Preparation method and application method of corrosion inhibitor intercalation LDH / MoS2 synergistically enhanced corrosion-resistant polyurea coating

Abstract

The invention relates to a preparation method and an application method of a corrosion inhibitor intercalated LDH / MoS2 synergistically enhanced corrosion-resistant polyurea coating. The preparation method comprises the following steps: preparing corrosion inhibitor intercalated LDH by adopting a hydrothermal method; preparing a corrosion inhibitor intercalation LDH / MoS2 heterostructure by combining a hydrothermal method with an in-situ growth mode; preparing a polyurea matrix; and mixing the corrosion inhibitor intercalation LDH / MoS2 heterostructure into the polyurea matrix, and carrying out dispersing and defoaming treatment on the corrosion inhibitor intercalation LDH / MoS2 heterostructure. According to the preparation method, a corrosion inhibitor intercalation LDH / MoS2 heterostructure composite filler is constructed in situ in a polyurea matrix, efficient synergy of an active protection mechanism and a passive physical barrier is achieved, high compatibility of a filler system and the polyurea matrix is ensured, and finally the polyurea composite coating with excellent long-acting corrosion resistance and excellent comprehensive performance is obtained. And the long-acting protection requirement in an extremely severe environment is met.

Description

Technical Field

[0001] The present invention relates to the technical field of corrosion-resistant coatings, and in particular to a preparation method and an application method of a corrosion-resistant polyurea coating synergistically enhanced by a corrosion inhibitor intercalated LDH / MoS2. Background Art

[0002] Anti-corrosion coatings are widely used in the corrosion protection of engineering structures and equipment in marine environments such as ships, lighthouses, offshore wind power, and submarine pipelines. The anti-corrosion effect of existing anti-corrosion materials is still insufficient and cannot meet the long-term protection needs in extremely harsh environments. Summary of the Invention

[0003] Some embodiments of the present invention provide a method for preparing a corrosion-resistant polyurea coating synergistically enhanced by intercalating LDH / MoS2 as a corrosion inhibitor, the preparation method comprising the following steps:

[0004] The corrosion inhibitor intercalated LDH was prepared by hydrothermal method;

[0005] The corrosion inhibitor intercalated LDH / MoS2 heterostructure was prepared by a hydrothermal method combined with in situ growth;

[0006] preparing a polyurea matrix; and

[0007] The corrosion inhibitor intercalated LDH / MoS2 heterostructure is mixed into the polyurea matrix and subjected to dispersion and defoaming treatment.

[0008] In some embodiments, the preparation of the corrosion inhibitor intercalated LDH by a hydrothermal method comprises the following steps:

[0009] preparing a first mixed solution of magnesium nitrate hexahydrate, aluminum nitrate nonahydrate, and a corrosion inhibitor;

[0010] placing the first mixed solution into a reactor for hydrothermal reaction to obtain a first reactant;

[0011] The first reactant is washed and centrifuged to obtain a first precipitate, which is then dried.

[0012] In some embodiments, the preparation of a first mixed solution of magnesium nitrate hexahydrate, aluminum nitrate nonahydrate, and a corrosion inhibitor comprises the following steps:

[0013] Mixing magnesium nitrate hexahydrate, aluminum nitrate nonahydrate and a corrosion inhibitor, dissolving them in deionized water and stirring them evenly to obtain an initial mixed solution;

[0014] Dissolve sodium hydroxide in deionized water to prepare a sodium hydroxide alkaline solution;

[0015] The sodium hydroxide alkaline solution is dropped into the initial mixed solution until the pH value of the initial mixed solution reaches 11.

[0016] In some embodiments, the molar ratio of magnesium nitrate hexahydrate to aluminum nitrate nonahydrate and the corrosion inhibitor is 3:1:3.

[0017] In some embodiments, the preparation of the corrosion inhibitor intercalated LDH / MoS2 heterostructure by a hydrothermal method combined with an in-situ growth method comprises the following steps:

[0018] preparing a second mixed solution of ammonium molybdate tetrahydrate, thiourea and corrosion inhibitor intercalated LDH;

[0019] placing the second mixed solution into a reactor for hydrothermal in-situ growth to obtain a second reactant;

[0020] The second reactant is washed and centrifuged to obtain a second precipitate, which is then dried.

[0021] In some embodiments, the mass ratio of ammonium molybdate tetrahydrate, thiourea, and corrosion inhibitor intercalated LDH is 1:3:1.

[0022] In some embodiments, the preparation of the polyurea matrix comprises the following steps:

[0023] Preparation of semi-prepolymer;

[0024] preparing a chain extender; and

[0025] The semi-prepolymer and the chain extender are mixed and stirred according to a predetermined ratio.

[0026] In some embodiments, mixing the corrosion inhibitor intercalated LDH / MoS2 heterostructure into the polyurea matrix and performing a dispersion and defoaming treatment comprises the following steps:

[0027] mixing the corrosion inhibitor intercalated LDH / MoS2 heterostructure into the polyurea matrix;

[0028] Ultrasonic vibration was used to perform dispersion and defoaming treatment on the polyurea matrix with corrosion inhibitor intercalated LDH / MoS2 heterostructure.

[0029] In some embodiments, the mass ratio of the corrosion inhibitor intercalated LDH / MoS2 heterostructure to the polyurea matrix is ​​1:50.

[0030] Some embodiments of the present invention provide an application method of a corrosion inhibitor intercalated LDH / MoS2 synergistically enhanced corrosion-resistant polyurea coating, wherein the corrosion inhibitor intercalated LDH / MoS2 synergistically enhanced corrosion-resistant polyurea coating is prepared using the preparation method described in the aforementioned embodiment, and the application method comprises the following steps:

[0031] Applying the corrosion inhibitor intercalated LDH / MoS2 synergistically enhanced corrosion-resistant polyurea coating to the surface to be protected from corrosion; and

[0032] The drying and curing operation is performed in a predetermined temperature environment.

