrachlorotetraiodofluorescein, 4,4'-di(azido)-3,3'-dimethylbiphenyl, 4,4'-di(azido)diphenylamine, 1,5-di(azido)anthraquinone, and 4-phenoxydibenzophenone.

[0008] Further, the matrix resin is selected from one or more of vinyl resins.

[0009] Further, the crosslinking agent is selected from one or more of organic peroxides.

[0010] Further, the co-crosslinking agent is selected from one or more of triallyl isocyanurate, triallyl cyanurate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, and pentaerythritol triacrylate.

[0011] Further, the laser initiator includes bis(2,6-difluoro-3-pyrrolylphenyl)titanocene, N-phenylglycine, and disodium tetrachlorotetraiodofluorescein; wherein, the mass ratio of bis(2,6-difluoro-3-pyrrolylphenyl)titanocene, N-phenylglycine to disodium tetrachlorotetraiodofluorescein is (4 to 6):(2 to 4):(1 to 1.8); Or, the laser initiator is compounded by any one of 4,4'-di(azido)-3,3'-dimethylbiphenyl, 4,4'-di(azido)diphenylamine, and 1,5-di(azido)anthraquinone and 4-phenoxydibenzophenone; wherein, the mass ratio of any one of 4,4'-di(azido)-3,3'-dimethylbiphenyl, 4,4'-di(azido)diphenylamine, and 1,5-di(azido)anthraquinone to 4-phenoxydibenzophenone is (3 to 5):1.

[0012] Further, the A-layer adhesive film further includes a non-pre-crosslinked region that has not been laser pre-crosslinked.

[0013] Further, the pre-crosslinked region corresponds to the region of the battery cell to be packaged; the ratio of the area of the pre-crosslinked region to the area of the battery cell is (0.2 - 1):1, preferably (0.7 - 0.95):1; Preferably, the pre-crosslinked region is formed by arranging a plurality of rectangular regions in an array; the length and width of each rectangular region are independently 80 - 250 mm; and / or, along the length direction and / or width direction of the encapsulation film, the distance between two adjacent rectangular regions is 2 - 50 mm.

[0014] Furthermore, the pre-crosslinked region corresponds to the grid lines of the battery cell to be encapsulated and / or the solder tapes of the photovoltaic module; the pre-crosslinked region is composed of one or more strip-shaped regions, and each strip-shaped region extends along the length direction of the encapsulation film; Preferably, the width of the strip-shaped region is 0.2 - 8 mm; and / or, the ratio of the width of the strip-shaped region to the width of the grid line or the solder tape is (0.8 - 2):1; and / or, the width of the non-pre-crosslinked region between two adjacent strip-shaped regions is 8 - 30 mm.

[0015] According to the second aspect of the present invention, the present invention also provides a method for preparing the above-mentioned encapsulation film, including the following steps: Mix the matrix resin, crosslinking agent, co-crosslinking agent and laser initiator evenly, then plastify and extrude, cast into a film, and perform pre-crosslinking treatment to prepare an A-layer film; wherein, the A-layer film is subjected to pre-crosslinking treatment by laser radiation to form a pre-crosslinked region on the A-layer film.

[0016] Furthermore, the types of lasers used for the laser radiation include one or more of KrF excimer laser, Ar ion laser and YAG laser.

[0017] Furthermore, the laser wavelength range of the laser radiation is 200 - 600 nm.

[0018] Furthermore, the shape of the laser spot of the laser radiation includes rectangle, circle, ellipse, rhombus or trapezoid, preferably rectangle or circle.

[0019] Furthermore, the number of light sources of the laser radiation is n, n ≥ 1, and n light sources are arranged in parallel.

[0020] Furthermore, the distance between the light source of the laser radiation and the A-layer film is 50 - 500 mm.

[0021] Furthermore, when the pre-crosslinked region corresponds to the region of the battery cell to be encapsulated, n is less than or equal to the number of pre-crosslinked regions that the A-layer film has along the width direction; Preferably, during the formation of the pre-crosslinked region, the laser light source is intermittently turned on and off, and along the length direction of the encapsulation film, the distance between two adjacent pre-crosslinked regions = t1 * v, where t1 is the intermittent off time and v is the winding line speed of the A-layer film; Alternatively, during the formation of the pre-crosslinked region, keep the laser light source on all the time and start rotating around its own center. Along the length direction of the encapsulation adhesive film, the distance between two adjacent pre-crosslinked regions = t2 * v, where t2 is the time taken for the laser light source to rotate 360°, and v is the winding linear speed of the A-layer adhesive film; Alternatively, during the formation of the pre-crosslinked region, use a mask between the laser light source and the A-layer adhesive film. When using the mask, intermittently turn on and off the laser light source or keep it on all the time. The linear speed of the mask movement is equal to the winding linear speed of the A-layer adhesive film; preferably, the opening of the mask is rectangular, and the ratio of the opening area to the area of the pre-crosslinked region is (0.8 - 1.2):1.

[0022] Furthermore, when the pre-crosslinked region corresponds to the grid lines of the battery cell to be encapsulated and / or the solder ribbons of the photovoltaic module and n = 1, the ratio of the maximum width of the laser light source spot in the width direction of the A-layer adhesive film to the width of the A-layer adhesive film is (0.8 - 1.2):1; preferably, use a mask between the laser light source and the A-layer adhesive film. When using the mask, keep the mask stationary. The mask has m parallel openings in the width direction of the A-layer adhesive film, where m is less than or equal to the number of pre-crosslinked regions of the A-layer adhesive film along the width direction. The ratio of the maximum width of the opening shape in the width direction of the A-layer adhesive film to the width of the pre-crosslinked region is (0.8 - 1.2):1, and the ratio of the minimum distance between the m openings in the width direction of the A-layer adhesive film to the width of the non-pre-crosslinked region of the A-layer adhesive film is (0.8 - 1.2):1; When the pre-crosslinked region corresponds to the grid lines of the battery cell to be encapsulated and / or the solder ribbons of the photovoltaic module and n > 1, the ratio of the maximum width of the laser light source spot in the width direction of the A-layer adhesive film to the width of the pre-crosslinked region is (0.8 - 10):1.

[0023] According to the third aspect of the present invention, the present invention also provides a photovoltaic module, including the above-mentioned encapsulation adhesive film.

[0024] An encapsulation adhesive film provided by the present invention includes at least one layer of A-layer adhesive film. The A-layer adhesive film includes a pre-crosslinked region. Setting the pre-crosslinked region on the A-layer adhesive film can reduce the fluidity of this region, and thus during the lamination process, the adhesive film will not flow between the solder tape and the battery cell to prevent the solder tape from being adhered to the battery cell, and the phenomenon of false soldering can be avoided. The pre-crosslinked region therein is formed by laser pre-crosslinking. The laser has the characteristics of good penetrability, energy focusing, and low thermal effect, which can ensure the crosslinking depth, realize uniform crosslinking of the thick film in the thickness direction, and at the same time can shorten the pre-crosslinking time, improve production efficiency, and reduce production costs. In order to further improve the efficiency of laser pre-crosslinking, a laser initiator is added to the A-layer adhesive film, so that it can achieve better synergy with the laser and improve the absorption rate of the adhesive film to the laser. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0026] Figure 1 is one of the structural schematic diagrams of an encapsulation adhesive film provided by the present invention.

[0027] Figure 2 is another structural schematic diagram of an encapsulation adhesive film provided by the present invention.

[0028] Figure 3 is yet another structural schematic diagram of an encapsulation adhesive film provided by the present invention.

[0029] Figure 4 is still another structural schematic diagram of an encapsulation adhesive film provided by the present invention.

