Sizing agent and preparation method thereof, carbon fiber and composite material

Abstract

The present application provides a sizing agent and a preparation method thereof, carbon fiber and composite material, belonging to the technical field of carbon fiber sizing agents. The sizing agent is in the form of an emulsion, and the sizing agent includes a main sizing agent and water; the main sizing agent includes the following components in parts by weight: 20 to 30 parts of polyphenol oxide resin, 10 to 20 parts of epoxy resin and 10 to 20 parts of emulsifier; wherein SiO2 is covalently linked to the epoxy resin. The present application covalently links SiO2 to the epoxy resin of the sizing agent, which can not only significantly increase the surface roughness of the carbon fiber after the sizing agent treatment, but also increase the number of active functional groups on the surface of the carbon fiber after the sizing agent treatment, and can also reduce the fiber fuzzing amount of the carbon fiber after the sizing agent treatment, thereby improving the interface bonding strength between the carbon fiber after the sizing agent treatment and the matrix resin, and can improve the mechanical properties of the composite material formed by the carbon fiber and the matrix resin.

Description

Technical Field

[0001] The present application relates to the technical field of carbon fiber sizing agents, and in particular to a sizing agent and a preparation method thereof, carbon fibers, and composite materials. Background Art

[0002] Carbon fiber is made from raw silk through a series of complex physical and chemical changes such as pre-oxidation, carbonization, and graphitization. Carbon fiber has low elongation and is relatively brittle. During use and processing, it undergoes stretching and friction, which can cause fuzzing and loosening, seriously affecting the bonding performance between the carbon fiber and the matrix resin. Therefore, sizing treatment is required during carbon fiber production. After sizing treatment, the bonding performance between the carbon fiber and the matrix resin will be enhanced.

[0003] However, the existing sizing agent treatment has limited effect on enhancing the bonding performance between carbon fibers and matrix resin. Summary of the Invention

[0004] The purpose of the present application is to provide a sizing agent and a preparation method thereof, carbon fiber and a composite material, which are intended to improve the bonding performance between the carbon fiber treated with the sizing agent and the matrix resin.

[0005] In the first aspect, the present application provides a sizing agent, which is in the form of an emulsion and includes a main sizing agent and water; the main sizing agent includes the following components by weight: 20 to 30 parts of polyphenol oxide resin, 10 to 20 parts of epoxy resin and 10 to 20 parts of emulsifier; wherein SiO2 is covalently bonded to the epoxy resin.

[0006] The present application can not only significantly increase the surface roughness of the carbon fiber after the sizing agent treatment by covalently linking SiO2 to the epoxy resin of the sizing agent, but also increase the number of active functional groups on the surface of the carbon fiber after the sizing agent treatment, thereby improving the interfacial bonding strength between the carbon fiber treated with the sizing agent and the matrix resin, and improving the mechanical properties of the composite material formed by the carbon fiber and the matrix resin; compared with directly adding SiO2 to the sizing agent, covalently linking SiO2 to the epoxy resin is beneficial to avoid the problem of a sharp increase in the viscosity of the sizing agent and difficulty in the processing and preparation of the sizing agent due to the inability of SiO2 to be evenly dispersed in the sizing agent; in addition, the polyphenol oxide resin and the epoxy resin covalently linked to SiO2 cooperate with each other, which can make the carbon fiber after the sizing agent treatment have excellent smooth de-threading performance, reduce the fiber fuzzing amount of the carbon fiber after the sizing agent treatment, and facilitate the subsequent better formation of a composite material between the carbon fiber and the matrix resin.

[0007] In combination with the first aspect, in an optional embodiment of the present application, the polyphenol oxide resin includes at least one of PKHB and PKHH.

[0008] In the above technical solution, the polyphenol oxide resin is selected from the above substances, which is conducive to further cooperating with the epoxy resin covalently linked to SiO2 to reduce the fiber fuzzing amount of the carbon fiber after the sizing agent treatment, and further helps to further improve the interface bonding strength between the carbon fiber treated with the sizing agent and the matrix resin.