[0033] Compared with the related art, the above solution of the embodiment of the present invention has at least the following beneficial effects:

[0034] The preparation method provided by the present invention constructs a corrosion inhibitor-intercalated LDH / MoS2 heterogeneous structure composite filler in situ within a polyurea matrix, achieving efficient synergy between the active protection mechanism and the passive physical barrier, and ensuring that the filler system is highly compatible with the polyurea matrix, ultimately obtaining a polyurea composite coating with both excellent long-term corrosion resistance and excellent comprehensive performance to meet the long-term protection needs in extremely harsh environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 A flow chart showing a method for preparing a corrosion-resistant polyurea coating synergistically enhanced by intercalating LDH / MoS2 as a corrosion inhibitor, provided in some embodiments of the present invention;

[0036] Figure 2 for Figure 1 Specific flow chart of step S100;

[0037] Figure 3 for Figure 2 Specific flow chart of step S110;

[0038] Figure 4 for Figure 1 Specific flow chart of step S200;

[0039] Figure 5 for Figure 1 Specific flow chart of step S300;

[0040] Figure 6 for Figure 1 Specific flow chart of step S400;

[0041] Figure 7 A flow chart showing an application method of the corrosion inhibitor intercalated LDH / MoS2 synergistically enhanced corrosion-resistant polyurea coating provided by some embodiments of the present invention is shown. DETAILED DESCRIPTION

[0042] To make the objectives, technical solutions, and advantages of the present invention more apparent, the present invention will be further described in detail below with reference to the accompanying drawings. It is apparent that the embodiments described are only some, not all, of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are intended to fall within the scope of protection of the present invention.

[0043] In related technologies, polyurea coatings (PUA) are produced in situ through the high-speed reaction of diisocyanates and polyamines. Their unique microphase-separated structure (flexible soft segments provide elasticity, while rigid hard segments are physically crosslinked via urea bonds and a strong hydrogen-bonding network) imparts excellent mechanical strength, outstanding chemical resistance, wear resistance, and weathering resistance. Their customizable molecular structure (by adjusting the –NCO / –NH2 equivalent ratio) and solvent-free application make them highly valuable in heavy-duty corrosion protection projects, such as offshore steel structures, chemical storage tank linings, and underground pipeline protection.

[0044] Traditional polyurea coatings still face fundamental challenges in long-term, harsh corrosive environments: the free volume and inherent defects of the molecular chains at the microscopic level allow corrosive media, particularly small molecules of water, oxygen, and chloride ions, to penetrate slowly. Once these media reach the coating / metal interface, they trigger electrochemical corrosion, leading to coating failure and substrate damage.

[0045] In the technical path of improving the long-term corrosion resistance of metal protective coatings, introducing functional fillers into the polymer matrix is ​​a key strategy.

[0046] Corrosion inhibitors, such as 2-mercaptobenzimidazole (MBI), can actively inhibit the corrosion reaction of metal substrates through chemical adsorption or film formation mechanisms. Layered double hydroxides (LDH) are a general term for hydrotalcite (HT) and hydrotalcite-like compounds (HTLCs). With their unique interlayer anion exchange capacity, they are often used as ideal carriers for corrosion inhibitors to achieve controlled release. Their layered structure also provides a certain physical barrier effect. Molybdenum disulfide (MoS2), as a typical two-dimensional nanosheet, can effectively delay the absorption of water, oxygen and corrosive ions such as Cl due to its excellent chemical stability, high specific surface area and significant "maze effect". - , the penetration and diffusion.

[0047] However, there are obvious limitations in introducing these components individually or through simple physical blending: direct addition of corrosion inhibitors can easily lead to initial burst release and insufficient protection in the later stage; when LDH is used as a carrier, its physical barrier efficiency is limited by inherent interlayer spacing and dispersion problems; although MoS2 has excellent passive barrier properties, it lacks active corrosion inhibition function; and due to weak interface bonding and poor synergistic effects between different components, it is difficult to fully utilize the combined advantages of "active intelligent slow release" and "efficient physical barrier".

[0048] In order to overcome these limitations, the present invention provides a method for preparing a corrosion inhibitor intercalated LDH / MoS2 synergistically enhanced corrosion-resistant polyurea coating, the preparation method comprising the following steps: preparing a corrosion inhibitor intercalated LDH by a hydrothermal method; preparing a corrosion inhibitor intercalated LDH / MoS2 heterostructure by a hydrothermal method combined with an in-situ growth method; preparing a polyurea matrix; and mixing the corrosion inhibitor intercalated LDH / MoS2 heterostructure into the polyurea matrix and performing a dispersion and defoaming treatment.

[0049] The preparation method provided by the present invention constructs a corrosion inhibitor-intercalated LDH / MoS2 heterogeneous structure composite filler in situ within a polyurea matrix, achieving efficient synergy between the active protection mechanism and the passive physical barrier, and ensuring that the filler system is highly compatible with the polyurea matrix, ultimately obtaining a polyurea composite coating with both excellent long-term corrosion resistance and excellent comprehensive performance to meet the long-term protection needs in extremely harsh environments.

