Corrosion-resistant early-warning coating, preparation method and application of corrosion-resistant early-warning coating to environmental monitoring equipment

Abstract

The invention relates to the technical field of anti-corrosion coatings, in particular to an anti-corrosion early warning coating, a preparation method and application of the anti-corrosion early warning coating to environment monitoring equipment. The corrosion-resistant early-warning coating comprises an inner-layer coating and an outer-layer coating, wherein the outer-layer coating is prepared from the following components: a water-based fluorocarbon emulsion, a reinforcing agent, a polyether siloxane flatting agent and water; the inner-layer coating is prepared from the following components: waterborne epoxy emulsion, fluorescent particles, a waterborne amine curing agent, a polyether siloxane flatting agent and water. According to the double-layer structure coating prepared through the technical scheme, through the synergistic effect of the innovative reinforcing agent and the fluorescent particles, the excellent acid resistance is achieved, and the adhesive force can reach 26.5 MPa to the maximum; meanwhile, whether the surface protection state of the environment monitoring equipment is intact or not can be studied and judged immediately.

Description

Technical Field

[0001] This invention relates to the field of anti-corrosion coating technology, and more specifically, to a corrosion-resistant early warning coating and its preparation method, as well as its application in environmental monitoring equipment. Background Technology

[0002] High temperature, high humidity, high salinity, and high acidity are extreme environmental factors that severely corrode the casing of VOCs environmental monitoring equipment. Traditional anti-corrosion coatings are insufficient to meet long-term protection requirements, especially in terms of timely assessment of protective effectiveness. Corrosion products can flake off and enter the detection gas path, becoming a secondary VOCs source and interfering with the monitoring of low-concentration VOCs. Furthermore, if the coating itself releases a large amount of organic compounds, it can also increase the background radiation, affecting data accuracy. Existing technologies attempt to improve the weather resistance and corrosion resistance of epoxy coatings through fluorocarbon modification. Patent CN202011554821.1 discloses a hollow microsphere fluorocarbon emulsion-modified waterborne epoxy resin coating and its preparation method. The coating comprises two components, A and B. Component A includes waterborne epoxy resin, anti-settling agent, aluminum powder, mica powder, barium sulfate, and corrosion inhibitor; component B includes hollow microsphere fluorocarbon emulsion, film-forming aid, and waterborne epoxy curing agent. Component A and component B are mixed and stirred evenly at a mass ratio of 50.5–108:11–35 to obtain the hollow microsphere fluorocarbon emulsion-modified waterborne epoxy resin coating. This invention utilizes the good weather resistance and stain resistance of fluorocarbon resin itself, solving the problem of poor weather resistance and stain resistance of ordinary waterborne epoxy coatings, and improving corrosion resistance. However, the complex raw materials may introduce potential VOCs into the coating, and the protective effect cannot be assessed in a timely manner. Therefore, a coating system specifically designed for special environments, with low VOC release, excellent anti-corrosion performance, and timely assessment of protective effect is needed. Summary of the Invention

[0003] To overcome the shortcomings of the prior art described above, the present invention provides a corrosion-resistant early warning coating.

[0004] The present invention also provides a method for preparing a corrosion-resistant early warning coating.

[0005] This invention also provides an application of a corrosion-resistant early warning coating.

[0006] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows: A corrosion-resistant early warning coating includes an inner coating and an outer coating: The outer coating is prepared according to the following components by weight: 50-70 parts of water-based fluorocarbon emulsion, 8-12 parts of reinforcing agent, 0.3-0.5 parts of polyether siloxane leveling agent, and 8-12 parts of water; The inner coating is prepared according to the following components by weight: 40-60 parts of waterborne epoxy emulsion, 7-9 parts of fluorescent particles, 15-17 parts of waterborne amine curing agent, 0.2-0.5 parts of polyether siloxane leveling agent, and 10-15 parts of water. The fluorescent particles were prepared from a raw material containing 4-methylumbelliferone; The reinforcing agent is prepared from a raw material containing quercetin.

[0007] Preferably, the solid content in the aqueous fluorocarbon emulsion is 45% to 50%.

[0008] Preferably, the aqueous epoxy emulsion has an epoxy equivalent of 800~900 g / mol.

[0009] Preferably, the aqueous amine curing agent comprises polyetheramine.

[0010] Preferably, the polyether siloxane leveling agent comprises polyether-modified polydimethylsiloxane.

