POE photovoltaic adhesive film and preparation method thereof

Abstract

The invention relates to the technical field of photovoltaic adhesive films, and discloses a POE photovoltaic adhesive film and a preparation method thereof.The method comprises the steps that 1, POE and a silane coupling agent are premixed and then introduced into an ultrasonic melt extrusion system, the mixture is melted and then extruded in an ultrasonic environment, and modified POE is obtained; (2) mixing the modified POE, a cross-linking agent, an assistant cross-linking agent, an antioxidant and a light stabilizer, and then extruding, calendering and cooling; the ultrasonic melt extrusion system comprises a screw extrusion device and an ultrasonic generation device, the discharge end of the screw extrusion device is connected with the mouth mold, the ultrasonic generation device is connected with the mouth mold, so that the extrusion process in the mouth mold is carried out in an ultrasonic environment, and the ultrasonic generation device is provided with more than three ultrasonic probes. Through an ultrasonic environment provided by a plurality of ultrasonic probes, the grafting efficiency and uniformity of the modified POE are remarkably improved, the problem of migration of a silane additive is solved, and a photovoltaic adhesive film prepared from the modified POE has strong adhesive force and high light transmittance.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic films, and in particular to a POE photovoltaic film and a preparation method thereof. Background Art

[0002] Photovoltaic film is a critical component of photovoltaic modules, primarily used to bond photovoltaic cell modules to other materials such as backsheets and glass, protecting the cells and enhancing the mechanical performance of the modules. Existing photovoltaic film materials primarily utilize two polymers: EVA (ethylene-vinyl acetate copolymer) and POE (polyolefin elastomer). POE offers significantly superior weather resistance compared to EVA, particularly under environmental influences such as UV rays, high temperatures, and humidity. POE film exhibits superior aging resistance, effectively extending the lifespan of photovoltaic modules. While EVA film can experience yellowing and embrittlement over time, POE film maintains its physical and chemical properties in harsher environments. POE offers superior thermal stability, allowing it to withstand higher operating temperatures and avoid thermal degradation. EVA film is susceptible to thermal oxidation and aging under prolonged high temperatures, impacting the performance and lifespan of photovoltaic modules. POE film, however, has significantly lower hygroscopicity than EVA, effectively protecting photovoltaic modules from moisture, reducing hydrolysis, and enhancing long-term reliability. Moisture is one of the main reasons for the performance degradation of EVA film, especially in humid environments. Furthermore, POE film has a higher light transmittance than EVA, providing better light transmittance, which helps improve the power generation efficiency of photovoltaic modules. In particular, its light transmittance decreases less after long-term use.

[0003] However, POE's inherent adhesive properties are weaker than those of EVA, resulting in poor adhesion to various materials within the PV module (such as glass, solar cells, and backsheets) during the encapsulation process. Furthermore, additives in the film (such as silane coupling agents) are prone to migration and precipitation, leading to issues such as insufficient crosslinking, insufficient peel strength, and uneven peel strength. These weak adhesive properties are extremely detrimental to improving the mechanical strength and long-term stability of PV modules, particularly in terms of vibration and impact resistance, significantly limiting their application in high-efficiency PV modules. Summary of the Invention

[0004] The purpose of the present invention is to overcome the problems of poor bonding performance and uneven bonding of POE itself in the prior art, which limit its application in high-efficiency photovoltaic modules, and to provide a POE photovoltaic film and a preparation method thereof.

[0005] In order to achieve the above object, the present invention provides a method for preparing a POE photovoltaic film, which comprises the following steps: (1) POE and a silane coupling agent are premixed, and the resulting mixture is passed into an ultrasonic melt extrusion system, where the mixture is melted and mixed, and then extruded under an ultrasonic environment to obtain modified POE; (2) mixing the modified POE, a cross-linking agent, a co-cross-linking agent, an antioxidant and a light stabilizer, and then extruding, calendering, cooling, cutting and winding; Among them, the ultrasonic melt extrusion system includes a screw extruder and an ultrasonic generator. The discharge end of the screw extruder is connected to the die. The ultrasonic generator is connected to the die and is used to provide ultrasonic waves into the die so that the extrusion process in the die is carried out under an ultrasonic environment. The ultrasonic generator is equipped with more than three ultrasonic probes.

