Nonwoven fabric for photovoltaic module and process for producing the same

Abstract

This invention discloses a nonwoven fabric for photovoltaic tabletop paper and its preparation process, relating to the field of nonwoven fabric production technology. It is made from the following raw materials in parts by weight: 50-60 parts PET polyester chips, 10-20 parts carboxyl-terminated hyperbranched polyester, 15-25 parts poly(2,3,5,6-tetrafluoroterephthalic acid) 4,8-tricyclo[5.2.1.O2,7]decanediethanol ester, 0.8-1.5 parts coupling agent, 0.5-1 part antioxidant, 1-3 parts plasticizer, 5-8 parts filler, 2-4 parts aziridine crosslinking agent, and 0.5-1.5 parts chitosan quaternary ammonium salt. The nonwoven fabric for photovoltaic tabletop paper disclosed in this invention exhibits excellent mechanical properties, good air permeability and smoothness, and superior thermal stability and aging resistance.

Description

Technical Field

[0001] This invention relates to the field of nonwoven fabric production technology, and in particular to a nonwoven fabric for photovoltaic tabletop paper and its preparation process. Background Technology

[0002] Screen printing is a crucial process in photovoltaic (PV) cell production. It uses printing adhesive strips to expel a printing paste, forcing it through the holes in the screen and onto the cell's through-holes or surface. During screen printing, a dedicated PV printing platen is required on the printing table. The performance of this platen directly impacts the silicon wafer and the final screen printing result; therefore, using PV printing platen with excellent overall performance and stability is essential for PV cell production.

[0003] Nonwoven fabric is a common raw material for making photovoltaic panel paper. It is made by orienting or randomly arranging short textile fibers or filaments to form a fiber web structure, and then reinforcing it by mechanical, thermal bonding, or chemical methods. Existing nonwoven fabrics have more or less defects such as limited tensile strength, poor air permeability and smoothness, and thermal stability and aging resistance need to be further improved.

[0004] To address the aforementioned issues, Chinese invention patent ZL202211056483.8 discloses a nonwoven fabric for photovoltaic tabletop paper and its production method. The production method includes mixing polyester fibers and low-melting-point adhesive fibers to form a slurry, diluting the slurry, forming it into a web, and drying it to obtain a first nonwoven fabric. A prepared coating is then uniformly applied to the surface of the first nonwoven fabric, and after drying, a second nonwoven fabric is obtained. The second nonwoven fabric is then subjected to hot-pressing treatment, rewound, and slit to obtain the nonwoven fabric for photovoltaic tabletop paper. Through this method, the invention effectively improves the surface strength and smoothness of the nonwoven fabric, resulting in a nonwoven fabric with high tensile strength in both the longitudinal and transverse directions, good uniformity, good thickness consistency, and high air permeability, meeting the performance requirements for nonwoven fabric used in photovoltaic tabletop paper. Furthermore, the production method is simple, highly controllable, and meets the needs of industrial production, possessing high practical application value. However, the heat resistance and aging resistance of this nonwoven fabric material need further improvement.

[0005] Therefore, developing a nonwoven fabric for photovoltaic tabletop paper with excellent mechanical properties, good air permeability and smoothness, and superior thermal stability and aging resistance, as well as its preparation process, meets market demand, has broad market value and application prospects, and is of great significance to promoting the development of the photovoltaic tabletop paper field. Summary of the Invention

[0006] The main objective of this invention is to provide a nonwoven fabric for photovoltaic platform paper with excellent mechanical properties, good air permeability and smoothness, and excellent thermal stability and aging resistance, as well as its preparation process.

[0007] To achieve the above objectives, the present invention provides a nonwoven fabric for photovoltaic tabletop paper, which is made from the following raw materials in parts by weight: 50-60 parts of PET polyester chips, 10-20 parts of carboxyl-terminated hyperbranched polyester, 15-25 parts of poly(2,3,5,6-tetrafluoroterephthalic acid) 4,8-tricyclo[5.2.1.O2,7]decanediethanol ester, 0.8-1.5 parts of coupling agent, 0.5-1 part of antioxidant, 1-3 parts of plasticizer, 5-8 parts of filler, 2-4 parts of aziridine crosslinking agent, and 0.5-1.5 parts of chitosan quaternary ammonium salt.

[0008] Preferably, the PET polyester chips are BRN-24 bright polyester chips produced by Sinopec.

[0009] Preferably, there are no special requirements regarding the source of the end-carboxyl hyperbranched polyester. In one embodiment of the present invention, the end-carboxyl hyperbranched polyester is at least one of HyPer C403 and HyPer C404 produced by Wuhan Hyperbranched Resin Technology Co., Ltd.

