Fiber-reinforced recycled polyester material and preparation method thereof

Abstract

The invention discloses a fiber-reinforced regenerated polyester material and a preparation method thereof, belongs to the technical field of polyester regeneration, and is used for solving the technical problem that the impact resistance and flame retardance of regenerated polyester in the prior art need to be further improved. A porous composite structure is formed through ultrasonic treatment in a water medium by taking an organic silicon structure as an outer layer and taking modified polyurethane as an inner layer, an organic silicon structure of the outer layer and a silicon hydroxyl structure of the inner layer are hydrolyzed under an alkaline condition, so that the structures are tightly combined, and carboxyl is introduced to the surface of the fiber structure through modification of 4-trimethoxysilylbutyric acid, so that the surface of the fiber structure is enhanced. And depolymerizing a polyester material on the basis of the composite porous fiber, polymerizing to obtain regenerated polyester, and finally mixing the regenerated polyester with auxiliary materials to obtain the regenerated polyester material.

Description

Technical Field

[0001] The present invention relates to the technical field of polyester recycling, and particularly relates to a fiber-reinforced recycled polyester material and a preparation method thereof. Background Art

[0002] As an important innovation in the field of environmental protection, recycled polyester materials have gradually emerged in recent years, especially making remarkable progress in fiber reinforcement and flame retardancy. Initially, recycled polyester had limitations in terms of strength and durability, especially performing mediocrely in the face of fire and external impacts. However, through technical means such as adding flame retardants and fire-resistant fibers, its flame retardant performance has been greatly improved. The spread of flames in a fire has been effectively inhibited, and the release of toxic gases has been significantly reduced. At the same time, the addition of reinforcing materials such as glass fibers and carbon fibers has also enabled recycled polyester to achieve a breakthrough in impact resistance. The impact strength has been greatly improved, and it can maintain better toughness and stability under strong external forces, greatly reducing the risk of rupture. At the present stage, with the improvement of environmental protection requirements and the progress of technology, recycled polyester materials not only have excellent physical properties but also can effectively meet the market's demand for sustainable development.

[0003] In the prior art, CN118620353B discloses an impact-resistant recycled plastic and a preparation method thereof, which relates to the technical field of polymer materials. When preparing the impact-resistant recycled plastic, waste polyester is alcoholyzed with ethylene glycol to obtain a polyester oligomer. 2,5-dimercapto terephthalic acid is successively reacted with ethylene glycol and 2-(2H-benzotriazol-2-yl)-4-methyl-6-(2-propenyl)phenol to prepare an ultraviolet absorption monomer. The polyester oligomer, the ultraviolet absorption monomer, and dimethyl allyl malonate are polycondensed to obtain recycled polyester. Thiophene and 3-thiophene sulfonamide are polymerized and deposited on the surface of graphene to obtain polythiophene-coated graphene. The polythiophene-coated graphene is reacted with phenyl phosphite to obtain modified polythiophene-coated graphene. The recycled polyester and the modified polythiophene-coated graphene are mixed evenly and then molded by compression to obtain the impact-resistant recycled plastic.

[0004] However, after the alcoholysis of polyester in the above patent content, recycled polyester is prepared by re-polycondensation, and then mixed and compression-molded with modified polythiophene-coated graphene to obtain the impact-resistant recycled plastic. However, there is no carrier in the alcoholysis process, resulting in a slow alcoholysis process of the material and the need to further improve the degree of alcoholysis. Furthermore, while generating defects in the molecular chain of recycled polyester, it also makes the molecular weight distribution of recycled polyester uneven. In addition, the graphene structure, as an impact-resistant buffer layer, has a single structure and insufficient binding degree with the recycled polyester material, which easily leads to structural deviation during the combustion of the material, and further leads to the need to further improve the flame retardant performance and impact resistance of the material. Summary of the Invention

[0005] The object of the present invention is to provide a fiber-reinforced recycled polyester material and a preparation method thereof, which are used to solve the technical problem that the impact resistance and flame retardancy of recycled polyester in the prior art need to be further improved.

[0006] The object of the present invention can be achieved by the following technical solutions: A fiber-reinforced recycled polyester material, comprising the following raw materials in parts by weight: 80-100 parts of recycled polyester, 3-5 parts of heat stabilizer, 6-8 parts of lubricant, 3-5 parts of antioxidant, and 3-5 parts of ultraviolet absorber;

[0007] The preparation method of the recycled polyester comprises the following steps:

[0008] A1. Add the pretreated waste polyester and composite porous fiber into a high-pressure reaction kettle for depolymerization to obtain a depolymerized mixed solution;

[0009] A2. Add the depolymerized mixed solution, terephthalic acid, germanium dioxide, and dimethyl sulfoxide into a high-pressure reaction kettle. Raise the temperature of the high-pressure reaction kettle to 260-280 °C, control the pressure to 300-500 KPa, carry out a constant temperature and constant pressure reaction for 2-4 h, and perform post-treatment to obtain recycled polyester.

[0010] The reaction equation for preparing recycled polyester is:

[0011]

[0012] In the formula: " " represents the composite porous fiber.

[0013] The reaction principle for preparing recycled polyester is: Through the pore structure of the composite porous fiber, the uniform dispersion of the fluid is promoted, thereby improving the depolymerization efficiency of waste polyester, obtaining a depolymerized mixed solution, and during the high-temperature and high-pressure polymerization process, the carboxyl groups on the fiber structure participate in the reaction, hybridizing the spatial structure of the polyester chain segments, and at the same time, the organic silicon-aluminum composite on the surface forms a dense silicon-aluminum oxide protective layer during the high-temperature polymerization process, thereby preparing recycled polyester.

[0014] Furthermore, the heat stabilizer is one or more of calcium stearate and dibutyltin dilaurate; the lubricant is one or two of polyethylene oxide wax and montan wax; the antioxidant is one or two of tris(2,4-di-tert-butylphenyl) phosphate and cetyl-3,5-di-tert-butyl-4-hydroxybenzoate; the ultraviolet absorber is one or two of 2-hydroxy-4-octyloxybenzophenone and bis(2,2,6,6-tetramethylpiperidinol) sebacate.

