Water-soluble resveratrol-based epoxy resin emulsion, and preparation method and application thereof

Abstract

The present application relates to a kind of water-soluble resveratrol epoxy resin emulsion and its preparation method and application.The emulsion includes resveratrol epoxy resin and water, and the content of resveratrol epoxy resin is 15-20wt%;Resveratrol epoxy resin main structure is branched structure formed by the reaction of resveratrol and epichlorohydrin, and polyethylene glycol hydrophilic group is grafted on the main structure.Preparation method is as follows:resveratrol and epichlorohydrin are mixed and then condensed reaction is carried out, and branched structure resveratrol epoxy resin precursor is generated;Amino polyethylene glycol is added to resveratrol epoxy resin precursor and reaction is carried out in organic solvent, and grafted polyethylene glycol resveratrol epoxy resin derivative is generated;After reaction, organic solvent is removed and water is added, and water-soluble resveratrol epoxy resin emulsion is generated by stirring.Compared with prior art, the present application has the advantages of simple preparation method, green environmental protection, good emulsion stability and the like, and can be used as sizing agent for carbon fiber.

Description

Technical Field

[0001] This invention belongs to the field of epoxy resin technology, and in particular relates to a water-soluble resveratrol-based epoxy resin emulsion, its preparation method, and its application. Background Technology

[0002] Carbon fiber (CF) has a high strength-to-weight ratio, thus providing excellent strength and stiffness in carbon fiber reinforced polymer (CFRP) composites. However, the non-polar surface of carbon fibers significantly limits the bonding performance between the carbon fibers and the resin matrix, preventing the full realization of the potential properties of CFRP composites. Surface modification of carbon fibers is typically required, using a sizing agent to coat the carbon fiber surface. This improves surface wettability, increases surface reactive groups, and reduces fuzziness, facilitating subsequent fiber bundle weaving.

[0003] Research on epoxy resin sizing agents has been widely applied in the manufacturing of carbon fiber composite materials in fields such as automobile manufacturing and aerospace, supporting the development of the automotive and aerospace materials industries towards environmental protection, lightweighting, and high performance. However, common epoxy resins are generally insoluble in water, and emulsifiers are usually added for emulsification during use. However, organic emulsifiers have problems such as volatility, high price, and harm to human health. In addition, the traditional epoxy resin production process often uses bisphenol precursors, which are toxic and carcinogenic (such as bisphenol precursor glycidyl ester epoxy resin). The raw materials for these epoxy resins are basically derived from petrochemical products, which are non-renewable and harmful to the environment.

[0004] Furthermore, the development of waterborne epoxy resin sizing agents has become a social consensus. Among existing methods for preparing waterborne epoxy resin emulsions, directly grafting hydrophilic groups onto the epoxy resin is one of the most direct approaches. However, this method mostly involves grafting hydrophilic groups onto E51 epoxy resin via addition reactions. These reactions often require catalysts, resulting in cumbersome synthesis steps, complex and uncontrollable processes, and low yields, significantly limiting the practical production of waterborne epoxy resins. In addition, existing epoxy resin emulsions tend to separate after prolonged storage, exhibiting poor emulsion stability, which is detrimental to storage and use.

[0005] In summary, given the current state of epoxy resin technology, there is still a need to develop a green, environmentally friendly, and highly stable bio-based epoxy resin emulsion as a sizing agent for carbon fibers. Summary of the Invention

[0006] The purpose of this invention is to develop a green, environmentally friendly, and highly stable bio-based epoxy resin emulsion, and to provide a water-soluble resveratrol-based epoxy resin emulsion, its preparation method, and its application.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] This invention provides a water-soluble resveratrol-based epoxy resin emulsion, comprising resveratrol-based epoxy resin and water, wherein the content of the resveratrol-based epoxy resin is 15-20 wt%.

[0009] The main structure of the resveratrol-based epoxy resin is a branched structure formed by the reaction of resveratrol and epichlorohydrin, and polyethylene glycol hydrophilic groups are grafted onto the main structure.

[0010] Furthermore, the epoxy value of the resveratrol-based epoxy resin emulsion is 0.1-0.3.

[0011] Furthermore, the resveratrol-based epoxy resin emulsion has an average particle size of 5-50 nm.

[0012] Furthermore, the water-soluble resveratrol-based epoxy resin emulsion has self-emulsifying properties and maintains good stability even after standing for 60 days.

