CN114437611A

CN114437611A - Reflective coating for photovoltaic back plate, photovoltaic back plate and preparation method and application of photovoltaic back plate

Info

Publication number: CN114437611A
Application number: CN202210056953.4A
Authority: CN
Inventors: 詹志英; 李伟杰; 周光大
Original assignee: Foster Jiaxing New Material Co ltd
Current assignee: Foster Jiaxing New Material Co ltd
Priority date: 2022-01-18
Filing date: 2022-01-18
Publication date: 2022-05-06

Abstract

The invention provides a reflective coating for a photovoltaic back plate, the photovoltaic back plate, a preparation method and an application thereof. The reflective coating for the photovoltaic back plate comprises, by weight, 1-30 parts of acrylate resin, 1-40 parts of active monomer, 0.01-10 parts of photoinitiator, 5-60 parts of epoxy acrylate resin, 0.01-10 parts of epoxy curing agent and 10-60 parts of reflective filler. The reflective coating for the photovoltaic back panel can be directly arranged on the substrate layer of the back panel in a coating mode, and the formed coating is directly cured on the substrate layer, so that the reflective coating has high adhesiveness with the substrate layer. In addition, the reflective coating for the photovoltaic back panel comprises acrylate resin and epoxy acrylate resin, wherein the acrylate resin is used as the light curing resin, so that a cured layer can be formed at a preset position in an exposure and development mode, a reflective structure can be formed without a special molding process, and the process is simpler.

Description

Reflective coating for photovoltaic back plate, photovoltaic back plate and preparation method and application of photovoltaic back plate

Technical Field

The invention relates to the technical field of photovoltaic backboard materials, and particularly relates to a reflective coating for a photovoltaic backboard, a preparation method and an application thereof

Background

The solar cell is a green clean energy technology which can generate a photovoltaic effect only by illumination so as to generate current for power generation. Sunlight is influenced by natural environment and is not always in the strongest state, so that the sunlight is expected to be fully utilized to improve the power generation efficiency of the solar cell, for example, a double-sided component fully utilizes a back cell piece to receive light to improve the power generation efficiency of a photovoltaic component. Improving the light utilization of the back cell requires increasing the reflection of light at the back of the module, which requires designing the structure of the photovoltaic backsheet. Considering the harsh outdoor use conditions, except that the glass back plate is a fluoropolymer back plate which is a photovoltaic back plate used more in China at present, two corresponding back plate forms are provided according to the material of the fluoropolymer, one form is a gluing composite back plate, fluorine films are compounded on two sides of polyester films such as PET (polyethylene terephthalate), the cost of the fluorine films is higher, and the production efficiency is lower due to the longer period of the film laminating process; the other method is to coat a back plate, coat fluororesin coatings on two sides of polyester films such as PET and the like, and form a film through drying and curing.

The application number 201610353453.1 discloses a PVDF film adopting a melt co-extrusion construction four-layer structure, wherein one layer is a reflective layer and plays a role in reflecting light, the process of adopting a melt co-extrusion method to prepare the reflective layer is adopted, when the thickness of the PVDF used as an inner layer is considered to be thinner, the difficulty of controlling the four-layer co-extrusion is higher, the process is complex, and the reflective layer in the PVDF film is possibly not parallel to a battery piece, so that light deflection is caused.

Chinese patent No. zl201920666840.x discloses a high reflection back plate, which has a reflection film layer to realize reflection, and also has a synergistic film layer to improve conversion to ultraviolet rays, but the high reflection back plate has a complex structure and a complex process structure; high temperature lamination conditions can damage the engineered polyolefin structure when the assembly is laminated, thereby still reducing the light utilization of the high-contrast structure.

The utility model discloses a 204315600U utility model discloses that parallel arrangement's strip reflecting structure has been found at the surface of reflector layer, reaches the reflection area who increases the reflector layer surface to improve the utilization ratio to light. The patent application with publication number CN105609575 discloses that the inner layer of the back sheet material is a polyolefin layer and a high reflection structure on the surface of the polyolefin layer, and the utilization of light is realized by the design of the high reflection structure. The strip-shaped reflecting film or the strip-shaped reflecting structure is designed, the process of the strip-shaped reflecting film is complex when the assembly is laminated, and the strip-shaped reflecting structure has the problem of damage of the reflecting structure similar to the co-extruded PVDF and the like.

Disclosure of Invention

The invention mainly aims to provide a reflective coating for a photovoltaic back plate, the photovoltaic back plate, a preparation method and application thereof, and aims to solve the problems of insufficient adhesive force of a reflective layer of the photovoltaic back plate and complex preparation in the prior art.

In order to achieve the above object, according to one aspect of the present invention, there is provided a reflective paint for a photovoltaic back panel, which comprises, by weight, 1 to 30 parts of an acrylate resin, 1 to 40 parts of an active monomer, 0.01 to 10 parts of a photoinitiator, 5 to 60 parts of an epoxy acrylate resin, 0.01 to 10 parts of an epoxy curing agent, and 10 to 60 parts of a reflective filler.

Further, the reflective coating for the photovoltaic back panel comprises 5-25 parts of acrylate resin, 10-40 parts of active monomer, 1-8 parts of photoinitiator, 20-50 parts of epoxy acrylate resin, 1-10 parts of epoxy curing agent and 20-40 parts of reflective filler, wherein the acrylate resin is selected from any one or more of resins copolymerized from any one or more of the following monomers: (meth) acrylic acid, alkyl (meth) acrylates, styrene, benzyl (meth) acrylate; the alkyl (meth) acrylate is preferably selected from any one of methyl methacrylate, butyl acrylate, isooctyl acrylate, butyl methacrylate, and hydroxyethyl methacrylate.

Further, the epoxy acrylate resin is selected from any one or more of bisphenol A epoxy acrylate resin, hydrogenated bisphenol A epoxy acrylate resin, novolac epoxy acrylate resin and epoxidized oil acrylate resin.

Further, the reactive monomer is selected from any one or more of pentaerythritol triacrylate, pentaerythritol tetraacrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate and trimethylolpropane triacrylate.

Further, the photoinitiator is selected from any one or more of benzophenone, alpha-hydroxy-alpha, alpha-dimethylacetophenone, 1-hydroxycyclohexyl phenyl ketone, alpha-aminoalkylphenyl ketone, 2,4, 6-trimethylbenzoyl diphenyl phosphine oxide, bis (2,4, 6-trimethylbenzoyl) phenyl phosphine oxide, 2- (o-chlorophenyl) -4, 5-diphenyl imidazole dimer, and 9-phenylacridine.

