Graphene anticorrosive coating, preparation method and application thereof

Abstract

The application discloses a graphene anticorrosive paint and a preparation method and application thereof. The graphene anticorrosive paint is mainly composed of epoxy resin, polyaniline modified hexagonal boron nitride, anticorrosive filler, modified graphene slurry, additive, solvent and curing agent, etc. According to weight parts, the graphene anticorrosive paint comprises 20-40 parts of epoxy resin, 25-50 parts of polyaniline modified hexagonal boron nitride, 20-50 parts of anticorrosive filler, 0.2-1.0 parts of modified graphene slurry, 1-5 parts of additive, 10-20 parts of organic solvent and 20-40 parts of curing agent. The modified graphene slurry is added into the epoxy resin, the two-dimensional sheet layer graphene can improve the barrier property of the coating, meanwhile, the graphene dispersant phytic acid in the slurry can not only passivate the metal, but also can occur chelation reaction with the rust on the surface of the metal base material, thereby improving the rust coating performance of the coating.

Description

Technical Field

[0001] This invention relates to the field of metal anti-corrosion coatings, specifically to a graphene anti-corrosion coating, its preparation method, and its application. In particular, it designs a coating capable of protecting metal surfaces in marine environments and its preparation method. Background Technology

[0002] Hexagonal boron nitride (BN) is a two-dimensional sheet material with a structure similar to graphene, often referred to as "white graphene," and possesses excellent thermal conductivity, electrical insulation, chemical inertness, and barrier properties. Due to the electronegativity difference between B and N atoms in the BN structure, there are not only van der Waals forces but also ionic bonds between the BN layers, making BN more prone to aggregation. Therefore, modification treatment is necessary to improve its dispersion performance.

[0003] Polyaniline contains highly electronegative O and N polar groups, which can coordinate with protons in the pickling medium to form positively charged cations. The lone pair π electrons in its highly conjugated structure can form coordinate bonds with empty d orbitals of metals, adsorbing onto the metal surface through physical or chemical interactions. The C and H nonpolar groups in the polyaniline molecule arrange in parallel on the metal surface to form a hydrophobic layer, providing passivation and corrosion inhibition. Sang Yunlong of Hebei University of Technology achieved covalent bonding between hydroxylated hexagonal boron nitride and aminotrimethylenephosphonic acid-doped polyaniline using p-aminobenzoic acid, and characterized the covalent modification of boron nitride by polyaniline. The modified boron nitride showed good dispersibility in water and no aggregation after 24 hours, successfully enabling its application in organic passivation film systems.

[0004] The marine environment is a harsh and corrosive environment. Traditional anti-corrosion coatings require high pretreatment of the substrate, generally needing to reach Sa2.5 grade. Furthermore, they have a short service life in marine corrosive environments and are prone to blistering, peeling, and corrosion. Therefore, developing an anti-corrosion coating for marine environments with good anti-corrosion performance and low substrate pretreatment requirements is of great significance for extending the service life of marine engineering equipment. Summary of the Invention

[0005] The main objective of this invention is to provide a graphene anti-corrosion coating, its preparation method, and its application, so as to overcome the shortcomings of the prior art.

[0006] To achieve the aforementioned objectives, this invention provides a graphene anti-corrosion coating, which is mainly composed of epoxy resin, polyaniline-modified hexagonal boron nitride, anti-corrosion filler, additives, solvents, and curing agents.

[0007] The specific technical solution includes, by weight, the graphene anti-corrosion coating comprising 20-40 parts epoxy resin, 25-50 parts polyaniline-modified hexagonal boron nitride, 20-50 parts anti-corrosion filler, 0.2-1.0 parts modified graphene slurry, 1-5 parts additives, 10-20 parts organic solvent, and 20-40 parts curing agent.

[0008] Preferably, the polyaniline-modified hexagonal boron nitride is obtained by polymerization of aniline and hydroxylated hexagonal boron nitride in ammonium persulfate solution.

[0009] Preferably, the polymerization reaction includes a dehydration condensation reaction between the amino group in aniline and the hydroxyl group in hexagonal boron nitride, while the aniline monomer self-polymerizes to form polyaniline; during the polymerization reaction, polyaniline is grafted onto the surface of boron nitride to inhibit the aggregation of boron nitride.

[0010] Preferably, the polyaniline-modified hexagonal boron nitride has a two-dimensional lamellar structure, and the amino groups on the surface of the polyaniline-modified hexagonal boron nitride undergo a curing reaction with the epoxy groups of the epoxy resin to crosslink and form a paint film with a dense structure.