[0030] Figure 5 is one of the schematic diagrams of the device for pre-crosslinking treatment of the A-layer adhesive film provided by the present invention by laser radiation.

[0031] Figure 6 is another schematic diagram of the device for pre-crosslinking treatment of the A-layer adhesive film provided by the present invention by laser radiation.

[0032] Figure 7 is yet another schematic diagram of the device for pre-crosslinking treatment of the A-layer adhesive film provided by the present invention by laser radiation.

[0033] Figure 8 is one of the schematic diagrams of the device for unreeling the A-layer adhesive film provided by the present invention for pre-crosslinking treatment by laser radiation and then reeling it up.

[0034] Figure 9It is one of the schematic structural diagrams of the mask provided by the present invention.

[0035] Figure 10 It is the second of the schematic structural diagrams of the mask provided by the present invention.

[0036] Figure 11 It is the third of the schematic structural diagrams of the mask provided by the present invention.

[0037] Reference numerals: 1: A-layer film; 11: Pre-crosslinked area; 111: Rectangular area; 112: Strip area; 12: Non-pre-crosslinked area; 2: Light source; 3: Mask; 30: Opening; 4: Support roller; 5: Extrusion die head; 6: Reel. Specific embodiments

[0038] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without making creative efforts fall within the scope of protection of the present invention.

[0039] As analyzed in the background art, the pre-crosslinking treatment methods of photovoltaic encapsulation films in the prior art include thermal pre-crosslinking, radiation pre-crosslinking, ultraviolet / infrared pre-crosslinking, etc. These pre-crosslinking methods have problems such as long pre-crosslinking time, high requirements for the heat resistance of the film, high requirements for equipment, low production efficiency, high production cost, and uneven pre-crosslinking in the thickness direction.

[0040] In the first typical embodiment of the present invention, the present invention provides a packaging film, including at least one layer of A-layer film 1. As Figures 1-4 shown, the A-layer film 1 includes a pre-crosslinked area 11 that has been laser pre-crosslinked; based on 100 parts by weight of the matrix resin, the A-layer film 1 includes 100 parts of matrix resin, 0.01 - 5 parts of crosslinking agent, 0.01 - 3 parts of co-crosslinking agent, and 0.01 - 3 parts of laser initiator.

[0041] In the above solution, the encapsulation adhesive film of the present invention comprises at least one layer of A-layer adhesive film 1. The A-layer adhesive film 1 includes a pre-crosslinked region 11. Setting the pre-crosslinked region 11 on the A-layer adhesive film 1 can reduce the fluidity of this region, so that during the lamination process, the adhesive film will not flow between the solder tape and the battery cell to hinder the bonding of the solder tape to the battery cell, and can avoid the phenomenon of false soldering. The pre-crosslinked region 11 therein is formed by laser pre-crosslinking. The laser has the characteristics of good penetrability, energy focusing, and low thermal effect. Due to the good penetrability and energy focusing of the laser, the crosslinking depth is guaranteed, uniform crosslinking in the thickness direction of the thick film can be achieved, and at the same time, the time of pre-crosslinking can be shortened, the production efficiency can be improved, and the production cost can be reduced. In order to further improve the efficiency of laser pre-crosslinking, a laser initiator is added to the A-layer adhesive film 1, so that it can achieve better synergy with the laser and improve the absorption rate of the adhesive film to the laser. The present invention further limits the dosages of the various components in the A-layer adhesive film 1 within a reasonable range value, so that the various components can play better synergy, enabling the A-layer adhesive film 1 to better achieve pre-crosslinking while ensuring the bonding performance of its structure, and achieving a good encapsulation effect. According to some specific embodiments of the present invention, the pre-crosslinking degree of the pre-crosslinked region 11 is 2 to 30%.

[0042] Optionally, the pre-crosslinking degree of the pre-crosslinked region 11 can be 2%, 5%, 8%, 10%, 15%, 20%, 25% or 30%, etc. Of course, it can also be other values within the above range, which are not limited herein.

[0043] In the above solution, by limiting the pre-crosslinking degree of the pre-crosslinked region 11 within a reasonable range value, while ensuring the reduction of the overall fluidity of the A-layer adhesive film 1, it will not affect the adhesiveness of the adhesive film, and avoid the generation of bubbles in the components to be encapsulated and the occurrence of phenomena such as hidden cracks in the battery cells.

[0044] According to some specific embodiments of the present invention, the pre-crosslinking degree of the pre-crosslinked region 11 is 3 to 15%.

[0045] According to some specific embodiments of the present invention, the laser initiator is selected from one or more of bis(2,6-difluoro-3-pyrrolylphenyl)titanocene, N-phenylglycine, disodium tetrachlorotetraiodofluorescein, 4,4'-di-azido-3,3'-dimethylbiphenyl, 4,4'-di-azidodiphenylamine, 1,5-di-azidoanthraquinone, and 4-phenoxydibenzophenone.

[0046] In the above solution, by reasonably limiting the type of the laser initiator, the A-layer adhesive film and the laser can achieve better synergy and improve the absorption rate of the adhesive film to the laser.

[0047] According to some specific embodiments of the present invention, the laser initiator includes bis(2,6-difluoro-3-pyrrolylphenyl)titanocene, N-phenylglycine, and disodium tetrachlorotetraiodofluorescein; wherein, the mass ratio of bis(2,6-difluoro-3-pyrrolylphenyl)titanocene:N-phenylglycine:disodium tetrachlorotetraiodofluorescein is (4-6):(2-4):(1-1.8).

[0048] According to some specific embodiments of the present invention, the laser initiator is a compound prepared by mixing any one of 4,4'-di(azido)-3,3'-dimethylbiphenyl, 4,4'-di(azido)diphenylamine, and 1,5-di(azido)anthraquinone with 4-phenoxydibenzophenone; wherein, the mass ratio of any one of 4,4'-di(azido)-3,3'-dimethylbiphenyl, 4,4'-di(azido)diphenylamine, and 1,5-di(azido)anthraquinone to 4-phenoxydibenzophenone is (3-5):1, preferably (3.1-4.6):1.

[0049] According to some specific embodiments of the present invention, the matrix resin is selected from one or more of vinyl resins; Preferably, the matrix resin is selected from one or more of the following compounds: ethylene-vinyl acetate copolymer, polyvinyl butyral, metallocene-catalyzed polyethylene, ethylene-butene copolymer, ethylene-octene copolymer, ethylene-pentene copolymer, ethylene-methyl acrylate copolymer, ethylene-methyl methacrylate copolymer, ethylene-glycidyl methacrylate copolymer, ethylene-glycidyl methacrylate-vinyl acetate copolymer, ethylene-glycidyl methacrylate-methyl acrylate copolymer, saponified ethylene-vinyl acetate copolymer, saponified ethylene-vinyl acetate-acrylate copolymer, low-density polyethylene, linear low-density polyethylene, and linear ultra-low density polyethylene.

[0050] According to some specific embodiments of the present invention, the matrix resin is selected from one or more of ethylene-vinyl acetate copolymer (EVA), polyvinyl butyral (PVB), and ethylene-α-olefin copolymer (POE). The VA content in EVA generally ranges from 20% to 40%. The degree of acetalization of PVB is greater than 80%. The weight percentage of α-olefin in the comonomer of POE is greater than 20%.

[0051] According to some specific embodiments of the present invention, the crosslinking agent is selected from one or more of organic peroxides.

[0052] Preferably, the crosslinking agent is selected from one or more of the following compounds: 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 2-ethylhexyl percarbonate, 2,5-dimethyl-2,5-bis(benzoylperoxy)hexane, tert-amyl percarbonate, tert-butyl 3,3,5-trimethylhexanoate peroxide.

