A sizing agent and a preparation method thereof, carbon fibers and composite materials

Abstract

This application provides a sizing agent and its preparation method, carbon fiber, and composite materials, belonging to the technical field of carbon fiber sizing agents. The sizing agent is in emulsion form and includes a main sizing agent and water. The main sizing agent comprises the following components by weight: 80-120 parts of phenolic epoxy resin, 100-150 parts of epoxy vinyl resin, and 10-20 parts of surfactant. By simultaneously adding phenolic epoxy resin and epoxy vinyl resin to the sizing agent, this application improves the heat resistance and wear resistance of the sizing agent-treated carbon fiber through the synergistic effect of the two resins, making it suitable for use in high-temperature environments. Furthermore, the sizing agent-treated carbon fiber exhibits strong interfacial bonding strength with thermosetting matrix resins such as epoxy resin, phenolic resin, and vinyl resin, demonstrating strong versatility. The sizing agent also exhibits good stability and good wettability to carbon fiber, resulting in a wide range of applications.

Description

Technical Field

[0001] This application relates to the field of carbon fiber sizing agents, and more specifically, to a sizing agent and its preparation method, carbon fiber, and composite materials. Background Technology

[0002] Carbon fiber reinforced resin matrix composites possess a variety of excellent physical and mechanical properties, such as lightweight, high strength, and electrical conductivity. They are widely used in the aerospace industry and various mechanical industries, and can significantly replace traditional metal materials as primary and secondary load-bearing structural components, thereby improving the working efficiency and application range of aerospace vehicles.

[0003] Sizing agents play an important role in the production and processing of carbon fibers. They can protect the fiber surface and introduce an appropriate interface layer between the carbon fiber and the matrix resin, so that the matrix resin and the fiber can be better bonded and the interface properties of the composite material formed by carbon fiber and matrix resin can be improved.

[0004] However, the existing sizing agents have poor heat resistance and wear resistance of carbon fibers, and the interfacial bonding strength of composite materials formed between carbon fibers treated with existing sizing agents and thermosetting matrix resins such as phenolic resin and vinyl resin is weak, which affects the application range of carbon fibers. Summary of the Invention

[0005] The purpose of this application is to provide a sizing agent and its preparation method, carbon fiber and composite material, which aims to improve the technical problems of poor heat resistance and wear resistance of carbon fibers treated with existing sizing agents, as well as the weak interfacial bonding strength of composite materials formed by carbon fibers and thermosetting matrix resins such as phenolic resin and vinyl resin.

[0006] In a first aspect, this application provides a sizing agent, which is an emulsion and includes a main sizing agent and water. The main sizing agent includes the following components by weight: 80-120 parts of phenolic epoxy resin, 100-150 parts of epoxy vinyl resin, and 10-20 parts of surfactant.

[0007] This application improves the heat resistance and abrasion resistance of sizing agents by simultaneously adding phenolic epoxy resin and epoxy vinyl resin. The synergistic effect of these two resins enhances the properties of the sizing-treated carbon fibers, making them suitable for high-temperature environments. Furthermore, the addition of both resins strengthens the interfacial bonding between the sizing-treated carbon fibers and thermosetting matrix resins such as epoxy, phenolic, and vinyl resins, resulting in greater versatility in the preparation of composite materials with thermosetting matrix resins. The sizing agent provided in this application also exhibits good stability and excellent wettability to carbon fibers, making it suitable for a wide range of applications.

[0008] In conjunction with the first aspect, in optional embodiments of this application, the phenolic epoxy resin includes at least one of bisphenol A phenolic epoxy resin, phenolic epoxy resin, and o-cresol phenolic epoxy resin.

[0009] In the above technical solution, the phenolic epoxy resin selected can be used in combination with epoxy vinyl resin to improve the heat resistance and wear resistance of the carbon fiber after sizing agent treatment.

[0010] In conjunction with the first aspect, in optional embodiments of this application, the epoxy vinyl resin includes at least one of bisphenol A type epoxy vinyl resin and PU modified epoxy vinyl resin.

