An aqueous carbon fiber sizing agent, a preparation method and application thereof

Abstract

This invention discloses an aqueous carbon fiber sizing agent, its preparation method, and its application, belonging to the field of sizing agent technology. The aqueous carbon fiber sizing agent comprises a copolymer, modified Mxene, and water; the copolymer is an acrylate monomer-chlorinated polypropylene graft copolymer; the modified Mxene is polydopamine-modified Mxene; the mass ratio of chlorinated polypropylene, acrylate monomer, and polydopamine-modified Mxene in the copolymer is 1:(1-2):(0.005-0.05). The polydopamine-modified Mxene in the aqueous carbon fiber sizing agent of this invention has good compatibility with the resin matrix, improving its dispersibility in the resin matrix.

Description

Technical Field

[0001] This invention relates to the field of sizing agents, specifically to an aqueous carbon fiber sizing agent, its preparation method, and its application. Background Technology

[0002] The most significant challenge for new energy vehicles today is improving driving range. The industry is addressing this issue in two main directions: first, maximizing battery capacity within limited space; and second, given the current limitations of battery capacity, reducing vehicle weight to increase driving range. Therefore, exploring lightweight automotive technologies is crucial, and expanding the application of carbon fiber composite materials in automotive components has become a key focus of the automotive lightweighting industry.

[0003] With the continuous improvement of carbon fiber quality and the expanding application range, the industry is placing higher and more demanding requirements on the performance of carbon fiber composites. Carbon fiber reinforced polypropylene (PP / CF) composites have advantages such as lightweight and high strength, and have great application prospects in automotive lightweighting and civilian fields. Although PP / CF composites have significant advantages, the impact toughness of chopped carbon fiber reinforced polypropylene (PP / SCF) composites is relatively low, especially its low-temperature impact toughness, which limits its practical application. Taking effective measures to improve the impact strength of PP / CF is a meaningful research topic. The main factor affecting the mechanical properties of PP / CF composites is the interfacial interaction between PP and CF, and the sizing process is particularly important for the interfacial properties of carbon fiber and matrix. Therefore, the sizing process is developing rapidly, and the classification of sizing agents is becoming increasingly diverse to meet modern, diversified, and environmentally friendly requirements.

[0004] CN113463393A discloses a water-based modified chlorinated polypropylene sizing agent suitable for carbon fibers, its preparation method, and its application. This agent improves the thermal stability of the modified resin by grafting acrylic acid monomers onto chlorinated polypropylene, replacing the chlorine content. Since the modified resin has a similar structure to chlorinated polypropylene, it is soluble in organic solvents. The water-based sizing agent is obtained through an emulsion solvent evaporation method, effectively improving the interfacial properties of carbon fiber / polypropylene composites. However, it does not contain nanoparticles, and due to the presence of emulsifiers, it suffers from poor compatibility between the emulsifier and carbon fibers and polypropylene, as well as poor thermal stability, thus limiting its application.

[0005] Therefore, the development of an aqueous sizing agent system that does not contain emulsifiers remains an urgent task. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a water-based carbon fiber sizing agent, its preparation method and application, which can effectively enhance the interfacial strength between polypropylene and carbon fiber, thereby improving the tensile strength, flexural strength and impact strength of the composite material.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A water-based carbon fiber sizing agent comprises a copolymer, modified Mxene, and water;

[0009] The copolymer is an acrylate monomer-chlorinated polypropylene graft copolymer; the modified Mxene is polydopamine-modified Mxene;

[0010] The mass ratio of chlorinated polypropylene, acrylate monomer and polydopamine-modified Mxene in the copolymer is 1:(1-2):(0.005-0.05).

[0011] The water-based carbon fiber sizing agent of the present invention contains acrylate monomer-chlorinated polypropylene graft copolymer, polydopamine-modified Mxene and water. The acrylate monomer-chlorinated polypropylene graft copolymer can partially adsorb, partially coat and partially graft onto the surface of polydopamine-modified Mxene, which effectively improves the compatibility of polydopamine-modified Mxene with the resin matrix and improves its dispersibility in the resin matrix.

[0012] The water-based carbon fiber sizing agent of the present invention does not contain emulsifiers, which can solve the problems of poor compatibility and poor heat resistance of emulsifiers with carbon fibers and polypropylene. It also significantly improves the surface roughness and chemical activity of carbon fibers and strengthens the interaction between carbon fibers and polypropylene matrix.

[0013] The water-based carbon fiber sizing agent can effectively enhance the interfacial strength between polypropylene and carbon fiber, increase the carbon fiber content in polypropylene carbon fiber composites, thereby improving the tensile strength, flexural strength and impact strength of the composites, reducing the processing temperature of the composites, and thus reducing production costs and saving energy.