[0013] This invention also provides a method for preparing a water-soluble resveratrol-based epoxy resin emulsion, comprising the following steps:

[0014] S1: Resveratrol and epichlorohydrin are mixed and then subjected to a condensation reaction to generate a branched resveratrol-based epoxy resin precursor.

[0015] S2: Add amino polyethylene glycol to the resveratrol-based epoxy resin precursor and react in an organic solvent to generate a resveratrol-based epoxy resin derivative grafted with polyethylene glycol.

[0016] S3: After the reaction, remove the organic solvent and add water, stirring to generate a water-soluble resveratrol-based epoxy resin emulsion.

[0017] Further, in step S1, the molar ratio of resveratrol to epichlorohydrin is 1:(4-8).

[0018] Further, in step S1, the specific steps of the condensation reaction are as follows: stirring at 80-120℃ for 1-2 hours, followed by the dropwise addition of sodium hydroxide aqueous solution, and stirring continued for 4-6 hours.

[0019] Further, in step S2, the molar ratio of the resveratrol-based epoxy resin precursor to amino polyethylene glycol is 1:(0.5-1.25).

[0020] Furthermore, the molecular weight of the amino polyethylene glycol is 1000-3000 g / mol.

[0021] Further, in step S2, the organic solvent includes either chloroform or tetrahydrofuran, preferably chloroform.

[0022] Furthermore, in step S2, the reaction temperature is 50-70℃ and the reaction time is 5-6h.

[0023] Furthermore, in step S3, the stirring speed is 900-1100 rpm, preferably 1000 rpm.

[0024] The present invention also provides an application of a water-soluble resveratrol-based epoxy resin emulsion, wherein the water-soluble resveratrol-based epoxy resin emulsion is used as a sizing agent for carbon fibers.

[0025] Furthermore, the application specifically involves: using a water-soluble resveratrol-based epoxy resin emulsion as a sizing agent to coat the surface of carbon fibers, and then using the sizing carbon fibers to make a carbon fiber composite material with epoxy resin as the matrix.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) The present invention prepares a green and environmentally friendly resveratrol-based epoxy resin, and grafts hydrophilic polyethylene glycol long chains after some epoxy groups are ring-opened, which can greatly improve the water solubility of the resveratrol-based epoxy resin, and finally prepares a resveratrol-based epoxy resin emulsion with strong stability.

[0028] (2) In this invention, some epoxy groups are ring-opened and grafted with long polyethylene glycol chains onto resveratrol-based epoxy resin. The polyethylene glycol molecular chain contains water-soluble ethoxy structural units, and the hydrophilic polyethylene glycol long chain is introduced onto the epoxy resin molecular chain, thereby giving the resveratrol-based epoxy resin oleophilic and hydrophilic properties.

[0029] (3) When the modified resin is emulsified with water, the hydrophobic resveratrol-based epoxy resin molecular chains will aggregate into microparticles, while the hydrophilic polyethylene glycol long chains are distributed on the surface of these microparticles. The outer layer of the microparticles is hydrophilic and the inner layer is hydrophobic. They are dispersed in water in the form of tiny droplets to form an oil-in-water emulsion.

[0030] (4) The grafted polyethylene glycol of the present invention can not only enhance the hydrophilicity of epoxy resin molecules, but also increase the flexibility of molecular chains and reduce epoxy viscosity, thereby achieving the purpose of self-emulsification. Therefore, there is no need to add organic emulsifiers in the preparation process of waterborne epoxy resin emulsion.

[0031] (5) The epoxy resin emulsion of the present invention uses environmentally friendly resveratrol and does not use phenolic substances that are carcinogenic and derived from petrochemical products, resulting in less environmental pollution.

[0032] (6) The resveratrol-based epoxy resin emulsion of the present invention is simple and easy to operate, requires no catalyst, and the water-soluble epoxy resin emulsion prepared does not separate after being stored at room temperature for more than 60 days, and the emulsion still has good dispersibility.

[0033] (7) In this invention, resveratrol-based epoxy resin emulsion is used as a sizing agent in the preparation of carbon fiber composite materials, which can significantly improve the stiffness and bundle properties of carbon fibers, reduce the amount of fuzz, and facilitate the subsequent weaving of fiber bundles. Attached Figure Description

[0034] Figure 1 The image shows the 1H NMR spectrum of the resveratrol-based epoxy resin from Example 1.

[0035] Figure 2 The image shows the 1H NMR spectrum of the resveratrol-based epoxy resin grafted with polyethylene glycol in Example 1.

[0036] Figure 3 This is a particle size distribution curve of the water-soluble resveratrol-based epoxy resin emulsion in Example 1.