[0009] In combination with the first aspect, in an optional embodiment of the present application, the epoxy resin includes at least one of bisphenol A epoxy resin, bisphenol F epoxy resin and tetrafunctional epoxy resin.

[0010] In the above technical solution, the epoxy resin is selected from the above substances, which is conducive to further cooperating with the polyphenol oxide resin to reduce the fiber fuzzing amount of the carbon fiber treated with the sizing agent, and further helps to further improve the interface bonding strength between the carbon fiber treated with the sizing agent and the matrix resin.

[0011] In combination with the first aspect, in an optional embodiment of the present application, the emulsifier 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.

[0012] In combination with the first aspect, in an optional embodiment of the present application, the mass proportion of the main slurry in the sizing agent is 10-20%.

[0013] In a second aspect, the present application provides a method for preparing a sizing agent provided in any one of the first aspects above, the preparation method comprising: first mixing a system containing a main slurry and an organic 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 organic co-solvent in the intermediate emulsion.

[0014] The covalent bonding of SiO2 on the epoxy resin used in the preparation method of the sizing agent provided in the present application can not only significantly increase the surface roughness of the carbon fiber after the sizing agent treatment, but also increase the number of active functional groups on the surface of the carbon fiber after the sizing agent treatment, thereby improving the interfacial bonding strength between the carbon fiber treated with the sizing agent and the matrix resin, and improving the mechanical properties of the composite material formed by the carbon fiber and the matrix resin; compared with directly adding SiO2 to the sizing agent, covalently bonding SiO2 on the epoxy resin is beneficial to avoiding the problem of a sharp increase in the viscosity of the sizing agent and difficulty in processing and preparing the sizing agent due to the inability of SiO2 to be evenly dispersed in the sizing agent; in addition, the polyphenol oxide resin used in the preparation method of the sizing agent provided in the present application and the epoxy resin covalently bonded with SiO2 can cooperate with each other, so that the carbon fiber treated with the sizing agent has excellent smooth de-threading performance, reduces the amount of fiber fuzzing of the carbon fiber treated with the sizing agent, and facilitates the subsequent better formation of a composite material between the carbon fiber and the matrix resin.

[0015] In combination with the second aspect, in an optional embodiment of the present application, the organic co-solvent includes at least one of ethanol, acetone, isopropanol, chloroform, dichloromethane, ethyl acetate, methanol, ether and butyl acetate; or / and, the mass proportion of the main slurry in the oily system is 10-15%; or / and, the stirring speed of the second mixing is 5000-8000 r / min, and the time of the second mixing is 30-50 min.

[0016] In the above technical solution, the organic co-solvent is selected from the above-mentioned substance, which can more fully dissolve the polyphenol oxide resin and the epoxy resin covalently linked to SiO2, and reduce the viscosity of the oil system, so as to facilitate the subsequent emulsification operation of adding water; the mass proportion of the main slurry in the oil system is 10-15%, which can make the viscosity of the oil system more appropriate, so as to facilitate the subsequent emulsification operation of adding water; the stirring speed of the second mixing is 5000-8000r / min, and the time of the second mixing is 30-50min, so as to facilitate sufficient emulsification to form an emulsion-like sizing agent.

[0017] In combination with the second aspect, in an optional embodiment of the present application, the preparation method of an epoxy resin covalently linked to SiO2 includes: subjecting a silane coupling agent to a first reaction with an ethanol aqueous solution at 50 to 70°C to obtain a hydrolyzate; subjecting the hydrolyzate to a second reaction with SiO2 to obtain SiO2 modified with a silane coupling agent; and subjecting a mixed system containing SiO2 modified with a silane coupling agent, an epoxy resin, and ethanol to a third reaction at 50 to 70°C.

[0018] In the above technical solution, an epoxy resin covalently linked to SiO2 can be prepared.

[0019] Optionally, the mass ratio of the silane coupling agent to SiO2 is (0.2-0.3):1.