[0006] Preferably, in the screw extruder, the diameter of the screw is 20-50 mm, and the aspect ratio is 45-55.

[0007] Preferably, in step (1), the conditions of the ultrasonic environment include: a frequency of 10-50 kHz and a power of 100-1000 W.

[0008] Preferably, in step (1), the silane coupling agent is selected from one or more of vinyl triethoxysilane, γ-glycidyloxypropyl trimethoxysilane, γ-aminopropyl triethoxysilane, γ-epoxypropyl triethoxysilane and vinyl tris (2-methoxyethoxy) silane.

[0009] Preferably, in step (1), the weight ratio of the POE to the silane coupling agent is 100:0.1-5.

[0010] Preferably, in step (1), the melt index of the POE is not higher than 30 g / 10 min, preferably 10-20 g / 10 min.

[0011] Preferably, in step (1), the screw extruder comprises four temperature zones sequentially arranged along the material flow direction, and the temperatures thereof are 75-85°C, 115-125°C, 145-155°C and 145-155°C, respectively.

[0012] Preferably, in step (2), the cross-linking agent is selected from one or more of dicumyl peroxide, benzoyl peroxide, and dibenzoyl peroxide.

[0013] Preferably, in step (2), the auxiliary cross-linking agent is selected from one or more of triallyl isocyanurate, triallyl isocyanurate, isophorone diisocyanate, triallyl isocyanate, hexamethylene diisocyanate, tetramethyl diisocyanate and triallyl isocyanurate.

[0014] Preferably, in step (2), the antioxidant is selected from one or more of antioxidant 1010, antioxidant 912, antioxidant 168 and antioxidant 211.

[0015] Preferably, in step (2), the light stabilizer is selected from one or more of light stabilizer UV-531, light stabilizer UV-P, light stabilizer UV-234, light stabilizer UV-770 and light stabilizer UV-320.

[0016] Preferably, in step (2), the weight ratio of the modified POE, crosslinking agent, auxiliary crosslinking agent, antioxidant and light stabilizer is 100:0.1-5:0.1-3:0.05-2:0.05-2.

[0017] The second aspect of the present invention provides a POE photovoltaic film prepared by the method described above.

[0018] In the present invention, when preparing the modified POE, the silane coupling agent and POE are extruded under an ultrasonic environment. At the same time, the ultrasonic environment provided by multiple ultrasonic probes significantly improves the grafting efficiency and uniformity of the modified POE obtained, shortens the reaction time, and improves the migration problem of the silane additive. The modified POE is used to prepare the POE photovoltaic film, so that the POE photovoltaic film exhibits stronger adhesion to photovoltaic cells, glass, etc., improves the mechanical strength, heat resistance and weather resistance of the photovoltaic film, and the POE photovoltaic film has high light transmittance, which meets market usage needs. For example, the initial bonding strength of the POE photovoltaic film to the glass is above 150 N / cm, especially the bonding strength after high temperature and high humidity aging is still greater than 80 N / cm, thereby effectively ensuring the service life of the photovoltaic module. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of the ultrasonic melt extrusion system used in the preparation method provided by the present invention.

[0020] Description of Reference Numerals 1. Ultrasonic generator; 2. Piezoelectric transducer; 3. Thermocouple; 4. Die; 5. Screw extruder; 51. Housing; 6. Capillary rheometer; 7. Melt; 8. Ultrasonic probe. DETAILED DESCRIPTION

[0021] The following is a detailed description of the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0022] The endpoints of the ranges and any values ​​disclosed herein 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 endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0023] The present invention provides a method for preparing a POE photovoltaic film, the method comprising the following steps: (1) POE and a silane coupling agent are premixed, and the resulting mixture is passed into an ultrasonic melt extrusion system, where the mixture is melted and mixed, and then extruded under an ultrasonic environment to obtain modified POE; (2) mixing the modified POE, a cross-linking agent, a co-cross-linking agent, an antioxidant and a light stabilizer, and then extruding, calendering, cooling, cutting and winding; Among them, the ultrasonic melt extrusion system includes a screw extruder 5 and an ultrasonic generator. The discharge end of the screw extruder 5 is connected to the die 4. The ultrasonic generator is connected to the die 4 and is used to provide ultrasonic waves into the die 4 so that the extrusion process in the die 4 is carried out under an ultrasonic environment. The ultrasonic generator is equipped with more than three ultrasonic probes 8.