[0050] The optional embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0051] Figure 1 The flowchart of the preparation method of the corrosion inhibitor intercalated LDH / MoS2 synergistically enhanced corrosion resistant polyurea coating provided by some embodiments of the present invention is shown. Some embodiments of the present invention provide a method for preparing the corrosion inhibitor intercalated LDH / MoS2 synergistically enhanced corrosion resistant polyurea coating, such as Figure 1 As shown, the preparation method comprises the following steps:

[0052] S100: Preparation of corrosion inhibitor intercalated LDH by hydrothermal method;

[0053] S200: The corrosion inhibitor intercalated LDH / MoS2 heterostructure was prepared by a hydrothermal method combined with in situ growth;

[0054] S300: preparing a polyurea matrix;

[0055] S400: mixing the corrosion inhibitor intercalated LDH / MoS2 heterostructure into the polyurea matrix and performing a dispersion and defoaming treatment.

[0056] The corrosion inhibitor intercalated LDH / MoS2 synergistically reinforced corrosion resistant polyurea coating prepared by the above preparation method can achieve long-term, intelligent synergistic protection against penetration of corrosive media, while taking into account excellent mechanical properties and construction applicability. Its working mechanism is as follows: the corrosion inhibitor intercalated LDH / MoS2 heterostructure is constructed by in-situ growth, and the corrosion inhibitor response Cl loaded between the corrosion inhibitor intercalated LDH layers is utilized. -Ions trigger controlled release to form an active protective film at the metal interface; at the same time, the dense physical barrier formed by the interlaced MoS2 and LDH layers significantly extends the medium penetration path; in addition, the filler surface groups (–OH / S) form strong interfacial bonds with the polyurea urea bonds. The above-mentioned active corrosion inhibition, physical barrier, and interface strengthening work synergistically to construct a multi-level dynamic protection network, so that the coating can obtain excellent corrosion resistance, high mechanical strength and good performance at the same time.

[0057] Figure 2 for Figure 1 In the specific flow chart of step S100, in some embodiments, as Figure 2 As shown, step S100: preparing the corrosion inhibitor intercalated LDH by hydrothermal method includes the following steps:

[0058] S110: preparing a first mixed solution of magnesium nitrate hexahydrate, aluminum nitrate nonahydrate, and a corrosion inhibitor;

[0059] S120: placing the first mixed solution into a reactor for hydrothermal reaction to obtain a first reactant;

[0060] S130: washing and centrifuging the first reactant to obtain a first precipitate, and drying the precipitate.

[0061] Corrosion inhibitor response to LDH interlayer loading - Ions trigger controlled release to form an active protective film at the metal interface, and the corrosion inhibitor is, for example, at least one of 2-mercaptobenzimidazole (MBI) and 2-mercaptobenzothiazole (MBT).

[0062] Figure 3 for Figure 2 In the specific flow chart of step S110, in some embodiments, as Figure 3 As shown, step S110: preparing a first mixed solution of magnesium nitrate hexahydrate, aluminum nitrate nonahydrate and a corrosion inhibitor includes the following steps:

[0063] S111: dissolving magnesium nitrate hexahydrate, aluminum nitrate nonahydrate, and a corrosion inhibitor in deionized water and stirring to obtain an initial mixed solution;

[0064] S112: dissolving sodium hydroxide in deionized water to prepare a sodium hydroxide alkaline solution;

[0065] S113: Dropping the sodium hydroxide alkaline solution into the initial mixed solution until the pH value of the initial mixed solution reaches 11.

[0066] In some embodiments, in step S111, the molar ratio of magnesium nitrate hexahydrate to aluminum nitrate nonahydrate and the corrosion inhibitor is 3:1:3. Magnesium nitrate hexahydrate, aluminum nitrate nonahydrate and the corrosion inhibitor are dissolved in deionized water according to the above molar ratio and stirred to obtain an initial mixed solution.

[0067] In step S112, NaOH powder is dissolved in deionized water and stirred evenly to obtain a sodium hydroxide alkaline solution.

[0068] In step S113, the sodium hydroxide alkaline solution is dropped into the initial mixed solution while stirring, and the pH value of the initial mixed solution is monitored by a pH meter until the pH value reaches 11, and the dropping is stopped to obtain a first mixed solution of magnesium nitrate hexahydrate, aluminum nitrate nonahydrate and corrosion inhibitor.

[0069] In step S120, the first mixed solution is transferred to a reactor for hydrothermal reaction, maintaining a first predetermined temperature, for example, 120°C, and heating for 10 to 14 hours. After heating, the mixture is cooled to obtain a precipitate, i.e., the first reactant.

[0070] In step S130, the first reactant is washed with deionized water and then washed again with anhydrous ethanol. The above two washing processes can be performed multiple times. The first reactant is then centrifuged at a speed of 2000-4000 RPM for 8-12 minutes. The centrifuged first reactant is then placed in a culture dish and dried at 70°C-80°C for 10-14 hours to obtain a corrosion inhibitor intercalated LDH, which is referred to as LDH-MBI.

[0071] Figure 4 for Figure 1 In the specific flow chart of step S200, in some embodiments, as Figure 4 As shown, step S200: preparing the corrosion inhibitor intercalated LDH / MoS2 heterostructure by a hydrothermal method combined with an in-situ growth method includes the following steps:

[0072] S210: preparing a second mixed solution of ammonium molybdate tetrahydrate, thiourea and corrosion inhibitor intercalated LDH;

[0073] S220: placing the second mixed solution into a reactor for hydrothermal in-situ growth to obtain a second reactant;

[0074] S230: washing and centrifuging the second reactant to obtain a second precipitate, and drying the precipitate.

[0075] In some embodiments, the mass ratio of ammonium molybdate tetrahydrate, thiourea, and corrosion inhibitor intercalated LDH is 1:3:1.

[0076] Specifically, in step S210, ammonium molybdate tetrahydrate, thiourea, and LDH-MBI are weighed according to a mass ratio, mixed, added into deionized water, and stirred uniformly to obtain a second mixed solution.

