High-reflectivity reflective film and preparation method thereof

Abstract

The high-reflectivity reflective film comprises a first reflective layer, a microstructure layer, a base material layer, a second reflective layer and an adhesive layer which are sequentially arranged from top to bottom, wherein the micro-structure layer is a microprism structure arranged on the base material layer, the microprism structure is composed of a plurality of microprisms with the same height or more than one microprism with the same height, a V-shaped strip-shaped structure is arranged between every two adjacent microprisms, and the second light reflecting layer is arranged below the base material layer and plays a role in reflecting light again. According to the reflective film, under the action of the microprism structure, the first reflective layer and the second reflective layer, the light conversion efficiency can be effectively improved, the highest reflectivity of the reflective film can reach 92% or above, the second reflective layer is blocked by the base material layer and the microstructure layer and can be better protected, and therefore the service life of the reflective film is prolonged.

Description

Technical Field

[0001] The present application belongs to the field of photovoltaics, and specifically relates to a high-reflectivity reflective film and a preparation method thereof. Background Art

[0002] The photovoltaic industry is green and environmentally friendly, has no environmental pollution, and is a renewable resource. In today's energy shortage situation, solar photovoltaics is a new energy source with broad development prospects.

[0003] The conversion efficiency of existing solar photovoltaic modules is the most important indicator in the photovoltaic industry. The higher the conversion efficiency, the more expensive the photovoltaic module is. At present, in order to increase the conversion efficiency, in addition to improving the battery body, reflective film is added to the surface of the welding strip and reflective film is added in the gap between the battery cells to reflect the unusable light back to the surrounding for reuse, which can increase the conversion efficiency by 2-3%.

[0004] The first type is to apply reflective film on the surface of the soldering tape. Due to the reduction in the width of the soldering tape and the increase in thickness, it has been generally eliminated in the market.

[0005] The second type is to apply reflective film in the gap between the battery cells. A reflective film with a triangular prism structure is applied to the surface of the lower glass or the back panel. However, the reflective strip has a simple structure and only has a reflective layer on the top layer. Aluminum is conventionally used as the reflective layer material, and its reflectivity is 85-88%, and the light reflection utilization rate is insufficient.

[0006] In view of this, how to maximize the use of light irradiation area and improve conversion efficiency has become a technical problem that the industry urgently needs to solve. Summary of the invention

[0007] The object of the present invention is to provide a high reflectivity reflective film and a preparation method thereof to solve the problems raised in the above background technology.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] A high-reflectivity reflective film comprises a first reflective layer, a microstructure layer, a substrate layer, a second reflective layer and an adhesive layer which are arranged in sequence from top to bottom; wherein the microstructure layer is a microprism structure arranged on the substrate layer, the microprism structure is composed of a plurality of microprisms of equal height or one high and many low, a V-shaped strip structure is arranged between two adjacent microprisms, and the second reflective layer is arranged below the substrate layer to reflect light again.

[0010] To implement the above technical solution, the reflectivity of the reflective film can reach more than 95% by setting the micro-prism structure in coordination with the first reflective layer and the second reflective layer.

[0011] As a preferred solution of the present application, the substrate layer includes one of polycarbonate, polyethylene terephthalate, polyamide resin, polystyrene, polyethylene and polymethyl methacrylate.

[0012] The above technical solution is realized, and the device has excellent flexibility and lightness.

[0013] As a preferred solution of the present application, the microprism is in the form of a triangular prism, the cross section of the triangular prism is set to be a triangle, and all vertex angles of the microprism are set to be 60-145°.

[0014] The above technical solution is implemented to facilitate the reflection of light.

[0015] As a preferred solution of the present application, the extension direction of the V-shaped strip structure is in an up and down shaking shape or a straight line shape.

[0016] To implement the above technical solution, the shaking trajectory is one of sine / cosine, wave, and arc, the shaking period is 20-5000μm, and the shaking amplitude is 0.5-5μm.

[0017] As a preferred solution of the present application, the V-shaped height of the cross section of the micro-prism structure is set to 10-500μm, and the distance between the two peaks is set to 15-3000μm; the cross-sectional height ratio of two adjacent prism V-shaped strip structures is between 1:0.6 and 1, and cycles at a certain period.

