Modified epoxy resin coating, preparation method and application thereof and refrigerator

Abstract

The invention discloses modified epoxy resin paint, a preparation method and application thereof and a refrigerator, and belongs to the technical field of coating paint. The preparation method comprises the following steps: preparing the carbon nanodots by adopting a carbon nanodot preparation step, and preparing the carbon nanodots / titanium carbide by taking the carbon nanodots as a raw material through a carbon nanodot / titanium carbide preparation step, and preparing the carbon nanodot / titanium carbide modified epoxy resin coating by taking the carbon nanodot / titanium carbide as a raw material through a carbon nanodot / titanium carbide modified epoxy resin coating preparation step. The modified epoxy resin coating is applied to the aspect of shell coatings of household appliances, solves the problems that the existing epoxy resin coating is poor in corrosion resistance and short in service life due to oxidation aging, and has excellent oxidation resistance, antibacterial property and corrosion resistance.

Description

Technical Field

[0001] The present invention belongs to the technical field of coating materials, and in particular relates to a modified epoxy resin coating, a preparation method and application thereof, and a refrigerator. Background Art

[0002] Metal has high mechanical properties and a heavy texture, and is often used as the casing material for household appliances, but it is prone to corrosion in the natural environment.

[0003] Epoxy resin is an economical and effective anti-corrosion coating that can be used for metal corrosion protection and is widely used in actual engineering. However, it often contains defects such as holes and cracks, which affect its anti-corrosion ability. Titanium carbide, as a typical two-dimensional nanomaterial, is used as a filler and added to epoxy resin to enhance its anti-corrosion ability. However, titanium carbide has poor solubility in epoxy resin and is prone to agglomeration due to the van der Waals force caused by its high surface area. In addition, the free radicals in epoxy resin will trigger the formation of oxygen free radicals, leading to oxidative aging of the epoxy resin and reducing the physical properties and service life of the coating. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the technical problem to be solved by the present invention is to overcome the problems of poor corrosion resistance and short service life of existing epoxy resin coatings due to oxidation and aging, and propose a modified epoxy resin coating with excellent antioxidant, antibacterial and anticorrosive properties, its preparation method, application and refrigerator.

[0005] In order to solve the technical problem, the technical solution adopted by the present invention is:

[0006] In one aspect, the present invention provides a method for preparing a modified epoxy resin coating, comprising: preparing carbon nanodots by a carbon nanodot preparation step, using the carbon nanodots as raw materials to prepare carbon nanodots / titanium carbide by a carbon nanodot / titanium carbide preparation step, and preparing a carbon nanodot / titanium carbide modified epoxy resin coating by a carbon nanodot / titanium carbide modified epoxy resin coating by using the carbon nanodots / titanium carbide as raw materials;

[0007] The carbon nanodot preparation step comprises: using ethylenediamine and citric acid as raw materials, reacting under high pressure and heating conditions to prepare the carbon nanodots.

[0008] Preferably, the steps for preparing the carbon nanodot / titanium carbide modified epoxy resin coating include: mixing the epoxy resin and the diluent evenly until it becomes liquid, adding the carbon nanodots / titanium carbide thereto, continuing to stir to disperse it evenly, then adding a curing agent, a diluent and a defoaming agent, continuing to stir to obtain a dispersion in which the carbon nanodots / titanium carbide are evenly dispersed in the epoxy resin, and vacuuming the dispersion to prepare the carbon nanodot / titanium carbide modified epoxy resin coating.

[0009] Preferably, the carbon nanodots / titanium carbide preparation step comprises: adding titanium carbide, the carbon nanodots, and p-toluenesulfonic acid into deionized water, dissolving them by ultrasonication, then refluxing with stirring, heating for reaction, washing, and freeze-drying to prepare the carbon nanodots / titanium carbide.

[0010] Preferably, the carbon nanodot preparation step specifically includes: using ethylenediamine and citric acid as raw materials, transferring the mixed solution of ethylenediamine and citric acid into a polytetrafluoroethylene high-pressure reactor, heating the reaction at 200°C for 4 hours, washing after the reaction, and drying at 50°C for 18 hours to prepare the carbon nanodots.

