Composite polyester backboard and flexible photovoltaic module

Abstract

The utility model relates to the technical field of photovoltaic packaging, and discloses a composite polyester backboard and a flexible photovoltaic assembly. The composite polyester backboard comprises a first base film and a second base film which are sequentially laminated from bottom to top, an outer weather-proof coating is arranged on the lower surface of the first base film, an inner bonding layer is arranged on the upper surface of the second base film, and the inner bonding layer is bonded on the lower surface of a photovoltaic cell; a composite adhesive layer is arranged between the first base film and the second base film; the first base film and the second base film are polyester base films, and the composite adhesive layer is an epoxy acrylic adhesive layer. The composite polyester backboard has the advantages of high strength, weather resistance, aging resistance, good cohesiveness with a packaging adhesive film, small thermal shrinkage and low production cost, avoids the problem of edge warping of the flexible photovoltaic module, reduces the power attenuation of the flexible photovoltaic module after a hail test, and is helpful for improving the packaging reliability and long-term power generation power of the flexible photovoltaic module.

Description

TECHNICAL FIELD

[0001] The utility model relates to photovoltaic packaging technical field, concretely relates to a kind of composite polyester back sheet and flexible photovoltaic module. BACKGROUND

[0002] With the rapid rise of distributed photovoltaic power station, flexible photovoltaic module (such as shown in the publication CN220856590U) is favored by the market due to its strong adaptability, can be attached to various curved surface. However, the traditional flexible photovoltaic module has obvious short board in mechanical strength, load, hail test performance, which will lead to the difficulty of long-term maintenance of power generation power of flexible photovoltaic module in harsh outdoor environment for a long time, that is, will lead to the power attenuation of flexible photovoltaic module, and further limit the service life of photovoltaic module, and restrict the expansion of its application scene.

[0003] To overcome the above-mentioned defects of traditional flexible photovoltaic module, the existing flexible photovoltaic module is usually matched with glass fiber reinforced back sheet (such as the existing PP glass fiber reinforced white back sheet shown in the publication CN117799271A), or like the front plate packaging structure shown in the publication CN220856590U: double or multi-layer double-sided bonding transparent front plate is arranged to improve the mechanical strength, hail test performance and other performances of flexible photovoltaic module. However, if the flexible photovoltaic module is matched with glass fiber reinforced back sheet to improve its mechanical strength, its price will be multiplied by several times, which greatly improves the production cost of back sheet and flexible photovoltaic module. Moreover, if the existing PP glass fiber reinforced white back sheet is matched with transparent polyester front plate (such as transparent PET front plate) to make flexible photovoltaic module, the flexible photovoltaic module is also prone to warping problem. In addition, the arrangement of double or multi-layer double-sided bonding transparent front plate will also increase the production cost of front plate and flexible photovoltaic module. SUMMARY

[0004] The utility model aims at overcoming the deficiencies of prior art, and provides a kind of composite polyester back sheet and flexible photovoltaic module.

[0005] Based on this, the utility model discloses a kind of composite polyester back sheet,

[0006] First base film and second base film are sequentially stacked from bottom to top;The lower surface of the first base film is provided with an outer weather-resistant coating, and the upper surface of the second base film is provided with an inner adhesive layer, and the inner adhesive layer is bonded to the lower surface of the photovoltaic cell piece;

[0007] Composite adhesive layer is provided between the first base film and the second base film;The first base film and the second base film are polyester base film, and the composite adhesive layer is epoxy acrylic adhesive layer.

[0008] Preferably, the outer weather-resistant coating is a fluorosilicone-modified polyester weather-resistant coating, a fluorosilicone weather-resistant coating, a fluorocarbon weather-resistant coating, a silicone weather-resistant coating or a polyester weather-resistant coating; the thickness of the outer weather-resistant coating is 10-25 μm.

[0009] Further preferably, the outer weather-resistant coating is a self-cleaning weather-resistant coating (the water contact angle of the self-cleaning weather-resistant coating is ≥110°); the thickness of the outer weather-resistant coating is 15-20 μm.

[0010] Preferably, the first base film and the second base film are hot-pressed and bonded by the composite adhesive layer, and the thickness of the composite adhesive layer is 10-60 μm.

