Water-based thermoplastic sizing agent doped with nano material as well as preparation method and application of water-based thermoplastic sizing agent

Abstract

The invention discloses a water-based thermoplastic sizing agent doped with a nano material as well as a preparation method and application of the water-based thermoplastic sizing agent, and belongs to the technical field of composite materials. According to the sizing agent, a bisphenol compound-diphenolic acid-dihalogen benzophenone / sulfone copolymer is used as matrix resin, a carboxyl-containing polyaryletherketone / sulfone copolymer is synthesized through SN2 nucleophilic condensation polymerization, the carboxyl-containing polyaryletherketone / sulfone copolymer is prepared into the water-based sizing agent by adopting an emulsion / solvent evaporation method, and nano materials such as graphene oxide and multi-walled carbon nanotubes are further doped. The sizing agent takes water as a dispersion medium, is green and environment-friendly, has excellent heat resistance, has good compatibility with phenolphthalein polyether ketone and other high-performance thermoplastic resins, and can significantly improve the interface bonding strength, interlaminar shear strength, bending strength and monofilament tensile strength of the carbon fiber composite material. The preparation process is simple and controllable, and is suitable for preparing high-performance carbon fiber composite materials in the fields of aerospace, mechano-electronics and the like.

Description

Technical Field

[0001] This invention belongs to the field of composite material technology, specifically relating to an aqueous thermoplastic sizing agent doped with nanomaterials, its preparation method, and its application. Background Technology

[0002] Carbon fiber reinforced thermoplastic resin matrix composites (CFRTPs) have shown broad application prospects in high-tech fields such as aerospace, defense equipment, automotive industry, and electronics due to their excellent mechanical properties, good processability, recyclability, and rapid prototyping potential. While carbon fiber, as a reinforcement, possesses a series of advantages such as high specific strength, high specific modulus, and corrosion resistance, its chemically inert and smooth surface generally results in weak interfacial adhesion with the resin matrix, becoming a key bottleneck restricting the overall performance improvement of composite materials.

[0003] To address interface issues, sizing is widely used in carbon fiber production as a highly efficient and energy-saving surface treatment process. By coating the fiber surface with a thin layer of sizing agent, it not only protects the fiber, reduces fuzz, and improves bundle cohesion, but more importantly, it creates an effective interfacial transition layer between the fiber and the resin, optimizing stress transfer. However, most carbon fiber sizing agents currently used in industry are thermosetting epoxy resin systems. When these are combined with high-performance thermoplastic resins (such as PEEK, PEK, and PES), problems arise such as chemical structure incompatibility and insufficient heat resistance. Furthermore, these sizing agents are prone to degradation during the high-temperature processing typically required for thermoplastic resins, thus impairing interfacial properties.

[0004] While some progress has been made in the development of thermoplastic sizing agents, several limitations remain. For example, some techniques introduce special monomers or post-modifications to impart water solubility or improve adhesion to the resin, but these often involve cumbersome synthesis steps, multiple acid-base adjustments and washings, making the process complex and unsuitable for large-scale production. Other techniques employ resin salification to achieve water dispersion, but this still cannot completely avoid the residue of organic solvents, posing environmental and safety risks. Furthermore, although some studies have attempted to introduce nanomaterials into sizing systems to enhance the interface, these efforts are mostly focused on solvent-based systems or have failed to systematically address the stable dispersion of nanomaterials in aqueous systems and their synergistic effects with the resin matrix.