[0024] Please refer to Figure 1 In a specific embodiment, the ultrasonic melt extrusion system includes a screw extruder 5 and an ultrasonic generator, wherein the screw extruder 5 includes a shell 51 and a screw (not shown in the figure) installed in the shell 51, and the discharge end of the shell 51 is connected to the die 4; the ultrasonic generator includes an ultrasonic generator 1, a piezoelectric transducer 2 and an ultrasonic probe 8 connected in sequence, and the ultrasonic probe 8 is installed in the cavity of the die 4, and the ultrasonic probe 8 is configured with more than three.

[0025] During specific implementation, POE is melted in the screw extruder 5 and mixed with the silane coupling agent, and the obtained mixed melt 7 enters the cavity of the die 4; the ultrasonic wave provided by the ultrasonic generator 1 is converted by the piezoelectric transducer 2 and then transmitted to the cavity of the die 4 by multiple ultrasonic probes 8, so that the melt 7 in the cavity of the die 4 is extruded in an ultrasonic environment.

[0026] In a specific embodiment, the screw extruder 5 is a single screw extruder.

[0027] In some embodiments, a thermocouple 3 is further installed in the cavity of the die 4 for controlling and recording temperature changes during the extrusion process.

[0028] In some embodiments, a capillary rheometer 6 is further installed in the cavity of the die 4 for recording the rheological properties of the melt 7 .

[0029] In the present invention, in step (1), when preparing the modified POE, by extruding the silane coupling agent and POE under the assistance of ultrasound, the grafting reaction between the silane coupling agent and POE can be effectively promoted, significantly improving the grafting efficiency, shortening the reaction time, avoiding the material decomposition caused by high-temperature melt grafting, and also improving the migration problem of the silane auxiliary agent; at the same time, through the design of multiple ultrasonic probes 8, the grafting efficiency can be accelerated, and the uniformity of the modified POE obtained can be improved, so as to enhance the peel strength and bonding uniformity of the photovoltaic film, thereby improving the reliability and service life of the photovoltaic module. The grafting reaction of the POE is completed at a lower temperature, saving energy consumption and reducing the use of organic solvents, which meets the requirements of green environmental protection.

[0030] By using the above-mentioned modified POE as a raw material to prepare a POE photovoltaic film, the POE photovoltaic film exhibits stronger adhesion to photovoltaic cells, glass, etc., thereby improving the mechanical strength, heat resistance and weather resistance of the photovoltaic film, and the light transmittance of the photovoltaic film is high; for example: the initial bonding strength of the POE photovoltaic film to the glass is above 150 N / cm, especially the bonding strength after aging under high temperature and high humidity is still greater than 80 N / cm, and the high bonding strength effectively ensures the service life of the photovoltaic module.

[0031] In a preferred embodiment, in step (1), in the screw extruder 5, the diameter of the screw is 20-50 mm, and the aspect ratio is 45-55.

[0032] In a preferred embodiment, in step (1), the rotation speed of the screw is set to 10-100 rpm to adjust the extrusion rate.

[0033] In a preferred embodiment, in step (1), the ultrasonic environment conditions include: a frequency of 10-50 kHz and a power of 100-1000 W. By performing the grafting reaction in an ultrasonic environment with the above frequency and power, the grafting degree and cross-linking degree of the modified POE obtained are improved, thereby improving the adhesive properties of the final POE photovoltaic adhesive film. In specific implementation, the frequency of the ultrasonic generator 1 is set to 10-50 kHz and the power is set to 100-1000 W.