[0014] Preferably, the Mxene includes at least one of Ti3C2, V2C, Ti2C, Nb2C, Ti3C2Tx, V2CTx, and Nb2CTx.

[0015] Preferably, the chlorinated polypropylene resin has a chlorine content of 20% to 30 wt%, for example, it can be 20 wt%, 21 wt%, 22 wt%, 24.5 wt%, 25 wt%, 28 wt%, 29.5 wt%, 30 wt%, or any two of these values.

[0016] The inventors of this invention investigated the effect of chlorine content on the effect and found that when the chlorine content is controlled within this range, the chlorine on chlorinated polypropylene can be effectively replaced by acrylate monomers. However, if the chlorine content is too low, the content of free acrylate monomers will be too high, and if the chlorine content is too high, it cannot be effectively replaced. Therefore, it is necessary to control the chlorine content between 20% and 30 wt%.

[0017] Preferably, the mass ratio of the total mass of chlorinated polypropylene, acrylate monomers and water in the copolymer is (0.1 to 0.3):1, for example, it can be 0.1:1, 0.15:1, 0.18:1, 0.2:1, 0.22:1, 0.25:1, 0.28:1, 0.3:1 or any two of these values.

[0018] Preferably, the acrylate monomers include butyl acrylate, methyl methacrylate, and acrylic acid, wherein the molar ratio of butyl acrylate, methyl methacrylate, and acrylic acid is (1-2):(1-2):1.

[0019] Preferably, the preparation method of the polydopamine-modified Mxene is as follows: add dopamine hydrochloride to an aqueous solution of Mxene, adjust the pH to 8-9 with tris(hydroxymethyl)aminomethane hydrochloride buffer, react, filter, and dry to obtain polydopamine-modified Mxene;

[0020] In the preparation method of polydopamine-modified Mxene, the mass ratio of dopamine hydrochloride to Mxene is 1:(0.8-1.5), for example, it can be 1:0.8, 1:1, 1:1.2, 1:1.5, or any two of these values. This invention creatively synthesizes polydopamine-modified Mxene using dopamine hydrochloride and tris(hydroxymethyl)aminomethane hydrochloride buffer. By modifying Mxene with polydopamine, the compatibility and dispersibility of Mxene in the system are improved, preventing agglomeration. Simultaneously, it allows for better adsorption, coating, and grafting by the acrylate monomer-chlorinated polypropylene graft copolymer, thereby further improving the interfacial strength between polypropylene and carbon fiber, increasing the carbon fiber content in the polypropylene-carbon fiber composite material, and further improving the tensile strength, flexural strength, and impact strength of the composite material.

[0021] For example, the mass concentration of the Mxene aqueous solution is 1 mg / mL to 10 mg / mL, such as 1 mg / mL, 2 mg / mL, 4 mg / mL, 5 mg / mL, 6 mg / mL, 8 mg / mL, 10 mg / mL or any two of these values.

[0022] For example, the hydrochloric acid tris(hydroxymethyl)aminomethane buffer is a buffer solution formulated with hydrochloric acid and tris(hydroxymethyl)aminomethane, which is a conventional commercially available product.

[0023] For example, the reaction temperature is 40–60°C and the reaction time is 5–20 h.

[0024] This invention also provides a method for preparing an aqueous carbon fiber sizing agent, comprising the following steps:

[0025] Chlorinated polypropylene and organic solvent are stirred evenly to obtain a chlorinated polypropylene mixture solution;

[0026] The acrylate monomer, initiator, polydopamine-modified Mxene and water are mixed evenly and then dropped into a chlorinated polypropylene mixture solution. After reaction, the mixture is allowed to stand and separate into layers. The aqueous layer is then collected to obtain the water-based carbon fiber sizing agent.

[0027] Since chlorinated polypropylene is insoluble in water, this invention creatively dissolves it first in an organic solvent, and then drips a mixture of acrylate monomer, initiator, polydopamine-modified Mxene, and water into the chlorinated polypropylene mixture solution. During the dripping process, the acrylate monomer and chlorinated polypropylene react in the presence of the initiator to obtain an acrylate monomer-chlorinated polypropylene graft copolymer. The acrylate monomer-chlorinated polypropylene graft copolymer migrates from the organic layer to the water layer, and then adsorbs, coats, and grafts onto the surface of the polydopamine-modified Mxene. After the reaction is completed, the mixture is allowed to stand and separate into layers. The water layer is then taken to obtain the water-based carbon fiber sizing agent of this invention.

