Carbon fiber reinforced thermoplastic composite prepreg and preparation method thereof

Abstract

The invention belongs to the technical field of carbon fiber composite materials, and particularly relates to a carbon fiber reinforced thermoplastic composite prepreg and a preparation method thereof. According to the carbon fiber reinforced thermoplastic composite prepreg prepared by the preparation method disclosed by the invention, a layer of carbon fiber fabric and thermoplastic resin films on two sides of the carbon fiber fabric form a laminated structure, and the carbon fiber fabric is modified, so that polydopamine films are formed on two sides of the carbon fiber fabric through impregnation. Through heating, pressurizing and ultrasonic vibration of the laminated structure, resin in the thermoplastic resin film is softened and melted, flows in the laminating direction and is mechanically interlocked with the carbon fiber fabric through part of polydopamine, meanwhile, the carbon fiber fabric is infiltrated by the resin, and the thermoplastic resin and the carbon fibers are uniformly distributed. Therefore, the carbon fiber can be relatively difficultly stripped from the thermoplastic resin, the bonding strength of the composite material can be improved, and the process for preparing the fiber-reinforced thermoplastic composite material prepreg by the method has the advantages of high efficiency and batch production.

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon fiber composite materials, and in particular relates to a carbon fiber reinforced thermoplastic composite prepreg and a preparation method thereof. Background Art

[0002] In recent years, thermoplastic composites based on carbon fiber fabrics have been widely used in aerospace, automotive, military, and sports equipment applications. Achieving full synergistic effects between the two phases is crucial for the resin matrix to fully impregnate the carbon fiber fabric. Direct hot pressing is a common method, but due to its high viscosity, the thermoplastic resin matrix struggles to fully and evenly impregnate the carbon fiber fabric, resulting in poor performance in the resulting composite prepregs.

[0003] Chinese patent document CN101845232A discloses a thermoplastic resin-based carbon fiber composite material and a preparation method thereof. A stacked layer of carbon fiber fabric and a thermoplastic resin film are heated sequentially by infrared lamps and heating rollers to melt the thermoplastic resin film and impregnate the carbon fiber fabric. The carbon fiber fabric is then completely impregnated with the thermoplastic resin and pressed into a single-layer structure by a pressing roller. However, this method relies on highly automated technology and places high demands on the preparation equipment. Furthermore, during the preparation process, the material is exposed to infrared lamps, which can easily age the material, reducing the performance of the composite material. Summary of the Invention

[0004] In order to solve the problem of poor performance of existing composite material prepregs, the present invention provides a carbon fiber reinforced thermoplastic composite material prepreg and a preparation method thereof.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: A carbon fiber reinforced thermoplastic composite prepreg is composed of a layer of carbon fiber fabric and thermoplastic resin films on both sides of the carbon fiber fabric. The carbon fiber fabric is a carbon fiber fabric modified with polydopamine, and the thermoplastic resin film is a polypropylene resin film or PA6 resin film. The carbon fiber fabric accounts for 30% to 50% of the total volume of the prepreg.

[0006] Preferably, the carbon fiber fabric modified with polydopamine is modified by placing the carbon fiber fabric in a dopamine solution, fully impregnating it, ultrasonicating it while impregnating it, taking out the impregnated carbon fiber fabric, washing it, and drying it to obtain the polydopamine-modified carbon fiber fabric, wherein the dopamine solution is prepared by adding dopamine hydrochloride to a Tris buffer solution.

[0007] Preferably, the thermoplastic resin films on both sides are made of the same resin type.

[0008] Preferably, the thickness of a single layer of the thermoplastic resin film is greater than the thickness of the carbon fiber fabric.

[0009] More preferably, the thickness of a single layer of the thermoplastic resin film is 0.2-0.4 mm, the thickness of a single layer of the carbon fiber fabric is 0.05-0.1 mm, and the thickness change of the carbon fiber fabric before and after modification with polydopamine is negligible.

