Composite material and integrated front plate for light photovoltaic module and preparation method of composite material and integrated front plate

Abstract

The invention relates to the technical field of photovoltaic module packaging materials, in particular to a composite material and an integrated front plate for a light photovoltaic module and a preparation method of the composite material and the integrated front plate. The composite material for the light photovoltaic module comprises a glass fiber reinforced framework and a composite resin matrix, wherein the composite resin matrix is infiltrated in the glass fiber reinforced framework; the raw materials of the composite resin matrix comprise organic silicon and a polyurethane prepolymer, and the organic silicon is hydroxyl type organic silicon of which the number-average molecular weight is less than or equal to 2000 and / or isocyanate group type organic silicon of which the number-average molecular weight is more than or equal to 2000. The composite material for the light photovoltaic module and the integrated front plate provided by the invention can effectively solve the problems of poor wettability, insufficient light transmittance, yellowing and poor weather resistance of the traditional glass fiber reinforced composite material in the application of the photovoltaic front plate, and ensure the reliability and power generation stability of the module in long-term outdoor use.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic module encapsulation materials technology, and in particular to a lightweight composite material for photovoltaic modules and an integrated front panel, as well as a method for preparing the same. Background Technology

[0002] With the rapid development of the photovoltaic industry, the application of distributed photovoltaics is becoming increasingly widespread. Traditional photovoltaic modules typically use tempered glass as the front and back panels, along with aluminum frames, resulting in heavy modules and high requirements for the load-bearing capacity of the roof, limiting their application in some older factories and residential buildings. To solve the weight problem of photovoltaic modules, frameless lightweight modules have emerged on the market. To achieve both lightweight and high strength, some lightweight encapsulation solutions use resin and fiber composites, but these solutions suffer from problems such as low light transmittance, poor weather resistance, and deterioration of interface performance. Specifically, the refractive index mismatch between the resin and glass fiber leads to poor interface wetting, resulting in severe light scattering; the resin has poor UV resistance, and after long-term outdoor use, it yellows severely, causing a sharp drop in light transmittance and a decrease in module output power; in humid and hot environments, the resin-glass fiber interface is easily damaged, leading to product delamination and performance failure. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention provides an integrated front panel for lightweight photovoltaic modules and its manufacturing method. The lightweight photovoltaic module composite material and integrated front panel provided by this invention effectively solve the problems of poor wettability, insufficient light transmittance, yellowing, and poor weather resistance inherent in traditional glass fiber reinforced composite materials used in photovoltaic front panels. This ensures the reliability and power generation stability of the module under long-term outdoor use.

[0004] In a first aspect, the present invention provides a lightweight photovoltaic module composite material, comprising: a glass fiber reinforced skeleton and a composite resin matrix, wherein the composite resin matrix is ​​impregnated in the glass fiber reinforced skeleton; the raw materials of the composite resin matrix include organosilicon and polyurethane prepolymer, wherein the organosilicon is a hydroxyl-type organosilicon with a number average molecular weight ≤2000 and / or an isocyanate-type organosilicon with a number average molecular weight ≥2000. The lightweight photovoltaic module composite material provided by the present invention uses polyurethane resin as the resin matrix, whose refractive index is closer to that of glass fiber. Simultaneously, it employs a composite modification of low molecular weight hydroxyl-type organosilicon and high molecular weight isocyanate-type organosilicon, improving the overall performance in terms of light transmittance, yellowing resistance, and wettability. Through the bridging effect of the organosilicon, the interfacial bonding force between the polyurethane resin and the glass fiber is strengthened.

[0005] Preferably, the hydroxyl-type organosilicon is hydroxyl-terminated polydimethylsiloxane; the isocyanate-type organosilicon is isocyanate-terminated polydimethylsiloxane.

[0006] Preferably, the number average molecular weight of the hydroxyl-terminated polydimethylsiloxane is 500-10000, more preferably 500-2000; and the number average molecular weight of the isocyanate-terminated polydimethylsiloxane is 2000-10000, more preferably 5000-8000.

[0007] In this invention, polyurethane is used as the matrix resin, and specific low molecular weight hydroxyl-terminated polydimethylsiloxane and high molecular weight isocyanate-terminated polydimethylsiloxane are introduced for composite modification, which is beneficial to further improve the comprehensive properties such as light transmittance, yellowing resistance and wettability.