[0053] According to some specific embodiments of the present invention, the co-crosslinking agent is selected from one or more of triallyl isocyanurate, triallyl cyanurate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, and pentaerythritol triacrylate.

[0054] According to some specific embodiments of the present invention, the A-layer film 1 may further include one or more of the following components: 0 to 40 parts of pigment, 0.01 to 2 parts of light stabilizer, 0.01 to 2 parts of ultraviolet absorber, and 0.01 to 2 parts of tackifier.

[0055] According to some specific embodiments of the present invention, the pigment is selected from one or more of the following materials: calcium carbonate, barium sulfate, talc powder, titanium dioxide, zinc oxide, carbon black, graphene, graphene oxide, copper chromite black, magnesium hydroxide, aluminum hydroxide, alumina, magnesia, boron nitride, silicon carbide, ammonium phosphate, ammonium polyphosphate, pentaerythritol, dipentaerythritol, polyol esters of dipentaerythritol, melamine borate polyphosphate.

[0056] According to some specific embodiments of the present invention, the light stabilizer is selected from one or more of the following compounds: cetyl 3,5-di-tert-butyl-4-hydroxybenzoate, tris(1,2,2,6,6-pentamethyl-4-piperidyl) phosphite, bis(2,2,6,6-tetramethylpiperidin-4-yl) sebacate, bis(1-decyloxy-2,2,6,6-tetramethylpiperidin-4-yl) sebacate, polymer of succinic acid and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidinol, polymer of N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl)-1,6-hexanediamine and 2,4-dichloro-6-(1,1,3,3-tetramethylbutyl)amino-1,3,5-triazine, polymer of N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl)-1,6-hexanediamine and morpholine-2,4,6-trichloro-1,3,5-triazine.

[0057] According to some specific embodiments of the present invention, the ultraviolet absorber is selected from one or more of the following compounds: 2-hydroxy-4-n-octyloxybenzophenone, 2,2-tetramethylenebis(3,1-benzoxazine-4-one), 2-(2'-hydroxy-5-methylphenyl)benzotriazole, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone.

[0058] According to some specific embodiments of the present invention, the tackifier is selected from one or more of the following compounds: γ-aminopropyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, vinyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, γ-glycidyletheroxypropyltrimethylsilane, 3-aminopropyltrimethylsilane.

[0059] According to some specific embodiments of the present invention, as Figures 1-3 shown, the A-layer film further includes a non-pre-crosslinked region 12 that has not been pre-crosslinked by laser. The setting of the non-pre-crosslinked region 12 can prevent the adhesion between the A-layer film and the battery cell or the front and back plates of the photovoltaic module or other film layers from being significantly reduced due to the pre-crosslinking treatment, thus affecting the reliability of the photovoltaic module. Since the laser scattering angle is small, the laser can be collimated and directed at the target object, and precise crosslinking of a specific region can be achieved through laser irradiation treatment. Since the laser thermal effect is low, crosslinking of non-target regions caused by a high thermal effect is avoided.

[0060] According to some specific embodiments of the present invention, the pre-crosslinked region 11 corresponds to the battery cell region to be encapsulated; the ratio of the area of the pre-crosslinked region 11 to the area of the battery cell is (0.2-1):1.

[0061] Optionally, preferably, the ratio of the area of the pre-crosslinked region 11 to the area of the battery cell can be 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1 or 1:1, etc. Of course, it can also be other values within the above range, which are not limited herein. Preferably, it is (0.7-0.95):1.

[0062] In the above solution, the encapsulation adhesive film of the present invention can be used to encapsulate solar cells. The pre-crosslinked region 11 corresponds to the region of the solar cell to be encapsulated. The pre-crosslinked region 11 will reduce the fluidity of the adhesive film corresponding to the solar cell region. However, since the gap region around the solar cell corresponds to the non-pre-crosslinked region 12, the adhesion of this part of the region to the solar cell or the encapsulation adhesive film on the other side of the solar cell is good. By limiting the ratio of the area of the pre-crosslinked region to the area of the solar cell within a reasonable range, the adhesion between the non-pre-crosslinked region in the gap of the solar cell and the adhesive film on the other side of the solar cell can be ensured, thereby ensuring the firmness of the encapsulation and avoiding the occurrence of bubbles. The shape of the pre-crosslinked region 11 can be a regular shape such as a rectangle, a rhombus, a trapezoid, a pentagon, a hexagon, etc., or an irregular shape. Preferably, the pre-crosslinked region 11 is a rectangle. For the encapsulation adhesive film with a rectangular pre-crosslinked region 11, when the non-pre-crosslinked region 12 adheres to the solar cell, a sealed pocket is formed around the solar cell to place the solar cell therein, which can avoid the displacement of the solar cell and meet the sealing requirements.

[0063] Preferably, as Figure 1 shown, the pre-crosslinked region 11 is formed by a plurality of rectangular regions 111 arranged in an array; the length and width of each rectangular region 111 are independently 80 - 250 mm; along the length direction (i.e., the MD direction, the direction in which the adhesive film moves along the equipment operation direction) and / or the width direction (i.e., the TD direction) of the encapsulation adhesive film, the distance between two adjacent rectangular regions 111 is 2 - 50 mm.

[0064] In the above solution, by limiting the length and width of a single rectangular region 111 and the distance between two adjacent rectangular regions 111 within a reasonable range value, the pre-crosslinked region 11 and the non-pre-crosslinked region 12 can be more reasonably matched with the solar cell, better ensuring the improvement of the encapsulation firmness while reducing the overall fluidity of the A-layer adhesive film 1 and avoiding the occurrence of bubbles.

[0065] According to some specific embodiments of the present invention, the pre-crosslinked region 11 corresponds to the grid lines of the solar cell to be encapsulated and / or the position of the solder ribbon in the photovoltaic module; as Figure 2 shown, the pre-crosslinked region 11 is composed of one or more strip-shaped regions 112, and each strip-shaped region 112 extends along the length direction of the encapsulation adhesive film.

[0066] In the above solution, when the encapsulation adhesive film of the present invention encapsulates a solar cell or a photovoltaic module with grid lines and / or solder ribbons, the pre-crosslinked region 11 corresponds to the position of the grid lines and / or solder ribbons. The pre-crosslinked region 11 will reduce the fluidity of the adhesive film corresponding to the grid lines and / or solder ribbon regions. In this way, during the lamination process, the adhesive film in the pre-crosslinked region 11 will not flow into the region between the grid lines and / or solder ribbons, ensuring the connection between the solder ribbon and the solar cell.

[0067] Preferably, the width of the strip-shaped area 112 is 0.2 - 8 mm; the ratio of the width of the strip-shaped area 112 to the width of the grid line or solder strip is (0.8 - 2):1; the width of the non-pre-crosslinked area 12 between two adjacent strip-shaped areas 112 is 8 - 30 mm.

[0068] In the above solution, by limiting the ratio of the width of the strip-shaped area 112 to the width of the grid line or solder strip and the width of the non-pre-crosslinked area 12 within reasonable range values, the pre-crosslinked area 11 and the non-pre-crosslinked area 12 can be more reasonably matched with the grid line or solder strip, better ensuring that while reducing the fluidity of the A-layer adhesive film 1 at the corresponding position of the grid line / solder strip, the encapsulation firmness is improved and the occurrence of bubbles is avoided.

[0069] According to some specific embodiments of the present invention, it includes at least one layer of B-layer adhesive film that has not been pre-crosslinked. The B-layer adhesive film can be any conventional adhesive film purchased on the market.