[0028] For example, the reaction time is 50–70°C and the reaction temperature is 1–4 hours.

[0029] For example, the initiator is a conventional initiator in the art, such as at least one of dicumyl peroxide, ammonium persulfate, potassium persulfate, benzoyl peroxide, and azobisisobutyronitrile.

[0030] For example, the mass ratio of the initiator to the acrylic monomer is (0.005 to 0.02):1, such as 0.005:1, 0.008:1, 0.01:1, 0.015:1, 0.02:1, or any two of these values.

[0031] Preferably, the mass ratio of the chlorinated polypropylene, acrylate monomer, and polydopamine-modified Mxene is 1:(1-2):(0.005-0.05).

[0032] Preferably, the mass ratio of the total mass of the chlorinated polypropylene, the acrylate monomer, and the water is (0.1 to 0.3):1.

[0033] Preferably, the mass ratio of the chlorinated polypropylene to the organic solvent is (1-2):10, for example, it can be 1:10, 1.2:10, 1.5:10, 1.8:10, 2:10 or any two of these values.

[0034] Preferably, the Mxene includes at least one of Ti3C2, V2C, Ti2C, Nb2C, Ti3C2Tx, V2CTx, and Nb2CTx.

[0035] The chlorinated polypropylene resin has a chlorine content of 20% to 30 wt%, for example, it can be 20 wt%, 21 wt%, 22 wt%, 24.5 wt%, 25 wt%, 28 wt%, 29.5 wt%, 30 wt%, or any two of these values.

[0036] The acrylate monomers include butyl acrylate, methyl methacrylate, and acrylic acid, and the molar ratio of butyl acrylate, methyl methacrylate, and acrylic acid is (1-2):(1-2):1.

[0037] The organic solvent is a conventional organic solvent that is insoluble in water, such as at least one of toluene, xylene, chloroform, and dichloromethane.

[0038] Preferably, the preparation method of the polydopamine-modified Mxene is as follows: add dopamine hydrochloride to an aqueous solution of Mxene, adjust the pH to 8-9 with tris(hydroxymethyl)aminomethane hydrochloride buffer, react, filter, and dry to obtain polydopamine-modified Mxene;

[0039] The mass ratio of dopamine hydrochloride to Mxene is 1:(0.8-1.5), for example, it can be 1:0.8, 1:1, 1:1.2, 1:1.5, or any two of these values. This invention also provides the application of the above-described aqueous carbon fiber sizing agent in the preparation of carbon fibers.

[0040] The present invention also provides a method for preparing carbon fiber, comprising the following steps: immersing unsized carbon fiber in an aqueous carbon fiber sizing agent, shaking, filtering, and drying to obtain carbon fiber;

[0041] The water-based carbon fiber sizing agent is the water-based carbon fiber sizing agent described above.

[0042] During soaking, the mass ratio of the unsized carbon fiber to the water-based carbon fiber sizing agent is 1:(50-200), for example, it can be 1:50, 1:60, 1:80, 1:100, 1:120, 1:150, 1:180, 1:200 or any two of these values.

[0043] When using the water-based carbon fiber sizing agent of the present invention to modify the surface of carbon fiber, only simple oscillation is required. During the oscillation process, the acrylate monomer-chlorinated polypropylene graft copolymer and polydopamine-modified Mxene are adsorbed on the carbon fiber surface, thus completing the modification. Compared with the existing technology, it is simpler and can save costs more effectively, and has broad application prospects.

[0044] The present invention also provides a polypropylene composite material comprising carbon fiber and polypropylene, wherein the mass ratio of the carbon fiber and polypropylene is (5-20):(80-95), for example, it can be 5:95, 10:90, 15:85, 20:80 or any two of these values.

[0045] The carbon fiber is prepared by the preparation method described above.

[0046] Preferably, the melt flow rate of the polypropylene at 230℃ / 2.16kg is 2-30g / 10min, and the test standard is ISO1133-2011.

[0047] The polypropylene carbon fiber composite material of the present invention, by adding sized carbon fibers, can simultaneously possess excellent mechanical properties, low high-temperature creep, high thermal stability, good dimensional accuracy, wear resistance, and good colorability. It can be widely used in lightweight materials and has broad application prospects in the fields of power, machinery, automobiles, and aerospace.

[0048] This invention also provides an application of polypropylene composite material in the preparation of automotive parts, electronic appliances, industrial machinery and aerospace components.