[0005] In summary, developing a water-based thermoplastic sizing agent that combines excellent heat resistance, good compatibility with high-performance thermoplastic resins, true environmental friendliness, and simple processing, while effectively integrating nano-reinforcement technology, is of great significance for overcoming the interface performance bottleneck of carbon fiber / thermoplastic composites and promoting their wider application in high-tech fields. This invention is proposed against this backdrop. Summary of the Invention

[0006] This invention provides a water-based, high-temperature resistant thermoplastic sizing agent doped with nanomaterials, its preparation method, and its applications. The sizing agent uses bio-based bisphenol A as the key monomer, which is synthesized into a carboxyl-containing polyaryletherketone / sulfone matrix resin through nucleophilic condensation polymerization. This resin is then emulsified and doped with nanomaterials (such as graphene oxide and functionalized carbon nanotubes) in water. This product is environmentally friendly, exhibits excellent heat resistance, and has good compatibility with high-performance resins such as PEK-C. It can significantly improve the interfacial bonding strength and overall mechanical properties of carbon fiber composites, making it suitable for applications in aerospace and other fields.

[0007] On the one hand, the present invention provides an aqueous thermoplastic sizing agent doped with nanomaterials, using the following technical solution: An aqueous thermoplastic sizing agent doped with nanomaterials, comprising the following components by mass fraction: Matrix resin 0.5%–5%, Nanomaterials 0.1%–1%, Surfactant 0.1%–2%, The remainder is deionized water; The matrix resin is a carboxyl-containing polyarylether ketone / sulfone copolymer, which has the structure shown in Formula I: ;

[0008] Wherein, X is selected from one of the following structures: ;

[0009] Y is selected from one of the following structures: .

[0010] Preferably, the intrinsic viscosity of the carboxyl-containing polyaryletherketone / sulfone copolymer is 0.3–0.35 dL / g; the nanomaterial is selected from one or more of graphene oxide, hydroxylated multi-walled carbon nanotubes, carboxylated multi-walled carbon nanotubes, aminated multi-walled carbon nanotubes, and nano-silica; the surfactant is selected from one or more of sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, hexadecyltrimethylammonium bromide, and fatty alcohol polyoxyethylene ether.

[0011] On the other hand, the present invention also provides an aqueous thermoplastic sizing agent doped with nanomaterials, using the following technical solution: A method for preparing an aqueous thermoplastic sizing agent doped with nanomaterials includes the following steps: S1. Synthesis of the matrix resin: Under an inert atmosphere, bisphenol compounds, bisphenolic acids, and dihalogen compounds are dissolved in a polar aprotic solvent. A salt-forming agent and a dehydrating agent are added, and the dehydration reaction and polymerization reaction are carried out sequentially. After the reaction, the mixture is acidified, precipitated, washed, and dried to obtain a carboxyl-containing polyarylether ketone / sulfone copolymer. The dihalogen compound has the structure shown in Formula II. ;

[0012] Wherein, R is independently selected from fluorine or chlorine; S2. Preparation of preliminary sizing agent: The matrix resin obtained in step S1 is dissolved in an organic solvent that is immiscible with water to obtain an oil phase resin solution; the surfactant is dissolved in deionized water to obtain an aqueous phase solution; the oil phase resin solution is added dropwise to the aqueous phase solution under stirring, and the organic solvent is removed after emulsification to obtain a preliminary water-based sizing agent; S3. Doping with nanomaterials: Nanomaterials are added to the preliminary aqueous sizing agent obtained in step S2, and after dispersion treatment, an aqueous thermoplastic sizing agent doped with nanomaterials is obtained.

[0013] Preferably, in step S1, the bisphenol compound is selected from one or more of hydroquinone, biphenyl, bisphenol A, phenolphthalein, bisphenol fluorene, and N-phenylindolone; the molar ratio of the bisphenol compound to bisphenolic acid is 1:0.1 to 1; the molar ratio of the bisphenol compound to the dihalogen compound is 0.1 to 1:1; the salt-forming agent is potassium carbonate and / or sodium carbonate, and the molar ratio of the bisphenol compound to the salt-forming agent is 1:1 to 1.5.

[0014] Preferably, in step S1, the polar aprotic solvent is selected from at least one of sulfolane, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and N-methylpyrrolidone; the dehydrating agent is toluene and / or xylene; the temperature of the dehydrating reaction is 140–160°C, and the time is 2–3 h; the temperature of the polymerization reaction is 180–220°C, and the time is 4–6 h.