[0037] Figure 4 Scanning electron microscope images of carbon fibers before and after sizing with the resveratrol-based epoxy resin emulsion of Example 1.

[0038] Figure 5 The results show the contact angle test results before and after carbon fiber sizing. Detailed Implementation

[0039] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0040] Unless otherwise specified, the reagents, methods, instruments, and equipment used in this invention are conventional in the art. Unless otherwise specified, the reagents and materials used in the following examples are all commercially available.

[0041] Example 1:

[0042] This embodiment provides a water-soluble resveratrol-based epoxy resin emulsion and its application in the preparation of adhesives, wherein the reaction equation for preparing the resveratrol-based epoxy resin is as follows:

[0043]

[0044] The preparation method is as follows:

[0045] S1: Add 0.1 mol of resveratrol and 0.6 mol of epichlorohydrin to the reaction vessel and stir at 100°C and 500 rpm for 2 hours. Slowly add 50 mL of sodium hydroxide aqueous solution (20% w / w) to the reactants and continue stirring for another 5 hours, then cool to room temperature. Dilute the suspension with dichloromethane, remove the upper aqueous phase, wash the organic phase three times with distilled water and dry with anhydrous magnesium sulfate to obtain the resveratrol-based epoxy resin precursor (denoted as epoxy resin A), with an epoxy value of 0.4-0.5 and a mean degree of polymerization n of 1.

[0046] S2: 0.014 mol of epoxy resin precursor and 0.01 mol of amino polyethylene glycol 1000 were added to a reaction vessel (the molar ratio of epoxy resin precursor to amino polyethylene glycol was 1:0.71), followed by the addition of 15 mL of chloroform as a solvent. The mixture was stirred at 60 °C for 5 hours. The chloroform was then evaporated to remove it, and 80-100 g of deionized water was added. The mixture was stirred at 1000 rpm and sonicated at 100 Hz for 10 min. After the product dissolved, a light milky white, stable emulsion was obtained. The solid content of the aqueous epoxy emulsion was 15%-20%.

[0047] In this embodiment, the 1H NMR spectrum of the resveratrol-based epoxy resin precursor is as follows: Figure 1 As shown, this demonstrates the successful preparation of the resveratrol-based epoxy resin precursor in this embodiment. The 1H NMR spectrum of the product after partial epoxy group ring opening is shown below. Figure 2 As shown, a significant characteristic peak of the ethoxy structural unit is present at 3.6 ppm, indicating that polyethylene glycol long-chain groups were successfully grafted onto some of the epoxy groups of the resveratrol-based epoxy resin after ring opening.

[0048] In this embodiment, the epoxy value of the resveratrol-based epoxy resin was determined to be 0.1-0.3 using the hydrochloric acid-acetone method. The epoxy value affects the curing behavior, bond strength, and compatibility with carbon fibers of the sizing agent, as well as the resin's solubility and reactivity. A higher epoxy value is beneficial for improving reactivity and the bond strength between the carbon fiber and the resin matrix, while a lower epoxy value is beneficial for improving the emulsion's water solubility and stability. The average particle size of the emulsion was measured to be 4.7 nm using dynamic light scattering (DLS). Figure 3 As shown in the figure, this indicates that a relatively stable nanoemulsion system has been formed, which can fully wet the carbon fiber bundles, form a uniform sizing layer, and improve the surface roughness of the carbon fibers.

[0049] Example 2:

[0050] This embodiment provides a water-soluble resveratrol-based epoxy resin emulsion, the preparation method of which is as follows:

[0051] S1: Add 0.1 mol of resveratrol and 0.6 mol of epichlorohydrin to the reaction vessel and stir at 100°C and 500 rpm for 2 hours. Slowly add 50 mL of sodium hydroxide aqueous solution (20% w / w) to the reactants and react for another 5 hours with continuous stirring, then cool to room temperature. Dilute the suspension with dichloromethane, remove the upper aqueous phase, wash the organic phase three times with distilled water and dry with anhydrous magnesium sulfate to obtain a resveratrol-based epoxy resin precursor with an epoxy value of 0.4-0.5 and a mean degree of polymerization (n) of 1.

[0052] S2: 0.028 mol of epoxy resin precursor and 0.02 mol of amino polyethylene glycol 2000 were added to a reaction vessel, followed by 15 mL of chloroform as solvent. The mixture was stirred at 60 °C for 5 hours. The chloroform was then evaporated to remove it, and 150-200 g of deionized water was added. The mixture was stirred at 1000 rpm and sonicated at 100 Hz for 10 min. After the product dissolved, a light milky white and stable emulsion was obtained.

