A double-layer PET composite material for photovoltaic front panels, its preparation method, products and applications

Abstract

This invention, entitled "A Double-Layer PET Composite Material for Photovoltaic Front Panels, its Preparation Method, Products, and Applications," belongs to the field of PET material technology. The technical problem to be solved is to obtain a double-layer PET composite material for photovoltaic front panels that simultaneously possesses an initial peel strength ≥10 N / cm, a strength decay rate of less than 22.86% after 1000 hours of humid heat aging at 85℃ / 85%RH, and a light transmittance aging decay rate of less than 2.9%. This invention employs plasma surface grafting of carboxyl-containing monomers to modify the PET substrate and selects a specific adhesive formulation, thereby improving the interlayer peel strength and weather resistance of the PET, solving the problems of rapid aging decay of peel strength and poor weather resistance between the two PET layers.

Description

Technical Field

[0001] This invention belongs to the field of PET material technology, specifically relating to a double-layer PET composite material for photovoltaic front panels, its preparation method, products, and applications. Background Technology

[0002] For understanding the technical content of this invention:

[0003] The development of photovoltaic technology is trending towards lightweighting and low-carbonization. Achieving lightweighting requires the development of lightweight photovoltaic modules, which has emerged under the dual impetus of expanding traditional photovoltaic applications and technological iteration. Traditional crystalline silicon modules are heavy (approximately 30 kg / m²) due to the use of materials such as glass and aluminum frames. 2 This limits its application in areas with weak load-bearing roofs, flexible curved surfaces, and mobile scenarios.

[0004] Industrial and commercial factory buildings (load-bearing capacity ≤ 15kg / m²) 2 Old houses (load-bearing capacity ≤25kg / m) 2 Due to their limited load-bearing capacity, corrugated steel roofs used in warehousing and logistics facilities urgently require lightweight solutions. Against this backdrop, lightweight component technologies, centered on flexible substrates (such as polymers), ultra-thin glass, and frameless designs, are rapidly maturing, reducing weight to 3-6 kg / m². 2 Furthermore, it possesses bendability and ease of installation. The development of lightweight front panels is particularly important, requiring high light transmittance, moisture barrier properties, UV radiation resistance, impact resistance, excellent mechanical properties (such as toughness and rigidity), and good weather resistance. Currently, commonly used front panel materials include glass and polymer materials. While glass offers high light transmittance and rigidity, its weight is significant (12.5 kg / m²). 2 Their fragility limits their application in lightweight photovoltaic modules. Although polymer materials (such as polycarbonate and polymethyl methacrylate) are lightweight and have good toughness, they have poor rigidity and are prone to aging when exposed to outdoor environments for a long time.

[0005] Relevant patent documents retrieved:

[0006] The document, published in China (CN102569462A) on July 11, 2012, discloses a plasma-modified all-polyester solar cell backsheet and its production process. The process includes the following steps: (1) treating one side of a first high-weather-resistant PET in a plasma treatment machine for 0.1-2 seconds to form a graft layer on that side; (2) bonding the other side of the first high-weather-resistant PET to one side of a PET substrate using an adhesive to obtain a first high-weather-resistant PET layer, with a bonding pressure of 3-10 kgf, and pre-curing at 40-60°C for 1-3 days; (3) bonding the other side of the PET substrate to a second high-weather-resistant PET using an adhesive to obtain a second high-weather-resistant PET layer, with a bonding pressure of 3-10 kgf, and curing at 40-60°C for 3-10 days.

[0007] The document, published in China (CN101646739A) on February 10, 2010, discloses a pressure-sensitive adhesive comprising needle-like silica particles crosslinked with multifunctional aziridine. It comprises: (a) a polymer comprising: (i) 90 to 99 parts by weight of a non-tertiary alcohol (meth)acrylate having 1 to 14 carbon atoms, preferably having an average number of carbon atoms of about 4 to about 12; (ii) 1 to 10 parts by weight of an acidic functional monomer; (iii) 0 to 10 parts by weight of a second, non-acidic functional polar monomer; (iv) 0 to 5 parts by weight of a vinyl monomer; (v) optionally 0.01 to 1 part by weight of a polyfunctional acrylate; (b) 0.001 to 1 part by weight of a polyfunctional aziridine crosslinking agent based on 100 parts by weight of polymer (a); and (c) 1 to 8 parts by weight of silica nanoparticles having an average particle size of 9-25 nm and a length of 40-300 nm based on 100 parts by weight of polymer (a).

[0008] Relevant non-patent literature retrieved:

[0009] Journal or book title: Functional Materials; document title: Study on surface-modified polyester material and its anticoagulant properties with choline phosphate; volume number: 2011, issue 7, pp. 1265-1268, 1272; publication date: April 21, 2012; this document discloses the use of oxygen plasma to pretreat the surface of polyester material (polyethylene terephthalate, PET), and then grafting acrylic acid onto its surface by ultraviolet irradiation, with the carboxyl groups in the grafted polyacrylic acid chain as the reaction sites.

[0010] The prior art represented by the aforementioned documents has at least the following unresolved technical problems or defects:

[0011] To meet the stringent operating conditions of distributed photovoltaic and BIPV, lightweight front panels must achieve a triple balance: 1. Lightweight, with a weight of <4kg / m² 2 2. High reliability: Transmittance over 90%, damp heat aging retention rate >90%, resistant to hail impact. 3. Process compatibility, roll-to-roll production possible. Current technological gaps: Single materials cannot achieve optimal performance: Fluorine films have high transmittance but insufficient rigidity; transmittance drops sharply after glass fiber reinforcement; Composite interfaces are prone to delamination: The peel strength of the PET / adhesive / PET structure decreases by >60% in damp heat environments (TÜV test). Developing a double-layer PET composite front panel with high initial bond strength (≥10N / cm) and aging resistance (both strength and transmittance are better maintained at 85℃ / 85%RH for 1000h) remains an urgent industry need. Summary of the Invention

[0012] The purpose of this invention is to provide a double-layer PET composite structure for photovoltaic front panels and related technologies.

[0013] Terminology Explanation:

[0014] Unless otherwise defined, all technical terms in this document have the same meanings as commonly understood by one of ordinary skill in the art to which the subject matter of the claims pertains. Unless otherwise stated, all patents, patent inventions, and publications cited in this document are incorporated herein by reference in their entirety. If multiple definitions exist for terms in this document, the definitions in this chapter shall prevail.

[0015] It should be understood that the above brief description and the following detailed description are exemplary and for illustrative purposes only, and do not limit the subject matter of the invention in any way. In this invention, the singular is used in conjunction with the plural unless otherwise specifically stated. It should also be noted that, unless otherwise stated, the use of “or” or “or” means “and / or”. Furthermore, the use of the term “comprising” and other forms such as “including,” “containing,” and “contains” are not limiting.

[0016] Definitions of standard chemical terms can be found in the reference book *Polymer Chemistry* (Chemical Industry Press, May 2005). See also standard IEC 62788-2-1:2023.

[0017] Unless otherwise stated, conventional methods within the scope of the art, such as peel strength testing and material transmittance testing, shall be used.