[0077] In step S220, the second mixed solution is transferred to a reactor for hydrothermal in-situ growth, maintaining a second predetermined temperature, for example, 180°C for 10-14 hours, and cooling after heating to obtain a precipitate, i.e., the second reactant.

[0078] In a hydrothermal environment with high temperature and high pressure (180°C), the precursor thiourea (CH4N2S) decomposes to produce H2S gas, which reacts with molybdate ions (MoO4² - ) undergoes a sulfide-reduction reaction, ultimately forming MoS2 nanosheets. The key to this process is that the active reaction sites are directly located on the layer and surface of the LDH, which allows the nucleation and growth of MoS2 to be precisely confined to the LDH support, ultimately forming a heterogeneous structure in which the MoS2 nanosheets are tightly anchored and coated on the LDH surface.

[0079] In step S230, the second reactant is washed with deionized water and washed again with anhydrous ethanol. Both washing methods can be performed multiple times. The second reactant is then centrifuged at a speed of 2000RPM~4000RPM for 8~12 minutes. The centrifuged second reactant is then placed in a culture dish and dried at 70℃~80℃ for 10~14 hours to obtain a corrosion inhibitor intercalated LDH / MoS2 heterostructure, which is recorded as MoS2@LDH-MBI.

[0080] Figure 5 for Figure 1 In the specific flow chart of step S300, in some embodiments, as Figure 5 As shown, step S300: preparing a polyurea matrix includes the following steps:

[0081] S310: preparing semi-prepolymer;

[0082] S320: preparing a chain extender;

[0083] S330: Mixing and stirring the semi-prepolymer and the chain extender in a predetermined ratio.

[0084] In these embodiments, the semi-prepolymer (component A) and the chain extender (component B) are mixed and fully stirred with a mechanical stirring blade to form a polyurea matrix.

[0085] In step S310, a semi-prepolymer (component A) is synthesized by reacting polyetheramine D2000 with IPDI (isophorone diisocyanate). Specifically, polyetheramine D2000 and IPDI are mixed in a molar ratio of 1:3, placed in an ice-water bath, and stirred for 8-12 minutes. After stirring, the mixture is transferred to an oil bath at 70°C-80°C and stirred for 1-1.5 hours to obtain a polyurea prepolymer (component A).

[0086] In step S320 , the chain extender (component B) is selected as E-100 chain extender. Specifically, the E-100 chain extender is dissolved in DMF (N,N-dimethylformamide) and stirred evenly.

[0087] In step S330, a polyurea matrix is ​​prepared by mixing and stirring a semi-prepolymer (component A) and a chain extender (component B). Specifically, the chain extender (component B) solution prepared in step S320 is added dropwise to the semi-prepolymer (component A) and stirred for 10 to 20 minutes to obtain a polyurea matrix.

[0088] Figure 6 for Figure 1 In the specific flow chart of step S400, in some embodiments, as Figure 6 As shown, step S400: mixing the corrosion inhibitor intercalated LDH / MoS2 heterostructure into the polyurea matrix and performing a dispersion and defoaming treatment includes the following steps:

[0089] S410: mixing the corrosion inhibitor intercalated LDH / MoS2 heterostructure into the polyurea matrix;

[0090] S420: Ultrasonic vibration is used to perform dispersion and defoaming treatment on the polyurea matrix with the corrosion inhibitor intercalated LDH / MoS2 heterostructure.

[0091] In some embodiments, the mass ratio of the corrosion inhibitor intercalated LDH / MoS2 heterostructure to the polyurea matrix is ​​1:50.

[0092] In step S410, MoS2@LDH-MBI is mixed into the polyurea matrix at a mass ratio of 1:50.

[0093] In step S420, ultrasonic vibration is used to evenly disperse MoS2@LDH-MBI in the polyurea matrix and defoam it. Specifically, the ultrasonic vibration is performed for 10 to 20 minutes to obtain a corrosion inhibitor intercalated LDH / MoS2 synergistically enhanced corrosion-resistant polyurea coating, which is recorded as PUA-MoS2@LDH-MBI.

[0094] The surface groups (–OH / S) of the filler containing the corrosion inhibitor-intercalated LDH / MoS2 heterostructure can form strong interfacial bonds with the polyurea-urea bond. Specifically, the filler surface groups (–OH of LDH, S atoms of MoS2) form strong hydrogen bonds / coordination bonds with the polyurea-urea bond, simultaneously filling the polymer free volume, giving the coating excellent corrosion resistance while maintaining excellent mechanical properties.

[0095] The corrosion inhibitor intercalated LDH / MoS2 synergistically enhanced corrosion-resistant polyurea coating prepared by the preparation method of the above embodiment has the following beneficial effects:

[0096] MoS2 is in situ grown on the surface of the corrosion inhibitor intercalated LDH by a hydrothermal method combined with an in-situ growth method to construct a compact heterogeneous structure (MoS2@LDH-MBI / MBT). This achieves the integrated integration of the corrosion inhibitor carrier and the physical barrier unit. It can be evenly dispersed in the polyurea matrix without the need for additional dispersants, significantly improving the filler-matrix interface compatibility.

[0097] Active corrosion inhibition and passive barrier synergistically enhance the corrosion inhibitor loaded between LDH layers in response to Cl - Ions trigger controlled release, forming an active protective film at the metal interface. At the same time, the dense "maze" structure formed by the interlaced MoS2 and LDH layers physically blocks the penetration of media. The dual mechanisms work together to achieve long-term intelligent protection.

[0098] The low filler addition level (e.g., 2.0wt%) and process compatibility, along with the highly effective protective properties of the MoS2@LDH-MBI / MBT heterostructure, significantly improve corrosion resistance at low loadings, avoiding the problems of excessive filler-induced increases in polyurea viscosity, deterioration in construction rheology, and attenuation of mechanical properties.