[0020] Optionally, the mass ratio of SiO2 modified by the silane coupling agent to the epoxy resin is (0.005-0.01):1.

[0021] Optionally, the first reaction time is 20 to 40 minutes.

[0022] Optionally, the second reaction time is 20 to 40 minutes.

[0023] Optionally, the third reaction includes stirring treatment and ultrasonic treatment performed sequentially, and the time of the stirring treatment and the ultrasonic treatment are each independently 20 to 40 minutes.

[0024] In a third aspect, the present 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 one of the first aspects above.

[0025] The carbon fibers provided in the present application have a strong interface bonding strength with the matrix resin, which is beneficial to improving the mechanical properties of the composite material formed by the carbon fibers and the matrix resin.

[0026] In a fourth aspect, the present application provides a composite material comprising a matrix resin and the carbon fiber provided in the third aspect.

[0027] The composite material provided in this application has good mechanical properties and high interface bonding strength between the matrix resin and the carbon fibers.

[0028] Optionally, the matrix resin comprises a thermoplastic resin.

[0029] Optionally, the thermoplastic resin includes a polyamide resin. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0031] Figure 1 This is a flow chart of the preparation method of the sizing agent provided in this application. DETAILED DESCRIPTION

[0032] The present application provides a sizing agent, which is in emulsion form and includes a main sizing agent and water; the main sizing agent includes the following components by weight: 20 to 30 parts of polyphenol oxide resin, 10 to 20 parts of epoxy resin and 10 to 20 parts of emulsifier; wherein SiO2 is covalently bonded to the epoxy resin.

[0033] The present application covalently links SiO2 to the epoxy resin of the sizing agent. After the carbon fiber is treated with the sizing agent, SiO2 can be evenly loaded on the surface of the carbon fiber, which can not only significantly increase the surface roughness of the carbon fiber after the sizing agent treatment, but also increase the number of active functional groups on the surface of the carbon fiber after the sizing agent treatment, which is beneficial to the physical effect of mechanical engagement between the carbon fiber and the matrix resin, thereby improving the interfacial bonding strength between the carbon fiber treated with the sizing agent and the matrix resin, and improving the mechanical properties of the composite material formed by the carbon fiber and the matrix resin; compared with directly adding SiO2 to the sizing agent, covalently linking SiO2 to the epoxy resin is beneficial to avoiding the problem of a sharp increase in the viscosity of the sizing agent and difficulty in the processing and preparation of the sizing agent due to the inability of SiO2 to be evenly dispersed in the sizing agent, and the SiO2 in the sizing agent is evenly dispersed and does not agglomerate.

[0034] In addition, the cooperation between polyphenol oxide resin and epoxy resin covalently linked to SiO2 can make the carbon fiber treated with the sizing agent have excellent smooth de-filamenting performance, and the carbon fiber treated with the sizing agent has a higher smooth de-filamenting performance, avoiding the problems of sticking and splitting in the de-filamenting process, and reducing the amount of fiber fuzzing of the carbon fiber treated with the sizing agent, so as to facilitate the subsequent formation of a composite material between the carbon fiber and the matrix resin.

[0035] As an example, in the main slurry, the weight proportion of the polyphenol oxide resin can be any value among 20 parts, 21 parts, 22 parts, 23 parts, 24 parts, 25 parts, 26 parts, 27 parts, 28 parts, 29 parts and 30 parts, or a range between any two parts; the weight proportion of the epoxy resin covalently linked to SiO2 can be any value among 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts and 20 parts, or a range between any two parts; the weight proportion of the emulsifier can be any value among 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts and 20 parts, or a range between any two parts.

[0036] In some optional embodiments of the present application, the SiO2 covalently linked to the epoxy resin is nano-scale silica; this is beneficial to further enhance the physical effect of mechanical engagement between the carbon fiber and the matrix resin, thereby further enhancing the interfacial bonding strength between the carbon fiber treated with the sizing agent and the matrix resin.

