Wind power blade recovery method taking fiber reinforced anhydride cured epoxy resin as main body

Abstract

The invention relates to the field of waste fan blade recovery, in particular to a wind power blade recovery method with fiber reinforced anhydride cured epoxy resin as a main body. The degradation efficiency of the whole reaction is improved through the swelling reagent, a part of degradation products obtained through catalyst degradation can be added into new resin according to a certain proportion to be cured, the whole cost of the epoxy resin is effectively reduced, the catalyst can be recycled, and the efficiency is not affected. The reaction conditions in the whole recovery process are mild, high-value resources in the leaves are fully recycled, and waste of the resources is avoided. The degradation rate of the catalyst system is high and can reach 95% or above, and the effectiveness of the catalyst is still guaranteed after the catalyst is circulated for five times or above. The mechanical property of the acid anhydride cured epoxy resin obtained by adding the epoxy resin monomer recovered by degrading the waste wind turbine blade into the new monomer according to a certain proportion is not obviously influenced, and the performance requirement of the thermosetting acid anhydride cured epoxy resin is met.

Description

Technical Field

[0001] This invention relates to the field of waste wind turbine blade recycling, specifically to a method for recycling waste wind turbine blades using fiber-reinforced anhydride-cured epoxy resin as the main component. Background Technology

[0002] Fiber-reinforced composite materials are commonly used in the manufacture of wind turbine blades (WTB). Given the limited lifespan of wind turbine blades, an increasing number of them will be decommissioned over the next few decades. How to effectively recycle them to avoid environmental problems is a pressing issue. With the first wave of early commercial wind turbine installations nearing the end of their lifespan, blade disposal has become a significant factor influencing the future development of the wind power industry.

[0003] Currently, the capacity for recycling and reprocessing wind turbine blades is insufficient, and the recycling value cannot offset the costs. Every year, a large amount of wind turbine blade waste is landfilled or incinerated. However, landfilling pollutes the soil and occupies land, while incineration generates toxic gases, fly ash, and additional solid residues. Therefore, to prevent such disposal, an efficient, cost-effective recycling solution with minimal environmental impact is needed.

[0004] For the reuse of this type of waste, mechanical methods, pyrolysis methods, and catalytic recycling methods have been proposed. Mechanical methods often limit the application scenarios of recycled products; for pyrolysis, the properties of recycled carbon fiber and glass fiber are significantly affected by high temperatures; unlike the first two recycling methods which damage the fibers, many studies on catalytic recycling methods have shown that they can recover glass fiber and carbon fiber with higher efficiency. Furthermore, catalytic recycling can oxidize and degrade the waste resin matrix into recyclable small-molecule chemical raw materials, which also brings a high recycling efficiency advantage to catalytic recycling methods.

[0005] Existing recycling methods still have the following problems in production practice:

[0006] (1) Harsh reaction conditions: Some methods use supercritical fluids to degrade epoxy resins at 300℃ and 15MPa. The reaction conditions are relatively harsh and require specific reaction vessels, which poses a high safety risk and high energy consumption. At the same time, supercritical fluids need to be added to the reactor at equal time intervals under high temperature and high pressure, which is complicated and not conducive to large-scale production.

[0007] (2) Incomplete recovery of degradation products: Some research methods focus on the recovery of composite reinforcements such as glass fiber and carbon fiber, while research on the recovery of epoxy resin degradation products is relatively limited. However, in actual production, the economic value of resin degradation products is far higher than that of glass fiber. Therefore, neglecting the recovery of epoxy resin degradation products will waste a large amount of high-value resources, thereby reducing the efficiency of degradation and recovery and reducing the enthusiasm for production.