[0010] More preferably, the thermoplastic resin films on both sides have the same thickness.

[0011] Preferably, the carbon fiber fabric has a fiber specification of 3K and a mass per unit area of 198±5g / m 2 .

[0012] The present invention also provides a method for preparing the above-mentioned carbon fiber reinforced thermoplastic composite material prepreg, comprising the following steps: (1) Place the carbon fiber fabric in the dopamine solution, fully immerse it, and perform ultrasonic treatment while immersing it; (2) taking out the impregnated carbon fiber fabric, washing it, and drying it to obtain a polydopamine-modified carbon fiber fabric; (3) The polydopamine modified carbon fiber fabric obtained above and the thermoplastic resin film are hot pressed to obtain a carbon fiber reinforced thermoplastic composite prepreg.

[0013] Preferably, the carbon fiber fabric in step (1) is a PAN-type carbon fiber made from polyacrylonitrile or a pitch-type carbon fiber made from petroleum asphalt.

[0014] Preferably, the dopamine solution in step (1) is a dopamine solution formed by adding dopamine hydrochloride to a Tris buffer solution, and the Tris buffer solution is a Tris buffer solution formed by dissolving Tris in deionized water, stirring evenly, and then adding a dilute hydrochloric acid solution dropwise until the pH reaches 8.5.

[0015] Further preferably, the concentration of the Tris buffer solution is 0.01-0.05 mol / L, and the concentration of the dopamine solution is 3.5-4.5 g / L.

[0016] More preferably, the concentration of the dopamine solution is 4 g / L.

[0017] Further preferably, the immersion time in step (1) is 2 hours, and the ultrasonic frequency is 1 kHz to 30 kHz.

[0018] Further preferably, the drying temperature in step (2) is 50° C. and the drying time is 2 h.

[0019] Further preferably, in step (2), both sides of the carbon fiber fabric are impregnated to form a polydopamine film to obtain a polydopamine-modified carbon fiber fabric.

[0020] Further preferably, the hot pressing molding in step (3) includes a stacking structure preparation process, an infiltration process, and a pressure-maintaining cooling process.

[0021] More preferably, the laminated structure preparation process is to sequentially stack a thermoplastic resin film, a polydopamine-modified carbon fiber fabric, and a thermoplastic resin film.

[0022] Further preferably, the impregnation process is: heating, pressurizing, and applying ultrasonic vibration to the stacked structure along the stacking direction, so that the resin contained in the thermoplastic resin film in the stacked structure melts and flows, and impregnates into the polydopamine-modified carbon fiber fabric.

[0023] Preferably, the carbon fiber fabric in step (1) is a component in which a plurality of carbon fibers are arranged, and is a porous structure having pores that can be impregnated with resin during the impregnation step.

[0024] More preferably, in the infiltration process, the hot pressing reaction temperature is 170-280° C., the hot pressing pressure is 1-5 MPa, the hot pressing time is 1-25 min, and the ultrasonic frequency is 1-30 Hz.

[0025] Preferably, in the impregnation process, the four sides of the polydopamine-modified carbon fiber fabric are bonded and fixed by adhesive tape made of the same material as the thermoplastic resin film to prevent the fiber direction from shifting during the transfer process.

[0026] Further preferably, the pressure-holding cooling process is: applying pressure along the stacking direction, and at the same time, cooling the carbon fiber fabric after being impregnated with thermoplastic resin at a cooling rate of 10°C / min, and the pressure-holding pressure is the same as the hot pressing molding pressure.

[0027] Preferably, the carbon fiber reinforced thermoplastic composite prepreg has a laminated structure in at least a portion of the longitudinal section direction, which is composed of three layers, namely, a layer of the thermoplastic resin, a layer comprising the polydopamine-modified carbon fiber fabric, and a layer of the thermoplastic resin, which are laminated in sequence.

