Thermoplastic composite for photovoltaic front sheets

Abstract

The application discloses a thermoplastic composite material for a photovoltaic front plate, glass fibers coated with a thermoplastic resin emulsion are dispersed by vibration, and then impregnated with a thermoplastic resin melt in an impregnation mold cavity; 0.5-5 parts of a glass fiber dispersing agent is used to further disperse the glass fibers in the melt, thereby improving the light transmittance consistency of the material; a nucleating agent is used to control the crystallization behavior of the resin matrix, thereby further improving the light transmittance of the material; and compounded anti-aging additives can maintain long-term operation of the material under light conditions. The material has strong designability; according to the requirements of light transmittance and strength, different resin combinations can be selected, and the number of layers and the angle of the layers can be adjusted to realize strengthening in a specific direction.

Description

Technical Field

[0001] This invention relates to a continuous fiber-reinforced thermoplastic composite material for manufacturing the front panel of a photovoltaic module, belonging to the field of novel polymer materials and their applications. Background Technology

[0002] The photovoltaic industry originated from the photovoltaic effect, which refers to a power generation system that directly converts solar radiation energy into electrical energy using the photovoltaic effect of photovoltaic cells. However, individual photovoltaic cells have poor mechanical strength, are very thin and easily broken. If exposed to air for a long time, their conversion efficiency will drop sharply due to external factors such as humidity, dust, hail, and sandstorms, and they are also prone to corrosion, causing cell failure. In addition, the output voltage and power of individual cells are relatively small. In order to obtain a continuous and usable power source, several individual cells must be connected in series and parallel and tightly packaged into photovoltaic modules (also called solar panels).

[0003] After the battery array is assembled and connected, it is sealed between the front panel and the back panel using encapsulation material. The encapsulation panel material is photovoltaic glass, which serves as the cover for the photovoltaic cells, allowing light to pass through and protecting the cells. Its main indicators are light transmittance and intensity. With the expansion of application scenarios, the front cover of photovoltaic cells is trending towards thinner and lighter designs. However, this rigid component is still relatively heavy and requires support brackets during installation.

[0004] In recent years, flexible photovoltaic (PV) modules have developed rapidly. They are about 80% lighter than rigid modules, and are flexible and portable, making them widely used in solar backpacks, solar awnings, solar flashlights, solar cars, solar sailboats, and even solar airplanes. Another important application area for flexible PV modules is BIPV (Building Integrated Photovoltaics), which can be integrated into windows or roofs, exterior or interior walls, and has a very broad development prospect.

[0005] To achieve flexibility, the front cover of the photovoltaic cell also needs to be made of a flexible material. Patent CN102945879 B discloses a high-transmittance, lightweight photovoltaic module and its preparation method, using PMMA, PC, or a mixture of both as the high-transmittance, lightweight polymer material layer to replace traditional tempered glass. This eliminates the need for an aluminum frame, significantly reducing the overall weight of the photovoltaic module and facilitating transport and assembly. Patent CN 107994092 A discloses a flexible photovoltaic module comprising, from bottom to top, an aluminum alloy backsheet layer, a first encapsulation film layer, a TPT backsheet layer, a second encapsulation film layer, a solar cell layer, a third encapsulation film layer, and a PET layer. The encapsulation film layer is mainly composed of thermosetting resins such as epoxy resin, toughening agent, and curing agent. The resulting module is flexible and bendable, and can be installed on any irregular object or building surface according to user needs without affecting the aesthetics of the original building or object, thus well meeting the needs of practical applications. The two patents mentioned above use thermoplastic and thermosetting pure resins as front panel materials, respectively, which have poor strength and are easily damaged by severe weather such as hail. Patent CN 110620161 A discloses a lightweight flexible photovoltaic module, which, from top to bottom, includes a PVF film layer, a composite fiberglass layer, a battery string, and an FFC double-sided fluorinated backsheet. The PVF film layer is connected to the composite fiberglass layer, the composite fiberglass layer is connected to the battery string, and the battery string is connected to the FFC double-sided fluorinated backsheet through an EVA film. Although this solution adds a composite fiberglass layer, which improves the strength of the front panel to some extent, the fiberglass inside the fiberglass layer is not impregnated during the re-lamination process. This may not only reduce the light transmittance of the front panel but also fail to effectively disperse stress when the module is subjected to external impact. Summary of the Invention

[0006] To overcome the shortcomings of existing technologies, this invention provides a lightweight, high-strength, high-impact, high-transmittance, and bendable continuous glass fiber reinforced thermoplastic composite material sheet, which can be applied to photovoltaic front panels. It can solve the problems of traditional glass being heavy and inflexible, and also improve the strength of photovoltaic front panels, expanding the application scenarios of lightweight and flexible photovoltaic modules.