[0018] Unless specifically defined herein, the use of all commercially available products herein employs standard techniques. For example, it may be carried out using the manufacturer's instructions for use with the kit, or in accordance with methods known in the art or the description of this invention. The techniques and methods described herein can generally be implemented according to conventional methods well known in the art, based on the descriptions in the various summary and more specific documents cited and discussed in this specification.

[0019] The terms “optional / arbitrary” or “optionally / arbitrarily” mean that the event or situation described below may or may not occur, including both the occurrence and non-occurrence of the event or situation.

[0020] The terms "at most" and "at least" refer to the upper limit (including endpoint values) and lower limit (including endpoint values) of the range of values, respectively. For example, "at least one layer" means one or more layers, including 1 layer, 2 layers, 3 layers, etc.

[0021] The term "grafting rate" as used in this article refers to the percentage of the mass of the new chain grafted onto the surface or molecular chain of a material relative to the mass of the original material after another polymer chain has been introduced through a chemical reaction.

[0022] The term "plasma treatment" as used in this article refers to a surface treatment technology that uses plasma (partially ionized gas containing active particles such as ions, electrons, and free radicals) to bombard the surface of a material, thereby cleaning, activating, or altering its surface chemical properties.

[0023] The term "monomer" as used in this article refers to a small molecule compound that can form a polymer through a polymerization reaction; it is the basic structural unit of a polymer.

[0024] The term "carboxyl-containing monomer" as used in this article refers to a monomer that simultaneously contains at least one addition reaction site (addition reaction sites include, but are not limited to, alkenyl and alkynyl groups) and at least one carboxyl group or a functional group capable of generating a carboxyl group (functional groups include, but are not limited to, carboxyl groups, acyl halides, carboxylic anhydrides, and esters).

[0025] The term “(elements) are selected independently from (a certain range)” used in this article means that: there are two or more elements, all of which are selected from a certain range, and the selection method of each element is not restricted, influenced or guided by the selection methods of other elements.

[0026] In a first aspect, the present invention provides: a double-layer PET composite material for photovoltaic front panels, comprising two PET substrates, an adhesive layer and a fluorine-containing coating, wherein the two PET substrates are laminated and bonded together by the adhesive layer, and at least one of the outer sides of the two PET substrates is coated with a fluorine-containing coating.

[0027] At least one PET substrate layer has a grafting surface at the contact surface with the adhesive layer. The grafting surface is a grafting surface with carboxyl monomers grafted by radio frequency plasma, and the grafting rate is 5%-15%.

[0028] The adhesive comprises:

[0029] (a) Polyurethane-modified acrylate;

[0030] (b) Aziridine crosslinking agent comprising 3%-8% of the total weight of the adhesive; and

[0031] (c) 1%-5% by weight of epoxy silane-modified SiO2 nanoparticles.

[0032] Wherein, the contact surface between the at least one PET substrate and the adhesive layer is a grafted surface, including the contact surface between one PET substrate and the adhesive layer being a grafted surface or the contact surfaces between both PET substrates and the adhesive layer being grafted surfaces; preferably, the contact surfaces between both PET substrates and the adhesive layer are grafted surfaces.

[0033] The carboxyl-containing monomers include, but are not limited to, one or more of the following monomers:

[0034]

[0035]

[0036] .

[0037] The grafting rate is selected from any value between 5% and 15%, for example, the following values ​​or any range formed by both: 5.0%, 5.1%, 5.2%, 5.3%, 5.4%, 5.5%, 5.6%, 5.7%, 5.8%, 5.9%, 6.0%, 6.1%, 6.2%, 6.3%, 6.4%, 6.5%, 6.6%, 6.7%, 6.8%, 6.9%, 7.0%, 7.1%, 7.2%, 7.3%, 7.4%, 7.5%, 7.6%, 7.7%, 7.8%, 7.9%, 8.0%, 8.1%, 8.2%, 8.3%, 8.4%, 8.5%, 8.6%, 8.7%, 8.8%, 8.9%, 9.0%, 9.1%, 9.2%, 9.3%, 9.4%, 9.5%, 9.6%, 9.7%, 9.8%, 9.9%, 10.0%. 10.1%, 10.2%, 10.3%, 10.4%, 10.5%, 10.6%, 10.7%, 10.8%, 10.9%, 11.0%, 11.1%, 11.2%, 11.3%, 11.4%, 11.5%, 11.6%, 11.7%, 11.8%, 11.9%, 12.0%, 12.1%, 12.2%, 12.3%, 12.4%, 12.5%. 12.6%, 12.7%, 12.8%, 12.9%, 13.0%, 13.1%, 13.2%, 13.3%, 13.4%, 13.5%, 13.6%, 13.7%, 13.8%, 13.9%, 14.0%, 14.1%, 14.2%, 14.3%, 14.4%, 14.5%, 14.6%, 14.7%, 14.8%, 14.9%, 15.0%.

[0038] In one specific embodiment of the present invention, the grafting rate is 5%.

[0039] In one specific embodiment of the present invention, the grafting rate is 8.3%.

[0040] In one specific embodiment of the present invention, the grafting rate is 13%.

[0041] In one specific embodiment of the present invention, the grafting rate is 15%.

[0042] The percentage of the aziridine crosslinking agent in the total weight of the adhesive is selected from any value between 3% and 8%, for example, the following values ​​or any range formed between the two: 3.0%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9%, 4.0%, 4.1%, 4.2%, 4.3%, 4.4%, 4.5%, 4.6%, 4.7%, 4.8%, 4.9%, 5.0%, 5.1%, 5.2%, 5.3%, 5.4%, 5.5%, 5.6%, 5.7%, 5.8%, 5.9%, 6.0%, 6.1%, 6.2%, 6.3%, 6.4%, 6.5%, 6.6%, 6.7%, 6.8%, 6.9%, 7.0%, 7.1%, 7.2%, 7.3%, 7.4%, 7.5%, 7.6%, 7.7%, 7.8%, 7.9%, 8.0%.

[0043] In one specific embodiment of the present invention, the aziridine crosslinking agent accounts for 3% of the total weight of the adhesive.

[0044] In one specific embodiment of the present invention, the aziridine crosslinking agent accounts for 5% of the total weight of the adhesive.

[0045] In one specific embodiment of the present invention, the aziridine crosslinking agent accounts for 6% of the total weight of the adhesive.

[0046] In one specific embodiment of the present invention, the aziridine crosslinking agent accounts for 8% of the total weight of the adhesive.

[0047] The percentage of the epoxy-silane-modified SiO2 nanoparticles in the total weight of the adhesive is selected from any value between 1% and 5%, for example, the following values ​​or any range formed between the two: 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3.0%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9%, 4.0%, 4.1%, 4.2%, 4.3%, 4.4%, 4.5%, 4.6%, 4.7%, 4.8%, 4.9%, 5.0%.

[0048] In one specific embodiment of the present invention, the epoxy-silane modified SiO2 nanoparticles account for 1% of the total weight of the adhesive.

[0049] In one specific embodiment of the present invention, the epoxy-silane modified SiO2 nanoparticles account for 3% of the total weight of the adhesive.

