Water-borne epoxy resin composite anticorrosive coating with MXene-NiO-PPy as filler and preparation method of water-borne epoxy resin composite anticorrosive coating

Abstract

The invention relates to the technical field of anticorrosive coatings, in particular to a waterborne epoxy resin composite anticorrosive coating with MXene-NiO-PPy as filler and a preparation method of the waterborne epoxy resin composite anticorrosive coating. The invention discloses a water-borne epoxy resin composite anticorrosive coating taking MXene-NiO-PPy as a filler. The water-borne epoxy resin composite anticorrosive coating is prepared from a water-borne epoxy resin emulsion, a modified amine adduct curing agent, MXene-NiO-PPy, a microencapsulated corrosion inhibitor, a dispersing and leveling aid, nano cellulose, nano silicon dioxide aerogel powder and deionized water. The waterborne epoxy resin composite anticorrosive coating with MXene-NiO-PPy as a filler is prepared by pre-dispersing slurry, microencapsulating and stirring at a low speed, has physical shielding property, active chemical passivation property, excellent mechanical toughness and good construction performance, and effectively solves the problems that the traditional waterborne epoxy coating is insufficient in shielding property, easy to crack and only passive in protection.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of anticorrosive coating, in particular to a water-based epoxy resin composite anticorrosive coating with MXene-NiO-PPy as filler and a preparation method thereof. BACKGROUND

[0002] In harsh environments such as marine, chemical, hot and humid, and high salt spray, metals and non-metals are exposed to moisture, oxygen, chloride ions, and sulfides for a long time. Corrosion media such as electrochemical corrosion, pitting corrosion, crevice corrosion, and stress corrosion cracking can easily occur, leading to degradation of material performance, structural instability, and even catastrophic failure. Anticorrosive coatings can significantly extend the service life of materials and significantly reduce maintenance and replacement costs caused by corrosion. At the same time, traditional toxic coatings containing chromium and lead are being phased out. In today's green and environmentally friendly environment, higher requirements for anticorrosive materials are long life, lightweight, and green environmental protection. Therefore, developing efficient, durable, and environmentally friendly new anticorrosive materials and technologies has become an urgent task to ensure the safe operation and sustainable development of major projects.

[0003] Water-based epoxy resin coatings have strong and tough paint films, full gloss, strong adhesion, and good water and corrosion resistance. They are widely used in high-grade wooden furniture and can also be used on metal surfaces. However, traditional water-based epoxy resin coatings have high porosity in spatial structure, poor crack propagation resistance, and oxygen, water, and chloride ions can easily diffuse through the voids to the metal-coating interface, reducing the barrier and adhesion properties of the coating.

[0004] To overcome the above problems, a multi-component composite filler and structural design are used to improve the comprehensive performance of water-based epoxy resin coatings. By adding MXene (such as Ti3C2T x ) as a two-dimensional transition metal carbide / nitride, the penetration path of corrosion media (such as water, Cl - ) can be extended, and the physical shielding performance of the coating can be improved. Adding polypyrrole (PPy) rich in imine groups can form a "redox" protective layer on the metal surface, preventing further penetration of corrosion media and being less likely to decompose in complex environments. It can also form a uniform film on the metal surface and tightly bond with the substrate. Adding nickel oxide (NiO) can form a stable passivation film in alkaline or neutral environments, further blocking the invasion of corrosion media. The combination of physical shielding of MXene, anodic protection of PPy, and passivation effect of NiO with the water-based epoxy resin matrix can form a multi-level protection mechanism and improve the mechanical properties and interfacial adhesion of the coating.

[0005] In the above background, a water-based epoxy resin composite anticorrosive coating with MXene-NiO-PPy as filler and a preparation method thereof are developed. Through the synergistic effect of multiple functional units, the protection bottleneck of traditional water-based epoxy resin coating in harsh environments is solved, and the overall improvement of long-term corrosion resistance, crack resistance and durability of the coating is realized. SUMMARY

[0006] In order to solve the problems of high porosity, poor crack propagation resistance, and difficult balance between environmental protection and durability of traditional water-based epoxy resin coating, the present application provides a water-based epoxy resin composite anticorrosive coating with MXene-NiO-PPy as filler and a preparation method thereof. Through the synergistic effect of multiple functional units, the protection bottleneck of traditional water-based epoxy resin coating in harsh environments is solved, and the overall improvement of long-term corrosion resistance, crack resistance and durability of the coating is realized.

[0007] In the first aspect, the present application provides a water-based epoxy resin composite anticorrosive coating with MXene-NiO-PPy as filler, which adopts the following technical scheme: A water-based epoxy resin composite anticorrosive coating with MXene-NiO-PPy as filler is prepared from the following raw materials by weight: Water-based epoxy resin emulsion: 100 parts; Modified amine addition product curing agent: 25-35 parts; MXene-NiO-PPy: 0.5-3 parts; Microencapsulated corrosion inhibitor: 1.5-3.0 parts; Dispersing leveling aid: 0.7-1.4 parts; Deionized water: 30-50 parts; The core material of the microencapsulated corrosion inhibitor is BTA, and the wall material is polyurethane; The dispersing leveling aid includes non-ionic wetting dispersant 0.4-0.8 parts and mineral oil defoaming agent 0.3-0.6 parts. By introducing MXene-NiO-PPy composite fillers and microencapsulated corrosion inhibitors, and optimizing the dispersion leveling aid system, the prepared waterborne epoxy resin composite anticorrosive coating realizes the synergistic effect of multiple anticorrosive mechanisms; the non-ionic wetting dispersant ensures that the nanofiller MXene-NiO-PPy and the microcapsule can be uniformly and stably dispersed in the water-based system, preventing agglomeration, so as to fully exert its functionality; the defoaming agent effectively eliminates the air bubbles introduced in the production and construction process, preventing defects such as pinholes in the paint film after curing; at the same time, the waterborne epoxy resin emulsion uses water as a diluent, and the VOC content is extremely low. Through the compounding of various fillers, the anticorrosive effect of traditional high-content heavy metal pigments (such as chromium and lead) can be achieved at a very low addition amount, while the environmental toxicity problem is avoided, meeting the green environmental protection regulations and development trend. The protective life of the coating is significantly prolonged, reducing the frequency and cost of maintenance and recoating.