[0011] Furthermore, the method for preparing the reinforcing agent includes the following steps: Quercetin, formaldehyde, and polyethyleneimine were added to an aqueous ethanol solution, the pH was adjusted, the reaction was carried out, and the mixture was distilled under reduced pressure to obtain the reinforcing agent.

[0012] Preferably, in the method for preparing the reinforcing agent, the molecular weight of the polyethyleneimine is 9000~11000.

[0013] Preferably, in the method for preparing the reinforcing agent, the molar ratio of quercetin to formaldehyde is (0.9~1.1):1.

[0014] Preferably, in the method for preparing the reinforcing agent, the mass ratio of quercetin:polyethyleneimine:ethanol aqueous solution is (2~4):18:50.

[0015] Preferably, in the method for preparing the reinforcing agent, the pH is adjusted to 4-6.

[0016] Preferably, in the method for preparing the reinforcing agent, the reaction temperature is 70~100℃ and the reaction time is 2~4h.

[0017] More preferably, in the method for preparing the reinforcing agent, the reaction temperature is 85~95℃.

[0018] Preferably, in the method for preparing the reinforcing agent, the vacuum distillation includes the use of a rotary evaporator.

[0019] Preferably, in the method for preparing the reinforcing agent, the ethanol aqueous solution contains ethanol and water, and the mass percentage concentration of ethanol is 60% to 80%.

[0020] Furthermore, the method for preparing fluorescent particles includes the following steps: S1 was reacted with nano-silica and 3-aminopropyltriethoxysilane (KH550) in anhydrous ethanol, cooled, centrifuged to collect the precipitate, washed and dried to obtain NH2-nano-silica particles. In step S2, 4-methylumbelliferone, the NH2-nano silica particles obtained in step S1, and formaldehyde are added to anhydrous ethanol. The mixture is reacted, cooled, centrifuged, and the precipitate is collected. The precipitate is washed three times with anhydrous ethanol and dried to obtain fluorescent particles.

[0021] Preferably, the particle size range of the nano-silica in step S1 is 10~30 nm.

[0022] Preferably, the mass ratio of nano-silica to 3-aminopropyltriethoxysilane (KH550) in step S1 is (19~21):1.

[0023] Preferably, the mass-to-volume ratio of nano-silica to anhydrous ethanol in step S1 is 1 g: (3~5) mL.

[0024] Preferably, the reaction temperature in step S1 is 75~85℃, and the reaction time is 3~5 h.

[0025] Preferably, the centrifugal speed in step S1 is 4000~6000 rpm.

[0026] Preferably, the washing in step S1 includes washing three times with anhydrous ethanol.

[0027] Preferably, the molar ratio of 4-methylumbelliferone to formaldehyde in step S2 is (0.9~1.1):1.

[0028] Preferably, the mass-to-volume ratio of NH2-nano silica to anhydrous ethanol in step S2 is 1 g: (3~5) mL.

[0029] Preferably, the mass ratio of NH2-nano silica to 4-methylumbelliferone in step S2 is (19~21):1.

[0030] Preferably, the reaction temperature in step S2 is 75~85℃, and the reaction time is 3~5 h.

[0031] Preferably, the centrifugal speed in step S2 is 4000~6000 rpm.

[0032] Preferably, the washing in step S2 includes washing three times with anhydrous ethanol.

[0033] Furthermore, the method for preparing the corrosion-resistant early warning coating includes the following steps: (1) Apply the inner coating to the substrate and dry it to form the inner coating layer; (2) Apply the outer coating onto the inner coating, dry it to form the outer coating, and cure it at 50~85℃ for 1~2 h to obtain the corrosion-resistant early warning coating.

[0034] Preferably, the dry weight of the inner coating is 0.2~0.5 g / cm³. 2 .

[0035] Preferably, the dry weight of the outer coating is 0.3~0.6 g / cm³. 2 .

[0036] More preferably, the dry weight of the inner coating is 0.3~0.4 g / cm³. 2 .

[0037] More preferably, the dry weight of the outer coating is 0.3~0.5 g / cm³. 2 .

[0038] Preferably, the curing temperature in step (2) is 75~85℃.

[0039] Preferably, the curing temperature in step (2) is 78~82℃.

[0040] The corrosion-resistant early warning coating prepared by the method described in this invention is applied in the field of VOCs environmental monitoring equipment.