[0011] Preferably, the hydroxylated hexagonal boron nitride is prepared by ultrasonication of hexagonal boron nitride in a concentrated alkaline solution.

[0012] Preferably, the particle size of the polyaniline-modified hexagonal boron nitride is 5–30 μm, more preferably 5–15 μm, and the optimal particle size is 10 μm.

[0013] Preferably, the concentrated alkaline solution is a saturated sodium hydroxide solution and / or a saturated potassium hydroxide solution.

[0014] Preferably, the polymerization reaction conditions include a reaction temperature of 0–4°C.

[0015] Preferably, the modified graphene slurry comprises mixing phytic acid, graphene oxide, and deionized water, performing a hydrolysis polymerization reaction at 80–90°C for 10–12 hours, and then separating the solid and liquid phases to obtain the modified graphene slurry.

[0016] Preferably, the graphene oxide is prepared by oxidation of high-purity graphite in concentrated sulfuric acid and saturated potassium permanganate solution.

[0017] Preferably, the oxidation reaction conditions include a reaction temperature of 30–60°C and a reaction time of 24–48 h.

[0018] Preferably, the epoxy resin includes one or a combination of E20, E44 and E51.

[0019] Preferably, the anti-corrosion filler includes one or more of talc powder, precipitated barium sulfate, and ferrophosphorus powder.

[0020] Preferably, the additives include one or more of the following: efka4010 dispersant, bentonite, and fumed silica.

[0021] Preferably, the solvent is one or a combination of acetone, xylene, and n-butanol.

[0022] Preferably, the amount of the additive is 1 wt% to 2 wt%; more preferably 1.2 wt% to 1.8 wt%; and most preferably 1.5 wt%.

[0023] Preferably, the curing agent is one or a combination of polyamide, polyetheramine, and alicyclic amine.

[0024] As another objective, the present invention also provides a method for preparing the aforementioned graphene anti-corrosion coating, comprising the following steps:

[0025] S1. Provides polyaniline-modified hexagonal boron nitride:

[0026] After the hydroxylated hexagonal boron nitride is evenly dispersed in an alkaline solution, aniline is added and stirred to form a milky white mixture; an oxidant is added dropwise to polymerize aniline on the surface of the hydroxylated hexagonal boron nitride to form the polyaniline-modified hexagonal boron nitride.

[0027] S2. Preparation of anti-corrosion coatings:

[0028] Modified graphene slurry, additives, first solvent and anti-corrosion filler are added to epoxy resin in sequence, stirred, ground and filtered to obtain the first component;

[0029] The second component is obtained by adding a second solvent and polyaniline-modified hexagonal boron nitride to the curing agent, stirring, grinding, and filtering.

[0030] The anti-corrosion coating is obtained by mixing the first component and the second component and then allowing them to mature.

[0031] Preferably, in S1, the preparation of the hydroxylated hexagonal boron nitride includes: adding hexagonal boron nitride to a saturated concentrated alkaline solution, reacting with ultrasound, and then drying to obtain hydroxylated hexagonal boron nitride.

[0032] Preferably, the dispersion method of the hydroxylated hexagonal boron nitride includes: adding the hydroxylated hexagonal boron nitride to a saturated concentrated alkaline solution and sonicating for 2-5 hours, magnetically stirring at 3000 r / min for 2-6 hours to form a homogeneous solution, and then refluxing in an oil bath at 130°C for 48 hours. The resulting solution is cooled and filtered, washed with deionized water until the solution pH is neutral, and dried in a vacuum drying oven at 80°C to obtain the dispersed hydroxylated hexagonal boron nitride.

[0033] Preferably, the polymerization is carried out at 0–4°C; preferably, the oxidant is added dropwise under stirring conditions in an ice bath at 0–4°C, and after stirring for 12–24 h, it is allowed to stand at 0–4°C for 24 h to allow aniline to undergo a polymerization reaction on the surface of the hydroxylated hexagonal boron nitride to obtain the hydroxylated hexagonal boron nitride.

[0034] Preferably, the oxidant includes at least one of ammonium persulfate solution, hydrogen peroxide (H2O2) solution, or chlorate solution; more preferably, the oxidant is added dropwise to an alkaline solution of aniline and hydroxylated hexagonal boron nitride.

[0035] Preferably, the concentration of the oxidant is 3-5 wt%.

[0036] Preferably, the mass ratio of aniline, the oxidant and the hydroxylated hexagonal boron nitride is (3-5):(4.5-6.5):(1.5-5.5).

[0037] Preferably, the stirring speed in the preparation of the first component is 3000 r / min, and the stirring time is 30-50 min; the fineness of the first component is ≤30 micrometers.

