CN218482256U

CN218482256U - Weather-resistant film for solar cell back plate

Info

Publication number: CN218482256U
Application number: CN202222869538.9U
Authority: CN
Inventors: 吴培服; 吴迪; 孙化斌; 臧辉
Original assignee: Jiangsu Shuangxing Color Plastic New Materials Co Ltd
Current assignee: Jiangsu Shuangxing Color Plastic New Materials Co Ltd
Priority date: 2022-10-29
Filing date: 2022-10-29
Publication date: 2023-02-14
Anticipated expiration: 2032-10-29

Abstract

The application discloses a weather-resistant film for a solar cell back plate, which comprises a PVDF film (1), wherein a plurality of saw tooth stripes (11) which are arranged in parallel at equal intervals and have isosceles triangle-shaped sections are formed on the surfaces of two sides of the PVDF film (1), and the minimum gap between every two adjacent saw tooth stripes (11) is 0-5 mu m; a white protective layer (12) is formed on the surface of the sawtooth stripe (11) facing one side of the solar cell piece through vacuum sputtering, and a black protective layer (13) is formed on the surface of the sawtooth stripe (11) far away from one side of the solar cell piece through vacuum sputtering; one side of the PVDF film (1) with the white protective layer (12) is bonded with a layer of heat-conducting metal film (2). The weather-resistant film for the solar cell back plate can obviously improve the bonding property to avoid layering under the condition of having the sawtooth stripes, is excellent in heat conduction property, can increase the contact angle of the outer surface, and improves the self-cleaning capability.

Description

Weather-resistant film for solar cell back plate

Technical Field

The application relates to a weather-resistant film for a solar cell back plate.

Background

A common structure of solar cell back sheets is a TPT structure, where T generally refers to polyvinyl fluoride (PVF) film and P generally refers to polyethylene terephthalate (PET) film, i.e., PVF/PET/PVF structure. The main function of PVF films is weather resistance, but they are relatively expensive and have low surface energy, low surface energy and are easily delaminated.

CN 103563096B discloses a back sheet for a solar cell module, comprising a polyester film layer and a fluorine coating layer coating at least one surface of the polyester film layer. The back sheet is formed on an upper surface of the polyester film layer, and includes a polyethylene film layer attached to an Ethylene Vinyl Acetate (EVA) sheet of the solar cell module. In this prior art, it has been repeatedly mentioned that the conventional fluorine-containing film has poor adhesion, and the weather-resistant fluorine-containing film covering the backsheet has insufficient adhesion to the base material or the EVA sheet of the solar cell module, and therefore, even if the fluorine-containing film has excellent weather resistance, the barrier property is poor due to the weak adhesion, and the moisture-proof performance is poor. The prior art adopts the fluorine coating coated on the outer side to reduce the cost and improve the adhesive force, but the effective weather-resistant components in the coating are less, and the coating is difficult to resist the erosion of wind and sand for a long time and is easy to fall off because the coating is positioned on the outermost side of the back plate. In addition, in order to reduce the cost and improve the adhesion, the prior art also stresses that the coating cannot be too thick, so that the weather resistance is obviously weaker than that of the fluorine-containing thin film under the condition of the same thickness, if a better protection effect is achieved, the coating thickness can only be increased, the thicker coating can cause the capability of bearing the thermal stress change of the back plate to be reduced, and the coating is easier to fall off under the cold and hot alternating action.

Disclosure of Invention

The technical problem to be solved by the present application is to provide a weatherable film for solar cell back sheets to reduce or avoid the aforementioned problems.

In order to solve the technical problem, the application provides a weather-resistant film for a solar cell back plate, which comprises a PVDF film, wherein a plurality of equally-spaced parallel saw tooth stripes with isosceles triangle-shaped sections are formed on the surfaces of two sides of the PVDF film, and the minimum gap between every two adjacent saw tooth stripes is 0-5 μm; a white protective layer is formed on the surface of the sawtooth stripe facing one side of the solar cell piece through vacuum sputtering, and a black protective layer is formed on the surface of the sawtooth stripe far away from one side of the solar cell piece through vacuum sputtering; one side of the PVDF film with the white protective layer is bonded with a layer of heat-conducting metal film.

Preferably, the white protective layer and the black protective layer have a thickness of 1 to 3 μm, respectively.

Preferably, the sawtooth stripes on the two side surfaces of the PVDF film are mutually and vertically arranged; the included angle between the length direction of the sawtooth stripes and the four rectangular sides of the PVDF film is 45 degrees.

Preferably, the thickness of the heat conductive metal film is 8 to 16 μm.