[0028] Compared with the prior art, the present invention has the following beneficial effects: (1) The carbon fiber reinforced thermoplastic composite prepreg prepared by the present invention has polydopamine filled on the surface and inside of the carbon fiber fabric, and the polydopamine serves as an intermediate bridge connecting the carbon fiber fabric and the thermoplastic resin. By heating and pressurizing the stacked structure, on one side of the carbon fiber fabric, the resin in the thermoplastic resin film softens, melts, and flows along the stacking direction, and is mechanically interlocked with the carbon fiber fabric through part of the polydopamine. On the other side of the carbon fiber fabric, the resin in the thermoplastic resin film softens, melts, and flows along the stacking direction, and is mechanically interlocked with the other side of the carbon fiber fabric through part of the polydopamine, and the resin impregnates the carbon fiber fabric. As a result, the polydopamine and the thermoplastic resin can be fully impregnated into the carbon fiber fabric, and at the same time, the thermoplastic resin and the carbon fiber are evenly distributed. Therefore, the carbon fiber can be relatively difficult to peel off from the thermoplastic resin, which can improve the bonding strength of the composite material.

[0029] (2) The present invention optimizes the preparation process of polydopamine-modified carbon fiber fabric by simultaneously impregnating and ultrasonically optimizing the process, significantly improving the efficiency of polydopamine in the interfiber gaps and shortening the impregnation time. During the impregnation process, ultrasonic vibration is applied to the laminated structure to force the resin to penetrate the interfiber bundle gaps, thereby improving the impregnation of the carbon fiber fabric with the thermoplastic resin. During the cooling process, the process is cooled at a cooling rate of 10°C / min, shortening the preparation time of the prepreg and improving production efficiency. Therefore, through the improvement of the above technology, the carbon fiber fabric and the thermoplastic resin can be evenly distributed, which is conducive to the complete impregnation of the carbon fiber fabric with the thermoplastic resin and improving the mechanical properties of the prepreg.

[0030] (3) The method of the present invention is used to prepare fiber-reinforced thermoplastic composite prepregs. The process has the advantages of high efficiency and mass production, and can be applied to the automotive, aerospace, and machinery manufacturing fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The present invention provides a flow chart for preparing a carbon fiber thermoplastic composite prepreg; Figure 2 The temperature and pressure curves of the infiltration process and the pressure-maintaining cooling process in Example 1 of the present invention; Figure 3 This is a bar graph showing the tensile properties of the composite materials prepared in Example 1 of the present invention and Comparative Examples 1, 2, 4, and 5; Figure 4 This is a bar graph showing the bending properties of the composite materials prepared in Example 1 of the present invention and Comparative Examples 1, 2, 4, and 5; Figure 5 The tensile properties bar graph of the composite materials prepared in Example 2 of the present invention and Comparative Example 3; Figure 6 This is a bar chart of the bending properties of the composite materials prepared in Example 2 of the present invention and Comparative Example 3. DETAILED DESCRIPTION

[0032] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0033] The carbon fiber fabric used in the embodiment is PAN type carbon fiber made of polyacrylonitrile as raw material, with a width of 300 mm, a fiber specification of 3K, and a unit area mass of 198 g / m 2 ; The density of polypropylene resin film is 0.9g / cm 3 , thickness is 0.3mm, width is 300mm; the density of PA6, nylon 6 resin film, is 1.14g / cm 3 , thickness is 0.3mm and width is 300mm.

[0034] Tensile strength and tensile modulus test standards: According to ASTM D3039 "Standard test method for tensile properties of polymer matrix composites".

[0035] Flexural strength and flexural modulus test standards: According to ASTM D7264 "Standard test method for flexural properties of polymer matrix composites".

