A material usable for photovoltaic devices and a process for processing the same

Abstract

The present application belongs to the field of material processing, especially relates to the field of B29D7 / 01, and more particularly relates to a material for photovoltaic equipment and a processing technology thereof. The processing technology steps comprise the following steps: (1) mixing and hot baking; (2) screw extrusion; (3) traction calendering; (4) electromagnetic wave heating; (5) cooling roll cooling; (6) secondary hot baking; wherein the raw materials of the material are high-melt-index fluorine-containing resin and low-melt-index fluorine-containing resin compounding, and the finished product obtained through the final processing has excellent mechanical properties, and the surface flatness is higher and there is no yellowing phenomenon.

Description

Technical Field

[0001] This invention belongs to the field of materials processing, particularly to the field of B29D7 / 01, and more specifically to a material that can be used in photovoltaic equipment and its processing technology. Background Technology

[0002] Against the backdrop of a severe shortage of non-renewable energy sources such as oil, natural gas, and coal, and the escalating environmental pollution problem, the efficient utilization of renewable energy has attracted widespread attention from governments and the energy industry worldwide. However, compared to traditional non-renewable resources, the use of renewable alternative energy often incurs higher costs. Therefore, solar energy, with its wide availability, high energy content, and relatively high expected returns, is playing an increasingly important role in the use of renewable resources. Photovoltaic materials, which can directly convert solar energy into electricity, are applied in the field of photovoltaic power generation. As an important form of renewable energy, it is one of the most technologically advanced and commercially viable power generation methods currently available, and is receiving increasing attention.

[0003] Existing technology, patent CN106935666B, discloses a photovoltaic material, its preparation method, and its applications. The preparation method involves mixing relevant raw materials, transferring the mixture to a tube furnace, reacting it under inert conditions, cooling and drying it, and then microwave-treating it. This photovoltaic material can be applied to solar cell thin films; however, it requires further processing to better suit its photovoltaic applications, as issues such as surface smoothness and yellowing remain unresolved. Existing technology, patent CN110511627B, discloses a self-cleaning FEVE fluorocarbon coating and its preparation method. FEVE is also a photovoltaic material. The preparation method involves stirring relevant raw materials in a specific order. However, the resulting FEVE fluorocarbon coating may have low toughness without further processing, making it unsuitable for long-term use. Therefore, how to efficiently process materials to obtain a smooth surface with sufficient toughness and hardness has become a hot research topic. Summary of the Invention

[0004] To address the aforementioned problems, this invention proposes a material that can be used in photovoltaic equipment. The raw materials for preparing the material include a high melt index fluorinated resin and a low melt index fluorinated resin. The high melt index fluorinated resin has a melt index of 5-7 g / 10 min, and the low melt index fluorinated resin has a melt index of 3-5 g / 10 min. The mass ratio of the high melt index fluorinated resin to the low melt index fluorinated resin is (1-2.5):(1-2).

[0005] As an implementable example, the mass ratio of the high melt index fluorinated resin to the low melt index fluorinated resin may include 1:1, 1:2, 5:4, 2:1, 2:3 or 3:2.

[0006] Preferably, the high melt flow index fluorinated resin includes at least one of polyvinylidene fluoride, polyvinylidene fluoride, trifluorochloroethylene resin, and tetrafluoroethylene resin.

[0007] More preferably, the high melt flow index fluorinated resin includes at least polyvinylidene fluoride.

[0008] Preferably, the low melt index fluorinated resin includes at least one of polyvinylidene fluoride, polyvinylidene fluoride, trifluorochloroethylene resin, and tetrafluoroethylene resin.

[0009] More preferably, the low melt index fluorinated resin includes at least polyvinylidene fluoride.

[0010] The second aspect of the present invention provides a processing technology for materials that can be used in photovoltaic equipment, comprising at least the following steps: (1) mixing and drying; (2) screw extrusion; (3) traction calendering; (4) electromagnetic wave heating; (5) cooling roller cooling; and (6) secondary drying.