[0099] Interfacial bonding and matrix densification work together to ensure mechanical properties. The filler surface groups (–OH of LDH, S atoms of MoS2) form strong hydrogen bonds / coordination bonds with the polyurea urea bonds, and simultaneously fill the free volume of the polymer, giving the coating excellent corrosion resistance while maintaining outstanding mechanical properties.

[0100] Figure 7 The flowchart of the application method of the corrosion inhibitor intercalated LDH / MoS2 synergistically enhanced corrosion resistant polyurea coating provided by some embodiments of the present invention is shown. Some embodiments of the present invention provide a method for applying the corrosion inhibitor intercalated LDH / MoS2 synergistically enhanced corrosion resistant polyurea coating, such as Figure 7 As shown, the corrosion inhibitor intercalated LDH / MoS2 synergistically enhanced corrosion-resistant polyurea coating is prepared by the preparation method described in the above embodiment, and the application method includes the following steps:

[0101] S710: applying the corrosion inhibitor intercalated LDH / MoS2 synergistically enhanced corrosion-resistant polyurea coating to the surface to be protected from corrosion;

[0102] S720: Perform a drying and curing operation in a predetermined temperature environment.

[0103] In step S710, a corrosion inhibitor intercalated LDH / MoS2 synergistically enhanced corrosion-resistant polyurea coating is evenly applied to a surface to be protected from corrosion, such as a metal surface, with a coating thickness of, for example, 80 to 150 μm. The surface to be protected from corrosion may be pretreated in advance, specifically, by cleaning with acetone and drying, and polishing the surface with sandpaper to make it smooth.

[0104] In step 720 , the surface to be anti-corrosion coated with the coating is dried in an environment of 70° C. to 80° C. for 10 to 14 hours.

[0105] The following specifically introduces the specific embodiments and comparative examples of the preparation method of the present invention. For the convenience of comparison, in the following specific embodiments and comparative examples, the prepared coating is applied to the surface of a Q235 steel sheet sample, and a coating is obtained after drying and curing, and the anti-corrosion performance of each coating is subsequently compared.

[0106] Example 1

[0107] Example 1 provides a method for preparing a corrosion-resistant polyurea coating synergistically enhanced by intercalating LDH / MoS2 as a corrosion inhibitor, which specifically comprises the following steps:

[0108] S1: Preparation of corrosion inhibitor intercalated LDH by hydrothermal method

[0109] Specifically, 2.56 g of magnesium nitrate hexahydrate, 1.25 g of aluminum nitrate nonahydrate, and 1.5 g of MBI were weighed and mixed into a beaker, and 90 ml of deionized water was added and stirred to obtain an initial mixed solution; 2 g of NaOH powder was weighed and placed into a beaker, 25 ml of deionized water was added, and stirred to obtain a sodium hydroxide alkaline solution; the sodium hydroxide alkaline solution was dropped into the initial mixed solution, and stirred while adding, and the pH value of the initial mixed solution was monitored by a pH meter until the pH value reached 11, and the dropwise addition was stopped to obtain a first mixed solution of magnesium nitrate hexahydrate, aluminum nitrate nonahydrate, and a corrosion inhibitor;

[0110] The first mixed solution was transferred to a reactor for hydrothermal reaction, maintained at 120°C for 12 hours, and cooled after heating to obtain a precipitate, i.e., the first reactant;

[0111] The first reactant was washed three times with deionized water and again three times with anhydrous ethanol. The first reactant was then centrifuged at 3000 RPM for 10 minutes. The centrifuged first reactant was placed in a culture dish and dried in an oven at 75° C. for 12 hours to obtain a corrosion inhibitor intercalated LDH, which was recorded as LDH-MBI.

[0112] S2: The corrosion inhibitor intercalated LDH / MoS2 heterostructure was prepared by a hydrothermal method combined with in situ growth.

[0113] Specifically, 2g of ammonium molybdate tetrahydrate, 6g of thiourea, and 2g of LDH-MBI were weighed into a beaker, 100ml of deionized water was added and stirred evenly to obtain a second mixed solution; the second mixed solution was transferred to a reactor for hydrothermal in situ growth, maintained at 180°C for 12h, and cooled after heating to obtain a precipitate, i.e., the second reactant; the second reactant was washed 3 times with deionized water, and the second reactant was washed again 3 times with anhydrous ethanol, and then the second reactant was centrifuged in a centrifuge at a speed of 3000RPM for 10min, and then the centrifuged second reactant was placed in a culture dish and dried in an oven at 75°C for 12h to obtain a corrosion inhibitor intercalated LDH / MoS2 heterostructure, recorded as MoS2@LDH-MBI.

[0114] S3: preparing a polyurea matrix.

[0115] Specifically, 10 g of polyetheramine D2000 and 3.42 g of IPDI were weighed and placed in an ice-water bath and stirred for 10 minutes. After stirring, the mixture was transferred to an oil bath and stirred at 75°C for 1 hour to obtain a polyurea prepolymer (component A). 1.63 g of E-100 chain extender (component B) was dissolved in 10 ml of DMF (N,N-dimethylformamide) and stirred evenly. The chain extender (component B) solution was added dropwise to the semi-prepolymer (component A) and stirred for 15 minutes to obtain a polyurea matrix.

[0116] S4: mixing the corrosion inhibitor intercalated LDH / MoS2 heterostructure into the polyurea matrix and performing a dispersion and defoaming treatment.

[0117] Specifically, 0.3 g of MoS2@LDH-MBI was mixed into the polyurea matrix, and ultrasonic vibration was used to evenly disperse the MoS2@LDH-MBI in the polyurea matrix and defoam it. Specifically, ultrasonic vibration was performed for 15 minutes to obtain a corrosion inhibitor intercalated LDH / MoS2 synergistically enhanced corrosion-resistant polyurea coating, which was recorded as PUA-MoS2@LDH-MBI.