Further, the epoxy curing agent is selected from one or more of aliphatic amine curing agents, aromatic amine curing agents, acid anhydride curing agents, imidazole curing agents and latent curing agents.

Further, the reflective filler is selected from one or two of glass beads and titanium dioxide, preferably a mixture of the glass beads and the titanium dioxide in a mass ratio of 1: 10-10: 1, preferably the glass beads are selected from one or more of galvanized glass beads, silver-plated glass beads and aluminum-plated glass beads, preferably the titanium dioxide is rutile titanium dioxide, and preferably 20-40 parts.

Further, the reflective coating for the photovoltaic back panel further comprises a solvent, wherein the solvent is selected from any one or more of acetone, butanone, methanol, ethanol, isopropanol, ethylene glycol methyl ether and propylene glycol methyl ether, preferably the reflective coating for the photovoltaic back panel further comprises a hydrogen donor, a leveling agent and/or an antifoaming agent, and preferably the hydrogen donor is selected from one or more of triethylamine, mercaptobenzothiazole, 2- (dimethylamino) ethanol, mercaptobenzimidazole and the like.

According to another aspect of the invention, a photovoltaic back plate is provided, which includes a substrate layer and a reflective layer, wherein the reflective layer is obtained by drying, exposing and developing any one of the above reflective coatings for photovoltaic back plates, one side of the reflective layer away from the substrate layer has a rough surface, preferably the rough surface has a reflective microstructure, a cross section of the reflective microstructure parallel to the substrate layer is reduced along a direction away from the substrate layer, further preferably a cross section of the reflective microstructure perpendicular to the substrate layer is a cone or a trapezoid, and further preferably the reflective microstructure is a pyramid.

Furthermore, the thickness of the reflecting layer is 3-20 μm, preferably 5-15 μm; preferably, the height of the reflective microstructure corresponds to the thickness of the reflective layer.

Further, the thickness of the base material layer is 100 to 350 μm, and more preferably 200 to 300 μm.

Further, the photovoltaic back plate further comprises a reinforcing layer, the reinforcing layer covers the reflecting layer and the base material layer, the thickness of the reflecting layer is larger than or equal to that of the reinforcing layer, and the difference between the thickness of the reflecting layer and the thickness of the reinforcing layer is not larger than 8 μm, preferably not larger than 5 μm, and further preferably not larger than 3 μm; or the reinforcing layer is positioned on the surface of the base material layer, and the reflecting layer is arranged on the surface of the reinforcing layer far away from the base material layer; the thickness of the reinforcing layer is preferably 3 to 20 μm, and more preferably 5 to 15 μm.

Further, the photovoltaic back plate further comprises an air weather-resistant layer, the air weather-resistant layer is arranged on the surface, far away from the reflecting layer, of the base material layer, and the thickness of the air weather-resistant layer is preferably 10-30 micrometers.

Further, the preparation method comprises the following steps: step S1, arranging a reflective coating for the photovoltaic back panel on one surface of the substrate layer to obtain a wet coating; step S2, drying, exposing, and developing the wet coating to obtain a reflective layer.

Further, the exposure intensity is 0.1-120 mJ/cm²(ii) a Preferably, the developing solution used for developing is any one of 0.1-5 wt% of sodium carbonate solution, 0.1-5 wt% of potassium carbonate solution, 0.1-5 wt% of sodium hydroxide solution and 0.1-5 wt% of diluted sodium tetraborate solution; preferably, the pH value of the developing solution is between 8 and 12.

Further, after the development, the preparation method further comprises the step of carrying out thermocuring on the developed coating to obtain the reflecting layer, wherein the thermocuring temperature is preferably 100-200 ℃, and the thermocuring time is preferably 3-30 min.

Further, the preparation method also comprises the following steps: step S3, covering the raw material of the reinforcing layer on the reflecting layer and the base material layer to form a reinforcing preparation layer, and step S4, carrying out heat curing on the reinforcing preparation layer to obtain a reinforcing layer; alternatively, before step S1, the preparation method further includes: step S01, a raw material for a reinforcing layer is provided on the base material layer to form a reinforcing preliminary layer, step S02, the reinforcing preliminary layer is thermally cured to obtain a reinforcing layer, and step S1, the reflective paint for the photovoltaic back sheet is provided on the surface of the upper base material layer of the reinforcing layer.

Further, the preparation method also comprises the following steps: arranging the air weather-resistant layer raw material on the other surface of the base material layer to obtain an air weather-resistant preparation layer; and thermally curing the air weather-proof preparation layer to obtain the air weather-proof layer.

According to another aspect of the invention, a photovoltaic cell module is provided, which comprises a front transparent packaging plate, a front packaging adhesive film, a solar cell unit, a back packaging adhesive film and a back plate, wherein the solar cell unit comprises cells arranged in an array.

By applying the technical scheme of the invention, the reflective coating for the photovoltaic back panel can be directly arranged on the substrate layer of the back panel in a coating mode, and the formed coating is directly cured on the substrate layer, so that the adhesiveness of the reflective coating with the substrate layer is higher. In addition, the reflective coating for the photovoltaic back panel comprises acrylate resin and epoxy acrylate resin, wherein the acrylate resin is used as light curing resin, so that a cured layer can be formed at a preset position in an exposure and development mode, and the uncured acrylate resin at the exposure position is removed in subsequent development by controlling the exposure degree, so that a rough surface with a multi-angle reflection function is formed, a reflection structure can be formed without a special forming process, and the process is simpler. Meanwhile, the light-reflecting filler in the reflective coating for the photovoltaic back plate also plays a role in light reflection, so that the light reflection efficiency of the photovoltaic back plate is further improved, and the utilization rate of the photovoltaic module to sunlight is further improved.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:

fig. 1 shows a schematic view of a photovoltaic backsheet according to embodiments of a reflective coating for a photovoltaic backsheet, a photovoltaic backsheet and a method for preparing the same.

Wherein the figures include the following reference numerals:

1. a substrate layer; 2. a reflective layer; 3. a reinforcing layer; 4. an air weathering layer.

Detailed Description

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.

As analyzed by the background art of the application, the reflective layer of the photovoltaic back plate in the prior art has insufficient adhesive force and is complex to prepare, and aiming at the problem, the application provides a reflective coating for the photovoltaic back plate, a preparation method and an application thereof.