[0008] Preferably, the MXene-NiO-PPy adopts the following technical scheme: S21 Synthesis of MXene: 2.0 parts of lithium fluoride is dissolved in 40 parts of hydrochloric acid with a concentration of 9 mol / L, and stirred at room temperature for 30 min to obtain a LiF / HCI mixture; 2.0 parts of aluminum titanium carbide powder is slowly added to the LiF / HCI mixture, and stirred at 35°C for 48 h; the reacted mixture is centrifuged to remove the supernatant to obtain a precipitate A; 3 times the volume of deionized water is added to the precipitate A, and ultrasonic treatment is performed at 500W for 10 min, followed by centrifugation to remove the supernatant; 3 times the volume of anhydrous ethanol is added to the precipitate A for intercalation, and ultrasonic treatment is performed at 500W for 60 min, followed by centrifugation to remove the supernatant; the ethanol intercalation step is repeated 2-5 times to ensure the separation of MXene, and the precipitate is collected to obtain MXene nanosheets; S22 Preparation of PPy-MXene composite material: 0.4 parts of MXene nanosheets from step S21 is first dispersed in 50 parts of water, and then added to a solution of 50 parts of anhydrous ethanol; 0.4 parts of pyrrole monomer is added, and an ice water bath and high-speed stirring are performed; then, the prepared FeCl3·6H2O aqueous solution is added dropwise, and the ice water bath is maintained for 24 hours to obtain a PPy-MXene mixture; the supernatant is removed by centrifugation at 7000 rpm for 8-10 min to obtain a PPy-MXene precipitate; the PPy-MXene precipitate is washed with anhydrous ethanol and deionized water in sequence for 2 times, and centrifuged at 7000 rpm for 10 min; the washed and centrifuged PPy-MXene precipitate is vacuum dried at 50°C for 12 hours to obtain a PPy-MXene composite material; Preparation of S23 NiO nanowires: 32 parts of ethylene glycol and 18 parts of deionized water were mixed, 0.47 parts of NiCl2·6H2O was added and dissolved, then 0.12 parts of sodium oxalate was added and mixed, and then transferred to a high-pressure reaction kettle, heated at 200°C for 24 hours, and then naturally cooled after heating treatment. The obtained product was centrifuged at 7000 rpm for 5-10 min to obtain precipitate B, anhydrous ethanol was added for alcohol washing, and the supernatant was removed by centrifugation at 7000 rpm for 5 min. This process was repeated twice. The washed precipitate B was vacuum dried at 60°C for 24h to obtain a NiO nanowire precursor. The NiO nanowire precursor was calcined in air at 400°C for 2 hours to obtain polycrystalline NiO nanowires. Preparation of S24 composite material MXene-NiO-PPy: The PPy-MXene composite material of step S22 was dispersed in 5 parts of deionized water, ultrasonically dispersed at 100W for 5min, and then 0.47 parts of NiO nanowires of step S23 was added and mixed by ultrasonic treatment at 100W for 50min, with the ultrasonic temperature controlled at no more than 40°C. The mixture was filtered and dried to obtain the composite material MXene-NiO-PPy.

[0009] Preferably, the FeCl3·6H2O aqueous solution is prepared by mixing 1.785 parts of FeCl3·6H2O oxidant into 10 parts of deionized water.

[0010] Preferably, the PPy-MXene composite material and the NiO nanowires are prepared in a mass ratio of (1.5-2):1.

[0011] By using the above scheme, in the composite material MXene-NiO-PPy, MXene as a two-dimensional transition metal carbon / nitride can extend the penetration path of the corrosion medium and improve the physical shielding performance of the coating; the addition of PPy rich in imine groups can form a "redox" protective layer on the metal surface to prevent the further penetration of the corrosion medium, and the PPy is not easy to decompose in complex environments, and can form a uniform film on the metal surface and tightly combine with the substrate; the addition of NiO nanowires can form a stable passivation film in alkaline or neutral environments to further block the invasion of the corrosion medium. The combination of the physical shielding of MXene, the anodic protection of PPy and the passivation effect of NiO with the waterborne epoxy resin matrix makes the waterborne epoxy resin coating upgrade from a simple physical barrier to an intelligent anti-corrosion system with physical shielding, active chemical passivation and enhanced mechanical properties, which is the most key technical innovation point to realize long service life and high reliability of the coating.

[0012] Preferably, the microencapsulated corrosion inhibitor is prepared by the following steps: dissolving 0.5-2 parts of water-soluble polymer emulsifier and 1-3 parts of emulsion stabilizer in 200-300 parts of deionized water to obtain an aqueous phase solution; dissolving 10-20 parts of core material BTA and 5-15 parts of PAPI in 20-40 parts of dimethylbenzene to obtain an oil phase solution; adding the oil phase solution to the aqueous phase solution, and emulsifying under high-speed shearing at 1500-2000 rpm for 15-20 minutes to form a stable oil / water emulsion; moving the emulsion system to a constant temperature water bath at 35±2℃, continuously stirring at 600-800 rpm, and slowly adding a chain extender aqueous solution through a dropping funnel at a rate of 1.0-2.0 mL / min to form microcapsules with polyurethane as the wall material and BTA wrapped therein; after the reaction, washing the microcapsules with deionized water and anhydrous ethanol alternately for 3-5 times, placing the obtained microcapsules in a vacuum drying oven at 50℃, drying for 24 hours, crushing to 200 mesh, and sieving to obtain the microencapsulated corrosion inhibitor powder.