[0015] Further, in step A1, the pretreatment operation includes: heating the waste polyester to melting, and then the melt first passes through a filter screen I with a particle size of 10 - 30 μm under a pressure of 1 - 2 MPa, and then passes through a filter screen II with a particle size of 5 - 8 μm under a pressure of 2 - 4 MPa. After the filtration is completed, it is naturally cured to obtain the pretreated waste polyester;

[0016] Further, in step A1, the dosage ratio of the pretreated waste polyester to the composite porous fiber is 8 - 10 g: 2 - 3 g. The depolymerization operation selects the supercritical carbon dioxide depolymerization process. The specific operation is as follows: Place the high-pressure reactor in a salt bath furnace. After using carbon dioxide gas to exhaust the air in the high-pressure reactor, use a pressurizing device to introduce 20 - 24 MPa of carbon dioxide gas into the high-pressure reactor. The temperature of the salt bath furnace rises to 120 - 160 °C. During the heating process, use a valve to release gas and relieve pressure to control the pressure in the reactor to be less than 24 MPa. Keep the reaction for 4 - 6 h. After the reaction is completed, wait for the pressure in the high-pressure reactor to drop to room temperature and pressure, and discharge the carbon dioxide gas to obtain the depolymerized mixture;

[0017] Further, in step A2, the dosage ratio of the depolymerized mixture, terephthalic acid, germanium dioxide, and dimethyl sulfoxide is 12 - 16 g: 1 - 2 g: 0.6 - 0.8 g: 40 - 60 mL. The post-treatment includes: After the reaction is completed, wait for the temperature of the reactor to drop to room temperature, transfer the reaction solution to a rotary evaporator, raise the temperature of the rotary evaporator to 60 - 80 °C, and perform vacuum distillation until no liquid is collected to obtain the regenerated polyester.

[0018] Further, the preparation method of the composite porous fiber includes the following steps:

[0019] B1. Add the composite fiber and deionized water to an ultrasonic device. After the temperature of the ultrasonic device rises to 40 °C, the frequency is 20 - 40 kHz. Keep the ultrasonic treatment for 10 - 12 h, and then perform post-treatment to obtain the composite porous fiber blank;

[0020] B2. Add the composite porous fiber blank, 4-trimethoxysilylbutyric acid, absolute ethanol, and deionized water to a reactor. After the temperature of the reactor rises to 40 - 60 °C, use a saturated sodium hydroxide aqueous solution to adjust the pH of the reaction system to 8 - 10, keep the reaction for 1 - 2 h, and then perform post-treatment to obtain the composite porous fiber.

[0021] The reaction principle for preparing the composite porous fiber is as follows: Under the conditions of heating and ultrasonic treatment, the polyvinylpyrrolidone component of the composite fiber melts, forming a porous structure in the outer and inner layer structures of the fiber, thereby obtaining the composite porous fiber blank. Under alkaline conditions, the silicon hydroxyl groups capped by the modified polyurethane component in the inner layer and the active structures generated by the hydrolysis of the outer layer organosilicon aluminum component crosslink, thereby optimizing the fiber structure. And after being modified by 4-trimethoxysilylbutyric acid, carboxyl groups are introduced into the fiber structure, and finally the composite porous fiber is prepared.

[0022] Further, in step B1, the dosage ratio of the composite fiber to deionized water is 1-2 g: 10 mL. The post-treatment includes: after ultrasonic treatment is completed, take out the fiber material and wash it 3-5 times with deionized water and absolute ethanol, then transfer the fiber material to a vacuum drying oven at a temperature of 60-80 °C and vacuum dry it to constant weight to obtain a composite porous fiber blank.

[0023] Further, in step B2, the dosage ratio of the composite porous fiber blank, 4-trimethoxysilylbutyric acid, absolute ethanol and deionized water is 8-10 g: 1-2 g: 30-40 mL: 10-12 mL. The post-treatment includes: take out after the reaction is completed, wash the fiber material 3-5 times with deionized water and absolute ethanol, then transfer the fiber material to a vacuum drying oven at a temperature of 60-80 °C and vacuum dry it to constant weight to obtain the composite porous fiber.

[0024] Further, the preparation method of the composite fiber includes the following steps:

[0025] C1. Add aluminum isopropoxide, methyl orthosilicate and deionized water into a reaction kettle. After stirring at room temperature for 10-15 min, add an auxiliary agent to the reaction kettle to obtain an outer shell liquid.

[0026] C2. Load the inner core liquid and the outer shell liquid into two syringes connected to the inner and outer needles of a coaxial spinneret respectively, and prepare the composite fiber by electrospinning.

[0027] The principle of preparing the composite fiber is as follows: under the catalysis of acetic acid, aluminum isopropoxide, methyl orthosilicate and silica sol undergo hydrolysis to produce a gel structure, obtain the outer shell liquid, and obtain the composite fiber with a double-layer structure by electrospinning.

[0028] Further, in step C1, the dosage ratio of the aluminum isopropoxide, methyl orthosilicate, deionized water and the auxiliary agent is 12-15 g: 6-8 g: 40-50 mL: 18-26 g. The auxiliary agent is obtained by mixing silica sol, acetic acid, polyvinylpyrrolidone and conductive carbon black according to the dosage ratio of 12-16 g: 2-3 g: 1-2 g: 3-5 g.

[0029] Further, in step C2, the electrospinning parameters are as follows: the flow rate of the inner core liquid is 5-6 mL / h, the flow rate of the outer shell liquid is 7-8 mL / h, set the voltage of the electrospinning machine to 21-25 kV, and set the spinning distance to 20-24 cm.

[0030] Further, the preparation method of the inner core liquid includes the following steps:

[0031] D1. Hydroxy silicone oil, N,N-dimethylformamide and dibutyltin dilaurate are added to a reaction kettle. After purging with nitrogen, isophorone diisocyanate solution is added to the reaction kettle. The temperature of the reaction kettle is raised to 50 - 60 °C, and the reaction is carried out under insulation for 1 - 2 h. After post-treatment, modified polyurethane is obtained.

[0032] The reaction equation for preparing the modified polyurethane is:

[0033]

[0034] In the formula: .

[0035] The reaction principle for preparing the modified polyurethane is: Under the promotion of dibutyltin dilaurate and heating, the hydroxyl groups at the ends of the hydroxy silicone oil react with the isocyanate groups on the isophorone diisocyanate, and finally the modified polyurethane is prepared.

[0036] D2. The modified polyurethane, conductive carbon black, nano-silica, polyvinylpyrrolidone and N,N-dimethylformamide are added to a stirring kettle and stirred. After stirring evenly, the core liquid is obtained.