[0038] Preferably, the stirring speed in the preparation of the second component is 500 r / min, and the stirring time is 3-5 min.

[0039] This invention also provides a coating formed from any of the aforementioned anti-corrosion coatings for marine environments.

[0040] The present invention also provides the use of any of the aforementioned graphene anti-corrosion coatings for marine environments in the protective treatment of metal surfaces.

[0041] Compared with existing technologies, this invention is a metal anti-corrosion coating that can be naturally dried at room temperature in a marine environment. The resulting paint film has good adhesion to the metal surface, strong resistance to salt spray and water vapor barrier properties, and low requirements for substrate pretreatment, and has the function of coating on rusted surfaces.

[0042] The beneficial technical effects obtained by this invention are as follows:

[0043] 1. In this invention, polyaniline is used to chemically modify hexagonal boron nitride. Aniline is then chemically polymerized on the surface of hydroxylated boron nitride and grafted onto the surface of hydroxylated hexagonal boron nitride to form a polymer layer. On the one hand, this reduces the interaction forces between boron nitride layers, effectively inhibiting the aggregation of boron nitride and improving the dispersion performance of boron nitride in epoxy resin. On the other hand, the aniline oligomers formed by the polymerization on the boron nitride surface can undergo ring-opening reactions with the epoxy groups in the epoxy resin, improving the toughness and density of the epoxy coating.

[0044] 2. Polyaniline on the surface of hexagonal boron nitride can not only improve the dispersion performance of boron nitride, but also the nonpolar groups such as C and H in the polyaniline molecular structure are arranged in parallel on the metal surface to form a hydrophobic layer, which has the functions of passivation and corrosion inhibition on the metal.

[0045] 3. Adding modified graphene slurry to epoxy resin can improve the barrier properties of the coating. At the same time, phytic acid, a graphene dispersant in the slurry, can not only passivate metals, but also chelate with rust on the surface of metal substrates, thereby improving the coating performance for rust-resistant surfaces. Attached Figure Description

[0046] Figure 1 This is a schematic diagram illustrating the preparation mechanism of polyaniline-modified hexagonal boron nitride according to the present invention.

[0047] Figure 2 These are the infrared spectra of boron nitride (BN), hydroxylated boron nitride (BN-OH), polyaniline (PANI), and polyaniline-modified hexagonal boron nitride (PANI / BN) of Example 1 of this invention.

[0048] Figures 3a-3c The images are SEM images of undispersed boron nitride (BN), polyaniline (PANI), and polyaniline-modified hexagonal boron nitride (PANI / BN) after dispersion, respectively, in Example 1.

[0049] Figure 4 The images show the potentiodynamic polarization curves of different coating systems in Embodiment 1, Comparative Examples 1-2, and Comparative Example 5 of the present invention.

[0050] Figures 5a-5c The images show salt spray resistance test photos of different coating systems provided in Embodiment 1, Comparative Example 1, and Comparative Example 2 of the present invention. Detailed Implementation

[0051] The technical solution of the present invention will be explained in more detail below through specific embodiments. However, it should be understood that within the scope of the present invention, the above-mentioned technical features of the present invention and the technical features specifically described below (such as embodiments) can be combined with each other to form new or preferred technical solutions. Due to space limitations, they will not be described in detail here.

[0052] This invention provides a graphene anti-corrosion coating for marine environments, which is mainly composed of epoxy resin, polyaniline-modified hexagonal boron nitride, anti-corrosion filler, additives, solvents and curing agents.

[0053] Among them, polyaniline-modified hexagonal boron nitride is formed by in-situ polymerization of polyaniline on the surface of hexagonal boron nitride, thereby forming a polymer layer with hydrophobic properties. On the one hand, it can reduce the interaction force between boron nitride layers, thereby improving the dispersion performance of hexagonal boron nitride and effectively inhibiting the agglomeration of boron nitride. On the other hand, the aniline oligomers formed by polymerization on the surface of boron nitride can undergo ring-opening reaction with the epoxy groups in epoxy resin, improving the toughness and density of epoxy coating. At the same time, the nonpolar groups such as C and H in the polyaniline molecular structure are arranged in parallel on the metal surface to form a hydrophobic layer, which has passivation and corrosion inhibition functions for the metal.

[0054] See Figure 1 The diagram illustrates the preparation mechanism of polyaniline-modified hexagonal boron nitride according to the present invention. First, hexagonal boron nitride is modified by hydroxylation. Then, polyaniline reacts and fully polymerizes on the surface of the hydroxylated hexagonal boron nitride, ultimately yielding polyaniline-modified hexagonal boron nitride.

