A composite metal cultural relic sealing agent and a preparation and use method thereof

Abstract

This invention discloses a composite sealant for metal artifacts and its preparation and application method, comprising a base sealant and a top sealant. The base sealant comprises 20-40 parts by weight of a film-forming substance, 0.5-5 parts by weight of a composite corrosion inhibitor, and 55-79 parts by weight of a first solvent. The composite corrosion inhibitor comprises benzotriazole and 2-mercaptobenzothiazole, with a mass ratio of benzotriazole to 2-mercaptobenzothiazole of 1:0.2-1:5. The top sealant comprises 20-40 parts by weight of a film-forming substance, 1-10 parts by weight of nano-silica, 0.5-5 parts by weight of a hydrophobic modifier, and 45-78 parts by weight of a second solvent. This invention achieves efficient and durable protection for metal artifacts through the synergistic combination of benzotriazole and 2-mercaptobenzothiazole in the base sealant, exhibiting advantages such as good water resistance, strong salt spray corrosion resistance, high transparency, and good reversibility.

Description

Technical Field

[0001] This invention relates to the field of cultural relic sealing technology, specifically to a composite metal cultural relic sealing agent and its preparation and application method. Background Technology

[0002] Metal artifacts refer to cultural relics made of metal materials that possess historical, artistic, and scientific value, mainly including bronzes, ironware, goldware, silverware, tinware, and leadware. Protecting unearthed ancient artifacts, as well as those exposed to the elements, is a complex and challenging systemic project. Environmental factors affecting artifacts primarily include temperature, humidity, air pollution, and light radiation. Sealing is a crucial step in the preservation of metal artifacts, involving coating the surface with natural or synthetic materials to form a protective film. This film isolates or reduces the erosion caused by corrosive media in the external environment, thus achieving protection. Currently, commonly used materials for sealing metal artifacts include microcrystalline wax, acrylic resin, polyurethane, fluorocarbon resin, and silane materials. However, existing sealing materials still have many shortcomings in practical applications.

[0003] Patent document CN106350792A discloses a metal surface corrosion inhibitor, whose composition includes 2-mercaptobenzothiazole MBT, 2-mercaptobenzoimidazolium MBI, 2-mercaptobenzothiazole MBO, benzotriazole BTA, polyacrylic acid resin, polyethylene ester, lubricant, and surfactant. The weight percentage of 2-mercaptobenzothiazole MBT:2-mercaptobenzoimidazolium MBI:2-mercaptobenzothiazole MBO:benzotriazole BTA is 2:1:1:1. Benzotriazole is the most commonly used corrosion inhibitor for copper and copper alloy artifacts, but single BTA treatment still has significant room for improvement in long-term protective effects. This solution simply mixes multiple corrosion inhibitors without optimizing the synergistic mechanism of different corrosion inhibitors in the metal artifact protection system. Existing sealing materials cannot simultaneously meet the multiple requirements of cultural relic protection. Cultural relic protection demands that sealing materials possess basic properties such as colorlessness and transparency, no glare, strong adhesion, and good reversibility, while also exhibiting excellent waterproofing, corrosion resistance, and UV aging resistance. Single-material systems often compromise on certain aspects. Furthermore, research on double-layer composite sealing structures is gaining attention, but the functional synergy between the bottom and top layers in double-layer composite sealing technology remains insufficient.

[0004] Therefore, this invention proposes a composite metal artifact sealing agent and its preparation and application method, which can achieve efficient protection of metal artifacts. Summary of the Invention

[0005] (a) Technical problems to be solved

[0006] This invention aims to solve the aforementioned technical problems of existing metal artifact sealing materials, particularly the limited corrosion inhibition efficiency of single sealing materials, insufficient functional synergy of double-layer composite structures, and the difficulty in balancing coating transparency and protective performance. It provides a composite metal artifact sealing agent that achieves high-efficiency protection through a dual mechanism of synergistic corrosion inhibitor formulation and nanomaterial surface modification, as well as its preparation and application methods.

