A thermoset carbon fiber composite material recycling system and method

Abstract

The present application belongs to the technical field of carbon fiber composite materials, and particularly relates to a thermosetting carbon fiber composite material recycling system and method. The thermosetting carbon fiber composite material recycling system comprises a steam generation unit, a steam activation unit and a recycling unit connected in sequence. The steam generation unit comprises a heating device and a steam pipeline connected to the heating device. The steam activation unit comprises an oxidizing agent reservoir and an auxiliary heating device. The auxiliary heating device is used to heat the oxidizing agent in the oxidizing agent reservoir into oxidizing agent gas, and mix the oxidizing agent gas with steam flowing through the steam pipeline to form an oxidizing and activating mixed gas. The oxidizing and activating mixed gas is used for recycling and processing of the thermosetting carbon fiber composite material in the recycling unit. The system can be widely used for recycling of thermosetting resin-based carbon fiber composite material products, and has the advantages of short recycling time, stable processing effect, high cleanliness of the recycled carbon fiber surface and the like.

Description

Technical Field

[0001] This invention belongs to the field of carbon fiber composite material technology, specifically relating to a recycling system and method for thermosetting carbon fiber composite materials. Background Technology

[0002] Thermosetting carbon fiber composites are formed by embedding carbon fibers in a thermosetting resin matrix. Due to their high specific strength, high specific modulus, and excellent fatigue resistance, they are widely used in aerospace, transportation, new energy, and sporting goods. With the continuous expansion of the application fields of thermosetting carbon fiber composites, the amount of scrapped thermosetting carbon fiber composite products has increased dramatically.

[0003] Due to the thermosetting and cross-linking characteristics of thermosetting resins, their separation from carbon fibers presents significant technical challenges. Existing recycling technologies for thermosetting carbon fiber composites mainly fall into three categories: mechanical recycling, pyrolysis, and solvent decomposition. Mechanical recycling severely damages the original structure and length of the carbon fibers, leading to a significant decrease in the mechanical properties of the recycled products. Pyrolysis produces complex liquid-phase products with difficult subsequent processing, causing severe secondary environmental pollution. Solvent decomposition has low processing efficiency, and the use of large amounts of highly corrosive reagents such as nitric acid can lead to equipment corrosion and secondary pollution. Summary of the Invention

[0004] The purpose of this invention is to provide a recycling system and method for thermosetting carbon fiber composite materials, thereby overcoming the shortcomings of the prior art. It uses a specific processing device and method to perform phase separation and surface purification and recycling of thermosetting carbon fiber composite materials, which has many advantages such as short recycling time, good processing effect, and high surface cleanliness of recycled carbon fibers.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows: On one hand, the present invention provides a recycling system for thermosetting carbon fiber composite materials, comprising a steam generation unit, a steam activation unit and a recycling unit connected in sequence; The steam generating unit includes a heating device and a steam pipe connected thereto. The steam activation unit includes an oxidant reservoir and an auxiliary heating device; The auxiliary heating device is used to heat the oxidant in the oxidant reservoir into oxidant gas, and to mix the oxidant gas with the steam flowing through the steam pipe to form an oxidizing and activating mixed gas. The oxidation-activation mixed gas is used to recycle the thermosetting carbon fiber composite material in the recycling unit.

[0006] The steam generating unit heats water to form high-temperature, high-pressure steam; the steam activation unit heats the oxidant into a gaseous state and mixes it with the high-temperature steam to form an oxidation-activation mixed gas, which is then transported to the recycling heating unit; the recycling heating unit heats the thermosetting carbon fiber composite material to be treated and contacts it with the oxidation-activation mixed gas for carbon fiber recycling. The oxidation-activation mixed gas, after the combined action of the steam generator and the steam activation device, is transported to the recycling heating furnace through a pressure-resistant high-temperature pipeline and sprayed onto the surface of the waste thermosetting composite material product to be treated through a spray pipe at a specific location.

[0007] In some other embodiments, the recycling unit includes a heating furnace body, the top of which is provided with an oxidation-activation mixed gas delivery pipe connected to a spray device. The oxidation-activation mixed gas delivery pipe is also connected to a steam pipe and is used to deliver the oxidation-activation mixed gas to the spray device.

[0008] In some other embodiments, the heating furnace body is a closed heat recovery cavity formed by a high-temperature resistant, sealed, and heat-insulating structure, used to store the thermosetting carbon fiber composite material to be processed and to heat it.