[0055] In some preferred embodiments, the graphene anti-corrosion coating for marine environments comprises the following components by weight: 20-40 parts epoxy resin, 25-50 parts polyaniline-modified hexagonal boron nitride, 20-50 parts anti-corrosion filler, 0.2-1.0 parts modified graphene slurry, 1-5 parts additives, 10-20 parts organic solvent, and 20-40 parts curing agent.

[0056] Furthermore, the polyaniline-modified hexagonal boron nitride is formed by chemical polymerization of aniline and hydroxylated hexagonal boron nitride in a low-temperature ammonium persulfate solution.

[0057] Furthermore, hydroxylated hexagonal boron nitride is prepared by ultrasonication of hexagonal boron nitride in a concentrated alkaline solution.

[0058] Furthermore, the chemical polymerization mainly utilizes the dehydration condensation reaction between the amino group in aniline and the hydroxyl group in hexagonal boron nitride, and the aniline monomer can also self-polymerize to form polyaniline. Through the entire chemical polymerization process, polyaniline can grow on the surface of boron nitride, improving the dispersibility of boron nitride.

[0059] Furthermore, polyaniline-modified hexagonal boron nitride is not only a functional anti-corrosion filler with a two-dimensional layered structure, but the amino groups on the surface of boron nitride can also undergo a curing reaction with the epoxy groups of epoxy resin, thereby improving the density and cross-linking density of the coating film.

[0060] Furthermore, the concentrated alkaline solution is one or a combination of saturated sodium hydroxide solution, saturated potassium hydroxide solution, and the temperature of the low-temperature ammonium persulfate solution is 0℃-4℃.

[0061] Furthermore, the modified graphene slurry is prepared by mixing phytic acid, graphene oxide, and deionized water, performing a hydrolysis polymerization reaction at 80-90°C for 10-12 hours, and then separating the solid and liquid phases to obtain a phytic acid-modified graphene slurry.

[0062] Furthermore, the graphene oxide is prepared by oxidation of high-purity graphite in 5 mol / L concentrated sulfuric acid and saturated potassium permanganate solution at a reaction temperature of 30-60℃ for 24-48 h.

[0063] Furthermore, the epoxy resin is one or a combination of E20, E44 and E51; the anti-corrosion filler is one or a combination of talc, precipitated barium sulfate and ferric phosphate.

[0064] Furthermore, the additive is one or a combination of EFKA4010 dispersant, bentonite, and fumed silica; the solvent is one or a combination of acetone, xylene, and n-butanol. The additive dosage is 1 wt% to 2 wt%, preferably 1.2 wt% to 1.8 wt%, and the optimal content is 1.5 wt%.

[0065] Furthermore, the curing agent is one or a combination of polyamide, polyetheramine, and alicyclic amine. The amount of curing agent added is determined based on the epoxy value of the epoxy resin.

[0066] In some specific embodiments, the preparation method of graphene anti-corrosion coating includes the following steps:

[0067] Preparation of S1. Hydroxylated hexagonal boron nitride:

[0068] Add a saturated concentrated alkali solution to a beaker, then add hexagonal boron nitride. Sonicate for 2–5 hours, then magnetically stir at 3000 rpm for 2–6 hours to form a homogeneous solution. Finally, reflux in an oil bath at 130°C for 48 hours. Cool and filter the resulting solution, wash with deionized water until the pH is neutral, and dry in a vacuum drying oven at 80°C to obtain hydroxylated hexagonal boron nitride.

[0069] Preparation of S2 polyaniline-modified hexagonal boron nitride:

[0070] First, weigh 3-5g of aniline and add it to 500ml of prepared 1.5M hydrochloric acid solution. Stir magnetically at 1200r / min to form a uniform, transparent solution. Then, weigh 1.5-5.5g of hydroxylated nano-hexagonal boron nitride and dissolve it in 200ml of deionized water. Disperse the solution ultrasonically for 2-5 hours. Add the dispersed nano-hexagonal boron nitride solution to the aniline mixture and stir magnetically for 6-10 hours until a milky white mixture is formed. Finally, stir in an ice bath at 0-4℃, adding 4.5-6.5g of an oxidant aqueous solution dropwise during stirring. After stirring for 12-24 hours, let it stand at 0-4℃ for 24 hours to allow the polyaniline to chemically react and fully polymerize on the surface of the hydroxylated hexagonal boron nitride. Vacuum filter the solution after standing, wash it 5-8 times with deionized water and ethanol, dry it in a vacuum drying oven at 80℃ for 24 hours, grind it, and finally obtain a dark green product, which is polyaniline-modified hexagonal boron nitride. The particle size of polyaniline-modified hexagonal boron nitride is controlled to be 5-30 μm, preferably 5-15 μm, and the optimal particle size is 10 μm.