[0053] The aqueous epoxy emulsion prepared in this embodiment has a solid content of 15%-20%, an epoxy value of 0.1-0.3, and an average particle size of 4-50 nm.

[0054] Example 3:

[0055] This embodiment provides a water-soluble resveratrol-based epoxy resin emulsion, the preparation method of which is as follows:

[0056] S1: Add 0.1 mol of resveratrol and 0.6 mol of epichlorohydrin to the reaction vessel and stir at 100°C and 500 rpm for 2 hours. Slowly add 50 mL of sodium hydroxide aqueous solution (20% w / w) to the reactants and react for another 5 hours with continuous stirring, then cool to room temperature. Dilute the suspension with dichloromethane, remove the upper aqueous phase, wash the organic phase three times with distilled water and dry with anhydrous magnesium sulfate to obtain a resveratrol-based epoxy resin precursor with an epoxy value of 0.4-0.5 and a mean degree of polymerization (n) of 1.

[0057] S2: 0.042 mol of epoxy resin precursor and 0.03 mol of amino polyethylene glycol 3000 were added to a reaction vessel, followed by 25 mL of chloroform as solvent. The mixture was stirred at 60 °C for 5 hours. The chloroform was then evaporated to remove the chloroform, and 150-200 g of deionized water was added. The mixture was stirred at 1000 rpm and sonicated at 100 Hz for 10 min. After the product dissolved, a light milky white and stable emulsion was obtained.

[0058] The aqueous epoxy emulsion prepared in this embodiment has a solid content of 15%-20%, an epoxy value of 0.1-0.3, and an average particle size of 4-50 nm.

[0059] Comparative Example 1:

[0060] This comparative example provides a resveratrol-based epoxy resin emulsion without grafted polyethylene glycol.

[0061] S1: Add 0.1 mol of resveratrol and 0.6 mol of epichlorohydrin to the reaction vessel and stir at 100°C and 500 rpm for 2 hours. Slowly add 50 mL of sodium hydroxide aqueous solution (20% w / w) to the reactants and react for another 5 hours with continuous stirring, then cool to room temperature. Dilute the suspension with dichloromethane, remove the upper aqueous phase, wash the organic phase three times with distilled water, and dry with anhydrous magnesium sulfate. A resveratrol-based epoxy resin precursor with an epoxy value of 0.4-0.5 is obtained.

[0062] S2: 0.042 mol of epoxy resin precursor was added to a reaction vessel, followed by 250-300 g of deionized water. The mixture was stirred at 1000 rpm and sonicated at 100 Hz for 10 min. The product was found to separate into layers and could not form a stable, light milky white emulsion. This indicates that resveratrol-based epoxy resin is not water-soluble when not grafted with hydrophilic polyethylene glycol.

[0063] Comparative Example 2:

[0064] This comparative example provides a resveratrol-based epoxy resin emulsion, and the specific preparation method is as follows:

[0065] S1: Add 0.1 mol of resveratrol and 0.6 mol of epichlorohydrin to the reaction vessel and stir at 100°C and 500 rpm for 2 hours. Slowly add 50 mL of sodium hydroxide aqueous solution (20% w / w) to the reactants and react for another 5 hours with continuous stirring, then cool to room temperature. Dilute the suspension with dichloromethane, remove the upper aqueous phase, wash the organic phase three times with distilled water, and dry with anhydrous magnesium sulfate. A resveratrol-based epoxy resin precursor with an epoxy value of 0.4-0.5 is obtained.

[0066] S2: 0.028 mol of epoxy resin precursor and 0.005 mol of amino polyethylene glycol 1000 were added to a reaction vessel, followed by 15 mL of chloroform as solvent. The mixture was stirred at 60 °C for 5 hours. The chloroform was then evaporated to remove the chloroform, and 150-200 g of deionized water was added. The mixture was stirred at 1000 rpm and sonicated at 100 Hz for 10 minutes. The product partially dissolved, and a white flocculent precipitate formed. This demonstrates that when the amount of polyethylene glycol grafted onto the resveratrol-based epoxy resin is insufficient, the product still exhibits poor water solubility and cannot be formulated into a stable water-soluble epoxy resin emulsion.