[0011] Preferably, the carbon nanodots / titanium carbide preparation step specifically includes: adding the titanium carbide, the carbon nanodots, and the p-toluenesulfonic acid to deionized water, dissolving them by ultrasound, and then heating them at 75°C for 6 hours while stirring and refluxing. After the reaction, washing and freeze-drying are performed to prepare the carbon nanodots / titanium carbide.

[0012] Preferably, in the preparation step of the carbon nanodot / titanium carbide modified epoxy resin coating, the diluent is added twice, and the amount of the diluent added each time is any value between 20-25% of the mass of the epoxy resin, the amount of the defoaming agent is any value between 0.01-0.02 mL / g of the mass of the epoxy resin, and the amount of the curing agent is 1 / 2 of the mass of the epoxy resin.

[0013] The present invention also provides a modified epoxy resin coating prepared by the preparation method of the modified epoxy resin coating described in any of the above technical solutions.

[0014] Preferably, the mass fraction of carbon nanodots / titanium carbide in the modified epoxy resin coating is selected from any value within the range of 1-5 wt.%.

[0015] Another aspect of the present invention provides the use of the modified epoxy resin coating described in any of the above technical solutions in the housing coating of household appliances.

[0016] The present invention also provides a refrigerator, wherein the outer shell coating of the refrigerator adopts any one of the modified epoxy resin coatings described above.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The present invention provides a method for preparing a modified epoxy resin coating. By limiting the preparation process of carbon nanodots, the obtained carbon nanodots are ensured to be rich in amine groups. The interaction between the amine-rich carbon nanodots, titanium carbide and epoxy resin ensures that the prepared modified epoxy resin coating has excellent antioxidant, antibacterial and anti-corrosion properties. DETAILED DESCRIPTION

[0019] The following is a detailed and complete description of the technical solutions in the specific embodiments of the present invention. Obviously, the described embodiments are only some specific implementation methods of the overall technical solution of the present invention, and are not all implementation methods. Based on the overall concept of the present invention, all other embodiments obtained by ordinary skill in the art are within the scope of protection of the present invention.

[0020] In one aspect, the present invention provides a method for preparing a modified epoxy resin coating, comprising: preparing carbon nanodots using a carbon nanodot preparation step; using the carbon nanodots as raw materials to prepare carbon nanodots / titanium carbide using a carbon nanodot / titanium carbide preparation step; and using the carbon nanodots / titanium carbide as raw materials to prepare a carbon nanodot / titanium carbide-modified epoxy resin coating using a carbon nanodot / titanium carbide-modified epoxy resin coating step to prepare a carbon nanodot / titanium carbide-modified epoxy resin coating; wherein the carbon nanodot preparation step comprises reacting ethylenediamine and citric acid as raw materials under high pressure and heating to prepare the carbon nanodots. This method, by defining the carbon nanodot preparation process, ensures that the resulting carbon nanodots are rich in amine groups. The interaction between the amine-rich carbon nanodots and the titanium carbide and epoxy resin ensures that the resulting modified epoxy resin coating has excellent antioxidant, antibacterial, and anticorrosive properties. In a preferred embodiment, the carbon nanodot preparation step specifically includes: using ethylenediamine and citric acid as raw materials, transferring the mixed solution of ethylenediamine and citric acid into a polytetrafluoroethylene autoclave, heating the mixture at 200°C for 4 hours, washing the mixture after the reaction, and drying the mixture at 50°C for 18 hours to prepare the carbon nanodots. The structure of the carbon nanodot / titanium carbide is as follows:

[0021]

[0022] In the modified epoxy resin coating prepared by the above method, titanium carbide has a high aspect ratio, which can play a physical barrier effect and hinder the penetration of corrosive media, thereby improving the anti-corrosion performance of epoxy resin; carbon nanodots have excellent antibacterial properties and can give epoxy resin antibacterial properties; carbon nanodots can stabilize the active electrons of external free radicals in the π-π conjugated structure constructed by sp2 hybridized carbon inside the carbon nanodots through electron transfer, and the active groups on the surface can act as proton donors to accept the electrons of free radicals and transfer them to the π-π conjugated structure inside the carbon nanodots, which can effectively quench A variety of active free radicals provide antioxidant properties and can effectively prevent epoxy resin from being oxidized; there are a large number of hydroxyl groups on the surface of titanium carbide, which can undergo esterification reaction with the carboxyl groups of carbon nanodots to form covalent bonds. Titanium carbide has high conductivity. The electrons of the free radicals accepted by the hydroxyl groups as proton donors can be transferred from titanium carbide to the internal structure of the carbon nanodots. Titanium carbide provides more active sites. The combination of titanium carbide and carbon nanodots increases the probability of free radicals being captured and has higher antioxidant properties; carbon nanodots / titanium carbide improves the compatibility of titanium carbide in epoxy resin and avoids agglomeration.

