Recycled carbon fiber reinforced polypropylene composite material as well as preparation method and application thereof

Abstract

The invention provides a recycled carbon fiber reinforced polypropylene composite material as well as a preparation method and application thereof, and the recycled carbon fiber reinforced polypropylene composite material comprises 75-90 parts of polypropylene, 10-20 parts of modified recycled carbon fiber, 0-3 parts of a compatilizer, 0.2-0.5 part of an antioxidant, 0.1-0.2 part of a light stabilizer and 0.3-1 part of a coloring agent. The modified recycled carbon fiber is obtained by sequentially carrying out supercritical treatment and silane coupling agent treatment on recycled carbon fiber. According to the invention, organic matters and oxide layers remained on the recovered carbon fibers are removed through supercritical treatment, and the surface energy of the carbon fibers is enhanced, so that the surface energy of the carbon fibers is closer to that of polypropylene, and the compatibility of the carbon fibers and the polypropylene is improved; on the other hand, the supercritical treatment can improve the surface roughness of the recycled carbon fibers, increase the surface activity of the recycled carbon fibers, enable the recycled carbon fibers to be more strongly combined with a silane coupling agent, enable the surface energy of the grafted carbon fibers to be further improved, enable the grafted carbon fibers to be more compatible with a polypropylene matrix, enable the binding power between the recycled carbon fibers and polypropylene to be enhanced, and effectively transmit stress; and the mechanical strength, rigidity and toughness of the composite material are obviously improved.

Description

Technical Field

[0001] The invention relates to the technical field of composite material processing, and in particular to a recycled carbon fiber reinforced polypropylene composite material and a preparation method and application thereof. Background Art

[0002] Lightweighting of automobiles means reducing the curb weight of automobiles as much as possible while ensuring the strength and safety performance of automobiles, thereby improving the power of automobiles, reducing fuel consumption, and reducing exhaust pollution. Experiments have shown that if the weight of automobiles is reduced by half, fuel consumption will also be reduced by nearly half. Due to the needs of environmental protection and energy saving, lightweighting of automobiles has become a trend in the development of automobiles in the world.

[0003] The function of the car seat guard is to protect the car seat and effectively keep the interior of the seat clean. The seat guard is generally made of PP / EPDM-TD20 composite material. However, there are some problems with the PP / EPDM-TD20 composite material in practical applications, such as high density, poor rigidity, and easy deformation under stress.

[0004] Therefore, in order to meet the current demand for lightweight automobiles, developing a composite material with higher performance while maintaining lightweight is a difficult problem that needs to be overcome. Summary of the invention

[0005] In view of the shortcomings of the prior art described above, the purpose of the present invention is to provide a recycled carbon fiber reinforced polypropylene composite material to solve the problems of high density and poor rigidity of automobile seat materials in the prior art. At the same time, the present invention will also provide a method for preparing the recycled carbon fiber reinforced polypropylene composite material; in addition, the present invention will also provide an application of the recycled carbon fiber reinforced polypropylene composite material.

[0006] In order to achieve the above-mentioned object and other related objects, the present invention provides the following technical solutions: In a first aspect of the present invention, there is provided a recycled carbon fiber reinforced polypropylene composite material, comprising the following components in parts by weight:

[0007] The modified recycled carbon fiber is obtained by sequentially treating the recycled carbon fiber with a supercritical fluid and a silane coupling agent.

[0008] Furthermore, the supercritical fluid includes supercritical carbon dioxide.

[0009] Furthermore, the silane coupling agent includes at least one of an aminosilane coupling agent and an epoxysilane coupling agent.

[0010] Furthermore, the aminosilane coupling agent includes at least one of γ-aminopropyltriethoxysilane (APTES), γ-aminopropyltrimethoxysilane (APMS), 3-amino-1-propenyltriethoxysilane (AMPS), and γ-aminopropyl-β-chloropropenyltriethoxysilane; The epoxysilane coupling agent includes at least one of γ-epoxypropyltriethoxysilane, 3-epoxypropyltrimethoxysilane and KH-560.

