Graphene-based negative ion antibacterial egg tray and preparation method thereof

Abstract

The invention relates to the technical field of antibacterial materials, in particular to a graphene-based negative ion antibacterial egg tray and a preparation method thereof. The preparation method comprises the following steps: step one, ultrasonically dispersing graphene oxide in N, N-dimethylformamide to form a dispersion liquid, heating to 140-150 DEG C, adding N-methylimidazole, dropwise adding cardanol glycidyl ester for 30-60 minutes, continuously reacting for 22-24 hours, cooling to room temperature, centrifuging, washing and drying to obtain modified graphene; 2, uniformly mixing epoxy resin, modified graphene, tourmaline, titanium dioxide, deionized water, a flatting agent and a curing agent to obtain an antibacterial coating; 3, the regenerated paper pulp base body is soaked in the antibacterial coating, taken out and dried, an antibacterial coating is formed, an egg support is processed through a hot press forming technology, plasma surface treatment is conducted on the formed egg support, and the negative ion antibacterial egg support with the excellent mechanical property is obtained.

Description

Technical Field

[0001] This invention relates to the field of antibacterial materials technology, specifically to a graphene-based negative ion antibacterial egg tray and its preparation method. Background Technology

[0002] With increasing attention to food safety and packaging materials, traditional egg trays face significant challenges in ensuring egg quality and safety. Most traditional egg trays are made of materials such as pulp or plastic, which, while providing some cushioning and physical protection, lack sufficient antibacterial properties to inhibit the growth of microorganisms (such as Salmonella) on the eggshell surface. Furthermore, they are prone to accelerating egg spoilage in humid environments, and vibrations during transportation can easily cause microcracks in the eggshell, increasing the risk of microbial contamination.

[0003] Graphene, as a novel two-dimensional material, possesses excellent electrical, thermal, and mechanical properties, exhibiting high specific surface area, superior chemical stability, and outstanding mechanical strength. Negative ions can react with harmful substances in the air, purifying and sterilizing it. However, traditional negative ion-releasing materials suffer from low release efficiency and poor stability, limiting their practical applications.

[0004] Therefore, researching and developing a graphene-based negative ion antibacterial egg tray and its preparation method is of great significance. Summary of the Invention

[0005] The purpose of this invention is to provide a graphene-based negative ion antibacterial egg tray and its preparation method, so as to solve the problems raised in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A method for preparing a graphene-based negative ion antibacterial egg tray includes the following steps: Step 1: Graphene oxide is ultrasonically dispersed in N,N-dimethylformamide to form a dispersion. The temperature is raised to 140-150℃, N-methylimidazole is added, and cashew phenol glycidyl ester is added dropwise over 30-60 minutes. The reaction continues for 22-24 hours. After cooling to room temperature, the modified graphene is obtained by centrifugation, washing, and drying. Step 2: Mix epoxy resin, modified graphene, tourmaline, titanium dioxide, deionized water, leveling agent and curing agent evenly to obtain antibacterial coating; Step 3: The recycled pulp matrix is ​​impregnated in antibacterial coating, removed, dried to form an antibacterial coating, and processed into an egg tray using hot pressing technology. The formed egg tray is then subjected to plasma surface treatment to obtain a graphene-based negative ion antibacterial egg tray.

[0007] In a more optimized scheme, the concentration of the dispersion in step one is 5-10 mg / mL.

[0008] In a more optimized scheme, the mass ratio of graphene oxide, N-methylimidazole and cashew phenol glycidyl ester is 1:(0.1-0.3):(2-4).

[0009] A more optimized method for preparing the cashew phenol glycidyl ester is as follows: Under nitrogen protection, cashew nut shellac, triethylamine, 4-methoxyphenol, 4-dimethylaminopyridine, and dichloromethane were mixed thoroughly. A mixed solution of succinyl chloride and dichloromethane was added dropwise over 1-2 hours in an ice bath. The mixture was reacted at 40-50°C for 4-6 hours. The mixture was filtered to obtain a filtrate, which was then washed with distilled water and rotary evaporated to obtain cashew nut shellac succinate. Cashew nut shellac succinate, formic acid, toluene, p-toluenesulfonic acid, and hydrogen peroxide were mixed thoroughly and reacted at 60-70°C for 5-7 hours. After filtration, washing, and rotary evaporation, cashew nut shellac glycidyl ester was obtained.