[0009] The spraying device is an array-arranged spraying device; The distance between the spraying device and the waste thermosetting carbon fiber composite material is 1-10 mm, which effectively ensures that the surface of the waste carbon fiber composite material can be uniformly contacted by high-temperature oxidation activation steam.

[0010] In some other embodiments, the thermosetting carbon fiber composite material recycling system further includes a thermal cleaning and drying unit, which comprises a thermal cleaning device and a drying device connected in sequence. The thermal cleaning and drying unit is used to clean and dry the recycled carbon fibers.

[0011] In some other embodiments, the hot cleaning device includes an ultrasonic vibrator and a heater; the oxidant reservoir includes a mechanical pump that pushes the oxidant into an auxiliary heating device, and then into a steam pipe.

[0012] On the other hand, the present invention provides a method for recycling thermosetting carbon fiber composite materials, comprising the following steps: (1) The oxidant is heated to an oxidant gas and mixed with water vapor to obtain an oxidizing and activating mixed gas; (2) The oxidative activation mixed gas is used to recycle the thermosetting composite material to be treated to obtain recycled carbon fiber; (3) The recycled carbon fibers are subjected to thermal cleaning and drying to obtain carbon fibers.

[0013] In some other embodiments, in step (1), the oxidant is selected from one or more of hydrofluoric acid, concentrated nitric acid, concentrated sulfuric acid, sodium hydroxide, potassium hydroxide and hydrogen peroxide; the oxidant may also be any of other salts or weak acidic or weak alkaline oxidants.

[0014] The oxidant is heated to a temperature of 70-120℃. The specific heating temperature can be flexibly set according to the type of oxidant and the requirements for separation of the activated phase.

[0015] In some other embodiments, in step (1), the volume ratio of the oxidant gas to water vapor is 2% to 20%.

[0016] In some other embodiments, in step (2), the pressure of the oxidizing and activating mixed gas is 0.3-2 MPa; The recycling process is carried out at a temperature of 400-530 ℃ for 15-30 minutes. The time can be adjusted flexibly according to the specifications of the specific recycled products.

[0017] In some other embodiments, in step (3), the temperature of the hot cleaning is 40-80°C, and the solvent is an organic solvent; the temperature of the drying treatment is 100-150°C. The hot cleaning device uses organic solvents (acetone, alcohol, etc.) to clean the recycled carbon fibers. The device is equipped with an ultrasonic vibration device and a heating device to ensure the cleaning effect on the carbon fiber surface. The drying device dries the carbon fibers after the hot cleaning.

[0018] The beneficial effects of this invention are: (1) The thermosetting carbon fiber composite material recycling system of the present invention employs an auxiliary heating device to heat the oxidant in the oxidant reservoir into oxidant gas, and mixes the oxidant gas with steam flowing through the steam pipe to form an oxidizing and activating mixed gas. The oxidizing and activating mixed gas is used for the recycling of thermosetting carbon fiber composite materials in the recycling unit, and sprayed onto the surface of the thermosetting carbon fiber composite material at a set pressure to achieve carbon fiber recycling. The process parameters are higher than those of the prior art, and a better recycling effect can be achieved.

[0019] (2) The thermosetting carbon fiber composite material recycling method of the present invention can recycle continuous carbon fibers with excellent performance and original woven structure, reduce recycling costs and environmental impact, and realize the industrial recycling of carbon fiber reinforced resin matrix composite materials.

[0020] In summary, the thermosetting carbon fiber composite material recycling system and method of the present invention can be widely used for the recycling of thermosetting resin-based carbon fiber composite material products, and has many advantages such as short recycling time, stable treatment effect, and high surface cleanliness of recycled carbon fibers. Attached Figure Description

[0021] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0022] Figure 1 This is a schematic diagram of the thermosetting carbon fiber composite material recycling system in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the structure of the thermal cleaning and drying unit in Embodiment 1 of the present invention; The unit includes a steam generation unit 1, a steam activation unit 2, a recovery heating unit 3, a hot cleaning and drying unit 4, a heating device 5, a steam pipeline 6, an oxidant reservoir 7, an auxiliary heating device 8, a heating furnace body 9, an oxidation-activation mixed gas conveying pipeline 10, a spraying device 11, a hot cleaning device 12, and a drying device 13. Detailed Implementation

[0023] Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be construed as limiting the scope of the invention. Specific conditions not specified in the embodiments are performed under conventional conditions or conditions recommended by the manufacturer. Components whose manufacturers are not specified are all commercially available conventional products.