[0008] (3) Limited variety of blade resins: Some research methods mainly focus on fiber-reinforced amine-cured epoxy resin materials with relatively mature degradation methods, while there is less research on the recycling of fiber-reinforced anhydride-cured epoxy resin composites. In practical applications, anhydride-cured epoxy resins account for a considerable portion of blade applications. Summary of the Invention

[0009] To address the aforementioned technical problems, this invention provides a method for recycling wind turbine blades primarily composed of fiber-reinforced anhydride-cured epoxy resin, comprising the following steps:

[0010] (1) The waste wind turbine blades are mechanically crushed and sieved, and the blade particles under the sieve are retained; the waste wind turbine blades are mainly composed of fiber-reinforced anhydride-cured epoxy resin, including anhydride-cured carbon fiber reinforced material, anhydride-cured glass fiber reinforced material, or anhydride-cured glass-carbon hybrid fiber reinforced material.

[0011] (2) Place the leaf particles in a swelling reagent and pretreat them at 80-160℃ for 3-5 hours. The liquid-solid ratio of the leaf particles to the swelling reagent is 300-700 g / L.

[0012] (3) After filtering and washing the pretreated blade particles from the swelling reagent, add them to the degradation catalyst at a liquid-solid ratio of 1-5 g / mL to form a catalytic degradation system. Place the mixture in a reaction vessel and heat it at 130-180℃ for 7-16 h to fully degrade the blade material.

[0013] (4) After the reaction is complete, filter and separate the liquid. Thoroughly wash and dry the filtered solid to recover the fiber.

[0014] (5) Dissolve the filtrate obtained in step (4) in an excess solvent, extract and remove impurities by rotary evaporation, and distill to obtain a viscous degradation product;

[0015] (6) Mix the viscous degradation product obtained in step (5) with bisphenol A diglycidyl ether and anhydride curing agent in a certain proportion. The mass ratio of viscous degradation product, bisphenol A diglycidyl ether and anhydride curing agent is 1-30:100:50-120. Add a certain amount of curing accelerator. The amount of curing accelerator added is 1%-4% of the total mass. Curing yields thermosetting epoxy resin.

[0016] Furthermore, the sieve aperture in step (1) is 80 mesh.

[0017] Further, the swelling agent mentioned in step (2) is one or a mixture of several of ethanol, acetone, methanol, nitric acid, ethyl acetate or ethylene glycol.

[0018] Further, the degradation catalyst mentioned in step (3) is one of ethylene glycol, cerium nitrate, dodecylbenzenesulfonic acid, ethyl acetate or n-methyl-4-piperidinol.

[0019] Furthermore, the solvent mentioned in step (5) is one of ethanol, methanol or ethyl acetate.

[0020] Further, the anhydride curing agent mentioned in step (6) is one of methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, or maleic anhydride.

[0021] Furthermore, the curing accelerator mentioned in step (6) is dmp-30 accelerator.

[0022] Further, the curing in step (6) is performed by storing the product at 40-60℃, 100-120℃, and 140-155℃ for 1-2 hours, 2-3 hours, and 3-4 hours, respectively.

[0023] The degradation catalyst used in this invention for recovering fiber-reinforced anhydride-cured epoxy resin composites exhibits excellent stability, maintaining its performance unchanged after multiple cycles. It demonstrates strong catalytic degradation of the anhydride-cured resin, effectively decomposing it into high-value small-molecule resin monomers without damaging the monomer's structure. The catalyst does not react with other components in the leaf, facilitating the separation of degradation products. This catalyst can simultaneously carry monomers into the aqueous phase, significantly improving degradation efficiency. The non-degradable glass fibers and other components obtained after decomposition can be separated and used as fillers, while the resin degradation products can be reused as chemical products in resin curing.

[0024] The beneficial effects of this invention are:

[0025] This invention improves the overall degradation efficiency of the reaction by using a swelling agent. The degradation products obtained after degradation can be partially added to new resin for curing, effectively reducing the overall cost of epoxy resin. Furthermore, the catalyst can be repeatedly recycled without affecting efficiency. The entire recycling process operates under mild reaction conditions, ensuring full recovery and utilization of high-value resources from the leaves and avoiding resource waste. The catalyst system used in this invention has a high degradation rate, exceeding 95%, and its effectiveness is maintained even after more than five cycles.

