A black backplane film with high reflectivity, preparation method and application thereof

Abstract

The present application discloses a black backplane film with high reflectivity, comprising a black reflective layer, a black support layer and a black outer layer, wherein the raw materials for preparing the black outer layer are: PET, perylene pigments, GO-HMDI-SiO2 composite materials, acrylate crosslinking agents, dispersants and antioxidants. The black backplane film with high reflectivity of the present application has excellent performance in terms of mechanical properties, photothermal stability, hiding tinting power, water vapor barrier properties and weather resistance, and also has high light reflectivity, greatly increases the photoelectric conversion rate and service life, and can meet the use requirements of solar backplane films.

Description

Technical Field

[0001] The present application relates to the technical field of new materials, and in particular to a black backplane film with high reflectivity, a preparation method and application thereof. Background Art

[0002] With the rapid development of solar cells, the photovoltaic backplane film used in solar cells has received extensive attention from researchers. The photovoltaic backplane is located on the back of the solar cell module and plays a supporting and protective role, which is of great significance to extending the service life of solar cells. Due to the long-term exposure of photovoltaic backplanes to harsh weather conditions such as high temperature and high humidity, they are easily affected by ultraviolet light, which can easily cause delamination, degradation of mechanical properties, and aging and yellowing of the backplane film, thus affecting the service life of solar cells.

[0003] Due to the large color contrast between the white photovoltaic backplane and the black solar cell, it is easy to reflect light and cause light pollution, while the black photovoltaic backplane and the all-black photovoltaic module can achieve the best color match, so researchers have conducted a lot of research on black photovoltaic backplanes. However, the black photovoltaic backplane can hardly form an effective secondary reflection of the sunlight waves, and the backplane needs to be modified accordingly to reflect ultraviolet light, thereby increasing the photoelectric conversion rate and further improving the service life of the photovoltaic module. Therefore, the preparation of black photovoltaic backplane films with high reflectivity and high weather resistance stability has become an important research direction in the field of photovoltaic backplane technology. Summary of the invention

[0004] The purpose of the present application is to provide a black backplane film with good mechanical properties and high reflectivity.

[0005] In order to achieve the above objectives, the technical solution adopted in the present application is: to provide a black backplane film with high reflectivity, including a black reflective layer, a black support layer and a black outer layer, and the raw materials for preparing the black outer layer are: PET, perylene pigments, GO-HMDI-SiO2 composite materials, acrylate crosslinking agents, dispersants and antioxidants.

[0006] As a preferred embodiment, the preparation method of the GO-HMDI-SiO2 composite material is: using a silane coupling agent to modify nano-silicon dioxide to obtain modified nano-SiO2, reacting graphene oxide with an isocyanate curing agent to obtain isocyanate-modified graphene; reacting the modified nano-SiO2 with the isocyanate-modified graphene to obtain the GO-HMDI-SiO2 composite material.

[0007] As another preference, the isocyanate curing agent is a combination of one or more of toluene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, and xylylene diisocyanate.

[0008] As another preference, the acrylate crosslinking agent is a combination of one or more of isobornyl acrylate, benzyl acrylate, 2-phenoxyethyl acrylate, ethoxylated nonylphenol acrylate, hydroxyethyl acrylate, cyclotrimethylolpropane formal acrylate, and tetrahydrofurfuryl alcohol acrylate.

[0009] As another preference, the dispersant is a combination of any one or more of silicates, phthalates, alkali metal phosphate compounds, triethylhexyl phosphoric acid, sodium dodecyl sulfate, methylpentanol, fatty acid esters, and cellulose derivatives; the antioxidant is a combination of one or more of 2,4-dimethyl-6-tert-butylphenol, 1-hydroxy-3-methyl-4-isopropylbenzene, 2,2′-methylenebis(4-ethyl-6-tert-butylphenol), N,N′-di-2-naphthyl-p-phenylenediamine, and 2,6-di-tert-butyl-α-dimethylamino-p-cresol.