[0013] Preferably, the water-soluble polymer emulsifier is any one of sodium dodecylbenzenesulfonate, polyvinylpyrrolidone, and gum arabic.

[0014] Preferably, the emulsion stabilizer is any one of polyvinyl alcohol, gelatin, and sodium carboxymethyl cellulose.

[0015] Preferably, the chain extender aqueous solution is obtained by mixing 2-4 parts of ethylenediamine with 10 parts of deionized water.

[0016] By using the above scheme, BTA (core material) is dissolved in a hydrophobic solvent and dispersed as an oil phase into an aqueous phase to form an oil / water emulsion. At this time, the oil phase already contains isocyanate monomers. When the ethylenediamine chain extender in the aqueous phase diffuses to the oil-water interface, it rapidly polymerizes with the isocyanate to form a dense polyurethane wall material at the oil droplet interface, which wraps the BTA solution inside, and finally obtains microcapsules. The microencapsulated corrosion inhibitor solves the problem of the persistence of active protection. When the coating is damaged and cracks occur, stress will cause the microcapsules to break, releasing BTA corrosion inhibitor molecules. BTA can quickly adsorb on the exposed metal surface to form a protective film, effectively inhibiting anode dissolution, and achieving intelligent self-repair. The polyurethane wall material is compatible with epoxy resin.

[0017] Preferably, the water-based epoxy resin composite anti-corrosion coating with MXene-NiO-PPy as the filler further comprises 0.3-1.0 parts of nanocellulose.

[0018] By the above scheme, the addition of nanocellulose effectively solves the problem of poor crack propagation resistance; nanocellulose has a very high aspect ratio and mechanical strength, can form a three-dimensional network structure in the resin matrix, effectively bridge and deflect microcracks, consume fracture energy, and greatly improve the toughness, impact resistance and anti-cracking of the coating.

[0019] Preferably, the water-based epoxy resin composite anticorrosive coating with MXene-NiO-PPy as filler further comprises a blocking agent and nanosilica aerogel powder: 0.5-2.0 parts.

[0020] By the above scheme, nanosilica aerogel powder solves the problem of high porosity. This material has a porous nanostructure and high specific surface area, can effectively adsorb and fix moisture and bubbles in the system during the initial curing of the resin, and its surface is modified by a silane coupling agent, which is rich in epoxy groups and can participate in the curing reaction, chemically bonded to the crosslinked network, permanently sealing the micro-pores left after curing, greatly improving the density of the coating.

[0021] By the above scheme, a multi-cooperative protection system of "physical shielding-fiber toughening-active repair-pore sealing" is constructed by using water-based epoxy resin emulsion, modified amine adduct curing agent, MXene-NiO-PPy, microencapsulated corrosion inhibitor, dispersing and leveling aids, deionized water, nanocellulose and nanosilica aerogel powder; by introducing nanofiber reinforcement, microencapsulated corrosion inhibitor and reactive pore sealing agent, and synergizing with MXene-NiO-PPy filler, a new generation of water-based anticorrosive coating is prepared, which not only has excellent shielding performance, but also has excellent mechanical properties, long-term self-repairing ability and extreme density.

[0022] In the second aspect, the application provides a preparation method of a water-based epoxy resin composite anticorrosive coating with MXene-NiO-PPy as filler, which adopts the following technical scheme: S1 Preparation of pre-dispersed slurry: MXene-NiO-PPy, nanocellulose, nanosilica aerogel powder, non-ionic wetting dispersant and deionized water are added to a high-speed disperser and continuously dispersed for 30-45 minutes until a uniform and stable slurry is formed; S2: After the slurry of step S1 is uniformly mixed with the water-based epoxy resin emulsion under low-speed stirring, the microencapsulated corrosion inhibitor is slowly added, and low-speed stirring is performed for 10-15 minutes; then mineral oil defoaming agent is added, low-speed stirring is performed for 3-5 minutes, and standing and defoaming is performed for 15 minutes; before construction, the modified amine adduct curing agent is added in proportion, low-speed stirring is performed for 5 minutes, and aging is performed for 10 minutes to obtain a water-based epoxy resin composite anticorrosive coating with MXene-NiO-PPy as filler; S3: Construction and curing: using high-pressure airless spraying equipment, the MXene-NiO-PPy filled waterborne epoxy resin composite anticorrosive coating is coated on the metal substrate after shot blasting and rust removal, the dry film thickness is controlled at 150-200 μm, and the curing time is 24 h.

[0023] Preferably, the low-speed stirring in step S2 is 300-500 rpm.

[0024] By the above scheme, the pre-dispersed slurry is first prepared, and then mixed with the resin, which ensures that the nano-filler with high surface energy can be fully dispersed and de-agglomerated in water first, and then introduced into the resin system, avoiding the agglomeration of the nano-filler and ensuring the stability of the final performance; low-speed stirring after adding microcapsules protects the microcapsule structure from being damaged during mixing, ensuring its repair function; standing and defoaming cooperates with the defoaming agent to completely eliminate bubbles and prevent pinholes in the paint film; aging allows the resin and curing agent to fully pre-react, ensuring the construction leveling property and the final film quality; high-pressure airless spraying: this construction method is efficient, the film thickness is uniform, and the coating is dense and bubble-free.