[0026] In this invention, the epoxy resin monomers recovered by degrading waste wind turbine blades are added to new monomers in a certain proportion. The mechanical properties of the resulting anhydride-cured epoxy resin are not significantly affected, and the tensile strength is greater than 145 kgf / cm². 2 Flexural strength greater than 300 kgf / cm 2 With a hardness greater than 80 Shore-D, it meets the performance requirements of thermosetting anhydride-cured epoxy resin. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the overall process of the recycling method of the present invention.

[0028] Figure 2 These are discarded wind turbine blades used in the embodiments of this invention.

[0029] Figure 3 The glass fiber obtained after recycling in the embodiments of the present invention.

[0030] Figure 4 The tensile and bending specimens are made from the new anhydride-cured epoxy resin obtained by re-curing the resin degradation of the wind turbine blade in the embodiments of the present invention.

[0031] Figure 5 The Fourier transform infrared spectrum of the degradation products of wind turbine blades in an embodiment of the present invention is shown. Detailed Implementation

[0032] See Figure 1-5 As shown, the present invention will be further described in conjunction with embodiments.

[0033] In this invention, the formula for calculating the degradation rate of the organic component (i.e., the anhydride-cured epoxy resin) is expressed as follows:

[0034] η = m2 / rm1 × 100%;

[0035] Where: η—degradation rate of epoxy resin, %; m1—initial weight of waste wind turbine blade material, g; m2—mass of organic phase in the reaction product, g; r—percentage of organic component content in waste wind turbine blade material, 47%.

[0036] Examples 1 to 7 below mainly focus on experiments conducted on wind turbine blades made primarily of glass fiber reinforced polymer (GFRP) formed from anhydride-cured epoxy resin.

[0037] Example 1

[0038] This embodiment provides a method for recycling wind turbine blades mainly composed of fiber-reinforced anhydride-cured epoxy resin, the steps of which include:

[0039] (1) The waste wind turbine blades are mechanically crushed and screened, and the blade particles below the screen are retained;

[0040] (2) Place the leaf particles in anhydrous ethanol and add them together to the reaction vessel. Pre-treat at 90°C for 3 hours. The liquid-solid ratio of the leaf particles to the swelling reagent is 400 g / L.

[0041] (3) After filtering and washing the pretreated blade particles, add them to ethylene glycol at a liquid-solid ratio of 2 g / mL to form a catalytic degradation system. Place the mixture in a reaction vessel and heat it at 130°C for 8 hours to fully degrade the blade material.

[0042] (4) After the reaction is complete, filter and separate the liquid. Thoroughly wash and dry the filtered solid to recover the glass fiber.

[0043] (5) Dissolve the lower filtrate obtained in step (4) in a certain amount of anhydrous ethanol, extract and remove impurities by rotary evaporation, and after evaporating the solvent, obtain a viscous degradation product and calculate the organic matter degradation rate.

[0044] (6) The viscous degradation product obtained in step (5) is mixed with bisphenol A diglycidyl ether and methyltetrahydrophthalic anhydride at a mass ratio of 1:10:10; and a certain amount of dmp-30 accelerator is added, the amount of dmp-30 accelerator added is 2% of the total mass; and the thermosetting epoxy resin is obtained by storing it at 60℃, 120℃ and 140℃ for 1 hour, 2 hours and 4 hours respectively.

[0045] Example 2

[0046] This embodiment provides a method for recycling wind turbine blades mainly composed of fiber-reinforced anhydride-cured epoxy resin, the steps of which include:

[0047] (1) The waste wind turbine blades are mechanically crushed and screened, and the blade particles below the screen are retained;

[0048] (2) Place the leaf particles in anhydrous ethanol and add them together to the reaction vessel. Pre-treat at 160℃ for 4h. The liquid-solid ratio of the leaf particles to the swelling reagent is 400g / L.

[0049] (3) After filtering and cleaning the pretreated blade particles, add them to a 5% dodecylbenzenesulfonic acid solution at a liquid-to-solid ratio of 2 g / mL to form a catalytic degradation system. Place the mixture in a reaction vessel and heat it at 150°C for 12 h to fully degrade the blade material.

[0050] (4) After the reaction is complete, filter and separate the liquid. Thoroughly wash and dry the filtered solid to recover the glass fiber.