[0011] Further preferably, the thickness of the composite adhesive layer is 30-50 μm.

[0012] Preferably, the first base film and the second base film are both polyethylene terephthalate base films (i.e., PET base films); the thickness of the first base film and the second base film is both 300-400 μm.

[0013] Further preferably, the first base film and the second base film are both polyethylene terephthalate base films after corona treatment; the thickness of the first base film and the second base film is both 340-360 μm.

[0014] Preferably, the inner bonding layer is an adhesive coating, and the thickness of the adhesive coating is 5-15 μm.

[0015] Further preferably, the inner bonding layer is a polyester adhesive coating, and the thickness of the polyester adhesive coating is 8-12 μm.

[0016] The utility model discloses still a kind of flexible photovoltaic module, including composite polyester backsheet, first encapsulation adhesive layer, photovoltaic cell, second encapsulation adhesive layer and transparent polyester front plate (such as transparent PET front plate) which are sequentially laminated from bottom to top;The composite polyester backsheet is the composite polyester backsheet described above in the contents of the utility model.

[0017] Compared with the structure of the existing flexible photovoltaic module, the flexible photovoltaic module uses the composite polyester backboard of the utility model in structure, and is matched with the high-weather-resistant transparent polyester front plate, so that the mechanical strength, impact resistance, weather resistance and aging resistance of the photovoltaic module are improved, the warping problem of the existing flexible photovoltaic module caused by the heat shrinkage after lamination due to the use of the PP glass fiber reinforced backboard and other plate materials on the market is effectively improved, and the following defects of the existing backboard (such as the existing PET backboard) are solved: insufficient mechanical strength, and the inability to simultaneously meet the requirements of low cost, excellent surface stain resistance and excellent (such as the encapsulation adhesive film of EVA) adhesion performance. The composite polyester backboard and the photovoltaic module thereof have wide application potential in distributed photovoltaic power stations, environmentally-friendly buildings and other fields.

[0018] Compared with the prior art, the utility model at least has the following beneficial effects:

[0019] In the composite polyester backboard, the outer weather-resistant coating effectively improves the high-weather-resistant performance and excellent aging performance of the composite polyester backboard; the inner adhesive layer enhances the interfacial bonding force between the composite polyester backboard and the encapsulation adhesive film such as EVA; the epoxy acrylic adhesive layer (i.e. the composite adhesive layer) can realize high-adhesion composite between the first base film (which is a polyester base film) and the second base film (which is a polyester base film) under low-temperature hot pressing, effectively avoids the heat shrinkage (size change rate ≤0.1%) of the polyester base film, and effectively improves the mechanical strength of the composite polyester backboard through the composite of the two polyester base films. Moreover, the cost of the composite polyester backboard is reduced by 50% compared with the price of the existing PP glass fiber reinforced white backboard with the same thickness; compared with the front plate packaging structure of CN220856590U which is provided with double-layer or multi-layer double-sided adhesive transparent front plate, the structure of the composite polyester backboard is simpler and the cost is lower.

[0020] In summary, the composite polyester backboard coats the outer weather-resistant coating on the lower surface of the first base film (which is a polyester base film), sets the inner adhesive layer on the upper surface of the second base film (which is a polyester base film), and bonds the first base film and the second base film through the composite adhesive layer (which is an epoxy acrylic adhesive layer) under low-temperature hot pressing, so that the composite polyester backboard with high strength, weather resistance, aging resistance, good (such as the encapsulation adhesive film of EVA) adhesion performance, small heat shrinkage and low cost is formed. Therefore, the composite polyester backboard can enhance the mechanical strength and other properties of the flexible photovoltaic module, greatly reduce the power attenuation of the flexible photovoltaic module after the hail test, avoid the edge warping problem of the flexible photovoltaic module, achieve the balance between performance and cost (the total thickness of the composite polyester backboard is preferably 730-770 μm, and the cost is reduced by 50% compared with the price of the existing PP glass fiber reinforced white backboard with the same thickness), and further improve the packaging reliability and long-term power generation of the flexible photovoltaic module. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 It is a cross-section structure schematic view of a composite polyester backboard of the utility model.