[0010] The present application provides a method for preparing a black backplane film with high reflectivity, comprising the following steps: S1: modifying nano-silicon dioxide using a silane coupling agent to obtain modified nano-SiO2; reacting graphene oxide with an isocyanate curing agent to obtain isocyanate-modified graphene as a product; reacting the modified nano-SiO2 and the isocyanate-modified graphene in a solution to obtain a GO-HMDI-SiO2 composite material; S2: mixing PET, graphene oxide, perylene pigments, acrylate crosslinking agents, dispersants and antioxidants in proportion and adding the mixture to a screw extruder for extrusion to obtain a black support layer; S3: adding PET, the GO-HMDI-SiO2 composite material, perylene pigments, acrylate crosslinking agents, dispersants and antioxidants to a screw extruder for extrusion to obtain a black outer layer and a black reflective layer; stacking the black reflective layer, the black support layer and the black outer layer in sequence, and obtaining the black backplane film with high reflectivity after co-extrusion.

[0011] As another preference, the silane coupling agent is one or more combinations of -aminopropyltriethoxysilane, -methacrylphthaloxypropyltrimethoxysilane, γ-glycidyloxypropyltrimethoxysilane, -thiopropyltrimethoxysilane.

[0012] As another preferred embodiment, the mass ratio of the silane coupling agent to the nano-silicon dioxide in S1 is 1:(1-3).

[0013] As another preferred embodiment, the raw materials for preparing the black support layer are calculated by percentage: 2%-20% of the perylene black pigment, 2%-10% of the GO-HMDI-SiO2 composite material, 0.2%-5% of the acrylate crosslinking agent, 1%-5% of the dispersant, 0.5%-2% of the antioxidant, and the rest is PET.

[0014] The present application provides a photovoltaic cell, which includes, from top to bottom, a photovoltaic backplane, a packaging material, a battery cell, a packaging material and a packaging glass, wherein the photovoltaic backplane includes the above-mentioned black backplane film with high reflectivity, or a black backplane film with high reflectivity prepared by any of the above-mentioned preparation methods, and the black outer layer is arranged on a side away from the battery cell.

[0015] Compared with the prior art, the beneficial effects of this application are:

[0016] (1) The GO-HMDI-SiO2 composite material prepared in the present application is uniformly dispersed in the PET system and forms a stable barrier structure, which reduces the penetration of oxygen and moisture, and overcomes the problems of easy degradation, poor hydrolysis resistance, and easy aging of traditional PET materials;

[0017] (2) The GO-HMDI-SiO2 composite material prepared in the present application absorbs ultraviolet light and reflects visible light and infrared light, thereby effectively increasing the anti-ultraviolet and high-reflection properties of the backplane film. DETAILED DESCRIPTION

[0018] Below, the present application is further described in conjunction with specific implementation methods. It should be noted that, under the premise of no conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0019] In the description of the present application, it should be noted that directional words, such as the terms "center", "lateral", "longitudinal", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", etc., indicating directions and positional relationships are based on the directions or positional relationships shown in the scheme, which are only for the convenience of narrating the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and cannot be understood as limiting the specific scope of protection of the present application.

[0020] It should be noted that the terms "first", "second", etc. in the description and claims of the present application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence.

[0021] The terms "including" and "having" and any variations thereof in the specification and claims of this application are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus comprising a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products or apparatuses.

[0022] A high-reflectivity black backplane film of the present application has a three-layer structure, including a black reflective layer, a black support layer and a black outer layer. The raw materials for preparing the black outer layer are: PET, perylene pigments, GO-HMDI-SiO2 composite materials, acrylate crosslinking agents, dispersants and antioxidants.

[0023] This application uses PET as the substrate to prepare a black fluorine-free photovoltaic backplane film, which has excellent performance in mechanical properties, photosynthetic stability, hiding power, water vapor barrier and weather resistance, and has high light reflectivity, which greatly increases the photoelectric conversion rate and service life, and can meet the use requirements of solar backplane films.

[0024] Perylene pigments are organic pigments with excellent light resistance, heat resistance, and solubility resistance. They have a wide chromatographic range. In recent years, black varieties have been obtained by changing the color molecular structure, namely perylene black pigments. This application uses Ranbar Black P0086 perylene black pigment, pigment black 32, with a molecular formula of C 40 H 26 N2O6, with a relative molecular mass of 630.68, is a high-performance translucent green-phase black perylene black. Compared with other pigments, it has a higher reflectivity in the near-infrared band, can absorb ultraviolet light and photo-oxidative free radicals, improve good chemical resistance and light stability, has excellent light and weather resistance and high heat stability, high tinting strength, high blackness and relative transparency, non-toxic and environmentally friendly, and is used in the preparation of reflective thermal insulation coatings.