[0010] In the above technical solution, cashew phenol and succinyl chloride, which are biomass resources, are used as raw materials to prepare cashew phenol succinate through esterification reaction, introducing dynamic ester bonds; then, hydrogen peroxide is used to oxidize the double bonds in cashew phenol succinate to epoxy groups to obtain cashew phenol glycidyl ester.

[0011] A more optimized scheme is that the cashew phenol, triethylamine, 4-methoxyphenol, 4-dimethylaminopyridine and dichloromethane are in the ratio of 1: (0.3-0.5): (0.003-0.005): (0.01-0.03): (2-4).

[0012] In a more optimized scheme, the mass of succinyl chloride is 0.25-0.35 times the mass of cashew phenol; the mass ratio of succinyl chloride to dichloromethane is 1:(2-3).

[0013] In a more optimized scheme, the mass ratio of cashew phenolic succinate, formic acid, toluene, p-toluenesulfonic acid and hydrogen peroxide is 1:(0.3-0.5):(3-5):(0.01-0.03):(1.6-1.8).

[0014] A more optimized solution is that the antibacterial coating comprises the following raw materials in parts by weight: 40-50 parts epoxy resin, 5-10 parts modified graphene oxide, 6-12 parts curing agent, 3-8 parts tourmaline, 2-5 parts titanium dioxide, 0.2-0.5 parts leveling agent, and 10-20 parts deionized water.

[0015] In a more optimized solution, the tourmaline undergoes a modification treatment, the specific process of which is as follows: Step 1: Mix tourmaline, anhydrous ethanol and deionized water evenly, heat to 50-70℃, introduce nitrogen gas, add vinyltrimethoxysilane, react for 4-6 hours, filter, wash and dry to obtain vinyl tourmaline; Step 2: Dissolve chitosan in acetic acid solution, add a mixed solution of caffeic acid, carbodiimide hydrochloride, N-hydroxysuccinimide and ethanol, react for 22-24 hours, and obtain modified chitosan after centrifugation, dialysis and drying. Step 3: Mix vinyl tourmaline and deionized water evenly, add methyl methacrylate, methacrylamide and modified chitosan, purge with nitrogen gas, add potassium persulfate, and react at 70-80℃ for 10-12 hours. After centrifugation, washing and drying, modified tourmaline is obtained.

[0016] In a more optimized scheme, in step 1, the mass ratio of tourmaline, anhydrous ethanol, deionized water and vinyltrimethoxysilane is 1:(15-20):(3-5):(1-2).

[0017] In a more optimized scheme, in step 2, the mass ratio of chitosan, acetic acid solution and caffeic acid is 1:(50-60):(0.2-0.4), and the concentration of acetic acid solution is 1wt%.

[0018] The optimized scheme has a mass ratio of caffeic acid, carbodiimide hydrochloride, N-hydroxysuccinimide and ethanol of 1:(1.0-1.2):(0.5-0.7):(20-40).

[0019] In a more optimized scheme, in step 3, the mass ratio of the vinyl tourmaline to deionized water is 1:(50-100).

[0020] In a more optimized scheme, the mass ratio of vinyl tourmaline, methyl methacrylate, methacrylamide and modified chitosan is 1:(1-2):(2-4):(0.5-1.5).

[0021] In a more optimized scheme, the amount of potassium persulfate used is 1-3% of the total mass of vinyl tourmaline, methyl methacrylate, methacrylamide and modified chitosan.

[0022] In a more optimized embodiment, the curing agent is one or more of ethylenediamine, diethylenetriamine, triethylenetetramine, and diethylaminopropylamine.

[0023] In a more optimized scheme, the thickness of the antibacterial coating is 50-150 μm.

