Nano-modified sealing and protecting agent with excellent acid and alkali resistance and preparation method of nano-modified sealing and protecting agent

Abstract

The invention discloses a nano modified sealing and protecting agent with excellent acid and alkali resistance and a preparation method thereof. The modified sealing and protecting agent is prepared from nano particles, microcrystalline wax, petroleum ether, benzotriazole and ethanol. Wherein the nano particles are a mixture of g-C3N4-COOH and nano TiO2 (titanium dioxide). The raw materials are directly dispersed and mixed in the preparation process. The modified sealing and protecting agent disclosed by the invention has good stability, can reduce maintenance times and cost, and is especially suitable for scenes difficult to maintain frequently, so that the integrity of cultural relics is guaranteed. And other properties of the product meet the requirements of the cultural relic sealing and protecting agent.

Description

Technical Field

[0001] This invention relates to the field of cultural relic protection materials technology, and more specifically to a nano-modified sealing agent with excellent acid and alkali resistance and its preparation method. Background Technology

[0002] Significant progress has been made in the sealing and protection of cultural relics in recent years, primarily through the modification of sealing agents using nanoparticles to improve their performance, and this area shows great promise. Research into highly acid- and alkali-resistant sealing agents stems mainly from the specific needs of cultural relic protection in practical applications. In reality, many cultural relics are exposed to acidic or alkaline environments for various reasons, and are subject to long-term contact with acidic and alkaline mists, acid rain, and other media. Ordinary sealing agents are easily corroded and fail in such environments, leading to problems such as rust, weathering, and peeling of the protected materials, affecting their service life and performance. Therefore, it is necessary to research a highly acid- and alkali-resistant sealing agent that can form a stable protective layer on the material surface, effectively resisting acid and alkali corrosion. Simultaneously, its excellent stability reduces the frequency and cost of maintenance, making it particularly suitable for scenarios where infrequent maintenance is difficult, thereby ensuring the integrity of the cultural relics. Summary of the Invention

[0003] In view of this, the present invention provides a sealing agent formulation with added nanoparticles, which has excellent acid and alkali resistance, and other properties also meet the requirements for cultural relic sealing agents.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: A nano-modified sealing agent with excellent acid and alkali resistance comprises, by weight percentage: 0.5%-1% nanoparticles, 8% microcrystalline wax, 55% petroleum ether, 1% benzotriazole, and the balance being ethanol; The nanoparticles are a mixture of g-C3N4-COOH and nano-TiO2.

[0005] Preferably, the ratio of g-C3N4-COOH to nano-TiO2 is 3:1.

[0006] This invention also provides a method for preparing a nano-modified sealing agent with excellent acid and alkali resistance as described above, comprising the following steps: (1) Melt the microcrystalline wax to obtain a microcrystalline wax liquid, then add petroleum ether and benzotriazole to the wax liquid and mix evenly; (2) g-C3N4-COOH and nano-TiO2 were ultrasonically dispersed in anhydrous ethanol to obtain a nano solution; (3) Add the nano solution prepared in step (2) to the mixed solution in step (1) and ultrasonically disperse and mix thoroughly. Cool at room temperature to obtain the modified sealing agent.

[0007] Preferably, the melting temperature of the microcrystalline wax in step (1) is 60-70℃.

[0008] Preferably, in step (1), benzotriazole is added to the wax solution in the form of a 2% (w / w) BTA ethanol solution. Preferably, the preparation method of the g-C3N4-COOH is as follows: S1. Melamine was placed in a tube furnace and fired under a nitrogen atmosphere. After cooling to room temperature, it was taken out and ground to obtain a yellow powder, which is g-C3N4. g-C3N4 was ultrasonicated for 48 hours. S2. Prepare a mixed solution of concentrated nitric acid and concentrated sulfuric acid, add g-C3N4 obtained in step S1, heat to boiling, stir under reflux for 2 hours, wash with distilled water until pH is neutral, and dry at 80℃ to obtain carboxylated g-C3N4-COOH.

[0009] Furthermore, the firing temperature in S1 is 550℃, and the firing time is 2 hours.

[0010] Furthermore, the volume ratio of concentrated nitric acid to concentrated sulfuric acid in S2 is 1:3.

[0011] Furthermore, the mass-to-volume ratio of g-C3N4 in S2 to the mixture of concentrated nitric acid and concentrated sulfuric acid is 1 g: 6 mL.