[0025] In some embodiments, the acrylate crosslinking agent is a combination of one or more of isobornyl acrylate, benzyl acrylate, 2-phenoxyethyl acrylate, ethoxylated nonylphenol acrylate, hydroxyethyl acrylate, cyclotrimethylolpropane formal acrylate, and tetrahydrofurfuryl alcohol acrylate.

[0026] In a more preferred embodiment, the acrylate crosslinking agent is 2-phenoxyethyl acrylate. The present application uses 2-phenoxyethyl acrylate as an acrylate crosslinking agent, which has excellent biocompatibility of acrylic acid, and reacts chemically with the carboxyl hydroxyl group in PET, playing a role in supporting crosslinking; and solves the problem of poor compatibility between the PET inner layer and the backplane substrate EVA film, and effectively improves the interfacial bonding strength between the backplane film inner layer and EVA. In addition, 2-phenoxyethyl acrylate has a large refractive index, and adding it to the reflective inner layer has a certain enhancement effect on color brightening and reflection.

[0027] In some embodiments, the dispersant is a combination of any one or more of silicates, phthalates, alkali metal phosphate compounds, triethylhexyl phosphoric acid, sodium lauryl sulfate, methylpentanol, fatty acid esters, and cellulose derivatives.

[0028] In a more preferred embodiment, the dispersant is sodium dodecyl sulfate. The selection of sodium dodecyl sulfate is beneficial to the dispersion of raw materials such as perylene black pigment and the adjustment of melt viscosity.

[0029] In some embodiments, the antioxidant is a combination of one or more of 2,4-dimethyl-6-tert-butylphenol, 1-hydroxy-3-methyl-4-isopropylbenzene, 2,2′-methylenebis(4-ethyl-6-tert-butylphenol), N,N′-di-2-naphthyl-p-phenylenediamine, and 2,6-di-tert-butyl-α-dimethylamino-p-cresol.

[0030] In a more preferred embodiment, the antioxidant is a combination of 1-hydroxy-3-methyl-4-isopropylbenzene and 2,6-di-tert-butyl-α-dimethylamino-p-cresol.

[0031] The present application uses perylene black as a perylene pigment. Unlike carbon black, perylene black absorbs light in the visible light band and has a certain reflective effect in the infrared light band, thus causing less heat accumulation, which will help improve the weather resistance and service life of the solar backplane film. Therefore, the highly reflective black backplane film prepared in the present application has a black appearance and secondary reflective ability to increase the photoelectric conversion rate.

[0032] The present application provides a method for preparing a GO-HMDI-SiO2 composite material, comprising the following steps:

[0033] S11: dispersing nano-silicon dioxide in toluene, adding a silane coupling agent to react, separating, washing and drying the product to obtain modified nano-SiO2;

[0034] S12: GO is dispersed in an ethanol solution, an isocyanate curing agent is added to continue the reaction, and the product is washed and dried to obtain isocyanate-modified graphene (HMDI-GO);

[0035] S13: dispersing the isocyanate-modified graphene and the modified nano-SiO2 in ethanol, followed by heating for reaction, and centrifugally washing and drying the reaction product to obtain a GO-HMDI-SiO2 composite material.

[0036] In some embodiments, the isocyanate curing agent is a combination of one or more of toluene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane-4,4′-diisocyanate, and xylylene diisocyanate.

[0037] In a more preferred embodiment, the isocyanate curing agent is dicyclohexylmethane-4,4'-diisocyanate (HMDI). Isocyanate curing agents are polyurethane materials with excellent light stability, chemical resistance, weather resistance and mechanical properties. The higher molecular weight and functionality enhance the plasticity of the PET film, and the mechanical properties are good and the adhesion is strong. The present application uses dicyclohexylmethane-4,4'-diisocyanate as a curing agent to improve the surface properties of the PET support film, reduce the pore defects on its surface, and enhance the structural stability and tensile strength of the support layer.