[0023] Specifically, the carbon nanodots have a large number of amino groups on their surface, which can form chemical bonds with epoxy resins. Therefore, the carbon nanodot / titanium carbide combination improves the compatibility of titanium carbide in epoxy resins and prevents agglomeration. Carbon nanodots have excellent antibacterial properties. When in contact with bacteria, they can adsorb onto the surface of bacterial cell membranes and disrupt the cell membranes through electrostatic interactions, leading to the outflow of internal solutions and the death of the bacteria. Furthermore, carbon nanodots can stabilize the active electrons of external free radicals through electron transfer within their internal π-π conjugated structure constructed from sp2 hybridized carbon. The surface active groups can act as proton donors, accepting electrons from free radicals and transferring them to the π-π conjugated structure within the carbon nanodots. This effectively quenches various active free radicals, provides antioxidant properties, and effectively prevents oxidation of epoxy resins. The titanium carbide surface has a large number of hydroxyl groups that can undergo esterification reactions with the carboxyl groups of the carbon nanodots, forming a covalent bond. Titanium carbide has high conductivity, and the electrons from free radicals accepted by hydroxyl groups as proton donors can be transferred from titanium carbide to the internal structure of carbon nanodots. Titanium carbide provides more active sites, and the combination of titanium carbide and carbon nanodots increases the probability of free radicals being captured, resulting in higher oxidation resistance.

[0024] In a preferred embodiment, the carbon nanodot / titanium carbide modified epoxy resin coating preparation steps include: mixing epoxy resin and a diluent until a liquid is formed, adding the carbon nanodots / titanium carbide thereto, and continuing to stir to uniformly disperse the mixture; then adding a curing agent, a diluent, and a defoaming agent, and continuing to stir to obtain a dispersion of the carbon nanodots / titanium carbide uniformly dispersed in the epoxy resin; and vacuuming the dispersion to obtain the carbon nanodot / titanium carbide modified epoxy resin coating. This technical solution specifically specifies the vacuuming step to remove bubbles generated by stirring. The presence of bubbles can cause pore defects in the coating after curing, serving as diffusion pathways for corrosive media and severely reducing the coating's corrosion resistance. Preferably, the oven is vacuumed for 30 minutes.

[0025] In a preferred embodiment, the carbon nanodot / titanium carbide preparation step comprises: adding titanium carbide, the carbon nanodots, and p-toluenesulfonic acid to deionized water, ultrasonically dissolving them, then stirring and refluxing, heating to react, washing, and freeze-drying to produce the carbon nanodot / titanium carbide. In a preferred embodiment, the carbon nanodot / titanium carbide preparation step specifically comprises: adding the titanium carbide, the carbon nanodots, and p-toluenesulfonic acid to deionized water, ultrasonically dissolving them, then stirring and refluxing, heating to react at 75°C for 6 hours, washing, and freeze-drying to produce the carbon nanodot / titanium carbide.

[0026] In a preferred embodiment, during the preparation of the carbon nanodot / titanium carbide modified epoxy resin coating, the diluent is added in two steps, with the amount of diluent added each time accounting for anywhere between 20-25% of the epoxy resin's mass. The defoamer is used in an amount between 0.01-0.02 mL / g of the epoxy resin's mass, and the curing agent is used in an amount of 1 / 2 of the epoxy resin's mass. Both diluents and defoamers are additives. The diluent serves to dilute the resin. Too little diluent prevents the resin from becoming fluid; too much diluent slows volatilization during curing and can easily cause coating defects. Therefore, neither too much nor too little diluent is desirable. Preferably, the epoxy resin is bisphenol A epoxy resin; the diluent is a mixed solution of xylene and n-butanol in a 7:3 mass ratio; the curing agent is a polyamide curing agent; and the defoamer is a silicone defoamer.