In a typical embodiment, the reflective coating for the photovoltaic back panel comprises 1-30 parts by weight of acrylate resin, 1-40 parts by weight of active monomer, 0.01-10 parts by weight of photoinitiator, 5-60 parts by weight of epoxy acrylate resin, 0.01-10 parts by weight of epoxy curing agent and 10-60 parts by weight of reflective filler.

The application discloses reflective coating for photovoltaic backplate can directly set up on the substrate layer of backplate with the coated mode, and the coating that forms is directly solidification on the substrate layer, consequently higher with the adhesion of substrate layer. In addition, the reflective coating for the photovoltaic back panel comprises acrylate resin and epoxy acrylate resin, wherein the acrylate resin is used as light curing resin, so that a cured layer can be formed at a preset position in an exposure and development mode, and the uncured acrylate resin at the exposure position is removed in subsequent development by controlling the exposure degree, so that a rough surface with a multi-angle reflection function is formed, a reflection structure can be formed without a special forming process, and the process is simpler. Meanwhile, the light-reflecting filler in the reflective coating for the photovoltaic back plate also plays a role in light reflection, so that the light reflection efficiency of the photovoltaic back plate is further improved, and the utilization rate of the photovoltaic module to sunlight is further improved.

In order to improve the synergistic effect among the components and comprehensively consider the adhesiveness and the reflection performance of the formed coating, the preferable reflective coating for the photovoltaic back panel comprises 5-25 parts of acrylate resin, 10-40 parts of active monomer, 1-8 parts of photoinitiator, 20-50 parts of epoxy acrylate resin, 1-10 parts of epoxy curing agent and 20-40 parts of reflective filler.

The acrylate resin used in the present application may be selected from acrylate resins commonly used in the art, and in order to improve compatibility and synergistic effect of the acrylate resin with the epoxy acrylate resin, in some embodiments, the acrylate resin is selected from any one or more of resins copolymerized from any one or more of the following monomers: (meth) acrylic acid, alkyl (meth) acrylates, styrene, benzyl (meth) acrylate, preferably the alkyl (meth) acrylate is selected from methyl methacrylate, butyl acrylate, isooctyl acrylate, butyl methacrylate, hydroxyethyl methacrylate.

In some embodiments, the epoxy acrylate resin is selected from any one or more of bisphenol a epoxy acrylate resin, hydrogenated bisphenol a epoxy acrylate resin, novolac epoxy acrylate resin, and epoxidized oil acrylate resin. The epoxy acrylic resin is added, so that the heat curing performance of the light reflecting coating for the photovoltaic back panel is ensured, the photocuring speed of the coating is improved as much as possible, and the corrosion resistance, the heat resistance, the wear resistance and the adhesion of a cured coating film can be improved.

In the present application, in order to increase the photocuring rate and adhesion of the above reflective coating, a reactive monomer is added. In some embodiments, the reactive monomer includes, but is not limited to, any one or more of pentaerythritol triacrylate, pentaerythritol tetraacrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, and trimethylolpropane triacrylate.

The use of photoinitiators can increase the cure rate of the coating. In some embodiments, the photoinitiator includes, but is not limited to, any one or more of benzophenone, α -hydroxy- α, α -dimethylacetophenone, 1-hydroxycyclohexyl phenyl ketone, α -aminoalkylphenyl ketone, 2,4, 6-trimethylbenzoyl diphenyl phosphine oxide, bis (2,4, 6-trimethylbenzoyl) phenyl phosphine oxide, 2- (o-chlorophenyl) -4, 5-diphenylimidazole dimer, and 9-phenylacridine.

The coating is also added with an epoxy curing agent which is used for carrying out chemical reaction with epoxy acrylate resin to form a reticular three-dimensional polymer so as to promote curing. In some embodiments, the epoxy curing agent is selected from any one or more of aliphatic amine curing agents, aromatic amine curing agents, anhydride curing agents, imidazole curing agents, and latent curing agents. The specific selection of the epoxy acrylate resin and the epoxy curing agent can be referred to in the prior art, and the detailed description is omitted.

The application discloses photovoltaic is its reflective properties of reflective coating for backplate benefit from its reflection of light filler that adds to a great extent, improves the quantity of reflection of light filler moreover, can improve the reflective properties of coating. In some embodiments, the reflective filler is selected from any one or two of glass beads and titanium dioxide, and is preferably a mixture of glass beads and titanium dioxide in a mass ratio of 1:10 to 10: 1. The glass beads are low in price, high-temperature resistant, easy to disperse in organic components and good in light reflection performance, and preferably, the glass beads are selected from any one or more of galvanized glass beads, silver-plated glass beads and aluminum-plated glass beads. The titanium dioxide is added into the paint, which is beneficial to protecting the stability of a paint film, enhancing the mechanical strength and the adhesive force of the paint film, preventing cracks and prolonging the service life of the paint film. Preferably, the titanium dioxide is rutile titanium dioxide which is relatively stable and has good weather resistance.

In some embodiments, in order to facilitate direct construction of the reflective paint for photovoltaic back sheets, the reflective paint for photovoltaic back sheets further comprises a solvent selected from any one or more of acetone, butanone, methanol, ethanol, isopropanol, ethylene glycol methyl ether and propylene glycol methyl ether. By weight, the amount of the solvent is preferably 10-50 parts, so that the viscosity of the reflective coating for the photovoltaic back panel can be adjusted by adjusting the amount of the solvent, and construction coating is facilitated.

The skilled person can also add some auxiliary agents according to other performance requirements of the photovoltaic back sheet, for example, in some embodiments, the reflective coating for photovoltaic back sheet further comprises a hydrogen donor, a leveling agent and/or an antifoaming agent, wherein the hydrogen donor is selected from one or more of triethylamine, mercaptobenzothiazole, 2- (dimethylamino) ethanol, mercaptobenzimidazole, and the like.

In another exemplary embodiment of the present application, a photovoltaic back sheet is provided, as shown in fig. 1, the photovoltaic back sheet includes a substrate layer 1 and a reflective layer 2, wherein the reflective layer 2 is obtained by drying, exposing, and developing the above coating for a photovoltaic back sheet, and has a rough surface on the side of the reflective layer 2 away from the substrate layer 1.

The utility model provides a photovoltaic is reflective coating for backplate directly sets up on the substrate layer of backplate with the mode of coating, and the coating that forms is direct solidifies on the substrate layer, consequently is higher with the adhesion of substrate layer. In addition, because the reflective coating for the photovoltaic back panel contains the acrylate resin and the epoxy acrylate resin, and the acrylate resin is used as the light-cured resin, a cured layer can be formed at a preset position in an exposure and development mode, and the exposure degree is controlled to remove part of uncured acrylate resin at the exposure position in subsequent development, so that a rough surface with a reflection function is formed, a special molding process is not needed to form the rough surface with multi-angle reflection, and the process is simpler. Meanwhile, the light-reflecting filler in the reflective coating for the photovoltaic back plate also plays a role in light reflection, so that the light reflection efficiency of the photovoltaic back plate is further improved, and the utilization rate of the photovoltaic module to sunlight is further improved.