[0038] Graphene oxide is a two-dimensional carbon material with excellent physical, chemical, optical and electrical properties. In addition, graphene oxide also has excellent corrosion resistance and aging resistance. Under the action of isocyanate curing agent, the isocyanate group reacts with the hydroxyl and other functional groups on GO to form a stable urea bond, thereby effectively improving the hydrolysis resistance of GO, which not only enhances the chemical stability of GO, but also improves its dispersibility and compatibility in the polymer matrix, thereby improving the overall performance of the composite material.

[0039] This application uses silanized SiO2 as a high-reflection additive. Through silanization treatment, the hydrophilic hydroxyl groups on the surface of silica are converted into hydrophobic silane groups, thereby enhancing its reflective properties for infrared light. This modification not only enhances the hydrophobicity of the material, but also improves its reflectivity in the infrared region. In addition, the presence of epoxy groups in silanized silica increases steric hindrance, and synergizes with the dispersant to make nano-silica and perylene pigment particles uniformly dispersed in the PET system. The silica particles can fill the infrared absorption area between the perylene pigment particles, increase the light reflection area and path of the reflective layer, and effectively improve the reflectivity and weather resistance of the backplane film.

[0040] The present application combines silanized SiO2 with isocyanate-modified graphene. The hydrolysis resistance and light reflectivity of the silanized silicon dioxide are greatly improved, and the hydrolysis resistance and chemical stability of the isocyanate-modified graphene oxide are enhanced. The prepared high-reflectivity GO-HMDI-SiO2 composite material is uniformly dispersed in the PET system and forms a stable barrier structure, which reduces the penetration of oxygen and moisture, and overcomes the problems of easy degradation, poor hydrolysis resistance, and easy aging of traditional PET materials. In addition, the GO-HMDI-SiO2 composite material absorbs ultraviolet light and reflects visible light and infrared light, thereby effectively increasing the anti-ultraviolet and high-reflectivity properties of the backplane film.

[0041] In some embodiments, the black reflective layer and the black outer layer are made of the same raw materials. A small amount of infrared light reflected by the ground will reach the bottom surface of the photovoltaic backplane. This part of light cannot be effectively utilized. The infrared light will also cause the temperature of the side of the photovoltaic backplane facing the ground to rise. Therefore, the black reflective layer also needs to have the function of reflecting infrared light.

[0042] The high-reflectivity black backplane film of the present application is thin in material, has strong barrier properties, high mechanical strength, is resistant to aging, has strong resistance to ultraviolet rays, has good light covering rate and high reflectivity, and can be used in photovoltaic modules to extend the service life of the photovoltaic modules.

[0043] In some embodiments, the raw materials for preparing the black support layer are: PET, graphene oxide, perylene pigment, isocyanate curing agent, dispersant and antioxidant.

[0044] The present application also provides a method for preparing a black backplane film with high reflectivity, comprising the following steps:

[0045] S1: using a silane coupling agent to modify nano-silicon dioxide to obtain modified nano-SiO2; reacting graphene oxide with an isocyanate curing agent to obtain isocyanate-modified graphene; reacting the modified nano-SiO2 and isocyanate-modified graphene in a solution to obtain a GO-HMDI-SiO2 composite material;

[0046] S2: PET, graphene oxide, perylene pigment, acrylate crosslinking agent, dispersant and antioxidant are mixed evenly in proportion and added into a screw extruder for extrusion to obtain a black support layer;

[0047] S3: adding PET, GO-HMDI-SiO2 composite material, perylene pigment, acrylate crosslinking agent, dispersant and antioxidant into a screw extruder, and extruding to obtain a black outer layer and a black reflective layer;

[0048] The black reflective layer, the black supporting layer and the black outer layer are stacked in sequence, and after co-extrusion, the high-reflectivity black backplane film of the present application is obtained.

[0049] In some preferred embodiments, the silane coupling agent is one or more combinations of -aminopropyltriethoxysilane, -methacrylphthaloxypropyltrimethoxysilane, γ-glycidyloxypropyltrimethoxysilane, -thiopropyltrimethoxysilane.

[0050] In a preferred embodiment, the silane coupling agent is γ-glycidyloxypropyltrimethoxysilane.

[0051] In some embodiments, the weight ratio of the silane coupling agent to the silicon dioxide is 1:(1-3).