[0041] In this invention, 4-methylumbelliferone is creatively covalently bonded to the surface of nano-silica to form a fluorescent core, which is covalently locked and does not release any free volatile gas.

[0042] In this invention, the reaction of quercetin with polyethyleneimine endows the topcoat with three functions: ring-opening crosslinking with epoxy to improve adhesion; quercetin can enhance the shielding of ultraviolet light and work with fluorocarbon to isolate 365 nm excitation light, so that the inner layer does not emit excitation light when the outer layer is intact; and it further enhances adhesion by working with the inner coating layer to crosslink.

[0043] In this invention, the inner coating and the outer coating constitute a double coating with the outer coating blocking light and the inner coating emitting light. Each of them undertakes key functions and forms a synergistic effect: the inner coating locks in the light and forms a fluorescent nucleus, and the crack exhibits blue-green fluorescence under 365 nm excitation; the outer coating isolates ultraviolet light, ensuring that there is no light when the coating is intact, and the crack is excited by ultraviolet light. This invention is suitable for the field of VOCs environmental monitoring equipment.

[0044] Compared with the prior art, the beneficial effects of the technical solution of the present invention are: The double-layer coating prepared by the technical solution of this invention is a corrosion-resistant coating made by innovative reinforcing agents and fluorescent particles. It not only has excellent acid resistance, but also has an adhesion of up to 26.5 MPa. Moreover, the failure status of this coating can be judged on site, making it particularly suitable for VOCs on-site environmental monitoring tools, sampling tools, gas storage cylinders and other equipment under special environmental conditions. Attached Figure Description

[0045] Figure 1 Fluorescence emission spectrum of the inner coating in Example 1. Detailed Implementation

[0046] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in this technical field.

[0047] Unless otherwise specified, all reagents and materials used in the following examples are commercially available.

[0048] Aqueous fluorocarbon emulsion, solid content: 48%, purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0049] The waterborne epoxy emulsion Banco 2060H 850 has an epoxy equivalent of 850 g / mol and was purchased from Lian Gu Chemical.

[0050] Polyethyleneimine (PEI) with a molecular weight of 10,000 (MW) was purchased from Aladdin Reagent (Shanghai) Co., Ltd.

[0051] Nano SiO2 (nano silica) S698334 with a particle size of 20 nanometers and a purity of 99 wt% was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0052] KH550, A800524, 3-aminopropyltriethoxysilane, 98%, purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0053] Quercetin, Q817162 Quercetin, 97%, purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0054] 4-Methylumbelliferone, M813258, 98%, purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0055] Polyether siloxane leveling agent, polyether modified polydimethylsiloxane JS-3018, Shanghai Banggao Chemical.

[0056] Polyetheramine, MW 2000, EO / PO ratio: 6 / 29.

[0057] Example 1 (a) Preparation of reinforcing agents: Add 30.2g of quercetin (0.1mol), 9g of formaldehyde (0.1mol), and 180g of polyethyleneimine to 500g of 80% ethanol aqueous solution. Adjust the pH to 5 with 1mol / L hydrochloric acid aqueous solution. Incubate the reaction at 90℃ for 3h under nitrogen protection. After the reaction is completed, distill under reduced pressure at least 3 times to remove the solvent and unreacted formaldehyde to obtain the reinforcing agent.

[0058] (II) Preparation of fluorescent particles: S1 added 50g of nano-silica (20nm) and 2.5g of KH550 to 200mL of anhydrous ethanol, reacted at 80℃ for 4 h, cooled to room temperature, centrifuged at 5000rpm for 10min to collect the precipitate, washed three times with anhydrous ethanol, and dried to obtain NH2-nano-silica particles. S2 added 2.5 g of 4-methylumbelliferone, 50 g of NH2-nano silica particles, and 0.25 g of formaldehyde to 200 mL of anhydrous ethanol, reacted at 80 °C for 4 h, cooled to room temperature, centrifuged at 5000 rpm for 10 min, collected the precipitate, washed three times with anhydrous ethanol, and obtained fluorescent particles.

[0059] (III) Coating Preparation: The preparation method of the inner coating is as follows: weigh the following components according to the mass ratio: 50 parts of water-based epoxy emulsion, 8 parts of fluorescent particles, 16 parts of water-based amine curing agent (polyether amine), 0.2 parts of polyether siloxane leveling agent (polyether modified polydimethylsiloxane), and 12 parts of water, mix them, and disperse them by stirring at 200 rpm for no less than 30 min to obtain the inner coating. The outer coating is prepared by weighing the following components according to their mass percentages: 60 parts of water-based fluorocarbon emulsion, 10 parts of reinforcing agent, 0.3 parts of polyether siloxane leveling agent, and 10 parts of water. Mix them and disperse them by stirring at 200 rpm for no less than 30 minutes to obtain the outer coating.