[0007] (II) Technical Solution

[0008] To achieve the above objectives, the present invention provides the following technical solution: a composite metal artifact sealant, comprising a base sealant and a top sealant;

[0009] The raw material components of the underlying sealing agent include: 20-40 parts by weight of film-forming substance, 0.5-5 parts by weight of composite corrosion inhibitor, and 55-79 parts by weight of first solvent; the composite corrosion inhibitor contains benzotriazole and 2-mercaptobenzothiazole, and the mass ratio of benzotriazole to 2-mercaptobenzothiazole is 1:0.2-1:5.

[0010] Benzotriazole is a classic corrosion inhibitor for copper and copper alloys. It forms a dense complex protective film on the metal surface by forming a coordination bond between the nitrogen atom on the triazole ring and copper ions, effectively inhibiting the anodic dissolution reaction of the metal. 2-Mercaptobenzothiazole, on the other hand, is a sulfur-containing heterocyclic corrosion inhibitor. Its mercapto group (-SH) and the nitrogen and sulfur atoms on the thiazole ring can form stable chelate structures with metal ions, exhibiting good corrosion inhibition performance on various metals such as copper, iron, and silver.

[0011] The raw material components of the surface sealing agent include: 20-40 parts by weight of film-forming substance, 1-10 parts by weight of nano-silica, 0.5-5 parts by weight of hydrophobic modifier, and 45-78 parts by weight of second solvent.

[0012] Nano-silica possesses a high specific surface area and excellent reinforcing effect. Adding nano-silica to the topcoat sealant can significantly improve the thermal stability, corrosion resistance, and mechanical properties of the coating. This invention uses a hydrophobic modifier to modify the surface of nano-silica, changing it from hydrophilic to hydrophobic. This improves the dispersion stability of nanoparticles in the film-forming material and constructs a micro-nano rough structure on the surface of the sealant, endowing the coating with superhydrophobic properties and significantly enhancing its waterproof and self-cleaning performance.

[0013] As a preferred embodiment, the mass ratio of benzotriazole to 2-mercaptobenzothiazole in the underlying sealing agent is 1:0.5 to 1:2.

[0014] As a preferred embodiment, the film-forming substances in the underlayer sealant and the toplayer sealant are each independently selected from one or more of waterborne polyurethane resin, acrylic resin, pure acrylic emulsion, and fluorocarbon resin.

[0015] As a preferred embodiment, the nano-silica in the surface sealing agent has a particle size of 10–100 nm, preferably 20–50 nm.

[0016] As a preferred embodiment, the hydrophobic modifier is selected from one or more of fluorosilane coupling agents, long-chain alkylsilane coupling agents, and fluorinated surfactants;

[0017] The fluorosilane coupling agent is selected from one or two of perfluorodecyltrimethoxysilane and perfluorooctyltriethoxysilane;

[0018] The long-chain alkylsilane coupling agent is selected from one or two of dodecyltrimethoxysilane and hexadecyltrimethoxysilane.

[0019] As a preferred embodiment, the first solvent and the second solvent are each independently selected from one or more of water, ethanol, isopropanol, acetone, and ethyl acetate.

[0020] As a preferred embodiment, the raw material components of the topcoat sealant further include 0.1 to 2 parts by weight of a leveling agent and / or 0.1 to 2 parts by weight of a defoamer; the leveling agent is selected from one or more of polyether-modified polysiloxane and acrylate leveling agents; the defoamer is selected from one or more of polysiloxane defoamers and polyether defoamers.

[0021] A method for preparing a composite sealant for metal cultural relics, characterized by comprising the following steps:

[0022] Step 1, Preparation of the underlayer sealant: Mix benzotriazole and 2-mercaptobenzothiazole at a mass ratio of 1:0.2 to 1:5, dissolve them in the first solvent, and stir until completely dissolved to obtain a composite corrosion inhibitor solution; add the film-forming substance to the composite corrosion inhibitor solution, stir evenly, and filter to obtain the underlayer sealant;

[0023] Step 2, preparation of the topcoat sealant: Disperse nano-silica in a second solvent, ultrasonically disperse for 10-30 min, add a hydrophobic modifier, and stir and react at 40-80℃ for 1-4 h to obtain a modified nano-silica dispersion; add the film-forming substance to the modified nano-silica dispersion, stir evenly, filter, and the topcoat sealant is obtained.