[0052] In some embodiments, the raw materials for preparing the black support layer are calculated by percentage: 2%-20% perylene black pigment, 2%-10% high reflective GO-HMDI-SiO2 composite material, 0.2%-5% acrylate crosslinker, 1%-5% dispersant, 0.5%-2% antioxidant, and the rest is PET.

[0053] In some embodiments, the raw materials for preparing the black reflective layer and the black outer layer are calculated by percentage: 2%-10% graphene oxide, 2%-10% perylene black pigment, 0.5%-5% isocyanate curing agent, 1%-5% dispersant, 0.5%-2% antioxidant, and the rest is PET.

[0054] The present application provides a photovoltaic cell, which includes, from top to bottom, a photovoltaic backplane, a packaging material, a battery cell, a packaging material and a packaging glass. The photovoltaic backplane includes the above-mentioned high-reflectivity black backplane film, or a high-reflectivity black backplane film prepared by any of the above-mentioned preparation methods, and the black outer layer is arranged on a side away from the battery cell.

[0055] Example 1

[0056] S1: Add nano-silica to toluene, ultrasonically disperse for 20 minutes, then add γ-glycidyloxypropyltrimethoxysilane, heat to 65°C in a water bath, stir and react for 6 hours, centrifuge the product and wash it repeatedly with purified water, and vacuum dry it at 60°C to obtain modified nano-SiO2;

[0057] GO was added to a 30% ethanol aqueous solution and ultrasonically dispersed in an ice-water bath for 30 minutes, followed by the addition of 5% dicyclohexylmethane-4,4'-diisocyanate (HMDI). After mixing evenly, the mixture was transferred to a 90°C oil bath and stirred for 8 hours. The product was cooled and centrifuged and repeatedly washed with anhydrous ethanol to remove excess HMDI. The washed product was vacuum dried at 65°C for 12 hours to obtain HMDI-GO powder.

[0058] The HMDI-GO powder and the modified nano-SiO2 were mixed in a mass ratio of 2:1, dispersed in a 30% ethanol aqueous solution, and the mixture was ultrasonically dispersed in an ice-water bath for 30 minutes, then transferred to an oil bath, the oil bath was set at 80°C and stirred for 6 hours, and after cooling, the product was centrifuged and washed with anhydrous ethanol for 3 times, and vacuum dried at 65°C for 10 hours to obtain a GO-HMDI-SiO2 composite material;

[0059] S2: According to the mass ratio, 5% of graphene oxide, 5% of perylene black pigment, 1.5% of dicyclohexylmethane-4,4'-diisocyanate, 2% of sodium dodecyl sulfate, 0.7% of 1-hydroxy-3-methyl-4-isopropylbenzene and 0.3% of 2,6-di-tert-butyl-α-dimethylamino-p-cresol, and the rest of polyethylene terephthalate (PET) are put into a high-speed mixer, mixed at 90° C. for 30 minutes, and the mixed materials are added into a screw extruder, extruded and melted to obtain a black support layer;

[0060] S3: According to the mass ratio, 10% perylene black pigment, 6% GO-HMDI-SiO2 composite material, 2% 2-phenoxyethyl acrylate, 2% sodium dodecyl sulfate, 0.7% 1-hydroxy-3-methyl-4-isopropylbenzene and 0.3% 2,6-di-tert-butyl-α-dimethylamino-p-cresol, and the rest is polyethylene terephthalate (PET) are added into a high-speed mixer, mixed at 90°C for 30 minutes, and the mixed raw materials are added into a screw extruder, and after extrusion and melting and plasticization, a black outer layer and a black reflective layer are obtained;

[0061] The black reflective layer, the black supporting layer and the black outer layer are stacked in sequence and formed by a co-extrusion casting machine to obtain a black backplane film with high reflectivity of the present application.

[0062] Example 2

[0063] In step S1, the addition ratio of HMDI-GO powder and modified nano-SiO2 is adjusted to 3:2, and the other preparation steps are consistent with those in Example 1.

[0064] Example 3

[0065] In step S1, the addition ratio of HMDI-GO powder and modified nano-SiO2 is adjusted to 3:1, and the other preparation steps are consistent with those in Example 1.

[0066] Example 4

[0067] In step S3, the addition amount of the GO-HMDI-SiO2 composite material is adjusted to 3%, and the other preparation steps are consistent with those in Example 1.