[0011] Preferably, the mixing and drying process involves uniformly mixing high melt index fluorinated resin and low melt index fluorinated resin according to a mass ratio, and then drying at a certain temperature. The mixing and drying temperature is 80-100℃, and the mixing and drying time is 3-5 hours. Examples of mixing and drying temperatures include 80℃, 85℃, 90℃, 95℃, or 100℃; examples of mixing and drying times include 3 hours, 3.6 hours, 4 hours, 4.8 hours, 5 hours, or 6 hours.

[0012] Preferably, the screw extrusion involves feeding the material obtained after mixing and heating into a single-screw extruder for extrusion. The extrusion temperature of the single-screw extruder is 190-200℃ in zone 1, 190-200℃ in zone 2, 190-200℃ in zone 3, and 190-200℃ in zone 4; the die temperature of the single-screw extruder is 220-240℃, and the screw speed is 50-80 rpm. Examples of possible extrusion temperatures for the single-screw extruder include: 190℃ in zone 1, 190℃ in zone 2, and 190-200℃ in zone 4. 190℃, Zone 3 190℃, Zone 4 190℃ or Zone 1 195℃, Zone 2 195℃, Zone 3 195℃, Zone 4 195℃ or Zone 1 200℃, Zone 2 200℃, Zone 3 200℃, Zone 4 200℃; the die head temperature can be listed as: 220℃, 225℃, 228℃, 230℃, 234℃, 238℃ or 240℃; the screw speed can be listed as 50rpm, 60rpm, 70rpm or 80rpm.

[0013] Polyvinylidene fluoride (PVDF) possesses excellent chemical stability and electrical insulation properties, making it widely applicable in the manufacture of photovoltaic equipment. However, its wear resistance and toughness are relatively poor. Furthermore, high melt index PVDF alone is quite expensive. To address these shortcomings, the inventors discovered that using PVDF with a melt index of 5-7 g / 10 min and PVDF with a melt index of 3-5 g / 10 min together in a melt compound significantly improves the material's hardness. Using a single PVDF with a melt index of 5-7 g / 10 min, due to its high melt index... The high melt index (MIF) of PVDF results in poor physical toughness. However, when combined with PVDF of 3-5 g / 10 min, it significantly reduces the MIF of the polymerization system and combines the excellent properties of both high and low MIF PVDF, resulting in a significant improvement in the material's physical properties and reduced production costs. This invention specifies MIF values ​​of 3-5 g / 10 min and 5-7 g / 10 min for PVDF. Significant differences in MIF will lead to poor PVDF compatibility, potentially reducing the product's mechanical strength and surface finish. Furthermore, insufficient addition of high MIF PVDF will not significantly alter the material's mechanical strength, while excessive addition will result in a yellowish PVDF product with severely reduced anti-aging properties, impacting its lifespan in photovoltaic applications. Only when the mass ratio of high MIF fluorinated resin to low MIF fluorinated resin is (1-2.5):(1-2) is the cost lower, mechanical properties significantly improved, and the product whiter with good anti-aging properties. For the above-mentioned blends of PVDF with different melt indices at specific mass ratios, the inventors discovered that a single-screw extruder extrusion temperature of 190-200℃ can effectively achieve co-extrusion. If the extrusion temperature is too low, surface defects such as burrs and bubbles will appear on the product surface, affecting the product's appearance and quality. If the extrusion temperature is too high, problems such as bubbles, skin bursting, and scorching will occur. Only when the extrusion temperature is between 190-200℃ does the blending effect of PVDF with different melt indices in this invention improve, resulting in a smooth and even product surface with better mechanical properties.