[0025] In summary, the present application has the following beneficial effects: The MXene-NiO-PPy filled waterborne epoxy resin composite anticorrosive coating prepared by the present application has the functions of physical shielding, active chemical passivation, excellent mechanical toughness, and good construction, effectively solves the technical problems of traditional waterborne epoxy coatings such as "insufficient shielding, easy cracking, and passive protection", and has great engineering application value and market prospect. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 Scanning electron microscope image of the MXene-NiO-PPy composite material prepared in Preparation Example 1; Figure 2 EDS layering image of the MXene-NiO-PPy composite material prepared in Preparation Example 1; Figure 3 X-ray diffraction pattern of the MXene-NiO-PPy composite material prepared in Preparation Example 1 (wherein the (111), (200), and (220) positions are characteristic peaks of NiO); Figure 4 Nyquist plot of the MXene-NiO-PPy filled waterborne epoxy resin composite anticorrosive coating prepared in Example 4 and Comparative Examples 11-13. DETAILED DESCRIPTION

[0027] The technical solutions of the present application are further illustrated below through specific embodiments, and the specific embodiments do not represent a limitation on the protection scope of the present application; some non-essential modifications and adjustments made by others according to the concept of the present application still belong to the protection scope of the present application.

[0028] The test methods shown in the following examples are all conventional methods unless otherwise specified. The reagents and materials shown are all commercially available products.

[0029] Aqueous epoxy resin emulsion: Anhui Xinyuan Technology Co., Ltd., Model: HY604-820; Modified amine adduct curing agent: Wuxi Arkema Technology Co., Ltd., Model: MA-2203ED; Non-ionic wet dispersant: BYK, Germany, Model: BYK-199, Item No. 21033545; Mineral oil defoamer: BYK, Germany, Model: BYK-024; Nanocellulose: Jinan Shengquan Group Co., Ltd., Model: NFC-33L2; Benzotriazole: Jinan Zhongbei Fine Chemical Co., Ltd., CAS: 95-14-7, Item No. 20210103, active substance ≥ 99.5%; Polymeric methylene polyphenyl polyisocyanate (abbreviation: PAPI): Zhongshan Dixin Chemical Co., Ltd., CAS: 9016-87-9, Content ≥ 99.8%; Ethylene diamine (abbreviation: EDA): Shanghai Gaoming Chemical Co., Ltd., CAS: 333-18-6, Model: 56434; Nanosilica aerogel powder: Jinshan County Jin Yuan Mining Processing Factory, Item No. 336; Sodium dodecylbenzenesulfonate (abbreviation: SDBS): Suzhou Dinghao Chemical Technology Co., Ltd., Item No. 0717056; Polyvinyl alcohol: Shandong Hongquan Chemical Technology Co., Ltd., Model: PVA-1799, Item No. 009.

[0030] The present application is further described in detail below in combination with examples and comparative examples.

[0031] Preparation Example Preparation of MXene-NiO-PPy S21 Synthesis of MXene: 2.0 kg of lithium fluoride was dissolved in 40 kg of hydrochloric acid with a concentration of 9 mol / L, stirred at room temperature for 30 min to obtain a LiF / HCI mixture; 2.0 kg of aluminum titanium carbide powder was slowly added to the LiF / HCI mixture, stirred at 35°C for 48 h, and the reacted mixture was centrifuged to remove the supernatant to obtain a precipitate A; 3 times the volume of deionized water was added to the precipitate A, and after 500W ultrasonic treatment for 10 min, the supernatant was removed by centrifugation; 3 times the volume of anhydrous ethanol was added to the precipitate A for intercalation, and after 500W ultrasonic treatment for 60 min, the supernatant was removed by centrifugation; the ethanol intercalation step was repeated 2-5 times to ensure the separation of MXene, and the precipitate was collected to obtain MXene nanosheets; S22 Preparation of PPy-MXene composite material: 0.4 kg of MXene nanosheets in step S21 was first dispersed in 50 parts of water, and then added to a solution of 50 parts of anhydrous ethanol, 0.4 kg of pyrrole monomer was added, and then FeCl3·6H2O aqueous solution prepared (containing 1.785 kg of FeCl3·6H2O) was added dropwise under the condition of ice water bath and high speed stirring, and the ice water bath was maintained for 24 hours to obtain a PPy-MXene mixture; the supernatant was removed by centrifugation at 7000 rpm for 8-10 min to obtain a PPy-MXene precipitate; the PPy-MXene precipitate was washed with anhydrous ethanol and deionized water in turn for 2 times, and centrifuged at 7000 rpm for 10 min; the washed and centrifuged PPy-MXene precipitate was vacuum dried at 50°C for 12 hours to obtain a PPy-MXene composite material; S23 Preparation of NiO nanowire: 32 kg of ethylene glycol and 18 kg of deionized water were mixed, and then 0.47 kg of NiCl2·6H2O was dissolved and added, followed by the addition of 0.12 kg of sodium oxalate; the mixture was transferred to a high-pressure reaction kettle and heated at 200°C for 24 hours; after heating treatment, the product was naturally cooled, centrifuged at 7000 rpm for 5-10 min to obtain a precipitate B, and then washed with anhydrous ethanol; the supernatant was removed by centrifugation at 7000 rpm for 5 min, and this process was repeated 2 times; the washed precipitate B was vacuum dried at 60°C for 24 h to obtain a NiO nanowire precursor; the NiO nanowire precursor was calcined in air at 400°C for 2 hours to obtain polycrystalline NiO nanowires; S24 Preparation of composite material MXene-NiO-PPy: 1.5 kg of PPy-MXene composite material in step S22 was dispersed in 5 parts of deionized water, ultrasonically dispersed at 100W for 5 min, and then 1.0 kg of NiO nanowires in step S23 was added and mixed by ultrasonic treatment at 100W for 50 min, with the ultrasonic temperature controlled to be not more than 40°C; the mixture was dried by suction filtration to obtain the composite material MXene-NiO-PPy.