[0050] In one specific embodiment of the present invention, the epoxy-silane modified SiO2 nanoparticles account for 4% of the total weight of the adhesive.

[0051] In one specific embodiment of the present invention, the epoxy-silane modified SiO2 nanoparticles account for 5% of the total weight of the adhesive.

[0052] Furthermore, the thickness of each of the two PET substrate layers is independently selected from 200-300 μm; the light transmittance of each PET substrate layer is >90%, and the haze is <1%; the thickness of the fluorine-containing coating is 3-15 μm, and the thickness of the adhesive layer is 5-50 μm.

[0053] The thickness of each of the two PET substrate layers is independently selected from 200-300 μm, specifically, it can be selected from any value between 200-300 μm, such as the following values ​​or any range formed by both: 200 μm, 201 μm, 202 μm, 203 μm, 204 μm, 205 μm, 206 μm, 207 μm, 208 μm, 209 μm, 210 μm, 211 μm, 212 μm, 213 μm, 214 μm, 215 μm. μm, 216μm, 217μm, 218μm, 219μm, 220μm, 221μm, 222μm, 223μm, 224μm, 225μm, 226μm, 227μm, 228μm, 229μm m, 230μm, 231μm, 232μm, 233μm, 234μm, 235μm, 236μm, 237μm, 238μm, 239μm, 240μm, 241μm, 242μm, 243μm, 244μm, 245μm, 246μm, 247μm, 248μm, 249μm, 250μm, 251μm, 252μm, 253μm, 254μm, 255μm, 256μm, 257μm, 2 58μm, 259μm, 260μm, 261μm, 262μm, 263μm, 264μm, 265μm, 266μm, 267μm, 268μm, 269μm, 270μm, 271μm, 272 μm, 273μm, 274μm, 275μm, 276μm, 277μm, 278μm, 279μm, 280μm, 281μm, 282μm, 283μm, 284μm, 285μm, 286μm m, 287μm, 288μm, 289μm, 290μm, 291μm, 292μm, 293μm, 294μm, 295μm, 296μm, 297μm, 298μm, 299μm, 300μm.

[0054] In one specific embodiment of the present invention, the thickness of both PET substrate layers is 250 μm.

[0055] In one specific embodiment of the present invention, the thickness of both PET substrate layers is 300 μm.

[0056] The thickness of the fluorine-containing coating is 3-15 μm / layer, specifically selectable from any value between 3-15 μm / layer, such as the following values ​​or any range formed by both: 3 μm / layer, 4 μm / layer, 5 μm / layer, 6 μm / layer, 7 μm / layer, 8 μm / layer, 9 μm / layer, 10 μm / layer, 11 μm / layer, 12 μm / layer, 13 μm / layer, 14 μm / layer, 15 μm / layer.

[0057] In one specific embodiment of the present invention, the thickness of the fluorine-containing coating is 3 μm / layer.

[0058] In one specific embodiment of the present invention, the thickness of the fluorine-containing coating is 5 μm / layer.

[0059] In one specific embodiment of the present invention, the thickness of the fluorine-containing coating is 6 μm / layer.

[0060] In one specific embodiment of the present invention, the thickness of the fluorine-containing coating is 8 μm / layer.

[0061] In one specific embodiment of the present invention, the thickness of the fluorine-containing coating is 10 μm / layer.

[0062] In one specific embodiment of the present invention, the thickness of the fluorine-containing coating is 15 μm / layer.

[0063] The thickness of the adhesive layer is 5-50 μm, specifically selectable from any value between 5-50 μm, such as the following values ​​or any range formed by both: 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, 20μm, 21μm, 22μm. m, 23μm, 24μm, 25μm, 26μm, 27μm, 28μm, 29μm, 30μm, 31μm, 32μm, 33μm, 34μm, 35μm, 36μm , 37μm, 38μm, 39μm, 40μm, 41μm, 42μm, 43μm, 44μm, 45μm, 46μm, 47μm, 48μm, 49μm, 50μm.

[0064] In one specific embodiment of the present invention, the thickness of the adhesive layer is 5 μm.

[0065] In one specific embodiment of the present invention, the thickness of the adhesive layer is 20 μm.

[0066] In one specific embodiment of the present invention, the thickness of the adhesive layer is 30 μm.

[0067] In one specific embodiment of the present invention, the thickness of the adhesive layer is 50 μm.

[0068] Furthermore, the carboxyl-containing monomer is selected from acrylic acid or maleic anhydride.

[0069] Furthermore, the epoxy silane is γ-(2,3-epoxypropoxy)propyltrimethoxysilane, the epoxy silane-modified SiO2 nanoparticles are made of fumed silica nanoparticles, the average particle size of the fumed silica nanoparticles is 20-50 nm, and the surface epoxy content of the modified SiO2 nanoparticles is ≥0.8 mmol / g.

[0070] The average particle size of the fumed silica nanoparticles is 20-50 nm, specifically selectable from any value between 20-50 nm, such as the following values ​​or any range formed by both: 20 nm, 21 nm, 22 nm, 23 nm, 24 nm, 25 nm, 26 nm, 27 nm, 28 nm, 29 nm, 30 nm, 31 nm, 32 nm, 33 nm, 34 nm, 35 nm, 36 nm, 37 nm, 38 nm, 39 nm, 40 nm, 41 nm, 42 nm, 43 nm, 44 nm, 45 nm, 46 nm, 47 nm, 48 nm, 49 nm, 50 nm.

[0071] In one specific embodiment of the present invention, the average particle size of the fumed silica nanoparticles is 20 nm.

[0072] The surface epoxy content is ≥0.8 mmol / g, and can be selected from any value exceeding 0.8 mmol / g, such as the following values ​​or any range formed between the two: 0.8 mmol / g, 0.9 mmol / g, 1.0 mmol / g, 1.1 mmol / g, 1.2 mmol / g, 1.3 mmol / g, 1.4 mmol / g, 1.5 mmol / g, 1.6 mmol / g, 1.7 mmol / g.

[0073] As a specific embodiment of the present invention, the surface epoxy group content of the modified SiO2 nanoparticles is 1.4 mmol / g.

[0074] Furthermore, the adhesive also includes 0.3%-0.8% polyether-modified polysiloxane leveling agent by weight of the total adhesive.

[0075] The percentage of the polyether-modified polysiloxane leveling agent in the total weight of the adhesive is selected from any value between 0.3% and 0.8%, such as the following values ​​or any range formed between the two: 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%.

[0076] In one specific embodiment of the present invention, the polyether-modified polysiloxane leveling agent accounts for 0.3% of the total weight of the adhesive.

[0077] In one specific embodiment of the present invention, the polyether-modified polysiloxane leveling agent accounts for 0.5% of the total weight of the adhesive.

[0078] In one specific embodiment of the present invention, the polyether-modified polysiloxane leveling agent accounts for 0.8% of the total weight of the adhesive.

[0079] Furthermore, the adhesive is composed of the following substances in weight percentage:

[0080] 3%-8% aziridine crosslinking agent, 1%-5% epoxy silane modified SiO2 nanoparticles and the balance polyurethane modified acrylate.