[0010] Preferably, the preparation method of the poly(2,3,5,6-tetrafluoroterephthalic acid) 4,8-tricyclo[5.2.1.O2,7]decanediethanol comprises the following steps: adding 2,3,5,6-tetrafluoroterephthalic acid, 4,8-tricyclo[5.2.1.O2,7]decanediethanol, dicyclohexylcarbodiimide (DCC), 4-dimethylaminopyridine (DMAP), and a catalyst to a high-boiling-point solvent, stirring until homogeneous, transferring to a high-pressure reactor, replacing the air in the reactor with an inert gas, and heating at 100°C. Esterification was carried out at 120℃ for 4-6 hours, with water being fractionated off during the reaction to obtain oligomers. Then, polycondensation was carried out at a reaction pressure of 30-80 kPa and a temperature of 235-250℃ for 4-6 hours. After the reaction was completed, the pressure and temperature were adjusted to normal, and the polymer was allowed to settle in water. The settled polymer was washed with ethanol 3-6 times. Finally, it was dried in a vacuum drying oven at 85-95℃ to constant weight to obtain 2,3,5,6-tetrafluoroterephthalic acid 4,8-tricyclo[5.2.1.O2,7]decanediethanol ester.

[0011] Preferably, the molar ratio of 2,3,5,6-tetrafluoroterephthalic acid, 4,8-tricyclo[5.2.1.O2,7]decanediethanol, dicyclohexylcarbodiimide (DCC), 4-dimethylaminopyridine (DMAP), catalyst, and high-boiling-point solvent is 1:1:(0.6-1):0.5:(0.3-0.5):(6-10).

[0012] Preferably, the catalyst is a mixture of tetrabutyl titanate and tetraisopropyl titanate in a mass ratio of 1:(0.8-1.2).

[0013] Preferably, the high-boiling-point solvent is dimethyl sulfoxide; the inert gas is any one of nitrogen, helium, and neon.

[0014] Preferably, the coupling agent is at least one of silane coupling agent KH550, silane coupling agent KH560, and silane coupling agent KH570; the antioxidant is one or more of antioxidant 1010, antioxidant 1076, antioxidant 1098, and antioxidant 168; the plasticizer is epoxidized soybean oil; and the filler is calcium carbonate with a particle size of 800-1000 mesh.

[0015] Preferably, the aziridine crosslinking agent is aziridine crosslinking agent XR-100; the chitosan quaternary ammonium salt has a molecular weight of 100,000 and a degree of substitution of 90%, and is provided by Shanghai Yuanye Biotechnology Co., Ltd., with the product number S26618-500g.

[0016] Another objective of this invention is to provide a preparation process for the nonwoven fabric for photovoltaic tabletop paper, comprising the following steps: mixing PET polyester chips, carboxyl-terminated hyperbranched polyester, poly(2,3,5,6-tetrafluoroterephthalic acid 4,8-tricyclo[5.2.1.O2,7]decanediethanol ester, coupling agent, antioxidant, plasticizer, and filler in proportion to weight to obtain a mixture; then adding the mixture to a twin-screw extruder for sequential melt-blowing, web forming, rolling mill pressing into fabric, soaking in a modifying liquid, drying and curing, washing with water, and drying again to produce the nonwoven fabric for photovoltaic tabletop paper.

[0017] Preferably, the temperature during the rolling mill is 120℃-160℃, and the speed at which the nonwoven fabric passes through the hot rollers of the rolling mill is 180-300 rpm.

[0018] Preferably, the modified liquid is a mixture of aziridine crosslinking agent and chitosan quaternary ammonium salt; the mass of water solvent contained therein is 70-80 wt% of the total mass of the mixture.

[0019] Preferably, the drying and curing temperature is 60-80℃ and the time is 2-4 hours.

[0020] Due to the application of the above technical solution, the present invention has the following beneficial effects:

[0021] (1) The preparation process of nonwoven fabric for photovoltaic tabletop paper disclosed in this invention can be achieved with conventional equipment, with low energy consumption, low capital investment, high preparation efficiency and high finished product qualification rate, and is suitable for continuous large-scale production.

[0022] (2) The nonwoven fabric for photovoltaic tabletop paper disclosed in this invention is made from the following raw materials in parts by weight: 50-60 parts PET polyester chips, 10-20 parts carboxyl-terminated hyperbranched polyester, 15-25 parts poly(2,3,5,6-tetrafluoroterephthalic acid) 4,8-tricyclo[5.2.1.O2,7]decanediethanol ester, 0.8-1.5 parts coupling agent, 0.5-1 part antioxidant, 1-3 parts plasticizer, 5-8 parts filler, 2-4 parts aziridine crosslinking agent, and 0.5-1.5 parts chitosan quaternary ammonium salt. Through the synergistic effect of the various raw materials, the resulting nonwoven fabric has excellent mechanical properties, good air permeability and smoothness, and excellent thermal stability and aging resistance.