[0024] Example 1 This embodiment provides a recycling system for thermosetting carbon fiber composite materials, including a steam generating unit 1, a steam activation unit 2, a recycling unit 3, and a cleaning and drying unit 4 connected in sequence. The steam generating unit 1 is used to heat water to form high-temperature and high-pressure steam; the steam activation unit 2 is used to heat an oxidant into a gaseous state and mix it with the high-temperature steam to form an oxidizing and activating mixed gas, which is then transported to the recycling unit 3; the recycling unit 3 is used to heat the thermosetting carbon fiber composite material to be treated and contact it with the oxidizing and activating mixed gas to perform carbon fiber recycling treatment; and the cleaning and drying unit 4 is used to clean and dry the recycled carbon fiber.

[0025] like Figure 1 As shown, the steam generating unit 1 includes a heating device 5 and a steam pipe 6 connected to the water heating device 5. The heating device 5 heats deionized water to a boiling state to generate high-temperature steam. The steam pipe 6 transports the high-temperature steam generated by the heating device 5.

[0026] The steam activation unit 2 includes an oxidant reservoir 7 and an auxiliary heating device 8 connected in sequence. The auxiliary heating device 8 is connected to a steam pipe 6. The oxidant reservoir 7 is equipped with a mechanical pump to provide driving force, which pushes the oxidant into the auxiliary heating device 8 and then into the steam pipe 6. The oxidant reservoir 7 is used to store the oxidant. The oxidant is selected from one or more of strong oxidants and their salts, weak acidic oxidants, and weak basic oxidants. Strong oxidants are selected from one or more of hydrofluoric acid, concentrated nitric acid, concentrated sulfuric acid, sodium hydroxide, potassium hydroxide, and hydrogen peroxide. The heating temperature of the auxiliary heating device 8 can be controlled between 70-120℃. The auxiliary heating device 8 is used to heat the oxidant in the oxidant reservoir 7 into a gaseous state, forming an oxidant gas. The oxidant gas is mixed with high-temperature steam to form an oxidizing and activating mixed gas. The mixing ratio of high-temperature steam and oxidant gas can be controlled within the volume ratio range of 2% to 20% according to the specific phase separation activation design requirements, and can be flexibly adjusted as required. The oxidizing and activating mixed gas is transported to the recycling heating furnace through the steam pipe 6 for recycling and processing waste thermosetting carbon fiber composite materials.

[0027] The recycling unit 3 includes a heating furnace body 9, with an oxidation-activation mixed gas conveying pipe 10 at the top, which is connected to a spray device 11. The heating furnace body 9 is a closed heat recovery chamber formed by a high-temperature resistant, sealed, and insulated structure, used to store the thermosetting carbon fiber composite material to be processed and to heat it. The heating temperature can be controlled within the range of 400-530℃ and can be flexibly adjusted according to the recycling process. The oxidation-activation mixed gas conveying pipe 10 is connected to a high-temperature and pressure-resistant pipe 6, and is used to convey the oxidation-activation mixed gas to the spray device 11. The spray device 11 consists of multiple existing spray structures arranged in an array. The spray pressure of the spray device 11 is controlled between 0.3-2 MPa, and the spray time is controlled between 15-30 min, which can be flexibly adjusted according to the specifications of the specific recycled product. The distance between the spray device 11 and the waste carbon fiber composite material is 1-10 mm, effectively ensuring that the surface of the waste carbon fiber composite material can be uniformly contacted by the high-temperature oxidation-activation vapor.

[0028] like Figure 2 As shown, the hot cleaning and drying unit 4 includes a hot cleaning device 12 and a drying device 13 connected in sequence. The hot cleaning device 12 is equipped with an ultrasonic vibrator and a heater to perform hot cleaning on the recycled carbon fibers. The solvent used in the hot cleaning device 12 is an organic solvent, which can be selected from one or both of acetone and alcohol. The drying device 13 is used to dry the hot-cleaned carbon fibers. The drying temperature is controlled within the range of 100-150℃, and the drying time is flexibly adjusted according to design requirements.