[0027] The present invention also provides a modified epoxy resin coating prepared by the method for preparing a modified epoxy resin coating according to any of the above technical solutions. In a preferred embodiment, the mass fraction of the carbon nanodots / titanium carbide in the modified epoxy resin coating is selected from any value between 1 and 5 wt.%. It is understood that the mass fraction of the carbon nanodots / titanium carbide in the modified epoxy resin coating can also be 2 wt.%, 3 wt.%, 4 wt.%, or any value within this range.

[0028] Another aspect of the present invention provides the use of the modified epoxy resin coating described in any of the above technical solutions in the housing coating of household appliances.

[0029] The present invention also provides a refrigerator, wherein the outer shell coating of the refrigerator adopts any one of the modified epoxy resin coatings described above.

[0030] In order to more clearly and in detail introduce the modified epoxy resin coating, its preparation method, application and refrigerator provided by the embodiments of the present invention, the following description will be made in conjunction with specific embodiments.

[0031] Example 1

[0032] A method for preparing an epoxy resin coating comprises the following steps:

[0033] (1) Preparation of carbon nanodots

[0034] Weigh 180 mg of citric acid using a balance and add it to 40 mL of deionized water. Dissolve completely with magnetic stirring at 600 rpm for 20 minutes. Use a pipette to add 67 μL of ethylenediamine to the citric acid solution. The mixed solution is then transferred to a polytetrafluoroethylene autoclave and heated at 200°C for 4 hours. The resulting solution is washed three times with deionized water and dried at 50°C for 18 hours to produce carbon nanodots.

[0035] (2) Preparation of carbon nanodots / titanium carbide

[0036] 50 mg of titanium carbide, 759 mg of carbon nanodots, and 15 mg of p-toluenesulfonic acid were weighed using a balance and added to 100 mL of deionized water. Dissolved by sonication, the mixture was then transferred to a round-bottom flask and heated at 75°C for 6 hours with stirring and reflux. The resulting solution was washed several times with deionized water and freeze-dried for 24 hours to prepare carbon nanodot / titanium carbide.

[0037] (3) Preparation of carbon nanodot / titanium carbide modified epoxy resin coating

[0038] Weigh 10g of epoxy resin using a balance, add 2.5g of diluent, and stir with a glass rod until it becomes liquid. Add 0.1g of carbon nanodots / titanium carbide to the mixture and continue stirring to evenly disperse it. Then, add 5g of curing agent, 2g of diluent, and 0.2mL of defoamer, and continue stirring to obtain a uniform dispersion of the carbon nanodots / titanium carbide in the epoxy resin. Place the dispersion in an oven and evacuate for 30 minutes to remove bubbles generated by stirring. This yields a carbon nanodot / titanium carbide-modified epoxy resin coating with a mass fraction of 1 wt.%.

[0039] Example 2

[0040] A method for preparing an epoxy resin coating comprises the following steps:

[0041] (1) Preparation of carbon nanodots

[0042] Weigh 180 mg of citric acid using a balance and add it to 40 mL of deionized water. Dissolve completely with magnetic stirring at 600 rpm for 20 minutes. Use a pipette to add 67 μL of ethylenediamine to the citric acid solution. The mixed solution is then transferred to a polytetrafluoroethylene autoclave and heated at 200°C for 4 hours. The resulting solution is washed three times with deionized water and dried at 50°C for 18 hours to produce carbon nanodots.

[0043] (2) Preparation of carbon nanodots / titanium carbide

[0044] 50 mg of titanium carbide, 759 mg of carbon nanodots, and 15 mg of p-toluenesulfonic acid were weighed using a balance and added to 100 mL of deionized water. Dissolved by sonication, the mixture was then transferred to a round-bottom flask and heated at 75°C for 6 hours with stirring and reflux. The resulting solution was washed several times with deionized water and freeze-dried for 24 hours to prepare carbon nanodot / titanium carbide.