[0023] (3) The photovoltaic tabletop paper nonwoven fabric disclosed in this invention uses PET polyester chips as the base material and blends them with carboxyl-terminated hyperbranched polyester and poly(2,3,5,6-tetrafluoroterephthalic acid 4,8-tricyclo[5.2.1.O2,7]decanedimethyl ester, combining the advantages of these materials, resulting in a nonwoven fabric with high tensile strength, low heat shrinkage, good thermal stability, smooth surface, and excellent aging resistance; these materials all contain aromatic polyester structures, which makes them compatible and have sufficient performance stability; 2,3, 5,6-Tetrafluoroterephthalic acid 4,8-tricyclo[5.2.1.O2,7]decanediethanol ester is formed by a head-to-tail esterification polycondensation reaction of 2,3,5,6-tetrafluoroterephthalic acid and 4,8-tricyclo[5.2.1.O2,7]decanediethanol. Tricycloalkane and tetrafluorobenzene structures are introduced into the polymer molecular chain at the same time. With the coordination of other structures and groups, under the multiple effects of electronic effect, steric effect and conjugation effect, the aging resistance, smoothness and mechanical properties of the prepared material are further improved.

[0024] (4) The nonwoven fabric for photovoltaic tabletop paper disclosed in this invention has carboxyl groups on the end-carboxyl hyperbranched polyester that can react chemically with aziridine crosslinking agent and chitosan quaternary ammonium salt to form a surface interpenetrating network crosslinking structure, which further improves the aging resistance and heat resistance of the material and makes its performance stability higher. By modifying the surface of the nonwoven fabric by soaking in the modification liquid, the uneven areas of the surface can be filled, further improving the smoothness, and the formed crosslinking structure can also effectively extend the service life of the material. Detailed Implementation

[0025] The following description is intended to disclose the invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art. Example 1

[0026] A nonwoven fabric for photovoltaic tabletop paper is made from the following raw materials in parts by weight: 50 parts PET polyester chips, 10 parts carboxyl-terminated hyperbranched polyester, 15 parts poly(2,3,5,6-tetrafluoroterephthalic acid) 4,8-tricyclo[5.2.1.O2,7]decanediethanol ester, 0.8 parts coupling agent, 0.5 parts antioxidant, 1 part plasticizer, 5 parts filler, 2 parts aziridine crosslinking agent, and 0.5 parts chitosan quaternary ammonium salt.

[0027] The PET polyester chips are BRN-24 bright polyester chips produced by Sinopec; the carboxyl-terminated hyperbranched polyester is HyPer C403 produced by Wuhan Hyperbranched Resin Technology Co., Ltd.

[0028] The preparation method of the poly(2,3,5,6-tetrafluoroterephthalic acid 4,8-tricyclo[5.2.1.O2,7]decanediethanol ester includes the following steps: 2,3,5,6-tetrafluoroterephthalic acid, 4,8-tricyclo[5.2.1.O2,7]decanediethanol, dicyclohexylcarbodiimide (DCC), 4-dimethylaminopyridine (DMAP), and a catalyst are added to a high-boiling-point solvent, stirred evenly, and then transferred to a high-pressure reactor. The air inside the reactor is replaced with an inert gas, and an esterification reaction is carried out at 100°C for 4 hours. Water is fractionated off during the reaction to obtain the oligomer. Then, a polycondensation reaction is carried out at a reaction pressure of 30 kPa and 235°C for 4 hours. After the reaction, the pressure and temperature are adjusted to normal, and the product is then subjected to a polycondensation reaction in water. The polymer was settled in a vacuum oven and washed three times with ethanol. Finally, it was dried to constant weight at 85°C to obtain 2,3,5,6-tetrafluoroterephthalic acid 4,8-tricyclo[5.2.1.O2,7]decanediethanol ester. The molar ratio of 2,3,5,6-tetrafluoroterephthalic acid, 4,8-tricyclo[5.2.1.O2,7]decanediethanol, dicyclohexylcarbodiimide (DCC), 4-dimethylaminopyridine (DMAP), catalyst, and high-boiling solvent was 1:1:0.6:0.5:0.3:6. The catalyst was a mixture of tetrabutyl titanate and tetraisopropyl titanate in a mass ratio of 1:0.8. The high-boiling solvent was dimethyl sulfoxide. The inert gas was nitrogen. GPC testing showed that the polymer's M... n =14620 g / mol, M W / M n =1.338.

[0029] The coupling agent is silane coupling agent KH550; the antioxidant is antioxidant 1010; the plasticizer is epoxidized soybean oil; the filler is calcium carbonate with a particle size of 800 mesh; the aziridine crosslinking agent is aziridine crosslinking agent XR-100; the chitosan quaternary ammonium salt has a molecular weight of 100,000 and a degree of substitution of 90%, and is provided by Shanghai Yuanye Biotechnology Co., Ltd., with product number S26618-500g.