By controlling the conditions of the exposure and development, in some embodiments, it is preferable that the rough surface has a reflective microstructure whose cross section parallel to the substrate layer 1 decreases in a direction away from the substrate layer 1, it is further preferable that the cross section of the reflective microstructure perpendicular to the substrate layer 1 is tapered or trapezoidal, and it is further preferable that the reflective microstructure is pyramidal.

Because the photovoltaic back plate forms a module after being laminated with a solar cell unit and the like, on the basis of ensuring the reflection effect of the reflecting layer 2 and avoiding generating excessive pressure stress on the cell, in some embodiments, the thickness of the reflecting layer 2 is 3-20 μm, preferably 5-15 μm; it is further preferable that the height of the reflective microstructure is equal to the thickness of the reflective layer.

The photovoltaic backboard has the advantages that the reflection area is increased on one hand by the reflection microstructures on the surface of the reflection layer, the overall reflectivity is improved, the output power of the photovoltaic board is improved, and on the other hand, the rough surface has an anchoring effect, so that the peeling strength after lamination is enhanced.

In some embodiments, the reflective layer 2 is distributed on the substrate layer 1 in a grid manner, and the distribution positions are set according to the arrangement positions of the solar cells, so that the utilization rate of solar energy is improved, and resources are saved. In some preferred embodiments, the reflective layer 2 is disposed on the whole surface of the substrate layer, so that the cell sheet, especially the back cell sheet of the double-sided cell sheet photovoltaic cell module, sufficiently receives the light reflected back by the reflective layer.

The thickness of substrate layer 1 in the photovoltaic backplate of this application can refer to prior art's substrate layer thickness, for example selects the thickness of substrate layer 1 to be 100 ~ 350 mu m, preferably 200 ~ 300 mu m to provide enough support and protection to the battery piece. The material of the substrate layer 1 is common transparent back plate material, such as white or semi-white polyethylene naphthalate film, polytrimethylene terephthalate film, polyethylene terephthalate film, polybutylene terephthalate film, polycarbonate film, copolymerized silicon modified polycarbonate film, polymethyl methacrylate film, and the like, preferably polyethylene terephthalate film. In order to improve environmental compatibility, in some embodiments of the present application, the photovoltaic backsheet further comprises a stiffening layer 3, as shown in fig. 1. The arrangement of the reinforcing layer 3 reduces the reflection path of light and the transmission of light, thereby achieving the effect of reinforcing reflection. The reinforcing layer 3 may be provided in various ways, for example in one way the reinforcing layer covers the reflective layer 2, i.e. in the order reinforcing layer 3, reflective layer 2, substrate 1. The thickness of the reflecting layer 2 is larger than or equal to that of the reinforcing layer 3, so that the rough surface or the microstructure of the reflecting layer 2 can still be displayed after the reinforcing layer 3 is applied, and the reflecting effect is ensured by utilizing the roughness enhancement of the reflecting layer 2 and the peeling strength of a back layer packaging adhesive film in the photovoltaic module; in order to avoid excessive thickness difference between the reinforcing layer 3 and the reflecting layer 2 and excessive compressive stress generated during lamination of the assembly to cause subfissure of the cell, the thickness difference between the reflecting layer 2 and the reinforcing layer 3 is preferably not more than 8 μm, preferably not more than 5 μm, and further preferably not more than 3 μm, so as to ensure continuous stability of the subsequent production process.

In another mode, the reinforcing layer 3 is located on the surface of the base material layer 1, and the reflective layer 2 is disposed on the surface of the reinforcing layer 3 away from the base material layer 1, that is, the reflective layer 2, the reinforcing layer 3, and the base material 1 are disposed in this order.

In some embodiments, the thickness of the reinforcing layer 3 is 3 to 20 μm, preferably 5 to 15 μm, so as to sufficiently protect the substrate layer 1. The photovoltaic back plate formed by the former is more firm and durable because the reinforcing layer 3 plays a role in protecting the reflecting layer 2.

To further enhance environmental compatibility and improve the water, high temperature, and aging resistance of the photovoltaic backsheet, in some embodiments, the photovoltaic backsheet further includes an air weathering layer 4, as shown in fig. 1. The air weather-resistant layer 4 is arranged on the surface of the base material layer 1 far away from the reflecting layer 2, and the thickness of the air weather-resistant layer 4 is preferably 10-30 μm.

In some embodiments, the air weather-resistant layer 4 is prepared by coating raw materials comprising 100 parts of main resin, 0.1-30 parts of modified resin, 1-50 parts of curing agent, 1-60 parts of inorganic filler, 0.1-10 parts of auxiliary agent and 10-200 parts of solvent according to a certain proportion, and then coating and heating and curing the surface of the substrate layer 1.

The reinforcing layer 3 can be made of the same formulation as the air-resistant layer 4. When different formulas are selected for the reinforcing layer 3 and the air weather-resistant layer 4, the main resin of the reinforcing layer 3 can be hydroxyl acrylate resin, the main resin of the air weather-resistant layer 4 is fluorocarbon resin, and when the formulas are the same, the main resins of the reinforcing layer 3 and the air weather-resistant layer 4 are both fluorocarbon resin; the modified resin is selected from butanol etherified amino resin, butanol etherified urea resin, epoxy resin, C5 petroleum resin, terpene resin, organic silicon resin, etc.; the curing agent is selected from hexamethylene diisocyanate tripolymer, hexamethylene diisocyanate biuret, diphenylmethane diisocyanate tripolymer, isophorone diisocyanate prepolymer, isophorone diisocyanate-trimethylolpropane methanol substance, imidazole modified isocyanate curing agent and the like; the inorganic filler is selected from titanium dioxide or a mixture of titanium dioxide and glass beads and the like; the auxiliary agent is formed by mixing one or more of a dispersing agent, a flatting agent, a coupling agent and the like according to any proportion; the solvent is selected from xylene, ethyl acetate, butyl acetate, propylene glycol methyl ether acetate, butanone, ethanol, isopropanol, N-methylpyrrolidone, dimethyl sulfoxide, etc.

