CN111253885A - Adhesive composition, light guide film and solar cell module - Google Patents

Abstract

The present invention provides an adhesive composition comprising a resin binder, a peroxide crosslinking agent, a non-peroxide crosslinking agent, a coupling agent, an ultraviolet absorber and an ultraviolet stabilizer, wherein the adhesive composition undergoes an exothermic reaction at a temperature above 95°C and has an exothermic heat of 2-40 J/g. The present invention also provides a light guide film including a reactive adhesive layer containing the adhesive composition. In addition, the present invention also provides a solar cell module including the light guide film. When the adhesive composition according to the present invention is used as an adhesive layer for adhering a light guide film to a back sheet during assembly of a solar cell module, the adhesion can be avoided while maintaining high adhesion The agent layer is bulged during the high temperature wet heat aging process, and the relative position drift of the light guide film during the high temperature lamination preparation process can be greatly reduced.

Description

Adhesive composition, light directing film and solar cell module

technical field

The present invention relates to the technical field of photovoltaic cells, in particular, to an adhesive composition, a light guide film and a solar cell assembly comprising the same.

Background technique

With the gradual aggravation of environmental problems, the development and application of clean energy is increasingly urgent. Solar energy has received more and more attention as a clean energy. A solar cell is a device that uses solar energy to generate electricity.

A common solar cell today includes a cell body encapsulated in a package cover sheet and a package back sheet. The light is irradiated on the light-facing surface of the battery main body through the packaging cover plate, and the battery main body converts the light energy in the light into electrical energy. In order to improve the power generation efficiency of the solar cell module, a light guide film can be provided inside the solar cell module. When the solar module is used to generate electricity, the light can be irradiated on the optical structure of the light guide film after passing through the light-transmitting element. The optical structure of the light guide film can reflect the incident light and change the propagation direction of the light. Since the light is incident from top to bottom, the light guide film reflects the light upward toward the light-transmitting element. When the light reflected by the light guide film enters the light-transmitting element and propagates to the interface between the light-transmitting element and the air in the light-transmitting element, reflection occurs, the propagation direction of the light changes again, and finally illuminates the solar cell's welcome light On the surface, the solar cells use the light to generate electricity, thereby improving the power generation efficiency. The light directing film is usually adhered by an adhesive layer on the backlit side surface of the solar cell or on the surface of the encapsulating backsheet that is inside the solar cell assembly. However, in an environment of high temperature and high humidity, the adhesive layer will gradually age over time, and a bulge will be formed between the light guide film and the package backplane, resulting in damage to the light guide film or from the adhering surface. fall off.

Therefore, it is of great significance to develop an adhesive material for solar cell modules with good moisture-heat aging resistance.

SUMMARY OF THE INVENTION

Proceeding from the technical problems set forth above, one of the objects of the present invention is to provide an adhesive material for solar cell modules with good moisture and heat aging resistance, which adhesive material has high adhesive force and can be used at high temperature No bulges in the adhesive layer under damp heat aging conditions.

The inventors of the present invention have completed the present invention through intensive and meticulous research.

According to one aspect of the present invention, there is provided an adhesive composition comprising a resin binder, a peroxide cross-linking agent, a non-peroxide cross-linking agent, a coupling agent, a UV absorbing agent and UV stabilizer, wherein the adhesive composition undergoes an exothermic reaction at a temperature above 95°C and has an exothermic heat of 2-40 J/g.

According to certain preferred embodiments of the present invention, the adhesive composition comprises, based on the total weight of the adhesive composition:

90-98% by weight of the resin binder;

0.4-1.4% by weight of the peroxide crosslinking agent;

0.4-1.6% by weight of the non-peroxide crosslinking agent;

0.5-1.5% by weight of the coupling agent;

0.5-4% by weight of the UV absorber; and

0.2-2% by weight of the UV stabilizer.

According to certain preferred embodiments of the present invention, the resin binder is selected from one or more of the group consisting of: ethylene-vinyl acetate (EVA) copolymer, polyolefin resin (PO), polyolefin Propylene oxide (PP), polyvinyl butyral (PVB), tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride (THV) copolymer, ethylene-tetrafluoroethylene (ETFE) copolymer, polyvinylidene fluoride Vinyl (PVDF), Polyurethane (PU), Polymethylmethacrylate (PMMA) and Polyimide (PI).

According to certain preferred embodiments of the present invention, the resin binder has a melt flow index (MFI) in the range of 10-30.

According to certain preferred embodiments of the present invention, the resin binder is an ethylene-vinyl acetate (EVA) copolymer.

According to certain preferred embodiments of the present invention, in the ethylene-vinyl acetate (EVA) copolymer, based on the total weight of the ethylene-vinyl acetate copolymer, the content of repeating units derived from vinyl acetate 24-30% by weight.

According to certain preferred embodiments of the present invention, in the ethylene-vinyl acetate (EVA) copolymer, based on the total weight of the ethylene-vinyl acetate copolymer, the content of repeating units derived from vinyl acetate 26-28% by weight.

According to certain preferred embodiments of the present invention, the peroxide cross-linking agent is selected from one or more of the group consisting of: benzoyl peroxide (BPO), dicumyl peroxide ( DCP), tert-amyl peroxyacetate (TAPA), tert-butyl peroxy-2-ethylhexyl carbonate (TBEC), and tert-butyl peroxy-3,5,5-trimethylhexanoate (TBPMH).

According to certain preferred embodiments of the present invention, the non-peroxide crosslinking agent is selected from one or more of the group consisting of trimethylolpropane triacrylate (TMPTA) and triallyl base isocyanurate (TAIC).

According to certain preferred embodiments of the present invention, the coupling agent is selected from one or more of silane coupling agents and phthalate coupling agents.

According to certain preferred embodiments of the present invention, the ultraviolet absorber is selected from one or more of the group consisting of: salicylate type ultraviolet absorber, benzophenone type ultraviolet absorber, benzotriazole Azole UV absorbers and triazine UV absorbers.