[0029] Example 2 This embodiment provides a method for recycling thermosetting carbon fiber composite materials, using the recycling system for thermosetting carbon fiber composite materials described in Embodiment 1. Taking carbon fiber epoxy resin-based composite materials as an example, the specific steps are as follows: (1) The oxidant in the oxidant reservoir is heated to a gaseous state by an auxiliary heating device and mixed with high-temperature water vapor to form an oxidizing and activating mixed gas; wherein the mixing volume ratio is 5%, the oxidant liquid is hydrofluoric acid, and the heating temperature is 80℃.

[0030] (2) The oxidizing and activating mixed gas is transported into the recycling heating furnace through a pressure-resistant high-temperature pipeline and sprayed onto the surface of the thermosetting composite material to be treated through a spraying device; wherein, the distance between the thermosetting composite material to be treated by the spraying device is 2mm, the heating temperature of the heating furnace is 420℃, the spraying pressure is 0.5MPa, and the recycling treatment is carried out for 15 minutes to obtain carbon fiber.

[0031] (3) The carbon fiber is subjected to hot cleaning and drying treatment. The hot cleaning is done with acetone at a temperature of 45°C and the drying temperature is 100°C to obtain clean recycled carbon fiber.

[0032] Example 3 This embodiment provides a method for recycling thermosetting carbon fiber composite materials, using the recycling system for thermosetting carbon fiber composite materials described in Example 1. Taking carbon fiber phenolic resin-based composite materials as an example, the specific steps are as follows: (1) The oxidant in the oxidant reservoir is heated to a gaseous state by an auxiliary heating device and mixed with high-temperature water vapor to form an oxidizing and activating mixed gas; wherein the mixing volume ratio is 8%, the oxidant liquid is concentrated nitric acid, and the heating temperature is 90℃.

[0033] (2) The oxidizing and activating mixed gas is transported into the recycling heating furnace through a pressure-resistant high-temperature pipeline and sprayed onto the surface of the thermosetting composite material to be treated through a spraying device; wherein, the distance between the thermosetting composite material to be treated by the spraying device is 4mm, the heating temperature of the heating furnace is 450℃, the spraying pressure is 0.8MPa, and the recycling treatment is carried out for 20 minutes to obtain carbon fiber.

[0034] (3) The carbon fiber is subjected to hot cleaning and drying treatment. The hot cleaning is carried out with acetone at a temperature of 50°C and the drying temperature is 110°C to obtain clean recycled carbon fiber.

[0035] Example 4 This embodiment provides a method for recycling thermosetting carbon fiber composite materials, using the recycling system for thermosetting carbon fiber composite materials described in Example 1. Taking carbon fiber polyimide resin-based composite materials as an example, the specific steps are as follows: (1) The oxidant in the oxidant reservoir is heated to a gaseous state by an auxiliary heating device and mixed with high-temperature water vapor to form an oxidizing and activating mixed gas; wherein the mixing volume ratio is 10%, the oxidant liquid is concentrated sulfuric acid, and the heating temperature is 100℃.

[0036] (2) The oxidizing and activating mixed gas is transported into the recycling heating furnace through a pressure-resistant high-temperature pipeline and sprayed onto the surface of the thermosetting composite material to be treated through a spraying device; wherein, the distance between the thermosetting composite material to be treated by the spraying device is 5mm, the heating temperature of the heating furnace is 480℃, the spraying pressure is 1MPa, and the recycling treatment is carried out for 25 minutes to obtain carbon fiber.

[0037] (3) The carbon fiber is subjected to hot cleaning and drying treatment. The hot cleaning is carried out with acetone at a temperature of 60°C and the drying temperature is 120°C to obtain clean recycled carbon fiber.

[0038] Example 5 This embodiment provides a method for recycling thermosetting carbon fiber composite materials, using the recycling system for thermosetting carbon fiber composite materials described in Example 1. Taking carbon fiber bismaleimide resin-based composite materials as an example, the specific steps are as follows: (1) The oxidant in the oxidant reservoir is heated to a gaseous state by an auxiliary heating device and mixed with high-temperature water vapor to form an oxidizing and activating mixed gas; wherein the mixing volume ratio is 15%, the oxidant liquid is sodium hydroxide, and the heating temperature is 110℃.

[0039] (2) The oxidizing and activating mixed gas is transported into the recycling heating furnace through a pressure-resistant high-temperature pipeline and sprayed onto the surface of the thermosetting composite material to be treated through a spraying device; wherein, the distance between the thermosetting composite material to be treated by the spraying device is 6 mm, the heating temperature of the heating furnace is 490℃, the spraying pressure is 1.5MPa, and the recycling treatment is carried out for 30 min to obtain carbon fiber.