[0037] Further, in step D1, the dosage ratio of the hydroxy silicone oil, N,N-dimethylformamide, dibutyltin dilaurate and isophorone diisocyanate solution is 8 - 10 g : 30 - 36 mL : 1 - 2 g : 24 - 27 mL. Among them, the isophorone diisocyanate solution is obtained by mixing isophorone diisocyanate and N,N-dimethylformamide according to the dosage ratio of 1 - 2 g : 8 - 9 mL. The post-treatment includes: After the reaction is completed, when the temperature of the reaction kettle is reduced to room temperature, the reaction solution is transferred to a rotary evaporator. The temperature of the rotary evaporator is raised to 60 - 80 °C, and vacuum distillation is carried out until no liquid is collected, and then the modified polyurethane is obtained.

[0038] Further, in step D2, the dosage ratio of the modified polyurethane, conductive carbon black, nano-silica, polyvinylpyrrolidone and N,N-dimethylformamide is 12 - 15 g : 0.5 - 0.8 g : 0.5 - 0.8 g : 1 - 2 g : 70 - 80 mL.

[0039] The present invention also provides a method for preparing a fiber-reinforced recycled polyester material, which includes the following steps: The recycled polyester, heat stabilizer, lubricant, antioxidant and ultraviolet absorber are added to a twin-screw extruder, melt-extruded, and naturally cured to obtain the recycled polyester material.

[0040] Furthermore, the temperatures of the seven temperature zones of the twin-screw extruder from the feed inlet towards the discharge outlet are 270 °C, 275, 275 °C, 280 °C, 280 °C, 285 °C, and 290 °C in sequence. The main machine speed of the twin-screw extruder is 120 - 160 rpm, and the pressure is 80 - 120 bar.

[0041] The present invention has the following beneficial effects:

[0042] 1. In the present invention, the outer layer of silicon-aluminum composite of the composite fiber forms a dense inorganic network structure after high-temperature polymerization, directly enhancing the tensile resistance by strengthening the material rigidity; while the inner layer of modified polyurethane contains flexible silicone segments, which disperse the tensile stress through the ductility of the molecular chain to avoid local fracture; in the depolymerization and regeneration stage, the three-dimensional network of the porous fiber serves as a slow-release carrier for supercritical fluid, promoting the uniform depolymerization of waste polyester, reducing molecular chain defects, and making the molecular weight distribution of the recycled polyester more uniform; during the high-temperature polymerization process, the small molecules generated by depolymerization undergo a chemical cross-linking reaction with the carboxyl groups on the fiber surface to form a strong intermolecular bonding network, which not only enhances the binding force between molecular chains but also inhibits the generation of local weak points by evenly dispersing the tensile stress. This synergistic mechanism from rigidity enhancement, molecular cross-linking to microstructure optimization significantly improves the tensile resistance of the material.

[0043] 2. The outer layer of organosilicon-aluminum composite of the composite fiber prepared by the present invention forms a dense inorganic structure on the material surface, directly enhancing the wear resistance by increasing the surface hardness and scratch resistance; while the inner layer of modified polyurethane contains flexible silicone segments, which absorb impact energy through the ductility of the molecular segments to relieve external stress concentration, thereby improving the impact resistance; in the depolymerization and regeneration stage, the three-dimensional network structure of the porous fiber serves as a slow-release carrier for supercritical fluid, promoting the uniform depolymerization of waste polyester, reducing molecular chain defects, and making the molecular weight distribution of the recycled polyester more uniform. During the high-temperature polymerization process, the small molecules generated by depolymerization undergo a chemical cross-linking reaction with the carboxyl groups on the fiber surface to form a strong intermolecular bonding network, which not only improves the overall strength of the material but also inhibits crack propagation through the stress dispersion effect. This synergistic mechanism from surface strengthening, internal toughening to molecular cross-linking comprehensively improves the wear resistance and impact resistance of the material.

[0044] 3. In the present invention, firstly, a dense silicon-aluminum oxide protective layer is formed during the high-temperature polymerization of the outer layer of organosilicon-aluminum composite of the composite porous fiber, thereby effectively isolating oxygen and blocking the transfer of heat to the interior of the material. Secondly, the modified polyurethane in the inner layer contains organosilicon segments, which will release silicon-containing gases during combustion, thereby diluting the concentration of combustible gases and interfering with the combustion chain reaction. At the same time, the porous structure of the fiber forms a cross-linked network during ultrasonic treatment and hydrolysis, enhancing the mechanical strength of the carbon layer and preventing the carbon layer from cracking during combustion, which may lead to secondary combustion. Moreover, during the depolymerization and regeneration stage, the carboxyl groups on the surface of the composite fiber chemically react with small molecules generated by the depolymerization of waste polyester to form intermolecular chemical cross-links, which not only improves the thermal stability of the material but also promotes the rapid carbonization of polyester molecules during combustion, reducing the generation of combustible volatiles. Its porous network serves as a slow-release carrier for supercritical fluids, promoting the uniform dispersion of fluids, thereby improving the depolymerization efficiency of waste polyester. The entire process significantly improves the flame retardancy of the material through multiple mechanisms of physical barrier, gas-phase flame retardancy, catalytic carbonization, and structural enhancement. Detailed implementation mode

[0045] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0046] The hydroxy silicone oil used in the present invention is purchased from Zhejiang Zhenghe Silicon Materials Co., Ltd., with the product number 207-35;

[0047] The oxidized polyethylene wax used in the present invention is purchased from Jiaxing Zhongcheng Environmental Protection Technology Co., Ltd., with the product number ZC316AA;

[0048] The polyvinylpyrrolidone used in the present invention is purchased from Qingdao Chenxi New Energy Co., Ltd., with the product number M050092-250g;

[0049] The sources of the waste polyester used in the present invention are: products with defects during the production process of Anhui Guanhong Plastics Co., Ltd. and recycled waste polyester materials;

[0050] The conductive carbon black used in the present invention is purchased from Guangdong Wengjiang Chemical Reagent Co., Ltd., with the product number PA951233-500g; the silica sol used in the present invention is purchased from Shijiazhuang Shuanglian Chemical Industry Co., Ltd.