[0015] Preferably, in step S2, the organic solvent that is immiscible with water is selected from one of dichloromethane, trichloromethane, and 1,1-dichloroethane; the emulsification treatment is performed by ultrasonic shearing for 15 to 30 minutes.

[0016] Preferably, in step S3, the dispersion treatment includes: first, ultrasonic dispersion at a power of 400-1000W for 15-30 minutes, and then stirring at a speed of 500-1500rpm for 2-4 hours.

[0017] This invention also provides the application of an aqueous thermoplastic sizing agent doped with nanomaterials in the preparation of carbon fiber reinforced thermoplastic composites, using the following technical solution: The application of an aqueous thermoplastic sizing agent doped with nanomaterials in the preparation of carbon fiber reinforced thermoplastic composites includes the following steps: (1) The carbon fiber fabric is immersed in a sizing agent for sizing treatment, and then dried to obtain the sized carbon fiber fabric. (2) The sized carbon fiber fabric and thermoplastic resin film are alternately stacked and hot-pressed to obtain carbon fiber reinforced thermoplastic composite material.

[0018] Preferably, in step (1), the immersion time for sizing is 1 to 2 hours, the drying temperature is 100 to 150°C, the drying time is 12 to 24 hours, and the sizing amount is controlled to be 1.0% to 5.0% of the carbon fiber fabric mass.

[0019] Preferably, in step (2), the thermoplastic resin film is a phenolphthalein polyetherketone film; the hot pressing conditions are: temperature 320~380℃, pressure 5~10MPa, time 30~60min.

[0020] In summary, the beneficial effects of the present invention are as follows: This invention achieves multiple beneficial effects in material design and process. First, by using bio-based bisphenolic acid as the key monomer, it not only reduces raw material costs and aligns with green chemistry principles, but also makes large-scale production possible. The synthesized carboxyl-containing polyaryletherketone / sulfone matrix resin exhibits high main chain rigidity and excellent heat resistance. Its glass transition temperature and thermal decomposition temperature far exceed the processing temperatures of common thermoplastic resins, ensuring stability during high-temperature molding. Simultaneously, the resin structure is similar to high-performance matrix materials such as phenolphthalein polyetherketone (PEK-C), following the principle of "like dissolves like," and the introduced carboxyl groups can specifically interact with it, thereby fundamentally improving the interfacial compatibility between the fiber and the resin.

[0021] Secondly, this invention employs a mature emulsion / solvent evaporation method to prepare water-based sizing agents. The process is simple and controllable, allowing for precise control of emulsion particle size and solid content, making it suitable for continuous production. Furthermore, the final product uses water as the continuous phase, ensuring safety and environmental friendliness. By incorporating nanomaterials such as graphene oxide or functionalized carbon nanotubes, a multi-scale reinforcing network can be constructed at the fiber-resin interface, effectively transferring stress and inhibiting crack propagation. This results in a significant synergistic reinforcing effect with the matrix resin, ultimately leading to a substantial improvement in key mechanical properties of the composite material, such as interlaminar shear strength and flexural strength. Attached Figure Description

[0022] Figure 1 The 1H NMR spectra of the carboxyl-containing copolymer resins prepared in Examples 1-5 are shown below. Figure 2 The following are the Fourier Transform Infrared (FT-IR) spectra of the carboxyl-containing copolymer resins prepared in Examples 1-5; Figure 3 Differential scanning calorimetry (DSC) curves of the carboxyl-containing copolymer resins prepared in Examples 1-5; Figure 4Thermogravimetric analysis (TGA) curves of the carboxyl-containing copolymer resins prepared in Examples 1-5. Detailed Implementation

[0023] The present invention will be further described in detail below with reference to the embodiments.