[0036] Example 1 A method for preparing a carbon fiber reinforced thermoplastic composite material prepreg comprises the following steps: (1) Dissolve 3.6 g of Tris in 1000 ml of deionized water, stir evenly, and then add dilute hydrochloric acid solution dropwise until the pH reaches 8.5 to form a Tris buffer solution with a concentration of 0.03 mol / L. (2) Add 4 g of dopamine hydrochloride to the Tris buffer solution to form a dopamine solution; (3) Place a carbon fiber fabric with a thickness of 0.08 mm in a dopamine solution and fully immerse it for 2 h. Apply ultrasonic vibration at a frequency of 30 Hz during the immersion. (4) The carbon fiber fabric after impregnation was taken out and washed, and then placed in a drying oven at 50°C for 2 h to obtain a polydopamine-modified carbon fiber fabric; (5) The polydopamine-modified carbon fiber fabric obtained in step (4) and a single-layer polypropylene resin film with a thickness of 0.3 mm are hot-pressed to obtain a carbon fiber reinforced thermoplastic composite prepreg.

[0037] The carbon fiber fabric accounts for 30% of the total volume of the prepreg. Figure 1As shown: polypropylene resin film, polydopamine modified carbon fiber fabric, and polypropylene resin film are stacked in sequence to form a stacked structure; the polydopamine modified carbon fiber fabric is bonded and fixed by polypropylene resin tape on all sides, and pressure is applied along the stacking direction and heated and ultrasonically vibrated to make the two layers of resin melt and flow, and infiltrate into the gaps in the carbon fiber fabric respectively; the pressure is maintained to keep the fiber and the molten resin as close as possible, and the cooling rate is maintained at 10°C / min to quickly form the carbon fiber thermoplastic composite prepreg. Among them, the hot pressing reaction temperature is 210°C, the hot pressing pressure and holding pressure are 3MPa, the hot pressing time is 1min, the ultrasonic frequency is 30Hz, and the hot pressing temperature and pressure change curves are shown as follows. Figure 2 As shown in the figure, the black curve represents the temperature setting during the molding process, the red curve represents the process of applying pressure during the molding process, and the green line represents the holding time during the molding process.

[0038] The performance test of the prepared composite material showed that the tensile strength was 275 MPa, the tensile modulus was 16.5 GPa, the flexural strength was 78 MPa, and the flexural modulus was 15.2 GPa.

[0039] Example 2 A method for preparing a carbon fiber reinforced thermoplastic composite material prepreg comprises the following steps: (1) Dissolve 3.6 g of Tris in 1000 ml of deionized water, stir evenly, and then add dilute hydrochloric acid solution dropwise until the pH reaches 8.5 to form a Tris buffer solution with a concentration of 0.03 mol / L. (2) Add 4 g of dopamine hydrochloride to the Tris buffer solution to form a dopamine solution; (3) Place a carbon fiber fabric with a thickness of 0.08 mm in a dopamine solution and fully immerse it for 2 h. Apply ultrasonic vibration at a frequency of 30 Hz during the immersion. (4) The carbon fiber fabric after impregnation was taken out and washed, and then placed in a drying oven at 50°C for 2 h to obtain a polydopamine-modified carbon fiber fabric; (5) The polydopamine-modified carbon fiber fabric obtained in step (4) and a single-layer PA6 resin film with a thickness of 0.3 mm are hot-pressed to obtain a carbon fiber reinforced thermoplastic composite prepreg.

[0040] Specifically, the hot pressing process is as follows: PA6 resin film, polydopamine-modified carbon fiber fabric, and PA6 resin film are stacked in sequence to form a stacked structure; the polydopamine-modified carbon fiber fabric is bonded and fixed with PA6 resin tape on all sides, and pressure is applied along the stacking direction while heating and ultrasonic vibration are performed to melt and flow the two layers of resin, respectively infiltrating into the gaps in the carbon fiber fabric; pressure is maintained to keep the fibers and the molten resin as close as possible, and a cooling rate of 10°C / min is maintained to rapidly form the carbon fiber thermoplastic composite prepreg. The hot pressing reaction temperature is 250°C, the hot pressing pressure and holding pressure are 5MPa, the hot pressing time is 10min, and the ultrasonic frequency is 30Hz.