[0024] As a preferred embodiment, the ultrasonic dispersion power in step two is 200–800 W, the stirring reaction temperature is 50–70 °C, and the reaction time is 2–3 h.

[0025] A method for using a composite sealant for metal artifacts includes the following steps:

[0026] S1, Cleaning and drying the surface of the metal artifact;

[0027] S2, Apply the base sealant evenly to the surface of the metal artifact, with a coating amount of 50–200 g / m². It cures at room temperature for 12–48 hours to form the underlying protective layer;

[0028] S3, Apply the top layer sealant evenly to the surface of the bottom layer sealant, with a coating amount of 50-200 g / L. It is cured at room temperature for 24–72 hours to form a surface protective layer.

[0029] As a preferred embodiment, in S2 and S3, the coating method is selected from brush coating, spray coating or dip coating;

[0030] In S1, the cleaning and drying process includes removing floating dust, loose rust and soluble salts by mechanical cleaning, chemical cleaning or laser cleaning, followed by rinsing with deionized water and drying at a temperature not exceeding 60°C.

[0031] The thickness of the bottom protective layer is 20–80 μm, and the thickness of the top protective layer is 20–80 μm.

[0032] (III) Beneficial Effects

[0033] Compared with existing technologies, the composite metal artifact sealing agent and its preparation and application method proposed in this invention achieve the following significant beneficial effects:

[0034] (1) This invention forms a denser and more complete corrosion-inhibiting protective film on the metal surface by combining BTA and MBT in a specific ratio range. BTA inhibits anodic dissolution by forming Cu(I)BTA complex film with copper ions, while MBT fills and repairs micro-defects on the surface through its strong chelating ability. The synergistic effect of the two significantly improves the corrosion inhibition efficiency compared with BTA treatment alone.

[0035] (2) The hydrophobically modified nano-silica in the topcoat sealant constructs a micro-nano rough structure on the coating surface, giving the coating superhydrophobic properties (water contact angle can reach over 150°), effectively preventing the penetration of moisture and corrosive electrolytes. At the same time, the filling effect of nano-silica makes the coating more dense, significantly improving the coating's barrier performance against corrosive media such as oxygen and acidic gases. The nano-silica particle size is below the visible light wavelength range, and its uniform dispersion in the film-forming material does not affect the coating's transparency. The sealant is colorless, transparent, and glare-free, and can completely preserve the original appearance and surface information of the metal artifacts, which conforms to the basic principle of "not changing the original state of the artifacts" in cultural relic protection.

[0036] (3) The water-based film-forming material system exhibits excellent adhesion to the metal substrate. Furthermore, the sealant of this invention can be dissolved and removed under mild conditions using appropriate solvents (such as acetone, ethyl acetate, etc.), facilitating subsequent reprocessing and resealing, overcoming the irreversible drawbacks of traditional thermosetting resin sealants. The water-based or alcohol-based solvent system is free of toxic and harmful organic solvents such as benzene and toluene, resulting in low volatile organic compound emissions during construction. This is beneficial to the health of cultural relic restorers and the environment, aligning with the current concept of "green protection" in cultural relic preservation. Detailed Implementation

[0037] To better understand the purpose, structure, and function of this invention, a composite metal artifact sealing agent and its preparation and application method are described in further detail.

[0038] Example 1

[0039] I. Preparation of the Underlying Sealant

[0040] Take 1.0 g of benzotriazole (BTA) and 1.0 g of 2-mercaptobenzothiazole (MBT) (mass ratio 1:1), dissolve them in 78 g of anhydrous ethanol, and stir magnetically for 30 min at room temperature until completely dissolved to obtain a clear and transparent composite corrosion inhibitor solution. Slowly add 20 g of aqueous polyurethane resin (40% solids) to the above solution, and continue stirring magnetically for 60 min at room temperature until the system is homogeneous. Filter through a 200-mesh stainless steel filter to obtain the bottom sealing agent.

[0041] II. Preparation of Topcoat Sealing Agent

[0042] 5 g of 30 nm nano-silica was dispersed in 65 g of anhydrous ethanol and ultrasonically dispersed for 20 min at 500 W (ultrasonic frequency 40 kHz). 2 g of perfluorodecyltrimethoxysilane was added to the dispersion, and the mixture was magnetically stirred in a 60 °C water bath for 2.5 h to obtain a modified nano-silica dispersion. 28 g of aqueous polyurethane resin (40% solids) was slowly added to the dispersion, and the mixture was magnetically stirred at room temperature for 60 min until homogeneous. The mixture was then filtered through a 200-mesh stainless steel filter to obtain the topcoat sealant.

