PVC (polyvinyl chloride) composite sheet for photovoltaic backboard film and preparation method of PVC composite sheet

Abstract

The invention relates to the technical field of photovoltaic backboards, in particular to a PVC composite sheet for a photovoltaic backboard film and a preparation method thereof.The PVC composite sheet for the photovoltaic backboard film comprises a PVC base material, and the two sides of the PVC base material are each connected with a hydrolysis-resistant layer through a bonding layer; the adhesive layer is prepared by mixing an acrylic adhesive, a first inorganic filler, a curing agent, a curing accelerator, a first anti-hydrolysis stabilizer, a silane coupling agent and a solvent; according to the photovoltaic backboard film, the PVC material with relatively low cost is used as the core layer, so that the cost is reduced, and the photovoltaic backboard film is endowed with relatively good physical strength and impact resistance based on the characteristic of high tensile strength of the PVC material, thereby laying a foundation for maintaining the structural integrity and external pressure resistance of the photovoltaic backboard film and ensuring the service life of a photovoltaic module.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic backboards, and in particular to a PVC composite sheet for photovoltaic backboard films and a preparation method thereof. Background Art

[0002] Photovoltaic backsheets (also known as solar backsheets) are used on the back of photovoltaic modules to protect and support the cells. Since photovoltaic backsheets are directly exposed to the air, they are susceptible to corrosion by water vapor, acidic gases, high and low temperatures, and ultraviolet rays. Therefore, improving the weather resistance of photovoltaic backsheets has always been the focus of the industry. In addition, under long-term sunlight exposure, photovoltaic backsheets are prone to yellowing or cracking, which can seriously affect the insulation of photovoltaic backsheets and make photovoltaic modules unusable. The reflectivity of traditional photovoltaic backsheet films is low (for example, the reflectivity of common PET is 80%-85%). After a large amount of light energy is absorbed by the photovoltaic backsheet film, it is easy to cause the battery module to heat up, affecting the life of the photovoltaic module. Therefore, photovoltaic backsheet films with high reflectivity (≥97%) have extremely strong practical value. Summary of the invention

[0003] The purpose of the present invention is to solve the problem that the existing photovoltaic backplane film generates a lot of heat during use, which leads to yellowing and brittleness, thereby affecting the service life of the photovoltaic module, and to provide a PVC composite sheet for photovoltaic backplane film and a preparation method thereof. The PVC composite sheet for photovoltaic backplane film provided by the present invention has good barrier properties, electrical insulation and heat resistance, and has a high reflectivity, can effectively reduce the heat absorption of the photovoltaic backplane surface, and improve the conversion efficiency of the battery module. The preparation method thereof is simple in process and easy to operate.

[0004] In order to achieve the above-mentioned purpose, the present invention provides a PVC composite sheet for photovoltaic backplane film, comprising a PVC substrate, and both sides of the PVC substrate are connected with a hydrolysis-resistant layer through an adhesive layer; wherein the adhesive layer comprises an acrylic adhesive, a first inorganic filler, a curing agent, a curing accelerator, a first anti-hydrolysis stabilizer, a silane coupling agent and a solvent.

[0005] Preferably, the acrylic adhesive is an acrylic adhesive containing a hydroxyl group.

[0006] Preferably, the first inorganic filler is selected from one or a combination of at least two of titanium dioxide, silicon dioxide, aluminum oxide, aluminum sulfate, calcium carbonate, magnesium carbonate, aluminum silicate, and magnesium silicate.

[0007] Preferably, the particle size of the first inorganic filler is 0.01-1 μm.

[0008] Preferably, the first anti-hydrolysis stabilizer is polycarbodiimide, carbodiimide, or a combination thereof.

[0009] Preferably, the adhesive layer comprises a mixture of the following components in percentage by weight: 80-85% acrylic adhesive, 2-7% first inorganic filler, 3.5-5.5% curing agent, 0.2-0.5% curing accelerator, 0.1-0.5% first anti-hydrolysis stabilizer, 0.1-0.5% silane coupling agent, and 10-15% solvent.

[0010] Preferably, the thickness of the PVC substrate is 100-250 μm, the thickness of the adhesive layer is 5-15 μm, and the thickness of the hydrolysis-resistant layer is 20-50 μm.