[0011] Furthermore, the modified recycled carbon fiber is obtained by the following preparation method: (1) Supercritical fluid processing The cleaned recycled carbon fiber is placed in a supercritical reactor, and then a supercritical fluid is injected and pressurized to a supercritical state, the pressure is increased to 8-12MPa, the temperature is raised to 40-80°C and reacted for a period of time. After the reaction is completed, the pressure is slowly reduced, the supercritical fluid is recovered, and the treated recycled carbon fiber is taken out and dried to obtain recycled carbon fiber treated with supercritical fluid; (2) Silane coupling agent treatment The recycled carbon fiber treated with supercritical fluid is cut to a required length, and the surface of the recycled carbon fiber is irradiated with ultraviolet rays. Then, the recycled carbon fiber treated with ultraviolet rays is immersed in a solution containing a silane coupling agent, and the temperature is raised to 60-80° C. to react for a period of time. Then, the recycled carbon fiber grafted with the silane coupling agent is taken out, washed, and dried to obtain the modified recycled carbon fiber.

[0012] In step (1), the supercritical treatment time is 0.5-2h; The pressure reduction rate is 0.5-1 MPa / min.

[0013] In step (2), the recycled carbon fiber is cut to 1-6 mm; The wavelength of ultraviolet light is 100-280nm, and the ultraviolet light exposure time is 10-600s; The reaction time of silane coupling agent is 30-60min; The solution for dissolving the silane coupling agent includes at least one of water, methanol, ethanol, isopropanol and DMF.

[0014] Furthermore, the polypropylene is selected from copolymer polypropylene.

[0015] Furthermore, the compatibilizer includes at least one of maleic anhydride grafted polypropylene (PP-g-MAH), styrene-maleic anhydride grafted copolymer (SEBS-g-MAH), and acrylic acid grafted polypropylene (PP-g-AA).

[0016] Furthermore, the added amount of the compatibilizer is preferably 1-2 parts by weight.

[0017] Furthermore, the mass ratio of the modified recycled carbon fiber to the compatibilizer is (5-15):1, preferably 10:1. The mass ratio within this range allows the grafted substance (maleic anhydride and acrylic acid groups) on the compatibilizer to fully cross-link with the amino or epoxy groups on the modified recycled carbon fiber to form a cross-linked network in the composite material, improve various properties of the material, and promote uniform dispersion of the recycled carbon fiber.

[0018] Furthermore, the antioxidant includes at least one of a phenolic antioxidant, an amine antioxidant, and a phosphite composite antioxidant.

[0019] Furthermore, the light stabilizer includes at least one of an ultraviolet absorber and a hindered amine light stabilizer; the light stabilizer is preferably a compound package of an ultraviolet absorber and a hindered amine light stabilizer, the ultraviolet absorber can effectively prevent the damage of ultraviolet rays, and the hindered amine light stabilizer can further inhibit the photodegradation process of the material.

[0020] Furthermore, the light stabilizer includes at least one of benzotriazole ultraviolet absorbers, Tinuvin 770, Tetrakis, and Irganox series.

[0021] Furthermore, the colorant is selected from carbon black masterbatch.

[0022] A second aspect of the present invention provides a method for preparing a recycled carbon fiber reinforced polypropylene composite material, comprising the following steps: S1, modifying the recycled carbon fiber to obtain modified recycled carbon fiber for standby use; S2, weigh each component according to proportion; S3, blending polypropylene, a compatibilizer, an antioxidant, a light stabilizer and a colorant in a high-speed mixer to obtain a premix; S4, first feeding the premix into a twin-screw extruder for melt blending, and then adding the modified recycled carbon fiber into the twin-screw extruder through side feeding; S5. After extrusion, strip drawing, cooling and pelletizing, a recycled carbon fiber reinforced polypropylene composite material is obtained.

[0023] In step S4, the temperature of each zone of the screw is 190-230°C, and the screw speed is 100-200 rpm.

[0024] The third aspect of the present invention provides the use of the recycled carbon fiber reinforced polypropylene composite material in automotive materials.

[0025] Specifically, the recycled carbon fiber reinforced polypropylene composite material is used to be processed into a car seat guard plate.