[0045] (3) Preparation of carbon nanodot / titanium carbide modified epoxy resin coating

[0046] Weigh 10g of epoxy resin using a scale, add 2.5g of diluent, and stir with a glass rod until it becomes liquid. Add 0.3g of carbon nanodots / titanium carbide to the mixture and continue stirring to evenly disperse it. Then, add 5g of curing agent, 2g of diluent, and 0.2mL of defoamer, and continue stirring to obtain a uniform dispersion of the carbon nanodots / titanium carbide in the epoxy resin. Place the dispersion in an oven and evacuate for 30 minutes to remove bubbles generated by stirring. This yields a carbon nanodot / titanium carbide-modified epoxy resin coating with a mass fraction of 3 wt.%.

[0047] Example 3

[0048] A method for preparing an epoxy resin coating comprises the following steps:

[0049] (1) Preparation of carbon nanodots

[0050] Weigh 180 mg of citric acid using a balance and add it to 40 mL of deionized water. Dissolve completely with magnetic stirring at 600 rpm for 20 minutes. Use a pipette to add 67 μL of ethylenediamine to the citric acid solution. The mixed solution is then transferred to a polytetrafluoroethylene autoclave and heated at 200°C for 4 hours. The resulting solution is washed three times with deionized water and dried at 50°C for 18 hours to produce carbon nanodots.

[0051] (2) Preparation of carbon nanodots / titanium carbide

[0052] 50 mg of titanium carbide, 759 mg of carbon nanodots, and 15 mg of p-toluenesulfonic acid were weighed using a balance and added to 100 mL of deionized water. Dissolved by sonication, the mixture was then transferred to a round-bottom flask and heated at 75°C for 6 hours with stirring and reflux. The resulting solution was washed several times with deionized water and freeze-dried for 24 hours to prepare carbon nanodot / titanium carbide.

[0053] (3) Preparation of carbon nanodot / titanium carbide modified epoxy resin coating

[0054] Weigh 10g of epoxy resin using a balance, add 2.5g of diluent, and stir with a glass rod until it becomes liquid. Add 0.5g of carbon nanodots / titanium carbide to the mixture and continue stirring to evenly disperse it. Then, add 5g of curing agent, 2g of diluent, and 0.2mL of defoamer, and continue stirring to obtain a uniform dispersion of the carbon nanodots / titanium carbide in the epoxy resin. Place the dispersion in an oven and evacuate for 30 minutes to remove bubbles generated by stirring. This yields a carbon nanodot / titanium carbide-modified epoxy resin coating with a mass fraction of 5wt%.

[0055] Comparative Example 1

[0056] A method for preparing an epoxy resin coating comprises the following steps:

[0057] (1) Preparation of carbon nanodots

[0058] Weigh 180 mg of citric acid using a balance and add it to 40 mL of deionized water. Dissolve completely with magnetic stirring at 600 rpm for 20 minutes. Use a pipette to add 67 μL of ethylenediamine to the citric acid solution. The mixed solution is then transferred to a polytetrafluoroethylene autoclave and heated at 200°C for 4 hours. The resulting solution is washed three times with deionized water and dried at 50°C for 18 hours to produce carbon nanodots.

[0059] (2) Preparation of carbon nanodot modified epoxy resin coating

[0060] Weigh 10g of epoxy resin using a balance, add 2.5g of diluent, and stir with a glass rod until it becomes liquid. Add 0.1g of carbon nanodots and continue stirring to evenly disperse them. Then, add 5g of curing agent, 2g of diluent, and 0.2mL of defoaming agent, and continue stirring to obtain a uniform dispersion of the carbon nanodots in the epoxy resin. Place the dispersion in a vacuum drying oven and heat at 30°C for 30 minutes to remove bubbles generated by stirring. This yields a carbon nanodot-modified epoxy resin coating with a mass fraction of 1 wt.%.

[0061] Comparative Example 2

[0062] An epoxy resin coating, which differs from Example 1 only in that titanium carbide is used instead of carbon nanodots / titanium carbide. Specifically:

[0063] A method for preparing an epoxy resin coating comprises the following steps:

[0064] Preparation of titanium carbide modified epoxy resin coating

[0065] Weigh 10g of epoxy resin using a balance, add 2.5g of diluent, and stir with a glass rod until it becomes liquid. Add 0.1g of titanium carbide and continue stirring to evenly disperse it. Then, add 5g of curing agent, 2g of diluent, and 0.2mL of defoamer, and continue stirring to obtain a uniform dispersion of carbon nanodots / titanium carbide in the epoxy resin. Place the dispersion in an oven and evacuate for 30 minutes to remove bubbles generated by stirring. This yields a titanium carbide-modified epoxy resin coating with a mass fraction of 1wt%.