[0032] Preferably, the FeCl3·6H2O aqueous solution is prepared by mixing 1.785 kg of FeCl3·6H2O oxidant into 10 kg of deionized water.

[0033] Preparation of MXene-NiO-PPy The difference from Preparation Example 1 is that the PPy-MXene composite and the NiO nanowire are added in a mass ratio of 2:1, and the specific addition amount is 2 kg of PPy-MXene composite and 1 kg of NiO nanowire.

[0034] Preparation of microencapsulated corrosion inhibitor 1.3 kg of sodium dodecyl benzene sulfonate and 2 kg of polyvinyl alcohol are dissolved in 250 kg of deionized water to obtain an aqueous phase solution; 15 kg of core material BTA and 10 kg of PAPI are dissolved in 30 kg of xylene to obtain an oil phase solution; the oil phase solution is added to the aqueous phase solution, and emulsification is carried out under high-speed shearing at 1800 rpm for 20 minutes to form a stable oil / water emulsion; the emulsion system is moved to a constant temperature water bath at 35°C, and continuously stirred at 700 rpm, and a chain extender aqueous solution is slowly added dropwise through a dropping funnel at a dropwise addition rate of 1.5 mL / min; after the reaction is completed, the microcapsules are washed with deionized water and anhydrous ethanol alternately for 4 times, and the obtained microcapsules are placed in a vacuum drying oven at 50°C and dried for 24 hours, and then crushed to 200 mesh and sieved to obtain the microencapsulated corrosion inhibitor powder.

[0035] The chain extender aqueous solution is 3 kg of ethylenediamine dissolved in 10 kg of deionized water.

[0036] Preparation of microencapsulated corrosion inhibitor The difference from Preparation Example 3 is that in the aqueous phase, 200 kg of deionized water, 1 kg of polyvinyl alcohol, and 0.5 kg of sodium dodecyl benzene sulfonate are added; and in the oil phase, 20 kg of xylene, 10 kg of BTA, and 5 kg of PAPI are added. The chain extender aqueous solution is 2 kg of ethylenediamine dissolved in 10 kg of deionized water; and the dropwise addition rate is 1.0 mL / min.

[0037] Preparation of microencapsulated corrosion inhibitor The difference from Preparation Example 3 is that in the aqueous phase, 300 kg of deionized water, 3 kg of polyvinyl alcohol, and 2 kg of sodium dodecyl benzene sulfonate are added; and in the oil phase, 40 kg of xylene, 20 kg of BTA, and 15 kg of PAPI are added. The chain extender aqueous solution is 4 kg of ethylenediamine dissolved in 10 kg of deionized water; and the dropwise addition rate is 2.0 mL / min. Example

[0038] Example 1 A preparation method of a water-based epoxy resin composite anticorrosive coating with MXene-NiO-PPy as filler, adopts the technical scheme as follows: S1 Preparation of pre-dispersed slurry: MXene-NiO-PPy, non-ionic wetting dispersant and deionized water are added into a high-speed disperser, and continuous dispersion is carried out for 40 minutes until a uniform and stable slurry is formed; S2: After the slurry of step S1 is uniformly mixed with the water-based epoxy resin emulsion under low-speed stirring, the microencapsulated corrosion inhibitor is slowly added, and low-speed stirring is carried out for 15 minutes; then the mineral oil defoaming agent is added, and low-speed stirring is carried out for 5 minutes, and standing and defoaming is carried out for 15 minutes; before construction, the curing agent is added in proportion, low-speed stirring is carried out for 5 minutes, and after aging for 10 minutes, the water-based epoxy resin composite anticorrosive coating with MXene-NiO-PPy as filler is obtained; S3: Construction and curing: the water-based epoxy resin composite anticorrosive coating with MXene-NiO-PPy as filler is coated on the metal substrate subjected to shot blasting derusting by using high-pressure airless spraying equipment, and the dry film thickness is controlled at 150 μm, and curing is carried out for 24 h.

[0039] Table 1 Composition and amount (kg) of the water-based epoxy resin composite anticorrosive coating in examples 1-6 The MXene-NiO-PPy is prepared according to the scheme of Preparation Example 1; and the microencapsulated corrosion inhibitor is prepared according to the method of Preparation Example 3.

[0040] The metal substrate is test-grade tinplate, the surface quality is grade I, the hardness grade is T52, and the model is BGD2301; the size (mm) of each piece is: length x width x thickness = 100 x 50 x 0.28 mm 3 . The four iron pieces are longitudinally unidirectionally polished with 600-grit sandpaper, transversely unidirectionally polished with 800-grit sandpaper, sprayed with alcohol, and wiped.

[0041] Example 2 A preparation method of a water-based epoxy resin composite anticorrosive coating with MXene-NiO-PPy as filler, which is different from example 1 in that in the preparation method: S1 Preparation of pre-dispersed slurry: continuous dispersion is carried out for 30 minutes; S2: The microencapsulated corrosion inhibitor is slowly added, and low-speed stirring is carried out for 10 minutes; then the mineral oil defoaming agent is added, and low-speed stirring is carried out for 3 minutes; S3: The water-based epoxy resin composite anticorrosive coating with MXene-NiO-PPy as filler is coated on the metal substrate subjected to shot blasting derusting, and the dry film thickness is controlled at 200 μm, and curing is carried out for 24 h.

[0042] The component dosage of the water-based epoxy resin composite anticorrosive coating is shown in Table 1.

[0043] The MXene-NiO-PPy is prepared according to the scheme of Preparation Example 2; and the microencapsulated corrosion inhibitor is prepared according to the method of Preparation Example 4.

[0044] Example 3 A preparation method of a water-based epoxy resin composite anticorrosive coating with MXene-NiO-PPy as filler, which is different from Example 1 in that: The component dosage of the water-based epoxy resin composite anticorrosive coating is shown in Table 1.