According to certain preferred embodiments of the present invention, the salicylate ultraviolet absorber is selected from one or more of methyl salicylate, ethyl salicylate and octyl salicylate.

According to some preferred embodiments of the present invention, the benzophenone ultraviolet absorber is selected from the group consisting of 2-hydroxy-4-methoxybenzophenone and 2-hydroxy-4-n-octyloxybenzophenone one or more.

According to some preferred embodiments of the present invention, the benzotriazole-based UV absorber is selected from 2-(2'-hydroxy-3',5'-di-tert-phenyl)-5-benzotriazole chloride azole and one or more of 2-(2'-hydroxy-5'-methylphenyl)benzotriazole.

According to certain preferred embodiments of the present invention, the UV stabilizer is a hindered amine UV stabilizer.

According to certain preferred embodiments of the present invention, the hindered amine UV stabilizer is selected from one or more of the group consisting of: polysuccinic acid (4-hydroxy-2,2,6,6 -Tetramethyl-1-piperidineethanol) ester, poly[(6-morpholino-5-triazine-2,4-diyl)(2,2,6,6-tetramethylpiperidinyl) Iminohexamethylene[(2,2,6,6-tetramethylpiperidinyl)-imino]], 4-benzoyloxy-2,2,6,6-tetramethyl Piperidine and tris(1,2,2,6,6-pentamethylpiperidinyl)phosphite.

According to another aspect of the present invention, there is provided a light guide film, the light guide film sequentially includes a light guide layer, a base layer and a reactive adhesive layer, wherein the reactive adhesive layer comprises the above-mentioned adhesive composition.

According to certain preferred embodiments of the present invention, the base layer is physically surface treated.

According to certain preferred embodiments of the present invention, the physical surface treatment is corona treatment or plasma treatment.

According to certain preferred embodiments of the present invention, the thickness of the reactive adhesive layer is in the range of 10-100 μm.

According to certain preferred embodiments of the present invention, the light-guiding layer includes an ordered array of a plurality of microstructures extending from the base layer.

According to certain preferred embodiments of the present invention, the light guide layer includes a plurality of microstructures that are disordered and protrude from the base layer.

According to certain preferred embodiments of the present invention, the plurality of microstructures comprise an array of juxtaposed triangular prisms, and the orientation direction of the array of juxtaposed triangular prisms is non-linearly oriented.

According to certain preferred embodiments of the present invention, the plurality of microstructures comprise an array of parallel triangular prisms, wherein one quadrilateral face of each triangular prism is in the same plane.

According to certain preferred embodiments of the present invention, the light directing film further includes a primer layer between the reactive adhesive layer and the base layer.

According to certain preferred embodiments of the present invention, the primer layer is a polyester primer layer or a polyacrylate primer layer.

According to one aspect of the present invention, it is provided that the light guide film further includes a light reflective layer covering the plurality of microstructures and conforming to the plurality of microstructures.

According to yet another aspect of the present invention, a solar cell assembly is provided, the solar cell assembly includes a light-transmitting element, a front encapsulation layer, a plurality of spaced solar cells, and a rear encapsulation layer sequentially arranged along the thickness direction thereof. and a back sheet, wherein the solar cell assembly further comprises the light guide film as described above, the light guide film is disposed between the rear encapsulation layer and the back sheet and is adhered by the reactive adhesive layer attached to the surface of the backplane.

According to certain preferred embodiments of the present invention, the side of the back sheet facing the solar cell comprises a non-hot melt adhesive material.

According to certain preferred embodiments of the present invention, the side of the back sheet facing the solar cell comprises a fluorine-containing non-hot-melt adhesive material.

Compared with the prior art in this field, the advantages of the present invention are:

1. The adhesive layer has high adhesiveness;

2. Avoid bulging between the light guide film and the package backplane during high temperature and humidity aging; and

3. The relative position drift of the light guide film during the high temperature lamination preparation process is greatly reduced.

Description of drawings

Figure 1 shows a cross-sectional view of a light directing film according to one embodiment of the present invention; and

2 shows a perspective view of an array of parallel triangular prisms contained in a light directing film according to an embodiment of the present invention; and

3 shows a cross-sectional view of a solar cell module according to an embodiment of the present invention.

Detailed ways

The present invention will be described in further detail below with reference to specific embodiments. It will be understood that other embodiments are contemplated, which may be practiced without departing from the scope or spirit of the invention. Accordingly, the following detailed description is not limiting.

Unless otherwise indicated, all numbers used in this specification and claims for the dimensions, quantities, and physicochemical properties of features should be understood to be modified in all instances by the term "about." Accordingly, unless indicated to the contrary, the numerical parameters set forth in the foregoing specification and attached claims are approximations that can be modified by those skilled in the art to obtain the desired properties sought to be obtained by the teachings disclosed herein. approximation. The use of numerical ranges by endpoints includes all numbers within that range and any range within that range, eg, 1 to 5 includes 1, 1.1, 1.3, 1.5, 2, 2.75, 3, 3.80, 4, and 5, etc. .

During assembly of the solar cell module, the light directing film is usually adhered by an adhesive layer on the backlit side surface of the solar cell or the surface of the encapsulating backsheet that is inside the solar cell module. However, in an environment of high temperature and high humidity, the adhesive layer will gradually age over time, and a bulge will be formed between the light guide film and the package backplane, resulting in damage to the light guide film or from the adhering surface. fall off.

According to one aspect of the present invention, there is provided an adhesive composition comprising a resin binder, a peroxide cross-linking agent, a non-peroxide cross-linking agent, a coupling agent, a UV absorbing agent and UV stabilizer, wherein the adhesive composition undergoes an exothermic reaction in the lamination process of the solar module production process (generally, the lamination temperature is above 140°C) and has 2-40 J/g.