[0049] The beneficial effects of the present invention are as follows: (1) The water-based carbon fiber sizing agent of the present invention contains acrylate monomer-chlorinated polypropylene graft copolymer, polydopamine-modified Mxene and water, wherein the acrylate monomer-chlorinated polypropylene graft copolymer is partially adsorbed, partially coated and partially grafted on the surface of polydopamine-modified Mxene, which effectively improves the compatibility of polydopamine-modified Mxene with the resin matrix and improves its dispersibility in the resin matrix. (2) The water-based carbon fiber sizing agent of the present invention does not contain emulsifier, which can solve the problems of poor compatibility and poor heat resistance of emulsifier with carbon fiber and polypropylene, and also significantly improves the surface roughness and chemical activity of carbon fiber, and strengthens the interaction between carbon fiber and polypropylene matrix. (3) The water-based carbon fiber sizing agent can effectively enhance the interfacial strength between polypropylene and carbon fiber, and improve the tensile strength, flexural strength and impact strength of composite materials. Detailed Implementation

[0050] To better illustrate the purpose, technical solution, and advantages of this invention, the invention will be further described below with reference to specific embodiments and comparative examples. The purpose of this description is to provide a detailed understanding of the invention, not to limit its scope. All other embodiments obtained by those skilled in the art without inventive effort are within the protection scope of this invention.

[0051] The raw materials used in the examples and comparative examples are described below:

[0052] Tris(hydroxymethyl)aminomethane hydrochloride buffer: purchased from Maclean's Reagents, product model T6044.

[0053] Chlorinated polypropylene-1: chlorine content is 24.5 wt%, purchased from Nippon Paper Corporation, product model 1122S.

[0054] Chlorinated polypropylene-2: chlorine content is 21 wt%, purchased from Nippon Paper Corporation, product model 930S.

[0055] Chlorinated polypropylene-3: chlorine content is 29.5 wt%, purchased from Nippon Paper Corporation, product model number 803MWS.

[0056] Chlorinated polypropylene-4: chlorine content is 15wt%, purchased from Nippon Paper Corporation, product model 204HS.

[0057] Chlorinated polypropylene-5: chlorine content is 32.5 wt%, purchased from Nippon Paper Corporation, product model 833S.

[0058] Polypropylene: Purchased from Sinopec, product model HP500N.

[0059] Unless otherwise specified, all components and raw materials used in the embodiments and comparative examples of this invention are commercially available, and the same type of components and raw materials are used in each parallel experiment.

[0060] Example 1

[0061] A method for preparing a polypropylene carbon fiber composite material includes the following steps:

[0062] (1) Add 1.0 g of dopamine hydrochloride to 1 L of Ti3C2 aqueous dispersion at 1 mg / mL and mix well. Then adjust the pH of the solution to 8.5 with tris(hydroxymethyl)aminomethane hydrochloride buffer solution and react at 60 °C for 8 h. After the reaction is completed, filter and dry to obtain polydopamine modified Ti3C2.

[0063] (2) Dissolve 10g of chlorinated polypropylene-1 and 100g of toluene at 50°C by stirring to obtain a chlorinated polypropylene solution. Mix 10g of acrylate monomer (4.27g of butyl acrylate, 3.33g of methyl methacrylate and 2.40g of acrylic acid), 0.05g of ammonium persulfate, 0.05g of polydopamine-modified Ti3C2 and 100g of water thoroughly and add them dropwise to the above chlorinated polypropylene solution. The dropwise addition time is 0.5h. After the dropwise addition is completed, continue to stir the reaction at 50°C for 4h. After the reaction is completed, cool to room temperature and separate into layers. Take the water layer to obtain the water-based carbon fiber sizing agent.

[0064] (3) Immerse the unsized carbon fiber in water-based carbon fiber sizing agent, shake and adsorb at room temperature in a constant temperature shaker for 10 minutes, take it out, dry it, and obtain carbon fiber. The mass ratio of the unsized carbon fiber to the water-based carbon fiber sizing agent is 1:50.

[0065] (4) The carbon fiber and polypropylene from step (3) are extruded and granulated by a twin-screw extruder to obtain a polypropylene carbon fiber composite material; wherein the temperature of each extrusion granulation section is 180-220℃ and the mass ratio of carbon fiber to polypropylene is 5:95.

[0066] Example 2

[0067] A method for preparing a polypropylene carbon fiber composite material includes the following steps:

[0068] (1) Add 1.5g of dopamine hydrochloride to 1L of Ti3C2 aqueous dispersion and mix well. Then adjust the pH of the solution to 8.5 with tris(hydroxymethyl)aminomethane hydrochloride buffer solution and react at 40℃ for 12h. After the reaction is completed, filter and dry to obtain polydopamine modified Ti3C2.