[0012] Furthermore, the drying temperature in S2 is 80°C.

[0013] As can be seen from the above technical solution, compared with the prior art, the present invention discloses a nano-modified sealing agent with excellent acid and alkali resistance and its preparation method, which has the following beneficial effects: This sealing agent maintains a stable film structure even after immersion in strong acid and alkali environments, showing no significant swelling, peeling, or performance degradation, effectively solving the problem of traditional sealing agents easily failing in harsh acid and alkali environments. Furthermore, the preparation process of this sealing agent is simple and cost-effective, making it widely applicable in scenarios requiring resistance to acid and alkali corrosion. It also possesses other basic properties of sealing agents, demonstrating significant practical value and promising prospects for widespread application. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0015] Figure 1The diagram shows the particle size distribution of different particles in different media. A: Particle size distribution of nano-SiO2; B: Particle size distribution of nano-TiO2; C: Particle size distribution of g-C3N4-COOH. Figure 2 The appearance of the sealing agent coatings in Examples 1 and Comparative Examples 1-9 is shown. Figure 3 The contact angle diagrams for the sealing agents in Example 1 and Comparative Examples 1-9 are shown, where a: g-C3N4-COOH; b: g-C3N4-COOH:TiO2 = 1:1; c: g-C3N4-COOH:SiO2 = 1:1; d: g-C3N4-COOH:TiO2 = 2:1; e: SiO2 and TiO2; f: nano-SiO2; g: nano-TiO2; h: g-C3N4-COOH:TiO2 = 3:1; i: g-C3N4-COOH:SiO2 = 2:1; j: g-C3N4-COOH:SiO2 = 3:1. Figure 4 Here is a SEM image of the sealing agent coating from Example 1; Figure 5 The light transmittance of the sealing agent coatings in Example 1 and Comparative Examples 1-9; Figure 6 The images show a comparison of the appearance of the sealing agent coatings before and after the aging test of the sealing agents in Examples 1 and 1-9. In the images, a and b are the appearance of the film before aging; c and d are the appearance of the film after 7 days of aging. Detailed Implementation

[0016] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0017] Table 1 Specifications and Sources of Major Drugs and Reagents reagents Specifications / Grade Manufacturer Nano titanium dioxide T823119 Shandong Keyuan Biochemical Co., Ltd. Nano silica 99.5% Shandong Keyuan Biochemical Co., Ltd. melamine Analytical Pure Tianjin Kemio Chemical Reagent Co., Ltd. Microcrystalline wax C875530 Shandong Keyuan Biochemical Co., Ltd. petroleum ether Analytical Pure Tianjin Tianli Chemical Reagent Co., Ltd. Anhydrous ethanol Analytical Pure Tianjin Tianli Chemical Reagent Co., Ltd. Benzotriazole 99% Shandong Keyuan Biochemical Co., Ltd.

[0018] Example 1 The nano-modified sealing agent with excellent acid and alkali resistance comprises, by weight percentage: 1% nanoparticles, 8% microcrystalline wax, 55% petroleum ether, 1% benzotriazole, and 35% ethanol; The nanoparticles are a mixture of g-C3N4-COOH and nano-TiO2 in a ratio of 3:1 by mass.

[0019] The preparation process is as follows: First, prepare g-C3N4-COOH: Weigh 10g of melamine sample and place it in a corundum boat. Check the equipment status and confirm that the valve is closed, the flange sealing ring is intact, and the seal is intact. Push the sample into the constant temperature zone in the middle of the tube furnace, introduce nitrogen gas, and fire it in the tube furnace at 550℃ for 2 hours. After cooling to room temperature, grind the blocky solid in the corundum boat to obtain a yellow powder, which is carbon nitride (g-C3N4). Sonicate g-C3N4 for 48 hours and then carboxylate it. Prepare 60 mL of a mixed solution of concentrated nitric acid and concentrated sulfuric acid in a volume ratio of 1:3. Weigh 10 g of g-C3N4 and place it in a three-necked flask. Heat and bring to a gentle boil. Stir under reflux for 2 hours. Wash with distilled water until the pH is neutral. Dry at 80 °C to obtain carboxylated g-C3N4, which is g-C3N4-COOH.