[0037] In some optional embodiments of the present application, the polyphenoloxy resin includes at least one of PKHB and PKHH.

[0038] The polyphenol oxide resin selected from the above substances is beneficial to further cooperate with the epoxy resin covalently linked to SiO2 to reduce the fiber fuzzing amount of the carbon fiber treated with the sizing agent, which is beneficial to further improve the interface bonding strength between the carbon fiber treated with the sizing agent and the matrix resin.

[0039] Furthermore, the polyphenol oxide resin is PKHB.

[0040] In some optional embodiments of the present application, the epoxy resin includes at least one of bisphenol A epoxy resin, bisphenol F epoxy resin and tetrafunctional epoxy resin.

[0041] The epoxy resin selected from the above substances is beneficial for further cooperating with the polyphenol oxide resin to reduce the fiber fuzzing amount of the carbon fiber treated with the sizing agent, thereby further improving the interface bonding strength between the carbon fiber treated with the sizing agent and the matrix resin.

[0042] In some optional embodiments of the present application, the emulsifier 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.

[0043] In some optional embodiments of the present application, the mass proportion of the main slurry in the sizing agent is 10-20%.

[0044] As an example, the mass proportion of the main slurry in the sizing agent can be any value among 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% and 20%, or a range value between any two of them.

[0045] The present application provides a method for preparing a sizing agent, which comprises: first mixing a system containing a main slurry and an organic 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 organic co-solvent from the intermediate emulsion.

[0046] It should be noted that the selection of components in the main slurry used in the preparation method and the dosage ratio of each component in the sizing agent are the same as the selection of components in the main slurry and the dosage ratio of each component in the sizing agent mentioned above, and will not be repeated here.

[0047] The covalent bonding of SiO2 to the epoxy resin used in the preparation method of the sizing agent provided in the present application can not only significantly increase the surface roughness of the carbon fiber after the sizing agent treatment, but also increase the number of active functional groups on the surface of the carbon fiber after the sizing agent treatment, thereby improving the interfacial bonding strength between the carbon fiber treated with the sizing agent and the matrix resin, and improving the mechanical properties of the composite material formed by the carbon fiber and the matrix resin; compared with directly adding SiO2 to the sizing agent, covalently bonding SiO2 to the epoxy resin is beneficial to avoiding the problem of a sharp increase in the viscosity of the sizing agent and difficulty in the processing and preparation of the sizing agent due to the inability of SiO2 to be evenly dispersed in the sizing agent.

[0048] In addition, the polyphenol oxide resin used in the preparation method of the sizing agent provided in the present application and the epoxy resin covalently linked to SiO2 can cooperate with each other, so that the carbon fiber treated with the sizing agent has excellent smooth de-filamentation performance, reduces the amount of fiber fuzzing of the carbon fiber treated with the sizing agent, and facilitates the subsequent better formation of a composite material between the carbon fiber and the matrix resin.

[0049] Figure 1 For the flow chart of the preparation method of the sizing agent provided in this application, please refer to Figure 1 , the preparation method of the sizing agent comprises the following steps:

[0050] S110, performing a first mixing of a system containing a main slurry and an organic co-solvent to obtain an oily system; wherein the main slurry comprises the following components by weight: 20 to 30 parts of polyphenol oxide resin, 10 to 20 parts of epoxy resin, and 10 to 20 parts of emulsifier; SiO2 is covalently bonded to the epoxy resin.

[0051] In some optional embodiments of the present application, the organic co-solvent includes at least one of ethanol, acetone, isopropanol, chloroform, dichloromethane, ethyl acetate, methanol, ether and butyl acetate.

[0052] The organic co-solvents selected from the above substances can more fully dissolve the polyphenol oxide resin and the epoxy resin covalently linked to SiO2, and reduce the viscosity of the oil system to facilitate the subsequent emulsification operation of adding water.