[0069] (2) Dissolve 10g of chlorinated polypropylene-1 and 100g of xylene at 50°C to obtain a chlorinated polypropylene solution. Mix 20g of acrylate monomer (11.96g of butyl acrylate, 4.68g of methyl methacrylate and 3.36g of acrylic acid), 0.2g of ammonium persulfate, 0.1g of polydopamine-modified Ti3C2 and 100g of water thoroughly and add them dropwise to the above chlorinated polypropylene solution. The dropwise addition time is 0.5h. After the dropwise addition is completed, continue to stir the reaction at 50°C for 4h. After the reaction is completed, cool to room temperature and separate into layers. Take the water layer to obtain the water-based carbon fiber sizing agent.

[0070] (3) Immerse the unsized carbon fiber in water-based carbon fiber sizing agent, shake and adsorb at room temperature in a constant temperature shaker for 30 minutes, take it out, dry it, and obtain carbon fiber. The mass ratio of the unsized carbon fiber to the water-based carbon fiber sizing agent is 1:200.

[0071] (4) The carbon fiber and polypropylene from step (3) are extruded and granulated by a twin-screw extruder to obtain a polypropylene carbon fiber composite material; wherein the temperature of each section of the extrusion granulation is 180 to 220°C and the mass ratio of carbon fiber to polypropylene is 10:90.

[0072] Example 3

[0073] A method for preparing a polypropylene carbon fiber composite material includes the following steps:

[0074] (1) Add 5g of dopamine hydrochloride to 1L of Ti3C2 aqueous dispersion and mix well. Then adjust the pH of the solution to 8.5 with tris(hydroxymethyl)aminomethane hydrochloride buffer solution and react at 60℃ for 8h. After the reaction is completed, filter and dry to obtain polydopamine modified Ti3C2.

[0075] (2) Dissolve 10g of chlorinated polypropylene-2 ​​and 50g of toluene at 60°C to obtain a chlorinated polypropylene solution. Mix 15g of acrylate monomer (7.27g of butyl acrylate, 5.68g of methyl methacrylate and 2.05g of acrylic acid), 0.3g of ammonium persulfate, 0.15g of polydopamine-modified Mxene and 100g of water thoroughly and add them dropwise to the above chlorinated polypropylene solution. The dropwise addition time is 0.5h. After the dropwise addition is completed, continue to stir the reaction at 50°C for 4h. After the reaction is completed, cool to room temperature and separate into layers. Take the water layer to obtain the water-based carbon fiber sizing agent.

[0076] (3) Immerse the unsized carbon fiber in water-based carbon fiber sizing agent, shake and adsorb at room temperature in a constant temperature shaker for 30 minutes, take it out, dry it, and obtain carbon fiber. The mass ratio of the unsized carbon fiber to the water-based carbon fiber sizing agent is 1:200.

[0077] (4) The carbon fiber and polypropylene from step (3) are extruded and granulated by a twin-screw extruder to obtain a polypropylene carbon fiber composite material; wherein the temperature of each section of the extrusion granulation is 180-220℃ and the mass ratio of carbon fiber to polypropylene is 15:85.

[0078] Example 4

[0079] A method for preparing a polypropylene carbon fiber composite material includes the following steps:

[0080] (1) Add 6g of dopamine hydrochloride to 1L of Ti3C2 aqueous dispersion and mix well. Then adjust the pH of the solution to 8.5 with tris(hydroxymethyl)aminomethane hydrochloride buffer solution and react at 60℃ for 8h. After the reaction is completed, filter and dry to obtain polydopamine modified Ti3C2.

[0081] (2) Dissolve 10g of chlorinated polypropylene-2 ​​and 50g of xylene at 70°C to obtain a chlorinated polypropylene solution. Mix 10g of acrylate monomer (3.20g of butyl acrylate, 5.00g of methyl methacrylate and 1.80g of acrylic acid), 0.15g of ammonium persulfate, 0.2g of polydopamine-modified Ti3C2 and 100g of water thoroughly and add them dropwise to the above chlorinated polypropylene solution. The dropwise addition time is 0.5h. After the dropwise addition is completed, continue to stir the reaction at 70°C for 4h. After the reaction is completed, cool to room temperature and separate into layers. Take the water layer to obtain the water-based carbon fiber sizing agent.

[0082] (3) Immerse the unsized carbon fiber in water-based carbon fiber sizing agent, shake and adsorb at room temperature in a constant temperature shaker for 30 minutes, take it out, dry it, and obtain carbon fiber. The mass ratio of the unsized carbon fiber to the water-based carbon fiber sizing agent is 1:100.