[0026] As described above, the recycled carbon fiber reinforced polypropylene composite material and its preparation method and application of the present invention have the following beneficial effects: 1. The present invention uses modified recycled carbon fiber to reinforce polypropylene. On the one hand, the residual organic matter and oxide layer on the recycled carbon fiber are first removed by supercritical treatment, and the surface energy of the recycled carbon fiber is enhanced to make it closer to the surface energy of polypropylene, thereby increasing its compatibility with polypropylene; on the other hand, the supercritical treatment improves the surface roughness of the recycled carbon fiber, increases its surface activity, and makes it more strongly combined with the silane coupling agent. The surface energy of the carbon fiber after the silane coupling agent is grafted is further improved, and it is more affinity with the polypropylene matrix, so that the bonding force between the recycled carbon fiber and the polypropylene is enhanced, the stress is effectively transmitted, and the mechanical strength, rigidity and toughness of the composite material are significantly improved.

[0027] 2. The performance of the modified recycled carbon fiber prepared by the present invention is no different from that of new carbon fiber, and the cost is lower, and the production process is more low-carbon and environmentally friendly; compared with other reinforcing fillers such as talcum powder, the modified recycled carbon fiber has little effect on the density of the material, and can ensure the lightweight requirements of the composite material.

[0028] 3. The aminosilane coupling agent or epoxysilane coupling agent grafted on the recycled carbon fiber of the present invention can undergo a cross-linking reaction with the compatibilizer of the present invention to establish a cross-linking network in the composite material, which can effectively transfer and disperse stress, improve the strength and rigidity of the material, and reduce the deformation of the material.

[0029] 4. The light stabilizer of the present invention is a composite package of an ultraviolet absorber and a hindered amine light stabilizer. The ultraviolet absorber can effectively prevent the damage of ultraviolet rays, while the hindered amine light stabilizer can further inhibit the photodegradation process of the material, thereby improving the anti-aging performance of the material and maintaining the stability of the material.

[0030] 5. In the preparation process of the present invention, polypropylene, compatibilizer, antioxidant, light stabilizer and colorant are first blended and then added to the main feed, so that the compatibilizer is evenly dispersed in the matrix, and then the modified recycled carbon fiber is added from the side feed, so that the evenly dispersed compatibilizer can promote the dispersion of the carbon fiber, avoid the floating or agglomeration of the carbon fiber, and further improve the performance of the composite material.

[0031] 6. The present invention uses recycled carbon fiber to reinforce polypropylene. The production process of recycled carbon fiber is low-carbon and environmentally friendly. Compared with new carbon fiber, it can reduce carbon dioxide emissions to about one tenth of the original, which is more green and environmentally friendly. DETAILED DESCRIPTION

[0032] The following is a description of the implementation of the present invention by means of specific embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0033] Example 1 The modified treatment of the recycled carbon fiber includes the following steps: (1) The recycled carbon fiber is preliminarily cleaned to remove the resin residue, dust and other impurities on its surface. After drying, the recycled carbon fiber is placed in a supercritical reactor, and then a sufficient amount of supercritical carbon dioxide is injected to completely penetrate the recycled carbon fiber. The reactor is pressurized to 10 MPa and heated to 60°C for 15 min. After the reaction, the pressure is reduced to normal pressure at a rate of 0.5 MPa / min and the temperature is naturally reduced to normal temperature. The carbon dioxide is recovered, and the treated recycled carbon fiber is taken out and dried to obtain recycled carbon fiber treated with supercritical fluid; (2) Silane coupling agent treatment The recycled carbon fiber treated with supercritical fluid was cut to about 3 mm, and the surface of the recycled carbon fiber was irradiated with 275 nm ultraviolet light for 30 seconds. The recycled carbon fiber was then immersed in an isopropanol solution containing 3% γ-aminopropyltriethoxysilane, and the temperature was raised to 60 ° C for reaction for 30 minutes. The recycled carbon fiber was then taken out, washed with an alcohol solution and dried to obtain modified recycled carbon fiber.

[0034] A recycled carbon fiber reinforced polypropylene composite material, the preparation method of which comprises the following steps: S1, weighing 10 parts by weight of the modified recycled carbon fiber prepared above for later use; S2, weighing 86 parts by weight of copolymerized polypropylene, 0.2 parts by weight of antioxidant, 0.2 parts by weight of Tinuvin 770 and 1 part by weight of carbon black masterbatch; S3, blending the weighed copolymerized polypropylene, antioxidant, Tinuvin 770 and carbon black masterbatch in a high-speed mixer to obtain a premix; S4, first feeding the premix into a twin-screw extruder for melt blending, and then adding the modified recycled carbon fiber into the twin-screw extruder through side feeding; S5. After extrusion, strip drawing, cooling and pelletizing, a recycled carbon fiber reinforced polypropylene composite material is obtained.