[0071] Preparation of S3 anti-corrosion coating:

[0072] Modified graphene slurry, additives, solvents, and anti-corrosion fillers are added to epoxy resin in sequence, following the order from light to heavy. The mixture is stirred at 3000 rpm for 30-50 minutes, ground, and then filtered and packaged to obtain component A.

[0073] Add solvent and polyaniline-modified hexagonal boron nitride to the curing agent, stir at 500 rpm for 3-5 minutes, filter, and package to obtain component B;

[0074] Based on the relationship between epoxy value and active hydrogen equivalent in components A and B, the mixing ratio is determined, and the mixture is allowed to mature for 5-10 minutes to obtain an anti-corrosion coating for marine environments.

[0075] Another aspect of the present invention provides a coating formed by applying the graphene coating to a metal surface.

[0076] Another aspect of the present invention provides the use of the graphene coating in the protection of metals in a marine environment.

[0077] Another aspect of the present invention provides a method for protecting a metal substrate, comprising: coating the surface of the metal substrate with the aforementioned anti-corrosion coating for metal surfaces, and curing the protective coating into a film (particularly at room temperature).

[0078] Preferably, the metal substrate includes various stainless steels and heat-resistant steels.

[0079] In the aforementioned implementation scheme, spraying can be used to ensure the uniformity of the coating thickness.

[0080] The coating formed by the anti-corrosion coating used on the metal surface can seal and protect the metal substrate.

[0081] The present invention will be described in more detail below with reference to several embodiments and accompanying drawings, but the embodiments described herein do not constitute a limitation of the present invention.

[0082] Example 1

[0083] This embodiment provides an anti-corrosion coating for marine environments, and the specific preparation steps include:

[0084] 1. Preparation of polyaniline-modified hexagonal boron nitride:

[0085] 200 mL of saturated potassium hydroxide solution was added to a 500 mL beaker, and 180 g of hexagonal boron nitride was added. The mixture was sonicated for 4 h and then magnetically stirred at 3000 r / min for 6 h to form a homogeneous solution. The solution was refluxed in an oil bath at 130 °C for 48 h, cooled and filtered, washed with deionized water until the pH of the solution was neutral, and dried in a vacuum drying oven at 80 °C to obtain hydroxylated hexagonal boron nitride.

[0086] 4.0 g of aniline was weighed and added to 500 ml of a prepared 1.5 mol / L hydrochloric acid solution. The solution was stirred at 1200 rpm to form a homogeneous, transparent solution. Then, 2.5 g of hydroxylated nano-hexagonal boron nitride was weighed and dissolved in 200 ml of deionized water. The solution was ultrasonically dispersed for 2 h. The dispersed nano-hexagonal boron nitride solution was added to the aniline mixture and magnetically stirred for 10 h to form a milky white mixture. Finally, the mixture was stirred in an ice bath at 4 °C, and 5.5 g of hydrogen peroxide aqueous solution (3 wt%) was added dropwise during the stirring process. After stirring for 24 h, the mixture was allowed to stand at 0 °C for 24 h to allow the polyaniline to react and fully polymerize on the surface of the hydroxylated hexagonal boron nitride. The solution after standing was vacuum filtered, washed 8 times each with deionized water and ethanol, dried in a vacuum drying oven at 80 °C for 24 h, and ground to obtain a dark green product, which is polyaniline-modified hexagonal boron nitride.

[0087] 2. Preparation of modified graphene slurry:

[0088] 50g of high-purity graphite was added to 100mL of a 5mol / L concentrated sulfuric acid and saturated potassium permanganate solution. The solution was kept at 30℃ and magnetically stirred at 300r / min for 24h. After washing five times with 800mL of deionized water, graphene oxide was obtained. 5g of phytic acid, 20g of graphene oxide, and 200mL of deionized water were weighed and mixed evenly. The mixture was subjected to a condensation polymerization reaction in an 80℃ water bath for 12h. Then, the solid and liquid phases were separated to obtain phytic acid-modified graphene slurry.

[0089] 3. Preparation of anti-corrosion coatings:

[0090] Add 0.5g modified graphene slurry, 0.5g bentonite, 0.5g efka4010 dispersant, 15g xylene and 25g talc to 40g epoxy resin E20 (Nan Ya Epoxy Resin (Kunshan) Co., Ltd.) in sequence. Stir at 3000r / min for 30min in the order of light to heavy, grind to a fineness of 25μm, filter and package to obtain component A.