Without wishing to be bound by theory, it is believed that the cause of the visually discernible bulge between the light directing film and the backsheet during moist heat aging of the adhesive layer is that under aging conditions (e.g., 85°C/85% humidity) ), the resin in the adhesive glue will soften and melt, resulting in a decrease in the adhesive force with the light guide film layer and the backplane. At the same time, water vapor in the environment and other small molecular gases in the assembly can accumulate in the weak adhesion and form a bulge. The bulge may be formed anywhere inside or near the light guide film, such as between the adhesive layer and the backing plate, or between the base layer and the adhesive layer, or between the light guide layer and the base layer. According to the technical idea of the invention, by specifically selecting specific components and their contents, the adhesive composition can undergo an exothermic reaction in the lamination process of the solar module production process, thereby further crosslinking the adhesive glue to form a network , enhance the strength of the body, maintain the adhesion and do not form weak points.

According to the disclosure of the present application, unless otherwise specified, "exothermic heat" refers to the heat (unit: J/g) released per gram of the adhesive composition at a temperature above 95°C. The heat release of the adhesive composition is 2-40 J/g. When the heat release is less than 2 J/g, the heat released during the aging process is too low to cause further cross-linking and networking of the adhesive glue. On the other hand, when the heat release is greater than 40J/g, due to the excessive heat release of the adhesive layer system and the excessive crosslinking of the system, after the components are laminated, the light guide film will be wrinkled and bulged after high temperature and humidity aging.

Preferably, based on the total weight of the adhesive composition, the adhesive composition comprises:

90-98% by weight of the resin binder;

0.4-1.4% by weight of the peroxide crosslinking agent;

0.4-1.6% by weight of the non-peroxide crosslinking agent;

0.5-1.5% by weight of the coupling agent;

0.5-4% by weight of the UV absorber; and

0.2-2% by weight of the UV stabilizer.

系列EVA树脂(例如，

150、

250、

260、

PV 1300Z和

3135SB)；由Hanwa公司生产的EVA树脂(例如，PV280、PV282、E182和E283F)；由巴斯夫公司生产的EVA树脂V5110J和6110M；由陶氏公司生产的聚烯烃(POE)树脂8842和7256；以及由三井(Mistuchem)公司生产的聚烯烃(POE)树脂Tafmer DF605、TafmerDF640、Tafmer DF740、Tafmer DF7350、Tafmer DF8200、Tafmer DF840和Tafmer DF7350。According to the technical solution of the present application, the adhesive composition comprises a high content (90-98% by weight) of a resin binder as a basic material. The resin binder is usually used in the form of pellets. The specific type of the resin binder is not particularly limited, as long as the resin binder can continue to be networked and cross-linked under an exothermic heat of 2-40 J/g. Preferably, the resin binder is selected from one or more of the group consisting of: ethylene-vinyl acetate (EVA) copolymer, polyolefin resin (PO), polypropylene oxide (PP), Polyvinyl butyral (PVB), tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride (THV) copolymer, ethylene-tetrafluoroethylene (ETFE) copolymer, polyvinylidene fluoride (PVDF), polyurethane ( PU), polymethyl methacrylate (PMMA) and polyimide (PI), etc. The adhesive composition comprises 90-98% by weight of the resin binder, based on the total weight of the adhesive composition. Commercially available products of resin binders that can be used in the present invention include:

series of EVA resins (eg,

150,

250,

260,

PV 1300Z and

and Polyolefin (POE) resins Tafmer DF605, Tafmer DF640, Tafmer DF740, Tafmer DF7350, Tafmer DF8200, Tafmer DF840 and Tafmer DF7350 produced by Mistuchem.

Unless otherwise specified, the term "melt flow index" in accordance with the present invention has the ordinary definition of the term in the art. That is, the term "melt flow index" according to the present invention refers to the amount of polymer pellets that melt into a polymer fluid at a temperature of 190° C. and a pressure of 2.16 kg and flow through a circular tube having a diameter of 2.095 mm. Grams (unit: g). The melt flow index (MFI) of the polymer raw material is a very important processing parameter to characterize the properties of the polymer. The higher the melt flow index (MFI), the better the flowability of the polymer and the easier the processing. However, during the research process of the present invention, it was found that for the application of the present invention, the polymer with high melt flow index is prone to drift after high temperature lamination. The adhesive composition according to the present invention is used for adhering a light directing film on a backlit side surface of a solar cell or on a surface of an encapsulation backsheet that is inside a solar cell module. The solar cell assembly includes a light-transmitting element, a front encapsulation layer, a plurality of mutually spaced solar cells, a rear encapsulation layer and an encapsulation back sheet arranged in sequence along its thickness direction, the plurality of spaced apart solar cells forming an array comprising a plurality of mutually parallel solar cell strings in the same plane perpendicular to the thickness direction, each of the solar cell strings being composed of a plurality of solar cells connected in series, every two String gaps are formed between adjacent solar cell strings, and sheet gaps are formed between adjacent solar cells in each of the solar cell strings. The function of the light guide film according to the present invention is to re-reflect the light incident through the string gap and/or the sheet gap (2-4mm) to the solar cell sheet so as to improve the power generation efficiency of the module. However, the drift of the film causes light loss and whitening of the assembly, resulting in poor appearance. Preferably, the resin binder has a melt flow index (MFI) in the range of 10-30. According to the present invention, when the melt flow index (MFI) of the resin binder is lower than 10, it is not easy to uniformly extrude the obtained adhesive composition to form an adhesive film layer. According to the present invention, when the melt flow index (MFI) of the resin base material is in the range of 10-30, the relative position drift of the light guide film during the high temperature lamination preparation process can be effectively suppressed, so that the drift degree is less than 0.5mm. The "drift degree" according to the present invention refers to the displacement value of the light guide film relative to the initial position after the light guide film is adhered to the substrate through the adhesive composition and subjected to high temperature lamination processing (unit: mm).