[0035] Example 2 A recycled carbon fiber reinforced polypropylene composite material, the preparation method of which comprises the following steps: S1. Weigh 10 parts by weight of the modified recycled carbon fiber prepared in Example 1 for later use; S2, weighing 86 parts by weight of copolymerized polypropylene, 1 part by weight of maleic anhydride grafted polypropylene, 0.2 parts by weight of antioxidant, 0.2 parts by weight of Tinuvin 770 and 1 part by weight of carbon black masterbatch; S3, blending the weighed copolymerized polypropylene, maleic anhydride grafted polypropylene, antioxidant, Tinuvin 770 and carbon black masterbatch in a high-speed mixer to obtain a premix; S4, first feeding the premix into a twin-screw extruder for melt blending, and then adding the modified recycled carbon fiber into the twin-screw extruder through side feeding; S5. After extrusion, strip drawing, cooling and pelletizing, a recycled carbon fiber reinforced polypropylene composite material is obtained.

[0036] Example 3 A recycled carbon fiber reinforced polypropylene composite material, the preparation method of which comprises the following steps: S1, weighing 20 parts by weight of the modified recycled carbon fiber prepared in Example 1 for later use; S2, weighing 76 parts by weight of copolymerized polypropylene, 0.2 parts by weight of antioxidant, 0.2 parts by weight of Tinuvin 770 and 1 part by weight of carbon black masterbatch; S3, blending the weighed copolymerized polypropylene, antioxidant, Tinuvin 770 and carbon black masterbatch in a high-speed mixer to obtain a premix; S4, first feeding the premix into a twin-screw extruder for melt blending, and then adding the modified recycled carbon fiber into the twin-screw extruder through side feeding; S5. After extrusion, strip drawing, cooling and pelletizing, a recycled carbon fiber reinforced polypropylene composite material is obtained.

[0037] Example 4 A recycled carbon fiber reinforced polypropylene composite material, the preparation method of which comprises the following steps: S1. Weigh 10 parts by weight of the modified recycled carbon fiber prepared in Example 1 for later use; S2, weighing 86 parts by weight of copolymerized polypropylene, 1 part by weight of maleic anhydride grafted polypropylene, 0.2 parts by weight of antioxidant, 0.1 parts by weight of Tinuvin 770, 0.1 parts by weight of benzotriazole ultraviolet absorber and 1 part by weight of carbon black masterbatch; S3, blending the weighed copolymerized polypropylene, antioxidant, Tinuvin 770, benzotriazole ultraviolet absorber and carbon black masterbatch in a high-speed mixer to obtain a premix; S4, first feeding the premix into a twin-screw extruder for melt blending, and then adding the modified recycled carbon fiber into the twin-screw extruder through side feeding; S5. After extrusion, strip drawing, cooling and pelletizing, a recycled carbon fiber reinforced polypropylene composite material is obtained.

[0038] Example 5 The modified treatment of the recycled carbon fiber includes the following steps: (1) The recycled carbon fiber is preliminarily cleaned to remove the resin residue, dust and other impurities on its surface. After drying, the recycled carbon fiber is placed in a supercritical reactor, and then a sufficient amount of supercritical carbon dioxide is injected to completely penetrate the recycled carbon fiber. The reactor is pressurized to 10 MPa and heated to 60°C for 15 min. After the reaction, the pressure is reduced to normal pressure at a rate of 0.5 MPa / min and the temperature is naturally reduced to normal temperature. The carbon dioxide is recovered, and the treated recycled carbon fiber is taken out and dried to obtain recycled carbon fiber treated with supercritical fluid; (2) Silane coupling agent treatment The recycled carbon fiber treated with supercritical fluid was cut to about 3 mm, and the surface of the recycled carbon fiber was irradiated with 275 nm ultraviolet light for 30 seconds. The recycled carbon fiber was then immersed in a DMF solution containing 3% γ-aminopropyl-β-chloropropenyltriethoxysilane, and the temperature was raised to 60 ° C for reaction for 30 minutes. The recycled carbon fiber was then taken out, washed with an alcohol solution and dried to obtain a modified recycled carbon fiber.