[0034] In the present invention, the silane coupling agent is an organosilicon compound containing functional groups such as amino, epoxy, and methyl groups. Examples include aminosilanes (such as γ-aminopropyltriethoxysilane), epoxysilanes (such as γ-epoxypropyltriethoxysilane), vinyltris(2-methoxyethoxy)silane, γ-glycidoxypropyltrimethoxysilane, and vinyltriethoxysilane.

[0035] In a preferred embodiment, the silane coupling agent is selected from one or more of vinyl triethoxysilane, γ-glycidyloxypropyl trimethoxysilane, γ-aminopropyl triethoxysilane, γ-epoxypropyl triethoxysilane and vinyl tris (2-methoxyethoxy) silane. By selecting the above-mentioned types of silane coupling agents, the source is easily available, the cost is low, and the performance of the modified POE obtained is better.

[0036] In a preferred embodiment, in step (1), the weight ratio of the POE to the silane coupling agent is 100:0.1-5, specifically, for example, 100:0.1, 100:1, 100:1.5, 100:2, 100:3, 100:4 or 100:5.

[0037] In some embodiments, in step (1), the melt index of the POE is not higher than 30 g / 10 min.

[0038] In a preferred embodiment, in step (1), the melt index of the POE is 10-20 g / 10 min.

[0039] In a preferred embodiment, in step (1), the screw extruder 5 includes four temperature zones arranged in sequence along the material flow direction, and the temperatures thereof are 75-85°C, 115-125°C, 145-155°C and 145-155°C, respectively. In a specific implementation, the area from the feed zone to the die head 4 includes four temperature zones arranged in sequence, with the temperature of zone 1 being 75-85°C, the temperature of zone 2 being 115-125°C, the temperature of zone 3 being 145-155°C, and the temperature of zone 4 being 145-155°C.

[0040] In some embodiments, in step (2), the cross-linking agent is selected from one or more of dicumyl peroxide, benzoyl peroxide, and dibenzoyl peroxide, preferably dicumyl peroxide.

[0041] In some embodiments, in step (2), the auxiliary cross-linking agent is selected from one or more of triallyl isocyanurate, triallyl isocyanurate, isophorone diisocyanate, triallyl isocyanate, hexamethylene diisocyanate, tetramethyl diisocyanate and triallyl isocyanurate, preferably triallyl isocyanurate.

[0042] In some embodiments, in step (2), the antioxidant is selected from one or more of antioxidant 1010, antioxidant 912, antioxidant 168, and antioxidant 211, preferably antioxidant 1010.

[0043] In some embodiments, in step (2), the light stabilizer is selected from one or more of the group consisting of light stabilizer UV-531, light stabilizer UV-P, light stabilizer UV-234, light stabilizer UV-770, and light stabilizer UV-320. Preferably, the light stabilizer is a mixture of light stabilizer UV-531 and light stabilizer UV-770. More preferably, the weight ratio of light stabilizer UV-531 to light stabilizer UV-770 is 1:0.5-2.

[0044] In a preferred embodiment, in step (2), the weight ratio of the modified POE, cross-linking agent, auxiliary cross-linking agent, antioxidant and light stabilizer is 100:0.1-5:0.1-3:0.05-2:0.05-2. By controlling the amount of each raw material component within the above range, the prepared POE photovoltaic adhesive film has better bonding performance, high mechanical strength and high light transmittance.

[0045] In a more preferred embodiment, in step (2), the weight ratio of the modified POE, crosslinking agent, auxiliary crosslinking agent, antioxidant and light stabilizer is 100:0.1-3:0.1-1:0.1-0.5:0.1-0.5.

[0046] In some embodiments, in step (2), the extrusion is performed in a twin-screw extruder.

[0047] In some embodiments, in step (2), the extrusion conditions include: a temperature of 80-150° C. and a screw speed of 100-200 rpm.

[0048] The present invention also provides a POE photovoltaic adhesive film prepared by the above-described method. The specific operation of the method is similar to the above-described embodiments. Since the POE photovoltaic adhesive film of the present invention adopts all the technical solutions of all the above-described embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above-described embodiments, and will not be described in detail here.

[0049] The present invention will be described in detail below by way of examples, but the scope of the present invention is not limited thereto. The experimental methods in the following examples, unless otherwise specified, are conventional methods in the art. The experimental materials used in the following examples, unless otherwise specified, are commercially available products.