[0018] As a preferred solution of the present application, the first light reflecting layer and the second light reflecting layer are configured as aluminum-plated layers or silver-plated layers.

[0019] The above technical solution is implemented to increase the reflectivity of the reflective film.

[0020] As a preferred solution of the present application, the thickness of the first light reflecting layer and the second light reflecting layer is set to 0.05-1.0 μm.

[0021] The above technical solution is realized, which is light and thin, reduces the weight of the reflective film and improves the adhesion of the back adhesive layer.

[0022] As a preferred solution of the present application, the adhesive layer is connected to the surface of the glass layer or the back panel layer.

[0023] To implement the above technical solution, the adhesive layer is bonded to the surface of the glass layer or the back panel layer by means of heat curing and pressurization.

[0024] As a preferred solution of the present application, the reflective film is in a roll shape, and its width after cutting is greater than or equal to the width of the gap between the battery cells.

[0025] A method for preparing a high-reflectivity reflective film comprises the following steps:

[0026] Step 1: Making a negative mold for forming a microprism structure;

[0027] Step 2: using UV curing or thermal curing methods, engraving on the surface of the negative mold, and curing on the surface of the substrate layer to obtain a corresponding micro-prism structure;

[0028] Step 3: Obtaining a first reflective layer on the surface of the micro-prism structure by chemical plating, evaporation, spraying, etc.;

[0029] Step 4: Repeat the steps of step 3, and use the same method on the lower surface of the substrate layer to obtain a second reflective layer on the lower surface of the substrate layer by chemical plating, evaporation, spraying, etc.;

[0030] Step 5: The adhesive layer is obtained by cast co-extrusion treatment on the surface of the second reflective layer, and then the reflective film product corresponding to the demand is obtained by slitting.

[0031] As a preferred solution of the present application, the material of the female mold is set to copper, nickel or chromium.

[0032] Compared with the prior art, the beneficial effects of this application are:

[0033] The reflective film provided by the present invention can effectively improve the reflective efficiency of the reflective film through the first reflective layer and the second reflective layer under the effect of the micro-prism structure, and its reflectivity can reach up to more than 92%. In addition, the second reflective layer is blocked by the substrate layer and the micro-structure layer, and can be better protected, thereby improving the service life of the reflective film. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a schematic diagram of the structure involved in this application.

[0035] In the figure: a first light reflecting layer 1, a microstructure layer 2, microprisms 201, a V-shaped strip structure 202, a substrate layer 3, a second light reflecting layer 4, an adhesive layer 5, and glass 6. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] Embodiment:

[0038] A high reflectivity reflective film, reference Figure 1, including a first reflective layer 1, a microstructure layer 2, a substrate layer 3, a second reflective layer 4, and an adhesive layer 5 arranged in sequence from top to bottom; wherein, the microstructure layer 2 is a microprism structure arranged on the substrate layer 3. In this embodiment, the microprism structure is composed of a number of microprisms with the same height, and the microprisms are parallel to each other in the extending direction. The first reflective layer 1 is an aluminized layer plated on the surface of the microprisms, and the second reflective layer 4 is an aluminized layer plated below the substrate layer 3, which plays the role of reflecting light again. In other embodiments, the microprism structure can be composed of a number of microprisms 201 with one high and multiple lows, and the first reflective layer 1 and the second reflective layer 4 can also use coating / plating layers such as metal materials and inorganic materials.

[0039] Refer to Figure 1 , and a V-shaped strip structure 202 is arranged between two adjacent microprisms 201. In this embodiment, the extending direction of the V-shaped strip structure 202 is in an up-and-down jitter shape, and the jitter trajectory is in a wavy shape, with a jitter period of 20 - 5000 μm and a jitter amplitude of 0.5 - 5 μm. In other embodiments, the extending direction of the V-shaped strip structure 202 can be in a straight line shape; its jitter trajectory can be in one of the sine / cosine or arc shapes.