[0030] A process for preparing nonwoven fabric for photovoltaic tabletop paper includes the following steps: PET polyester chips, carboxyl-terminated hyperbranched polyester, poly(2,3,5,6-tetrafluoroterephthalic acid 4,8-tricyclo[5.2.1.O2,7]decanediethanol ester, coupling agent, antioxidant, plasticizer, and filler are mixed evenly according to weight parts to obtain a mixture. The mixture is then added to a twin-screw extruder and sequentially subjected to melt-blowing, web forming, rolling mill pressing into fabric, soaking in a modifying liquid, drying and curing, washing with water, and further drying to produce nonwoven fabric for photovoltaic tabletop paper. The rolling mill pressing temperature is 120℃, and the speed of the nonwoven fabric passing through the hot rollers of the rolling mill is 180 rpm. The modifying liquid is a mixture of aziridine crosslinking agent and chitosan quaternary ammonium salt, containing water as a solvent at a mass of 70 wt% of the total mass of the mixture. The drying and curing temperature is 60℃, and the time is 2 hours. Example 2

[0031] A nonwoven fabric for photovoltaic tabletop paper is made from the following raw materials in parts by weight: 52 parts PET polyester chips, 12 parts carboxyl-terminated hyperbranched polyester, 17 parts poly(2,3,5,6-tetrafluoroterephthalic acid) 4,8-tricyclo[5.2.1.O2,7]decanediethanol ester, 1 part coupling agent, 0.6 parts antioxidant, 1.5 parts plasticizer, 6 parts filler, 2.5 parts aziridine crosslinking agent, and 0.7 parts chitosan quaternary ammonium salt.

[0032] The PET polyester chips are BRN-24 bright polyester chips produced by Sinopec; the carboxyl-terminated hyperbranched polyester is HyPer C404 produced by Wuhan Hyperbranched Resin Technology Co., Ltd.

[0033] The preparation method of the poly(2,3,5,6-tetrafluoroterephthalic acid) 4,8-tricyclo[5.2.1.O2,7]decanediethanol ester includes the following steps: 2,3,5,6-tetrafluoroterephthalic acid, 4,8-tricyclo[5.2.1.O2,7]decanediethanol, dicyclohexylcarbodiimide (DCC), 4-dimethylaminopyridine (DMAP), and a catalyst are added to a high-boiling-point solvent, stirred evenly, and then transferred to a high-pressure reactor. The air inside the reactor is replaced with an inert gas, and an esterification reaction is carried out at 105°C for 4.5 hours. Water is fractionated off during the reaction to obtain the oligomer. Then, a polycondensation reaction is carried out at a reaction pressure of 50 kPa and 240°C for 4.5 hours. After the reaction is completed, the pressure and temperature are adjusted to normal. The polymer was settled in water and washed four times with ethanol. Finally, it was dried in a vacuum drying oven at 87°C to constant weight to obtain 2,3,5,6-tetrafluoroterephthalic acid 4,8-tricyclo[5.2.1.O2,7]decanediethanol ester. The molar ratio of 2,3,5,6-tetrafluoroterephthalic acid, 4,8-tricyclo[5.2.1.O2,7]decanediethanol, dicyclohexylcarbodiimide (DCC), 4-dimethylaminopyridine (DMAP), catalyst, and high-boiling solvent was 1:1:0.7:0.5:0.35:7. The catalyst was a mixture of tetrabutyl titanate and tetraisopropyl titanate in a mass ratio of 1:0.9. The high-boiling solvent was dimethyl sulfoxide. The inert gas was helium.

[0034] The coupling agent is silane coupling agent KH560; the antioxidant is antioxidant 1076; the plasticizer is epoxidized soybean oil; the filler is calcium carbonate with a particle size of 850 mesh; the aziridine crosslinking agent is aziridine crosslinking agent XR-100; the chitosan quaternary ammonium salt has a molecular weight of 100,000 and a degree of substitution of 90%, and is provided by Shanghai Yuanye Biotechnology Co., Ltd., with product number S26618-500g.

[0035] A process for preparing nonwoven fabric for photovoltaic tabletop paper includes the following steps: PET polyester chips, carboxyl-terminated hyperbranched polyester, poly(2,3,5,6-tetrafluoroterephthalic acid 4,8-tricyclo[5.2.1.O2,7]decanediethanol ester, coupling agent, antioxidant, plasticizer, and filler are mixed evenly according to weight parts to obtain a mixture. The mixture is then added to a twin-screw extruder and sequentially subjected to melt-blowing, web forming, rolling mill pressing into fabric, soaking in a modifying liquid, drying and curing, washing with water, and further drying to produce nonwoven fabric for photovoltaic tabletop paper. The rolling mill pressing temperature is 130℃, and the speed of the nonwoven fabric passing through the hot rollers of the rolling mill is 210 rpm. The modifying liquid is a mixture of aziridine crosslinking agent and chitosan quaternary ammonium salt; the mass of water as solvent is 73 wt% of the total mass of the mixture. The drying and curing temperature is 65℃, and the time is 2.5 hours. Example 3

[0036] A nonwoven fabric for photovoltaic tabletop paper is made from the following raw materials in parts by weight: 55 parts PET polyester chips, 15 parts carboxyl-terminated hyperbranched polyester, 20 parts poly(2,3,5,6-tetrafluoroterephthalic acid 4,8-tricyclo[5.2.1.O2,7]decanediethanol ester, 1.2 parts coupling agent, 0.7 parts antioxidant, 2 parts plasticizer, 6.5 parts filler, 3 parts aziridine crosslinking agent, and 1 part chitosan quaternary ammonium salt.