[0043] III. Pretreatment of Metal Samples Before Use

[0044] Take a Q235 low-carbon steel sample (50 mm × 50 mm × 2 mm) and a bronze sample (CuSn6.5, 50 mm × 50 mm × 2 mm). Grind each sample sequentially with 400#, 800#, and 1200# wet sandpaper until the surface is smooth to remove the oxide layer. Then, ultrasonically clean each sample for 15 minutes with deionized water and anhydrous ethanol to remove surface oil and impurities. Allow the cleaned samples to air dry at room temperature for later use.

[0045] IV. Sealing Treatment

[0046] The primer was uniformly applied to the surface of the pretreated metal sample by brushing, with an application amount of approximately 120 g / m². The sample was then cured for 24 h at room temperature (25±2℃) and relative humidity of 50±5%.

[0047] Apply the top layer sealant evenly to the surface of the bottom protective layer using a brush method, with a coating amount of approximately 100 g / m². Cure under the same conditions for 48 hours to complete the sealing treatment.

[0048] Example 2

[0049] I. Preparation of the Underlying Sealant

[0050] Take 1.2 g of benzotriazole (BTA) and 0.6 g of 2-mercaptobenzothiazole (MBT) (mass ratio 2:1), dissolve them in 72 g of a mixed solvent of deionized water and anhydrous ethanol (volume ratio 1:1), and stir magnetically for 40 min at room temperature until completely dissolved. Slowly add 26 g of pure acrylic emulsion (45% solids) to the above solution, and continue stirring magnetically for 60 min at room temperature until the system is homogeneous. Filter through a 200-mesh stainless steel filter to obtain the bottom sealing agent.

[0051] II. Preparation of Topcoat Sealing Agent

[0052] 3 g of 20 nm nano-silica was dispersed in 72 g of a 1:1 mixture of deionized water and anhydrous ethanol and ultrasonically dispersed for 25 min at 400 W (ultrasonic frequency 40 kHz). 1.5 g of dodecyltrimethoxysilane was added to the dispersion, and the mixture was magnetically stirred in a 55 °C water bath for 3 h to obtain a modified nano-silica dispersion. 23 g of pure acrylic emulsion (45% solids) was slowly added to the dispersion, and the mixture was magnetically stirred at room temperature for 60 min until homogeneous. The mixture was then filtered through a 200-mesh stainless steel filter to obtain the topcoat sealant.

[0053] III. Sealing Treatment

[0054] The primer was uniformly applied to the surface of the pretreated metal sample by brushing, with an application amount of approximately 120 g / m². The sample was then cured for 24 h at room temperature (25±2℃) and relative humidity of 50±5%.

[0055] Apply the top layer sealant evenly to the surface of the bottom protective layer using a brush method, with a coating amount of approximately 100 g / m². Cure under the same conditions for 48 hours to complete the sealing treatment.

[0056] Example 3

[0057] I. Preparation of the Underlying Sealant

[0058] Take 0.8 g of benzotriazole (BTA) and 1.6 g of 2-mercaptobenzothiazole (MBT) (mass ratio 1:2), dissolve them in 70 g of isopropanol, and stir magnetically for 40 min at room temperature until completely dissolved. Slowly add 27 g of fluorocarbon resin (40% solids) to the above solution, and continue stirring magnetically for 90 min at room temperature until the system is homogeneous. Filter through a 200-mesh stainless steel filter to obtain the bottom sealing agent.

[0059] II. Preparation of Topcoat Sealing Agent

[0060] 8 g of 50 nm nano-silica was dispersed in 60 g of isopropanol and ultrasonically dispersed for 20 min at 600 W (ultrasonic frequency 40 kHz). 3 g of perfluorooctyltriethoxysilane was added to the dispersion, and the mixture was magnetically stirred in a 65 °C water bath for 3 h to obtain a modified nano-silica dispersion. 29 g of fluorocarbon resin (40% solids) was slowly added to the dispersion, and the mixture was magnetically stirred at room temperature for 90 min until homogeneous. The mixture was then filtered through a 200-mesh stainless steel filter to obtain the surface sealing agent.