[0068] Example 5

[0069] In step S2, the addition amount of graphene oxide is adjusted to 3%, and the other preparation steps are consistent with those in Example 1.

[0070] Example 6

[0071] In step S3, the addition amount of 2-phenoxyethyl acrylate was adjusted to 4%, and the other preparation steps were consistent with those in Example 1.

[0072] Comparative Example 1

[0073] The preparation step of modified nano-SiO2 is removed in step S1, and the GO-HMDI-SiO2 composite material is replaced with HMDI-GO powder in step S3. The other preparation steps remain the same as those in Example 1.

[0074] Comparative Example 2

[0075] Preparation of GO-SiO2 powder: Add nano-silica powder to toluene, ultrasonically disperse for 20 minutes, then add γ-glycidyloxypropyltrimethoxysilane, heat the water bath to 65°C, stir and react for 6 hours; then centrifuge and repeatedly wash with purified water, vacuum dry at 60°C for 5 hours to obtain modified nano-SiO2;

[0076] A certain amount of GO and modified nano-SiO2 were added to a 30% ethanol aqueous solution in a ratio of 2:1, ultrasonically dispersed in an ice-water bath for 30 minutes, then transferred to an oil bath, stirred and reacted at 80°C for 6 hours, cooled and centrifuged, and washed with anhydrous ethanol. Finally, the precipitate was vacuum dried at 65°C for 10 hours to obtain GO-SiO2 powder.

[0077] The GO-HMDI-SiO2 composite material in step S3 was replaced with GO-SiO2 powder, and the other preparation steps were consistent with those in Example 1.

[0078] Comparative Example 3

[0079] The GO-HMDI-SiO2 composite material in step S3 was replaced by modified nano-SiO2, and the other preparation steps were consistent with those in Example 1.

[0080] Comparative Example 4

[0081] In step S3, 2-phenoxyethyl acrylate was removed, and the other preparation steps were consistent with those in Example 1.

[0082] Performance Evaluation

[0083] The black photovoltaic backplane films prepared in Examples 1 to 6 and Comparative Examples 1 to 4 were subjected to tensile tests and bending strength tests at room temperature according to GB / T1040-1992 and GB / T9341-2000 standards. The water vapor transmission rate test was conducted according to the test method in BG / T26253-2010, with the test temperature at 38°C and the test humidity at 85%. With reference to GB / T3979-2008, the reflectivity test was conducted in the wavelength range of 400-1100nm using a Color Quest XE spectrophotometer. The above test results are recorded in Table 1 below.

[0084] Table 1 Photovoltaic backsheet performance test results of each embodiment and each comparative example

[0085] Category Tensile strength(MPa) Bending strength(MPa) <![CDATA[Water vapor transmission rate (g / cm 2 ·d)]]> Reflectivity Example 1 68.26 94.22 1.08 87 Example 2 67.82 93.13 1.12 85 Example 3 67.21 91.86 1.13 83 Example 4 68.13 93.43 1.21 85 Example 5 67.02 92.56 1.15 86 Example 6 68.12 93.03 1.22 84 Comparative Example 1 68.15 93.55 1.36 53 Comparative Example 2 67.63 92.16 1.34 56 Comparative Example 3 64.11 91.24 1.65 44 Comparative Example 4 67.32 92.16 1.45 58

[0086] Judging from the performance test results of Example 1 and Comparative Examples 1 to 3, whether using pure HMDI-GO powder, modified nano-SiO2 powder, or GO-SiO2 powder, the reflectivity effect is not as good as the GO-HMDI-SiO2 composite material used in the present application. Adding GO-HMDI-SiO2 composite material to the black outer layer and black reflective layer of the photovoltaic backsheet can achieve better reflectivity while maintaining good tensile strength and bending strength of the photovoltaic backsheet, and can also reduce the water vapor permeability of the photovoltaic backsheet, thereby extending the service life of the photovoltaic backsheet.

[0087] In addition, in the preparation method of GO-HMDI-SiO2 composite material, HMDI-GO powder and modified nano-SiO2 are mixed in a mass ratio of 2:1, which can obtain the best reflectivity properties, has no effect on the tensile strength and bending strength of the photovoltaic backsheet, and can also reduce the water vapor permeability of the photovoltaic backsheet.