[0081] Furthermore, and as a specific embodiment of the present invention, the adhesive is composed of the following substances in weight percentage: 5% aziridine crosslinking agent, 3% epoxy silane modified SiO2 nanoparticles, and the balance polyurethane modified acrylate.

[0082] Furthermore, the adhesive is composed of the following substances in weight percentage:

[0083] 3%-8% aziridine crosslinking agent, 1%-5% epoxy silane modified SiO2 nanoparticles, 0.3%-0.8% polyether modified polysiloxane leveling agent and the balance polyurethane modified acrylate.

[0084] As a specific embodiment of the present invention, the adhesive is composed of the following substances in weight percentage: 6% aziridine crosslinking agent, 4% epoxy silane modified SiO2 nanoparticles, 0.5% polyether modified polysiloxane leveling agent and the balance polyurethane modified acrylate.

[0085] As a specific embodiment of the present invention, the adhesive is composed of the following substances in weight percentage: 8% aziridine crosslinking agent, 1% epoxy silane modified SiO2 nanoparticles, 0.8% polyether modified polysiloxane leveling agent and the balance polyurethane modified acrylate.

[0086] As a specific embodiment of the present invention, the adhesive is composed of the following substances in weight percentage: 3% aziridine crosslinking agent, 5% epoxy silane modified SiO2 nanoparticles, 0.3% polyether modified polysiloxane leveling agent and the balance polyurethane modified acrylate.

[0087] Secondly, the present invention provides a method for preparing the above-mentioned double-layer PET composite material for photovoltaic front panels, comprising the following steps:

[0088] S1. PET surface modification: Carboxyl monomer vapor is introduced into the PET substrate, and radio frequency plasma grafting is performed for 1-5 minutes at a power of 100-300W and a pressure of 10-50Pa to obtain the modified PET substrate.

[0089] S2. Preparation of adhesive: Mix polyurethane modified acrylate, aziridine crosslinking agent and epoxy silane modified SiO2 nanoparticles, and ultrasonically disperse for 10-30 minutes to obtain adhesive;

[0090] S3. Composite: The modified surface of the PET substrate obtained in step S1 is coated with the adhesive obtained in step S2, and another layer of PET is laminated roll to roll; cured at 40-80℃ for 24-72 hours to obtain the composite substrate;

[0091] S4. Coat the outer surface of the composite substrate obtained in step S3 with a fluorine-containing coating and cure it to obtain a double-layer PET composite material for photovoltaic front panel.

[0092] In step S1, the power of the radio frequency plasma graft is selected from any value between 100-300W, such as the following values ​​or any range formed by both: 100W, 110W, 120W, 130W, 140W, 150W, 160W, 170W, 180W, 190W, 200W, 210W, 220W, 230W, 240W, 250W, 260W, 270W, 280W, 290W, 300W.

[0093] In one specific embodiment of the present invention, in step S1, the power of the radio frequency plasma grafting is 100W.

[0094] In one specific embodiment of the present invention, in step S1, the power of the radio frequency plasma grafting is 150W.

[0095] In step S1, the gas pressure for the radio frequency plasma grafting is selected from any value between 10 and 50 Pa, for example, the following values ​​or any range formed between the two: 10 Pa, 11 Pa, 12 Pa, 13 Pa, 14 Pa, 15 Pa, 16 Pa, 17 Pa, 18 Pa, 19 Pa, 20 Pa, 21 Pa, 22 Pa, 23 Pa, 24 Pa, 25 Pa, 26 Pa, 27 Pa, 28 Pa, 29 Pa, 30 Pa, 31 Pa, 32 Pa, 33 Pa, 34 Pa, 35 Pa, 36 Pa, 37 Pa, 38 Pa, 39 Pa, 40 Pa, 41 Pa, 42 Pa, 43 Pa, 44 Pa, 45 Pa, 46 Pa, 47 Pa, 48 Pa, 49 Pa, 50 Pa.

[0096] In one specific embodiment of the present invention, in step S1, the gas pressure of the radio frequency plasma graft is 10 Pa.

[0097] In one specific embodiment of the present invention, in step S1, the gas pressure of the radio frequency plasma graft is 40 Pa.

[0098] In step S1, the time for radio frequency plasma grafting is selected from any value between 1 and 5 minutes, such as the following values ​​or any range between the two: 1 minute, 2 minutes, 3 minutes, 4 minutes, and 5 minutes.

[0099] In one specific embodiment of the present invention, in step S1, the radio frequency plasma grafting time is 1 minute.

[0100] In one specific embodiment of the present invention, in step S1, the radio frequency plasma grafting time is 2 minutes.

[0101] In one specific embodiment of the present invention, the radio frequency plasma grafting time in step S1 is 4 minutes.

[0102] In one specific embodiment of the present invention, the radio frequency plasma grafting time in step S1 is 5 minutes.

[0103] In step S2, the ultrasonic dispersion time is any value between 10 and 30 minutes, such as the following values ​​or any range between the two: 10 minutes, 15 minutes, 20 minutes, 25 minutes, and 30 minutes.

[0104] In one specific embodiment of the present invention, in step S2, the ultrasonic dispersion time is 10 minutes.

[0105] In one specific embodiment of the present invention, in step S2, the ultrasonic dispersion time is 25 minutes.

[0106] In one specific embodiment of the present invention, in step S2, the ultrasonic dispersion time is 30 minutes.

[0107] In step S3, the curing temperature is selected from any value between 40-80℃, for example, the following values ​​or any range between them: 40℃, 41℃, 42℃, 43℃, 44℃, 45℃, 46℃, 47℃, 48℃, 49℃, 50℃, 51℃, 52℃, 53℃, 54℃, 55℃, 56℃, 57℃, 58℃, 59℃, 60℃, 61℃, 62℃, 63℃, 64℃, 65℃, 66℃, 67℃, 68℃, 69℃, 70℃, 71℃, 72℃, 73℃, 74℃, 75℃, 76℃, 77℃, 78℃, 79℃, 80℃.

[0108] In one specific embodiment of the present invention, in step S3, the curing temperature is 80°C.

[0109] In one specific embodiment of the present invention, in step S3, the curing temperature is 40°C.

[0110] In step S3, the curing time is selected from any value between 24 and 72 hours, such as the following values ​​or any range between the two: 24 hours, 25 hours, 26 hours, 27 hours, 28 hours, 29 hours, 30 hours, 31 hours, 32 hours, 33 hours, 34 hours, 35 hours, 36 hours, 37 hours, 38 hours, 39 hours, 40 hours, 41 hours, 42 hours, 43 hours, 44 hours, 45 hours, 46 hours, 47 hours, 48 ​​hours, 49 hours, 50 hours, 51 hours, 52 hours, 53 hours, 54 hours, 55 hours, 56 hours, 57 hours, 58 hours, 59 hours, 60 hours, 61 hours, 62 hours, 63 hours, 64 hours, 65 hours, 66 hours, 67 hours, 68 hours, 69 hours, 70 hours, 71 hours, and 72 hours.