[0014] Preferably, the traction calendering involves feeding the material extruded from the screw into a three-roll calender for traction calendering. The three-roll calender has an upper roll speed of 0.2-0.3 rpm, a middle roll speed of 0.2-0.3 rpm, and a lower roll speed of 0.2-0.3 rpm; an upper roll temperature of 100-105℃, a middle roll temperature of 102-107℃, and a lower roll temperature of 105-110℃; a first traction force of 0.24-0.25 kN; a second traction force of 0.245-0.26 kN; and upper roll speeds, such as 0.2 rpm, 0.215 rpm, 0.23 rpm, or 0.25 rpm, and middle roll speeds, such as 0.2 rpm, 0.217 rpm, or 0.215 rpm. The following parameters are listed: 0.23 rpm, 0.25 rpm; 0.205 rpm, 0.23 rpm, or 0.25 rpm; 100°C, 101°C, 102°C, 103°C, or 105°C; 102°C, 105°C, 106°C, or 107°C; 105°C, 107°C, 109°C, or 110°C; 0.24 KN, 0.241 KN, 0.245 KN, or 0.25 KN; 0.245 KN, 0.246 KN, 0.25 KN, or 0.255 KN.

[0015] Preferably, the electromagnetic wave heating is infrared heating, and the infrared heating temperature is 150-170℃; the infrared heating temperature may include 150℃, 155℃, 160℃, 165℃ or 170℃.

[0016] Preferably, the cooling roller cooling involves feeding the material obtained after the electromagnetic wave heating step into the cooling roller for cooling. The cooling roller temperature is 60-70°C, and the cooling roller temperature is 35-45°C. Examples of cooling roller temperatures include 60°C, 62°C, 65°C, 68°C, or 70°C. Examples of cooling roller temperatures include 35°C, 38°C, 40°C, 42°C, or 45°C.

[0017] Preferably, the temperature of the secondary drying is 90-100℃, and the drying time is 16-24 hours. As an example, the temperature of the secondary drying can be 90℃, 91℃, 92℃, 93℃, 94℃, 95℃, 96℃, 97℃, 98℃, 99℃ or 100℃; and the drying time can be 16 hours, 18 hours, 20 hours, 22 hours or 24 hours.

[0018] After PVDF is cooled by cooling rollers, its toughness and hardness are still relatively poor. In order to further improve the mechanical properties of PVDF, a secondary heat-drying treatment is required. This can reduce the compression ratio of the plastic and remove some air, thereby increasing the toughness of the material itself. However, PVDF compounded at different melt indices can only be toughened at specific temperatures. The inventors found that the effect is best when the secondary heat-drying temperature is 90-100℃ and the secondary heat-drying time is 16-24h. Since the compatibility between high melt index PVDF and low melt index PVDF is limited, if the secondary heat-drying temperature is too high, the toughness of the material will decrease. If the secondary heat-drying temperature is too low, the toughening effect of the material is not obvious.

[0019] Beneficial effects

[0020] (I) In this invention, by limiting the fluorinated resin to a blend of high melt index fluorinated resin and low melt index fluorinated resin, with the high melt index fluorinated resin having a melt index of 5-7 g / 10 min and the low melt index fluorinated resin having a melt index of 3-5 g / 10 min, and the mass ratio of the high melt index fluorinated resin to the low melt index fluorinated resin being (1-2.5):(1-2), the problem of poor mechanical properties of the material can be significantly improved. In addition, the finished product obtained by processing is white in color and does not yellow, and its anti-aging performance is not significantly affected.

[0021] (ii) The present invention uses specific processing steps including: (1) mixing and drying; (2) screw extrusion; (3) traction calendering; (4) electromagnetic wave heating; (5) cooling roller cooling; (6) secondary drying; the final product has excellent mechanical properties and high surface flatness, and the product will not turn yellow.

[0022] (III) In this invention, the toughness of the PVDF finished product can be further improved by performing a secondary drying process after cooling with a cooling roller, under specific drying temperature and drying time.

[0023] (iv) In this invention, the surface finish of the material is significantly improved by heating it with electromagnetic waves after traction calendering and then cooling it with cooling rollers, and it is also beneficial to improve the toughness of the material.

[0024] (v) In this invention, the material processing technology is relatively simple, and the use of chemical solvents is avoided, making it green, environmentally friendly and low-cost. Detailed Implementation

[0025] Example 1

[0026] The first aspect of this embodiment provides a material that can be used in photovoltaic equipment. The raw materials of the material are high melt index PVDF and low melt index PVDF. The melt index of high melt index PVDF is 5.8 g / 10 min, the melt index of low melt index PVDF is 4.1 g / 10 min, and the mass ratio of high melt index PVDF to low melt index PVDF is 1:1.