[0045] The MXene-NiO-PPy is prepared according to the scheme of Preparation Example 1; and the microencapsulated corrosion inhibitor is prepared according to the method of Preparation Example 5.

[0046] Examples 4-6 A preparation method of a water-based epoxy resin composite anticorrosive coating with MXene-NiO-PPy as filler, which is different from Example 1 in that: the component dosage of the water-based epoxy resin composite anticorrosive coating is shown in Table 1.

[0047] Comparative Example Comparative Example 1 Different from Example 4, the MXene-NiO-PPy composite filler, the microencapsulated corrosion inhibitor, the nanocellulose and the nanosilica aerogel powder are not added in the composite coating.

[0048] Comparative Example 2 Different from Example 4, the MXene-NiO-PPy composite filler is not added in the composite coating.

[0049] Comparative Example 3 Different from Example 4, the microencapsulated corrosion inhibitor is not added in the composite coating.

[0050] Comparative Example 4 Different from Example 4, the nanocellulose is not added in the composite coating.

[0051] Comparative Example 5 Different from Example 4, the nanosilica aerogel powder is not added in the composite coating.

[0052] Comparative Example 6 Different from Example 4, the same amount of graphene is used to replace the MXene-NiO-PPy composite filler in the composite coating.

[0053] Comparative Example 7 The difference from Example 4 is that an equal amount of polypyrrole (PPy) is used instead of MXene-NiO-PPy composite filler in the composite coating.

[0054] Comparative Example 8 The difference from Example 4 is that an equal amount of NiO nanowires are used in the composite coating to replace the MXene-NiO-PPy composite filler.

[0055] Comparative Example 9 The difference from Example 4 is that the MXene, NiO, and PPy added to the composite coating are a physical mixture of the three fillers, rather than a pre-prepared MXene-NiO-PPy composite filler.

[0056] Comparative Example 10 The difference from Example 4 is that the amount of MXene-NiO-PPy composite filler added in the composite coating is 5 kg.

[0057] Comparative Examples 11-13 The difference from Example 4 is that the amount of PPy-MXene composite material and NiO nanowires added is different, as shown in Table 2.

[0058] Table 2. Addition amounts of PPy-MXene composite material and NiO nanowires Performance testing 1. Neutral salt spray resistance test: Prepare a coating on tinplate according to the standard GB / T 1771-2007, draw cross lines, and test for 3000 hours.

[0059] 2. Adhesion: The adhesion was tested by pull-off method according to the standard GB / T 5210-2006.

[0060] 3. Impact resistance: According to the standard GB / T 1732-1993, with a forward impact height of 50cm, assess whether the coating cracks or peels off.

[0061] 4. Scratch self-healing ability (rating): Prepare a tinplate sample with scratches, and after 500 hours of salt spray testing, observe the width of corrosion products at the scratches under a microscope and rate it (1-5, with 1 being the worst and 5 being the best).

[0062] 5. Electrochemical impedance spectroscopy (EIS): Tested in 3.5% NaCl solution, and the results were recorded after 10 days of immersion.

[0063] The waterborne epoxy resin composite anti-corrosion coatings prepared by the methods of Examples 1-6 and Comparative Examples 1-10 were subjected to the above performance tests, and the test results are shown in Table 3.

[0064] Table 3 Performance test results The MXene-NiO-PPy composite material obtained by Preparation Example 1 was combined with PPy and MXene together by an in-situ polymerization method, and then MXene-PPy and NiO were mixed by an ultrasonic mixing method. The detection by an energy spectrometer and a scanning electron microscope showed that PPy was closely combined with flaky MXene, and NiO was uniformly dispersed between the layers. Figure 1 and Figure 2

[0065] The MXene-NiO-PPy composite material obtained by Preparation Example 1 was combined with PPy and MXene together by an in-situ polymerization method, and then MXene-PPy and NiO were mixed by an ultrasonic mixing method. The detection by an energy spectrometer and a scanning electron microscope showed that PPy was closely combined with flaky MXene, and NiO was uniformly dispersed between the layers. Figure 3 As shown in the X-ray diffraction pattern obtained from the X-ray diffractometer, it can be seen from the figure that there is a wide and strong peak package between 20°-30°, which is the amorphous characteristic of PPy; the (002) characteristic peak of MXene usually appears at 5°-9°, but is covered due to left shift of the peak value; the characteristic peaks of NiO appear at 37.2°, 43.1° and 62.8°, respectively corresponding to its (111), (200) and (220) crystal faces, which is the typical cubic crystal structure of NiO. The above results show that MXene, PDA and NiO are successfully combined; in addition, the intensity of the wide peak of PPy is reduced in the pattern of the composite material, and a weak diffraction signal appears near 25°, which is due to the fact that MXene and NiO provide dispersion support for PPy, inhibit its agglomeration behavior, and thus partially improve the molecular arrangement of PPy; at the same time, the (200) crystal face peak of NiO is slightly broadened, indicating that the grain size of NiO is reduced during the compounding process; these further indicate that the introduction of MXene improves the microstructure uniformity of the MXene-NiO-PPy composite material to some extent.

[0066] As can be seen from the performance test results in Table 3, in Examples 1-6, the waterborne epoxy resin composite anticorrosive coating prepared in Examples 4-6 with MXene-NiO-PPy as the filler shows relatively optimal comprehensive performance, MXene-NiO-PPy provides top-level shielding and active corrosion protection, nanocellulose endows extremely high adhesion and flexibility, and nano-silica aerogel powder ensures the denseness of the paint film, and microcapsules provide perfect self-repairing ability.