[0011] Preferably, the hydrolysis-resistant layer is a biaxially stretched polyester film, and a second anti-hydrolysis stabilizer is added inside the biaxially stretched polyester film.

[0012] Preferably, the second anti-hydrolysis stabilizer is polycarbodiimide, carbodiimide, or a combination thereof.

[0013] Preferably, the added amount of the second anti-hydrolysis stabilizer is 5-8% of the total weight of the hydrolysis-resistant layer.

[0014] Preferably, a second inorganic filler is also added to the hydrolysis resistant layer.

[0015] Preferably, the second inorganic filler is selected from one or a combination of at least two of titanium dioxide, silicon dioxide, aluminum oxide, aluminum sulfate, calcium carbonate, magnesium carbonate, aluminum silicate, and magnesium silicate.

[0016] Preferably, the particle size of the second inorganic filler is 0.01-0.1 μm.

[0017] Preferably, the added amount of the second inorganic filler is 1-3% of the total weight of the hydrolysis resistant layer.

[0018] Preferably, a triangular prism-shaped protrusion structure distributed along the length direction of the PVC composite sheet is pressed on one side of the adhesive layer close to the hydrolysis-resistant layer.

[0019] Preferably, the height of the protruding structure is 5-20 μm, and the top angle is 120°±10°.

[0020] The present invention also provides a method for preparing the above-mentioned PVC composite sheet for photovoltaic backplane film, comprising the following steps: preparing a PVC substrate by a calendering process; preparing a coating liquid for forming an adhesive layer, and then applying the coating liquid to the PVC substrate, and then bonding and fixing the hydrolysis-resistant layer made by a biaxial stretching process to the PVC substrate.

[0021] Through the above technical scheme, by connecting the hydrolysis-resistant layer with the adhesive layer on both sides of the PVC substrate, it is ensured that the photovoltaic backplane film with excellent barrier properties, electrical insulation and heat resistance is obtained under the premise of reducing the cost of raw materials; compared with the traditional photovoltaic backplane film using PET material as the core layer, the present invention uses relatively low-cost PVC material as the core layer, while reducing the cost, it can also give the photovoltaic backplane film better physical strength and impact resistance based on the high tensile strength of the PVC material, thereby laying a foundation for maintaining the structural integrity of the photovoltaic backplane film and resisting external pressure, ensuring the service life of the photovoltaic module; in addition, in the adhesive layer provided by the present invention, the first inorganic filler filled can, on the one hand, play a role in improving the aging resistance, and on the other hand, can reflect the light penetrating through the hydrolysis-resistant layer, which can not only improve the light utilization rate of the photovoltaic module, but also reduce the heat generation of the photovoltaic backplane film, effectively improving the photovoltaic backplane film overheating to affect its life, and then yellowing, cracking and other problems that affect the service life of the photovoltaic module.

[0022] Other features and advantages of the embodiments of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings are used to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the embodiments of the present invention, but do not constitute a limitation on the embodiments of the present invention. In the accompanying drawings:

[0024] Figure 1 This is a schematic structural diagram of a PVC composite sheet for photovoltaic backplane film provided by the present invention;

[0025] Description of Reference Numerals

[0026] 1. PVC substrate; 2. Adhesive layer; 3. Hydrolysis resistant layer. DETAILED DESCRIPTION

[0027] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings and specific examples. It should be understood that the specific implementation described here is only used to illustrate and explain the implementation of the present invention, and is not used to limit the implementation of the present invention.

[0028] Combination Figure 1 As shown, the present invention provides a PVC composite sheet for photovoltaic backplane film, which includes a PVC substrate 1, and both sides of the PVC substrate 1 are connected with a hydrolysis-resistant layer 3 through an adhesive layer 2; wherein the adhesive layer 2 includes an acrylic adhesive, a first inorganic filler, a curing agent, a curing accelerator, a first anti-hydrolysis stabilizer, a silane coupling agent and a solvent.

[0029] Compared with the traditional photovoltaic backplane film that uses PET material as the core layer, the present invention uses a PVC substrate with relatively cheap raw materials and relatively mature manufacturing technology as the core layer, which reduces the cost of the photovoltaic backplane film; in addition, thanks to the high tensile strength of the PVC material, the photovoltaic backplane film is endowed with good physical strength and impact resistance, thereby laying the foundation for maintaining the structural integrity of the photovoltaic backplane film and resisting external pressure, thereby ensuring the service life of the photovoltaic module.