[0037] The PET polyester chips are BRN-24 bright polyester chips produced by Sinopec; the carboxyl-terminated hyperbranched polyester is HyPer C403 produced by Wuhan Hyperbranched Resin Technology Co., Ltd.

[0038] The preparation method of the poly(2,3,5,6-tetrafluoroterephthalic acid) 4,8-tricyclo[5.2.1.O2,7]decanediethanol ester includes the following steps: 2,3,5,6-tetrafluoroterephthalic acid, 4,8-tricyclo[5.2.1.O2,7]decanediethanol, dicyclohexylcarbodiimide (DCC), 4-dimethylaminopyridine (DMAP), and a catalyst are added to a high-boiling-point solvent, stirred evenly, and then transferred to a high-pressure reactor. The air inside the reactor is replaced with an inert gas, and an esterification reaction is carried out at 110°C for 5 hours. Water is fractionated off during the reaction to obtain the oligomer. Then, a polycondensation reaction is carried out at a reaction pressure of 60 kPa and 243°C for 5 hours. After the reaction, the pressure and temperature are adjusted to normal. The polymer was settled in water and washed five times with ethanol. Finally, it was dried in a vacuum drying oven at 90°C to constant weight to obtain 2,3,5,6-tetrafluoroterephthalic acid 4,8-tricyclo[5.2.1.O2,7]decanediethanol ester. The molar ratio of 2,3,5,6-tetrafluoroterephthalic acid, 4,8-tricyclo[5.2.1.O2,7]decanediethanol, dicyclohexylcarbodiimide (DCC), 4-dimethylaminopyridine (DMAP), catalyst, and high-boiling solvent was 1:1:0.8:0.5:0.4:8. The catalyst was a mixture of tetrabutyl titanate and tetraisopropyl titanate in a 1:1 mass ratio. The high-boiling solvent was dimethyl sulfoxide. The inert gas was neon.

[0039] The coupling agent is silane coupling agent KH570; the antioxidant is antioxidant 1098; the plasticizer is epoxidized soybean oil; the filler is calcium carbonate with a particle size of 900 mesh; the aziridine crosslinking agent is aziridine crosslinking agent XR-100; the chitosan quaternary ammonium salt has a molecular weight of 100,000 and a degree of substitution of 90%, and is provided by Shanghai Yuanye Biotechnology Co., Ltd., with product number S26618-500g.

[0040] A process for preparing nonwoven fabric for photovoltaic tabletop paper includes the following steps: PET polyester chips, carboxyl-terminated hyperbranched polyester, poly(2,3,5,6-tetrafluoroterephthalic acid 4,8-tricyclo[5.2.1.O2,7]decanediethanol ester, coupling agent, antioxidant, plasticizer, and filler are mixed evenly according to weight parts to obtain a mixture. The mixture is then added to a twin-screw extruder and sequentially subjected to melt-blowing, web forming, rolling mill pressing into fabric, soaking in a modifying liquid, drying and curing, washing with water, and further drying to produce nonwoven fabric for photovoltaic tabletop paper. The rolling mill pressing temperature is 140℃, and the speed of the nonwoven fabric passing through the hot rollers of the rolling mill is 240 rpm. The modifying liquid is a mixture of aziridine crosslinking agent and chitosan quaternary ammonium salt, containing water as a solvent at a mass of 75 wt% of the total mass of the mixture. The drying and curing temperature is 70℃, and the time is 3 hours. Example 4

[0041] A nonwoven fabric for photovoltaic tabletop paper is made from the following raw materials in parts by weight: 58 parts PET polyester chips, 18 parts carboxyl-terminated hyperbranched polyester, 23 parts poly(2,3,5,6-tetrafluoroterephthalic acid) 4,8-tricyclo[5.2.1.O2,7]decanediethanol ester, 1.3 parts coupling agent, 0.9 parts antioxidant, 2.5 parts plasticizer, 7.5 parts filler, 3.5 parts aziridine crosslinking agent, and 1.3 parts chitosan quaternary ammonium salt.

[0042] The PET polyester chips are BRN-24 bright polyester chips produced by Sinopec; the carboxyl-terminated hyperbranched polyester is a mixture of HyPer C403 and HyPer C404 produced by Wuhan Hyperbranched Resin Technology Co., Ltd., mixed in a mass ratio of 3:5.