[0022] Figure 2 It is a composite process flow chart of a composite polyester backboard of the utility model.

[0023] Figure 3 It is a cross-section structure schematic view of a flexible photovoltaic module of the utility model.

[0024] Brief Description of the Drawings: composite polyester backboard 1;Inner layer adhesive layer 11;Second base film 12;Composite adhesive layer 13;First base film 14;Outer weatherable coating 15;First encapsulation adhesive layer 2;Photovoltaic cell 3;Second encapsulation adhesive layer 4;Transparent polyester front plate 5. DETAILED DESCRIPTION

[0025] In order to make the above-mentioned purpose, features and advantages of the utility model more obvious and easy to understand, the utility model will be further explained in detail below by combining with the drawings and specific embodiments.

[0026] EMBODIMENT

[0027] The composite polyester backboard 1 of this embodiment, see Figure 1 、 3 , it includes that outer weatherable coating 15, first base film 14, composite adhesive layer 13, second base film 12 and inner layer adhesive layer 11 are sequentially laminated from bottom to top.

[0028] Wherein, outer weatherable coating 15 is fluorine silicon modified polyester weatherable coating, fluorine silicon weatherable coating, fluorocarbon weatherable coating, organic silicon weatherable coating or polyester weatherable coating, to improve the weather resistance and aging resistance of composite polyester backboard 1, to improve its stability and reliability of long-term outdoor use.The thickness of the outer weatherable coating 15 is 10-25 μm (such as 10 μm, 15 μm, 20 μm or 25 μm).

[0029] Further, the outer weatherable coating 15 is a self-cleaning weatherable coating, to improve the surface self-cleaning property and surface stain resistance of composite polyester backboard 1, to reduce the artificial cleaning burden and reduce the labor cost.The thickness of the outer weatherable coating 15 is preferably 15-20 μm.

[0030] The first base film 14 and the second base film 12 are both polyester base films; the first base film 14 and the second base film 12 are preferably polyethylene terephthalate base films. The thickness of the first base film 14 and the second base film 12 is 300-400 μm (such as 300 μm, 320 μm, 340 μm, 360 μm, 380 μm or 400 μm). The use of the above material and thickness of the two base films can greatly improve the mechanical strength (such as tensile strength) of the composite polyester backboard 1, providing mechanical support for the flexible photovoltaic module; moreover, compared with the existing PP glass fiber reinforced white backboard such as CN117799271A, or the front plate packaging structure provided with double or multiple double-sided bonding transparent front plates such as CN220856590U, the production cost of the composite polyester backboard 1 of the present embodiment is lower.

[0031] Further, the first base film 14 and the second base film 12 are both polyethylene terephthalate base films (i.e. PET base films) after corona treatment, which can improve the interlayer adhesion and the interlayer structural stability of the composite polyester backboard 1. The thickness of the first base film 14 and the second base film 12 is preferably 340-360 μm (such as 350 μm).

[0032] The first base film 14 and the second base film 12 are bonded by the composite adhesive layer 13 to realize composite, and the composite adhesive layer 13 is an epoxy acrylic adhesive layer; in this way, the first base film 14 (which is a polyester base film) and the second base film 12 (which is a polyester base film) can be hot-pressed and combined at low temperature, effectively avoiding the thermal shrinkage (dimensional change rate ≤0.1%) of the polyester base film, which helps to improve the dimensional stability of the composite polyester backboard 1; moreover, the epoxy acrylic adhesive layer has good adhesion with the PET base film, which helps to improve the interlayer adhesion of the composite polyester backboard 1.

[0033] Specifically, the thickness of the composite adhesive layer 13 is 10-60 μm; the thickness of the composite adhesive layer 13 is preferably 30-50 μm (such as 40 μm).

[0034] The inner adhesive layer 11 is an adhesive coating; the thickness of the inner adhesive layer 11 is 5-15 μm (such as 5 μm, 8 μm, 10 μm, 12 μm or 15 μm). Specifically, the inner adhesive layer 11 is preferably a polyester adhesive coating; the thickness of the inner adhesive layer 11 is preferably 8-12 μm. The inner adhesive layer 11 enhances the interfacial bonding force between the composite polyester backboard 1 and the packaging adhesive film such as EVA.