[0024] A more optimized solution is that the hot pressing process conditions are: temperature 120-150℃, pressure 2-5MPa, and time 5-10min.

[0025] A more optimized scheme is that the plasma treatment process conditions are: power 300-500W, time 60-120s, and Ar / O2 gas flow ratio of 1:4.

[0026] Compared with the prior art, the beneficial effects of the present invention are: 1. The present invention relates to a graphene-based negative ion antibacterial egg tray and its preparation method, which uses cashew phenol glycidyl ester as a hydrophobic monomer and introduces hydrophobic carbon chains on the surface of graphene oxide through covalent bonding of epoxy and carboxylic acid, effectively improving its dispersibility and compatibility in epoxy resin matrix, significantly reducing agglomeration, thereby improving the stability of the material in humid environments and helping to reduce bacterial growth. In this solution, to further improve the antibacterial and mechanical properties of the egg tray, the tourmaline is modified as follows: First, the tourmaline powder is surface-modified using vinyltrimethoxysilane (KH-171), a silane coupling agent containing carbon-carbon double bonds, to obtain vinyl tourmaline. Then, through free radical copolymerization, methyl methacrylate, methacrylamide, and modified chitosan are copolymerized and coated onto the surface of the tourmaline to form an amino-containing organic layer. This not only improves the dispersibility and interfacial bonding of tourmaline in epoxy resin but also further enhances its negative ion release characteristics, synergistically strengthening the antibacterial and antioxidant properties of the material. Chitosan is a natural biodegradable material with excellent antibacterial, biocompatibility, and anti-infective activity. By grafting chitosan with caffeic acid, its bioactivity and preservation function are further enhanced, giving the egg tray continuous and efficient antibacterial capabilities, making it suitable for high-hygiene scenarios such as food packaging.

[0027] 2. This invention discloses a graphene-based negative ion antibacterial egg tray and its preparation method. Using an economical and environmentally friendly recycled pulp matrix as the main framework, it achieves the recycling of waste resources. Simultaneously, an antibacterial coating is constructed on its surface. On one hand, the layered structure of modified graphene forms a physical barrier within the coating, preventing microbial penetration. On the other hand, the tourmaline coating continuously releases negative ions, inactivating microbial proteins. The synergistic effect of these two processes significantly enhances the broad-spectrum antibacterial efficiency and durability of the material, far exceeding the effect of a single antibacterial mechanism. The preparation process employs hot-pressing molding technology to ensure the mechanical strength of the egg tray matrix. Finally, surface plasma treatment activates and cleans the egg tray surface, significantly improving the interfacial bonding and adhesion between the antibacterial coating and the recycled pulp matrix, further enhancing the stability of the antibacterial performance. The antibacterial egg tray prepared by this invention possesses excellent biodegradability and environmental friendliness. The preparation process is mature, easy to scale up, and has good market application prospects. Detailed Implementation

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Unless otherwise specified, all quantities below are by weight. It should be noted that there are no special restrictions on the manufacturers of the raw materials involved in this invention. Exemplary examples include (in this embodiment) graphene oxide: DN-20DY, from Zhejiang Zhitai Nanomaterials Co., Ltd.; epoxy resin: E51, CYD-128, from Baling Petrochemical; tourmaline: 1-5μm, from Lingshou County Yancheng Mineral Products Processing Plant; titanium dioxide: Chemours Ti-Pure™ R-902+; leveling agent: Keying KYC-615; curing agent: triethylenetetramine, from Aladdin Chemical Reagents.