[0067] Comparative Example 3:

[0068] This comparative example provides a resveratrol-based epoxy resin emulsion, and the specific preparation method is as follows:

[0069] S1: Add 0.1 mol of resveratrol and 0.6 mol of epichlorohydrin to the reaction vessel and stir at 100°C and 500 rpm for 2 hours. Slowly add 50 mL of sodium hydroxide aqueous solution (20% w / w) to the reactants and react for another 5 hours with continuous stirring, then cool to room temperature. Dilute the suspension with dichloromethane, remove the upper aqueous phase, wash the organic phase three times with distilled water, and dry with anhydrous magnesium sulfate. A resveratrol-based epoxy resin precursor with an epoxy value of 0.4-0.5 is obtained.

[0070] S2: 0.028 mol of epoxy resin precursor and 0.04 mol of amino polyethylene glycol 1000 were added to a reaction vessel, followed by 15 mL of chloroform as solvent. The mixture was stirred at 60 °C for 5 hours. The chloroform was then evaporated to remove it, and 150-200 g of deionized water was added. The mixture was stirred at 1000 rpm and sonicated at 100 Hz for 10 min. After the product dissolved, a light milky white and stable emulsion was obtained.

[0071] The aqueous epoxy emulsion prepared in this comparative example has a solid content of 15%-20%, an epoxy value of 0.05, and an average particle size of 4-50 nm.

[0072] The present invention also conducted the following stability tests on the resveratrol-based epoxy resin emulsions of Examples 1-3 and Comparative Examples 1-3:

[0073] (1) Centrifugal stability: The emulsion was diluted with water to a solid content of 2% and then centrifuged at 6000 rpm for 30 min. The stability of the emulsion was then observed.

[0074] sample Centrifugal stability 1 Stablize 2 Stablize 3 Stablize Comparative Example 1 Layering Comparative Example 2 Layering Comparative Example 3 Stablize

[0075] (2) Static stability: Dilute the emulsion with water to 2% solid content, take 10ml and let it stand at room temperature for 60 days to observe the stability of the emulsion.

[0076]

[0077]

[0078] As shown in the table above, the water-soluble resveratrol-based epoxy resin emulsions prepared in Examples 1-3 exhibit good centrifugal stability and maintain good static stability even after 60 days. In Comparative Examples 1 and 2, when too little or no polyethylene glycol was grafted, the resulting epoxy resin had poor water solubility, easily causing precipitation and disrupting the stable emulsion system. In Comparative Example 3, even with excessive polyethylene glycol grafting, the entire emulsion system maintained good stability.

[0079] The present invention also prepared resveratrol-based epoxy resin emulsions according to the preparation method of Example 1, as described in the following examples.

[0080] Example 4:

[0081] The preparation methods of this embodiment and Example 1 are basically the same, except that the amount of amino polyethylene glycol 1000 used in this embodiment is 0.008 mol, that is, the molar ratio of epoxy resin precursor to amino polyethylene glycol is 1:0.57.

[0082] Example 5:

[0083] The preparation methods of this embodiment and Example 1 are basically the same, except that the amount of amino polyethylene glycol 1000 used in this embodiment is 0.012 mol, that is, the molar ratio of epoxy resin precursor to amino polyethylene glycol is 1:0.86.

[0084] Example 6:

[0085] The preparation methods of this embodiment and Example 1 are basically the same, except that the amount of amino polyethylene glycol 1000 used in this embodiment is 0.014 mol, that is, the molar ratio of epoxy resin precursor to amino polyethylene glycol is 1:1.

[0086] The present invention uses the water-soluble resveratrol-based epoxy resin emulsion obtained in Examples 1 and 4-6 to sizing carbon fibers. The specific preparation steps are as follows: the sizing agent is added to the impregnation tank, the unsized carbon fibers enter the impregnation tank through the yarn guide roller, the carbon fibers are pulled out from the impregnation tank at a constant rate, dried in a blower at 150°C, and then wound in a take-up spool.

[0087] The following tests were conducted after sizing:

[0088] (1) The fiber sizing amount was tested according to the national standard GB / T 29761-2022. The fiber sizing amount was determined by Soxhlet extraction.

[0089] (2) Fiber bundle property test referenced patent CN114720467A. The sized fibers were left to stand at 24℃ for 12 hours, with a fiber length of 300±3mm. The ends of the fiber were flexibly fixed, and the middle section of the fiber was spread outwards from the centerline to 30mm from the centerline using vernier calipers. This was fixed for 30 seconds, and the vernier calipers were removed and flexibly fixed from the side where the fiber was removed. After stabilization, the distance from the centerline after the middle section of the fiber rebounded was calculated, and the fiber resilience rate was used as the evaluation standard for bundle property. Five discontinuous sections of each fiber sample were tested repeatedly, and the average value was taken.