[0061] III. Sealing Treatment

[0062] The primer was uniformly applied to the surface of the pretreated metal sample by brushing, with an application amount of approximately 120 g / m². The sample was then cured for 24 h at room temperature (25±2℃) and relative humidity of 50±5%.

[0063] Apply the top layer sealant evenly to the surface of the bottom protective layer using a brush method, with a coating amount of approximately 100 g / m². Cure under the same conditions for 48 hours to complete the sealing treatment.

[0064] Comparative Example 1 (single BTA corrosion inhibitor, without MBT formulation)

[0065] Preparation of the undercoat sealant: Dissolve 2.0 g of benzotriazole (BTA) in 78 g of anhydrous ethanol and stir magnetically for 30 min until completely dissolved. Slowly add 20 g of aqueous polyurethane resin (40% solids) to the above solution and continue stirring for 60 min until homogeneous. Filter through a 200-mesh screen to obtain the undercoat sealant. The topcoat sealant, its application method, and coating amount are the same as in Example 1.

[0066] Comparative Example 2 (The topcoat sealant contains no nano-silica or hydrophobic modifier)

[0067] The preparation of the base layer sealant is the same as in Example 1. Preparation of the top layer sealant: Take 33 g of waterborne polyurethane resin (40% solids), dissolve it in 67 g of anhydrous ethanol, stir for 60 min until homogeneous, and filter through a 200-mesh screen to obtain the top layer sealant. The application method and coating amount are the same as in Example 1.

[0068] Comparative Example 3 (The nano-silica in the topcoat sealant was not hydrophobically modified)

[0069] The preparation of the bottom layer sealant is the same as in Example 1. Preparation of the top layer sealant: Take 5g of 30 nm nano-silica and disperse it in 65g of anhydrous ethanol. Sonicate the dispersion at 500 W for 20 min to obtain a nano-silica dispersion (without adding a hydrophobic modifier). Slowly add 28g of aqueous polyurethane resin (40% solids) to the dispersion and continue stirring for 60 min until homogeneous. Filter through a 200-mesh screen to obtain the top layer sealant. The application method and coating amount are the same as in Example 1.

[0070] Comparative Example 4 (BTA to MBT mass ratio exceeds the scope of this invention)

[0071] Preparation of the base layer sealant: Dissolve 1.6 g of benzotriazole (BTA) and 0.2 g of 2-mercaptobenzothiazole (MBT) (mass ratio 8:1) in 78 g of anhydrous ethanol, the rest being the same as in Example 1. The top layer sealant is the same as in Example 1. The application method and coating amount are the same as in Example 1.

[0072] Performance testing and characterization

[0073] I. Adhesion Test

[0074] The cross-cut adhesion test was conducted according to GB / T 9286-2021 "Paints and Varnishes - Cross-cut Test". The surface of the metal sample coated with the protective layer was cut into a 1 mm × 1 mm grid using a cross-cutting tool (the cut depth penetrated the coating to the metal substrate). The grid was then adhered with 3M adhesive tape and quickly peeled off. The extent of coating peeling was observed under a magnifying glass. Test results were graded from 0 to 5, with 0 being the best (completely smooth cut edges, no grid peeling) and 5 being the worst (peeling area greater than 65%). The test results are shown in Table 1.

[0075]

[0076] Table 1 Adhesion test results

[0077] As shown in Table 1, the adhesion of Examples 1 and 2 both reached grade 0 (the best grade), while Example 3 reached grade 1. Comparative Examples 2 and 3 showed an adhesion grade of 2, indicating that the introduction of nano-silica helps enhance the mechanical properties of the coating. However, the uneven dispersion of the unmodified nano-silica led to a decrease in the coating's cohesion. The only difference between Comparative Example 1 and Example 1 was the composition of the underlying corrosion inhibitor; their adhesion was similar, indicating that the composition of the underlying corrosion inhibitor has little impact on adhesion.