[0020] Next, prepare the sealing agent: Microcrystalline wax is melted at 60-70℃ to obtain microcrystalline wax liquid. Petroleum ether and 2% (w / w) benzotriazole (BTA) are added to the melted wax liquid and mixed evenly to prepare an unmodified sealing agent. Note that the 2% BTA solution is a BTA ethanol solution and the preparation should be carried out in a fume hood. Nanoparticles were added to anhydrous ethanol and dispersed by ultrasonication to obtain a nanosolution. The prepared nanosolution was then added to an unmodified sealing agent and dispersed again by ultrasonication to ensure thorough mixing of the components. After cooling at room temperature, the modified sealing agent was obtained.

[0021] Comparative Example 1 The difference from Example 1 is that the nanoparticles are a mixture of g-C3N4-COOH and nano-TiO2 in a ratio of 2:1.

[0022] Comparative Example 2 The difference from Example 1 is that the nanoparticles are a mixture of g-C3N4-COOH and nano-TiO2 in a ratio of 1:1.

[0023] Comparative Example 3 The difference from Example 1 is that the nanoparticles are g-C3N4-COOH.

[0024] Comparative Example 4 The difference from Example 1 is that the nanoparticles are a mixture of g-C3N4-COOH and nano-SiO2 in a ratio of 3:1.

[0025] Comparative Example 5 The difference from Example 1 is that the nanoparticles are a mixture of g-C3N4-COOH and nano-SiO2 in a ratio of 2:1.

[0026] Comparative Example 6 The difference from Example 1 is that the nanoparticles are a mixture of g-C3N4-COOH and nano-SiO2 in a ratio of 1:1.

[0027] Comparative Example 7 The difference from Example 1 is that the nanoparticles are nano-TiO2.

[0028] Comparative Example 8 The difference from Example 1 is that the nanoparticles are nano-SiO2.

[0029] Comparative Example 9 The difference from Example 1 is that the nanoparticles are a mixture of nano-SiO2 and nano-TiO2 in a ratio of 1:1.

[0030] Experimental Example I. The particle size and Zeta potential of g-C3N4-COOH, nano-SiO2, and nano-TiO2 were detected, and the results are as follows: Figure 1 As shown in Table 2.

[0031] Table 1. Particle size and potential values ​​in different media. category Particle size (nm) in ethanol Particle size in water (nm) Potential in ethanol (mV) Potential in water (mV) <![CDATA[SiO2]]> 411.6 324.5 -19.2 -27.8 <![CDATA[TiO2]]> 86.71 535.8 -110 11.9 <![CDATA[g-C3N4-COOH]]> 16.32 2664 -24.1 -6.91 Table 2 and Figure 1 As can be seen, silica and carboxylated carbon nitride exhibit relatively uniform particle size dispersion in the ethanol-based system. The absolute potential value of the SiO2 dispersion system did not reach 40 mV; the absolute potential value of the TiO2-ethanol dispersion system exceeded 40 mV, indicating excellent stability. The g-C3N4-COOH system showed good dispersibility and electrostatic stability when the absolute value of the Zeta potential was ≥30 mV. However, the absolute potential values ​​in both media did not reach stable values, indicating poor dispersibility and stability, suggesting that a dispersant could be added to improve performance.

[0032] II. The sealing agents of Example 1 and Comparative Examples 1-9 were subjected to performance tests in sequence, including coating appearance, color difference, contact angle, scanning electron microscopy, acid and alkali resistance, UV resistance, anti-aging properties, and breathability. The test results and analysis are as follows: 1) such as Figure 2 As shown, the sealant coating has a smooth and transparent appearance. This is because the solvent evaporates quickly during the coating process, allowing for uniform coating on the glass slide and copper sheet. After film formation, the molecules are oriented, ensuring a tight bond between the substrate and the sealant film and reducing light reflection and scattering at the interface, thus making the sealant film transparent. Therefore, it can be concluded that applying the sealant to the surface of bronze artifacts will not obscure the original appearance of the artifacts, and the sealant produced adheres to the principle of restoring the old as it was.