The utility model provides a resistant time membrane can increase the area of contact with the adhesive through the sawtooth stripe that sets up to increase resistant time membrane's whole adhesive force, avoided the easy problem of delaminating of resistant time membrane. The weather-resistant film for the solar cell back plate can obviously improve the bonding property to avoid layering under the condition of having the sawtooth stripes, is excellent in heat conduction property, can increase the contact angle of the outer surface, and improves the self-cleaning capability.

Drawings

The drawings are only for purposes of illustrating and explaining the present application and are not to be construed as limiting the scope of the present application.

Fig. 1 shows a schematic cross-sectional view of a weatherable film for a solar cell back sheet according to one embodiment of the present application.

Fig. 2 is a schematic view showing the structure of a PVDF film of a weatherable film for a solar cell back sheet according to another embodiment of the present application.

Detailed Description

In order to more clearly understand the technical features, objects, and effects of the present application, embodiments of the present application will now be described with reference to the accompanying drawings. Wherein like parts are given like reference numerals.

The application provides a weather-resistant film for a solar cell back plate, as shown in fig. 1, the weather-resistant film comprises a PVDF film 1, wherein a plurality of equally spaced and parallel saw tooth stripes 11 with isosceles triangle-shaped cross sections are formed on the surfaces of two sides of the PVDF film 1, a white protective layer 12 is formed on the surface of the saw tooth stripe 11 facing one side of a solar cell, and a black protective layer 13 is formed on the surface of the saw tooth stripe 11 far away from one side of the solar cell through vacuum sputtering.

Wherein, the PVDF mass content in the PVDF film is more than or equal to 90 percent, and in order to improve the performance of the PVDF film, an ultraviolet absorber, an abrasion-resistant filler and the like can be added. It is preferable that the both side surfaces of the PVDF film 1 are formed with the sawtooth stripes 11 which are identical. The weatherable film is shown in exaggerated size scale for ease of viewing and understanding, with the actual sawtooth streaks being relatively fine in size and the surface having only a small texture that is not readily noticeable. In one embodiment, the maximum thickness of the PVDF membrane 1 is 20 to 30 μm.

The existing PVDF weather-resistant film has the problems of easy delamination due to low surface energy and insufficient adhesive force. In order to overcome this technical problem, the present application forms a sawtooth stripe on the surface of the PVDF film, by which the contact area with the adhesive 3 (described in further detail later) can be increased, for example, when the tip angle of the isosceles trapezoid of the sawtooth stripe is 60 degrees, the sawtooth stripe can double the surface area, thereby increasing the overall adhesion of the PVDF film and avoiding the problem that the weather-resistant film is easily delaminated.

It should be noted that, in practice, only the sawtooth stripes need to be arranged on the inner side of the PVDF film to improve the overall adhesion of the weatherable film, but the stripes are very tiny and difficult to observe, and for the convenience of assembly operation, the inventor chooses to simultaneously form the same sawtooth stripes on both surfaces of the PVDF film, so that both sides can be coated with the film, and the application range of the weatherable film can be improved. The inventor thinks that the originally located sawtooth stripes on the outer side do not assume any effect, however, in the actual laying experiment process, the inventor finds that if the scale of the sawtooth stripes formed on the surface of the PVDF film is smaller than a certain range, the PVDF film can play a self-cleaning effect, the adhesion force of dust on the surface of the weather-resistant film can be reduced, and rainwater can easily flush the adhered dust. For example, in one embodiment, it is preferable that the isosceles triangle of the sawtooth stripe 11 has a length of a base of 5 to 10 μm, an apex angle of 45 to 135 degrees and a height of 5 to 10 μm, and a minimum gap between adjacent sawtooth stripes 11 is 0 to 5 μm. The same sawtooth stripes are formed on the two side surfaces of the PVDF film, so that the manufacturing cost can be reduced, and the sawtooth stripes in the size range can be selected to obtain better bonding performance on the inner side and form excellent dust adsorption resistance on the outer side. In addition, the surface area of the outer surface is further improved by the sawtooth stripes on the outer side, the heat dissipation area is increased, and the overall heat dissipation performance of the weather-resistant film is further improved.