[0024] Example Example 1

[0025] The specific steps for preparing a carbon fiber composite material are as follows: Step 1: Under N2 protection, add 0.025 mol phenolphthalein, 0.025 mol bisphenol A, 0.05 mol difluorobenzophenone, 8.707 g K2CO3, 60 mL sulfolane, and 60 mL xylene sequentially to a three-necked flask equipped with a water-removing device. Heat and stir, reflux at 160℃ for 2 h to remove water, distill off the xylene, slowly raise the temperature to 210℃ and react for 0.5 h, then stop the reaction. Cool the system to 100℃, add 100 mL DMAc / acetic acid (9:1) to the polymer solution, and stir for 2 h. Pour the polymer solution into a settling agent ethanol / deionized water (volume ratio = 3:1) to obtain a pale yellow filamentous polymer, repeatedly boiled and washed with deionized water 5-7 times. Dry under vacuum at 150℃ for 24 h to obtain a white powdery carboxyl-containing copolymer resin, denoted as PEK-DA1.

[0026] Figure 2 The PEK-DA NMR spectrum was used to assign peaks to the polymer NMR spectrum. Furthermore, by using the peak area ratio of Hn:Ho in the NMR spectrum, it was determined that the polymer potassium carboxyl salt was completely acidified to carboxyl groups, thus confirming the successful synthesis of carboxyl-containing thermoplastic polyarylether ketone.

[0027] Step 2: Weigh 2.0 g of dry powdered resin and dissolve it in 40 mL of dichloromethane as the oil phase. Dissolve 0.4 g of sodium dodecyl sulfate (SDS) in 195.6 mL of deionized water as the aqueous phase. Under high-speed stirring at 1500 rpm, slowly add the oil phase dropwise to the aqueous phase. After the addition is complete, treat with an ultrasonic cell disruptor (600 W) for 20 min to form a stable emulsion. Then, remove the dichloromethane by rotary evaporation to obtain an aqueous sizing agent matrix with a solid content of approximately 1%. Take 100 mL of this matrix and add 0.1 g of carboxylated multi-walled carbon nanotubes (CNTs-COOH). After ultrasonic dispersion (800 W, 20 min) and high-speed mechanical stirring (1200 rpm, 3 h), the final sizing agent is obtained.

[0028] Step 3: Cut T300 3K carbon fiber plain weave fabric (area density 200 g / m²) to the specified size, thoroughly desizing it in a Soxhlet extractor by reflux with acetone at 80℃ for 24 h, and drying at 100℃. Immerse it in a sizing agent for 2 h, remove it, and dry it in an oven at 120℃ for 24 h, controlling the sizing amount to 1.5±0.1 wt%. Alternately stack the sizing carbon fiber fabric and phenolphthalein polyetherketone (PEK-C) film (thickness 0.1 mm) in the [0°] layup direction (9 layers of film, 8 layers of fabric), and place them in a hot press mold. Hot pressing procedure: heat to 380℃ at 10℃ / min, apply pressure of 8 MPa, hold at temperature and pressure for 45 min, and then cool under pressure to below 100℃ to demold, obtaining the composite material sheet. After processing into standard test strips, test its interlaminar shear strength (ILSS), flexural strength, and carbon fiber monofilament tensile strength.

[0029] Example 2 The preparation method of a carbon fiber composite material differs from that in Example 1 in that the amount of phenolphthalein in step 1 is changed from 0.025 mol to 0.03 mol and the amount of bisphenol acid is changed from 0.025 mol to 0.02 mol. The resulting white powdery carboxyl-containing copolymer resin is designated as PEK-DA2. The remaining steps are the same as in Example 1.

[0030] Example 3 The preparation method of a carbon fiber composite material differs from that in Example 1 in that the amount of phenolphthalein in step 1 is changed from 0.025 mol to 0.035 mol and the amount of bisphenol A is changed from 0.025 mol to 0.015 mol. The resulting white powdery carboxyl-containing copolymer resin is designated as PEK-DA3. The remaining steps are the same as in Example 1.

[0031] Example 4 The preparation method of a carbon fiber composite material differs from that in Example 1 in that the amount of phenolphthalein in step 1 is changed from 0.025 mol to 0.04 mol and the amount of bisphenol acid is changed from 0.025 mol to 0.01 mol. The resulting white powdery carboxyl-containing copolymer resin is designated as PEK-DA4. The remaining steps are the same as in Example 1.