[0070] According to some specific embodiments of the present invention, based on 100 parts by weight of the matrix resin, the B-layer adhesive film includes: 100 parts of matrix resin, 0.01 - 5 parts of crosslinking agent, and 0.01 - 3 parts of co-crosslinking agent. The B-layer adhesive film can be a transparent layer or a color layer (for example: black, white, and colors such as red, yellow, blue, etc.). When the B-layer adhesive film is a color layer, this encapsulation adhesive film is used as the back film of the photovoltaic module, and the A-layer adhesive film 1 can play a role in preventing the pigment in the B-layer adhesive film from migrating to the front film.

[0071] In the second typical embodiment of the present invention, the present invention also provides the preparation method of the above laser pre-crosslinked encapsulation adhesive film, including the following steps: Mix the matrix resin, crosslinking agent, co-crosslinking agent, and laser initiator evenly, then plasticize and extrude, cast into a film, and perform pre-crosslinking treatment to prepare the A-layer adhesive film 1; wherein, the A-layer adhesive film 1 is subjected to pre-crosslinking treatment by laser radiation to form a pre-crosslinked area 11 on the A-layer adhesive film 1. As Figures 5-7 shown, the pre-crosslinking treatment process can be set after the plasticizing extrusion (extruded from the extrusion die head 5) and the film casting process, and before the winding (wound onto the reel 6) process. As Figure 8 shown, the pre-crosslinking treatment process can also be wound first after the plasticizing extrusion and the film casting process, and then unwound for pre-crosslinking treatment. Among them, the direction indicated by the thick arrow in the figure is the MD direction, that is, the direction in which the adhesive film moves along the equipment operation direction.

[0072] In the above solution, in the process of preparing the A-layer film 1 of the encapsulant film of the present invention, laser radiation is used to pre-crosslink the A-layer film 1. By utilizing the characteristics of good collimation, good penetrability, low energy focusing and low thermal effect of the laser, precise and uniform crosslinking of a specific area can be achieved, and the crosslinking depth is guaranteed, which can shorten the pre-crosslinking time, improve production efficiency and reduce production costs.

[0073] According to some specific embodiments of the present invention, the types of lasers used for laser radiation include one or more of KrF excimer laser, Ar ion laser and YAG laser, but are not limited to the above laser types, as long as lasers that can stably emit lasers satisfying the above characteristic parameters can be used.

[0074] In the above solution, by selecting a suitable type of laser, the efficiency of laser radiation can be improved, and thus more precise and uniform crosslinking can be better achieved.

[0075] According to some specific embodiments of the present invention, the laser wavelength range of laser radiation is 200 - 600 nm.

[0076] In the above solution, by selecting a suitable laser wavelength range and frequency, the efficiency of laser radiation can be further improved, and thus more precise and uniform crosslinking can be better achieved.

[0077] According to some specific embodiments of the present invention, the shape of the laser spot of laser radiation includes rectangle, circle, ellipse, rhombus or trapezoid, and preferably rectangle or circle.

[0078] According to some specific embodiments of the present invention, the number of light sources of laser radiation is n, n ≥ 1, and n light sources are arranged in parallel.

[0079] As Figure 5 shown, the light source 2 of laser radiation needs to maintain a certain distance from the A-layer film 1. According to some specific embodiments of the present invention, the distance between the light source 2 of laser radiation and the A-layer film 1 is 50 - 500 mm.

[0080] Optionally, the distance between the light source 2 of laser radiation and the A-layer film 1 can be 50 mm, 60 mm, 70 mm, 80 mm, 90 mm, 100 mm, 200 mm, 300 mm, 400 mm or 500 mm, etc. Of course, it can also be other values within the above range, which is not limited herein.

[0081] In the above solution, by limiting the distance between the light source 2 of laser radiation and the A-layer film 1 within a reasonable range value, the efficiency of laser radiation can be further improved.

[0082] According to some specific embodiments of the present invention, when the pre-crosslinked region 11 corresponds to the region of the battery cell to be encapsulated, n is less than or equal to the number of pre-crosslinked regions 11 that the A-layer adhesive film 1 has along the width direction (i.e., the TD direction, perpendicular to the MD direction).

[0083] According to some specific embodiments of the present invention, during the formation of the pre-crosslinked region 11, the laser light source 2 is intermittently turned on and off. Along the length direction of the encapsulation adhesive film, the distance between two adjacent pre-crosslinked regions 11 = t1 * v, where t1 is the intermittent off time and v is the winding line speed of the A-layer adhesive film 1.

[0084] In the above solution, during the formation of the pre-crosslinked region 11, the laser light source 2 is intermittently turned on and off. When the laser light source 2 is turned on, the laser irradiates the A-layer adhesive film 1 for pre-crosslinking treatment to form a pre-crosslinked region 11 on the A-layer adhesive film 1. When the laser light source 2 is turned off, the laser does not irradiate the A-layer adhesive film 1 and no pre-crosslinking treatment is performed to form a non-pre-crosslinked region 12 on the A-layer adhesive film 1.

[0085] According to some specific embodiments of the present invention, during the formation of the pre-crosslinked region 11, the laser light source 2 is kept on and starts to rotate around itself. Along the length direction of the encapsulation adhesive film, the distance between two adjacent pre-crosslinked regions 11 = t2 * v, where t2 is the time taken for the laser light source 2 to rotate 360°, and v is the winding line speed of the A-layer adhesive film 1.

[0086] In the above solution, during the formation of the pre-crosslinked region 11, the laser light source 2 is kept on and starts to rotate around itself. When the laser light source 2 is aligned with the A-layer adhesive film 1, pre-crosslinking treatment is performed to form a pre-crosslinked region 11 on the A-layer adhesive film 1. When the laser light source 2 deviates from the A-layer adhesive film 1, no pre-crosslinking treatment is performed to form a non-pre-crosslinked region 12 on the A-layer adhesive film 1.

[0087] According to some specific embodiments of the present invention, during the formation of the pre-crosslinked region 11, as Figure 6 and Figure 7 shown, a mask 3 is used between the laser light source 2 and the A-layer adhesive film 1. When using the mask 3, the laser light source 2 is intermittently turned on and off, or kept on all the time. The linear speed of the movement of the mask 3 is equal to the winding line speed of the A-layer adhesive film 1.

[0088] It should be noted that the mask 3 is a tool widely used in fields such as image processing and semiconductor manufacturing. It usually has openings or specific patterns for controlling the processing area or transferring specific graphics. The structural form of the mask 3 is diverse, and its design depends on specific application requirements. It can be strip-shaped as shown in Figure 9 and Figure 10 shown, or it can be asFigure 11 In the shape of a hollow cylinder in the center as shown.

[0089] According to some specific embodiments of the present invention, the mask 3 can be installed on the support roller 4 of the transfer device and supported in a square shape. The support roller 4 is used to fix the mask 3 and ensure the stability of its relative position with respect to the A-layer adhesive film 1. Alternatively, the mask 3 itself is circular and is placed at the target position and rotated through a support member. The support member is not specifically limited as long as it can achieve the above object, and it can be the support roller 4 or a support frame and a rotating shaft, etc.

[0090] In the above solution, the mask 3 can rotate around the light source 2, and its combination with the laser light source 2 can better achieve pre-crosslinking in a specific area and achieve precise control of the area where pre-crosslinking occurs.

[0091] In order to more precisely control the pre-crosslinked area 11, preferably, as Figure 9 and Figure 10 shown, the opening 30 of the mask 3 is rectangular, and the ratio of the area of the opening 30 to the area of the pre-crosslinked area 11 is (0.8 - 1.2):1. Such a ratio limit can achieve the best pre-crosslinking effect, ensure the clear boundary between the pre-crosslinked area 11 and the non-pre-crosslinked area 12, and avoid the diffusion of the crosslinked area.