[0091] Add 5g xylene and 15g polyaniline-modified hexagonal boron nitride to 30g polyamide curing agent, stir at 500r / min for 3min, filter, and package to obtain component B;

[0092] Mix component A and component B in a 2:1 ratio and stir until homogeneous to obtain a marine anti-corrosion coating. Apply the coating directly to the surface of a rusted carbon steel substrate and control the film thickness to 100±10μm to obtain a modified epoxy coating with corrosion resistance, salt spray resistance and strong adhesion.

[0093] The coating prepared by the above method was subjected to film performance testing. The cross-cut adhesion was grade 0, the flexibility was 2 mm, and the salt spray resistance was 3000 h. The basic performance parameters of the coating film prepared in this embodiment are shown in Table 1.

[0094] Performance characterization:

[0095] Figure 2 The infrared spectra of boron nitride (BN), hydroxylated boron nitride (BN-OH), polyaniline (PANI), and polyaniline-modified hexagonal boron nitride (PANI / BN) in Example 1 show that a value of 1400 cm⁻¹ appears in the infrared spectra of both boron nitride and hydroxylated boron nitride. -1 and 810cm -1 The two main peaks are caused by BN bond bending and stretching vibrations, respectively, but in the spectrum of hydroxylated boron nitride, the peak at 3430 cm⁻¹ is also present. -1 A distinct -OH peak was observed, indicating successful hydroxylation modification of nano-hexagonal boron nitride. Meanwhile, in the infrared spectrum of polyaniline, a peak was observed at 1562 cm⁻¹. -1 This corresponds to the C=C stretching vibration of the quinone ring at 1480 cm⁻¹. -1 The characteristic peak at 1300 cm⁻¹ corresponds to the C=C tensile vibration of the benzene ring. -1 The position corresponds to the aromatic amine skeleton. The coexistence of benzene and quinone rings indicates that aniline has successfully undergone oxidative polymerization. A 1400 cm⁻¹ position also appears in the infrared spectrum of PANI / BN. -1 and 810cm -1 The BN bond bending peak and tensile vibration peak at the point indicate that the in-situ growth and polymerization of polyaniline on the boron nitride surface was successfully achieved through the interaction between aniline and the -OH active sites on the surface of boron nitride.

[0096] Figures 3a-3c The images show scanning electron microscope (SEM) images of undispersed boron nitride (BN), polyaniline (PANI), and polyaniline-dispersed hydroxylated boron nitride (PBN) from Example 1, respectively. As can be seen from the images, undispersed boron nitride exhibits a two-dimensional lamellar structure with significant agglomeration, while pure polyaniline displays a nanorod-like structure. For polyaniline-dispersed hydroxylated boron nitride, a large number of coral-like polyaniline particles accumulate on the surface of hexagonal boron nitride, effectively inhibiting boron nitride agglomeration.

[0097] Example 2

[0098] The difference between this embodiment and Embodiment 1 is that 0.8g of modified graphene slurry is added in step 3, while the other steps are the same.

[0099] The basic performance parameters of the coating film prepared in Example 2 are shown in Table 1.

[0100] Comparative Example 1

[0101] This comparative example uses the method described in Example 1, except that in step 3, during the preparation of curing agent component B, the addition of 15g of polyaniline-modified hexagonal boron nitride is replaced by the addition of 15g of hexagonal boron nitride. The basic performance parameters of the paint film prepared in Comparative Example 1 are shown in Table 1.

[0102] Comparative Example 2

[0103] This comparative example uses the method described in Example 1, except that in step 3, during the preparation of curing agent component B, 15g of polyaniline-modified hexagonal boron nitride is replaced by 15g of talc. The basic performance parameters of the paint film prepared in Comparative Example 2 are shown in Table 1.

[0104] Comparative Example 3

[0105] This comparative example uses the method described in Example 1, except that in step 3, 0.5g of modified graphene slurry is added to component A of the main agent to replace the addition of 0.5g of graphene slurry. The basic performance parameters of the coating film prepared in Comparative Example 2 are shown in Table 1.

[0106] Comparative Example 4

[0107] This comparative example uses the method described in Example 1, except that in step 3, 0.5g of modified graphene slurry is not added to component A of the main agent, but 25.5g of talc is added. The basic performance parameters of the coating film prepared in Comparative Example 2 are shown in Table 1.

[0108] Comparative Example 5

[0109] This comparative example uses the method described in Example 1, except that in step 3, during the preparation of curing agent component B, the addition of 15g of polyaniline-modified hexagonal boron nitride is replaced by the addition of 15g of polyaniline (PANI). The basic performance parameters of the coating film prepared in Comparative Example 2 are shown in Table 1.