[0118] This embodiment is based on the prepared corrosion inhibitor intercalated LDH / MoS2 synergistically enhanced corrosion-resistant polyurea coating to prepare a coating for subsequent corrosion resistance testing, and specifically includes the following steps:

[0119] PUA-MoS2@LDH-MBI was uniformly coated on the surface of a pretreated Q235 steel sheet to a film thickness of approximately 100 μm. The sample was then dried in an oven at 75°C for 12 hours to complete curing, resulting in a corrosion-inhibitor-intercalated LDH / MoS2 synergistically reinforced corrosion-resistant polyurea coating, designated as the PUA-MoS2@LDH-MBI layer. In some embodiments, the aforementioned pretreatment included acetone cleaning and drying, and sanding the surface for smoothness.

[0120] Example 2

[0121] Example 2 provides a preparation method for a corrosion inhibitor intercalated LDH / MoS2 synergistically enhanced corrosion-resistant polyurea coating. The preparation method in Example 2 is basically the same as the preparation method in Example 1, except that in the preparation method in Example 2, the corrosion inhibitor uses MBT instead of MBI, and the obtained coating is recorded as PUA-MoS2@LDH-MBT. The coating prepared in a manner basically the same as the preparation method of the coating in Example 1 is recorded as PUA-MoS2@LDH-MBT layer.

[0122] Comparative Example 1

[0123] Comparative Example 1 provides a preparation method for a corrosion-resistant polyurea coating. The preparation method in Comparative Example 1 is basically the same as the preparation method in Example 1, except that the preparation method in Comparative Example 1 does not use a corrosion inhibitor, and the other parameters are the same as those in Example 1. The obtained coating is recorded as PUA-MoS2@LDH, and the coating prepared in a manner basically the same as the preparation method of the coating in Example 1 is recorded as PUA-MoS2@LDH layer.

[0124] Comparative Example 2

[0125] Comparative Example 2 provides a preparation method for a corrosion-resistant polyurea coating. The preparation method in Comparative Example 2 is basically the same as the preparation method in Example 1, except that MoS2 is not used in the preparation method in Comparative Example 2. Specifically, after obtaining LDH-MBI in step S1, step S3 is directly performed. In step S4, MoS2@LDH-MBI is replaced with LDH-MBI of equal mass. The remaining steps are the same. The obtained coating is recorded as PUA-LDH-MBI, and the coating prepared in a manner basically the same as the preparation method of the coating in Example 1 is recorded as PUA-LDH-MBI layer.

[0126] Comparative Example 3

[0127] Comparative Example 3 provides a preparation method for a corrosion-resistant polyurea coating. The preparation method in Comparative Example 3 is basically the same as the preparation method in Example 1, except that LDH is not used in the preparation method in Comparative Example 3. Specifically, steps S1 and S2 are omitted; step S3 is the same as in Example 1, and 0.3 g of MoS2 is added to the polyurea matrix in step S4. The remaining steps are the same. The obtained coating is recorded as PUA-MoS2, and the coating prepared in a manner basically the same as the preparation method of the coating in Example 1 is recorded as a PUA-MoS2 layer.

[0128] Comparative Example 4

[0129] Comparative Example 4 provides a preparation method for a corrosion-resistant polyurea coating. The preparation method in Comparative Example 4 is basically the same as the preparation method in Example 1, except that no filler is used in the preparation method in Comparative Example 4. Specifically, steps S1, S2, and S4 are omitted, and the polyurea matrix obtained in step S3 is directly used as a coating, which is recorded as PUA. The coating prepared in a manner basically the same as the preparation method of the coating in Example 1 is recorded as a PUA layer.

[0130] To systematically evaluate the corrosion resistance of the present invention's corrosion-inhibitor intercalated LDH / MoS2 synergistically enhanced corrosion-resistant polyurea coating, electrochemical impedance spectroscopy (EIS) testing was performed over a 50-day period on the coating samples prepared in Example 1 and Example 2, as well as Comparative Examples 1, 2, 3, and 4. During the test, all samples were immersed in a simulated seawater environment, and impedance data was regularly collected to monitor changes in the coating's corrosion resistance over time. By analyzing changes in the impedance modulus in the low-frequency region, the permeability resistance and long-term protective effects of coatings with different formulations were evaluated, aiming to verify the synergistic protection mechanism and superiority of the composite coatings prepared in this invention.

[0131] Table 1 shows the low-frequency impedance modulus values ​​(|Z|) of the Bode diagram of different samples during 50 days of immersion. 0.01 Hz, unit: Ω·cm²)

[0132] Table 1 Bode plot low-frequency impedance modulus values ​​of different samples during 50 days of immersion

[0133]