[0040] Refer to Figure 1 , in this embodiment, the cross-sectional V-shaped height of the microprism structure is set at 80 μm, and the distance between two peaks is set at 500 μm; the cross-sectional height ratio of the V-shaped strip structure 202 between two adjacent prisms is 1:0.6. In other embodiments, the cross-sectional V-shaped height of the prism structure can be set at 10 - 500 μm, and the distance between two peaks can be set at 15 - 3000 μm; and the cross-sectional height ratio of the V-shaped strip structure 202 between two adjacent prisms is between 1:0.6 and 1, and circulates at a certain period.

[0041] In this embodiment, the V-shaped strip structure 202 is obtained by UV curing. In other embodiments, the V-shaped strip structure 202 can also be formed by polymer materials.

[0042] In this embodiment, the first reflective layer 1 and the second reflective layer 4 are obtained by methods including but not limited to electroless plating, evaporation plating, and spraying plating.

[0043] Refer to Figure 1 , in this embodiment, the microprism 201 is in a triangular prism shape, the cross-section of the triangular prism is set as a triangle, and all the vertex angles of the microprism 201 are set at 120°. In other embodiments, the triangle can be an isosceles triangle, and the vertex angle of the microprism 201 can be set at 60 - 145.

[0044] Refer to Figure 1 , in this embodiment, the vertex angle of the microprism 201 can be set as a sharp angle. In other embodiments, the vertex angle of the microprism 201 can be set as a rounded angle (0.5 < R < 5 mm) or wavy.

[0045] Reference Figure 1 In order to increase the flexibility and lightness of the reflective film. In this embodiment, the substrate layer 3 is made of polycarbonate. In other embodiments, the substrate layer 3 can be made of one of polyethylene terephthalate, polyamide resin, polystyrene, polyethylene or polymethyl methacrylate.

[0046] Reference Figure 1 In order to increase the lightness of the reflective film, in this embodiment, the thickness of the first reflective layer 1 is set at 0.05 μm, and the thickness of the second reflective layer 4 is set at 0.01 μm. In other embodiments, the thickness of the first reflective layer 1 and the second reflective layer 4 can be set between 0.05-1.0 μm.

[0047] Reference Figure 1 In this embodiment, the extending direction of all microprisms 201 forms an angle of 15° with the direction of the substrate layer 3. In other embodiments, the extending direction of the microprisms 201 and the direction of the substrate layer 3 may form an angle of 0-45°.

[0048] Reference Figure 1 In this embodiment, the adhesive layer 5 is bonded to the surface of the glass layer or the back panel layer by means of heat curing and pressurization.

[0049] In order to facilitate the use of the reflective film, in this embodiment, the reflective film is in a roll shape, and its width after cutting is greater than or equal to the width of the gap between the battery cells.

[0050] The method for preparing a high reflectivity reflective film is as follows: firstly, a negative mold for forming a micro-prism structure is prepared;

[0051] Then, UV curing or thermal curing is used to perform engraving on the surface of the negative mold, and the corresponding micro-prismatic structure is obtained by curing on the surface of the substrate layer 3; then, the first reflective layer 1 and the second reflective layer 4 are obtained on the surface of the micro-prismatic structure and the lower surface of the substrate layer 3 by chemical plating, evaporation, spraying and other methods; finally, the surface of the second reflective layer 4 is treated by cast co-extrusion to obtain the adhesive layer 5, and then the reflective film product corresponding to the requirements is obtained by slitting.

[0052] In the present embodiment, the material of the female mold is copper. In other embodiments, the material of the female mold can be nickel or chromium.

[0053] In this embodiment, the angle of the extension direction of the micro-prismatic structure on the female mold is opposite to that on the finished product, that is, -15°. In other embodiments, the angle of the extension direction of the micro-prismatic structure is 0° to -45° with respect to the finished product.

[0054] Specifically, in actual use, the reflective film is applied to the lower glass surface in advance by heat pasting to form a grid-like space, and the reserved position is the placement position of the battery cell;

[0055] Prepare the photovoltaic upper glass, upper EVA layer (ethylene-vinyl acetate copolymer), series-connected cells, lower EVA layer, and lower glass. Stack in the above order, put the laid materials into the laminator for high-temperature vacuum lamination, trim the excess EVA and backplane at the edge after lamination, install the aluminum frame and wire box after the laminated parts cool down, and finally test a series of data such as component power.