In another exemplary embodiment of the present application, there is provided a method of preparing a photovoltaic backsheet, the method comprising: step S1, arranging a reflective coating for the photovoltaic back panel on one surface of the substrate layer 1 to obtain a wet coating; in step S2, the wet coating is dried, exposed, and developed to obtain the reflective layer 2.

With the direct setting of the photovoltaic for backplate reflective coating of this application on the substrate layer of backplate, the coating that forms solidifies directly on the substrate layer, consequently higher with the adhesion of substrate layer. In addition, the reflective coating for the photovoltaic back panel comprises acrylate resin and epoxy acrylate resin, wherein the acrylate resin is used as light curing resin, so that a cured layer can be formed at a preset position in an exposure and development mode, and the uncured acrylate resin at the exposure position is removed in subsequent development by controlling the exposure degree, so that a rough surface with a multi-angle reflection function is formed, a reflection structure can be formed without a special forming process, and the process is simpler. Meanwhile, the light-reflecting filler in the reflective coating for the photovoltaic back plate also plays a role in light reflection, so that the light reflection efficiency of the photovoltaic back plate is further improved, and the utilization rate of the photovoltaic module to sunlight is further improved.

The roughness of the formed reflecting layer 2 can be adjusted by adjusting exposure and development conditions, under certain exposure conditions, the reflecting coating for the photovoltaic back plate is solidified to a certain extent to form a semi-solidified layer, and when developing is carried out by adopting developing solution, the contact time between the developing solution on the surface layer and the semi-solidified layer is longer, so that more resin is removed, a structure with a smaller upper layer and a larger bottom layer is formed, and the reflecting effect is realized.

In some embodiments, it is preferable that the intensity of the exposure is 0.1 to 120mJ/cm²(ii) a Further preferably, the developing solution used for developing is selected from any one of 0.1 wt% -5 wt% of dilute sodium carbonate solution, 0.1 wt% -5 wt% of dilute potassium carbonate solution, 0.1 wt% -5 wt% of dilute sodium hydroxide solution and 0.1 wt% -5 wt% of dilute sodium tetraborate solution; preferably, the pH value of the dilute solution is between 8 and 12.

In order to improve the curing speed and the strength of the coating, in some embodiments, the developed coating is thermally cured to obtain the reflective layer 2, preferably at a temperature of 100 to 200 ℃ for 3 to 30 min. The heat curing may be performed directly after the development, or may be performed along with the heat curing of the subsequent reinforcing layer 3 or the air-weatherable layer 4.

In some embodiments, the method for preparing the photovoltaic back sheet further comprises: step S3, covering the raw material of the reinforcing layer 3 on the reflecting layer 2 and the base material layer 1 to form a reinforcing preparation layer; in step S4, the reinforcing preliminary layer is thermally cured to obtain the reinforcing layer 3. Alternatively, before the step S1, the preparation method further includes: step S01, arranging a raw material of a reinforcing layer 3 on a base material layer 1 to form a reinforcing preparation layer; step S02 of heat-curing the reinforcing preparatory layer to obtain a reinforcing layer 3, and then step S1 of disposing a reflective paint for a photovoltaic back sheet on the surface of the above-mentioned base material layer 1 of the reinforcing layer 3. The photovoltaic back plate formed in the two different steps has different structures, the reinforcing layer formed in the two different steps is covered with the reflecting layer 2 and the base material layer 1, and the developed reflecting layer 2 is cured simultaneously when the reinforcing layer is thermally cured; or the reflective layer 2 is provided on the reinforcing layer 3.

In some preferred embodiments, the preparation method further comprises: arranging a raw material of an air weather-resistant layer 4 on the other surface of the base material layer 1 to obtain an air weather-resistant preparation layer; the air weathering preparation layer was thermally cured to obtain the air weathering layer 4. The base material layer 1 is protected by the air-resistant layer 4.

When the reinforcing preparation layer and/or the air weather-resistant preparation layer are/is thermally cured, the thermal curing temperature is preferably 100-200 ℃, and the thermal curing time is preferably 3-30 min.

In another exemplary embodiment of the present application, there is provided a photovoltaic cell module including a front transparent encapsulant sheet, a front encapsulant film, a solar cell sheet unit, a back encapsulant film, and a back sheet having the above coating layer.

When the reflecting layer 2 is arranged in contact with the back layer packaging adhesive film and laminated, double bonds in the acrylate resin and the epoxy acrylate resin of the reflecting layer 2 are crosslinked with resin double bonds in the adhesive film, so that the peeling strength of the back plate and the adhesive film can be further improved.

The advantageous effects of the present application will be further described below with reference to examples and comparative examples.

Example 1

Preparing 10 parts by weight of acrylate resin, 20 parts by weight of active monomer, 3 parts by weight of photoinitiator, 30 parts by weight of epoxy acrylate resin, 2 parts by weight of epoxy curing agent, 35 parts by weight of aluminized glass microspheres and titanium dioxide which are mixed according to a ratio of 1:2, 25 parts by weight of methanol, acetone and propylene glycol methyl ether mixed solvent which are mixed according to a ratio of 2:2:1 into a reflective coating for later use, coating the surface of 250 mu m white PET with the reflective coating with the thickness of 15 mu m, drying, exposing, developing and molding to obtain the pyramid-shaped reflective layer, wherein the exposure intensity is 20mj/cm²The developing solution is selected from 1% sodium carbonate aqueous solution, and the pH value is 11.7.

Then, 100 parts of fluorocarbon resin (LF-200) and 20 parts of butanol etherified amino resin (amino resin 5860,jiangsu Sanmu chemical industry), 25 parts of isophorone diisocyanate trimer (I)

Z4470 MPA/X), 50 parts of titanium dioxide (TR88), 5 parts of auxiliary agent and 150 parts of dimethylbenzene, wherein the fluorocarbon coating is firstly coated on one surface with a reflecting layer, the curing is carried out for 3min at 180 ℃ to obtain a reinforcing layer with the thickness of 15 microns, the fluorocarbon coating is then coated on the other surface, the curing is carried out for 5min at 180 ℃ to obtain an air weather-resistant layer with the thickness of 20 microns, the photovoltaic back panel is coated, and the interlayer structure is shown in the attached drawing 1.

Wherein the acrylic resin is prepared by solution free radical copolymerization of 26 parts of methacrylic acid, 14 parts of butyl methacrylate, 42 parts of styrene and 18 parts of benzyl methacrylate, and the weight average molecular weight of the acrylic resin is about 50000; the active monomer is selected from trimethylolpropane triacrylate; the photoinitiator is a mixture of 2- (o-chlorophenyl) -4, 5-diphenyl imidazole dimer and 9-phenylacridine in a mass ratio of 9: 1; epoxy acrylate resin A type epoxy acrylate resin (EP-4080); the epoxy curing agent is triphenylphosphine; the filler is selected from a mixture of glass beads and titanium dioxide in a mass ratio of 6: 4.