[0030] In the technical solution provided by the present invention, the adhesive layer 2 plays a connecting role on the one hand, and the first inorganic filler filled therein can play a role in improving the aging resistance on the other hand; and the first inorganic filler filled in the adhesive layer 2 can reflect the light penetrating through the hydrolysis-resistant layer 3, which can improve the light utilization rate of the photovoltaic module on the one hand, and reduce the heat generation of the photovoltaic backplane film on the other hand, effectively improving the photovoltaic backplane film overheating that affects its life, and then causing yellowing, cracking and other problems that affect the service life of the photovoltaic module.

[0031] In the present invention, the acrylic adhesive may be an acrylic adhesive containing a hydroxyl group. The acrylic adhesive containing a carboxyl group can react chemically with the surface of the PVC substrate by the carboxyl group carried by the acrylic adhesive, thereby enhancing the bonding effect between the adhesive layer and the PVC substrate.

[0032] In the present invention, the first inorganic filler can be selected from one or a combination of at least two of titanium dioxide, silicon dioxide, aluminum oxide, aluminum sulfate, calcium carbonate, magnesium carbonate, aluminum silicate, and magnesium silicate; in the present invention, the particle size of the first inorganic filler can be selected within an appropriate range. As a preferred embodiment, the particle size of the first inorganic filler is 0.01-1μm, for example, it can be 0.01μm, 0.02μm, 0.03μm, 0.04μm, 0.05μm, 0.1μm, 0.2μm, 0.3μm, 0.4μm, 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm, 1μm.

[0033] In the present invention, the first anti-hydrolysis stabilizer is used to improve the hydrolysis resistance of the hydrolysis-resistant layer on the outside of the PVC substrate. Preferably, the first anti-hydrolysis stabilizer can be polycarbodiimide, or carbodiimide, or a combination of polycarbodiimide and carbodiimide. When a combination of polycarbodiimide and carbodiimide is used as the first anti-hydrolysis stabilizer, the weight ratio of the polycarbodiimide to the carbodiimide can be 1:1.

[0034] In the present invention, the amount of each raw material component in the adhesive layer can be selected within an appropriate range. In some embodiments of the present invention, the adhesive layer comprises a mixture of the following components in percentage by weight: 80-85% acrylic adhesive, 2-7% first inorganic filler, 3.5-5.5% curing agent, 0.2-0.5% curing accelerator, 0.1-0.5% first anti-hydrolysis stabilizer, 0.1-0.5% silane coupling agent, and 10-15% solvent.

[0035] In the present invention, the thickness of the PVC substrate is 100-250 μm, the thickness of the adhesive layer is 5-15 μm, and the thickness of the hydrolysis-resistant layer is 20-50 μm.

[0036] In the present invention, the hydrolysis resistant layer is a biaxially stretched polyester film, and a second hydrolysis resistant stabilizer is added to the biaxially stretched polyester film; preferably, the second hydrolysis resistant stabilizer can be polycarbodiimide, or carbodiimide, or a combination of polycarbodiimide and carbodiimide. When a combination of polycarbodiimide and carbodiimide is used as the second hydrolysis resistant stabilizer, the weight ratio of the polycarbodiimide to carbodiimide can be 1:1. In the present invention, the addition amount of the second hydrolysis resistant stabilizer is 5-8% of the total weight of the hydrolysis resistant layer.

[0037] In some embodiments, a second inorganic filler is further added to the hydrolysis-resistant layer; the second inorganic filler is selected from one or a combination of at least two of titanium dioxide, silicon dioxide, aluminum oxide, aluminum sulfate, calcium carbonate, magnesium carbonate, aluminum silicate, and magnesium silicate; the particle size of the second inorganic filler is 0.01-0.1 μm; the amount of the second inorganic filler added is 1-3% of the total weight of the hydrolysis-resistant layer.

[0038] In some embodiments, a triangular prism-shaped protrusion structure distributed along the length direction of the PVC composite sheet is pressed on one side of the adhesive layer close to the hydrolysis-resistant layer; further, the height of the protrusion structure is 5-20 μm, and the top angle is 120°±10°. Through the above arrangement, the contact area between the adhesive layer and the hydrolysis-resistant layer is further increased, and the bonding effect is improved.