[0066] Comparative Example 3

[0067] An epoxy resin coating, which differs from Example 1 only in that no carbon nanodots / titanium carbide are added. Specifically:

[0068] A method for preparing an epoxy resin coating comprises the following steps:

[0069] Weigh 10g of epoxy resin using a balance, add 2.5g of diluent, and stir with a glass rod until it becomes liquid. Then, add 5g of curing agent, 2g of diluent, and 0.2mL of defoamer. Continue stirring to obtain a uniform dispersion of carbon nanodots / titanium carbide in the epoxy resin. Place the dispersion in an oven and evacuate for 30 minutes to remove bubbles generated by stirring, thereby preparing an epoxy resin coating.

[0070] Performance Testing

[0071] (1) Anti-corrosion performance test

[0072] The coatings prepared in Examples 1-3 and Comparative Examples 1-3 were applied to a clean 1cm*1cm*0.5cm metal substrate and allowed to cure at room temperature for 7 days, resulting in a coating thickness of 80±10μm. Working electrodes were prepared. The working electrodes were immersed in a 3.5wt% NaCl solution, and the electrochemical behavior of the coatings was tested using an electrochemical workstation and a three-electrode system. After the working electrodes were immersed for a period of time, the open-circuit potential reached a steady state. The data at this point are recorded in Table 1.

[0073] Table 1 Corrosion potential

[0074]

[0075] As shown in Table 1, the open circuit potentials of Examples 1-3 are significantly higher than those of the comparative example, indicating that the addition of carbon nanodots / titanium carbide is beneficial for improving the corrosion resistance of epoxy resin. Example 2 has the highest open circuit potential and exhibits the best corrosion resistance. The open circuit potential of Example 3 begins to decrease, due to excessive addition of carbon nanodots / titanium carbide, which leads to aggregation in the epoxy resin.

[0076] (2) Antibacterial performance test

[0077] The antibacterial properties of the coatings were evaluated using Escherichia coli and Staphylococcus aureus as test bacteria. The coatings from Examples 1-3 and Comparative Examples 1-3 were applied to glass slides and allowed to solidify into films. Subsequently, 100 μL of a bacterial suspension with a concentration of 108 CFU / mL was applied to the coating surface and incubated at 37°C in a sterile environment for 24 hours. The slides were removed and repeatedly rinsed with phosphate buffered saline. The wash solution was inoculated onto nutrient agar and incubated at 37°C for 24 hours. Bacterial survival was recorded (Table 2).

[0078] Table 2 Antibacterial effect

[0079] project Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Escherichia coli 97.5％ 98.6％ 99.2％ 92.1％ 56.3％ No antibacterial effect Staphylococcus aureus 98.6％ 99.3％ 99.8％ 94.5％ 65.9％ No antibacterial effect

[0080] As shown in Table 2, the antibacterial rates against Escherichia coli and Staphylococcus aureus in Examples 1-3 exceeded 97%, demonstrating that the carbon nanodot / titanium carbide-modified epoxy resin coatings exhibit excellent antibacterial properties. On the one hand, upon contact with bacteria, the carbon nanodots can adsorb onto the bacterial cell membrane. Electrostatic interactions with the membrane disrupt the membrane, leading to the outflow of the solution and the death of the bacteria. On the other hand, the sharp edges of the titanium carbide easily rupture the bacterial cell membrane, causing bacterial death.

[0081] (3) Antioxidant performance test

[0082] Carbon nanodots / titanium carbide were added to a DPPH solution at a concentration of 85 μg / mL. The solution was shaken and allowed to stand at room temperature for 10 minutes. The absorbance of the solution at 517 nm was measured using a UV spectrophotometer, denoted as A1. A DPPH solution without any additives was used as a reference, and its absorbance at 517 nm was measured using a UV spectrophotometer, denoted as A0.

[0083] DPPH free radical scavenging rate = (A0-A1) / A0×100%

[0084] Another set of experiments was conducted simultaneously for comparison, using carbon nanodots as the experimental samples, and the above test steps were repeated.