In order to achieve the technical effect of the present invention, preferably, the resin binder is an ethylene-vinyl acetate (EVA) copolymer. Ethylene-vinyl acetate (EVA) copolymer is a polymer formed by copolymerizing ethylene monomer and vinyl acetate. Preferably, in the ethylene-vinyl acetate (EVA) copolymer, based on the total weight of the ethylene-vinyl acetate (EVA) copolymer, the content of repeating units derived from vinyl acetate (in the present application , also referred to as "VA content") in the Examples section of 24-30% by weight. More preferably, in the ethylene-vinyl acetate (EVA) copolymer, based on the total weight of the ethylene-vinyl acetate copolymer (EVA), the content of repeating units derived from vinyl acetate (herein In the Examples section of the application, also referred to as "VA content") was 26-28% by weight. When the VA content is less than 24% by weight, the adhesiveness of the obtained adhesive composition to the substrate becomes poor, and the transparency of the obtained material after lamination is also poor, which is very important for the application of double-sided double-glass modules. Adverse. On the other hand, when the VA content is higher than 30% by weight, the adhesive film formed from the adhesive composition is too soft, thereby causing the adhesive film to wrinkle.

By adjusting the specific content of the repeating unit derived from vinyl acetate to be in the range of 24-30 wt %, it may be advantageous to improve the adhesive strength and damp heat aging resistance of the adhesive composition.

According to the technical solution of the present invention, the adhesive composition includes a peroxide cross-linking agent to promote its cross-linking reaction. In the art, peroxide crosslinkers are very effective crosslinkers, which generate alkyl radicals by pyrolysis, which generate polymer radicals through chain transfer, and the polymer radicals are added to each other. cross-linked. There is no limitation on the specific kind of peroxide cross-linking agent that can be used in the present invention, preferably, the peroxide cross-linking agent is selected from one or more of the group consisting of: benzene peroxide Formyl (BPO), dicumyl peroxide (DCP), tert-amyl peroxyacetate (TAPA), tert-butyl 2-ethylhexyl peroxycarbonate (TBEC) and peroxy-3,5,5- tert-Butyl trimethylhexanoate (TBPMH) and the like. Adding a peroxide cross-linking agent to the adhesive composition can effectively increase the cross-linking degree of the product, thereby improving the bulk strength and viscosity of the polymer. However, under the lamination process of solar cell modules, if the peroxide is added too much and the reaction is not completed in time, it will slowly decompose during use to generate gas, resulting in bulging in the adhesive layer. The adhesive composition comprises 0.4-1.4 wt% of the peroxide crosslinking agent, based on the total weight of the adhesive composition. Specific examples of peroxide cross-linking agents that can be used in the present invention include: tert-butyl 2-ethylhexyl carbonate (TBEC) peroxy and 3,5,5-trioxy-3,5,5-trioxide produced by Arkema Corporation tert-Butyl methylhexanoate (TBPMH).

According to the technical solution of the present invention, a lower concentration of peroxide crosslinking agent is used. In order to ensure that a high degree of cross-linking can also be achieved at a low peroxide cross-linking agent concentration to obtain the required bonding strength and moisture-heat aging resistance, the present invention adds a non-peroxide cross-linking agent as an essential component. Non-peroxide crosslinking agents are compounds with multiple double bond functional groups, which participate in crosslinking in the reaction. Due to the fast reaction speed, low molecular weight products generated by the coupling of peroxide alkyl radicals and polymer radicals are reduced. There is no limitation on the specific kind of non-peroxide cross-linking agent that can be used in the present invention, preferably, the non-peroxide cross-linking agent is selected from one or more of the group consisting of: three Methylol propane triacrylate (TMPTA) and triallyl isocyanurate (TAIC). When the non-peroxide content is too high, the shrinkage rate of the adhesive film (ie, the adhesive layer) becomes high, and some regional wrinkles are generated during the application process, which is not conducive to the appearance of the component and the wrinkles are prone to bulge. Preferably, the adhesive composition comprises 0.4-1.6 wt% of a non-peroxide crosslinking agent, based on the total weight of the adhesive composition. The non-peroxide crosslinking agent can be a single component or a combination of two or more components. Specific examples of non-peroxide crosslinking agents that can be used in the present invention include trimethylolpropane triacrylate (TMPTA) SR 351 and triallyl isocyanurate (TAIC) produced by Sartomer. ).

According to the technical solution of the present invention, the adhesive composition includes a coupling agent. Preferably, the coupling agent is selected from one or more of silane coupling agents and phthalate coupling agents. Preferably, the adhesive composition comprises 0.5-1.5 wt % of the coupling agent, based on the total weight of the adhesive composition. Specific products of coupling agents that can be used in the present invention include γ-(methacryloyloxy)propyltrimethoxysilane produced by Momentive under the product name A174 and by Momentive under the product name of A174. 3-Aminopropyltriethoxysilane of A1100.

81的2-羟基-4-正辛氧基二苯甲酮；和由巴斯夫公司生产的产品名为UVP 327的2-(2’-羟基-3’,5’-二-叔苯基)-5-氯化苯并三唑。According to the technical solution of the present invention, the adhesive composition contains an ultraviolet absorber. Preferably, the ultraviolet absorber is selected from one or more of the group consisting of: a salicylate type ultraviolet absorber, a benzophenone type ultraviolet absorber, a benzotriazole type ultraviolet absorber, and a triazole type ultraviolet absorber. Azine UV absorbers, etc. The salicylate ultraviolet absorber is selected from one or more of methyl salicylate, ethyl salicylate and octyl salicylate. The benzophenone ultraviolet absorber is selected from one or more of 2-hydroxy-4-methoxybenzophenone and 2-hydroxy-4-n-octyloxybenzophenone. The benzotriazole ultraviolet absorber is selected from 2-(2'-hydroxy-3',5'-di-tert-phenyl)-5-benzotriazole chloride and 2-(2'-hydroxy- One or more of 5'-methylphenyl)benzotriazole. The adhesive composition comprises 0.5-4 wt% of the ultraviolet absorber, based on the total weight of the adhesive composition. Specific products of ultraviolet absorbers that can be used in the present invention include: products produced by BASF are named

2-hydroxy-4-n-octyloxybenzophenone of 81; and 2-(2'-hydroxy-3',5'-di-tert-phenyl)- 5-Chlorobenzotriazole.