[0033] 2) Table 3 shows the color difference variation data. Table 3 Color Difference Variation Data Sample Name Color data (L / a / b) <![CDATA[ΔE * ]]> Change level <![CDATA[SiO2]]> 33.65 / -4.69 / 3.76 0.29 trace amounts <![CDATA[TiO2]]> 35.05 / -4.76 / 2.66 1.93 Senseable <![CDATA[SiO2 and TiO2]]> 34.02 / -4.94 / 3.20 0.79 slight <![CDATA[g-C3N4-COOH]]> 31.68 / -4.96 / 2.50 2.19 Senseable <![CDATA[TiO2:g-C3N4-COOH is 1:1]]> 32.82 / -4.85 / 3.55 0.69 slight <![CDATA[The ratio of TiO2:g-C3N4-COOH is 1:2]]> 33.48 / -5.15 / 3.48 0.36 trace amounts <![CDATA[TiO2:g-C3N4-COOH is 1:3]]> 32.09 / -4.81 / 3.89 1.39 slight <![CDATA[SiO2:g-C3N4-COOH is 1:1]]> 32.26 / -4.82 / 3.87 1.22 slight <![CDATA[SiO2:g-C3N4-COOH is 1:2]]> 32.99 / -4.87 / 3.53 0.53 slight <![CDATA[SiO2:g-C3N4-COOH is 1:3]]> 32.48 / -4.57 / 3.59 1.06 slight In the mixed system, the color difference level is slight when the TiO2:g-C3N4-COOH ratio is 1:3. When the nanoparticles are small in size and uniformly dispersed, light scattering is stable and controllable, and the color difference value changes little. The higher the absolute value of the potential, the better the dispersibility, which can reduce the abnormal light absorption or light scattering caused by agglomeration, thus affecting the color difference value. When g-C3N4-COOH forms a mixed system with SiO2 and TiO2, the particle size and potential values ​​will change with the preparation ratio, causing ΔE* to fluctuate slightly and in trace amounts. The absolute value of the potential in the TiO2 ethanol dispersion system is greater than 40, which also means that the g-C3N4-COOH has the smallest particle size in the ethanol system. When the ratio of TiO2 to g-C3N4-COOH is more suitable, the particle size and potential are synergistically optimized, and the dispersion is stable.

[0034] 3) Table 4 and Figure 3 For different sealing agent contact angles Table 4 Contact angle data for different sealants performance <![CDATA[Contact angle of H2O (˚)]]> <![CDATA[Contact angle of CCl4 (˚)]]> <![CDATA[g-C3N4-COOH]]> 116.1 0 <![CDATA[The ratio of g-C3N4-COOH to TiO2 is 1:1]]> 111.8 0 <![CDATA[The ratio of g-C3N4-COOH to SiO2 is 1:1]]> 120.6 0 <![CDATA[The ratio of g-C3N4-COOH to TiO2 is 2:1]]> 107.1 0 <![CDATA[SiO2 and TiO2]]> 103.9 0 <![CDATA[SiO2]]> 107.8 0 <![CDATA[TiO2]]> 107.5 0 <![CDATA[The ratio of g-C3N4-COOH to TiO2 is 3:1]]> 113.8 0 <![CDATA[The ratio of g-C3N4-COOH to SiO2 is 2:1]]> 114.6 0 <![CDATA[The ratio of g-C3N4-COOH to SiO2 is 3:1]]> 113.9 0 Because of the presence of water in the air, a large number of water molecules will corrode bronze artifacts upon contact, which is detrimental to their preservation. The contact angle of the sealant can be measured to determine whether the film has hydrophobic and oleophobic properties, thus eliminating or suppressing the effects of humidity on the bronze. Table 4 shows that the g-C3N4-COOH:TiO2 sealant with a 3:1 ratio has a contact angle of 113.8˚, exhibiting basic hydrophobic and oleophilic properties.

[0035] 4) Figure 4 SEM image of the sealing agent coating in Example 1 Figure 4 The image shows a scanning electron microscope image magnified 100,000 times of the coating of the g-C3N4-COOH:TiO2 content ratio of 3:1. The image shows obvious and uniformly distributed dense particles. Although there are some very small gaps, they can still form a dense film on the surface of the cultural relic, playing a basic role in the sealing of the cultural relic.