[0039] The present invention also provides a method for preparing the above-mentioned PVC composite sheet for photovoltaic backplane film, comprising the following steps: preparing a PVC substrate by a calendering process; preparing a coating liquid for forming an adhesive layer, and then applying the coating liquid to the PVC substrate, and then bonding and fixing the hydrolysis-resistant layer made by a biaxial stretching process to the PVC substrate.

[0040] The performance of the PVC composite sheet for photovoltaic backsheet film provided by the present invention is further described below through specific examples. In addition, the test methods for the adhesion performance, barrier properties and weather resistance of the photovoltaic backsheet film in the following examples are briefly described as follows:

[0041] 1) Adhesion test

[0042] The obtained photovoltaic backsheet film was cut into strips with a width of 15 mm and a length of about 1 m, and the hydrolysis-resistant layer was slightly peeled off at one end of the strip. The PVC substrate and the hydrolysis-resistant layer were clamped separately on a tensile tester (INSTRON universal material testing machine), and stretched at an angle of 180° to continuously and completely peel off the PVC substrate and the hydrolysis-resistant layer. The tensile force data displayed during the stretching period was read to obtain the force required for peeling. The greater the peeling force, the better the bonding performance of the photovoltaic backsheet film.

[0043] 2) Barrier test

[0044] The barrier property is characterized by the water vapor transmission rate, referring to the method disclosed in the ISO15106-3 test standard, with the test environment temperature being 35±5°C and the relative humidity being 95±5%.

[0045] 3) Weather resistance test

[0046] Weather resistance is characterized by delamination, breakdown voltage, and discoloration. The delamination test of the samples was carried out using the method disclosed in the solar panel certification / solar photovoltaic panel IEC61215 standard. The test conditions were: temperature 85°C, relative humidity 85% RH, time 2000 hours, and the samples were observed for delamination. No delamination was OK, and delamination was NO. The breakdown voltage test of the samples was carried out using the method disclosed in the ASTMF-149 standard. The detection method of discoloration was: place the samples at 60°C under a 1KW ultraviolet xenon lamp for 150 hours, and observe for discoloration. No discoloration was OK, and discoloration was NO.

[0047] Example 1

[0048] The PVC raw material (purchased from Formosa Plastics, model S-70) was prepared into a PVC substrate with a thickness of 200 μm by a calendering process;

[0049] The coating liquid for forming the adhesive layer was prepared according to the following formula:

[0050] Acrylic adhesive containing hydroxyl group (brand 8723, manufactured by Nippon Synthetic Chemical Co., Ltd.) 82.5%; inorganic filler (rutile titanium dioxide; particle size 0.02μm) 3.5%; curing agent (brand D201, Dornade) 4.0%; curing accelerator (dibutyltin dilaurate) 0.5%; anti-hydrolysis stabilizer (polycarbodiimide, brand P200, Stabaxol series of German Rheinland Company) 0.5%; silane coupling agent (NCO-C3H6-Si(OCH3)3) 0.5%; solvent (butyl acetate) 8.5%.

[0051] The coating liquid was scraped onto both sides of the PVC substrate, and the hydrolysis-resistant layers were adhered to the two sides respectively; wherein the thickness of the adhesive layer was 10 μm, and the thickness of the hydrolysis-resistant layer was 50 μm.

[0052] The hydrolysis-resistant layer is a biaxially stretched polyester film, to which polycarbodiimide (brand name P200, Stabaxol series of German Rhine Company) and titanium dioxide (rutile type, particle size 0.02μm) are added, and the amount of polycarbodiimide added is 5% of the total weight of the hydrolysis-resistant layer, and the amount of titanium dioxide added is 3% of the total weight of the hydrolysis-resistant layer.

[0053] The PVC composite sheet for photovoltaic backplane film prepared in the above embodiment has an interlayer peeling force of 75N / 15mm and a water vapor permeability of 0.13g / m2·24h. In terms of weather resistance, the delamination phenomenon is OK, the breakdown voltage is 28.5kV, and the discoloration phenomenon is OK.

[0054] Based on this, it can be seen that the PVC composite sheet for photovoltaic backplane film provided by the present invention has excellent performance and can completely replace the existing photovoltaic backplane film based on PET material as the core layer.