[0092] Optionally, the ratio of the area of the opening 30 to the area of the pre-crosslinked area 11 can be 0.8:1, 0.85:1, 0.9:1, 0.95:1, 1:1, 1.05:1, 1.1:1, 1.15:1 or 1.2:1, etc. Of course, it can also be other values within the above range, which are not limited here.

[0093] According to some specific embodiments of the present invention, when the pre-crosslinked area corresponds to the grid lines and / or solder tapes of the photovoltaic module to be encapsulated and n = 1, the ratio of the maximum width of the light spot of the laser light source 2 in the width direction of the A-layer adhesive film 1 to the width of the A-layer adhesive film 1 is (0.8 - 1.2):1. Such a design can improve the efficiency of laser pre-crosslinking.

[0094] Optionally, the ratio of the maximum width of the light spot of the laser light source 2 in the width direction of the A-layer adhesive film 1 to the width of the A-layer adhesive film 1 can be 0.8:1, 0.85:1, 0.9:1, 0.95:1, 1:1, 1.05:1, 1.1:1, 1.15:1 or 1.2:1, etc. Of course, it can also be other values within the above range, which are not limited here.

[0095] Preferably, a mask 3 is used between the laser light source 2 and the A-layer adhesive film 1. The target spot width transmitted onto the A-layer adhesive film 1 is achieved by directly adjusting the spot width emitted by the light source and / or by adjusting the width of the opening of the mask 3. When using the mask 3, the mask 3 remains stationary. The mask 3 has m parallel openings 30 in the width direction of the A-layer adhesive film 1. The ratio of the maximum width of the shape of the opening 30 in the width direction of the A-layer adhesive film 1 to the width of the pre-crosslinking region 11 is (0.8 - 1.2):1. The ratio of the minimum spacing between the m openings 30 in the width direction of the A-layer adhesive film 1 to the width of the non-pre-crosslinking region 12 is (0.8 - 1.2):1.

[0096] Optionally, the ratio of the maximum width of the shape of the opening 30 in the width direction of the A-layer adhesive film 1 to the width of the pre-crosslinking region 11 can be 0.8:1, 0.85:1, 0.9:1, 0.95:1, 1:1, 1.05:1, 1.1:1, 1.15:1 or 1.2:1, etc. Of course, it can also be other values within the above range, which are not limited here. The ratio of the minimum spacing between the m openings 30 in the width direction of the A-layer adhesive film 1 to the width of the non-pre-crosslinking region 12 can be 0.8:1, 0.85:1, 0.9:1, 0.95:1, 1:1, 1.05:1, 1.1:1, 1.15:1 or 1.2:1, etc. Of course, it can also be other values within the above range, which are not limited here.

[0097] In the above solution, by limiting the ratio of the maximum width of the shape of the opening 30 of the mask 30 in the width direction of the A-layer adhesive film 1 to the width of the pre-crosslinking region 11 and the ratio of the minimum spacing between the m openings 30 in the width direction of the A-layer adhesive film 1 to the width of the non-pre-crosslinking region 12 within reasonable range values, the pre-crosslinking region 11 and the non-pre-crosslinking region 12 can be controlled more precisely, so that the arrangement of the pre-crosslinking region 11 and the non-pre-crosslinking region 12 meets the usage requirements.

[0098] Similarly, in order to control the pre-crosslinking region 11 and the non-pre-crosslinking region 12 more precisely, when the pre-crosslinking region 11 corresponds to the grid lines and / or solder tapes of the photovoltaic module to be encapsulated and n > 1, the ratio of the maximum width of the spot of the laser light source 2 in the width direction of the A-layer adhesive film 1 to the width of the pre-crosslinking region 11 is (0.8 - 10):1. If there are more pre-crosslinking regions 11 in the width direction and the number of light sources 2 is small (the number of light sources 2 is much smaller than the number of pre-crosslinking regions 11 in the width direction), at this time the spot size of the light source 2 needs to be much larger than the width of the pre-crosslinking region 11, and the mask 3 is required. When n is equal to the number of pre-crosslinking regions 11 in the width direction, the mask 3 is not necessary.

[0099] Optionally, when the pre-crosslinked region 11 corresponds to the grid lines of the cell to be encapsulated and / or the solder tape position of the photovoltaic module and n>1, the ratio of the maximum width of the light spot of the laser light source 2 in the width direction of the A-layer film 1 to the width of the pre-crosslinked region 11 can be 0.8:1, 0.85:1, 0.9:1, 0.95:1, 1:1, 1.05:1, 1.1:1, 1.15:1, 1.2:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1 or 10:1, etc. Of course, it can also be other values within the above range, which are not limited herein.

[0100] According to some specific embodiments of the present invention, the preparation method further includes: coating a B-layer film with the A-layer film as the base material. If the B-layer film is a formed sheet, it is not compounded with the A-layer film by coating, but by conventional methods such as hot pressing.

[0101] In the third typical embodiment of the present invention, the present invention further provides a photovoltaic module, which includes the above encapsulation film, a cell and a solder tape.

[0102] According to some specific embodiments of the present invention, the pre-crosslinked region of the encapsulation film corresponds to the position of the cell region and / or the solder tape and / or the grid lines of the cell.

[0103] Hereinafter, the beneficial effects of the present invention will be described in conjunction with specific examples and comparative examples.

[0104] Example 1 This example provides an encapsulation film, including an A-layer film. By weight, the A-layer film includes: 100 parts of a matrix resin ethylene-vinyl acetate copolymer (VA mass fraction is 28%), 0.6 parts of a crosslinking agent tert-butyl peroxycarbonate-2-ethylhexyl ester, 1 part of a co-crosslinking agent triallyl isocyanurate, and 1 part of a laser initiator 4,4'-di azido-3,3'-dimethylbiphenyl.

[0105] As Figure 1 shown, the A-layer film 1 includes a pre-crosslinked region 11 and a non-pre-crosslinked region 12 that have been laser pre-crosslinked. The pre-crosslinked region 11 corresponds to the cell region one by one, and the ratio of the area of the pre-crosslinked region 11 to the area of the cell is 1:1; the pre-crosslinked region 11 is formed by arranging a plurality of rectangular regions 111 in an array; the length of each rectangular region 111 is 180 mm, and the width is 90 mm; along the width direction of the encapsulation film, the width of the non-pre-crosslinked region 12 between two adjacent rectangular regions 111 is 5 mm.

[0106] This example provides a preparation method for the above encapsulation film, which specifically includes the following steps: The matrix resin, crosslinking agent, co-crosslinking agent and laser initiator are mixed evenly, then plasticized and extruded, cast into a film, and pre-crosslinked to prepare the A-layer film; among them, the A-layer film is pre-crosslinked by laser radiation to form pre-crosslinked regions and non-pre-crosslinked regions on the A-layer film.

[0107] The laser radiation uses a KrF excimer laser with a laser wavelength of 248 nm and a rectangular light spot; the number of light sources n = 6 (the number of pre-crosslinked regions that the A-layer film has along the width direction); the distance between the light source and the A-layer film is 500 mm; the light source is intermittently turned off, and the product of the intermittent off time t1 and the winding linear velocity v1 of the A-layer film is equal to the distance of 5 mm between two adjacent pre-crosslinked regions in the length direction (winding direction) of the encapsulation film.

[0108] Example 2 This example provides an encapsulation film, which is different from Example 1 in that the laser initiator is 0.8 parts of 4,4'-di(azido)-3,3'-dimethylbiphenyl and 0.2 parts of 4-phenoxydibenzophenone.