[0110] See Figure 4 The image shows the potentiodynamic polarization curves of the coating prepared in Example 1 of this invention after curing a paint film on Q235 carbon steel and immersing it in a 3.5wt% NaCl solution for 48 hours. The dry film thickness of the paint film is 50 micrometers. Potentiodynamic polarization curve tests were then performed, and the results were compared with those of an epoxy coating and epoxy coatings prepared in the comparative example. (See [reference]). Figure 4 A comparison of pure epoxy coating (EP), epoxy coating with 0.5% PANI (PANI / EP), epoxy coating with 0.5% BN (BN / EP), and epoxy coating with 0.5% PANI / BN (PANI / BN / EP) shows that the PANI / BN / EP coating has the lowest self-corrosion current density and the best protective performance for Q235 carbon steel.

[0111] See Figures 5a-5c The images show salt spray resistance photos of the coating systems: pure epoxy coating (EP), epoxy coating with 0.5% BN (BN / EP), and epoxy coating with 0.5% PANI / BN (PANI / BN / EP). Figures 5a-5c In the image (left side is a photo before the salt spray test, right side is a photo after the salt spray test), it can be seen that the epoxy coating with 0.5% PANI / BN remained intact after 120 hours, while the metal substrate with added unmodified hexagonal boron nitride had already rusted, and the pure epoxy coating had the most severe rust.

[0112] Table 1. Performance test comparison of the embodiments and comparative examples.

[0113]

[0114]

[0115] Referring to Table 1, compared with Comparative Example 2, hexagonal boron nitride was added directly to the epoxy coating without undergoing polyaniline chemical modification, resulting in reduced cross-cut adhesion, salt spray resistance, and water resistance, and its impact resistance did not reach 50 kg cm.

[0116] Compared with Comparative Examples 2 and 5, Example 1 demonstrates that adding polyaniline-modified hexagonal boron nitride to the epoxy coating can improve the adhesion of the paint film and significantly enhance the salt spray resistance and water resistance of the epoxy paint film.

[0117] Compared with Comparative Example 3, Example 1 shows that adding phytic acid-modified graphene slurry to the epoxy coating can improve salt spray resistance and water resistance, and can also be applied to rusted carbon steel substrates with good adhesion.

[0118] Example 1, compared with Comparative Example 4, demonstrates that graphene can improve the salt spray resistance and water resistance of the coating film.

[0119] Clearly, the performance test results of Example 1 and Comparative Examples 1-5 show that by using the technical solution of the present invention, adding polyaniline-modified hexagonal boron nitride and phytic acid-modified graphene slurry to epoxy resin can significantly improve the salt spray resistance and water resistance of the coating material, and it has good adhesion to rusted carbon steel.

[0120] It should be understood that the above embodiments are merely illustrative of the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A graphene anti-corrosion coating, characterized in that: By weight, it includes 20-40 parts epoxy resin, 25-50 parts polyaniline-modified hexagonal boron nitride, 20-50 parts anti-corrosion filler, 0.2-1.0 parts modified graphene slurry, 1-5 parts additives, 10-20 parts organic solvent, and 20-40 parts curing agent. The polyaniline-modified hexagonal boron nitride is obtained by polymerization of aniline and hydroxylated hexagonal boron nitride in ammonium persulfate solution; The polymerization reaction includes a dehydration condensation reaction between the amino group in aniline and the hydroxyl group in hexagonal boron nitride, while the aniline monomer self-polymerizes to form polyaniline; during the polymerization reaction, polyaniline is grafted onto the surface of hexagonal boron nitride to inhibit the aggregation of hexagonal boron nitride. The polyaniline-modified hexagonal boron nitride has a two-dimensional lamellar structure. The amino groups on the surface of the polyaniline-modified hexagonal boron nitride undergo a curing reaction with the epoxy groups of the epoxy resin, crosslinking to form a paint film with a dense structure. The modified graphene slurry comprises mixing phytic acid, graphene oxide, and deionized water, performing a hydrolysis polymerization reaction at 80–90°C for 10–12 hours, and then separating the solid and liquid components to obtain the modified graphene slurry. The curing agent is one or more of polyamide, polyetheramine, and alicyclic amine; The preparation method of the graphene anti-corrosion coating includes the following steps: S1. Provides polyaniline-modified hexagonal boron nitride: After the hydroxylated hexagonal boron nitride is evenly dispersed in an alkaline solution, aniline is added and stirred to form a milky white mixture; An oxidant is added dropwise to polymerize aniline on the surface of the hydroxylated hexagonal boron nitride to form the polyaniline-modified hexagonal boron nitride. S2. Preparation of anti-corrosion coatings: Modified graphene slurry, additives, first solvent and anti-corrosion filler are added to epoxy resin in sequence, stirred, ground and filtered to obtain the first component; The second component is obtained by adding a second solvent and polyaniline-modified hexagonal boron nitride to the curing agent, stirring, grinding, and filtering. The anti-corrosion coating is obtained by mixing the first component and the second component and then allowing them to mature.