[0032] Example 5 The preparation method of a carbon fiber composite material differs from that in Example 1 in that the amount of phenolphthalein in step 1 is changed from 0.025 mol to 0.045 mol and the amount of bisphenol acid is changed from 0.025 mol to 0.005 mol. The resulting white powdery carboxyl-containing copolymer resin is designated as PEK-DA5. The remaining steps are the same as in Example 1.

[0033] Example 6 A carbon fiber composite material was prepared, with the specific preparation method differing from that in Example 1. In step 1, 0.025 mol of phenolphthalein was replaced with an equal amount of 4,4'-biphenyl hydroquinone, and the resulting white powdery resin was designated BP-DA1. In step 2, 40 mL of dichloromethane was replaced with an equal volume of trichloromethane; 0.4 g of sodium dodecyl sulfate (SDS) was replaced with an equal mass of hexadecyltrimethylammonium bromide (CTAB); and 0.1 g of carboxylated multi-walled carbon nanotubes (CNTs-COOH) was replaced with an equal mass of hydroxylated multi-walled carbon nanotubes (CNTs-OH). The remaining steps were the same as in Example 1.

[0034] Example 7 The preparation method of a carbon fiber composite material differs from that in Example 1 in that 0.025 mol of 4,4'-biphenyl was replaced with an equal amount of hydroquinone in step 1, and the resulting white powdery resin was designated as HQ-DA1; the remaining steps were the same as in Example 2.

[0035] Example 8 The preparation method of a carbon fiber composite material differs from that in Example 3 in that: in step 2, 100 mL of aqueous sizing agent matrix is ​​replaced with 50 mL; 0.1 g of carboxylated multi-walled carbon nanotubes is replaced with 0.05 g of graphene oxide (GO) aqueous dispersion (2% solid content); ultrasonic dispersion and high-speed mechanical stirring are replaced with ultrasonic treatment in an ice-water bath for 30 minutes; and in step 3, the sizing amount is changed from 1.5 ± 0.1 wt% to 1.2 wt%. The remaining steps are the same as in Example 1.

[0036] Example 9 The preparation method of a carbon fiber composite material differs from that in Example 4 in that: in step 2, 100 mL of aqueous sizing agent matrix is ​​replaced with 50 mL; 0.1 g of carboxylated multi-walled carbon nanotubes are replaced with 0.03 g of GO aqueous dispersion (2% solid content) and 0.04 g of COOH-MWCNTs powder; ultrasonic dispersion and high-speed mechanical stirring are replaced with ultrasonic treatment in an ice-water bath for 45 minutes; and in step 3, the sizing amount is changed from 1.5 ± 0.1 wt% to 1.25 wt%. The remaining steps are the same as in Example 1.

[0037] Comparative Example Comparative Example 1 The desized and dried carbon fiber fabric was directly bonded to a PEK-C film using the same hot-pressing process to prepare a composite material.

[0038] Comparative Example 2 Commercially available T300 carbon fiber cloth with an epoxy sizing agent (approximately 1.2 wt%) was hot-pressed with a PEK-C film. Due to the severe decomposition of the epoxy resin at 380°C, defects existed at the interface of the composite material.

[0039] Test case Test Example 1 The carboxyl-containing copolymer resins prepared in step 1 of Examples 1-5 were analyzed by Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance (NMR) spectroscopy (NMR). 1 ¹H NMR analysis, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA) were performed. Fourier transform infrared spectroscopy (FT-IR) was performed using a Nicolet iS10 spectrometer with KBr pellet method. ¹H NMR was performed using a Bruker AVANCE III 400 MHz spectrometer with DMSO-d6 as solvent. Differential scanning calorimetry (DSC) was performed using a TA Instruments Q200 spectrometer under nitrogen atmosphere at a heating rate of 10 °C / min. Thermogravimetric analysis (TGA) was performed using a TA Instruments Q500 spectrometer under nitrogen atmosphere at a heating rate of 10 °C / min.