[0008] Further preferably, the organosilicon accounts for 5% to 20% of the total mass of the polyurethane prepolymer, for example, 9% to 11%, 6%, 8%, 9%, 10%, 11%, 12%, 15%, 18%, etc., preferably 9% to 11%, and most preferably 10%; and / or, the mass ratio of the hydroxyl-type organosilicon to the isocyanate-type organosilicon is 0 to 10:0 to 10, preferably 3 to 7:3 to 7; for example, 1:9, 2:8, 3:7, 4:6, 1:1, etc.

[0009] The photovoltaic front panel provided by this invention features high light transmittance, resistance to yellowing, high wettability, and strong weather resistance. By adding different types and molecular weights of organosilicon prepolymers to modify polyurethane, the yellowing of the material is effectively suppressed. At the same time, it can significantly reduce the hygroscopicity of the resin and enhance the hydrolysis resistance of the interface, enabling the product to maintain excellent performance in high temperature and high humidity environments. Especially under the above-mentioned preferred ratio, it can greatly improve light transmittance, resistance to yellowing, and wettability, making it more suitable for the front-end encapsulation of lightweight photovoltaic modules and a good replacement for the front glass of traditional photovoltaic modules.

[0010] Preferably, the polyurethane prepolymer is an isocyanate-terminated polyurethane prepolymer. The isocyanate-terminated polyurethane resin used in this invention has a refractive index closer to that of glass fiber. Combined with the excellent wettability of organosilicon, it reduces interfacial scattering loss of light, enabling the light transmittance of the composite material to reach over 90%.

[0011] Preferably, the preparation of the isocyanate-terminated polyurethane prepolymer comprises: mixing a polyol, an isocyanate, and a catalyst, and heating the mixture under an inert atmosphere; the polyol is preferably selected from one or more of polyester polyols, polycaprolactone polyols, polycarbonate polyols, dimer acid-modified polyester polyols, and polyether polyols; the molecular weight of the polyol is 500-5000; the isocyanate is preferably selected from one or more of trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, octamethylene diisocyanate, trimethylhexane diisocyanate, tetramethylhexane diisocyanate, decamethylene diisocyanate, dodecamethylene diisocyanate, isophorone diisocyanate, toluene diisocyanate, diphenylmethane-2,4'-diisocyanate, and diphenylmethane-4,4'-diisocyanate; the catalyst is preferably dibutyltin dilaurate.

[0012] More preferably, the heating reaction temperature is 75~85℃, the reaction time is 2~4h, and the inert atmosphere includes nitrogen or argon.

[0013] Preferably, the mass ratio of the polyol, isocyanate and catalyst is 70~90:10~30:0.1~0.5.

[0014] Preferably, the process further includes vacuum dehydrating the polyol and organic solvent separately before mixing, wherein the vacuum dehydration temperature is 110~120℃ and the time is 1.5~2h.

[0015] Secondly, the present invention provides a method for preparing the composite material for lightweight photovoltaic modules, comprising: 1) The polyurethane prepolymer is mixed with the organosilicon and reacted. The reaction is terminated when the NCO% content reaches 9%~11%, preferably 10%. An organic solvent is added to dilute the mixture to obtain a resin solution.

[0016] 2) The glass fiber reinforced skeleton is impregnated into the resin solution, and then squeezed and semi-cured.

[0017] Preferably, in step 1), the viscosity of the resin solution is 200~500 mPa·s, the solid content is 40%~50%, and the organic solvent used for dilution is selected from one or more of acetone, butanone, ethyl acetate, butyl acetate, N,N-dimethylformamide, and tetrahydrofuran.

[0018] Preferably, in step 2), the glass fiber reinforcing skeleton is alkali-free glass fiber with a surface treated with a silane coupling agent, and the glass fiber reinforcing skeleton has a basis weight of 100~200 g / m². 2The extrusion coating is performed by roller extrusion coating with a pressure of 10~50 N / cm. The semi-curing treatment is performed by baking at 70~90℃ for 5~15 min to make the resin solution reach a touch-dry state, thus obtaining a semi-cured sheet.

[0019] Thirdly, the present invention provides an integrated front panel for lightweight photovoltaic modules, comprising a fiberglass resin composite layer, wherein the fiberglass resin composite layer uses a lightweight photovoltaic module composite material prepreg prepared by the aforementioned method for preparing lightweight photovoltaic module composite materials.

[0020] Preferably, the fiberglass resin composite layer is obtained by hot-pressing and curing two layers of the lightweight photovoltaic module composite material prepreg after lamination.