[0051] Example 1

[0052] This example is used to provide a preparation method for the inner core liquid for preparing fiber-reinforced recycled polyester materials, including the following steps:

[0053] Step Ⅰ: Prepare modified polyurethane

[0054] Weigh: 30.0 g of isophorone diisocyanate and 240.0 mL of N,N-dimethylformamide are mixed to obtain an isophorone diisocyanate solution;

[0055] Weigh: 80.0 g of hydroxy silicone oil, 300.0 mL of N,N-dimethylformamide and 10.0 g of dibutyltin dilaurate are added to a reaction kettle. After purging with nitrogen, 240.0 mL of the isophorone diisocyanate solution is added to the reaction kettle. The temperature of the reaction kettle is raised to 50 °C and kept for 1 h. After the reaction is completed, when the temperature of the reaction kettle drops to room temperature, the reaction solution is transferred to a rotary evaporator. The temperature of the rotary evaporator is raised to 60 °C and vacuum distilled until no liquid is collected, then the modified polyurethane is obtained.

[0056] Step Ⅱ: Prepare the inner core liquid

[0057] Weigh: 96.0 g of modified polyurethane, 4.0 g of conductive carbon black, 4.0 g of nano-silica, 8.0 g of polyvinylpyrrolidone and 560.0 mL of N,N-dimethylformamide are added to a stirring kettle and stirred. After stirring evenly, the inner core liquid is obtained.

[0058] Example 2

[0059] This example is used to provide a method for preparing an inner core liquid for preparing a fiber-reinforced recycled polyester material, including the following steps:

[0060] Step Ⅰ: Prepare modified polyurethane

[0061] Weigh: 60.0 g of isophorone diisocyanate and 270.0 mL of N,N-dimethylformamide are mixed to obtain an isophorone diisocyanate solution;

[0062] Weigh: 100.0 g of hydroxy silicone oil, 360.0 mL of N,N-dimethylformamide and 20.0 g of dibutyltin dilaurate are added to a reaction kettle. After purging with nitrogen, 270.0 mL of the isophorone diisocyanate solution is added to the reaction kettle. The temperature of the reaction kettle is raised to 60 °C and kept for 2 h. After the reaction is completed, when the temperature of the reaction kettle drops to room temperature, the reaction solution is transferred to a rotary evaporator. The temperature of the rotary evaporator is raised to 80 °C and vacuum distilled until no liquid is collected, then the modified polyurethane is obtained.

[0063] Step Ⅱ: Prepare the inner core liquid

[0064] Weigh: 150.0 g of modified polyurethane, 8.0 g of conductive carbon black, 8.0 g of nano-silica, 20.0 g of polyvinylpyrrolidone and 800.0 mL of N,N-dimethylformamide are added to a stirring kettle and stirred. After stirring evenly, the inner core liquid is obtained.

[0065] Example 3

[0066] This example is used to provide a preparation method of a core liquid for preparing a fiber-reinforced recycled polyester material, including the following steps:

[0067] Step Ⅰ: Prepare modified polyurethane

[0068] Weigh: 48.0 g of isophorone diisocyanate and 270.0 mL of N,N-dimethylformamide are mixed to obtain an isophorone diisocyanate solution;

[0069] Weigh: 90.0 g of hydroxy silicone oil, 320.0 mL of N,N-dimethylformamide and 16.0 g of dibutyltin dilaurate are added to a reaction kettle. After introducing nitrogen protection, 270.0 mL of the isophorone diisocyanate solution is added to the reaction kettle. The temperature of the reaction kettle is raised to 60 °C, and the reaction is carried out under insulation for 2 h. After the reaction is completed, when the temperature of the reaction kettle is lowered to room temperature, the reaction solution is transferred to a rotary evaporator. The temperature of the rotary evaporator is raised to 70 °C, and the pressure is reduced and distilled until no liquid is collected, and then modified polyurethane is obtained.

[0070] Step Ⅱ: Prepare the core liquid

[0071] Weigh: 135.0 g of modified polyurethane, 6.4 g of conductive carbon black, 6.4 g of nano-silica, 16.0 g of polyvinylpyrrolidone and 720.0 mL of N,N-dimethylformamide are added to a stirring kettle and stirred. After stirring evenly, the core liquid is obtained.

[0072] Example 4

[0073] This example is used to provide a preparation method of a composite porous fiber for preparing a fiber-reinforced recycled polyester material, including the following steps:

[0074] Step ①: Prepare the shell liquid

[0075] Weigh: 120.0 g of silica sol, 20.0 g of acetic acid, 10.0 g of polyvinylpyrrolidone and 30.0 g of conductive carbon black are mixed according to the dosage ratio to obtain an auxiliary agent;

[0076] Weigh: 150.0 g of aluminum isopropoxide, 60.0 g of methyl orthosilicate and 400.0 mL of deionized water are added to a reaction kettle. After stirring at room temperature for 10 min, 180.0 g of the auxiliary agent is added to the reaction kettle to obtain the shell liquid.

[0077] Step ②: Prepare the composite fiber

[0078] The core liquid and the shell liquid prepared in Example 1 were respectively filled into two syringes connected to the inner and outer needles of a coaxial spinneret. The flow rate of the core liquid was 5 mL / h, and the flow rate of the shell liquid was 7 mL / h. The voltage of the electrospinning machine was set at 21 kV, and the spinning distance was set at 20 cm to prepare composite fibers.

[0079] Step ③: Prepare a composite porous fiber preform

[0080] Weigh: 100.0 g of composite fibers and 1000.0 mL of deionized water were added to an ultrasonic device. After the temperature of the ultrasonic device was raised to 40 °C, the frequency was 20 kHz, and after heat preservation and ultrasonic treatment for 10 h, after the ultrasonic treatment was completed, the fiber material was taken out and washed 3 times with deionized water and absolute ethanol, and then the fiber material was transferred to a vacuum drying oven at 60 °C and vacuum dried to constant weight to obtain a composite porous fiber preform.

[0081] Step ④: Prepare composite porous fibers

[0082] Weigh: 80.0 g of composite porous fiber preform, 10.0 g of 4-trimethoxysilylbutyric acid, 300.0 mL of absolute ethanol and 100.0 mL of deionized water were added to a reaction kettle. After the temperature of the reaction kettle was raised to 40 °C, the pH of the reaction system was adjusted to 8 with a saturated sodium hydroxide aqueous solution, and after heat preservation and reaction for 1 h, after the reaction was completed, the fiber material was taken out and washed 3 times with deionized water and absolute ethanol, and then the fiber material was transferred to a vacuum drying oven at 60 °C and vacuum dried to constant weight to obtain composite porous fibers.