[0067] The Nyquist plots of the waterborne epoxy resin composite anticorrosive coatings prepared in Example 4 and Comparative Examples 11-13 were obtained by electrochemical impedance spectroscopy test. Figure 4 ​As shown, the diameter of the semicircle in the high-frequency region reflects the rate of charge transfer in the coating, the larger the diameter of the semicircle, the slower the charge transfer rate, the better the corrosion resistance; after ten days of immersion, the corrosion potential of the composite coating is always greater than that of the pure waterborne epoxy resin coating, indicating that the addition of MXene-NiO-PPy, microencapsulated corrosion inhibitor and other functional materials makes the corrosion rate of the tinplate smaller; among them, example 4, MXene-NiO-PPy prepared by PPy-MXene composite material and NiO nanowire with a mass ratio of 1.5:1 1.5 The coating WEP obtained has the largest diameter of the semicircle, and the corrosion resistance of the coating is optimal.

[0068] Comparative example 1 has no other functional fillers compared with example 4, only waterborne epoxy resin emulsion, curing agent and dispersing leveling agent: the performance is overall sharply deteriorated, proving that all functional fillers are crucial to the improvement of the basic performance.

[0069] Comparative example 2 has no MXene-NiO-PPy addition compared with example 4, and the corrosion resistance is severely decreased, proving that MXene-NiO-PPy is the core to provide corrosion resistance.

[0070] Comparative example 3 has no microencapsulated corrosion inhibitor compared with example 4, and the mechanical properties are good, but there is no repair ability at the scratch, and the scratch corrosion is serious after salt spray, proving that the microencapsulated corrosion inhibitor provides the function of “damage emergency repair” for the waterborne epoxy resin composite corrosion resistant coating.

[0071] Comparative example 4 has no nanocellulose addition compared with example 4, and the adhesion, flexibility and impact resistance are obviously decreased, proving that the nanocellulose mainly contributes to mechanical enhancement to prevent the coating from cracking.

[0072] Comparative example 5 has no nanosilica aerogel powder addition compared with example 4, and the performance is significantly lower than that of example 4, proving that the aerogel greatly improves the shielding property of the coating by closing the pores.

[0073] Comparative example 6 uses an equal amount of graphene instead of MXene-NiO-PPy composite filler compared with example 4, and the performance is inferior to that of example 4, proving that the synergistic corrosion prevention effect of MXene-NiO-PPy composite filler is better than that of single graphene physical shielding.

[0074] Comparative examples 7-8 use single component polypyrrole or NiO nanowire instead of MXene-NiO-PPy composite filler compared with example 4, and the performance is far worse than that of example 4, proving that the synergistic effect of MXene, NiO and PPy ternary composite, physical shielding and chemical passivation is much better than any single component.

[0075] Compared with Example 4, the MXene-NiO-PPy in Comparative Example 9 is physically mixed, and the performance is obviously lower than that of Example 4, which proves that the "composite" structure of MXene-NiO-PPy (rather than simple physical mixing) is crucial for forming a high-efficiency synergistic network.

[0076] Compared with Example 4, the MXene-NiO-PPy filler in Comparative Example 10 is excessive, and the mechanical properties (adhesion, impact resistance, and flexibility) are significantly deteriorated, which proves that there is an optimal amount of filler, and an excessive amount will cause the continuity of the resin matrix to be destroyed and the performance to be reduced.

[0077] From the above test results, it can be seen that the waterborne epoxy resin composite anticorrosive coating prepared by using MXene-NiO-PPy as the filler has the functions of extreme physical shielding, active chemical passivation, excellent mechanical toughness, and good workability, effectively solves the technical problems of insufficient shielding, easy cracking, and passive protection of traditional waterborne epoxy coatings, and has great engineering application value and market prospect.

[0078] The specific embodiments are merely an explanation of the present application, and are not a limitation of the present application. Those skilled in the art can make modifications to the embodiments without creative contribution after reading the specification, as long as the modifications are within the scope of the present application and are protected by the patent law.

Claims

1. An aqueous epoxy resin composite anticorrosive coating with MXene-NiO-PPy as filler, characterized in that, The following raw materials are prepared by weight parts: Water-based epoxy resin emulsion: 100 parts; Modified amine addition product curing agent: 25-35 parts; MXene-NiO-PPy: 0.5-3 parts; Microencapsulated corrosion inhibitor: 1.5-3.0 parts; Dispersing leveling aid: 0.7-1.4 parts; Deionized water: 30-50 parts; The core material of the microencapsulated corrosion inhibitor is BTA, and the wall material is polyurethane; The dispersing leveling aid includes non-ionic wet dispersing agent 0.4-0.8 parts and mineral oil defoaming agent 0.3-0.6 parts. The water-based epoxy resin composite anticorrosive coating filled with MXene-NiO-PPy according to claim 1, wherein the MXene-NiO-PPy adopts the following technical solutions: S21 Synthesis of MXene: 2.0 parts of lithium fluoride are dissolved in 40 parts of hydrochloric acid with a concentration of 9 mol / L, stirred at room temperature for 30 min to obtain a LiF / HCI mixture; 2.0 parts of aluminum titanium carbide powder are slowly added to the LiF / HCI mixture, stirred at 35 ℃ for 48 h, the reacted mixture is centrifuged to remove the supernatant to obtain precipitate A, 3 times the volume of deionized water is added to the precipitate A, and after 500 W ultrasonic treatment for 10 min, the supernatant is removed by centrifugation, then 3 times the volume of anhydrous ethanol is added to the precipitate A for intercalation, and after 500 W ultrasonic treatment for 60 min, the supernatant is removed by centrifugation, and the ethanol intercalation step is repeated 2-5 times to ensure the separation of MXene, and the precipitate is collected to obtain MXene nanosheets; S22 Preparation of PPy-MXene composite material: 0.4 parts of MXene nanosheets in step S21 are first dispersed in 50 parts of water, then added to a solution of 50 parts of anhydrous ethanol, 0.4 parts of pyrrole monomer is added, and then FeCl3·6H2O aqueous solution is added dropwise under the condition of ice water bath and high speed stirring, and the reaction is maintained for 24 hours, to obtain a PPy-MXene mixture, the supernatant is removed by centrifugation at 7000 rpm for 8-10 min, to obtain PPy-MXene precipitate, which is washed with anhydrous ethanol and deionized water for 2 times respectively, and then centrifuged at 7000 rpm for 10 min, and the washed and centrifuged PPy-MXene precipitate is vacuum dried at 50 ℃ for 12 hours to obtain PPy-MXene composite material; S23 Preparation of NiO nanowires: 32 parts of ethylene glycol and 18 parts of deionized water were mixed, 0.47 parts of NiCl2·6H2O was dissolved and then 0.12 parts of sodium oxalate was added, and then transferred to a high-pressure reaction kettle, heated at 200℃ for 24 hours, and then naturally cooled after heating treatment. The obtained product was centrifuged at 7000 rpm for 5-10 min to obtain precipitate B, and then washed with anhydrous ethanol, centrifuged at 7000 rpm for 5 min to remove the supernatant, and the process was repeated 2 times. The washed precipitate B was vacuum dried at 60℃ for 24 h to obtain a NiO nanowire precursor. The NiO nanowire precursor was calcined in air at 400℃ for 2 hours to obtain polycrystalline NiO nanowires. S24 Preparation of composite material MXene-NiO-PPy: The PPy-MXene composite material of step S22 was dispersed in 5 parts of deionized water, ultrasonically dispersed at 100W for 5min, and then 0.47 parts of NiO nanowires of step S23 was added and ultrasonically treated at 100W for 50min, and the ultrasonic temperature was controlled to be not more than 40℃. The mixture was filtered and dried to obtain the composite material MXene-NiO-PPy.