[0039] A recycled carbon fiber reinforced polypropylene composite material, the preparation method of which comprises the following steps: S1, weighing 10 parts by weight of the modified recycled carbon fiber prepared above for later use; S2, weighing 86 parts by weight of copolymerized polypropylene, 1 part by weight of maleic anhydride grafted polypropylene, 0.2 parts by weight of antioxidant, 0.2 parts by weight of Tinuvin 770 and 1 part by weight of carbon black masterbatch; S3, blending the weighed copolymerized polypropylene, maleic anhydride grafted polypropylene, antioxidant, Tinuvin 770 and carbon black masterbatch in a high-speed mixer to obtain a premix; S4, first feeding the premix into a twin-screw extruder for melt blending, and then adding the modified recycled carbon fiber into the twin-screw extruder through side feeding; S5. After extrusion, strip drawing, cooling and pelletizing, a recycled carbon fiber reinforced polypropylene composite material is obtained.

[0040] Example 6 The modified treatment of the recycled carbon fiber includes the following steps: (1) The recycled carbon fiber is preliminarily cleaned to remove the resin residue, dust and other impurities on its surface. After drying, the recycled carbon fiber is placed in a supercritical reactor, and then a sufficient amount of supercritical carbon dioxide is injected to completely penetrate the recycled carbon fiber. The reactor is pressurized to 10 MPa and heated to 60°C for 15 min. After the reaction, the pressure is reduced to normal pressure at a rate of 0.5 MPa / min and the temperature is naturally reduced to normal temperature. The carbon dioxide is recovered, and the treated recycled carbon fiber is taken out and dried to obtain recycled carbon fiber treated with supercritical fluid; (2) Silane coupling agent treatment The recycled carbon fiber treated with supercritical fluid was cut to about 3 mm, and the surface of the recycled carbon fiber was irradiated with 275 nm ultraviolet light for 30 seconds. The recycled carbon fiber was then immersed in an ethanol solution containing 3% γ-epoxypropyltriethoxysilane, heated to 60 ° C and reacted for 30 minutes. The recycled carbon fiber was then taken out, washed with ethanol solution and dried to obtain modified recycled carbon fiber.

[0041] A recycled carbon fiber reinforced polypropylene composite material, the preparation method of which comprises the following steps: S1, weighing 10 parts by weight of the modified recycled carbon fiber prepared above for later use; S2, weighing 86 parts by weight of copolymerized polypropylene, 1 part by weight of maleic anhydride grafted polypropylene, 0.2 parts by weight of antioxidant, 0.2 parts by weight of Tinuvin 770 and 1 part by weight of carbon black masterbatch; S3, blending the weighed copolymerized polypropylene, maleic anhydride grafted polypropylene, antioxidant, Tinuvin 770 and carbon black masterbatch in a high-speed mixer to obtain a premix; S4, first feeding the premix into a twin-screw extruder for melt blending, and then adding the modified recycled carbon fiber into the twin-screw extruder through side feeding; S5. After extrusion, strip drawing, cooling and pelletizing, a recycled carbon fiber reinforced polypropylene composite material is obtained.

[0042] Comparative Example 1 A polypropylene composite material, the preparation method of which comprises the following steps: S1, weighing 86 parts by weight of copolymerized polypropylene, 0.2 parts by weight of antioxidant, 0.2 parts by weight of Tinuvin 770 and 1 part by weight of carbon black masterbatch; S2, blending the weighed copolymerized polypropylene, antioxidant, Tinuvin 770 and carbon black masterbatch in a high-speed mixer to obtain a premix; S3, first feeding the premix into a twin-screw extruder for melt blending; S4, obtaining a polypropylene composite material through extrusion, strip drawing, cooling and pelletizing.

[0043] Comparative Example 2 A recycled carbon fiber reinforced polypropylene composite material, the preparation method of which comprises the following steps: S1. Weigh 10 parts by weight of unmodified recycled carbon fiber for later use; S2, weighing 86 parts by weight of copolymerized polypropylene, 0.2 parts by weight of antioxidant, 0.2 parts by weight of Tinuvin 770 and 1 part by weight of carbon black masterbatch; S3, blending the weighed copolymerized polypropylene, antioxidant, Tinuvin 770 and carbon black masterbatch in a high-speed mixer to obtain a premix; S4, first feeding the premix into a twin-screw extruder for melt blending, and then adding the recycled carbon fiber into the twin-screw extruder through side feeding; S5. After extrusion, strip drawing, cooling and pelletizing, a recycled carbon fiber reinforced polypropylene composite material is obtained.