[0053] In some optional embodiments of the present application, the oily system is prepared by mixing a polyphenol oxide resin, an epoxy resin covalently bonded to SiO2, and an emulsifier to obtain a main slurry; and then mixing the main slurry with an organic cosolvent to obtain the oily system. Alternatively, the oily system is prepared by mixing a polyphenol oxide resin, an epoxy resin covalently bonded to SiO2, an emulsifier, and an organic cosolvent to obtain the oily system.

[0054] Furthermore, the mass proportion of the main slurry in the oily system is 10-15%, which can make the viscosity of the oily system more appropriate to facilitate the subsequent emulsification operation of adding water.

[0055] As an example, the mass proportion of the main slurry in the oily system can be any value among 10%, 11%, 12%, 13%, 14% and 15%, or a range of values ​​between any two of them.

[0056] In some optional embodiments of the present application, a method for preparing an epoxy resin covalently linked to SiO2 includes: conducting a first reaction between a silane coupling agent and an aqueous ethanol solution at 50-70°C to obtain a hydrolyzed solution; conducting a second reaction between the hydrolyzed solution and SiO2 to obtain SiO2 modified with the silane coupling agent; and conducting a third reaction between the mixed system containing the SiO2 modified with the silane coupling agent, the epoxy resin, and ethanol at 50-70°C. The above method can prepare an epoxy resin covalently linked to SiO2.

[0057] Illustratively, the temperatures of the first reaction and the third reaction can each independently be any value among 50°C, 52°C, 55°C, 57°C, 60°C, 62°C, 65°C, 67°C and 70°C, or a range between any two of them.

[0058] Furthermore, the mass ratio of the silane coupling agent to SiO2 is (0.2-0.3):1.

[0059] As an example, the silane coupling agent is KH-550, and SiO2 is nano-sized silicon dioxide.

[0060] Furthermore, the mass ratio of SiO2 modified by the silane coupling agent to the epoxy resin is (0.005-0.01):1.

[0061] Furthermore, the first reaction time is 20 to 40 minutes; the second reaction time is 20 to 40 minutes; the third reaction includes stirring treatment and ultrasonic treatment performed in sequence, and the stirring treatment and ultrasonic treatment time are each independently 20 to 40 minutes.

[0062] As an example, the time for the first reaction, the second reaction, the stirring treatment and the ultrasonic treatment can each independently be any point value among 20min, 22min, 25min, 27min, 30min, 32min, 35min, 37min and 40min or a range value between any two of them.

[0063] As an example, the second reaction is an ultrasonic dispersion reaction.

[0064] In some optional embodiments of the present application, the preparation method of the above-mentioned hydrolyzate includes: mixing ethanol and water in a mass ratio of (5 to 9): 1, adding hydrochloric acid to adjust the pH to 2 to 4 to obtain an ethanol aqueous solution; and then slowly adding the silane coupling agent dropwise to the aforementioned ethanol aqueous solution and conducting a first reaction at 50 to 70°C.

[0065] Furthermore, the mass ratio of the silane coupling agent to the ethanol aqueous solution is (0.01-0.02):1.

[0066] In some optional embodiments of the present application, the step of the third reaction includes: first ultrasonically dispersing SiO2 modified with a silane coupling agent and ethanol for 20 to 40 minutes to obtain a dispersion; then slowly adding the aforementioned dispersion to the epoxy resin at 50 to 70°C, and sequentially performing stirring treatment and ultrasonic treatment.

[0067] In some optional embodiments of the present application, the method for preparing an epoxy resin covalently bonded with SiO2 further includes: before performing the third reaction, drying the SiO2 modified with a silane coupling agent in a forced air drying oven (for example, at a temperature of 100°C).

[0068] In some optional embodiments of the present application, the method for preparing an epoxy resin covalently bonded with SiO2 further includes: drying the system after the third reaction in a vacuum oven (for example, at a temperature of 60°C) to remove the ethanol solvent.

[0069] It should be noted that the preparation method of the epoxy resin covalently bonded with SiO2 is not limited to the preparation method provided above, as long as the epoxy resin covalently bonded with SiO2 can be prepared.