Example 2

The difference from example 1 is that the reinforcing layer has a thickness of 14 μm.

Example 3

The difference from example 1 is that the reinforcing layer has a thickness of 12 μm.

Example 4

The difference from example 1 is that the reinforcing layer has a thickness of 10 μm.

Example 5

The difference from example 1 is that the reflective layer has a thickness of 12 μm.

Example 6

The difference from example 1 is that the reflective layer has a thickness of 10 μm.

Example 7

The difference from example 1 is that the reflective layer has a thickness of 10 μm and the reinforcing layer has a thickness of 10 μm.

Example 8

The difference from example 1 is that the reflective layer has a thickness of 10 μm and the reinforcing layer has a thickness of 8 μm.

Example 9

The difference from example 1 is that the reflective layer is 8 μm thick and the reinforcing layer is 10 μm thick.

Example 10

The difference from example 1 is that the reflective layer has a thickness of 6 μm and the reinforcing layer has a thickness of 5 μm.

Example 11

The difference from example 1 is that the reflective layer is 3 μm thick and the reinforcing layer is 3 μm thick.

Example 12

The difference from example 1 is that the reflective layer is 5 μm thick and the reinforcing layer is 20 μm thick.

Example 13

The difference from example 1 is that the reflective layer has a thickness of 20 μm and the reinforcing layer has a thickness of 12 μm.

Example 14

The difference from example 1 is that the reinforcing layer is not coated.

Example 15

The difference from example 1 is that the reflective layer has a thickness of 20 μm and the reinforcing layer has a thickness of 18 μm.

Example 16

The difference from example 1 is that the reflective layer has a thickness of 25 μm and the reinforcing layer has a thickness of 23 μm.

Example 17

The difference from example 1 is that the exposure amount was 0.1mj/cm²。

Example 18

The difference from example 1 is that the exposure amount was 120mj/cm²。

Example 19

The difference from example 1 is that the developer solution is 1% aqueous sodium hydroxide solution and has a pH of 13.4.

Example 20

The difference from example 1 is that the epoxy acrylate resin was a novolac epoxy acrylate resin (prepared from an acrylic-modified novolac epoxy resin F51).

Example 21

The difference from the example 1 is that 35 parts of glass micro-beads and rutile titanium dioxide which are mixed by 10:1 of reflective filler are added.

Example 22

The difference from example 1 is that the composition of the reflective coating is: 30 parts of acrylate resin, 10 parts of active monomer, 10 parts of photoinitiator, 5 parts of epoxy acrylate resin, 10 parts of epoxy curing agent, 35 parts of aluminized glass microsphere and titanium dioxide mixed according to a ratio of 1:2 and 25 parts of methanol, acetone and propylene glycol methyl ether mixed solvent mixed according to a ratio of 2:2: 1.

Example 23

The difference from example 1 is that the composition of the reflective coating is: 5 parts of acrylate resin, 40 parts of active monomer, 0.1 part of photoinitiator, 20 parts of epoxy acrylate resin, 0.1 part of epoxy curing agent, 35 parts of silver-plated glass microbeads and titanium dioxide which are mixed according to a ratio of 1:2 and 25 parts of methanol, acetone and propylene glycol methyl ether mixed solvent which are mixed according to a ratio of 2:2: 1.

Example 24

The difference from example 1 is that the composition of the reflective coating is: 14 parts of acrylate resin, 28 parts of active monomer, 3.5 parts of photoinitiator, 42 parts of epoxy acrylate resin, 2.5 parts of epoxy curing agent, 10 parts of aluminum glass micro-beads and titanium dioxide mixed according to a ratio of 1:2 and 25 parts of methanol, acetone and propylene glycol methyl ether mixed solvent mixed according to a ratio of 2:2: 1.

Example 25

The difference from example 1 is that the composition of the reflective coating is: 6 parts of acrylate resin, 12 parts of active monomer, 2 parts of photoinitiator, 18 parts of epoxy acrylate resin, 2 parts of epoxy curing agent, 60 parts of 1:2 mixed zinc-coated glass microsphere and titanium dioxide and 25 parts of 2:2:1 mixed methanol, acetone and propylene glycol methyl ether mixed solvent.

Example 26

The difference from example 1 is that the composition of the reflective coating is: 6 parts of acrylate resin, 6 parts of active monomer, 0.04 part of photoinitiator, 30 parts of epoxy acrylate resin, 0.06 part of epoxy curing agent, 60 parts of aluminized glass microsphere and titanium dioxide mixed according to a ratio of 1:2 and 25 parts of methanol, acetone and propylene glycol methyl ether mixed according to a ratio of 2:2: 1.

Example 27

The composition of the reflective coating, the composition of the raw materials of the reinforcing layer and the composition of the raw materials of the air weather-resistant layer are the same as those in example 1, except that the preparation steps are as follows:

the raw material of the reinforcing layer is coated on the surface of white PET and cured for 3min at 180 ℃ to form the reinforcing layer.

A reflective coating was applied to the reinforcing layer, and the layer was exposed and developed under the conditions of example 1 to form a reflective layer.

Coating the other surface of the white PET with the raw material of the air weather-resistant layer, and curing at 180 ℃ for 5min to form the air weather-resistant layer.

Example 28

The difference from example 1 is that the composition of the reflective coating is: 30 parts of acrylate resin, 16 parts of active monomer, 2.5 parts of photoinitiator, 23 parts of epoxy acrylate resin, 1.5 parts of epoxy curing agent, 27 parts of aluminized glass microsphere and titanium dioxide mixed according to a ratio of 1:2 and 25 parts of methanol, acetone and propylene glycol methyl ether mixed according to a ratio of 2:2: 1.

Example 29

The difference from example 1 is that the composition of the reflective coating is: 7.5 parts of acrylate resin, 40 parts of active monomer, 3 parts of photoinitiator, 22 parts of epoxy acrylate resin, 2 parts of epoxy curing agent, 25.5 parts of 1:2 mixed aluminized glass microsphere and titanium dioxide and 25 parts of 2:2:1 mixed methanol, acetone and propylene glycol methyl ether mixed solvent.