[0041] The carbon fiber fabric accounts for 30% of the total volume of the prepreg. Performance tests of the resulting composite material showed a tensile strength of 321 MPa, a tensile modulus of 3.3 GPa, a flexural strength of 285 MPa, and a flexural modulus of 17.0 GPa.

[0042] Comparative Example 1 A polypropylene resin film, carbon fiber fabric, and polypropylene resin film are stacked in sequence to form a laminated structure; the carbon fiber fabric is bonded and fixed with polypropylene resin tape on all sides, and pressure is applied along the stacking direction while heating and ultrasonic vibration are performed to melt and flow the two layers of resin, respectively, and infiltrate the gaps in the carbon fiber fabric; pressure is maintained to keep the fibers and the molten resin as close as possible, and the cooling rate is maintained at a cooling rate of 10°C / min, so that the carbon fiber thermoplastic composite prepreg is quickly formed. Among them, the hot pressing reaction temperature is 210°C, the hot pressing pressure and holding pressure are 3MPa, the hot pressing time is 1min, the ultrasonic frequency is 30Hz, the single layer thickness of the polypropylene resin film is 0.3mm, the thickness of the carbon fiber fabric is 0.08mm, and the carbon fiber fabric accounts for 30% of the total volume of the prepreg.

[0043] The performance test of the prepared composite material showed that the tensile strength was 228 MPa, the tensile modulus was 15.6 GPa, the flexural strength was 75 MPa, and the flexural modulus was 12.6 GPa.

[0044] Comparative Example 2 A polypropylene resin film, carbon fiber fabric, and polypropylene resin film are stacked in sequence to form a laminated structure. The carbon fiber fabric is bonded and fixed with polypropylene resin tape on all sides. Pressure is applied along the stacking direction and heated and ultrasonically vibrated to melt and flow the two layers of resin, infiltrating the gaps in the carbon fiber fabric. Pressure is maintained to keep the fibers and the molten resin as close as possible, and the temperature is lowered by natural cooling. The hot pressing reaction temperature is 210°C, the hot pressing pressure and holding pressure are 3MPa, the hot pressing time is 1min, the ultrasonic frequency is 30Hz, the single layer thickness of the polypropylene resin film is 0.3mm, the thickness of the carbon fiber fabric is 0.08mm, and the carbon fiber fabric accounts for 30% of the total volume of the prepreg.

[0045] The performance test of the prepared composite material showed that the tensile strength was 216 MPa, the tensile modulus was 14.8 GPa, the flexural strength was 75 MPa, and the flexural modulus was 9.8 GPa.

[0046] Comparative Example 3 PA6 resin film, carbon fiber fabric, and PA6 resin film are stacked in sequence to form a laminated structure; the carbon fiber fabric is bonded and fixed with PA6 resin tape on all sides, and pressure is applied along the stacking direction while heating and ultrasonic vibration are performed to melt and flow the two layers of resin, respectively, and infiltrate the gaps in the carbon fiber fabric; pressure is maintained to keep the fibers and the molten resin as close as possible, and the cooling rate is maintained at a cooling rate of 10°C / min, so that the carbon fiber thermoplastic composite prepreg is quickly formed. Among them, the hot pressing reaction temperature is 250°C, the hot pressing pressure and holding pressure are 5MPa, the hot pressing time is 10min, the ultrasonic frequency is 30Hz, the single layer thickness of the PA6 resin film is 0.3mm, the thickness of the carbon fiber fabric is 0.08mm, and the carbon fiber fabric accounts for 30% of the total volume of the prepreg.

[0047] The composite material was tested for performance. The tensile strength was 250 MPa, the tensile modulus was 2.6 GPa, the flexural strength was 230 MPa, and the flexural modulus was 14.8 GPa.