[0060] (iv) Coating preparation: The inner coating was sprayed onto the surface of the iron sheet and dried at room temperature (25℃) for 2 hours. The amount of inner coating applied was 0.3 g / cm³, which was the dry weight (dry film weight) of the inner coating after drying. 2 Then, the outer coating is sprayed onto the surface of the inner coating, with an interval of 2 hours. The amount of outer coating applied is 0.4 g / cm³, which is the dry weight (dry film weight) of the outer coating after drying. 2 Cur at 80℃ for 1 hour.

[0061] Early warning function test method: A 365 nm LED ultraviolet lamp (3 W power, 10 cm irradiation distance) was used to vertically irradiate the coating surface, and a digital camera (ISO 800, exposure time 1 / 30 s) was used to record fluorescence images. For intact coatings, the image grayscale value was <20 (no fluorescence); after scratching the surface with a utility knife and irradiating it with ultraviolet light again, the crack showed a bluish-green fluorescence with a grayscale value >150, which was clearly visible to the naked eye. After continuous irradiation with 365 nm ultraviolet light for 168 h, the fluorescence intensity decayed by <5%, confirming the stability of the fluorescence.

[0062] The fluorescence spectrum of the inner coating was measured using a Fluorolog-4 fluorescence spectrometer. Figure 1 It can be seen that the peak fluorescence emission wavelength of the inner coating is between 503 and 507 nm.

[0063] Example 2 This embodiment is similar to Embodiment 1, except that the amount of inner layer coating sprayed in step (iv) is 0.3 g / cm³. 2 (Dry weight), the amount of outer coating used for spraying is 0.3 g / cm³. 2 (dry weight); the remaining components and steps are the same as in Example 1.

[0064] Example 3 This embodiment is similar to Embodiment 1, except that the amount of inner layer coating applied in step (iv) is 0.4 g / cm³. 2 (Dry weight), the application rate of the outer coating is 0.5 g / cm³. 2 (dry weight); the remaining components and steps are the same as in Example 1.

[0065] Example 4 This embodiment is similar to Embodiment 1, except that in step (iv), the amount of inner layer coating applied is 0.2 g / cm³ (dry weight). 2 The remaining components and steps are the same as in Example 1.

[0066] Example 5 This embodiment is similar to Embodiment 1, except that the amount of inner layer coating sprayed in step (iv) is 0.5 g / cm³. 2 The remaining components and steps are the same as in Example 1.

[0067] Example 6 This embodiment is similar to Embodiment 1, except that in step (iv), the amount of outer coating applied is 0.6 g / cm³ (dry weight). 2 The remaining components and steps are the same as in Example 1.

[0068] Example 7 This embodiment is similar to Embodiment 1, except that step (iv) involves curing at 50°C for 2 hours.

[0069] Example 8 This embodiment is similar to Embodiment 1, except that the reaction temperature in step (a) of preparing the reinforcing agent is 70°C.

[0070] Example 9 The corrosion-resistant early warning coating of the present invention was prepared on a VOCs on-site environmental monitoring instrument and a gas storage cylinder using the method of Example 1. The VOCs gas was not detected by the corrosion-resistant early warning coating of the present invention, which effectively protected the detection instrument and ensured the accuracy of the detection results.

[0071] Comparative Example 1 This comparative example is similar to Example 1, except that the inner layer coating was not sprayed in step (iv), and only the outer layer coating was sprayed according to steps (iii) and (iv) of Example 1. The dry weight of the coating was 0.4 g / cm³. 2 .

[0072] Comparative Example 2 This comparative example is similar to Example 1, except that in step (iv), the outer coating was not sprayed; only the inner coating was sprayed according to steps (iii) and (iv) of Example 1. The dry weight of the coating was 0.3 g / cm³. 2 .

[0073] Comparative Example 3 This comparative example is similar to Example 1, except that fluorescent particles were not added to the inner coating in step (iii), while the other components and steps are the same as in Example 1.