2. The aqueous epoxy resin composite anticorrosive coating with MXene-NiO-PPy as filler according to claim 2, characterized in that, The mass ratio of the PPy-MXene composite material and the NiO nanowires is (1.5-2):

1.

3. The aqueous epoxy resin composite anticorrosive coating with MXene-NiO-PPy as filler according to claim 1, characterized in that, The microencapsulated corrosion inhibitor is prepared by the following steps: 0.5-2 parts of a water-soluble polymer emulsifier and 1-3 parts of an emulsion stabilizer are dissolved in 200-300 parts of deionized water to obtain an aqueous solution; 10-20 parts of core material BTA and 5-15 parts of PAPI are dissolved in 20-40 parts of xylene to obtain an oil phase solution; the oil phase solution is added to the aqueous solution, and emulsified under high-speed shearing at 1500-2000 rpm for 15-20 minutes to form a stable oil / water emulsion; the emulsion system is moved to a constant-temperature water bath at 35±2℃, and continuously stirred at 600-800 rpm, and a chain extender aqueous solution is slowly added dropwise through a dropping funnel at a dropwise adding rate of 1.0-2.0 mL / min to form microcapsules with polyurethane as a wall material and BTA wrapped therein; after the reaction is completed, the microcapsules are washed with deionized water and anhydrous ethanol alternately for 3-5 times, the obtained microcapsules are placed in a vacuum drying oven at 50℃ for drying for 24 hours, and are crushed to 200 mesh for sieving to obtain the microencapsulated corrosion inhibitor powder.

4. The aqueous epoxy resin composite anticorrosive coating with MXene-NiO-PPy as filler according to claim 4, characterized in that, The water-soluble polymer emulsifier is any one of sodium dodecyl benzene sulfonate, polyvinylpyrrolidone and gum arabic.

5. The aqueous epoxy resin composite anticorrosive coating with MXene-NiO-PPy as filler according to claim 4, characterized in that, The emulsion stabilizer is any one of polyvinyl alcohol, gelatin and sodium carboxymethyl cellulose.

6. The aqueous epoxy resin composite anticorrosive coating with MXene-NiO-PPy as filler according to claim 1, characterized in that, It further includes 0.3-1.0 parts of nanocellulose.

7. The aqueous epoxy resin composite anticorrosive coating with MXene-NiO-PPy as filler according to claim 1, characterized in that, It further includes a sealing agent, nanosilica aerogel powder: 0.5-2.0 parts.

8. A method for preparing the waterborne epoxy resin composite anticorrosive coating with MXene-NiO-PPy as filler according to any one of claims 1-8, characterized in that, It includes the following steps: S1 Preparation of pre-dispersed slurry: MXene-NiO-PPy, nanocellulose, nanosilica aerogel powder, non-ionic wetting dispersant and deionized water are added to a high-speed disperser and continuously dispersed for 30-45 minutes until a uniform and stable slurry is formed; S2: After mixing the slurry of step S1 with the aqueous epoxy resin emulsion under low-speed stirring, slowly add the microencapsulated corrosion inhibitor, low-speed stirring for 10-15 minutes; then add mineral oil defoaming agent, low-speed stirring for 3-5 minutes, standing for 15 minutes; before construction, add modified amine adduct curing agent in proportion, low-speed stirring for 5 minutes, aging for 10 minutes, then obtain the MXene-NiO-PPy as filler water-based epoxy resin composite anticorrosive coating; S3: Construction and curing: using high-pressure airless spraying equipment, MXene-NiO-PPy as filler water-based epoxy resin composite anticorrosive coating is coated on the metal substrate after shot blasting derusting, control the dry film thickness at 150-200μm, curing for 24h.

9. The method for preparing the waterborne epoxy resin composite anticorrosive coating with MXene-NiO-PPy as filler according to claim 9, characterized in that: The low-speed stirring in step S2 is 300-500rpm.

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