[0021] Fourthly, the present invention provides a method for preparing the above-mentioned integrated front panel for lightweight photovoltaic modules, comprising: pre-curing two layers of the aforementioned lightweight photovoltaic module composite material semi-cured sheet preferably according to 0... o 90 o The layers are stacked to obtain a glass fiber resin composite layer; then, the glass fiber resin composite layer is placed between two release films and pressed and cured. In a preferred embodiment of the present invention, the step of stacking according to 0... o 90 o Stacking refers to placing the first layer of prepreg at a 0° angle and the second layer of prepreg at a 90° angle to the first layer. Other stacking methods based on this invention are also within the scope of protection of this invention. This invention preferably uses two layers of lightweight photovoltaic module composite prepreg to prepare the fiberglass resin composite layer, which yields excellent results. Using one or more layers of fiberglass resin composite layer according to the scheme of this invention is also within the scope of protection of this invention.

[0022] Preferably, the lamination temperature for pressing and curing is 130~170℃, and the lamination time is 10~20min.

[0023] The beneficial effects of this invention are at least as follows: 1. The polyurethane resin in this invention has a refractive index closer to that of glass fiber. Combined with the excellent wettability of specific organosilicon, it reduces the interfacial scattering loss of light, enabling the light transmittance of the composite material to reach over 90%.

[0024] 2. The present invention uses low molecular weight hydroxyl-type organosilicon and high molecular weight isocyanate-type organosilicon for composite modification. The two work synergistically to achieve optimal comprehensive performance in terms of light transmittance, yellowing resistance, and wettability.

[0025] 3. This invention strengthens the interfacial bonding between polyurethane resin and glass fiber through the bridging effect of organosilicon. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the integrated front panel of a lightweight photovoltaic module provided in an embodiment of the present invention. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0029] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0030] Unless otherwise specified, the techniques or conditions described in the embodiments of this invention shall be performed in accordance with the techniques or conditions described in the literature in this field, or in accordance with the product instructions. Devices, instruments, reagents, etc., without specified manufacturers, are all conventional products that can be purchased through legitimate channels. All experimental reagents and raw materials involved are commercially available products, and all reagents are analytical grade products.

[0031] Example 1 This embodiment provides an integrated front panel for lightweight photovoltaic modules, the structure of which consists of a glass fiber reinforced skeleton and a polyurethane-silicone composite resin matrix. Its preparation method is as follows: 1. Preparation of resin solution: The resin adopts a self-synthesized polyurethane-organic silicone composite system. The resin synthesis scheme is as follows: S1. Polyether polyol (Mn=2000) and acetone were vacuum dehydrated at 110℃ and 0.1MPa for 2 hours and then cooled for later use. 70 parts of polyether polyol, 10 parts of toluene diisocyanate and 0.1 parts of dibutyltin dilaurate were mixed evenly and reacted at 85℃ for 2 hours under a nitrogen atmosphere to obtain isocyanate-terminated polyurethane prepolymer.

[0032] S2. Add 5 wt% hydroxyl-terminated polydimethylsiloxane to the isocyanate-terminated polyurethane prepolymer and react, wherein the number average molecular weight of the hydroxyl-terminated polydimethylsiloxane is 1000. S3. The reaction was terminated when the NCO content reached 10% (the NCO content was monitored using the di-n-butylamine method, referring to HG / T 2409-2023). Acetone was added for dilution to obtain the target resin with a solid content of 42%.

[0033] 2. Impregnation molding: Select a weight of 110g / m³ 2 The alkali-free fiberglass cloth is impregnated in an adhesive bath, and then subjected to pressure (squeezing and scraping adhesive) by a pair of rollers at 30 N / cm. It is then placed in an oven and baked at 80°C for 10 minutes to achieve semi-curing. Two semi-cured sheets are then laid out according to a 0... o 90 o Stacked placement ( Figure 1 During the stacking process, the upper and lower release films are placed in a laminator and pressed and cured. The lamination temperature is 150℃ and the lamination time is 15 minutes. After curing, the film is cooled and removed to form an integrated front panel.

[0034] Example 2-13 The same method as in Example 1 was used, with the main difference being the type, molecular weight, and amount of organosilicon added, as detailed in Table 1.

[0035] Comparative Example 1 The method is the same as in Example 1, except that no organosilicon is added.

[0036] Performance tests were conducted on Examples 1-13 and Comparative Example 1: Transmittance: Take a 5cm × 5cm sample and place it in the test window of the UV spectrophotometer, then close the test window cover. Select a test wavelength of 200-1100nm and an instrument resolution of 1nm. After the test, select the average transmittance in the 400-1100nm band as the transmittance value, and take the average of 3 samples as the test result.

[0037] Yellowing index: The test temperature is 60 (±5)℃, as specified in IEC 61215-2021. After the test, the sample is removed and the yellowing index b is tested according to GB / T 3979-2008 and GB / T 7921-2008. Δb is calculated and the average value is taken.