[0027] The high melt flow index PVDF was purchased from Zhejiang Funolin, and the low melt flow index PVDF was purchased from Shandong Huaxia Shenzhou New Materials Co., Ltd.

[0028] The second aspect of this embodiment provides a material processing technology that can be used in photovoltaic equipment, comprising the following steps: (1) mixing and hot drying; (2) screw extrusion; (3) traction calendering; (4) electromagnetic wave heating; (5) cooling roller cooling; and (6) secondary hot drying.

[0029] The aforementioned mixing and drying process involves mixing high melt index fluorinated resin and low melt index fluorinated resin evenly according to a mass ratio, and then drying at 90°C for 4 hours.

[0030] The screw extrusion process involves feeding the mixed and dried material into a single-screw extruder for extrusion. The temperatures of the single-screw extruder are 200°C in zone 1, 200°C in zone 2, 200°C in zone 3, and 200°C in zone 4; the die head temperature is 225°C; and the screw speed is 60 rpm.

[0031] The aforementioned traction calendering involves feeding the material extruded by the screw into a three-roll calender for traction calendering. The three-roll calender has an upper roll speed of 0.215 rpm, a middle roll speed of 0.217 rpm, and a lower roll speed of 0.205 rpm. The upper roll temperature, middle roll temperature, and lower roll temperature are all 102°C and 107°C, respectively. The first traction force is 0.241 kN, and the second traction force is 0.246 kN.

[0032] The electromagnetic wave heating is infrared heating, and the infrared heating temperature is 155℃.

[0033] The cooling roller cooling process involves feeding the material obtained after the electromagnetic wave heating step into the cooling roller for cooling. The temperature of the cooling roller is 65°C, and the temperature of the cooling roller is 40°C.

[0034] The secondary drying temperature is 95℃, and the secondary drying time is 18 hours.

[0035] Example 2

[0036] The first aspect of this embodiment provides a material that can be used in photovoltaic devices. The material is high melt index PVDF and low melt index PVDF. The melt index of high melt index PVDF is 5.8 g / 10 min, the melt index of low melt index PVDF is 4.1 g / 10 min, and the mass ratio of high melt index PVDF to low melt index PVDF is 6:5.

[0037] The high melt flow index PVDF was purchased from Zhejiang Funolin, and the low melt flow index PVDF was purchased from Shandong Huaxia Shenzhou New Materials Co., Ltd.

[0038] The second aspect of this embodiment provides a material processing technology that can be used in photovoltaic equipment, comprising the following steps: (1) mixing and hot drying; (2) screw extrusion; (3) traction calendering; (4) electromagnetic wave heating; (5) cooling roller cooling; and (6) secondary hot drying.

[0039] The aforementioned mixing and drying process involves mixing high melt index fluorinated resin and low melt index fluorinated resin evenly according to a mass ratio, and then drying at 90°C for 4 hours.

[0040] The screw extrusion process involves feeding the mixed and dried material into a single-screw extruder for extrusion. The temperatures of the single-screw extruder are 200°C in zone 1, 200°C in zone 2, 200°C in zone 3, and 200°C in zone 4; the die head temperature is 225°C; and the screw speed is 60 rpm.

[0041] The aforementioned traction calendering involves feeding the material extruded by the screw into a three-roll calender for traction calendering. The three-roll calender has an upper roll speed of 0.23 rpm, a middle roll speed of 0.23 rpm, and a lower roll speed of 0.23 rpm. The upper roll temperature of the three-roll calender is 104°C, the middle roll temperature is 104°C, and the lower roll temperature is 110°C. The first traction force is 0.241 kN, and the second traction force is 0.246 kN.

[0042] The electromagnetic wave heating is infrared heating, and the infrared heating temperature is 150℃.

[0043] The cooling roller cooling process involves feeding the material obtained after the electromagnetic wave heating step into the cooling roller for cooling. The temperature of the cooling roller is 65°C, and the temperature of the cooling roller is 40°C.