[0109] This example also provides a preparation method of the encapsulation film, which is different from Example 1 in that the number of light sources n = 1; the distance between the light source and the A-layer film is 500 mm; the light source is always on, and a mask is used between the laser light source and the A-layer film, and the linear velocity of the moving mask is equal to the winding linear velocity of the A-layer film; the opening of the mask is rectangular, and the ratio of the area of the opening to the area of the pre-crosslinked region is 1:1.

[0110] Example 3 This example provides an encapsulation film, which is different from Example 1 in that the laser initiator is 0.8 parts of 4,4'-di(azido)diphenylamine and 0.2 parts of 4-phenoxydibenzophenone. The preparation method of the encapsulation film is the same as that of Example 1.

[0111] Example 4 This example provides an encapsulation film, which is different from Example 1 in that the laser initiator is 0.8 parts of 1,5-di(azido)anthraquinone and 0.2 parts of 4-phenoxydibenzophenone. The preparation method of the encapsulation film is the same as that of Example 1.

[0112] Example 5 This example provides an encapsulation film, which is different from Example 1 in that the laser initiator is 0.76 parts of 4,4'-di(azido)-3,3'-dimethylbiphenyl and 0.24 parts of 4-phenoxydibenzophenone. The preparation method of the encapsulation film is the same as that of Example 1.

[0113] Example 6 This embodiment provides a packaging adhesive film, which is different from that of Embodiment 1 in that the photoinitiator is 0.82 parts of 4,4'-di(azido)-3,3'-dimethylbiphenyl and 0.18 parts of 4-phenoxydibenzophenone. The preparation method of the packaging adhesive film is the same as that of Embodiment 1.

[0114] Embodiment 7 This embodiment provides a packaging adhesive film, which is different from that of Embodiment 1 in that the photoinitiator is 0.4 parts of bis(2,6-difluoro-3-pyrrolylphenyl)titanocene, 0.2 parts of N-phenylglycine, and 0.1 part of disodium tetrachlorotetraiodofluorescein. The preparation method of the packaging adhesive film is the same as that of Embodiment 1.

[0115] Embodiment 8 This embodiment provides a packaging adhesive film, which is different from that of Embodiment 1 in that the photoinitiator is 0.4 parts of bis(2,6-difluoro-3-pyrrolylphenyl)titanocene, 0.4 parts of N-phenylglycine, and 0.1 part of disodium tetrachlorotetraiodofluorescein. The preparation method of the packaging adhesive film is the same as that of Embodiment 1.

[0116] Embodiment 9 This embodiment provides a packaging adhesive film, which is different from that of Embodiment 1 in that the photoinitiator is 0.6 parts of bis(2,6-difluoro-3-pyrrolylphenyl)titanocene, 0.2 parts of N-phenylglycine, and 0.1 part of disodium tetrachlorotetraiodofluorescein. The preparation method of the packaging adhesive film is the same as that of Embodiment 1.

[0117] Embodiment 10 This embodiment provides a packaging adhesive film, which is different from that of Embodiment 1 in that the photoinitiator is 0.4 parts of bis(2,6-difluoro-3-pyrrolylphenyl)titanocene, 0.2 parts of N-phenylglycine, and 0.18 parts of disodium tetrachlorotetraiodofluorescein. The preparation method of the packaging adhesive film is the same as that of Embodiment 1.

[0118] Embodiment 11 This embodiment provides a packaging adhesive film, which is different from that of Embodiment 1 in that the photoinitiator is 3 parts of 4,4'-di(azido)-3,3'-dimethylbiphenyl. The preparation method of the packaging adhesive film is the same as that of Embodiment 1.

[0119] Embodiment 12 This embodiment provides a packaging adhesive film, which is different from that of Embodiment 1 in that the photoinitiator is 2 parts of 4,4'-di(azido)-3,3'-dimethylbiphenyl. The preparation method of the packaging adhesive film is the same as that of Embodiment 1.

[0120] Embodiment 13 This embodiment provides a packaging adhesive film, which is different from that of Embodiment 1 in that the photoinitiator is 0.5 parts of 4,4'-di(azido)-3,3'-dimethylbiphenyl. The preparation method of the packaging adhesive film is the same as that of Embodiment 1.

[0121] Example 14 This example provides a packaging film, which is different from that in Example 1 in that the photoinitiator is 0.01 part of 4,4'-di(azido)-3,3'-dimethylbiphenyl. The preparation method of the packaging film is the same as that in Example 1.

[0122] Example 15 This example provides a packaging film, which is different from that in Example 1 in that the ratio of the area of the pre-crosslinked region to the area of the cell is 0.2:1; the pre-crosslinked region is rectangular, with a length of 144 mm and a width of 22.5 mm; along the width direction of the packaging film, the width of the non-pre-crosslinked region is 41 mm. The product of the intermittent shutdown time t1 and the winding line speed v1 of the A-layer film is equal to the distance of 72.5 mm between two adjacent pre-crosslinked regions in the length direction (winding direction) of the packaging film. The preparation method is the same as that in Example 1.

[0123] Example 16 This example provides a packaging film, which is different from that in Example 1 in that the ratio of the area of the pre-crosslinked region to the area of the cell is 0.5:1; the pre-crosslinked region is rectangular, with a length of 90 mm and a width of 90 mm; along the width direction of the packaging film, the width of the non-pre-crosslinked region is 95 mm; the product of the intermittent shutdown time t1 and the winding line speed v1 of the A-layer film is equal to the distance of 5 mm between two adjacent pre-crosslinked regions in the length direction (winding direction) of the packaging film. The preparation method is the same as that in Example 1.

[0124] Example 17 This example provides a packaging film, which is different from that in Example 1 in that the ratio of the area of the pre-crosslinked region to the area of the cell is 0.7:1; the pre-crosslinked region is rectangular, with a length of 180 mm and a width of 63 mm; along the width direction of the packaging film, the width of the non-pre-crosslinked region is 5 mm; the product of the intermittent shutdown time t1 and the winding line speed v1 of the A-layer film is equal to the distance of 32 mm between two adjacent pre-crosslinked regions in the length direction (winding direction) of the packaging film. The preparation method is the same as that in Example 1.

[0125] Example 18 This example provides a packaging film, which is different from that in Example 1 in that the ratio of the area of the pre-crosslinked region to the area of the cell is 0.7:1; the pre-crosslinked region is rectangular, with a length of 126 mm and a width of 90 mm; along the width direction of the packaging film, the width of the non-pre-crosslinked region is 59 mm. The product of the intermittent shutdown time t1 and the winding line speed v1 of the A-layer film is equal to the distance of 5 mm between two adjacent pre-crosslinked regions in the length direction (winding direction) of the packaging film. The preparation method is the same as that in Example 1.

[0126] Example 19 This embodiment provides a packaging adhesive film, which is different from that of Embodiment 1 in that: the ratio of the area of the pre-crosslinked region to the area of the battery cell is 0.95:1; the pre-crosslinked region is rectangular, with a length of 171 mm and a width of 90 mm; along the width direction of the packaging adhesive film, the width of the non-pre-crosslinked region is 14 mm. The product of the intermittent closing time t1 and the winding line speed v1 of the A-layer adhesive film is equal to the distance of 5 mm between two adjacent pre-crosslinked regions in the length direction (winding direction) of the packaging adhesive film. Its preparation method is the same as that of Embodiment 1.