[0083] Example 5

[0084] This example is used to provide a preparation method of composite porous fibers for preparing a fiber-reinforced regenerated polyester material, including the following steps:

[0085] Step ①: Prepare the shell liquid

[0086] Weigh: 160.0 g of silica sol, 30.0 g of acetic acid, 20.0 g of polyvinylpyrrolidone and 50.0 g of conductive carbon black were mixed according to the dosage ratio to obtain an auxiliary agent;

[0087] Weigh: 150.0 g of aluminum isopropoxide, 80.0 g of methyl orthosilicate and 500.0 mL of deionized water were added to a reaction kettle. After stirring at room temperature for 15 min, 260.0 g of the auxiliary agent was added to the reaction kettle to obtain the shell liquid.

[0088] Step ②: Prepare composite fibers

[0089] The core liquid and the shell liquid prepared in Example 2 were respectively filled into two syringes connected to the inner and outer needles of a coaxial spinneret. The flow rate of the core liquid was 6 mL / h, and the flow rate of the shell liquid was 8 mL / h. The voltage of the electrospinning machine was set to 25 kV, and the spinning distance was set to 24 cm to obtain composite fibers.

[0090] Step ③: Prepare a composite porous fiber preform

[0091] Weigh: 100.0 g of composite fibers and 1000.0 mL of deionized water were added to an ultrasonic device. After the temperature of the ultrasonic device was raised to 40 °C, the frequency was 40 kHz, and after heat preservation and ultrasonic treatment for 12 h, after the ultrasonic treatment was completed, the fiber material was taken out and washed 5 times with deionized water and absolute ethanol, and then the fiber material was transferred to a vacuum drying oven at 80 °C and vacuum dried to constant weight to obtain a composite porous fiber preform.

[0092] Step ④: Prepare composite porous fibers

[0093] Weigh: 100.0 g of composite porous fiber preform, 20.0 g of 4-trimethoxysilylbutyric acid, 400.0 mL of absolute ethanol, and 120.0 mL of deionized water were added to a reaction kettle. After the temperature of the reaction kettle was raised to 60 °C, the pH of the reaction system was adjusted to 10 with a saturated sodium hydroxide aqueous solution, and after heat preservation and reaction for 2 h, after the reaction was completed, the fiber material was taken out and washed 5 times with deionized water and absolute ethanol, and then the fiber material was transferred to a vacuum drying oven at 80 °C and vacuum dried to constant weight to obtain composite porous fibers.

[0094] Example 6

[0095] This example is used to provide a preparation method of composite porous fibers for preparing a fiber-reinforced regenerated polyester material, including the following steps:

[0096] Step ①: Prepare the shell liquid

[0097] Weigh: 150.0 g of silica sol, 24.0 g of acetic acid, 16.0 g of polyvinylpyrrolidone, and 40.0 g of conductive carbon black were mixed according to the dosage ratio to obtain an auxiliary agent;

[0098] Weigh: 135.0 g of aluminum isopropoxide, 72.0 g of methyl orthosilicate, and 480.0 mL of deionized water were added to a reaction kettle. After stirring at room temperature for 12 min, 230.0 g of the auxiliary agent was added to the reaction kettle to obtain the shell liquid.

[0099] Step ②: Prepare composite fibers

[0100] The inner core liquid and the outer shell liquid prepared in Example 3 were respectively filled into two syringes connected to the inner and outer needles of a coaxial spinneret. The flow rate of the inner core liquid was 6 mL / h, and the flow rate of the outer shell liquid was 7 mL / h. The voltage of the electrospinning machine was set to 24 kV, and the spinning distance was set to 21 cm to prepare composite fibers.

[0101] Step ③: Prepare a composite porous fiber preform

[0102] Weigh: 100.0 g of composite fibers and 1000.0 mL of deionized water were added to an ultrasonic device. After the temperature of the ultrasonic device was raised to 40 °C, the frequency was 30 kHz, and after heat preservation and ultrasonic treatment for 12 h, after the ultrasonic treatment was completed, the fiber material was taken out and washed 4 times with deionized water and absolute ethanol, and then the fiber material was transferred to a vacuum drying oven at 70 °C and vacuum dried to constant weight to obtain a composite porous fiber preform.

[0103] Step ④: Prepare composite porous fibers

[0104] Weigh: 100.0 g of composite porous fiber preform, 16.0 g of 4-trimethoxysilylbutyric acid, 360.0 mL of absolute ethanol and 100.0 mL of deionized water were added to a reaction kettle. After the temperature of the reaction kettle was raised to 50 °C, the pH of the reaction system was adjusted to 9 with a saturated sodium hydroxide aqueous solution, and the reaction was carried out under heat preservation for 2 h. After the reaction was completed, the fiber material was taken out and washed 4 times with deionized water and absolute ethanol, and then the fiber material was transferred to a vacuum drying oven at 70 °C and vacuum dried to constant weight to obtain composite porous fibers.

[0105] Example 7

[0106] This example is used to provide a preparation method of a fiber-reinforced recycled polyester material, including the following steps:

[0107] Step 1: Prepare a depolymerization mixture

[0108] Weigh: After 200.0 g of waste polyester was heated to melt, the melt first passed through a filter screen Ⅰ with a particle size of 30 μm under a pressure of 1 MPa, and then passed through a filter screen Ⅱ with a particle size of 8 μm under a pressure of 2 MPa. After the filtration was completed, it was naturally solidified to obtain pretreated waste polyester;

[0109] Weigh: 160 g of pretreated waste polyester and 40.0 g of the composite porous fibers prepared in Example 4 were added to a high-pressure reactor. The high-pressure reactor was placed in a salt bath furnace. After purging the air in the high-pressure reactor with carbon dioxide gas, 20 MPa of carbon dioxide gas was introduced into the high-pressure reactor using a pressurizing device. The temperature of the salt bath furnace rose to 120 °C. During the heating process, the valve was used for deflation and pressure relief to control the pressure in the reactor to be less than 24 MPa. The reaction was carried out under insulation for 4 h. After the reaction was completed, when the pressure and temperature in the high-pressure reactor dropped to room temperature and pressure, the carbon dioxide gas was discharged to obtain a depolymerization mixture.