[0011] In the above technical solution, the epoxy vinyl resin selected can be combined with phenolic epoxy resin to improve the heat resistance and wear resistance of the carbon fiber after sizing agent treatment.

[0012] In conjunction with the first aspect, in optional embodiments of this application, the surfactant includes at least one of alkylphenol polyoxyethylene ether, fatty acid polyoxyethylene ester, polyethylene glycol fatty acid ester, polyethylene glycol, dehydrated sorbitan fatty acid ester, and polyoxyethylene dehydrated sorbitan fatty acid ester.

[0013] In conjunction with the first aspect, in an optional embodiment of this application, the mass percentage of the main slurry in the sizing agent is 0.8% to 1.2%.

[0014] In conjunction with the first aspect, in an optional embodiment of this application, the emulsion particle size of the sizing agent is 300-500 nm.

[0015] In the above technical solution, the emulsion particle size of the sizing agent is more suitable, which makes the sizing agent more stable.

[0016] Secondly, this application provides a method for preparing the sizing agent provided in any of the first aspects above. The preparation method includes: first mixing a system containing a main sizing agent and a co-solvent to obtain an oily system; then adding water to the oily system and second mixing to obtain an intermediate emulsion; and removing the co-solvent from the intermediate emulsion.

[0017] The sizing agent preparation method provided in this application uses both phenolic epoxy resin and epoxy vinyl resin. The synergistic effect of phenolic epoxy resin and epoxy vinyl resin improves the heat resistance and wear resistance of the sizing agent-treated carbon fiber, making it suitable for high-temperature environments. Furthermore, by adding phenolic epoxy resin and epoxy vinyl resin to the sizing agent preparation method, this application ensures strong interfacial bonding strength between the sizing agent-treated carbon fiber and thermosetting matrix resins such as epoxy resin, phenolic resin, and vinyl resin. This enhances the versatility of the sizing agent-treated carbon fiber in the field of preparing composite materials with thermosetting matrix resins. Moreover, the sizing agent prepared in this application exhibits good stability and excellent wettability to carbon fibers, resulting in a wide range of applications.

[0018] In conjunction with the second aspect, in optional embodiments of this application, the co-solvent includes at least one of dichloromethane, acetone, and methanol.

[0019] In the above technical solution, the cosolvent selected is the aforementioned substance, which can dissolve phenolic epoxy resin and epoxy vinyl resin more fully and reduce the viscosity of the system, so as to facilitate the subsequent emulsification operation of adding water.

[0020] Thirdly, this application provides a carbon fiber comprising a carbon fiber matrix and a coating layer located on the surface of the carbon fiber matrix; the coating layer comprises the dried product of the sizing agent provided in any of the first aspects above.

[0021] The carbon fiber provided in this application has high heat resistance and wear resistance, and can be used in high-temperature environments. Furthermore, the carbon fiber provided in this application has strong interfacial bonding strength with thermosetting matrix resins such as epoxy resin, phenolic resin, and vinyl resin, which is beneficial to improving the mechanical properties of composite materials formed by carbon fiber and thermosetting matrix resins such as epoxy resin, phenolic resin, and vinyl resin.

[0022] Optionally, the decomposition temperature of carbon fiber is ≥300℃.

[0023] Fourthly, this application provides a composite material comprising a matrix resin and the carbon fiber provided in the third aspect above.

[0024] The composite material provided in this application has high heat resistance and wear resistance, and the interfacial bonding strength between the matrix resin and carbon fiber is high.

[0025] Optionally, the matrix resin includes a thermosetting resin.

[0026] Optionally, the thermosetting resin includes at least one of epoxy resin, phenolic resin, and vinyl resin. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 A flowchart illustrating the preparation method of the sizing agent provided in this application.