[0007] A thermoplastic composite material for photovoltaic front panels, comprising, by weight:

[0008] 100 parts of thermoplastic resin

[0009] Continuous glass fiber 50-180 parts

[0010] Glass fiber dispersant 0.5-5 parts

[0011] 0-5 parts compatibilizer

[0012] 0-2 parts of nucleating agent

[0013] 0.2-3 parts lubricant

[0014] Anti-aging adjuvant 0.3-3 parts

[0015] The thermoplastic resin is one or more of PC, PMMA, PET, and PP. The resin must be selected from high-transmittance grades with a transmittance ≥80%.

[0016] The continuous glass fiber yarn can be made of alkali-free E glass, high-modulus M glass, or high-strength S glass, with a surface coating of coupling agent, film-forming agent, emulsifier, etc., and a total volatile matter content of more than 1.0%. The emulsifier contains corresponding thermoplastic resin powder, with a powder content of 20-40%. The powder is made by grinding a thermoplastic resin matrix into a particle size of less than 50 μm after liquid nitrogen quenching. The glass fiber monofilament diameter is 8-20 μm; preferably, to improve the dispersibility of the glass fiber, glass fiber with a diameter of 15-20 μm is selected as the raw material.

[0017] The dispersion of glass fiber in composite materials directly affects light transmittance. Unevenly dispersed glass fibers cause differences in light transmittance at different locations in the material, thus affecting the power generation efficiency of photovoltaic modules. Adding a glass fiber dispersant can improve the dispersion effect. This dispersant is a near-spherical particle, such as glass microspheres, calcium carbonate, or barium sulfate, with glass microspheres (preferably with higher transparency) added at 0.5-5 parts. Further preferred is 800-mesh calcium carbonate, added at 0.5-1 parts. The spherical particles prevent glass fiber monofilament overlap, promote fiber "flattening" during fiber movement, and reduce the tension required for fiber dispersion, thereby reducing fiber fuzz and its impact on material transmittance.

[0018] The thermoplastic resin mixture or resins with poor polarity, such as PP, need to add compatibilizers to the formulation, such as PP-g-GMA, PP-g-GMA, POE-g-MAH, PE-g-MAH, styrene-acrylate functional copolymers, ethylene-methyl acrylate-glycidyl methacrylate terpolymers, etc., with an addition amount of 0-5 parts.

[0019] The formulations containing thermoplastic resins PET and PP also require the addition of nucleating agents to control crystallization behavior and adjust the light transmittance of the material. The nucleating agents include sodium succinate, sodium glutarate, sodium hexanoate, potassium benzoate, lithium benzoate, sodium cinnamate, sodium β-naphthoate, phosphate metal salts, dibenzyl sorbitol (DBS), di(p-methylbenzyl)sorbitol (PM-DBS), polyvinylcyclohexane, polyvinylpentane, ethylene / acrylate copolymer, etc., with an addition amount of 0-2 parts.

[0020] The lubricant is used to improve the dispersion effect of glass fiber and increase the fluidity of resin melt, thereby obtaining better wetting effect and light transmittance. It is mainly composed of fatty acids, hydrocarbon waxes, silicone or polytetrafluoroethylene, and the addition amount is 0.2-3 parts.

[0021] Photovoltaic front panels are exposed to direct sunlight for extended periods, and therefore must possess excellent aging resistance to meet usage requirements. An aging-resistant transparent varnish can be applied to the panel surface. A preferred approach is to add long-term anti-aging additives to the resin formulation. These additives are combinations of various phosphorus-based antioxidants, phenolic antioxidants, sulfur-based antioxidants, salicylates, benzophenones, benzotriazoles, organic complexes of nickel and cobalt, and hindered amine light stabilizers, added at amounts of 0.3-3 parts.