[0044] The secondary drying temperature is 95℃, and the secondary drying time is 24 hours.

[0045] Comparative Example 1

[0046] The first aspect of this comparative example provides a material that can be used in photovoltaic devices. The material is high melt index PVDF and low melt index PVDF. The melt index of the high melt index PVDF is 11 g / 10 min, and the melt index of the low melt index PVDF is 4.1 g / 10 min. The mass ratio of the high melt index PVDF to the low melt index PVDF is 3:1.

[0047] The high melt flow index PVDF was purchased from Arkema, France, and the low melt flow index PVDF was purchased from Shandong Huaxia Shenzhou New Materials Co., Ltd.

[0048] The second aspect of this comparative example provides a processing technology for a material that can be used in photovoltaic equipment, comprising the following steps: (1) mixing and drying; (2) screw extrusion; (3) traction calendering; (4) electromagnetic wave heating; (5) cooling roller cooling; and (6) secondary drying.

[0049] The aforementioned mixing and drying process involves mixing high melt index fluorinated resin and low melt index fluorinated resin evenly according to a mass ratio, and then drying at 90°C for 4 hours.

[0050] The screw extrusion process involves feeding the mixed and dried material into a single-screw extruder for extrusion. The temperatures of the single-screw extruder are 200°C in zone 1, 200°C in zone 2, 200°C in zone 3, and 200°C in zone 4; the die head temperature is 225°C; and the screw speed is 60 rpm.

[0051] The aforementioned traction calendering involves feeding the material extruded by the screw into a three-roll calender for traction calendering. The three-roll calender has an upper roll speed of 0.215 rpm, a middle roll speed of 0.217 rpm, and a lower roll speed of 0.205 rpm. The upper roll temperature, middle roll temperature, and lower roll temperature are all 102°C and 107°C, respectively. The first traction force is 0.241 kN, and the second traction force is 0.246 kN.

[0052] The electromagnetic wave heating is infrared heating, and the infrared heating temperature is 155℃.

[0053] The cooling roller cooling process involves feeding the material obtained after the electromagnetic wave heating step into the cooling roller for cooling. The temperature of the cooling roller is 65°C, and the temperature of the cooling roller is 40°C.

[0054] The secondary drying temperature is 95℃, and the secondary drying time is 18 hours.

[0055] Comparative Example 2

[0056] The first aspect of this comparative example provides a material that can be used in photovoltaic devices, wherein the material is PVDF and the melt flow index of PVDF is 5.8 g / 10 min.

[0057] The PVDF was purchased from Zhejiang Funolin.

[0058] The second aspect of this embodiment provides a material processing technology that can be used in photovoltaic equipment, comprising the following steps: (1) mixing and hot drying; (2) screw extrusion; (3) traction calendering; (4) electromagnetic wave heating; (5) cooling roller cooling; and (6) secondary hot drying.

[0059] The aforementioned mixing and drying process involves drying PVDF at 90°C for 4 hours.

[0060] The screw extrusion process involves feeding the mixed and dried material into a single-screw extruder for extrusion. The temperatures of the single-screw extruder are 200°C in zone 1, 200°C in zone 2, 200°C in zone 3, and 200°C in zone 4; the die head temperature is 225°C; and the screw speed is 60 rpm.

[0061] The aforementioned traction calendering involves feeding the material extruded by the screw into a three-roll calender for traction calendering. The three-roll calender has an upper roll speed of 0.215 rpm, a middle roll speed of 0.217 rpm, and a lower roll speed of 0.205 rpm. The upper roll temperature, middle roll temperature, and lower roll temperature are all 102°C and 107°C, respectively. The first traction force is 0.241 kN, and the second traction force is 0.246 kN.

[0062] The electromagnetic wave heating is infrared heating, and the infrared heating temperature is 120℃.

[0063] The cooling roller cooling process involves feeding the material obtained after the electromagnetic wave heating step into the cooling roller for cooling. The temperature of the cooling roller is 65°C, and the temperature of the cooling roller is 40°C.