[0036] 5) Table 5-6 shows the acid and alkali resistance of the sealing agents. Table 5. Acid resistance of sealing agents Sample Name <![CDATA[M1(g)]]> <![CDATA[M2(g)]]> <![CDATA[R H (%)]]> <![CDATA[SiO2]]> 1.0396 1.0362 99.67 <![CDATA[TiO2]]> 1.0724 1.0623 99.06 <![CDATA[SiO2 and TiO2]]> 1.1130 1.1066 99.42 <![CDATA[g-C3N4-COOH]]> 1.0438 1.0404 99.67 <![CDATA[TiO2:g-C3N4-COOH is 1:1]]> 0.9642 0.9618 99.75 <![CDATA[The ratio of TiO2:g-C3N4-COOH is 1:2]]> 1.0037 0.7807 77.78 <![CDATA[The ratio of TiO2:g-C3N4-COOH is 1:3]]> 0.9956 0.9813 98.56 <![CDATA[SiO2:g-C3N4-COOH is 1:1]]> 1.3000 1.2794 98.42 <![CDATA[SiO2:g-C3N4-COOH is 1:2]]> 0.9472 0.8900 93.96 <![CDATA[SiO2:g-C3N4-COOH is 1:3]]> 1.1286 1.1214 99.36 Table 6 Alkali resistance of sealing agents Sample Name <![CDATA[M1(g)]]> <![CDATA[M2(g)]]> <![CDATA[R OH (%)]]> <![CDATA[SiO2]]> 1.1318 1.1302 99.86 <![CDATA[TiO2]]> 1.0739 1.0674 99.39 <![CDATA[SiO2 and TiO2]]> 1.1702 1.1684 99.85 <![CDATA[g-C3N4-COOH]]> 0.9359 0.9274 99.09 <![CDATA[TiO2:g-C3N4-COOH is 1:1]]> 1.0948 1.0841 99.02 <![CDATA[TiO2:g-C3N4-COOH is 1:2]]> 0.9593 0.9528 99.32 <![CDATA[The ratio of TiO2:g-C3N4-COOH is 1:3]]> 1.0440 1.0432 99.92 <![CDATA[SiO2:g-C3N4-COOH is 1:1]]> 1.4377 1.4242 99.06 <![CDATA[SiO2:g-C3N4-COOH is 1:2]]> 1.7114 1.6972 99.17 <![CDATA[SiO2:g-C3N4-COOH is 1:3]]> 0.9762 0.9638 98.73 The results showed that the alkali resistance of TiO2:g-C3N4-COOH with a ratio of 1:3 was 99.92%, and the acid resistance was 98.56%. The overall results showed that the sealing agent of this formulation has excellent acid and alkali resistance. In an alkaline environment, in a formulation where TiO2:g-C3N4-COOH is 1:3, the metal-oxygen bonds of TiO2 are relatively stable under alkaline conditions, and the functional groups such as the hydroxyl groups of g-C3N4-COOH, after combining with TiO2, have a strong sealing effect on OH-. This system synergistically inhibits the damage of OH- to the sealing agent film, so it has good alkali resistance.

[0037] 6) Light transmittance of different types of sealing agent coatings like Figure 5 As shown in the figure, when the ratio of g-C3N4-COOH to TiO2 is 2:1 and 3:1, the transmittance in the visible light band is above 70%, indicating that the sealing agent film is completely transparent. Through comparison, it was found that adding a certain amount of g-C3N4-COOH mixed with nanoparticles can reduce the transmittance. When the ratio of g-C3N4-COOH to TiO2 and SiO2 is 3:1, the multi-component synergy can maximize the shielding of ultraviolet rays. The nano-level mixed particles can absorb and scatter ultraviolet light. Furthermore, when the proportion of each particle is appropriate, the aggregation between particles is reduced, making the sealing agent film completely transparent in the visible light region. Therefore, the sealing agent film is not only completely transparent, but also has relatively good UV resistance.

[0038] 7) Aging test Accelerated aging was performed at 80 ℃ for 7 days. Figure 6 The images show the appearance of the film before and after the aging experiment. The results show that after accelerated aging, the appearance of the sealing agent film did not change significantly. There were no cracks, bubbles, yellowing or other phenomena on the film surface, and it still maintained its smoothness and transparency.

[0039] The fact that the sealing agent film remains smooth and crack-free at high temperatures indicates that the chemical bonds inside the sealing agent film have not undergone any destructive reactions such as breakage or recombination. The fact that the sealing agent film does not turn yellow after aging indicates that the sealing agent has a certain degree of antioxidant and anti-degradation ability. This may be because there are antioxidant groups in the sealing agent. Furthermore, as can be seen from the SEM image, the sealing agent film has a dense structure, which can prevent the penetration of harmful substances such as water vapor and reduce the erosion of external factors, demonstrating that the sealing agent has good thermal stability and aging resistance.

[0040] 8) Data on the breathability of the sealant As shown in Table 7.