[0051] (5) Dissolve the lower filtrate obtained in step (4) in a certain amount of methanol, extract and remove impurities by rotary evaporation, and after evaporating the solvent, obtain a viscous degradation product and calculate the organic matter degradation rate.

[0052] (6) The viscous degradation product obtained in step (5) is mixed with bisphenol A diglycidyl ether and methyl hexahydrophthalic anhydride at a mass ratio of 2:10:9; and a certain amount of dmp-30 accelerator is added, the amount of dmp-30 accelerator added is 2% of the total mass; and the thermosetting epoxy resin is obtained by storing it at 60℃, 120℃ and 155℃ for 2 hours, 2 hours and 4 hours respectively.

[0053] Example 3

[0054] This embodiment provides a method for recycling wind turbine blades mainly composed of fiber-reinforced anhydride-cured epoxy resin, the steps of which include:

[0055] (1) The waste wind turbine blades are mechanically crushed and screened, and the blade particles below the screen are retained;

[0056] (2) Place the leaf particles in acetone and add them together to the reaction vessel. Pre-treat at 130°C for 3 hours. The liquid-solid ratio of the leaf particles to the swelling reagent is 400 g / L.

[0057] (3) After filtering and cleaning the pretreated blade particles, add them to a 30% cerium nitrate solution at a liquid-to-solid ratio of 2 g / mL to form a catalytic degradation system. Place the mixture in a reaction vessel and heat it at 140°C for 8 hours to fully degrade the blade material.

[0058] (4) After the reaction is complete, filter and separate the liquid. Thoroughly wash and dry the filtered solid to recover the glass fiber.

[0059] (5) Dissolve the lower filtrate obtained in step (4) in a certain amount of methanol, extract and remove impurities by rotary evaporation, and after evaporating the solvent, obtain a viscous degradation product and calculate the organic matter degradation rate.

[0060] (6) The viscous degradation product obtained in step (5) is mixed with bisphenol A diglycidyl ether and methyltetrahydrophthalic anhydride at a mass ratio of 1.5:10:6; and a certain amount of dmp-30 accelerator is added, the amount of dmp-30 accelerator added is 2% of the total mass; and the thermosetting epoxy resin is obtained by storing it at 40℃, 120℃ and 150℃ for 1 hour, 3 hours and 4 hours respectively.

[0061] Example 4

[0062] This embodiment provides a method for recycling wind turbine blades mainly composed of fiber-reinforced anhydride-cured epoxy resin, the steps of which include:

[0063] (1) The waste wind turbine blades are mechanically crushed and screened, and the blade particles below the screen are retained;

[0064] (2) Place the leaf particles in methanol and add them together to the reaction vessel. Pre-treat at 100°C for 5 hours. The liquid-solid ratio of the leaf particles to the swelling reagent is 400 g / L.

[0065] (3) After filtering and washing the pretreated blade particles, add them to n-methyl4-piperidinol at a liquid-solid ratio of 2 g / mL to form a catalytic degradation system. Put the mixture into a reaction vessel and heat it at 140℃ for 10 h to fully degrade the blade material.

[0066] (4) After the reaction is complete, filter and separate the liquid. Thoroughly wash and dry the filtered solid to recover the glass fiber.

[0067] (5) Dissolve the lower filtrate obtained in step (4) in a certain amount of ethyl acetate, extract and remove impurities by rotary evaporation, and after evaporating the solvent, obtain a viscous degradation product and calculate the organic degradation rate.

[0068] (6) The viscous degradation product obtained in step (5) is mixed with bisphenol A diglycidyl ether and methyltetrahydrophthalic anhydride at a mass ratio of 1:10:7; and a certain amount of dmp-30 accelerator is added, the amount of dmp-30 accelerator added is 2% of the total mass; and the thermosetting epoxy resin is obtained by storing it at 40℃, 120℃ and 150℃ for 1 hour, 3 hours and 4 hours respectively.