[0078] II. Surface water contact angle test

[0079] The static water contact angle of the metal sample surface after coating was measured using a contact angle meter. Test conditions: room temperature (25±1℃), relative humidity 50±5%, test droplet was deionized water, droplet volume 5 μL, each sample was measured 5 times at different locations and the average value was taken. The test results are expressed as the arithmetic mean ± standard deviation. The test results are shown in Table 2.

[0080]

[0081] Table 2 Water contact angle test results

[0082] As shown in Table 2, the water contact angles of Examples 1-3 all reached or exceeded 148.7°, with Example 3 reaching a maximum of 156.8°, all achieving superhydrophobicity (contact angle > 150°). Comparative Example 1, with the same surface layer composition as Example 1, also achieved a contact angle of 151.8°; Comparative Example 2, without the addition of nano-silica, had a contact angle of only 98.5°, exhibiting a hydrophilic state; Comparative Example 3, although containing nano-silica, did not undergo hydrophobic modification, resulting in a contact angle of 112.4°, exhibiting hydrophobicity but not reaching superhydrophobicity. These results indicate that hydrophobic modification of nano-silica is a key factor in imparting superhydrophobic properties to the coating.

[0083] III. Saltwater Immersion Resistance Test

[0084] The metal samples treated in Examples 1-3 and each comparative example, as well as the untreated blank sample, were completely immersed in a 3.5 wt% NaCl aqueous solution and soaked at room temperature (25±2℃) for 30 days, with the solution being changed every 5 days. After soaking, the samples were removed, the surface was gently rinsed with deionized water, dried at room temperature, and the macroscopic morphology of the sample surface was photographed with a digital camera, and the microscopic morphology of the surface was observed with a scanning electron microscope.

[0085] The test results are as follows:

[0086] Blank sample (untreated): After immersion for 7 days, obvious yellowish-brown rust spots appeared on the surface. After immersion for 15 days, the rust coverage exceeded 80%, and a loose rust layer was formed on the surface. After 30 days, the thickness of the rust layer increased significantly, showing a typical uniform corrosion morphology.

[0087] The sample treated in Example 1: After immersion for 30 days, no obvious rust spots were found on the surface, and the coating remained intact, smooth, and transparent. SEM observation showed that the coating surface structure was dense, with no corrosion products observed. The bottom sealant was well bonded to the metal substrate, and the micro-nano rough structure formed by nano-silica in the top sealant remained intact.

[0088] Samples treated in Examples 2 and 3: The results were similar to those in Example 1. After soaking for 30 days, there was no obvious rust on the surface, and the coating remained in good condition.

[0089] The sample treated in Comparative Example 1 showed scattered rust spots on the surface after immersion for 25 days. The coating around the rust spots showed slight blistering, indicating that the long-term protective effect of a single BTA corrosion inhibitor was not as good as that of the BTA / MBT compound system.

[0090] The sample treated in Comparative Example 2: After soaking for 18 days, multiple rust spots appeared on the surface, and the rust area was significantly larger than that in Comparative Example 1. This indicates that the surface layer lacks the reinforcement of nano-silica, and the physical barrier properties of the coating are insufficient, making it easier for corrosive media to penetrate to the metal surface.

[0091] The sample treated in Comparative Example 3 showed localized blistering and corrosion after immersion for 22 days. The degree of corrosion was between that in Comparative Example 1 and Comparative Example 2. This indicates that although the unmodified nano-silica enhanced the density of the coating to some extent, the failure to construct a superhydrophobic surface meant that water had strong wettability on the coating surface and could still penetrate the coating.

[0092] The sample treated in Comparative Example 4 showed sporadic rust on the surface after immersion for 27 days. The corrosion was slightly better than that in Comparative Example 1 but significantly worse than that in Example 1. This indicates that when the mass ratio of BTA to MBT exceeds the range of the present invention, the synergistic effect of the corrosion inhibitor is weakened and the long-term protective performance decreases.

[0093] The above results show that the present invention significantly improves the corrosion resistance of metal artifacts through the synergistic effect of the bottom layer of BTA / MBT composite corrosion inhibitor and the top layer of hydrophobic modified nano-silica.

[0094] It is understood that the present invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Furthermore, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present invention.