[0111] In one specific embodiment of the present invention, the curing time in step S3 is 24 hours.

[0112] In one specific embodiment of the present invention, the curing time in step S3 is 72 hours.

[0113] Further, in step S2, the preparation method of the epoxy-silane modified SiO2 nanoparticles includes the following steps:

[0114] Fumed silica and γ-(2,3-epoxypropoxy)propyltrimethoxysilane were mixed at a mass ratio of 1:0.4-0.6; the mixture was refluxed in ethanol and then centrifuged and dried to obtain epoxysilane-modified SiO2 nanoparticles.

[0115] The mass ratio of fumed silica to γ-(2,3-epoxypropoxy)propyltrimethoxysilane is selected from any ratio between 1:0.4 and 0.6, for example, the following ratios or any range between the two: 1:0.40, 1:0.41, 1:0.42, 1:0.43, 1:0.44, 1:0.45, 1:0.46, 1:0.47, 1:0.48, 1:0.49, 1:0.50, 1:0.51, 1:0.52, 1:0.53, 1:0.54, 1:0.55, 1:0.56, 1:0.57, 1:0.58, 1:0.59, 1:0.60.

[0116] In one specific embodiment of the present invention, the mass ratio of the fumed silica to γ-(2,3-epoxypropoxy)propyltrimethoxysilane is 1:0.5.

[0117] Further, step S2 is as follows: polyurethane modified acrylate, aziridine crosslinking agent, polyether modified polysiloxane leveling agent and epoxy silane modified SiO2 nanoparticles are mixed and ultrasonically dispersed for 10-30 minutes to obtain adhesive.

[0118] Furthermore, in step S4, the curing is performed in an oven.

[0119] Furthermore, in step S4, the curing temperature is 100-160°C.

[0120] In step S4, the curing temperature is selected from any value between 100-160℃, such as the following values ​​or any range between the two: 100℃, 110℃, 120℃, 130℃, 140℃, 150℃.

[0121] In one specific embodiment of the present invention, in step S4, the curing temperature is 150°C.

[0122] Thirdly, the present invention provides the application of the above-mentioned double-layer PET composite material for photovoltaic front panels or the double-layer PET composite material for photovoltaic front panels prepared by the above-mentioned preparation method in the production of photovoltaic materials.

[0123] Furthermore, the photovoltaic material is a photovoltaic front panel.

[0124] Fourthly, the present invention provides a photovoltaic material, including the above-mentioned double-layer PET composite material for photovoltaic front panels or the double-layer PET composite material for photovoltaic front panels prepared by the above-mentioned preparation method.

[0125] Furthermore, the photovoltaic material is a photovoltaic front panel.

[0126] The beneficial effects of this invention include:

[0127] Compared with existing technologies, the present invention has better technical effects in terms of peel strength attenuation rate and light transmittance attenuation rate after aging.

[0128] According to experimental tests, the present invention reduces the peel strength decay rate of double-layer PET composite material after aging at 85℃ / 85%RH for 1000h from 22.86%-59.62% in the prior art to below 16.02%.

[0129] According to experimental tests, the present invention reduces the light transmittance aging decay rate of double-layer PET composite material after 1000 hours of 85℃ / 85%RH damp heat aging from 2.9%-12.3% in the prior art to below 2.8%. Attached Figure Description

[0130] Figure 1 This is a schematic diagram of the double-layer PET composite structure obtained in Example 1, where 1 represents the adhesive, 2 represents the PET substrate, and 3 represents the fluorine-containing coating.

[0131] Figure 2 This is a flowchart of the preparation of the bilayer PET composite structure in Example 1. Detailed Implementation

[0132] The following non-limiting embodiments are intended to enable those skilled in the art to gain a more comprehensive understanding of the present invention, but do not limit the invention in any way. The following content is merely an exemplary description of the scope of protection claimed by the present invention, and those skilled in the art can make various changes and modifications to the present invention based on the disclosed content, and such changes should also fall within the scope of protection claimed by the present invention.

[0133] The present invention will be further described below by way of specific embodiments. Unless otherwise specified, all instruments, devices, equipment, reagents, products, etc., used in the embodiments of the present invention are obtained through conventional commercial means.

[0134] Table 1 provides a non-limiting description of the raw materials used in the following specific embodiments.

[0135] Table 1

[0136]

[0137] Example 1

[0138] A double-layer PET composite material for photovoltaic front panels, the structural schematic diagram is as follows. Figure 1 As shown in the diagram. A schematic diagram of the preparation process is shown below. Figure 2 As shown. The preparation method is as follows:

[0139] S1. PET Surface Modification: A 250μm thick PET substrate was grafted using radio frequency plasma (100W, 10Pa). The PET substrate was placed in an radio frequency plasma device (frequency 13.56MHz), and acrylic acid vapor containing carboxyl monomers was introduced for 1 minute. The grafting rate was 5%. The modified PET substrate was obtained.

[0140] S2. Prepare adhesive.

[0141] Vaporized SiO2 (particle size 20 nm) was mixed with γ-(2,3-epoxypropoxy)propyltrimethoxysilane at a mass ratio of 1:0.5; the mixture was refluxed in ethanol solution at 80 °C for 4 hours, and then centrifuged and dried to obtain modified silica.

[0142] The epoxy group content of the modified silica was determined using a titration method described in existing technology.

[0143] The test results showed that the surface epoxy content of the modified silica was 1.4 mmol / g.

[0144] 92 parts by weight of polyurethane-modified acrylate, 5 parts by weight of aziridine crosslinking agent and 3 parts by weight of modified silica were mixed and ultrasonically dispersed for 10 minutes to obtain an adhesive.

[0145] S3. Take the modified PET substrate obtained in step S1, and apply the adhesive obtained in step S2 to the modified surface, with a coating thickness of 5 μm. Lay another layer of the modified PET substrate obtained in step S1 on a roll-to-roll composite, with the composite surface being the modified surface. After lamination, cure at 40°C for 24 hours to obtain the composite substrate.

[0146] S4. Coat the outer surface of the composite substrate obtained in step S3 with a high weather-resistant fluorine-containing coating with thicknesses of 3μm and 8μm on both sides, and cure it in an oven at 150℃ to obtain a double-layer PET composite material for photovoltaic front panels.

[0147] Example 2

[0148] A double-layer PET composite material for photovoltaic front panels is prepared as follows:

[0149] S1. PET Surface Modification: A 250μm thick PET substrate was grafted using radio frequency plasma (150W, 40Pa). The PET substrate was placed in an radio frequency plasma device (frequency 13.56MHz), and maleic anhydride vapor containing carboxyl monomers was introduced for 2 minutes. The grafting rate was 8.3%. The modified PET substrate was obtained.

[0150] S2. Prepare adhesive.

[0151] Vaporized SiO2 (particle size 20 nm) was mixed with γ-(2,3-epoxypropoxy)propyltrimethoxysilane at a mass ratio of 1:0.5; the mixture was refluxed in ethanol solution at 80 °C for 4 hours, and then centrifuged and dried to obtain modified silica.