[0029] Figure 2 The image shows the thermogravimetric curve of the sized carbon fiber prepared in Example 1. Detailed Implementation

[0030] This application provides a sizing agent, which is an emulsion and includes a main sizing agent and water. The main sizing agent includes the following components by weight: 80-120 parts of phenolic epoxy resin, 100-150 parts of epoxy vinyl resin, and 10-20 parts of surfactant.

[0031] This application improves the heat resistance and wear resistance of carbon fibers treated with sizing agent by simultaneously adding phenolic epoxy resin and epoxy vinyl resin to the sizing agent. This allows the carbon fibers to be used in high-temperature environments.

[0032] Furthermore, by adding phenolic epoxy resin and epoxy vinyl resin to the sizing agent, this application enables the carbon fiber treated with the sizing agent to have a strong interfacial bonding strength with thermosetting matrix resins such as epoxy resin, phenolic resin, and vinyl resin, thereby making the carbon fiber treated with the sizing agent more versatile in the field of preparing composite materials with thermosetting matrix resins.

[0033] Furthermore, the sizing agent provided in this application has good stability and good wettability on carbon fibers, and has a wide range of applications.

[0034] As an example, in the main slurry, the weight parts of phenolic epoxy resin can be any one of 80, 85, 90, 95, 100, 105, 110, 115 and 120 or any range between two; the weight parts of epoxy vinyl resin can be any one of 100, 105, 110, 115, 120, 125, 130, 135, 140, 145 and 150 or any range between two; and the weight parts of surfactant can be any one of 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 and 20 or any range between two.

[0035] In some optional embodiments of this application, the phenolic epoxy resin includes at least one of bisphenol A phenolic epoxy resin, phenolic epoxy resin, and o-cresol phenolic epoxy resin.

[0036] The phenolic epoxy resin selected above can be combined with epoxy vinyl resin to improve the heat resistance and wear resistance of carbon fibers after sizing agent treatment.

[0037] Furthermore, the phenolic epoxy resin is selected from phenolic epoxy resin; phenolic epoxy resin can improve the reactivity of the sizing agent and further improve the heat resistance and wear resistance of the carbon fiber after sizing agent treatment.

[0038] In some optional embodiments of this application, the epoxy vinyl resin includes at least one of bisphenol A type epoxy vinyl resin (e.g., Altac 430), flexible epoxy vinyl resin (e.g., Fuchem 810), and PU modified epoxy vinyl resin (e.g., Fuchem 820).

[0039] The epoxy vinyl resin selected above can be combined with phenolic epoxy resin to improve the heat resistance and wear resistance of carbon fibers after sizing agent treatment.

[0040] Furthermore, the epoxy vinyl resin selected is PU-modified epoxy vinyl resin; PU-modified epoxy vinyl resin can improve the abrasion resistance and flexibility of carbon fibers after sizing agent treatment.

[0041] In some optional embodiments of this application, the surfactant includes at least one of alkylphenol polyoxyethylene ether, fatty acid polyoxyethylene ester, polyethylene glycol fatty acid ester, polyethylene glycol, sorbitan fatty acid ester, and polyoxyethylene sorbitan fatty acid ester.

[0042] Furthermore, the surfactant selected is alkylphenol polyoxyethylene ether.

[0043] In some optional embodiments of this application, the mass percentage of the main slurry in the sizing agent is 0.8% to 1.2%.

[0044] As an example, the mass percentage of the main slurry in the sizing agent can be any one of 0.8%, 0.85%, 0.9%, 0.95%, 1.0%, 1.05%, 1.1%, 1.15%, and 1.2%, or any range between the two.

[0045] In some optional embodiments of this application, the emulsion particle size of the sizing agent is 300–500 nm. A suitable emulsion particle size results in good stability of the sizing agent.

[0046] As an example, the emulsion particle size of the sizing agent can be any value among 300nm, 350nm, 400nm, 450nm and 500nm or any range between the two.