[0041] Table 7. Air permeability data of occlusive agents Types of sealing agents Total water loss (g) <![CDATA[Air permeability (g / m 2 ·24 h)]]> <![CDATA[TiO2]]> 7.45 95.62 <![CDATA[SiO2 and TiO2]]> 6.01 77.14 <![CDATA[SiO2:g-C3N4-COOH is 1:1]]> 6.61 84.84 <![CDATA[SiO2:g-C3N4-COOH is 1:2]]> 7.61 97.68 <![CDATA[SiO2:g-C3N4-COOH is 1:3]]> 7.02 90.10 <![CDATA[TiO2:g-C3N4-COOH is 1:1]]> 8.96 76.83 <![CDATA[TiO2:g-C3N4-COOH is 1:2]]> 7.16 91.90 <![CDATA[TiO2:g-C3N4-COOH is 1:3]]> 6.74 86.51 <![CDATA[g-C3N4-COOH]]> 8.03 68.86 <![CDATA[SiO2]]> 7.9 67.74 The total testing time was 168 hours. The weights of the beakers and water were recorded before and after the test. As shown in Table 7, all the sealing agents in this experiment have good air permeability. The sealing agent with a TiO2:g-C3N4-COOH ratio of 1:3 has an air permeability of 86.51%, which meets the basic requirements for the air permeability of sealing agents.

[0042] The various embodiments described in this specification are presented in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A nano-modified sealing agent with excellent acid and alkali resistance, characterized in that, By weight percentage, it includes: 0.5%-1% nanoparticles, 8% microcrystalline wax, 55% petroleum ether, 1% benzotriazole, and the balance being ethanol; The nanoparticles are a mixture of g-C3N4-COOH and nano-TiO2.

2. The nano-modified sealing agent with excellent acid and alkali resistance according to claim 1, characterized in that, The ratio of g-C3N4-COOH to nano-TiO2 by mass is 3:

1.

3. A method for preparing a nano-modified sealing agent with excellent acid and alkali resistance as described in any one of claims 1-2, characterized in that, Includes the following steps: (1) Melt the microcrystalline wax to obtain a microcrystalline wax liquid, then add petroleum ether and benzotriazole to the wax liquid and mix evenly; (2) g-C3N4-COOH and nano-TiO2 were ultrasonically dispersed in anhydrous ethanol to obtain a nano solution; (3) Add the nano solution prepared in step (2) to the mixed solution in step (1) and ultrasonically disperse and mix thoroughly. Cool at room temperature to obtain the modified sealing agent.

4. The method for preparing a nano-modified sealing agent with excellent acid and alkali resistance according to claim 3, characterized in that, In step (1), the melting temperature of microcrystalline wax is 60-70℃.

5. The method for preparing a nano-modified sealing agent with excellent acid and alkali resistance according to claim 3, characterized in that, In step (1), benzotriazole is added to the wax solution in the form of a 2% (w / w) BTA ethanol solution.

6. The method for preparing a nano-modified sealing agent with excellent acid and alkali resistance according to claim 3, characterized in that, The preparation method of the g-C3N4-COOH is as follows: S1. Melamine was placed in a tube furnace and fired under a nitrogen atmosphere. After cooling to room temperature, it was taken out and ground to obtain a yellow powder, which is g-C3N4. g-C3N4 was ultrasonicated for 48 hours. S2. Prepare a mixed solution of concentrated nitric acid and concentrated sulfuric acid, add g-C3N4 obtained in step S1, heat to boiling, stir under reflux for 2 hours, wash with distilled water until pH is neutral, and dry at 80℃ to obtain carboxylated g-C3N4-COOH.

7. The method for preparing a nano-modified sealing agent with excellent acid and alkali resistance according to claim 6, characterized in that, S1 is fired at 550℃ for 2 hours.

8. The method for preparing a nano-modified sealing agent with excellent acid and alkali resistance according to claim 6, characterized in that, The volume ratio of concentrated nitric acid to concentrated sulfuric acid in S2 is 1:

3.

9. The method for preparing a nano-modified sealing agent with excellent acid and alkali resistance according to claim 6, characterized in that, The mass-to-volume ratio of g-C3N4 in S2 to the mixture of concentrated nitric acid and concentrated sulfuric acid is 1 g: 6 mL.

10. The method for preparing a nano-modified sealing agent with excellent acid and alkali resistance according to claim 6, characterized in that, The drying temperature in S2 is 80℃.

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