[0110] Step 2: Prepare recycled polyester

[0111] Weigh: 120.0 g of the depolymerization mixture, 10.0 g of terephthalic acid, 6.0 g of germanium dioxide, and 400.0 mL of dimethyl sulfoxide were added to a high-pressure reactor. The temperature of the high-pressure reactor was raised to 260 °C, and the pressure was controlled at 300 KPa. The reaction was carried out at a constant temperature and pressure for 2 h. After the reaction was completed, when the temperature of the reactor dropped to room temperature, the reaction solution was transferred to a rotary evaporator. The temperature of the rotary evaporator was raised to 60 °C, and vacuum distillation was carried out until no liquid was collected, and recycled polyester was obtained.

[0112] Step 3: Prepare recycled polyester material

[0113] Weigh by weight: 80 parts of recycled polyester, 3 parts of calcium stearate, 6 parts of polyethylene oxide wax, 3 parts of tris(2,4-di-tert-butylphenyl) phosphate, and 3 parts of 2-hydroxy-4-octyloxybenzophenone were added to a twin-screw extruder. The temperatures of the seven temperature zones of the twin-screw extruder from the feed inlet to the discharge outlet were 270 °C, 275, 275 °C, 280 °C, 280 °C, 285 °C, and 290 °C in sequence. The main motor speed of the twin-screw extruder was 120 rpm, and the pressure was 80 bar. After melt extrusion and natural curing, a recycled polyester material was obtained.

[0114] Example 8

[0115] This example is used to provide a method for preparing a fiber-reinforced recycled polyester material, including the following steps:

[0116] Step 1: Prepare a depolymerization mixture

[0117] Weigh: 200.0 g of waste polyester was heated to melting. The melt first passed through a filter screen I with a particle size of 10 μm under a pressure of 2 MPa, and then passed through a filter screen II with a particle size of 5 μm under a pressure of 4 MPa. After the filtration was completed, it was naturally cured to obtain pretreated waste polyester;

[0118] Weigh: 180.0 g of pretreated waste polyester and 30.0 g of the composite porous fiber prepared in Example 5 were added to a high-pressure reactor. The high-pressure reactor was placed in a salt bath furnace. After purging the air in the high-pressure reactor with carbon dioxide gas, 24 MPa of carbon dioxide gas was introduced into the high-pressure reactor using a pressurizing device. The temperature of the salt bath furnace rose to 160 °C. During the heating process, the valve was used to release gas and relieve pressure to control the pressure in the reactor to be less than 24 MPa. The reaction was carried out under insulation for 6 h. After the reaction was completed, when the temperature and pressure in the high-pressure reactor dropped to room temperature and pressure, the carbon dioxide gas was discharged to obtain a depolymerization mixture.

[0119] Step Two: Prepare regenerated polyester

[0120] Weigh: 160.0 g of the depolymerization mixture, 20.0 g of terephthalic acid, 8.0 g of germanium dioxide and 600.0 mL of dimethyl sulfoxide were added to a high-pressure reactor. The temperature of the high-pressure reactor was raised to 280 °C, and the pressure was controlled at 500 KPa. The reaction was carried out at a constant temperature and pressure for 4 h. After the reaction was completed, when the temperature of the reactor dropped to room temperature, the reaction solution was transferred to a rotary evaporator. The temperature of the rotary evaporator was raised to 80 °C, and vacuum distillation was carried out until no liquid was collected, and then regenerated polyester was obtained.

[0121] Step Three: Prepare regenerated polyester material

[0122] Weigh by weight: 100 parts of regenerated polyester, 5 parts of calcium stearate, 8 parts of polyethylene oxide wax, 5 parts of tris(2,4-di-tert-butylphenyl) phosphate and 5 parts of 2-hydroxy-4-octyloxybenzophenone were added to a twin-screw extruder. The temperatures of the seven temperature zones of the twin-screw extruder from the feed inlet to the discharge outlet were 270 °C, 275, 275 °C, 280 °C, 280 °C, 285 °C, 290 °C in sequence. The main machine speed of the twin-screw extruder was 160 rpm, and the pressure was 120 bar. After melting and extrusion and natural curing, a regenerated polyester material was obtained.

[0123] Example 9

[0124] This example is used to provide a preparation method of a fiber-reinforced regenerated polyester material, including the following steps:

[0125] Step One: Prepare depolymerization mixture

[0126] Weigh: 200.0 g of waste polyester was heated to melting, and the melt first passed through a filter screen I with a particle size of 20 μm under a pressure of 2 MPa, and then passed through a filter screen II with a particle size of 6 μm under a pressure of 3 MPa. After the filtration was completed, it was naturally cured to obtain pretreated waste polyester;

[0127] Weigh: 160.0 g of pretreated waste polyester and 24.0 g of the composite porous fiber prepared in Example 6 were added to a high-pressure reactor. The high-pressure reactor was placed in a salt bath furnace. After purging the air in the high-pressure reactor with carbon dioxide gas, 21 MPa of carbon dioxide gas was introduced into the high-pressure reactor using a pressurizing device. The temperature of the salt bath furnace rose to 150 °C. During the heating process, a valve was used to release gas and relieve pressure to control the pressure in the reactor to be less than 24 MPa. The reaction was carried out under insulation for 5 h. After the reaction was completed, when the temperature and pressure in the high-pressure reactor dropped to room temperature, the carbon dioxide gas was discharged to obtain a depolymerization mixture.

[0128] Step 2: Preparation of recycled polyester

[0129] Weigh: 150.0 g of the depolymerization mixture, 16.0 g of terephthalic acid, 7.0 g of germanium dioxide, and 500.0 mL of dimethyl sulfoxide were added to a high-pressure reactor. The temperature of the high-pressure reactor was raised to 280 °C, and the pressure was controlled at 400 KPa. The reaction was carried out at a constant temperature and pressure for 3 h. After the reaction was completed, when the temperature of the reactor dropped to room temperature, the reaction solution was transferred to a rotary evaporator. The temperature of the rotary evaporator was raised to 70 °C, and vacuum distillation was carried out until no liquid was collected, obtaining recycled polyester.

[0130] Step 3: Preparation of recycled polyester material

[0131] Weigh by weight: 96 parts of recycled polyester, 4 parts of calcium stearate, 7 parts of polyethylene oxide wax, 4 parts of tris(2,4-di-tert-butylphenyl) phosphate, and 4 parts of 2-hydroxy-4-octyloxybenzophenone were added to a twin-screw extruder. The temperatures of the seven temperature zones of the twin-screw extruder from the feed inlet to the discharge outlet were 270 °C, 275, 275 °C, 280 °C, 280 °C, 285 °C, and 290 °C in sequence. The main motor speed of the twin-screw extruder was 150 rpm, and the pressure was 100 bar. After melting and extrusion and natural curing, a recycled polyester material was obtained.