[0152] Mix 89.5 parts by weight of polyurethane modified acrylate, 6 parts by weight of aziridine crosslinking agent, 4 parts by weight of modified silica, and 0.5 parts by weight of polyether modified polysiloxane leveling agent, and ultrasonically disperse for 30 minutes to obtain an adhesive.

[0153] S3. Take the modified PET substrate obtained in step S1, and coat the modified surface with the adhesive obtained in step S2, with a coating thickness of 30 μm. Lay another layer of the modified PET substrate obtained in step S1 on a roll-to-roll composite, with the composite surface being the modified surface. Cure at 80℃ for 24 hours after lamination to obtain the composite substrate.

[0154] S4. Coat the outer surface of the composite substrate obtained in step S3 with a high weather-resistant fluorine-containing coating with thicknesses of 5μm and 10μm on both sides, and cure it in an oven at 150℃ to obtain a double-layer PET composite material for photovoltaic front panels.

[0155] Example 3

[0156] A double-layer PET composite material for photovoltaic front panels is prepared as follows:

[0157] S1. PET Surface Modification: A 300μm thick PET substrate was grafted using radio frequency plasma (150W, 40Pa). The PET substrate was placed in an radio frequency plasma device (frequency 13.56MHz), and maleic anhydride vapor containing carboxyl monomers was introduced for 4 minutes. The grafting rate was 13%. The modified PET substrate was obtained.

[0158] S2. Prepare adhesive.

[0159] Vaporized SiO2 (particle size 20 nm) was mixed with γ-(2,3-epoxypropoxy)propyltrimethoxysilane at a mass ratio of 1:0.5; the mixture was refluxed in ethanol solution at 80 °C for 4 hours, and then centrifuged and dried to obtain modified silica.

[0160] 90.2 parts by weight of polyurethane modified acrylate, 8 parts by weight of aziridine crosslinking agent, 1 part by weight of modified silica, and 0.8 parts by weight of polyether modified polysiloxane leveling agent were mixed and ultrasonically dispersed for 25 minutes to obtain an adhesive.

[0161] S3. Take the modified PET substrate obtained in step S1, and coat the modified surface with the adhesive obtained in step S2, with a coating thickness of 20 μm. Lay another layer of the modified PET substrate obtained in step S1 on a roll-to-roll composite, with the composite surface being the modified surface. Cure at 40°C for 72 hours after lamination to obtain the composite substrate.

[0162] S4. Coat the outer surface of the composite substrate obtained in step S3 with a high weather-resistant fluorine-containing coating with thicknesses of 6μm and 15μm on both sides, and cure it in an oven at 150℃ to obtain a double-layer PET composite material for photovoltaic front panels.

[0163] Example 4

[0164] A double-layer PET composite material for photovoltaic front panels is prepared as follows:

[0165] S1. PET Surface Modification: A 250μm thick PET substrate was grafted using radio frequency plasma (150W, 40Pa). The PET substrate was placed in an radio frequency plasma device (frequency 13.56MHz), and acrylic acid vapor containing carboxyl monomers was introduced for 5 minutes. The grafting rate was 15%. The modified PET substrate was obtained.

[0166] S2. Prepare adhesive.

[0167] Vaporized SiO2 (particle size 20 nm) was mixed with γ-(2,3-epoxypropoxy)propyltrimethoxysilane at a mass ratio of 1:0.5; the mixture was refluxed in ethanol solution at 80 °C for 4 hours, and then centrifuged and dried to obtain modified silica.

[0168] Mix 91.7 parts by weight of polyurethane modified acrylate, 3 parts by weight of aziridine crosslinking agent, 5 parts by weight of modified silica, and 0.3 parts by weight of polyether modified polysiloxane leveling agent, and ultrasonically disperse for 30 minutes to obtain an adhesive.

[0169] S3. Take a piece of the modified PET substrate obtained in step S1, and coat the modified surface with the adhesive obtained in step S2, with a coating thickness of 50 μm. Roll-to-roll composite another layer of the modified PET substrate obtained in step S1, with the composite surface being the modified surface. After lamination, cure at 40℃ for 72 h to obtain the composite substrate.

[0170] S4. Coat the outer surface of the composite substrate obtained in step S3 with a high weather-resistant fluorine-containing coating with thicknesses of 10μm and 15μm on both sides, and cure it in an oven at 150℃ to obtain a double-layer PET composite material for photovoltaic front panels.

[0171] Comparative Example 1

[0172] Compared to Example 1, the only difference is that the PET substrate surface was not modified by radio frequency plasma grafting; all other aspects are the same. The specific preparation method of the double-layer PET composite material for photovoltaic front panels is as follows:

[0173] S1. Prepare adhesive.

[0174] Vaporized SiO2 (particle size 20 nm) was mixed with γ-(2,3-epoxypropoxy)propyltrimethoxysilane at a mass ratio of 1:0.5; the mixture was refluxed in ethanol solution at 80 °C for 4 hours, and then centrifuged and dried to obtain modified silica.

[0175] 92 parts by weight of polyurethane-modified acrylate, 5 parts by weight of aziridine crosslinking agent and 3 parts by weight of modified silica were mixed and ultrasonically dispersed for 10 minutes to obtain an adhesive.

[0176] S2. Apply the adhesive obtained in step S1 to an unmodified PET substrate, with a coating thickness of 5 μm. Lay another layer of unmodified PET substrate onto the substrate roll to roll. After lamination, cure at 40°C for 24 hours to obtain the composite substrate.

[0177] S3. Coat the outer surface of the composite substrate obtained in step S2 with a high weather-resistant fluorine-containing coating with thicknesses of 3μm and 8μm on both sides, and cure it in an oven at 150℃ to obtain a double-layer PET composite material for photovoltaic front panels.

[0178] Comparative Example 2

[0179] Compared with Example 1, the only difference is that in step S2, the modified silica component is omitted from the adhesive, and 95 parts by weight of polyurethane acrylate is used instead; all other steps are the same. The specific preparation method of the double-layer PET composite material for photovoltaic front panels is as follows:

[0180] S1. PET Surface Modification: A 250μm thick PET substrate was grafted using radio frequency plasma (100W, 10Pa). The PET substrate was placed in an radio frequency plasma device (frequency 13.56MHz), and acrylic acid vapor containing carboxyl monomers was introduced for 1 minute. The grafting rate was 5%. The modified PET substrate was obtained.

[0181] S2. Prepare adhesive.

[0182] Mix 95 parts by weight of polyurethane-modified acrylate and 5 parts by weight of aziridine crosslinking agent, and ultrasonically disperse for 10 minutes to obtain an adhesive.

[0183] S3. Take the modified PET substrate obtained in step S1, and apply the adhesive obtained in step S2 to the modified surface, with a coating thickness of 5 μm. Lay another layer of the modified PET substrate obtained in step S1 on a roll-to-roll composite, with the composite surface being the modified surface. After lamination, cure at 40°C for 24 hours to obtain the composite substrate.

[0184] S4. Coat the outer surface of the composite substrate obtained in step S3 with a high weather-resistant fluorine-containing coating with thicknesses of 3μm and 8μm on both sides, and cure it in an oven at 150℃ to obtain a double-layer PET composite material for photovoltaic front panels.