[0030] Example 1: A method for preparing a graphene-based negative ion antibacterial egg tray, comprising the following processes: Step 1: Disperse 5 parts of graphene oxide in N,N-dimethylformamide by ultrasonication to form a 5 mg / mL dispersion. Heat to 140℃, add 0.5 parts of N-methylimidazole, and dropwise add 10 parts of cashew phenol glycidyl ester. The addition is completed in 30 min. Continue the reaction for 22 h, cool to room temperature, and obtain modified graphene after centrifugation, washing, and drying. Step 2: Mix 40 parts epoxy resin, 5 parts modified graphene, 3 parts tourmaline, 2 parts titanium dioxide, 10 parts deionized water, 0.2 parts leveling agent and 6 parts curing agent evenly to obtain antibacterial coating; Step 3: The recycled pulp matrix is ​​impregnated in antibacterial coating, removed, and dried to form an antibacterial coating. It is then processed into an egg tray using hot pressing molding technology (temperature 120℃, pressure 2MPa, time 5min). The molded egg tray is then subjected to plasma surface treatment (power 300W, time 60s, Ar / O2 gas flow ratio of 1:4) to obtain a graphene-based negative ion antibacterial egg tray. The preparation method of cashew phenol glycidyl ester is as follows: Under nitrogen protection, 10 parts of cashew nut shellac, 3 parts of triethylamine, 0.03 parts of 4-methoxyphenol, 0.1 parts of 4-dimethylaminopyridine, and 20 parts of dichloromethane were mixed thoroughly. Under ice bath conditions, a mixed solution of 2.5 parts of succinyl chloride and 5 parts of dichloromethane was added dropwise over 1 hour. The mixture was reacted at 40°C for 4 hours, filtered, and the filtrate was washed with distilled water and then rotary evaporated to obtain cashew nut shellac succinate. 10 parts of cashew nut shellac succinate, 3 parts of formic acid, 30 parts of toluene, 0.1 parts of p-toluenesulfonic acid, and 16 parts of hydrogen peroxide were mixed thoroughly and reacted at 60°C for 5 hours. After filtration, washing, and rotary evaporation, cashew nut shellac glycidyl ester was obtained.

[0031] Example 2: A method for preparing a graphene-based negative ion antibacterial egg tray, comprising the following processes: Step 1: Disperse 8 parts of graphene oxide in N,N-dimethylformamide by ultrasonication to form an 8 mg / mL dispersion. Heat to 145℃, add 1.6 parts of N-methylimidazole, and dropwise add 24 parts of cashew phenol glycidyl ester. The addition is completed in 40 min, and the reaction continues for 23 h. After cooling to room temperature, the modified graphene is obtained after centrifugation, washing, and drying. Step 2: Mix 45 parts epoxy resin, 8 parts modified graphene, 5 parts tourmaline, 4 parts titanium dioxide, 15 parts deionized water, 0.3 parts leveling agent and 10 parts curing agent evenly to obtain antibacterial coating. Step 3: The recycled pulp matrix is ​​impregnated in antibacterial coating, removed, and dried to form an antibacterial coating. It is then processed into an egg tray using hot pressing molding technology (temperature 130℃, pressure 4MPa, time 8min). The molded egg tray is then subjected to plasma surface treatment (power 400W, time 80s, Ar / O2 gas flow ratio of 1:4) to obtain a graphene-based negative ion antibacterial egg tray. The preparation method of cashew phenol glycidyl ester is as follows: Under nitrogen protection, 24 parts of cashew nut shellac, 9.6 parts of triethylamine, 0.96 parts of 4-methoxyphenol, 0.48 parts of 4-dimethylaminopyridine, and 72 parts of dichloromethane were mixed thoroughly. Under ice bath conditions, a mixed solution of 7.2 parts of succinyl chloride and 18 parts of dichloromethane was added dropwise over 1.5 hours. The mixture was reacted at 45°C for 5 hours, filtered, and the filtrate was washed with distilled water and then rotary evaporated to obtain cashew nut shellac succinate. 24 parts of cashew nut shellac succinate, 9.6 parts of formic acid, 96 parts of toluene, 0.48 parts of p-toluenesulfonic acid, and 40 parts of hydrogen peroxide were mixed thoroughly and reacted at 65°C for 6 hours. After filtration, washing, and rotary evaporation, cashew nut shellac glycidyl ester was obtained. Tourmaline undergoes modification treatment, the specific process of which is as follows: Step 1: Mix 5 parts tourmaline, 75 parts anhydrous ethanol and 45 parts deionized water evenly, heat to 50°C, introduce nitrogen gas, add 5 parts vinyltrimethoxysilane, react for 4 hours, filter, wash and dry to obtain vinyl tourmaline. Step 2: Dissolve 2.5 parts of chitosan in 125 parts of 1wt% acetic acid solution, add 0.5 parts of caffeic acid, 0.5 parts of carbodiimide hydrochloride, 0.25 parts of N-hydroxysuccinimide and 10 parts of ethanol mixed solution, react for 22 h, and obtain modified chitosan after centrifugation, dialysis and drying. Step 3: Mix 5 parts of vinyl tourmaline and 250 parts of deionized water evenly, add 5 parts of methyl methacrylate, 10 parts of methacrylamide and 2.5 parts of modified chitosan, purge with nitrogen gas, add 0.3 parts of potassium persulfate, react at 70°C for 10 hours, centrifuge, wash and dry to obtain modified tourmaline.