[0035] In practice, when the composite polyester backboard 1 is applied to a flexible photovoltaic module, the inner adhesive layer 11 is bonded to the back light surface of the photovoltaic cell 3 in the flexible photovoltaic module (i.e. the lower surface of the photovoltaic cell 3).

[0036] The preparation method of the composite polyester backboard 1 of the present embodiment comprises the following preparation steps:

[0037] Step 1, the outer layer weather-resistant paint is coated on the lower surface of the first base film 14 after the corona treatment by three-roller coating, and the coated outer layer weather-resistant paint is dried in an oven, after which the outer layer weather-resistant paint is cured to form an outer layer weather-resistant coating 15, and the first base film 14 single-coated product with the lower surface of the first base film 14 having the outer layer weather-resistant coating 15 is obtained by winding.

[0038] Step 2, the polyester adhesive coating is coated on the upper surface of the second base film 12 after the corona treatment by three-roller coating, and the coated polyester adhesive coating is dried in an oven, after which the polyester adhesive coating is cured to form an inner layer adhesive layer 11, and the second base film 12 single-coated product with the upper surface of the second base film 12 having the inner layer adhesive layer 11 is obtained by winding.

[0039] Step 3, the non-coated surface of the first base film 14 single-coated product is compounded with the non-coated surface of the second base film 12 single-coated product by a dry compounding process, and the specific dry compounding process is as follows (see Figure 2 ): after the non-coated surface of the first base film 14 single-coated product is treated by corona surface plasma, the epoxy acrylic glue is coated on the non-coated surface of the first base film 14 single-coated product, and then it is put into an oven with a temperature of 60-80℃ (such as 80℃) to dry the solvent of the epoxy acrylic glue to form an epoxy acrylic glue layer (i.e. a compounding glue layer 13); then the non-coated surface of the second base film 12 single-coated product after the corona surface plasma treatment is hot-pressed and bonded with the epoxy acrylic glue layer, and after the bonding, it is put into an oven for baking and compounding, the linear speed of the compounding is 10-60m / min (such as 30m / min), and the whole process adopts low-temperature drying and curing, the temperature of the baking and compounding is ≤90℃ (such as 86℃), and the compounding polyester backboard 1 of the embodiment is obtained by winding.

[0040] A light-weight flexible photovoltaic module of the embodiment, see Figure 3 , which comprises a compounding polyester backboard 1, a first encapsulating glue layer 2, a photovoltaic cell 3, a second encapsulating glue layer 4 and a transparent polyester front plate 5 arranged in a stack from bottom to top. The compounding polyester backboard 1 is the compounding polyester backboard 1 prepared by steps 1-3 of the embodiment, and the inner layer adhesive layer 11 is bonded to the lower surface of the photovoltaic cell 3 in the flexible photovoltaic module through the first encapsulating glue layer 2. The transparent polyester front plate 5 is preferably a transparent PET front plate.

[0041] In summary, in the composite polyester backboard 1 of the embodiment, the outer weather-resistant coating layer 15 effectively improves the high weather resistance and excellent aging performance of the composite polyester backboard 1; the inner adhesive layer 11 enhances the interfacial bonding force of the composite polyester backboard 1 and the packaging adhesive film such as EVA; the epoxy acrylic adhesive layer (i.e., the composite adhesive layer 13) can realize high adhesion composite between the first base film 14 (which is a polyester base film) and the second base film 12 (which is a polyester base film) under low-temperature hot pressing, effectively avoiding the thermal shrinkage (dimensional change rate ≤0.1%) of the polyester base film, and effectively improving the mechanical strength of the composite polyester backboard 1 through the composite of the two layers of polyester base films. Moreover, the cost of the composite polyester backboard 1 is reduced by 50% compared with the price of the existing PP glass fiber reinforced white backboard with the same thickness; compared with the front plate packaging structure of CN220856590U which is provided with double or multiple double-sided adhesive transparent front plates, the structure of the composite polyester backboard 1 is simpler and the cost is lower.