[0185] Comparative Example 3

[0186] Compared to Example 1, the only difference is that in step S1, a nitrogen:oxygen = 2:1 atmosphere is used for surface plasma treatment. The specific preparation method of the double-layer PET composite material for photovoltaic front panels is as follows:

[0187] S1. PET Surface Modification: A 250μm thick PET substrate was grafted using radio frequency plasma (100W, 10Pa). The PET substrate was placed in an radio frequency plasma device (frequency 13.56MHz) and subjected to surface plasma treatment with a nitrogen:oxygen = 2:1 atmosphere for 1 minute. The modified PET substrate was obtained.

[0188] S2. Prepare adhesive.

[0189] Vaporized SiO2 (particle size 20 nm) was mixed with γ-(2,3-epoxypropoxy)propyltrimethoxysilane at a mass ratio of 1:0.5; the mixture was refluxed in ethanol solution at 80 °C for 4 hours, and then centrifuged and dried to obtain modified silica.

[0190] 92 parts by weight of polyurethane-modified acrylate, 5 parts by weight of aziridine crosslinking agent and 3 parts by weight of modified silica were mixed and ultrasonically dispersed for 10 minutes to obtain an adhesive.

[0191] S3. Take the modified PET substrate obtained in step S1, and coat the modified surface with the adhesive obtained in step S2, with a coating thickness of 5 μm. Lay another layer of the modified PET substrate obtained in step S1 on a roll-to-roll composite, with the composite surface being the modified surface. After lamination, cure at 40°C for 24 hours to obtain the composite substrate.

[0192] S4. Coat the outer surface of the composite substrate obtained in step S3 with a high weather-resistant fluorine-containing coating with thicknesses of 3μm and 8μm on both sides, and cure it in an oven at 150℃ to obtain a double-layer PET composite material for photovoltaic front panels.

[0193] Comparative Example 4

[0194] Compared with Example 1, the only difference is that in step S2, the fumed silica used is replaced with needle-shaped silica; all other aspects are the same. The specific preparation method of the double-layer PET composite material for photovoltaic front panels is as follows:

[0195] S1. PET Surface Modification: A 250μm thick PET substrate was grafted using radio frequency plasma (100W, 10Pa). The PET substrate was placed in an radio frequency plasma device (frequency 13.56MHz), and acrylic acid vapor containing carboxyl monomers was introduced for 1 minute. The grafting rate was 5%. The modified PET substrate was obtained.

[0196] S2. Prepare adhesive.

[0197] Needle-shaped SiO2 (obtained by centrifugation and drying from SNOWTEX ST-PS-M) was mixed with γ-(2,3-epoxypropoxy)propyltrimethoxysilane at a mass ratio of 1:0.5; the mixture was refluxed in ethanol solution at 80°C for 4 hours, and then centrifuged and dried to obtain modified silica.

[0198] 92 parts by weight of polyurethane-modified acrylate, 5 parts by weight of aziridine crosslinking agent and 3 parts by weight of modified silica were mixed and ultrasonically dispersed for 10 minutes to obtain an adhesive.

[0199] S3. Take the modified PET substrate obtained in step S1, and coat the modified surface with the adhesive obtained in step S2, with a coating thickness of 5 μm. Lay another layer of the modified PET substrate obtained in step S1 on a roll-to-roll composite, with the composite surface being the modified surface. After lamination, cure at 40°C for 24 hours to obtain the composite substrate.

[0200] S4. Coat the outer surface of the composite substrate obtained in step S3 with a high weather-resistant fluorine-containing coating with thicknesses of 3μm and 8μm on both sides, and cure it in an oven at 150℃ to obtain a double-layer PET composite material for photovoltaic front panels.

[0201] Comparative Example 5

[0202] Compared with Example 1, the only difference is that in step S2, the silica is not modified, and the adhesive component is replaced with an equal weight of fumed silica; all other aspects remain the same. The specific preparation method of the double-layer PET composite material for photovoltaic front panels is as follows:

[0203] S1. PET Surface Modification: A 250μm thick PET substrate was grafted using radio frequency plasma (100W, 10Pa). The PET substrate was placed in an radio frequency plasma device (frequency 13.56MHz), and acrylic acid vapor containing carboxyl monomers was introduced for 1 minute. The grafting rate was 5%. The modified PET substrate was obtained.

[0204] S2. Prepare adhesive.

[0205] 92 parts by weight of polyurethane modified acrylate, 5 parts by weight of aziridine crosslinking agent and 3 parts by weight of fumed silica were mixed and ultrasonically dispersed for 10 minutes to obtain an adhesive.

[0206] S3. Take the modified PET substrate obtained in step S1, and coat the modified surface with the adhesive obtained in step S2, with a coating thickness of 5 μm. Lay another layer of the modified PET substrate obtained in step S1 on a roll-to-roll composite, with the composite surface being the modified surface. After lamination, cure at 40°C for 24 hours to obtain the composite substrate.

[0207] S4. Coat the outer surface of the composite substrate obtained in step S3 with a high weather-resistant fluorine-containing coating with thicknesses of 3μm and 8μm on both sides, and cure it in an oven at 150℃ to obtain a double-layer PET composite material for photovoltaic front panels.

[0208] Comparative Example 6

[0209] Compared to Example 1, the only difference is that in step S2, the surface modification of silica is changed from γ-(2,3-epoxypropoxy)propyltrimethoxysilane to an equal weight of APTES; all other steps are the same. The specific preparation method of the double-layer PET composite material for photovoltaic front panels is as follows:

[0210] S1. PET Surface Modification: A 250μm thick PET substrate was grafted using radio frequency plasma (100W, 10Pa). The PET substrate was placed in an radio frequency plasma device (frequency 13.56MHz), and acrylic acid vapor containing carboxyl monomers was introduced for 1 minute. The grafting rate was 5%. The modified PET substrate was obtained.

[0211] S2. Prepare adhesive.

[0212] Vaporized SiO2 (particle size 20 nm) was mixed with 3-aminopropyltriethoxysilane (APTES) at a mass ratio of 1:0.5; the mixture was refluxed in an ethanol solution at 80 °C for 4 hours, and then centrifuged and dried to obtain modified silica.

[0213] 92 parts by weight of polyurethane-modified acrylate, 5 parts by weight of aziridine crosslinking agent and 3 parts by weight of modified silica were mixed and ultrasonically dispersed for 10 minutes to obtain an adhesive.

[0214] S3. Take the modified PET substrate obtained in step S1, and apply the adhesive obtained in step S2 to the modified surface, with a coating thickness of 5 μm. Lay another layer of the modified PET substrate obtained in step S1 on a roll-to-roll composite, with the composite surface being the modified surface. After lamination, cure at 40°C for 24 hours to obtain the composite substrate.

[0215] S4. Coat the outer surface of the composite substrate obtained in step S3 with a high weather-resistant fluorine-containing coating with thicknesses of 3μm and 8μm on both sides, and cure it in an oven at 150℃ to obtain a double-layer PET composite material for photovoltaic front panels.