[0044] Comparative Example 3 A novel carbon fiber reinforced polypropylene composite material, the preparation method of which comprises the following steps: S1, weigh 10 parts by weight of new carbon fiber for later use; S2, weighing 86 parts by weight of copolymerized polypropylene, 0.2 parts by weight of antioxidant, 1 part by weight of maleic anhydride grafted polypropylene, 0.2 parts by weight of Tinuvin 770 and 1 part by weight of carbon black masterbatch; S3, blending the weighed copolymerized polypropylene, antioxidant, maleic anhydride grafted polypropylene, Tinuvin 770 and carbon black masterbatch in a high-speed mixer to obtain a premix; S4, first feeding the premix into a twin-screw extruder for melt blending, and then adding the new carbon fiber into the twin-screw extruder through side feeding; S5. After extrusion, strip drawing, cooling and pelletizing, a new carbon fiber reinforced polypropylene composite material is obtained.

[0045] The performance of the recycled carbon fiber reinforced polypropylene composite materials prepared in Examples 1-6 and the polypropylene composite materials prepared in Comparative Examples 1-3 were tested. The test results are shown in Table 1.

[0046] Table 1. Performance test results of Examples 1-6 and Comparative Examples 1-3

[0047] By comparing the test results of Example 1 with those of Comparative Examples 1 and 2, it can be seen that adding recycled carbon fiber to polypropylene can directly improve the tensile strength, flexural modulus and notched impact strength of the material, and the reinforcing effect of the modified recycled carbon fiber of the present invention is more obvious, which can better improve the rigidity of the polypropylene material. The reason is that the present invention By comparing the test results of Example 1 and Example 2, it can be seen that maleic anhydride grafted polypropylene is first mixed into the polypropylene material, and the compatibilizers of the two are very good. The maleic anhydride grafted polypropylene can be evenly dispersed in the matrix, and then the modified recycled carbon fiber of the present invention is added. The amino or epoxy group grafted on the modified recycled carbon fiber can be cross-linked with maleic anhydride, which on the one hand promotes the uniform dispersion of the modified recycled carbon fiber in the matrix, and on the other hand, the formation of a composite cross-linked network in the matrix can further improve the material performance and ensure the stability and durability of the performance.

[0048] By comparing the test results of Example 1 and Example 3, it can be seen that continuing to add modified recycled carbon fiber to polypropylene can further improve the tensile strength and flexural modulus of the material, but will have a negative impact on the notched impact strength of the material. Therefore, it is necessary to control the amount of modified recycled carbon fiber within an appropriate range.

[0049] By comparing the test results of Example 2 and Example 4, it can be seen that the light stabilizer compounded with the ultraviolet absorber and the hindered amine light stabilizer is better than a single light stabilizer, making the material have better anti-aging properties. This is because the ultraviolet absorber can effectively prevent the damage of ultraviolet rays, while the hindered amine light stabilizer can further inhibit the photodegradation process of the material.

[0050] By comparing the test results of Example 2 with those of Examples 5 and 6, it can be seen that the recycled carbon fiber modified with aminosilane coupling agent has better compatibility with polypropylene; and the bonding strength between the aminosilane coupling agent and the compatibilizer is higher, so it is preferred to use an aminosilane coupling agent to modify the recycled carbon fiber; and among the aminosilane coupling agents, γ-aminopropyl-β-chloropropenyltriethoxysilane has a better modification effect, which can be used to simultaneously promote crosslinking with the compatibilizer and improve the adhesion of the substrate.

[0051] In summary, on the one hand, the present invention first removes the residual organic matter and oxide layer on the recycled carbon fiber by supercritical treatment, and enhances the surface energy of the recycled carbon fiber, making it closer to the surface energy of polypropylene, thereby increasing its compatibility with polypropylene; on the other hand, supercritical treatment can improve the surface roughness of the recycled carbon fiber, increase its surface activity, make it more strongly combined with the silane coupling agent, and further improve the surface energy of the carbon fiber after the silane coupling agent is grafted, and it is more affinity with the polypropylene matrix, so that the bonding force between the recycled carbon fiber and the polypropylene is enhanced, effectively transmitting stress, and significantly improving the mechanical strength, rigidity and toughness of the composite material. Therefore, the present invention effectively overcomes the various shortcomings in the prior art and has a high industrial utilization value.