[0134] The core of the corrosion resistance of organic polyurea coating systems lies in their ability to resist penetration by corrosive media, which can be quantitatively evaluated by the impedance modulus (Ω·cm²) in the low-frequency region of electrochemical impedance spectroscopy (EIS). The coatings of various formulations were immersed in artificial seawater for 50 days and the impedance changes were monitored in real time (data shown in the table). The results showed that the low-frequency impedance modulus of the pure polyurea coating (PUA layer in Comparative Example 4) increased from an initial 1.8×10 9 Ω·cm² rapidly decreases to 9.0×10 7Ω·cm², indicating that the corrosive medium has quickly penetrated the coating and induced electrochemical reactions at the metal / coating interface. The composite coating with only a single functional filler also showed significant attenuation, in which the PUA-MoS2 layer (Comparative Example 3) decreased from 2.4×10 9 Ω·cm² dropped to 1.6×10 8 Ω·cm², the PUA-LDH-MBI layer (Comparative Example 2) increased from 2.6×10 9 Ω·cm² dropped to 1.4×10 8 Ω·cm², indicating that a single physical barrier or corrosion inhibition structure is difficult to effectively block penetration for a long time; while the MoS2@LDH composite filler system without corrosion inhibitor (Comparative Example 1, PUA-MoS2@LDH layer) 9 Ω·cm² rapidly decreased to 4.0×10 7 Ω·cm², further proving that the lack of active corrosion inhibition will lead to early failure of the protection system. In contrast, the two synergistic heterostructure coatings constructed in the present invention show significantly superior performance: the impedance modulus of Example 1 (PUA-MoS2@LDH-MBI) increased from 5.2×10 9 Ω·cm² slowly decreases to 4.0×10 9 Ω·cm², Example 2 (PUA-MoS2@LDH-MBT) from 4.8×10 9 Ω·cm² dropped to 3.5×10 9 Ω·cm², and both remained at 10 during the 50-day immersion period. 9 The decrease in the corrosion rate was on the order of Ω·cm², with the most gradual attenuation. This result fully demonstrates that the multi-synergistic mechanism of "controlled release of LDH-loaded corrosion inhibitor – maze effect of MoS2 sheets – filler-matrix interface densification" can effectively extend the penetration path of the corrosive medium and continuously inhibit interfacial reactions, thereby endowing the coating with long-term corrosion resistance significantly superior to all comparative examples.

[0135] The excellent long-term corrosion resistance of the coating system is due to its multi-level synergistic protection mechanism: the MBI corrosion inhibitor loaded between the LDH layers can respond to the Cl - The ions are triggered to achieve controlled release, migrate to the metal interface and form a dense passivation film through adsorption-coordination, actively inhibiting the cathode corrosion reaction; at the same time, the inherent exchangeable layered skeleton of LDH constructs a multi-level ion capture barrier inside the coating, effectively intercepting corrosive ions (such as Cl - More importantly, the MoS2 sheets grown in situ on the surface of the corrosion inhibitor intercalated LDH by the secondary hydrothermal method formed a dense heterogeneous structure (MoS2@LDH), which was staggered in the polyurea matrix and significantly prolonged the Cl -, H2O, and O2. Furthermore, the abundant active groups on the surface of the heterogeneous filler (-OH from LDH, -S from MoS2) form a strong hydrogen bond and coordination bond network with the urea bonds (-NH-CO-NH-) in the polyurea molecular chain. This not only strengthens the filler-matrix interface adhesion but also simultaneously densifies the polymer matrix structure, effectively blocking the penetration of media along the interface. These "active corrosion inhibition," "ion capture," "high-efficiency physical barrier," and "interface strengthening" mechanisms are not isolated but rather work in synergy and dynamic response, forming an intelligent, efficient, multi-layered dynamic protection network. This is the core guarantee for the coating's excellent permeability resistance and extremely long service life in harsh corrosive environments (such as marine environments).

[0136] In summary, the low-frequency impedance modulus of the coating increases with the immersion time from 10 9 The magnitude decays smoothly to 10 8 -10 9 The changing pattern of Ω·cm² (especially the high initial value and slow decay rate of Example 1) fully verifies the innovation of the present invention - the triple synergistic mechanism of "active intelligent slow release", "efficient physical barrier" and "interface strengthening" achieved by constructing a corrosion inhibitor intercalated LDH / MoS2 heterostructure plays a decisive role in significantly improving the anti-permeability of the polyurea coating and extending its service life in harsh environments (such as marine environments).

[0137] Table 2 shows the EDS atomic percentages (at%) of different coating cross-sections after 50 days of electrochemical immersion. After the 50-day electrochemical immersion test, SEM-EDS point / surface scans were performed on the peeled cross-sections of the six coatings, yielding the element atomic percentages (at%) shown in Table 2. To highlight the differences between corrosion products (Fe, Cl) and functional components (Mg, Al, Mo, S, N), Na (introduced from seawater) is also listed separately. Data were measured at three different locations and averaged, totaling approximately 100% (rounding may result in slight deviations of ±0.1% in some columns).

[0138] Table 2 EDS atomic percentage (at%) of different coating cross sections after 50 days of electrochemical immersion

[0139]

[0140] From the above EDS atomic percentage results, it can be seen that the corrosion product iron (Fe) and the electrolyte characteristic element chlorine (Cl) are almost undetectable in the cross-sectional area of ​​the bionic coatings with complete structures (Examples 1 and 2) (total amount ≤ 1%). At the same time, these coatings still retain the characteristic elements of layered double hydroxides (LDH) magnesium (Mg) and aluminum (Al), as well as the elements molybdenum (Mo) and sulfur (S) corresponding to molybdenum disulfide (MoS2). This phenomenon strongly indicates that: MoS2 sheets and LDH layered skeletons are still stably embedded in the polyurea matrix network after immersion for up to 50 days; the exchangeable sites between LDH layers effectively capture the infiltrating chloride ions (Cl - ) and simultaneously release the corrosion inhibitor MBI / MBT, so that the coating / metal interface can be maintained in a passivation state for a long time, thereby almost completely inhibiting the dissolution corrosion of the metal matrix.

[0141] In the coating of Comparative Example 1, which lacks the main corrosion inhibitor, the contents of Fe and Cl increased significantly to a total of 7.9%, and the Na content was as high as 12.4%. This indicates that the seawater electrolyte has penetrated into the interface area over a large area and triggered a serious corrosion reaction. This result is consistent with the impedance modulus value in the electrochemical impedance spectroscopy (EIS) data from 10 9 The weight level dropped sharply to 10 7 The phenomenon of Ω·cm² is completely consistent with that of Ω·cm², which mutually proves that the protection is ineffective.