[0069] Example 5

[0070] This embodiment provides a method for recycling wind turbine blades mainly composed of fiber-reinforced anhydride-cured epoxy resin, the steps of which include:

[0071] (1) The waste wind turbine blades are mechanically crushed and screened, and the blade particles below the screen are retained;

[0072] (2) Place the leaf particles in nitric acid and add them together to the reaction vessel. Pre-treat at 80°C for 5 hours. The liquid-solid ratio of the leaf particles to the swelling reagent is 400 g / L.

[0073] (3) After filtering and cleaning the pretreated blade particles, add them to a 2% dodecylbenzenesulfonic acid solution at a liquid-to-solid ratio of 2 g / mL to form a catalytic degradation system. Place the mixture in a reaction vessel and heat it at 170°C for 15 h to fully degrade the blade material.

[0074] (4) After the reaction is complete, filter and separate the liquid. Thoroughly wash and dry the filtered solid to recover the glass fiber.

[0075] (5) Dissolve the lower filtrate obtained in step (4) in a certain amount of ethanol, extract and remove impurities by rotary evaporation, and after evaporating the solvent, obtain a viscous degradation product and calculate the organic matter degradation rate.

[0076] (6) The viscous degradation product obtained in step (5) is mixed with bisphenol A diglycidyl ether and methyltetrahydrophthalic anhydride at a mass ratio of 3:10:6; and a certain amount of dmp-30 accelerator is added, the amount of dmp-30 accelerator added is 2% of the total mass; and the thermosetting epoxy resin is obtained by storing it at 40℃, 100℃ and 150℃ for 1 hour, 2 hours and 4 hours respectively.

[0077] Example 6

[0078] This embodiment provides a method for recycling wind turbine blades mainly composed of fiber-reinforced anhydride-cured epoxy resin, the steps of which include:

[0079] (1) The waste wind turbine blades are mechanically crushed and screened, and the blade particles below the screen are retained;

[0080] (2) Place the leaf particles in ethyl acetate and add them together to the reaction vessel. Pre-treat at 160℃ for 4h. The liquid-solid ratio of the leaf particles to the swelling reagent is 400g / L.

[0081] (3) After filtering and cleaning the pretreated blade particles, add them to a 5% dodecylbenzenesulfonic acid solution at a liquid-to-solid ratio of 2 g / mL to form a catalytic degradation system. Place the mixture in a reaction vessel and heat it at 180°C for 8 hours to fully degrade the blade material.

[0082] (4) After the reaction is complete, filter and separate the liquid. Thoroughly wash and dry the filtered solid to recover the glass fiber.

[0083] (5) Dissolve the lower filtrate obtained in step (4) in a certain amount of ethanol, extract and remove impurities by rotary evaporation, and after evaporating the solvent, obtain a viscous degradation product and calculate the organic matter degradation rate.

[0084] (6) The viscous degradation product obtained in step (5) is mixed with bisphenol A diglycidyl ether and methyltetrahydrophthalic anhydride at a mass ratio of 2.5:10:7; and a certain amount of dmp-30 accelerator is added, the amount of dmp-30 accelerator added is 2% of the total mass; and the thermosetting epoxy resin is obtained by storing it at 40℃, 120℃ and 155℃ for 2 hours, 2 hours and 4 hours respectively.

[0085] Example 7

[0086] This embodiment provides a method for recycling wind turbine blades mainly composed of fiber-reinforced anhydride-cured epoxy resin, the steps of which include:

[0087] (1) The waste wind turbine blades are mechanically crushed and screened, and the blade particles below the screen are retained;

[0088] (2) Place the leaf particles in ethylene glycol and add them together to the reaction vessel. Pre-treat at 160°C for 4 hours. The liquid-solid ratio of the leaf particles to the swelling reagent is 400 g / L.

[0089] (3) After filtering and cleaning the pretreated blade particles, add them to a 3% dodecylbenzenesulfonic acid solution at a liquid-to-solid ratio of 2 g / mL to form a catalytic degradation system. Place the mixture in a reaction vessel and heat it at 180°C for 10 h to fully degrade the blade material.

[0090] (4) After the reaction is complete, filter and separate the liquid. Thoroughly wash and dry the filtered solid to recover the glass fiber.