According to the technical solution of the present invention, the adhesive composition includes a UV stabilizer. Preferably, the UV stabilizer is a hindered amine UV stabilizer. Preferably, the hindered amine UV stabilizer is one or more selected from the group consisting of: polysuccinic acid (4-hydroxy-2,2,6,6-tetramethyl-1- piperidineethanol) ester, poly[(6-morpholinyl-5-triazine-2,4-diyl)(2,2,6,6-tetramethylpiperidinyl)iminohexamethylene [(2,2,6,6-Tetramethylpiperidinyl)-imino]], 4-benzoyloxy-2,2,6,6-tetramethylpiperidine and tris(1, 2,2,6,6-Pentamethylpiperidinyl)phosphite. The adhesive composition comprises 0.2-2 wt% of the UV stabilizer, based on the total weight of the adhesive composition. Specific products of the UV stabilizer that can be used in the present invention include: polysuccinic acid (4-hydroxy-2,2,6,6-tetramethyl-1-piperidine) named TINUVIN 622 produced by BASF pyridineethanol) ester; poly[(6-morpholino-5-triazine-2,4-diyl)(2,2,6,6-tetramethyl) produced by Cytec under the product name CYASORB UV3346 piperidinyl)iminohexamethylene[(2,2,6,6-tetramethylpiperidinyl)-imino]]; the product name 744 produced by Guangdong Light Stabilizer Production Co., Ltd. - Benzoyloxy-2,2,6,6-tetramethylpiperidine; tris(1,2,2,6,6-pentamethylpiperidine) produced by Hubei Jusheng Technology Co., Ltd. named GW540 base) phosphite; BASF's TINUVIN 770, TINUVIN783, TINUVIN P, TINUVIN 788; and Cytec's CYASORB UV1164, CYASORB UV 2126, CYASORBUV 3853, CYASORB THT, etc.

There is no particular limitation on the method of preparing the adhesive composition according to the present invention. Typically, the adhesive composition can be prepared by simple mixing and stirring. Specifically, the resin binder particles are mixed with peroxide cross-linking agent, non-peroxide cross-linking agent, coupling agent, ultraviolet absorber, ultraviolet stabilizer and optional other components in a certain proportion at room temperature (10°C). -30°C) stirring and mixing to obtain an adhesive composition.

According to another aspect of the present invention, there is provided a light guide film including a light guide layer, a base layer and a reactive adhesive layer in sequence, wherein the reactive adhesive layer comprises the above-mentioned adhesive composition. In order to enhance the adhesion between the adhesive layer and the substrate layer to prevent delamination between the adhesive layer and the substrate layer, it is preferable that the substrate layer has undergone a physical surface treatment. The physical surface treatment is corona treatment or plasma treatment. In order to ensure sufficient adhesion to adhere the light guide film on the backlit side surface of the solar cell or on the surface of the encapsulation backsheet that is inside the solar cell module, the reactive adhesive layer has a thickness of 10- 100 μm, preferably in the range of 20-50 μm. Optionally, the light directing layer includes an ordered array of a plurality of microstructures extending from the base layer. Optionally, the light-guiding layer includes a disordered arrangement of a plurality of microstructures extending from the base layer. Optionally, the plurality of microstructures comprise an array of side-by-side triangular prisms, and the orientation direction of the array of side-by-side triangular prisms is non-linearly oriented. According to certain preferred embodiments of the present invention, the term "juxtaposed triangular prism array" refers to an array comprising a plurality of triangular prisms arranged side by side with each other. According to certain preferred embodiments of the present invention, each triangular prism in the side-by-side triangular prism array is a triangular prism with a top angle of 120 degrees toward the solar cell and two base angles of 30 degrees each. Optionally, the plurality of microstructures comprise an array of parallel triangular prisms, wherein one quadrilateral face of each triangular prism is in the same plane. Optionally, the peaks facing the solar cells of at least one triangular prism in the array of side-by-side triangular prisms may be replaced by rounded peaks. Preferably, the circular peaks of at least one triangular prism in the juxtaposed triangular prism array have a radius of curvature of 0.2 microns to 5 microns. Preferably, the light directing film further includes a primer layer between the reactive adhesive layer and the base layer. The role of the primer layer is to enhance the adhesion between the adhesive layer and the substrate layer to prevent delamination between the adhesive layer and the substrate layer. In addition to using the primer layer to achieve this technical effect, the corona treatment of the substrate layer can also be used to enhance the adhesion between the adhesive layer and the substrate layer to prevent the adhesion between the substrate layer and the adhesive layer. Delamination occurs. Preferably, the primer is a polyester primer or a polyacrylate primer. The light directing film also includes a light reflective layer covering and conforming to the plurality of microstructures.

Specifically, FIG. 1 shows a cross-sectional view of a light guide film 1 according to an embodiment of the present invention. The light guide film 1 sequentially includes a light guide layer 2, a base layer 3 and a reactive adhesive layer 4, wherein the reactive adhesive layer 4 comprises the adhesive composition as described above. The thickness of the reactive adhesive layer 4 is in the range of 10-100 μm, preferably 20-50 μm. When the thickness of the reactive adhesive layer 4 is greater than 100 μm, the relative position drift of the light guide film is likely to occur during the high temperature lamination process. The light guide layer 2 includes a plurality of microstructures 5 which are arranged in an orderly manner and protrude from the base layer 3 . In one embodiment, the ordered plurality of microstructures 5 extending from the base layer comprises an array of parallel triangular prisms, wherein one quadrangular face of each triangular prism is in the same plane. FIG. 2 shows a perspective view of the parallel triangular prism array 6 contained in the light guide film 1 according to an embodiment of the present invention. As shown in FIG. 2 , the light guide layer 4 includes an array of parallel triangular prisms 6 , wherein one quadrangular face of each triangular prism 7 is in the same plane 8 . D is the orientation direction of the parallel triangular prism array 6 . As shown in FIG. 1 , the light directing film 1 also includes a primer layer 9 between the reactive adhesive layer 4 and the base layer 3 . The primer layer 9 includes a polyester primer layer or a polyacrylate primer layer. As shown in FIG. 1 , the light guide film 1 further includes a light reflective layer 10 covering the plurality of microstructures 5 and conforming to the plurality of microstructures 5 .