[0083] (4) The carbon fiber and polypropylene from step (3) are extruded and granulated by a twin-screw extruder to obtain a polypropylene carbon fiber composite material; wherein the temperature of each section of the extrusion granulation is 180 to 220°C and the mass ratio of carbon fiber to polypropylene is 20:80.

[0084] Example 5

[0085] A method for preparing a polypropylene carbon fiber composite material includes the following steps:

[0086] (1) Add 12g of dopamine hydrochloride to 1L of Ti3C2 aqueous dispersion and mix well. Then adjust the pH of the solution to 8.5 with tris(hydroxymethyl)aminomethane hydrochloride buffer solution and react at 60℃ for 8h. After the reaction is completed, filter and dry to obtain polydopamine modified Ti3C2.

[0087] (2) Dissolve 10g of chlorinated polypropylene-3 and 50g of xylene by stirring at 60℃ to obtain a chlorinated polypropylene solution. Mix 10g of acrylate monomer (3.20g of butyl acrylate, 5.00g of methyl methacrylate and 1.80g of acrylic acid), 0.2g of ammonium persulfate, 0.5g of polydopamine-modified Ti3C2 and 100g of water thoroughly and add them dropwise to the above chlorinated polypropylene solution. The dropwise addition time is 0.5h. After the dropwise addition is completed, continue to stir the reaction at 70℃ for 4h. After the reaction is completed, cool to room temperature and separate into layers. Take the water layer to obtain the water-based carbon fiber sizing agent.

[0088] (3) Immerse the unsized carbon fiber in water-based carbon fiber sizing agent, shake and adsorb at room temperature in a constant temperature shaker for 30 minutes, take it out, dry it, and obtain carbon fiber. The mass ratio of the unsized carbon fiber to the water-based carbon fiber sizing agent is 1:100.

[0089] (4) The carbon fiber and polypropylene from step (3) are extruded and granulated by a twin-screw extruder to obtain a polypropylene carbon fiber composite material; wherein the temperature of each section of the extrusion granulation is 180 to 220°C and the mass ratio of carbon fiber to polypropylene is 20:80.

[0090] Example 6

[0091] The difference between Example 6 and Example 2 is that Example 6 uses an equal amount of Ti2C to replace Ti3C2, while everything else is the same.

[0092] Comparative Example 1

[0093] The difference between Comparative Example 1 and Example 2 is that Comparative Example 1 does not contain polydopamine-modified Ti3C2, but all other aspects are the same.

[0094] A method for preparing a polypropylene carbon fiber composite material includes the following steps:

[0095] (1) Dissolve 10g of chlorinated polypropylene-1 and 100g of xylene at 50°C to obtain a chlorinated polypropylene solution. Mix 20g of acrylate monomer (11.96g of butyl acrylate, 4.68g of methyl methacrylate and 3.36g of acrylic acid), 0.2g of ammonium persulfate and 100g of water thoroughly and add them dropwise to the above chlorinated polypropylene solution. The dropwise addition time is 0.5h. After the dropwise addition is completed, continue to stir the reaction at 50°C for 4h. After the reaction is completed, cool to room temperature and separate into layers. Take the water layer to obtain the water-based carbon fiber sizing agent.

[0096] (3) Immerse the unsized carbon fiber in water-based carbon fiber sizing agent, shake and adsorb at room temperature in a constant temperature shaker for 30 minutes, take it out, dry it, and obtain carbon fiber. The mass ratio of the unsized carbon fiber to the water-based carbon fiber sizing agent is 1:200.

[0097] (4) The carbon fiber and polypropylene from step (3) are extruded and granulated by a twin-screw extruder to obtain a polypropylene carbon fiber composite material; wherein the temperature of each section of the extrusion granulation is 180 to 220°C and the mass ratio of carbon fiber to polypropylene is 10:90.

[0098] Comparative Example 2

[0099] The difference between Comparative Example 2 and Example 2 is that Comparative Example 2 uses an equal amount of Ti3C2 to replace the polydopamine-modified Ti3C2, while everything else is the same. That is, this comparative example does not contain step (1) of Example 2, and replaces the polydopamine-modified Ti3C2 in step (2) with Ti3C2.

[0100] Comparative Example 3

[0101] The difference between Comparative Example 3 and Example 2 is that Comparative Example 3 uses unsized carbon fiber instead of the carbon fiber in Example 2, but everything else is the same.

[0102] A method for preparing a polypropylene carbon fiber composite material includes the following steps:

[0103] Unsized carbon fibers and polypropylene are extruded and granulated using a twin-screw extruder to obtain a polypropylene carbon fiber composite material; wherein the temperature of each stage of extrusion granulation is 180-220℃, and the mass ratio of carbon fiber to polypropylene is 10:90.