[0132] Comparative Example 1

[0133] The difference between this comparative example and Example 9 is that in the process of preparing the recycled polyester used in Step 3 and in the process of preparing the composite porous fiber used, Step ④ was cancelled.

[0134] Comparative Example 2

[0135] The difference between this comparative example and Example 9 is that in Step ② of the process of preparing the recycled polyester used in Step 3, the inner core liquid was replaced with an equal amount of the outer shell liquid.

[0136] Comparative Example 3

[0137] The difference between this comparative example and Example 9 is that the use of the composite porous fiber was cancelled in Step 1.

[0138] Performance test:

[0139] The limiting oxygen index of the recycled polyester materials prepared in Examples 7-9 and Comparative Examples 1-3 was tested with reference to the standard GB / T 26526-2011 Plastics - Determination of burning behaviour by oxygen index - Part 2: Ambient temperature test;

[0140] The tensile strength and elongation at break of the recycled polyester materials prepared in Examples 7-9 and Comparative Examples 1-3 were detected with reference to the standard GB / T 1040-2018 Plastics - Determination of tensile properties;

[0141] The volume abrasion of the recycled polyester materials prepared in Examples 7-9 and Comparative Examples 1-3 was tested with reference to the standard GB / T 9867-2008 Rubber, vulcanized or thermoplastic - Determination of abrasion resistance (rotary drum abrader method);

[0142] The Izod impact strength of the recycled polyester materials prepared in Examples 7-9 and Comparative Examples 1-3 was determined with reference to the standard GB / T 1843-2008 Plastics - Determination of Izod impact strength. The specific data are shown in Table 1.

[0143] Table 1 - Performance test data table of each sample

[0144]

[0145] Data analysis:

[0146] By comparing and analyzing the data in Table 1, it can be found that the limiting oxygen index of the recycled polyester material prepared by the present invention is 36.1%, the tensile strength is 75.1 MPa, the elongation at break is 483%, the volume abrasion is 15 mm 3 while the Izod impact strength is 70 kJ·m -2 , and all the data are better than those of the comparative examples, indicating that:

[0147] In the present invention, firstly, a dense silicon-aluminum oxide protective layer is formed during the high-temperature polymerization of the outer layer of organosilicon-aluminum composite of the composite porous fiber, thus effectively isolating oxygen and blocking the transfer of heat to the interior of the material. Secondly, the modified polyurethane in the inner layer contains organosilicon segments, which will release silicon-containing gases during combustion, thereby diluting the concentration of combustible gases and interfering with the combustion chain reaction. At the same time, the porous structure of the fiber forms a cross-linked network during ultrasonic treatment and hydrolysis, enhancing the mechanical strength of the carbon layer and preventing the carbon layer from cracking during combustion, which may lead to secondary combustion. Moreover, during the depolymerization and regeneration stage, the carboxyl groups on the surface of the composite fiber chemically react with the small molecules generated by the depolymerization of waste polyester to form intermolecular chemical cross-links, which not only improves the thermal stability of the material but also promotes the rapid carbonization of polyester molecules during combustion, reducing the generation of combustible volatiles. Its porous network serves as a slow-release carrier for supercritical fluids, promoting the uniform dispersion of fluids, thereby improving the depolymerization efficiency of waste polyester. The entire process significantly improves the flame retardancy of the material through multiple mechanisms including physical barrier, gas-phase flame retardancy, catalytic carbonization, and structural enhancement;

[0148] In the present invention, the outer layer of organosilicon-aluminum composite of the prepared composite fiber forms a dense inorganic structure on the material surface, directly enhancing the wear resistance by improving the surface hardness and scratch resistance; while the modified polyurethane in the inner layer contains flexible organosilicon segments, which absorb impact energy through the ductility of the molecular segments, alleviating the external stress concentration, thereby improving the impact resistance; during the depolymerization and regeneration stage, the three-dimensional network structure of the porous fiber serves as a slow-release carrier for supercritical fluids, promoting the uniform depolymerization of waste polyester, reducing molecular chain defects, and making the molecular weight distribution of the recycled polyester more uniform. During the high-temperature polymerization process, the small molecules generated by depolymerization chemically react with the carboxyl groups on the fiber surface to form a strong intermolecular bonding network, which not only improves the overall strength of the material but also inhibits crack propagation through the stress dispersion effect. This synergistic mechanism from surface strengthening, internal toughening to molecular cross-linking comprehensively improves the wear resistance and impact resistance of the material;

[0149] In addition, the outer layer of silicon-aluminum composite of the composite fiber forms a dense inorganic network structure after high-temperature polymerization, directly enhancing the tensile resistance by increasing the material rigidity; while the modified polyurethane in the inner layer contains flexible organosilicon segments, which disperse the tensile stress through the ductility of the molecular chain, avoiding local fracture; during the depolymerization and regeneration stage, the three-dimensional network of the porous fiber serves as a slow-release carrier for supercritical fluids, promoting the uniform depolymerization of waste polyester, reducing molecular chain defects, and making the molecular weight distribution of the recycled polyester more uniform; during the high-temperature polymerization process, the small molecules generated by depolymerization chemically react with the carboxyl groups on the fiber surface to form a strong intermolecular bonding network, which not only enhances the bonding force between molecular chains but also inhibits the generation of local weak points through the uniform dispersion of tensile stress. This synergistic mechanism from rigidity enhancement, molecular cross-linking to microstructure optimization significantly improves the tensile resistance of the material;

[0150] It is described that the present invention prepares a shell liquid mainly composed of an organosilicon-aluminum composite and a core liquid mainly composed of a modified polyurethane containing an organosilicon segment. A composite fiber with a silicon-aluminum composite structure as the outer layer and a modified polyurethane as the inner layer is prepared by electrospinning. Through ultrasonic treatment in an aqueous medium, a porous composite structure is formed. Under alkaline conditions, the organosilicon structure in the outer layer and the silicon hydroxyl structure in the inner layer are hydrolyzed, making the structure combination tight. And through modification with 4-trimethoxysilylbutyric acid, carboxyl groups are introduced on the surface of the fiber structure, thus preparing a composite porous fiber. The composite porous fiber and the pretreated waste polyester prepared by melt filtration are depolymerized together. The porous structure of the composite porous fiber serves as a slow-release carrier for supercritical fluids, thereby improving the depolymerization effect to obtain a depolymerized mixed liquid. During the high-temperature polymerization of the depolymerized mixed liquid, the small molecular structures generated by depolymerization react with the carboxyl group structures on the composite porous fiber, and the outer layer organosilicon-aluminum composite forms a dense inorganic structure on the material surface. Finally, the composite porous fiber modifies the structure of the prepared recycled polyester, and the recycled polyester and auxiliary materials are mixed and melt-extruded to prepare a recycled polyester material.