[0047] This application provides a method for preparing a sizing agent, the method comprising: first mixing a system containing a main sizing agent and a co-solvent to obtain an oily system; then adding water to the oily system and performing a second mixing to obtain an intermediate emulsion; and removing the co-solvent from the intermediate emulsion.

[0048] It should be noted that the selection of components in the main slurry and the dosage ratio of each component in the sizing agent used in the preparation method are the same as those in the main slurry and the dosage ratio of each component in the sizing agent mentioned above, and will not be repeated here.

[0049] The sizing agent preparation method provided in this application uses both phenolic epoxy resin and epoxy vinyl resin. Through the synergistic effect of phenolic epoxy resin and epoxy vinyl resin, the heat resistance and wear resistance of the carbon fiber treated with the sizing agent can be improved, making it suitable for use in high-temperature environments.

[0050] Furthermore, by adding phenolic epoxy resin and epoxy vinyl resin to the preparation method of the sizing agent, this application enables the sizing agent-treated carbon fiber to have strong interfacial bonding strength with thermosetting matrix resins such as epoxy resin, phenolic resin, and vinyl resin. This makes the sizing agent-treated carbon fiber more versatile in the field of preparing composite materials with thermosetting matrix resins. Moreover, the sizing agent prepared in this application has good stability and good wettability to carbon fiber, and has a wide range of applications.

[0051] Figure 1 For a flowchart of the preparation method of the sizing agent provided in this application, please refer to [link / reference needed]. Figure 1 The preparation method of the sizing agent includes the following steps:

[0052] S110, the system containing the main slurry and the co-solvent is first mixed to obtain an oily system; wherein, the main slurry includes the following components by weight: 80-120 parts of phenolic epoxy resin, 100-150 parts of epoxy vinyl resin and 10-20 parts of surfactant.

[0053] In some optional embodiments of this application, the co-solvent includes at least one of dichloromethane, acetone, and methanol.

[0054] The aforementioned substances are selected as cosolvents, which can effectively dissolve phenolic epoxy resin and epoxy vinyl resin, and reduce the viscosity of the system to facilitate subsequent emulsification with water.

[0055] Furthermore, dichloromethane is selected as the cosolvent.

[0056] In some optional embodiments of this application, the preparation steps of the oily system include: mixing phenolic epoxy resin, epoxy vinyl resin, and a surfactant to obtain a main slurry; and then mixing the main slurry with a co-solvent to obtain an oily system. Alternatively, the preparation steps of the oily system include: mixing phenolic epoxy resin, epoxy vinyl resin, a surfactant, and a co-solvent to obtain an oily system.

[0057] Furthermore, the oily system comprises the following components by weight: 80-120 parts of phenolic epoxy resin, 100-150 parts of epoxy vinyl resin, 10-20 parts of surfactant, and 50-100 parts of cosolvent.

[0058] S120, water is added to the oily system and a second mixing is performed to obtain an intermediate emulsion.

[0059] In some optional embodiments of this application, adding water to the oily system during the stirring process is beneficial for thorough emulsification.

[0060] In some optional embodiments of this application, the intermediate emulsion comprises the following components by weight: 80-120 parts of phenolic epoxy resin, 100-150 parts of epoxy vinyl resin, 10-20 parts of surfactant, 50-100 parts of cosolvent, and 220-270 parts of water.

[0061] As an example, the water is deionized water.

[0062] S130 removes the cosolvent from the intermediate emulsion.

[0063] It should be noted that this application does not limit the specific method of removing the cosolvent; for example, rotary evaporation may be used.

[0064] This application also provides a carbon fiber comprising a carbon fiber matrix and a coating layer located on the surface of the carbon fiber matrix; the coating layer comprises the dried product of the sizing agent provided above.

[0065] The carbon fiber provided in this application has high heat resistance and wear resistance, and can be used in high-temperature environments. Furthermore, the carbon fiber provided in this application has strong interfacial bonding strength with thermosetting matrix resins such as epoxy resin, phenolic resin, and vinyl resin, which is beneficial to improving the mechanical properties of composite materials formed by carbon fiber and thermosetting matrix resins such as epoxy resin, phenolic resin, and vinyl resin.