[0070] S120, adding water to the oily system and performing a second mixing to obtain an intermediate emulsion.

[0071] Water is added to the oily system and mixed a second time to obtain an intermediate emulsion by phase inversion emulsification.

[0072] In some optional embodiments of the present application, water is added to the oily system during stirring of the oily system to facilitate full emulsification.

[0073] In some optional embodiments of the present application, the stirring speed of the second mixing is 5000-8000 r / min, and the second mixing time is 30-50 min; so as to fully emulsify and form an emulsion-like sizing agent.

[0074] As an example, the second mixing is homogenous stirring.

[0075] As an example, the water used in the second mixing is deionized water.

[0076] S130, removing the cosolvent from the intermediate emulsion.

[0077] It should be noted that the present application does not limit the specific method of removing the co-solvent. For example, rotary evaporation can be used.

[0078] The present application also provides a carbon fiber, which 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 the sizing agent provided above.

[0079] The carbon fibers provided in the present application have a strong interface bonding strength with the matrix resin, which is beneficial to improving the mechanical properties of the composite material formed by the carbon fibers and the matrix resin.

[0080] It should be noted that the present application does not limit the specific material of the carbon fiber matrix.

[0081] The present application also provides a method for preparing carbon fiber, which comprises: applying the above-mentioned sizing agent to the surface of the carbon fiber substrate, and then drying it.

[0082] The present application also provides a composite material, which includes a matrix resin and the carbon fiber provided above.

[0083] The composite material provided in this application has good mechanical properties and high interface bonding strength between the matrix resin and the carbon fibers.

[0084] In some optional embodiments of the present application, the matrix resin includes a thermoplastic resin.

[0085] Illustratively, the thermoplastic resin includes a polyamide resin.

[0086] To make the purpose, technical solutions and advantages of the examples of the present application clearer, the technical solutions in the examples of the present application will be described clearly and completely below. Where specific conditions are not specified in the examples, conventional conditions or conditions recommended by the manufacturer are used. Where the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially.

[0087] Example 1

[0088] This embodiment provides a sizing agent and sized carbon fiber, which are prepared by the following steps:

[0089] (1) Ethanol and water are mixed in a mass ratio of 9:1, hydrochloric acid is added to adjust the pH to 2, and the mixture is stirred to obtain an ethanol-water solution; silane coupling agent KH-550 is slowly added dropwise to the aforementioned ethanol-water solution, and the mixture is refluxed and stirred at 60°C for 30 minutes to obtain a hydrolyzed solution. The mass ratio of silane coupling agent KH-550 to the aforementioned ethanol-water solution is 0.01:1.

[0090] The hydrolyzate was mixed with nano-SiO2 in a mass ratio of 0.2:1, and dispersed and reacted in an ultrasonic machine for 30 minutes. The reacted system was then dried in a forced air drying oven at 100°C to obtain SiO2 modified with a silane coupling agent.

[0091] SiO2 modified with a silane coupling agent was mixed with ethanol and dispersed using an ultrasonic machine for 30 minutes to obtain a dispersion. This dispersion was then slowly added dropwise to bisphenol A epoxy resin at 60°C. The mixture was magnetically stirred for 30 minutes, then ultrasonically dispersed for 30 minutes. The mixture was then transferred to a vacuum oven at 60°C to remove the ethanol solvent, yielding an epoxy resin with covalently attached SiO2. The mass ratio of SiO2 modified with a silane coupling agent to bisphenol A epoxy resin was 0.006:1.

[0092] (2) adding phenoxy resin PKHB, the epoxy resin covalently linked to SiO2 obtained in step (1), and alkylphenol polyoxyethylene ether in a mass ratio of 25:20:15 to dichloromethane and mixing them uniformly to obtain an oily system; then adding deionized water to the oily system and stirring at 6000 rpm for 30 minutes to obtain an emulsion-like mixed system; then volatilizing the dichloromethane in the emulsion-like mixed system to obtain a sizing agent.