[0104] Comparative Example 4

[0105] The difference between Comparative Example 4 and Example 2 is that Comparative Example 4 uses an equal amount of chlorinated polypropylene-4 to replace chlorinated polypropylene-1, while everything else is the same.

[0106] Comparative Example 5

[0107] The difference between Comparative Example 5 and Example 2 is that Comparative Example 5 uses an equal amount of chlorinated polypropylene-5 to replace chlorinated polypropylene-1, while everything else is the same.

[0108] Comparative Example 6

[0109] The difference between Comparative Example 6 and Example 2 is that the mass ratio of chlorinated polypropylene, acrylate monomer, and polydopamine-modified Mxene is different. That is, only step (2) of the comparative example is different from that of Example 2, while everything else is the same.

[0110] A method for preparing a polypropylene carbon fiber composite material includes the following steps:

[0111] (1) Add 1.5g of dopamine hydrochloride to 1L of Ti3C2 aqueous dispersion and mix well. Then adjust the pH of the solution to 8.5 with tris(hydroxymethyl)aminomethane hydrochloride buffer solution and react at 40℃ for 12h. After the reaction is completed, filter and dry to obtain polydopamine modified Ti3C2.

[0112] (2) Dissolve 10g of chlorinated polypropylene-1 and 100g of xylene at 50°C to obtain a chlorinated polypropylene solution. Mix 5g of acrylate monomer (2.99g of butyl acrylate, 1.17g of methyl methacrylate and 0.84g of acrylic acid), 0.05g of ammonium persulfate, 1g of polydopamine-modified Ti3C2 and 100g of water thoroughly and add them dropwise to the above chlorinated polypropylene solution. The dropwise addition time is 0.5h. After the dropwise addition is completed, continue to stir the reaction at 50°C for 4h. After the reaction is completed, cool to room temperature and separate into layers. Take the water layer to obtain the water-based carbon fiber sizing agent.

[0113] (3) Immerse the unsized carbon fiber in water-based carbon fiber sizing agent, shake and adsorb at room temperature in a constant temperature shaker for 30 minutes, take it out, dry it, and obtain carbon fiber. The mass ratio of the unsized carbon fiber to the water-based carbon fiber sizing agent is 1:200.

[0114] (4) The carbon fiber and polypropylene from step (3) are extruded and granulated by a twin-screw extruder to obtain a polypropylene carbon fiber composite material; wherein the temperature of each section of the extrusion granulation is 180 to 220°C and the mass ratio of carbon fiber to polypropylene is 10:90.

[0115] Comparative Example 7

[0116] The difference between Comparative Example 7 and Example 2 is that the mass ratio of chlorinated polypropylene, acrylate monomer, and polydopamine-modified Mxene is different, while all other aspects are the same.

[0117] A method for preparing a polypropylene carbon fiber composite material includes the following steps:

[0118] (1) Add 1.5g of dopamine hydrochloride to 1L of Ti3C2 aqueous dispersion and mix well. Then adjust the pH of the solution to 8.5 with tris(hydroxymethyl)aminomethane hydrochloride buffer solution and react at 40℃ for 12h. After the reaction is completed, filter and dry to obtain polydopamine modified Ti3C2.

[0119] (2) Dissolve 10g of chlorinated polypropylene-1 and 100g of xylene at 50°C to obtain a chlorinated polypropylene solution. Mix 40g of acrylate monomer (23.92g of butyl acrylate, 9.36g of methyl methacrylate and 6.72g of acrylic acid), 0.4g of ammonium persulfate, 0.04g of polydopamine-modified Ti3C2 and 100g of water thoroughly and add them dropwise to the above chlorinated polypropylene solution. The dropwise addition time is 0.5h. After the dropwise addition is completed, continue to stir the reaction at 50°C for 4h. After the reaction is completed, cool to room temperature and separate into layers. Take the water layer to obtain the water-based carbon fiber sizing agent.

[0120] (3) Immerse the unsized carbon fiber in water-based carbon fiber sizing agent, shake and adsorb at room temperature in a constant temperature shaker for 30 minutes, take it out, dry it, and obtain carbon fiber. The mass ratio of the unsized carbon fiber to the water-based carbon fiber sizing agent is 1:200.

[0121] (4) The carbon fiber and polypropylene from step (3) are extruded and granulated by a twin-screw extruder to obtain a polypropylene carbon fiber composite material; wherein the temperature of each section of the extrusion granulation is 180 to 220°C and the mass ratio of carbon fiber to polypropylene is 10:90.