[0066] In some optional embodiments of this application, the decomposition temperature of the carbon fiber is ≥300°C.

[0067] It should be noted that this application does not limit the specific material of the carbon fiber matrix.

[0068] This application also provides a method for preparing carbon fiber, which includes: coating the surface of a carbon fiber matrix with the above-mentioned sizing agent, and then drying it.

[0069] In some optional embodiments of this application, the mass ratio of sizing agent to carbon fiber matrix is ​​(0.008 to 0.012):1.

[0070] As an example, the mass ratio of sizing agent to carbon fiber matrix can be any one of 0.008:1, 0.0085:1, 0.009:1, 0.0095:1, 0.01:1, 0.0102:1, 0.011, and 0.012:1 or any range between the two.

[0071] This application also provides a composite material comprising a matrix resin and the carbon fiber provided above.

[0072] The composite material provided in this application has high heat resistance and wear resistance, and the interfacial bonding strength between the matrix resin and carbon fiber is high.

[0073] In some optional embodiments of this application, the matrix resin includes a thermosetting resin.

[0074] Furthermore, the thermosetting resin includes at least one of epoxy resin, phenolic resin, and vinyl resin.

[0075] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0076] Example 1

[0077] This embodiment provides a sizing agent and sized carbon fiber, which are prepared by the following steps:

[0078] (1) 100g of phenolic epoxy resin (i.e., phenolic epoxy resin), 150g of PU-modified epoxy vinyl resin Fuchem 820 (i.e., epoxy vinyl resin), 20g of alkylphenol polyoxyethylene ether (i.e., surfactant), and 100g of dichloromethane (i.e., cosolvent) were stirred at 500rpm for 30min. Then, 250g of deionized water was added, and the mixture was stirred at 1500rpm for 30min to obtain an emulsion mixture. The dichloromethane in the emulsion mixture was then evaporated to obtain a sizing agent.

[0079] (2) The polyacrylonitrile carbon fiber is sized using the sizing agent obtained in step (1) and then dried to obtain sized carbon fiber. The mass ratio of the sizing agent to the carbon fiber is 0.0102:1.

[0080] Example 2

[0081] This embodiment provides a sizing agent and sized carbon fiber, which are prepared by the following steps:

[0082] (1) 100g of phenolic epoxy resin (i.e., phenolic epoxy resin), 100g of PU-modified epoxy vinyl resin Fuchem 820 (i.e., epoxy vinyl resin), 15g of alkylphenol polyoxyethylene ether (i.e., surfactant), and 80g of dichloromethane (i.e., cosolvent) were stirred at 500rpm for 30min. Then, 250g of deionized water was added, and the mixture was stirred at 1500rpm for 30min to obtain an emulsion mixture. The dichloromethane in the emulsion mixture was then evaporated to obtain a sizing agent.

[0083] (2) The polyacrylonitrile carbon fiber is sized using the sizing agent obtained in step (1) and then dried to obtain sized carbon fiber. The mass ratio of the sizing agent to the carbon fiber is 0.011:1.

[0084] Comparative Example 1

[0085] This comparative example provides a sizing agent and sized carbon fiber, which are prepared by the following steps:

[0086] (1) 250g of phenolic epoxy resin (i.e., phenolic epoxy resin), 20g of alkylphenol polyoxyethylene ether (i.e., surfactant), and 100g of dichloromethane (i.e., cosolvent) were stirred at 500rpm for 30min. Then, 250g of deionized water was added, and the mixture was stirred at 1500rpm for 30min to obtain an emulsion mixture. The dichloromethane in the emulsion mixture was then evaporated to obtain a sizing agent.

[0087] (2) The polyacrylonitrile carbon fiber is sized using the sizing agent obtained in step (1) and then dried to obtain sized carbon fiber. The mass ratio of the sizing agent to the carbon fiber is 0.0102:1.