Example 30

The difference from example 1 is that the composition of the reflective coating is: 6 parts of acrylate resin, 12 parts of active monomer, 1 part of photoinitiator, 60 parts of epoxy acrylate resin, 2 parts of epoxy curing agent, 19 parts of aluminized glass microsphere and titanium dioxide mixed according to a ratio of 1:2 and 25 parts of methanol, acetone and propylene glycol methyl ether mixed solvent mixed according to a ratio of 2:2: 1.

Comparative example 1

The difference from example 1 is that the reflective layer is not coated.

Comparative example 2

The difference from example 1 is that the reinforcing layer is not coated and the reflective layer is not developed to a set shape.

Comparative example 3

The difference from example 1 is that the composition of the reflective coating is: 40 parts of acrylate resin, 14 parts of active monomer, 2 parts of photoinitiator, 20 parts of epoxy acrylate resin, 1 part of epoxy curing agent, 23 parts of aluminized glass microsphere and titanium dioxide mixed according to a ratio of 1:2 and 25 parts of methanol, acetone and propylene glycol methyl ether mixed solvent mixed according to a ratio of 2:2: 1.

Comparative example 4

The difference from example 1 is that the composition of the reflective coating is: 0 part of acrylate resin, 22 parts of active monomer, 3.5 parts of photoinitiator, 33 parts of epoxy acrylate resin, 2.5 parts of epoxy curing agent, 39 parts of aluminized glass microsphere and titanium dioxide mixed according to a ratio of 1:2 and 25 parts of methanol, acetone and propylene glycol methyl ether mixed according to a ratio of 2:2: 1.

Comparative example 5

The difference from example 1 is that the composition of the reflective coating is: 6 parts of acrylate resin, 50 parts of active monomer, 2.5 parts of photoinitiator, 18 parts of epoxy acrylate resin, 1.5 parts of epoxy curing agent, 22 parts of aluminized glass microsphere and titanium dioxide mixed according to a ratio of 1:2 and 25 parts of methanol, acetone and propylene glycol methyl ether mixed according to a ratio of 2:2: 1.

Comparative example 6

The difference from example 1 is that the composition of the reflective coating is: 14.5 parts of acrylate resin, 28.5 parts of active monomer, 4.5 parts of photoinitiator, 0 part of epoxy acrylate resin, 2.5 parts of epoxy curing agent, 50 parts of aluminized glass microsphere and titanium dioxide mixed according to a ratio of 1:2 and 25 parts of methanol, acetone and propylene glycol methyl ether mixed solvent mixed according to a ratio of 2:2: 1.

Comparative example 7

The difference from example 1 is that the composition of the reflective coating is: 4 parts of acrylate resin, 8.5 parts of active monomer, 1 part of photoinitiator, 70 parts of epoxy acrylate resin, 1.5 parts of epoxy curing agent, 15 parts of aluminized glass microsphere and titanium dioxide mixed according to a ratio of 1:2 and 25 parts of methanol, acetone and propylene glycol methyl ether mixed according to a ratio of 2:2: 1.

The photovoltaic back sheets prepared in the above examples and comparative examples were packaged into photovoltaic modules as follows: the photovoltaic module is prepared by sequentially arranging and laminating glass, a front layer transparent packaging adhesive film, a double-sided battery piece, a rear layer transparent packaging adhesive film and the back plate from top to bottom, wherein the light transmittance of the front layer transparent packaging adhesive film and the rear layer transparent packaging adhesive film is more than 90%, and the battery piece is a double-sided battery piece.

And (4) performance testing:

1. reflectance ratio: the test method refers to CQC3308-2013 backboard authentication technical Specification for photovoltaic module packaging.

2. And the peel strength with EVA: the test method refers to GB/T2790 method for testing the peel strength of adhesive 180. flexible material to rigid material.

3. Adhesion force: the test method refers to GB/T31034 insulating back plate for crystalline silicon solar cell module.

4. Maximum power: the test method selects 72 double-sided modules according to the standard IEC61215 crystalline silicon photovoltaic module for ground-design identification and sizing.

The following table shows the test results of examples and comparative examples.

The test data in the table show that the maximum power of the uncoated reflecting layer in comparative example 1 is significantly lower than that of the coated reflecting layer in the example, which shows that the arrangement of the reflecting layer has a significant promoting effect on fully utilizing solar energy and improving the power of the photovoltaic panel.

Comparative example 2, in which the reflective layer was provided but not subjected to the development setting, had a slightly higher maximum power than that of comparative example 1, but was still lower than that of the other test groups, indicating that the reflective microstructures provided on the reflective layer by the development had an important role in improving the reflectivity.

The reinforcing layer is not arranged in the comparative example 2 and the example 14, the PCT peeling strength is lower, and the reinforcing layer constructed on the surface of the substrate layer and the reflecting layer show excellent PCT peeling strength and PCT adhesive force after being matched for use.

The embodiment shows that the reflection layer with proper thickness is matched with the reinforcing layer, so that the reflectivity and the output power can be effectively improved, and the PCT adhesive force and the PCT peeling strength are good.

From the above description, it can be seen that the above-described embodiments of the present invention achieve the following technical effects: the application discloses photovoltaic is reflective coating for backplate can be directly set up on the substrate layer of backplate with the mode of coating, and the coating that forms is solidification directly on the substrate layer, consequently higher with the adhesion of substrate layer. In addition, the reflective coating for the photovoltaic back panel comprises acrylate resin and epoxy acrylate resin, wherein the acrylate resin is used as light curing resin, so that a cured layer can be formed at a preset position in an exposure and development mode, and the uncured acrylate resin at the exposure position is removed in subsequent development by controlling the exposure degree, so that a rough surface with a multi-angle reflection function is formed, a reflection structure can be formed without a special forming process, and the process is simpler. Meanwhile, the light-reflecting filler in the reflective coating for the photovoltaic back plate also plays a role in light reflection, so that the light reflection efficiency of the photovoltaic back plate is further improved, and the utilization rate of the photovoltaic module to sunlight is further improved.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. The reflective coating for the photovoltaic back plate is characterized by comprising, by weight, 1-30 parts of acrylate resin, 1-40 parts of active monomer, 0.01-10 parts of photoinitiator, 5-60 parts of epoxy acrylate resin, 0.01-10 parts of epoxy curing agent and 10-60 parts of reflective filler.