[0032] Example 3: A method for preparing a graphene-based negative ion antibacterial egg tray, comprising the following processes: Step 1: 10 parts of graphene oxide were ultrasonically dispersed in N,N-dimethylformamide to form a 10 mg / mL dispersion. The temperature was raised to 150℃, 3 parts of N-methylimidazole were added, and 40 parts of cashew phenol glycidyl ester were added dropwise over 60 min. The reaction was continued for 24 h. After cooling to room temperature, the modified graphene was obtained by centrifugation, washing, and drying. Step 2: Mix 50 parts epoxy resin, 10 parts modified graphene, 8 parts tourmaline, 5 parts titanium dioxide, 20 parts deionized water, 0.5 parts leveling agent and 12 parts curing agent evenly to obtain antibacterial coating. Step 3: The recycled pulp matrix is ​​impregnated in antibacterial coating, removed, and dried to form an antibacterial coating. It is then processed into an egg tray using hot pressing molding technology (temperature 150℃, pressure 5MPa, time 10min). The molded egg tray is then subjected to plasma surface treatment (power 500W, time 120s, Ar / O2 gas flow ratio of 1:4) to obtain a graphene-based negative ion antibacterial egg tray. The preparation method of cashew phenol glycidyl ester is as follows: Under nitrogen protection, 40 parts of cashew nut shellac, 20 parts of triethylamine, 0.2 parts of 4-methoxyphenol, 1.2 parts of 4-dimethylaminopyridine, and 160 parts of dichloromethane were mixed evenly. Under ice bath conditions, a mixed solution of 14 parts of succinyl chloride and 42 parts of dichloromethane was added dropwise over 2 hours. The mixture was reacted at 50°C for 6 hours, filtered, and the filtrate was washed with distilled water and then rotary evaporated to obtain cashew nut shellac succinate. 40 parts of cashew nut shellac succinate, 20 parts of formic acid, 200 parts of toluene, 1.2 parts of p-toluenesulfonic acid, and 72 parts of hydrogen peroxide were mixed evenly and reacted at 70°C for 7 hours. After filtration, washing, and rotary evaporation, cashew nut shellac glycidyl ester was obtained. Tourmaline undergoes modification treatment, the specific process of which is as follows: Step 1: Mix 8 parts tourmaline, 160 parts anhydrous ethanol and 40 parts deionized water evenly, heat to 70°C, introduce nitrogen gas, add 16 parts vinyltrimethoxysilane, react for 6 hours, filter, wash and dry to obtain vinyl tourmaline. Step 2: Dissolve 12 parts of chitosan in 720 parts of 1wt% acetic acid solution, add a mixed solution of 4.8 parts of caffeic acid, 5.76 parts of carbodiimide hydrochloride, 3.36 parts of N-hydroxysuccinimide and 192 parts of ethanol, react for 24 h, and obtain modified chitosan after centrifugation, dialysis and drying. Step 3: Mix 8 parts of vinyl tourmaline and 800 parts of deionized water evenly, add 16 parts of methyl methacrylate, 32 parts of methacrylamide and 12 parts of modified chitosan, purge with nitrogen gas, add 2 parts of potassium persulfate, react at 80°C for 12 hours, and after centrifugation, washing and drying, obtain modified tourmaline.