[0088] In summary, the high-reflectivity black backplane film of the present application has a high infrared reflectivity, increases the light reflection area and path of the reflective layer, and improves the reflective ability and weather resistance of the backplane film. Applying the high-reflectivity black backplane film of the present application to the photovoltaic backplane can improve the photoelectric conversion efficiency of the photovoltaic backplane and extend its service life.

[0089] The above describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited by the above embodiments, and the above embodiments and the specification only describe the principles of the present application. The present application may have various changes and improvements without departing from the spirit and scope of the present application, and these changes and improvements fall within the scope of the present application for which protection is sought. The scope of protection claimed by the present application is defined by the attached claims and their equivalents.

Claims

1. A black backplane film with high reflectivity, characterized in that: The invention comprises a black reflective layer, a black supporting layer and a black outer layer. The raw materials for preparing the black outer layer are: PET, perylene pigment, GO-HMDI-SiO2 composite material, acrylate crosslinking agent, dispersant and antioxidant; the preparation method of the GO-HMDI-SiO2 composite material is: using a silane coupling agent to modify nano-silicon dioxide to obtain modified nano-SiO2, reacting graphene oxide with an isocyanate curing agent to obtain isocyanate-modified graphene; reacting the modified nano-SiO2 with the isocyanate-modified graphene to obtain the GO-HMDI-SiO2 composite material.

2. The black backplane film with high reflectivity as claimed in claim 1, characterized in that: The acrylate crosslinking agent is a combination of one or more of isobornyl acrylate, benzyl acrylate, 2-phenoxyethyl acrylate, ethoxylated nonylphenol acrylate, hydroxyethyl acrylate, cyclotrimethylolpropane formal acrylate, and tetrahydrofurfuryl alcohol acrylate.

3. The black backplane film with high reflectivity as claimed in claim 1, characterized in that: The dispersant is a combination of any one or more of silicate, phthalate, alkali metal phosphate compound, triethylhexyl phosphoric acid, sodium dodecyl sulfate, methylpentanol, fatty acid ester, and cellulose derivative; the antioxidant is a combination of one or more of 2,4-dimethyl-6-tert-butylphenol, 1-hydroxy-3-methyl-4-isopropylbenzene, 2,2′-methylenebis(4-ethyl-6-tert-butylphenol), N,N′-di-2-naphthyl-p-phenylenediamine, and 2,6-di-tert-butyl-α-dimethylamino-p-cresol.

4. A method for preparing a black backplane film with high reflectivity, characterized in that: The following steps are involved: S1: using a silane coupling agent to modify nano-silicon dioxide to obtain modified nano-SiO2; reacting graphene oxide with an isocyanate curing agent to obtain a product, isocyanate-modified graphene; reacting the modified nano-SiO2 and the isocyanate-modified graphene in a solution to obtain a GO-HMDI-SiO2 composite material; S2: PET, graphene oxide, perylene pigment, acrylate crosslinking agent, dispersant and antioxidant are mixed evenly in proportion and added into a screw extruder for extrusion to obtain a black support layer; S3: adding PET, the GO-HMDI-SiO2 composite material, perylene pigment, acrylate crosslinking agent, dispersant and antioxidant into a screw extruder, and extruding to obtain a black outer layer and a black reflective layer; The black reflective layer, the black supporting layer and the black outer layer are stacked in sequence, and co-extruded to obtain the black backplane film with high reflectivity.

5. The preparation method according to claim 4, characterized in that: The silane coupling agent is one or more combinations of γ-aminopropyl triethoxysilane, γ-methacrylphthaloxypropyl trimethoxysilane, γ-glycidyloxypropyl trimethoxysilane, and γ-thiopropyl trimethoxysilane.

6. The preparation method according to claim 4, characterized in that: The mass ratio of the silane coupling agent to the nano-silicon dioxide in S1 is 1:(1-3).

7. A photovoltaic cell, comprising, from top to bottom, a photovoltaic back sheet, a packaging material, a cell sheet, a packaging material and a packaging glass, characterized in that: The photovoltaic backplane comprises the high-reflectivity black backplane film according to any one of claims 1 to 3, or the high-reflectivity black backplane film prepared by the preparation method according to any one of claims 4 to 6, and the black outer layer is arranged on a side away from the cell.