2. The reflective paint for photovoltaic back panels as claimed in claim 1, wherein the reflective paint for photovoltaic back panels comprises 5 to 25 parts of the acrylate resin, 10 to 40 parts of the active monomer, 1 to 8 parts of the photoinitiator, 20 to 50 parts of the epoxy acrylate resin, 1 to 10 parts of the epoxy curing agent and 20 to 40 parts of the reflective filler, and the acrylate resin is selected from any one or more of resins copolymerized from any one or more of the following monomers:

(meth) acrylic acid, alkyl (meth) acrylates, styrene, benzyl (meth) acrylate; preferably, the alkyl (meth) acrylate is selected from any one of methyl methacrylate, butyl acrylate, isooctyl acrylate, butyl methacrylate and hydroxyethyl methacrylate;

and/or the epoxy acrylate resin is selected from any one or more of bisphenol A epoxy acrylate resin, hydrogenated bisphenol A epoxy acrylate resin, phenolic epoxy acrylate resin and epoxidized oil acrylate resin;

and/or the reactive monomer is selected from any one or more of pentaerythritol triacrylate, pentaerythritol tetraacrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate and trimethylolpropane triacrylate;

and/or the photoinitiator is selected from any one or more of benzophenone, alpha-hydroxy-alpha, alpha-dimethylacetophenone, 1-hydroxycyclohexyl phenyl ketone, alpha-aminoalkylphenyl ketone, 2,4, 6-trimethylbenzoyl diphenyl phosphine oxide, bis (2,4, 6-trimethylbenzoyl) phenyl phosphine oxide, 2- (o-chlorophenyl) -4, 5-diphenyl imidazole dimer and 9-phenylacridine;

and/or the epoxy curing agent is selected from any one or more of aliphatic amine curing agent, aromatic amine curing agent, anhydride curing agent, imidazole curing agent and latent curing agent;

and/or the reflective filler is selected from any one or two of glass beads and titanium dioxide, preferably a mixture of the glass beads and the titanium dioxide with the mass ratio of 1: 10-10: 1, preferably the glass beads are selected from any one or more of galvanized glass beads, silver-plated glass beads and aluminum-plated glass beads, preferably the titanium dioxide is rutile titanium dioxide, and preferably 20-40 parts.

3. The reflective paint for photovoltaic back sheets according to claim 1 or 2, further comprising a solvent selected from any one or more of acetone, butanone, methanol, ethanol, isopropanol, ethylene glycol methyl ether, and propylene glycol methyl ether, preferably further comprising a hydrogen donor selected from one or more of triethylamine, mercaptobenzothiazole, 2- (dimethylamino) ethanol, mercaptobenzimidazole, and the like, a leveling agent, and/or an antifoaming agent.

4. A photovoltaic back plate comprises a substrate layer and a reflecting layer, wherein the reflecting layer is obtained by drying, exposing and developing the reflecting coating for the photovoltaic back plate according to any one of claims 1 to 3, one side of the reflecting layer, which is far away from the substrate layer, is provided with a rough surface, preferably the rough surface is provided with reflecting microstructures, the cross section, parallel to the substrate layer, of each reflecting microstructure is reduced along the direction far away from the substrate layer, further preferably the cross section, perpendicular to the substrate layer, of each reflecting microstructure is conical or trapezoidal, and further preferably the reflecting microstructures are pyramidal.

5. The photovoltaic backsheet according to claim 4, wherein the reflective layer has a thickness of 3 to 20 μm, preferably 5 to 15 μm; preferably, the height of the reflective microstructure corresponds to the thickness of the reflective layer.

6. The photovoltaic back sheet according to claim 4, wherein the thickness of the substrate layer is 100 to 350 μm, and more preferably 200 to 300 μm.

7. The photovoltaic backsheet according to any one of claims 4 to 6, further comprising a reinforcing layer disposed overlying the reflective layer and the substrate layer, wherein the thickness of the reflective layer is greater than or equal to the thickness of the reinforcing layer, and the thickness of the reflective layer differs from the thickness of the reinforcing layer by no more than 8 μm, preferably by no more than 5 μm, and further preferably by no more than 3 μm;

or the reinforcing layer is positioned on the surface of the base material layer, and the reflecting layer is arranged on the surface of the reinforcing layer far away from the base material layer;

the thickness of the reinforcing layer is preferably 3 to 20 μm, and more preferably 5 to 15 μm.

8. The photovoltaic backsheet according to any one of claims 4 to 7, further comprising an air weatherable layer disposed on a surface of the substrate layer remote from the reflective layer, preferably the air weatherable layer has a thickness of 10 to 30 μm.

9. A method for preparing a photovoltaic backsheet according to any one of claims 4 to 8, characterized in that it comprises:

step S1, arranging a reflective coating for the photovoltaic back panel on one surface of the substrate layer to obtain a wet coating;

and step S2, drying, exposing and developing the wet coating to obtain the reflecting layer.

10. The method according to claim 9, wherein the intensity of the exposure is 0.1 to 120mJ/cm²(ii) a Preferably, the developing solution used for developing is any one of a sodium carbonate solution with the weight percentage of 0.1-5 percent, a potassium carbonate solution with the weight percentage of 0.1-5 percent, a sodium hydroxide solution with the weight percentage of 0.1-5 percent and a dilute sodium tetraborate solution with the weight percentage of 0.1-5 percent; preferably, the pH value of the developing solution is between 8 and 12.

11. The method according to claim 9 or 10, wherein after the developing, the method further comprises thermally curing the developed coating to obtain the reflective layer, preferably the thermal curing temperature is 100 to 200 ℃, and preferably the thermal curing time is 3 to 30 min.

12. The production method according to claim 9 or 10, characterized by further comprising:

step S3, covering a reinforcing layer raw material on the reflecting layer and the base material layer to form a reinforcing preparation layer;

step S4, heat-curing the reinforcing preparation layer to obtain the reinforcing layer,

alternatively, before the step S1, the preparation method further includes:

step S01, arranging a reinforcing layer raw material on the substrate layer to form a reinforcing preparation layer;

step S02, heat-curing the reinforcing preparation layer to obtain the reinforcing layer,

the step S1 is to dispose the reflective paint for photovoltaic back sheets on the surface of the base material layer on the reinforcing layer.

13. The production method according to any one of claims 9 to 12, characterized by further comprising:

arranging an air weather-resistant layer raw material on the other surface of the base material layer to obtain an air weather-resistant preparation layer;

and thermally curing the air weather-proof preparation layer to obtain the air weather-proof layer.

14. A photovoltaic cell module comprises a front transparent packaging plate, a front packaging adhesive film, solar cell units, a back packaging adhesive film and a back plate, wherein the solar cell units comprise cells arranged in an array, and the back plate is the photovoltaic back plate of any one of claims 4 to 8.