[0042] Therefore, the composite polyester backboard 1 of the embodiment forms a composite polyester backboard 1 with high strength, weather resistance, aging resistance, good adhesion performance (with packaging adhesive films such as EVA), small thermal shrinkage, and low cost by coating the outer weather-resistant coating layer 15 on the lower surface of the first base film 14 (which is a polyester base film), providing the inner adhesive layer 11 on the upper surface of the second base film 12 (which is a polyester base film), and bonding the first base film 14 and the second base film 12 through the composite adhesive layer 13 (which is an epoxy acrylic adhesive layer) under low-temperature hot pressing. Therefore, the composite polyester backboard 1 can enhance the mechanical strength and other properties of the flexible photovoltaic module, greatly reduce the power attenuation of the flexible photovoltaic module after the hail test, and avoid the edge warping problem of the flexible photovoltaic module, achieving a balance between performance and cost (the total thickness of the composite polyester backboard 1 is preferably 730-770 μm, and the cost is reduced by 50% compared with the price of the existing PP glass fiber reinforced white backboard with the same thickness), and thus the composite polyester backboard 1 product can significantly improve the packaging reliability and long-term power generation of the flexible photovoltaic module.

[0043] Although the preferred embodiments of the utility model embodiments have been described, those skilled in the art can make additional changes and modifications to these embodiments once they know the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the utility model embodiments.

[0044] The above technical solutions provided by the utility model are described in detail, and the principles and implementation manners of the utility model are described by applying specific examples, and the above example is only used for helping to understand the method and core idea of the utility model; meanwhile, for the general technical personnel in the field, the specific implementation manners and application ranges will be changed according to the idea of the utility model, and the above description should not be understood as the limitation of the utility model.

Claims

1. A composite polyester backsheet characterized in that, The composite polyester backboard comprises, from bottom to top, a first base film and a second base film; the lower surface of the first base film is provided with an outer weather-resistant coating layer, and the upper surface of the second base film is provided with an inner adhesive layer which is bonded to the lower surface of a photovoltaic cell; The composite adhesive layer is arranged between the first base film and the second base film; the first base film and the second base film are polyester base films, and the composite adhesive layer is an epoxy-acrylic adhesive layer.

2. The composite polyester backsheet according to claim 1, wherein, The outer weather-resistant coating layer is a fluorosilicon-modified polyester weather-resistant coating layer, a fluorosilicon weather-resistant coating layer, a fluorocarbon weather-resistant coating layer, an organic silicon weather-resistant coating layer or a polyester weather-resistant coating layer; the thickness of the outer weather-resistant coating layer is 10-25 μm.

3. The composite polyester backsheet according to claim 1 or 2, characterized in that, The outer weather-resistant coating layer is a self-cleaning weather-resistant coating layer; the thickness of the outer weather-resistant coating layer is 15-20 μm.

4. The composite polyester backsheet of claim 1, wherein, The first base film and the second base film are hot-pressed and bonded through the composite adhesive layer, and the thickness of the composite adhesive layer is 10-60 μm.

5. The composite polyester backsheet according to claim 1 or 4, wherein The thickness of the composite adhesive layer is 30-50 μm.

6. The composite polyester backsheet of claim 1, wherein, The first base film and the second base film are both polyethylene terephthalate base films; the thickness of the first base film and the second base film is both 300-400 μm.

7. The composite polyester backsheet according to claim 1 or 6, wherein The first base film and the second base film are both polyethylene terephthalate base films treated by corona discharge; the thickness of the first base film and the second base film is both 340-360 μm.

8. The composite polyester backsheet of claim 1, wherein, The inner adhesive layer is an adhesive coating layer, and the thickness thereof is 5-15 μm.

9. The composite polyester backsheet according to claim 1 or 8, wherein The inner adhesive layer is a polyester adhesive coating layer, and the thickness thereof is 8-12 μm.

10. A flexible photovoltaic module, characterized by The composite polyester backboard comprises, from bottom to top, a first base film and a second base film; the lower surface of the first base film is provided with an outer weather-resistant coating layer, and the upper surface of the second base film is provided with an inner adhesive layer which is bonded to the lower surface of a photovoltaic cell; The composite adhesive layer is arranged between the first base film and the second base film; the first base film and the second base film are polyester base films, and the composite adhesive layer is an epoxy-acrylic adhesive layer.

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