[0043] The preparation method of the poly(2,3,5,6-tetrafluoroterephthalic acid) 4,8-tricyclo[5.2.1.O2,7]decanediethanol ester includes the following steps: 2,3,5,6-tetrafluoroterephthalic acid, 4,8-tricyclo[5.2.1.O2,7]decanediethanol, dicyclohexylcarbodiimide (DCC), 4-dimethylaminopyridine (DMAP), and a catalyst are added to a high-boiling-point solvent, stirred evenly, and then transferred to a high-pressure reactor. The air inside the reactor is replaced with an inert gas, and an esterification reaction is carried out at 118°C for 5.5 hours. Water is fractionated off during the reaction to obtain the oligomer. Then, a polycondensation reaction is carried out at a reaction pressure of 70 kPa and 248°C for 5.5 hours. After the reaction is completed, the pressure and temperature are adjusted to normal. The polymer was settled in water and washed six times with ethanol. Finally, it was dried in a vacuum drying oven at 93°C to constant weight to obtain 2,3,5,6-tetrafluoroterephthalic acid 4,8-tricyclo[5.2.1.O2,7]decanediethanol ester. The molar ratio of 2,3,5,6-tetrafluoroterephthalic acid, 4,8-tricyclo[5.2.1.O2,7]decanediethanol, dicyclohexylcarbodiimide (DCC), 4-dimethylaminopyridine (DMAP), catalyst, and high-boiling solvent was 1:1:0.9:0.5:0.45:9. The catalyst was a mixture of tetrabutyl titanate and tetraisopropyl titanate in a mass ratio of 1:1.1. The high-boiling solvent was dimethyl sulfoxide. The inert gas was nitrogen.

[0044] The coupling agent is a mixture of silane coupling agents KH550, KH560, and KH570 in a mass ratio of 1:2:2; the antioxidant is a mixture of antioxidants 1010, 1076, 1098, and 168 in a mass ratio of 1:1:2:2; the plasticizer is epoxidized soybean oil; the filler is calcium carbonate with a particle size of 950 mesh; the aziridine crosslinking agent is aziridine crosslinking agent XR-100; the chitosan quaternary ammonium salt has a molecular weight of 100,000 and a degree of substitution of 90%, and is provided by Shanghai Yuanye Biotechnology Co., Ltd., with product number S26618-500g.

[0045] A process for preparing nonwoven fabric for photovoltaic tabletop paper includes the following steps: PET polyester chips, carboxyl-terminated hyperbranched polyester, poly(2,3,5,6-tetrafluoroterephthalic acid 4,8-tricyclo[5.2.1.O2,7]decanediethanol ester, coupling agent, antioxidant, plasticizer, and filler are mixed evenly according to weight parts to obtain a mixture. The mixture is then added to a twin-screw extruder and sequentially subjected to melt-blowing, web forming, rolling mill pressing into fabric, soaking in a modifying liquid, drying and curing, washing with water, and further drying to produce nonwoven fabric for photovoltaic tabletop paper. The rolling mill pressing temperature is 155℃, and the speed of the nonwoven fabric passing through the hot rollers of the rolling mill is 290 rpm. The modifying liquid is a mixture of aziridine crosslinking agent and chitosan quaternary ammonium salt, containing water as a solvent at a mass of 78 wt% of the total mass of the mixture. The drying and curing temperature is 75℃, and the time is 3.5 hours. Example 5

[0046] A nonwoven fabric for photovoltaic tabletop paper is made from the following raw materials in parts by weight: 60 parts PET polyester chips, 20 parts carboxyl-terminated hyperbranched polyester, 25 parts poly(2,3,5,6-tetrafluoroterephthalic acid) 4,8-tricyclo[5.2.1.O2,7]decanediethanol ester, 1.5 parts coupling agent, 1 part antioxidant, 3 parts plasticizer, 8 parts filler, 4 parts aziridine crosslinking agent, and 1.5 parts chitosan quaternary ammonium salt.

[0047] The PET polyester chips are BRN-24 bright polyester chips produced by Sinopec; the carboxyl-terminated hyperbranched polyester is HyPer C403 produced by Wuhan Hyperbranched Resin Technology Co., Ltd.

[0048] The preparation method of the poly(2,3,5,6-tetrafluoroterephthalic acid) 4,8-tricyclo[5.2.1.O2,7]decanediethanol ester includes the following steps: 2,3,5,6-tetrafluoroterephthalic acid, 4,8-tricyclo[5.2.1.O2,7]decanediethanol, dicyclohexylcarbodiimide (DCC), 4-dimethylaminopyridine (DMAP), and a catalyst are added to a high-boiling-point solvent, stirred evenly, and then transferred to a high-pressure reactor. The air inside the reactor is replaced with an inert gas, and an esterification reaction is carried out at 120°C for 6 hours. Water is fractionated off during the reaction to obtain the oligomer; then, a polycondensation reaction is carried out at a reaction pressure of 80 kPa and 250°C for 6 hours to obtain the final product. After precipitation, the polymer was adjusted to normal pressure and temperature, settled in water, and washed six times with ethanol. Finally, it was dried in a vacuum drying oven at 95°C to constant weight to obtain 2,3,5,6-tetrafluoroterephthalic acid 4,8-tricyclo[5.2.1.O2,7]decanediethanol ester. The molar ratio of 2,3,5,6-tetrafluoroterephthalic acid, 4,8-tricyclo[5.2.1.O2,7]decanediethanol, dicyclohexylcarbodiimide (DCC), 4-dimethylaminopyridine (DMAP), catalyst, and high-boiling solvent was 1:1:1:0.5:0.5:10. The catalyst was a mixture of tetrabutyl titanate and tetraisopropyl titanate in a mass ratio of 1:1.2.