[0055] The optional implementation modes of the examples of the present invention are described in detail above in combination with the accompanying drawings and embodiments. However, the implementation modes of the present invention are not limited to the specific details in the above implementation modes. Within the technical concept of the implementation modes of the present invention, various simple modifications can be made to the technical solutions of the implementation modes of the present invention. These simple modifications all belong to the protection scope of the implementation modes of the present invention.

[0056] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the embodiments of the present invention will not further describe various possible combinations.

[0057] In addition, various different embodiments of the embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the embodiments of the present invention, they should also be regarded as the contents disclosed in the embodiments of the present invention.

Claims

1. A PVC composite sheet for photovoltaic backplane film, characterized in that: It comprises a PVC substrate, and two sides of the PVC substrate are respectively connected with a hydrolysis-resistant layer through an adhesive layer; The adhesive layer is formed by mixing an acrylic adhesive, a first inorganic filler, a curing agent, a curing accelerator, a first anti-hydrolysis stabilizer, a silane coupling agent and a solvent.

2. The PVC composite sheet for photovoltaic backplane film according to claim 1, characterized in that: The acrylic adhesive is an acrylic adhesive containing a hydroxyl group.

3. The PVC composite sheet for photovoltaic backplane film according to claim 1, characterized in that: The first inorganic filler is selected from one or a combination of at least two of titanium dioxide, silicon dioxide, aluminum oxide, aluminum sulfate, calcium carbonate, magnesium carbonate, aluminum silicate, and magnesium silicate; Preferably, the particle size of the first inorganic filler is 0.01-1 μm.

4. The PVC composite sheet for photovoltaic backplane film according to claim 1, characterized in that: The first anti-hydrolysis stabilizer is polycarbodiimide, carbodiimide, or a combination thereof.

5. The PVC composite sheet for photovoltaic backplane film according to claim 1, characterized in that: The adhesive layer comprises the following components in percentage by weight: 80-85% acrylic adhesive, 2-7% first inorganic filler, 3.5-5.5% curing agent, 0.2-0.5% curing accelerator, 0.1-0.5% first anti-hydrolysis stabilizer, 0.1-0.5% silane coupling agent and 10-15% solvent.

6. The PVC composite sheet for photovoltaic backplane film according to claim 1, characterized in that: The thickness of the PVC substrate is 100-250 μm, the thickness of the adhesive layer is 5-15 μm, and the thickness of the hydrolysis-resistant layer is 20-50 μm.

7. The PVC composite sheet for photovoltaic backplane film according to claim 1, characterized in that: The hydrolysis-resistant layer is a biaxially stretched polyester film, and a second anti-hydrolysis stabilizer is added inside the biaxially stretched polyester film; Preferably, the second anti-hydrolysis stabilizer is polycarbodiimide, carbodiimide, or a combination thereof; Preferably, the added amount of the second anti-hydrolysis stabilizer is 5-8% of the total weight of the hydrolysis-resistant layer.

8. The PVC composite sheet for photovoltaic backplane film according to claim 7, characterized in that: A second inorganic filler is also added to the hydrolysis-resistant layer; Preferably, the second inorganic filler is selected from one or a combination of at least two of titanium dioxide, silicon dioxide, aluminum oxide, aluminum sulfate, calcium carbonate, magnesium carbonate, aluminum silicate, and magnesium silicate; Preferably, the particle size of the second inorganic filler is 0.01-0.1 μm; Preferably, the added amount of the second inorganic filler is 1-3% of the total weight of the hydrolysis resistant layer.

9. The PVC composite sheet for photovoltaic backplane film according to any one of claims 1 to 8, characterized in that: A triangular prism-shaped protrusion structure distributed along the length direction of the PVC composite sheet is pressed on one side of the adhesive layer close to the hydrolysis-resistant layer; Preferably, the height of the protruding structure is 5-20 μm, and the top angle is 120°±10°.

10. The method for preparing a PVC composite sheet for photovoltaic backplane film according to any one of claims 1 to 9, characterized in that: The following steps are involved: The PVC substrate is prepared by calendering process; A coating liquid for forming an adhesive layer is prepared, and then the coating liquid is coated on the PVC substrate, and then the hydrolysis-resistant layer made by a biaxial stretching process is bonded and fixed to the PVC substrate.

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