[0151] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to only the specific implementation manners. Obviously, according to the content of this specification, many modifications and changes can be made. These embodiments are selected and specifically described in this specification to better explain the principle and practical application of the present invention, so that those skilled in the art in the relevant technical field can well understand and utilize the present invention. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A fiber-reinforced recycled polyester material, characterized in that: The raw material composition includes the following parts by weight: 80-100 parts of recycled polyester, 3-5 parts of heat stabilizer, 6-8 parts of lubricant, 3-5 parts of antioxidant and 3-5 parts of ultraviolet absorber; The preparation method of the recycled polyester comprises the following steps: A1. Adding pre-treated waste polyester and composite porous fibers into a high-pressure reactor for depolymerization to obtain a depolymerization mixed solution; A2. Add the depolymerization mixture, terephthalic acid, germanium dioxide and dimethyl sulfoxide into a high-pressure reactor, increase the temperature of the high-pressure reactor to 260-280°C, control the pressure to 300-500KPa, react at constant temperature and pressure for 2-4h, and obtain recycled polyester through post-treatment.

2. The fiber-reinforced recycled polyester material according to claim 1, characterized in that: In step A1, the depolymerization operation selects a carbon dioxide supercritical depolymerization process, and the specific operation is: placing a high-pressure reactor in a salt bath furnace, using carbon dioxide gas to exhaust the air in the high-pressure reactor, using a pressurizing device to pass 20-24MPa carbon dioxide gas into the high-pressure reactor, the temperature of the salt bath furnace rises to 120-160°C, and a valve is used to vent and release pressure during the heating process to control the pressure in the reactor to be less than 24MPa. The reaction is kept warm for 4-6h. After the reaction is completed, the pressure in the high-pressure reactor is reduced to room temperature, and carbon dioxide gas is discharged to obtain a depolymerization mixed solution; in step A2, the amount ratio of the depolymerization mixed solution, terephthalic acid, germanium dioxide and dimethyl sulfoxide is 12-16g:1-2g:0.6-0.8g:40-60mL.

3. The fiber-reinforced recycled polyester material according to claim 1, characterized in that: The method for preparing the composite porous fiber comprises the following steps: B1. Add the composite fiber and deionized water into an ultrasonic device, raise the temperature of the ultrasonic device to 40°C, set the frequency to 20-40kHz, and perform ultrasonic treatment for 10-12h, and then obtain a composite porous fiber blank by post-treatment; B2. Add the composite porous fiber blank, 4-trimethoxysilylbutyric acid, anhydrous ethanol and deionized water into the reactor. After the temperature of the reactor is increased to 40-60°C, use saturated sodium hydroxide aqueous solution to adjust the pH of the reaction system to 8-10, keep the reaction warm for 1-2 hours, and post-treat to obtain the composite porous fiber.

4. The fiber-reinforced recycled polyester material according to claim 3, characterized in that: In step B1, the usage ratio of the composite fiber and deionized water is 1-2g:10mL; in step B2, the usage ratio of the composite porous fiber blank, 4-trimethoxysilylbutyric acid, anhydrous ethanol and deionized water is 8-10g:1-2g:30-40mL:10-12mL.

5. The fiber-reinforced recycled polyester material according to claim 3, characterized in that: The preparation method of the composite fiber comprises the following steps: C1. Aluminum isopropoxide, methyl orthosilicate and deionized water are added to a reaction kettle, stirred at room temperature for 10-15 minutes, and then an auxiliary agent is added to the reaction kettle to obtain a shell liquid; C2. The inner core liquid and the outer shell liquid are respectively loaded into two syringes connected to the inner and outer needles of the coaxial spinneret, and composite fibers are prepared by electrospinning.

6. The fiber-reinforced recycled polyester material according to claim 5, characterized in that: In step C1, the dosage ratio of aluminum isopropoxide, methyl orthosilicate, deionized water and auxiliary agent is 12-15g:6-8g:40-50mL:18-26g, and the auxiliary agent is obtained by mixing silica sol, acetic acid, polyvinyl pyrrolidone and conductive carbon black in a dosage ratio of 12-16g:2-3g:1-2g:3-5g.

7. The fiber-reinforced recycled polyester material according to claim 5, characterized in that: The preparation method of the inner core liquid comprises the following steps: D1. Add hydroxy silicone oil, N,N-dimethylformamide and dibutyltin dilaurate into a reactor, introduce nitrogen protection, add isophorone diisocyanate solution into the reactor, increase the temperature of the reactor to 50-60°C, keep the temperature for reaction for 1-2h, and post-treat to obtain modified polyurethane; D2. Add modified polyurethane, conductive carbon black, nano-silicon dioxide, polyvinyl pyrrolidone and N,N-dimethylformamide into a stirring tank and stir until the inner core liquid is obtained.

8. The fiber-reinforced recycled polyester material according to claim 7, characterized in that: In step D1, the amount ratio of hydroxy silicone oil, N,N-dimethylformamide, dibutyltin dilaurate and isophorone diisocyanate solution is 8-10g:30-36mL:1-2g:24-27mL, wherein the isophorone diisocyanate solution is obtained by mixing isophorone diisocyanate and N,N-dimethylformamide in an amount ratio of 1-2g:8-9mL; in step D2, the amount ratio of modified polyurethane, conductive carbon black, nano-silica, polyvinyl pyrrolidone and N,N-dimethylformamide is 12-15g:0.5-0.8g:0.5-0.8g:1-2g:70-80mL.

9. A method for preparing a fiber-reinforced recycled polyester material according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: adding recycled polyester, a heat stabilizer, a lubricant, an antioxidant and an ultraviolet absorber into a twin-screw extruder, melting and extruding, and naturally curing to obtain a recycled polyester material.

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