[0052] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A recycled carbon fiber reinforced polypropylene composite material, characterized in that: The composition comprises the following components in parts by weight: Polypropylene 75-90 parts; 10-20 parts of modified recycled carbon fiber; Compatibilizer 0-3 parts; Antioxidant 0.2-0.5 parts; Light stabilizer 0.1-0.2 parts; Colorant 0.3-1 part; The modified recycled carbon fiber is obtained by sequentially treating the recycled carbon fiber with a supercritical fluid and a silane coupling agent.

2. The recycled carbon fiber reinforced polypropylene composite material according to claim 1, characterized in that: The silane coupling agent includes at least one of an aminosilane coupling agent and an epoxysilane coupling agent.

3. The recycled carbon fiber reinforced polypropylene composite material according to claim 2, characterized in that: The aminosilane coupling agent includes at least one of γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, 3-amino-1-propenyltriethoxysilane, and γ-aminopropyl-β-chloropropenyltriethoxysilane; The epoxysilane coupling agent includes at least one of γ-epoxypropyltriethoxysilane, 3-epoxypropyltrimethoxysilane and KH-560.

4. The recycled carbon fiber reinforced polypropylene composite material according to claim 3, characterized in that: The modified recycled carbon fiber is obtained by the following preparation method: (1) Supercritical fluid processing The cleaned recycled carbon fiber is placed in a supercritical reactor, and then a supercritical fluid is injected and pressurized to a supercritical state, the pressure is increased to 8-12MPa, the temperature is raised to 40-80°C and reacted for a period of time. After the reaction is completed, the pressure is slowly reduced, the supercritical fluid is recovered, and the treated recycled carbon fiber is taken out and dried to obtain recycled carbon fiber treated with supercritical fluid; (2) Silane coupling agent treatment The recycled carbon fiber treated with supercritical fluid is cut to a required length, and the surface of the recycled carbon fiber is irradiated with ultraviolet rays. Then, the recycled carbon fiber treated with ultraviolet rays is immersed in a solution containing a silane coupling agent, and the temperature is raised to 60-80° C. to react for a period of time. Then, the recycled carbon fiber grafted with the silane coupling agent is taken out, washed, and dried to obtain the modified recycled carbon fiber.

5. The recycled carbon fiber reinforced polypropylene composite material according to claim 2, characterized in that: The compatibilizer includes at least one of maleic anhydride grafted polypropylene, styrene-maleic anhydride grafted copolymer, and acrylic acid grafted polypropylene.

6. The recycled carbon fiber reinforced polypropylene composite material according to claim 5, characterized in that: The mass ratio of the modified recycled carbon fiber to the compatibilizer is (5-15):

1.

7. The recycled carbon fiber reinforced polypropylene composite material according to claim 1, characterized in that: The light stabilizer includes at least one of an ultraviolet light absorber and a hindered amine light stabilizer.

8. The recycled carbon fiber reinforced polypropylene composite material according to claim 7, characterized in that: The light stabilizer includes at least one of benzotriazole ultraviolet absorbers, Tinuvin 770, Tetrakis, and Irganox series.

9. A method for preparing the recycled carbon fiber reinforced polypropylene composite material according to any one of claims 1 to 8, characterized in that: The steps include: S1, modifying the recycled carbon fiber to obtain modified recycled carbon fiber for standby use; S2, weigh each component according to proportion; S3, blending polypropylene, a compatibilizer, an antioxidant, a light stabilizer and a colorant in a high-speed mixer to obtain a premix; S4, first feeding the premix into a twin-screw extruder for melt blending, and then adding the modified recycled carbon fiber into the twin-screw extruder through side feeding; S5. After extrusion, strip drawing, cooling and pelletizing, a recycled carbon fiber reinforced polypropylene composite material is obtained.

10. Use of the recycled carbon fiber reinforced polypropylene composite material according to any one of claims 1 to 8 in automotive materials.

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