[0122] Performance testing

[0123] Standard specimens for testing the mechanical properties of the polypropylene composites from the examples and comparative examples were prepared using an injection molding machine. Tensile strength was tested according to ISO 527-2012 (1A specimen, test rate 10 mm / min); flexural strength was tested according to ISO 178-2019; and cantilever beam notched impact strength was tested according to ISO 180-2019, with a notch depth of 2 mm and an impact load of 2.75 J. The results are shown in Table 1.

[0124] Table 1

[0125]

[0126]

[0127] As shown in Table 1, the carbon fibers sized with the sizing agent described in this invention can effectively enhance the interfacial strength between polypropylene and carbon fibers, and improve the tensile strength, flexural strength, and impact strength of the composite material. The polypropylene composite material composed of carbon fibers sized with the sizing agent described in this invention and polypropylene has a tensile strength greater than 41 MPa, a flexural strength greater than 60 MPa, and a notched impact strength greater than 15 kJ / m. 2 .

[0128] Comparing Example 1 with Comparative Examples 1 and 2, it can be seen that the present invention further improves the tensile strength, flexural strength and impact strength of the composite material by adding polydopamine-modified Mxene. Moreover, compared with the direct addition of Mxene, polydopamine-modified Mxene can significantly improve the tensile strength, flexural strength and impact strength.

[0129] Comparing Example 1 with Comparative Examples 4-5, it can be seen that the present invention further improves tensile strength, flexural strength and impact strength by controlling the chlorine content of chlorinated polypropylene fiber between 20% and 30 wt%.

[0130] Comparing Example 1 with Comparative Examples 6-7, it can be seen that by controlling the mass ratio of chlorinated polypropylene, acrylate monomer, and polydopamine-modified Mxene to 1:(1-2):(0.005-0.05), the tensile strength, flexural strength, and impact strength are further improved.

[0131] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A water-based carbon fiber sizing agent, characterized in that, Includes copolymers, modified Mxene, and water; The copolymer is an acrylate monomer-chlorinated polypropylene graft copolymer; the modified Mxene is polydopamine-modified Mxene; The mass ratio of chlorinated polypropylene, acrylate monomer, and polydopamine-modified Mxene in the copolymer is 1:(1~2):(0.005~0.05); the chlorine content of the chlorinated polypropylene resin is 20%~30wt%. The Mxene includes at least one of Ti3C2, V2C, Ti2C, Nb2C, Ti3C2Tx, V2CTx, and Nb2CTx; The acrylate monomers include butyl acrylate, methyl methacrylate, and acrylic acid, wherein the molar ratio of butyl acrylate, methyl methacrylate, and acrylic acid is (1~2):(1~2):1; The total mass ratio of chlorinated polypropylene, acrylate monomers, and water in the copolymer is (0.1~0.3):1; The preparation method of the polydopamine-modified Mxene is as follows: add dopamine hydrochloride to Mxene aqueous solution, adjust the pH to 8-9 with tris(hydroxymethyl)aminomethane hydrochloride buffer, react, filter, and dry to obtain polydopamine-modified Mxene. The mass ratio of dopamine hydrochloride to Mxene is 1:(0.8~1.5).

2. The method for preparing the water-based carbon fiber sizing agent according to claim 1, characterized in that, Includes the following steps: Chlorinated polypropylene and organic solvent are stirred evenly to obtain a chlorinated polypropylene mixture solution; The acrylate monomer, initiator, polydopamine-modified Mxene and water are mixed evenly and then dropped into a chlorinated polypropylene mixture solution. After reaction, the mixture is allowed to stand and separate into layers. The aqueous layer is then collected to obtain the water-based carbon fiber sizing agent.

3. The method for preparing the aqueous carbon fiber sizing agent according to claim 2, characterized in that, The mass ratio of the chlorinated polypropylene to the organic solvent is (1-2):10; and / or The organic solvent includes at least one of toluene, xylene, chloroform, and dichloromethane.

4. The application of the water-based carbon fiber sizing agent according to claim 1 in the preparation of carbon fiber.

5. A method for preparing carbon fiber, characterized in that, Includes the following steps: Unsized carbon fibers are immersed in an aqueous carbon fiber sizing agent, shaken, filtered, and dried to obtain carbon fibers. The aqueous carbon fiber sizing agent is the aqueous carbon fiber sizing agent according to claim 1.

6. A polypropylene composite material, characterized in that, It includes carbon fiber and polypropylene, wherein the mass ratio of the carbon fiber to the polypropylene is (5~20):(80~95); The carbon fiber is prepared using the preparation method described in claim 5.

7. The application of the polypropylene composite material according to claim 6 in the preparation of automotive parts, electronic appliances, industrial machinery and equipment, and aerospace components.

Images