[0050] In the following examples and comparative examples, the raw materials involved are: POE: melt index is 14 g / 10 min, brand is Engage 8669, purchased from Dow Chemical Company; Silane coupling agent 1: vinyl triethoxysilane, industrial grade, purchased from Dow Corning; Silane coupling agent 2: γ-glycidyloxypropyltrimethoxysilane, industrial grade, purchased from Anhui Guibao Organic Silicon New Materials Co., Ltd. The cross-linking agent was dicumyl peroxide, technical grade, purchased from Akzo Nobel; The co-crosslinking agent was triallyl isocyanurate, industrial grade, purchased from Hunan Yixiang Technology Co., Ltd. The antioxidant was antioxidant 1010, industrial grade, purchased from BASF; The light stabilizer is a mixture of light stabilizer UV-531 and light stabilizer UV-770 in a weight ratio of 1:1, purchased from Tianjin Li'anlong New Materials Co., Ltd.

[0051] The following examples are in reference Figure 1 The ultrasonic melt extrusion system shown is implemented, and the ultrasonic melt extrusion system includes a screw extrusion device 5 and an ultrasonic generating device, wherein the screw extrusion device 5 is a single-screw extruder, which includes a shell 51 and a screw installed in the shell 51, and the screw has a diameter of 35 mm and an aspect ratio L / D = 48; the discharge end of the shell 51 is connected to the die 4; the ultrasonic generating device includes an ultrasonic generator 1, a piezoelectric transducer 2 and an ultrasonic probe 8 connected in sequence, and the ultrasonic probe 8 is installed in the cavity of the die 4.

[0052] Example 1 This embodiment is used to illustrate the POE photovoltaic film and its preparation method.

[0053] (1) POE and silane coupling agent 1 (vinyl triethoxysilane) are mixed in a mass ratio of 100:2, and then the obtained mixture is passed into an ultrasonic melt extrusion system, melted and mixed in a single-screw extruder, and the obtained melt 7 enters the cavity of the die 4 from the discharge end. The ultrasonic wave provided by the ultrasonic generator 1 is converted by the piezoelectric transducer 2 and then transmitted to the cavity of the die 4 by the ultrasonic probe 8, so that the melt 7 in the cavity of the die 4 is extruded in an ultrasonic environment to obtain modified POE; The single-screw extruder has four temperature zones from the feed zone to the die (i.e., the material flow direction), with temperatures of 80°C, 120°C, 150°C, and 150°C, respectively. The screw speed is set at 30 rpm. The number of ultrasonic probes 8 is 3, and the conditions of the ultrasonic generator 1 are: frequency 30 kHz, power 300 W.

[0054] (2) The modified POE obtained in step (1) is mixed with a cross-linking agent, a co-cross-linking agent, an antioxidant and a light stabilizer (the weight parts of each raw material are: 100 parts of modified POE, 1 part of cross-linking agent, 0.5 parts of co-cross-linking agent, 0.3 parts of antioxidant, and 0.3 parts of light stabilizer), and extruded through a twin-screw extruder, wherein the conditions of the twin-screw extruder include: an extrusion temperature of 100°C and a screw speed of 150 rpm, and then calendering, cooling, cutting, and winding processes are carried out to obtain a POE encapsulation film.

[0055] Example 2 The method described in Example 1 was followed, except that the power of the ultrasonic generator 1 was 200W.

[0056] Example 3 The method described in Example 1 was followed, except that the power of the ultrasonic generator 1 was 400W.

[0057] Example 4 The method described in Example 1 was followed, except that the power of the ultrasonic generator 1 was 600W.

[0058] Example 5 The method described in Example 1 was followed, except that the power of the ultrasonic generator 1 was 800W.

[0059] Example 6 The method described in Example 1 was used, except that the frequency of the ultrasonic generator 1 was 40 kHz.

[0060] Example 7 The method described in Example 1 was followed, except that the silane coupling agent used was Silane Coupling Agent 2 (γ-glycidyloxypropyltrimethoxysilane).