[0216] Comparative Example 7

[0217] Compared with Example 1, the only difference is that step S2 is omitted, and the adhesive used in step S3 is the adhesive of sample 3A in Example 3 of prior art CN101646739A. The specific preparation method of the double-layer PET composite material for photovoltaic front panel is as follows:

[0218] S1. PET Surface Modification: A 250μm thick PET substrate was grafted using radio frequency plasma (100W, 10Pa). The PET substrate was placed in an radio frequency plasma device (frequency 13.56MHz), and acrylic acid vapor containing carboxyl monomers was introduced for 1 minute. The grafting rate was 5%. The treated PET substrate was obtained.

[0219] S2. Take the modified PET substrate obtained in step S1, and coat the modified surface with the adhesive of sample 3A from Example 3 in CN101646739A, with a coating thickness of 5μm. Lay another layer of the modified PET substrate obtained in step S1 on a roll-to-roll composite, with the composite surface being the modified surface. After lamination, cure at 40℃ for 24 hours to obtain the composite substrate.

[0220] S3. Coat the outer surface of the composite substrate obtained in step S2 with a high weather-resistant fluorine-containing coating with thicknesses of 3μm and 8μm on both sides, and cure it in an oven at 150℃ to obtain a double-layer PET composite material for photovoltaic front panels.

[0221] Detection Example 1

[0222] Peel strength test.

[0223] The peel strength of the double-layer PET composite structures for photovoltaic front panels obtained in each embodiment and comparative example was tested using the method of IEC 62788-2-1:2023. Then, the double-layer PET composite structures for photovoltaic front panels obtained in each embodiment and comparative example were subjected to damp heat aging at 85°C / 85%RH for 1000 hours. After aging, the peel strength of the double-layer PET composite structures for photovoltaic front panels obtained in each embodiment and comparative example was tested using the same method, and the peel strength decay rate after aging was calculated.

[0224] The rate of decrease in peel strength after aging (%) = (initial peel strength - peel strength after aging) ÷ initial peel strength × 100%.

[0225] The test results are summarized in Table 2 below.

[0226] Table 2

[0227]

[0228] It is evident that the various embodiments provided by the present invention have better anti-aging performance and a lower peel strength attenuation rate after aging, reaching 13.87%-16.02%.

[0229] Detection Example 2

[0230] Transmittance testing.

[0231] The light transmittance of the double-layer PET composite structures for photovoltaic front panels obtained in each embodiment and comparative example was tested using the method of IEC 62788-2-1:2023. Then, the double-layer PET composite structures for photovoltaic front panels obtained in each embodiment and comparative example were subjected to damp heat aging at 85°C / 85%RH for 1000 hours. After aging, the light transmittance of the double-layer PET composite structures for photovoltaic front panels obtained in each embodiment and comparative example was tested using the same method.

[0232] Transmittance aging attenuation rate = (1 - transmittance after aging ÷ transmittance before aging) × 100%.

[0233] The test results are summarized in Table 3 below.

[0234] Table 3

[0235]

[0236] It can be seen that the light transmittance aging degradation of the double-layer PET composite material provided in the various embodiments of the present invention is lower, reaching 1.9%-2.8%.

[0237] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, and is not intended to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention do not depart from the essence and scope of the technical solution of the present invention.

Claims

1. A double-layer PET composite material for photovoltaic front panels, characterized in that, It includes two PET substrates, an adhesive layer and a fluorinated coating. The two PET substrates are laminated and bonded together by the adhesive layer. At least one side of the outer side of the two PET substrates is coated with a fluorinated coating. At least one PET substrate layer has a grafting surface at the contact surface with the adhesive layer. The grafting surface is a grafting surface with carboxyl monomers grafted by radio frequency plasma, and the grafting rate is 5%-15%. The adhesive comprises: (a) Polyurethane-modified acrylate; (b) Aziridine crosslinking agent comprising 3%-8% of the total weight of the adhesive; and (c) 1%-5% by weight of epoxy silane-modified SiO2 nanoparticles; The epoxy silane is γ-(2,3-epoxypropoxy)propyltrimethoxysilane, and the epoxy silane-modified SiO2 nanoparticles are made of fumed silica nanoparticles with an average particle size of 20-50 nm and a surface epoxy content of ≥0.8 mmol / g.

2. The double-layer PET composite material for photovoltaic front panels according to claim 1, characterized in that, The thickness of each of the two PET substrate layers is independently selected from 200-300μm; the light transmittance of each PET substrate layer is >90%, and the haze is <1%; the thickness of the fluorine-containing coating is 3-15μm / layer, and the thickness of the adhesive layer is 5-50μm.

3. The double-layer PET composite material for photovoltaic front panels according to claim 1, characterized in that, The carboxyl-containing monomer is selected from acrylic acid or maleic anhydride.

4. The double-layer PET composite material for photovoltaic front panels according to claim 1, characterized in that, The adhesive also includes 0.3%-0.8% polyether-modified polysiloxane leveling agent by weight of the total adhesive.

5. The method for preparing the double-layer PET composite material for photovoltaic front panels according to any one of claims 1-4, characterized in that, Includes the following steps: S1. PET surface modification: Carboxyl monomer vapor is introduced into the PET substrate, and radio frequency plasma grafting is performed for 1-5 minutes at a power of 100-300W and a pressure of 10-50Pa to obtain the modified PET substrate. S2. Preparation of adhesive: Mix polyurethane modified acrylate, aziridine crosslinking agent and epoxy silane modified SiO2 nanoparticles, and ultrasonically disperse for 10-30 minutes to obtain adhesive; S3. Composite: The modified surface of the PET substrate obtained in step S1 is coated with the adhesive obtained in step S2, and another layer of PET is laminated roll to roll; cured at 40-80℃ for 24-72 hours to obtain the composite substrate; S4. Coat the outer surface of the composite substrate obtained in step S3 with a fluorine-containing coating and cure it to obtain a double-layer PET composite material for photovoltaic front panel.

6. The preparation method according to claim 5, characterized in that, In step S2, the preparation method of the epoxy-silane modified SiO2 nanoparticles includes the following steps: Fumed silica and γ-(2,3-epoxypropoxy)propyltrimethoxysilane were mixed at a mass ratio of 1:0.4-0.6; the mixture was refluxed in ethanol and then centrifuged and dried to obtain epoxysilane-modified SiO2 nanoparticles.

7. The preparation method according to claim 5, characterized in that, Step S2 is as follows: mix polyurethane modified acrylate, aziridine crosslinking agent, polyether modified polysiloxane leveling agent and epoxy silane modified SiO2 nanoparticles, and ultrasonically disperse for 10-30 minutes to obtain adhesive.

8. The application of the double-layer PET composite material for photovoltaic front panels as described in any one of claims 1-4 or the double-layer PET composite material for photovoltaic front panels prepared by the preparation method described in any one of claims 5-7 in the production of photovoltaic materials.

9. A photovoltaic material, characterized in that, This includes the double-layer PET composite material for photovoltaic front panels as described in any one of claims 1-4, or the double-layer PET composite material for photovoltaic front panels prepared by the preparation method described in any one of claims 5-7.

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