[0088] Comparative Example 2

[0089] This comparative example provides a sizing agent and sized carbon fiber, which are prepared by the following steps:

[0090] (1) 250g of PU-modified epoxy vinyl resin Fuchem 820 (i.e., epoxy vinyl resin), 20g of alkylphenol polyoxyethylene ether (i.e., surfactant), and 100g of dichloromethane (i.e., cosolvent) were stirred at 500rpm for 30min. Then, 250g of deionized water was added, and the mixture was stirred at 1500rpm for 30min to obtain an emulsion mixture. The dichloromethane in the emulsion mixture was then evaporated to obtain a sizing agent.

[0091] (2) The polyacrylonitrile carbon fiber is sized using the sizing agent obtained in step (1) and then dried to obtain sized carbon fiber. The mass ratio of the sizing agent to the carbon fiber is 0.0102:1.

[0092] Comparative Example 3

[0093] This comparative example provides a sizing agent and sized carbon fiber, which are prepared by the following steps:

[0094] (1) 250g of bisphenol A type epoxy E44 resin (i.e., epoxy resin), 20g of alkylphenol polyoxyethylene ether (i.e., surfactant), and 100g of dichloromethane (i.e., cosolvent) were stirred at 500rpm for 30min. Then, 250g of deionized water was added, and the mixture was stirred at 1500rpm for 30min to obtain an emulsion mixture. The dichloromethane in the emulsion mixture was then evaporated to obtain a sizing agent.

[0095] (2) The polyacrylonitrile carbon fiber is sized using the sizing agent obtained in step (1) and then dried to obtain sized carbon fiber. The mass ratio of the sizing agent to the carbon fiber is 0.0102:1.

[0096] Comparative Example 4

[0097] This comparative example provides a sizing agent and sizing carbon fiber. The only difference between this comparative example and Example 1 is that the phenolic epoxy resin in Example 1 (i.e., phenolic epoxy resin) is replaced with bisphenol A type epoxy E44 resin (i.e., epoxy resin).

[0098] Comparative Example 5

[0099] This comparative example provides a sizing agent and sizing carbon fiber. The only difference between this comparative example and Example 1 is that the PU modified epoxy vinyl resin Fuchem 820 (i.e., epoxy vinyl resin) in Example 1 is replaced with bisphenol A type epoxy E44 resin (i.e., epoxy resin).

[0100] Comparative Example 6

[0101] This comparative example provides a sizing agent and sizing carbon fiber. The only difference between this comparative example and Example 1 is that the phenolic epoxy resin in Example 1 (i.e., phenolic epoxy resin) is replaced with phenolic resin (Dongrun New Materials D126-1, i.e., phenolic resin without epoxy groups).

[0102] Experimental Example 1

[0103] Referring to GB / T 3357-1982 "Test Method for Interlaminar Shear Strength of Unidirectional Fiber Reinforced Plastics", the sized carbon fibers prepared in Examples 1-2 and Comparative Examples 1-6 were respectively compounded with matrix resin to prepare composite materials. The interlaminar shear strength (ILSS) of the sized carbon fiber unidirectional plates was tested, and the test results are shown in Table 1.

[0104] The matrix resins are: thermosetting epoxy resin AG80 (purchased from Shanghai Synthetic Resin Research Institute), thermosetting phenolic resin 2123 (purchased from Sumitomo Chemical Co., Ltd., Japan), and thermosetting vinyl resin 430LV (purchased from Jinling Lilians Resin Co., Ltd.).

[0105] Table 1

[0106]

[0107]

[0108] As can be seen from Table 1, the interlaminar shear strength of the sized carbon fibers prepared in Examples 1-2 with thermosetting epoxy resin AG80, thermosetting phenolic resin 2123, and thermosetting vinyl resin 430LV is higher than that of Comparative Examples 1-6, indicating that the sized carbon fibers prepared in Examples 1-2 have strong interfacial bonding strength with these thermosetting matrix resins such as epoxy resin, phenolic resin, and vinyl resin.