[0049] The high-boiling-point solvent is dimethyl sulfoxide; the inert gas is nitrogen; the coupling agent is silane coupling agent KH550; the antioxidant is antioxidant 168; the plasticizer is epoxidized soybean oil; the filler is calcium carbonate with a particle size of 1000 mesh; the aziridine crosslinking agent is aziridine crosslinking agent XR-100; the chitosan quaternary ammonium salt has a molecular weight of 100,000 and a degree of substitution of 90%, and is provided by Shanghai Yuanye Biotechnology Co., Ltd., with product number S26618-500g.

[0050] A process for preparing nonwoven fabric for photovoltaic tabletop paper includes the following steps: PET polyester chips, carboxyl-terminated hyperbranched polyester, poly(2,3,5,6-tetrafluoroterephthalic acid 4,8-tricyclo[5.2.1.O2,7]decanediethanol ester, coupling agent, antioxidant, plasticizer, and filler are mixed evenly according to weight parts to obtain a mixture. The mixture is then added to a twin-screw extruder and sequentially subjected to melt-blowing, web forming, rolling mill pressing into fabric, soaking in a modifying liquid, drying and curing, washing with water, and further drying to produce nonwoven fabric for photovoltaic tabletop paper. The rolling mill pressing temperature is 160℃, and the speed of the nonwoven fabric passing through the hot rollers of the rolling mill is 300 rpm. The modifying liquid is a mixture of aziridine crosslinking agent and chitosan quaternary ammonium salt, containing water as a solvent at a mass of 80 wt% of the total mass of the mixture. The drying and curing temperature is 80℃, and the time is 4 hours.

[0051] Comparative Example 1

[0052] A nonwoven fabric for photovoltaic tabletop paper has a similar formulation and preparation process to Example 1, except that PET polyester chips are used instead of poly(2,3,5,6-tetrafluoroterephthalic acid 4,8-tricyclo[5.2.1.O2,7]decanediethanol ester, and no aziridine crosslinking agent is added.

[0053] Comparative Example 2

[0054] A nonwoven fabric for photovoltaic tabletop paper has a formula and preparation process similar to that of Example 1, except that PET polyester chips are used instead of end-carboxyl hyperbranched polyester, and chitosan quaternary ammonium salt is not added.

[0055] To further illustrate the beneficial technical effects of the nonwoven fabrics for photovoltaic platform paper prepared in the various embodiments of the present invention, relevant performance tests were conducted on the nonwoven fabrics for photovoltaic platform paper prepared in Examples 1-5 and Comparative Examples 1-2. The test results are shown in Table 1, and the test methods are as follows:

[0056] (1) Bursting strength of nonwoven fabric: tested according to standard GB / T 24218.5-2016.

[0057] (2) Aging resistance: After the nonwoven fabric is placed in hot air at 85°C for 96 hours, the retention rate of burst strength is tested and calculated. The higher the value, the better the aging resistance.

[0058] (3) Smoothness: The smoothness was tested using the Asahi-seiko EBO1 digital smoothness testing machine from Japan.

[0059] (4) Air permeability: Tested according to the method in standard GB / T24218.15-2018.

[0060] Table 1

[0061] project Breaking through the powerful Frontal smoothness Aging resistance breathability unit N S % cfm Example 1 1230 29 98.8 6.6 Example 2 1236 32 99.1 6.7 Example 3 1240 33 99.6 7.0 Example 4 1248 35 99.8 7.2 Example 5 1253 36 99.9 7.5 Comparative Example 1 928 27 92.6 6.4 Comparative Example 2 916 25 94.2 6.0

[0062] As shown in Table 1, the nonwoven fabric for photovoltaic tabletops disclosed in this invention exhibits superior mechanical properties, aging resistance, smoothness, and breathability. The addition of poly(2,3,5,6-tetrafluoroterephthalic acid) 4,8-tricyclo[5.2.1.O2,7]decanediethanol ester (CAS: 26896-48-0), aziridine crosslinking agent, carboxyl-terminated hyperbranched polyester, and chitosan quaternary ammonium salt is beneficial in improving these properties.

[0063] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention. The scope of protection claimed by the appended claims and their equivalents is defined.