[0022] This invention also provides a method for preparing continuous glass fiber reinforced thermoplastic composite material sheets. The technical solution involves dispersing surface-treated continuous glass fiber yarn through various methods such as spreading rollers and vibrating rollers, preheating it, and then inserting several glass fibers side-by-side into an impregnation tank. At the other end, an extruder continuously feeds a formulation containing thermoplastic resin and additives into the impregnation tank in molten form. Inside the impregnation tank, nitrogen gas is continuously injected into the mold to prevent the resin melt from oxidizing and discoloring, thus reducing the material's light transmittance. The special structure of the equipment further disperses the glass fiber bundles, and the combined effect of the melt's own fluidity and the internal pressure of the mold cavity promotes rapid impregnation between the glass fiber filaments, achieving thorough impregnation. The glass fibers are not sheared during impregnation and remain completely continuous, oriented in the direction of travel. After subsequent flattening and cooling processes, a highly transparent thin strip material is formed. This strip material has high strength along the length of the glass fiber, but lower strength perpendicular to the length of the glass fiber. When used, it can be laid in a single direction or in multiple directions to achieve the required mechanical properties, depending on the reinforcement requirements.

[0023] Compared with the prior art, the advantages of the present invention include:

[0024] 1. Melt impregnation technology is used to achieve monofilament impregnation of glass fibers, resulting in uniform dispersion of glass fibers in the resin and improving the light transmittance of the material;

[0025] 2. Continuous fiber reinforced thermoplastic composites have extremely high strength, with a fiber direction tensile strength of up to 1000MPa. Under the same strength requirements, the thickness and weight of the front panel can be greatly reduced.

[0026] 3. High design flexibility: Based on the requirements of light transmittance and strength, not only can different resin combinations be selected, but reinforcement in a specific direction can also be achieved by adjusting the number of layers and angles of the layup. Detailed Implementation

[0027] To better understand the purpose, technical solution, and advantages of this invention, the following detailed description will be provided using implementation examples.

[0028] Example 1

[0029] 100 parts of PC resin (Chimei PC122), glass microspheres, and other additives were premixed at high speed according to the proportion (see Table 1) and then added to a twin-screw extruder. After being preheated by emulsion-coated 600Tex glass fiber (Owens Corning SE-4805), the mixture was fed into the impregnation die. The temperature of the impregnation die was set to 260℃. After cooling, shaping, and flattening, the relevant properties were tested (see Table 2).

[0030] Example 2

[0031] 100 parts of PMMA resin (Chimei CM211), glass microspheres, and other additives were premixed at high speed according to the proportion (see Table 1) and then added to a twin-screw extruder. After being preheated by emulsion-coated 600Tex glass fiber (Owens Corning SE-4805), the mixture was fed into the impregnation die. The temperature of the impregnation die was set to 210℃. After cooling, shaping, and flattening, the mixture was then laminated in a 0 / 90 layer using a press at 210℃. The relevant properties were then tested (see Table 2).

[0032] Example 3

[0033] 100 parts of high-transparency PP resin (Maoming MT60), glass microspheres, and other additives were premixed at high speed according to the proportion (see Table 1) and then added to a twin-screw extruder. After being preheated by emulsion-coated 600Tex glass fiber (Owens Corning SE-4805), the mixture was fed into the impregnation die. The temperature of the impregnation die was set at 230℃. After cooling, shaping, and flattening, the mixture was then laminated in a 0 / 90 layer using a press at 230℃. The relevant properties were then tested (see Table 2).

[0034] Example 4

[0035] 100 parts of high-transparency PP resin (Maoming MT60), glass microspheres, and other additives were premixed at high speed according to the proportion (see Table 1) and then added to a twin-screw extruder. After being preheated by emulsion-coated 600Tex glass fiber (Owens Corning SE-4805), the mixture was fed into the impregnation die. The temperature of the impregnation die was set at 230℃. After cooling, shaping, and flattening, the mixture was then laminated in a 0 / 90 / 0 layer using a press at 230℃. The relevant properties were then tested (see Table 2).

[0036] Example 5

[0037] 100 parts of high-transparency PP resin (Maoming MT60), 800-mesh calcium carbonate, and other additives were premixed at high speed according to the proportions (see Table 1) and then added to a twin-screw extruder. After being preheated by emulsion-coated 600Tex glass fiber (Owens Corning SE-4805), the mixture was fed into the impregnation die. The temperature of the impregnation die was set at 230℃. After cooling, shaping, and flattening, the mixture was then laminated in a 0 / 90 layer using a press at 230℃. The relevant properties were then tested (see Table 2).