Further, in order to improve the adhesion of the PVDF film and avoid delamination, the included angle between the length direction of the saw-tooth stripes and the four rectangular sides of the weatherable film is selected to be 45 degrees, as shown in fig. 2. In general, the solar cell panel is usually designed to be rectangular, four sides are perpendicular to each other, and if the length direction of the sawtooth stripes is perpendicular to one pair of rectangular sides of the weatherable film, the other pair of rectangular sides will be parallel to the length direction of the sawtooth stripes. Since the rigidity in the longitudinal direction and the rigidity in the width direction of the zigzag stripes are different, the expansion rates are also different, which causes the weather-resistant film to easily warp and delaminate at one pair of rectangular sides. This application turns to the direction of sawtooth stripe and is 45 degrees contained angles with four rectangle limits, then because the rigidity difference of equidirectional not that the sawtooth stripe arouses can tend to averagely to the proportion of four rectangle limit diffusion, therefore can avoid the problem of the resistant membrane delaminating of waiting of causing because setting up of sawtooth stripe, further improved the structural performance of resistant membrane.

In addition, when the same saw-tooth stripes are formed on both sides, if the saw-tooth stripes on both sides are oriented in the same direction, that is, the saw-tooth stripes on both sides are arranged in parallel to each other in the longitudinal direction, different thermal expansion coefficients on both sides are concentrated in the same direction, and thus, stress concentration may occur, which may cause delamination. In order to avoid the delamination problem caused by the consistent direction of the sawtooth stripes on both sides, the present application further proposes a special design, in which the sawtooth stripes 11 on both sides of the PVDF film 1 are arranged perpendicular to each other, so as to avoid the delamination problem caused by the formation of a profit bias in one direction at the same time.

In addition, in order to avoid the problem that the back plate in the prior art is too large in thickness and difficult to apply to the field of flexible solar cells with larger flexibility requirements, the white protective layer 12 and the black protective layer 13 are formed on the sawtooth stripes through a vacuum sputtering mode on the basis of the PVDF film with the sawtooth stripe structure, and the binding force of the sputtering layer formed through vacuum sputtering is far greater than that of adhesion, so that the protection function can be achieved through very thin thickness. For example, the white protective layer 12 may be composed of titanium dioxide; the black protective layer 13 may be composed of silicon carbide. Preferably, the white protective layer 12 and the black protective layer 13 have a thickness of 1 to 3 μm, respectively.

The white protective layer 12 can provide a good light reflection function, and can reflect light transmitted from the front surface of the solar cell back to the solar cell as much as possible, thereby improving the light conversion efficiency. Meanwhile, the white protective layer 12 is integrally sputtered on the surface of the sawtooth stripes, so that an additional white polyethylene film layer is not needed, the structure of the weather-resistant film is simplified, and the thickness of the film layer is reduced.

The black protective layer 13 is also a very thin sputtered layer, and can be used to improve the wear resistance and the ability of the weather-resistant film to resist wind and sand erosion. In addition, the black protection layer 13 has better heat radiation capability, so that heat absorbed by the back plate can be radiated as soon as possible, and the temperature of the solar cell module can be reduced. Meanwhile, the mode of sputtering the layer not only improves the bonding force, but also reduces the additional film layer structure and reduces the thickness and the cost.

Further, for the heat-sinking capability of better improvement backplate, this application has one deck heat conduction metal film 2 at PVDF membrane 1 one side that has white protective layer 12, for example can bond heat conduction metal film 2 and PVDF membrane 1 as an organic whole through suitable adhesive 3, through heat conduction metal film 2, can conduct the heat that the backplate absorbed for PVDF membrane 1 to through the surface area that the sawtooth stripe in the outside increases, go out the heat high-efficient radiation. In one embodiment, the heat conductive metal film 2 may be a metal aluminum foil with a thickness of 8-16 μm, and the adhesive 3 may be a commercially available EVA adhesive or acrylic adhesive with a maximum thickness of 15-20 μm.

The method for producing the weather-resistant film for a solar battery back sheet according to the present invention is described in further detail below with reference to the drawings. Specifically, the preparation method comprises the following steps:

first, a PVDF membrane is provided. The PVDF film can be a PVDF film with the thickness of 20-30 μm sold in the market, or a PVDF raw material particle with the mass content of more than or equal to 90 percent is added with an ultraviolet absorber, an abrasion-resistant filler and the like, and the PVDF film is formed by melt co-extrusion and then two-way stretching.

Then, a plurality of equally spaced saw-tooth stripes 11 having isosceles triangle-shaped cross sections are formed on both side surfaces of the PVDF film by hot press molding. For example, the cured zigzag stripes 11 can be obtained on the PVDF film by using two rollers arranged one above the other and having a pattern matching the shape of the zigzag stripes, passing the heated PVDF film between the two rollers, and then air-cooling or water-cooling the PVDF film. Wherein the longitudinal directions of the patterns matching with the shape of the sawtooth stripes on the surfaces of two rollers which are arranged up and down are arranged perpendicular to each other, so that the sawtooth stripes 11 which are perpendicular to each other can be formed on the surfaces of both sides of the PVDF film. For example, the pattern direction of the two roller surfaces forms an angle of 45 degrees with the advancing direction of the PVDF film, so that the sawtooth stripes 11 forming an angle of 45 degrees with the four rectangular sides of the weather-resistant film can be formed.