[0038] For the fiberglass contact angle: a contact angle meter was used for testing. The alkali-free fiberglass cloth was fixed on the sample stage, and resin was dropped onto the surface of the fiberglass cloth using a micro-syringe. After the droplet stabilized, an image was taken, and the static contact angle was calculated by fitting the data using the instrument software. Each sample was tested in parallel 5 times, and the average value was taken.

[0039] Interlaminar shear strength: Refer to ASTM D2344. Apply load through a three-point or four-point bending configuration, control the span-to-depth ratio (usually 5:1), and cause the specimen to fail under interlaminar shear stress. Calculate the interlaminar shear strength by measuring the failure load and the geometry of the beam.

[0040] Table 1

[0041] Compared with the unmodified control, the transmittance, UV resistance, and other indicators of Examples 1-6 were all improved after organosilicon modification. The effects of adding different types and proportions of organosilicon prepolymers were also different: In Examples 1-3, hydroxyl-type organosilicon, as a capping agent, was mainly located at the chain end, had good dispersibility in the matrix, small phase separation scale (<100nm), and weak light scattering, so the transmittance was significantly improved; its Si-O-Si segments effectively absorbed / shielded ultraviolet rays, improving yellowing resistance; it moderately reduced surface energy, improving wettability; the terminal hydroxyl groups formed chemical bonds with the glass fiber surface, and the long-chain polysiloxane was compatible with the polyurethane matrix, forming a flexible interface layer at the interface, which was beneficial to improving shear strength. In Examples 4-6, isocyanate-based silicones were used as chain extenders to incorporate into the main chain, forming PU-Si block copolymers. This process facilitates more pronounced microphase separation (~200 nm), slightly affecting light transmittance. However, the silicone segments on the main chain provide a more durable UV shielding effect, superior resistance to yellowing, and significantly reduced resin surface energy, resulting in good wettability. Furthermore, its strong hydrophobicity and chemical bonding form a robust "organic-inorganic" interface with the glass fiber surface, greatly enhancing interfacial adhesion after damp heat aging. When the silicone addition ratio is between 5% and 10%, a good balance of overall performance is achieved.

[0042] Examples 2, 7, and 8 use hydroxyl-containing organosilicones of different molecular weights to modify polyurethane: the lower the molecular weight, the shorter the chain segments, the more uniform the dispersion in the polyurethane matrix, the weaker the tendency for phase separation, the almost no light scattering, and the highest light transmittance. However, its ability to migrate to the surface is weak, resulting in limited improvement on surface hydrophobicity and yellowing resistance. Increasing the molecular weight enhances the mobility of organosilicon chain segments, resulting in stronger ability to migrate and accumulate to the surface, more effectively reducing surface energy, improving wettability, increasing yellowing resistance, and simultaneously thickening the interface layer for better anti-delamination effect. However, the phase region size increases, affecting light transmittance.

[0043] Examples 5, 9, and 10 use isocyanate silicones of different molecular weights to modify polyurethane: low molecular weight results in a small phase region size, weak light scattering, and high light transmittance; higher molecular weight leads to longer and higher content of silicone segments, which can absorb more ultraviolet light and have excellent resistance to yellowing. High molecular weight silicone segments have a stronger ability to migrate and accumulate on the resin surface, which can significantly reduce surface energy and improve the wetting effect on high surface energy glass fibers. However, excessively high molecular weight leads to excessively high system viscosity, which affects the actual processing.

[0044] Examples 11-13 employ a composite modification of hydroxyl-type and isocyanate-type organosilicon. The composite modification of 5% hydroxyl-type organosilicon (Mn=500) + 5% isocyanate-type organosilicon (Mn=5000) shows superior results, with performance results indicating a light transmittance of 92.5% and resistance to yellowing (UV 800kWh / m). 2 With a Δb=4.0 and a contact angle of 46°, the interlaminar shear strength retention rate reaches 90% after damp heat aging. Low molecular weight hydroxyl-type silicone acts as a highly efficient compatibilizer and end-capping agent, ensuring microscopic uniformity and high light transmittance; high molecular weight isocyanate-type silicone acts as a main chain reinforcing unit and surface modifier, providing durable yellowing resistance and optimal surface wettability, while forming strong chemical bonds with the glass fiber surface and polyurethane matrix, enhancing interfacial adhesion strength. The two work synergistically to achieve optimal overall performance in terms of light transmittance, yellowing resistance, wettability, and damp heat resistance.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A lightweight photovoltaic module composite material, characterized in that, include: A glass fiber reinforced skeleton and a composite resin matrix, wherein the composite resin matrix is ​​impregnated in the glass fiber reinforced skeleton; The raw materials of the composite resin matrix include organosilicon and polyurethane prepolymer, wherein the organosilicon is hydroxyl-type organosilicon with a number average molecular weight ≤2000 and / or isocyanate-type organosilicon with a number average molecular weight ≥2000.