[0048] Comparative Example 4: A method for preparing a carbon fiber reinforced thermoplastic composite material prepreg comprises the following steps: (1) Dissolve 3.6 g of Tris in 1000 ml of deionized water, stir evenly, and then add dilute hydrochloric acid solution dropwise until the pH reaches 8.5 to form a Tris buffer solution with a concentration of 0.03 mol / L. (2) Add 4 g of dopamine hydrochloride to the Tris buffer solution to form a dopamine solution; (3) Place a 0.08 mm thick carbon fiber fabric in the dopamine solution and soak it for 2 h; (4) The carbon fiber fabric after impregnation was taken out and washed, and then placed in a drying oven at 50°C for 2 h to obtain a polydopamine-modified carbon fiber fabric; (5) The polydopamine-modified carbon fiber fabric obtained in step (4) and a single layer of polypropylene resin with a thickness of 0.3 mm are hot-pressed to obtain a carbon fiber reinforced thermoplastic composite prepreg.

[0049] The carbon fiber fabric accounts for 30% of the total volume of the prepreg. Other processes are the same as in Example 1.

[0050] The performance tests of the prepared composite material showed that the tensile strength was 250 MPa, the tensile modulus was 16.0 GPa, the flexural strength was 76 MPa, and the flexural modulus was 14.4 GPa.

[0051] Comparative Example 5 A method for preparing a carbon fiber reinforced thermoplastic composite material prepreg comprises the following steps: (1) Dissolve 3.6 g of Tris in 1000 ml of deionized water, stir evenly, and then add dilute hydrochloric acid solution dropwise until the pH reaches 8.5 to form a Tris buffer solution with a concentration of 0.03 mol / L. (2) Add 4 g of dopamine hydrochloride to the Tris buffer solution to form a dopamine solution; (3) Place a carbon fiber fabric with a thickness of 0.08 mm in a dopamine solution and fully immerse it for 2 h while applying ultrasonic vibration; (4) The carbon fiber fabric after impregnation was taken out and washed, and then placed in a drying oven at 50°C for 2 h to obtain a polydopamine-modified carbon fiber fabric; (5) The polydopamine-modified carbon fiber fabric obtained in step (4) and a single layer of polypropylene resin with a thickness of 0.3 mm are hot-pressed to obtain a carbon fiber reinforced thermoplastic composite prepreg.

[0052] Specifically, the hot pressing process is as follows: polypropylene resin film, polydopamine-modified carbon fiber fabric, and polypropylene resin film are stacked in sequence to form a stacked structure; the polydopamine-modified carbon fiber fabric is bonded and fixed with polypropylene resin tape on all sides, and pressure is applied along the stacking direction while heating and ultrasonic vibration are applied to melt and flow the two layers of resin, respectively, soaking into the gaps in the carbon fiber fabric; pressure is maintained to keep the fibers and the molten resin as close as possible, and the temperature is lowered by natural cooling. The hot pressing reaction temperature is 210°C, the hot pressing pressure and holding pressure are 3MPa, the hot pressing time is 1min, the ultrasonic frequency is 30Hz, and the carbon fiber fabric accounts for 30% of the total volume of the prepreg.

[0053] The performance tests of the prepared composite material showed that the tensile strength was 248 MPa, the tensile modulus was 15.2 GPa, and the flexural strength was 76 MPa, and the flexural modulus was 12.0 GPa.

[0054] Figure 3 The tensile properties of the composite materials prepared in Example 1 and Comparative Examples 1, 2, 4, and 5 of the present invention are shown in the bar graph. Figure 4 The bending properties of the composite materials prepared in Example 1 and Comparative Examples 1, 2, 4, and 5 of the present invention are shown in the bar graph. Figure 5 The tensile properties of the composite materials prepared in Example 2 and Comparative Example 3 are shown in the bar graph. Figure 6 This is a bar chart of the bending properties of the composite materials prepared in Example 2 of the present invention and Comparative Example 3. It can be seen from the figure that the tensile strength, tensile modulus, flexural strength and flexural modulus of the carbon fiber reinforced thermoplastic composite prepreg prepared by the preparation method of the present invention are improved.