According to yet another aspect of the present invention, a solar cell assembly is provided, the solar cell assembly includes a light-transmitting element, a front encapsulation layer, a plurality of spaced solar cells, and a rear encapsulation layer sequentially arranged along the thickness direction thereof. and a back sheet, wherein the solar cell assembly further comprises the light guide film as described above, the light guide film is disposed between the rear encapsulation layer and the back sheet and is adhered by the reactive adhesive layer attached to the surface of the backplane.

Specifically, FIG. 3 shows a cross-sectional view of a solar cell module 11 according to an embodiment of the present invention. The solar cell assembly 11 includes a light-transmitting element 12, a front encapsulation layer 13, a plurality of solar cells 14 spaced apart from each other, a rear encapsulation layer 15 and a back sheet 16, which are sequentially arranged along its thickness direction T, wherein the solar cells The assembly 11 also includes the light-guiding film 1 as described above, which is disposed between the rear encapsulation layer 15 and the backplate 16 and is adhered to the entire assembly by the reactive adhesive layer 4 . on the surface 17 of the back plate 16 .

In this study, the inventors of the present invention found that when the inner layer (ie, the side facing the solar cell) of the backsheet contains a non-hot-melt adhesive material or a fluorine-containing material (for example, commercially available from Saiwu Company under the brand name of Kpf backplane, or the backplane of the brand TFB produced by Jolywood), it is especially prone to bulge between the backplane and the light guide film under aging conditions. According to the technical solution of the present invention, after the light guide film and the fluorine-containing backplane are bonded with the adhesive composition of the present invention and subjected to aging conditions, there will be no bulging between the backplane and the light guide film.

The present invention will be described in more detail below with reference to the embodiments. It should be pointed out that these descriptions and examples are for the purpose of facilitating the understanding of the present invention, rather than limiting the present invention. The scope of protection of the present invention is determined by the appended claims.

Example

In the present invention, unless otherwise indicated, the reagents used are all commercially available products, which are used directly without further purification. Furthermore, the reference to "%" is "% by weight", and the reference to "parts" is "parts by weight".

Performance Testing

Test pieces were prepared from the various adhesive compositions prepared in the Examples and Comparative Examples by the subbing layer and test piece preparation methods listed below.

Preparation of reactive adhesive films

The adhesive compositions prepared in Examples and Comparative Examples were extruded into polyethylene terephthalate films with a thickness of 35 μm at 80-100° C. using a single-screw extruder produced by Kingwell Corporation , to form a reactive adhesive film with a thickness of 25 μm.

Preparation of test components

The light guide film with the reactive adhesive film was cut into narrow strips with a width of 5 mm and a length of 25 cm. The strip was thermally attached to the inward facing side of a Kpf backing plate manufactured by Saiwu Company at a speed of 5-10 cm/sec at 100°C. The light-transmitting element (glass with the brand name XYG produced by Xinyi Peel off Co., Ltd.), 2 layers of EVA packaging film (EVA packaging film with the brand name 9100T and 9210B produced by 3M Innovation Co., Ltd.) The backplane of the light guide film of the adhesive film (the surface of the light guide film faces the EVA encapsulation film) is laminated in sequence to obtain a laminated body. The laminate was put into a laminator of model KRA-Y1322 produced by Qinhuangdao Kezhirui Technology Co., Ltd., vacuumed for 5 minutes at a lamination temperature of 145° C., pressurized for 30 seconds and heated for 13 minutes to Get test components.

The above-obtained reactive adhesive films and test assemblies were tested with respect to damp heat aging resistance, heat release, adhesion, and drift according to the specific methods listed below.

Moisture and heat aging resistance

The test assembly obtained as above was placed in a C1000 environmental test box manufactured by Envirotronics, and was taken out after being kept at 85° C./85% humidity for 1000 hours. Observe with the naked eye from the back panel surface and the glass surface of the test assembly to see if there is bulging, foaming and delamination. If the above phenomenon exists, it is considered that the damp-heat aging resistance is poor; if the above phenomenon does not exist, the damp-heat aging resistance is considered to meet the requirements (pass).

heat release

The reactions prepared in the Examples and Comparative Examples were directly measured in the temperature range of 20-220°C (with a heating rate of 10°C/min and under nitrogen atmosphere) using a differential scanning calorimeter, model Q2000, produced by TA Company. Heat capacity and heat flow of the adhesive film. The exothermic heat (in J/g) and the exothermic temperature (°C) were calculated from the obtained DSC curve.

Adhesion

The laminated test assembly was tested according to the ASTM D1876 standard using an electronic universal testing machine model 5969 produced by Instron to test the adhesive strength (unit: N/cm) between the polymer glue in the test assembly and the backplane. ). According to the test performance, the higher the bond strength, the better, and when the bond strength is greater than 40N/cm, the performance is excellent.

Drift

The adhesive compositions prepared in Examples and Comparative Examples were extruded onto a light guide film (T81 produced by 3M Innovation Co., Ltd.), respectively, to obtain a light guide having a reactive adhesive layer with a thickness of 25 μm membrane. The light guide film was cut into 5 mm wide and 25 cm long film blocks. The film block was thermally attached to the textured surface of a solar glass with a model of XYG produced by Xinyi Glass, so as to obtain a solar glass with a light-guiding film. Then, draw the outline of the light guide film with a marker close to the periphery of the light guide film. Subsequently, the light-transmitting element (glass with the brand name of XYG produced by Xinyi Glass Company), 2 layers of EVA encapsulation films (the EVA encapsulation film with the brand names of 9100T and 9210B produced by 3M Innovation Co., Ltd.) and the above-prepared glass with light guide The solar glass of the film is sequentially laminated to obtain a laminate. The laminate was put into a laminator of model KRA-Y1322 produced by Qinhuangdao Kezhirui Technology Co., Ltd., vacuumed for 5 minutes at a lamination temperature of 145° C., pressurized for 30 seconds and heated for 13 minutes to Get test components.