[0090] (3) Fiber stiffness test was conducted according to national standard GB / T 7690.4-2013. The sized fibers were left to stand at 24℃ for 12 hours. The fiber length was 450±5mm. The midpoint of the fiber was suspended on a cylinder with a diameter of 16mm, and the distance between the fiber ends was measured after 30 seconds. Three discontinuous sections of each fiber sample were tested repeatedly, and the average value was taken.

[0091] (4) The contact angle between the carbon fiber surface and water after sizing was studied using a high-speed fully automatic contact angle measuring instrument. The carbon fiber bundle was fixed on the test platform, and the contact angle between the carbon fiber surface and deionized water was measured. Each sample was tested 3 times, and the average value was taken. Figure 5 (Only the contact angle results from one of the tests are shown).

[0092] (5) The fiber filament content test adopts the enterprise standard Q / 110000BH 006-2018. The test fiber length is 4m, the mass of the pressure weight and pad is 500g, and the tensile speed is 0.5m / min. Each sample is tested 3 times and the average value is taken. The mass of the polyurethane foam used for testing is 1.8±0.1g.

[0093] In the above tests, the emulsions obtained in Examples 1, 4, 5, and 6 were designated as EM-1 to EM-4, respectively, and the sizing-free filaments were designated as EM-0. The test results for sizing T800 carbon fiber are shown in Table 1. The results show that sizing with the water-soluble resveratrol-based epoxy resin emulsions of the above examples significantly improved the stiffness and bundle cohesion of the fibers, reduced the amount of fuzz, and facilitated subsequent weaving processing of the fiber bundles. Sizing significantly reduced the contact angle of the carbon fiber surface, improved surface wettability, and increased the number of polar groups on the surface. Figure 4 As can be seen from the SEM images, compared with unsized carbon fibers, the grooves on the surface of carbon fibers became shallower and the surface defects were reduced after the water-soluble resveratrol-based epoxy resin emulsion of Example 1 was applied to the carbon fiber surface.

[0094] Table 1. Performance test results of carbon fiber before and after sizing.

[0095]

[0096] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A water-soluble resveratrol-based epoxy resin emulsion, characterized in that, It includes resveratrol-based epoxy resin and water, wherein the content of resveratrol-based epoxy resin is 15-20 wt%, and the epoxy value of the resveratrol-based epoxy resin emulsion is 0.1-0.3; The main structure of the resveratrol-based epoxy resin is a branched structure formed by the reaction of resveratrol and epichlorohydrin, and polyethylene glycol hydrophilic groups are grafted onto the main structure. The water-soluble resveratrol-based epoxy resin emulsion has self-emulsifying properties and an average particle size of 4-50 nm. The preparation method of the water-soluble resveratrol-based epoxy resin emulsion includes the following steps: S1: Resveratrol and epichlorohydrin are mixed and then subjected to a condensation reaction to generate a branched resveratrol-based epoxy resin precursor. S2: Add amino polyethylene glycol to the resveratrol-based epoxy resin precursor and react it in an organic solvent to generate a resveratrol-based epoxy resin derivative grafted with polyethylene glycol; the molar ratio of the resveratrol-based epoxy resin precursor to amino polyethylene glycol is 1:(0.5-1.25). S3: After the reaction, remove the organic solvent and add water, stirring to generate a water-soluble resveratrol-based epoxy resin emulsion; The water-soluble resveratrol-based epoxy resin emulsion is used as a sizing agent for carbon fibers to improve fiber stiffness and bundle cohesion, and reduce fuzziness.

2. The water-soluble resveratrol-based epoxy resin emulsion according to claim 1, characterized in that, In step S1, the molar ratio of resveratrol to epichlorohydrin is 1:(4-8).

3. The water-soluble resveratrol-based epoxy resin emulsion according to claim 1, characterized in that, In step S1, the specific steps of the condensation reaction are as follows: stirring at 80-120℃ for 1-2 hours, followed by the dropwise addition of sodium hydroxide aqueous solution, and stirring for another 4-6 hours.

4. The water-soluble resveratrol-based epoxy resin emulsion according to claim 1, characterized in that, In step S2, the reaction temperature is 50-70℃ and the reaction time is 5-6h.

5. The water-soluble resveratrol-based epoxy resin emulsion according to claim 1, characterized in that, In step S3, the stirring speed is 900-1100 rpm.

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