[0127] Embodiment 20 This embodiment provides a packaging adhesive film, which is different from that of Embodiment 1 in that: the ratio of the area of the pre-crosslinked region to the area of the battery cell is 1:1; the pre-crosslinked region is rectangular, with a length of 210 mm and a width of 210 mm; along the width direction of the packaging adhesive film, the width of the non-pre-crosslinked region is 5 mm. The product of the intermittent closing time t1 and the winding line speed v1 of the A-layer adhesive film is equal to the distance of 2 mm between two adjacent pre-crosslinked regions in the length direction (winding direction) of the packaging adhesive film. Its preparation method is the same as that of Embodiment 1.

[0128] Embodiment 21 This embodiment provides a packaging adhesive film, which is different from that of Embodiment 1 in that: the pre-crosslinked region is strip-shaped and corresponds to the position of the solder tape (such as Figure 2 ), the width of the strip-shaped region is 2 mm; the ratio of the width of the strip-shaped region to the width of the grid line or the solder tape is 1:1; the width of the non-pre-crosslinked region between two adjacent strip-shaped regions is 10 mm.

[0129] This embodiment also provides a preparation method of the above packaging adhesive film, which specifically includes the following steps: Mix the matrix resin, crosslinking agent, co-crosslinking agent and laser initiator evenly, then plasticize and extrude, cast into a film, and perform pre-crosslinking treatment to prepare the A-layer adhesive film; among them, the A-layer adhesive film is pre-crosslinked by laser radiation to form a pre-crosslinked region and a non-pre-crosslinked region on the A-layer adhesive film.

[0130] The laser radiation is an Ar ion laser, 514 nm, circular light spot; the number of light sources n = 1; the distance between the light source and the A-layer adhesive film is 500 mm; the light source is always on; a mask is used between the laser light source and the A-layer adhesive film, the mask remains stationary, the number of parallel openings of the mask in the width direction of the A-layer adhesive film is the same as the number of pre-crosslinked regions, and the ratio of the maximum width of the opening shape in the width direction of the A-layer adhesive film to the width of the pre-crosslinked region is 1:1, and the ratio of the minimum distance between the openings in the width direction of the A-layer adhesive film to the width of the non-pre-crosslinked region is 1:1.

[0131] Embodiment 22 This embodiment provides an encapsulation film, which is different from that of Embodiment 21 in that: the width of the strip region is 4 mm; the ratio of the width of the strip region to the width of the grid line or the solder strip is 2:1; the width of the non-pre-crosslinked region between two adjacent strip regions is 8 mm.

[0132] This embodiment also provides a method for preparing the above encapsulation film, which is different from that of Embodiment 21 in that: the laser radiation is YAG laser, 514 nm, circular spot; the number of light sources n = the number of pre-crosslinked regions in the width direction of the A-layer film; the distance between the light source and the A-layer film is 500 mm; the light source is always on.

[0133] Embodiment 23 This embodiment provides an encapsulation film, which is different from that of Embodiment 21 in that: the width of the strip region is 8 mm; the ratio of the width of the strip region to the width of the grid line or the solder strip is 4:1; the width of the non-pre-crosslinked region between two adjacent strip regions is 4 mm. The preparation method is the same as that of Embodiment 21.

[0134] Embodiment 24 This embodiment provides an encapsulation film, which is different from that of Embodiment 21 in that: the width of the strip region is 1 mm; the ratio of the width of the strip region to the width of the grid line or the solder strip is 0.5:1; the width of the non-pre-crosslinked region between two adjacent strip regions is 11 mm. The preparation method is the same as that of Embodiment 21.

[0135] Embodiment 25 This embodiment provides an encapsulation film, which is different from that of Embodiment 21 in that: the width of the strip region is 0.4 mm; the ratio of the width of the strip region to the width of the grid line or the solder strip is 0.8:1; the width of the non-pre-crosslinked region between two adjacent strip regions is 15 mm. The preparation method is the same as that of Embodiment 21.

[0136] Embodiment 26 This embodiment provides an encapsulation film, which is different from that of Embodiment 1 in that: the pre-crosslinked region is located in the middle and the non-pre-crosslinked region is located around (such as Figure 3 )), the width of the pre-crosslinked region is 800 mm, the length of the pre-crosslinked region is 1600 mm, and the width of the non-pre-crosslinked region is 40 mm.

[0137] This embodiment also provides a method for preparing the above encapsulation film, which specifically includes the following steps: Mix the matrix resin, crosslinking agent, co-crosslinking agent and laser initiator evenly, then plastify and extrude, cast into a film, and perform pre-crosslinking treatment to prepare an A-layer film; among them, the A-layer film is pre-crosslinked by laser radiation to form a pre-crosslinked region and a non-pre-crosslinked region on the A-layer film.

[0138] The laser radiation is an Ar ion laser, with a wavelength of 514 nm and a circular light spot; the number of light sources n * the diameter of the light spot = the width of the pre-crosslinked area; the distance between the light source and the A-layer film is 500 mm; the light source is intermittently turned off, and the product of the intermittent off time t1 and the winding line speed v1 of the A-layer film is equal to the width of the non-pre-crosslinked area, which is 40 mm.

[0139] Example 27 This example provides a packaging film, which is different from Example 1 in that: the pre-crosslinked area is rectangular (as Figure 4 ), the width of the pre-crosslinked area is 880 mm, and the length of the pre-crosslinked area is 1680 mm.

[0140] This example also provides a method for preparing the above packaging film, which specifically includes the following steps: Mix the matrix resin, crosslinking agent, co-crosslinking agent and laser initiator evenly, then plasticize, extrude, cast into a film, and perform pre-crosslinking treatment to prepare the A-layer film; among them, the A-layer film is pre-crosslinked by laser radiation to form a pre-crosslinked area on the A-layer film.

[0141] The laser radiation is an Ar ion laser, with a wavelength of 514 nm and a circular light spot; the number of light sources n * the diameter of the light spot = the width of the pre-crosslinked area; the distance between the light source and the A-layer film is 500 mm; the light source is always on.

[0142] Comparative Example 1 This comparative example provides a packaging film, which is different from Example 1 in that: the A-layer film does not contain a laser initiator; thermal pre-crosslinking treatment is used. In Comparative Example 1, a packaging film with pre-crosslinking in a specific area cannot be obtained.

[0143] Comparative Example 2 This comparative example provides a packaging film, which is different from Example 1 in that: the A-layer film does not contain a laser initiator; radiation pre-crosslinking treatment is used during the preparation of the packaging film.

[0144] Comparative Example 3 This comparative example provides a packaging film, which is different from Example 1 in that: the A-layer film does not contain a laser initiator; ultraviolet pre-crosslinking treatment is used during the preparation of the packaging film.

[0145] Comparative Example 4 This comparative example provides a packaging film, which is different from Example 1 in that: the laser initiator is 5 parts of 4,4'-di(azido) - 3,3'-dimethylbiphenyl.

[0146] Comparative Example 5 This comparative example provides a packaging film, which is different from Example 1 in that: the laser initiator is 0.005 parts of 4,4'-di(azido) - 3,3'-dimethylbiphenyl.

[0147] The encapsulation films of Examples 1-27 and Comparative Examples 1-5 were tested as follows:

Pre-crosslinking degree

[0148]

Peeling strength

[0149]

Appearance evaluation

[0150] The test results are shown in Table 1 below.