Then, the relative distance between the position of the light guide film on the test assembly after lamination and the outline of the original marker was measured and counted as the degree of drift (unit: mm). When the drift is less than 0.5mm, it meets the requirements.

The raw materials employed in the Examples and Comparative Examples according to the present invention are shown in Table 1 below. Unless otherwise indicated, the starting materials were used without additional purification.

Table 1 List of raw materials used in the examples and comparative examples

Example 1

Mix the resin pellets EVA1, peroxide crosslinking agent 1, non-peroxide crosslinking agent 1, coupling agent 1, UV absorber 1 and UV stabilizer 2, and uniformly stir at room temperature to obtain a binder combination item 1. According to the adhesive composition 1, as shown in Table 1 below, based on the total weight of the adhesive composition 1, the resin pellets EVA1 accounted for 95.2 wt%, and the peroxide crosslinking agent 1 accounted for 1.4 wt% % by weight, non-peroxide crosslinking agent 1 is 0.4% by weight, coupling agent 1 is 1% by weight, UV absorber 1 is 1% by weight, and UV stabilizer 2 is 1% by weight.

The reactive adhesive film 1 was prepared from the adhesive composition 1 according to the preparation method of the polymer adhesive layer as described above. The test assembly 1 is prepared by using the reactive adhesive film 1 according to the test assembly preparation method as described above. The Adhesive Composition 1, Reactive Film 1 and Test Component 1 were tested with respect to the Damp Heat Aging Resistance, The heat release, adhesion and drift were tested and the test results are shown in Table 2 below.

Examples 2-9 and Comparative Examples 1-6

Examples 2-9 and Comparative Examples 1-6 were carried out according to the same method as Example 1, except that the kinds, presence or absence, and contents of the respective components were changed as shown in Table 2 to obtain respective adhesives combination.

Each reactive adhesive film was prepared from the adhesive compositions obtained in Examples 2-9 and Comparative Examples 1-6 according to the preparation method of the polymer adhesive layer as described above. Each test assembly is prepared using the respective reactive adhesive films according to the test assembly preparation method as described above. The respective adhesive compositions, respective reactive adhesive films, and respective test assemblies were tested for their respective adhesive compositions, respective reactive adhesive films, and respective test assemblies with respect to moisture and heat aging resistance, Heat release, adhesion and drift were tested and the test results are shown in Tables 2 and 3 below.

The component allocation ratio of table 2 embodiment 1-9 and performance test result

Table 3 Group allocation ratio and performance test results of comparative examples 1-6

As can be seen from the above Tables 2 and 3, according to the embodiments of Examples 1-9, when the adhesive composition undergoes an exothermic reaction at a temperature above 95°C and has an exothermic heat of 2-40 J/g, when the adhesive composition is removed from the test assembly When the back surface and the glass surface were observed with the naked eye, no bulging, foaming and delamination were found, and good humidity and heat aging resistance could be achieved.

Example 1 was run under similar conditions as Comparative Example 1, except that no non-peroxide crosslinking agent was present in the adhesive composition of Comparative Example 1. As can be seen from Tables 2 and 3 above, in the absence of a non-peroxide crosslinking agent, there may be low molecular weight products resulting from the coupling of peroxide alkyl radicals and polymer radicals in the adhesive composition system, thereby As a result, the bond strength of the polymer adhesive film was significantly reduced, and bulging, foaming and delamination of the light guide film were found.

According to the embodiment of Comparative Example 2, no peroxide crosslinking agent and non-peroxide crosslinking agent are present in the adhesive composition system, so that no exothermic reaction occurs and no heat is released at temperatures above 95°C, As a result, the adhesive glue does not undergo further crosslinking reactions, bulges occur and the bond strength decreases.

According to the embodiment of Comparative Example 3, the amount of non-peroxide crosslinking agent present in the adhesive composition system was too low (only 0.2 wt%), resulting in an exotherm of only 1.8 J/g. The adhesive glue did not sufficiently undergo further crosslinking reactions, a little bulge occurred, and the bond strength decreased.

According to the embodiment of Comparative Example 4, the amount of non-peroxide crosslinking agent present in the adhesive composition system was too high (1.8 wt%), resulting in an excessive heat release (46 J/g). Excessive heat release increases the shrinkage rate of the adhesive film, resulting in wrinkles in some areas during the application process, which is not conducive to the appearance of the component and bulges in the wrinkled part.

The adhesive composition system of Comparative Example 5 used the resin binder EVA2. As shown in Table 1, the melt flow index (MFI) of the resin base EVA2 was too large (40). The results show that although the bonding strength is high, the light guide film on the test assembly has a very obvious drift (drift degree is greater than 1mm) and has poor resistance to moisture and heat aging, resulting in bulging.

The adhesive composition system of Comparative Example 6 used the resin binder EVA3. As shown in Table 1, the VA content of the resin base EVA3 was too small (only 20% by weight), the bond strength decreased and bulging, foaming and delamination were found.

It will be apparent to those skilled in the art that various changes and modifications can be made to the present disclosure without departing from the spirit and scope of the present disclosure. Thus, provided that these modifications and variations of the present disclosure fall within the scope of the claims of the present invention and their equivalents, the present disclosure is also intended to include such modifications and variations.