[0033] Comparative Example 1: A method for preparing a graphene-based negative ion antibacterial egg tray, comprising the following processes: Compared with Example 2, Comparative Example 1 replaced the modified graphene with the same mass of graphene oxide, and the other steps were the same as in Example 2.

[0034] Comparative Example 2: A method for preparing a graphene-based negative ion antibacterial egg tray, comprising the following processes: Compared with Example 2, Comparative Example 2 did not introduce modified chitosan, but the other steps were the same as in Example 2.

[0035] Comparative Example 3: A method for preparing a graphene-based negative ion antibacterial egg tray, comprising the following processes: Step 1: Disperse 8 parts of graphene oxide in N,N-dimethylformamide by ultrasonication to form an 8 mg / mL dispersion. Heat to 145℃, add 1.6 parts of N-methylimidazole, and add 8 parts of cashew phenol glycidyl ester dropwise over 40 min. Continue the reaction for 23 h, cool to room temperature, and obtain modified graphene after centrifugation, washing, and drying. Step 2: Mix 45 parts epoxy resin, 8 parts modified graphene, 5 parts tourmaline, 4 parts titanium dioxide, 15 parts deionized water, 0.3 parts leveling agent and 10 parts curing agent evenly to obtain antibacterial coating. Step 3: Impregnate the recycled pulp matrix in antibacterial coating, remove it, dry it to form an antibacterial coating, and process it into an egg tray using hot pressing molding technology (temperature 130℃, pressure 4MPa, time 8min). Then, perform plasma surface treatment on the molded egg tray (power 400W, time 80s, Ar / O2 gas flow ratio of 1:4) to obtain a negative ion antibacterial egg tray. Compared with Example 2, in step one of Comparative Example 3, the mass ratio of graphene oxide to cashew phenol glycidyl ester was 1:1, and the other steps were the same as in Example 2.

[0036] Experiment: Graphene-based negative ion antibacterial egg trays obtained in Examples 1-3 and Comparative Examples 1-3 were used to prepare samples. Their performance was tested and the results were recorded. Determination of negative ion release: An atmospheric negative ion detector was used to determine the number of negative ions released by the board. The instrument detection point was 10 cm away from the sample surface. Compressive strength test: The loading speed of the universal testing machine was set to 12 mm / min. Pressure was applied to the sample at a uniform speed until the sample was destroyed to test the compressive strength of the sample. Antibacterial test: The test was conducted in accordance with GB / T 21866-2008. The test species was Staphylococcus aureus.

[0037] The test results are shown in Table 1.

[0038] Table 1. Test results of graphene-based negative ion antibacterial egg tray performance. ; Based on the data in the table above, the following conclusions can be clearly drawn: Combining Examples 1-3 and Comparative Examples 1-3, it can be seen that the graphene-based negative ion antibacterial egg tray prepared by the present invention has excellent mechanical and antibacterial properties. Compared with Example 2, the compressive strength of the products obtained in Comparative Examples 1 and 3 decreased, indicating that the modified graphene prepared by the present invention has better compatibility than graphene oxide, thereby improving the overall performance of the material. At the same time, the results of Comparative Example 3 also confirm that the amount of cashew phenol glycidyl ester added is crucial to ensuring good dispersion. Insufficient amount will lead to decreased dispersibility, which in turn affects the mechanical properties of the final product. In Comparative Example 2, the antibacterial rate of the product decreased because no modified chitosan was introduced.

[0039] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A method for preparing a graphene-based negative ion antibacterial egg tray, characterized in that: Includes the following steps: Step 1: Graphene oxide is ultrasonically dispersed in N,N-dimethylformamide to form a dispersion. The temperature is raised to 140-150℃, N-methylimidazole is added, and cashew phenol glycidyl ester is added dropwise over 30-60 minutes. The reaction continues for 22-24 hours. After cooling to room temperature, the modified graphene is obtained by centrifugation, washing, and drying. Step 2: Mix epoxy resin, modified graphene, tourmaline, titanium dioxide, deionized water, leveling agent and curing agent evenly to obtain antibacterial coating; Step 3: The recycled pulp matrix is ​​impregnated in antibacterial coating, removed, dried to form an antibacterial coating, and processed into an egg tray using hot pressing technology. The formed egg tray is then subjected to plasma surface treatment to obtain a graphene-based negative ion antibacterial egg tray.