[0061] Comparative Example 1 The method described in Example 1 was followed, except that the extrusion process in step (1) did not involve ultrasonic treatment; Specifically, step (1): POE and silane coupling agent are mixed in a mass ratio of 100:2, and the obtained mixture is then passed into a single-screw extruder (without ultrasound) for melt extrusion to obtain modified POE, wherein the feed zone of the single-screw extruder to the die 4 zone (i.e., the material flow direction) includes four temperature zones set in sequence, and the temperatures are 80°C, 120°C, 150°C and 150°C respectively, the screw speed is set to 30 rpm, and the diameter of the screw in the single-screw extruder is 35 mm, and the aspect ratio L / D=48.

[0062] Comparative Example 2 The method described in Example 1 is used for implementation, except that the number of ultrasonic probes 8 is one.

[0063] The conditions in the above examples and comparative examples are shown in Table 1 below.

[0064] Table 1

[0065] Test Case The modified POE prepared in the examples and comparative examples were tested for silane grafting rate and adjuvant migration, and the POE photovoltaic adhesive films prepared in the examples and comparative examples were tested for crosslinking degree and peel strength performance.

[0066] (1) Test of grafting rate and additive migration of modified POE: The grafting rate of silane coupling agent on modified POE: determined by acid-base titration; this method indirectly calculates the silane grafting rate by measuring the content of the hydrolysis product (silanol) of the silane group in the modified POE after silane grafting. The specific experimental method is: take a certain amount (about 0.5-1.0 g) of silane-grafted modified POE sample and weigh it accurately (recorded as W0); cut the sample into fine particles to increase the reaction surface area. Place the sample in a conical flask and add 50 mL of deionized water; add a few drops of acidic catalyst (such as 0.1 M hydrochloric acid or sulfuric acid) and adjust the pH to 3-4; heat and stir in a water bath at 80-90 °C for 2-4 hours to fully hydrolyze the silane group to silanol (Si-OH); after the hydrolysis is completed, cool to room temperature and titrate with 0.1 M sodium hydroxide (NaOH) standard solution to pH=7, and record the volume of NaOH consumed (recorded as V 1). Take the same amount of ungrafted POE sample, repeat the above hydrolysis and titration steps, and record the volume of NaOH consumed (recorded as V 0).

[0067] The silane grafting efficiency (GE) can be calculated using the following formula: (1) in, V 1: Volume of NaOH consumed by the sample (mL); V 0: blank NaOH volume consumed (mL); C NaOH : concentration of NaOH standard solution (mol / L); M 硅烷 : molar mass of silane (g / mol); W0: sample mass (g).

[0068] Silane additive migration and precipitation test method (qualitative): Place 5 grams of POE sample after silane grafting modification into a separate unused polyethylene plastic ziplock bag, seal it and store it at room temperature for 7 days. After 7 days, press the test sample and the polyethylene plastic ziplock bag together and observe the oil marks left on the inner surface of the bag under light. The oil marks indicate the degree of additive migration and precipitation in the test sample. The more oil marks on the inner surface of the bag, the more serious the additive precipitation of the test sample. According to the area of ​​the oil marks, the degree of additive precipitation can be recorded as none, very little (oil area <2 cm 2 ), obvious (oil area 2 cm 2 -4 cm 2 ), very much (oil area > 4 cm 2 ) to sort the precipitation amounts.

[0069] (2) Performance test of POE photovoltaic film: Cross-linking degree test: GB / T 29848-2018 xylene extraction method.

[0070] Peel Strength and Peel Strength Uniformity Tests: According to GB / T2790-1995, the peel strength between the POE film and glass is evaluated to ensure that the modified film will not peel during long-term use. In the peel strength test, samples are randomly selected at five locations on the sample, and the average and variance of the five peel strength test values ​​are calculated. The average value represents the sample's peel strength, while the variance reflects the uniformity of the peel strength, and thus the film's bonding uniformity.

[0071] Stability test: Through a 1000-h damp heat aging test under the test conditions of (85±2)°C and (85±5)%, the peel strength between the film and the glass after aging is measured to evaluate the stability and durability of the film in high temperature and high humidity environments.