2. The composite material according to claim 1, characterized in that, The hydroxyl-type organosilicon is hydroxyl-terminated polydimethylsiloxane; the isocyanate-type organosilicon isocyanate-terminated polydimethylsiloxane. Preferably, the number average molecular weight of the hydroxyl-terminated polydimethylsiloxane is 500-10000, more preferably 500-2000; and the number average molecular weight of the isocyanate-terminated polydimethylsiloxane is 2000-10000, more preferably 5000-8000.

3. The composite material according to claim 1, characterized in that, The organosilicon accounts for 5% to 20% of the total mass of the polyurethane prepolymer, preferably 9% to 11%; and / or, the mass ratio of the hydroxyl-type organosilicon to the isocyanate-type organosilicon is 0 to 10: 0 to 10, preferably 3 to 7: 3 to 7.

4. The composite material according to claim 1, characterized in that, The polyurethane prepolymer is an isocyanate-terminated polyurethane prepolymer.

5. The composite material according to claim 4, characterized in that, The preparation of the isocyanate-terminated polyurethane prepolymer includes: mixing a polyol, an isocyanate, and a catalyst, and heating the mixture under an inert atmosphere; the polyol is selected from one or more of polyester polyols, polycaprolactone polyols, polycarbonate polyols, dimer acid-modified polyester polyols, and polyether polyols; the molecular weight of the polyol is 500-5000; the isocyanate is preferably selected from one or more of trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, octamethylene diisocyanate, trimethylhexane diisocyanate, tetramethylhexane diisocyanate, decamethylene diisocyanate, dodecamethylene diisocyanate, isophorone diisocyanate, toluene diisocyanate, diphenylmethane-2,4'-diisocyanate, and diphenylmethane-4,4'-diisocyanate; the catalyst is preferably dibutyltin dilaurate.

6. The composite material according to claim 5, characterized in that, The heating reaction is carried out at a temperature of 75-85°C for 2-4 hours, and the inert atmosphere includes nitrogen or argon. And / or, the mass ratio of the polyol, isocyanate and catalyst is 70~90:10~30:0.1~0.5; And / or, it also includes vacuum dehydrating the polyol and organic solvent separately before mixing, wherein the vacuum dehydration temperature is 110~120℃ and the time is 1.5~2h.

7. The method for preparing the lightweight photovoltaic module composite material according to any one of claims 1-6, characterized in that, include: 1) The polyurethane prepolymer is mixed with the organosilicon and reacted. The reaction is terminated when the NCO% content reaches 9%~11%. An organic solvent is added to dilute the mixture to obtain a resin solution. 2) The glass fiber reinforced skeleton is impregnated into the resin solution, and then squeezed and semi-cured.

8. The preparation method according to claim 7, characterized in that, In step 1), the viscosity of the resin solution is 200~500 mPa·s, the solid content is 40%~50%, and the organic solvent used for dilution is selected from one or more of acetone, butanone, ethyl acetate, butyl acetate, N,N-dimethylformamide, and tetrahydrofuran. And / or, in step 2), the glass fiber reinforced skeleton is alkali-free glass fiber with a surface treated with a silane coupling agent, and the basis weight of the glass fiber reinforced skeleton is 100~200 g / m². 2 ; The extrusion coating is performed by roller extrusion coating with a pressure of 10~50 N / cm. The semi-curing treatment is performed by baking at 70~90℃ for 5~15 min to obtain a semi-cured sheet.

9. An integrated front panel for lightweight photovoltaic modules, characterized in that, It includes a glass fiber resin composite layer, wherein the lightweight photovoltaic module composite material prepreg used in the glass fiber resin composite layer is prepared by the method for preparing the lightweight photovoltaic module composite material as described in claim 7; Preferably, the fiberglass resin composite layer is obtained by hot-pressing and curing two layers of the lightweight photovoltaic module composite material prepreg after lamination.

10. The method for preparing the integrated front panel for lightweight photovoltaic modules according to claim 9, characterized in that, include: Two layers of the lightweight photovoltaic module composite material semi-cured sheet are stacked to obtain a glass fiber resin composite layer; then the glass fiber resin composite layer is placed between two release films and pressed and cured; preferably, the lamination temperature of the pressing and curing is 130~170℃ and the lamination time is 10~20min.

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