[0040] like Figures 1-4 As shown, the structure and properties of the carboxyl-containing polyarylether ketone / sulfone copolymer synthesized in this invention were confirmed by multiple characterization methods: Figure 1 The ratio of chemical shift to proton peak area in the proton NMR spectrum further confirmed the polymer's chemical structure and the complete acidification of the carboxyl group. Figure 2 The appearance of characteristic peaks of specific functional groups in the infrared spectrum verifies the successful introduction of the target polymer backbone and carboxyl groups; Figure 3 The differential scanning calorimetry (DSC) curves show the glass transition temperature (T) of this series of resins. g Temperatures can reach as high as 192-221℃. Figure 4 The thermogravimetric analysis curves indicate its initial thermal decomposition temperature (T). d5% Both exceeded 415℃, which together proves that the matrix resin has excellent heat resistance stability far exceeding the conventional thermoplastic processing temperature, laying the foundation for its application in high-temperature composite materials.

[0041] Test Example 2 The carbon fibers and their composites prepared in Examples 1, 6-9, and Comparative Examples 1-2 were tested for interlaminar shear strength, flexural strength, and monofilament tensile strength according to the national standards ASTM D2344, ASTM D790, and ASTM D3379. Interlaminar shear strength (ILSS) was tested using a universal testing machine according to ASTM D2344; flexural strength was tested using a universal testing machine according to ASTM D790; and monofilament tensile strength was tested using a fiber strength tester according to ASTM D3379 (to assess the effect of sizing on the intrinsic strength of the fiber).

[0042] Table 1 clearly shows that the sizing agents provided in each embodiment of this invention can significantly improve the key mechanical properties of carbon fiber / PEK-C composite materials. Compared to Comparative Example 1 (ILSS 65.4 MPa, flexural strength 685 MPa) without sizing and Comparative Example 2 (ILSS 58.2 MPa) which used a commercial epoxy sizing agent but failed at high temperature, the interlaminar shear strength (ILSS) of all embodiments was increased to over 90 MPa, and the flexural strength exceeded 850 MPa. Among them, Example 4 (PEK-DA4 resin system) exhibited the best overall performance, with an ILSS as high as 101.5 MPa and a flexural strength of 918 MPa. This fully demonstrates that the sizing agent of this invention, by introducing a specific carboxyl copolymer matrix and nanomaterials, effectively enhances the interfacial bonding force between the fiber and the resin, thereby achieving a synergistic and significant improvement in the overall mechanical properties of the composite material.

[0043] Table 1. Summary of mechanical properties of carbon fiber composites in Examples 1, 6-9 and Comparative Examples 1-2 Interlaminar shear strength (MPa) Bending strength (MPa) Monofilament tensile strength (GPa) Example 1 94.2 890 4.22 Example 6 93.0 875 4.19 Example 7 90.3 857 4.15 Example 8 101.5 918 4.28 Example 9 99.8 905 4.26 Comparative Example 1 65.4 685 3.95 Comparative Example 2 58.2 620 4.05

[0044] The above are all preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A water-based thermoplastic sizing agent doped with nanomaterials, characterized in that, By mass fraction, it includes the following components: Matrix resin 0.5%–5%, Nanomaterials 0.1%–1%, Surfactant 0.1%–2%, The remainder is deionized water; The matrix resin is a carboxyl-containing polyarylether ketone / sulfone copolymer, which has the structure shown in Formula I: ； Wherein, X is selected from one of the following structures: ； Y is selected from one of the following structures: 。 2. The aqueous thermoplastic sizing agent doped with nanomaterials according to claim 1, characterized in that, The intrinsic viscosity of the carboxyl-containing polyarylether ketone / sulfone copolymer is 0.3–0.35 dL / g; the nanomaterial is selected from one or more of graphene oxide, hydroxylated multi-walled carbon nanotubes, carboxylated multi-walled carbon nanotubes, aminated multi-walled carbon nanotubes, and nano-silica; the surfactant is selected from one or more of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, hexadecyltrimethylammonium bromide, and fatty alcohol polyoxyethylene ether.