[0074] Comparative Example 4 This comparative example is similar to Example 1, except that no reinforcing agent was added to the outer coating in step (iii), while the remaining components and steps are the same as in Example 1.

[0075] Comparative Example 5 This comparative example is similar to Example 1, except that in step (iv), the amount of outer coating applied is 0.2 g / cm³ (dry weight). 2 The remaining components and steps are the same as in Example 1.

[0076] Comparative Example 6 This comparative example is similar to Example 1, except that in step (iii), unmodified 4-methylumbelliferone is directly added to the inner coating to replace the fluorescent particles, and quercetin is directly added to the outer coating to replace the reinforcing agent. The remaining components and steps are the same as in Example 1.

[0077] Comparative Example 7 This comparative example uses a commercially available ordinary metallic paint, applied to the surface of VOCs sampling canisters (tubes) and gas cylinders.

[0078] Analysis and detection The adhesion test method refers to GB / T 5210, and the acid resistance test (5% HCl) refers to GB / T 9274-1988. The fluorescence spectrum of the inner coating is tested using a Fluorolog-4 fluorescence spectrometer. The early warning function can be performed by observing whether a bluish-green fluorescence appears after the coating cracks under 365 nm LED ultraviolet light irradiation. The VOCs test method refers to GB / T 23985-2009, and the abrasion resistance test refers to GB / T 1768-2006, tested under 1000 cycles and 1000g conditions. The data are shown in Table 1 below: Table 1. Summary Data of Examples and Comparative Examples

[0079] Results Analysis As can be seen from Table 1 and Examples 1-8, the anti-corrosion coating prepared using the technical solution of the present invention has good corrosion resistance, adhesion and wear resistance, and has a visible cracking early warning function. The product prepared using the technical solution of the present invention does not contain any VOCs components, achieving undetectable VOCs release, and is suitable for the field of VOCs environmental monitoring.

[0080] As can be seen from Examples 1-3, the products prepared using the technical solutions of Examples 1-3 have better adhesion and abrasion resistance (less than or equal to 35mg).

[0081] The results of Examples 1 and Comparative Examples 1-4 show that the lack of an inner coating (Comparative Example 1), the lack of an outer coating (Comparative Example 2), the lack of fluorescent particles in the inner coating (Comparative Example 3), or the lack of reinforcing agent in the outer coating (Comparative Example 4) all lead to the damage to the functional integrity of the coating system. Specifically, the following are the manifestations: (1) Adhesion is significantly reduced. The adhesion of Comparative Example 1 (without inner coating) is only 18.9 MPa, and that of Comparative Example 2 (without outer coating) is 20.3 MPa, both lower than that of Example 1 (25.1 MPa). This indicates that the inner and outer coatings share the mechanical reinforcement function, and the absence of either one weakens the interfacial bonding. (2) Corrosion resistance is reduced. Comparative Examples 1 and 2 showed blistering after 5 days, while Example 1 showed no abnormalities after 7 days. This indicates that the synergy of the two layers is a necessary condition for acid resistance. (3) Cracking warning function is lost. Comparative Examples 1 and 3 do not have fluorescent components. Comparative Examples 2 and 4 have fluorescence, but in the fluorescence test (warning), neither can produce a fluorescence response change under 365 nm LED irradiation.

[0082] As can be seen from the results of Comparative Example 5, reducing the thickness of the outer coating not only causes a decrease in adhesion and prevents the coating from producing fluorescence response changes under 365 nm LED irradiation, but also causes the coating to lose its early warning function.

[0083] As can be seen from Comparative Example 6, directly adding fluorescent components and quercetin will greatly reduce the adhesion and corrosion resistance of the coating.

[0084] As can be seen from the results of Example 9 and Comparative Example 7, the corrosion-resistant early warning coating prepared using the technical solution of the present invention (Example 9) showed no detection of VOCs gas, effectively protecting the detection instrument and ensuring the accuracy of the on-site detection results.