[0064] The secondary drying temperature is 60℃, and the secondary drying time is 12 hours.

[0065] Performance Evaluation

[0066] 1. Material Hardness Test: Test Objects: Materials prepared in Examples 1-2 and Comparative Examples 1-2 that can be used in photovoltaic equipment. Test Method: Refer to ISO 2039-2:2017 and record the corresponding test results in Table 1.

[0067] 2. Surface Smoothness Test: Test Object: Materials prepared in Examples 1-2 and Comparative Examples 1-2 that can be used in photovoltaic equipment. Test Method: Observe whether the surface of the prepared product is smooth and free of pits, and record the results in Table 1. 3. Material Color Test: Test Object: Materials prepared in Examples 1-2 and Comparative Examples 1-2 that can be used in photovoltaic equipment. Test Method: Observe the color of the surface of the prepared product to see if it is yellowish, and record the results in Table 1.

[0068] Table 1

[0069] Hardness (degrees) Surface smoothness Material color Example 1 86 Smooth and flat surface without pits Pure white, without yellowing Example 2 84 Smooth and flat surface without pits Pure white, without yellowing Comparative Example 1 81 Smooth and flat surface without pits Yellowish surface Comparative Example 2 78 The surface is not smooth and has pits. Yellowish surface

Claims

1. A processing technology for materials that can be used in photovoltaic equipment, characterized in that: The process includes at least the following steps: (1) mixing and drying; (2) screw extrusion; (3) traction calendering; (4) electromagnetic wave heating; (5) cooling roller cooling; and (6) secondary drying. The raw materials for preparing the material include high melt index fluorinated resin and low melt index fluorinated resin. The melt index of the high melt index fluorinated resin is 5-7 g / 10 min, and the melt index of the low melt index fluorinated resin is 3-5 g / 10 min. The mass ratio of the high melt index fluorinated resin to the low melt index fluorinated resin is (1-2.5):(1-2). The high melt index fluorinated resin and the low melt index fluorinated resin have different melt indices; The high melt flow index fluorinated resin is polyvinylidene fluoride; The low melt flow index fluorinated resin is polyvinylidene fluoride; The electromagnetic wave heating mentioned above includes at least infrared heating, and the infrared heating temperature is 150-170℃; The secondary drying temperature is 90-100℃, and the secondary drying time is 16-24 hours; The cooling roller cooling process involves feeding the material obtained after the electromagnetic wave heating step into the cooling roller for cooling. The cooling roller temperature is 60-70℃, and the cooling roller temperature is 35-45℃.

2. The processing technology for materials applicable to photovoltaic equipment according to claim 1, characterized in that: The aforementioned mixing and drying involves uniformly mixing high melt index fluorinated resin and low melt index fluorinated resin, and then drying them at a certain temperature. The temperature of the mixing and drying process is 80-100℃, and the drying time is 3-5 hours.

3. The processing technology for materials applicable to photovoltaic equipment according to claim 1, characterized in that: The screw extrusion process involves feeding the material obtained after mixing and drying into a single-screw extruder for extrusion. The extrusion temperature of the single-screw extruder is 190-200℃ in zone 1, 190-200℃ in zone 2, 190-200℃ in zone 3, and 190-200℃ in zone 4. The die temperature of the single-screw extruder is 220-240℃, and the screw speed is 50-80 rpm.

4. The processing technology for materials applicable to photovoltaic equipment according to claim 1, characterized in that: The aforementioned traction calendering involves feeding the material extruded by the screw into a three-roll calender for traction calendering. The rotational speed of the upper roller of the three-roll calender is 0.2-0.3 rpm, the rotational speed of the middle roller is 0.2-0.3 rpm, and the rotational speed of the lower roller is 0.2-0.3 rpm. The temperature of the upper roller of the three-roll calender is 100-105℃, the temperature of the middle roller is 102-107℃, and the temperature of the lower roller is 105-110℃. The first traction force is 0.24-0.25 kN, and the second traction force is 0.245-0.26 kN.