[0093] The sum of the masses of the phenoxy resin PKHB, the epoxy resin covalently linked to SiO2, and the alkylphenol polyoxyethylene ether is 10% of the total mass of the oily system; and the mass ratio of the oily system to deionized water is 2:1.

[0094] (3) Using the sizing agent obtained in step (2) to sizing the polyacrylonitrile carbon fiber, and then drying to obtain sized carbon fiber.

[0095] Example 2

[0096] This embodiment provides a sizing agent and sized carbon fiber. The only difference between this embodiment and Example 1 is that the bisphenol A epoxy resin in step (1) of Example 1 is replaced by bisphenol F epoxy resin, and the mass ratio of SiO2 modified by the silane coupling agent to the bisphenol F epoxy resin is 0.007:1.

[0097] Example 3

[0098] This embodiment provides a sizing agent and sized carbon fiber. The only difference between this embodiment and Example 1 is that the bisphenol A epoxy resin in step (1) of Example 1 is replaced by a tetrafunctional epoxy resin (purchased from Shanghai Huayi Resin Co., Ltd., model AG-80), and the mass ratio of SiO2 modified by the silane coupling agent to the tetrafunctional epoxy resin is 0.01:1.

[0099] Comparative Example 1

[0100] This comparative example provides a sizing agent and sized carbon fiber, which are prepared by the following steps:

[0101] (1) Phenoxy resin PKHB, bisphenol A epoxy resin, and alkylphenol polyoxyethylene ether in a mass ratio of 25:20:15 are added to dichloromethane and mixed uniformly to obtain an oily system; deionized water is then added to the oily system and stirred at 6000 rpm for 30 minutes to obtain an emulsion-like mixed system. The dichloromethane organic cosolvent in the emulsion-like mixed system is then volatilized to obtain a sizing agent.

[0102] The sum of the masses of phenoxy resin PKHB, bisphenol A epoxy resin and alkylphenol polyoxyethylene ether is 10% of the total mass of the oily system; and the mass ratio of the oily system to deionized water is 2:1.

[0103] (2) Using the sizing agent obtained in step (1) to perform sizing treatment on polyacrylonitrile carbon fiber, and then drying to obtain sized carbon fiber.

[0104] Comparative Example 2

[0105] This comparative example provides a sizing agent and sized carbon fiber. The only difference between this comparative example and comparative example 1 is that bisphenol A epoxy resin is replaced by bisphenol F epoxy resin.

[0106] Comparative Example 3

[0107] This comparative example provides a sizing agent and sized carbon fiber. The only difference between this comparative example and comparative example 1 is that the bisphenol A epoxy resin is replaced by a tetrafunctional epoxy resin (purchased from Shanghai Huayi Resin Co., Ltd., model AG-80).

[0108] Experimental Example 1

[0109] The sized carbon fibers prepared in Examples 1 to 3 and Comparative Examples 1 to 3 were respectively compounded with PA66 matrix resin to prepare composite materials, and the interlaminar shear strength of the composite materials was tested (according to JC / T 773-2010). The test results are shown in Table 1.

[0110] Table 1

[0111]

[0112]

[0113] As can be seen from Table 1, the interlaminar shear strength of the sized carbon fibers prepared in Examples 1 to 3 and the thermoplastic PA66 matrix resin is higher than that of Comparative Examples 1 to 3, indicating that the sized carbon fibers prepared in Examples 1 to 3 and the PA66 matrix resin have a strong interface bonding strength.

[0114] Experimental Example 2

[0115] The fiber fuzzing amounts of the sized carbon fibers after de-filamentation obtained in Examples 1 to 3 and Comparative Examples 1 to 3 were compared, and the results are shown in Table 2.