[0142] In the coatings of Comparative Example 2, which removes the MoS2 physical barrier, or Comparative Example 3, which removes the LDH support, the Mo / S or Mg / Al signals disappear in their cross-sections, respectively, while the Fe and Cl contents both rise to approximately 5%. This clearly demonstrates that the absence of either the active corrosion inhibitor support (LDH) or the efficient physical barrier (MoS2) significantly shortens the diffusion path of the corrosive medium in the coating and severely reduces the inhibitor's efficiency at the interface.

[0143] In the pure polyurea coating (Comparative Example 4), which lacks any functional fillers, the nitrogen (N) and oxygen (O) contents indicate that the polyurea skeleton structure is still intact, but the combined Fe (3.8%) and Cl (2.6%) contents reach 6.4%. This demonstrates that relying solely on the physical barrier effect of the hydrophobic segments of the polyurea itself is insufficient to effectively prevent the penetration and accumulation of corrosive media during long-term immersion.

[0144] In summary, the low chlorine / iron content and high magnesium / aluminum / molybdenum / sulfur element distribution characteristics presented by EDS analysis are consistent with the impedance value in EIS test being able to maintain at 10 9This further confirms the key role played by the triple synergistic mechanism of "MBI cathode passivation," "LDH ion capture," and "MoS2 sheet maze effect" in effectively inhibiting electrolyte migration and metal substrate dissolution at the microscopic level of elemental composition and distribution.

[0145] Finally, it should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. References to the common and similar parts between the various embodiments will be sufficient. For the systems or devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, their descriptions are relatively simple; for relevant details, refer to the descriptions of the methods.

[0146] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for preparing a corrosion-resistant polyurea coating synergistically enhanced by intercalating LDH / MoS2 as a corrosion inhibitor, characterized in that: The preparation method comprises the following steps: The corrosion inhibitor intercalated LDH was prepared by hydrothermal method; The corrosion inhibitor intercalated LDH / MoS2 heterostructure was prepared by a hydrothermal method combined with in situ growth; preparing a polyurea matrix; and The corrosion inhibitor intercalated LDH / MoS2 heterostructure is mixed into the polyurea matrix and subjected to dispersion and defoaming treatment.

2. The preparation method according to claim 1, characterized in that The hydrothermal method for preparing the corrosion inhibitor intercalated LDH comprises the following steps: preparing a first mixed solution of magnesium nitrate hexahydrate, aluminum nitrate nonahydrate, and a corrosion inhibitor; placing the first mixed solution into a reactor for hydrothermal reaction to obtain a first reactant; The first reactant is washed and centrifuged to obtain a first precipitate, which is then dried.

3. The preparation method according to claim 2, characterized in that The preparation of the first mixed solution of magnesium nitrate hexahydrate, aluminum nitrate nonahydrate and a corrosion inhibitor comprises the following steps: Mixing magnesium nitrate hexahydrate, aluminum nitrate nonahydrate and a corrosion inhibitor, dissolving them in deionized water and stirring them evenly to obtain an initial mixed solution; Dissolve sodium hydroxide in deionized water to prepare a sodium hydroxide alkaline solution; The sodium hydroxide alkaline solution is dropped into the initial mixed solution until the pH value of the initial mixed solution reaches 11.

4. The preparation method according to claim 2 or 3, characterized in that The molar ratio of magnesium nitrate hexahydrate, aluminum nitrate nonahydrate and the corrosion inhibitor is 3:1:

3.

5. The preparation method according to any one of claims 1 to 3, characterized in that The preparation of the corrosion inhibitor intercalated LDH / MoS2 heterostructure by a hydrothermal method combined with an in-situ growth method comprises the following steps: preparing a second mixed solution of ammonium molybdate tetrahydrate, thiourea and corrosion inhibitor intercalated LDH; placing the second mixed solution into a reactor for hydrothermal in-situ growth to obtain a second reactant; The second reactant is washed and centrifuged to obtain a second precipitate, which is then dried.

6. The preparation method according to claim 5, characterized in that The mass ratio of the ammonium molybdate tetrahydrate, thiourea and corrosion inhibitor intercalated LDH is 1:3:

1.

7. The preparation method according to any one of claims 1 to 3, characterized in that The preparation of the polyurea matrix comprises the following steps: Preparation of semi-prepolymer; preparing a chain extender; and The semi-prepolymer and the chain extender are mixed and stirred according to a predetermined ratio.

8. The preparation method according to any one of claims 1 to 3, characterized in that Mixing the corrosion inhibitor intercalated LDH / MoS2 heterostructure into the polyurea matrix and performing a dispersion and defoaming treatment comprises the following steps: mixing the corrosion inhibitor intercalated LDH / MoS2 heterostructure into the polyurea matrix; Ultrasonic vibration was used to perform dispersion and defoaming treatment on the polyurea matrix with corrosion inhibitor intercalated LDH / MoS2 heterostructure.

9. The preparation method according to claim 4, characterized in that The mass ratio of the corrosion inhibitor intercalated LDH / MoS2 heterostructure to the polyurea matrix is ​​1:

50.

10. An application method of a corrosion inhibitor intercalated LDH / MoS2 synergistically enhanced corrosion-resistant polyurea coating, characterized in that: The corrosion inhibitor intercalated LDH / MoS2 synergistically enhanced corrosion-resistant polyurea coating is prepared by the preparation method according to any one of claims 1 to 9, and the application method comprises the following steps: Applying the corrosion inhibitor intercalated LDH / MoS2 synergistically enhanced corrosion-resistant polyurea coating to the surface to be protected from corrosion; and The drying and curing operation is performed in a predetermined temperature environment.

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