3. A method for preparing the water-based thermoplastic sizing agent according to any one of claims 1 to 2, characterized in that, Includes the following steps: S1. Synthesis of the matrix resin: Under an inert atmosphere, bisphenol compounds, bisphenolic acids, and dihalogen compounds are dissolved in a polar aprotic solvent. A salt-forming agent and a dehydrating agent are added, and the dehydration reaction and polymerization reaction are carried out sequentially. After the reaction, the mixture is acidified, precipitated, washed, and dried to obtain a carboxyl-containing polyarylether ketone / sulfone copolymer; the dihalogen compound has the structure shown in Formula II: ； Wherein, R is independently selected from fluorine or chlorine; S2. Preparation of preliminary sizing agent: The matrix resin obtained in step S1 is dissolved in an organic solvent that is immiscible with water to obtain an oil phase resin solution; the surfactant is dissolved in deionized water to obtain an aqueous phase solution; the oil phase resin solution is added dropwise to the aqueous phase solution under stirring, and the organic solvent is removed after emulsification to obtain a preliminary water-based sizing agent; S3. Doping with nanomaterials: Nanomaterials are added to the preliminary aqueous sizing agent obtained in step S2, and after dispersion treatment, the aqueous thermoplastic sizing agent doped with nanomaterials is obtained.

4. The preparation method according to claim 3, characterized in that, In step S1, the bisphenol compound is selected from one or more of hydroquinone, biphenyl, bisphenol A, phenolphthalein, bisphenol fluorene, and N-phenylindolone; the molar ratio of the bisphenol compound to bisphenolic acid is 1:0.1 to 1; the molar ratio of the bisphenol compound to the dihalogen compound is 0.1 to 1:1; the salt-forming agent is potassium carbonate and / or sodium carbonate, and the molar ratio of the bisphenol compound to the salt-forming agent is 1:1 to 1.

5.

5. The preparation method according to claim 3, characterized in that, In step S1, the polar aprotic solvent is selected from at least one of sulfolane, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and N-methylpyrrolidone; the dehydrating agent is toluene and / or xylene; the temperature of the dehydration reaction is 140–160°C and the time is 2–3 h; the temperature of the polymerization reaction is 180–220°C and the time is 4–6 h.

6. The preparation method according to claim 3, characterized in that, In step S2, the water-immiscible organic solvent is selected from one of dichloromethane, trichloromethane, and 1,1-dichloroethane; the emulsification treatment is performed by ultrasonic shearing for 15 to 30 minutes.

7. The preparation method according to claim 3, characterized in that, In step S3, the dispersion process includes: first, ultrasonic dispersion at a power of 400-1000W for 15-30 minutes, and then stirring at a speed of 500-1500rpm for 2-4 hours.

8. The application of the aqueous thermoplastic sizing agent according to any one of claims 1 to 2 in the preparation of carbon fiber reinforced thermoplastic composite materials, characterized in that, Includes the following steps: (1) The carbon fiber fabric is immersed in the sizing agent for sizing treatment, and then dried to obtain the sized carbon fiber fabric. (2) The sized carbon fiber fabric and thermoplastic resin film are alternately stacked and hot-pressed to obtain a carbon fiber reinforced thermoplastic composite material.

9. The application according to claim 8, characterized in that, In step (1), the sizing treatment is performed for 1 to 2 hours, the drying temperature is 100 to 150°C, the drying time is 12 to 24 hours, and the sizing amount is controlled to be 1.0% to 5.0% of the carbon fiber fabric mass.

10. The application according to claim 8, characterized in that, In step (2), the thermoplastic resin film is a phenolphthalein polyetherketone film; the hot pressing conditions are: temperature 320~380℃, pressure 5~10MPa, time 30~60min.

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