[0072] The test results are shown in Table 2 below.

[0073] Table 2

[0074] As can be seen from Table 2, the present invention utilizes an ultrasonic energy field to perform silane grafting modification on POE, while simultaneously using multiple ultrasonic probes 8, resulting in a high silane grafting rate on POE and no migration of the silane additive. This results in a high degree of crosslinking and high transmittance in the resulting POE photovoltaic film, while maintaining high initial peel strength and peel strength after wet-heat aging. Furthermore, the variance of the peel strength represents the uniformity of adhesion at different locations on the sample. A larger variance indicates more uneven adhesion, while a smaller variance indicates more uniform adhesion. Under the same extrusion conditions, adhesion uniformity reflects the uniformity of the POE grafted silane. Test results show that the use of multiple ultrasonic probes 8 improves the uniformity of film adhesion, thereby reflecting the uniformity of the POE grafted silane.

[0075] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A method for preparing a POE photovoltaic film, characterized in that: The method comprises the following steps: (1) POE and a silane coupling agent are premixed, and the resulting mixture is passed into an ultrasonic melt extrusion system, where the mixture is melted and mixed, and then extruded under an ultrasonic environment to obtain modified POE; (2) mixing the modified POE, a cross-linking agent, a co-cross-linking agent, an antioxidant and a light stabilizer, and then extruding, calendering, cooling, cutting and winding; Among them, the ultrasonic melt extrusion system includes a screw extruder and an ultrasonic generator. The discharge end of the screw extruder is connected to the die. The ultrasonic generator is connected to the die and is used to provide ultrasonic waves into the die so that the extrusion process in the die is carried out under an ultrasonic environment. The ultrasonic generator is equipped with more than three ultrasonic probes.

2. The method according to claim 1, characterized in that In the screw extruder, the diameter of the screw is 20-50 mm, and the aspect ratio is 45-55.

3. The method according to claim 1 or 2, characterized in that In step (1), the conditions of the ultrasonic environment include: a frequency of 10-50 kHz and a power of 100-1000 W.

4. The method according to any one of claims 1 to 3, characterized in that In step (1), the silane coupling agent is selected from one or more of vinyl triethoxysilane, γ-glycidyloxypropyl trimethoxysilane, γ-aminopropyl triethoxysilane, γ-epoxypropyl triethoxysilane and vinyl tris (2-methoxyethoxy) silane; and / or In step (1), the weight ratio of the POE to the silane coupling agent is 100:0.1-5.

5. The method according to any one of claims 1 to 4, characterized in that In step (1), the melt index of the POE is not higher than 30 g / 10 min, preferably 10-20 g / 10 min.

6. The method according to any one of claims 1 to 5, characterized in that In step (1), the screw extruder includes four temperature zones arranged in sequence along the material flow direction, and the temperatures thereof are 75-85°C, 115-125°C, 145-155°C and 145-155°C, respectively.

7. The method according to any one of claims 1 to 6, characterized in that In step (2), the cross-linking agent is selected from one or more of dicumyl peroxide, benzoyl peroxide, and dibenzoyl peroxide; and / or In step (2), the auxiliary cross-linking agent is selected from one or more of triallyl isocyanurate, triallyl isocyanurate, isophorone diisocyanate, triallyl isocyanate, hexamethylene diisocyanate, tetramethyl diisocyanate and triallyl isocyanurate.

8. The method according to any one of claims 1 to 7, characterized in that In step (2), the antioxidant is selected from one or more of antioxidant 1010, antioxidant 912, antioxidant 168 and antioxidant 211; and / or In step (2), the light stabilizer is selected from one or more of light stabilizer UV-531, light stabilizer UV-P, light stabilizer UV-234, light stabilizer UV-770 and light stabilizer UV-320.

9. The method according to any one of claims 1 to 8, characterized in that In step (2), the weight ratio of the modified POE, crosslinking agent, auxiliary crosslinking agent, antioxidant and light stabilizer is 100:0.1-5:0.1-3:0.05-2:0.05-2.

10. POE photovoltaic film prepared by the method according to any one of claims 1 to 9.

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