[0085] The corrosion-resistant early warning coating of this invention achieves an organic unity of protective performance and damage early warning function through an innovative dual-layer synergistic structural design. The fluorescence early warning mechanism of the dual-layer coating is based on the following principle: the inner coating covalently bonds 4-methylumbelliferone to the surface of nano-silica to form a fluorescent nucleus, which produces a characteristic bluish-green fluorescence under 365 nm ultraviolet light excitation; the quercetin-polyethyleneimine reinforcing agent in the outer coating synergistically forms an ultraviolet shielding layer with the water-based fluorocarbon emulsion, effectively blocking the excitation light from penetrating to the inner layer. When the outer layer cracks due to mechanical damage or corrosion, the ultraviolet shielding effect at the crack fails, and 365 nm ultraviolet light directly irradiates the inner fluorescent nucleus, exciting it to produce a visible bluish-green fluorescence, thereby enabling real-time on-site assessment of the coating's protective integrity. This early warning mechanism is highly compatible with the specific needs of VOCs environmental monitoring equipment: on the one hand, the covalently bonded fluorescent substances do not migrate or volatilize, ensuring that the VOCs release from the coating itself is undetectable and does not interfere with the monitoring of low-concentration VOCs; on the other hand, the early warning function can quickly screen for coating damage during on-site equipment operation and maintenance, preventing corrosion products from peeling off and entering the detection gas path to form a secondary source of VOCs pollution. The synergistic effect of the two-layer coating is also reflected in the enhanced interfacial cross-linking, which improves the coating adhesion.

[0086] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A corrosion warning coating, characterized in that, The inner layer coating and the outer layer coating are prepared by using the following components: The outer layer coating is prepared by using the following components in parts by weight: water-based fluorocarbon emulsion 50-70 parts, reinforcing agent 8-12 parts, polyether siloxane leveling agent 0.3-0.5 parts, and water 8-12 parts; The inner layer coating is prepared by using the following components in parts by weight: water-based epoxy emulsion 40-60 parts, fluorescent particles 7-9 parts, water-based amine curing agent 15-17 parts, polyether siloxane leveling agent 0.2-0.5 parts, and water 10-15 parts; The fluorescent particles are prepared from a raw material containing 4-methyl umbelliferone; The reinforcing agent is prepared from a raw material containing quercetin.

2. The corrosion warning coating according to claim 1, wherein The method for preparing the fluorescent particles comprises the following steps: S1: adding nano-silicon dioxide and 3-aminopropyl triethoxysilane into anhydrous ethanol, reacting, cooling, centrifuging to obtain a precipitate, washing, and drying to obtain NH2-nano-silicon dioxide particles; S2: adding 4-methyl umbelliferone, the NH2-nano-silicon dioxide particles obtained in step S1, and formaldehyde into anhydrous ethanol, reacting, cooling, centrifuging to obtain a precipitate, washing with anhydrous ethanol for three times, and drying to obtain fluorescent particles.

3. The corrosion warning coating according to claim 2, wherein In step S1, the mass ratio of nano-silicon dioxide to 3-aminopropyl triethoxysilane is (19-21):1, and the mass-volume ratio of nano-silicon dioxide to anhydrous ethanol is 1g:(3-5)mL.

4. The corrosion warning coating of claim 2, wherein, In step S2, the molar ratio of 4-methyl umbelliferone to formaldehyde is (0.9-1.1):1, the mass-volume ratio of NH2-nano-silicon dioxide to anhydrous ethanol is 1g:(3-5)mL, and the mass ratio of NH2-nano-silicon dioxide to 4-methyl umbelliferone is (19-21):

1.

5. The corrosion warning coating of claim 1, wherein, The method for preparing the reinforcing agent comprises the following steps: adding quercetin, formaldehyde, and polyethyleneimine into an ethanol aqueous solution, adjusting pH, reacting, and performing vacuum distillation to obtain the reinforcing agent.

6. The corrosion warning coating according to claim 5, characterized in that The molar ratio of quercetin to formaldehyde is (0.9-1.1):1, and the mass ratio of quercetin:polyethyleneimine:ethanol aqueous solution is (2-4):18:

50.

7. A corrosion warning coating characterized by, The method for preparing the corrosion-resistant early warning coating comprises the following steps: (1) applying the inner layer coating on a substrate and drying to form an inner coating layer; (2) applying the outer layer coating on the inner coating layer, drying, forming an outer coating layer, and curing at 50-85°C for 1-2 hours to obtain a corrosion-resistant early warning coating.

8. The corrosion warning coating according to claim 7, characterized in that The inner layer coating is applied at a dry weight of 0.2 to 0.5 g / cm 2 .

9. The corrosion warning coating of claim 7, wherein, The outer layer coating is applied at a dry weight of 0.3 to 0.6 g / cm 2 .

10. Application of the corrosion-resistant early warning coating according to any one of claims 1-6 in the field of VOCs environmental monitoring equipment.

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