[0116] Table 2

[0117] Fuzzing amount (mg / 50m) Example 1 3.2 Example 2 3.7 Example 3 3.5 Comparative Example 1 5.4 Comparative Example 2 6.2 Comparative Example 3 4.9

[0118] As can be seen from Table 2, the amount of fuzz after unwinding of the sized carbon fibers prepared in Examples 1 to 3 is less than that of Comparative Examples 1 to 3, indicating that the sized carbon fibers prepared in Examples 1 to 3 have excellent smooth unwinding performance.

[0119] In summary, the present application covalently links SiO2 to the epoxy resin of the sizing agent, which can not only significantly increase the surface roughness of the carbon fiber after the sizing agent treatment, but also increase the number of active functional groups on the surface of the carbon fiber after the sizing agent treatment, and can also reduce the fiber fuzzing amount of the carbon fiber after the sizing agent treatment, thereby improving the interface bonding strength between the carbon fiber treated with the sizing agent and the matrix resin, and can improve the mechanical properties of the composite material formed by the carbon fiber and the matrix resin.

[0120] The embodiments described above are part of the embodiments of the present application, rather than all of the embodiments. The detailed description of the embodiments of the present application is not intended to limit the scope of the present application for protection, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

Claims

1. A sizing agent, characterized in that The sizing agent is in the form of an emulsion, and comprises a main sizing agent and water; the main sizing agent comprises the following components in parts by weight: 20-30 parts of polyphenol oxide resin, 10-20 parts of epoxy resin and 10-20 parts of emulsifier; The epoxy resin is covalently linked to SiO2, and the preparation method includes: a first reaction of a silane coupling agent and an ethanol aqueous solution at 50-70°C to obtain a hydrolyzate; a second reaction of the hydrolyzate and SiO2 to obtain SiO2 modified with a silane coupling agent; and a third reaction of a mixed system containing SiO2 modified with the silane coupling agent, an epoxy resin, and ethanol at 50-70°C.

2. The sizing agent according to claim 1, wherein The polyphenoloxy resin includes at least one of PKHB and PKHH.

3. The sizing agent according to claim 1, characterized in that The epoxy resin includes at least one of bisphenol A epoxy resin, bisphenol F epoxy resin and tetrafunctional epoxy resin.

4. The sizing agent according to claim 1, characterized in that The emulsifier 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.

5. The sizing agent according to any one of claims 1 to 4, characterized in that The mass proportion of the main slurry in the sizing agent is 10-20%.

6. A method for preparing a sizing agent according to any one of claims 1 to 5, characterized in that: include: The system containing the main slurry and the organic co-solvent is first mixed to obtain an oily system; the water is then added to the oily system and secondly mixed to obtain an intermediate emulsion; and the organic co-solvent in the intermediate emulsion is removed.

7. The method for preparing a sizing agent according to claim 6, wherein The organic co-solvent comprises at least one of ethanol, acetone, isopropanol, chloroform, dichloromethane, ethyl acetate, methanol, ether and butyl acetate; Or / and, the mass proportion of the main slurry in the oily system is 10-15%; Or / and, the stirring speed of the second mixing is 5000-8000 r / min, and the time of the second mixing is 30-50 min.

8. The method for preparing a sizing agent according to claim 6 or 7, wherein: The mass ratio of the silane coupling agent to the SiO2 is (0.2-0.3):1; And / or, the mass ratio of the SiO2 modified by the silane coupling agent to the epoxy resin is (0.005-0.01):1; Or / and, the first reaction time is 20 to 40 minutes; Or / and, the second reaction time is 20 to 40 minutes; Or / and, the third reaction comprises stirring treatment and ultrasonic treatment performed sequentially, and the time of the stirring treatment and the ultrasonic treatment are each independently 20 to 40 minutes.

9. A carbon fiber, characterized in that The invention comprises 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 according to any one of claims 1 to 5.

10. A composite material, characterized in that The method comprises a matrix resin and the carbon fiber according to claim 9.

11. The composite material according to claim 10, characterized in that The base resin includes a thermoplastic resin.

12. The composite material according to claim 11, characterized in that The thermoplastic resin includes a polyamide resin.

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