[0056] For this reflective film photovoltaic module with a micro-prismatic structure, the incident light can be reflected on the reflective film. Since the refractive index of glass is greater than that of air, the reflected light can be totally reflected at the interface between glass and air. The totally reflected light will finally enter the battery cell again, thereby increasing the conversion efficiency.

[0057] The use of a reflective film with a regular high and low micro-prismatic structure can block the reflected light source on the edge of the battery cell from reflecting outside the battery cell, and further reflect it back to the battery cell for reuse, thereby improving its conversion efficiency.

[0058] The extension direction of the microprism is 45° to the direction of the substrate, that is, light sources from different lighting directions can be reflected to the surrounding cells, so that conventional components can be used in areas with different lighting directions, increasing the versatility of the reflective film. Through a large amount of test data comparison and analysis, there is a 3% to 4% power gain on conventional components, and the highest reflectivity can reach more than 92%.

[0059] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A high reflectivity reflective film, characterized in that: The invention comprises a first light reflecting layer (1), a microstructure layer (2), a substrate layer (3), a second light reflecting layer (4) and an adhesive layer (5) which are arranged in sequence from top to bottom; wherein the microstructure layer (2) is a microprism structure arranged on the substrate layer (3), the microprism structure is composed of a plurality of microprisms (201) of equal height or one high and many low, and a V-shaped strip structure (202) is arranged between two adjacent microprisms (201); the second light reflecting layer (4) is arranged below the substrate layer (3) to play a role in reflecting light again.

2. A high reflectivity reflective film according to claim 1, characterized in that: The substrate layer (3) comprises one of polycarbonate, polyethylene terephthalate, polyamide resin, polystyrene, polyethylene or polymethyl methacrylate.

3. The high reflectivity reflective film according to claim 1, characterized in that: The microprism (201) is in the form of a triangular prism, the cross section of the triangular prism is set to be a triangle, and all vertex angles of the microprism (201) are set to be 60-145 degrees.

4. The high reflectivity reflective film according to claim 1, characterized in that: The V-shaped strip structure (202) extends in a direction that is in an up-and-down shaking shape or a straight line shape.

5. The high reflectivity reflective film according to claim 1, characterized in that: The V-shaped height of the cross section of the micro-prism structure is set at 10-500 μm, and the distance between the two peaks is set at 15-3000 μm; The cross-sectional height ratio of the V-shaped strip structure (202) between two adjacent microprisms (201) is between 1:0.6 and 1.

6. The high reflectivity reflective film according to claim 1, characterized in that: The first light reflecting layer (1) and the second light reflecting layer (4) are configured as aluminum-plated layers or silver-plated layers.

7. The high reflectivity reflective film according to claim 1, characterized in that: The thickness of the first light reflecting layer (1) and the second light reflecting layer (4) is set at 0.05-1.0 μm.

8. The high reflectivity reflective film according to claim 1, characterized in that: The adhesive layer (5) is connected to the surface of the glass layer or the back panel layer.

9. A method for preparing a high reflectivity reflective film, characterized in that: The following steps are involved: Step 1: Making a negative mold for forming a microprism structure; Step 2: using UV curing or thermal curing methods to engrave on the surface of the negative mold, and curing on the surface of the substrate layer (3) to obtain a corresponding micro-prism structure; Step 3: Obtaining a first reflective layer (1) on the surface of the micro-prism structure by chemical plating, evaporation, spraying, etc.; Step 4: Repeat the steps of step 3, and use the same method on the lower surface of the substrate layer (3) to obtain a second reflective layer (4) on the lower surface of the substrate layer (3) by chemical plating, evaporation, spraying, etc.; Step 5: The adhesive layer (5) is obtained by cast co-extrusion treatment on the surface of the second reflective layer (4), and then the reflective film product corresponding to the requirements is obtained by slitting.

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