2. The preparation method of a graphene-based negative ion antibacterial egg tray according to claim 1, characterized in that: The mass ratio of graphene oxide, N-methylimidazole and cashew phenol glycidyl ester is 1:(0.1-0.3):(2-4).

3. The preparation method of a graphene-based negative ion antibacterial egg tray according to claim 2, characterized in that: The preparation method of the cashew phenol glycidyl ester is as follows: Under nitrogen protection, cashew nut shellac, triethylamine, 4-methoxyphenol, 4-dimethylaminopyridine, and dichloromethane were mixed thoroughly. A mixed solution of succinyl chloride and dichloromethane was added dropwise over 1-2 hours in an ice bath. The mixture was reacted at 40-50°C for 4-6 hours. The mixture was filtered to obtain a filtrate, which was then washed with distilled water and rotary evaporated to obtain cashew nut shellac succinate. Cashew nut shellac succinate, formic acid, toluene, p-toluenesulfonic acid, and hydrogen peroxide were mixed thoroughly and reacted at 60-70°C for 5-7 hours. After filtration, washing, and rotary evaporation, cashew nut shellac glycidyl ester was obtained.

4. The preparation method of a graphene-based negative ion antibacterial egg tray according to claim 1, characterized in that: The antibacterial coating comprises the following raw materials in parts by weight: 40-50 parts epoxy resin, 5-10 parts modified graphene oxide, 6-12 parts curing agent, 3-8 parts tourmaline, 2-5 parts titanium dioxide, 0.2-0.5 parts leveling agent, and 10-20 parts deionized water.

5. The preparation method of a graphene-based negative ion antibacterial egg tray according to claim 4, characterized in that: The tourmaline undergoes a modification process, the specific steps of which are as follows: Step 1: Mix tourmaline, anhydrous ethanol and deionized water evenly, heat to 50-70℃, introduce nitrogen gas, add vinyltrimethoxysilane, react for 4-6 hours, filter, wash and dry to obtain vinyl tourmaline; Step 2: Dissolve chitosan in acetic acid solution, add a mixed solution of caffeic acid, carbodiimide hydrochloride, N-hydroxysuccinimide and ethanol, react for 22-24 hours, and obtain modified chitosan after centrifugation, dialysis and drying. Step 3: Mix vinyl tourmaline and deionized water evenly, add methyl methacrylate, methacrylamide and modified chitosan, purge with nitrogen gas, add potassium persulfate, and react at 70-80℃ for 10-12 hours. After centrifugation, washing and drying, modified tourmaline is obtained.

6. The preparation method of a graphene-based negative ion antibacterial egg tray according to claim 5, characterized in that: In step 1, the mass ratio of tourmaline, anhydrous ethanol, deionized water and vinyltrimethoxysilane is 1:(15-20):(3-5):(1-3).

7. The preparation method of a graphene-based negative ion antibacterial egg tray according to claim 5, characterized in that: In step 2, the mass ratio of chitosan, acetic acid solution and caffeic acid is 1:(50-60):(0.2-0.4), and the concentration of acetic acid solution is 1wt%.

8. The preparation method of a graphene-based negative ion antibacterial egg tray according to claim 5, characterized in that: In step 3, the mass ratio of vinyl tourmaline, methyl methacrylate, methacrylamide and modified chitosan is 1:(1-2):(2-4):(0.5-1.5).

9. The preparation method of a graphene-based negative ion antibacterial egg tray according to claim 1, characterized in that: The plasma treatment process conditions are: power 300-500W, time 60-120s, and Ar / O2 gas flow ratio of 1:

4.

10. A graphene-based negative ion antibacterial egg tray prepared by the preparation method according to any one of claims 1-9.