[0109] Experiment Example 2

[0110] The emulsion particle size of the sizing agents prepared in Examples 1-2 and Comparative Examples 1-6 was tested, and the hairiness and heat resistance of the sized carbon fibers prepared in Examples 1-2 and Comparative Examples 1-6 were tested. The test results are shown in Table 2. The thermogravimetric curve of the sized carbon fiber prepared in Example 1 is shown in Table 2. Figure 2 As shown.

[0111] The heat resistance test was conducted in accordance with GB / T 19466.2-2004, and the initial decomposition temperature of the sized carbon fiber was recorded.

[0112] Table 2

[0113]

[0114] As can be seen from Table 2, the amount of hairiness of the sizing carbon fibers prepared in Examples 1-2 is lower than that of the sizing carbon fibers prepared in Comparative Examples 1-6. The initial decomposition temperature of the sizing carbon fibers prepared in Examples 1-2 is higher than that of the sizing carbon fibers prepared in Comparative Examples 1-6. This indicates that the sizing agent prepared in Examples 1-2 can improve the wear resistance and heat resistance of the sizing carbon fibers.

[0115] In summary, this application, by simultaneously adding phenolic epoxy resin and epoxy vinyl resin to the sizing agent, improves the heat resistance and wear resistance of the sizing agent-treated carbon fiber through the synergistic effect of the two resins, making it suitable for use in high-temperature environments. Furthermore, by adding phenolic epoxy resin and epoxy vinyl resin to the sizing agent, this application ensures strong interfacial bonding strength between the sizing agent-treated carbon fiber and thermosetting matrix resins such as epoxy resin, phenolic resin, and vinyl resin. This enhances the versatility of the sizing agent-treated carbon fiber in the preparation of composite materials with thermosetting matrix resins. Moreover, the sizing agent provided by this application exhibits good stability and excellent wettability to carbon fibers, resulting in a wide range of applications.

[0116] The embodiments described above are some, but not all, of the embodiments of this application. The detailed description of the embodiments of this application is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

Claims

1. A carbon fiber, characterized in that, It includes a carbon fiber matrix and a coating layer located on the surface of the carbon fiber matrix; the coating layer includes the dried product of a sizing agent; The sizing agent is in the form of an emulsion and includes a main sizing agent and water; the main sizing agent is composed of the following components by weight: 100 parts of phenolic epoxy resin, 100-150 parts of PU-modified vinyl ester resin, and 10-20 parts of surfactant; The decomposition temperature of the carbon fiber is ≥300℃.

2. The carbon fiber according to claim 1, characterized in that, The surfactant includes at least one of alkylphenol polyoxyethylene ether, fatty acid polyoxyethylene ester, polyethylene glycol fatty acid ester, polyethylene glycol, sorbitan fatty acid ester, and polyoxyethylene sorbitan fatty acid ester.

3. The carbon fiber according to claim 1 or 2, characterized in that, The main slurry accounts for 0.8-1.2% of the mass of the sizing agent.

4. The carbon fiber according to claim 1 or 2, characterized in that, The emulsion particle size of the sizing agent is 300~500nm.

5. The carbon fiber according to claim 1, characterized in that, The preparation method of the sizing agent includes: first mixing a system containing the main sizing agent and a co-solvent to obtain an oily system; then adding water to the oily system and mixing it a second time to obtain an intermediate emulsion; and removing the co-solvent from the intermediate emulsion.

6. The carbon fiber according to claim 5, characterized in that, The co-solvent includes at least one of dichloromethane, acetone, and methanol.

7. A composite material, characterized in that, It includes a matrix resin and carbon fiber as described in any one of claims 1 to 6.

8. The composite material according to claim 7, characterized in that, The matrix resin includes thermosetting resins.

9. The composite material according to claim 8, characterized in that, The thermosetting resin includes at least one of epoxy resin, phenolic resin, and vinyl resin.

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