[0151] Table 1

[0152] It can be seen from the experimental results in Table 1 that by adding a specific type and dosage of laser initiator to the encapsulation film in the present invention, a better synergistic effect with the laser can be achieved, the absorption rate of the film to the laser is increased, and precise crosslinking of specific regions can be realized through laser irradiation treatment. At the same time, by limiting the dosage of each component in the encapsulation film within a reasonable range value, a better synergistic effect can be exerted among the components, enabling the encapsulation film to better achieve pre-crosslinking while ensuring the bonding performance of its structure, thus achieving a good encapsulation effect. It can be seen from the comparison results between Example 1 and Comparative Examples 1-3 that compared with other conventional pre-crosslinking treatment methods, the encapsulation film obtained by the laser pre-crosslinking treatment method of the present invention has a good pre-crosslinking effect and a better encapsulation effect. It can be seen from the comparison results between Example 1 and Comparative Examples 4 and 5 that too high a dosage of laser initiator can improve the sensitivity, thereby increasing the pre-crosslinking degree within a specific time. However, too high a pre-crosslinking degree results in a low peeling strength between the encapsulation film and the solar cell and is prone to cracking phenomena. Too low a dosage of laser initiator results in a very low pre-crosslinking degree within a specific time, affecting the production efficiency and not having a good encapsulation effect.

[0153] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A packaging film, characterized in that: The invention comprises at least one layer A adhesive film, wherein the A adhesive film comprises a pre-crosslinked area pre-crosslinked by laser; based on 100 parts by weight of the base resin, the A adhesive film comprises 100 parts of the base resin, 0.01 to 5 parts of the crosslinking agent, 0.01 to 3 parts of the auxiliary crosslinking agent and 0.01 to 3 parts of the laser initiator.

2. The packaging film according to claim 1, characterized in that: The laser initiator is selected from one or more of bis-2,6-difluoro-3-pyrrolophenyl titanocene, N-phenylglycine, disodium tetrachlorotetraiodine fluorescein, 4,4'-diazide-3,3'-dimethylbiphenyl, 4,4'-diazide diphenylamine, 1,5-diazide anthraquinone and 4-phenoxybenzophenone; preferably, the laser initiator includes bis-2,6-difluoro-3-pyrrolophenyl titanocene, N-phenylglycine and disodium tetrachlorotetraiodine fluorescein; wherein, the bis-2,6-difluoro-3-pyrrolophenyl titanocene, N-phenylglycine, disodium tetrachlorotetraiodine fluorescein The mass ratio of disodium fluoride is (4-6): (2-4): (1-1.8); or, preferably, the laser initiator is a compound of any one of 4,4'-diazide-3,3'-dimethylbiphenyl, 4,4'-diazide diphenylamine, and 1,5-diazide anthraquinone and 4-phenoxybenzophenone; wherein the mass ratio of any one of 4,4'-diazide-3,3'-dimethylbiphenyl, 4,4'-diazide diphenylamine, and 1,5-diazide anthraquinone and 4-phenoxybenzophenone is (3-5): 1; And / or, the base resin is selected from one or more vinyl resins; And / or, the cross-linking agent is selected from one or more organic peroxides; And / or, the auxiliary cross-linking agent is selected from one or more of triallyl isocyanurate, triallyl cyanurate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate and pentaerythritol triacrylate.

3. The encapsulation film according to any one of claims 1 to 2, characterized in that: The A-layer adhesive film also includes a non-pre-crosslinked area that has not been pre-crosslinked by laser.

4. The packaging film according to claim 3, characterized in that: The pre-crosslinked region corresponds to the region of the battery cell to be encapsulated; the ratio of the area of ​​the pre-crosslinked region to the area of ​​the battery cell is (0.2-1):1, preferably (0.7-0.95):1; Preferably, the pre-crosslinked area is formed by a plurality of rectangular areas arranged in an array; the length and width of each rectangular area are independently 80-250 mm; and / or, along the length and / or width direction of the packaging film, the distance between two adjacent rectangular areas is 2-50 mm.

5. The packaging film according to claim 3, characterized in that: The pre-crosslinking region corresponds to the grid lines of the cell to be encapsulated and / or the welding strip position in the photovoltaic module; the pre-crosslinking region is composed of one or more strip-shaped regions, each of which extends along the length direction of the encapsulation film; Preferably, the width of the strip region is 0.2-8 mm; and / or the ratio of the width of the strip region to the width of the grid line or the welding strip is (0.8-2):1; and / or the width of the non-pre-crosslinked region between two adjacent strip regions is 8-30 mm.

6. The method for preparing the encapsulating adhesive film according to any one of claims 1 to 5, characterized in that: The steps include: The matrix resin, cross-linking agent, auxiliary cross-linking agent and laser initiator are mixed evenly, and then plasticized, extruded, cast into film, and pre-cross-linked to prepare a layer A adhesive film; wherein the layer A adhesive film is pre-cross-linked by laser radiation to form a pre-cross-linked area on the layer A adhesive film.

7. The preparation method according to claim 6, characterized in that: The laser radiation adopts one or more of KrF excimer laser, Ar ion laser and YAG laser; And / or, the laser wavelength range of the laser radiation is 200-600nm; And / or, the laser spot shape of the laser radiation includes rectangle, circle, ellipse, diamond or trapezoid, preferably rectangle or circle; And / or, the number of light sources of the laser radiation is n, n ≥ 1, and the n light sources are arranged in parallel; And / or, the distance between the light source of the laser radiation and the A layer of adhesive film is 50-500 mm.

8. The preparation method according to claim 7, characterized in that: When the pre-crosslinked region corresponds to the battery cell region to be encapsulated, n is less than or equal to the number of pre-crosslinked regions of the A layer of adhesive film along the width direction; Preferably, during the formation of the pre-crosslinked area, the laser light source is intermittently turned on and off, and along the length direction of the packaging film, the distance between two adjacent pre-crosslinked areas = t1*v, where t1 is the intermittent closing time, and v is the winding line speed of the A layer of film; Or, during the formation of the pre-crosslinked area, the laser light source is always turned on and starts to rotate with itself as the center, wherein along the length direction of the packaging film, the distance between two adjacent pre-crosslinked areas = t2*v, wherein t2 is the time taken for the laser light source to rotate 360°, and v is the winding linear speed of the A layer of film; Alternatively, during the formation of the pre-cross-linked area, a mask is used between the laser light source and layer A of the adhesive film. When the mask is used, the laser light source is turned on and off intermittently, or is normally on, and the linear speed of movement of the mask is equal to the winding linear speed of layer A of the adhesive film; preferably, the opening of the mask is rectangular, and the ratio of the area of ​​the opening to the area of ​​the pre-cross-linked area is (0.8-1.2):

1.

9. The preparation method according to claim 7, characterized in that: When the pre-crosslinked region corresponds to the grid line of the cell to be encapsulated and / or the welding strip position in the photovoltaic module and n=1, the ratio of the maximum width of the spot of the laser light source in the width direction of the A-layer adhesive film to the width of the A-layer adhesive film is (0.8-1.2): 1; preferably, a mask is used between the laser light source and the A-layer adhesive film. When the mask is used, the mask remains stationary, and the mask has m parallel openings in the width direction of the A-layer adhesive film, m is less than or equal to the number of pre-crosslinked regions of the A-layer adhesive film along the width direction, the ratio of the maximum width of the opening shape in the width direction of the A-layer adhesive film to the width of the pre-crosslinked region is (0.8-1.2): 1, and the ratio of the minimum spacing between the m openings in the width direction of the A-layer adhesive film to the width of the non-pre-crosslinked region of the A-layer adhesive film is (0.8-1.2): 1; When the pre-crosslinked area corresponds to the grid lines of the cell to be encapsulated and / or the welding strip position of the photovoltaic module and n>1, the ratio of the maximum width of the laser light source spot in the width direction of the A layer of adhesive film to the width of the pre-crosslinked area is (0.8-10):

1.

10. A photovoltaic module, characterized in that: It comprises the encapsulation film according to any one of claims 1 to 5 or the encapsulation film prepared by the preparation method according to any one of claims 6 to 9, a battery cell and a welding strip.

Images