Claims

1. A nonwoven fabric for photovoltaic tabletop paper, characterized in that, It is made from the following raw materials in parts by weight: 50-60 parts PET polyester chips, 10-20 parts carboxyl-terminated hyperbranched polyester, 15-25 parts poly(2,3,5,6-tetrafluoroterephthalic acid) 4,8-tricyclo[5.2.1.O2,7]decanediethanol ester, 0.8-1.5 parts coupling agent, 0.5-1 part antioxidant, 1-3 parts plasticizer, 5-8 parts filler, 2-4 parts aziridine crosslinking agent, and 0.5-1.5 parts chitosan quaternary ammonium salt.

2. The photovoltaic deck sheet nonwoven fabric according to claim 1, characterized by The PET polyester chips are BRN-24 bright polyester chips produced by Sinopec.

3. The photovoltaic deck sheet nonwoven fabric according to claim 1, characterized by The end-carboxyl hyperbranched polyester is at least one of HyPer C403 and HyPer C404 produced by Wuhan Hyperbranched Resin Technology Co., Ltd.

4. The photovoltaic deck sheet nonwoven fabric according to claim 1, wherein The preparation method of the poly(2,3,5,6-tetrafluoroterephthalic acid) 4,8-tricyclo[5.2.1.O2,7]decanediethanol ester includes the following steps: adding 2,3,5,6-tetrafluoroterephthalic acid, 4,8-tricyclo[5.2.1.O2,7]decanediethanol, dicyclohexylcarbodiimide (DCC), 4-dimethylaminopyridine (DMAP), and a catalyst to a high-boiling-point solvent, stirring until homogeneous, transferring to a high-pressure reactor, replacing the air in the reactor with an inert gas, and heating at 100-1200°C. Esterification was carried out at 0℃ for 4-6 hours, with water being fractionated off during the reaction to obtain oligomers; then polycondensation was carried out at a reaction pressure of 30-80 kPa and 235-250℃ for 4-6 hours. After the reaction was completed, the pressure and temperature were adjusted to normal, and the polymer was settled in water. The settled polymer was washed with ethanol 3-6 times, and finally dried in a vacuum drying oven at 85-95℃ to constant weight to obtain 2,3,5,6-tetrafluoroterephthalic acid 4,8-tricyclo[5.2.1.O2,7]decanediethanol ester.

5. The photovoltaic deck sheet nonwoven fabric according to claim 4, wherein The molar ratio of 2,3,5,6-tetrafluoroterephthalic acid, 4,8-tricyclo[5.2.1.O2,7]decanediethanol, dicyclohexylcarbodiimide (DCC), 4-dimethylaminopyridine (DMAP), catalyst, and high-boiling solvent is 1:1:(0.6-1):0.5:(0.3-0.5):(6-10).

6. The photovoltaic deck sheet nonwoven fabric according to claim 4, wherein The catalyst is a mixture of tetrabutyl titanate and tetraisopropyl titanate in a mass ratio of 1:(0.8-1.2); the high-boiling solvent is dimethyl sulfoxide; and the inert gas is any one of nitrogen, helium, and neon.

7. The nonwoven fabric for photovoltaic tabletop paper according to claim 1, characterized in that, The coupling agent is at least one of silane coupling agent KH550, silane coupling agent KH560, and silane coupling agent KH570; the antioxidant is one or more of antioxidant 1010, antioxidant 1076, antioxidant 1098, and antioxidant 168; the plasticizer is epoxidized soybean oil; the filler is calcium carbonate, and the particle size of the filler is 800-1000 mesh.

8. The photovoltaic deck sheet nonwoven fabric according to claim 1, wherein The aziridine crosslinking agent is aziridine crosslinking agent XR-100; the chitosan quaternary ammonium salt has a molecular weight of 100,000 and a degree of substitution of 90%, and is provided by Shanghai Yuanye Biotechnology Co., Ltd., with the product number S26618-500g.

9. A process for preparing nonwoven fabric for photovoltaic platform paper according to any one of claims 1-8, characterized in that, The process includes the following steps: PET polyester chips, carboxyl-terminated hyperbranched polyester, poly(2,3,5,6-tetrafluoroterephthalic acid 4,8-tricyclo[5.2.1.O2,7]decanediethanol ester, coupling agent, antioxidant, plasticizer, and filler are mixed evenly according to their weight proportions to obtain a mixture. The mixture is then added to a twin-screw extruder and sequentially subjected to melt-blowing, web forming, rolling mill pressing into fabric, soaking in modified liquid, drying and curing, washing with water, and drying again to produce nonwoven fabric for photovoltaic tabletop paper.

10. The process for the preparation of a nonwoven fabric for photovoltaic deck paper according to claim 9, characterized in that, The rolling mill temperature is 120℃-160℃, and the nonwoven fabric passes through the hot rolling mill at a speed of 180-300 rpm; the modified liquid is a mixture of aziridine crosslinking agent and chitosan quaternary ammonium salt; the mass of solvent water contained in the mixture is 70-80 wt% of the total mass of the mixture; the drying and curing temperature is 60-80℃, and the time is 2-4 hours.