[0040] (3) The carbon fiber is subjected to hot cleaning and drying treatment. The hot cleaning is carried out with acetone at a temperature of 70°C and the drying temperature is 130°C to obtain clean recycled carbon fiber.

[0041] Comparative Example 1 Unlike Example 2, the steam activation unit 2 in Example 1 is removed. In step (1), only high-temperature water vapor is generated and sprayed onto the surface of the thermosetting composite material to be treated through a spraying device. The other steps are the same as in Example 2.

[0042] Comparative Example 2 Unlike Example 2, the steam generating unit 1 in Example 1 is removed. In step (1), only oxidant gas is generated and sprayed onto the surface of the thermosetting composite material to be treated through a spraying device. The other steps are the same as in Example 2.

[0043] Table 1 shows the properties of recycled carbon fiber.

[0044] A comparison of Examples 2-5 and Comparative Examples 1-2 in Table 1 reveals that the thermosetting carbon fiber composite material recycling system provided in Example 1 of the present invention can be widely used for the recycling of thermosetting resin-based carbon fiber composite material products. It has many advantages such as short recycling time, low processing energy consumption, and high surface cleanliness of recycled carbon fibers.

[0045] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A recycling system for thermosetting carbon fiber composite materials, characterized in that, It includes a steam generation unit, a steam activation unit, and a recovery and treatment unit connected in sequence; The steam generating unit includes a heating device and a steam pipe connected thereto. The steam activation unit includes an oxidant reservoir and an auxiliary heating device; The auxiliary heating device is used to heat the oxidant in the oxidant reservoir into oxidant gas, and to mix the oxidant gas with the steam flowing through the steam pipe to form an oxidizing and activating mixed gas. The oxidizing and activating mixed gas is used to recycle the thermosetting carbon fiber composite material in the recycling unit. The recycling unit includes a heating furnace body, and the top of the heating furnace body is provided with an oxidation-activation mixed gas conveying pipe, which is connected to a spraying device. The heating furnace body is a closed heat recovery cavity formed by a high-temperature resistant, sealed, and heat-insulating structure. The spraying device is an array-arranged spraying device; The distance between the spraying device and the waste thermosetting carbon fiber composite material is 1-10 mm.

2. The recycling system for thermosetting carbon fiber composite materials according to claim 1, characterized in that, The thermosetting carbon fiber composite material recycling system further includes a thermal cleaning and drying unit, which comprises a thermal cleaning device and a drying device connected in sequence.

3. The recycling system for thermosetting carbon fiber composite materials according to claim 2, characterized in that, The hot cleaning device is equipped with an ultrasonic vibrator and a heater; the oxidant reservoir is equipped with a mechanical pump.

4. A method for recycling thermosetting carbon fiber composite materials, characterized in that, The recycling process using the thermosetting carbon fiber composite material recycling system according to any one of claims 1-3 includes the following steps: (1) The oxidant is heated to an oxidant gas and mixed with water vapor to obtain an oxidizing and activating mixed gas; (2) The oxidative activation mixed gas is used to recycle the thermosetting composite material to be treated to obtain recycled carbon fiber; (3) The recycled carbon fibers are subjected to thermal cleaning and drying to obtain carbon fibers.

5. The recycling method for thermosetting carbon fiber composite materials according to claim 4, characterized in that, In step (1), the oxidant is selected from one or more of concentrated nitric acid, concentrated sulfuric acid, sodium hydroxide, potassium hydroxide and hydrogen peroxide; The oxidant is heated to a temperature of 70-120℃.

6. The recycling method for thermosetting carbon fiber composite materials according to claim 4, characterized in that, In step (1), the volume ratio of the oxidant gas to water vapor is 2-20%.

7. The method for recycling thermosetting carbon fiber composite materials according to claim 4, characterized in that, In step (2), the pressure of the oxidation-activation mixed gas is 0.3-2 MPa; The recycling process is carried out at a temperature of 400-530 ℃ for 15-30 min.

8. The method for recycling thermosetting carbon fiber composite materials according to claim 4, characterized in that, In step (3), the temperature of the hot cleaning is 40-80℃, and the solvent is an organic solvent; The drying process is carried out at a temperature of 100-150℃.

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