Claims

1. A carbon fiber reinforced thermoplastic composite prepreg, characterized in that: It consists of a layer of carbon fiber fabric and thermoplastic resin films on both sides of it. The carbon fiber fabric is a carbon fiber fabric modified by polydopamine, and the thermoplastic resin film is a polypropylene resin film or PA6 resin film. The carbon fiber fabric accounts for 30% to 50% of the total volume of the prepreg.

2. The carbon fiber reinforced thermoplastic composite prepreg according to claim 1, characterized in that: The thermoplastic resin films on both sides are made of the same resin type and have the same thickness. The thickness of the thermoplastic resin films is greater than the thickness of the carbon fiber fabric.

3. The carbon fiber reinforced thermoplastic composite prepreg according to claim 2, characterized in that: The thickness of the thermoplastic resin film is 0.2-0.4 mm, and the thickness of the carbon fiber fabric is 0.05-0.1 mm.

4. A method for preparing a carbon fiber reinforced thermoplastic composite prepreg according to any one of claims 1 to 3, characterized in that: The following steps are involved: (1) Place the carbon fiber fabric in the dopamine solution, fully immerse it, and perform ultrasonic treatment while immersing it; (2) taking out the impregnated carbon fiber fabric, washing it, and drying it to obtain a polydopamine-modified carbon fiber fabric; (3) The polydopamine modified carbon fiber fabric obtained above and the thermoplastic resin film are hot pressed to obtain a carbon fiber reinforced thermoplastic composite prepreg.

5. The method for preparing a carbon fiber reinforced thermoplastic composite prepreg according to claim 4, characterized in that: The carbon fiber fabric in step (1) is a PAN-type carbon fiber made from polyacrylonitrile or a pitch-type carbon fiber made from petroleum asphalt.

6. The method for preparing a carbon fiber reinforced thermoplastic composite prepreg according to claim 4, characterized in that: The dopamine solution in step (1) is formed by adding dopamine hydrochloride to a Tris buffer solution, and the Tris buffer solution is formed by dissolving Tris in deionized water, stirring evenly, and then adding dilute hydrochloric acid solution dropwise until the pH is 8.

5.

7. The method for preparing a carbon fiber reinforced thermoplastic composite prepreg according to claim 6, characterized in that: The concentration of the Tris buffer solution is 0.01-0.05 mol / L, and the concentration of the dopamine solution is 3.5-4.5 g / L.

8. The method for preparing a carbon fiber reinforced thermoplastic composite prepreg according to claim 4, characterized in that: The hot pressing molding in step (3) includes a stacking structure preparation process, an infiltration process, and a pressure-maintaining cooling process.

9. The method for preparing a carbon fiber reinforced thermoplastic composite prepreg according to claim 8, characterized in that: The laminated structure preparation process comprises sequentially stacking a thermoplastic resin film, a polydopamine-modified carbon fiber fabric, and a thermoplastic resin film; The impregnation step comprises: heating, pressurizing, and applying ultrasonic vibration to the stacked structure along the stacking direction, so that the resin contained in the thermoplastic resin film in the stacked structure melts and flows, and impregnates the polydopamine-modified carbon fiber fabric; The pressure-maintaining cooling process is as follows: applying pressure along the stacking direction, and at the same time, cooling the carbon fiber fabric impregnated with thermoplastic resin at a cooling rate of 10° C. / min to form the fabric.

10. The method for preparing a carbon fiber reinforced thermoplastic composite prepreg according to claim 9, characterized in that: In the infiltration process, the hot pressing reaction temperature is 170-280° C., the hot pressing pressure is 1-5 MPa, the hot pressing time is 1-25 min, and the ultrasonic frequency is 1-30 Hz.

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