Claims

1. A composite sealant for metal cultural relics, characterized in that, Includes a base sealant and a top sealant; The raw material components of the underlying sealing agent include: 20-40 parts by weight of film-forming substance, 0.5-5 parts by weight of composite corrosion inhibitor, and 55-79 parts by weight of first solvent; the composite corrosion inhibitor contains benzotriazole and 2-mercaptobenzothiazole, and the mass ratio of benzotriazole to 2-mercaptobenzothiazole is 1:0.2-1:

5. The raw material components of the surface sealing agent include: 20-40 parts by weight of film-forming substance, 1-10 parts by weight of nano-silica, 0.5-5 parts by weight of hydrophobic modifier, and 45-78 parts by weight of second solvent.

2. The composite metal artifact sealing agent according to claim 1, characterized in that, In the underlying sealing agent, the mass ratio of benzotriazole to 2-mercaptobenzothiazole is 1:0.5 to 1:

2.

3. The composite metal artifact sealing agent according to claim 1, characterized in that, The film-forming substances in the bottom and top sealing agents are each independently selected from one or more of waterborne polyurethane resin, acrylic resin, pure acrylic emulsion, and fluorocarbon resin.

4. The composite metal artifact sealing agent according to claim 1, characterized in that, In the surface sealing agent, the particle size of nano-silica is 10-100 nm, preferably 20-50 nm.

5. The composite metal artifact sealing agent according to claim 1, characterized in that, The hydrophobic modifier is selected from one or more of fluorosilane coupling agents, long-chain alkylsilane coupling agents, and fluorinated surfactants; The fluorosilane coupling agent is selected from one or two of perfluorodecyltrimethoxysilane and perfluorooctyltriethoxysilane; The long-chain alkylsilane coupling agent is selected from one or two of dodecyltrimethoxysilane and hexadecyltrimethoxysilane.

6. The composite metal artifact sealing agent according to claim 1, characterized in that, The first solvent and the second solvent are each independently selected from one or more of water, ethanol, isopropanol, acetone, and ethyl acetate.

7. The composite metal artifact sealing agent according to claim 1, characterized in that, The raw material components of the surface sealing agent further include 0.1 to 2 parts by weight of leveling agent and / or 0.1 to 2 parts by weight of defoamer; the leveling agent is selected from one or more of polyether modified polysiloxane and acrylate leveling agents; the defoamer is selected from one or more of polysiloxane defoamers and polyether defoamers.

8. A method for preparing a composite metal artifact sealant according to any one of claims 1 to 7, characterized in that, Includes the following steps: Step 1, Preparation of the underlayer sealant: Mix benzotriazole and 2-mercaptobenzothiazole at a mass ratio of 1:0.2 to 1:5, dissolve them in the first solvent, and stir until completely dissolved to obtain a composite corrosion inhibitor solution; add the film-forming substance to the composite corrosion inhibitor solution, stir evenly, and filter to obtain the underlayer sealant; Step 2, preparation of the topcoat sealant: Disperse nano-silica in a second solvent, ultrasonically disperse for 10-30 min, add a hydrophobic modifier, and stir and react at 40-80℃ for 1-4 h to obtain a modified nano-silica dispersion; add the film-forming substance to the modified nano-silica dispersion, stir evenly, filter, and the topcoat sealant is obtained.

9. A method for using a composite metal artifact sealant according to any one of claims 1 to 7, characterized in that, Includes the following steps: S1, Cleaning and drying the surface of the metal artifact; S2, Apply the base sealant evenly to the surface of the metal artifact, with a coating amount of 50–200 g / m². It cures at room temperature for 12–48 hours to form the underlying protective layer; S3, Apply the top layer sealant evenly to the surface of the bottom layer sealant, with a coating amount of 50-200 g / L. It is cured at room temperature for 24–72 hours to form a surface protective layer.

10. The method of using a composite metal artifact sealant according to claim 9, characterized in that, In S2 and S3, the coating method is selected from one of brush coating, spray coating or dip coating; In S1, the cleaning and drying process includes removing floating dust, loose rust and soluble salts by mechanical cleaning, chemical cleaning or laser cleaning, followed by rinsing with deionized water and drying at a temperature not exceeding 60°C. The thickness of the bottom protective layer is 20–80 μm, and the thickness of the top protective layer is 20–80 μm.

Images