2. The graphene anti-corrosion coating as described in claim 1, characterized in that: Hydroxylated hexagonal boron nitride was prepared by ultrasonication of hexagonal boron nitride in a concentrated alkaline solution; The particle size of the polyaniline-modified hexagonal boron nitride is 5–30 μm; The concentrated alkaline solution is a saturated sodium hydroxide solution and / or a saturated potassium hydroxide solution; And / or, the conditions for the polymerization reaction include a reaction temperature of 0 to 4°C.

3. The graphene anti-corrosion coating as described in claim 2, characterized in that: The particle size of the polyaniline-modified hexagonal boron nitride is 5–15 μm.

4. The graphene anti-corrosion coating as described in claim 2, characterized in that: The particle size of the polyaniline-modified hexagonal boron nitride is 10 μm.

5. The graphene anti-corrosion coating as described in claim 1, characterized in that: The graphene oxide is prepared by oxidation of high-purity graphite in concentrated sulfuric acid and saturated potassium permanganate solution.

6. The graphene anti-corrosion coating as described in claim 5, characterized in that: The conditions for the oxidation reaction include a reaction temperature of 30–60°C and a reaction time of 24–48 h.

7. The graphene anti-corrosion coating as described in claim 1, characterized in that: The epoxy resin includes one or a combination of E20, E44 and E51.

8. The graphene anti-corrosion coating as described in claim 1, characterized in that: The corrosion-resistant filler includes one or more of the following: talc powder, precipitated barium sulfate, and ferrophosphorus powder.

9. The graphene anti-corrosion coating as described in claim 1, characterized in that: The additives include one or more of the following: efka4010 dispersant, bentonite, and fumed silica.

10. The graphene anti-corrosion coating as described in claim 1, characterized in that: The solvent is one or a combination of acetone, xylene, and n-butanol.

11. The graphene anti-corrosion coating as described in claim 1, characterized in that: The amount of the additive is 1 wt% to 2 wt%.

12. The graphene anti-corrosion coating as described in claim 1, characterized in that, In S1, the preparation of the hydroxylated hexagonal boron nitride includes: adding hexagonal boron nitride to a saturated concentrated alkaline solution, reacting with ultrasound, and then drying to obtain hydroxylated hexagonal boron nitride.

13. The graphene anti-corrosion coating according to claim 12, characterized in that, The dispersion method of the hydroxylated hexagonal boron nitride includes: adding the hydroxylated hexagonal boron nitride to a saturated concentrated alkaline solution and sonicating for 2-5 hours, stirring magnetically at 3000 r / min for 2-6 hours to form a homogeneous solution, and refluxing in an oil bath at 130°C for 48 hours. The resulting solution was cooled and filtered, washed with deionized water until the pH of the solution was neutral, and dried in a vacuum drying oven at 80°C to obtain the dispersed hydroxylated hexagonal boron nitride.

14. The graphene anti-corrosion coating according to claim 1, characterized in that, The polymerization reaction involves adding an oxidant dropwise under stirring conditions in an ice bath at 0–4°C, stirring for 12–24 h, and then allowing it to stand at 0–4°C for 24 h to allow aniline to polymerize on the surface of the hydroxylated hexagonal boron nitride to obtain the hydroxylated hexagonal boron nitride.

15. The graphene anti-corrosion coating according to claim 14, characterized in that, The oxidant includes at least one of ammonium persulfate solution, hydrogen peroxide (H2O2) solution, or chlorate solution.

16. The graphene anti-corrosion coating according to claim 14, characterized in that, The concentration of the oxidant in the solution is 3-5 wt%.

17. The graphene anti-corrosion coating according to claim 14, characterized in that, The mass ratio of aniline, the oxidant, and the hydroxylated hexagonal boron nitride is (3-5):(4.5-6.5):(1.5-5.5).

18. The graphene anti-corrosion coating according to claim 1, characterized in that, The stirring speed in the preparation of the first component is 3000 r / min, and the stirring time is 30-50 min; The fineness of the first component is ≤30 micrometers; The stirring speed in the preparation of the second component is 500 r / min, and the stirring time is 3-5 min.

19. The application of the anti-corrosion coating according to any one of claims 1-18 in the corrosion protection of metal surfaces in a marine environment.

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