[0085] Calculation results show that the carbon nanodots / titanium carbide composite has a DPPH radical scavenging rate of 74.9%, indicating that the addition of carbon nanodots / titanium carbide effectively scavenges free radicals generated by epoxy resin and exhibits excellent antioxidant capacity. The carbon nanodots' DPPH radical scavenging rate is significantly lower at 65.4%, indicating that the composite composite has more efficient free radical scavenging capabilities and stronger antioxidant capacity.

[0086] The above test results show that the carbon nanodot / titanium carbide modified epoxy resin coating described in the present invention has excellent anti-corrosion and antibacterial functions, can effectively scavenge free radicals, has strong antioxidant properties, and can meet the protection requirements of metal casings of household appliances.

Claims

1. A method for preparing a modified epoxy resin coating, characterized in that: include: The carbon nanodots are prepared by the carbon nanodot preparation step, the carbon nanodots are used as raw materials to prepare carbon nanodots / titanium carbide by the carbon nanodot / titanium carbide preparation step, and the carbon nanodots / titanium carbide modified epoxy resin coating is prepared by the carbon nanodot / titanium carbide modified epoxy resin coating preparation step. The carbon nanodot preparation step comprises: using ethylenediamine and citric acid as raw materials, reacting under high pressure and heating conditions to prepare the carbon nanodots.

2. The method for preparing the modified epoxy resin coating according to claim 1, wherein The steps for preparing the carbon nanodot / titanium carbide modified epoxy resin coating include: The epoxy resin and the diluent are mixed evenly until they become liquid, the carbon nanodots / titanium carbide are added thereto, and stirring is continued to make them evenly dispersed, and then a curing agent, a diluent and a defoaming agent are added, and stirring is continued to obtain a dispersion in which the carbon nanodots / titanium carbide are evenly dispersed in the epoxy resin. The dispersion is vacuumed to prepare the carbon nanodot / titanium carbide modified epoxy resin coating.

3. The method for preparing the modified epoxy resin coating according to claim 1, wherein The carbon nanodot / titanium carbide preparation steps include: Titanium carbide, the carbon nanodots, and p-toluenesulfonic acid are added to deionized water, dissolved by ultrasound, and then refluxed with stirring. After heating for reaction, the carbon nanodots / titanium carbide are washed and freeze-dried to prepare the carbon nanodots / titanium carbide.

4. The method for preparing the modified epoxy resin coating according to claim 1, wherein The carbon nanodot preparation steps specifically include: using ethylenediamine and citric acid as raw materials, transferring the mixed solution of ethylenediamine and citric acid into a polytetrafluoroethylene high-pressure reactor, heating and reacting at 200°C for 4 hours, washing after the reaction, and drying at 50°C for 18 hours to prepare the carbon nanodots.

5. The method for preparing the modified epoxy resin coating according to claim 3, wherein The carbon nanodot / titanium carbide preparation steps specifically include: adding the titanium carbide, the carbon nanodots, and the p-toluenesulfonic acid into deionized water, sonicating to dissolve them, then stirring and refluxing, heating at 75° C. for 6 hours, and after the reaction, washing and freeze-drying to prepare the carbon nanodot / titanium carbide.

6. The method for preparing the modified epoxy resin coating according to claim 2, wherein: In the preparation steps of the carbon nanodot / titanium carbide modified epoxy resin coating, the diluent is added twice, and the amount of the diluent added each time is any value between 20-25% of the mass of the epoxy resin. The amount of the defoaming agent is any value between 0.01-0.02 mL / g of the mass of the epoxy resin, and the amount of the curing agent is 1 / 2 of the mass of the epoxy resin.

7. The modified epoxy resin coating prepared according to the method for preparing the modified epoxy resin coating according to any one of claims 1 to 6.

8. The modified epoxy resin coating according to claim 7, characterized in that: The mass fraction of carbon nanodots / titanium carbide in the modified epoxy resin coating is selected from any value within the range of 1-5 wt.%.

9. Use of the modified epoxy resin coating according to claim 7 or 8 in housing coatings for household appliances.

10. A refrigerator, characterized in that: The outer shell coating of the refrigerator adopts the modified epoxy resin coating according to claim 7 or 8.

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