[0038] Example 6

[0039] 100 parts of high-transparency PP resin (Maoming MT60), 3000 mesh calcium carbonate, and other additives were premixed at high speed according to the proportions (see Table 1) and then added to a twin-screw extruder. After being preheated by emulsion-coated 600Tex glass fiber (Owens Corning SE-4805), the mixture was fed into the impregnation die. The temperature of the impregnation die was set at 230℃. After cooling, shaping, and flattening, the mixture was then laminated in a 0 / 90 layer using a press at 230℃. The relevant properties were then tested (see Table 2).

[0040] Example 7

[0041] 100 parts of high-transparency PP resin (Maoming MT60), 800-mesh calcium carbonate, and other additives were premixed at high speed according to the proportions (see Table 1) and then added to a twin-screw extruder. After being preheated by emulsion-coated 600Tex glass fiber (Owens Corning SE-4805), the mixture was fed into the impregnation die. The temperature of the impregnation die was set at 230℃. After cooling, shaping, and flattening, the mixture was then laminated in a 0 / 90 layer using a press at 230℃. The relevant properties were then tested (see Table 2).

[0042] The materials used in the embodiments have good mechanical properties, high light transmittance, and are bendable, making them a preferred option for the front panel of lightweight flexible photovoltaic modules.

[0043] Table 1

[0044] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Chimei PC-PC122 100 Chimei PMMA-CM211 100 Maoming PP-MT60 100 100 100 100 100 SE4805-600Tex 150 150 150 150 150 150 150 Sovitec050-20-215 glass microspheres 3 2 1 1 800 mesh calcium carbonate 1 2 3000 mesh calcium carbonate 1 Compatibilizer Bondyram 1001 4 4 4 4 4 Nucleating agent NX8000i 0.5 0.5 0.5 0.5 0.5 Lubricant WS-3100 0.8 0.8 0.5 0.5 0.5 0.5 0.5 Anti-aging additive B215 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Anti-aging additive TINUVIN 783 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Processing temperature 260 210 230 230 230 230 230 Layering 0 0 / 90 0 / 90 0 / 90 / 0 0 / 90 0 / 90 0 / 90

[0045] Table 2

[0046] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 0° tensile strength, MPa 960 335 379 525 388 371 371 0° tensile modulus, GPa 22 17 15 17 16 14 14 Double 85 aging time (tensile strength retention rate of 85%), h ＞1000 ＞1000 ＞1000 ＞1000 ＞1000 ＞1000 ＞1000 Light transmittance, % 85 92 90 81 92 88 85

[0047] Comparing Examples 3 and 5-7, calcium carbonate with a lower mesh size can achieve better light transmittance when added in a low proportion.

[0048] It will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A thermoplastic composite material for photovoltaic front panels, characterized in that, By weight, the material composition includes: 100 parts of thermoplastic resin Continuous glass fiber 50-180 parts Glass fiber dispersant 0.5-1 part 0-5 parts compatibilizer 0-2 parts of nucleating agent 0.2-3 parts lubricant Anti-aging adjuvant 0.3-3 parts; The thermoplastic resin is one or more of PC, PMMA, PET, and PP, and the resin must be selected from high-transmittance grades with a transmittance ≥80%. The glass fiber dispersant is 800-mesh calcium carbonate; The diameter of the continuous glass fiber monofilament is 15-20 μm.

2. The thermoplastic composite material for photovoltaic front panels according to claim 1, characterized in that, The continuous glass fiber is made of alkali-free E glass, high-modulus M glass, and high-strength S glass, and its surface is coated with coupling agent, film-forming agent, and emulsifier, with a total volatile matter content of more than 1.0%.

3. The thermoplastic composite material for photovoltaic front panels according to claim 1, characterized in that, The compatibilizer is one or more of PP-g-GMA, POE-g-MAH, PE-g-MAH, styrene-acrylate functional copolymers, and ethylene-methyl acrylate-glycidyl methacrylate terpolymers.

4. The thermoplastic composite material for photovoltaic front panels according to claim 1, characterized in that, The lubricant is one or more of fatty acids, hydrocarbon waxes, silicone, and polytetrafluoroethylene.

5. The thermoplastic composite material for photovoltaic front panels according to claim 1, characterized in that, The anti-aging additives are two or more of the following: phosphorus antioxidants, phenolic antioxidants, sulfur antioxidants, salicylates, benzophenones, benzotriazoles, organic complexes of nickel and cobalt, and hindered amine light stabilizers.