[0091] (5) Dissolve the lower filtrate obtained in step (4) in a certain amount of ethyl acetate, extract and remove impurities by rotary evaporation, and after evaporating the solvent to dryness, obtain a viscous degradation product. Calculate the degradation rate of organic matter, which is 97.2%.

[0092] (6) The viscous degradation product obtained in step (5) is mixed with bisphenol A diglycidyl ether and methyl hexahydrophthalic anhydride in a mass ratio of 3:10:10; and a certain amount of dmp-30 accelerator is added, the amount of dmp-30 accelerator added is 2% of the total mass; and the thermosetting epoxy resin is obtained by storing it at 50℃, 115℃ and 150℃ for 2 hours, 2 hours and 4 hours respectively.

Claims

1. A method for recycling wind turbine blades primarily composed of fiber-reinforced anhydride-cured epoxy resin, characterized by the following steps: include: (1) The waste wind turbine blades are mechanically crushed and screened, and the blade particles below the screen are retained; The discarded wind turbine blades are mainly composed of fiber-reinforced anhydride-cured epoxy resin, including anhydride-cured carbon fiber reinforcement, anhydride-cured glass fiber reinforcement, or anhydride-cured glass-carbon hybrid fiber reinforcement. (2) Place the leaf particles in a swelling reagent and pretreat them at 80-160℃ for 3-5 hours. The liquid-solid ratio of the leaf particles to the swelling reagent is 300-700 g / L. (3) After filtering and washing the pretreated blade particles from the swelling reagent, add them to the degradation catalyst at a liquid-solid ratio of 1-4 g / mL to form a catalytic degradation system. Place the mixture in a reaction vessel and heat it at 130-180℃ for 7-16 h to fully degrade the blade material. (4) After the reaction is complete, filter and separate the liquid. Thoroughly wash and dry the filtered solid to recover the fiber. (5) Dissolve the filtrate obtained in step (4) in an excess solvent, extract and remove impurities by rotary evaporation, and distill to obtain a viscous degradation product; (6) Mix the viscous degradation product obtained in step (5) with bisphenol A diglycidyl ether and anhydride curing agent in a certain proportion. The mass ratio of viscous degradation product, bisphenol A diglycidyl ether and anhydride curing agent is 1-30:100:50-120. Add a certain amount of curing accelerator. The amount of curing accelerator added is 1%-4% of the total mass. Curing yields thermosetting epoxy resin.

2. The method for recycling wind turbine blades based on fiber-reinforced anhydride-cured epoxy resin according to claim 1, characterized in that: The sieve aperture in step (1) is 80 mesh.

3. The method for recycling wind turbine blades based on fiber-reinforced anhydride-cured epoxy resin according to claim 1, characterized in that: The swelling agent mentioned in step (2) is one or a mixture of several of the following: ethanol, acetone, methanol, nitric acid, ethyl acetate or ethylene glycol.

4. The method for recycling wind turbine blades based on fiber-reinforced anhydride-cured epoxy resin according to claim 1, characterized in that: The degradation catalyst mentioned in step (3) is one of ethylene glycol, cerium nitrate, dodecylbenzenesulfonic acid, ethyl acetate or n-methyl-4-piperidinol.

5. The method for recycling wind turbine blades based on fiber-reinforced anhydride-cured epoxy resin according to claim 1, characterized in that: The solvent mentioned in step (5) is one of ethanol, methanol or ethyl acetate.

6. The method for recycling wind turbine blades based on fiber-reinforced anhydride-cured epoxy resin according to claim 1, characterized in that: The anhydride curing agent mentioned in step (6) is one of methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, or maleic anhydride.

7. The method for recycling wind turbine blades based on fiber-reinforced anhydride-cured epoxy resin according to claim 1, characterized in that: The curing accelerator mentioned in step (6) is dmp-30 accelerator.

8. The method for recycling wind turbine blades based on fiber-reinforced anhydride-cured epoxy resin according to claim 1, characterized in that: The curing conditions described in step (6) are: storage at 40-60℃, 100-120℃, and 140-155℃ for 1-2 hours, 2-3 hours, and 3-4 hours, respectively.

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