Thereafter, a white protective layer 12 is formed on the sawtooth pattern 11 on one side by vacuum sputtering, and a black protective layer 13 is formed on the sawtooth pattern 11 on the other side by vacuum sputtering. For example, a layer of titanium dioxide having a thickness of 1 to 3 μm may be formed on the sawtooth stripes 11 on one side by vacuum sputtering to form a white protective layer 12; a black protective layer 13 is formed by vacuum sputtering of silicon carbide having a thickness of 1-3 μm on the sawtooth stripes 11 on the other side, and since the protective layer is formed to be relatively very thin, the protective layer is not shown in fig. 2, and the

protective layers

12 and 13 in fig. 1 are enlarged for easy understanding.

Finally, a heat conductive metal film 2 is adhered to the side having the white protective layer 12, thereby forming the weather-resistant film. For example, an acrylic adhesive with a thickness of 15-20 μm may be coated on the side having the white protective layer 12, the surface may be scraped off, and then a metal aluminum foil with a thickness of 8-16 μm may be bonded.

Examples 1 to 6

And preparing the weather-resistant film for the solar cell back plate according to the following parameters.

In examples 1 to 3, the included angles between the sawtooth stripes and the rectangular sides of the weatherable film are both 45 degrees, and in examples 4 to 6, the included angles between the sawtooth stripes and the rectangular sides of the weatherable film are both 0/90 degrees, that is, the included angles between the sawtooth stripes and one pair of rectangular sides are 0 degree, and the included angles between the sawtooth stripes and the other pair of rectangular sides are 90 degrees. The white protective layer is made of titanium dioxide; the black protective layer is made of silicon carbide.

Comparative examples 1 to 6

Comparative examples 1 to 6 used PVDF films without sawtooth stripes and bonded heat conductive metal films as weather resistant films, with the following parameters. In examples 1 to 6 and comparative examples 1 to 6, an EVA adhesive was used, and a metal aluminum foil was used as a heat conductive metal film.

The weatherable films of examples 1 to 6 and comparative examples 1 to 6 were respectively adhered to the surface of a 188 μm PET support base film, and the parametric properties of the examples in which the weatherable film was measured were compared as follows.

As can be seen from the comparison of performance parameters of the embodiment, the weather-resistant film for the solar cell back plate can obviously improve the adhesive property and avoid layering under the condition of having the sawtooth stripes, has excellent heat-conducting property, can increase the contact angle of the outer surface, improves the self-cleaning capability and has excellent dust-resistant adsorbability.

It should be appreciated by those skilled in the art that while the present application is described in terms of several embodiments, not every embodiment includes only a single embodiment. The description is thus given for clearness of understanding only, and it is to be understood that all matters in the embodiments are to be interpreted as including all technical equivalents which are encompassed by the claims and are to be interpreted as combined with each other in a different embodiment so as to cover the scope of the present application.

The above description is only illustrative of the present invention and is not intended to limit the scope of the present invention. Any equivalent changes, modifications and combinations that may be made by those skilled in the art without departing from the spirit and principles of the present application shall fall within the scope of the present application.

Claims

1. The weather-resistant film for the solar cell back plate comprises a PVDF film (1), and is characterized in that a plurality of saw tooth stripes (11) which are arranged in parallel at equal intervals and have isosceles triangle-shaped sections are formed on the surfaces of two sides of the PVDF film (1), and the minimum gap between every two adjacent saw tooth stripes (11) is 0-5 mu m; a white protective layer (12) is formed on the surface of the sawtooth stripe (11) facing one side of the solar cell piece through vacuum sputtering, and a black protective layer (13) is formed on the surface of the sawtooth stripe (11) far away from one side of the solar cell piece through vacuum sputtering; one side of the PVDF film (1) with the white protective layer (12) is bonded with a layer of heat-conducting metal film (2).

2. The weatherable film according to claim 1, wherein the white protective layer (12) and the black protective layer (13) each have a thickness of 1 to 3 μm.

3. The weatherable film according to claim 2, characterized in that the sawtooth striations (11) of the two lateral surfaces of the PVDF film (1) are arranged perpendicular to each other; the included angles between the length direction of the sawtooth stripes (11) and the four rectangular sides of the PVDF film (1) are 45 degrees.

4. The weatherable film according to claim 3, characterized in that the thickness of the thermally conductive metal film (2) is 8-16 μm.