Claims (30)

1. An adhesive composition comprising a resin binder, a peroxide crosslinking agent, a non-peroxide crosslinking agent, a coupling agent, an ultraviolet absorber and an ultraviolet stabilizer, wherein The adhesive composition undergoes an exothermic reaction at temperatures above 95°C and has an exothermic heat of 2-40 J/g. 2. The adhesive composition of claim 1 comprising, based on the total weight of the adhesive composition: 90-98% by weight of the resin binder; 0.4-1.4% by weight of the peroxide crosslinking agent; 0.4-1.6% by weight of the non-peroxide crosslinking agent; 0.5-1.5% by weight of the coupling agent; 0.5-4% by weight of the UV absorber; and 0.2-2% by weight of the UV stabilizer. 3. The adhesive composition of claim 1 or 2, wherein the resin binder is selected from one or more of the group consisting of: ethylene-vinyl acetate (EVA) copolymer, Polyolefin resin (PO), polypropylene oxide (PP), polyvinyl butyral (PVB), tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride (THV) copolymer, ethylene-tetrafluoroethylene (ETFE) ) copolymer, polyvinylidene fluoride (PVDF), polyurethane (PU), polymethyl methacrylate (PMMA) and polyimide (PI). 4. The adhesive composition of claim 1 or 2, wherein the resin binder has a melt flow index (MFI) in the range of 10-30. 5. The adhesive composition of claim 3, wherein the resin binder is an ethylene vinyl acetate (EVA) copolymer. 6. The adhesive composition of claim 5, wherein in the ethylene-vinyl acetate (EVA) copolymer, based on the total weight of the ethylene-vinyl acetate (EVA) copolymer, derivatized The content of repeating units from vinyl acetate is 24-30% by weight. 7. The adhesive composition of claim 5, wherein in the ethylene-vinyl acetate (EVA) copolymer, based on the total weight of the ethylene-vinyl acetate (EVA) copolymer, derivatized The content of repeating units from vinyl acetate is 26-28% by weight. 8. The adhesive composition of claim 1 or 2, wherein the peroxide crosslinking agent is selected from one or more of the group consisting of: Benzoyl Peroxide (BPO) , Dicumyl peroxide (DCP), tert-amyl peroxyacetate (TAPA), tert-butyl peroxy 2-ethylhexyl carbonate (TBEC) and peroxy-3,5,5-trimethylhexanoic acid tert-Butyl ester (TBPMH). 9. The adhesive composition of claim 1 or 2, wherein the non-peroxide crosslinking agent is selected from one or more of the group consisting of: trimethylolpropane triacrylic acid ester (TMPTA) and triallyl isocyanurate (TAIC). 10. The adhesive composition according to claim 1 or 2, wherein the coupling agent is selected from one or more of silane coupling agents and phthalate-based coupling agents. 11. The adhesive composition according to claim 1 or 2, wherein the ultraviolet absorber is selected from one or more of the group consisting of: salicylate type ultraviolet absorber, benzophenone UV absorbers, benzotriazole UV absorbers and triazine UV absorbers. 12. The adhesive composition according to claim 11, wherein the salicylate ultraviolet absorber is selected from one or more of methyl salicylate, ethyl salicylate and octyl salicylate. kind. 13. The adhesive composition according to claim 11, wherein the benzophenone-based ultraviolet absorber is selected from the group consisting of 2-hydroxy-4-methoxybenzophenone and 2-hydroxy-4-n-octyloxy One or more of benzophenones. 14. The adhesive composition according to claim 11, wherein the benzotriazole-based ultraviolet absorber is selected from 2-(2'-hydroxy-3',5'-di-tert-phenyl)-5 - one or more of benzotriazole chloride and 2-(2'-hydroxy-5'-methylphenyl)benzotriazole. 15. The adhesive composition according to claim 1 or 2, wherein the UV stabilizer is a hindered amine UV stabilizer. 16. The adhesive composition of claim 15, wherein the hindered amine UV stabilizer is selected from one or more of the group consisting of: polysuccinic acid (4-hydroxy-2 ,2,6,6-tetramethyl-1-piperidineethanol) ester, poly[(6-morpholino-5-triazine-2,4-diyl)(2,2,6,6-tetra Methylpiperidinyl)iminohexamethylene[(2,2,6,6-tetramethylpiperidinyl)-imino]], 4-benzoyloxy-2,2,6 , 6-tetramethylpiperidine and tris(1,2,2,6,6-pentamethylpiperidinyl) phosphite. 17. A light guide film comprising, in sequence, a light guide layer, a base layer and a reactive adhesive layer, wherein the reactive adhesive layer comprises the the described adhesive composition. 18. The light directing film of claim 17, wherein the base layer is physically surface treated. 19. The light directing film of claim 18, wherein the physical surface treatment is corona treatment or plasma treatment. 20. The light directing film of claim 17, wherein the reactive adhesive layer has a thickness in the range of 10-100 [mu]m. 21. The light directing film of claim 17, wherein the light directing layer comprises an ordered array of a plurality of microstructures extending from the base layer. 22. The light directing film of claim 17, wherein the light directing layer comprises a disordered arrangement of a plurality of microstructures extending from the base layer. 23. The light directing film of claim 21 or 22, wherein the plurality of microstructures comprises an array of juxtaposed triangular prisms, and the orientation direction of the array of juxtaposed triangular prisms is non-linearly oriented. 24. The light directing film of claim 21 or 22, wherein the plurality of microstructures comprises an array of parallel triangular prisms, wherein one quadrangular face of each triangular prism is in the same plane. 25. The light directing film of claim 17, wherein the light directing film further comprises a primer layer between the reactive adhesive layer and the base layer. 26. The light directing film of claim 25, wherein the primer coat is a polyester primer coat or a polyacrylate primer coat. 27. The light directing film of claim 21 or 22, wherein the light directing film further comprises a light reflective layer covering and conforming to the plurality of microstructures. 28. A solar cell assembly, the solar cell assembly comprising a light-transmitting element, a front encapsulation layer, a plurality of mutually spaced solar cells, a rear encapsulation layer and a back sheet arranged in sequence along its thickness direction, wherein the solar energy The battery assembly further includes the light directing film of any one of claims 17-27, the light directing film disposed between the rear encapsulation layer and the backplate and through the reactive adhesive layer Adhered to the surface of the backing plate. 29. The solar cell assembly of claim 28, wherein a side of the back sheet facing the solar cell comprises a non-hot melt adhesive material. 30. The solar cell assembly of claim 28, wherein a side of the back sheet facing the solar cell comprises a fluorine-containing material.

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